Authoritative jempo dating remarkable, rather amusing
Posted in Dating
Tuesday, April 5, Science Brain and Behavior contiuned Opiates, such as morphine, after all, are not naturally occurring brain chemicals. This question was answered by Scottish pharmacologists John Hughes and Hans Kosterlitz , who identified two short peptides that had opioid properties and appeared to be neurotransmitters see Figure They called these opiate-like transmitters endorphins, an abridgement of the phrase endogenous morphine-like substances. We now know that there are endorphin-containing neurons in many brain regions and that morphine is similar enough to endorphins to mimic their action in the brain. Researchers have extensively studied whether endorphins can be used as drugs to relieve pain.
Information on time, temperature and bacterial growth is collected at the wholesaler, the transporter, the grocery store and in your refrigerator. This information is dynamic and could, for example detect if the temperature has been too high somewhere in the supply chain leading to a shortened shelf life.
In the store the information is transferred to the digital price tags on the display case. At your house, point the mobile phone against the chip and using an app, you can read the last time you have to cook the raw material. If you left the grocery bag in the car for an hour on a hot summer day, the system will shorten the expiration date. The service can be combined with tips on recipes that fit the raw material.
We know that there some people still make a new idea to manage the waste to increase the shelf life of foods. It is important to keep an eye on the temperature and other parameters of the entire cold chain they are working to develop a technology called dynamic labelling.
That until the humans can life healthy and nicely and about this article can make us effort our self to life more health. Email This BlogThis! Share to Twitter Share to Facebook. Direction: Questions 41 to 50 are passage completion.
Read the passage. A word or Apa yang menyebabkan UKM dapat bertahan dalam badai krisis? Incomplete dialog 16 - 30 Yesterday she came to my apartment and asks to borrow some sugar. She wished she were older o Then, core the apples and cop them, After that Total Pageviews. Popular Tags Blog Archives hero Can I help you? Powered by Blogger.
The distribution of the different glutamate receptor subtypes in the brain varies from region to region. Kainate receptors are especially numerous in the hippocampus. If domoic acid reaches these receptors in high enough concentrations, it overexcites the receptors, initiating a series of biochemical reactions that results in the death of the postsynaptic neuron.
Consequently, domoic acid is more toxic to the hippocampus than it is to other brain regions. Figure shows a section through the brain of a rat that has been given an injection of domoic acid. The brain is colored with a silver stain that accumulates in damaged neurons. Tissue in the hippocampus exhibits the greatest amount of damage, although there is also sparse damage elsewhere in the brain. It may seem surprising that a chemical that mimics a neurotransmitter can cause memory problems and brain damage.
To understand how domoic acid can act as a neurotoxin requires that we temporarily turn to a different story, that of monosodium glutamate MSG. The plot of this second story eventually links up with the plot of the domoic acid story. In the late s, there were many reports that MSG, a salty-tasting, flavorenhancing food additive, produced headaches in some people. In the process of investigating why this effect happened, scientists placed large doses of MSG on cultured neurons and noticed that the neurons died.
Subsequently, they injected monosodium glutamate into the brains of experimental animals, where it also produced neuron death. Domoic acid Kainic acid Figure Neurotoxicity Domoic acid damage is not restricted to the hippocampus; it can be seen to a lesser extent in many other brain regions.
Micrograph from NeuroScience Associates. It turned out that it is. This finding suggested that a large dose of any substance that acts like glutamate might be toxic. Now the toxic action of domoic acid can be explained. Domoic acid in large quantities excessively stimulates the glutamate receptors of certain brain cells, and this activation is related to neuronal death.
Glutamate-receptor activation results in an influx of Ca2! Such apoptosis, as you learned in Chapter 6, may be a mechanism by which the brain disposes of sick cells.
This is not to say that people should totally avoid MSG, which is similar in chemical structure to glutamate. Only very large doses of these substances are harmful, just as glutamate itself is not harmful except in large doses.
Glutamate, in fact, is an essential chemical in the body. Recent findings show that we even have taste-bud receptors for glutamate on our tongues, in addition to our receptors for sweet, salty, bitter, and sour. The glutamate taste-bud receptor, mGluR4, most likely functions to encourage us to eat foods containing glutamate, especially high-protein foods such as meat. Clearly, glutamate in doses typically found in food is required by the body and is not toxic.
Only excessive doses of glutamate or its analogues cause harm. Are any of them potentially harmful? The answer is not always easy to determine, as Una McCann and her coworkers found in their review of research. For one thing, there is the problem of sorting out the effects of the drug itself from the effects of other factors related to taking the drug.
For instance, although chronic alcohol use can be associated with damage to the thalamus and limbic system, producing severe memory disorders, it is not the alcohol itself that seems to cause this damage but rather related complications of alcohol abuse, including vitamin deficiencies due to poor diet.
For example, not only do alcoholics obtain reduced amounts of thiamine vitamin B1 in their diets, but alcohol also interferes with the absorption of thiamine by the intestine.
Thiamine plays a vital role in maintaining cell-membrane structure. Similarly, there are many reports of people who suffer some severe psychiatric disorder subsequent to their abuse of certain recreational drugs, but, in most cases, it is difficult to determine whether the drug initiated the condition or just aggravated an existing problem.
It is also hard to determine exactly whether the drug itself or some contaminant in the drug is related to a harmful outcome. But the marijuana plant contains at least chemicals, 60 or more of which are structurally related to its active ingredient tetrahydrocannabinol.
Clearly, it is almost impossible to determine whether the psychotic attacks are related to THC or to some other ingredient contained in marijuana or to aggravation of an existing condition. There is growing evidence that some recreational drugs can cause brain damage and cognitive impairments. MDMA, also called ecstasy, is a widely used synthetic amphetamine. For years, he had been selectively breeding a particularly potent strain of marijuana in anticipation of the day when it would be legalized.
One evening, R. Convinced that he was being manipulated by a small computer that had been implanted into his brain when he was 7 years old, he confided in a close friend, who urged him to consult a doctor.
He also claimed that all the other children who participated in the experiment had been murdered. The doctor told R. The records of the study had long since been destroyed. The delusion seemed completely compartmentalized in R.
When asked why he could no longer fly, he intently recounted the story of the implant and the murders, asserting that its truth had cost him the medical certification needed for a license. Then he happily discussed other topics in a normal way. In some cases, this loss of contact is so severe and the capacity to respond to the environment is so impaired and distorted that the person can no longer function in the world.
People in a state of psychosis may experience hallucinations false sensory perceptions or delusions false beliefs or they may withdraw into a private world isolated from people and events around them. A variety of drugs can produce psychosis, including LSD, amphetamine, cocaine, and, as shown by this case, marijuana. The active ingredient in marijuana is Dtetrahydrocannabinol THC. At low doses, THC has mild sedativehypnotic effects, similar to those of alcohol.
At high doses, it can produce euphoria and hallucinations. The marijuana that R. Humans have used hemp for thousands of years to make rope, paper, cloth, and a host of products. And marijuana has beneficial medical effects: THC alleviates nausea and vomiting associated with chemotherapy in cancer and AIDS patients, controls the brain seizures symptomatic of epilepsy, reduces intraocular pressure in patients with glaucoma, and relieves the symptoms of some movement disorders.
THC may mimic a naturally occurring substance called anandamide, which acts on a THC receptor that naturally inhibits adenyl cyclase, part of one of the second-messenger systems active in sensitization see Chapter 5.
Henquet et al. There is no evidence that marijuana use produces brain damage. It is possible that R. Furthermore, marijuana contains about compounds besides THC, any of which could trigger psychotic symptoms. Approximately 10 years after his initial attack, R. Cannabis sativa is an annual herb that reaches a height between 3 and 15 feet. Hemp grows in a wide range of altitudes, climates, and soils and has myriad practical uses.
Memory impairments have been reported in users of MDMA, which may be a result of similar neuronal damage Morgan, Answering this question is complicated by the fact that many MDMA users have also used other drugs. In addition, the types of anatomical analysis used with other animals cannot be used with humans. The finding that MDMA can be toxic to neurons has led to investigations into whether amphetamine itself also is toxic.
The results of studies in rodents have shown that high doses of amphetamine can result in the loss of DA terminals. One form of amphetamine-methamphetamine, one of the most widely used recreational drugs-has been found to produce both brain damage, as revealed by brain-imaging studies, and impaired memory performance, as indicated by neuropsychological tests Thompson et al. The subjects used in this study had been using the drug for about 10 years, and so the study does not produce evidence that a single or only a few uses of the drug have similar detrimental brain and behavioral effects but that in some way repeated use can permanently damage neurons.
The psychoactive properties of cocaine are similar to those of amphetamine, and its possible deleterious effects have been subjected to intense investigation. The results of many studies show that cocaine use is related to the blockage of cerebral blood flow and other changes in blood circulation.
Whether cocaine causes these abnormalities or aggravates preexisting conditions is not clear. Its use was discontinued after about half of treated patients were found to display psychotic symptoms for as long as a week after coming out of anesthesia. PCP users report perceptual changes and the slurring of speech after small doses, with high doses producing perceptual disorders and hallucinations. Some of the symptoms can last for weeks. The mechanisms by which PCP produces enduring behavioral changes are unknown, but John Olney and his colleagues reported that, after rats are given a related drug MKthey undergo abnormal changes in neurons, as well as loss of neurons.
This finding suggests that the altered behavior of PCP users may be related to neuron damage. Some drugs that produce altered perceptual experiences and changes in mood do not appear linked to brain damage. For instance, LSD, a drug believed to act on serotonergic neurons, produces hallucinations but does not seem to cause enduring brain changes in rats.
Similarly, although opiates produce mood changes, the results of longterm studies of opiate users have not revealed persistent cognitive impairments or brain damage. Behavior may change in a number of ways with the repeated use of a drug. These changes include tolerance, in which a behavioral response decreases; sensitization, in which a behavioral response increases; and substance dependence, or addiction, in which the desire to use a drug increases as a function of experience with it. Today, many researchers believe that it is not so much avoidance of withdrawal symptoms that keeps people using a drug as it is a set of powerful learned incentives associated with drug taking.
Disinhibited behavior while a person is ! McCann, K. Lowe, and G. Ricaurte,The Neurologist, 3, p. Berthold performed the first experiment to demonstrate the existence and function of hormones, chemicals released by an endocrine gland.
Endocrine glands are cell groups in the body that secrete hormones into the bloodstream to circulate to a body target and affect it.
Berthold removed the testes of a rooster and found that the rooster no longer crowed; nor did it engage in sexual or aggressive behavior. The rooster began crowing and displaying normal sexual and aggressive behavior again. That chemical, we now know, is testosterone, the sex hormone secreted by the testes and responsible for the distinguishing characteristics of the male. The effect that Berthold produced by reimplanting the testis can be mimicked by administering testosterone to a castrated rooster, or capon.
The hormone is sufficient to make the capon behave like a rooster with testes. Testosterone also initiates changes in the size and appearance of the mature male body. Hormones, like other drugs, are used to treat or prevent disease. People take synthetic hormones as a replacement therapy because of the removal of glands that produce those hormones or because of their malfunction.
People also take hormones, especially sex hormones, to counteract the effects of aging, and they take them to increase physical strength and endurance and to gain an advantage in sports.
As many as hormones in the human body are classified as either steroids or peptides.
Steroid hormones are synthesized from cholesterol and are lipid fat soluble. Steroids diffuse away from their site of synthesis in glands, including the gonads, adrenal cortex, and thyroid, easily crossing the cell membrane.
Hormones fall into one of three main groups with respect to their behavioral functions, and they may function in more than one of these groups: 1. Hormones that maintain homeostasis, a state of internal metabolic balance and regulation of physiological systems in an organism, form one group. Gonadal sex hormones control reproductive functions.
They instruct the body to develop as male e. Scientists are still investigating the potential deleterious effects on the brain of different psychedelic drugs. So far, their findings have been mixed, with some drugs producing brain damage and others apparently not doing so. Steroid hormone. Fat-soluble chemical messenger synthesized from cholesterol.
Peptide hormone. State of internal metabolic balance and regulation of physiological systems in an organism. Gonadal sex hormone. One of a group of hormones, such as testosterone, that control reproductive functions and bestow sexual appearance and identity as male or female. Normal rooster Rooster who has had gonads removed CH Hormones activated in psychologically challenging events or emergency situations prepare the body to cope by fighting or fleeing.
Glucocorticoids cortisol and corticosterone are examplesa group of steroid hormones secreted in times of stress, are important in protein and carbohydrate metabolism, controlling sugar levels in the blood and the absorption of sugar by cells. Hierarchical Control of Hormones Figure shows that the control and action of hormones are organized into a fourlevel hierarchy consisting of the brain, the pituitary and remaining endocrine glands, and the target cells affected by the hormones.
As detailed in Chapter 11, the brain, mainly the hypothalamus, releases neurohormones that stimulate the pituitary to pump hormones into the circulatory system. The pituitary hormones, in turn, influence the endocrine glands to release appropriate hormones into the bloodstream.
These hormones then act on various targets in the body, also providing feedback to the brain about the need for more or less hormone release. Although many questions remain about how hormones produce complex behavior, they not only affect body organs but also target the brain and activating systems there. Almost every neuron in the brain contains receptors on which various hormones can act. In addition to influencing sex organs and physical appearance in a rooster, testosterone may have neurotransmitter-like effects on the brain cells that it targets, especially neurons that control crowing, male sexual behavior, and aggression.
In these neurons, testosterone is transported into the cell nucleus, where it activates genes. Thus, the rooster receives not only a male body but a male brain as well.
One of a group of steroid hormones, such as cortisol, secreted in times of stress; important in protein and carbohydrate metabolism. In response to sensory stimuli and cognitive activity, the hypothalamus produces neurohormones that enter the anterior pituitary through veins and the posterior pituitary through axons. On instructions from these releasing hormones, the pituitary sends hormones into the bloodstream to target endocrine glands. In response to pituitary hormones, the endocrine glands release their own hormones that stimulate target organs, including the brain.
In response, the hypothalamus and the pituitary decrease hormone production. In subsequent chapters, we will take up the story of hormones again, as we examine motivation and the relation between learning and memory. An appropriate balance of sugars, proteins, carbohydrates, salts, and water is required in the bloodstream, in the extracellular compartments of muscles, in the brain and other body structures, and within all body cells.
As children or adults, at rest or in strenuous work, when we have overeaten or when we are hungry, to survive, we need a relatively constant internal environment. Thus, the homeostatic hormones are essential to life itself. Insulin is a homeostatic hormone. The normal concentration of glucose in the bloodstream varies between 80 and milligrams per milliliters of blood. One group of cells in the pancreas releases insulin, which causes blood sugar to fall by instructing the liver to start storing glucose rather than releasing it and by instructing cells to increase glucose uptake.
The resulting decrease in glucose then decreases the stimulation of pancreatic cells so that they stop producing insulin. Diabetes mellitus is caused by a failure of these pancreatic cells to secrete enough or any insulin. As a result, blood-sugar levels can fall hypoglycemia or rise hyperglycemia. In hyperglycemia, blood-glucose levels rise because insulin does not instruct cells of the body to take up that glucose.
Consequently, cell function, including neural function, can fail through glucose starvation, even in the presence of high levels of glucose in the blood. In addition, chronic high blood-glucose levels cause damage to the eyes, kidneys, nerves, heart, and blood vessels.
In hypoglycemia, inappropriate diet can lead to to low blood sugar, which can be so severe as to cause fainting. Gonadal Hormones We are prepared for our adult reproductive roles by the gonadal hormones that give us our sexual appearance, mold our identity as male or female, and allow us to engage in sex-related behaviors.
Sex hormones begin to act on us even before we are born and continue their actions throughout our lives see Chapters 6, 11, and For males, sex hormones produce the male body and male behaviors.
The Y chromosome of males contains a gene called the sex-determining region or SRY gene. If cells in the undifferentiated gonads of the early embryo contain an SRY gene, they will develop into a testes and, if they do not, they will develop into an ovary. In the male, the testes produce the hormone testosterone,which in turn masculinizes the body, producing the male body and genital organs and the male brain.
The organizational hypothesis proposes that actions of hormones during development alter tissue differentiation. Thus, testosterone masculinizes the brain early in life by being taken up in brain cells where it is converted into estrogen by the enzyme aromatase. Estrogen then acts on estrogen receptors to initiate a chain of events that include the activation of certain genes in the cell nucleus.
These genes then contribute to the masculinization of brain cells and their interactions with other brain cells. Proposal that actions of hormones during development alter tissue differentiation; for example, testosterone masculinizes the brain. It might seem surprising that estrogen, a hormone usually associated with the female, masculinizes the male brain. Estrogen does not have the same effect on the female brain, because females have a blood enzyme that binds to estrogen and prevents its entry into the brain.
Hormones contribute to surprising differences in the brain and in cognitive behavior. The male brain is slightly larger than the female brain after corrections are made for body size, and the right hemisphere is somewhat larger than the left in males. The female brain has a higher rate both of cerebral blood flow and of glucose utilization. There are also a number of differences in brain size in different regions of the brain including nuclei in the hypothalamus that are related to sexual function, parts of the corpus callosum that are larger in females, and a somewhat larger language region in the female brain.
Three lines of evidence, summarized by Elizabeth Hampson and Doreen Kimurasupport the conclusion that sex-related cognitive differences result from these brain differences.
These cognitive differences also depend in part on the continuing circulation of the sex hormones. The evidence: 1. The results of spatial and verbal tests given to females and males in many different settings and cultures show that males tend to excel in the spatial tasks and females in the verbal ones.
The results of similar tests given to female subjects in the course of the menstrual cycle show fluctuations in test scores with various phases of the cycle. During the phase in which the female sex hormones estradiol metabolized from estrogen and progesterone are at their lowest levels, women do comparatively better on spatial tasks, whereas, during the phase in which levels of these hormones are high, women do comparatively better on verbal tasks. Tests comparing premenopausal and postmenopausal women, women in various stages of pregnancy, and females and males with varying levels of circulating hormones all provide some evidence that hormones affect cognitive function.
These sex-hormone-related differences in cognitive function are not huge. A great deal of overlap in performance scores exists between males and females. Yet statistically the differences seem reliable. Similar influences of sex hormones on behavior are found in other species. Findings from a number of studies demonstrate that motor skills in female humans and other animals improve at estrus, a time when progesterone levels are high.
Stress Hormones Life is stressful. Stress responses are not only physiological, but also behavioral, and include both arousal and attempts to reduce stress.
A stress response can outlast a stress-inducing incident and may even occur in the absence an obvious stressor. Living with constant stress can be debilitating. Robert Sapolsky uses the vivid image of a hungry lion chasing down a zebra to illustrate the stress response. The chase elicits very different reactions in the two animals, but their physiological stress responses are exactly the same.
The stress response begins when the body is subjected to a stressor, and especially when the brain perceives a stressor and responds with arousal. The response consists of two separate sequences, one fast and the other slow. In addition, the sympathetic division stimulates the medulla on the interior of the adrenal gland to release epinephrine.
The hormone controlling the slow response is the steroid cortisol, a glucocorticoid released from the outer layer cortex of the adrenal gland, as shown on the right side of Figure The cortisol pathway is activated more slowly, taking from minutes to hours.
Cortisol has a wide range of functions, which include turning off all bodily systems not immediately required to deal with a stressor.
For example, cortisol turns off insulin so that the liver starts releasing glucose, thus temporarily producing an increase in energy supply. It also shuts down reproductive functions and inhibits the production of growth hormone. Ending a Stress Response Normally, stress responses are brief. The body mobilizes its resources, deals with the challenge physiologically and behaviorally, and then shuts down the stress response. Just as the brain is responsible for turning on the stress reaction, it is also responsible for turning it off.
Consider what can happen if the stress response is not shut down: The body continues to mobilize energy at the cost of energy storage. Proteins are used up, resulting in muscle wasting and fatigue. Growth hormone is inhibited, and so the body cannot grow. The gastrointestinal system remains shut down, reducing the intake and processing of food to replace used resources.
The fast-acting pathway primes the body immediately for fight or flight. The immune system is suppressed, contributing to the possibility of infection or disease. Sapolsky argued that the hippocampus plays an important role in turning off the stress response. The hippocampus contains a high density of cortisol receptors, and it has axons that project to the hypothalamus. Consequently, the hippocampus is well suited to detecting cortisol in the blood and instructing the hypothalamus to reduce blood-cortisol levels.
There may, however, be a more insidious relation between the hippocampus and blood-cortisol levels. Sapolsky and his coworkers observed wild-born vervet monkeys that had become agricultural pests in Kenya and had therefore been trapped and caged. They found that some of the monkeys became sick and died of a syndrome that appeared to be related to stress.
Those that died seemed to have been subordinate animals housed with particularly aggressive, dominant monkeys. Autopsies showed high rates of gastric ulcers, enlarged adrenal glands, and pronounced hippocampal degeneration that was especially noticeable in the CA3 region of the hippocampus. The hippocampal damage may have been due to prolonged high cortisol levels produced by the unremitting stress of being caged with the aggressive monkeys. Cortisol levels are usually regulated by the hippocampus, but, if these levels remain elevated because a stress-inducing situation continues, the high cortisol levels eventually damage the hippocampus.
The damaged hippocampus is then unable to do its work of reducing the level of cortisol. Thus, a vicious cycle is set up in which the hippocampus undergoes progressive degeneration and cortisol levels are not controlled. Remember that domoic acid, the agent in mussel poisoning, damages the hippocampus because it mimics the effects of high levels of the neurotransmitter glutamate. Prolonged high cortisol levels may damage the hippocampus by mimicking the excitotoxicity of domoic acid.
By stimulating some hippocampal cells, cortisol causes them to release glutamate. If this stimulation is excessive, the sustained release of glutamate may be toxic to other hippocampal cells.
The cycle of prolonged stress, elevated cortisol levels, and damage to the hippocampus is illustrated in Figure Because stress-response circuits in monkeys are very similar to those in humans, the possibility exists that excessive stress in humans also can lead to damaged hippocampal neurons.
Because the hippocampus is thought to play a role in memory, stress-induced damage to the hippocampus is postulated to result in impaired memory as well as in posttraumatic stress disorder PTSD. Posttraumatic stress disorder is characterized by physiological arousal symptoms related to recurring memories and dreams related to a traumatic event-for months or years after the event. People with PTSD feel as if they are reexperiencing the trauma, and the accompanying physiological arousal enhances their belief of impending danger.
Research has not led to a clear-cut answer concerning whether the cumulative effects of stress damage the human hippocampus. That such different results can be obtained in what appear to be similar studies can be explained in a number of ways. First, how much damage to the hippocampus must occur to produce a stress syndrome is not certain.
Second, brain-imaging techniques may not be sensitive to subtle changes in hippocampal cell function or moderate cell loss. Third, large individual and environmental differences influence how people respond to stress. Finally, preexisting ! CHAPTER 7 off cortisol secretion Decreased ability to shut Destruction of hippocampal neurons Fewer hippocampal neurons More cortisol secretion Prolonged stress Figure Vicious Cycle Unrelieved stress promotes an excessive release of cortisol that causes damage to neurons in the hippocampus.
The damaged neurons are unable to detect cortisol and therefore cannot signal the adrenal gland to stop producing it. The result is a feedback loop in which the enhanced secretion of cortisol further damages hippocampal neurons. Posttraumatic stress disorder PTSD.
Syndrome characterized by physiological arousal symptoms related to recurring memories and dreams related to a traumatic event-for months or years after the event. Humans are long lived and have many life experiences that complicate simple extrapolations from a single stressful event. Nevertheless, changes to the brain induced by prolonged stress complicate the treatment of stress-related disorders and suggest that it is important to treat stress so that brain and body injury do not occur.
Psychoactive drugs-substances that alter mood, thought, or behavior-produce their effects by acting on receptors or on chemical processes in the nervous system, especially on processes of neural transmission at synapses. They act either as agonists to stimulate neuronal activity or as antagonists to depress it. Psychopharmacology is the study of drug effects on the brain and behavior. How does a drug enter the body, reach its target, and leave the body? Drugs, chemicals taken to bring about some desired change in the body, are administered by mouth, by inhalation, by absorption through the skin, and by injection.
To reach a target in the nervous system, a drug must pass a through numerous barriers posed by digestion, dilution, the blood-brain barrier, and cell membranes. Drugs are diluted by body fluids as they pass through successive barriers,metabolized in the body, and excreted through sweat glands and in feces, urine, breath, and breast milk. How do people respond to drugs?
A drug does not have a uniform action on every person. Physical differences-in body weight, sex, age, or genetic background-influence the effects of a given drug on a given person, as do behaviors, such as learning, and environmental context.
How are psychoactive drugs classified? Psychoactive drugs are classified into seven groups according to their major behavioral effects, as sedative hypnotics and antianxiety agents, antipsychotic agents, antidepressants,mood stabilizers, narcotic analgesics, psychomotor stimulants, and stimulants that have psychedelic and hallucinogenic effects.
Each group contains natural or synthetic drugs or both, and they may produce their actions in different ways. How does the repeated use of drugs and their use in different contexts affect behavior? A common misperception about drugs is that their actions are specific and consistent. But the body and brain rapidly become tolerant to many drugs, and so the dose must be increased to produce a constant effect.
Alternatively, people may become sensitized to a drug, in which case the same dose produces increasingly greater effects. Hormones are hierarchically controlled by sensory experiences, the brain, the pituitary gland, and the endocrine glands that produce and secrete them through the bloodstream to targets throughout the body. Because these hormones often have such widespread targets, traveling through the bloodstream is an effective way to deliver their chemical messages.
Addiction develops in a number of stages as a result of repeated drug taking. Initially, drug taking produces pleasure, or liking, but, with repeated use, it becomes conditioned to associated objects, events, and places.
Eventually, those conditioned cues acquire incentive salience, causing the drug user to seek them out, which leads to more drug taking. The subjective experience associated with prominent cues and drug seeking promotes craving for the drug. As addiction proceeds, the subjective experience of liking decreases while that of wanting increases. Does the effect of a drug depend on the drug-taking situation? The influence of drugs on behavior varies widely with the situation and as a person learns appropriate drugrelated behaviors.
Some drugs, such as alcohol, can produce behavioral myopia such that a person is primarily influenced by prominent cues in the environment. These cues may encourage the person to act in ways in which he or she would not normally behave. Considering how many people use tobacco, drink alcohol, use recreational drugs, or abuse prescription drugs, it is probably rare to find someone who has not used a drug when it was available.
Nevertheless, some people do seem vulnerable to drug use and addiction. Individual differences in genetics could be influential, but drug availability and peer influences are likely more influential. Because the neural mechanisms that are implicated in addiction are the same neural systems responsible for wanting and liking more generally, anyone is likely to be a potential drug abuser.
Can the repeated use of drugs produce brain damage? Excessive use of alcohol can be associated with damage to the thalamus and hypothalamus, but the cause of the damage is poor nutrition rather than the direct actions of alcohol. Cocaine can harm brain circulation, producing brain damage by reduced blood flow or by bleeding into neural tissue. Psycedelic drugs such as marijuana and LSD can be associated with psychotic behavior, but whether this behavior is due to the direct effects of the drugs or to the aggravation of preexisting conditions is not clear.
What are hormones? Steroid and peptide hormones are produced by endocrine glands and circulate in the bloodstream to affect a wide variety of targets. Hormones are under the hierarchical control of sensory events, the brain, the pituitary gland, and the endocrine glands, which all interact to regulate hormone levels. Homeostatic hormones regulate the balance of sugars, proteins, carbohydrates, salts, and other substances in the body.
Sex hormones regulate the physical features and behaviors associated with reproduction and the care of offspring. Failures to turn stress responses off after a stressor has passed can contribute to susceptibility to posttraumatic stress disorder and other psychological and physical diseases.
Describe how the blood-brain barrier works. Describe the seven categories of drugs. Distinguish between the dependency hypothesis and the wanting-and-liking theory of drug addiction.
Distinguish between the disinhibition, time-out, and alcohol-myopia explanations of behavior under the effects of drugs. Describe the hierarchical control of hormones. Describe some proposed effects of prolonged stress responses on the body and brain.
Discuss contemporary views of how drugs can influence our behavior. Because many drugs work by affecting the function of synapses, the effect that they produce must be similar to some naturally produced behavior. Discuss this idea in relation to a drug of your choice. Behavioral endocrinology. A book consisting of a number of chapters on hormones, each written by an expert. Cooper, J.
The biochemical basis of neuropharmacology.
New York: Oxford University Press. A summary of how synapses respond to drugs. Consists of a general description of how synapses work and summarizes the structure and function of a number of different neurochemical synapses.
Feldman, R. Principles of neuropsychopharmacology. Sunderland, MA: Sinauer. A comprehensive but advanced book about how various drugs affect the nervous system. An outstanding reference on contemporary neuropsychopharmacology.
Julien, R. A primer of drug action. New York:Worth Publishers. As the name suggests, this book is an extremely readable introduction to how drugs affect the nervous system and produce changes in behavior, mood, and cognitive function.
Sapolsky, R. New York:W. Freeman and Company. A readable popular summary of everything you would like to know about stress. Tune the frequency at the time that the station is normally on, and keep doing this until the moment comes that you work the rare one. He may be booming in due to freak conditions or he may be very weak in the noise. But keep trying. EDT, or any other time. Tlie beauty of this clock is that it will run for almost two years on a standard C-size flashlight battery.
This handsome clock will look beautifut in your shack and it will help you meet your nets and skeds. The FPM features all solid- state construction with only two tubes and modular construction throughout.
Full coverage of all bands and built-in ac and dc power supplies complement the rig for a great fixed or mobile signaL Hallicrafters Co, Hicks Rd. L S. Membership currently numbersincluding over 40 menv ber societies, and is worldwide with amateurs from some thirty countries represenEed.
The satellite will be placed in a geostationary synchronous orbit. The SYNCART package is designed for emergency communcations, educa- tional training and experiments with small terminal multiple-access com- munications. Illy to get thinp done it would be safe to assume that every- thing will come off as scheduled. It therefore be- hooves each of us to avoid doing things which deprive others of their pleasure.
Do you call a rare or DX station every tune he stops transmit- ting? Do you inquire if the frequency is in use before calling CO or tuning up? Do you make transmissions so long the band folds before you complete one schange?
Do you call CQ so long the prospective contact gets tired of waiting and looks elsewhere?
We have all experienced signals 20, 30 or 40 kHz wide obli- terating a goodly segment of the band. A malfunction can happen to anyone, but all too often the cause is Fred talking to Harvey down the block with his Band Burner VI for the matching linear cranked into satura- tion.
Just like tlie last time Uie band was open, QRM from other stations in QSO ajid tuning up, etc, has become as common as on the lower bands. But il need not be so. Rarely, even during the widest open- ings, does one hear activity above With 4 MHz available.
Would it not be reasonable to assume that all would profit if we were to make better use of the hand during openings? This industrious pair will be operating from a fire tower at 15W fi above sea level during the VHF contest and will be happy to make schedules on kHz. A fair amount of activity from Europe and Africa there also. So 1 checked into them and found a real gold mine of fast and slow scan TV goodies.
Zoom lens, turrents, projec- tion TV systems and much more. The video tape recorders really cauglit my eye. Some were under S4n0!
What possibilities! Coupled with an on-olT timer and TV, you could work up a system to tape favorite TV programs for later view- ing. Our day of dreams is rapidly approachine. Those suffering TV! Doc has had antenna difficulties but promises to be back in full operation shortly. K9SDF is recovering from double hip surgery and expects to be out of the hospital and on hand for all of the spring openings. Very good planning, Gabe! You late night types would do well to turn your beams in the general direc- tion of St.
Louis in theeariy morning hours. This list is not complete in that many ''house" and imported brands are not included, but it does cover a good cross-section of the more popular brands.
See you on fi. Notice first the skewed lines running from the bottom left to the top riglit of the picture. It' the two tape recorders were running at the same speed the lines would be verticaL and not noticeable, except for four very slight 'humps" at the very top of the picture.
The picture starts errati- cally on the right top. A perfect SS fV picture starts tlie first line two thirds of the way across the top. The blank period is the vertical re-tracej Notice the texture of the hair, and the white of the collar this is evidence of a high quality gray scale, Tlie re is a slight light reflection in the center of the left eye, showing the definition a I 20 line slow scan picture is capable of producing.
So the magazine picture is third rate to the original viewed on the screen. Robot Research is busy these days. Their SSTV directory is in the works and should be available verj' soon. If you haven't sent them a postcard yet telling of your SSTV activity better do so right away or you may get left out.
They are also publishing a short SSTV newsletter which is usually available from authorized distributors. Close behind him is Eddie W4MS. The apparatus used as a mixer for these niLasurements uses a micro- scopic version of the cat-whisker diode.
Shades of t! The FCC has respon- ded by opening a new band from to 88], MHz, to be used exclusively for mobile communications. If this plan is implemented, there is going to be quite a haul of VHF surplus FM gear on the market from people evacu- ating to the new band. Base and femitter line widths of one micron allow minimal parasitic reac- tance while still providing maximum power gain at 4 GHz for the MSC Now, that's really moving!
But alas. Not enough articles that are really for a beginner like me, so I've had to go out and buy 73 off the stand. Your 'General Class License Study" is a help for my next step which Fra sure is going to come out on the passing side. Keep up the good work, Guys like me need a mag like Please accept my cojigratulations for your consistent production of a publication that contains useful, auth- oritative articles. These articles are written so they are easily understood without regard to the complexity of their subject matter.
I am interested in your IC applications articles. Gripes 1 Just shelled out one buck for your April issue! It s a catalogue not a magazine! You lost a long- tanding reader!!
But turning 73 into a catalopie, phooey! At Cassehmn? This issue was so great that a few of us got together just to sit and praise it last evening! You really hit the top with this issue! Then they saw amateurs with call plates and learned that the hams paid only about S2. People got mad and wrote their congressmen. Now we wait! I like Alaskans system for ama- teur plates if rumors are correct: SI.
This isn't anything new but what is new is that some group has pushed a bill througli the Senate March 16, boosting the fee to S Tlie bill is Substitute Senate Bill'i believe. If it can happen here it can happen in other states. How have other groups worked to repeal this form of dis- crimination against hanis? Amateurs all over the world must have a quiet chuckle to themselves as they watch the goggle-box and any- thing to do with radio crops up - for the TV-men ALWAYS goof it!
When will the film producers learn to consult an amateur?
Welcome to the best free dating site on the web
December 21,1 wrote Jim Penny at Dycomm and indicated our CD group was in the process of installing a repeater and I wanted information on the Dycomm repeater. We had been considering a Motorola unit. Two months passed, we had our money in our hands, but no word from Dycomm I called Dycomm the latter part of January, talked to the secretary who answered the phone, explained to her the situation, and she said that Penny was in a conference with everybody else and couldn't be disturbed.
She acknowledged receipt of my letter and said that she would have him either call me back or get a letter out to me tit the next day's maiL Two weeks later nothing.
A friend who is the owner of a nearby repeater saw me a week later and I told him of my unsuccessful attempt to buy a repeater from Dycomm he had ordered a Dycomm machine earlier but had not received it and he said he would be talking to Penny in a few days and would mention my plight, which he did. He told me that Penny was sorry as hell and had misplaced my letter and would 1 please by so kind as to drop him another letter, wliich I did.
I sent him a Xerox of the first letter to him with a note at the bottom telling him that I had also called him. To this date! We have since bought a solid state GE repeater S Also I guess you are not the only one who has trouble getting them to read their mail. Name withheld No further ads will be accepted from Dycomm Jar the Repeater Bulletin, 73 Magazine, or any other 73 publica- tions. You are probably wondermg why I took so long to renew so Til tell you, 1 was considenng dropping you because I did not like your sideways format and the fine print was too much strain on my farsighted eyes, and also you did not put your yearly index tn the Dec.
What 1 do like is your construction articles and also you keep me posted on what the other mags do wrong. I have also operated on but there wasn't much activity so I shelved it temporarily. Reading your January issue, there is a letter from Ed Brooks Jr. Why get another mess started. If you give them another one of our bands, they may at a later date want more. As the saying goes, you give them an inch and they wiU take a mile.
I know several CBers who are running against every regulation the FCC has put forth, 1 have converted a few of them to amateur radio. But, one should carefully check what one is getting and total all the costs involved against other available plans. It is a so-called "Gasthaus' or inn. There are other points one could mention such as: what does one see of Europe staying in insolated spots? Ever drive around in Europe during the tourist peak?
Diario de la marina ( )
There will be no pileups waiting to work you. Name withheld Visiting Europe during the summer months can be a terrible grind. I like the smaller hotels better than the first class Hilton type sanitized and plastic American type hotels. And who wants to sit in a hotel room watching a German-dubbed rerun of December Bride? There was a mad scramble to disconnect linears and lower antennas by the local CB'ers. They are designed to he used as FM mobile logs.
The CB reaction is a side benefit, but one certainly worth ptirsuing. Forming a new utganization by the act of merging does not guarantee continuity of the oJd organization, it is merely a way of saving face, in most cases, it is the final plea for recogni- tion as mentioned earher. Once the merger is complete the old organiza- tion is gone forever, I would like to know how Mr.
The ARRL simply has no competition. I know 1 repeated it.
Show me an organiza- tion or company with sole rights and distributorship of a product or service and 1 witl show you an inferior pro- duct or service! You know it, 1 know it, and Mr. Chapin knows it along withother amateurs in the U. For my part, since all the dissension began 3 years ago. Let's face it, competi- tion is food for the soul, we all must have it.
It is only with competition that products improve and progress is made. Any company or organisation that has a monopoly stands only to protect its monopoly and great efforts are often made tn crush any smaller organiza- tion that threatens to upset the status quo. About a decade ago, a small group organized the Institute of A ma- teur Radi o This a rgan ii a tio n promised to ttutke tftany resounding changes in our hobby: but this proved to he such an earth-shaker that the well esta b lish ed orga n iza t io n to o k great efforts to stop the competition.
What can be done now? Well, for a start, a new organization is needed to offer services, pnKhice some sort of information disseminating system, and liresent ideas to its membership.
The resultant competition need not be vicious nor cruel, but tnay be done with a keen eye tp the other to see what is being done so that it may improve upon the latest offerings. The cottsumer has the abiUty to vote for the system he approves of most, and that vote he casts is in the form of the do liar Ob viously th e organ ization that offers the most will win. That which offers nothing will stagnate. Al- though the planes had been able to inform McMurdo of their change in plan, due to high latitude communica- tion interruptions neither they nor McMurdo were able at that time to notify New Zealand or to request the needed lighting at the airports there.
By working an amateur circuit with Palmer Station you were perhaps the only person in the United States in radio communication with Antarctica at that time. By relay through Palmer, and thence through you to the Office of Polar Programs. McMurdo Station was able to report thLs operational emergency. We were then able to telephone New Zealand authorities to verify thai the situation was known to them and that the airports were ready to receive the flights.
Both planes landed safely. Was one of the Massachusetts bandits, by any chance, my favorite anathema. Herb Gordon of Woodchuck Hill? As your files will disclose I wrote you on Oct. Ultimately I turned the matter over to my attorney and all normal legal steps of a preliminary natitre were taken.
Gordon blithely ignored all correspondence including mineso we decided it would be ridiculous to spend a couple of hundred dollars in court to recover S I publi- cized his performance via a couple of OT organizations to which I belong. I wonder if he is still in business? Further concerning material in re- cent issues.
You have indicated an interest in the possibility of introdu- cing things of a new nature which might have departmental cts.
So how would you like to bankrupt the organization via a thing that might be entitled '"Marketing Magic? It would report complaints from amateurs who, in fact or in fancy, have been victim- ized by suppliers. U would contain nothing libelous, but would rather constitute a factual and objective re- cord that would, hopefully, different tiate between the suppliers who deal above the table and those who don't.
Include your chffck wilh ordc-f Deadline for adi ts ttie 1st of ihe morith tvvo monrhs pnof to pubhcaiian. For example: January 1si i5 the deadline for The March issue which Will be mailed on the 10th o1 February.
Typp copy Phrase and pynctuaie exactly SS you Wish it to appear. No all capital ads. Loudspeaker on front panel for best audio results, S-meter. Nationally advertised. Good discount.
May 23, Book1 1. NO PELAJAR NAMA PENUH NO KAD PENGENALAN MOHD RABBANI BIN WAKIMAN Siti Hawa binti Mohd Yusof NORHASANAH BT ABD GHANI HAZLIZA BINTI HARIS Siti . Sep 24, Cerita Jempol - Ini asli kisah gua sama ibu pacar gua waktu dulu masih pacaran, waktu itu sekitar 7 tahun yang lalu, ibu pacar gua panggil aja namanya tante Sarah, memang sih udah tua, umurnya aja sekitar 45 tapi mukanya masih kelihatan cantik dan body nya juga montok, tinggi sekitar cm, kalau di taksir susu. Jan 28, Paparan dir. bipran renstra & rpjp ditjen. bina marga fixdeal rev1 1. RENCANA STRATEGISDAN RENCANA JANGKA PANJANGDIREKTORAT JENDERAL BINA MARGA W O R K S H O P A R A H P E N Y E L E N G G A R AA N J A LA N K E D E PA N 24 JAN UAR I 2 0 1 2.
Ail equipment guaranteed. Box Anaheim CA. But of course it might take 73 out of the picture - or, like the various con- sumer's magazines, it might start a boom for you. What do you think?
Gordon, though no I with any remarkable success. Bi- monthly. Box B, Phila- delphia, Penna. Complete with ail manuals atid cabinets and precision master oscillator, clock, comparator scope and transfer oscillators. Tech Editor, 73 Magazine. Gas Co, Park, on Thompson Rd. Between Franklin Rd.
Admission SLOO. Vendors Free Hourly Prizes, Refreshments. For info Write Bill Evans, P. BoxIndianapolis, Ind. Low Pass Filter. See pi 15, March Write for brochure. Taylor Communis cationa Manufacturing Company. Box 1 26, Agineourt, Ontario, Canada. Are you going to sH still while this piracy tafces place? Or are ynu going to fight back?
Dec 24, - Explore nikiajanae's board "Goth disney" on Pinterest. See more ideas about Disney, Goth disney and Disney love pins. JEMPO. likes. Siamo cinque persone, siamo treasuresforthesoul.comers: Pages Directory Results for B - bslady. B - B & C Property Maintenance Inc. B & C Property Management Ltd - B & L Vending. B & L Veranstaltungstechnik - B &P ???????????????????????????????. B &P's Rings N Things - B A B E. B A B E - B A R S. B A R S
Are you going to get on ? Are you going to help get a repeater on ? USA only. Interstate all the way; 2 hours Chicago; 2 hours Cincinnati: 2 hours Louisville. Indiana Radio Club Coun- cil. Shipping costs collect. W3RYJ, R. Will trade. Swan-TV2-B - S BoxWaterioo, Ontario, Canada. List available. Don't make a move until you've seen our new publication. Free sample copv! Six issues SI. Kleinschmidt teletypewriter KSRvery good con- dition, S Aircraft emergency horn, 28vft5.
New 28LPR rcperf in ognl sealed carton, S Still, it seems that most hams do not have as good an antenna system as they would like to have. There are two major reasons for this: They don't have the room or they don't have the money. Although I was working a fair number of stations, the reports were usually, "You have a good signal here, but there is plenty of QRM on the frequency, 73 and hope to see you when the band is quieter.
Several months ago I had the idea of suspending a quad from a wire boom. Closer examination of this idea showed that if the square element config- uration was to be used, two booms would be required, if the diamond configuration were to be used it would be difficult to form the square shape necessary and the elements themselves would almost touch the ground. Suddenly while playing about with dif- ferent element configurations, I realized that the most compact shape with a iX perimeter would be a triangle.
So i came up with the antenna shown in Fig, 1. This requires only one supporting wire, and the element shape can be adjusted so that the height above ground is about 7 ft. Al- though this sounds low, it turns out to be just high enough to mow the lawn, yet low enough to reach easily for pruning. With the guys which hold the elements in shape attached to a fence at the edge of the yard, the forces are directed to the side instead of downwards, thus putting less stress on the supporting wire.
Although I wUl explain the method of construction in considerable detail here, the mechanical structure is not very critical and is only presented for the use of those who wish to duplicate my antenna exactly. Do not anchor guys to ground unlit the mast is vertical. Then tighten guys as tension on the antenna is increased. The insulators I used have the two holes drilled perpendic- ular to each other, which makes them excellent for supporting the elements of this antenna.
Electrical tape was used to hold them in position. Second, set up the masts according to the details of Fig. A pulley is attached to the top of the mast and 50 ft of flexible guy wire is pulled through it.
This will be used to lift the antenna into position after the masts have been erected and lower it for changes or servicing. Two guys attached adjacent to the pulley are used to balance the tension on the support- ing wire. In addition, two more guys are attached halfway up the masts to hold them straight. The entire assembly is light enough to be walked up into the vertical position and dropped into a ft hole.
FREE Jempol chat rooms at treasuresforthesoul.com Join the hottest Jempol chatrooms online! Mingle2's Jempol chat rooms are full of fun, sexy singles like you. Sign up for your free Jempol chat account now and meet hundreds of Negeri Sembilan singles online! No other Jempol chat sites compare! Jeempo Dating. Search this site. Jeempo United Kingdom - Meet Online Singles. Ce este Jeempo Romania. Encuentros exclusivos y sin compromiso - Jeempo Argentina. Jeempo Canada. Looking for a friend or a date? Jeempo France - Rencontrez des celibataires pres de chez vous. Jeempo is a membership only online club. 29, people have already joined. Chatting, making new friends, dating - find anything you want right now! The more photos you upload, the more people will notice you and the higher your chances will be to meet someone who shares your interests. Thousands of users register every day on Jeempo to.
The earth can then be filled in around the mast and the guys temporarily anchored. Next, measure the wire for the elements according to the table in Fig. Make sure you do not mix up the elements at this point. Add two more insulators to each element and spread the wire out on each side of the boom so that it will not tangle when the antenna is being lifted into place. The feedline should be attached to the driven element and taped along the support wire to the end nearest the shack.
Rg, 5, Details of the element mounting. The loss in RG is 1. Next, attach the support wire ends to the wire on pulleys of the masts and hoist the antenna into the air. Attach nylon clothesline or heavy string to the insulators and pull the elements into a triangular shape. These guys should be attached as far from the antenna as possible or even better as high from the ground as possible.
This is to prevent the strain of the guys from pulling the support wire out of shape. Now you are ready to prune the ele- ments. This can be done by setting a field strength meter in front of the antenna and trimming the elements for a maximum reading. If this is not possible, a reasonably good approximation can be made by reson- ating the elements to the frequencies shown in Fig.
If the frequency Is higher, they should be shortened accordtngfy. D max. Choose the combina- tjon or add the RK'3 to your present B and enjoy the improved gain and front to back. P, El Length 11' Turn. Radius r Total Weifiht nibs. No center loading.
Excellent quality eonstrucEion, Mount with inexpensive TV hardware. Power Rating Watts P. P, Total Weight 6 lbs. Call 1 W. A plot of swi' vs frequency shows that the antenna is quite flat across the entire band. In fact the swr does not exceed J. SrJ on any frequency, dipper is not being pulled by the antenna element, a communications receiver can be connected to the antenna which will pick up the signal and assure accurate calibra- tion.
Last, trim the driven element for a minimum swr. The first time I plugged the antenna into the transmitter I thought something had gone wrong with my swr meter. No matter how far I advanced the sensitivity I could not get a reading in the reflected position.
The swr was a flat The final resonance swr is shown in the graph of Fig. Receiving, his signals were also S9. A few more contacts with more S9 reports using W PEP confirmed that the anten- na was working well. Comparison reports with a vertical show a consistent 10 to 15 dB gain on both receive and transmit. Since I am no antenna engineer, I cannot give any rigid theories as to how or why this antenna works. I do not even know what the polarization is.
All I can say with certainty is that it works for me and I am quite pleased with its performance. Like, how about a cheap I2-element 20m beam? What is that, OM?
Television on these DX bands would be most interesting. They have just given the article a cursory glance and then forgotten all about it. SSTV is a means whereby amateurs can transmit and receive television pictures world-wide using the normal narrow band wavelengths in the amateur bands of 80, 40, 20 J 15 and 10 meters. All amateurs will understand the prin- ciples of commercial broadcast television. Built-in telescoping antenna, and connector for external antenna. Use barefoot or with accessory amplifier.
Transmitted by W4LAS, the picture is of his niece. To use a mini- mum of 2 MHz bandwidth for amateur televison means that hams have to use the MHz or even higher frequency bands, which they do, but activity is comparatively low and communication is normally only a few miles, seldom out of the amateur's own country. By using SSTV, television pictures can be transmitted using a bandwidth of no more than 2,5 kHz so that transmission is perfect- ly possible in the 80 to 10 meter bands where world-wide communication is quite normal.
Not only is this possible, but, because of the narrow bandwidth used, it easily complies with international regula- tions, covering no wider a channel than SSB does and even less than that of AM or FM. L Block diagram of interconnections for the short-wave viewer and tranmntter for television reception.
Block diagram of interconnections for the transmission of pictures. The difference between amateur tele- vision on MHz, where objects can be seen moving, and SSTV, is that the picture must be static.
Call signs, photographs of self, yl, xyl, family, shack, cartoons and written messages can be easily transmitted anywhere in the world with surprisingly good definition.
But it is fascinating to contact a station 10, miles or even 50 miles away and exchange a series of pictures. To make this technically feasible on a world-wide basis, a standard has been reached which all SSTV amateurs use, as follows: Number of lines Time per frame Modulation white Modulation black Sync- Sync duration Horizontal Vertical 8 seconds Hz Modulation FM 1 Hz Hz 5 milliseconds 30 milliseconds Normally after transmitting video signals, the same frequency is used for sound to announce the fact that you are looking for slow scan contacts.
Althougli technically it is possible to use vision and sound simulta- neously on either sideband, I have not heard of this method in use yet. For reception of the pictures, all that is necessary is for the output from your communication receiver speaker terminals to be fed into a cathode ray assembly called the monitor.
The incoming signal is truly slow scan and, unlike commercial television which appears to be instantaneous due to the high line and frame rate, appears to paint the picture from the top left to the bottom right of the cathode ray tube, taking a total of eight seconds to complete the picture on the tube.
That is why you have to use a P-7 phosphor. When this eight second period reaches the bottom of the tube, the sync signal starts the process over again. The normal practice is to transmit each picture for three or more frames, enabling the receiving amateur to get a full picture and tape record. Intensity of the picture is frequency - modulated ac- cording to the standards already hsted, ix.
The baiidwidth is thus limited to the normal voice grade communication frequencies into the trans- mitter microphone socket for transmitting and into the receiver circuits for reception. Now don't think that this is too complex for you. I understand that there are over 30 countries using SSTV and that some amateurs akeady have over 20 C to their credit.
It is a pleasure to find the slow scan amateurs such a friendly bunch, with no rush to get rid of you for the next QSO. Contact for an hour or more is quite normal and the experts are always willing to give you every assistance and advice. If you hear the station on sound then that is the correct tuning position to receive the picture. Then you can play them back at leisure for checking purposes, proving reception to your friends or taking photographs of the pictures.
For transmitting you can use any of the following methods to feed the picture into your transmitter microphone socket: 1. Use a video tape recorder.
Get an SSTV amateur to make a video tape of your call sign, photographs, etc. All you do is feed recorder output into your transmitter microphone socket. Use a Flying Spot Scanner, With this, you can make up your own version of your call sign to feed into the transmitter, 3. Use a video camera. This is the ultimate for SSTV, You can have a target stand in front of the camera on which to place any writing or photographs or you can tum the camera on yourself, your shack, etc.
Camera output again is fed into the transmitter as in the other methods. The video signal is adjusted to give the same transmitter rf output level as your voice peaks, or just slightly lower, being careful on SSB not to go beyond the specified carrier insertion levels or, if using an AM or FM transmitter, the same levels.
If, for example, your SSB transmitter instruc- tions say speech peaks of mA, then 1 would adjust the video level to arpund mA- If you build your own equipment, see the appendix for numerous articles on equip- ment. Pictured above is a complete SSTV sta- tion.
The inset photo shows the back of the Robot monitor, with all connecting cables. Power is then sup- plied to the camera from the monitor and the video image from your camera is displayed on the monitor. Your microphone cable now connects to the microphone jack provided on the back of the Robot Monitor 3. After these connections are made, the sta- tion is operated by switches on the monitor front paneL That's all there is to it.
As you can see, abso- lutely no modifications of your existing equip- ment are required. All necessary cables are included with your Robot monitor and camera. See 73 magazine May 7K E:K. Y: Video Vision Co. Sfock- holm NJ. Monitors, monitor kit sets. See 73 magazine April 71, It will take you no more than one hour after receiving the ready-made equipment to be on the air. Recep- tion is remarkably good since even signals as low as S3 will provide a picture and S7 signals will take a lot of QRM punishment.
Various simple cabling connections for the viewer and transmitting amateur are shown in Figs. The big advantage of taping all contacts is that you can edit the tape, keeping the best pictures and sound reception as a permanent record to photograph at your leisure. It wUl take eight seconds to reach the bottom. The photographs in this article were taken by this method. Times for long distance communication will be the same as for phone contacts mainly operating on km or kHz. Macdonald, C. Cohen, TJ.
WatKon, DJ. Popkin-C'lurman, J. Miller, D. Heavier QRM during reception and reduced radiation in a desired direction are inherent to this type of antenna, despite the low vertical angle of propagation which is favorable for DX work. Such arrays will exhibit a cardioid or "figure-8" horizontal pattern, dependent upon the phasing-Iine length and feed point.
This arrangement is suitable only for single band operation due to the phasing requirements, and in the case of trap verticals may involve the significant expense of the dupli- cate antenna. The directional pattern is broad, fixed to the plane of the twin antennas, and can only be reversed by somewhat complex coaxial switching of the phasing line. The purpose here is not to give detailed construction of such an array, but rather to present some ideas which I have found to accomplish effective directional characteristics for my commercial trap vertical.
Vertical Reflector The simplest application of a parasitic element is a vertical reflector spaced 0. The photograph shows a 21 MHz reflector used in conjunction with a popu- lar trap vertical. Figure 1 illustrates the arrangement of the reflector with a single band groundplane antenna. Simple reflector for ground plane antenna. This can be done by inserting a switch, or remote operated relay J close to the reflector base.
The equivalent increase of x4 power would cost up to one hundred times as much. Director elements may be added in-line for improved gain and front-to-back ratio.
However, to achieve worthwhile results directors must be spaced OJ to 0,15 wavelengths from the antenna and each other.
This requires that they be adjusted to an electrical length shorter than 0.
It agree, very good message19.01.2020|Reply
I shall afford will disagree with you22.01.2020|Reply