By L. Lukjan. Maryville University of Saint Louis. 2018.

One important feature of the wave-like properties of matter is that it can pass through regions that would be inaccessible if it were treated as a particle cheap 160 mg super avana free shipping erectile dysfunction caused by jelqing, i order super avana 160mg otc erectile dysfunction medications injection. This can be visualised, for example, by considering the Enzymology takes a quantum leap forward 23 Figure 2. A popular approach to modelling catalysis has been to visualise an energy barrier that must be surmounted to proceed from reactants to products. For the reaction to proceed, reactants (A–H B) must pass over the potential energy barrier to the product (A H–B) side via the so-called transition state (denoted by [A. The greater the height of this energy barrier, the slower the rate of reaction. Enzymes (like other catalysts) reduce the energy required to pass over this barrier, thereby increasing reaction rate. This classical over-the-barrier treatment – known as ‘transition state theory’ – has been used to picture enzyme-catalysed reactions over the past 50 years. However, recent developments indicate that this representation is, at least in some circumstances, fundamentally flawed and should instead be considered in terms of quantum tunnelling through the barrier. Thus, the pathway from reactants to products in an enzyme-catalysed reac- tion may not need to pass over the barrier, as in transition state theory with particle-like behaviour, but could pass through the barrier. As the analogy suggests, this can lower significantly the energy required to proceed from reactants to 24 M. Illustration of the wave-like property of matter by analogy with the vibrations on a violin string. Although there is a node (a position where the string is stationary) in the centre of the string, the vibration is transmitted through this node – this is analogous to passing through a region of zero probability as in quantum tunnelling. Thus, quantum tunnelling may play an important role in driving enzyme-catalysed reactions, especially for the transfer of small nuclei such as hydrogen. Indeed, quantum tunnelling is the established mechanism for enzyme- mediated transfer of the much smaller electron. Proteins are electrical insulators; nevertheless, electrons can travel large distances on the atomic scale (up to around 3 10 9 m) through them. This apparent paradox – of an electron passing through an electrical insulator – can be understood in terms of the wave-like properties of the electron. Thus, the electron can pass via quantum tunnelling through regions from which it would be excluded by its particle-like nature. In contrast to electron transfer via quantum tunnelling, evidence for hydrogen tunnelling in enzyme molecules is extremely limited. This arises conceptually because the mass of the hydrogen is approximately 1840 times greater than that of the electron. The probability of tunnelling decreases with increasing mass, which reduces significantly the probabil- ity of hydrogen versus electron tunnelling. Nevertheless, for those enzyme-catalysed reactions with a large activation energy – requiring a Enzymology takes a quantum leap forward 25 Figure 2. Tunnelling of a wave with kinetic energy E through a rectangular potential energy barrier, height V. The narrower the barrier, the smaller the mass of the particle and the smaller the difference between V and E, the greater the tunnelling probability. If the amplitude of the wave has not reached zero at the far side of the barrier, it will stop decaying and resume the oscillation it had on entering the barrier (but with smaller amplitude). Until recently, quantum tunnelling was thought to be significant only at very low (so-called ‘cryogenic’) temperatures. However, deviations from classical transition state theory behaviour have been seen recently, implying that hydrogen tunnelling may be significant at physiological temperatures. These results have, in the main, been modelled as hybrid ‘over’ (transition state theory) and ‘through’ (quantum tunnelling) barrier transfer reactions, i. Our own studies have revealed for the first time that quantum tunnel- ling can be the sole means by which an enzyme catalyses hydrogen trans- fer during C–H (carbon–hydrogen) bond breakage. The reaction pathway does not pass up the energy barrier prior to tunnelling – as with the quantum correction models of transition state theory – but tunnels through the barrier from the starting (or so-called ‘ground’) state. SCRUTTON Paradoxically, reaction rates (as with transition state theory) are still highly dependent on temperature. This observation is inconsistent with a pure ‘ground state’ tunnelling reaction, since the probability of tunnelling (and thus rate of reaction) is a function of barrier width, but is independent of temperature.

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As VF is so readily treatable and resuscitation is more likely to be successful trusted 160mg super avana erectile dysfunction in young males causes, it is vital that great care is taken before diagnosing asystole to the exclusion of VF discount super avana 160 mg visa erectile dysfunction doctors augusta ga. The electrocardiographic leads and their connections must all be checked, as must the gain and brilliance of the monitor. All contact with the patient should cease briefly to reduce the possibility of interference. Persistent P waves due to atrial depolarisation are seen 16 Asystole and pulseless electrical activity recorded when the monitor has the facility to do this, or the defibrillator monitor electrodes should be moved to different positions. BP 0 On occasions, atrial activity may continue for a short time after the onset of ventricular asystole. In this case, the ECG will ECG show a straight line interrupted by P waves but with no evidence of ventricular depolarisation. Pulseless electrical activity in a patient with acute myocardial infarction. PEA Despite an apparently near normal cardiac rhythm there was no blood pressure (BP) Diagnosis PEA is the term used to describe the features of cardiac arrest despite normal (or near normal) electrical excitation. The diagnosis is made from a combination of the clinical features of cardiac arrest in the presence of an ECG rhythm that would PEA can be a primary cardiac normally be accompanied by cardiac output. In “primary” PEA, excitation-contraction coupling fails, which results in a profound loss of cardiac output. Causes include massive myocardial infarction (particularly of the inferior wall), poisoning with drugs (for example, blockers, calcium antagonists), or toxins, and electrolyte disturbance (hypocalcaemia, hyperkalaemia). In “secondary” PEA, a mechanical barrier to ventricular filling or cardiac output exists. Causes include tension pneumothorax, pericardial tamponade, cardiac rupture, pulmonary embolism, occlusion of a prosthetic heart valve, and Cardiac arrest hypovolaemia. Treatment in all cases is Precordial thump, if appropriate directed towards the underlying cause. Basic life support algorithm, if appropriate Management of asystole and PEA Attach defibrillator/monitor Guidelines for the treatment of cardiopulmonary arrest caused by asystole or PEA are contained in the universal advanced life Assess rhythm support algorithm. Treatment for all cases of cardiac arrest is determined by the presence or absence of a rhythm likely to respond ± Check pulse to a countershock. Both are treated in the same way, by following the right-hand side of the algorithm. CPR 3 minutes (1 minute if immediately after defibrillation) When using a manual defibrillator and ECG monitor, non-VF/VT will be recognised by the clinical appearance of the patient and the rhythm on the monitor screen. When using an During CPR, correct reversible causes If not done already: automated defibrillator, non-VF/VT rhythms are diagnosed • Check electrode/paddle positions and contact when the machine dictates that no shock is indicated and the • Attempt/verify: Airway and O2, intravenous access • Give adrenaline (epinephrine) every 3 minutes patient has no signs of a circulation. When the rhythm is • Consider: Amiodarone, atropine/pacing, buffers checked on a monitor screen, the ECG trace should be examined carefully for the presence of P waves or other Potentially reversible causes electrical activity that may respond to cardiac pacing. Pacing is • Hypoxia often effective when applied to patients with asystole due to • Hypovolaemia • Hyper- or hypokalaemia and metabolic disorders atrioventricular block or failure of sinus node discharge. The role • Tamponade • Toxic/therapeutic disturbances of cardiac pacing in the management of patients with • Thromboembolic or mechanical obstruction cardiopulmonary arrest is considered further in Chapter 17. As soon as a non-VF/VT rhythm is diagnosed, basic life The advanced life support algorithm for the management of non-VF cardiac support should be performed for three minutes, after which arrest in adults. Adapted from Resuscitation Guidelines 2000, London: the rhythm should be reassessed. During this first loop of the Resuscitation Council (UK), 2000 17 ABC of Resuscitation algorithm, the airway may be secured, intravenous access 4Hs obtained, and the first dose of adrenaline (epinephrine) given. If asystole is present atropine, in a single dose of 3mg ● Hypoxia ● Hypovolaemia intravenously (6mg by tracheal tube), should be given to block ● Hyper- or hypokalaemia and metabolic the vagus nerve completely. The most common treatable causes are ● Tension pneumothorax ● Tamponade listed as the 4Hs and 4Ts at the foot of the universal algorithm. If, during the treatment of asystole or PEA, the rhythm changes to VF (which will be evident on a monitor screen or by an automated external defibrillator advising that a shock is indicated) then the left-hand side of the universal algorithm should be followed with attempts at defibrillation. After the delivery of a shock, it takes a few moments before the monitor display recovers; during this time the rhythm may be Asystole after defibrillation interpreted erroneously as asystole.

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In open questions respondents use their own words to answer a question generic 160 mg super avana amex erectile dysfunction hormonal causes, whereas in closed questions prewritten response categories are provided (see Table 9) Also cheap super avana 160mg with mastercard erectile dysfunction watermelon, you need to think about whether your ques- tionnaire is to be self-administered, that is, the respondent fills it in on his own, away from the researcher, or whether it is to be interviewer administered. Self-administered ques- tionnaires could be sent through the post, delivered in per- son or distributed via the internet. It is also important to think about the analysis of your questionnaire at this stage as this could influence its design (see Chapter 11). Respondents tend to feel that Respondents can only answer they have been able to speak in a way which may not their mind. In self-administered Is quick and easy for questionnaires, respondents respondents to tick boxes – might not be willing to write might be more likely to a long answer and decide to answer all the questions. How do you know the meaning of a blank answer when you come to the analysis? Can use open questions to Can include a section at the find out all the possible end of a closed-ended responses before designing a questionnaire for people to closed-ended questionnaire. HOW TO CONSTRUCT QUESTIONNAIRES/ 89 WORDING AND STRUCTURE OF QUESTIONS When constructing each question think about the words you use. Try not to use words which may have a double mean- ing or be misinterpreted, as some words have different meanings for different groups of people. And, above all, avoid questions which will cause annoyance, frustration, offence, embarrassment or sadness. You should never make someone feel uncomfortable, for what- ever reason, as a result of filling in your questionnaire. Check that a question is not double-barrelled, that is, two ques- tions in one. Also, avoid negative questions – the type which have ‘not’ in them as this can be confusing, especially when a respondent is asked to agree or disagree. X Make sure that your questions don’t contain some type of prestige bias. This phrase refers to questions which could embarrass or force respondents into giving a false answer. They might do this if they do not want to look ‘bad’ in front of the researcher, or they might do it because it is expected behaviour. Questions about income or educational qualifications might illicit this type of response, so you need to be careful about how you try to obtain this information. X Some issues may be very sensitive and you might be bet- ter asking an indirect question rather than a direct ques- tion. Promising confidentiality and anonymity may 90 / PRACTICAL RESEARCH METHODS help, but many respondents can, understandably, be sceptical about these promises. If you ask an indirect question in which respondents can relate their answer to other people, they may be more willing to answer the question. Using closed-ended questions If you are constructing a closed-ended question, try to make sure that all possible answers are covered. This is particularly important for time and frequency questions such as ‘how often do you. Also, you want to make sure that you don’t artificially create opinions by asking someone a question about which they don’t know, or don’t care. You need to make sure that you include a ‘don’t know’ category in this case. Firstly, it assumes that the respondent has a car and secondly, it assumes the respondent washes his car. Would a respondent feel bad if they didn’t have a car and therefore would tick ‘four times a week’ anyway? Would they feel bad if they don’t ever wash their car but feel the researcher expects them to? If you need to ask this question, you should ask a filter question first to find out whether the respondent actually owned a car. Then you would need to ask: ‘If you wash your car, HOW TO CONSTRUCT QUESTIONNAIRES/ 91 how many times a year? Have a look at Exercise 2 which will help you to think about some of the issues involved in the wording and structuring of questions. EXERCISE 2 Read the following questions and decide what is wrong with them. What do you think about the Green Peace attempt to blackmail the Government?

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Belman Department of Neurology generic super avana 160 mg with mastercard erectile dysfunction clinic, School of Medicine super avana 160mg low price impotence divorce, State University of New York (SUNY) at Stony Brook, Stony Brook, New York, U. Bergin Childrens Hospital, Department of Neurology, Boston, Massachusetts, U. Bibat Neurogenetics Unit, Kennedy Krieger Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland, U. Ian Butler The University of Texas Medical School at Houston, Houston, Texas, U. Department of Neurological Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, U. Cohn Johns Hopkins Hospital, Children’s Center, McKusick-Nathans Institute of Genetic Medicine, Baltimore, Maryland, U. Conry George Washington University School of Medicine, Children’s National Medical Center, Washington, D. Courvoisie Division of Child and Adolescent Psychiatry, Department of Psychiatry and Behavioral Sciences, The Johns Hopkins Medical Institutions, Baltimore, Maryland, U. Martha Bridge Denckla Johns Hopkins University School of Medicine, Kennedy Krieger Institute, Baltimore, Maryland, U. Dure, IV Division of Pediatric Neurology, Department of Pediatrics, The University of Alabama at Birmingham, Birmingham, Alabama, U. Paul Grahan Fisher The Beirne Family Director of Neuro-Oncology at Packard Children’s Hospital, Stanford University, Stanford, California, U. Freeman Pediatrics and Neurology, Johns Hopkins Hospital, Baltimore, Maryland, U. Natan Gadoth Department of Neurology, Meir General Hospital, Kfar Saba, Israel William Davis Gaillard Department of Neurology, Children’s National Medical Center, Washington, D. Gailloud Division of Interventional Neuroradiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, U. Gilbert Cincinnati Children’s Hospital Medical Center, Movement Disorders Clinics, Cincinnati, Ohio, U. Fiona Goodwin Department of Pediatric Neurology, Child Health, University of Southampton and Southampton University Hospitals, Southampton, U. Grados The Johns Hopkins Hospital, Department of Psychiatry, Division of Child and Adolescent Psychiatry, Baltimore, Maryland, U. Gray Kennedy Krieger Institute, Department of Neuropsychology, Baltimore, Maryland, U. Carolyn Elizabeth Hart Mecklenburg Neurological Associates, Charlotte, North Carolina, U. Hayflick Molecular and Medical Genetics, Pediatrics and Neurology, Oregon Health & Science University, Portland, Oregon, U. Michael Hemphill Department of Neurology, Medical College of Georgia, Savannah Neurology, Savannah, Georgia, U. Alec Hoon Johns Hopkins University School of Medicine, Kennedy Krieger Institute, Baltimore, Maryland, U. Judy Huang Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, U. Ichord Department of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, U. Jinnah Department of Neurology, Johns Hopkins University, Baltimore, Maryland, U. Johnston Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, U. Edwards School of Medicine, Marshall University, Huntington, West Virginia, U. Jordan Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, U.

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