1. The eyes of the crab Carcinus follow with constantly increasing lag the movement of a horizontally rotating (but not a linearly translated) visual field during the slow phase of optokinetic nystagmus. The difference between the eye speed and the drum speed is the effective stimulus for optokinetic nystagmus, and the response bears a constant relation to the stimulus over four orders of magnitude. The lower limit of the response is due to the breakdown of neuromuscular, and not visual mechanism. 2. An overall feedback mechanism exists in which the movement of the eye reduces the apparent movement of the drum. The control of the eye movement is by way of visual cues and proprioceptors play no part. 3. A seeing eye, provided with the appropriate visual stimulus, will drive the other eye if the latter sees no contrasting objects in its visual field or is blinded. Clamping an eye so that it cannot move relative to a stationary, contrasting visual field has the same effect as surrounding the animal with a blank field. 4. The rapid return phase of optokinetic nystagmus also takes no account of proprioceptors, but seems to be triggered when the efferent impulses to the eye muscles reach a definite frequency. Blinding one eye or increasing the drum speed cause a delay of the fast phase. Both eyes flick back simultaneously and the impulses in the oculomotor nerve which cause the slow phase are inhibited during the fast phase. 5. The fast protective retraction of the eye into its socket is a reflex which can be elicited by mechanical stimulation of a single sensory hair. The eyes can retract independently and if retraction occurs during the slow phase of optokinetic nystagmus, the efferent impulses in the oculomotor nerve of the retracting side are centrally suppressed. Peripheral inhibition of the optokinetic response occurs in the retracted eye when it. Is retained in its socket after retraction while the other eye continues with the slow phase of optokinetic nystagmus.7. A comparison reveals similarities in the mechanism causing the onset of the fast phase of optokinetic nystagmus in the crab and in mammals.

Smooth muscles as a group exhibit great diversity of pharmacological and physiological properties. This makes it impossible to produce any but extremely generalised schemes for smooth muscle contractile mechanisms. However, knowledge of the detailed physiology and pharmacology of specific types of smooth muscle has been growing at an increasing rate, especially regarding vascular and visceral muscles. The rat anococcygeus muscle has, however, been investigated little. This work describes the excitation- contraction coupling mechanism in this preparation. The rat anococcygeus muscle was found to contract to all three of the agonists used (noradrenaline, acetylcholine and potassium chloride). In the first section of this work the properties of these contractions were investigated. It was found that the contractions induced by each agonist exhibited different pharmacological properties, (with regard to low calcium, sodium nitroprusside, verapamil, Stellazine and theophylline). This can be taken as an indication that the different agonists use different activation pathways. Electrophysiological studies showed that the membrane potential per se is not important in the regulation of contraction. (ie. the depolarisation produced by an agonist is not simply related to the tension produced ). KC1 produces the greatest change in membrane potential (from -55mV to -20mV for a maximal dose), but produces the least rise in tension of the three agonists. Evidence from other preparations and the results of the experiments with Stellazine suggest that the rise in tension produced by the agonists is not simply related to the rise in intracellular calcium concentration, but that some amplification of the response occurs. The way in which the agonists produce this amplification of the response is suggested as being related to changes in the levels of the cyclic nucleotides, cAMP and cGMP within the cells. It was found that the agonists did not substantially affect cAMP levels, but that all three reduced cGMP levels by varying amounts. The ratio of the levels of cAMP/cGMP produced by activation with each agonist correllates very well with the tension produced. This suggests that the ratio cAMP/cGMP is important in the regulation of contractility in this muscle. However, doubt is cast upon this theory by the results of experiments using sodium nitroprusside (NP). It was found that NP (2 X 10-7M) caused a pronounced change in the ratio cAMP/cGMP (by increasing cGMP levels ), but only a small change in tension (so that the tension in these experiments does not correllate well with the ratio cAMP/cGMP). In order to retain the hypothesis that cyclic nucleotides are important in the regulation of contractility in this preparation, it is proposed that some form of compartmentalisation of the cyclic nucleotide changes occurs within the cells.

As stated earlier the Simplex Method (or its variations e.g. Dual Simplex Method) has thus far been the most effective and widely used general method for the solution of linear programming problems. The Simplex Method in its various forms starts initially with a basic feasible solution and continues its moves in different iterations within the feasible region till it finds the optimal solution. The only other notable variation of the Simplex Method, namely the Dual Simplex Method, on the other hand, by virtue of the special formulation of the linear programming problem, starts with an in-feasible solution and continues to move in the in-feasible region till it finds the optimal solution at which it enters the feasible region. In other respects both the Simplex and the Dual Simplex Methods follow essentially the same principle for obtaining the optimal solution. The rigorous mathematical features have been widely discussed in the literature [12, 16, 34, 35, 38, 68, 77] and only those formal aspects of this topic which are closely related to the subject of this thesis will be outlined. The Multiplex Method, though reported in the literature [30, 15, 69, 71, 29, 32], is not so well known and has also not been widely coded on electronic computers. It had earlier been programmed for the English Electric's Computer ‘DEUCE' by the author [72] and Ferranti's ‘MERCURY' by Ole-John Dahl in 1960 [15]. Later both the above mentioned computers were obsolete and the efforts presently concentrate on coding it for UNIVAC 1100 and IBM 360. The Multiplex Method, as such, has been included in the present thesis and discussed in some detail in chapter 2. The flow diagram and the algorithm for the method is given in section 2.4, chapter 2. The main body of the thesis consists of developing a new linear programming method which has been called the Bounding Hyperplane Method – Part I. This is explained in detail in chapter 3. The method could initially start with either a basic feasible or in-feasible point and in its subsequent moves it may either alternate between the feasible and the in-feasible regions or get restricted to either of them depending upon the problem. It is applicable as a new phase which we call phase 0 to the Simple Method, particularly in situations where an initial basic feasible point is not available. In such cases it either results in a feasible point at the end of phase 0 or else yields a ‘better' in-feasible point for phase 1 operations of the Simplex Method. Moreover, it is found that the number of iterations required to reach either the former by the application of phase 0 or the latter by the application of first phase 0 and then phase 1 are, in general, less than those required by following phase 1 alone. This is explained with illustrations in Chapter 6. Even when applied alone the method, in general, yields the optimal solution in fewer iterations as compared with the Simplex Method. This is illustrated with examples in chapter 3. We also develop and illustrate a powerful but straight-forward method whereby we first find the solution to the equality constraints and (if the former does not yield an inconsistent solution point) then the transformations to the latter are obtained from the equality solution tableau corresponding to the former. This results in reducing the iteration time appreciably for each iteration of the method. It has been called the B.H.P.M. – part II and is discussed in chapter 4. To estimate the time taken by the B.H.P and the Simplex Method, the two codes (written in Fortran) have been run on a number of problems taken from the literature. The results have been summarised in chapter 7. Finally, the suggestions for further research towards i. the extensions of the B.H.P.M. to the quadratic programming problem where the function in (1.1.1) is positive semi-definite, and (ii) the accuracy of computations in linear programming, in general, are discussed in sections 8.1 and 8.2 respectively of chapter 8.

Chapter I. Pulse/chase labelling and DNA fibre autoradiography have been used to study the durations of the stages of the cell cycle, and the manner of chromosomal DNA replication, in Xenopus cells in tissue culture at 18°C, 23°C and 28°C. Cultures were grown in modified Eagle's basal medium, containing salts at concentrations appropriate to Amphibia, plus glutamine and foetal calf serum. The subculturing procedures were carried out every fortnight, with a medium change every week. For studying the durations of the stages of the cell cycle, cells were labelled with low specific activity tritiated thymidine (3H-TdR) for 30 min or 1 hour, then left to continue growth in non-radioactive medium, and fixed at regular intervals thereafter. Whole-cell autoradiographs, stained in Giemsa, were prepared from these fixations. For studying DNA replication, tissue cultures were treated with flurodeoxyuridine (FUdR) to arrest cells at the beginning of the S-phase, then labelled with high specific activity 3H-TdR for various times. In the case of pulse/stepdown labelling, the first period of labelling was followed by a further period in the presence of 3H-TdR at one quarter of the original specific activity. DNA fibre autoradiographs were prepared from such labelled tissue cultures. Chapter II. An analysis of the durations of the cell cycle stages obtained from pulse/chase labelling experiments gave the following results: (1) at 18°C G1 lasts for 31 hrs, S for 29.5 hrs, G2 for 8.5 hrs, M for 3 hrs and the total generation time is 72 hrs; (2) at 23°C G1 lasts for 14-3 hrs, S for 15-5 hrs, G2 for 5.7 hrs, M for 0.5 hrs and the total generation time is 36 hrs, and (3) at 28°C G1 lasts for 11.3 hrs, S for 13.5 hrs, G2 for 4.8 hrs, M for 0.4 hrs and the total generation time is 30 hrs. Pulse labelling followed immediately by fixation, and subsequent Giemsa staining, enables a quick and convenient assessment to be made of the relative durations of the cell cycle stages. In such preparations nuclei in S-phase are labelled, nuclei in G1 are small and unlabelled and nuclei in G2 are large and unlabelled. Chapter III. Pulse/stepdown labelling shows that DSTA replicates bidirectionally in the Xenopus cells. Origin to origin distances (initiation intervals) vary, but the range of and the mean initiation intervals at all three temperatures are much the same. The mean interval between initiation points is of the order of 60 to 66 mum. Staggering of initiations is evident at all three temperatures, and may be disproportionately greater at 28°C than at 23°C and 18°C. Evidence against the existence of replication termini is provided. Chapter IV. The rates of progress of DITA replication forks cannot be determined from pulse/stepdown preparations, so these rates had to be estimated from pulse labelled cultures. They are 5.5 mum/hr at 18°C, 10 mum/hr at 23°C and 16 mum/hr at 28°C.

Sodium borohydride in aqueous dimethylsulfoxide has been shown to be a good reducing agent for converting certain activated aromatic halo-compounds to their corresponding dehalogenated products. The order for ease of removal of the halogen is I>Br>Cl. The activating groups are those that are strongly electron-withdrawing. The reactivity for activating aryl halides substituted with groups such as -NO₂, -CF₃, -F, -Cl, -Br, and -I is in the order ortho > meta > para, thus indicating that the activating effect has its origins in inductive rather than resonance effects. The removal of halogen appears to be occurring via a displacement on-halogen. This has been demonstrated in certain cases by using deuterium oxide instead of water in the reaction. When this is done, the halogen is replaced by deuterium instead of hydrogen. This indicates that the halogen leaves without its bonding electrons, thus leaving a carbanionic site on the aromatic ring. The carbanion is subsequently quenched by a proton from the water. This reaction has also been shown to be applicable to aromatic systems other than benzene. On-halogen type displacement by the hydride ion also occurs on certain polyhalogenated alkanes with the formation of a guasi-carbanionic intermediate which can be quenched by a proton from water, undergo alpha elimination, or undergo beta elimination. The alpha elimination occurs when a good leaving group is not present on the beta carbon. Attempts at trapping the carbene type intermediate from alpha eliminations were unsuccessful, evidently because of the presence of the water in the reaction medium. In two cases eliminations have occurred through a benzene system to generate para-xylylenes. Diazonium salts were also shown to undergo direct reduction with sodium borohydride, thus providing a new route for the deamination of aromatic amines. / Ph. D.

The anti-S2 peptides, the stabilizer and destabilizer, were designed to target myosin sub-fragment 2 (S2) in muscle. When the peptides are coupled to a heart-targeting molecule, they can reach the cardiomyocytes and interfere with cardiac muscle contraction. Monoclonal antibodies, MF20 and MF30, are also known to interact with light meromyosin and S2 respectively. The MF30 antibody compared to anti-S2 peptides and the MF20 antibody is used as a control to test the central hypothesis that: Both the anti-S2 peptides and antibodies bind to myosin S2 with high affinity, compete with MyBPC, and possibly interact with titin, in which case the anti-S2 peptides have further impact on myosin helicity and reach the heart with the aid of tannic acid to modulate cardiomyocytes' contraction in live mice. In this research, the effects of anti-S2 peptides and antibodies on myosin S2 were studied at the molecular and tissue levels. The anti-myosin binding mechanism to whole myosin was determined based on total internal reflectance fluorescence spectroscopy (TIRFS), and a modified cuvette was utilized to accommodate this experiment. The binding graphs indicated the cooperative binding of the peptides and antibodies with high affinity to myosin. Anti-myosin peptides and antibodies competition with Myosin Binding Protein C (MyBPC) was revealed through the super-resolution expansion microscopy using wildtype skeletal and cardiac myofibrils, and MyBPC knock-out cardiac myofibril. This new emerging technique depends on using the regular confocal microscope in imaging expanded myofibril after embedding in a swellable hydrogel polymer and digestion. A decrease in the fluorescent intensity at the C-zone was observed in myofibrils labeled with fluorescently labeled anti-S2 peptides or antibodies supporting the competition with MyBPC, which further was confirmed by the absence of this reduction at the C-zone in the knockout MyBPC cardiac tissue. The anti-S2 peptide's ability to reach inside the cardiomyocytes was tested by injecting fluorescently labeled anti-S2 peptides bound to tannic acid in live mice, the destabilizer peptide reached the heart 6X more than the stabilizer peptide. Some of the peptides labeled cardiac arterioles and T-tubules as detected by super-resolution microscopic images, meanwhile some peptides reached inside the cardiomyocytes and labeled some sarcomeres. This dissertation demonstrates the ability of anti-S2 peptides and antibodies in modifying myosin as they bind cooperatively with high affinity to myosin and compete with the regulatory protein MyBPC, in addition to the possible interaction between the stabilizer peptide and titin. Lastly, the peptides succeeded in labeling some cardiac sarcomeres in live mice.

No description available.

Urea and thiourea form inclusion compounds in which organic and organometallic guest molecules are confined within non-intersecting, unidirectional tunnels within a solid urea or thiourea host structure. In this thesis, studies have been undertaken using a variety of techniques to examine the properties of urea and thiourea inclusion compounds, with a view to improving the understanding of the forces controlling the ordering of these systems on a molecular scale. From single crystal X-ray diffraction studies of urea inclusion compounds carried out at room temperature, different modes of ordering between guest molecules in adjacent tunnels, dependent on the guest species present, have been observed. Extension of these studies to low temperature, in conjunction with powder X-ray diffraction, has revealed information on phase transitions in both the host and guest substructures of urea inclusion compounds. Computer modelling, using a mathematical model developed for application to one-dimensional inclusion compounds, has been applied to model properties of n-alkane/urea and dimethylketone/urea inclusion compounds. The model has also been applied to the chlorocyclohexane/thiourea inclusion compound. EXAFS spectroscopy has been carried out on α,w-dibromoalkane/urea inclusion compounds to examine the local structural properties of the guest molecules. Halogenocyclohexane/thiourea and halogenocyclohexanes included within the pores of several zeolite-type hosts have also been investigated to determine the conformation of the guest molecules when constrained to occupy a confined environment. Additional studies have examined the potential for the polymerisation of monomeric guest molecules within the tunnels of the organic host structure of perhydrotriphenylene, and a solid state NMR investigation on the effect of magic angle spinning on the observed NMR spectrum for metallocenes.

Noise is considered to be a physical form of environmental pollution which can influence the health of exposed persons. Excessive exposure to noise can interfere with performance at work and with the ability to relax or sleep. Also it may impair hearing and it can evoke other physiological and pathological symptoms to the detriment of health. The sources of noise may be local or general. Industrial processes are an important source of indoor or localised noise. Persons exposed to noise as a consequence of their employment are legally protected to some extent by European Directives and National Regulations which limit the maximum permissible noise levels to 85-90dB. A research project was launched with the full co-operation of the Don and Low Group of Companies, Forfar and Perth, Scotland. Study indicates that the proportion of employees who have noise-induced hearing loss is higher amongst those who work in higher than 85dB, (e.g. Group 1 < 85dB-11%; Group 2 85<90dB-44%; Group 3 90<95dB-44%; Group 4≥95dB-39% = 138% in total). In all groups social and economic status, sex, age and average number of years' service are almost identical. In general, the study indicates a higher number of employees suffered from ear problems between groups exposed to 85dB and more, (e.g. perforated eardrum, noise tinnitus, vertigo, wax in ears). The danger of noise has been studied in detail regarding the general health of employees as follows: 1. Sleep disturbance It appeared that most of the cases who suffered from sleep disturbance were found amongst employees exposed to greater than 85dB, averaging about 33%. On the other hand, only 8% of the employees in category <85dB complained of sleep disturbance. 2. Blood Pressure According to job categories 10% of employees had heart problems in job category higher than 85dB, but only one case reported heart problems in job categories less than 85dB. 3. Stress Smoking was one of the subjects studied in detail in this project and the results were significant. An average of 40% of employees were smokers among groups exposed to higher than 85dB compared to 10% of smokers among employees exposed to less than 85dB. Industrial accidents occur at a higher rate among employees who worked in noisy environments (~85dB) with regard to reported or unreported accidents. From the result of the research, industrial noise should be studied in a more comprehensive way to measure all effects of noise regarding employees health by using the statistical data and always noise should be controlled at source. Industrial noise is still a major danger to employees. From the results in this study it appears there is a need for more co-operation between employer and employee and not just depend on the health and safety regulations and try to solve the problem.

This dissertation aims to formulate a view of Arabian tribalism in the pre- Islamic period and its development in Islamic times. The first part assesses the historical usability of the literary source material of the Jahiliya. The focus is on oral historical traditions - the ayyam al- carab. These are found to have remained textually fluid until the time of their recording. This fluidity may have affected style and form but did not substantially affect certain historical elements. The more inter-tribal and less local the account was, the more reliable it is likely to be historically. A sample comparison between tribal hostility and tribal distribution showed that the accounts seem to be highly consistent. The second part of the thesis is concerned firstly with establishing a Jahili profile for two tribal groups; secondly with tracing the affairs of their descendants into the Umayyad period. The tribal groups of Taghlib and Ghatafan were picked for examination. Both were strong cohesive groups in the pre-Islamic period. In Islamic times, Taghlibis lose importance since they opted to remain Christian, thus, Taghlibis are virtually impossible to trace. Ghatafanis did join Islam on a far greater scale and are often mentioned in the Islamic period. After the second civil war Ghatafanis are only ever mentioned as individuals. Close kin continued to cooperate but cooperation above this level was only conducted within the Qaysi faction. The third part discusses changes in the tribal system. A review of the functions of modern tribal genealogies illuminates the process by which genealogies can change in order to reflect changing realities. Early Arabic genealogies are clearly seen to be also naturally dynamic and the subject of deliberate change. New links reflected new realities, particularly the political alliances forged under the Umayyads. A belief in a single progenitor led to a move towards creating genealogical links to one ancestor, while the conditions of the conquests let to a regionalization of tribalism. The professionalization of the Marwanid army enabled cross-regional tribal co-operation which resulted in dividing in two the Umayyad army and Arab genealogies.