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Experiments are presented on the Richtmyer–Meshkov instability (RMI) with a three-dimensional, multi-mode initial perturbation. The experiments use a vertical shock tube, where a stably stratified interface is formed between air and sulphur hexafluoride (SF$_6$) via counterflow. A perturbation is imposed at the interface by vertical oscillation of the gas column, forming Faraday waves. The interface is accelerated by a Mach 1.17 (in air) shock wave, and the development of the mixing region between the gases is investigated using particle image velocimetry. Following shock acceleration, a reflected shock wave from the bottom of the shock tube interacts with the mixing layer a second time (reshock). The experiment is initialized with both high and low amplitude perturbations to examine the effect of the perturbation amplitude on measured quantities. The instability growth exponent ($\theta$) is determined from the kinetic energy field using the width of the mixing layer and the decay of kinetic energy, which are found to be in agreement when the flow is most strongly excited. A growth exponent of $\theta \approx 0.5$ is found for all cases except the high-amplitude reshocked regime (where $\theta \approx 0.33$). High-amplitude experiments exhibit the transitional outer Reynolds number $(Re \equiv {h \dot {h}}/{\nu } > 10^4)$ required for mixing transition following the incident shock, and both experiments are elevated well above this threshold following reshock. However, neither set of experiments meet the more stringent requirements proposed by Zhou et al. (Phys. Rev.E, vol. 67, issue 5, 2003) which include the time dependent aspect of the RMI, an observation which is also made when examining the spectra.
Active participation in social activities is important for the wellbeing of older adults. This study explored benefits of active social engagement by evaluating whether relationships that comprise active involvement (e.g. co-engagement in activities) bring more social benefits (i.e. social support, companionship, positive social influence) than other relationships that do not involve co-engagement. A total of 133 adults ages 60 years and older living in a rural Midwestern city in the United States of America were interviewed once and provided information on 1,740 social network members. Among 1,506 social relationships in which interactions occurred at least once a month, 52 per cent involved engagement in social activities together and 35 per cent involved eating together regularly. Results of the generalised linear mixed model showed that relationships involving co-engagement were significantly more likely to also convey social support (i.e. emotional, instrumental, informational), companionship and social influence (encouragement for healthy behaviours) than relationships that do not involve co-engagement. Having more network members who provide companionship was associated with higher sense of environmental mastery, positive relations with others and satisfaction with social network. Interventions may focus on maintaining and developing such social relationships and ensuring the presence of social settings in which co-engagement can occur. Future research may explore whether increasing co-engagement leads to an enhanced sense of companionship and psychological wellbeing.
The relationship between depression and sexual behaviour among men who have sex with men (MSM) is poorly understood.
Aims
To investigate prevalence and correlates of depressive symptoms (Patient Health Questionnaire-9 score ≥10) and the relationship between depressive symptoms and sexual behaviour among MSM reporting recent sex.
Method
The Attitudes to and Understanding of Risk of Acquisition of HIV (AURAH) is a cross-sectional study of UK genitourinary medicine clinic attendees without diagnosed HIV (2013–2014).
Results
Among 1340 MSM, depressive symptoms (12.4%) were strongly associated with socioeconomic disadvantage and lower supportive network. Adjusted for key sociodemographic factors, depressive symptoms were associated with measures of condomless sex partners in the past 3 months (≥2 (prevalence ratio (PR) 1.42, 95% CI 1.17–1.74; P=0.001), unknown or HIV-positive status (PR 1.43, 95% CI 1.20–1.71; P<0.001)), sexually transmitted infection (STI) diagnosis (PR 1.46, 95% CI 1.19–1.79; P<0.001) and post-exposure prophylaxis use in the past year (PR 1.83, 95% CI 1.33–2.50; P<0.001).
Conclusions
Management of mental health may play a role in HIV and STI prevention.
Coronal Multi-channel Polarimeter (CoMP-S), developed by HAO/NCAR, has been introduced to regular operation at the Lomnicky Peak Observatory (High Tatras in northern Slovakia, 2633 m a.s.l.) of the Astronomical Institute of Slovak Academy of Sciences. We present here the technical parameters of the current version of the instrument and its potential for observations of prominences in the visual and near-IR spectral regions. The first results derived from observations of prominences in the Hα emission line taken during a coordinated observing campaign of several instruments in October 2012 are shown here.
A cloud monitor has been developed for use with cosmic ray air shower fluorescence detectors, the High Resolution Fly's Eye and the Pierre Auger Observatory. This is based on an infrared thermopile device which, unlike previous such monitors, requires no moving chopper and is suitable for unattended operation over long periods of time.
The aim of this book is to highlight and begin to give 'voice' to some of the notable 'silences' evident in recent years in the study of contentious politics. The seven co-authors take up seven specific topics in the volume: the relationship between emotions and contention; temporality in the study of contention; the spatial dimensions of contention; leadership in contention; the role of threat in contention; religion and contention; and contention in the context of demographic and life-course processes. The seven spent three years involved in an ongoing project designed to take stock, and attempt a partial synthesis, of various literatures that have grown up around the study of non-routine or contentious politics. As such, it is likely to be viewed as a groundbreaking volume that not only undermines conventional disciplinary understanding of contentious politics, but also lays out a number of provocative new research agendas.
The antibody response of the appropriate hosts (cattle) to Taenia saginata larvae was compared with that of an inappropriate host (Balb/c mice) using gel electrophoresis followed by immunoelectrotransfer blot techniques (Western blotting). Three groups of cattle were included, those known to be resistant to challenge infection because of repeated oral challenge with T. saginata eggs over a 1-year period, a previously infected but known susceptible group and a group of uninfected controls. Serum from the mice and the two groups of infected cattle contained antibodies recognizing different ‘target’ antigens, some of which may be related to host resistance. The potential value of the technique of Western blotting in dissecting the humoral response of a particular host species to parasitic infection and in the identification of those antigens suitable for the production of effective vaccines is discussed.
In many problems of applied mathematics, science, engineering or economics, an energy expenditure or its analogue can be approximated by upper and lower bounds. This book provides a unified account of the theory required to establish such bounds, by expressing the governing conditions of the problem, and the bounds, in terms of a saddle functional and its gradients. There are several features, including a chapter on the Legendre dual transformation and some of its singularities. Many substantial examples and exercises are included, especially from the mechanics of fluids, elastic and plastic solids and from optimisation theory. The saddle functional viewpoint gives the book a wide scope. The treatment is straightforward, the only prerequisite being a basic knowledge of the calculus of variations. Part of the book is based on final-year undergraduate courses. This is developed into an account which will interest a wide range of students and professionals in applied mathematics, engineering, physics and operations research.
Excretions and secretions (ES) and somatic components of 4, 8, 12 and 16-week-old Taenia saginata metacestodes were biosynthetically radio-isotope labelled by incubating the larvae in the presence of [35S]methionine. Despite their small size, 4-week-old metacestodes produced as much isotope-labelled ES/parasite as older metacestodes, indicating a proportionately greater metabolic activity of the parasite at this age. In situ the 4-week-old metacestodes were surrounded by a marked granulomatous cellular infiltrate which had largely resolved around 8-week-old metacestodes. Examination of the isotope-labelled ES by SDS-PAGE revealed distinct age-specific components from 4- and 12-week-old metacestodes and other ES components which were produced by all the ages of metacestodes examined. In comparison the labelled somatic components were conserved. Antigenic characterization of the ES by immunoprecipitation against a panel of clinically defined bovine sera combined with SDS-PAGE analysis, identified some highly immunogenic parasite products and others which did not elicit an antibody response demonstrable by immunoprecipitation. These components are of interest in relation to the host/parasite relationship, to the construction of diagnostic assays for the detection of T. saginata cysticercosis, and to the immunity that cattle develop against this parasite.
Associations between social rank, immunodepression and resistance to Babesia microti infection within single-sex groups of male house mice suggest rank-dependent suites of response involving different hormonal and immune changes in relation to aggressive behaviour and group size prior to infection. Reduced resistance among high-ranking males was associated with increased serum testosterone and corticosterone concentration and reduced serum immunoglobulin, but was independent of group size. Among low-ranking males, hormonal changes were not associated with resistance to B. microti but changes in corticosterone concentration and measures of immunodepression increased with group size and aggressive behaviour. The results concur with earlier findings suggesting differences between high- and low-ranking mice in their physiological responses to social experience and consequently reduced resistance to B. microti infection among high-ranking individuals.
Taenia saginata cyst fluid proteins from 4, 8, 12 and 16-week-old cysticerci were analysed by a combination of direct I radio-isotope labelling, immunoprecipitation using a panel of sera from infected cattle infected with T. saginata and SDS–PAGE. Protein antigens of 12, 14, 16, 20 and 26 kDa were identified in all of the cyst fluids examined. These were immunogenic and were precipitated by serum taken from cattle from 8 weeks after infection onwards and were therefore considered to be of diagnostic potential. A 185 kDa protein antigen found only in the cyst fluid of 4-week-old cysticerci and a 43 kDa protein antigen first detected in cyst fluid from 8-week-old cysticerci were also identified but were considered to be of more limited diagnostic potential due to their restricted presence. An apparently non-immunogenic 67 kDa protein, found in all the cyst fluids examined, may have been host serum albumin.
Direct surface I radio-isotope labelling techniques and SDS—PAGE analysis were used to compare the proteins and lentil—lectin adherent glycoproteins of the bovine stage of viable Taenia saginata larvae at three points in their development, the invasive oncospheres, immature (4-week-old) and mature (12 to 16-week-old) cysticerci. Some proteins and glycoproteins were present on all three of the ages of the parasite examined but there were also distinct age-specific proteins and glycoproteins detected on oncospheres and 4-week-old cysticerci and a marked difference between the protein/glycoprotein profiles of the parasite was apparent at these earlier stages of development and the mature cysticerci. The latter were characterized by the presence of high, 160–200 kDa molecular weight, lysine rich, glycoproteins, whereas small 16 and 18 kDa glycoproteins and a reduction-sensitive 23 kDa glycoprotein were first detected on 4-week-old immature cysticerci. Antigenic characterization of the isotope-labelled proteins and glycoproteins by immunoprecipitation against a panel of clinically defined bovine sera combined with SDS–PAGE analysis indicated that relatively few proteins were precipitated by sera from T. saginata-infected cattle as compared to the glycoproteins. However, both protein and glycoprotein antigens of possible protective and/or diagnostic significance were identified from oncospheres and cysticerci.
Unrelated and initially unfamiliar male CFLP mice, maintained for different periods in groups of 6, differed in both their rate of clearance of Babesia microti and the time taken to reach peak parasitaemia in relation to their aggressive behaviour within groups prior to infection. Males maintained in groups for shorter periods and showing more aggression within their group were slower to clear infection and males showing more marked external evidence of aggressive interaction reached a peak of parasitaemia sooner. Serum IgG and corticosterone analyses were consistent with increased aggression causing stress-induced immunodepression but relationships with aggression and social status were not simple. Males showing more aggression tended to enter their groups with higher levels of corticosterone and, to a lesser extent, reduced levels of IgG compared with other mice. The results thus suggest that increased susceptibility to disease may be a cost to males aggressively maintaining high social status.
A murine model using Heligmosomoides polygyrus and Trypanosoma congolense has been developed for studying the effects of concurrent chronic gastrointestinal nematode and trypanosome infections. Female outbred mice were infected either with 500 infective larvae (L3) of H. polygyrus or with 104 bloodstream forms of T congolense or both. In concurrent infections, animals were dosed with both parasites simultaneously or the trypanosomes were injected 5 or 10 days after the mice were infected with the nematode. The course of infection was monitored by routine parasitological and immunological techniques for 30 days after the H. polygyrus infection. Concurrently infected mice were severely compromised, except when T. congolense was superimposed on a 10-day-old (adult) H. polygyrus infection. In H. polygyrus-infected mice, simultaneous or subsequent infection with trypanosomes did not markedly influence worm establishment or fecundity, but the female worms were slightly stunted. Surviving mice displayed a markedly reduced antibody response to H. polygyrus antigens and a slightly reduced antibody response to T. congolense antigens.
Existing languages provide good support for typeful programming of stand-alone programs. In a distributed system, however, there may be interaction between multiple instances of many distinct programs, sharing some (but not necessarily all) of their module structure, and with some instances rebuilt with new versions of certain modules as time goes on. In this paper, we discuss programming-language support for such systems, focussing on their typing and naming issues. We describe an experimental language, Acute, which extends an ML core to support distributed development, deployment, and execution, allowing type-safe interaction between separately built programs. The main features are (1) type-safe marshalling of arbitrary values; (2) type names that are generated (freshly and by hashing) to ensure that type equality tests suffice to protect the invariants of abstract types, across the entire distributed system; (3) expression-level names generated to ensure that name equality tests suffice for type safety of associated values, for example, values carried on named channels; (4) controlled dynamic rebinding of marshalled values to local resources; and (5) thunkification of threads and mutexes to support computation mobility. These features are a large part of what is needed for typeful distributed programming. They are a relatively lightweight extension of ML, should be efficiently implementable, and are expressive enough to enable a wide variety of distributed infrastructure layers to be written as simple library code above the byte-string network and persistent store APIs. This disentangles the language run-time from communication intricacies. This paper highlights the main design choices in Acute. It is supported by a full language definition (of typing, compilation, and operational semantics), by a prototype implementation, and by example distribution libraries.
The response of a mononuclear, heteroleptic titanium alkoxide [(OPy)2Ti(4MP)2, where OPy = pyridinecarbinol; NC5H4(CH2O) and 4MP = 4-mercaptophenol; OC6H4(SH)] to ultraviolet (UV) irradiation in dilute solution and in solid-state samples has been measured. Vibrational spectroscopy [Fourier transform infrared (FTIR) absorption and Raman scattering] was used to monitor changes in molecular structure upon exposure to 337.1- and 365-nm light. Assignment of spectral features to vibrational modes of the molecule was aided by a normal-mode analysis of the energy-minimized molecular structure within a density-functional theory framework. Photoinduced decreases in peak areas were observed in both FTIR spectra of the precursor solutions and Raman data collected from solution-cast films of the precursor material. These changes were associated with vibrational modes localized at the 4MP ligands. Conversely, no significant modification of vibrational structure associated with the OPy moiety was observed under the excitation conditions examined. In a related study, thin films of the precursor were cast, sampled, and irradiated with UV light in scintillation vials under hydrated air (40% relative humidity) and dry Ar to evaluate the influence of local atmospheric composition on the photoresponse. An increase in the magnitude of photoinduced vibrational changes was observed in the moist-air environment, again associated primarily with the 4MP ligand. The results support an interpretation of these structural changes in terms of a preferential enhancement of hydrolysis at the 4MP site under these conditions. These findings are discussed in the context of an optically driven molecular assembly strategy based on the photoinitiation of intermolecular bonding at selected sites about the metal center.
The effects of ultraviolet irradiation on a heteroleptic titanium alkoxide ((OPy)2Ti(4MP)2) have been investigated. The molecule has been studied in solution and in thin film form using FTIR and Raman spectroscopies. Quantum computational modeling was used to associate vibrational modes with structural moieties present in the molecule. In all cases examined, a preferential photoinduced modification in vibrational resonances linked to the 4-mercaptophenol (4MP) ligand was observed. In contrast, little or no change was exhibited in the vibrational structure of the OPy ligands.