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By a labelled graph we shall mean a set of “nodes,“ distinguishable from one another and denoted by A1, A2, …, and a collection of “edges” viz., pairs of nodes. We say that an edge “joins” the pair of nodes which specifies it. We further stipulate that at most one edge joins any two nodes, and that no edge joins a node to itself.
By a “colouring” of a graph in k colours we shall mean a mapping of the nodes of the graph onto a set of k colours C1, C2, …, Ck such that no two nodes which are joined by an edge are mapped onto the same colour. A graph so coloured in exactly k colours will be called a k-coloured graph. Since it is usually possible to colour a graph in more than one way, there will, in general, be many k-coloured graphs corresponding to a given graph.
The cell growth problem is a combinatorial problem which may be stated as follows: A plane animal is made up of cells, each of which is a square of unit area. It starts as a single cell, and grows by adding cells one at a time in such a way that the new cell has at least one side in contact with a side of a cell already present in the animal. The problem is to find the number of different animals of area n, it being understood that animals which can be transformed into each other by reflections or rotations of the plane will be regarded as the same animal.
The technique of image sharpening which allows high resolution images to be produced from ground-based telescopes is applied to the problem of photometry in crowded field regions - such as close to the cores of globular clusters. The conditions for image sharpening are discussed and the technique is demonstrated using simple objects (close double stars). Preliminary results from image sharpening of M15 are presented.
The rapid rise in syphilis cases has prompted a number of public health campaigns to assist men who have sex with men (MSM) recognize and present early with symptoms. This study aimed to investigate the temporal trend of the duration of self-report symptoms and titre of rapid plasma reagin (RPR) in MSM with infectious syphilis. Seven hundred and sixty-one syphilis cases in MSM diagnosed at the Melbourne Sexual Health Centre (MSHC) from 2007–2013 were reviewed. Median duration of symptoms and RPR titres in each year were calculated. The median durations of symptoms with primary and secondary syphilis were 9 [interquartile range (IQR) 6–14] days and 14 (IQR 7–30) days, respectively. The overall median titre of RPR in secondary syphilis (median 128, IQR 64–256) was higher than in primary syphilis (median 4, IQR 1–32) and in early latent syphilis (median 32, IQR 4–64). The median duration of symptoms for primary syphilis, secondary syphilis and titre of RPR level did not change over time. Public health campaigns were not associated with a significant shorter time from onset of symptoms to treatment. Alternative strategies such as more frequent testing of MSM should be promoted to control the syphilis epidemic in Australia.
There is little known regarding the transmissibility of human papillomavirus (HPV) between different sites in men who have sex with men (MSM) and heterosexual individuals. We conducted a retrospective analysis investigating all new patients attending the Melbourne Sexual Health Centre in Australia between 2002 and 2013. We describe the prevalence and ratio of the first episode of anogenital warts in MSM and heterosexual males and females. The proportion of new MSM clients with anal and penile warts was 4·0% (362/8978) and 1·6% (141/8978), respectively; which gave an anal-to-penile wart ratio of 1:2·6. About 13·7% (1656/12112) of heterosexual males had penile warts and 10·0% (1121/11166) of females had vulval warts, which yielded a penile-to-vulval wart ratio of 1:0·7. Penile–anal transmission has a higher ratio than penile–vulval transmission, suggesting that the anal epithelium may be more susceptible to HPV infection than the vulval epithelium in females; these ratios are important in modelling the control of HPV in MSM.
Data were extracted from the case records of UK patients admitted with laboratory-confirmed influenza A(H1N1)pdm09. White and non-White patients were characterized by age, sex, socioeconomic status, pandemic wave and indicators of pre-morbid health status. Logistic regression examined differences by ethnicity in patient characteristics, care pathway and clinical outcomes; multivariable models controlled for potential confounders. Whites (n = 630) and non-Whites (n = 510) differed by age, socioeconomic status, pandemic wave of admission, pregnancy, recorded obesity, previous and current smoking, and presence of chronic obstructive pulmonary disease. After adjustment for a priori confounders non-Whites were less likely to have received pre-admission antibiotics [adjusted odds ratio (aOR) 0·43, 95% confidence interval (CI) 0·28–0·68, P < 0·001) but more likely to receive antiviral drugs as in-patients (aOR 1·53, 95% CI 1·08–2·18, P = 0·018). However, there were no significant differences by ethnicity in delayed admission, severity at presentation for admission, or likelihood of severe outcome.
The development of widely accessible, effective psychological interventions for depression is a priority. This randomized trial provides the first controlled data on an innovative cognitive bias modification (CBM) training guided self-help intervention for depression.
One hundred and twenty-one consecutively recruited participants meeting criteria for current major depression were randomly allocated to treatment as usual (TAU) or to TAU plus concreteness training (CNT) guided self-help or to TAU plus relaxation training (RT) guided self-help. CNT involved repeated practice at mental exercises designed to switch patients from an unhelpful abstract thinking habit to a helpful concrete thinking habit, thereby targeting depressogenic cognitive processes (rumination, overgeneralization).
The addition of CNT to TAU significantly improved depressive symptoms at post-treatment [mean difference on the Hamilton Rating Scale for Depression (HAMD) 4.28, 95% confidence interval (CI) 1.29–7.26], 3- and 6-month follow-ups, and for rumination and overgeneralization post-treatment. There was no difference in the reduction of symptoms between CNT and RT (mean difference on the HAMD 1.98, 95% CI −1.14 to 5.11), although CNT significantly reduced rumination and overgeneralization relative to RT post-treatment, suggesting a specific benefit on these cognitive processes.
This study provides preliminary evidence that CNT guided self-help may be a useful addition to TAU in treating major depression in primary care, although the effect was not significantly different from an existing active treatment (RT) matched for structural and common factors. Because of its relative brevity and distinct format, it may have value as an additional innovative approach to increase the accessibility of treatment choices for depression.
Existing work in the mechanical behavior of thin films focuses mainly on measurement of macroscopic properties without strong correlation to microstructural features. We used transmission electron microscopy (TEM) to characterize the microstructures of free-standing copper thin films both before and after monotonic tensile deformation in an ex-situ thin film tensile testing system, as well as during in-situ loading in the TEM. The defect structures contributing to plastic deformation were investigated with an emphasis on comparison to mechanisms known to operate in bulk copper. The thin film exhibited much lower ductility (approximately 1%) than that normally observed in bulk form (greater than 40%). The predominant plastic deformation mechanisms did not include the typical dislocation activity that occurs in bulk copper, but rather greatly inhibited dislocation interactions typical of stages I and II hardening only. The absence of those structures normally found in tensile-deformed bulk copper is attributed to the differences in characteristic sizes of features within the microstructure available for deformation in bulk versus evaporated thin film material, that is, grain size and film thickness. The thin film ductility is an order of magnitude lower than what has been observed in bulk, ultrafine-grained copper, implying that a pure thin film effect on ductility exists and is significant. Microstructural features both near to and far from the fracture surface regions will be presented.
Samples of ground beef (225), pork (235) and chicken (200) were randomly selected from meat processing plants in the southwestern Ontario area. Supernatants of broth cultures of the samples were tested for verocytotoxins using a Vero cell assay. Neutralization of cytotoxic activity using antisera specific for three types of verocytotoxin (Verotoxin 1, Verotoxin 2 and Shiga-like toxin II) was performed on positive samples. Isolation of verocytotoxigenic Escherichia coli (VTEC) was attempted from positive samples. VTEC were confirmed as E. coli biochemically, tested for drug resistance, and serotyped. Based on neutralization studies, the prevalance of VTEC in beef and pork was at least 36·4% and 10·6%. respectively. This is much higher than has been reported from a survey of retail meats in which a method designed to detect only E. coli O 157.H7 was used. Isolations of VTEC were made from 10·4 % of the beef samples and 3·8 % of the pork samples. No VTEC were recovered from the chicken samples. The majority of VTEC isolates were susceptible to commonly used antimicrobial agents. A number of the serotypes of the VTEC isolates recovered have been associated with human disease; however, no VTEC of serotype O 157.H7 were isolated.
Rodent models of sepsis differ from clinical human disease in that humans make substantially less whole-body nitric oxide and have different cellular responses to endotoxin. Sheep, when exposed to endotoxin, behave in a manner more similar to humans. Many studies of rodent peripheral blood mononuclear cells (PBMCs) exposed to endotoxin demonstrate increased cationic amino acid transporter function (particularly through the y+ transporter) to supply arginine substrate to upregulated nitric oxide synthase. Whether this is true in sheep is not known. We have studied cationic amino acid transport in sheep PBMCs stimulated with endotoxin, using labelled lysine. PBMCs stimulated both in vitro and in vivo show an initial reduction in total and y+ lysine transport (after 1-2 h exposure to endotoxin): a previously undescribed effect of endotoxin. In in vitro activated cells, the reduction in y+ transport was prevented by the lipoxygenase inhibitor, nordihydroguaretic acid (NDGA), and the phospholipase inhibitor 4-bromophenacyl bromide (4-BPAB), but not cyclohexamide or a number of other inhibitors of intracellular second-messenger pathways. In contrast after 14 h incubation, the expected increase in total and y+ lysine transport was seen. The increase in y+ transport could be prevented by cyclohexamide, dexamethasone, ibuprofen, the protein kinase C inhibitor sphingosine, NDGA and 4-BPAB. These results suggest that in response to endotoxin exposure there is an initial decrease in y+ activity mediated by a lipoxygenase product, followed by a substantial increase in y+ activity mediated by the products of either cyclo-oxygenase or lipoxygenase. Cyclo-oxygenase and/or lipoxygenase inhibition might be useful in reducing arginine transport, and hence nitric oxide production, in these cells. Experimental Physiology (2003) 88.2, 201-208.
This paper reports the anti-cryptosporidial effects of, and concomitant amelioration of the histological changes in the gut of neonatal rats with intestinal cryptosporidiosis treated with the dinitroaniline, oryzalin. The ED50 was determined to be 7 mg/kg using twice daily doses administered for 3 consecutive days. A maximum inhibition of 85.5% was achieved at 25 mg/kg and this inhibition remained constant despite increasing the oryzalin dose to 200 mg/kg. Cryptosporidiosis significantly decreased the intestinal villus/crypt (VC) ratio by approximately 50% (duodenum = 2.3, jejunum = 2.5 and ileum = 1.7) when compared to uninfected untreated controls (duodenum = 4.3, jejunum = 5.9 and ileum = 4.5). Treatment with oryzalin doubled the VC ratio in the duodenum, jejunum and ileum following doses of 5 mg, 50 mg and 200 mg/kg respectively. Oryzalin concentrations in the small intestine contents and plasma were determined, using HPLC, at 0.5, 1 and 2 h after dosing. The much greater dose required to return VC ratios to normal in the ileum (200 mg/kg) compared to the duodenum (6.25 mg/kg) appeared to reflect the decreased concentration of the drug in the distal small intestine. Concentrations of oryzalin equivalent to the in vitro IC50 were maintained for 2 h in the first half of the small intestine following a single dose of 100 mg/kg.
North Atlantic harbour porpoises Phocoena phocoena (L.) face considerable energetic challenges, as they are relatively small marine mammals with an intense reproductive schedule and a cold-water habitat. Post-natal growth of these porpoises was described using ontogenetic allometry and body composition techniques. The cross-sectional sample contained robust calves, immature, and mature porpoises (n = 122) incidentally killed in commercial fishing operations between 1992 and 1998. Total mass and the mass of 26 body components were measured using a standard dissection protocol. Most body components grew similarly in female and male porpoises. Blubber, brain and skull were negatively allometric, while muscle and reproductive tissues exhibited positive allometry. Female heart, liver, intestine and mesenteric lymph node grew at significantly higher rates than in males. Male locomotor muscle and pelvic bones grew significantly faster than in females. High growth rates for visceral and reproductive organs in porpoises, relative to other mammals, may underlie their early maturation and support their intensive, annual reproductive schedule. Relative to other cetaceans, porpoises seem to allocate a larger percentage of their total body mass to blubber. This allocation to blubber, which is greatest in calves (37% of body mass), may provide harbour porpoises with the thermal insulation required to live in cold water. The factors influencing growth rates and differential investments in body composition seem to change at various stages of a porpoise's life. Energy allocation in porpoises seems to shift from an emphasis on developing an insulative blubber layer in young animals to preparing the body for annual reproduction at sexual maturity.
Coagulation and growth of aerosol particles subject to isotropic turbulence has been
explored using direct numerical simulations. The computations follow the trajectories
of 262 144 initial particles as they are convected by the turbulent flow field. Collision
between two parent particles leads to the formation of a new daughter particle with
the mass and momentum (but not necessarily the energy) of the parent particles. The
initially monodisperse population of particles will develop a size distribution over
time that is controlled by the collision dynamics. In an earlier study, Sundaram &
Collins (1997) showed that collision rates in isotropic turbulence are controlled by
two statistics: (i) the radial distribution of the particles and (ii) the relative velocity
probability density function. Their study considered particles that rebound elastically;
however, we find that the formula that they derived is equally valid in a coagulating
system. However, coagulation alters the numerical values of these statistics from the
values they attain for the elastic rebound case. This difference is substantial and must
be taken into consideration to properly predict the evolution of the size distribution
of a population of particles. The DNS results also show surprising trends in the
relative breadth of the particle size distribution. First, in all cases, the standard
deviation of the particle size distribution of particles with finite Stokes numbers is
much larger than the standard deviation for either the zero-Stokes-number or infinite-Stokes-number limits. Secondly, for particles with small initial Stokes numbers, the
standard deviation of the final particle size distribution decreases with increasing
initial particle size; however, the opposite trend is observed for particles with slightly
larger initial Stokes numbers. An explanation for these phenomena can be found by
carefully examining the functional dependence of the radial distribution function on
the particle size and Stokes number.
Of 219 elderly patients with a major depressive disorder (meeting RDC), 69 recovered sufficiently and consented to enter a two-year double-blind placebo-controlled trial of dothiepin. Survival analysis revealed that dothiepin reduced the relative risk of relapse by two and a half times. Past but not current serious physical illness was also associated with a favourable outcome, whereas a prolonged index depressive illness trebled the relative risk of relapse. In the light of previous research on prognosis it is suggested that elderly persons who recover from a major depressive illness should continue with antidepressant medication for at least two years, if not indefinitely.
It was observed that uninfected red cells resuspended in supernatant from Plasmodium falciparum cultures, then examined between a glass slide and cover-slip, assumed varying morphologies. A series of experiments suggested that P. falciparum releases molecules which cause red cells to become stomatocytic (cupped). These molecules, some of which are heat- stable, have an apparent molecular weight < 12 kDa, are released at or about schizogony, and do not bind tightly to erythrocytes.