Geographic variation in hybridization and ecological differentiation between three syntopic, morphologically similar species of montane lizards.

To understand factors shaping species boundaries in closely related taxa, a powerful approach is to compare levels of genetic admixture at multiple points of contact and determine how this relates to intrinsic and extrinsic factors, such as genetic, morphological and ecological differentiation. In the Australian Alps, the threatened alpine bog skink Pseudemoia cryodroma co-occurs with two morphologically and ecologically similar congeners, P. entrecasteauxii and P. pagenstecheri, and all three species are suspected to hybridize. We predicted that the frequency of hybridization should be negatively correlated with genetic divergence, morphological differentiation and microhabitat separation. We tested this hypothesis using a mitochondrial locus, 13 microsatellite loci, morphological and microhabitat data and compared results across three geographically isolated sites. Despite strong genetic structure between species, we detected hybridization between all species pairs, including evidence of backcrossed individuals at the two sites where all three species are syntopic. Hybridization frequencies were not consistently associated with genetic, morphological or ecological differentiation. Furthermore, P. entrecasteauxii and P. pagenstecheri only hybridized at the two sites where they are syntopic with P. cryodroma, but not at the largest site where P. cryodroma was not recorded, suggesting that P. cryodroma may serve as a bridging species. This study reveals the complex dynamics within a three species hybrid zone and provides a baseline for assessing the impact of climate change and anthropogenic habitat modification on future hybridization frequencies.

Precision mapping of laser-driven magnetic fields and their evolution in high-energy-density plasmas.

The magnetic fields generated at the surface of a laser-irradiated planar solid target are mapped using ultrafast proton radiography. Thick (50 µm) plastic foils are irradiated with 4-kJ, 2.5-ns laser pulses focused to an intensity of 4×10^{14} W/cm^{2}. The data show magnetic fields concentrated at the edge of the laser-focal region, well within the expanding coronal plasma. The magnetic-field spatial distribution is tracked and shows good agreement with 2D resistive magnetohydrodynamic simulations using the code draco when the Biermann battery source, fluid and Nernst advection, resistive magnetic diffusion, and Righi-Leduc heat flow are included.

Impact of 6 different intestinal bacteria on broiler breeder sperm motility in vitro.

Male fertility is often evaluated by measuring sperm parameters, including concentration, viability, and motility. This is important because after copulation occurs, sperm must overcome many barriers in the female reproductive tract to fertilize the ovum. In mammalian species, sperm have been shown to have reduced motility when bacteria are present. In male broiler breeders, bacteria have been associated with spermatozoa, but their effect on motility has not been investigated. The sperm quality index is a modern rapid method of evaluating avian sperm motility. Therefore, the objective of this study was to use the sperm quality index to determine if broiler breeder sperm motility is reduced when semen is exposed to various bacteria. In this experiment, semen was collected from 20 broiler breeders to obtain a pooled neat semen sample. Six different intestinal bacteria, Salmonella enterica, Escherichia coli, Campylobacter jejuni, Clostridium bifermentans, Lactobacillus acidophilus, and Bifidobacterium animalis were cultured overnight. For each bacterium, 50 µL of semen was diluted in 450 µL of saline, sterile broth, or the overnight culture, creating 3 treatments. The experiment was repeated twice. In each treatment, 3 replicates were evaluated at 0 and 10 min postinoculation, creating a completely randomized design with a split plot over time. Also, the pH was measured for each treatment at 0 and 10 min. The results indicated that all broths containing bacteria immediately reduced broiler breeder sperm motility when compared with the controls (P < 0.0001), but broths containing Bifidobacterium or Lactobacillus virtually made sperm immotile. Although broth containing Salmonella, Campylobacter, and Bifidobacterium immediately reduced sperm motility, the reduction did not change over time. Broths containing E. coli, Clostridium, and Lactobacillus reduced sperm motility immediately, but over time motility continued to decrease. However, pH was increased when semen was exposed to the E. coli and Campylobacter treatment, but when semen was exposed to Bifidobacterium and Lactobacillus treatments, pH was reduced. In conclusion, the results indicate that bacteria can reduce broiler breeder sperm motility upon exposure.

Observation of self-similarity in the magnetic fields generated by the ablative nonlinear Rayleigh-Taylor instability.

Magnetic fields generated by the nonlinear Rayleigh-Taylor growth of laser-seeded three-dimensional broadband perturbations were measured in laser-accelerated planar targets using ultrafast proton radiography. The experimental data show self-similar behavior in the growing cellular magnetic field structures. These observations are consistent with a bubble competition and merger model that predicts the time evolution of the number and size of the bubbles, linking the cellular magnetic field structures with the Rayleigh-Taylor bubble and spike growth.

Magnetic field generation by the Rayleigh-Taylor instability in laser-driven planar plastic targets.

Magnetic fields generated by the Rayleigh-Taylor instability were measured in laser-accelerated planar foils using ultrafast proton radiography. Thin plastic foils were irradiated with ∼4-kJ, 2.5-ns laser pulses focused to an intensity of ∼10(14) W/cm(2) on the OMEGA EP Laser System. Target modulations were seeded by laser nonuniformities and amplified during target acceleration by the Rayleigh-Taylor instability. The experimental data show the hydrodynamic evolution of the target and MG-level magnetic fields generated in the broken foil. The experimental data are in good agreement with predictions from 2-D magnetohydrodynamic simulations.

Evaluating 3 gas-delivery systems for culturing Campylobacter jejuni in a microaerophilic environment.

Campylobacter spp. require a microaerophilic environment (80% N(2), 10% CO(2), 5% H(2), and 5% O(2)) for growth. Since the late 1800s, several systems for creating and maintaining specific microbial atmospheres have been developed and applied. The objective of this study was to evaluate Campylobacter jejuni growth by means of 3 commonly used gas-delivery systems for generating a microaerophilic environment: automated, gas-generating sachet, and plastic storage bag. Pure culture C. jejuni cells were suspended in Brucella broth and spread onto campy cefex agar plates. For the automated gas-delivery system, plates were positioned in a Mart anaerobic jar and flushed with a microaerophilic gas mixture using an Anoxomat Mart II system (Mart Microbiology B. V., Netherlands). For the sachet samples, plates were placed in a Mart anaerobic jar and 3 Gaspak EZ campy sachets (Becton Dickinson and Company, Franklin Lakes, NJ) were activated to induce a microaerophilic gas environment. The plates placed in plastic storage bags were flushed with a microaerophilic gas mixture from a premixed tank. For all 3 systems, plates were placed in a low-temperature incubator at 42°C for 24 h. After 24 h, plates were removed from the incubator and colonies were counted. The entire experiment was repeated 5 times. Results indicated no significant difference in colony counts among the gas-delivery systems tested, but colonies grown under the sachet-generated environment were smaller than colonies in the other 2 methods. Smaller colonies could have resulted from the type of media used or the length of time the plates were incubated. In conclusion, all 3 gas-delivery methods were able to produce similar Campylobacter growth results. Initial and long-term costs of equipment, as well as laboratory space availability, may be influential when choosing a gas-delivery method for generating a microaerophilic environment.

Numerical modeling of fast electron generation in the presence of preformed plasma in laser-matter interaction at relativistic intensities.

Fast electron generation in the presence of coronal plasma in front of a solid target (typically referred to as preformed plasma) in laser-matter interaction in the intensity range of 10(19)-10(21) W/cm(2) is studied in a one-dimensional slab approximation with particle-in-cell (PIC) simulations. Three different preformed plasma density scale lengths of 1, 5, and 15 µm are considered. We report an increase in both mean and maximum energy of generated fast electrons with an increase in the preformed plasma scale length (in the range 1-15 µm). The heating of plasma electrons is predominantly due to their stochastic motion in counterpropagating electromagnetic (EM) waves (incident and reflected waves) and the presence of a longitudinal electric field produced self-consistently inside the preformed plasma. The synergetic effects of this longitudinal electric field and EM waves responsible for the efficient preformed plasma electrons heating are discussed.

Fast advection of magnetic fields by hot electrons.

Experiments where a laser-generated proton beam is used to probe the megagauss strength self-generated magnetic fields from a nanosecond laser interaction with an aluminum target are presented. At intensities of 10(15) W cm(-2) and under conditions of significant fast electron production and strong heat fluxes, the electron mean-free-path is long compared with the temperature gradient scale length and hence nonlocal transport is important for the dynamics of the magnetic field in the plasma. The hot electron flux transports self-generated magnetic fields away from the focal region through the Nernst effect [A. Nishiguchi, Phys. Rev. Lett. 53, 262 (1984)] at significantly higher velocities than the fluid velocity. Two-dimensional implicit Vlasov-Fokker-Planck modeling shows that the Nernst effect allows advection and self-generation transports magnetic fields at significantly faster than the ion fluid velocity, v(N)/c(s)≈10.

Dietary poorly absorbed, short-chain carbohydrates increase delivery of water and fermentable substrates to the proximal colon.

BACKGROUND: Functional gut symptoms are induced by inclusion and reduced by dietary restriction of poorly absorbed short-chain carbohydrates (FODMAPs), but the mechanisms of action remain untested. AIMS: To determine the effect of dietary FODMAPs on the content of water and fermentable substrates of ileal effluent. METHODS: Twelve ileostomates without evidence of small intestinal disease undertook two 4-day dietary periods, comprising diets differing only in FODMAP content in a randomized, cross-over, single-blinded intervention study. Daytime (14 h) ileal effluent was collected on day four of each diet. Patients rated effluent volume and consistency on a 10-cm visual analogue scale. The FODMAP content of the diet and effluent was measured. RESULTS: Ingested FODMAPs of 32% (range 6-73%) was recovered in the high FODMAP diet effluent. Effluent collection weight increased by a mean of 22% (95% CI, 5-39), water content by 20% (2-38%) and dry weight by 24% (4-43%) with the high compared to low FODMAP diet arm. Output increased by 95 (28-161) mL. Volunteers perceived effluent consistency was thicker (95% CI, 0.6-1.9) with the low FODMAP diet than with the high FODMAP diet (3.5-6.1; P = 0.006). CONCLUSIONS: These data support the hypothetical mechanism; FODMAPs increase delivery of water and fermentable substrates to the proximal colon.

Germicidal activity of antimicrobials and VIOlight Personal Travel Toothbrush sanitizer: an in vitro study.

OBJECTIVES: The study evaluated the antibacterial effect of VIOlight (VL) Personal Travel Toothbrush Sanitizer on biofilms after toothbrush exposure to human saliva compared to Listerine Antiseptic (LA), 3% hydrogen peroxide (3%HP) and water. METHODS: Twenty toothbrush heads (n=5/Gp) were immersed in saliva and to allow for bacterial growth and biofilm formation for 24h. VL sanitizer and antiseptic(s) were used for 7 min; after treatment, brush heads were rinsed and placed into 10 mL of 2x AOAC Letheen Broth, sonicated and vortexed for 10s. Tenfold serial dilutions were prepared and plated and incubated aerobically and anaerobically. Log(10)CFU/mL data were compared utilizing ANOVA (p<0.05). RESULTS: Results showed 3%HP with significantly lower counts than LA, VL and control for aerobic and anaerobic bacteria. LA had significantly lower counts than VL and control for both types of bacteria and VIOlight had significantly lower counts than the control for aerobic bacteria. 3%HP and LA were most effective in rapidly killing bacteria when compared to VIOlight. CONCLUSIONS: Results showed that 3% hydrogen peroxide was most effective in reducing the numbers of both aerobic and anaerobic bacteria present on the toothbrush heads. Under the same test conditions, Listerine Antiseptic was shown to be secondarily effective for the same bacteria while the VIOlight unit was the least effective when compared to the other treatment groups.

Delayed adverse reactions to total-dose intravenous iron polymaltose.

The rate of infusion reactions to total-dose intravenous iron polymaltose is very low, but the frequency and severity of adverse reactions following the infusion are unknown. In 50 consecutive patients, adverse reactions developed up to 2 days after the infusion in 26% and lasted 1-8 days (median 4). Severe systemic reactions occurred in 8%. Patients should be warned of the chance of delayed reactions and an alternative iron preparation should be considered if parenteral iron is again indicated.

Hot-electron temperature and laser-light absorption in fast ignition.

Experimental data [F. N. Beg, Phys. Plasmas 4, 447 (1997)10.1063/1.872103] indicate that for intense short-pulse laser-solid interactions at intensities up to 5 x 10(18) W cm(-2) the hot-electron temperature proportional, variant(Ilambda(2)) (1/3). A fully relativistic analytic model based on energy and momentum conservation laws for the laser interaction with an overdense plasma is presented here. A general formula for the hot-electron temperature is found that closely agrees with the experimental scaling over the relevant intensity range. This scaling is much lower than ponderomotive scaling. Examination of the electron forward displacement compared to the collisionless skin depth shows that electrons experience only a fraction of a laser-light period before being accelerated forward beyond the laser light's penetration region. Inclusion of backscattered light in a modified model indicates that light absorption approaches 80%-90% for intensity >10(19) W cm(-2).

Quality, clinical influence and tolerance of computed tomography enteroclysis in patients with suspected small bowel disease.

BACKGROUND: Computed tomography enteroclysis (CTE) may be superior to other small bowel imaging techniques, detecting subtle mucosal lesions and extraluminal pathology. This study aimed to define the technical success, clinical influence and tolerance of CTE in patients with suspected small bowel disease. METHODS: CTE scans of 42 consecutive patients (aged 21-78 years, 12 men) were reviewed by a single radiologist for technical adequacy and diagnosis. A panel of gastroenterologists reviewed clinical information. At a telephone interview, tolerance of CTE was graded numerically from 1 (unbearable) to 10 (excellent) and descriptively as unbearable, fair, good or excellent. RESULTS: Good or optimal distension of small bowel was achieved in 98%. The entire small bowel was imaged in 88%. Eighteen patients had a normal small bowel, whereas 12 (29%) had active small bowel Crohn disease, 4 intussusception, 3 small bowel diverticula and 7 having other diagnoses. Mesenteric lymphadenopathy was evident in 11 and fat stranding in 5. CTE resulted in a new or altered diagnosis in 13 (31%) patients and identified more extensive Crohn disease in a further 8 (19%). A change in management plan was instituted in 18 (43%) patients, with subsequent clinically significant improvement in 12. 33 (85%) described the procedure as 'fair' or 'unbearable' rather than 'good' or 'excellent'. The median tolerance score was 3 out of 10. CONCLUSION: CTE provided high-quality images in nearly all patients and had an effect on diagnosis, management or outcome in most, but was not well tolerated.

Systematic review: The evidence base for long-term management of coeliac disease.

BACKGROUND: While gluten-free diet is an effective treatment for coeliac disease, the need for and goals of long-term management of patients are poorly defined. AIM: To review systematically the complications and associations of coeliac disease, to identify potential risk factors, to define ways of assessing risk factors and to provide a strategy for management. METHODS: Review of medical literature from 1975. RESULTS: There is an increasing list of potential complications and/or conditions associated with coeliac disease, in particular, autoimmune disease, malignancy and bone disease. Risk factors that may predict or influence long-term outcomes include genetic susceptibility, environmental factors predominantly gluten ingestion, persistent small intestinal inflammation/injury and nutritional deficiencies. Genotyping of patients is yet to have an established clinical role in long-term management. Assessment of adherence to the gluten-free diet largely relies upon skilled dietary history, but the ultimate test is duodenal histopathology, which is the only currently established means of assessing healing. Symptoms, serology or other non-invasive means are poor predictors of healing and the likelihood of complications. CONCLUSION: Evidence (albeit limited) that adherence to a gluten-free diet and mucosal healing prevent and/or ameliorate complications indicates that a planned long-term strategy for follow-up is essential.

Modulation of AMPA receptor GluR1 subunit phosphorylation in neurons by the intravenous anaesthetic propofol.

BACKGROUND: The ionotropic glutamate receptor is a potential molecular site in the central nervous system that general anaesthetics may interact with to produce some of their biological actions. Protein phosphorylation has been well documented to occur in the intracellular C-terminal domain of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) subtype of glutamate receptors, which represents a pivotal mechanism for the post-translational modulation of AMPA receptor functions. In this study, we investigated a possible influence of an i.v. anaesthetic agent propofol on the phosphorylation of AMPA receptor GluR1 subunits in cultured neurons. METHODS: The effect of propofol on phosphorylation of GluR1 subunits at serine 831 and 845 was assayed in cultured rat striatal and cortical neurons by western blot with phospho- and site-specific antibodies. RESULTS: Propofol consistently elevated phosphorylation of GluR1 subunits at the C-terminal serine 845 site in both striatal and cortical neurons. The elevation in phosphorylation was concentration-dependent and started at a low concentration (3 microM). This increase in serine 845 phosphorylation was rapid and sustained during the entire course of propofol exposure. In contrast to serine 845, phosphorylation of GluR1 at serine 831 was not altered by propofol in striatal and cortical neurons. Total GluR1 abundance remained unchanged in response to propofol incubation. CONCLUSIONS: These data indicate that propofol possesses the ability to upregulate AMPA receptor GluR1 subunit phosphorylation at a specific serine 845 site in neurons and provide evidence supporting the AMPA receptor as a molecular target for general anaesthetics.

Wire initiation critical for radiation symmetry in z-pinch-driven dynamic hohlraums.

Axial symmetry in x-ray radiation of wire-array z pinches is important for the creation of dynamic hohlraums used to compress inertial-confinement-fusion capsules. We present the first evidence that this symmetry is directly correlated with the magnitude of the negative radial electric field along the wire surface. This field (in turn) is inferred to control the initial energy deposition into the wire cores, as well as any current shorting to the return conductor.

Dynamics of cylindrically converging precursor plasma flow in wire-array Z -pinch experiments.

This paper summarizes the present understanding of the processes leading to precursor column formation in cylindrical wire arrays on the 1 MA MAGPIE generator at Imperial College London. Direct experimental measurements of the diameter variation during the collapse and formation phase of the precursor column are presented, along with soft x-ray emission, and quantitative radiography. In addition, data from twisted cylindrical arrays are presented which give additional information on the behavior of coronal plasma generated in wire array z pinches. Three stages in precursor column formation are identifiable from the data: broad initial density profile, rapid contraction to small diameter, and slow expansion after formation. The correlation of emission to column diameter variation indicates the contraction phase is a nonlinear collapse resulting from the increasing on-axis density and radiative cooling rate. The variation in the minimum diameter is measured for several array materials, and data show good agreement with a pressure balance model. Comparison of column expansion rates to analytical models allows an estimate of column temperature variation, and estimates of the current in the column are also made. Formation data are in good agreement with both fluid and kinetic modeling, but highlight the need to include collisionless flow in the early time behavior.

Body mass, weight control behaviours, weight perception and emotional well being in a multiethnic sample of early adolescents.

OBJECTIVE: To investigate weight perception, dieting and emotional well being across the range of body mass index (BMI) in a population-based multiethnic sample of early adolescents. DESIGN: Cross-sectional population-based survey. SUBJECTS: In total, 2789 adolescents 11-14 years of age from three highly deprived regional authorities in East London, in 2001. MEASUREMENTS: Data were collected by student-completed questionnaire on weight perception, dieting history, mental and physical health, health behaviours, social capital and sociodemographic factors. Height and weight were measured by trained researchers. Overweight was defined as BMI > or =85th centile and obesity as BMI > or =98th centile. Underweight was defined as BMI< or =15th centile. RESULTS: In all, 73% were from ethnic groups other than white British. Valid BMI were available for 2522 subjects (90.4%) of whom 14% were obese. Only 20% of overweight boys and 51% of overweight girls assessed their weight accurately. Accuracy of weight perception did not vary between ethnic groups. In all, 42% of girls and 26% of boys reported current dieting to lose weight. Compared with white British teenagers, a history of dieting was more common among Bangladeshi, Indian and mixed ethnicity boys and less likely among Pakistani girls. Self-esteem was not associated with BMI in girls but was significantly lower in obese boys than those of normal weight (P=0.02). Within ethnic subgroups, self-esteem was significantly lower in overweight white British boys (P=0.03) and obese Bangladeshi boys (P=0.01) and Bangladeshi girls (P=0.04), but significantly higher in obese black African girls (P=0.01) than those of normal weight. Obese young people had a higher prevalence of psychological distress (P=0.04), except among Bangladeshi teenagers, where overweight and obese young people had less psychological distress than those of normal weight (P=0.02). Birth outside the UK was associated with reduced risk of obesity in girls (P=0.02) but not with history of dieting, weight perception or psychological factors in either gender. CONCLUSION: High levels of current dieting for weight control and inaccurate perception of body mass are common across all ethnic groups. However, dieting history and the associations of obesity with self-esteem and psychological distress vary between ethnic groups. Interventions to prevent or treat obesity in black or minority ethnicity groups must consider cultural differences in the relationship between body mass, self-esteem and psychological distress.

Ion viscous heating in a magnetohydrodynamically unstable Z pinch at over 2 x 10(9) Kelvin.

Pulsed power driven metallic wire-array Z pinches are the most powerful and efficient laboratory x-ray sources. Furthermore, under certain conditions the soft x-ray energy radiated in a 5 ns pulse at stagnation can exceed the estimated kinetic energy of the radial implosion phase by a factor of 3 to 4. A theoretical model is developed here to explain this, allowing the rapid conversion of magnetic energy to a very high ion temperature plasma through the generation of fine scale, fast-growing m = 0 interchange MHD instabilities at stagnation. These saturate nonlinearly and provide associated ion viscous heating. Next the ion energy is transferred by equipartition to the electrons and thus to soft x-ray radiation. Recent time-resolved iron spectra at Sandia confirm an ion temperature Ti of over 200 keV (2 x 10(9) degrees), as predicted by theory. These are believed to be record temperatures for a magnetically confined plasma.

Illicit and traditional drug use among ethnic minority adolescents in East London.

OBJECTIVES: To explore ethnic variations in the use of illicit and traditional drugs, and the association of indicators of acculturation with drug use among an ethnically diverse representative sample of early adolescents in East London. STUDY DESIGN: A cross-sectional questionnaire survey. METHODS: Confidential questionnaires were used to assess 2789 male and female pupils in years 7 and 9, aged 11-14 years old, from a representative sample of 28 secondary schools in East London. RESULTS: In total, 10.8% reported having ever tried illicit drugs and 7.3% reported ever using cannabis. Compared with white British adolescents, cannabis use in the previous month was significantly higher amongst black Caribbean adolescents. Lifetime cannabis use was significantly higher amongst black Caribbean and mixed ethnicity young people, but was lower amongst Bangladeshi, Indian and Pakistani adolescents. Living in UK for 5 years or less markedly reduced the risk of lifetime and recent cannabis use when controlled for ethnicity and social class. Glue or solvent use was reported in 3.2% of adolescents, with use significantly higher amongst Bangladeshi young people. Lifetime paan use was reported by 14.1% of the sample, and was almost completely confined to South Asian or mixed ethnicities. CONCLUSIONS: Ethnic differences in illicit drug use were found in the study population, and significant differences were found between ethnic groups often identified as 'black.' Further research is needed in understanding cultural-specific risk and protective factors in different ethnic groups, and the importance of cultural identity in mediating health risk behaviors. The high use of paan and glue/gas/solvents by Bangladeshi young people poses an unappreciated public health problem that may require targeted interventions.