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The application of an external 26 Tesla axial magnetic field to a D_{2} gas-filled capsule indirectly driven on the National Ignition Facility is observed to increase the ion temperature by 40% and the neutron yield by a factor of 3.2 in a hot spot with areal density and temperature approaching what is required for fusion ignition [1]. The improvements are determined from energy spectral measurements of the 2.45 MeV neutrons from the D(d,n)^{3}He reaction, and the compressed central core B field is estimated to be â¼4.9 kT using the 14.1 MeV secondary neutrons from the D(T,n)^{4}He reactions. The experiments use a 30 kV pulsed-power system to deliver a â¼3 µs current pulse to a solenoidal coil wrapped around a novel high-electrical-resistivity AuTa_{4} hohlraum. Radiation magnetohydrodynamic simulations are consistent with the experiment.
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Adherent-invasive Escherichia coli (AIEC) has been implicated as a microbiological factor in inflammatory bowel disease (IBD) pathogenesis. These strains are defined by their ability to adhere to and invade intestinal epithelial cells, and to survive and replicate in macrophages. We postulated that AIEC strains may commonly inhabit the gut of healthy individuals (HI), cause extraintestinal infections, and be found in sewage treatment plants (STP) and surface waters (SW). A total of 808 E. coli strains isolated from HI; patients with community-acquired urinary tract infection (CA-UTI), septicaemia and urosepsis; STP; and SW, showing a diffuse adhesion pattern to Caco-2 cells were included in this study. Typing of the strains using a combination of RAPD-PCR and PhPlate fingerprinting grouped them into 48 common clones (CCs). Representatives of each CC were tested for the ability to invade Caco-2 cells, survive and replicate in macrophages, and for the presence of six virulence genes commonly found among AIEC strains. Twenty CCs were deemed AIEC based on their ability to survive and replicate in macrophages, while encoding htrA, dsbA and clbA genes. These CCs primarily originated from HI and CA-UTI patients but were also detected in secondary locations including STP and SW. Strains lacking intramacrophagic survival and replication abilities were regarded as diffusely adhering E. coli (DAEC). Certain clones of AIEC are common in the gut of HI whilst promoting CA-UTI. The survival and persistence of AIEC in STP and SW may have serious public health ramifications for individuals predisposed to IBD.
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Meio Ambiente , Infecções por Escherichia coli/epidemiologia , Escherichia coli/patogenicidade , Doenças Inflamatórias Intestinais/epidemiologia , Microbiologia da Água , Abastecimento de Água , Adulto , Idoso , Idoso de 80 Anos ou mais , Infecções por Escherichia coli/etiologia , Infecções por Escherichia coli/microbiologia , Feminino , Humanos , Doenças Inflamatórias Intestinais/etiologia , Doenças Inflamatórias Intestinais/microbiologia , Masculino , Pessoa de Meia-Idade , Queensland/epidemiologiaRESUMO
The implosion efficiency in inertial confinement fusion depends on the degree of stagnated fuel compression, density uniformity, sphericity, and minimum residual kinetic energy achieved. Compton scattering-mediated 50-200 keV x-ray radiographs of indirect-drive cryogenic implosions at the National Ignition Facility capture the dynamic evolution of the fuel as it goes through peak compression, revealing low-mode 3D nonuniformities and thicker fuel with lower peak density than simulated. By differencing two radiographs taken at different times during the same implosion, we also measure the residual kinetic energy not transferred to the hot spot and quantify its impact on the implosion performance.
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Experiencing a sexual assault can have long-lasting negative consequences including development of posttraumatic stress disorder (PTSD) and alcohol misuse. Intervention provided in the initial weeks following assault can reduce the development of these chronic problems. This study describes the iterative treatment development process for refining a brief intervention targeting PTSD and alcohol misuse for women with recent sexual assault experiences. Experts, treatment providers, and patients provided feedback on the intervention materials and guided the refinement process. Based on principles of cognitive change, the final intervention consists of one in-person session and four coaching calls targeting beliefs about the assault and about drinking behavior. Initial feasibility and acceptability data are presented for patients enrolled in an open trial (N = 6). The intervention was rated as helpful, not distressing, and interesting by patients and all patients completed the entire treatment protocol. A large decrease in PTSD symptoms pre- to post-intervention was observed. A small effect on decreasing alcohol consequences also emerged, although drinks consumed per week showed a slight increase, not a decrease, over the course of the intervention. Applications of this intervention and next steps for testing efficacy are presented.
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Uropathogenic Escherichia coli (UPEC) strains are found in high numbers in the gut of patients with urinary tract infections (UTIs). We hypothesised that in hospitalised patients, UPEC strains might translocate from the gut to the blood stream and that this could be due to the presence of virulence genes (VGs) that are not commonly found in UPEC strains that cause UTI only. To test this, E. coli strains representing 75 dominant clonal groups of UPEC isolated from the blood of hospitalised patients with UTI (urosepsis) (n = 22), hospital-acquired (HA) UTI without blood infection (n = 24) and strains isolated from patients with community-acquired (CA)-UTIs (n = 29) were tested for their adhesion to, invasion and translocation through Caco-2 cells, in addition to the presence of 34 VGs associated with UPEC. Although there were no differences in the rate and degree of translocation among the groups, urosepsis and HA-UTI strains showed significantly higher abilities to adhere (P = 0.0095 and P < 0.0001 respectively) and invade Caco-2 cells than CA-UTI isolates (P = 0.0044, P = 0.0048 respectively). Urosepsis strains also carried significantly more VGs than strains isolated from patients with only UTI and/or CA-UTI isolates. In contrast, the antigen 43 allele RS218 was found more commonly among CA-UTI strains than in the other two groups. These data indicate that UPEC strains, irrespective of their source, are capable of translocating through gut epithelium. However, urosepsis and HA-UTI strains have a much better ability to interact with gut epithelia and have a greater virulence potential than CA-UPEC, which allows them to cause blood infection.
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Infecções Comunitárias Adquiridas/microbiologia , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Biossíntese de Proteínas , Sepse/microbiologia , Infecções Urinárias/microbiologia , Escherichia coli Uropatogênica/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Aderência Bacteriana/genética , Carga Bacteriana , Linhagem Celular , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Escherichia coli Uropatogênica/isolamento & purificação , Escherichia coli Uropatogênica/patogenicidade , Virulência/genética , Fatores de Virulência/genéticaRESUMO
Escherichia coli strains are normal inhabitants of the gut and are normally found in the faeces of the host at different population sizes. We characterised faecal E. coli of 45 healthy male (n = 17) and female (n = 28) volunteers by testing 28 isolates from each individual. These isolates were typed and divided into dominant (if constituted >50% of the population tested) and non-dominant types in each individual. Representative strains of each dominant and non-dominant type were tested for their virulence gene profiles, their ability to form biofilm, adhere to, invade and translocate through a gut epithelial cell line (Caco-2 cells). Strains belonging to dominant types adhered significantly more to Caco-2 cells than non-dominant strains (5.7 ± 0.3 versus 4.3.± 0.13 CFU/cell mean ± SEM, P = 0.0003). They also invaded (135 ± 6 versus 63 ± 13 CFU) and translocated through Caco-2 cells (84 ± 5 versus 32 ± 9 CFU) significantly more than non-dominant strains (P < 0.0001 and P = 0.0002, respectively). Moreover, dominant strains showed the ability to form significantly more biofilm than non-dominant strains (1.1 ± 0.01 versus 0.5 ± 0.1 OD600, P < 0.0001). Majority (51%) of the strains belonged to phylogroup D followed by B2 (23%). Furthermore, out of 25 virulence genes tested, kpsMTII, papC and papG allele III were found to be significantly higher among dominant than non-dominant strains. Our results suggest that E. coli strains dominating the gut may have virulence properties that enable them to efficiently interact with the gut epithelium and translocate under predisposing conditions of the host.
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Infecções por Escherichia coli/microbiologia , Escherichia coli/patogenicidade , Trato Gastrointestinal/microbiologia , Enteropatias/microbiologia , Transportadores de Cassetes de Ligação de ATP/genética , Adesinas de Escherichia coli/genética , Aderência Bacteriana , Translocação Bacteriana , Biofilmes , Células CACO-2 , Células Epiteliais/microbiologia , Escherichia coli/classificação , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Proteínas de Escherichia coli/genética , Fezes/microbiologia , Feminino , Proteínas de Fímbrias/genética , Interações Hospedeiro-Patógeno , Humanos , Masculino , Porinas/genética , Prevalência , Fatores Sexuais , Virulência/genéticaRESUMO
Highly intoxicated versus sober women were evaluated using multi-group path analyses to test the hypothesis that sexual victimization history would interact with partner pressure to forgo condom use, resulting in greater condom-decision abdication-letting the man decide whether or not to use a condom. After beverage administration, community women (n = 408) projected themselves into a scenario depicting a male partner exerting high or low pressure for unprotected sex. Mood, anticipated negative reactions from the partner, and condom-decision abdication were assessed. In both control and alcohol models, high pressure increased anticipated negative partner reaction, and positive mood was associated with increased abdication. In the alcohol model, victimization predicted abdication via anticipated negative partner reaction, and pressure decreased positive mood and abdication. In the control model, under high pressure, victimization history severity was positively associated with abdication. Findings implicate condom-decision abdication as an important construct in understanding how women's sexual victimization histories may exert sustained impact on sexual interactions.
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Sobreviventes Adultos de Maus-Tratos Infantis/psicologia , Consumo de Bebidas Alcoólicas/psicologia , Coerção , Preservativos/estatística & dados numéricos , Parceiros Sexuais , Sexo sem Proteção/psicologia , Adulto , Criança , Vítimas de Crime/psicologia , Tomada de Decisões , Feminino , Infecções por HIV/prevenção & controle , Humanos , Intenção , Assunção de Riscos , Percepção Social , Maus-Tratos Conjugais , População Urbana , Adulto JovemRESUMO
Parallel bodies of research have described the diverse and complex ways that men understand and construct their masculine identities (often termed "masculinities") and, separately, how adherence to traditional notions of masculinity places men at risk for negative sexual and health outcomes. The goal of this analysis was to bring together these two streams of inquiry. Using data from a national, online sample of 555 heterosexually active young men, we employed latent class analysis (LCA) to detect patterns of masculine identities based on men's endorsement of behavioral and attitudinal indicators of "dominant" masculinity, including sexual attitudes and behaviors. LCA identified four conceptually distinct masculine identity profiles. Two groups, termed the Normative and Normative/Male Activities groups, respectively, constituted 88 % of the sample and were characterized by low levels of adherence to attitudes, sexual scripts, and behaviors consistent with "dominant" masculinity, but differed in their levels of engagement in male-oriented activities (e.g., sports teams). Only eight percent of the sample comprised a masculinity profile consistent with "traditional" ideas about masculinity; this group was labeled Misogynistic because of high levels of sexual assault and violence toward female partners. The remaining four percent constituted a Sex-Focused group, characterized by high numbers of sexual partners, but relatively low endorsement of other indicators of traditional masculinity. Follow-up analyses showed a small number of differences across groups on sexual and substance use health indicators. Findings have implications for sexual and behavioral health interventions and suggest that very few young men embody or endorse rigidly traditional forms of masculinity.
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Heterossexualidade/psicologia , Masculinidade , Homens/psicologia , Adulto , Feminino , Grupos Focais , Humanos , Masculino , Parceiros Sexuais , Violência , Adulto JovemRESUMO
CASE HISTORY: Health monitoring of tuatara (Sphenodon punctatus) at Auckland Zoo between 2001 and 2009 showed that 58/93 tuatara had been affected by dermatitis of unknown origin. From 2011 onwards, cases of suspected fungal dermatitis underwent extensive diagnostic investigations. CLINCAL FINDINGS: Six cases of dermatomycosis were attributed to Paranannizziopsis australasiensis, five in tuatara and one in a coastal bearded dragon (Pogona barbata). Cases presented typically as raised, yellow to brown encrustations on the skin. Severe cases progressed to necrotising ulcerative dermatitis, and in the bearded dragon to fatal systemic mycosis. Following topical and systemic treatments, lesions resolved in all five tuatara. LABORATORY FINDINGS: Histopathological examination of skin biopsy samples revealed dermatitis with intralesional septate branching hyphae. Fungal culture yielded isolates morphologically resembling Chrysosporium species, and isolates were submitted for molecular confirmation and sequencing of DNA. DIAGNOSIS: All six cases were confirmed as dermatitis due to infection with P. australasiensis, on the basis of fungal culture and DNA sequencing of isolates. CLINICAL RELEVANCE: These are the first reported cases of dermatomycosis associated with P. australasiensis infection in tuatara, and the first cases in which systemic therapeutic agents have been used in the treatment of such disease. Tuatara at the Auckland Zoo are now routinely examined every 3 months and tissue samples from any lesions sent for histopathology and fungal culture. Further work to elucidate the epidemiology and significance of P. australasiensis infections in reptiles in New Zealand is important for both welfare and conservation purposes.
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Dermatomicoses/veterinária , Lagartos/microbiologia , Onygenales , Répteis/microbiologia , Animais , Animais de Zoológico/microbiologia , Dermatomicoses/microbiologia , Feminino , Masculino , Nova Zelândia , Reação em Cadeia da Polimerase/veterinária , Pele/microbiologiaRESUMO
Research on heterosexual men's sexual expectations has focused on self-described personal traits and culturally dominant models of masculinity. In a pair of studies, we used a sexual scripts perspective to explore the range and diversity of young men's thoughts about sex and relationships with women and to develop measures for assessing these scripts. In the first study, we conducted semi-structured interviews to elicit young men's accounts of their sexual relationships. We used these narratives to produce brief sexual script scenarios describing typical sexual situations, as well as conventional survey items assessing sexual behavior themes. In the second study, we administered the scenarios and theme items to an ethnically diverse, national sample of 648 heterosexually active young men in an online survey. Using exploratory factor analysis, we delineated sets of sexual scripts and sexual behavior themes. In the scenarios, we found both a traditional masculine "player" script and a script that emphasized mutual sexual pleasure. Analysis of theme items produced scales of Drinking and Courtship, Monogamy and Emotion, and Sexual Focus and Variety. We discuss the implications of these findings for understanding heterosexual men's thinking about sexuality and how cultural change in sexual thinking may arise. We also discuss the need for measures of sexual thinking that better integrate perceptions and expectations about the partner as well as the self in relation to the partner, rather than solely self-assessed traits.
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Heterossexualidade/psicologia , Masculinidade , Homens/psicologia , Prazer , Emoções , Análise Fatorial , Feminino , Inquéritos Epidemiológicos , Humanos , Entrevistas como Assunto , Masculino , Comportamento Sexual/psicologia , Parceiros Sexuais/psicologia , PensamentoRESUMO
We investigated the usefulness of the ß-d-glucuronidase gene variance in Escherichia coli as a microbial source tracking tool using a novel algorithm for comparison of sequences from a prescreened set of host-specific isolates using a high-resolution PhP typing method. A total of 65 common biochemical phenotypes belonging to 318 E. coli strains isolated from humans and domestic and wild animals were analysed for nucleotide variations at 10 loci along a 518 bp fragment of the 1812 bp ß-d-glucuronidase gene. Neighbour-joining analysis of loci variations revealed 86 (76.8%) human isolates and 91.2% of animal isolates were correctly identified. Pairwise hierarchical clustering improved assignment; where 92 (82.1%) human and 204 (99%) animal strains were assigned to their respective cluster. Our data show that initial typing of isolates and selection of common types from different hosts prior to analysis of the ß-d-glucuronidase gene sequence improves source identification. We also concluded that numerical profiling of the nucleotide variations can be used as a valuable approach to differentiate human from animal E. coli. This study signifies the usefulness of the ß-d-glucuronidase gene as a marker for differentiating human faecal pollution from animal sources.
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Técnicas de Tipagem Bacteriana/métodos , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli/genética , Escherichia coli/enzimologia , Escherichia coli/isolamento & purificação , Variação Genética , Glucuronidase/genética , Animais , Animais Domésticos/microbiologia , Animais Selvagens/microbiologia , Bovinos , Galinhas , Cães , Escherichia coli/classificação , Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Fezes/microbiologia , Glucuronidase/metabolismo , Cavalos , Humanos , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNA , SuínosRESUMO
We studied the survival of Escherichia coli and enterococci populations in fecal samples of 7 host species after storage at -20 and -80 °C for 30 days. Composite fecal samples were collected from cows, chickens, horses, pigs, dogs, birds, and humans, and bacteria were enumerated before and after storage. Twenty-eight colonies of each bacterial species were typed before and after storage and the strains were assigned to different biochemical phenotypes (BPTs). A significant reduction in the number of E. coli was observed in all samples stored at -20 °C but in only 3 of those samples stored at -80 °C. However, the numbers of enterococci were similar in most stored samples (except cow and birds). The number and the distribution of E. coli and enterococci BPTs in fresh samples did not vary significantly from those stored at either temperature. Furthermore, the population structure of E. coli and enterococci did not change significantly after storage at -80 °C, this was always the case for those samples stored at -20 °C. We conclude that for those studies investigating E. coli or enterococci population structure, short-term storage (≤ 30 days) of fecal samples in a glycerol broth at -80 °C is a preferable option.
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Enterococcus/crescimento & desenvolvimento , Escherichia coli/crescimento & desenvolvimento , Fezes/microbiologia , Viabilidade Microbiana , Animais , Aves , Bovinos , Galinhas , Cães , Fezes/química , Feminino , Congelamento , Cavalos , Humanos , Fenótipo , SuínosRESUMO
This study used an experimental paradigm to investigate the roles of sexual victimization history and alcohol intoxication in young women's sexual-emotional responding and sexual risk taking. A nonclinical community sample of 436 young women, with both an instance of heavy episodic drinking and some HIV/STI risk exposure in the past year, completed childhood sexual abuse (CSA) and adolescent/adult sexual assault (ASA) measures. A majority of them reported CSA and/or ASA, including rape and attempted rape. After random assignment to a high alcohol dose (.10 %) or control condition, participants read and projected themselves into an eroticized scenario of a sexual encounter involving a new partner. As the story protagonist, each participant rated her positive mood and her sexual arousal, sensation, and desire, and then indicated her likelihood of engaging in unprotected sex. Structural equation modeling analyses revealed that ASA and alcohol were directly associated with heightened risk taking, and alcohol's effects were partially mediated by positive mood and sexual desire. ASA was associated with attenuated sexual-emotional responding and resulted in diminished risk taking via this suppression. These are the first findings indicating that, compared to non-victimized counterparts, sexually victimized women respond differently in alcohol-involved sexual encounters in terms of sexual-emotional responding and risk-taking intentions. Implications include assessing victimization history and drinking among women seeking treatment for either concern, particularly women at risk for HIV, and alerting them to ways their histories and behavior may combine to exacerbate their sexual risks.
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Intoxicação Alcoólica/psicologia , Libido , Comportamento Sexual/psicologia , Adulto , Criança , Abuso Sexual na Infância/psicologia , Vítimas de Crime/psicologia , Etanol/farmacologia , Feminino , Infecções por HIV , Humanos , Libido/efeitos dos fármacos , Estupro/psicologia , Risco , Assunção de Riscos , Comportamento Sexual/efeitos dos fármacos , Sexo sem Proteção/psicologia , Adulto JovemRESUMO
We present the development of an experimental platform that can collect four frames of x-ray diffraction data along a single line of sight during laser-driven, dynamic-compression experiments at the National Ignition Facility. The platform is comprised of a diagnostic imager built around ultrafast sensors with a 2-ns integration time, a custom target assembly that serves also to shield the imager, and a 10-ns duration, quasi-monochromatic x-ray source produced by laser-generated plasma. We demonstrate the performance with diffraction data for Pb ramp compressed to 150 GPa and illuminated by a Ge x-ray source that produces â¼7 × 1011, 10.25-keV photons/ns at the 400 µm diameter sample.
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Young adults have high rates of sexually transmitted infections (STIs). Sexual minority youths' risk for STIs, including HIV, is as high as or higher than sexual majority peers'. Sexual safety, while often treated as a single behavior such as condom use, can be best conceptualized as the result of multiple factors. We used latent class analysis to identify profiles based on ever-used sexual safety strategies and lifetime number of partners among 425 self-identified LGBTQ youth aged 14-19. Data collection took place anonymously online. We identified four specific subgroup profiles for males and three for females, with each subgroup representing a different level and type of sexual safety. Profiles differed from each other in terms of age and outness for males, and in outness, personal homonegativity, and amount of education received about sexual/romantic relationships for females. Youths' sexual safety profiles have practice implications for sexuality educators, health care professionals, and parents.
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Grupos Minoritários , Sexo Seguro , Comportamento Sexual , Infecções Sexualmente Transmissíveis/prevenção & controle , Adolescente , Bissexualidade , Feminino , Homossexualidade Feminina , Homossexualidade Masculina , Humanos , Masculino , Inquéritos e Questionários , Pessoas TransgêneroRESUMO
An x-ray Fresnel diffractive radiography platform was designed for use at the National Ignition Facility. It will enable measurements of micron-scale changes in the density gradients across an interface between isochorically heated warm dense matter materials, the evolution of which is driven primarily through thermal conductivity and mutual diffusion. We use 4.75 keV Ti K-shell x-ray emission to heat a 1000 µm diameter plastic cylinder, with a central 30 µm diameter channel filled with liquid D2, up to 8 eV. This leads to a cylindrical implosion of the liquid D2 column, compressing it to â¼2.3 g/cm3. After pressure equilibration, the location of the D2/plastic interface remains steady for several nanoseconds, which enables us to track density gradient changes across the material interface with high precision. For radiography, we use Cu He-α x rays at 8.3 keV. Using a slit aperture of only 1 µm width increases the spatial coherence of the source, giving rise to significant diffraction features in the radiography signal, in addition to the refraction enhancement, which further increases its sensitivity to density scale length changes at the D2/plastic interface.
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AIMS: The host specificity (H-SPF) and host sensitivity (H-SNV) values of the sewage-associated HF183 Bacteroides marker in the current study were compared with the previously published studies in South East Queensland (SEQ), Australia, by testing a large number of wastewater and faecal DNA samples (n=293) from 11 target and nontarget host groups. This was carried out to obtain information on the consistency in the H-SPF and H-SNV values of the HF183 marker for sewage pollution tracking in SEQ. METHODS AND RESULTS: Polymerase chain reaction (PCR) analysis was used to determine the presence/absence of the HF183 marker in wastewater and faecal DNA samples. Among the human composite wastewater (n=59) from sewage treatment plants and individual human (n=20) faecal DNA samples tested, 75 (95%) were PCR positive for the HF183 marker. The overall H-SNV of this marker in target host group was 0·95 (maximum of 1·00). Among the 214 nontarget animal faecal DNA samples tested, 201 (94%) samples were negative for the HF183 marker. Six chicken, five dog and two bird faecal DNA samples, however, were positive for the marker. The overall H-SPF of the HF183 marker to differentiate between target and nontarget faecal DNA samples was 0·94 (maximum of 1·00). CONCLUSIONS: The H-SNV (0·95) and H-SPF (0·94) values obtained in this study was slightly lower than previous studies (H-SNV value of 1·00 in 2007 and 1·00 in 2009; H-SPF value of 1·00 in 2007 and 0·99 in 2009). Nonetheless, the overall high H-SNV (0·98) and H-SPF (0·97) values of the HF183 marker over the past 4 years (i.e. 2007-2011) suggest that the HF183 marker can be reliably used for the detection of sewage pollution in environmental waters in SEQ. SIGNIFICANCE AND IMPACT OF THE STUDY: In the current study, the HF183 marker was detected in small number nontarget animal faecal samples. Care should be taken to interpret results obtained from catchments or waterways that might be potentially contaminated with dog faecal matter or poultry litter.
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Bacteroides/genética , Biomarcadores/análise , Monitoramento Ambiental/métodos , Poluição Ambiental/análise , Esgotos/microbiologia , Animais , Galinhas , DNA Bacteriano/análise , Cães , Fezes/microbiologia , Especificidade de Hospedeiro , Humanos , Reação em Cadeia da Polimerase , QueenslandRESUMO
This study investigates methods to optimize quasi-monochromatic, â¼10 ns long x-ray sources (XRS) for time-resolved x-ray diffraction measurements of phase transitions during dynamic laser compression measurements at the National Ignition Facility (NIF). To support this, we produce continuous and pulsed XRS by irradiating a Ge foil with NIF lasers to achieve an intensity of 2 × 1015 W/cm2, optimizing the laser-to-x-ray conversion efficiency. Our x-ray source is dominated by Ge He-α line emission. We discuss methods to optimize the source to maintain a uniform XRS for â¼10 ns, mitigating cold plasma and higher energy x-ray emission lines.
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Recent progress at the National Ignition Facility (NIF), with neutron yields of order 1 × 1017, places new constraints on diagnostics used to characterize implosion performance. The Magnetic Recoil neutron Spectrometer (MRS), which is routinely used to measure yield, ion temperature (Tion), and down-scatter ratio (dsr), has been adapted to allow measurements of dsr up to 5 × 1017, and yield and Tion up to 2 × 1018 in the near term with new data processing techniques and conversion foil solutions. This paper presents a solution for extending MRS operation up to a yield of 2 × 1019 (60 MJ) by moving the spectrometer outside of the NIF shield wall. This will not only enhance the upper yield limit by 10× but also improve signal-to-background by 5×.
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During inertial confinement fusion experiments at the National Ignition Facility (NIF), a capsule filled with deuterium and tritium (DT) gas, surrounded by a DT ice layer and a high-density carbon ablator, is driven to the temperature and densities required to initiate fusion. In the indirect method, 2 MJ of NIF laser light heats the inside of a gold hohlraum to a radiation temperature of 300 eV; thermal x rays from the hohlraum interior couple to the capsule and create a central hotspot at tens of millions degrees Kelvin and a density of 100-200 g/cm3. During the laser interaction with the gold wall, m-band x rays are produced at â¼2.5 keV; these can penetrate into the capsule and preheat the ablator and DT fuel. Preheat can impact instability growth rates in the ablation front and at the fuel-ablator interface. Monitoring the hohlraum x-ray spectrum throughout the implosion is, therefore, critical; for this purpose, a Multilayer Mirror (MLM) with flat response in the 2-4 keV range has been installed in the NIF 37° Dante calorimeter. Precision engineering and x-ray calibration of components mean the channel will report 2-4 keV spectral power with an uncertainty of ±8.7%.