Time-resolved X-ray diffraction diagnostic development for the National Ignition Facility.

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 ∼7 × 1011, 10.25-keV photons/ns at the 400 µm diameter sample.

Developing a platform for Fresnel diffractive radiography with 1 µm spatial resolution at the National Ignition Facility.

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 ∼2.3 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.

Optimized x-ray emission from 10 ns long germanium x-ray sources at the National Ignition Facility.

This study investigates methods to optimize quasi-monochromatic, ∼10 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 ∼10 ns, mitigating cold plasma and higher energy x-ray emission lines.

A 2-4 keV multilayer mirrored channel for the NIF Dante system.

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 ∼2.5 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%.

Increased Ion Temperature and Neutron Yield Observed in Magnetized Indirectly Driven D_{2}-Filled Capsule Implosions on the National Ignition Facility.

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 ∼4.9 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 ∼3 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.

High-yield magnetic recoil neutron spectrometer on the National Ignition Facility for operation up to 60 MJ.

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×.

Long duration x-ray source development for x-ray diffraction at the National Ignition Facility.

We present the results of experiments to produce a 10 ns-long, quasi-monochromatic x-ray source. This effort is needed to support time-resolved x-ray diffraction (XRDt) measurements of phase transitions during laser-driven dynamic compression experiments at the National Ignition Facility. To record XRDt of phase transitions as they occur, we use high-speed (∼1 ns) gated hybrid CMOS detectors, which record multiple frames of data over a timescale of a few to tens of ns. Consequently, to make effective use of these imagers, XRDt needs the x-ray source to be narrow in energy and uniform in time as long as the sensors are active. The x-ray source is produced by a laser irradiated Ge foil. Our results indicate that the x-ray source lasts during the whole duration of the main laser pulse. Both time-resolved and time-integrated spectral data indicate that the line emission is dominated by the He-α complex over higher energy emission lines. Time-integrated spectra agree well with a one-dimensional Cartesian simulation using HYDRA that predicts a conversion efficiency of 0.56% when the incident intensity is 2 × 1015 W/cm2 on a Ge backlighter.

Commonality of adherent-invasive Escherichia coli isolated from patients with extraintestinal infections, healthy individuals and the environment.

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.

Time-Resolved Fuel Density Profiles of the Stagnation Phase of Indirect-Drive Inertial Confinement Implosions.

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.

X-ray diffraction at the National Ignition Facility.

We report details of an experimental platform implemented at the National Ignition Facility to obtain in situ powder diffraction data from solids dynamically compressed to extreme pressures. Thin samples are sandwiched between tamper layers and ramp compressed using a gradual increase in the drive-laser irradiance. Pressure history in the sample is determined using high-precision velocimetry measurements. Up to two independently timed pulses of x rays are produced at or near the time of peak pressure by laser illumination of thin metal foils. The quasi-monochromatic x-ray pulses have a mean wavelength selectable between 0.6 Å and 1.9 Å depending on the foil material. The diffracted signal is recorded on image plates with a typical 2θ x-ray scattering angle uncertainty of about 0.2° and resolution of about 1°. Analytic expressions are reported for systematic corrections to 2θ due to finite pinhole size and sample offset. A new variant of a nonlinear background subtraction algorithm is described, which has been used to observe diffraction lines at signal-to-background ratios as low as a few percent. Variations in system response over the detector area are compensated in order to obtain accurate line intensities; this system response calculation includes a new analytic approximation for image-plate sensitivity as a function of photon energy and incident angle. This experimental platform has been used up to 2 TPa (20 Mbar) to determine the crystal structure, measure the density, and evaluate the strain-induced texturing of a variety of compressed samples spanning periods 2-7 on the periodic table.

Refinement and Pilot Testing of a Brief, Early Intervention for PTSD and Alcohol Use Following Sexual Assault.

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.

Social Norms: Are Sexually Aggressive Men More Likely to Misperceive Other Men's Sexual Desires and Behavior?

Separate lines of research show that men overestimate the extent of male peers' sexual activity, and independently, that sexually aggressive men believe that other men approve of coercive behavior. This study examined the intersection of these lines of inquiry, testing whether the degree of male participants' misperception of other men's sexual behavior differs as a function of perpetrator status. In a national sample, we presented heterosexually active men (n=497) with sexual scenarios varying in sexual acts, partner types, and circumstances. Results showed that participants significantly overestimated the typicality of all types of sexual situations for other men. Participants also misjudged the desirability of scenarios consistent with a traditional masculinity sexual script to other men; these scenarios reflected an adversarial perspective on relationships and an impersonal approach to sexuality - a known risk factor for sexual aggression. Further, sexually aggressive men overestimated the desirability of these traditional masculinity scenarios to a greater extent than non-aggressive peers. Findings suggest that interventions that provide accurate knowledge about social norms, or "typical" sexual desires and behaviors among other men, may reduce pressure to live up to perceived but perhaps inaccurate masculine ideals, as well as reduce social norm-related risks for sexually aggressive behavior.

Young Women's Experiences with Coercive and Noncoercive Condom Use Resistance: Examination of an Understudied Sexual Risk Behavior.

OBJECTIVES: To investigate young women's engagement in and receipt of condom use resistance (CUR; attempts to avoid condom use with a partner who wants to use one), including nonconsensual condom removal ("stealthing"), with male partners. METHODS: Participants were 503 women aged 21-30 years with increased sexual risk characteristics recruited from 2013 to 2017. Participants completed measures assessing sexual victimization history and CUR experiences. RESULTS: Findings indicated that 87% of women experienced noncoercive CUR from a partner and 49% experienced coercive CUR. Of these women, 58% and 19% reported having engaged in noncoercive and coercive CUR, respectively. Twelve percent of women had a partner engage in stealthing; none of the women engaged in stealthing. The severity of sexual victimization history was positively associated with both use and receipt of coercive and noncoercive CUR. Diagnoses of sexually transmitted infections were positively associated with receipt of, but not engagement in, CUR. CONCLUSIONS: Findings demonstrate that sexual victimization and both the use and receipt of CUR are positively related for young women, suggesting that prevention efforts focusing on women's sexual health would benefit from joint consideration of sexual violence and risk behaviors and that such efforts should target victims of sexual violence.

Using time-resolved penumbral imaging to measure low hot spot x-ray emission signals from capsule implosions at the National Ignition Facility.

We have developed and fielded a new x-ray pinhole-imaging snout that exploits time-resolved penumbral imaging of low-emission hot spots in capsule implosion experiments at the National Ignition Facility. We report results for a series of indirectly driven Be capsule implosions that aim at measuring x-ray Thomson scattering (XRTS) spectra at extreme density conditions near stagnation. In these implosions, x-ray emission at stagnation is reduced by 100-1000× compared to standard inertial confinement fusion (ICF) implosions to mitigate undesired continuum background in the XRTS spectra. Our snout design not only enables measurements of peak x-ray emission times, t o , where standard ICF diagnostics would not record any signal, but also allows for inference of hot spot shapes. Measurement of t o is crucial to account for shot-to-shot variations in implosion velocity and therefore to benchmark the achieved plasma conditions between shots and against radiation hydrodynamic simulations. Additionally, we used differential filtering to infer a hot spot temperature of 520 ± 80 eV, which is in good agreement with predictions from radiation hydrodynamic simulations. We find that, despite fluctuations of the x-ray flash intensity of up to 5×, the emission time history is similar from shot to shot and slightly asymmetric with respect to peak x-ray emission.

Invasion and translocation of uropathogenic Escherichia coli isolated from urosepsis and patients with community-acquired urinary tract infection.

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.

How Childhood Maltreatment Profiles of Male Victims Predict Adult Perpetration and Psychosocial Functioning.

This study used latent class analysis to empirically identify subgroups of men based on their exposure to childhood maltreatment (i.e., emotional neglect and abuse, physical neglect and abuse, and sexual abuse). It then examined subgroups' differential perpetration of adult intimate partner violence (IPV; both psychological and physical), violence against peers, and sexual assault. Finally, we compared sociodemographic variables and psychosocial functioning across profiles to characterize the adult experiences of men in different maltreatment groups. The community sample consisted of 626 heterosexually active 21- to 30-year-old men. We identified four subgroups: Low Maltreatment (80% of the sample), Emotional and Physical Maltreatment (12%), Emotional and Sexual Maltreatment (4%), and Poly-Victimized (4%). The Low Maltreatment group had significantly lower IPV perpetration rates than the Emotional and Physical Maltreatment group, but groups did not significantly differ on peer violence or sexual assault perpetration rates. Overall, Poly-Victimized men were significantly worse off than the Low Maltreatment group regarding income, education level, and incarceration history. Their rates of recent anxiety and depression symptoms were also higher than those of Low Maltreatment men. Findings support the use of person-oriented techniques for deriving patterns of childhood maltreatment and how these patterns relate to psychological, behavioral, and social factors in adulthood.

Comparison between virulence characteristics of dominant and non-dominant Escherichia coli strains of the gut and their interaction with Caco-2 cells.

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.

Predicting Sexual Assault Perpetration Among Heterosexually Active Young Men.

Data from an online community sample of young men were analyzed to test predictors of sexual assault perpetration. We used structural equation modeling to test the relative contributions of specific sub-types of childhood adversity to subsequent sexual aggression. Mediators included hostile masculinity, impersonal sexual behavior and attitudes, and substance use variables. Findings suggested that childhood sexual abuse had direct and mediated effects on sexual assault perpetration, but hostile masculinity was the only proximal factor significantly related to aggression. Childhood polytrauma was also associated with increased perpetration risk, suggesting that prevention efforts may be aided by increased attention to childhood maltreatment.

Using Qualitative Disease Risk Analysis for Herpetofauna Conservation Translocations Transgressing Ecological and Geographical Barriers.

Through the exploration of disease risk analysis methods employed for four different UK herpetofauna translocations, we illustrate how disease hazards can be identified, and how the risk of disease can be analysed. Where ecological or geographical barriers between source and destination sites exist, parasite populations are likely to differ in identity or strain between the two sites, elevating the risk from disease and increasing the number and category of hazards requiring analysis. Simplification of the translocation pathway through the avoidance of these barriers reduces the risk from disease. The disease risk analysis tool is intended to aid conservation practitioners in decision making relating to disease hazards prior to implementation of a translocation.

Correlates of Young Men's Intention to Discuss Birth Control with Female Partners.

CONTEXT: Heterosexually active men who wish to prevent conception, but are not willing to use condoms consistently, need to discuss birth control with female partners. Improving the understanding of correlates of men's intention to have such discussions is one step toward supporting this health-facilitating behavior. METHODS: A sample of 372 heterosexually active men aged 18-25 were recruited and surveyed online between December 2010 and June 2011. Men answered questions on attitudes toward, norms regarding and self-efficacy about discussing birth control, and about endorsement of two sexual scripts. Multiple regression analyses tested these measures' associations with intention to discuss birth control, controlling for age and relationship status. RESULTS: Attitudes, norms and self-efficacy were each positively associated with men's intention to discuss birth control, accounting for 34% of variance. The more strongly men endorsed a traditional masculinity sexual script, the less likely they were to intend to discuss birth control (coefficient, -0.2). Endorsement of an alternative, gender-equitable "sex-positive woman" script, which emphasizes sexual pleasure and emotional connection as goals for both partners, had no association with intention. CONCLUSION: Strategies that merit further exploration as potential supports for men's intention to discuss birth control include improving men's self-efficacy and positive attitudes and norms pertaining to such discussions, and reducing belief in traditionally masculine sexual scripts or transforming them to include discussing birth control. Future research should work both experimentally and longitudinally to document each element of the process that ends with men's full participation in effective contraceptive use.