1,268 research outputs found
Imaging Photon Lattice States by Scanning Defect Microscopy
Microwave photons inside lattices of coupled resonators and superconducting
qubits can exhibit surprising matter-like behavior. Realizing such open-system
quantum simulators presents an experimental challenge and requires new tools
and measurement techniques. Here, we introduce Scanning Defect Microscopy as
one such tool and illustrate its use in mapping the normal-mode structure of
microwave photons inside a 49-site Kagome lattice of coplanar waveguide
resonators. Scanning is accomplished by moving a probe equipped with a sapphire
tip across the lattice. This locally perturbs resonator frequencies and induces
shifts of the lattice resonance frequencies which we determine by measuring the
transmission spectrum. From the magnitude of mode shifts we can reconstruct
photon field amplitudes at each lattice site and thus create spatial images of
the photon-lattice normal modes
Big Bang nucleosynthesis revisited via Trojan Horse Method measurements
Nuclear reaction rates are among the most important input for understanding
the primordial nucleosynthesis and therefore for a quantitative description of
the early Universe. An up-to-date compilation of direct cross sections of
2H(d,p)3H, 2H(d,n)3He, 7Li(p,alpha)4He and 3He(d,p)4He reactions is given.
These are among the most uncertain cross sections used and input for Big Bang
nucleosynthesis calculations. Their measurements through the Trojan Horse
Method (THM) are also reviewed and compared with direct data. The reaction
rates and the corresponding recommended errors in this work were used as input
for primordial nucleosynthesis calculations to evaluate their impact on the 2H,
3,4He and 7Li primordial abundances, which are then compared with observations.Comment: 22 pages, 7 figures, accepted for publication in The Astrophysical
Journa
Quality of life of adolescents with cancer: family risks and resources
PURPOSE: The goal of this study was to evaluate the relative contribution of treatment intensity, family sociodemographic risk, and family resources to health-related quality of life (QOL) of 102 adolescents in treatment for cancer. METHODS: Adolescents and parents completed self-report measures of teen QOL, family functioning, and parent-child bonding. Based on parent report of family sociodemographic variables, an additive risk index was computed. A pediatric oncologist rated treatment intensity. RESULTS: Simultaneous regression analyses demonstrated the significant contribution of roles in family functioning and quality of parent-child relationship to prediction of psychosocial QOL (parent and teen-reported) as well as parent-reported teen physical QOL over and above the contribution of treatment intensity. Family sociodemographic risk did not contribute to QOL in these regression analyses. In additional analyses, specific diagnosis, types of treatment and individual sociodemographic risk variables were not associated with QOL. Parent and teen ratings of family functioning and quality of life were concordant. CONCLUSIONS: Family functioning, including quality of parent-child relationship, are central and potentially modifiable resistance factors in teen QOL while under treatment for cancer. Even more important than relying on diagnosis or treatment, screening for roles and relationships early in treatment may be an important aspect of determining risk for poor QOL outcomes
Molecular Structures in T=1 states of 10B
Multi-center (molecular) structures can play an important role in light
nuclei. The highly deformed rotational band in 10Be with band head at 6.179 MeV
has been observed recently and suggested to have an exotic alpha:2n:alpha
configuration. A search for states with alpha:pn:alpha two-center molecular
configurations in 10B that are analogous to the states with alpha:2n:alpha
structure in 10Be has been performed. The T=1 isobaric analog states in 10B
were studied in the excitation energy range of E=8.7-12.1 MeV using the
reaction 1H(9Be,alpha)6Li*(T=1, 0+, 3.56 MeV). An R-matrix analysis was used to
extract parameters for the states observed in the (p,alpha) excitation
function. Five T=1 states in 10B have been identified. The known 2+ and 3-
states at 8.9 MeV have been observed and their partial widths have been
measured. The spin-parities and partial widths for three higher lying states
were determined. Our data support theoretical predictions that the 2+ state at
8.9 MeV (isobaric analog of the 7.54 MeV state in 10Be) is a highly clustered
state and can be identified as a member of the alpha:np:alpha rotational band.
The next member of this band, the 4+ state, has not been found. A very broad 0+
state at 11 MeV that corresponds to pure alpha+6Li(0+,T=1) configuration is
suggested and it might be related to similar structures found in 12C, 18O and
20Ne.Comment: 10 pages, 10 figures, accepted in Physical Review
ASTROPHYSICAL IMPACT of the UPDATED 9Be(p,)6Li and 10B(p,)7Be REACTION RATES AS DEDUCED by THM
The complete understanding of the stellar abundances of lithium, beryllium, and boron represents one of the most interesting open problems in astrophysics. These elements are largely used to probe stellar structure and mixing phenomena in different astrophysical scenarios, such as pre-main-sequence or main-sequence stars. Their different fragility against (p,) burning reactions allows one to investigate different depths of the stellar interior. Such fusion mechanisms are triggered at temperatures between T ≈ (2-5) × K, thus defining a corresponding Gamow energy between ≈ 3-10 keV, where S(E)-factor measurements need to be performed to get reliable reaction rate evaluations. The Trojan Horse Method is a well defined procedure to measure cross sections at Gamow energies overcoming the uncertainties due to low-energy S(E)-factor extrapolation as well as electron screening effects. Taking advantage of the measure of the 9Be(p,)6Li and 10B(p,)7Be cross sections, the corresponding reaction rates have been calculated and compared with the evaluations by the NACRE collaboration, widely used in the literature. The impact on surface abundances of the updated 9Be and 10B (p,) burning rates is discussed for pre-MS stars
Assessing the presence of Wuchereria bancrofti in vector and human populations from urban communities in Conakry, Guinea
The Global Programme to Eliminate Lymphatic Filariasis was launched in 2000 with the goal of interrupting transmission of lymphatic filariasis (LF) through multiple rounds of mass drug administration (MDA). In Guinea, there is evidence of ongoing LF transmission, but little is known about the most densely populated parts of the country, including the capital Conakry. In order to guide the LF control and elimination efforts, serological and entomological surveys were carried out to determine whether or not LF transmission occurs in Conakry.; The prevalence of circulating filarial antigen (CFA) of Wuchereria bancrofti was assessed by an immuno-chromatography test (ICT) in people recruited from all five districts of Conakry. Mosquitoes were collected over a 1-year period, in 195 households in 15 communities. A proportion of mosquitoes were analysed for W. bancrofti, using dissection, loop-mediated isothermal amplification (LAMP) assay and conventional polymerase chain reaction (PCR).; CFA test revealed no infection in the 611 individuals examined. A total of 14,334 mosquitoes were collected; 14,135 Culex (98.6Â %), 161 Anopheles (1.1Â %) and a few other species. Out of 1,312 Culex spp. (9.3Â %) and 51 An. gambiae (31.7Â %) dissected, none was infected with any stage of the W. bancrofti parasite. However, the LAMP assay revealed that 1.8Â % of An. gambiae and 0.31Â % of Culex spp. were positive, while PCR determined respective prevalences of 0Â % and 0.19Â %.; This study revealed the presence of W. bancrofti DNA in mosquitoes, despite the apparent absence of infection in the human population. Although MDA interventions are not recommended where the prevalence of ICT is below 1Â %, the entomological results are suggestive of the circulation of the parasite in the population of Conakry. Therefore, rigorous surveillance is still warranted so that LF transmission in Conakry would be identified rapidly and adequate responses being implemented
An Initial Application of a Biopsychosocial Framework to Predict Posttraumatic Stress Following Pediatric Injury
Objectives—Each year millions of children suffer from unintentional injuries that result in poor emotional and physical health. This study examined selected biopsychosocial factors (i.e., child heart rate, peritrauma appraisals, early coping, trauma history) to elucidate their roles in promoting emotional recovery following injury. The study evaluated specific hypotheses that threat appraisals (global and trauma-specific) and coping would predict subsequent posttraumatic stress symptoms (PTSS), that coping would mediate the association between early and later PTSS, and that heart rate would predict PTSS and appraisals would mediate this association.
Method—Participants were 96 children hospitalized for injury and assessed at 3 time points: T1 (within 2 weeks of injury), T2 (6-week follow-up), and T3 (12-week follow-up). Participants completed measures of trauma history and appraisals at T1, coping at T2, and PTSS at T1, T2, and T3. Heart rate was abstracted from medical records. Structural equation modeling was employed to evaluate study hypotheses.
Results—Heart rate was not associated with PTSS or appraisals. Models including trauma history, appraisals, coping, and PTSS were constructed to test other study hypotheses and fit the data well. T1 global and trauma-specific threat appraisals were associated with T1 PTSS; T2 avoidant coping was a significant mediator of the relation between T1 and T3 PTSS.
Conclusions—Findings confirm a role for appraisals and coping in the development of PTSS over the weeks following pediatric injury. Early appraisals and avoidant coping may be appropriate targets for prevention and early intervention. Future researchers should further explicate the utility of a biopsychosocial framework in predicting PTSS
nuclear physics and its role for describing the early universe
Big Bang Nucleosynthesis (BBN) requires several nuclear physics inputs and nuclear reaction rates. An up-to-date compilation of direct cross sections of [Formula: see text], [Formula: see text]He and [Formula: see text]He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM) to study reactions of relevance for the BBN and measure their astrophysical S(E)-factor. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN [Formula: see text]. These value were then used as input physics for primordial nucleosynthesis calculations in order to evaluate their impact on the calculated primordial abundances and isotopical composition for H, He and Li. New results on the [Formula: see text]He reaction rate were also taken into account.These were compared with the observational primordial abundance estimates in different astrophysical sites. Reactions to be studied in perspective will also be discussed
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