183 research outputs found
Effect of laser temporal intensity skew on enhancing pair production in laser - Electron-beam collisions
Recent high-intensity laser experiments (Cole et al 2018 Phys. Rev. X 8 011020; Poder et al 2018 Phys. Rev. X 8 031004) have shown evidence of strong radiation reaction in the quantum regime. Experimental evidence of quantum effects on radiation reaction and electron-positron pair cascades has, however, proven challenging to obtain and crucially depends on maximising the quantum parameter of the electron (defined as the ratio of the electric field it feels in its rest frame to the Schwinger field). The quantum parameter can be suppressed as the electrons lose energy by radiation reaction as they traverse the initial rise in the laser intensity. As a result the shape of the intensity temporal envelope becomes important in enhancing quantum radiation reaction effects and pair cascades. Here we show that a realistic laser pulse with a faster rise time on the leading edge, achieved by skewing the temporal envelope, results in curtailing of pair yields as the peak power is reduced. We find a reduction in pair yields by orders of magnitude in contrast to only small reductions reported previously in large-scale particle-in-cell code simulations (Hojbota et al 2018 Plasma Phys. Control. Fusion 60 064004). Maximum pairs per electron are found in colliding 1.5 GeV electrons with a laser wakefield produced envelope 7.90 Ă 10-2 followed by a short 50 fs Gaussian envelope, 1.90 Ă 10-2, while it is reduced to 8.90 Ă 10-5, a factor of 100, for an asymmetric envelope
Psychosocial, socio-cultural, and environmental influences on mental health help-seeking among African-American men
http://dx.doi.org/10.1016/j.jomh.2012.03.00
Age at first birth in women is genetically associated with increased risk of schizophrenia
Prof. Paunio on PGC:n jÀsenPrevious studies have shown an increased risk for mental health problems in children born to both younger and older parents compared to children of average-aged parents. We previously used a novel design to reveal a latent mechanism of genetic association between schizophrenia and age at first birth in women (AFB). Here, we use independent data from the UK Biobank (N = 38,892) to replicate the finding of an association between predicted genetic risk of schizophrenia and AFB in women, and to estimate the genetic correlation between schizophrenia and AFB in women stratified into younger and older groups. We find evidence for an association between predicted genetic risk of schizophrenia and AFB in women (P-value = 1.12E-05), and we show genetic heterogeneity between younger and older AFB groups (P-value = 3.45E-03). The genetic correlation between schizophrenia and AFB in the younger AFB group is -0.16 (SE = 0.04) while that between schizophrenia and AFB in the older AFB group is 0.14 (SE = 0.08). Our results suggest that early, and perhaps also late, age at first birth in women is associated with increased genetic risk for schizophrenia in the UK Biobank sample. These findings contribute new insights into factors contributing to the complex bio-social risk architecture underpinning the association between parental age and offspring mental health.Peer reviewe
Revisiting Field Capacity (FC): variation of definition of FC and its estimation from pedotransfer functions
Plasma gut hormone levels in 37 patients with pheochromocytomas
Pheochromocytomas are usually recognized by the effects of overproduction of catecholamines, but there are clinical features that cannot be ascribed to catecholamine excess that may be due to vasoactive peptides. We, therefore, measured blood levels of vasoactive intestinal peptides (VIP), substance P, somatostatin (SS), and motilin in 50 instances in 37 patients with pheochromocytomas-21 malignant, 10 benign intra-adrenal, and 6 ectopic (5 paracardial and 1 perirenal). Hormone levels were considered raised if the level was more than 3 S.D. above the mean value found in 52 healthy subjects. Of the 37 patients, 20 (54%) had an abnormality in 1 or more gut hormone levels. The most common abnormality was a raised SS in 9/37 (24%). In addition to these, however, 3 (8%) others had raised VIP, 5 (13.5%) raised motilin, and 3 (8%) raised substance P. Patients with benign adrenal adenomas had raised levels of SS and substance P. Ectopic pheochromocytomas produced only SS in addition to catecholamines, but malignant pheochromocytomas could secrete all 4 peptides, and more than 1 in the same patient. We conclude that pheochromocytomas may secrete multiple vasoactive peptides, and they are more likely to do so if malignant. Somatostatin is the most commonly secreted peptide and is found with benign adrenal and ectopic (paracardiac) tumors. If the level of more than 1 peptide is elevated, the likelihood of malignancy is significantly increased . Les phĂ©ochromocytomes sont gĂ©nĂ©ralement dĂ©celĂ©spar les effets dĂ»s Ă la surproduction de catĂ©cholamines, mais certains troubles ne peuvent ĂȘtre attribuĂ©s Ă ce phĂ©nomĂšne et relĂšvent peut ĂȘtre de l'action de peptides vasoactifs. Les auteurs se sont donc attachĂ©s Ă doser dans le sang le VIP, la substance P, la somatostatine (SS), et la motiline. Ces dosages furent pratiquĂ©s 50 fois chez 37 malades porteurs de phĂ©ochromocytomes: 21 malins, 10 bĂ©nins et 6 ectopiques (5 paracardiaque et 1 pĂ©ri-rĂ©nal). Les taux des hormones furent considĂ©rĂ©s comme Ă©levĂ©s lorsque leur niveau fut supĂ©rieur Ă plus de 3 fois le taux de 52 sujets sains. Sur les 37 malades 20 (54%) prĂ©sentaient un excĂšs d'une ou de plusieurs hormones digestives. L'anomalie constatĂ©e la plus frĂ©quente fut l'Ă©lĂ©vation de la SS (9 fois sur 37 soit 24%). AjoutĂ©e Ă ce fait fut l'Ă©lĂ©vation de la VIP chez 3 sujets (8%), de la motiline chez 5 (13.5%) et de la substance P chez 3 (8%). Les phĂ©ochromocytomes bĂ©nins surrĂ©naliens prĂ©sentaient Ă la fois une Ă©lĂ©vation du taux de la SS et de la substance P. Les phĂ©ochromocytomes ectopiques en revanche prĂ©sentaient seulement une Ă©lĂ©vation de la SS. Les phĂ©ochromocytomes malins pouvaient sĂ©crĂ©ter les 4 peptides ou plus d'un chez le mĂȘme malade. En conclusion les phĂ©ochromocytomes peuvent secrĂ©ter de multiples peptides vasoactifs et plus particuliĂšrement lorsqu'ils sont malins. La SS est la substance qui est la plus souvent secrĂ©tĂ©e et elle est trouvĂ©e dans les tumeurs bĂ©nignes surrĂ©naliennes ou ectopiques. Si plus d'une de ces substances est produite en excĂšs les risques de malignitĂ© de la tumeur sont significativement plus importants. Los feocromocitomas generalmente son diagnosticados por los efectos del exceso de producciĂłn de catecolaminas pero hay caracterĂsticas clĂnicas que no pueden ser atribuidas al exceso de catecolaminas y que pueden ser mĂĄs bien manifestaciĂłn de pĂ©ptidos vasoactivos. Hemos establecido los niveles sanguĂneos del pĂ©ptido intestinal vasoactivo (VIP), de la sustancia P, de la somatostatina (SS), y de la motilina en 50 determinaciones en 37 pacientes con feocromocitomas; 21 malignos, 10 benignos intra-adrenales, y 6 ectĂłpicos (5 paracardiales y 1 perirrenal). Se considerĂł que los niveles hormonales estaban elevados cuando el nivel era de mĂĄs de 3 de desviaciĂłn estandar sobre el valor promedio en 52 individuos normales. De 37 pacientes, 20 (54%) presentaron un valor anormal en 1 o mĂĄs determinaciones del nivel de hormonas intestinales. La anormalidad mĂĄs comĂșn fue la elevaciĂłn de la SS en 9/37 (24%). AdemĂĄs de esto, sinembargo, otros 3 (8%) presentaban elevaciĂłn de VIP, 5 (13.5%) elevaciĂłn de sustancia P. Los adenomas suprarrenales benignos exhibieron niveles elevados de SS y de sustancia P. Los feocromocitomas ectĂłpicos demostraron producciĂłn sĂłlo de SS ademĂĄs de catecolaminas, pero los feocromocitomas malignos demostraron ser capaces de secretar todos los 4 pĂ©ptidos, y mĂĄs de 1 en el mismo paciente. Hemos llegado a la conclusiĂłn de que los feocromocitomas pueden secretar mĂșltiples peptidos vasoactivos y que Ă©sto tiende a ocurrir cuando son malignos. La SS es el pĂ©ptido mĂĄs frecuentemente secretado y se lo encuentra en los tumores suprarrenales benigno y ectĂłpico (paracardiacos). Si se encuentran niveles elevados de mĂĄs de 1 pĂ©ptido, la posibilidad de malignidad aparece significativamente aumentada.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41274/1/268_2005_Article_BF01655534.pd
The effect of transposable elements on phenotypic variation: insights from plants to humans
Study of the lineshape of the chi(c1) (3872) state
A study of the lineshape of the chi(c1) (3872) state is made using a data sample corresponding to an integrated luminosity of 3 fb(-1) collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate chi(c1)(3872) and psi(2S) mesons from b-hadron decays are selected in the J/psi pi(+)pi(-) decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the chi(c1 )(3872) and psi(2S) states, Delta m, and the width of the chi(c1 )(3872) state, Gamma(Bw), are determined to be (Delta m=185.598 +/- 0.067 +/- 0.068 Mev,)(Gamma BW=1.39 +/- 0.24 +/- 0.10 Mev,) where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be (mode=3871.69+0.00+0.05 MeV.)(FWHM=0.22-0.04+0.13+0.07+0.11-0.06-0.13 MeV, ) An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasibound D-0(D) over bar*(0) state but a quasivirtual state is still allowed at the level of 2 standard deviations
The LHCb upgrade I
The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software
Measurement of the CKM angle in and decays with
A measurement of -violating observables is performed using the decays
and , where the meson is
reconstructed in one of the self-conjugate three-body final states and (commonly denoted ). The decays are analysed in bins of the -decay phase space, leading
to a measurement that is independent of the modelling of the -decay
amplitude. The observables are interpreted in terms of the CKM angle .
Using a data sample corresponding to an integrated luminosity of
collected in proton-proton collisions at centre-of-mass
energies of , , and with the LHCb experiment,
is measured to be . The hadronic
parameters , , , and ,
which are the ratios and strong-phase differences of the suppressed and
favoured decays, are also reported
- âŠ