Dissipation of the sectored heliospheric magnetic field near the heliopause: a mechanism for the generation of anomalous cosmic rays

The recent observations of the anomalous cosmic ray (ACR) energy spectrum as Voyagers 1 and 2 crossed the heliospheric termination shock have called into question the conventional shock source of these energetic particles. We suggest that the sectored heliospheric magnetic field, which results from the flapping of the heliospheric current sheet, piles up as it approaches the heliopause, narrowing the current sheets that separate the sectors and triggering the onset of collisionless magnetic reconnection. Particle-in-cell simulations reveal that most of the magnetic energy is released and most of this energy goes into energetic ions with significant but smaller amounts of energy going into electrons. The energy gain of the most energetic ions results from their reflection from the ends of contracting magnetic islands, a first order Fermi process. The energy gain of the ions in contracting islands increases their parallel (to the magnetic field ${\bf B}$) pressure $p_\parallel$ until the marginal firehose condition is reached, causing magnetic reconnection and associated particle acceleration to shut down. The model calls into question the strong scattering assumption used to derive the Parker transport equation and therefore the absence of first order Fermi acceleration in incompressible flows. A simple 1-D model for particle energy gain and loss is presented in which the feedback of the energetic particles on the reconnection drive is included. The ACR differential energy spectrum takes the form of a power law with a spectral index slightly above 1.5. The model has the potential to explain several key Voyager observations, including the similarities in the spectra of different ion species.Comment: Submitted to ApJ; shortened abstract; degraded figure qualit

Resurrecting light stops after the 125 GeV Higgs in the baryon number violating CMSSM

In order to accommodate the observed Higgs boson mass in the CMSSM, the stops must either be very heavy or the mixing in the stop sector must be very large. Lower stop masses, possibly more accessible at the LHC, still give the correct Higgs mass only if the trilinear stop mixing parameter $|A_t|$ is in the multi-TeV range. Recently it has been shown that such large stop mixing leads to an unstable electroweak vacuum which spontaneously breaks charge or colour. In this work we therefore go beyond the CMSSM and investigate the effects of including baryon number violating operators $\lambda'' \bar{\bf U} \bar{\bf D}\bar{\bf D}$ on the stop and Higgs sectors. We find that for $\lambda'' \simeq {\mathcal{O}}(0.3)$ light stop masses as low as 220 GeV are consistent with the observed Higgs mass as well as flavour constraints while allowing for a stable vacuum. The light stop in this scenario is often the lightest supersymmetric particle. We furthermore discuss the importance of the one-loop corrections involving R-parity violating couplings for a valid prediction of the light stop masses.Comment: 26 pages, 9 figures; v2: slightly extended discussion about bounds from flavour observables; matches published versio

Fermion Masses and Mixing in Four and More Dimensions

We give an overview of recent progress in the study of fermion mass and flavor mixing phenomena. Mass matrix ansatze are considered within the SM and SUSY GUTs where some predictive frameworks based on SU(5) and SO(10) are reviewed. We describe a variety of schemes to construct quark mass matrices in extra dimensions focusing on four major classes: models with the SM residing on 3-brane, models with universal extra dimensions, models with split fermions and models with warped extra dimensions. We outline how realistic patterns of quark mass matrices could be derived from orbifold models in heterotic superstring theory. Finally, we address the fermion mass problem in intersecting D-branes scenarios, and present models with D6-branes able to give a good quantitatively description of quark masses and mixing. The role of flavor/CP violation problem as a probe of new physics is emphasized.Comment: a review based on seminars presented by S.K. in different places, 34 pages, late

Sunscreen use and intentional exposure to ultraviolet A and B radiation: a double blind randomized trial using personal dosimeters

A previous randomized trial found that sunscreen use could extend intentional sun exposure, thereby possibly increasing the risk of cutaneous melanoma. In a similarly designed trial, we examined the effect of the use of sunscreens having different sun protection factor (SPF) on actual exposure to ultraviolet B (UVB) and ultraviolet A (UVA) radiation. In June 1998, 58 European participants 18–24 years old were randomized to receive a SPF 10 or 30 sunscreens and were asked to complete daily records of their sun exposure during their summer holidays of whom 44 utilized a personal UVA and UVB dosimeter in a standard way during their sunbathing sessions. The median daily sunbathing duration was 2.4 hours in the SPF 10 group and 3.0 hours in the SPF 30 group (P = 0.054). The increase in daily sunbathing duration was paralleled by an increase in daily UVB exposure, but not by changes in UVA or UVB accumulated over all sunbathing sessions, or in daily UVA exposure. Of all participants, those who used the SPF 30 sunscreen and had no sunburn spent the highest number of hours in sunbathing activities. Differences between the two SPF groups in total number of sunbathing hours, daily sunbathing duration, and daily UVB exposure were largest among participants without sunburn during holidays. Among those with sunburn, the differences between the two groups tended to reduce. In conclusion, sunscreens used during sunbathing tended to increase the duration of exposures to doses of ultraviolet radiation below the sunburn threshold. © 2000 Cancer Research Campaig

Cardiac troponin T is elevated and increases longitudinally in ALS patients.

Objective: To test whether high-sensitivity cardiac troponin T (hs-cTnT) could act as a diagnostic or prognostic biomarker in ALS, comparing hs-cTnT to neurofilament light (NfL). Methods: We performed a case-control study, including 150 ALS patients, 28 ALS mimics, and 108 healthy controls, and a follow-up study of the ALS patients, during 2014-2020 in Stockholm, Sweden. We compared concentrations of hs-cTnT in plasma and NfL in the cerebrospinal fluid between cases and controls. To evaluate the diagnostic performance, we calculated the area under the curve (AUC). Hazard ratios (HRs) were estimated from Cox models to assess associations between hs-cTnT and NfL at ALS diagnosis and risk of death. The longitudinal analysis measured changes of hs-cTnT and NfL since ALS diagnosis. Results: We noted higher levels of hs-cTnT in ALS patients (median: 16.5 ng/L) than in ALS mimics (11 ng/L) and healthy controls (6 ng/L). Both hs-cTnT and NfL could distinguish ALS patients from ALS mimics, with higher AUC noted for NfL (AUC 0.88; 95%CI 0.79-0.97). Disease progression correlated weakly with hs-cTnT (Pearson's r = 0.18, p = 0.04) and moderately with NfL (Pearson's r = 0.41, p < 0.001). Shorter survival was associated with higher levels of NfL at diagnosis (HR 1.08, 95%CI 1.04-1.11), but not hs-cTnT. hs-cTnT increased (12.61 ng/L per year, 95%CI 7.14-18.06) whereas NfL decreased longitudinally since ALS diagnosis. Conclusions: NfL is a stronger diagnostic and prognostic biomarker than hs-cTnT for ALS. However, hs-cTnT might constitute a disease progression biomarker as it increases longitudinally. The underlying causes for this increase need to be investigated

Investigation of venting turbidity currents in the Rudbar-Lorestan reservoir in Iran

Venting of turbidity currents is known as an efficient measure to prevent reservoir sedimentation and is applied in many reservoirs globally. It has several economic and ecological advantages compared with other evacuation methods. In the literature, numerous researchers mentioned the importance of venting, but mostly qualitatively. Given the complexity of the phenomenon and the presence of many parameters affecting the efficiency of venting, case studies offer good insight into solutions for specific reservoirs where there is a high probability of occurrence of turbidity currents. In the present study, the efficiency of venting turbidity currents is investigated for Lorestan Reservoir in Iran. For that purpose, 3D numerical simulations of turbidity currents over 11 km and venting operation are performed using ANSYS Inc. software. The results of the present research allow to optimize venting operations in the Lorestan Reservoir and reservoirs having similar general characteristics. Recommendations are drawn on outlet opening timing and discharge allowing to vent the greater amount of sediments while minimizing the water release

Electroweak Supersymmetry around the Electroweak Scale

Inspired by the phenomenological constraints, LHC supersymmetry and Higgs searches, dark matter search as well as string model building, we propose the electroweak supersymmetry around the electroweak scale: the squarks and/or gluinos are around a few TeV while the sleptons, sneutrinos, bino and winos are within one TeV. The Higgsinos can be either heavy or light. We consider bino as the dominant component of dark matter candidate, and the observed dark matter relic density is achieved via the neutralino-stau coannihilations. Considering the Generalized Minimal Supergravity (GmSUGRA), we show explicitly that the electroweak supersymmetry can be realized, and the gauge coupling unification can be preserved. With two Scenarios, we study the viable parameter spaces that satisfy all the current phenomenological constraints, and we present the concrete benchmark points. Furthermore, we comment on the fine-tuning problem and LHC searches.Comment: RevTex4, 28 pages, 8 figures, 8 tables, version to appear in EPJ

Cholinergic Potentiation Alters Perceptual Eye Dominance Plasticity Induced by a Few Hours of Monocular Patching in Adults

A few hours of monocular deprivation with a diffuser eye patch temporarily strengthens the contribution of the deprived eye to binocular vision. This shift in favor of the deprived eye is characterized as a form of adult visual plasticity. Studies in animal and human models suggest that neuromodulators can enhance adult brain plasticity in general. Specifically, acetylcholine has been shown to improve certain aspects of visual function and plasticity in adulthood. We investigated whether a single administration of donepezil (a cholinesterase inhibitor) could further augment the temporary shift in perceptual eye dominance that occurs after 2 h of monocular patching. Twelve healthy adults completed two experimental sessions while taking either donepezil (5 mg, oral) or a placebo (lactose) pill. We measured perceptual eye dominance using a binocular phase combination task before and after 2 h of monocular deprivation with a diffuser eye patch. Participants in both groups demonstrated a significant shift in favor of the patched eye after monocular deprivation, however our results indicate that donepezil significantly reduces the magnitude and duration of the shift. We also investigated the possibility that donepezil reduces the amount of time needed to observe a shift in perceptual eye dominance relative to placebo control. For this experiment, seven subjects completed two sessions where we reduced the duration of deprivation to 1 h. Donepezil reduces the magnitude and duration of the patching-induced shift in perceptual eye dominance in this experiment as well. To verify whether the effects we observed using the binocular phase combination task were also observable in a different measure of sensory eye dominance, six subjects completed an identical experiment using a binocular rivalry task. These results also indicate that cholinergic enhancement impedes the shift that results from short-term deprivation. In summary, our study demonstrates that enhanced cholinergic potentiation interferes with the consolidation of the perceptual eye dominance plasticity induced by several hours of monocular deprivation

Constraints on the Variations of the Fundamental Couplings

We reconsider several current bounds on the variation of the fine-structure constant in models where all gauge and Yukawa couplings vary in an interdependent manner, as would be expected in unified theories. In particular, we re-examine the bounds established by the Oklo reactor from the resonant neutron capture cross-section of 149Sm. By imposing variations in \Lambda_{QCD} and the quark masses, as dictated by unified theories, the corresponding bound on the variation of the fine-structure constant can be improved by about 2 orders of magnitude in such theories. In addition, we consider possible bounds on variations due to their effect on long lived \alpha- and \beta-decay isotopes, particularly 147Sm and 187Re. We obtain a strong constraint on \Delta \alpha / \alpha, comparable to that of Oklo but extending to a higher redshift corresponding to the age of the solar system, from the radioactive life-time of 187Re derived from meteoritic studies. We also analyze the astrophysical consequences of perturbing the decay Q values on bound state \beta-decays operating in the s-process.Comment: 25 pages, latex, 5 eps figure

Dynamic Interpretation of Hedgehog Signaling in the Drosophila Wing Disc

Morphogens are classically defined as molecules that control patterning by acting at a distance to regulate gene expression in a concentration-dependent manner. In the Drosophila wing imaginal disc, secreted Hedgehog (Hh) forms an extracellular gradient that organizes patterning along the anterior–posterior axis and specifies at least three different domains of gene expression. Although the prevailing view is that Hh functions in the Drosophila wing disc as a classical morphogen, a direct correspondence between the borders of these patterns and Hh concentration thresholds has not been demonstrated. Here, we provide evidence that the interpretation of Hh signaling depends on the history of exposure to Hh and propose that a single concentration threshold is sufficient to support multiple outputs. Using mathematical modeling, we predict that at steady state, only two domains can be defined in response to Hh, suggesting that the boundaries of two or more gene expression patterns cannot be specified by a static Hh gradient. Computer simulations suggest that a spatial “overshoot” of the Hh gradient occurs, i.e., a transient state in which the Hh profile is expanded compared to the Hh steady-state gradient. Through a temporal examination of Hh target gene expression, we observe that the patterns initially expand anteriorly and then refine, providing in vivo evidence for the overshoot. The Hh gene network architecture suggests this overshoot results from the Hh-dependent up-regulation of the receptor, Patched (Ptc). In fact, when the network structure was altered such that the ptc gene is no longer up-regulated in response to Hh-signaling activation, we found that the patterns of gene expression, which have distinct borders in wild-type discs, now overlap. Our results support a model in which Hh gradient dynamics, resulting from Ptc up-regulation, play an instructional role in the establishment of patterns of gene expression