283 research outputs found
TT¯ -deformed actions and (1,1) supersymmetry
We describe an algorithmic method to calculate the TT¯ deformed Lagrangian of a given seed theory by solving an algebraic system of equations. This method is derived from the topological gravity formulation of the deformation. This algorithm is far simpler than the direct partial differential equations needed in most earlier proposals. We present several examples, including the deformed Lagrangian of (1,1) supersymmetry. We show that this Lagrangian is off-shell invariant through order λ2 in the deformation parameter and verify its SUSY algebra through order λ.Fil: Coleman, Evan Austen. University of Stanford. Physics Department; Estados UnidosFil: Aguilera Damia, Jeremías. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Freedman, Daniel Z.. University of Stanford. Physics Department; Estados Unidos. Massachusetts Institute of Technology; Estados UnidosFil: Soni, Ronak M.. University of Stanford. Physics Department; Estados Unido
Soft Supersymmetry Breaking Induced by Higher-Derivative Supergravitation in the Electroweak Standard Model
We show how spontaneous supersymmetry breaking in the vacuum state of
higher-derivative supergravity is transmitted, as explicit soft
supersymmetry-breaking terms, to the effective Lagrangian of the standard
electroweak model. The general structure of the soft supersymmetry breaking
terms is presented and a new scenario for understanding the gauge hierarchy
problem, based on the functional form of these terms, is discussed.Comment: LaTeX2e with AMS-LaTeX 1.2, 13 page
Preparation of Carbon Aerogels from Polymer-Cross-Linked Xerogel Powders Without Supercritical Fluid Drying and their Application in Highly Selective CO2Adsorption
Carbon aerogels are well-known materials for their high porosity and high surface areas. They are typically made from pyrolysis of carbonizable polymeric aerogels. Here, we report an alternative route to monolithic carbon aerogels starting from xerogel powders. Use of powders speeds up solvent exchanges along sol-gel processing, and xerogelling bypasses the supercritical fluid drying step that is needed for making polymeric aerogels. Overall, this alternative route results in time, energy, and materials efficiency in the fabrication of carbon aerogels. Specifically, polymer-cross-linked silica xerogel powders were prepared via free-radical surface-initiated polymerization of acrylonitrile (AN) on a suspension of silica particles derived from tetramethylorthosilicate (TMOS) surface modified with 3-aminopropyltriethoxysilane (APTES)-derived initiator. Alternatively, cross-linked silica xerogel powders were prepared with a carbonizable polyurea (PUA) derived from the reaction of an aromatic triisocyanate (tris(4-isocyanatophenyl)methane) with -OH, -NH2, and adsorbed water on the surface of a TMOS/APTES-derived silica suspension. Wet-gel powders by either method were dried under vacuum at 50 °C to xerogel powders, which were compressed into discs. In turn, these discs were carbonized and then they were treated with HF to remove silica and with CO2 to create microporosity. The resulting monolithic carbon aerogels had porosities up to 83% v/v, Brunauer-Emmett-Teller (BET) surface areas up to 1934 m2 g-1, and could uptake up to 9.15 mmol g-1 of CO2 at 273 K, with high selectivity over H2, N2, and CH4
Plasma Cleaning of Steam Ingressed ITER First Mirrors
In ITER, the first mirrors (FMs) are vulnerable to an in-vessel coolant leak which could severely diminish their optical properties. To understand the scope of this potential impact, several FM samples were exposed to a steam and humidity test simulating the event in ITER. Both rhodium and molybdenum mirrors, observed a loss in specular reflectivity as a result (the loss being greater for the Mo mirror). Their surfaces were tarnished with the development a thin Rh oxide and a thick Mo oxide (120–170 nm). This study focusses on capacitively coupled radio frequency (CCRF) plasma cleaning of steam ingressed (SI) FM samples and follow their optical recovery. Plasma cleaning experiments were performed with 13.56 MHz CCRF plasma using argon and/or hydrogen as process gas (with 230 eV ion energy). Initial and final reflectivity measurements, chemical surface analysis using in vaccuo X-ray photoelectron spectroscopy, scanning electron microscopy, focused ion beam and roughness measurements, were carried out for each sample to evaluate the cleaning efficiency. Using the plasma cleaning technique, it was possible to remove the SI induced contamination from the mirror surfaces and recover their optical properties to the pristine levels. Several ‘voids/inclusions’ were seen to arise along the grain boundaries as a result of the SI procedure. The concentration of these ‘voids/inclusions’ was observed to increase till a certain point followed by a decrease with increasing cleaning time
Dugesia Japonica Is The Best Suited Of Three Planarian Species For High-Throughput Toxicology Screening
High-throughput screening (HTS) using new approach methods is revolutionizing toxicology. Asexual freshwater planarians are a promising invertebrate model for neurotoxicity HTS because their diverse behaviors can be used as quantitative readouts of neuronal function. Currently, three planarian species are commonly used in toxicology research: Dugesia japonica, Schmidtea mediterranea, and Girardia tigrina. However, only D. japonica has been demonstrated to be suitable for HTS. Here, we assess the two other species for HTS suitability by direct comparison with D. japonica. Through quantitative assessments of morphology and multiple behaviors, we assayed the effects of 4 common solvents (DMSO, ethanol, methanol, ethyl acetate) and a negative control (sorbitol) on neurodevelopment. Each chemical was screened blind at 5 concentrations at two time points over a twelve-day period. We obtained two main results: First, G. tigrina and S. mediterranea planarians showed significantly reduced movement compared to D. japonica under HTS conditions, due to decreased health over time and lack of movement under red lighting, respectively. This made it difficult to obtain meaningful readouts from these species. Second, we observed species differences in sensitivity to the solvents, suggesting that care must be taken when extrapolating chemical effects across planarian species. Overall, our data show that D. japonica is best suited for behavioral HTS given the limitations of the other species. Standardizing which planarian species is used in neurotoxicity screening will facilitate data comparisons across research groups and accelerate the application of this promising invertebrate system for first-tier chemical HTS, helping streamline toxicology testing
and channels of decay at the physical point with periodic boundary conditions
We present a lattice calculation of the matrix elements and
amplitudes with both the and 1/2 channels and ,
the measure of direct violation. We use periodic boundary conditions
(PBC), where the correct kinematics of can be achieved via an
excited two-pion final state. To overcome the difficulty associated with the
extraction of excited states, our previous work \cite{Bai:2015nea,RBC:2020kdj}
successfully employed G-parity boundary conditions, where pions are forced to
have non-zero momentum enabling the two-pion ground state to express the
on-shell kinematics of the decay. Here instead we overcome the
problem using the variational method which allows us to resolve the two-pion
spectrum and matrix elements up to the relevant energy where the decay
amplitude is on-shell.
In this paper we report an exploratory calculation of decay
amplitudes and using PBC on a coarser lattice size of
with inverse lattice spacing GeV and the physical
pion and kaon masses. The results are promising enough to motivate us to
continue our measurements on finer lattice ensembles in order to improve the
precision in the near future
Predictors of multidomain decline in health‐related quality of life after stereotactic body radiation therapy (SBRT) for prostate cancer
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136687/1/cncr30519_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136687/2/cncr30519.pd
Gaugino Condensation in M-theory on S^1/Z_2
In the low energy limit of for M-theory on S^1/Z_2, we calculate the gaugino
condensate potential in four dimensions using the background solutions due to
Horava. We show that this potential is free of delta-function singularities and
has the same form as the potential in the weakly coupled heterotic string. A
general flux quantization rule for the three-form field of M-theory on S^1/Z_2
is given and checked in certain limiting cases. This rule is used to fix the
free parameter in the potential originating from a zero mode of the form field.
Finally, we calculate soft supersymmetry breaking terms. We find that
corrections to the Kahler potential and the gauge kinetic function, which can
be large in the strongly coupled region, contribute significantly to certain
soft terms. In particular, for supersymmetry breaking in the T-modulus
direction, the small values of gaugino masses and trilinear couplings that
occur in the weakly coupled, large radius regime are enhanced to order m_3/2 in
M-theory. The scalar soft masses remain small even, in the strong coupling
M-theory limit.Comment: 20 pages, LATE
Chronic Stress Prevents Cortico-Accumbens Cue Encoding and Alters Conditioned Approach
Chronic stress impairs the function of multiple brain regions and causes severe hedonic and motivational deficits. One brain region known to be susceptible to these effects is the PFC. Neurons in this region, specifically neuronal projections from the prelimbic region (PL) to the nucleus accumbens core (NAcC), have a significant role in promoting motivated approach. However, little is known about how activity in this pathway changes during associative learning to encode cues that promote approach. Less is known about how activity in this pathway may be altered by stress. In this study, an intersectional fiber photometry approach was used in male Sprague Dawley rats engaged in a Pavlovian autoshaping design to characterize the involvement of the PL-NAcC pathway in the typical acquisition of learned approach (directed at both the predictive cue and the goal), and its potential alteration by stress. Specifically, the hypothesis that neural activity in PL-NAcC would encode a Pavlovian approach cue and that prior exposure to chronic stress would disrupt both the nature of conditioned approach and the encoding of a cue that promotes approach was tested. Results of the study demonstrated that the rapid acquisition of conditioned approach was associated with cue-induced PL-NAcC activity. Prior stress both reduced cue-directed behavior and impaired the associated cortical activity. These findings demonstrate that prior stress diminishes the task-related activity of a brain pathway that regulates approach behavior. In addition, the results support the interpretation that stress disrupts reward processing by altering the incentive value of associated cues
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