Gluon propagation inside a high-energy nucleus

We show that, in the light-cone gauge, it is possible to derive in a very simple way the solution of the classical Yang-Mills equations for the collision between a nucleus and a proton. One important step of the calculation is the derivation of a formula that describes the propagation of a gluon in the background color field of the nucleus. This allows us to calculate observables in pA collisions in a more straightforward fashion than already proposed. We discuss also the comparison between light-cone gauge and covariant gauge in view of further investigations involving higher order corrections.Comment: 12 pages, 2 figure

Gas pressure sintering of Beta-Sialon with Z=3

An experiment conducted on beta-sialon in atmospheric pressure, using a temperature of 2000 C and 4 MPa nitrogen atmosphere, is described. Thermal decomposition was inhibited by the increase of the nitrogen gas pressure

The Disability Frame

This essay is the Foreword to the 2022 University of Pennsylvania Law Review symposium on “The Disability Frame.” “The disability frame” refers to the characterization of a particular controversy or problem as being “about” disability, which in turn can imply that disability-focused laws ought to resolve or adjudicate the issue. We see this frame function in at least four ways. First, the disability frame is sometimes invoked as a shield, with the hope that it will insulate someone from the reach of the state or exempt a person from an unwelcome or onerous responsibility (e.g., jury service, vaccination, a criminal sentence). Second, the disability frame may function more like a positive right, offering access to such resources as housing, accessible transportation, educational services, health care, and income support.Third, the disability frame may form the basis for a more systemic or policy-level demand on the state, such as masking requirements, abortion restriction, or government-funded healthcare. Fourth and most darkly, the disability frame has sometimes served as a reason to deny individuals basic rights and freedoms, such as sexual agency. What runs across these examples is contingency: the disability frame is rarely the only available option; when an issue or problem is framed in disability terms, that framing reflects a calculation, a choice. Notably, the disability frame has become a more prevalent choice in recent years. It is discernible not only in legal scholarship, but also in court filings, activist campaigns, and public debates. Why is this the case? And how should we evaluate this trend? These questions animate the contributions to this symposium. After introducing the concept of the disability frame, this essay pursues two goals. (1) We provide an overview of several themes we see running throughout the symposium, and by extension, throughout the suite of disability laws and policies that the disability frame rests upon. We focus our discussion on opportunities, costs, and constraints. (2) Because we hope this symposium will serve as a model for others, we summarize how we and our collaborators attempted to incorporate a disability justice perspective into the design of the symposium itself. We conclude with reflections on what can be gained from a critical examination of the disability frame and how that intellectual project connects to broader struggles for inclusion

Baryon stopping and saturation physics in relativistic collisions

We investigate baryon transport in relativistic heavy-ion collisions at energies reached at the CERN Super Proton Synchrotron, BNL Relativistic Heavy-Ion Collider (RHIC), and CERN LHC in the model of saturation. An analytical scaling law is derived within the color glass condensate framework based on small-coupling QCD. Transverse momentum spectra, net-baryon rapidity distributions and their energy, mass and centrality dependences are well described. In a comparison with RHIC data in Au + Au collisions at sqrt (s_NN) = 62.4 GeV and 200 GeV, the gradual approach to the gluon saturation regime is investigated, and limits for the saturation-scale exponent are determined. Predictions for net-baryon rapidity spectra and the mean rapidity loss in central Pb + Pb collisions at LHC energies of sqrt (s_NN) = 5.52 TeV are made.Comment: 11 pages, 10 Figures; improved figure inscriptions, corrected typos, minor changes in text/titl

Baryon Stopping as a new Probe of Geometric Scaling

We suggest to use net-baryon rapidity distributions in central relativistic heavy-ion collisions at SPS, RHIC and LHC energies in order to probe saturation physics. Within the color glass condensate framework based on small-coupling QCD, net-baryon rapidity distributions are shown to exhibit geometric scaling. In a comparison with RHIC data in Au + Au collisions at sqrt(s_NN) = 62.4 GeV and 200 GeV the gradual approach to the gluon saturation regime is investigated. Predictions for net-baryon rapidity spectra and the mean rapidity loss in central Pb + Pb collisions at LHC energies of sqrt (s_NN) = 5.5 TeV are made.Comment: 4 pages 3 figures; calculation and figures now for net baryons instead of net protons; modified conclusion

Single molecule and single quantum dot photodynamics by polarization-rotating modulation microscopy

We present our recent study of polarization modulating fluorescence imaging microscopy on single CdSe colloidal quantum dots (QDs) and quantum rods (QRs) adsorbed on silica glass substrates at room temperatures. Simple optical setup is introduced to provide detection of emission profiles projected on to the sample plane as well as detection of rotating excitation polarization effect. While most studies so far in structural changes in biological or amorphous systems rely on extrinsic fluorophores with linear transition dipoles, those with twofold degenerate dipoles are noteworthy due to the intrinsic advantage for 3D orientation information. Performance of modulations is also evaluated in combination with tetramethylrodamine moieties as typical linear emitters. CdSe QDs with aspect ratio of 1.3 actually reveal plane-polarized emission at room temperature and, based on maximum-likelihood analysis, are exceptionally highly oriented on silica glass substrates

Historia y frontera

Este artículo pretende reemplazar la idea de “frontera” por la de “catacresis histórica”. La metáfora de la frontera presupone un espacio preexistente y sugiere que nuestro trabajo como historiadores es ir más allá de lugares señalados previamente y revelar la existencia de otros aún no revelados o mejores. Este concepto de frontera, propuesto y discutido en el Congreso de Berkshire titulado “Sin Fronteras: Historias de las Mujeres, conversaciones globales” celebrado en junio de 2005 establece límites conceptuales en el pensamiento. Esto es evidente en el caso de entidades históricas ambiguas como el colonialismo, el género o algunos sistemas específicos de signos. En cambio, el concepto de catacresis histórica, abre vías para leer los materiales de la vida cotidiana como experiencias de cambio económico gradual, o de revolución comercial o de nuevas categorías de sexualidad, por mencionar solo algunos ejemplos. Desde la perspectiva de la catacresis histórica, y leyendo imágenes anacrónicas como la hermosa imagen femenina del fertilizante Bu’nei’men o de la “chica” de la compañía de cosméticos colonial Nakayama Taiyodo, los historiadores podemos acceder a un momento contemporáneo. El artículo finalmente clarifica por qué los trabajos clásicos sobre el semicolonialismo chino han sido, básicamente, reactivos. Sugiere que la lectura de materiales banales, efímeros buscando la emergencia de nuevas singularidades o experiencias radicalmente novedosas tiene la capacidad de reformular las preguntas habituales que los historiadores nos hacemos sobre el contexto, la subjetividad, la experiencia y la representación