Effect of lubricant environment on saw damage in silicon wafers

The chemomechanical effect of lubricant environments on the inner diameter (ID) sawing induced surface damage in Si wafers was tested for four different lubricants: water, dielectric oil, and two commercial cutting solutions. The effects of applying different potential on Si crystals during the sawing were also tested. It is indicated that the number and depth of surface damage are sensitive to the chemical nature of the saw lubricant. It is determined that the lubricants that are good catalysts for breaking Si bonds can dampen the out of plane blade vibration more effectively and produce less surface damage. Correlations between the applied potential and the depth of damage in the dielectric oil and one of the commercial cutting solutions and possible mechanisms involved are discussed

Toward Full LHC Coverage of Natural Supersymmetry

We argue that combining just a handful of searches for new physics at Run I of the LHC is sufficient to exclude most supersymmetric extensions of the Standard Model in which the gluino is kinematically accessible and the spectrum is natural. Such models typically give rise to significant MET, top quarks and/or high object multiplicity, and we show that having even one of these signatures generally results in stringent limits. We also identify, among models that lack these signatures, the few gaps in coverage remaining, and propose search strategies to close these gaps. Our results are general and independent of the details of the spectrum, assumptions about minimality, R-parity, etc. Our analysis strategy should remain applicable when the LHC moves to higher energy. Central to our argument are ATLAS and CMS searches for many jets and low MET, a proposed lepton + many jets search, an ATLAS search for 6-7 high-pT jets, and a reexamination of the control and signal regions of the CMS black hole search.Comment: 53 pages, 16 figures, journal versio

Visualizing Quantum Well State Perturbations of Metallic Thin Films near Stacking Fault Defects

We demonstrate that quantum well states (QWS) of thin Pb films are highly perturbed within the proximity of intrinsic film defects. Scanning Tunneling Spectroscopy (STM/STS) measurements indicate that the energy of these states have a strong distance dependence within 4 nm of the defect with the strongest energetic fluctuations equaling up to 100 meV. These localized perturbations show large spatially-dependent asymmetries in the LDOS around the defect site for each corresponding quantum well state. These energetic fluctuations can be described by a simple model which accounts for fluctuations in the confinement potential induced by topographic changes.Comment: Updated Versio

Understanding Rates of Marijuana Use and Consequences Among Adolescents in a Changing Legal Landscape.

Purpose of Review:There is not one answer to address whether marijuana use has increased, decreased, or stayed the same given changes in state legalization of medical and non-medical marijuana in the USA. Recent Findings:Evidence suggests some health benefits for medical marijuana; however, initiation of marijuana use is a risk factor for developing problem cannabis use. Though use rates have remained stable over recent years, about one in three 10th graders report marijuana use, most adolescents do not view the drug as harmful, and over 650,000 youth aged 12 to 17 struggle with cannabis use disorder. Summary:Although the health benefits of medical marijuana are becoming better understood, more research is needed. Intervention and prevention programs must better address effects of marijuana, acknowledging that while there may be some benefits medically, marijuana use can affect functioning during adolescence when the brain is still developing

Batalin-Vilkovisky Integrals in Finite Dimensions

The Batalin-Vilkovisky method (BV) is the most powerful method to analyze functional integrals with (infinite-dimensional) gauge symmetries presently known. It has been invented to fix gauges associated with symmetries that do not close off-shell. Homological Perturbation Theory is introduced and used to develop the integration theory behind BV and to describe the BV quantization of a Lagrangian system with symmetries. Localization (illustrated in terms of Duistermaat-Heckman localization) as well as anomalous symmetries are discussed in the framework of BV.Comment: 35 page

Boundary layer on the surface of a neutron star

In an attempt to model the accretion onto a neutron star in low-mass X-ray binaries, we present two-dimensional hydrodynamical models of the gas flow in close vicinity of the stellar surface. First we consider a gas pressure dominated case, assuming that the star is non-rotating. For the stellar mass we take M_{\rm star}=1.4 \times 10^{-2} \msun and for the gas temperature $T=5 \times 10^6$ K. Our results are qualitatively different in the case of a realistic neutron star mass and a realistic gas temperature of $T\simeq 10^8$ K, when the radiation pressure dominates. We show that to get the stationary solution in a latter case, the star most probably has to rotate with the considerable velocity.Comment: 7 pages, 7 figure

New high-efficiency source of photon pairs for engineering quantum entanglement

We have constructed an efficient source of photon pairs using a waveguide-type nonlinear device and performed a two-photon interference experiment with an unbalanced Michelson interferometer. Parametric down-converted photons from the nonlinear device are detected by two detectors located at the output ports of the interferometer. Because the interferometer is constructed with two optical paths of different length, photons from the shorter path arrive at the detector earlier than those from the longer path. We find that the difference of arrival time and the time window of the coincidence counter are important parameters which determine the boundary between the classical and quantum regime. When the time window of the coincidence counter is smaller than the arrival time difference, fringes of high visibility (80$\pm$ 10%) were observed. This result is only explained by quantum theory and is clear evidence for quantum entanglement of the interferometer's optical paths.Comment: 4 pages, 4 figures, IQEC200

Diffusion due to the Beam-Beam Interaction and Fluctuating Fields in Hadron Colliders

Random fluctuations in the tune, beam offsets and beam size in the presence of the beam-beam interaction are shown to lead to significant particle diffusion and emittance growth in hadron colliders. We find that far from resonances high frequency noise causes the most diffusion while near resonances low frequency noise is responsible for the large emittance growth observed. Comparison of different fluctuations shows that offset fluctuations between the beams causes the largest diffusion for particles in the beam core.Comment: 5 pages, 3 postscript figure