148 research outputs found
Mapping supply chain risk by network analysis of product platforms
AbstractModern technology makes use of a variety of materials to allow for its proper functioning. To explore in detail the relationships connecting materials to the products that require them, we map supply chains for five product platforms (a cadmium telluride solar cell, a germanium solar cell, a turbine blade, a lead acid battery, and a hard drive (HD) magnet) using a data ontology that specifies the supply chain actors (nodes) and linkages (e.g., material exchange and contractual relationships) among them. We then propose a set of network indicators (product complexity, producer diversity, supply chain length, and potential bottlenecks) to assess the situation for each platform in the overall supply chain networks. Among the results of interest are the following: (1) the turbine blade displays a high product complexity, defined by the material linkages to the platform; (2) the germanium solar cell is produced by only a few manufacturers globally and requires more physical transformation steps than do the other project platforms; (3) including production quantity and sourcing countries in the assessment shows that a large portion of nodes of the supply chain of the hard-drive magnet are located in potentially unreliable countries. We conclude by discussing how the network analysis of supply chains could be combined with criticality and scenario analyses of abiotic raw materials to comprise a comprehensive picture of product platform risk
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Interference, reduced action, and trajectories
Instead of investigating the interference between two stationary, rectilinear
wave functions in a trajectory representation by examining the two rectilinear
wave functions individually, we examine a dichromatic wave function that is
synthesized from the two interfering wave functions. The physics of
interference is contained in the reduced action for the dichromatic wave
function. As this reduced action is a generator of the motion for the
dichromatic wave function, it determines the dichromatic wave function's
trajectory. The quantum effective mass renders insight into the behavior of the
trajectory. The trajectory in turn renders insight into quantum nonlocality.Comment: 12 pages text, 5 figures. Typos corrected. Author's final submission.
A companion paper to "Welcher Weg? A trajectory representation of a quantum
Young's diffraction experiment", quant-ph/0605121. Keywords: interference,
nonlocality, trajectory representation, entanglement, dwell time, determinis
Probing Lorentz and CPT violation with space-based experiments
Space-based experiments offer sensitivity to numerous unmeasured effects
involving Lorentz and CPT violation. We provide a classification of clock
sensitivities and present explicit expressions for time variations arising in
such experiments from nonzero coefficients in the Lorentz- and CPT-violating
Standard-Model Extension.Comment: 15 page
CPT, T, and Lorentz Violation in Neutral-Meson Oscillations
Tests of CPT and Lorentz symmetry using neutral-meson oscillations are
studied within a formalism that allows for indirect CPT and T violation of
arbitrary size and is independent of phase conventions. The analysis is
particularly appropriate for studies of CPT and T violation in oscillations of
the heavy neutral mesons D, B_d, and B_s. The general Lorentz- and CPT-breaking
standard-model extension is used to derive an expression for the parameter for
CPT violation. It varies in a prescribed way with the magnitude and orientation
of the meson momentum and consequently also with sidereal time. Decay
probabilities are presented for both uncorrelated and correlated mesons, and
some implications for experiments are discussed.Comment: 11 pages, references added, accepted in Physical Review
Estudo endócrino reprodutivo e do comportamento sócio-sexual de sagui-de-tufo-preto (Callithrix penicillata) mantido em cativeiro
A comunicação do estado reprodutivo nos primatas da família Callithrichidae, depende principalmente dos comportamentos sócio-sexuais como um sistema de sinalização primário, uma vez que nestas espécies a ovulação não é percebida pelos machos. Neste trabalho, os padrões de comportamentos sócio-sexuais foram analisados em conjunto com as concentrações de metabólitos fecais dos esteróides sexuais progesterona (MFP), estradiol (MFE) e testosterona (MFT) em casais cativos de Sagüi-de-tufos-pretos (Callithrix penicillata), nas diferentes fases do ciclo ovariano. O grupo estudado era composto por quarto casais adultos, mantidos no Centro de Reabilitação de Animais Selvagens da prefeitura de São Paulo. Os padrões comportamentais foram registrados pelo método de amostragem focal por intervalo de tempo a cada 30 segundos, cinco vezes por semana, totalizando 14.400 registros por animal. A mensuração das concentrações de metabólitos fecais dos esteroides sexuais foram realizados pelo método de enzima imunoensaio (EIE). Os resultados obtidos dessas concentrações possibilitaram a determinação endócrina das fases do ciclo ovariano (folicular e luteal) e de suas respectivas durações, assim como a determinação da fase periovulatória. Foram caracterizados 31 ciclos ovarianos completos, com duração de 24,3±4,1 dias (média ±DP), sendo que a fase folicular compreendeu 13,04±4,8dias e a fase lútea 11,2±4,2 dias. Os comportamentos sócio-sexuais (marcação por cheiro, cheirar genitália, catação e apresentação sexual) e a variável "proximidade" mostraram-se significativamente mais prevalentes na fase periovulatória do que nas demais fases do ciclo. Não houve alteração das concentrações de MFT dos machos ao longo de todo o período estudado. A análise conjunta das concentrações de metabólitos fecais de esteróides sexuais e dos comportamentos sócio-sexuais possibilitou um melhor entendimento das relações endócrino-comportamentais e reprodutivas de C. penicillata
Corrections to flat-space particle dynamics arising from space granularity
The construction of effective Hamiltonians describing corrections to flat
space particle dynamics arising from the granularity of space at very short
distances is discussed in the framework of an heuristic approach to the
semiclassical limit of loop quantum gravity. After some general motivation of
the subject, a brief non-specialist introduction to the basic tools employed in
the loop approach is presented. The heuristical semiclassical limit is
subsequently defined and the application to the case of photons and spin 1/2
fermions is described. The resulting modified Maxwell and Dirac Hamiltonians,
leading in particular to Planck scale corrections in the energy-momentum
relations, are presented. Alternative interpretations of the results and their
limitations, together with other approaches are briefly discussed along the
text. Three topics related to the above methods are reviewed: (1) The
determination of bounds to the Lorentz violating parameters in the fermionic
sector, obtained from clock comparison experiments.(2) The calculation of
radiative corrections in preferred frames associated to space granularity in
the framework of a Yukawa model for the interactions and (3) The calculation of
synchrotron radiation in the framework of the Myers-Pospelov effective theories
describing Lorentz invariance violations, as well as a generalized approach to
radiation in Planck scale modified electrodynamics. The above exploratory
results show that quantum gravity phenomenology provides observational guidance
in the construction of quantum gravity theories and opens up the possibility of
probing Planck scale physics.Comment: 49 pages, 6 figures and 4 tables. Extended version of the talk given
at the 339-th WE-Heraeus-Seminar: Special Relativity, will it survive the
next 100 years?, Potsdam, february 200
Non-minimal Maxwell-Modified Gauss-Bonnet Cosmologies: Inflation and Dark Energy
In this paper we show that power-law inflation can be realized in non-minimal
gravitational coupling of electromagnetic field with a general function of
Gauss-Bonnet invariant. Such a non-minimal coupling may appear due to quantum
corrections. We also consider modified Maxwell- gravity in which
non-minimal coupling between electromagnetic field and occur in the
framework of modified Gauss-Bonnet gravity. It is shown that inflationary
cosmology and late-time accelerated expansion of the universe are possible in
such a theory.Comment: 10 pages, no figur
A patient-derived explant (PDE) model of hormone-dependent cancer
Breast and prostate cancer research to date has largely been predicated on the use of cell lines in vitro or in vivo. These limitations have led to the development of more clinically relevant models, such as organoids or murine xenografts that utilize patient-derived material; however, issues related to low take rate, long duration of establishment, and the associated costs constrain use of these models. This study demonstrates that ex vivo culture of freshly resected breast and prostate tumor specimens obtained from surgery, termed patient-derived explants (PDEs), provides a high-throughput and cost-effective model that retains the native tissue architecture, microenvironment, cell viability, and key oncogenic drivers. The PDE model provides a unique approach for direct evaluation of drug responses on an individual patient's tumor, which is amenable to analysis using contemporary genomic technologies. The ability to rapidly evaluate drug efficacy in patient-derived material has high potential to facilitate implementation of personalized medicine approaches.Margaret M. Centenera, Theresa E. Hickey, Shalini Jindal, Natalie K. Ryan, Preethi Ravindranathan, Hisham Mohammed, Jessica L. Robinson, Matthew J. Schiewer, Shihong Ma, Payal Kapur, Peter D. Sutherland, Clive E. Hoffmann, Claus G. Roehrborn, Leonard G. Gomella, Jason S. Carroll, Stephen N. Birrell, Karen E. Knudsen, Ganesh V. Raj, Lisa M. Butler, Wayne D. Tille
Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
We present the first results of the Fermilab Muon g-2 Experiment for the
positive muon magnetic anomaly . The anomaly is
determined from the precision measurements of two angular frequencies.
Intensity variation of high-energy positrons from muon decays directly encodes
the difference frequency between the spin-precession and cyclotron
frequencies for polarized muons in a magnetic storage ring. The storage ring
magnetic field is measured using nuclear magnetic resonance probes calibrated
in terms of the equivalent proton spin precession frequency
in a spherical water sample at 34.7C. The
ratio , together with known fundamental
constants, determines
(0.46\,ppm). The result is 3.3 standard deviations greater than the standard
model prediction and is in excellent agreement with the previous Brookhaven
National Laboratory (BNL) E821 measurement. After combination with previous
measurements of both and , the new experimental average of
(0.35\,ppm) increases the
tension between experiment and theory to 4.2 standard deviationsComment: 10 pages; 4 figure
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