8,164 research outputs found
Submillimeter satellite radiometer first semiannual engineering progress report
Development of 560 GHz fourth harmonic mixer and 140 GHz third harmonic generator for use in radiomete
Local Thermal Equilibrium in Quantum Field Theory on Flat and Curved Spacetimes
The existence of local thermal equilibrium (LTE) states for quantum field
theory in the sense of Buchholz, Ojima and Roos is discussed in a
model-independent setting. It is shown that for spaces of finitely many
independent thermal observables there always exist states which are in LTE in
any compact region of Minkowski spacetime. Furthermore, LTE states in curved
spacetime are discussed and it is observed that the original definition of LTE
on curved backgrounds given by Buchholz and Schlemmer needs to be modified.
Under an assumption related to certain unboundedness properties of the
pointlike thermal observables, existence of states which are in LTE at a given
point in curved spacetime is established. The assumption is discussed for the
sets of thermal observables for the free scalar field considered by Schlemmer
and Verch.Comment: 16 pages, some minor changes and clarifications; section 4 has been
shortened as some unnecessary constructions have been remove
Interplanetary communications study Final report
Mathematical expression for phase and amplitude distribution in focal plane of apertur
Natural History of Isolated Skull Fractures in Children.
Head injury is the most common cause of neurologic disability and mortality in children. We had hypothesized that in children with isolated skull fractures (SFs) and a normal neurological examination on presentation, the risk of neurosurgical intervention is very low. We retrospectively reviewed the medical records of all children aged six to sixteen years presenting to our Level 1 trauma center with traumatic brain injuries between January 1, 2006 and December 31, 2014. We also analyzed the National Trauma Data Bank (NTDB) research data set for the years 2012-2014 using the same metrics. During this study period, our center admitted 575 children with skull fractures, 197 of which were isolated (no associated intracranial lesions (ICLs)). Of the 197 patients with isolated SFs, 155 had a normal neurological examination at presentation. In these patients, there were no fatalities and only three (1.9%) required surgery, all for the elevation of the depressed skull fracture. Analyzing the NTDB yielded similar results. In 5,194 children with isolated SFs and a normal neurological examination on presentation, there were no fatalities and 249 (4.8%) required neurosurgical intervention, almost all involving craniotomy/craniectomy and/or elevation of the SF segments. In conclusion, children with non-depressed isolated skull fractures and a normal Glasgow coma scale (GCS) at the time of initial presentation are at extremely low risk of death or needing neurosurgical intervention
Heat Conduction and Magnetic Phase Behavior in Electron-Doped Ca_{1-x} La_x MnO_3(0 <= x <= 0.2)
Measurements of thermal conductivity (kappa) vs temperature are reported for
a series of Ca_{1-x} La_x MnO_3(0 <= x <= 0.2) specimens. For the undoped
(x=0), G-type antiferromagnetic compound a large enhancement of kappa below the
Neel temperature (T_N ~ 125 K) indicates a strong coupling of heat-carrying
phonons to the spin system. This enhancement exhibits a nonmonotonic behavior
with increasing x and correlates remarkably well with the small ferromagnetic
component of the magnetization reported previously [Neumeier and Cohn, Phys.
Rev. B 61 14319 (2000).] Magnetoelastic polaron formation appears to underly
the behavior of kappa and the magnetization at x <= 0.02.Comment: submitted to PRB; 4 pp., 4 Fig.'s, RevTex
Absence of singular superconducting fluctuation corrections to thermal conductivity
We evaluate the superconducting fluctuation corrections to thermal
conductivity in the normal state which diverge as T approaches T_c. We find
zero total contribution for one, two and three-dimensional superconductors for
arbitrary impurity concentration. The method used is diagrammatic many-body
theory, and all contributions -- Aslamazov-Larkin (AL), Maki-Thompson (MT), and
density-of-states (DOS) -- are considered. The AL contribution is convergent,
whilst the divergences of the DOS and MT diagrams exactly cancel.Comment: 4 pages text; 2 figure
Boolean Models of Bistable Biological Systems
This paper presents an algorithm for approximating certain types of dynamical
systems given by a system of ordinary delay differential equations by a Boolean
network model. Often Boolean models are much simpler to understand than complex
differential equations models. The motivation for this work comes from
mathematical systems biology. While Boolean mechanisms do not provide
information about exact concentration rates or time scales, they are often
sufficient to capture steady states and other key dynamics. Due to their
intuitive nature, such models are very appealing to researchers in the life
sciences. This paper is focused on dynamical systems that exhibit bistability
and are desc ribedby delay equations. It is shown that if a certain motif
including a feedback loop is present in the wiring diagram of the system, the
Boolean model captures the bistability of molecular switches. The method is
appl ied to two examples from biology, the lac operon and the phage lambda
lysis/lysogeny switch
- …