22,326 research outputs found
Interacting Individuals Leading to Zipf's Law
We present a general approach to explain the Zipf's law of city distribution.
If the simplest interaction (pairwise) is assumed, individuals tend to form
cities in agreement with the well-known statisticsComment: 4 pages 2 figure
Thermodynamics of modified black holes from gravity's rainbow
We study the thermodynamics of modified black holes proposed in the context
of gravity's rainbow. A notion of intrinsic temperature and entropy for these
black holes is introduced. In particular for a specific class of modified
Schwarzschild solutions, their temperature and entropy are obtained and
compared with those previously obtained from modified dispersion relations in
deformed special relativity. It turns out that the results of these two
different strategies coincide, and this may be viewed as a support for the
proposal of deformed equivalence principle.Comment: 3 pages, Revte
The kinematics of particles moving in rainbow spacetime
The kinematics of particles moving in rainbow spacetime is studied in this
paper. In particular the geodesics of a massive particle in rainbow flat
spacetime is obtained when the semi-classical effect of its own energy on the
background is taken into account. We show that in general the trajectory of a
freely falling particle remains unchanged which is still a straight line as in
the flat spacetime. The implication to the Unruh effect in rainbow flat
spacetime is also discussed.Comment: 5 page
Opportunistic Relaying in Time Division Broadcast Protocol with Incremental Relaying
In this paper, we investigate the performance of time division broadcast protocol (TDBC) with incremental relaying (IR) when there are multiple available relays. Opportunistic relaying (OR), i.e., the “best” relay is select for transmission to minimize the system’s outage probability, is proposed. Two OR schemes are presented. The first scheme, termed TDBC-OIR-I, selects the “best” relay from the set of relays that can decode both flows of signal from the two sources successfully. The second one, termed TDBC-OIR-II, selects two “best” relays from two respective sets of relays that can decode successfully each flow of signal. The performance, in terms of outage probability, expected rate (ER), and diversity-multiplexing tradeoff (DMT), of the two schemes are analyzed and compared with two TDBC schemes that have no IR but OR (termed TDBC-OR-I and TDBC-OR-II accordingly) and two other benchmark OR schemes that have no direct link transmission between the two sources
Statistics of lower tropospheric inversions over the continental United States
The basic structure parameters of lower tropospheric
inversions (LTIs) have been derived from 10 years (1998–2007) of high vertical
resolution (~50 m) radiosonde observations over 56 United States
stations. Seasonal and longitudinal variability of these parameters are
presented and the formation mechanisms of LTI are also discussed. It is
found that LTI seems to be a common feature over the continental United
States. The LTI occurrence rates (defined as the fraction of measurements
with LTI, which is calculated from the number of LTI cases divided by the
number of measurements of the whole 10 years) at these 56 stations vary from
3.7% to 14.5%; the averaged base heights of LTI have a range of 3–5 km
above mean sea level (a.m.s.l.); the averaged thicknesses and temperature jump
ranges from 420–465 m and 1.9–2.2 K, respectively. These parameters have an
obvious seasonal variation. In winter, all the occurrence rates, thicknesses
and temperature jumps of LTI have much larger values than those in summer.
LTI occurrence rate shows an obvious west-east increasing trend in all 4
seasons. Detailed analyses reveal that dynamical instability induced by
strong zonal wind shear is responsible for LTI in winter, spring and autumn;
the frontal system tends to generate LTI in summer. Since the higher
occurrence rate, larger temperature jump and larger thickness of LTI occur
in winter, we believe strong zonal wind shear plays a more important role in
the formation of LTI
Intelectin contributes to allergen-induced IL-25, IL-33, and TSLP expression and type 2 response in asthma and atopic dermatitis.
The epithelial and epidermal innate cytokines IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) have pivotal roles in the initiation of allergic inflammation in asthma and atopic dermatitis (AD). However, the mechanism by which the expression of these innate cytokines is regulated remains unclear. Intelectin (ITLN) is expressed in airway epithelial cells and promotes allergic airway inflammation. We hypothesized that ITLN is required for allergen-induced IL-25, IL-33, and TSLP expression. In two asthma models, Itln knockdown reduced allergen-induced increases in Il-25, Il-33, and Tslp and development of type 2 response, eosinophilic inflammation, mucus overproduction, and airway hyperresponsiveness. Itln knockdown also inhibited house dust mite (HDM)-induced early upregulation of Il-25, Il-33, and Tslp in a model solely inducing airway sensitization. Using human airway epithelial cells, we demonstrated that HDM-induced increases in ITLN led to phosphorylation of epidermal growth factor receptor and extracellular-signal regulated kinase, which were required for induction of IL-25, IL-33, and TSLP expression. In two AD models, Itln knockdown suppressed expression of Il-33, Tslp, and Th2 cytokines and eosinophilic inflammation. In humans, ITLN1 expression was significantly increased in asthmatic airways and in lesional skin of AD. We conclude that ITLN contributes to allergen-induced Il-25, Il-33, and Tslp expression in asthma and AD
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