An evaluation of location management procedures

This paper gives a comparative description of two scenarios for location management in a mobile telecommunications system. The first scenario uses fixed location and paging areas. Mobiles perform a location update as they enter a new location area. The second scenario uses a time-out based location updating scheme. Mobiles start their timer as they leave the paging area they are currently registered in. As the timer elapses, the mobile performs a location update. Both scenarios also differ in the way paging is performed. In the first scenario it is only necessary to page in the location area the mobile is currently registered in. In order to do this efficiently, the paging is done in a 2-step fashion: mobiles are paged first in the paging area in which they were registered in, and next in the entire location area they are registered in. In the second scenario the mobile is paged in multiple steps: first in the paging area it is registered in, next in a circle of paging areas surrounding that area, and so on, until the mobile is found, or the number of steps has reached a certain upper limit. Results comprise a quantitative and qualitative comparison of these scenarios, and guidelines for optimal applicatio

Identifying characteristics of frailty in female mice using a phenotype assessment tool

Preclinical studies are important in identifying the underlying mechanisms contributing to frailty. Frailty studies have mainly focused on male rodents with little directed at female rodents. Therefore, the purposes of this study were to identify the onset and prevalence of frailty across the life span in female mice, and to determine if frailty predicts mortality. Female C57BL/6 (n = 27) mice starting at 17 months of age were assessed across the life span using a frailty phenotype, which included body weight, walking speed, strength, endurance, and physical activity. The onset of frailty occurred at approximately 17 months (1/27 mice), with the prevalence of frailty increasing thereafter. At 17 months, 11.1% of the mice were pre-frail and by 26 months peaked at 36.9%. The percentage of frail mice progressively increased up to 66.7% at 32 months. Non-frail mice lived to 29 months whereas frail/pre-frail mice lived only to 26 months (p = .04). In closing, using a mouse frailty phenotype, we are able to identify that the prevalence of frailty in female mice increases across the life span and accurately predicts mortality. Together, this frailty phenotype has the potential to yield information about the underlying mechanisms contributing to frailty.T32 AG029796 - NIA NIH HHSPublished versio

Sex-specific components of frailty in C57BL/6 mice.

Many age-related biochemical, physiological and behavioral changes are known to be sex-specific. However, how sex influences frailty status and mortality risk in frail rodents has yet to be established. The purpose of this study was therefore to characterize sex differences in frail mice across the lifespan. Male (n=29) and female (n=27) mice starting at 17 months of age were assessed using a frailty phenotype adjusted according to sex, which included body weight, walking speed, strength, endurance and physical activity. Regardless of sex, frail mice were phenotypically dysfunctional compared to age-matched non-frail mice, while non-frail females generally possessed a higher body fat percentage and were more physically active than non-frail males (p≤0.05). The prevalence of frailty was greater in female mice at 26 months of age (p=0.05), but if normalized to mean lifespan, no sex differences remained. No differences were detected in the rate of death or mean lifespan between frail male and female mice (p≥0.12). In closing, these data indicate that sexual differences exist in aging C57BL/6 mice and if the frailty criteria are adjusted according to sex, the prevalence of frailty increases across age with frail mice dying early in life, regardless of sex.T32 AG029796 - NIA NIH HHS; T32 AR007612 - NIAMS NIH HHSPublished versio

Phenomenology of D-Brane Inflation with General Speed of Sound

A characteristic of D-brane inflation is that fluctuations in the inflaton field can propagate at a speed significantly less than the speed of light. This yields observable effects that are distinct from those of single-field slow roll inflation, such as a modification of the inflationary consistency relation and a potentially large level of non-Gaussianities. We present a numerical algorithm that extends the inflationary flow formalism to models with general speed of sound. For an ensemble of D-brane inflation models parameterized by the Hubble parameter and the speed of sound as polynomial functions of the inflaton field, we give qualitative predictions for the key inflationary observables. We discuss various consistency relations for D-brane inflation, and compare the qualitative shapes of the warp factors we derive from the numerical models with analytical warp factors considered in the literature. Finally, we derive and apply a generalized microphysical bound on the inflaton field variation during brane inflation. While a large number of models are consistent with current cosmological constraints, almost all of these models violate the compactification constraint on the field range in four-dimensional Planck units. If the field range bound is to hold, then models with a detectable level of non-Gaussianity predict a blue scalar spectral index, and a tensor component that is far below the detection limit of any future experiment.Comment: 23 pages, 11 figures, v2: version accepted by PRD; minor clarifications and references added to the text. Higher resolution figures are available in the published version. v3: post-publication correction of typo in Eq. 87. No results/conclusions change

Downhill exercise alters immunoproteasome content in mouse skeletal muscle

Content of the immunoproteasome, the inducible form of the standard proteasome, increases in atrophic muscle suggesting it may be associated with skeletal muscle remodeling. However, it remains unknown if the immunoproteasome responds to stressful situations that do not promote large perturbations in skeletal muscle proteolysis. The purpose of this study was to determine how an acute bout of muscular stress influences immunoproteasome content. To accomplish this, wildtype (WT) and immunoproteasome knockout lmp7-/-/mecl1-/-(L7M1) mice were run downhill on a motorized treadmill. Soleus muscles were excised 1 and 3 days post-exercise and compared to unexercised muscle(control). Ex vivophysiology, histology and biochemical analyses were used to assess the effects of immunoproteasome knockout and unaccustomed exercise. Besides L7M1 muscle being LMP7/MECL1deficient, no other major biochemical, histological or functional differences were observed between the control muscles. In both strains, the downhill run shifted the force-frequency curve to the right and reduced twitch force, however did not alter tetanic force or inflammatory markers. In the days post-exercise, several of the proteasome 's catalytic subunits were upregulated. Specifically, WT muscle increased LMP7 while L7M1 muscle instead increased ≤ 5. These findings indicate that running mice downhill results in subtle contractile characteristics that correspond to skeletal muscle injury, yet does not appear to induce a significant inflammatory response. Interestingly, this minor stress activated the production of specific immunoproteasome subunits; that if knocked out, were replaced by components of the standard proteasome. These data suggest that the immunoproteasome may be involved in maintaining cellular homeostasis.This study was supported by the Elaine and Robert Larson Endowed Vision Research Chair (to DAF), the National Institutes of Health/National Institute of Aging (T32-AG29796 to CWB), an anonymous benefactor for Macular Degeneration Research, the Lindsay Family Foundation and an unrestricted grant from Research to Prevent Blindness to the Department of Ophthalmology and Visual Neurosciences. The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript. (Elaine and Robert Larson Endowed Vision Research Chair; T32-AG29796 - National Institutes of Health/National Institute of Aging; Lindsay Family Foundation; Research to Prevent Blindness)Accepted manuscrip

Denervation-induced activation of the standard proteasome and immunoproteasome

The standard 26S proteasome is responsible for the majority of myofibrillar protein degradation leading to muscle atrophy. The immunoproteasome is an inducible form of the proteasome. While its function has been linked to conditions of atrophy, its contribution to muscle proteolysis remains unclear. Therefore, the purpose of this study was to determine if the immunoproteasome plays a role in skeletal muscle atrophy induced by denervation. Adult male C57BL/6 wild type (WT) and immunoproteasome knockout lmp7-/-/mecl-1-/- (L7M1) mice underwent tibial nerve transection on the left hindlimb for either 7 or 14 days, while control mice did not undergo surgery. Proteasome activity (caspase-, chymotrypsin-, and trypsin- like), protein content of standard proteasome (β1, β5 and β2) and immunoproteasome (LMP2, LMP7 and MECL-1) catalytic subunits were determined in the gastrocnemius muscle. Denervation induced significant atrophy and was accompanied by increased activities and protein content of the catalytic subunits in both WT and L7M1 mice. Although denervation resulted in a similar degree of muscle atrophy between strains, the mice lacking two immunoproteasome subunits showed a differential response in the extent and duration of proteasome features, including activities and content of the β1, β5 and LMP2 catalytic subunits. The results indicate that immunoproteasome deficiency alters the proteasome's composition and activities. However, the immunoproteasome does not appear to be essential for muscle atrophy induced by denervation.T32 AG029796 - NIA NIH HH

Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations

We derive the complete spectrum of gravitational waves induced by primordial scalar perturbations ranging over all observable wavelengths. This scalar-induced contribution can be computed directly from the observed scalar perturbations and general relativity and is, in this sense, independent of the cosmological model for generating the perturbations. The spectrum is scale-invariant on small scales, but has an interesting scale-dependence on large and intermediate scales, where scalar-induced gravitational waves do not redshift and are hence enhanced relative to the background density of the Universe. This contribution to the tensor spectrum is significantly different in form from the direct model-dependent primordial tensor spectrum and, although small in magnitude, it dominates the primordial signal for some cosmological models. We confirm our analytical results by direct numerical integration of the equations of motion.Comment: 19 pages, 5 figure

Determinants of agricultural land abandonment in post-soviet European Russia

Socio-economic and institutional changes may accelerate land-use and land-cover change. Our goal was to explore the determinants of agricultural land abandonment within one agro-climatic and economic region of post-Soviet European Russia during the first decade of transition from a state-command to market-driven economy (between 1990 and 2000). We integrated maps of abandoned agricultural land derived from 30 m resolution Landsat TM/ETM+ images, environmental and socioeconomic variables and estimated logistic regressions. Results showed that post-Soviet agricultural land abandonment was significantly associated with lower average grain yields in the late 1980s, higher distance from the populated places, areas with low population densities, for isolated agricultural areas within the forest matrix and near the forest edges. Hierarchical partitioning showed that average grain yields in the late 1980s contributed the most in explaining the variability of agricultural land abandonment, followed by location characteristics of the land. While the spatial patterns correspond to the classic micro-economic theories of von Thünen and Ricardo, it was largely the macro-scale driving forces that fostered agricultural abandonment. In the light of continuum depopulation process in the studied region of European Russia, we expect continuing agricultural abandonment after the year 2000. --agricultural land abandonment,institutional change, land use change,spatial analysis,logistic regression,remote sensing,Russia

Cosmological Inflation: Theory and Observations

In this article we review the theory of cosmological inflation with a particular focus on the beautiful connection it provides between the physics of the very small and observations of the very large. We explain how quantum mechanical fluctuations during the inflationary era become macroscopic density fluctuations which leave distinct imprints in the cosmic microwave background (CMB). We describe the physics of anisotropies in the CMB temperature and polarization and discuss how CMB observations can be used to probe the primordial universe.Comment: 18 pages, 12 figures. Invited review to appear in Advanced Science Letters Special Issue on Quantum Gravity, Cosmology and Black Holes. v2: published version, minor clarifications and references adde