12,372 research outputs found
Cross-Sender Bit-Mixing Coding
Scheduling to avoid packet collisions is a long-standing challenge in
networking, and has become even trickier in wireless networks with multiple
senders and multiple receivers. In fact, researchers have proved that even {\em
perfect} scheduling can only achieve . Here
is the number of nodes in the network, and is the {\em medium
utilization rate}. Ideally, one would hope to achieve ,
while avoiding all the complexities in scheduling. To this end, this paper
proposes {\em cross-sender bit-mixing coding} ({\em BMC}), which does not rely
on scheduling. Instead, users transmit simultaneously on suitably-chosen slots,
and the amount of overlap in different user's slots is controlled via coding.
We prove that in all possible network topologies, using BMC enables us to
achieve . We also prove that the space and time
complexities of BMC encoding/decoding are all low-order polynomials.Comment: Published in the International Conference on Information Processing
in Sensor Networks (IPSN), 201
A Contextual Perspective on E-Commerce Across Industries in Singapore and Lagos: Implications of Local Imperatives
System Development Practices: A Comparison of the Experience of Australian and United States\u27 Organizations
Physical Activity Minimum Threshold Predicting Improved Function in Adults With Lower‐Extremity Symptoms
Objective
To identify an evidence‐based minimum physical activity threshold to predict improved or sustained high function for adults with lower‐extremity joint symptoms. Methods
Prospective multisite data from 1,629 adults, age ≥49 years with symptomatic lower‐extremity joint pain/aching/stiffness, participating in the Osteoarthritis Initiative accelerometer monitoring substudy were clinically assessed 2 years apart. Improved/high function in 2‐year gait speed and patient‐reported outcomes (PROs) were based on improving or remaining in the best (i.e., maintaining high) function quintile compared to baseline status. Optimal thresholds predicting improved/high function were investigated using classification trees for the legacy federal guideline metric requiring 150 minutes/week of moderate‐vigorous (MV) activity in bouts lasting 10 minutes or more (MV‐bout) and other metrics (total MV, sedentary, light intensity activity, nonsedentary minutes/week). Results
Optimal thresholds based on total MV minutes/week predicted improved/high function outcomes more strongly than the legacy or other investigated metrics. Meeting the 45 total MV minutes/week threshold had increased relative risk (RR) for improved/high function (gait speed RR 1.8, 95% confidence interval [95% CI] 1.6, 2.1 and PRO physical function RR 1.4, 95% CI 1.3, 1.6) compared to less active adults. Thresholds were consistent across sex, body mass index, knee osteoarthritis status, and age. Conclusion
These results supported a physical activity minimum threshold of 45 total MV minutes/week to promote improved or sustained high function for adults with lower‐extremity joint symptoms. This evidence‐based threshold is less rigorous than federal guidelines (≥150 MV‐bout minutes/week) and provides an intermediate goal towards the federal guideline for adults with lower‐extremity symptoms
Densest Subgraph in Dynamic Graph Streams
In this paper, we consider the problem of approximating the densest subgraph
in the dynamic graph stream model. In this model of computation, the input
graph is defined by an arbitrary sequence of edge insertions and deletions and
the goal is to analyze properties of the resulting graph given memory that is
sub-linear in the size of the stream. We present a single-pass algorithm that
returns a approximation of the maximum density with high
probability; the algorithm uses O(\epsilon^{-2} n \polylog n) space,
processes each stream update in \polylog (n) time, and uses \poly(n)
post-processing time where is the number of nodes. The space used by our
algorithm matches the lower bound of Bahmani et al.~(PVLDB 2012) up to a
poly-logarithmic factor for constant . The best existing results for
this problem were established recently by Bhattacharya et al.~(STOC 2015). They
presented a approximation algorithm using similar space and
another algorithm that both processed each update and maintained a
approximation of the current maximum density in \polylog (n)
time per-update.Comment: To appear in MFCS 201
Using a model of group psychotherapy to support social research on sensitive topics
This article describes the exploratory use of professional therapeutic support by social researchers working on a sensitive topic. Talking to recently bereaved parents about the financial implications of their child's death was expected to be demanding work, and the research design included access to an independent psychotherapeutic service. Using this kind of professional support is rare within the general social research community, and it is useful to reflect on the process. There are likely to be implications for collection and interpretation of data, research output and the role and experience of the therapist. Here, the primary focus is the potential impact on researcher well-being
Effect of Electrically Mediated Intratumor and Intramuscular Delivery of a Plasmid Encoding IFN α on Visible B16 Mouse Melanomas
Interferon α may be used as a single agent therapy for metastatic malignant melanoma or as an adjuvant to chemotherapy. Delivery of interferon α by gene therapy offers an alternative to recombinant protein therapy. Electrically mediated delivery enhances plasmid expression in a number of tissues, for instance skin, liver, muscle and tumors including melanomas. Here we compare the effect of delivery of a plasmid encoding mouse interferon α on growth of visible B16 mouse melanomas following electrically mediated delivery to muscle or directly to the tumor. Intratumoral delivery of interferon α plasmid not only slows melanoma growth, but induces complete, long term, regression. This effect was not observed after intramuscular delivery
Risk of maltreatment-related injury: a cross-sectional study of children under five years old admitted to hospital with a head or neck injury or fracture.
To determine the predictive value and sensitivity of demographic features and injuries (indicators) for maltreatment-related codes in hospital discharge records of children admitted with a head or neck injury or fracture
Ionic Tuning of Cobaltites at the Nanoscale
Control of materials through custom design of ionic distributions represents
a powerful new approach to develop future technologies ranging from spintronic
logic and memory devices to energy storage. Perovskites have shown particular
promise for ionic devices due to their high ion mobility and sensitivity to
chemical stoichiometry. In this work, we demonstrate a solid-state approach to
control of ionic distributions in (La,Sr)CoO thin films. Depositing a Gd
capping layer on the perovskite film, oxygen is controllably extracted from the
structure, up-to 0.5 O/u.c. throughout the entire 36 nm thickness. Commensurate
with the oxygen extraction, the Co valence state and saturation magnetization
show a smooth continuous variation. In contrast, magnetoresistance measurements
show no-change in the magnetic anisotropy and a rapid increase in the
resistivity over the same range of oxygen stoichiometry. These results suggest
significant phase separation, with metallic ferromagnetic regions and
oxygen-deficient, insulating, non-ferromagnetic regions, forming percolated
networks. Indeed, X-ray diffraction identifies oxygen-vacancy ordering,
including transformation to a brownmillerite crystal structure. The unexpected
transformation to the brownmillerite phase at ambient temperature is further
confirmed by high-resolution scanning transmission electron microscopy which
shows significant structural - and correspondingly chemical - phase separation.
This work demonstrates room-temperature ionic control of magnetism, electrical
resistivity, and crystalline structure in a 36 nm thick film, presenting new
opportunities for ionic devices that leverage multiple material
functionalities
Pairing correlations and transitions in nuclear systems
We discuss several pairing-related phenomena in nuclear systems, ranging from
superfluidity in neutron stars to the gradual breaking of pairs in finite
nuclei. We describe recent experimental evidence that points to a relation
between pairing and phase transitions (or transformations) in finite nuclear
systems. A simple pairing interaction model is used in order to study and
classify an eventual pairing phase transition in finite fermionic systems such
as nuclei. We show that systems with as few as 10-16 fermions can exhibit clear
features reminiscent of a phase transition.Comment: Proceedings of COMEX1, Sorbonne, Paris, june 10-13 2003. To appear in
Nuclear Physics
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