Practical Power and Rate Control for WiFi

While there has been extensive theoretical work on sophisticated joint resource allocation algorithms for wireless networks, their applicability to WiFi (IEEE 802.11) networks is very limited. One of the main reasons is the limitations in changing MAC parameters in current driver implementations. To this end, in this work, we developed a general cross-layer communication interface in the Linux kernel between the IEEE 802.11 PHY and MAC to enable per packet TPC. Based on this implementation, we realize an decentralized rate-power controller (Minstrel-Piano). Our initial evaluation shows that Minstrel-Piano is able to significantly decrease the power levels while maintaining the same link performance. These results are encouraging for a better interference management and consequently, better resource allocation in WiFi networks

Antimicrobial resistance of Salmonella enterica in pork and vegetable servings at pork joints in Kampala, Uganda

The aim of this study was to investigate the prevalence and antimicrobial resistance of Salmonella enterica subsp. enterica serovars including the presence of shared plasmids in pork and related fresh vegetables served in pork joints in Kampala, Uganda. Pork butcheries in three of the five administrative divisions of Kampala were included for the survey. Samples included raw pork, roasted pork, water, onions, tomatoes, cabbage, butcher’s hands (swabs), utensils (swabs) and fly midgut extracts. A total of 693 samples were collected from 77 pork butcheries from June- October 2014. Overall 53.2% pork joints had samples positive for Salmonella enterica subsp. enterica serovars. Isolation rates ranged from 31.2% (24/77) for raw pork, 1.3% (1/77) for roasted pork, 7.8% (6/77) for tomatoes, 2.6% (2/77) for onions, 5.2% (4/77) for cabbage, 9.1% (7/77) in water, and 22.1% (17/77) from fly midguts. Swab samples taken from utensil and butcher’s hands swabs were found negative (Heilmann et al., 2015). In the isolates obtained, resistance towards 22 antibiotics was tested. Resistances were found towards 11 out of the 22 antibiotics tested. High resistances were found to Cephazolin (97%), Cefotixime (93%), Gentamicin (88%), and Ceftazidime (86%). Intermediate resistance was found to Ciprofloxacin (59%) and Amoxicillin-Clavulanic acid (57.6%). Most isolates (85%) were susceptible to Levofloxacin, Ofloxacin, Sulfamethoxazole and Trimethoprim. Identification of plasmids by PCR-based replicon typing was performed recognizing FIA,FIB,FIC,HI1,HI2,I1- 1ᵞ,L/M,N,P,W,T,A/C,K,B/O,X,Y,F and FIIA. Six incompatibility groups were identified: FIA, W, FIC, FIB, P, Y with more than one incompatibility group existing among different isolates. A high resistance rate among Salmonella strains was found while the total number of incompatibility groups detected was with approximation 2.4. Thus, even though the total number of plasmids per strain is low, resistance rates detected remain high. The high resistance rates are probably resulting from intensified food animal production driving a greater use of antibiotics, which is a crucial aspect of public health concern

Design and Performance of SiPM-Based Readout of PbF\u3csub\u3e2\u3c/sub\u3e Crystals for High-Rate, Precision Timing Applications

We have developed a custom amplifier board coupled to a large-format 16-channel Hamamatsu silicon photomultiplier device for use as the light sensor for the electromagnetic calorimeters in the Muon g - 2 experiment at Fermilab. The calorimeter absorber is an array of lead-fluoride crystals, which produces short-duration Cherenkov light. The detector sits in the high magnetic field of the muon storage ring. The SiPMs selected, and their accompanying custom electronics, must preserve the short pulse shape, have high quantum efficiency, be non-magnetic, exhibit gain stability under varying rate conditions, and cover a fairly large fraction of the crystal exit surface area. We describe an optimized design that employs the new-generation of thru-silicon via devices. The performance is documented in a series of bench and beam tests

mir-181A/B-1 controls thymic selection of treg cells and tunes their suppressive capacity

The interdependence of selective cues during development of regulatory T cells (Treg cells) in the thymus and their suppressive function remains incompletely understood. Here, we analyzed this interdependence by taking advantage of highly dynamic changes in expression of microRNA 181 family members miR-181a-1 and miR-181b-1 (miR-181a/b-1) during late T-cell development with very high levels of expression during thymocyte selection, followed by massive down-regulation in the periphery. Loss of miR-181a/b-1 resulted in inefficient de novo generation of Treg cells in the thymus but simultaneously permitted homeostatic expansion in the periphery in the absence of competition. Modulation of T-cell receptor (TCR) signal strength in vivo indicated that miR-181a/b-1 controlled Treg-cell formation via establishing adequate signaling thresholds. Unexpectedly, miR-181a/b-1–deficient Treg cells displayed elevated suppressive capacity in vivo, in line with elevated levels of cytotoxic T-lymphocyte–associated 4 (CTLA-4) protein, but not mRNA, in thymic and peripheral Treg cells. Therefore, we propose that intrathymic miR-181a/b-1 controls development of Treg cells and imposes a developmental legacy on their peripheral function

Search for First Generation Scalar Leptoquark Pairs in ppbar Collisions at sqrt(s)=1.8 TeV

We have searched for first generation scalar leptoquark (LQ) pairs in the enu+jets channel using ppbar collider data (integrated luminosity= 115 pb^-1) collected by the DZero experiment at the Fermilab Tevatron during 1992-96. The analysis yields no candidate events. We combine the results with those from the ee+jets and nunu+jets channels to obtain 95% confidence level (CL) upper limits on the LQ pair production cross section as a function of mass and of beta, the branching fraction to a charged lepton. Comparing with the next-to-leading order theory, we set 95% CL lower limits on the LQ mass of 225, 204, and 79 GeV/c^2 for beta=1, 1/2, and 0, respectively.Comment: 14 pages, 4 figures, submitted to Physical Review Letters Replaced to correct visitor addresse

Direct Measurement of the Top Quark Mass at D0

We determine the top quark mass m_t using t-tbar pairs produced in the D0 detector by \sqrt{s} = 1.8 TeV p-pbar collisions in a 125 pb^-1 exposure at the Fermilab Tevatron. We make a two constraint fit to m_t in t-tbar -> b W^+bbar W^- final states with one W boson decaying to q-qbar and the other to e-nu or mu-nu. Likelihood fits to the data yield m_t(l+jets) = 173.3 +- 5.6 (stat) +- 5.5 (syst) GeV/c^2. When this result is combined with an analysis of events in which both W bosons decay into leptons, we obtain m_t = 172.1 +- 5.2 (stat) +- 4.9 (syst) GeV/c^2. An alternate analysis, using three constraint fits to fixed top quark masses, gives m_t(l+jets) = 176.0 +- 7.9 (stat) +- 4.8 (syst) GeV/C^2, consistent with the above result. Studies of kinematic distributions of the top quark candidates are also presented.Comment: 43 pages, 53 figures, 33 tables. RevTeX. Submitted to Phys. Rev.

Measurement of the Top Quark Mass Using Dilepton Events

The D0 collaboration has performed a measurement of the top quark mass based on six candidate events for the process t tbar -> b W+ bbar W-, where the W bosons decay to e nu or mu nu. This sample was collected during an exposure of the D0 detector to an integrated luminosity of 125 pb^-1 of sqrt(s)=1.8 TeV p-pbar collisions. We obtain mt = 168.4 +- 12.3 (stat) +- 3.7 (sys) GeV/c^2, consistent with the measurement obtained using single-lepton events. Combination of the single-lepton and dilepton results yields mt = 172.0 +- 7.5 GeV/c^2.Comment: 12 pages, 3 figure