Publications

In this paper we address a seemingly simple question: Is there a universal packet scheduling algorithm? More precisely, we analyze (both theoretically and empirically) whether there is a single packet scheduling algorithm that, at a network-wide level, can match the results of any given scheduling algorithm. We find that in general the answer is "no". However, we show theoretically that the classical Least Slack Time First (LSTF) scheduling algorithm comes closest to being universal and demonstrate empirically that LSTF can closely, though not perfectly, replay a wide range of scheduling algorithms in realistic network settings. We then evaluate whether LSTF can be used in practice to meet various network-wide objectives by looking at three popular performance metrics (mean FCT, tail packet delays, and fairness); we find that LSTF performs comparable to the state-of-the-art for each of them.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The transport properties of a junction consisting of small donor-acceptor molecules bound to Au electrodes are studied and understood in terms of its hybrid donor-acceptor-electrode interfaces. A newly synthesized donor-acceptor molecule consisting of a bithiophene donor and a naphthalenediimide acceptor separated by a conjugated phenylacetylene bridge and a nonconjugated end group shows rectification in the reverse polarization, behavior opposite to that observed in mesoscopic p-n junctions. Solution-based spectroscopic measurements demonstrate that the molecule retains many of its original constituent properties, suggesting a weak hybridization between the wave functions of the donor and acceptor moieties, even in the presence of a conjugated bridge. Differential conductance measurements for biases as high as 1.5 V are reported and indicate a large asymmetry in the orbital contributions to transport arising from disproportionate electronic coupling at anode-donor and acceptor-cathode interfaces. A semi-empirical single Lorentzian coherent transport model, developed from experimental data and density functional theory based calculations, is found to explain the inverse rectification.

Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-95 are presented. The broad-band fluxes (B, V, R, and I), the spectrophotometric optical continuum flux F(5177) and the integrated emission-line fluxes of Ha, Hb, Hg, HeI, and HeII all show a nearly monotonic increase with episodes of milder short-term variations superposed. The amplitude of the continuum variations increases with decreasing wavelength (4400-9000 A). The optical continuum variations follow the variations in the ultraviolet and X-ray with time delays, measured from the centroids of the cross- correlation functions, typically around 5 days, but with uncertainties also typically around 5 days; zero time delay between the high-energy and low-energy continuum variations cannot be ruled out. The strong optical emission lines Ha, Hb, Hg, and HeI respond to the high-energy continuum variations with time delays typically about 20 days, with uncertainties of about 8 days. There is some evidence that HeII responds somewhat more rapidly, with a time delay of around 10 days, but again, the uncertainties are quite large (~8 days). The mean and rms spectra of the Ha and Hb line profiles provide indications for the existence of at least three distinct components located at +-4000 and 0 km/s relative to the line peak. The emission-line profile variations are largest near line center.

Three classes of mutants of Arabidopsis thaliana (L.) Heynhold with alterations in starch metabolism were found to have higher levels of leaf amylase activity than the wild type when grown in a 12-hr photoperiod. This effect was dependent upon the developmental stage of the plants and was largely suppressed during growth in continuous light. The various amylolytic activities in crude extracts were separated by electrophoresis in nondenaturing polyacrylamide gels and visualized by activity staining. The increased amylase activity in the mutants was due to an up to 40-fold increase in the activity of an extrachloroplast β-amylase (EC 3.2.1.2). These observations indicate the existence of a regulatory mechanism that controls the amount of β-amylase activity in response to fluctuations in photosynthetic carbohydrate metabolism. It is paradoxical that β-amylase appears to be a highly regulated enzyme, but as yet no physiologically relevant function can be assigned to this enzyme due to the absence of starch in the cytoplasmic compartment of leaf cells.

Exogenous application of an electric field can direct cell migration and improve wound healing; however clinical application of the therapy remains elusive due to lack of a suitable device and hence, limitations in understanding the molecular mechanisms. Here we report on a novel FDA approved redox-active Ag/Zn bioelectric dressing (BED) which generates electric fields. To develop a mechanistic understanding of how the BED may potentially influence wound re-epithelialization, we direct emphasis on understanding the influence of BED on human keratinocyte cell migration. Mapping of the electrical field generated by BED led to the observation that BED increases keratinocyte migration by three mechanisms: (i) generating hydrogen peroxide, known to be a potent driver of redox signaling, (ii) phosphorylation of redox-sensitive IGF1R directly implicated in cell migration, and (iii) reduction of protein thiols and increase in integrinαv expression, both of which are known to be drivers of cell migration. BED also increased keratinocyte mitochondrial membrane potential consistent with its ability to fuel an energy demanding migration process. Electric fields generated by a Ag/Zn BED can cross-talk with keratinocytes via redox-dependent processes improving keratinocyte migration, a critical event in wound re-epithelialization.

<p>Supplementary Table 1. The Comparisons of Patient Characteristics in All (N = 178), CT (N = 170), DXA (N = 162), and D3Cr (N = 118) Groups</p>

We conducted Hubble Space Telescope (HST) Snapshot observations of the Type IIb supernova (SN) 2011dh in M51 at an age of ~641 days with the Wide Field Camera 3. We find that the yellow supergiant star, clearly detected in pre-SN HST images, has disappeared, implying that this star was almost certainly the progenitor of the SN. Interpretation of the early time SN data which led to the inference of a compact nature for the progenitor, and to the expected survival of this yellow supergiant, is now clearly incorrect. We also present ground-based UBVRI light curves obtained with the Katzman Automatic Imaging Telescope at Lick Observatory up to SN age ~70 days. From the light-curve shape including the very late time HST data, and from recent interacting binary models for SN 2011dh, we estimate that a putative surviving companion star to the now deceased yellow supergiant could be detectable by late 2013, especially in the ultraviolet. No obvious light echoes are detectable yet in the SN environment.