Vibration-induced climbing of drops

We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wetted by the drop. The frequency of vibrations ranges from 30 to 200 Hz, and, above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up or down symmetry breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements. This phenomenon can be used to move a drop along an arbitrary path in a plane, without special surface treatments or localized forcing.Comment: 4 pages, 7 figure

Unmanned Aerial Vehicles: Legitimate Weapon Systems or Unlawful Angels of Death?

Since the invasion of Afghanistan, the United States has utilized Unmanned Aerial Vehicles (UAVs) to locate, surveil and kill members of the Taliban, Al-Qaeda and its associated forces. Such killings have decimated the leadership of these groups and disrupted their operations. However, there are collateral effects from UAV killings including civilian deaths. These deaths increase resentment and hatred toward the US, which is channeled by terrorist groups to recruit new members and for local support. Moreover, targeted killings outside a combat zone have political and diplomatic consequences. This paper argues that the current uses of UAV are legal under international and domestic law. However, it proposes amended targeting criteria, greater transparency and increased checks on the executive branch for future use of UAVs

The Spectrum of B Cell Neoplasia

Recent progress in our understanding of the immune system and the development of new techniques that permit the precise identification of lymphocytes have permitted a reexamination of lymphoid neoplasms. Most of the non-Hodgkin\u27s lymphomas and lymphocytic leukemias have been characterized as T or B cell neoplasms and have been shown to possess features similar to those expressed by normal lymphoid cells at different stages of maturation. The clinical significance and therapeutic implications of these discoveries are now being explored. This paper presents a concise overview of the differentiation of human B lymphocytes, the surface and cytoplasmic markers that permit their recognition, and the diverse tumors that are now known to be malignant counterparts of normal B cell elements. Particular emphasis is placed on the utility of surface and cytoplasmic immunoglobulin as unique B cell markers and on the clonal nature of B cell tumors

Cracks in rubber under tension exceed the shear wave speed

The shear wave speed is an upper limit for the speed of cracks loaded in tension in linear elastic solids. We have discovered that in a non-linear material, cracks in tension (Mode I) exceed this sound speed, and travel in an intersonic range between shear and longitudinal wave speeds. The experiments are conducted in highly stretched sheets of rubber; intersonic cracks can be produced simply by popping a balloon.Comment: 4 pages, 5 eps figure

The Inverse Shapley Value Problem

For $f$ a weighted voting scheme used by $n$ voters to choose between two candidates, the $n$ \emph{Shapley-Shubik Indices} (or {\em Shapley values}) of $f$ provide a measure of how much control each voter can exert over the overall outcome of the vote. Shapley-Shubik indices were introduced by Lloyd Shapley and Martin Shubik in 1954 \cite{SS54} and are widely studied in social choice theory as a measure of the "influence" of voters. The \emph{Inverse Shapley Value Problem} is the problem of designing a weighted voting scheme which (approximately) achieves a desired input vector of values for the Shapley-Shubik indices. Despite much interest in this problem no provably correct and efficient algorithm was known prior to our work. We give the first efficient algorithm with provable performance guarantees for the Inverse Shapley Value Problem. For any constant \eps > 0 our algorithm runs in fixed poly$(n)$ time (the degree of the polynomial is independent of \eps) and has the following performance guarantee: given as input a vector of desired Shapley values, if any "reasonable" weighted voting scheme (roughly, one in which the threshold is not too skewed) approximately matches the desired vector of values to within some small error, then our algorithm explicitly outputs a weighted voting scheme that achieves this vector of Shapley values to within error \eps. If there is a "reasonable" voting scheme in which all voting weights are integers at most \poly(n) that approximately achieves the desired Shapley values, then our algorithm runs in time \poly(n) and outputs a weighted voting scheme that achieves the target vector of Shapley values to within error $\eps=n^{-1/8}.

Cross-Product Extensions of the Gene Ontology

The Gene Ontology is being normalized and extended to include computable logical definitions. These definitions are partitioned into mutually exclusive cross-product sets, many of which reference other OBO Foundry ontologies. The results can be used to reason over the ontology, and to make cross-ontology queries

Zigzag-shaped nickel nanowires via organometallic template-free route

In this manuscript, the formation of nickel nanowires (average size: several tens to hundreds of μm long and 1.0-1.5 μm wide) at low temperature is found to be driven by dewetting of liquid organometallic precursors during spin coating process and by self-assembly of Ni clusters. Elaboration of metallic thin films by low temperature deposition technique makes the preparation process compatible with most of the substrates. The use of iron and cobalt precursor shows that the process could be extended to other metallic systems. In this work, AFM and SEM are used to follow the assembly of Ni clusters into straight or zigzag lines. The formation of zigzag structure is specific to the Ni precursor at appropriate preparation parameters. This template free process allows a control of anisotropic structures with homogeneous sizes and angles on standard Si/SiO2 surface

The strong influence of substrate conductivity on droplet evaporation

We report the results of physical experiments that demonstrate the strong influence of the thermal conductivity of the substrate on the evaporation of a pinned droplet. We show that this behaviour can be captured by a mathematical model including the variation of the saturation concentration with temperature, and hence coupling the problems for the vapour concentration in the atmosphere and the temperature in the liquid and the substrate. Furthermore, we show that including two ad hoc improvements to the model, namely a Newton's law of cooling on the unwetted surface of the substrate and the buoyancy of water vapour in the atmosphere, give excellent quantitative agreement for all of the combinations of liquid and substrate considered

T-Lymphocyte Subset Studies to Monitor Patients with AIDS and AIDS-Related Complex

Multiple specimens from 124 patients from our clinic were evaluated for T4/T8 cell ratio over three to 28 months. Twenty-nine of 30 patients with the acquired immunodeficiency syndrome (AIDS), 58 of 71 patients with AIDS-related complex (ARC), and four of 23 patients at risk showed initial T4/T8 cell ratios of less than 0.8. which either remained unchanged or decreased. Seventeen of 23 AIDS patients and two of 20 ARC patients with a consistently low ratio (0.3 or less) died during the follow-up period. This indicated that the severity of disease could be predicted by periodical T4/T8 cell ratio studies. These serial studies appeared to be valuable in monitoring the course of patients with AIDS, ARC, and the human immunodeficiency virus infection and also in evaluating the effects of available drug treatment