Measurements of Kinetic Energy Loss for Particles Impacting Surfaces

Incoming and rebounding particle velocities were measured to within several particle diameters of the impaction surface using laser Doppler velocimetry. Impacts occurred normal to the surface and ranged from 1 m/s, near the threshold for particle bounce, to 100 m/s, well into the plastic damage regime. Monodisperse ammonium fluorescein spheres, 2.6–6.9 μm in diameter, impacted target surfaces including polished molybdenum and silicon, cleaved mica, and a fluorocarbon polymer. The incident kinetic energy recovered on rebound depended on particle size and target composition at low velocity (< 20 m/s), where the adhesion surface energy is important. No dependence on target composition was found at higher velocities where up to half of the impact energy was lost to plastic deformation. Plastic deformation was a significant component of energy loss even at impact velocities near critical velocity. Critical velocities for the onset of bounce decreased with a stronger power-law dependence on particle diameter than expected from classical adhesion theory or the elastic flattening model proposed by Dahneke. This is consistent with kinetic energy loss contributions from both plastic deformation and surface forces. Auxiliary experiments conducted with and without continuous discharge of the impact surface indicated the absence of a significant electrostatic contribution to particle adhesion.     

Review essay: Narcissism and the interpersonal self.

Interpersonal approaches to the concept of a core self are explored in a review of Narcissism and the interpersonal self (John Fiscalini and Alan Grey, Editors) (see record 1993-97836-000). The role of self as system and self as identity--both the interpersonal, adaptive self and the personal, core self--is used to understand the evolution of the Interpersonal School and its varied approaches to narcissism. A formulation integrating subjectively and objectively based models is proposed whereby the "core" self may be understood as the totality and integrity between internal, personal self and reflected, interpersonal self. Narcissism involves an alienation of the reflected self from the inner self, which leads to a particular set of dynamics to regulate self-esteem. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On Early Myths and Formative Technologies: A Study of Pre-Pottery Neolithic B Sculptures and Modeled Skulls From Jericho

During the last two decades, considerable interest has been expressed in the development of lime and lime plaster products in the Near Eastern Pre-Pottery Neolithic B. The occurrences of lime products in numerous Levantine sites have raised questions concerning their methods of production, their role in the development of craft specialization, and their social and economic implications. Lime plaster was the first product that entailed the intentional chemical alteration of materials and the complete control over their properties. This was probably the reason for the wide spectrum of uses to which it was put, amongst which “daily” architectural functions appear to coexist with the symbolic or spiritual applications of this material. Amongst the variety of plaster products which appeared in the PPNB, it seems that the practice of skull plastering and sculpture production was the most “socially oriented” one, lacking any apparent relation to daily, functional use. In the present study two modeled skulls and a collection of plaster sculptures from Jericho were examined by means of thin section petrographic analysis, inductively coupled plasma atomic emission spectrometry, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectrometry. The results of the mineralogical and chemical analyses, when compared to data obtained from similar artifacts from other sites, demonstrate pronounced intersite variability in the methods of production of the skull and sculpture modeling. The full implications of this issue are discussed in detail in the paper.     

Patterns of magnetic flux penetration in superconducting films

Intermediate-state magnetic flux patterns have been observed in thin superconducting films of tin, lead, and indium in perpendicular applied fields of 0.1–100 Oe. The spatial variation in flux density was measured very close to the film with a high-resolution Hall probe which could be scanned in a plane parallel to the surface of the film. The patterns appear to contain both laminar and round normal regions, with the latter predominant. A model for the intermediate state has been developed in which the normal regions are macroscopic flux spots. Experimental results for the number density of these flux spots in 1.1–6.3--thick indium samples are in good agreement with the temperature, field, and thickness dependences of our model; indium samples thinner than 1 µ appear to enter the mixed state. In tin and lead, however, the flux patterns are strongly influenced by flux pinning. Appearance of the flux pattern at the critical field or temperature has been observed and correlated with distinctive features in the resistive transition. The extent of flux penetration into the sample was determined from measurement of the average field and compared for various field-temperature paths to the intermediate state. With the applied field reduced to zero, the magnetic field outside a current-carrying superconducting strip has been measured and indicates that the current distribution within the strip is consistent with the form predicted by Bowers.Supported in part by the NSF, ONR, and ARPA.     

Dental radiographic exposure normalization program (DENT). The experience in Nassau County, NY

A Federally sponsored program for reducing unnecessary exposures from dental radiographic procedures is monitored over four years. The results are encouraging.     

Determination of Kerosine Contamination in Local Gasoline by Gas Chromatography

A GLC method for the detection and determination of small admixtures of kerosine (0% and above) in local gasoline is described. The method is independent of gasoline and kerosine batch variations and of gasoline grades. Making use of the relationship which was found between the heights of three successive n-paraffin peaks (C₁₂, C₁₃ and C₁₄) the kerosine contamination can be determined with an absolute error of ± 0.2%.     

Impact Assessment of Different Management Scenarios on Water Quality of Porsuk River and Dam System – Turkey

Porsuk Dam Reservoir (PDR), which is located on Porsuk River, is the main drinking water resource of Eskisehir City-Turkey. Both the river and the reservoir are under the threat of several domestic and industrial point sources and land-based diffuse pollution. The river water quality is very poor with high concentrations of nitrogen and phosphorus compounds at the entrance to Porsuk Reservoir. The reservoir shows symptoms of a hypertrophic lake. The expected responses of the whole river and reservoir system under different pollution control scenarios were estimated to develop plausible water quality management strategies. The adopted scenarios assumed different levels of treatment for the major domestic point sources that include conventional treatment and tertiary treatment. The contemporary Turkish Allowable Discharge Limits (ADLs) and the best available technology choices were the investigated treatment options for the major industries. The expected improvements of water quality characteristics under the management scenario options have been estimated by means of mathematical models. The model choices were the QUAL2E for the river and BATHTUB for the reservoir. Recommendations for different levels of treatment were derived in order to improve the water quality both within the river and in the reservoir.     

A 23-dBm 60-GHz Distributed Active Transformer in a Silicon Process Technology

In this paper, a distributed active transformer for the operation in the millimeter-wave frequency range is presented. The transformer utilizes stacked coupled wires as opposed to slab inductors to achieve a high coupling factor of k_f=0.8 at 60 GHz. Scalable and compact equivalent-circuit models are used for the transformer design without the need for full-wave electromagnetic simulations. To demonstrate the feasibility of the millimeter-wave transformer, a 200-mW (23 dBm) 60-GHz power amplifier has been implemented in a standard 130-nm SiGe process technology, which, to date, is the highest reported output power in an SiGe process technology at millimeter-wave frequencies. The size of the output transformer is only 160times160 mum² and demonstrates the feasibility of efficient power combining and impedance transformation at millimeter-wave frequencies. The two-stage amplifier has 13 dB of compressed gain and achieves a power-added efficiency of 6.4% while combining the power of eight cascode amplifiers into a differential 100-Omega load. The amplifier supply voltage is 4 V with a quiescent current consumption of 300 mA     

Multi-Keyword search over encrypted data with scoring and search pattern obfuscation

Search over encrypted data recently became a critical operation that raised a considerable amount of interest in both academia and industry. Especially, as outsourcing, sensitive data to cloud prove to be a strong trend to benefit from the unmatched storage and computing capacities thereof. Indeed, privacy-preserving search over encrypted data, an apt term to address privacy-related issues concomitant in outsourcing sensitive data, have been widely investigated in the literature under different models and assumptions. In this work, we propose an efficient scheme that allows privacy-preserving search over encrypted data using queries with multiple keywords. Most important contributions of this work are as follows. Firstly, using a property referred as \(\delta \)-mean query obfuscation, the proposed scheme hides the search patterns, which are allowed to leak in many works in the literature including our preliminary work on the subject Orencik et al. (2013) [1]. Secondly, a two-server setting is employed to eliminate the correlation between the queries and matching documents sent to the user under the assumption that the two servers are not colluding. Thirdly, we propose a novel compression scheme that reduces both the communication cost between the two servers and the computation cost of the search operation more than 55 times compared to the standard approach. And finally, the proposed scheme also provides an effective scoring and ranking capability that is based on term frequency–inverse document frequency (tf-idf) weights of keyword–document pairs. Our analyses demonstrate that the proposed scheme is privacy-preserving, efficient and effective.