Particle acceleration and radiation friction effects in the filamentation instability of pair plasmas

The evolution of the filamentation instability produced by two counter-streaming pair plasmas is studied with particle-in-cell (PIC) simulations in both one (1D) and two (2D) spatial dimensions. Radiation friction effects on particles are taken into account. After an exponential growth of both the magnetic field and the current density, a nonlinear quasi-stationary phase sets up characterized by filaments of opposite currents. During the nonlinear stage, a strong broadening of the particle energy spectrum occurs accompanied by the formation of a peak at twice their initial energy. A simple theory of the peak formation is presented. The presence of radiative losses does not change the dynamics of the instability but affects the structure of the particle spectra.Comment: 8 pages, 8 figures, submitted to MNRA

A quantitative analysis of educational resources on the World Wide Web

The purpose of this study was to provide educators with a sampling of the educational resources that are available on the world wide web. It was also designed to determine the different categories of web sites available. The study was conducted by using the Yahoo! search engine. A search was entered for areas such as Social Studies and Special Education. The resulting web sites were then navigated to determine their relevancy to the study. Relevant web sites were placed into the following categories: Information sites and Lesson Plan sites. The sub-categories of Information sites are: For the Classroom, Special Education, Teacher Resources, References, and Content Areas. A quantitative analysis of the data was performed in order to find the number and percentage of web sites contained in each category. Two hundred ninety-two web sites were examined. Fifty-four of these sites were Lesson Plan sites and two hundred thirty-eight were Information sites. The Content Area sub-category contained the highest number of sites with one hundred fifteen and Social Studies was the dominant subject with forty-two sites

Cisplatin, 5-fluorouracil and interferon alpha 2b for recurrent or metastatic head and neck cancer.

On the basis of preclinical data suggesting the possibility of maximising the efficacy of 5-fluorouracil and cisplatin by interferon, a pilot clinical trial was initiated in recurrent and/or metastatic head and neck cancer. Thirty-four patients were treated with cisplatin at 100 mg m-2, followed by 5-fluorouracil at 1,000 mg m-2 by continuous infusion for 5 days. Interferon alpha 2b was administered at the dose of 3 million U i.m. daily for 7 days, beginning the day before chemotherapy. Courses were repeated every 3 weeks. Two patients achieved a complete remission, six a partial response, 14 had stable disease and 12 progressed on therapy, for an overall response rate of 23% (95% confidence interval 10-36%). Median survival time was 5 months. Toxicity was severe. Stomatitis, diarrhoea and myelosuppression were the most common side-effects. Because of the poor response rate and the presence of severe toxicity, in our opinion further clinical trials in head and neck cancer should be attempted only after a better definition in preclinical studies of interactions among 5-fluorouracil, cisplatin and interferon

A hybrid asymptotic-FVTD method for the estimation of the radar cross section of 3D structures

The Finite Volume Time-Domain (FVTD) method is an effective full-wave technique which allows an accurate computation of the electromagnetic field. In order to analyze the scattering effects due to electrically large structures, it can be combined with methods based on high-frequency approximations. This paper proposes a hybrid technique, which combines the FVTD method with an asymptotic solver based on the physical optics (PO) and the equivalent current method (ECM), allowing the solution of electromagnetic problems in the presence of electrically large structures with small details. Preliminary numerical simulations, aimed at computing the radar cross section of perfect electric conducting (PEC) composite objects, are reported in order to evaluate the effectiveness of the proposed method

Macroscopic contact angle and liquid drops on rough solid surfaces via homogenization and numerical simulations

We discuss a numerical formulation for the cell problem related to a homogenization approach for the study of wetting on micro rough surfaces. Regularity properties of the solution are described in details and it is shown that the problem is a convex one. Stability of the solution with respect to small changes of the cell bottom surface allows for an estimate of the numerical error, at least in two dimensions. Several benchmark experiments are presented and the reliability of the numerical solution is assessed, whenever possible, by comparison with analytical one. Realistic three dimensional simulations confirm several interesting features of the solution, improving the classical models of study of wetting on roughness

Pregnancy in immigrant women

Objective: We wanted to study how foreign women face pregnancy and childbirth in a society quite different from their own. Methods: In 2004 we studied 328 pregnant women at the Department of Gynaecology at the "General Hospital Umberto 1" in Rome. Information on patients' personal lives and experiences was collected. Results: Women were classified into six (6) groups based on nationality, race, religion and culture. Conclusions: Arabian women had the most natural childbirths. African women had a longer duration of gestation. Women from Eastern Europe underwent frequent tests and examinations, but had the highest chance of having preterm births. Chinese women did not usually undergo many examinations and were able to tolerate pain during childbirth quite well

A Short-Range FMCW Radar-Based Approach for Multi-Target Human-Vehicle Detection

In this article, a new microwave-radar-based technique for short-range detection and classification of multiple human and vehicle targets crossing a monitored area is proposed. This approach, which can find applications in both security and infrastructure surveillance, relies upon the processing of the scattered-field data acquired by low-cost off-The-shelf components, i.e., a 24 GHz frequency-modulated continuous wave (FMCW) radar module and a Raspberry Pi mini-PC. The developed method is based on an ad hoc processing chain to accomplish the automatic target recognition (ATR) task, which consists of blocks performing clutter and leakage removal with an infinite impulse response (IIR) filter, clustering with a density-based spatial clustering of applications with noise (DBSCAN) approach, tracking using a Benedict-Bordner $alpha$-$eta$ filter, features extraction, and finally classification of targets by means of a $k$-nearest neighbor ( $k$-NN) algorithm. The approach is validated in real experimental scenarios, showing its capabilities in correctly detecting multiple targets belonging to different classes (i.e., pedestrians, cars, motorcycles, and trucks)

Ultra-intense laser interaction with nanostructured near-critical plasmas

Near-critical plasmas irradiated at ultra-high laser intensities (I > 1018W/cm2) allow to improve the performances of laser-driven particle and radiation sources and to explore scenarios of great astrophysical interest. Near-critical plasmas with controlled properties can be obtained with nanostructured low-density materials. By means of 3D Particle-In-Cell simulations, we investigate how realistic nanostructures influence the interaction of an ultra-intense laser with a plasma having a near-critical average electron density. We find that the presence of a nanostructure strongly reduces the effect of pulse polarization and enhances the energy absorbed by the ion population, while generally leading to a significant decrease of the electron temperature with respect to a homogeneous near-critical plasma. We also observe an effect of the nanostructure morphology. These results are relevant both for a fundamental understanding and for the foreseen applications of laser-plasma interaction in the near-critical regime