A Monitor of the Focusing Strength of Plasma Lenses Using MeV Synchrotron Radiation

The focusing strength of plasma lenses used with high energy electron or positron beams can give rise to synchrotron radiation with critical energies in the MeV range. A method is described for measuring the characteristic energy of this radiation as a way of monitoring the strength of the focus. The principle has been implemented in a plasma lens experiment with a 28.5 GeV positron beam

Inductive and Electrostatic Acceleration in Relativistic Jet-Plasma Interactions

We report on the observation of rapid particle acceleration in numerical simulations of relativistic jet-plasma interactions and discuss the underlying mechanisms. The dynamics of a charge-neutral, narrow, electron-positron jet propagating through an unmagnetized electron-ion plasma was investigated using a three-dimensional, electromagnetic, particle-in-cell computer code. The interaction excited magnetic filamentation as well as electrostatic plasma instabilities. In some cases, the longitudinal electric fields generated inductively and electrostatically reached the cold plasma wave-breaking limit, and the longitudinal momentum of about half the positrons increased by 50% with a maximum gain exceeding a factor of 2 during the simulation period. Particle acceleration via these mechanisms occurred when the criteria for Weibel instability were satisfied.Comment: Revised for Phys. Rev. Lett. Please see publised version for best graphic

Code phase assignment DS/CDMA communications for indoor wireless Rician multipath fading channels

The technique of using a single basic signature sequence for the DS/CDMA system was investigated. All users have their sequences differed by cyclic phase shifts from a basic signature sequence. It is called Code Phase Assignment (CPA). In [1], it has been shown that the CPA DS/CDMA technique yielded better performance over conventional DS/CDMA communications by substantial reduction of the multiple access interference (MAI) and the multipath interference (MI) for a simplified channel model. This paper further investigates its performance in the indoor Rician multipath fading channel. Comparison with conventional DS/CDMA system will be made and the effect on the change of system parameters will be investigated. Higher multiple access capacity over conventional DS/CDMA will be demonstrated. Lastly, CPA could reduce the effort of exhaustive search for sequences which makes it suitable for indoor applications.published_or_final_versio

Error probabilities of synchronous DS/CDMA communications over multipath Rayleigh fading channels

This paper derives error probabilities for BPSK synchronous DS/CDMA communications over multipath Rayleigh fading WSSUS channels using a RAKE receiver. Both cases of perfectly and approximately synchronized signal transmission are considered. Numerical results are presented.published_or_final_versio

Some Results On Spectrum And Energy Of Graphs With Loops

Let $G_S$ be a graph with loops obtained from a graph $G$ of order $n$ and loops at $S \subseteq V(G)$. In this paper, we establish a neccesary and sufficient condition on the bipartititeness of a connected graph $G$ and the spectrum Spec($G_S$) and Spec($G_{V(G)\backslash S}$). We also prove that for every $S \subseteq V(G)$, $E(G_S) \geq E(G)$ when $G$ is bipartite. Moreover, we provide an identification of the spectrum of complete graphs $K_n$ and complete bipartite graphs $K_{m,n}$ with loops. We characterize any graphs with loops of order n whose eigenvalues are all positive or non-negative, and also any graphs with a few distinct eigenvalues. Finally, we provide some bounds related to $G_S$.Comment: 16 pages, published versio

Aplikasi Algoritma Semi – Fragile Image Watermarking Berdasarkan pada Region Segmentation

Kebanyakan algoritma semi-fragile watermarking yang telah ada memiliki kelemahan, seperti sifat tidak kelihatan (invisibility) yang jelek, robustness yang tidak sempurna pada beberapa rutin dari proses sinyal. Penyebab utamanya adalah karena kebanyakan algoritma menggunakan parameter kuantisasi tertentu tanpa mempertimbangkan perbedaan diantara citra. Untuk menyelesaikan permasalahan ini, Shengbing Che, Bin Ma, Jinkai Luo dan Shaojun Yu dari China (2009) [1] memperkenalkan sebuah algoritma image watermarking berdasarkan pada segmentasi region. Proses kerja dari sistem dimulai dari pemilihan citra sampul dan citra watermark hitam putih. Setelah itu, dilanjutkan pengisian nilai kunci dan proses pengacakan terhadap citra hitam putih. Kemudian, citra sampul akan dikonversi ke bentuk grayscale dan terakhir citra hitam putih akan ditempelkan ke dalam citra sampul. Citra watermark yang diperoleh dapat disimpan ke dalam sebuah file yang akan digunakan pada proses ekstraksi untuk mengekstrak keluar citra watermark hitam putih yang disisipkan di dalamnya. Hasil pengujian menunjukkan waktu eksekusi proses penempelan watermark relatif lebih cepat dari proses ekstraksi. Algoritma tidak bisa mengekstraksi citra hitam putih ketika citra watermark diberi efek brightness dan contrast. Citra hitam putih masih dapat terekstrak keluar walau citra watermark disisipkan noise atau dicrop. Apabila ada kesalahan pengisian kunci maka akan menyebabkan citra hitam putih menjadi tidak terekstrak keluar

Global Incidence and mortality of oesophageal cancer and their correlation with socioeconomic indicators temporal patterns and trends in 41 countries

Oesophageal cancers (adenocarcinomas [AC] and squamous cell carcinomas [SCC]) are characterized by high incidence/mortality in many countries. We aimed to delineate its global incidence and mortality, and studied whether socioeconomic development and its incidence rate were correlated. The age-standardized rates (ASRs) of incidence and mortality of this medical condition in 2012 for 184 nations from the GLOBOCAN database; national databases capturing incidence rates, and the WHO mortality database were examined. Their correlations with two indicators of socioeconomic development were evaluated. Joinpoint regression analysis was used to generate trends. The ratio between the ASR of AC and SCC was strongly correlated with HDI (r = 0.535 [men]; r = 0.661 [women]) and GDP (r = 0.594 [men]; r = 0.550 [women], both p < 0.001). Countries that reported the largest reduction in incidence in male included Poland (Average Annual Percent Change [AAPC] = −7.1, 95%C.I. = −12,−1.9) and Singapore (AAPC = −5.8, 95%C.I. = −9.5,−1.9), whereas for women the greatest decline was seen in Singapore (AAPC = −12.3, 95%C.I. = −17.3,−6.9) and China (AAPC = −5.6, 95%C.I. = −7.6,−3.4). The Philippines (AAPC = 4.3, 95%C.I. = 2,6.6) and Bulgaria (AAPC = 2.8, 95%C.I. = 0.5,5.1) had a significant mortality increase in men; whilst Columbia (AAPC = −6.1, 95%C.I. = −7.5,−4.6) and Slovenia (AAPC = −4.6, 95%C.I. = −7.9,−1.3) reported mortality decline in women. These findings inform individuals at increased risk for primary prevention

High Power Amplifier and Power Supply

A document discusses the creation of a high-voltage power supply (HVPS) that is able to contain voltages up to -20 kV, keep electrical field strengths to below 200 V/mil (approximately equal to 7.87 kV/mm), and can provide a 200-nanosecond rise/fall time focus modulator swinging between cathode potential of 16.3 kV and -19.3 kV. This HVPS can protect the 95-GHz, pulsed extended interaction klystron (EIK) from arcs/discharges from all sources, including those from within the EIK fs vacuum envelope. This innovation has a multi-winding pulse transformer design, which uses new winding techniques to provide the same delays and rise/fall times (less than 10 nanoseconds) at different potential levels ranging from -20 kV to -16 kV. Another feature involves a high-voltage printed-wiring board that was corona-free at -20 kV DC with a 3- kV AC swing. The corona-free multilayer high-voltage board is used to simulate fields of less than 200 V/mil (approximately equal to 7.87 kV/mm) at 20 kV DC. Drive techniques for the modulator FETs (field-effect transistors) (four to 10 in a series) were created to change states (3,000-V swing) without abrupt steps, while still maintaining required delays and transition times. The packing scheme includes a potting mold to house a ten-stage modulator in the space that, in the past, only housed a four-stage modulator. Problems keeping heat down were solved using aluminum oxide substrate in the high-voltage section to limit temperature rise to less than 10 while withstanding -20 kV DC voltage and remaining corona-free

A comprehensive framework for prioritizing variants in exome sequencing studies of Mendelian diseases

Exome sequencing strategy is promising for finding novel mutations of human monogenic disorders. However, pinpointing the casual mutation in a small number of samples is still a big challenge. Here, we propose a three-level filtration and prioritization framework to identify the casual mutation(s) in exome sequencing studies. This efficient and comprehensive framework successfully narrowed down whole exome variants to very small numbers of candidate variants in the proof-of-concept examples. The proposed framework, implemented in a user-friendly software package, named KGGSeq (http://statgenpro.psychiatry.hku.hk/kggseq), will play a very useful role in exome sequencing-based discovery of human Mendelian disease genes