III-V on-silicon sources for optical interconnect applications

Optical interconnects require efficient and flexible optical sources. This paper presents results on two technology platforms being developed for realizing these. Integration using wafer bonding technologies is well established now and the focus is on new device types including tunable lasers, multi-wavelength lasers and switching. As an alternative, we also started work on monolithic integration using heteroepitaxy directly on silicon. We here report recent results on low threshold nanowire lasers

Optimally Dense Packings for Fully Asymptotic Coxeter Tilings by Horoballs of Different Types

The goal of this paper to determine the optimal horoball packing arrangements and their densities for all four fully asymptotic Coxeter tilings (Coxeter honeycombs) in hyperbolic 3-space $\mathbb{H}^3$. Centers of horoballs are required to lie at vertices of the regular polyhedral cells constituting the tiling. We allow horoballs of different types at the various vertices. Our results are derived through a generalization of the projective methodology for hyperbolic spaces. The main result states that the known B\"or\"oczky--Florian density upper bound for "congruent horoball" packings of $\mathbb{H}^3$ remains valid for the class of fully asymptotic Coxeter tilings, even if packing conditions are relaxed by allowing for horoballs of different types under prescribed symmetry groups. The consequences of this remarkable result are discussed for various Coxeter tilings.Comment: 26 pages, 10 figure

The learning curve of laparoscopic, robot-assisted and transanal total mesorectal excisions:a systematic review

Background The standard treatment of rectal carcinoma is surgical resection according to the total mesorectal excision principle, either by open, laparoscopic, robot-assisted or transanal technique. No clear consensus exists regarding the length of the learning curve for the minimal invasive techniques. This systematic review aims to provide an overview of the current literature regarding the learning curve of minimal invasive TME. Methods A systematic literature search was performed. PubMed, Embase and Cochrane Library were searched for studies with the primary or secondary aim to assess the learning curve of either laparoscopic, robot-assisted or transanal TME for rectal cancer. The primary outcome was length of the learning curve per minimal invasive technique. Descriptive statistics were used to present results and the MINORS tool was used to assess risk of bias. Results 45 studies, with 7562 patients, were included in this systematic review. Length of the learning curve based on intraoperative complications, postoperative complications, pathological outcomes, or a composite endpoint using a risk-adjusted CUSUM analysis was 50 procedures for the laparoscopic technique, 32-75 procedures for the robot-assisted technique and 36-54 procedures for the transanal technique. Due to the low quality of studies and a high level of heterogeneity a meta-analysis could not be performed. Heterogeneity was caused by patient-related factors, surgeon-related factors and differences in statistical methods. Conclusion Current high-quality literature regarding length of the learning curve of minimal invasive TME techniques is scarce. Available literature suggests equal lengths of the learning curves of laparoscopic, robot-assisted and transanal TME. Well-designed studies, using adequate statistical methods are required to properly assess the learning curve, while taking into account patient-related and surgeon-related factors

Bayesian Centroid Estimation for Motif Discovery

Biological sequences may contain patterns that are signal important biomolecular functions; a classical example is regulation of gene expression by transcription factors that bind to specific patterns in genomic promoter regions. In motif discovery we are given a set of sequences that share a common motif and aim to identify not only the motif composition, but also the binding sites in each sequence of the set. We present a Bayesian model that is an extended version of the model adopted by the Gibbs motif sampler, and propose a new centroid estimator that arises from a refined and meaningful loss function for binding site inference. We discuss the main advantages of centroid estimation for motif discovery, including computational convenience, and how its principled derivation offers further insights about the posterior distribution of binding site configurations. We also illustrate, using simulated and real datasets, that the centroid estimator can differ from the maximum a posteriori estimator.Comment: 24 pages, 9 figure

On the combustion of fine iron particles beyond FeO stoichiometry: Insights gained from molecular dynamics simulations

Molecular dynamics (MD) simulations are performed to investigate the thermal and mass accommodation coefficients (TAC and MAC, respectively) for the combination of iron(-oxide) and air. The obtained values of TAC and MAC are then used in a point-particle Knudsen model to investigate the effect on the combustion behavior of (fine) iron particles. The thermal accommodation for the interactions of $\mathrm{Fe}$ with $\mathrm{N_2}$ and $\mathrm{Fe_xO_y}$ with $\mathrm{O_2}$ is investigated for different surface temperature, while the mass accommodation coefficient for iron(-oxide) with oxygen is investigated for different initial oxidation stages $Z_\mathrm{O}$, which represents the molar ratio of $\mathrm{O}/\left(\mathrm{O} + \mathrm{Fe}\right)$, and different surface temperatures. The MAC decreases almost linearly as a function of $Z_\mathrm{O}$, with a steeper slope when $Z_\mathrm{O} < 0.5$ and a gentler slope when $0.5 < Z_\mathrm{O} < 0.57$. By incorporating the MD-informed accommodation coefficients into the single iron particle model, the oxidation beyond $Z_\mathrm{O} = 0.5$ (from stoichiometric $\mathrm{FeO}$ to $\mathrm{Fe_3O_4}$) is modeled. A new temperature evolution for single iron particles is observed compared to results obtained with previously developed continuum models. Specifically, results of the present simulations show that the oxidation process continues after the particle reaching the peak temperature, while previous models predicting a maximum temperature was attained when the particle is fully oxidized to $Z_\mathrm{O} = 0.5$. Since the rate of formation slows down as the MAC decreases with an increasing oxidation stage, the rate of heat loss exceeds the rate of heat release upon reaching the maximum temperature. Finally, the effect of transition-regime heat and mass transfer on the combustion behavior of fine iron particles is investigated and discussed

Perekonomian Indonesia dalam Menghadapi Sistem Globalisasi

Globalisation is a part of human being. Until now, there aren´t succes for a nation without relation and assosiation to other countries. Indonesia hope, that globalisation can continue the national economic market system to the international level. What is our attitude to face it? what is the agenda need to be prepared? Preparing non market institution is a key toface globalisation and executing more effective diplomacy. Keywords:Globalisation, Economic market system

Принципи реалізму і теорії націоналізму

Статтю присвячено порівняльному аналізові теорій націоналізму й теорії політичного реалізму. Здійснена спроба синтезу цих двох теоретичних формацій з метою вдосконалення пізнавального апарату політології міжнародних відносин. На підставі базових положень реалізму, розглянуто роль націоналізму, як глобальної соціальної сили в світовій політиці, а також реалістські теоретичні інтерпретації цієї сили. Особливу увагу надано витлумаченню націоналізму як фактору міжнародних конфліктів та наслідкам для систем міжнародних відносин національних державотворчих процесів.Статья посвящена сравнительному анализу теорий национализма и теории политического реализма. С целью усовершенствования познавательного аппарата политологии международных отношений, осуществлена попытка синтеза этих двух теоретических систем. На основании базовых положений реализма рассмотрена роль национализма в мировой политике, а также реалистские интерпретации этой определяющей силы современности. Особое внимание уделено интерпретации роли национализма в международных конфликтах и последствиям для международных систем процессов образования новых государств.The article deals with comparative analysis of the theories of nationalism and theory of political realism. This study aimed at methodological synthesis of these two groups of theories in order to improve a cognitive potential of political science in the sphere of its application to international relations. The role of nationalism as a global social factor and interpretation of this factor by realism is regarded. The special research attention is paid to the ways modern international conflicts and state1building processes are inspired by nationalism

Phase modulators ands splitting network on Si PIC coherent fiber beam combining

Coherent beam combining (CBC) of fiber lasers provide an attractive mean of reaching high output laser power by scaling up the available energy while keeping fiber intrinsic advantages of compactness, reliability, efficiency, and beam quality. In CBC architectures, the power of a master oscillator (MO) is divided into N fibers that are amplified individually. The phase perturbations between channels can be measured using various techniques [1-3] and are corrected by individual phase modulators placed on each fiber before the amplification. In this Communication, we present a Silicon PIC integrating a 1:16 channels splitting network and thermal phase modulators array with low electrical power consumption and a bandwidth compatible with CBC requirements. In our CBC system, a 1.55µm CW master oscillator directly feeds the Silicon chip through a grating coupler, as shown in Fig.1(a). The power of the master oscillator is first split on chip into 16 channels, each of which including a thermal phase modulator. The outputs of the 16 waveguides are collectively out-coupled from the chip using a PM optical fiber array aligned and glued onto the PIC’s output grating couplers array [4]. At the other end of fiber array, the 16 fiber outputs are arranged in a 4 by 4 squared lattice, and collimated by a microlens array to form 16 collimated and parallel beamlets. The phase distribution from channel to channel is derived from the fringe pattern resulting from the collimated beamlets interfering with a reference plane wave on a camera. This signal is fed back to drive the PIC’s phase modulators in order to phase lock the 16 fiber

Progression of coronary artery calcification in conventional hemodialysis, nocturnal hemodialysis, and kidney transplantation

Introduction Cardiovascular disease is the leading cause of death in end-stage renal disease (ESRD) and is strongly associated with vascular calcification. An important driver of vascular calcification is high phosphate levels, but these become lower when patients initiate nocturnal hemodialysis or receive a kidney transplant. However, it is unknown whether nocturnal hemodialysis or kidney transplantation mitigate vascular calcification. Therefore, we compared progression of coronary artery calcification (CAC) between patients treated with conventional hemodialysis, nocturnal hemodialysis, and kidney transplant recipients. Methods We measured CAC annually up to 3 years in 114 patients with ESRD that were transplantation candidates: 32 that continued conventional hemodialysis, 34 that initiated nocturnal hemodialysis (>= 4x 8 hours/week), and 48 that received a kidney transplant. We compared CAC progression between groups as the difference in square root transformed volume scores per year (Delta CAC SQRV) using linear mixed models. Reference category was conventional hemodialysis. Results The mean age of the study population was 53 +/- 13 years, 75 (66%) were male, and median dialysis duration was 28 (IQR 12-56) months. Median CAC score at enrollment was 171 (IQR 10-647), which did not differ significantly between treatment groups (P = 0.83). Compared to conventional hemodialysis, CAC progression was non-significantly different in nocturnal hemodialysis -0.10 (95% CI -0.77 to 0.57) and kidney transplantation -0.33 (95% CI -0.96 to 0.29) in adjusted models. Conclusions Nocturnal hemodialysis and kidney transplantation are not associated with significantly less CAC progression compared to conventional hemodialysis during up to 3 years follow-up. Further studies are needed to confirm these findings, to determine which type of calcification is measured with CAC in end-stage renal disease, and whether that reflects cardiovascular risk