Polarized light detection in spiders

Copyright © 2001 The Company of BiologistsWe describe here the detection of polarized light by the simple eyes of spiders. Using behavioural, morphological, electrophysiological and optical studies, we show that spiders have evolved two different mechanisms to resolve the e-vector of light. Wolf spiders (Lycosidae), are able to turn in response to rotation of a polarized pattern at the zenith of their visual fields, and we also describe a strip in the ventral retina of the principal (anterio-median) eyes that views this location and has receptors tiered into two layers. This provides each pair of receptors with a similar optical solution to that provided by the ‘dorsal rim area’ of the insect compound eye. In contrast, gnaphosid spiders have evolved a pair of lensless secondary eyes for the detection of polarized light. These two eyes, each sensitive to orthogonal directions of polarization, are perfectly designed to integrate signals from the larger part of the sky and cooperate to analyse the polarization of light. Built-in polarizers help to improve signal purity. Similar organisation in the eyes of several other spider families suggests that these two mechanisms are not restricted to only a few families.Marie Dacke, Thuy A. Doan and David C. O’Carrol

HD101584: Circumstellar characteristics and evolutionary status

We have performed a study of the characteristics of the circumstellar environment of the binary object HD101584, that provides information on a likely evolutionary scenario. We have obtained and analysed ALMA observations, complemented with observations using APEX, of a large number of molecular lines. An analysis of the spectral energy distribution has also been performed. Emissions from 12 molecular species (not counting isotopologues) have been observed, and most of them mapped with angular resolutions in the range 0.1" to 0.6". Four circumstellar components are identified: i) a central compact source of size 0.15", ii) an expanding equatorial density enhancement (a flattened density distribution in the plane of the orbit) of size 3", iii) a bipolar high-velocity outflow (150 km/s), and iv) an hourglass structure. The outflow is directed almost along the line of sight. There is evidence of a second bipolar outflow. The mass of the circumstellar gas is 0.5[D/1 kpc]^2 Msun, about half of it lies in the equatorial density enhancement. The dust mass is 0.01[D/1 kpc]^2 Msun, and a substantial fraction of this is in the form of large-sized, up to 1 mm, grains. The estimated kinetic age of the outflow is 770[D/1 kpc] yr. The kinetic energy and the scalar momentum of the accelerated gas are estimated to be 7x10^(45)[D/1 kpc]^2 erg and 10^(39)[D/1 kpc]^2 g cm/s, respectively. We provide good evidence that the binary system HD101584 is in a post-common-envelope-evolution phase, that ended before a stellar merger. Isotope ratios combined with stellar mass estimates suggest that the primary star's evolution was terminated already on the first red giant branch (RGB). Most of the energy required to drive the outflowing gas was probably released when material fell towards the companion.Comment: Accepted for publication in A&

Performance Analysis on IEEE 802.11ah Standard with Enhanced Distributed Channel Access Mechanism

IEEE 802.11ah is a new task group on the IEEE 802.11 standard designed to work on the 900 MHz. It is with a range of communication coverage up to 1kilometer, lower energy consumption, and up to 8191 stations. There are two types of STAs in 802.11ah: sensor type to support sensor service and non-sensor type for offload service. In this research, it only focuses on non-sensor STA. For non-sensor STA, maximizing throughput is more important than power consumption. This research aims to see the performance of IEEE 802.1 1ah with Enhanced Distributed Channel Access (EDCA). To achieve that purpose, a mechanism is needed to provide guarantees various services required by theSTA. EDCA is an access mechanism used to set the Quality of Service (QoS) for the IEEE 802.11 standard through modifications in MAC layer. In this research,it focuses on one of the EDCA parameters, Arbitration Inter-Frame Space (AIFS). In addition, this research also focuses on the 802.11ah feature is Restricted Access Window (RAW) by changing the number of the RAW groups. From the results of the research, it is found that the improvement scheme with Arbitration Inter-Frame Space Number (AIFSN) value AC BK = 2, AC BE = 1, AC VI = 1, AC VO = 1 has better performance compared to the default scheme with AIFSN value AC BK = 7, AC BE = 3, AC VI = 2, AC VO = 2) with an average throughput of 1.504598 Mbps, average overall delay of 0.066242 second and average PDR of 62%. In addition, changes in the number of RAW groups and RAW slots affect network performance. This feature can improve the value of throughput, average delay, and Packet Delivery Ratio. The goals of this research is to know the effect of AIFSN value changes on AIFSN parameters, variation of RAW group and RAW slot number to throughput,average delay and packet delivery ratio

Analisis Throughput Dan Skalabilitas Virtualized Network Function VyOS Pada Hypervisor VMWare ESXi, XEN, DAN KVM

Virtualisasi berjalan diatas suatu hypervisor yang merupakan suatu program untuk membuat dan menjalankan virtual machine. Hypervisor mengatur sejumlah resources hardware seperti RAM, CPU, dan storage yang dimiliki hardware aslinya untuk digunakan bersama-sama dengan virtual environment. Salah satu implementasi yang dapat dimanfaatkan dengan adanya virtualisasi adalah Network Function Virtualization atau yang biasa disebut NFV. Konsep ini memanfaatkan teknik virtualisasi untuk membuat suatu Virtualized Network Function (VNF) yang memiliki fungsi sama dengan network device aslinya. Salah satu VNF yang dapat digunakan secara bebas adalah VyOS. VyOS merupakan sistem operasi jaringan berbasis open source yang memiliki fungsi seperti hardware router tradicional, firewall. VPN, proxy dan fungsi jaringan lainnya. Pada penelitian ini dilakukan pengujian performansi VyOS pada bare-metal hypervisor (XEN, VMware ESXi) dan hosted hypervisor (Kernel-based Virtual Machine atau KVM).  Penelitian ini bertujuan untuk mengetahui kinerja dari ketiga hypervisor tersebut dalam menjalankan VNF dengan parameter throughput, dan parameter skalabilitas. Dari hasil pengujian dan análisis dapat disimpulkan bahwa KVM memiliki performansi kecepatan tertinggi dengan besar throughput 19.29 GB/s. Sedangkan untuk parameter skalabilitas, VMware memiliki skalabilitas yang sangat baik yang ditunjukkan dengan kecilnya degradasi performansi pada throughput saat menjalankan banyak VNF daripada XEN dan KVM

Performance Analysis of VXLAN and NVGRE Tunneling Protocol on Virtual Network

Virtualization is a new revolutionary approach in networking industry, its make possible to build several virtual machine (VM) in one physical hardware. In virtualization practice, one VM might be connected to others, but not all of VM in one environment must be connected due the privacy and security issues. One of the solutions which can address this issue is tunneling protocol. Tunneling protocol is a layer-2-in-layer-3 protocol which can isolate tenant traffic in virtualize environment. This research conducted about the performance of VXLAN and NVGRE tunneling protocol which works on virtualize environment and aims to determine the perfomances of throughput, delay, jitter, and vCPU Usage using variable packet size in range of 128-1514 byte. From the the result, can be conclude that both of tunneling protocol can isolate the traffic between tenant. For the performance result, NVGRE has the highest value of throughput, 771,02 Mbps and the VXLAN got 753,62 Mbps. For the delay NVGRE got 2.24 ms and VXLAN got 2.29 ms. For the jitter, NVGRE has better rate value of 0.361 ms, than VXLAN value of 0.348 ms, and the vCPU USAge performance, NVGRE has the highest performance too that value is 60.57%. So on overall performance NVGRE has the better performance than VXLAN

Comparing drug-using behaviors among high school graduates entering military service, college, and civilian employment

https://deepblue.lib.umich.edu/bitstream/2027.42/137885/1/occ42.pd

Autocorrelation analysis for the unbiased determination of power-law exponents in single-quantum-dot blinking

We present an unbiased and robust analysis method for power-law blinking statistics in the photoluminescence of single nano-emitters, allowing us to extract both the bright- and dark-state power-law exponents from the emitters' intensity autocorrelation functions. As opposed to the widely-used threshold method, our technique therefore does not require discriminating the emission levels of bright and dark states in the experimental intensity timetraces. We rely on the simultaneous recording of 450 emission timetraces of single CdSe/CdS core/shell quantum dots at a frame rate of 250 Hz with single photon sensitivity. Under these conditions, our approach can determine ON and OFF power-law exponents with a precision of 3% from a comparison to numerical simulations, even for shot-noise-dominated emission signals with an average intensity below 1 photon per frame and per quantum dot. These capabilities pave the way for the unbiased, threshold-free determination of blinking power-law exponents at the micro-second timescale

The Monitoring the Future 8th Grade Panel Survey Data: Sample Design, Adjustments for Panel Attrition Biases, and Assessment of Measurement Bias

https://deepblue.lib.umich.edu/bitstream/2027.42/137871/1/occ55.pd

An iterative scheme for distributed model predictive control using Fenchel’s duality,

Abstract We present an iterative distributed version of Han's parallel method for convex optimization that can be used for distributed model predictive control (DMPC) of industrial processes described by dynamically coupled linear systems. The underlying decomposition technique relies on Fenchel's duality and allows subproblems to be solved using local communications only. We investigate two techniques aimed at improving the convergence rate of the iterative approach and illustrate the results using a numerical example. We conclude by discussing open issues of the proposed method and by providing an outlook on research in the field