Health of laying hens in an aviary system over five batches of birds

Mortality and health were studied in laying hens kept in an aviary system on a practical scale. All management inputs were done by university staff. Five batches of birds (trials) during a period of 6 years with approximately 4,700 birds per trial were included in the study. The aviary was a three-tiered "Marielund" system divided into 4 pens. Three hybrids, reared on litter with access to perches, were used; Lohmann Selected Leghorn (LSL), Lohmann Brown (LB) and an experimental cross (SLU-1329). The hens were not beak-trimmed. The stocking density was 17 hens/m2 ground floor. Mortality varied between pens and between batches, ranging from normal rates of 3.4% to 7.8%, except in LSL in Trial 2 and LB in Trial 3 where it was much higher (15.6% and 20.9%, respectively). The dominating causes of total mortality were salpingitis and cannibalism. Coccidiosis and lymphoid leucosis contributed significantly to mortality in Trial 2. An infestation with fowl mites (Dermanyssus gallinae) occurred in Trial 1. Feather loss was most severe in LB. Keel bone deviations were recorded at increasing levels by age. Foot abscesses occurred more frequently at 35 weeks than at 55 weeks. LSL was more severely affected than LB and SLU-1329.     

Significant time constants defined by high-current charge dynamicsin advanced silicon-based bipolar transistors

Analytical expressions for the time constants in advanced silicon-based bipolar transistors defined by the charge dynamics in the base-collector junction space-charge region (τ_C) and by the charge modulation in the quasi-neutral base (τ_BM) are derived based on an accounting for the high-current-induced perturbation of the space-charge region. The derivations show that voltage drops in the intrinsic and extrinsic collector regions and in the extrinsic emitter region are important in defining τ_C and τ_BM, and that τ_BM is approximately proportional to collector-current density. Application of the results to an aggressive SiGe-base HBT technology shows that τ_C and τ_BM are comparable to the base transit time, and hence that they are significant in defining high-current speed of the HBT     

A novel trench-defined MISIM CCD structure for X-ray imaging andother applications

A charge-coupled device (CCD) utilizing a trench-defined metal-insulator-semiconductor-insulator-metal (MISIM) sandwich structure is proposed and analyzed. The CCD features high charge capacity and a deep photogenerated carrier collection depth. The trench CCD structure has potential application in X-ray imaging as well as in high-density visible and infrared imaging     

What do successful computer science students know? An integrative analysis using card sort measures and content analysis to evaluate graduating students' knowledge of programming concepts

Abstract: This paper describes a multi‐institutional study that used a repeated single‐criterion card sort to investigate graduating computer science students' knowledge of programming concepts. The study seeks to improve computer science instruction by gaining insight into how graduating students retain and assimilate introductory programming knowledge into their broader understanding of the discipline. A total of 291 card sorts was elicited from 65 undergraduate students in their final year of study at eight colleges and universities throughout the USA. To fully exploit the rich qualitative and quantitative aspects of the card sort data, an integrative analysis process was used that combined content analysis with two measures, normalized minimum spanning tree and edit distance, both developed specifically to analyze card sort data.     

Numerical simulation of temperature-dependent minority-hole transport in n silicon emitters

A one-dimensional numerical computer simulation of minority-hole transport in heavily doped n⁺ silicon emitters is developed accounting for significant temperature dependences. The model includes the most recent insights regarding heavy-doping effects, which indeed facilitate the accounting for the temperature dependences. Measurements of base current in polysilicon-contacted n⁺pn transistors over a wide temperature range, carefully interpreted by accounting for unavoidable device/ambient temperature discrepancies, support the model and demonstrate its utility, for example in characterizing the electrical properties of the polysilicon emitter contact.     

Utilization of N,N-diethyl-3,5-difluorobenzene sulfonamide to prepare functionalized poly(arylene ether)s

A series of poly(arylene ether)s carrying a pendant diethyl sulfonamide group was prepared by the meta activated nucleophilic aromatic substitution reaction of a new aryl difluoride monomer, N,N-diethyl-3,5-difluorobenzene sulfonamide. The synthesis of N,N-diethyl-3,5-difluorobenzene sulfonamide was achieved via the one-step reaction of diethyl amine with commercially available 3,5-difluorobenzenesulfonyl chloride. Model reactions and NMR data indicated that the fluoride atoms were sufficiently activated by the sulfonamide group, located in the meta position, to provide access to high molecular weight poly(arylene ether)s. The corresponding poly(arylene ether)s, were prepared by reaction of N,N-diethyl-3,5-difluorobenzene sulfonamide with bisphenol A, bisphenol AF, 4,4′-biphenol, hydroquinone, resorcinol, and 4,4′-dihydroxydiphenyl ether. The polymers were characterized via NMR spectroscopy, size exclusion chromatography, thermogravimetric analysis, and differential scanning calorimetry. The sulfonamide based poly(arylene ether)s displayed moderate thermal stability with 5% weight loss temperatures ranging from 366 to 385 °C, but possessed relatively low glass transition temperatures, 72–142 °C.     

Physical noise modeling of SOI MOSFETs with analysis of theLorentzian component in the low-frequency noise spectrum

The implementation of a general physics-based compact model for noise in silicon-on-insulator (SOI) MOSFETs is described. Good agreement is shown between model-predicted and measured low-frequency (LF) noise spectra. In particular, the behavior of an excess Lorentzian component that dominates the LF noise spectra of SOI MOSFETs is investigated. Shot noise associated with the generation and removal (via recombination or a body contact) of body charge is shown to underlie the behavior of the Lorentzian in both floating-body and body-tied-to-source SOI MOSFET's operating under partially depleted or “mildly” fully depleted conditions; the Lorentzian is suppressed when the body is “strongly” fully depleted. Good physical insight distinguishes the behavior of the Lorentzian components in all these devices, and predicts the occurrence of additional excess noise sources in future scaled technologies. Simple analytic expressions that approximate the full model are derived to provide the insight     

Analytic accounting for carrier velocity overshoot in advancedBJT's for circuit simulation

An analytic model for electron velocity overshoot in advanced silicon-based bipolar junction transistors (BJTs) is presented. The model, which characterizes an effective saturated drift velocity in the collector space-charge regions, is intended for circuit simulation and has been implemented in MMSPICE. The model is based on a nonlocal augmented drift-velocity formalism that involves a length coefficient derived from Monte Carlo simulations. A phenomenological representation of the associated velocity relaxation is defined to be consistent with the overshoot analysis. Demonstrative MMSPICE device and circuit simulations show that effects of velocity overshoot in contemporary silicon BJTs produce only small performance enhancements, but can be exploited to optimize design tradeoffs in scaled technologies