cssi/SciSciGPT-SciSciNet huggingface dataset:
Spike-Train Level Direct Feedback Alignment: Sidestepping Backpropagation for On-Chip Training of Spiking Neural Nets

Spiking neural networks (SNNs) present a promising computing model and enable bio-plausible information processing and event-driven based ultra-low power neuromorphic hardware. However, training SNNs to reach the same performances of conventional deep artificial neural networks (ANNs), particularly with error backpropagation (BP) algorithms, poses a significant challenge due to inherent complex dynamics and non-differentiable spike activities of spiking neurons. In this paper, we present the first study on realizing competitive spike-train level backpropagation (BP) like algorithms to enable on-chip training of SNNs. We propose a novel spike-train level direct feedback alignment (ST-DFA) algorithm, which is much more bio-plausible and hardware friendly than BP. Algorithm and hardware co-optimization and efficient online neural signal computation are explored for on-chip implementation of ST-DFA. On the Xilinx ZC706 FPGA board, the proposed hardware-efficient ST-DFA shows excellent performance vs. overhead tradeoffs for real-world speech and image classification applications. SNN neural processors with on-chip ST-DFA training show competitive classification accuracy of 96.27% for the MNIST dataset with 4× input resolution reduction and 84.88% for the challenging 16-speaker TI46 speech corpus, respectively. Compared to the hardware implementation of the state-of-the-art BP algorithm HM2-BP, the design of the proposed ST-DFA reduces functional resources by 76.7% and backward training latency by 31.6% while gracefully trading off classification performance.
Middle School Science Teachers' Conceptions of Assessment Practice throughout a Year-Long Professional Development Experience.

Classroom assessment and the use of student performance data to inform instructional decisions have significant potential to help students meet the learning goals of science education. Research has...
Primer reporte para el Ecuador de la avispa endoparasitoide Dinocampus coccinellae (Schrank) (Hymenoptera: Braconidae)

Se reporta por primera vez para el Ecuador, la presencia de Dinocampus coccinellae (Schrank, 1802) (Hymenoptera: Braconidae), avispa endoparasitoide cosmopolita que se especializa en parasitar especies de la familia Coccinellidae. Se identifica como hospedante a Hippodamiaconvergens Guerin-Meneville, 1842 (Coleoptera: Coccinellidae). Ademas, se describen aspectos de su biologia reproductiva, incluida la capacidad que tiene de convertir en “zombi” a sus victimas, situacion que ocurre despues de que la larva del parasitoide abandona el cuerpo del coccinelido, el cual posteriormente se dedica a cuidar el capullo de la avispa hasta que esta emerge como adulta. Este nuevo registro resalta el poco conocimiento que se tiene de la mega diversidad de micro himenopteros en el Ecuador, y de su potencial efecto sobre otros organismos.
A STRONG ALLEE EFFECT AND PARASITOID AGGREGATION IN A DISCRETE HOST–PARASITOID SYSTEM

We study a discrete-time model of host–parasitoid interactions, where the host is subject to a strong Allee effect and the parasitoid is aggregated. The system may have multiple coexisting steady s...
Investigating the Effects of Academic Coaching on College Students’ Metacognition

Academic coaching is an increasingly prevalent form of student support in higher education, although empirical research on the intervention is relatively limited (Robinson, 2015). Academic coaching is intended to advance student learning, well-being, and success in a context external but complementary to the classroom (Richman, Rademacher, & Maitland, 2014; Robinson, 2015). This exploratory study used a randomized control trial design to investigate the effects of academic coaching on college students’ metacognition, a primary component of self-regulated learning. We recruited undergraduates who had not previously participated in academic coaching and randomly assigned them to three groups: in-person academic coaching, online academic coaching, and control. All participants completed a pre- and post-test instrument that included the Metacognitive Awareness Inventory (MAI; Schraw & Dennison, 1994). Results showed that students who received academic coaching had increased metacognition as measured by MAI subscales. Increases in metacognitive awareness occurred in both the in-person and online academic coaching conditions. However, repeated measures ANOVAs did not reveal differences between the three conditions. Overall preliminary results suggest that academic coaching may be a promising student support intervention for helping develop college students’ metacognition outside of the classroom environment.
Applications of topramezone and SpeedZone® for POST goosegrass (Eleusine indica) control in hybrid bermudagrass

Topramezone and carfentrazone + 2,4-D + mecoprop-p + dicamba (SpeedZone®) are herbicides labeled for POST goosegrass (Eleusine indica L. Gaertn.) control in hybrid bermudagrass (Cynodon dactylon × C. transvaalensis Burtt Davy). Field research was conducted in Knoxville, TN, during 2019 and 2020 to evaluate goosegrass control and hybrid bermudagrass tolerance to these herbicides applied alone and in mixture. Treatments included topramezone (12.2 g ha–1), SpeedZone® [carfentrazone (33.6 g ha–1) + 2,4-D (1,029 g ha–1) + mecoprop-p (322 g ha–1) + dicamba (91 g ha–1)] and SpeedZone® + topramezone at 12.2, 6.1, 3.6, or 2.4 g ha–1. A nontreated control was included for comparison. Hybrid bermudagrass tolerance was assessed on four cultivars (‘Northbridge’, ‘Tifway’, ‘Tahoma 31’, and ‘TifTuf’) via visual ratings of turfgrass injury and assessments of normalized difference vegetation index (NDVI). At the termination of the experiment, SpeedZone® alone and in mixture with topramezone controlled goosegrass better than or equal to topramezone alone. Mixtures of SpeedZone® + topramezone reduced injury on all cultivars compared to topramezone alone, particularly when mixtures delivered ≤6.1 g ha–1 topramezone. Injury subsided on all cultivars by 28 d after treatment regardless of herbicide. Findings suggest that SpeedZone® can be mixed with topramezone at the rates tested herein to minimize hybrid bermudagrass injury from topramezone applications for goosegrass control.
The Impact of Cumulative Cochlear Implant Wear Time on Spoken Language Outcomes at Age 3 Years.

Purpose The purpose of this study was to analyze the impact of cumulative hearing hour percentage (HHP) on pediatric cochlear implant users' speech and language development at age 3 years and to de...
Research on the Application of Rigid-flexible Compound Driven Fruit Picking Robot Design in Realizing Fruit Picking

This article mainly designs an efficient fruit picking robot that combines rigidity and flexibility. The design of the robot adopts a mechanical arm with 5 degrees of freedom for the mecanum wheel. The mechanical arm is equipped with a gripper made using artificial muscle technology. The ZED2 binocular vision system is used to obtain spatial coordinates to realize the positioning and positioning of the mechanical arm. Video image acquisition. In order to realize the automatic recognition and picking of strawberries, this paper creates a strawberry training set, and uses the yolov3 algorithm to train the data and obtains a strawberry recognition model, which has a recall rate of larger strawberries and immature strawberries and the precision rate reached 90%, and the detection precision and precision rate of small target strawberries reached more than 80%. It can Meet the requirements of picking in real life.
Detecting the Genetic Signature of Natural Selection in Human Populations: Models, Methods, and Data

Patterns of DNA sequence variation in the genome contain a record of past selective events. The ability to collect increasingly large data sets of polymorphisms has allowed investigators to perform hypothesis-driven studies of candidate genes as well as genome-wide scans for signatures of adaptations. This genetic approach to the study of natural selection has identified many signals consistent with predictions from anthropological studies. Selective pressures related to variation in climate, diet, and pathogen exposure have left strong marks on patterns of human variation. Additional signals of adaptations are observed in genes involved in chemosensory perception and reproduction. Several ongoing projects aim to sequence the complete genome of 1000 individuals from different human populations. These large-scale projects will provide data for more complete genome scans of selection, but more focused studies aimed at testing specific hypotheses will continue to hold an important place in elucidating the history of adaptations in humans.
Detection and Response to an HIV Cluster: People Living Homeless and Using Drugs in Seattle, Washington.

Introduction The HIV epidemic in King County, Washington has traditionally been highly concentrated among men who have sex with men, and incidence has gradually declined over 2 decades. In 2018, King County experienced a geographically concentrated outbreak of HIV among heterosexual people who inject drugs. Methods Data sources to describe the 2018 outbreak and King County's response were partner services interview data, HIV case reports, syringe service program client surveys, hospital data, and data from a rapid needs assessment of homeless individuals and people who inject drugs. In 2020, the authors examined the impact of delays in molecular sequence analyses and cluster member size thresholds, for identifying genetically similar clusters, on the timing of outbreak identification. Results In 2018, the health department identified a North Seattle cluster, growing to 30 people with related HIV infections diagnosed in 2008–2019. In total, 70% of cluster members were female, 77% were people who inject drugs, 87% were homeless, and 27% reported exchanging sex. Intervention activities included a rapid needs assessment, 2,485 HIV screening tests in a jail and other outreach settings, provision of 87,488 clean syringes in the outbreak area, and public communications. A lower cluster size threshold and more rapid receipt and analyses of data would have identified this outbreak 4–16 months earlier. Conclusions This outbreak shows the vulnerability of people who inject drugs to HIV infection, even in areas with robust syringe service programs and declining HIV epidemics. Although molecular HIV surveillance did not identify this outbreak, it may have done so with a lower threshold for defining clusters and more rapid receipt and analyses of HIV genetic sequences.
The Good, the Bad and the Ugly: The story of fast ignition and a path forward

The Fast Ignition (FI) concept for Inertial Confinement Fusion (ICF) [ 1 ] has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy. In FI, compression of the fuel to high density and heating are achieved in separate processes. Similar to conventional ICF, a number of long pulse lasers compress a shell to create a high-density fuel plasma. Subsequently, a high energy (of the order of 100 kJ), high intensity (over 10 20 W/cm 2 ), short (~10 ps) laser pulse drives a beam of high-energy (MeV) particles – electrons or ions – which then heat the compressed fuel plasma to initiate fuel burn-up.
Cross-layer network survivability under multiple cross-layer metrics

Given a cross-layer network with logical and physical topologies, the survivable logical topology routing problem is to route each link in the logical layer with a path in the physical topology between the end nodes of a logical link such that the logical topology remains connected after a physical link fails. The mixed-integer linear programming (MILP) formulation to determine such a routing has been considered in a recent paper. Using this formulation as a basic building block, in this paper we present unified MILP formulations to determine a survivable logical topology routing that also satisfies one of four crosslayer metrics: 1) minimizing the number of logical links to be added to guarantee the existence of survivable logical topology routing, 2) maximizing the capacity of the logical topology, 3) maximizing the connectivity of the logical topology after a physical link failure, and 4) maximizing the minimum cross-layer cut. We also provide heuristics for these problems and compare the performance of these heuristics and MILPs using extensive simulations.
Racial disparities in preterm birth rates and short inter-pregnancy interval: an overview

Objective. We seek to expand on a biopsychosocial framework underlying the etiology of excess preterm birth experienced by African-American women by exploring short inter-pregnancy intervals as a partial explanatory factor. Design. We conducted a qualitative analyses of published studies that met specified criteria for assessing the association of inter-pregnancy interval and preterm birth. Methods. We determine whether inter-pregnancy interval is associated with preterm birth, what the underlying causal mechanism may be, whether African-American women are more likely than Caucasian women to have short intervals, and whether achieving an optimal interval will result in reduced African-American–Caucasian gap in preterm births. Main Outcome Measures. Crude and adjusted odds ratios for preterm birth, with the referent group being the interval closest to the ‘ideal’ of 18–23 months and the exposed group having intervals <12 months or some subset of that inter-pregnancy interval. Results. Inter-pregnancy interval less than six months increases preterm birth by about 40%. The mechanism may be through failure to replenish maternal nutritional stores. While there may not be an interaction between race and short inter-pregnancy interval, short intervals can explain about 4% of the African-American–Caucasian gap in preterm birth because African-American women are approximately 1.8 times as likely to have inter-pregnancy intervals of less than six months. Limited studies indicate that optimal intervals can be achieved through appropriate counseling and health care. Conclusions. Excess risk for preterm birth may be reduced by up to 8% among African-Americans and up to 4% among Caucasians through increasing inter-pregnancy intervals to the optimal length of 18–23 months.
Novel shallow trench isolation process using flowable oxide CVD for sub-100 nm DRAM

We have investigated the characteristics of cell leakage and data retention time when using flowable oxide chemical vapor deposition (CVD) as a shallow trench isolation (STI) process of 1-Gbit DRAM. The trench gap filling capability was increased dramatically by combining high-density plasma (HDP) CVD with flowable oxide CVD. The reduced local stress by flowable oxide in narrow trenches leaded to decrease in junction leakage and gate induced drain leakage (GIDL) current and increase in data retention time of DRAM compared to HDP STI. Therefore, it is concluded that the combination of flowable oxide and HDP oxide is the most promising technology for STI gap filling process of sub-100 nm DRAM technology.
The structure of CDM halos

High resolution N-body simulations show that the density profiles of dark matter halos formed in the standard CDM cosmogony can be fit accurately by scaling a simple ``universal'' profile. Regardless of their mass, halos are nearly isothermal over a large range in radius, but significantly shallower than $r^{-2}$ near the center and steeper than $r^{-2}$ in the outer regions. The characteristic overdensity of a halo correlates strongly with halo mass in a manner consistent with the mass dependence of the epoch of halo formation. Matching the shape of the rotation curves of disk galaxies with this halo structure requires (i) disk mass-to-light ratios to increase systematically with luminosity, (ii) halo circular velocities to be systematically lower than the disk rotation speed, and (iii) that the masses of halos surrounding bright galaxies depend only weakly on galaxy luminosity. This offers an attractive explanation for the puzzling lack of correlation between luminosity and dynamics in observed samples of binary galaxies and of satellite companions of bright spiral galaxies, suggesting that the structure of dark matter halos surrounding bright spirals is similar to that of cold dark matter halos.
The Status of Interactivity in Computer Art: Formal Apories

Contemporary art, particularly that which is produced by computer technologies capable of receiving data input via interactive devices (sensors and controllers), constitutes an emerging expressive medium of interdisciplinary nature, which implies the need for a critical look at its constitution and artistic functions. To consider interactive art as a form of artistic expression that files under the present categorization, implies the acceptance of the participation of the spectator in the production of the work of art, supposedly at the time of its origin / or during its creation. When we examine the significance of the formal status of interactivity, assuming as a theoretical starting point the referred premises and reducing it to a phenomenological point of view of artistic creation, we quickly fall into difficulties of conceptual definitions and structural apories [1]. The fundamental aim of this research is to formally define the status of interactive art, by perpetrating a phenomenological examination on the creative process of this specific art, establishing crucial distinctions in order to develop a hermeneutics in favor of creation of new perspectives and aesthetic frameworks. What is interactive creation? Is interactivity, from the computing artistic creativity point of view, the exponentiation of the concept of the open work of art (ECO 2009)? Does interactive art correspond to an a priori projective and unachievable meta-art? What is the status of the artist and of the spectator in relation to an interactive work of art? What ontic and factical conditions are postulated as necessary in order to determine an artistic product as co-created? What apories do we find along the progres- sive process of reaching to a clarifying conceptual definition?This brief investigation will seek to contribute to the study of this issue, intending ultimately, and above all, to expose pertinent lines of inquiry rather than to provide definite scientific and aesthetic answers.
Molecular cytogenetic analysis of consistent abnormalities at 8q12‐q22 in breast cancer

Studies using comparative genomic hybridization (CGH) indicate that portions of chromosome arm 8q from 8q12 to 8qter are present at an increased relative copy number in a broad range of solid tumors. In this study we define an approximately 1 Mb wide region that appears to be frequently abnormal in copy number or structure in breast cancer cell lines and primary tumors. This was accomplished by fluorescence in situ hybridization (FISH) with yeast artificial chromosomes (YACs) mapped to 8q2-q22. Eleven breast cancer cell lines and ten primary tumors were analyzed. A minimal region of rearrangement was localized to the CEPH-YAC 928F9 in three breast cancer cell lines with unbalanced translocation breakpoints mapping in this region. Unbalanced translocations also were detected in two primary tumors mapping between CEPH-YAC clones 890C4 and 936B3, flanking 928F9. An increased copy number in the minimal region was detected in nine cell lines and in multiple primary tumors. This suggests the possibility that a single gene mapping to 928F9 is involved in breast cancer development or progression and may be deregulated by copy number increases in some tumors and by translocation in others. Four expressed sequence tags were mapped to YAC 928F9 and analyzed for rearrangements by Southern analysis and for abnormal expression by Northern analysis.
Nonpenetrating trauma to the heart.

This study presents a spectrum of injuries to the heart in 61 individuals from 2 months to 30 years of age who were in automobile accidents. Three patients are presented in detail. One patient died and had severe damage to the left ventricular myocardium. Another patient had severe damage to the tricuspid valve and survived after successful implantation of a Starr-Edwards valve. The third patient had a residual calcified plaque at the base of the left ventricle which was detected 30 years after a childhood automobile accident. Electrocardiographic changes compatible with myocardial injury were found in 29.5 per cent, and 19.6 per cent were found to have suspicious changes. Since the advent of open heart surgery, patients who sustain myocardial tears or rupture of cardiac septa are now potentially curable.
Systematics of pure and doped He 4 clusters

Optimized variational calculations have been carried out for pure and doped clusters of $^{4}\mathrm{He}$ atoms up to a cluster size of N=1000 particles. For small cluster sizes with less than or equal to 112 particles, where comparisions with existing diffusion Monte Carlo results are possible, we find excellent agreement for the ground-state energy, correlation, and structure functions. For larger clusters our ground-state energies extrapolate smoothly toward a bulk limit of -7.2 K with a surface energy of 0.272 K A${\mathrm{\r{}}}^{\mathrm{\ensuremath{-}}2}$. The resulting ground-state densities show unmistakable oscillations, confirming our earlier conclusions based on diffusion Monte Carlo studies. The present study of large clusters allows us to bridge the gap between finite systems and the bulk limit. Specifically, we show how the bulk limit of collective energies is reached as well as how the bulk Feynman spectrum is reproduced in the S-wave component of the dynamic structure function in large droplets. By plotting the collective excitation energy of higher multipole modes as a function of an effective wave number k=\ensuremath{\surd}scrl(scrl+1)/R, we show that the resulting spectrum can be directly compared with experimental excitation energies determined for plane liquid surfaces and films. By summing up to scrl=50 partial wave components, we show that the full dynamic structure function simultaneously displays the phonon-roton and the ripplon excitation spectrum. In the case of helium droplets doped with impurities such as rare gas atoms or the ${\mathrm{SF}}_{6}$ molecule, we show that the dipole collective mode becomes unstable with increased droplet size, strongly indicating that these impurities are delocalized inside large droplets. The microscopic character of the instability is revealed in the excitation functions and transition densities of the dipole mode. The introduction of impurities also profoundly alters the dynamic structure function, severely ``fragments'' the Feynman spectrum, and obliterates landmark structures such as the maxon and the roton.
Effects of labeling and number of pretraining exposures on children’s perceptual judgments

The effects of verbal labels used during pretraining on subsequent discrimination were investigated in third and fourth grade children. All stimuli presented to an S were identical. Results supported Miller and Dollard’s hypothesis of acquired equivalence of cues and only minimally supported Gibson and Gibson’s notion that increased practice results in more veridical perception.
Liver-Specific β-Catenin Knockout Mice Exhibit Defective Bile Acid and Cholesterol Homeostasis and Increased Susceptibility to Diet-Induced Steatohepatitis

Although the role of Wnt/β-catenin signaling in liver growth and development is well established, its contribution in non-neoplastic hepatic pathologies has not been investigated. Here, we examine the role of β-catenin in a murine model of diet-induced liver injury. Mice with hepatocyte-specific β-catenin deletion (KO) and littermate controls were fed the steatogenic methionine and choline-deficient (MCD) diet or the corresponding control diet for 2 weeks and characterized for histological, biochemical, and molecular changes. KO mice developed significantly higher steatohepatitis and fibrosis on the MCD diet compared with wild-type mice. Both wild-type and KO livers accumulated triglyceride on the MCD diet but, unexpectedly, higher hepatic cholesterol levels were observed in KO livers on both control and MCD diets. Gene expression analysis showed that hepatic cholesterol accumulation in KO livers was not attributable to increased synthesis or uptake. KO mice had lower expression of bile acid synthetic enzymes but exhibited higher hepatic bile acid and serum bilirubin levels, suggesting defects in bile export. Therefore, loss of β-catenin in the liver leads to defective cholesterol and bile acid metabolism in the liver and increased susceptibility to developing steatohepatitis in the face of metabolic stress.
Experiment and theoretical analysis of relative humidity sensor based on film bulk acoustic-wave resonator

Abstract Relative humidity (RH) was measured with ZnO based film bulk acoustic-wave resonator (FBAR). The resonant frequency of the FBAR decreased linearly in a two-stage manner as the RH increased in the environment. For low RH (RH 50%), a frequency downshift of 8.5 kHz per 1% RH change was obtained. It was demonstrated that the two-stage response of the FBAR can be interpreted using the power law theory for semiconductor gas sensors and the mass loading effect.
31P NMR study of insulin effects on the isolated perfused rabbit urinary bladder.

Insulin stimulates hexose transport, intermediary metabolism, and cell growth and development. These effects are well-documented in skeletal but not smooth muscle. 31P NMR spectroscopy was performed on rabbit urinary bladders (n=4) to characterize insulin's actions on smooth muscle. The bladder and its vasculature were surgically isolated from the animal and perfused with a PSS/red blood cell perfusate. After a control steady state was achieved (approx 1−2 h), insulin (0.100 mU/ml) was added to the perfusate. Relative levels of intracellular phosphorylated compounds, pH, and free Mg2+ were measured and compared to control values. Also, extracellular pH and fractional volume were assessed using phenylphosphonate, a 31P NMR extracellular pH and volume indicator. Insulin induced significant increases in PCr (16 ± 9%) at the expense of Pi, intracellular pH ( Δ 0.24 + 0.07 ), and fractional extracellular volume (49 ± 1%). Intracellular free Mg2+ and extracellular pH did not change. These results indicate that in situ smooth muscle is sensitive to physiological levels of insulin. In fact, insulin improves the energy state of smooth muscle cells and the overall tissue perfusion. © 1989 Academic Press, Inc.
Anodic oxidation of 5,10-dihydro-5,10-dimethylphenazine

The compound 5,10-dihydro-5,10-dimethylphenazine (DMPZ) exhibits two succesive reversible, 1-electron oxidation-reduction steps in acetonitrile and propylene carbonate as solvents. This system has been tested by most of the known diagnostic criteria of electrochemical reversibility and found to adhere to all of them unambiguously. This model system provides a reference for comparison of other multi-stage electrochemical processes. When DMPZ is oxidized in solvents or additives which are strong nucleophiles demethylation accompanies the second stage of oxidation. Since this chemical follow-up reaction occurs in aqueous media it is of significance in the biological redox reactions of N-alkylated phenazines.
Three-dimensional vibration of travelling elastic cables

A cable dynamics theory is derived for travelling cables having arbitrary initial sag and arbitrary support eyelet elevations. The theory incorporates the effect of cable elasticity through a finite strain model. Hamilton's principle provides three non-linear equations which describe the three-dimensional motion of the cable. The equations are linearized about a known equilibrium configuration. Natural frequencies, mode shapes and stability of equilibrium are predicted from the eigensolutions of the discretized model over a range of cable designs. Results of previous elastic cable theories are re-examined and new findings are presented.
Novel dual-lumen ureteral stents provide better ureteral flow than single ureteral stent in ex vivo porcine kidney model of extrinsic ureteral obstruction.

Abstract Objectives In the instance of extrinsic ureteral obstruction, indwelling ureteral stents have a high failure rate. Although technically challenging, simultaneous insertion of two ipsilateral stents can achieve better flow rates with time. A novel dual-lumen stent, composed of two adhered ureteral stents, offers the additional benefit of easier placement than a single guidewire. Using a novel ex vivo porcine model, the flow rates within an extrinsically obstructed renal unit were evaluated using two internal ipsilateral stents and two prototype double-lumen stents. Methods Sixteen renal units were harvested from eight adult Yorkshire female pigs. To quantify flow, the kidneys were infused at a constant pressure, and the corresponding ureteral drainage was measured for a defined interval. The flow was measured with a standard 7F double-pigtail stent, two ipsilateral 7F double-pigtail stents, a 7F novel double-lumen stent designed with both distal lumens open, and a 7F novel double-lumen stent with one distal lumen closed. The intraluminal and extraluminal flow in obstructed and nonobstructed systems was measured. Results The two ipsilateral standard stents or prototype double stents achieved better flow down the ureter than did one standard stent (P Conclusions Novel dual-lumen prototype ureteral stents provided better flow than a single stent in extrinsically obstructed ureters with the proposed added benefit of easier retrograde insertion compared with a single guidewire.
Effect of block size on image quality for compressed chest radiographs

Data compression can improve imaging system efficiency by reducing the required storage space and the image transmission time. Transform compression methods have been applied to digital radiographs with good results. Block transform compression is usually based on 8 X 8 or 16 X 16 transform blocks for the sake of simplicity and speed. Compression with these small sizes tends to require accurate coefficient representations to prevent blocking artifacts. Weighted quantization of block transform coefficients can reduce the blocking effects and improve compression performance. Full frame compression has the advantage of eliminating blocking effects but the disadvantage of heavy demand for computing resources. Small block compression can retain local variation better and has a simpler and faster implementation. We have evaluated the performance tradeoffs for different block sizes and their effects on the image quality of chest radiographs. The results showed that there is no significant difference in root-mean-square error nor in power spectra between different block sizes for visually lossless compression (at about 10:1 compression ratio).
Technological Trends and the Organization of Migrant Farm Workers

Several characteristics of the agricultural system in the Eastern United States have long obstructed successful union organization among farm workers despite considerable effort and the exploitative preconditions that have led to organization in other sectors of the labor force. Technological trends in agriculture, however, have begun to affect the structure of the labor force, creating the stability, stratification, and expectations conducive to organization. The conjunction of these factors with the availability of the Chavez model bear on the potential success of continued organizational efforts; for Chavez' approach, combining community organization, union organization, and use of the boycott, is particularly appropriate for groups with little trust or experience in the efficacy of organization.
Growth of Bi-Ca-Sr-Cu-O epitaxial layer by liquid phase epitaxial process

Abstract Bi-Ca-Sr-Cu-O epitaxial layers have been successfully grown on (001) MgO substrate by liquid phase epitaxial (LPE) technique. These superconducting films showed zero resistivity around 80 K. X-ray diffraction and differential thermal analysis results showed that the phase and composition of the grown epitaxial layer deviated from the starting nominal composition of Bi : Ca : Sr : Cu =4:3:3:4.
Rubric-Referenced Self-Assessment and Self-Efficacy for Writing

The authors investigated the relation between long- and short-term rubric use (including self-assessment), gender, and self-efficacy for writing by elementary and middle school students (N = 268). They measured long-term rubric use with a questionnaire. They manipulated short-term rubric use by a treatment that involved reviewing a model and using a rubric to self-assess drafts. The authors collected selfefficacy ratings 3 times. Results revealed that girls' self-efficacy was higher than boys' self-efficacy before they began writing. The authors found interactions between gender and rubric use: Average self-efficacy ratings increased as students wrote, regardless of condition, but the increase in the self-efficacy of girls in the treatment group was larger than that for girls in the comparison group, and long-term rubric use associated only with the self-efficacy of girls.
Computer-assisted optimization in high-performance liquid chromatographic method development

Abstract Computer-assisted optimization in high-performance liquid chromatography has been encouraged by a need to define method development strategies for automated chromatographic instruments. Several algorthms have been developed for the optimization of various aspects of chromatographic performance. Additional experimental designs have been used to understand the influence of factors on the performance of the chromatographic system.
Percutaneous nephrostomy and maintenance of nephrostomy drainage

A simple method for percutaneous insertion of nephrostomy tubes is described. In our series of 47 patients there have been no failed attempts at nephrostomy placement, and only one complication, transient septicemia, was noted. Catheter care is described, and use of the nephrostomy tract for various urologic problems is discussed.
Temperature dependence of 27Al NMR in YAlO3

Abstract The nuclear quadrupole tensor for 27Al in yttrium ortho-aluminate has been measured between 30°C and −150°C. The coupling constant e 2 qQ h varies linearly from 1.44 to 1.56 MHz over this range, whereas the asymmetry parameter η drops rapidly from 0.748 toward an asymptotic value of 0.663.
The radiosensitivity of rat bone-marrow cells

SummaryThe radiosensitivity of rat bone-marrow cells was determined by the spleen-colony technique. When the marrow cells were irradiated in vivo, the D0 was 97 rads, and the extrapolation number was 5·2. Similar results were obtained after in vitro irradiation: D0 = 94 rads, and extrapolation number = 4·1. Some observations are also reported on the proliferative capability of irradiated bone-marrow and spleen-colony cells injected into heavily irradiated recipient rats.
Strategic timing in group negotiations : The implications of forced entry and forced exit for negotiators with unequal power

This study used a three-person mixed-motive negotiation to (1) investigate the effects of asymmetrical caucusing (i.e., negotiations in which parties possess unequal opportunities to engage in discussion) on group negotiations and (2) assess potential explanations for these effects. Negotiators who were excluded from part of the discussion received a smaller share of rewards than those who remained throughout the discussion, and those who were excluded from the latter half of the discussion received a smaller share of rewards than those who were excluded from the beginning. In addition, groups that excluded the low power negotiator from part of the discussion achieved less integrative agreements than groups that excluded the high power negotiator and groups that retained all negotiators throughout the discussion. The results highlight the importance of negotiator participation for gaining a share of rewards and the critical role played by negotiators with low power for determining the quality of agreements reached.
Assessing Systems Quality in a Changing Health Care Environment: The 2009–10 National Survey of Children with Special Health Care Needs

To provide a national, population-based assessment of the quality of the health care system for children and youth with special health care needs using a framework of six health care system quality indicators. 49,242 interviews with parents of children with special health care needs from the 2009–10 National Survey of Children with Special Health Care Needs (NS-CSHCN) were examined to determine the extent to which CSHCN had access to six quality indicators of a well-functioning system of services. Criteria for determining access to each indicator were established and applied to the survey data to estimate the proportion of CSHCN meeting each quality indicator by socio-demographic status and functional limitations. 17.6 % of CSHCN received care consistent with all six quality indicators. Results for each component of the system quality framework ranged from a high of 70.3 % of parents reporting that they shared decision-making with healthcare providers to a low of 40 % of parents reporting receipt of services needed for transition to adult health care. Attainment rates were lower for CSHCN of minority racial and ethnic groups, those residing in households where English was not the primary language, those in lower income households, and those most impacted by their health condition. Only a small proportion of CSHCN receive all identified attributes of a high-quality system of services. Moreover, significant disparities exist whereby those most impacted by their conditions and those in traditionally disadvantaged groups are served least well by the current system. A small proportion of CSHCN appear to remain essentially outside of the system, having met few if any of the elements studied.
Measurements Of Optical And Noise Properties Of Screen-Film Systems In Radiography

The optical and noise properties of radiographic screen-film systems have often been evaluated by concepts and techniques related to Fourier analysis. Figure 1 illustrates the physical characteristics of these properties. The point spread function (PSF), which is the two dimensional representation of the optical property of the screen-film system, has not been applied experimentally for evaluation. The screen-film system is generally considered to be isoplanatic and isotropic; therefore, the line spread function (LSF) in an arbitrary direction can be used. This function is much simpler to measure than the PSF. In the spatial frequency domain, the optical property is evaluated by the modulation transfer function (MTF), which is the absolute value of the Fourier transform of the LSF. Other optical characteristics such as the edge response are usually related to the LSF or the MTF.© (1974) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
B-doped Si(001)2 × 1 gas-source molecular-beam epitaxy from Si2H6 and B2H6

Abstract The growth rates R Si , of Si films deposited on Si(001)2 × 1 from Si 2 H 6 by gas-source molecular-beam epitaxy (GS-MBE) were determined as a function of temperature T s (500–950 °C) and impingement flux J Si 2 H 6 (0.3–7.7 × 10 16 cm −2 s −1 ). R Si (T s , J Si 2 H 6 ) curves were well described using a model, with no fitting parameters, based upon dissociative Si 2 H 6 chemisorption followed by a series of surface decomposition reactions with the ratelimiting step being first-order hydrogen desorption from Si monohydride. The zero-coverage Si 2 H 6 reactive sticking probability in the impingement-flux-limited growth regime was found to be 0.036. B doping concentrations (C B = 5 × 10 16 − 5 × 10 19 cm −3 ) from B 2 H 6 increased linearly with increasing flux ratio J B 2 H 6 /J Si 2 H 6 at constant T s and decreased exponentially with 1/T s at constant J B 2 H 6 /J Si 2 H 6 . The B 2 H 6 reactive sticking probability ranged from ≅ 6.4 × 10 −4 at T s = 600 °C to 1.4 × 10 −3 at 950 °C. Secondary ion mass spectrometry analyses of modulation-doped samples revealed sharp profiles with no detectable B segregation. Hole mobilities in uniformly-doped samples were equal to bulk values.
Effects of light on shoot geometry and needle morphology in Abies amabilis

In some conifers, shoot geometry and needle morphology vary significantly in response to the light conditions under which they develop. We measured shoot length, silhouette area, total projected needle area, total needle weight and needle thickness on current shoots developed under a wide range of light conditions in a 36-year-old Abies amabilis (Dougl.) Forbes stand. Current light was quantified by evaluating percent openness from hemispherical photographs taken before the growing season. Unweighted total openness was correlated with shoot geometry and needle morphology better than any weighted indices tested. Needle thickness and leaf mass/area were both closely correlated with total openness (R(2) = 0.86 and 0.82, respectively). The most exposed needles were 2.5 times thicker and had 3-4 times more leaf mass/area than the most shaded needles. Total projected leaf area/shoot silhouette area was also correlated with openness (R(2) = 0.74) and was about twice as high in sun shoots as in shaded shoots. As a result of greater leaf mass/leaf area and greater leaf area/shoot silhouette area, a unit of intercepted light was dispersed over about 6 times as much leaf mass in a sun shoot as in a shade shoot, which presumably permits more efficient utilization of the intercepted light under high illumination with less energy wastage to light saturation. Moreover, leaf mass per unit of silhouette area was almost exactly proportional to canopy openness, as predicted by resource optimization theory if nitrogen concentration and photosynthetic capacity per unit mass are constant in new leaves. The close correlation of needle thickness and leaf mass/area with openness suggests that either parameter could be used as an index of the distribution of light or light-driven processes in an A. amabilis canopy.
Erythropoietin signaling promotes transplanted progenitor cell survival

We examine the potential for erythropoietin signaling to promote donor cell survival in a model of myoblast transplantation. Expression of a truncated erythropoietin receptor in hematopoietic stem cells has been shown to promote selective engraftment in mice. We previously demonstrated expression of endogenous erythropoietin receptor on murine myoblasts, and erythropoietin treatment can stimulate myoblast proliferation and delay differentiation. Here, we report that enhanced erythropoietin receptor expression, as well as exogenous erythropoietin treatment in myoblasts, provided a survival advantage and protection against apoptosis under serum-starvation conditions. When cultured in differentiation medium, expression of the myogenic regulatory proteins shifted toward early differentiation with increased erythropoietin receptor. Expression of early myogenic differentiation proteins Myf-5 and MyoD increased, while later stage protein myogenin decreased. Transplantation of C2C12 myoblasts overexpressing truncated erythropoietin receptor showed more transplanted cell incorporation into muscle fibers in muscular dystrophy mdx mice. These cells also restored dystrophin protein expression in mdx mice at 6 wk after cell treatment that was further increased with exogenous erythropoietin administration. In summary, enhanced erythropoietin receptor expression promotes transplanted cell survival in a mouse model for myoblast transplantation and provides dystrophin expression in mice with muscular dystrophy.—Jia, Y., Warin, R., Yu, X., Epstein, R., Noguchi, C. T. Erythropoietin signaling promotes transplanted progenitor cell survival.
Three-Dimensional Structure and Turbulence Within the Tip Leakage Vortex of an Axial Waterjet Pump

The flow structure and dynamics of turbulence are investigated by means of three-dimensional stereo particle image velocimetry (Stereo-PIV) measurements within the tip leakage vortex (TLV) of an axial waterjet pump rotor. Both the blades and casing of the pump are transparent and their optical refractive indices are matched with that of the pumped fluid, providing unobstructed optical access to the sample area without image distortion. Data are acquired on selected meridional planes in the rotor passage as well as in three-dimensional domains obtained by stacking closely-spaced planes situated within the rotor passage. Presented data have been sampled in one of these 3D regions, at 67% of the blade tip chordlength. All components of velocity and vorticity are calculated, together with the whole strain-rate and Reynolds stress tensors. The entire set of contributors to the turbulence production-rate is also available. The TLV and associated flow structures are completely 3D and change significantly along the blade tip chordwise direction. The vortex originates from the rollup of a multi-layered tip leakage flow, and propagates within the rotor passage towards the neighboring blade. Because of layered backflow rollup, vorticity entrained in the TLV is convected along different paths and re-oriented several times within the vortex. As a result, the TLV consists of a core surrounded by a tube of three-dimensional vorticity that wraps around it helically. Propagation of tip leakage backflow into the passage and subsequent TLV rollup also cause flow separation at the casing endwall with ejection of boundary layer vorticity that is finally entrained into the outer perimeter of the TLV. This complex TLV flow dominates the tip region of the rotor and involves non-uniform distributions of strain-rate and Reynolds stresses resulting in well-defined peaks of turbulence production-rate. For instance, turbulence is produced locally both at the flow contraction point near the region of aforementioned endwall separation and in the shear layer that connects the vortex with the suction side corner of the blade tip. The spatial inhomogeneity of turbulent kinetic energy (TKE) distribution within the TLV, and the mismatch between locations of TKE and production-rate peaks can be explained by analyzing the 3D mean flow advection of turbulence, for example from the region of endwall boundary layer separation towards the outer region of the TLV. In addition to being spatially non-uniform, turbulence is also anisotropic in both the shear layer and periphery of the TLV. Conversely, turbulence is intense and relatively isotropic near the TLV core, as well as monotonically increasing along the vortex centerline. This trend cannot be described solely in terms of local production of turbulence; it must also involve slow turbulence dissipation associated with the meandering of relatively large-size, interlaced vortex filaments in the TLV core region.Copyright © 2011 by ASME
Estradiol reduces seizure-induced hippocampal injury in ovariectomized female but not in male rats

Abstract Estrogens protect ovariectomized rats from hippocampal injury induced by kainic acid-induced status epilepticus (SE). We compared the effects of 17β-estradiol in adult male and ovariectomized female rats subjected to lithium-pilocarpine-induced SE. Rats received subcutaneous injections of 17β-estradiol (2 μg/rat) or oil once daily for four consecutive days. SE was induced 20 h following the second injection and terminated 3 h later. The extent of silver-stained CA3 and CA1 hippocampal neurons was evaluated 2 days after SE. 17β-Estradiol did not alter the onset of first clonus in ovariectomized rats but accelerated it in males. 17β-Estradiol reduced the argyrophilic neurons in the CA1 and CA3-C sectors of ovariectomized rats. In males, estradiol increased the total damage score. These findings suggest that the effects of estradiol on seizure threshold and damage may be altered by sex-related differences in the hormonal environment.