The Relative Effects of Immediate and Delayed Reinforcement on a Programed Learning Task

It was the purpose of this study (1) to compare the effects of immediate knowledge of results and delayed knowledge of results on a programed task to determine which, if either, would result in superior learning; and (2) to explore the effect of these two variables on the amount of retention of learning over time

Slope measurement from contour maps

Estimating slope gradients from digitized contour ma

Transport phenomenology for a holon-spinon fluid

We propose that the normal-state transport in the cuprate superconductors can be understood in terms of a two-fluid model of spinons and holons. In our scenario, the resistivity is determined by the properties of the holons while magnetotransport involves the recombination of holons and spinons to form physical electrons. Our model implies that the Hall transport time is a measure of the electron lifetime, which is shorter than the longitudinal transport time. This agrees with our analysis of the normal-state data. We predict a strong increase in linewidth with increasing temperature in photoemission. Our model also suggests that the AC Hall effect is controlled by the transport time.Comment: 4 pages, 1 postscript figure. Uses RevTeX, epsf, multico

Amplified Sensitivity of Nitrogen-Vacancy Spins in Nanodiamonds using All-Optical Charge Readout

Nanodiamonds containing nitrogen-vacancy (NV) centers offer a versatile platform for sensing applications spanning from nanomagnetism to in-vivo monitoring of cellular processes. In many cases, however, weak optical signals and poor contrast demand long acquisition times that prevent the measurement of environmental dynamics. Here, we demonstrate the ability to perform fast, high-contrast optical measurements of charge distributions in ensembles of NV centers in nanodiamonds and use the technique to improve the spin readout signal-to-noise ratio through spin-to-charge conversion. A study of 38 nanodiamonds, each hosting 10-15 NV centers with an average diameter of 40 nm, uncovers complex, multiple-timescale dynamics due to radiative and non-radiative ionization and recombination processes. Nonetheless, the nanodiamonds universally exhibit charge-dependent photoluminescence contrasts and the potential for enhanced spin readout using spin-to-charge conversion. We use the technique to speed up a $T_1$ relaxometry measurement by a factor of five.Comment: 13 pages, 14 figure

Time perspective, depression, and substance misuse among the homeless

Using the Zimbardo Time Perspective Inventory (ZTPI; P. G. Zimbardo & J. N. Boyd, 1999), the authors found that homeless people, in comparison with a control group, had a significantly more negative outlook concerning their past and present as evinced by high Past-Negative and Present-Fatalistic scores and low Past-Positive scores on the ZTPI. However, the homeless individuals were almost indistinguishable from control participants on measures of Present-Hedonism and Future thinking. The homeless individuals had significantly higher levels of depression, with 31 out of 50 (62%) reaching criteria for probable depression. However, this finding was unrelated to their atypical time perspective. There was no significant relation between substance misuse and time perspective. Despite their current difficulties, including depression and drug abuse, the homeless individuals maintained a propensity toward future thinking characterized by striving to achieve their goals.

Remote Sensing Analysis and Implications for Groundwater Resources in the Kharga Basin, Egypt

Identifying new groundwater resources in Africa is important because climate change may cause the Nile recharge to decrease by the end of the century, affecting water stability in the eleven countries that rely on this river as a water source. Further exacerbating the demand for water in Egypt in particular is a growing population that already lives on a small per capita amount of water. I report results from drainage analysis using a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) that corroborate evidence suggesting that the Kharga Basin in Egypt's Western Desert is a closed basin that could have held water in the past. Combined with evidence from other studies, this suggests water from Pleistocene humid periods still resides within the Kharga Basin. Fractures possibly facilitate the vertical movement of this groundwater, consistent with vegetation and tufa deposits following fractures in the basin. Thermal inertia analysis, due to its relation to soil moisture, may help locate areas of relatively shallow groundwater, possibly due to the vertical movement of water along fractures. I report results from remote sensing analysis of optical and thermal images (Moderate Resolution Imaging Spectroradiometer, MODIS) used to create thermal inertia images. Furthermore, I report results from remote sensing analysis of optical (Landsat Operational Land Imager) and radar (Radarsat-1) images and DEMs (SRTM and Advanced Spaceborne Thermal Emission and Reflection Radiometer, ASTER) on the fracture intensity and kinematics in the Kharga Basin. The thermal inertia and fracture density maps were combined with previously published hydraulic conductivity and aquifer thickness maps to perform multi-map analysis and determine the best locations for future water wells. The results suggest the southern end of the major north-south fault is the most conducive to shallow groundwater drilling. For all results, I performed digital image processing and spatial analysis using ENVI and ArcMap.Geolog

Tendinosis develops from age- and oxygen tension-dependent modulation of Rac1 activity.

Age-related tendon degeneration (tendinosis) is characterized by a phenotypic change in which tenocytes display characteristics of fibrochondrocytes and mineralized fibrochondrocytes. As tendon degeneration has been noted in vivo in areas of decreased tendon vascularity, we hypothesized that hypoxia is responsible for the development of the tendinosis phenotype, and that these effects are more pronounced in aged tenocytes. Hypoxic (1% O2 ) culture of aged, tendinotic, and young human tenocytes resulted in a mineralized fibrochondrocyte phenotype in aged tenocytes, and a fibrochondrocyte phenotype in young and tendinotic tenocytes. Investigation of the molecular mechanism responsible for this phenotype change revealed that the fibrochondrocyte phenotype in aged tenocytes occurs with decreased Rac1 activity in response to hypoxia. In young hypoxic tenocytes, however, the fibrochondrocyte phenotype occurs with concomitant decreased Rac1 activity coupled with increased RhoA activity. Using pharmacologic and adenoviral manipulation, we confirmed that these hypoxic effects on the tenocyte phenotype are linked directly to the activity of RhoA/Rac1 GTPase in in vitro human cell culture and tendon explants. These results demonstrate that hypoxia drives tenocyte phenotypic changes, and provide a molecular insight into the development of human tendinosis that occurs with aging

Comparison of Salivary and Serum Levels of Soluble Toll-Like Receptor 3 (TLR3) in Patients with Sjögren's Syndrome (SS) Compared to Age- and Sex-Matched Controls

This cross-sectional study examined potential differences in concentration of Toll-like receptor 3 (TLR3) in serum and citric acid-stimulated saliva from patients with Sjögren’s Syndrome (SS) and healthy age-, sex-, and periodontal disease- matched control patients. Salivation was stimulated with 5 ml of 2% citric acid, and whole saliva samples were collected. Full-mouth clinical periodontal measurements were recorded from 21 SS patients and 22 unaffected control patients. Saliva and plasma TLR3 concentrations were determined by enzyme-linked immunosorbentassays (ELISA). Data were tested statistically as appropriate to the data distribution. No significant difference in clinical periodontal measurements, or serum or salivary TLR3 concentrations was evident between groups. Salivary flow rates were significantly lower (p<0.001) whereas plaque % were significantly higher (p=0.048) in SS patients. SS patients expressed on average 0.183 and 0.219 ng/ml TLR in saliva and serum, respectively, while healthy control patients expressed on average 0.299 and 0.188 ng/ml TLR in saliva and serum, respectively. These differences were not significantly different (p<0.05). This is the first detection of TLR3 in human serum or saliva as quantified or qualified by ELISA. The present findings do not support a hypothesis that a hyperinflammatory systemic state, as seen in SS patients, can independently raise serum or saliva TLR3 concentration in the absence of periodontal disease in treated SS patients

Ultrasonic Evaluation in the Management of Postpartum Infection

To evaluate the effectiveness of ultrasound in the management of postpartum problems, ultrasonographic examination was performed on 98 patients with suspected postpartum infection. The study includes only those patients who did not respond to antibiotic treatment for at least 48 hours and those patients who were readmitted to the hospital with suspected postpartum infection. Echogenic tissue was found in the uterine cavity in 12 patients, and significant fluid collection was found in 24 patients. Gas collection appeared in the uterine cavity in five patients and around the uterine incision in four patients. Fluid collection was found around the uterine incision in five patients, and abscess formation under the abdominal incision was found in 11 patients. Although ultrasound was nondiagnostic in 31 of the 98 patients, information obtained by ultrasound could be used to reduce the duration of the infectious morbidity