We recently reported on the radio-frequency attenuation length of cold polar ice at Summit Station, Greenland, based on bi-static radar measurements of radio-frequency bedrock echo strengths taken during the summer of 2021. Those data also allow studies of (a) the relative contributions of coherent (such as discrete internal conducting layers with sub-centimeter transverse scale) vs incoherent (e.g. bulk volumetric) scattering, (b) the magnitude of internal layer reflection coefficients, (c) limits on signal propagation velocity asymmetries (‘birefringence’) and (d) limits on signal dispersion in-ice over a bandwidth of ~100 MHz. We find that (1) attenuation lengths approach 1 km in our band, (2) after averaging 10 000 echo triggers, reflected signals observable over the thermal floor (to depths of ~1500 m) are consistent with being entirely coherent, (3) internal layer reflectivities are ≈–60$\to$–70 dB, (4) birefringent effects for vertically propagating signals are smaller by an order of magnitude relative to South Pole and (5) within our experimental limits, glacial ice is non-dispersive over the frequency band relevant for neutrino detection experiments.

Objective: The Laboratory Response Network (LRN) is the United States’ laboratory system for detecting, confirming, and reporting potential bioterrorism agents. The first tier—sentinel laboratories—is composed principally of hospital-based laboratories and is tasked with ruling out potential biological threat agents in clinical specimens or the identification of suspicious specimens for further testing in higher tiers of the LRN system. The aim of the present study was to broadly describe preparedness of the first tier of the hospital LRN, the sentinel laboratories, with a specific focus on training, personnel, and communications.

Methods: A semistructured cross-sectional survey of US sentinel laboratories was designed and conducted. Hospitals with greater than 250 beds and an emergency department were considered eligible for inclusion. A geographically weighted sample of 201 hospitals was selected for inclusion. The survey was administered by telephone to the microbiology managers (or designees) at the selected hospitals. The survey contained questions related to drill frequency, proficiency survey participation, personnel training, personnel responsibilities, procedures for biological threat response, and overall confidence in preparedness.

Results: Overall, 179 hospitals (89.1%) identified themselves as sentinel laboratories and participated in the survey; 11.7% reported that they had had an emergency alert within the last 2 years. Although rates of internal drills were low (20.7%), participation in some form of bioterrorism proficiency evaluation was high (79.9%). In all, 83.8% of laboratories reported that they had personnel designated to coordinate response to acts of bioterrorism. More than 73% of respondents indicated that they had sufficient personnel, equipment, and training to respond to a biological terrorism event. By multivariate analysis, sentinel laboratories were 3.4 times more likely to feel confident that they had sufficient personnel, equipment, and training to respond to a biological terrorism event if they had designated personnel for bioterrorism roles.

Conclusions: This pilot study of sentinel laboratory bioterrorism preparedness demonstrated that hospital laboratory personnel, training, and communication preparedness were not universal, despite designation as sentinel laboratories. A need for unified monitoring of sentinel laboratories exists, and efforts should be made to develop standardized metrics for sentinel laboratory preparedness. (Disaster Med Public Health Preparedness. 2009;3(Suppl 1):S17–S23)

Subtypes of working memory performance were examined in a cohort of 50 HIV-infected adults and 23 uninfected controls using an n-back paradigm (2-back) in which alphabetic stimuli were quasi-randomly presented to a quadrant of a computer monitor. In the verbal working memory condition, participants determined whether each successive letter matched the letter that appeared two previously in the series, regardless of spatial location. In the spatial working memory condition, participants determined whether each letter matched the spatial location of the letter that had appeared two previously, regardless of letter identity. The dependent variable was percent accuracy in each condition. Results of mixed model ANOVA revealed that the HIV-infected participants performed significantly worse than controls on both the verbal and spatial working memory tasks. A significant main effect for working memory condition was also present with both participant groups performing better on the spatial working memory task. These results, the first study of HIV-infected adults to directly compare verbal versus spatial working memory performance using the identical test stimuli across task conditions, suggests that HIV infection is associated with a decrement in working memory efficiency that is equally apparent for both verbal and spatial processing. These findings implicate central executive dysfunction as a likely substrate and provide the basis for hypothesizing that decline in working memory may contribute to other HIV-associated neuropsychological deficits. (JINS, 2002, 8, 532–538.)

This study aimed to explore the limitations of the Ashworth scale for measuring spasticity. An isokinetic dynamometer to quantify resistance to passive stretch and surface EMG was used to verify if a stretch response occurred and, if so, at what joint angle. The authors sought to determine which components of passive resistance (magnitude, rate of change, onset angle of stretch, or velocity dependence) were most related to Ashworth scores and which were related to motor function in cerebral palsy (CP). Twenty-two individuals with spastic CP (11 males, 11 females; mean age 11.9 years, SD 4.3) and a comparison group of nine children without CP (four males, five females; mean age 11.3 years, SD 2.5)participated in the study. The group with CP included those with a diagnosis of spastic diplegia, hemiplegia, or quadriplegia, distributed across Gross Motor Functional Classification Levels. Procedures included: (1) clinical assessment at the knee joint, (2) functional assessments, and (3) isokinetic assessment of passive resistance torque in hamstrings and quadriceps at three velocities. EMG data were recorded simultaneously to identify stretch responses. Detecting stretch responses using the Ashworth scale compared with instrumented measures showed near complete agreement at extremes of the scale, with marked inconsistencies in mid-range values. Ashworth scores were correlated with instrumented measures, particularly for the quadriceps, with higher correlations to the rate of change in resistance (stiffness) and onset angle of stretch than to peak resistance torque. Those with greater resistance tended to have poorer function with isokinetic relations typically stronger.

While language facility was once considered to be the sole province of the “dominant” left hemisphere, clinical and experimental findings suggest the right hemisphere plays an equally important role in many language tasks. To elucidate differential hemispheric language processes, Right Hemisphere Language Battery and Western Aphasia Battery data from left (LHD) and right (RHD) hemisphere cerebral vascular accident (CVA) patients and controls were subjected to multivariate discriminant analysis. The highly significant group differences and overall 95% classification rate obtained confirms the utility of the dependent measures in differential diagnosis. Results suggest CVA patients experience disparate language deficits, with the LHD group experiencing concordant-convergent language deficits and the RHD group displaying discordant–divergent deficits that interfere with the receptive and expressive language skills necessary for successful social discourse. (JINS, 2001, 7, 655–664.)