Role of the pituitary-adrenal hormones in the acquisition of schedule-induced polydipsia.

Adrenalectomized female rats failed to develop schedule-induced polydipsia (SIP). Dexamethasone (DEX) injections failed to reinstate SIP in adrenalectomized rats. They did not prevent intact rats from acquiring SIP but interfered with subsequent expression of this behavior. In contrast, corticosterone, the rats' normally occurring glucocorticoid, fully restored the acquisition and subsequent expression of SIP in adrenalectomized rats. This strongly suggests that corticosterone plays an essential role in the normal acquisition and development of this behavior. Data are interpreted in the context of current information concerning adrenal hormone receptors. It is hypothesized that SIP acquisition is at least partly regulated by the Type I (mineralocorticoid) receptor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bandwidth selection for a class of difference-based variance estimators in the nonparametric regression: A possible approach

A possible approach to bandwidth selection for difference-based variance estimators in the nonparametric regression is proposed. The approach is based on the crossvalidation-type idea modified for the case of correlated data. The method is compared to an alternative plug-in style method. Difficulties in implementing the latter are highlighted and it is argued that the proposed method represents a better alternative. Simulations for several models are given that illustrate good practical performance of the proposed method.     

Calibration enhancement and on line accuracy assessment for singlesix-port reflectometers employing a nonlinear Kalman filter

The calibration and measurement performance of a single six-port reflectometer is directly affected by the presence of random errors. A technique using a nonlinear Kalman filter that enhances calibration by a factor of two to ten is presented. The technique also provides statistical information, allowing simple online accuracy assessment. The technique is readily extended for use within dual six-port reflectometer systems     

RECIST Applied to Realistic Tumor Models

RECIST (Response Evaluation Criteria in Solid Tumors) is a linear measure intended to predict tumor size in medical computed tomography (CT). In this work, using purely geometrical considerations, we estimate how well RECIST can predict the volume of randomly-oriented tumor models, each composed of the union of ellipsoids. The principal conclusion is that RECIST is likely to work less well for realistic tumors than for ellipsoids.     

Mental space travel: Damage to posterior parietal cortex prevents egocentric navigation and reexperiencing of remote spatial memories.

The ability to navigate in a familiar environment depends on both an intact mental representation of allocentric spatial information and the integrity of systems supporting complementary egocentric representations. Although the hippocampus has been implicated in learning new allocentric spatial information, converging evidence suggests that the posterior parietal cortex (PPC) might support egocentric representations. To date, however, few studies have examined long-standing egocentric representations of environments learned long ago. Here we tested 7 patients with focal lesions in PPC and 12 normal controls in remote spatial memory tasks, including 2 tasks reportedly reliant on allocentric representations (distance and proximity judgments) and 2 tasks reportedly reliant on egocentric representations (landmark sequencing and route navigation; see Rosenbaum, Ziegler, Winocur, Grady, & Moscovitch, 2004). Patients were unimpaired in distance and proximity judgments. In contrast, they all failed in route navigation, and left-lesioned patients also showed marginally impaired performance in landmark sequencing. Patients' subjective experience associated with navigation was impoverished and disembodied compared with that of the controls. These results suggest that PPC is crucial for accessing remote spatial memories within an egocentric reference frame that enables both navigation and reexperiencing. Additionally, PPC was found to be necessary to implement specific aspects of allocentric navigation with high demands on spontaneous retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On fault-tolerant observers

The problem of designing asymptotic observers for multioutput systems with one unreliable output measurement is addressed. It is shown that observers designed on the basis of observability indexes are not fault tolerant, and an observer for linear systems which tolerates failures in one a priori known output is given. The results are extended to nonlinear systems with no inputs: it is pointed out that the proposed design procedure may enlarge the class of nonlinear systems for which a nonlinear observer can be obtained     

Detection of movement-related patterns in ongoing single-channel electrocorticogram

Adaptive autoregressive parameters and a linear classifier were used to detect movement related desynchronization and synchronization patterns in single-channel electrocorticogram (ECoG) obtained from implanted electrode grids. The best classification accuracies found had more than 90% hits and less than 10% false positives. The findings show that the detection of event-related desynchronization and synchronization in ECoG data can be used to reliably provide switch control directly by the brain and is therefore very suitable as the basis of a direct brain interface.     

Erythema migrans-like rash illness at a camp in North Carolina: a new tick-borne disease?

BACKGROUND: Borrelia burgdorferi, the causative agent of Lyme disease, has never been isolated from a patient thought to have acquired Lyme disease in any southeastern state. OBJECTIVE: To investigate 14 cases of an erythema migrans (EM)-like rash illness that occurred during 2 summers at an outdoor camp in central North Carolina in an effort to determine the etiologic, epidemiological, and clinical aspects of this illness. METHODS: Using active surveillance, we identified cases of clinically diagnosed EM in residents and staff of the camp. We collected clinical and demographic information; history of exposure to ticks; acute and convalescent serum antibodies to B. burgdorferi, Rickettsia rickettsii, and Ehrlichia chaffeensis; and cultures for spirochetes from biopsy specimens of skin lesions. Serum samples from a group of residents and staff who did not develop rashes were tested for the same antibodies. We speciated ticks removed from people and collected from vegetation. RESULTS: We identified 14 cases of EM-like rash illness during the 2 summers. Of the 14 case-patients, 10 had associated mild systemic symptoms and 1 had documented fever. All 14 case-patients had removed attached ticks, and 8 remembered having removed a tick from the site where the rash developed a median of 12 days earlier (range, 2-21 days). One tick removed from the site where a rash later developed was identified as Amblyomma americanum, the Lone Star tick; 97% of ticks collected from vegetation and 95% of ticks removed from people were A. americanum. No spirochetes were isolated from skin biopsy specimens. Paired serum samples from 13 case-patients did not show diagnostic antibody responses to B. burgdorferi or other tick-borne pathogens. CONCLUSIONS: This investigation suggests the existence of a new tick-associated rash illness. We suspect that the disease agent is carried by A. americanum ticks. In the southern United States, EM-like rash illness should no longer be considered definitive evidence of early Lyme disease.