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Biomedical subjects

David Hoffman

Publications and source records attributed to David Hoffman.

5 recordsLinked to original sources

Nursing home involuntary relocation: clinical outcomes and perceptions of residents and families.

OBJECTIVES: To examine the physical and mental health characteristics of 120 residents 3 months following their discharge from 1 transferring nursing home to 23 facilities, to compare these characteristics to their pre-transfer status, and to describe resident and family perceptions of the transfer. DESIGN: Secondary analysis of a longitudinal, prospective quasi-experimental intervention and a qualitative description of resident and family views. SETTING: The setting was 23 nursing homes in the Philadelphia metropolitan area. PARTICIPANTS: Participants included 120 nursing home residents and 56 family members. MEASUREMENTS: Minimum Data Set (MDS) and data from the Centers for Medicare and Medicaid Services (CMS) Nursing Home Compare Web site RESULTS: There was a statistically significant increase in the number of residents who fell during the post-transfer (76.9%) compared to the pre-transfer (51.2%) period (P = .0001): 76.3% of those with a history of falling prior to transfer fell during the post-transfer period while 77.4% of those without a history of falling prior to transfer fell. Residents were 3.78 times more likely to fall if they required more than supervision while walking (95% confidence interval [CI] 1.57-9.06) and 2.65 times more likely if they required more than supervision while transferring (95% CI 1.09-6.44). Logistic regression demonstrated that the mobility was also associated with falls (odds ratio 1.15, 95% CI 1.05-1.26). Residents did not demonstrate any other significant physical or mental health changes during the 3 months following the involuntary transfer when compared with their pre-transfer status. Residents and family members clearly voiced their dismay over the process of involuntary relocation. CONCLUSION: Relocation is a stressful event; however, a move to a higher quality care environment does not result in any significant physical or mental health changes. The high incidence of falls post-transfer in both those with and without a fall history points to the need for extra fall precautions in newly admitted residents. In particular, frequent reorientation reminders for the cognitively intact and a high level of staff surveillance for all new residents is indicated during the first few weeks of admission.

Adult↗

Image denoising using a tight frame.

We present a general mathematical theory for lifting frames that allows us to modify existing filters to construct new ones that form Parseval frames. We apply our theory to design nonseparable Parseval frames from separable (tensor) products of a piecewise linear spline tight frame. These new frame systems incorporate the weighted average operator, the Sobel operator, and the Laplacian operator in directions that are integer multiples of 45 degrees. A new image denoising algorithm is then proposed, tailored to the specific properties of these new frame filters. We demonstrate the performance of our algorithm on a diverse set of images with very encouraging results.

Algorithms↗

An embedded genus-one helicoid.

There exists a properly embedded minimal surface of genus one with a single end asymptotic to the end of the helicoid. This genus-one helicoid is constructed as the limit of a continuous one-parameter family of screw-motion invariant minimal surfaces, also asymptotic to the helicoid, that have genus equal to one in the quotient.

Journal Article↗

Exposure to polybrominated diphenyl ethers (PBDEs): changes in thyroid, vitamin A, glutathione homeostasis, and oxidative stress in American kestrels (Falco sparverius).

Polybrominated diphenyl ethers (PBDEs), a class of additive flame retardants, are temporally increasing in wildlife tissues and capable of disrupting normal endocrine function. We determined whether in ovo and post-hatch exposure of captive American kestrels (Falco sparverius) to environmentally relevant PBDEs alter thyroid, retinol, and oxidative stress measures. Control eggs were injected with safflower oil and subsequent nestlings fed the same vehicle; dosed eggs received PBDE congeners (BDE-47, -99, -100, -153), which mainly comprise the Penta-BDE commercial mixture, dissolved in safflower oil at concentrations (1500 ng/g total [Sigma] PBDEs) approximating those in Great Lakes gull eggs. Nestlings hatching from dosed eggs were orally exposed for 29 days to variable SigmaPBDE concentrations that are similar to levels reported in tissues of Great Lakes trout (100 ng/g). Treatment kestrels had lower plasma thyroxine (T(4)), plasma retinol, and hepatic retinol and retinyl palmitate concentrations, but unaltered triiodothyronine (T(3)) concentrations and thyroid glandular structure. BDE-47, -100, and -99 were negatively associated with plasma T(4), plasma retinol (BDE-100, -99) and hepatic retinol (BDE-47). Despite an antioxidant-rich diet, PBDE exposure induced hepatic oxidative stress, particularly in females, with an increased hepatic GSSG:GSH ratio, a marginal increase in lipid peroxidation, and increased oxidized glutathione. Positive associations were found between concentrations of BDE-183 and thiols and, in males, between BDE-99 and reduced GSH, but a negative association occurred between BDE-99 and TBARS. Subsequently, concentrations of PBDE congeners in wild birds may alter thyroid hormone and vitamin A concentrations, glutathione metabolism and oxidative stress.

Animals↗

Two-sided tolerance intervals for balanced and unbalanced random effects models.

A procedure for constructing two-sided beta-content, gamma-confidence tolerance intervals is proposed for general random effects models, in both balanced and unbalanced data scenarios. The proposed intervals are based on the concept of effective sample size and modified large sample methods for constructing confidence bounds on functions of variance components. The performance of the proposed intervals is evaluated via simulation techniques. The results indicate that the proposed intervals generally maintain the nominal confidence and content levels. Application of the proposed procedure is illustrated with a one-fold nested design used to evaluate the performance of a quantitative bioanalytical method.

Algorithms↗