Gradient-based quantitative image reconstruction in ultrasound-modulated optical tomography: first harmonic measurement type in a linearised diffusion formulation

Ultrasound-modulated optical tomography is an emerging biomedical imaging modality which uses the spatially localised acoustically-driven modulation of coherent light as a probe of the structure and optical properties of biological tissues. In this work we begin by providing an overview of forward modelling methods, before deriving a linearised diffusion-style model which calculates the first-harmonic modulated flux measured on the boundary of a given domain. We derive and examine the correlation measurement density functions of the model which describe the sensitivity of the modality to perturbations in the optical parameters of interest. Finally, we employ said functions in the development of an adjoint-assisted gradient based image reconstruction method, which ameliorates the computational burden and memory requirements of a traditional Newton-based optimisation approach. We validate our work by performing reconstructions of optical absorption and scattering in two- and three-dimensions using simulated measurements with 1% proportional Gaussian noise, and demonstrate the successful recovery of the parameters to within +/-5% of their true values when the resolution of the ultrasound raster probing the domain is sufficient to delineate perturbing inclusions.Comment: 12 pages, 6 figure

High School to College Transition: A Profile of the Stressors, Physical and Psychological Health Issues That Affect the First-Year On-Campus College Student

The purpose of this article is to provide identified stressors, physical and psychological health issues that affect first year campus college students as they transition from high school to college. The Health Behaviors, Self-Rated Health and Quality of Life (QOL) questionnaire was administered to 514 university college students. Results from this study determined that there were significant differences among student life stressors and physical and psychological health status between first-year on-campus and first-year off-campus college students. Most importantly this study documented compelling information regarding selection of roommate, poor housing, chronic and temporary diseases, injury and prescription medicine among college students attending a university in North Carolina. Implications for university health administrators, student affairs personnel, counselors and faculty are discussed

Proximal genomic localization of STAT1 binding and regulated transcriptional activity

BACKGROUND: Signal transducer and activator of transcription (STAT) proteins are key regulators of gene expression in response to the interferon (IFN) family of anti-viral and anti-microbial cytokines. We have examined the genomic relationship between STAT1 binding and regulated transcription using multiple tiling microarray and chromatin immunoprecipitation microarray (ChIP-chip) experiments from public repositories. RESULTS: In response to IFN-γ, STAT1 bound proximally to regions of the genome that exhibit regulated transcriptional activity. This finding was consistent between different tiling microarray platforms, and between different measures of transcriptional activity, including differential binding of RNA polymerase II, and differential mRNA transcription. Re-analysis of tiling microarray data from a recent study of IFN-γ-induced STAT1 ChIP-chip and mRNA expression revealed that STAT1 binding is tightly associated with localized mRNA transcription in response to IFN-γ. Close relationships were also apparent between STAT1 binding, STAT2 binding, and mRNA transcription in response to IFN-α. Furthermore, we found that sites of STAT1 binding within the Encyclopedia of DNA Elements (ENCODE) region are precisely correlated with sites of either enhanced or diminished binding by the RNA polymerase II complex. CONCLUSION: Together, our results indicate that STAT1 binds proximally to regions of the genome that exhibit regulated transcriptional activity. This finding establishes a generalized basis for the positioning of STAT1 binding sites within the genome, and supports a role for STAT1 in the direct recruitment of the RNA polymerase II complex to the promoters of IFN-γ-responsive genes

Compact Magic-T using microstrip-slotline transitions

The design of a compact low-loss Magic-T is described. The planar Magic-T incorporates a compact microstrip-slotline tee junction and small microstrip-slotline transition area to reduce slotline radiation. The Magic-T produces broadband in-phase and out-of-phase power combiner/divider responses, has low in-band insertion loss, and small in-band phase and amplitude imbalance

The scid mouse as an experimental model for the evaluation of anti-Pneumocystis carinii therapy

The usefulness of scid mice bearing endogenous Pneumocystis carinii infection as a model for experimental chemotherapy was examined using standard compounds known to be effective against P. carinii. Trimethoprim/sulphamethoxazole was able to reduce pulmonary P. carinii cysts in a dose-dependent manner within the dose range studied (10/50 to 100/500 TMP/SMX mg/kg/d, bd, po, 5 days per week for 30 treatments). However, alterations in associated symptoms of infection (reduced body weight, increased lung weight, increased blood leucocytes and erythrocytes), was apparently not linearly dose-dependent. Blood and lung lavage fluid levels of sulphamethoxazole one hour post administration of trimethoprim/sulphamethoxazole was dose-dependent, but not linear with dose, andwas apparently correlated to cyst reduction; trimethoprim was below the limit of detection at this time. Treatment of micewith 100/500 mg/kg/day trimethoprim/ sulphamethoxazole required 2 weeks (bd for 10 days of treatment) before changes in indices of infection became significant. Pentamidine (20 mg/kg, sc, three times per week for 3 weeks) was nearly as effective as high-dose trimethoprim/sulphamethoxazole in reducing cysts, whereas lower doses were ineffective. Despite being unable to reduce pulmonary P. carinii infection, even low doses of pentamidine (6 or 2mg/kg, sc, three times per week for 3 weeks) were able to reduce lung weights and blood leucocyte levels. This model of pulmonary P. carinii infections is amenable to chemotherapeutic intervention in an apparently dose-dependent fashion, and can be used to evaluate the capacity of compounds to eradicate P. carinii and resolve signs of infectio

Assessing algal biomass and bio-optical distributions in perennially ice-covered polar ocean ecosystems

AbstractUnder-ice observations of algal biomass and seasonality are critical for understanding better how climate-driven changes affect polar ocean ecosystems. However, seasonal and interannual variability in algal biomass has been studied sparsely in perennially ice-covered polar ocean regions. To address this gap in polar ocean observing, bio-optical sensors for measuring chlorophyll fluorescence, optical scattering, dissolved organic matter fluorescence, and incident solar radiation were integrated into Ice-Tethered Profilers (ITPs). Eight such systems have been deployed in the Arctic Ocean, with five profilers completing their deployments to date including two that observed an entire annual cycle in the central Arctic Ocean and Beaufort Sea respectively. These time series revealed basic seasonal differences in the vertical distributions of algal biomass and related bio-optical properties in these two regions of the Arctic Ocean. Because they conduct profiles on daily or sub-daily scales, ITP bio-optical data allow more accurate assessments of the timing of changes in under-ice algal biomass such as the onset of the growing season in the water column, the subsequent export of particulate organic matter at the end, and the frequency of intermittent perturbations, which in the central Arctic Ocean were observed to have time scales of between one and two weeks