INTERFACE DESIGN FOR A VIRTUAL REALITY-ENHANCED IMAGE-GUIDED SURGERY PLATFORM USING SURGEON-CONTROLLED VIEWING TECHNIQUES

Initiative has been taken to develop a VR-guided cardiac interface that will display and deliver information without affecting the surgeons’ natural workflow while yielding better accuracy and task completion time than the existing setup. This paper discusses the design process, the development of comparable user interface prototypes as well as an evaluation methodology that can measure user performance and workload for each of the suggested display concepts. User-based studies and expert recommendations are used in conjunction to es­ tablish design guidelines for our VR-guided surgical platform. As a result, a better understanding of autonomous view control, depth display, and use of virtual context, is attained. In addition, three proposed interfaces have been developed to allow a surgeon to control the view of the virtual environment intra-operatively. Comparative evaluation of the three implemented interface prototypes in a simulated surgical task scenario, revealed performance advantages for stereoscopic and monoscopic biplanar display conditions, as well as the differences between three types of control modalities. One particular interface prototype demonstrated significant improvement in task performance. Design recommendations are made for this interface as well as the others as we prepare for prospective development iterations

Responses of Mammalian Cells to Membrane-Disrupting Peptides.

Responses of cultured mouse fibroblasts, human erythrocytes, bovine erythrocytes, and liposomes with different phosphatidylcholine (PC) and sphingomyelin (SPM) ratios to both natural and synthetic lytic peptides were characterized. Peptide-induced morphological alterations of the plasma membrane of cells were examined by various light microscopic techniques and scanning electron microscopy (SEM). The ability of natural and synthetic peptides to kill cells and cause increased permeability of liposomes was evaluated using Trypan Blue (TB) dye exclusion assay and fluorescent dye leakage assay, respectively. Differential interference contrast microscopy, SEM, and fluorescence studies revealed characteristic structural and lipid changes in the plasma membrane of lytic peptide-treated fibroblasts, and these alterations were accompanied by simultaneous changes in the cell permeability as indicated by the uptake of TB. Formation of membrane vesicles, composed primarily of lipids, was demonstrated in cells treated with a low lethal dose of melittin and eventually resulted in the liberation of membrane lipids. SEM revealed that much of the plasma membrane was lost by 5 minutes following peptide exposure. Confocal microscopy confirmed the translocation of membrane proteins from the cell surface to cytoplasmic areas in peptide-treated cells. A fluorescently labeled peptide was used to demonstrate the reaction of the peptides with the plasma membrane. The measurements of the ability of natural and synthetic peptides to kill fibroblasts allowed classification of these peptides into four groups. The results also suggested that peptide length and substitution of glycine for alanine affected the potency of synthetic peptides. Differential susceptibility of different cell types to destruction by the same peptides was demonstrated in mouse fibroblasts and human and bovine erythrocytes. These peptides were less efficient in lysing erythrocytes than in destroying fibroblasts. This difference in activity was possibly due to the higher content of membrane SPM in the resistant RBCs. Lytic peptides demonstrated less ability to permeate liposomes composed of 70% SPM. Synergistic effects were demonstrated in mammalian cells using weak lytic peptides and exogenous phospholipases. The effect was dependant upon the phospholipid composition of the target cells. Cell susceptibility and synergy between peptides and membrane reactive enzymes are important factors in the selection of therapeutic peptides

Living alone, social support, and feeling lonely among the elderly

This study aimed to describe the characteristics of the elderly population living alone, and to examine how living alone relates to feeling lonely. Interviews were conducted with a stratified random sample of 4,859 elderly individuals living in Kaohsiung, Taiwan. Variables collected included demographic information, living alone or not, activities of daily living(ADL), instrumental activities of daily living (IADL), Short Portable Mental Status Questionnaire (SPMSQ), chronic conditions, perceived social support, and a subjective measure of feeling lonely. Using logistic regression, it was found that factors associated with living alone included gender, marital status, occupation, source of income, religion, and IADL. Living alone was, in tum, related to decreased levels of both perceived social supportand feeling lonely after adjustment for potential confounders. Managing retired life is important for adult elders, particularly for men. Lack ofsocial support is common among the elderly community who live alone, which could wel1 be a main reason for this group to feel lonely. As loneliness is linked to physical and mental health problems, increasing social support and facilitating friendship should be factored into life-style management forcommunities of elderly

Mathematical Content Knowledge for Teaching Elementary Mathematics: A Focus on Fractions

This article presents a research summary of prospective elementary teachers’ (PTs’) mathematical content knowledge in the area of fractions. The authors conducted an extensive review of the research literature and present the findings across three time frames: a historical look (pre-­‐1998), a current perspective (1998–2011), and a look at the horizon (2011–2013). We discuss 43 articles written across these time frames that focus on PTs’ fraction knowledge. Consistent across these papers is that PTs’ fraction knowledge is relatively strong when it comes to performing procedures, but that they generally lack flexibility in moving away from procedures and using “fraction number sense” and have trouble understanding the meanings behind the procedures or why procedures work. Across the time frames, the trend in the research has moved from looking almost entirely at PTs’ understanding of fraction operations, particularly multiplication and division, to a more balanced study of both their knowledge of operations and fraction concepts. What is lacking in the majority of these studies are ways to help improve upon PTs’ fraction content knowledge. Findings from this summary suggest the need for a broader study of fractions in both content and methods courses for PTs, as well as research into how PTs’ fraction content knowledge develops

Motility induced changes in viscosity of suspensions of swimming microbes in extensional flows

Suspensions of motile cells are model systems for understanding the unique mechanical properties of living materials which often consist of ensembles of self-propelled particles. We present here a quantitative comparison of theory against experiment for the rheology of such suspensions. The influence of motility on viscosities of cell suspensions is studied using a novel acoustically-driven microfluidic capillary-breakup extensional rheometer. Motility increases the extensional viscosity of suspensions of algal pullers, but decreases it in the case of bacterial or sperm pushers. A recent model [Saintillan, Phys. Rev. E, 2010, 81:56307] for dilute active suspensions is extended to obtain predictions for higher concentrations, after independently obtaining parameters such as swimming speeds and diffusivities. We show that details of body and flagellar shape can significantly determine macroscale rheological behaviour.Comment: 12 pages, 1 appendix, 7 figures, submitted to Soft Matter - under revie

Preparing Globally and Socially-conscious Engineers: International and Humancentred Design Projects and Activities in the First Year

In recent years, a number of innovative activities involving early design/hands on experiences have been introduced into first and second semester freshman courses at Virginia Tech. The objective is to excite freshmen about the engineering profession and to provide early exposure to topics essential to their preparation as globally and socially conscious engineers. A number of initiatives including a sustainable development design project, study abroad presentations, and a world population activity have been implemented in the first course. In the second course, a design project with a focus on assistive technologies for third world countries has been implemented

Antitumor activity of the ERK inhibitor SCH772984 [corrected] against BRAF mutant, NRAS mutant and wild-type melanoma.

BackgroundIn melanoma, dysregulation of the MAPK pathway, usually via BRAF(V600) or NRAS(Q61) somatic mutations, leads to constitutive ERK signaling. While BRAF inhibitors are initially effective for BRAF-mutant melanoma, no FDA-approved targeted therapies exist for BRAF-inhibitor-resistant BRAF(V600), NRAS mutant, or wild-type melanoma.MethodsThe 50% inhibitory concentration (IC50) of SCH772984, a novel inhibitor of ERK1/2, was determined in a panel of 50 melanoma cell lines. Effects on MAPK and AKT signaling by western blotting and cell cycle by flow cytometry were determined.ResultsSensitivity fell into three groups: sensitive, 50% inhibitory concentration (IC50) < 1 μM; intermediately sensitive, IC50 1-2 μM; and resistant, >2 μM. Fifteen of 21 (71%) BRAF mutants, including 4 with innate vemurafenib resistance, were sensitive to SCH772984. All three (100%) BRAF/NRAS double mutants, 11 of 14 (78%) NRAS mutants and 5 of 7 (71%) wild-type melanomas were sensitive. Among BRAF(V600) mutants with in vitro acquired resistance to vemurafenib, those with MAPK pathway reactivation as the mechanism of resistance were sensitive to SCH772984. SCH772984 caused G1 arrest and induced apoptosis.ConclusionsCombining vemurafenib and SCH722984 in BRAF mutant melanoma was synergistic in a majority of cell lines and significantly delayed the onset of acquired resistance in long term in vitro assays. Therefore, SCH772984 may be clinically applicable as a treatment for non-BRAF mutant melanoma or in BRAF-mutant melanoma with innate or acquired resistance, alone or in combination with BRAF inhibitors

FOXD3 Regulates VISTA Expression in Melanoma.

Immune checkpoint inhibitors have improved patient survival in melanoma, but the innate resistance of many patients necessitates the investigation of alternative immune targets. Many immune checkpoint proteins lack proper characterization, including V-domain Ig suppressor of T cell activation (VISTA). VISTA expression on immune cells can suppress T cell activity; however, few studies have investigated its expression and regulation in cancer cells. In this study, we observe that VISTA is expressed in melanoma patient samples and cell lines. Tumor cell-specific expression of VISTA promotes tumor onset in vivo, associated with increased intratumoral T regulatory cells, and enhanced PDL-1 expression on tumor-infiltrating macrophages. VISTA transcript levels are regulated by the stemness factor Forkhead box D3 (FOXD3). BRAF inhibition upregulates FOXD3 and reduces VISTA expression. Overall, this study demonstrates melanoma cell expression of VISTA and its regulation by FOXD3, contributing to the rationale for therapeutic strategies that combine targeted inhibitors with immune checkpoint blockade

Understanding the Priorities and Practices of Rural Science Teachers: Implications for Designing Professional Learning

In order to design professional learning that supports rural science teachers to effectively implement standards-based “five-dimensional” (5D) instructional and assessment practices, a critical first step is to elicit their perspectives, prior experiences, concerns, and interests. Based on survey data from 87 rural science teachers in Colorado, along with focus group sessions with 18 of those teachers, this article investigates teachers’ perspectives on what makes rural science teaching unique, the degree to which they use 5D science instruction, their curricular and assessment resources, and their professional learning experiences and preferences. Overall, rural science teachers in Colorado reported using rich practices for engaging students’ interests and identities in the pursuit of high-quality engagement, and they expressed a need for more science-specific professional learning and materials distribution. Implications for designing professional learning opportunities for rural science teachers are offered

Examining Plasmodium falciparum and P. vivax clearance subsequent to antimalarial drug treatment in the Myanmar-China border area based on quantitative real-time polymerase chain reaction

BackgroundRecent emergence of artemisinin-resistant P. falciparum has posed a serious hindrance to the elimination of malaria in the Greater Mekong Subregion. Parasite clearance time, a measure of change in peripheral parasitaemia in a sequence of samples taken after treatment, can be used to reflect the susceptibility of parasites or the efficiency of antimalarials. The association of genetic polymorphisms and artemisinin resistance has been documented. This study aims to examine clearance time of P. falciparum and P. vivax parasitemia as well as putative gene mutations associated with residual or recurred parasitemia in Myanmar.MethodsA total of 63 P. falciparum and 130 P. vivax samples collected from two internally-displaced populations and one surrounding village were examined for parasitemia changes. At least four samples were taken from each patient, at the first day of diagnosis up to 3 months following the initial treatment. The amount of parasite gene copy number was estimated using quantitative real-time PCR based on a species-specific region of the 18S rRNA gene. For samples that showed residual or recurred parasitemia after treatment, microsatellites were used to identify the 'post-treatment' parasite genotype and compared such with the 'pre-treatment' genotype. Mutations in genes pfcrt, pfmdr1, pfatp6, pfmrp1 and pfK13 that are potentially associated with ACT resistance were examined to identify if mutation is a factor for residual or persistent parasitemia.ResultsOver 30% of the P. falciprium infections showed delayed clearance of parasitemia after 2-3 days of treatment and 9.5% showed recurred parasitemia. Mutations in codon 876 of the pfmrp1 corroborated significance association with slow clearance time. However, no association was observed in the variation in pfmdr1 gene copy number as well as mutations of various codonsinpfatp6, pfcrt, and pfK13 with clearance time. For P. vivax, over 95% of the infections indicated cleared parasitemia at days 2-3 of treatment. Four samples were found to be re-infected with new parasite strains based on microsatellite genotypes after initial treatment.ConclusionThe appearance of P.falciparum infected samples showing delayed clearance or recurred parasitemia after treatment raises concerns on current treatment and ACT drug resistance