Dynamics of Peer Education in Cooperative Learning Workgroups

Many recent studies demonstrate that cooperative learning provides a variety of educational advantages over more traditional instructional models, both in general and specifically in engineering education. Little is known, however, about the interactional dynamics among students in engineering work groups. To explore these dynamics and their implications for engineering education, we analyzed work sessions of student groups in a sophomore‐level chemical engineering course at North Carolina State University. Using conversation analysis as a methodology for understanding how students taught and learned from one another, we found that group members generally engaged in two types of teaching‐learning interactions. In the first type, transfer‐of‐knowledge (TK) sequences, they took on distinct teacher and pupil roles, and in the second, collaborative sequences (CS), they worked together with no clear role differentiation. The interactional problems that occurred during the work sessions were associated primarily with TK sequences, and had to do with students who either habitually assumed the pupil's role (constant pupils) or habitually discouraged others' contributions (blockers). Our findings suggest that professors can facilitate student group interactions by introducing students to the two modes of teaching interaction so group members can effectively manage exchanges of knowledge, and also by helping students distribute tasks in a way that minimizes role imbalances.     

Large-Format HgCdTe Dual-Band Long-Wavelength Infrared Focal-Plane Arrays

Raytheon Vision Systems (RVS) continues to further its capability to deliver state-of-the-art high-performance, large-format, HgCdTe focal-plane arrays (FPAs) for dual-band long-wavelength infrared (L/LWIR) detection. Specific improvements have recently been implemented at RVS in molecular-beam epitaxy (MBE) growth and wafer fabrication and are reported in this paper. The aim of the improvements is to establish producible processes for 512 × 512 30-μm-unit-cell L/LWIR FPAs, which has resulted in: the growth of triple-layer heterojunction (TLHJ) HgCdTe back-to-back photodiode detector designs on 6 cm × 6 cm CdZnTe substrates with 300-K Fourier-transform infrared (FTIR) cutoff wavelength uniformity of ±0.1 μm across the entire wafer; demonstration of detector dark-current performance for the longer-wavelength detector band approaching that of single-color liquid-phase epitaxy (LPE) LWIR detectors; and uniform, high-operability, 512 × 512 30-μm-unit-cell FPA performance in both LWIR bands.     

BANQ餐厅 美国波士顿

正Banq餐厅位是一家新型餐厅,位于便士储蓄银行(Penny Savings Bank)旧大楼以前用来经营银行业务的大厅内。餐厅分成两个部分,前面区域面向华盛顿大街,设计成酒吧,后面的大厅则作为用餐区。然而,这个空间在z轴上以天花板和地面之间的另一个分区为中心进行设计。如果由于餐厅空间活动的多变性而需要保持灵活性——包括两个座位、四个座位和六个座位,以及与聚会和其他活动有关的座位     

Flow and spawning habitat relationships for Dolly Varden: Understanding habitat–population dynamics in the Canadian Western Arctic

Northern form Dolly Varden (Salvelinus malma malma) have been designated as a species of Special Concern in Canada due to declines in population abundance and potential threats. Concern over detrimental effects of low flows on population abundance prompted research on how variability in discharge regimes influence habitat availability. Habitat suitability indices for prespawning and spawning adult anadromous Dolly Varden from two streams were integrated into a two‐dimensional hydrodynamic habitat model to assess the effect of flow variability on usable habitat. Regional hydrographs were used to identify an ecologically relevant range of flows that provided optimal spawning habitat for these populations and examine the relationship between abundance and discharge. Adults spawned in the tail end of pools at moderate water depths and water velocities, and used pebble‐ to cobble‐sized substrate for building redds; whereas, prespawning adults occupied deeper pools with moderate velocities and used cobble for cover. Model outputs showed that spawning habitat availability was optimized at flow rates between 1.6 and 3.0 m³/s and between 1.0 and 6.0 m³/s in Fish Hole Creek (FHC) and Little Fish Creek, respectively. A positive relationship between flows during the fall spawning period and abundance of the FHC population suggests that higher flows coinciding with optimal habitat availability may have contributed to positive recruitment. To strengthen and refine this habitat–population relationship for Dolly Varden in this area requires investigation of a broader suite of variables associated with environmental regimes and physical habitat in reaches used for spawning.     

Comparison of calcium lactate with chlorine as a washing treatment for fresh‐cut lettuce and carrots: quality and nutritional parameters

The efficacies of calcium lactate and chlorine washing treatments of fresh‐cut lettuce and carrots were compared during storage at 4 °C over 10 days. The gas composition of packages, colour, enzyme activity, texture, sensory attributes, microflora and levels of ascorbic acid and carotenoids were evaluated at 1, 3, 7 and 10 days. Calcium lactate treatment was not significantly different to chlorine treatment (p < 0.05) in terms of maintaining colour, texture and acceptability of fresh‐cut lettuce and carrots during the entire storage period. The washing treatments did not affect levels of ascorbic acid of fresh‐cut lettuce or carrots. Carotenoid levels were higher in calcium lactate‐treated carrots than chlorine‐treated samples at the end of storage. Mesophilic, psychrotrophic and lactic acid bacteria counts were not significantly different between treatments for both vegetables. Copyright © 2005 Society of Chemical Industry     

Adenovirus-mediated p53 gene transfer in patients with advanced recurrent head and neck squamous cell carcinoma

PURPOSE: Standard therapies of head and neck squamous cell carcinoma (HNSCC) often cause profound morbidity and have not significantly improved survival over the last 30 years. Preclinical studies showed that adenoviral vector delivery of the wild-type p53 gene reduced tumor growth in mouse xenograft models. Our purpose was to ascertain the safety and therapeutic potential of adenoviral (Ad)-p53 in advanced HNSCC. PATIENTS AND METHODS: Patients with incurable recurrent local or regionally metastatic HNSCC received multiple intratumoral injections of Ad-p53, either with or without tumor resection. Patients were monitored for adverse events and antiadenoviral antibodies, tumors were monitored for response and p53 expression, and body fluids were analyzed for Ad-p53. RESULTS: Tumors of 33 patients were injected with doses of up to 1 x 10(11) plaque-forming units (pfu). No dose-limiting toxicity or serious adverse events were noted. p53 expression was detected in tumor biopsies despite antibody responses after Ad-p53 injections. Clinical efficacy could be evaluated in 17 patients with nonresectable tumors: two patients showed objective tumor regressions of greater than 50%, six patients showed stable disease for up to 3.5 months, and nine patients showed progressive disease. One resectable patient was considered a complete pathologic response. Ad-p53 was detected in blood and urine in a dose-dependent fashion, and in sputum. CONCLUSION: Patients were safely injected intratumorally with Ad-p53. Objective antitumor activity was detected in several patients. The infectious Ad-p53 in body fluids was asymptomatic, and suggests that systemic or regional treatment may be tolerable. These results suggest the further investigation of Ad-p53 as a therapeutic agent for patients with HNSCC.     

Transplantation of stromal cells transduced with the human IL3 gene to stimulate hematopoiesis in human fetal bone grafts in non-obese, diabetic-severe combined immunodeficiency mice

The non-obese diabetic-severe combined immunodeficiency (NOD-SCID) mouse is a convenient host for human hematopoietic tissues and cells. Human fetal bone fragments engrafted subcutaneously in NOD-SCID mice sustain human hematopoiesis for several months. MS5 murine bone marrow stromal cells were transfected by electroporation with a plasmid containing the human interleukin-3 gene. As expected, stably transfected hu-IL3-MS5 cells supported human hematopoiesis in vitro more efficiently than MS5 cells. hu-IL3-MS5 cells were then injected intravenously into hu-NOD-SCID mice to test their ability to home to the mouse and/or human bone marrow, and to evaluate the role of hu-IL3 secretion on human hematopoiesis in vivo. hu-IL3 was detected in the mouse serum for up to an observation time of 8 weeks. hu-IL3-MS5 cells engrafted the bone marrow, spleen, liver and lungs of the mice but also the human bone graft. The presence of hu-IL3-MS5 cells in the human bone significantly stimulated local human hematopoiesis. This setting could be used to model the bone marrow homing of intravenously injected stromal cells or stromal cell precursors. The same experimental principle could also be applied in a therapeutic perspective to malignant human bone marrow hematopoiesis.