Digital Cavities and Their Potential Applications

The concept of a digital cavity is presented. The functionality of a tunable radio-frequency/microwave cavity with unrestricted Q-factor is implemented. The theoretical aspects of the cavity and its potential applications in high resolution spectroscopy and synchronization of clocks together with examples in signal processing and data acquisition are discussed

The Versatility of Perforator-Based Propeller Flap for Reconstruction of Distal Leg and Ankle Defects

Introduction. Soft tissue coverage of distal leg and ankle region represents a challenge and such defect usually requires a free flap. However, this may lead to considerable donor site morbidity, is time consuming, and needs facility of microsurgery. With the introduction of perforator flap, management of small- and medium-size defects of distal leg and ankle region is convenient, less time consuming, and with minimal donor site morbidity. When local perforator flap is designed as propeller and rotated to 180 degree, donor site is closed primarily and increases reach of flap, thus increasing versatility. Material and Methods. From June 2008 to May 2011, 20 patients were treated with perforator-based propeller flap for distal leg and ankle defects. Flap was based on single perforator of posterior tibial and peroneal artery rotated to 180 degrees. Defect size was from 4 cm × 3.5 cm to 7 cm × 5 cm. Results. One patient developed partial flap necrosis, which was managed with skin grafting. Two patients developed venous congestion, which subsided spontaneously without complications. Small wound dehiscence was present in one patient. Donor site was closed primarily in all patients. Rest of the flaps survived well with good aesthetic results. Conclusion. The perforator-based propeller flap for distal leg and ankle defects is a good option. This flap design is safe and reliable in achieving goals of reconstruction. The technique is convenient, less time consuming, and with minimal donor site morbidity. It provides aesthetically good result

Akimotoite to perovskite phase transition in MgSiO 3

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94612/1/grl18182.pd

Structural and Physical Properties of CaFe4As3 Single Crystals

We report the synthesis, and structural and physical properties of CaFe4As3 single crystals. Needle-like single crystals of CaFe4As3 were grown out of Sn flux and the compound adopts an orthorhombic structure as determined by X-ray diffraction measurements. Electrical, magnetic, and thermal properties indicate that the system undergoes two successive phase transitions occurring at TN1 ~ 90 K and TN2 ~ 26 K. At TN1, electrical resistivities (\rho(b) and \rho(ac)) are enhanced while magnetic susceptibilities (\chi(b) and \chi(ac)) are reduced in both directions parallel and perpendicular to the b-axis, consistent with the scenario of antiferromagnetic spin-density-wave formation. At TN2, specific heat reveals a slope change, and \chi(ac) decreases sharply but \chi(b) has a clear jump before it decreases again with decreasing temperature. Remarkably, both \rho(b) and \rho(ac) decrease sharply with thermal hysteresis, indicating the first-order nature of the phase transition at TN2. At low temperatures, \rho(b) and \rho(ac) can be described by {\rho} = {\rho}0 + AT^\alpha ({\rho}0, A, and {\alpha} are constants). Interestingly, these constants vary with applied magnetic field. The ground state of CaFe4As3 is discussed.Comment: 15 pages, 8 figures, Submitted to Physical Review

Thermal Performance Evaluation of a Residential Solar/Gas Hybrid Water Heating System

In climate regions with lower average daily solar radiation, such as the Pacific Northwest, a solar energy collector might not economically satisfy year-round domestic water heating demands, requiring an auxiliary unit, such as a natural gas water heater. Previous studies of such hybrid systems have shown that the efficiencies achieved while running in combined solar/gas mode was lower than expected. This inefficiency was attributed to a reduction in gas burner efficiency when the process fluid was partially pre-heated by the solar input. To predict the actual energy and cost savings under various design conditions, the performance of solar/gas hybrid systems must be better understood. In this work, the performance of a commercial hybrid solar/gas system is experimentally characterized to evaluate individual component and overall system efficiency. The hybrid water heating system consisted of three flat plate collectors arranged in series (total area = 6.44 m2), and a 22.3 kW natural gas burner. Under different temperature lifts and solar insolation values, the system was operated at three different modes of heating: solar, gas, and combined solar/gas mode. Efficiency value for each mode was calculated. Based on the experimental efficiency results, a configuration that would provide higher efficiency for combined solar/gas heating is suggested

High Precision Measurements Using High Frequency Signals

Generalized lock-in amplifiers use digital cavities with Q-factors as high as 5X10^8. In this letter, we show that generalized lock-in amplifiers can be used to analyze microwave (giga-hertz) signals with a precision of few tens of hertz. We propose that the physical changes in the medium of propagation can be measured precisely by the ultra-high precision measurement of the signal. We provide evidence to our proposition by verifying the Newton's law of cooling by measuring the effect of change in temperature on the phase and amplitude of the signals propagating through two calibrated cables. The technique could be used to precisely measure different physical properties of the propagation medium, for example length, resistance, etc. Real time implementation of the technique can open up new methodologies of in-situ virtual metrology in material design

Class III beta-tubulin, drug resistance and therapeutic approaches in cancers

Class III beta-tubulin is one of the critical proteins associated with microtubule assembly, important to many cellular functions including mitochondrial respiration and intracellular trafficking. Widely regarded as a specific neuronal marker in developmental neurobiology and stem cell research, it is also highly expressed in a wide range of tumors of both neuronal and non-neuronal origin. The expression of class III beta-tubulin is tightly controlled at multiple levels with tissue-dependent mechanisms of regulation. For instance, class III beta-tubulin expression is under the control of estrogens in breast cancer cells but is influenced by exposure to hypoxia and poor-nutrient supply in ovarian cancer. In some but not all cancers, class III beta-tubulin expression is purely a prognostic biomarker, predicting poor outcome of patients regardless of chemotherapy treatment. Moreover, the expression of class III beta-tubulin does not confer an aggressive phenotype by itself. Instead, class III beta-tubulin functions like a cytoskeletal gateway, which enhances the incorporation of pro-survival kinases into the cytoskeleton and protects them from degradation. The associations of class III beta-tubulin with survival kinase PIM-1, RNA-binding protein HuR, microRNAs are examples highlighting the functional complexity of this protein. The utility of class III beta-tubulin as a prognostic biomarker can also greatly improve if combined with these pro-survival partners. Subsequently, pharmacogenetic approaches, designed to counteract and target these pathways and associated-factors concurrently, might lead to better therapies and prognostic tools for class III beta-tubulin expressing cancers