Characterization of the thermodynamic cycle of a MEMS-based external combustion resonant engine

The thermodynamic cycle of a resonant, MEMS-based, micro heat engine is characterized. The micro heat engine is an external combustion engine made of a cavity encapsulated between two membranes. The cavity is filled with saturated liquid–vapor mixture working fluid. Heat is added to and rejected from the engine at a frequency corresponding to the resonant frequency of the engine. Both pressure–volume and temperature-entropy diagrams are used to investigate the thermodynamic cycle of the resonant micro heat engine. The results show that the working cycle is nearly rectangular in shape and consists of two constant temperature processes and two constant volume processes. We hypothesize that major sources of irreversibility in the engine are heat transfer over finite temperature differences during heat addition and rejection, heat transfer into and out of engine thermal mass, viscous losses due to liquid working fluid motion, and heat escape from the engine to the surroundings. The maximum pressure and volume changes measured inside the engine cavity are 45?Pa and 0.55?mm³, respectively. The results show that for a heat addition of 1?mJ, the engine operates over a very small temperature difference. The small operating temperature difference is mostly attributable to the large thermal storage of the engine structure, the membranes and the wicks. The measured second law efficiency of the micro heat engine is 16?%.     

Imported measles. A potential control problem

From Dec 23, 1978, through Jan 31, 1979, an outbreak of five laboratory-confirmed cases and four clinical cases of measles occurred in a Vietnamese refugee population living in a single housing complex in Albuquerque, NM. The index cases were in two refugee siblings in whom measles was incubating on arrival in the United States. Despite spread through three subsequent generations of disease transmission within the Vietnamese population, there was no additional spread into the general Albuquerque population. Responsible factors included the age distribution of susceptible persons, the social isolation of the refugee population, and the physical structure of the housing complex. There is a need to identify the problem of imported measles in "ethnic islands" in need of vaccination.     

The transient response of ZrO2 oxygen sensors to step changes in gas composition

The transient voltage response of ZrO₂ oxygen sensors was examined following step changes in gas composition. The experiments were performed on a laboratory flow reactor at 600° C. Composition changes between (a) 100% and (b) 1% O₂ in N₂ produced response curves whose symmetry varied between composition steps (a) from low-to-high oxygen and (b) from high-to-low oxygen. This difference is due to the logarithmic dependence of sensor voltage on oxygen partial pressure. Corresponding oxygen partial pressure-time curves, derived from experimental voltage via the Nernst equation, are symmetric with respect to the direction of composition changes. Abrupt transitions are found in voltage-time curves at 600° C following step changes of reactive gases; e.g. from O₂/N₂ mixtures to CO/N₂, H₂/N₂ or D₂/N₂ mixtures. These voltage-steps represent transitions in stoichiometry of the surface boundary layer on the ZrO₂ sensor. Delay times before the transition also reflect reaction stoichiometry. Response times with O₂/CO, O₂/H₂ and O₂/D₂ follow trends predicted by the kinetic theory of gases. A limited number of experiments were performed to examine the relationships between sensor response and sensor catalytic activity. Poorer oxidation catalytic activity parallels slower response characteristics.     

Electrical resistivity of nickel-rich nickel-chromium alloys between 4 and 300 K

Electrical resistivity of Ni–Cr alloys containing 5.5, 11.3, 15.7, 16.8, 19.4, 22.0, 24.6, and 27.0 at % Cr has been measured as a function of the absolute temperatureT between 4 and 300 K. The sample with the Cr content of 22.0 at % exhibits a small minimum at about 10 K. No minimum has been observed in any other of the above samples, although an anomalousT dependence has been found in alloys containing 15.7, 16.8, and 19.4 at % Cr. The minimum has been discussed from the viewpoint of the Béal-Monod theory for the Kondo effect in concentrated systems and the mechanism by Greig and Rowlands based on aT-dependent decrease of the impurity electrical resistivity. It is concluded that the minimum in the Ni–Cr system is still a phenomenon which is not well understood at the present time.     

Office otology follow-up

The validation of otological care in the previous quarter century has been based, by and large, on short-term follow-up information. The rapid variation in procedures introduced during this period indicates that there may be need for further consideration. Analyses based on relatively short duration have led the "acceptance" of a variety of diagnostic and treatment methods which have proven disappointing in some cases. To help avoid this invalid "acceptance," a review of patients with significant follow-up may result in a more critical evaluation of future procedural changes. This presentation will be in four parts: 1. History of the office structure. 2. Discussion of five long-term patients that illustrates and supports certain otological concepts. 3. A review of surgical care for chronic suppurative otitis media in 1968. 4. A review of patients treated for serous otitis media with myringotomy and tubal insertion in 1968.     

Sodium nitroprusside: pharmacology, toxicology and therapeutics

Sodium nitroprusside is a potent, effective, and readily reversible direct vasodilating agent. It is broken down by hemoglobin into cyanide, which is in part detoxified by liver and kidney to thiocyanate. Some cyanide, especially in nitroprusside- "resistant" individuals who need large amounts of the drug, appears to remain free to cause cyanide poisoning. Patients requiring inordinate amounts probably should not continue to receive the drug, although maximum dosage limits for long-term therapy are not established. Blood thiocyanate levels do not indicate the extent to which free cyanide is limiting oxygen utilization in essential tissue, nor do blood cyanide levels. Metabolic acidosis, elevated lactate levels, elevated lactate/pyruvate ratios, and elevated mixed venous blood oxygen content are at present the best indications of the presence of cyanide poisoning during nitroprusside administration. Nitroprusside appears useful for induction of hypotension during surgery, and for treatment of hypertensive emergencies from all causes, although continuance for more than a few days is probably unwise. The reductions of cardiac afterload and ventricular filling pressure by nitroprusside appear useful in treatment of severe myocardial failure or infarction, but studies of myocardial cyanide toxicity are needed before complete acceptance of this therapy is warranted. Initial dose rates between 0.5 and 1.5 mug/kg/min are recommended only as starting points for very careful titration. Total projected intra-operative dosage should be calculated as quickly as possible and should not exceed 3-3.5 mg/kg. It is hoped that future studies will reveal the maximum dose of nitroprusside that can safely be metabolized in a 24-hour period, and may indicate that cofactors of rhodanase such as thiosulfate, or cobalamins such as hydroxocobalamin, can be administered with nitroprusside to prevent cyanide poisoning.     

Genes, Race, and Psychology in the Genome Era: An Introduction.

The mapping of the human genome has reawakened interest in the topic of race and genetics, especially the use of genetic technology to examine racial differences in complex outcomes such as health and intelligence. Advances in genomic research challenge psychology to address the myriad conceptual, methodological, and analytical issues associated with research on genetics and race. In addition, the field needs to understand the numerous social, ethical, legal, clinical, and policy implications of research in this arena. Addressing these issues should not only benefit psychology but could also serve to guide such thought in other fields, including molecular biology. The purpose of this special issue is to begin a discussion of this issue of race and genetics within the field of psychology. Several scholars who work in the fields of genetics, race, or related areas were invited to write (or had previously submitted) articles sharing their perspectives. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Advice and Influence Networks of Transformational Leaders.

Existing transformational leadership research has focused primarily on the behaviors of leaders and their effects on followers. The authors extended this research by examining the social networks of managers who exhibit transformational leadership behaviors. Their focus was on the network of relationships that managers develop and whether they hold key positions in the organization's informal social networks. In a field study using data from 39 managers and 130 nonmanagement employees of 6 organizations, the authors found that managers who score higher on transformational leadership tend to hold more central positions in organizational advice and influence networks. Furthermore, the direct reports of these leaders were also more central in informal organizational networks. These results illuminate one of the ways that managers who exhibit transformational leadership behaviors may exert influence in organizations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Clinical Trial to Test the Feasibility of a Telehealth Psychoeducational Intervention for Persons With Schizophrenia and Their Families: Intervention and 3-Month Findings.

Objective: To evaluate the feasibility of a telehealth psychoeducation intervention for persons with schizophrenia and their family members. Study Design: Randomized controlled trial. Participants: 30 persons with schizophrenia and 21 family members or other informal support persons. Interventions: Web-based psychoeducation program that provided online group therapy and education. Main Outcome Measures: Measures for persons with schizophrenia included perceived stress and perceived social support; for family members, they included disease-related distress and perceived social support. Results: At 3 months, participants with schizophrenia in the intervention group reported lower perceived stress (p = .04) and showed a trend for a higher perceived level of social support (p = .06). Conclusions: The findings demonstrate the feasibility and impact of providing telehealth-based psychosocial treatments, including online therapy groups, to persons with schizophrenia and their families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Micro-engineered first wall tungsten armor for high average power laser fusion energy systems

The high average power laser program is developing an inertial fusion energy demonstration power reactor with a solid first wall chamber. The first wall (FW) will be subject to high energy density radiation and high doses of high energy helium implantation. Tungsten has been identified as the candidate material for a FW armor. The fundamental concern is long term thermo-mechanical survivability of the armor against the effects of high temperature pulsed operation and exfoliation due to the retention of implanted helium. Even if a solid tungsten armor coating would survive the high temperature cyclic operation with minimal failure, the high helium implantation and retention would result in unacceptable material loss rates. Micro-engineered materials, such as castellated structures, plasma sprayed nano-porous coatings and refractory foams are suggested as a first wall armor material to address these fundamental concerns. A micro-engineered FW armor would have to be designed with specific geometric features that tolerate high cyclic heating loads and recycle most of the implanted helium without any significant failure. Micro-engineered materials are briefly reviewed. In particular, plasma-sprayed nano-porous tungsten and tungsten foams are assessed for their potential to accommodate inertial fusion specific loads. Tests show that nano-porous plasma spray coatings can be manufactured with high permeability to helium gas, while retaining relatively high thermal conductivities. Tungsten foams where shown to be able to overcome thermo-mechanical loads by cell rotation and deformation. Helium implantation tests have shown, that pulsed implantation and heating releases significant levels of implanted helium. Helium implantation and release from tungsten was modeled using an expanded kinetic rate theory, to include the effects of pulsed implantations and thermal cycles. Although, significant challenges remain micro-engineered materials are shown to constitute potential candidate FW armor materials.