cssi/SciSciGPT-SciSciNet huggingface dataset:
The back reaction effect in particle creation in curved spacetime

The problem of determining the changes in the gravitational field caused by particle creation is investigated in the context of the semiclassical approximation, where the gravitational field (i.e., spacetime geometry) is treated classically and an effective stress energy is assigned to the created particles which acts as a source of the gravitational field. An axiomatic approach is taken. We list five conditions which the renormalized stress-energy operatorTμv should satisfy in order to give a reasonable semiclassical theory. It is proven that these conditions uniquely determineTμv, i.e. there is at most one renormalized stress-energy operator which satisfies all the conditions. We investigate existence by examining an explicit “point-splitting” type prescription for renormalizingTμv. Modulo some standard assumptions which are made in defining the prescription forTμv, it is shown that this prescription satisfies at least four of the five axioms.
Red cell substitutes: present status.

An attempt at developing a temporary red cell substitute has spanned many decades. The concept of having an acellular oxygen carrier that would not require any typing or cross-matching and have a much longer shelf-life than blood is an attractive one. Hemoglobin and perfluorochemicals are the two candidate substances that have received the most attention. A perfluorochemical emulsion (Fluosol-DA, 20%) was recently tested clinically. Though relatively safe, it was found to be ineffective as an oxygen carrier. Hemoglobin solutions have evolved through several chemical modifications with the aim of improving their oxygen carrying capacity, their oxygen binding characteristics and their intravascular dwell time. Polymerized pyridoxylated hemoglobin is the current modification that best fits these criteria. Its efficacy has been established. Its clinical use awaits the outcome of the ongoing investigations with respect to its safety.
Single-channel properties of mouse-Torpedo acetylcholine receptor hybrids expressed in Xenopus oocytes

This report analyzes the contribution of individual nicotinic acetylcholine receptor (AChR) subunits to the single-channel properties of the AChR ion channel. By in vitro synthesis of mRNA from cDNA clones encoding each AChR subunit (alpha, beta, gamma, and delta) from mouse BC3H-1 cells and Torpedo electric organ and microinjection of appropriate mRNA combinations into Xenopus oocytes, we studied the single-channel properties of both 'homologous' (all subunits from the same species) and 'hybrid' (subunits from both species) AChRs as they were expressed in the oocyte membrane. AChR expression was determined by surface binding of 125I-labeled alpha-bungarotoxin to intact oocytes, and those with binding sites of 1 fmol/cell or more were chosen for patch-clamp studies. Our results indicate the following: (1) Species difference in single-channel conductance can be explained largely by the charge distribution flanking the M2 transmembrane domain. (2) The alpha and delta subunits from mouse AChR independently lengthen the channel open time, in some cases by 10-fold; the beta subunit from mouse shortens the channel open time; the mouse gamma subunit lengthens open time less dramatically. (3) Voltage sensitivity, as measured by the ratio of channel open times at -60 mV and +60 mV, is influenced by the beta and delta subunits, in agreement with our previous study by two-electrode voltage-clamp recording. We conclude that single-channel properties of the AChR are governed by multiple elements located on different AChR subunits.
In the name of culture: berber activism and the material politics of “popular islam” in southeastern morocco

ABSTRACTAfter Moroccan independence in 1956, salafi critiques of the heterodox and heteroprax tendencies associated with “popular Islam” (l'islam populaire, as elaborated in particular by French colonial ethnologists and legal scholars) became enshrined within state ideology and administration. In response, over the past twenty years, a burgeoning Berber (or Amazigh) cultural movement has espoused local religious beliefs and practices as more attuned to the authentic culture of North Africa, and sought the protection of such regional idioms in the name of human rights. This article explores how a set of Amazigh activists from southeastern Morocco, while in many cases avowing a politics of secularism (laicite), nonetheless ambivalently embrace certain practices of “popular Islam” as paramount elements of Berber culture, including pilgrimage to the tombs of “saints,” the role of marabouts and Sufi brotherhoods, the pre-Islamic (Jewish or Christian) roots of ritual life, and the general inscription of the na...
Structural relationships among some BePO-, BeAsO-, and AISiO-RHO framworks

Abstract The structures of Tl+-exchanged and Rb+-exchanged forms of AlSiO-, BeAsO-, and BePO-rho have been investigated using neutron or synchrotron X-ray powder diffraction data collected at room temperature. All materials, except TlAlsiO-rho, crystallize in the space group 123, with a = 13.6469(6) A for TlBePO-rho, a = 13.4791(5) A for RbBePO-rho, and a = 13.998(1) A for (Rb,Tl)BeAsO-rho; for TlAlSiO-rho (I 43m ), a = 14.4636(7) A . The extraframework cations are distributed over the double 9-ring (D8R), single 8-ring (S8R), and two single 6-ring (S6R) sites. Dehydrated single crystals o the (Ca,Li)—beryllophosphate mineral Pahasapaite were also studied to temperatures of 500°C. Unlike AlSiO-rho containing singly charged extraframework cations, the (Ca,Li)—BePO material shows little
A discrete element model for kaolinite aggregate formation during sedimentation

The formation of colloidal aggregates during sedimentation is an important process when considering geotechnical and environmental engineering problems including wastewater treatment systems and slurry wall constructions for waste isolation. In this paper, a quasi three-dimensional discrete element framework is developed to model aggregate formation during sedimentation by considering the following microscopic inter-particle forces present in the clay–water–electrolyte system: van der Waals attraction, electrical double-layer repulsion, Born's repulsion, hydrodynamic viscous drag, and gravity. The role of these physico-chemical forces in the formation of clay clusters during sedimentation is investigated using an integrated numerical and experimental approach. The discrete element method (DEM) framework has been previously shown to accurately model clay behavior at the microscopic level. The model is validated with experimental data for comparison of distributions of aggregate density and aggregate size. Good agreement between the model prediction and the experimental results is obtained, suggesting that the DEM can be a powerful tool to better understand the aggregate formation process at the microscopic scale. For particle sizes ranging from 0.05 to 1 µm it is also shown, through numerical simulations, that ionic strength of the fluid medium is the controlling factor for aggregate size and density and that at aggregate sizes less than 20 µm, face-to-face interactions dominate the force regime between a pair of particles. Copyright © 2007 John Wiley & Sons, Ltd.
Assessment of Spring Wheat Genotypes for Disease Reaction to Rhizoctonia solani AG-8 in Controlled Environment and Direct-Seeded Field Evaluations

into undisturbed soil (Anonymous, 2001). Over 263 000 ha of cropland devoted to small grain production is now Rhizoctonia root rot, caused by Rhizoctonia solani Kuhn AG-8 under direct seed management in the PNW, of which (Anastomosis Group 8), is a yield limiting disease of direct-seeded cereal grains. The objectives of this study were to (i) determine 50% is planted to spring cereal grains (Pacific North- whether spring wheat (Triticum aestivum L.) genotypes vary in sus- west Direct Seed Association, 2001). Spring crops are ceptibility to Rhizoctonia root rot in inoculated field trials; and (ii) valuable in direct-seed systems due to the retention of evaluate whether disease ratings obtained by controlled environment undisturbed crop residue during the winter, when most (CE) analyses are predictive of disease ratings or genotype perfor- precipitation occurs in the PNW. Direct-seeding also mance in the field. Twenty-one spring wheat genotypes were evaluated maximizes soil water retention and increases water infil- for two crop years in a split-plot field study with high and low levels tration, which diminishes the risk of soil erosion while of disease pressure. The high-inoculum (high) treatment consisted of increasing crop productivity (Papendick, 1998). plots planted the previous fall with a 3:1 mixture of winter wheat and Attempts at grain production via direct-seeding in the oat (Avena sativa L.) grains colonized by the pathogen. The low- 1970s in the PNW failed due to problems associated inoculum (low) treatment was neither inoculated nor planted with a green bridge host the previous fall. Genotypes also were assayed with increased fertilizer requirements, rodent damage, for disease reaction in controlled environment (CE) assays. Average and increased pest and disease pressure (Papendick and disease ratings of field entries in the high treatment were 2.1 times Miller, 1977; Cook, 1991). Although direct-seed systems greater than those from the low treatment (P 0.05). The yield have evolved through the years to minimize these risks, average of entries in the high treatment was 87% of that of entries root diseases have resulted in tremendous yield and in the low treatment (P 0.001). Adult plant heights also were 5 cm crop quality losses when small grains are direct-seeded shorter (P 0.001), heading date was slightly delayed (P 0.05), into standing stubble of barley (Hordeum vulgare L.) and grain protein content decreased slightly (P 0.05) in the high or wheat (Wiese, 1987; Smiley et al., 1989; Cook, 1990, compared with the low treatment. Test weight was not affected by 1991; Cook and Haglund, 1991; Smiley, 1996). inoculum level. A statistically significant, negative association (P Rhizoctonia root rot, caused by the fungus R. solani
Neuroamine-derived alkaloids: Substrate-preferred inhibitors of rat brain monoamine oxidase in vitro

The effects of tetrahydropapaveroline (THP), salsolinol (SAL) and various hydroxylated and methoxylated tetrahydroprotoberberine (THPB) alkaloids on monoamine oxidase (MAO) forms A and B in rat brain homogenates were investigated. The substrates utilized were serotonin, a specific substrate for type A MAO; tyramine, a substrate for both type A and B MAO; and benzylamine, a preferred substrate for type B MAO. The concentrations of THP, SAL, 2,3,9,10-tetrahydroxyberbine and 2,3,10,11-tetrahydroxyberbine producing 50 per cent inhibition (I50) of the oxidation of serotonin were 1.0 mM, 0.25 mM, 0.24 mM and 0.04 mM, respectively. In marked contrast, the I50 concentrations of these alkaloids with benzylamine as substrate were 4.4 mM, 50 mM, 5.6 mM and 13 mM, respectively. These findings indicated that SAL and the tetrahydroxyberbines were substrate-preferred inhibitors of type A MAO whereas THP was a relatively nonspecific inhibitor of rat brain MAO. Kinetic data revealed that THP, SAL and 2,3,10,11-tetrahydroxyberbine inhibited the oxidation of serotonin in a typical competitive manner with apparent Ki values of 0.82 mM, 0.11 mM and 0.05 mM, respectively. THP and SAL noncompetitively inhibited benzylamine oxidation with apparent Ki values of 5.0 mM and 52 mM, respectively, while 2,3,10,11-tetrahydroxyberbine competitively inhibited the oxidation of benzylamine with an apparent Ki of 3.8 mM. Sequential replacement of the hydroxyl groups at the 2,3,9,10 and 11 positions of the berbine ring system by methoxyl groups substantially decreased the potency and selectivity of MAO inhibition. The interaction of these alkaloids with the metabolic pathways of neurotransmitters suggests that these compounds may be of relevance in the modification of central synaptic function.
Encoding the fine-structured mechanism of action potential dynamics with qualitative motifs

This work presents a neuroinformatic method for deriving mechanistic descriptions of fine-structured neural activity. This is a new development in the computer-assisted analysis of dynamics in conductance-based models, which is illustrated using single compartment models of an action potential. A sequence of abstract, qualitative motifs is inferred from this analysis, forming a template that is independent of the specific equations from which they were abstracted. The template encodes the assumptions behind the model reduction steps used to derive the motifs, and so specifies quantitative information about their domains of validity. The template representation of a mechanism is converted to a hybrid dynamical system, which is simulated as a sequence of low-dimensional reduced models (in this example, phase plane models) with appropriate switching conditions taken from the motifs. We demonstrate the validity of the template on a detailed single neuron model of spiking taken from the literature, and show that the corresponding hybrid system simulation closely mimics the spiking dynamics of the full model.
Synthesis, structure, and bonding of Eu3Bi(Sn,Bi)4. A rare inverse-Cr5B3-type structure with a new tin/bismuth network.

The ternary phase Eu3Bi(Sn1-xBix)4 ( approximately 0 0 probably originates with the electronic advantages of the pseudogap that would occur at the electron count of the ideal Zintl phase Eu3Bi(Sn3Bi). The stability of a competing phase reduces this limit to Eu3Bi(Sn3.4Bi0.6).
Paraneoplastic syndrome: a rare cause of gastrointestinal dysmotility.

77-year-old woman presented with 30 kg of Aprogressive weight loss during 12 months. She described recurrent episodes of regurgitation of undigested food immediately after intake. There was dysphagia, particularly to dry solid foods. These episodes were associated with colicky central abdominal pain, abdominal distention, and periods of constipation alternating with overflow diarrhea. She was diagnosed with limited-stage small cell lung cancer (SCLC) 5 years earlier for which she received chemotherapy and radiotherapy and continues to be in remission. On examination she was cachectic (weight, 43 kg; body mass index, 18.2 kg/m). Her abdomen was distended with scant bowel sounds. Laboratory tests revealed hypokalemia (3.3 mmol/L) and hypoalbuminemia (21 g/L). While she was in the hospital, her symptoms were refractory to antiemetics, laxatives, and prokinetics. She eventually required total parenteral nutrition. Computed tomography (Figure Ai [horizontal section], ii [coronal section]) of the abdomen showed moderately dilated small and large bowel loops with multiple air fluid levels and no transition point
Control of flying flexible aircraft using control surfaces and dispersed piezoelectric actuators

The flight of relatively stiff aircraft can be adequately controlled by standard means, i.e., by the engine throttles and control surfaces. When the flexibility becomes a factor, the standard controls may not be sufficient. In several earlier papers, the authors have addressed the problem of dynamics and control of maneuvering flexible aircraft. Using a perturbation approach they separated the problem into a quasi-rigid flight dynamics problem for the flight variables, which tend to be large, and an extended perturbation problem for the perturbations in the flight variables and the elastic vibration, which tend to be small, where the second problem receives input from the first. It was suggested in the earlier papers that, in addition to the standard controls, the controls for the extended perturbation problem include actuators whose task is to control the vibration. In this paper, the possibility of controlling the vibration by means of piezoelectric actuators dispersed over the flexible structural components, and in particular over the wing and empennage, is explored. It is concluded that piezoelectric actuators can be effective in damping out vibration if adequate power sources can be provided. This is the first time that the feasibility of piezoelectric actuators has been investigated in a flight environment.
Stimulation of protein tyrosine phosphorylation by the B-lymphocyte antigen receptor.

SIGNALLING by membrane immunoglobulin, the B-lymphocyte antigen receptor, regulates B-cell maturation and activation. Crosslinking of membrane immunoglobulin by antigen or by anti-immunoglobulin antibodies inactivates immature B cells, eliminating many of the B cells capable of producing auto-antibodies1. By contrast, crosslinking of membrane immunoglobulin promotes activation of mature B cells for clonal expansion and antibody production against foreign antigens2. Crosslinking membrane IgM on the immature B-cell line WEHI-231 induces growth arrest3. This response may be analogous to the deletion or inactivation of immature B cells that is induced by antigen or anti-IgM antibodies. Membrane immunoglobulin crosslinking stimulates phosphoinosi-tide hydrolysis, which leads to increases in intracellular calcium and activation of protein kinase C4–6. The induced phosphoinositide breakdown is important for inhibiting WEHI-231 growth (ref. 7 and D. Page, M.R.G., K. Fahey, L. Matsuuchi and A.L.D., manuscript submitted for publication), but may not be sufficient, as agents that elevate calcium and activate protein kinase C cause only partial growth arrest7. We now show that in both mature splenic B cells and the immature B–cell line WEHI-231 crosslinking membrane immunoglobulin also stimulates phosphorylation of protein tyrosine, a reaction that has been implicated as a key regulator of cell growth. Most of these phosphorylations were not a consequence of the phosphoinositide pathway. Thus, tyrosine phosphorylation is a second mode of transmembrane signalling by membrane immunoglobulin.
Pedagogical Aids in Textbooks: Do College Students' Perceptions Justify Their Prevalence?

Our study extends, Weiten, Guadagno, and Beck's (1996) research on the value of the pedagogical aids in introductory psychology textbooks. We asked 411 first-semester and advanced psychology students to rate each of 15 aids on familiarity, likelihood of use, and value. We also examined all full-length introductory psychology texts published between 1995 and 1997 to determine the prevalence of these aids. Although the 2 student groups generally agreed on the most and least useful aids, ratings did not consistently coincide with prevalence. We discuss how ratings may reflect students' concern with test preparation and call for empirical re-search on the relation between pedagogical aids and learning.
Prospecting for Strategic Advantage: The Proactive Entrepreneurial Personality and Small Firm Innovation

Our study proposed and tested an entrepreneurial process model that examined the interrelationships among a small firm owner's personality, strategic orientation, and innovation. In the first part of the model, it was posited that a proactive personality would directly influence a prospector strategic orientation. This type of strategic orientation would then be a key factor in determining the type of innovations introduced and implemented within the business. Using a sample of 107 small business owners, results revealed that the prospector strategy orientation mediated the relationship between proactive personality and three types of innovations: innovative targeting processes, innovative organizational systems, and innovative boundary supports. Implications for small business managers as well as future research directions are discussed.
Navigating chemical space for biology and medicine

Despite over a century of applying organic synthesis to the search for drugs, we are still far from even a cursory examination of the vast number of possible small molecules that could be created. Indeed, a thorough examination of all 'chemical space' is practically impossible. Given this, what are the best strategies for identifying small molecules that modulate biological targets? And how might such strategies differ, depending on whether the primary goal is to understand biological systems or to develop potential drugs?
Optical characterization of contrast agents for optical coherence tomography

The use of contrast agents in almost every imaging modality has been known to enhance the sensitivity of detection and improve diagnostic capabilities by site-specifically labeling tissues or cells of interest. The imaging capabilities of Optical Coherence Tomography (OCT) need to be improved in order to detect early neoplastic changes in medicine and tumor biology. We introduce and characterize the optical properties of several types of optical contrast agents in OCT, namely encapsulating microspheres that incorporate materials including melanin, gold, and carbon. Micron-sized microspheres have been fabricated by state-of-the-art sonicating and ultrasound technology. The optical properties of optical contrast agents have been characterized according to their scattering and absorption coefficients and lifetimes using OCT and the oblique incidence reflectometry method. Finally, we demonstrate the use of these optical contrast agents in in vitro mice liver and analyze the contrast improvement from the OCT images. These optical contrast agents have the potential to improve the detection of in vivo pathologies in the future.
Fine needle aspiration diagnosis of intraabdominal and retroperitoneal lymphomas by a morphologic and immunocytochemical approach

We reviewed 238 fine needle aspiration biopsies (FNA) of intraabdominal or retroperitoneal (IA/RP) masses in 192 patients with known or suspected lymphoma. A limited battery of immunocytochemical stains, including kappa (k) and lambda (l) light chains and Leu-4, was performed in 104 aspirates. On hundred twenty-eight of the FNA were diagnostic of or consistent with lymphoma, and three were diagnostic of carcinoma. Twenty-eight were considered negative for malignancy and 79 were suspicious for lymphoma or were nondiagnostic. For 135 of the FNA, a histologic biopsy specimen was available for comparison purposes. Overall, only one false-positive result was seen in a specimen lacking immunocytochemical data. The sensitivity of FNA lymphoma diagnosis was 66%. False-negative results due to sampling error were not uncommon, giving a predictive value of a negative result as 42%. The classification of the lymphomas by FNA was identical to that of the surgical biopsy in 86% of specimens and concurrently discrepant in 6%. We conclude that the routine performance of immunocytochemical studies on FNA of IA/RP masses is a feasible and valuable technique. Whereas suboptimal sensitivity and sampling error may make a negative diagnosis unreliable, lymphoma marker studies (combined with morphology) allow for an accurate and confident diagnosis and subclassification of lymphoma in the majority of cases.
An assessment of the pollution of cornish coastal waters

Abstract A detailed survey of pollution was undertaken in five areas around the Cornwall coast in south-west England, at St. Austell and Mevagissey Bays, Falmouth Bay, Mounts Bay, St. Ives Bay and Portreath. The aim of the study was to establish baseline values against which subsequent changes could be detected and their importance evaluated. Three major investigations were undertaken in each area involving seawater sampling and analysis, heavy metal analysis of seaweed specimens and quantitative surveys of intertidal fauna and flora. In general, the areas studied showed few signs of being exposed to significant levels of industrial or sewage pollution.
OMVPE growth of GaInAsSb/AlGaAsSb for quantum-well diode lasers

GaInAsSb and AlGaAsSb alloys have been grown by organometallic vapor phase epitaxy (OMVPE) using all organometallic sources, which include tritertiarybutylaluminum, triethylgallium, trimethylindium, tertiarybutylarsine (TBAs), and trimethylantimony. Excellent control of lattice-matching both alloys to GaSb substrates is achieved with TBAs. GaInAsSb/AlGaAsSb multiple quantum well (MQW) structures grown by OMVPE exhibit strong 4K photoluminescence with full width at half maximum of 10 meV, which is comparable to values reported for quantum well (QW) structures grown by molecular beam epitaxy. Furthermore, we have grown GaInAsSb/AlGaAsSb MQW diode lasers which consist of n- and p-doped Al0.59Ga0.41As0.05Sb0.95 cladding layers, Al0.28Ga0.72As0.02Sb0.98 confining layers, and four 15 nm thick Ga0.87In0.13As0.12Sb0.88 quantum wells with 20 nm thick Al0.28Ga0.72As0.02Sb0.98 barrier layers. These lasers, emitting at 2.1 µm, have exhibited room-temperature pulsed threshold current densities as low as 1.2 kA/cm2.
Responses of obese-hyperglycemic mice and normal mice to “bound” and crystalline insulin☆

Abstract The effects of bovine crystalline insulin and “bound” insulin obtained from human serum on glucose utilization in intact obese-hyperglycemic mice and their nonobese siblings and on their isolated epididymal adipose tissue have been studied. “Bound” insulin showed activity similar to that of crystalline insulin in control mice. It stimulated the incorporation of glucose into diaphragm glycogen in vivo and into epididymal adipose tissue glycogen and fat in intact mice and isolated epididymal fat pads. The utilization of glucose by obese-hyperglycemic mice was depressed when compared to controls in the presence of “bound” or crystalline insulin. In older obese and control mice, their ability to synthesize epididymal adipose fat decreased. The formation of diaphragm glycogen also decreased with age in the obese but not control mice.
Variable Property Effects in Laminar Natural Convection in a Square Enclosure

A numerical, finite-difference study has been carried out to determine the effects of variable properties on the temperature and velocity fields and the heat transfer rate in a differentially heated, two-dimensional square enclosure. Calculations have been done for a Rayleigh number range up to 106 , and temperature difference ratios θ0 = (TH –TC ) / TC of 0.2, 0.5, 1.0, and 2.0, where TH and TC are the hot and cold wall temperatures, respectively. Specific issues that have been addressed are the limits of validity of the Boussinesq approximation, the proper use of a reference temperature, variable property correlation of the heat transfer rate, and the limits of conduction-dominated regions.
Two-resource stochastic capacity planning employing a Bayesian methodology

We examine a stochastic capacity-planning problem with two resources that can satisfy demand for two services. One of the resources can only satisfy demand for a specific service, whereas the other resource can provide both services. We formulate the problem of choosing the capacity levels of each resource to maximize expected profits. In addition, we provide analytic, easy-to-interpret optimal solutions, as well as perform a comparative statics analysis. As applying the optimal solutions effectively requires good estimates of the unknown demand parameters, we also examine Bayesian estimates of the demand parameters derived via a class of conjugate priors. We compare the optimal expected profits when demands for the two services follow independent distributions with informative and non-informative priors, and demonstrate that using good informative priors on demand can significantly improve performance.
Compressed Air Energy Storage for Electricity Generation: ABSTRACT

Electric utilities attempt to meet fluctuating demands for power at lowest cost and with least consumption of premium fuel. Base-load coal and nuclear plants are designed to supply about 50% of maximum load. The remaining load is supplied by less efficient cycling generators which burn natural gas, petroleum, or coal. The compressed air energy storage (CAES) method reversibly converts electrical energy to mechanical energy. Air compressed with excess base-load capacity during off-peak periods is stored within an excavated geologic cavern or water-bearing porous rock formation. During peak-load periods, compressed air is released, mixed with fuel, burned, and expanded through turbines to generate power. CAES reduces conventional peaking plan consumption of petroleum by over 60%. Advanced conceptual plants could eliminate petroleum consumption by either (1) storing the heat of compression to reheat the compressed air, or (2) passing the compressed air through a pressurized fluidized coal-bed combustion chamber. CAES provides flexibility, frequency control, rapid start-up, and smaller impact on the en ironment than cycling plants. In California, potentially favorable geologic sites for CAES exist in depleted gas fields, depleted oil fields, saline aquifers, and hard rock formations. Economic benefit was evaluated using sensitivity analysis to identify how various parameters affect the bus-bar cost of electricity. Feasibility also depends upon the power generation cycle, experimental proof of operations in aquifer reservoirs, and institutional and legal clearances. The future potential for CAES is discussed with respect to the geology and population distributions of the Circum-Pacific region. End_of_Article - Last_Page 957------------
Silicone Gel Thermal Interface Materials for High Heat Dissipation and Thermo-Mechanical Stress Management for Good Reliability Performance

The recent trend in microprocessor architecture has been to increase the number of transistors (higher power), shrink processor size (smaller die), and increase clock speeds (higher frequency) in order to meet the market demand for high performance microprocessors. These have resulted in the escalation of power dissipation as well as the heat flux at the silicon die level. The Intel packaging technology development group has been challenged to develop packaging solutions that not only meet the package thermal targets but also the reliability requirements. As a result, an integrated heat spreading (IHS) package was developed, comprising a Cu based heat spreader and a first level thermal interface material (TIM) between the die and the heat spreader. Due to CTE mismatches between its different elements, the IHS package is subjected to high level of thermo-mechanical stresses which lead to severe failures post reliability testing. A significant amount of theoretical understanding of thermal resistance has been developed and applied to the development of TIM formulations, and it was found that the thermo-mechanical properties of the TIM material need to be optimized to mitigate the package reliability stresses. Several material and process solutions have been investigated using fundamental approaches, and, as a result of these efforts, low stress silicone gel TIM’s were developed. This paper provides an overview of the silicone gel TIM technologies investigated at Intel, and the key learnings from the fundamental material and package integration studies.Copyright © 2005 by ASME
On the two frequency spectra of Timoshenko beams

Abstract This paper is concerned with the question of whether there are, indeed, two distinct spectra of frequencies for the transverse vibrations of Timoshenko beams as has been claimed by a number of prior authors for the case of the simply supported beam and, more recently, for beams supported in an arbitrary manner. Elementary analysis leads to the conclusion that there is only a single frequency spectrum; in the particular case of the simply supported beam the “two frequency spectra” viewpoint may be expedient as a device to compute frequencies but does not serve otherwise to explain the complex, dynamical behavior of Timoshenko beams.
Bilateral effects of unilateral GDNF administration on dopamine- and GABA-regulating proteins in the rat nigrostriatal system.

Abstract Dopamine (DA) affects GABA neuronal function in the striatum and together these neurotransmitters play a large role in locomotor function. We recently reported that unilateral striatal administration of GDNF, a growth factor that has neurotrophic effects on DA neurons and enhances DA release, bilaterally increased striatal neuron activity related to locomotion in aged rats. We hypothesized that the GDNF enhancement of DA function and resulting bilateral enhancement of striatal neuronal activity was due to prolonged bilateral changes in DA- and GABA-regulating proteins. Therefore in these studies we assessed dopamine- and GABA-regulating proteins in the striatum and substantia nigra (SN) of 24 month old Fischer 344 rats, 30 days after a single unilateral striatal delivery of GDNF. The nigrostriatal proteins investigated were the DA transporter (DAT), tyrosine hydroxylase (TH), and TH phosphorylation and were examined by blot-immunolabeling. The striatal GABA neuron-related proteins were examined by assay of the DA D 1 receptor, DARPP-32, DARPP-32 Thr 34 phosphorylation, and glutamic acid decarboxylase (GAD). Bilateral effects of GDNF on TH and DAT occurred only in the SN, as 30 μg GDNF increased ser19 phosphorylation, and 100 μg GDNF decreased DAT and TH protein levels. GDNF also produced bilateral changes in GAD protein in the striatum. A decrease in DARPP-32 occurred in the ipsilateral striatum, while increased D 1 receptor and DARPP-32 phosphorylation occurred in the contralateral striatum. The 30 μg GDNF infusion into the lateral striatum was confined to the ipsilateral striatum and substantia nigra. Thus, long-lasting bilateral effects of GDNF on proteins regulating DA and GABA neuronal function likely alter physiological properties in neurons, some with bilateral projections, associated with locomotion. Enhanced nigrostriatal excitability and DA release by GDNF may trigger these bilateral effects.
Macroglobulin complement-related encodes a protein required for septate junction organization and paracellular barrier function in Drosophila

Polarized epithelia play crucial roles as barriers to the outside environment and enable the formation of specialized compartments for organs to carry out essential functions. Barrier functions are mediated by cellular junctions that line the lateral plasma membrane between cells, principally tight junctions in vertebrates and septate junctions (SJs) in invertebrates. Over the last two decades, more than 20 genes have been identified that function in SJ biogenesis in Drosophila, including those that encode core structural components of the junction such as Neurexin IV, Coracle and several claudins, as well as proteins that facilitate the trafficking of SJ proteins during their assembly. Here we demonstrate that Macroglobulin complement-related (Mcr), a gene previously implicated in innate immunity, plays an essential role during embryonic development in SJ organization and function. We show that Mcr colocalizes with other SJ proteins in mature ectodermally derived epithelial cells, that it shows interdependence with other SJ proteins for SJ localization, and that Mcr mutant epithelia fail to form an effective paracellular barrier. Tissue-specific RNA interference further demonstrates that Mcr is required cell-autonomously for SJ organization. Finally, we show a unique interdependence between Mcr and Nrg for SJ localization that provides new insights into the organization of the SJ. Together, these studies demonstrate that Mcr is a core component of epithelial SJs and also highlight an interesting relationship between innate immunity and epithelial barrier functions.
Clomipramine and EEG sleep in depression

Recent studies with clomipramine (CMI) have demonstrated that a pulse-loading approach is associated with a rapid improvement in symptomatology in the absence of continuous treatment. In the present study, sleep changes were evaluated to ascertain the rapidity of clomipramine's effect on electroencephalographic sleep, especially rapid eye movement (REM) and delta wave sleep measures. Clomipramine produced rapid changes in sleep with reduced sleep continuity and almost complete suppression of REM sleep as well as a redistribution of slow wave sleep. Delta waves during sleep were also found to be shifted to the earlier part of the night and increased in intensity. Spectral analysis revealed an increase in power in the delta frequency range that was correlated with clinical responsiveness. These studies point toward a role for clomipramine in the rapid treatment of depression and confirm that sleep physiology may be a good predictor of antidepressant action.
Mutant cell lines resistant to azetidine-2-carboxylic acid: alterations in the synthesis of proline from glutamic acid

Two mutant Chinese hamster lung fibroblast lines have been isolated that are resistant to the toxic proline analog L-azetidine-2-carboxylic acid. The line designated AZCA-1 has 30-fold elevated activity of pyrroline-5-carboxylate synthase and a large increase in the rate of proline production and release compared to controls. Pyrroline-5-carboxylate synthase activity is not elevated in the resistant line designated AZCA-4, but the enzyme is less sensitive to inhibition by ornithine and proline than control enzyme. Intracellular proline is elevated in AZCA-4 cells, with no change in the rate of release of proline synthesized from glutamate. Resistance to azetidine carboxylic acid in both mutant lines is attributed to the expanded intracellular proline pool that results from alterations in pyrroline-5-carboxylate synthase. These results indicate that intracellular proline levels are determined at least in part by the regulated activity of pyrroline-5-carboxylate synthase.
The density integration approach to populations. A critical comparison of projection populations to populations defined by the theory of atoms in molecules

The theory of atoms in molecules defines an unambiguous partitioning of the three-dimensional electron density into atomic basins based on the zero-flux surfaces of the gradient of the electron density, ∇(r). Integrations of the electron density within such basins yield integrated Bader populations (IBP) that have a rigorous foundation in quantum mechanics. In the density integration technique based on the two-dimensional electron density projection function, P(x,z), integrated projection populations (IPP) are obtained by integration within regions demarked by steepest descent lines Dp of P(x,z). These density integration techniques are compared by an analysis of the electron density of diatomic molecules that is based on the properties of the zero-flux surface that partitions the electron density between the atoms. The conventional method for the partitioning of regions of P(x,z) approximates the virial partitioning. Differences between IPP and IBP can be quantitatively described by two terms. One term reflects the error intrinsic to projection populations as a result of the loss of all information about the electron distribution in the third dimension in the calculation of P(x,z). The second term accounts for the effects of the displacement of the demarcation lines Dp toward the less polarizable atom compared with the cross-section of the density with the plane of projection, Dd. The analysis suggests the definition of a projection population IPP2 that is based on the cross-section Dd instead of the demarcation lines Dp. Relations between the populations IPP, IPP2, and IBP are derived for diatomic molecules and numerical results are presented for a series of diatomic molecules. Several polyatomic anions are also discussed. The values of IPP are found to be good approximations of IBP in highly polar diatomic molecules. In cases where the bonding involves comparatively little intramolecular charge transfer IPP2 is the better and equally satisfactory projection population. In the intermediate semipolar bonding situations projection populations provide qualitatively correct descriptions of the charge distributions but the numerical agreement with the IBP values is less satisfactory.
Gram-scale, high-yield synthesis of a robust metal–organic framework for storing methane and other gases

We have synthesized and characterized a new metal–organic framework (MOF) material, NU-125, that, in the single-crystal limit, achieves a methane storage density at 58 bar (840 psi) and 298 K corresponding to 86% of that obtained with compressed natural gas tanks (CNG) used in vehicles today, when the latter are pressurized to 248 bar (3600 psi). More importantly, the deliverable capacity (58 bar to 5.8 bar) for NU-125 is 67% of the deliverable capacity of a CNG tank that starts at 248 bar. (For crystalline granules or powders, particle packing inefficiencies will yield densities and deliverable capacities lower than 86% and 67% of high-pressure CNG.) This material was synthesized in high yield on a gram-scale in a single-batch synthesis. Methane adsorption isotherms were measured over a wide pressure range (0.1–58 bar) and repeated over twelve cycles on the same sample, which showed no detectable degradation. Adsorption of CO2 and H2 over a broad range of pressures and temperatures are also reported and agree with our computational findings.
Thioredoxin reductase 1 deficiency reverses tumor phenotype and tumorigenicity of lung carcinoma cells

Dietary selenium has potent cancer prevention activity. Both low molecular weight selenocompounds and selenoproteins are implicated in this effect. Thioredoxin reductase 1 (TR1) is one of the major antioxidant and redox regulators in mammals that supports p53 function and other tumor suppressor activities. However, this selenium-containing oxidoreductase is also overexpressed in many malignant cells and has been proposed as a target for cancer therapy. To further assess the role of TR1 in the malignancy process, we used RNA interference technology to decrease its expression in mouse lung carcinoma (LLC1) cells. Stable transfection of LLC1 cells with a small interfering RNA construct that specifically targets TR1 removal manifested a reversal in the morphology and anchorage-independent growth properties of these cancer cells that made them similar to those of normal cells. The expression of at least two cancer-related protein mRNAs, Hgf and Opn1, were reduced dramatically in the TR1 knockdown cells. Mice injected with the TR1 knockdown showed a dramatic reduction in tumor progression and metastasis compared with those mice injected with the corresponding control vector. In addition, tumors that arose from injected TR1 knockdown cells lost the targeting construct, suggesting that TR1 is essential for tumor growth in mice. These observations provide direct evidence that the reduction of TR1 levels in malignant cells is antitumorigenic and suggest that the enzyme is a prime target for cancer therapy.
High throughput screening of co-expressed gene pairs with controlled false discovery rate (FDR) and minimum acceptable strength (MAS).

Motivation: Many exploratory microarray data analysis tools such as gene clustering and relevance networks rely on detecting pairwise gene co-expression. Traditional screening of pairwise co-expression either controls biological significance or statistical significance, but not both. The former approach does not provide stochastic error control, and the later approach screens many co-expressions with excessively low correlation. Methods: We have designed and implemented a statistically sound two-stage co-expression detection algorithm that controls both statistical significance (False Discovery Rate, FDR) and biological significance (Minimum Acceptable Strength, MAS) of the discovered co-expressions. Based on estimation of pairwise gene correlation, the algorithm provides an initial co-expression discovery that controls only FDR, which is then followed by a second stage co-expression discovery which controls both FDR and MAS. It also computes and thresholds the set of FDR p-values for each correlation that satisfied the MAS criterion. Results: We validated asymptotic null distributions of the Pearson and Kendall correlation coefficients and the twostage error-control procedure using simulated data. We then used yeast galactose metabolism data (Ideker et al. 2001) to illustrate the advantage of our method for clustering genes and constructing a relevance network. In gene clustering, the algorithm screens a seeded cluster of co-expressed genes with controlled FDR and MAS. In constructing the relevance network, the algorithm discovers a set of edges with controlled FDR and MAS. Availability: The method has been implemented in an R package ”GeneNT” that is freely available from: http://wwwpersonal.umich.edu/ v zhud/genent.htm.
A Generalized Framework for Network Component Analysis

The authors recently introduced a framework, named network component analysis (NCA), for the reconstruction of the dynamics of transcriptional regulators' activities from gene expression assays. The original formulation had certain shortcomings that limited NCA's application to a wide class of network dynamics reconstruction problems, either because of limitations in the sample size or because of the stringent requirements imposed by the set of identifiability conditions. In addition, the performance characteristics of the method for various levels of data noise or in the presence of model inaccuracies were never investigated. In this article, the following aspects of NCA have been addressed, resulting in a set of extensions to the original framework: 1) The sufficient conditions on the a priori connectivity information (required for successful reconstructions via NCA) are made less stringent, allowing easier verification of whether a network topology is identifiable, as well as extending the class of identifiable systems. Such a result is accomplished by introducing a set of identifiability requirements that can be directly tested on the regulatory architecture, rather than on specific instances of the system matrix. 2) The two-stage least square iterative procedure used in NCA is proven to identify stationary points of the likelihood function, under Gaussian noise assumption, thus reinforcing the statistical foundations of the method. 3) A framework for the simultaneous reconstruction of multiple regulatory subnetworks is introduced, thus overcoming one of the critical limitations of the original formulation of the decomposition, for example, occurring for poorly sampled data (typical of microarray experiments). A set of Monte Carlo simulations we conducted with synthetic data suggests that the approach is indeed capable of accurately reconstructing regulatory signals when these are the input of large-scale networks that satisfy the suggested identifiability criteria, even under fairly noisy conditions. The sensitivity of the reconstructed signals to inaccuracies in the hypothesized network topology is also investigated. We demonstrate the feasibility of our approach for the simultaneous reconstruction of multiple regulatory subnetworks from the same data set with a successful application of the technique to gene expression measurements of the bacterium Escherichia coli.
Rapid growth and strain rates inferred from synkinematic garnets, Penokean orogeny, Minnesota

Recent reinterpretations of the Early Proterozoic Penokean orogeny in Minnesota invoke a plate-tectonic model with characteristics similar to Phanerozoic collisional belts. Deformation during collision produced large flattening strains (-89%) and the development of a tectonic foliation and progressive metamorphism up to amphibolite facies, as indicated by the presence of synkinematic (S1) garnets. Biotite-garnet thermometry and plagioclase-garnet-biotite-muscovite barometry give southward-increasing temperatures and pressures and indicate burial to depths of ≥21-25 km, similar to medial and internal zones of collisional orogens worldwide. Gibbs Method modeling on zoned synkinematic garnets indicates virtually no change in pressure ( P ) or temperature ( T ) during garnet growth. Growth and rotation of garnets at a point in P-T space in an actively evolving deformational and thermal regime are surprising and suggest rapid garnet growth rates and high rates of strain during orogeny. This is consistent with previous studies that indicate more rapid rates of tectonometamorphic processes in the Precambrian relative to younger orogenic belts.