cssi/SciSciGPT-SciSciNet huggingface dataset:
Properties of Hot-Melt Extruded Theophylline Tablets Containing Poly(Vinyl Acetate)

The objectives of this study were to investigate the properties of poly(vinyl acetate) (PVAc) as a retardant polymer and to study the drug release mechanism of theophylline from matrix tablets prepared by hot-melt extrusion. A physical mixture of drug, polymer, and drug release modifiers was fed into the equipment and heated inside the barrel of the extruder. The cylindrical extrudates were either cut into tablets or ground into granules and compressed with other excipients into tablets. Due to the low glass transition temperature of the PVAc, the melt extrusion process was conducted at approximately 70°C. Theophylline was used as the model drug in this study. Theophylline was present in the extrudate in its crystalline form and was released from the tablets by diffusion. The Higuchi diffusion model and percolation theories were applied to the dissolution data to explain the drug release properties of the matrix systems. The release rate was shown to be dependent on the granule size, drug particle size, a...
Senate hearing considers Law of the Sea treaty

The U.S. Senate Committee on Foreign Relations is once again discussing the Law of the Sea Convention (LOS). The treaty, which was adopted in 1982 by parties to a United Nations Conference as a framework for governing uses of the world's oceans, has been ratified by more than 160 countries, but the United States is a notable exception. The treaty has been approved twice by the Foreign Relations Committee but has not made it to a full Senate vote because of opponents' concerns about potential loss of U.S. sovereignty and U.S. access to the deep seabed, among other reasons. During a 23 May hearing of the committee, chairman John Kerry (D-Mass.), a strong supporter of the treaty, said U.S. ratification “is now more urgent than ever” and that to remain outside of the treaty “is fundamentally, directly counter to the best interests” of the United States.
STUDIES OF SPERMIOGENESIS IN A NEMATODE, NIPPOSTRONGYLUS BRASILIENSIS

The fine structure of the developing spermatids and the mature sperm of Nippostrongylus brasiliensis was investigated. Immature spermatids are found at one end of the tubelike testis, and the mature sperm at the other. The spermatid has a prominent nucleus, with the chromatin clumped at the margin. It also contains a pair of centrioles, located near the nucleus. The cytoplasm is filled with ribosomal clusters, but it lacks an organized Golgi area or endoplasmic reticulum. Besides the normal mitochondria, the spermatid has specialized mitochondrionlike inclusions with dense matrix, few broad cristae, and a crystalloid structure always facing the nucleus. As spermiogenesis proceeds, the nucleus elongates, comes to lie at one end, and later evaginates to form a separate head structure, leaving the mitochondria and other cytoplasmic organelles in a broad cytoplasmic region. The nuclear material becomes filamentous and spiral, and the centrioles come to lie at one end near the junction of the head and the cytoplasmic portion of the sperm. Microtubules are found in the cytoplasmic region extending from the tubelike nucleus. The specialized mitochondria are about eighteen in number, and are arranged in rows in staggered groups of three around the microtubules in the cytoplasmic region. The mature sperm is aflagellate and lacks an acrosome. No movement of the sperm was ever observed.
‘Yo, it’s IST yo’: The discursive construction of an Indian American youth identity in a South Asian student club

This study analyzes interactions among members of a South Asian Club (SAC) at an American university to illustrate how members construct a common Indian-American identity despite observable in-group differences. Members of this second-generation group differentiate themselves from White Americans and from natives of India, orienting to notions of both American model minority status and American youth culture and using humor as a strategy to downplay intra-Indian differences among themselves. While members of this student association succeed in achieving proud Indian-American youth identities – cool, socially mobile, and with cultural ties to another country – they unwittingly reinforce hegemonic racial structures in the United States. While ‘Indian-American’ is a positive identity for these students, it is also a racially marked identity that necessarily, however unintentionally, excludes them from the unmarked privileges of Whiteness.
Comparison of amount of myocardial cell disorganization in operatively excised septectomy specimens with amount observed at necropsy in 18 patients with hypertrophic cardiomyopathy.

Abstract The extent of cardiac muscle cell disorganization in excised septectomy specimens in 18 patients was compared morphometrically with that observed at necropsy when these patients died after operation. Disorganization was present in all 18 patients at necropsy and was extensive (5 percent or greater) in 16 of the 18. In contrast, there was no disorganization in the operative specimens of three patients and only a trivial amount (less than 1 percent) in five others. Disorganization extensive enough (5 percent or greater) to suggest hypertrophic cardiomyopathy was present in the operative specimens of only 6 of the 18 patients. The mean (± standard error of the mean) area of disorganization at necropsy was 20 ± 3 percent compared with 7 ± 2 percent in the operative specimens (p
Sperm storage in Spermathecae of the great lamper eel, Amphiuma tridactylum (Caudata: Amphiumidae).

The spermathecae of ten female Amphiuma tridactylum were examined by light and electron microscopy during the presumed mating and ovipository seasons (March-August) in Louisiana. Spermathecae were simple tubuloalveolar glands in the dorsal wall of the cloaca. Six of the ten specimens were vitellogenic, and all of these specimens contained sperm in their sperma- thecae and had secretory activity in the spermathecal epithelium. Two nonvitel- logenic females also had sperm in their spermathecae and active epithelial cells, whereas the other nonvitellogenic females lacked stored sperm and secretory activity in the spermathecae. In specimens storing sperm from March-May, the sperm were normal in cytology, and secretory vacuoles were contained within the epithelium. In the August sample, however, evidence of sperm degradation was present, and secretory material had been released into the lumen by an apocrine process. We therefore hypothesize that the spermathecal secretions function in sperm degeneration. Q 1996 Wiley-Liss, Inc. The Amphiumidae consists of three spe- cies of Amphiuma, elongate, fossorial sala- manders with reduced limbs and one exter- nal gill slit, a paedomorphic character (Duellman and Trueb, '86). Two of the spe- cies are aquatic and often exceed 70 cm snout- vent length (SVL); A. means occurs in the coastal plain from Virginia to Louisiana, and A. tridactylum occurs from western Alabama to Texas and up the Mississippi River valley to western Kentucky. A. phloleter is a dwarf (20-25 cm SVL), terrestrial species limited to the Florida panhandle and southern Ala- bama (Conant and Collins, '91). In the Missis- sippi River valley, A. tridactylum is com- monly called the "great lamper eel" (Parker, '37; Baker, '45; Dundee and Rossman, '89). A number of reports exist on the reproduc- tive biology of Amphiuma, but most of these are anecdotal and some are contradictory (Table 1). The majority of the literature con- cerns A. tridactylum. Sperm in the female cloaca was first observed by Davison (1895). The only report of mating behavior is an observation of copulation by cloacal apposi- tion (Baker et al., '47). Sperm storage glands, spermathecae, in the female cloaca were first described by Kreeger ('42), and Sever ('92a) extended her observations on spermathecae of
Reading and listening comprehension in broca's aphasia: lexical versus syntactical errors.

Abstract Ten agrammatic Broca's aphasics were presented with a series of four picture plates together with a spoken or written sentence stimulus. All sentence stimuli were of the structure, the + N + is/are + V + ing + the + N. The four pictures on each stimulus plate represented (a) the correct response, (b) a reversal of the stimulus sentence subject and object, (c) a change in the number of the subject of the stimulus sentence, and (d) a change in one of the major lexical items of the stimulus sentence. Subjects selected the correct picture most often. When they erred, they usually selected a subject-object reversal. Number errors were less frequent, and the patients seldom selected a change in major lexical item. This pattern occurred with both written and spoken sentences. These results were interpreted as reflecting the dependence of agrammatic Broca's aphasics on the semantic interpretation of the lexicon for decoding sentences in the face of deficits in syntactical-grammatical interpretation, irrespective of comprehension modality.
Optimal Test Scheduling of Stacked Circuits under Various Hardware and Power Constraints

As Integrated Circuits (ICs) become more complex through smaller semiconductor feature sizes and higher performance requirements, the thorough testing of silicon devices is becoming a greater economic challenge. System-on-Chip (SoC) test schedules not only need to achieve the shortest possible test application time, they must also satisfy new design constraints which are increasing test scheduling complexity, such as device power. Although many past studies of SoC test scheduling have addressed individual issues during test, none have present a model of test scheduling that has allowed for many different constraints to be enforced at once. By presenting a test scheduling formulation that allows the enforcement of many separate power and hardware constraints, including issues of test pins, as well as allowing the use of modern Dynamic Voltage and Frequency Scaling (DVFS) hardware to further compact test schedules, this study provides a generalized test scheduling formulation that will not only allow the enforcement of multiple testing constraints but will also allow for the further compaction of test schedules and reduction of test cost.
Accurate Intraprotein Electrostatics Derived from First Principles: An Effective Fragment Potential Method Study of the Proton Affinities of Lysine 55 and Tyrosine 20 in Turkey Ovomucoid Third Domain

A divide-and-conquer method by which an accurate static and induced multipole representation of the electrostatic potential of a protein can be generated using ab initio electronic structure theory is presented. The method is applied to the generation of an effective fragment potential (J. Chem. Phys. 1996, 105, 1968) for the protein turkey ovomucoid third domain. Dipoles and induced dipoles are necessary for accurate intraprotein electrostatics, as measured by their effects on the gas-phase proton affinities (PAs) of the amino acid residues lysine 55 (Lys55) and tyrosine 20 (Tyr20). Deprotonation of Tyr20 is predicted to result in spontaneous proton transfer from Lys55 to Tyr20, which thus have identical PAs. It is suggested that the experimentally measured (identical) pKas of Tyr20 and Lys55 might be identical for the same reason.
A dipolar amino acid substitution induces voltage-dependent transitions between two stable conductance states in gramicidin channels

O' .. HN hydrogen bonds, andthe channel appearances are usually denoted by stable(onthems tostimescale) rectangularcurrenttransitionswith a single predominantconductingstate (e.g., SawyeretaI., 1989). (Gramicidinchannelsexhibitbrief"flickers"to a low-conductancestate with an average duration of-1J1.S (Heinemann and Sigworth [1991]; these eventswill not concern us here.) Gramicidin channels aregenerally presumed to be voltage independent, but wehave recently found that some types of asymmetrical(heterodimeric) gramicidin channels exhibit voltage­dependent transitions between (at least) two conduc­tancestates.These channels were discovered in an attempt todiscern why heterodimers formed by [F6Vall]gramicidinA ([F6Vall]gA, in which YaP is replaced by 4,4,4,4',4',4'­hexafluorovaline), and [Vall]gA are energetically desta­bilized relative to the symmetrical parent channels(Russell et aI., 1986; Durkin et aI., 1990). From theheterodimer appearance rate it could be concluded that[F6VaP]gA forms
Agrobacterium-Mediated Transformation of Walnut Somatic Embryos and Regeneration of Transgenic Plants

Genetically transformed walnut plants were regenerated from somatic embryos inoculated with a disarmed Agrobacterium tumefaciens strain containing a gene encoding kanamycin resistance. Embryo subclones derived from the inoculated embryos were selected for continued embryo proliferation on kanamycin-containing medium. Embryos and shoots were shown to contain and express the foreign gene and have been subjected to rooting procedures. Four rooted plantlets have been transplanted to soil and acclimatized. This is the first report of the successful transformation of a woody tree species from somatic embryos using Agrobacterium.
ST101 induces a novel 17 kDa APP cleavage that precludes Aβ generation in vivo.

Objective: Inhibiting Aβ generation is a prime therapeutic goal for preventing or treating Alzheimer disease. Here we sought to identify any disease-modifying properties of an azaindolizinone derivative, spiro[imidazo[1,2-a]pyridine-3,2-idan]-2(3H)-one (ST101 or ZSET1446). Methods: The effects of ST101 were studied in 3xTg-AD mice and young cynomolgus monkeys using a combination of biochemical and histological analyses. Results: Here we describe that ST101 induces cleavage of APP protein at a novel site, generating a 17kDa C-terminal fragment. This 17kDa APP cleavage product does not appear to be a substrate for either α- or β-secretase, and thus bypasses generation of Aβ. ST101 is orally active, efficacious at low doses, improves memory function, and robustly reduces brain Aβ in transgenic mice and nonhuman primates. Interpretation: Using rodent and nonhuman primate models, we show that ST101 represents a novel class of small molecules that reduce central nervous system levels of Aβ by inducing an alternate pathway of APP cleavage. ANN NEUROL 2010;
Alkali-free glass as a high energy density dielectric material

Abstract One of the greatest challenges in the development of new high energy density materials is to increase dielectric permittivity while maintaining high breakdown strength. The dielectric breakdown behavior of an alkali-free barium boroaluminosilicate glass is shown to have remarkably high DC dielectric breakdown strength (12 MV/cm) and reasonably high permittivity (~ 6), equating to energy densities in excess of 35 J/cm 3 . This behavior is attributed to highly polarizable Ba ions enhancing the real part of complex permittivity, the low loss due to the alkali-free composition, and the substantially defect-free quality of the glass and its surfaces. To our knowledge, this is the highest breakdown strength reported for a bulk glass, and rivals the breakdown strength more typically observed in pristine thin films of SiO 2 . These findings indicate that alkali-free multicomponent glasses may be strong candidates for next-generation high energy density storage capacitors for portable or pulsed power applications.
Inconsistency of Nordström-type theories of gravitation with the principle of equivalence

In a recently published paper, the writer reconstructed an unpublished argument due to Einstein showing the first Nordstrom theory of gravitation to be in violation of the principle of equivalence because a rotating object would fall with lesser acceleration than a nonrotating object in a static, homogeneous, gravitational field. It has been suggested that this effect is that found by Papapetrou in his study of the motion of spinning particles in the general theory of Einstein. It is shown here that the effect is 1) present in any theory of the Nordstrom type and 2) not dependent on rotation as such but on the essential dependence of acceleration in one direction on the velocity in the transverse direction.
Planning Dental Treatment for People with Special Needs

People with disabilities and other special needs present unique challenges for oral health professionals in planning and carrying out dental treatment. This article presents a schema for planning dental treatment that encourages the oral health provider to fully consider multiple medical, social, psychologic and dental findings when preparing treatment recommendations for a patient with special needs. If these factors are fully integrated, the resulting treatment recommendations provide the best chance of helping the individual achieve and maintain a lifetime of oral health
The Role of Human Capital in Scaling Social Entrepreneurship

In this article, we discuss the importance of human assets in growing and scaling a social venture in order to achieve its objectives and attain financial sustainability. We focus on the three key dimensions of how a social enterprise’s human assets contribute to the effectiveness of the company’s operations and its missions: 1) human capital acquisition, 2) human capital development, and 3) human capital retention. In discussing and unpacking these three dimensions, we draw from rich insights and real- life examples from two social ventures we studied: Solar Sister of Uganda and E-Health Point of India. These inductively-generated research insights underscore the importance of productive engagement of human assets for the long-term viability of social ventures and in achieving their objectives on a broader social scale.
Tunneling spectroscopy of Stark-shifted image potential states on Cu and Au surfaces

Using low-temperature scanning tunneling microscopy (STM) distance-voltage characteristics at constant current are measured on Cu(111), Cu(110), Au(111), and Au(100) surfaces. Resonant tunneling features are observed that arise from image potential states distorted by the strong electric field of the STM tip. Distance-voltage characteristics are measured over a wide range of current setpoints and the energetic position and width of the resonant features show a significant dependence on this parameter. The lowest energy feature is found to be nearly independent of STM tip condition, while higher energy resonances show substantial tip dependence. The results are discussed and compared with recent calculations.
Experimental manipulation of TN:TP ratios suppress cyanobacterial biovolume and microcystin concentration in large-scale in situ mesocosms

Abstract A global dataset was compiled to examine relations between the total nitrogen to total phosphorus ratio (TN:TP) and microcystin concentration in lakes and reservoirs. Microcystin concentration decreased as TN:TP ratios increased, suggesting that manipulation of the TN:TP ratio may reduce microcystin concentrations. This relationship was experimentally tested by adding ammonium nitrate to increase the TN:TP ratio in large-scale (70 m3), in situ mesocosms located in a eutrophic reservoir that routinely experiences toxic blooms of cyanobacteria. At a TN:TP ratio >75:1, chlorophytes dominated the phytoplankton community in the mesocosms, while cyanobacterial biovolume was significantly reduced and microcystin was not detected. In contrast, the unmanipulated reservoir was dominated by cyanobacteria, and microcystin was detected. Secchi depths were 1.1 to 1.8 times greater in the mesocosms relative to the reservoir. Cladoceran zooplankton had a larger body size (0.14 mm on average) in the mesocosms com...
Thin film thermocouple arrays for sliding surface temperature measurement

Abstract Methods for measurement of sliding surface temperatures using thin film thermocouples (TFTCs) were developed and are described in this paper. Multi-junction copper–nickel TFTCs have been made using thin film deposition techniques. A thin hard dielectric coating was deposited on the TFTC for sensor protection. The thin film thermocouple sensors have been used to measure surface temperatures accurately in a variety of sliding contact situations including oscillatory sliding in a reciprocating seal configuration and unidirectional sliding in a rotary face seal configuration. Tests were run under liquid-lubricated as well as dry sliding conditions. In all of the tests, one of the test specimens (the moving one) was made from a thermoplastic polymer, ultra-high molecular weight polyethylene (UHMWPE). The surface temperature was measured during the tests at a number of points on the counterface, using an array of TFTCs. Correlation with analytical results was made and good agreement with theory was found. The total surface temperature measured in the tests has contributions from both flash (local) temperature rise and large-scale (nominal) temperature rise. The local surface temperature rise was found to be similar for both dry and liquid-lubricated cases, as long as the frictional heat input was the same. The nominal temperature rise was, however, considerably lower in the lubricated case owing to more efficient convective cooling.
Flexural vibration of rectangular plates subjected to sinusoidally distributed compressive loading on two opposite sides

Natural frequencies and mode shapes of rectangular plates subjected to sinusoidally distributed in-plane compressive loading on two opposite edges were considered in this work. Although vibration analysis of rectangular plates was investigated by numerous authors, flexural vibration of plates with nonlinearly distributed in-plane loading received much less attention. However, certain problems involving thermal stresses may have such nonlinear loading conditions in the plane of the plate. The analysis procedure for the title problem involves first finding a plane elasticity solution for the in-plane problem satisfying all boundary conditions. Then using this in- plane solution, flexural vibration analysis has to be carried out. In a related work investigated recently by the present authors, an in-plane elasticity solution was developed and was compared with existing analytical solutions in the literature and with the finite element method. One aspect of this study was the stress diffusion (i.e., reduction of stress) phenomenon along the length of the plate as well as the presence of all three in-plane stress components. Using this in-plane solution, vibration analysis of rectangular plates was carried out for various plate aspect ratios and the results were compared with corresponding values from finite element analysis.
Structural studies of the putative helix 8 in the human β2 adrenergic receptor: an NMR study

Abstract The recently reported crystal structure of bovine rhodopsin revealed a cytoplasmic helix (helix 8) in addition to the seven transmembrane helices. This domain is roughly perpendicular to the transmembrane bundle in the presence of an interface and may be a loop-like structure in the absence of an interface. Several studies carried out on this domain suggested that it might act as a conformational switch between the inactive and activated states of this G-protein coupled receptor (GPCR). These results raised the question whether helix 8 may be an important feature of other GPCRs as well. To explore this question, we determined the structure of a peptide representing the putative helix 8 domain in another receptor that belongs to the rhodopsin family of GPCRs, the human β2 adrenergic receptor (hβ2AR), using two-dimensional 1H nuclear magnetic resonance (NMR). The key results from this structural study are that the putative helix 8 domain is helical in detergent and in DMSO while in water this region is disordered; the conformation is therefore dependent upon the environment. Comparison of data from five GPCRs suggests that these observations may be generally important for GPCR structure and function.
Experimental study of chemical conversion of methanol and ethylene glycol in a film boiling reactor

Abstract Film boiling on a horizontal tube is used to convert methanol and ethylene glycol to synthesis gas and other species by thermal decomposition and catalytic reaction. Methanol reacts on a platinum catalyst to form CO and H 2 in near stoichiometric proportions while ethylene glycol products include additional condensable and soluble species. The influence of catalyst degradation on prolonged operation is suggested as a cause for some of the trends observed. Product yields for thermal decomposition of methanol are quite repeatable while for ethylene glycol significant carbon deposits appear to produce greater variability in the measured product flow rates.
A weave of time: The story of a Navajo family

The Navajo (or Dine’, as they call themselves) were decimated by their Long Walk in the 1860s, but the survivors soon returned to their homeland, bounded by sacred mountains in the high deserts of ...
Evaluation of Xanthan Gum in the Preparation of Sustained Release Matrix Tablets

AbstractThe objective of this study was to evaluate xanthan gum as a matrix former for the preparation of sustained release tablets. Preliminary experiments indicated that a fine particle sue of xanthan gum produced the slowest and most reproducible release profiles. Based on single surface experiments and tablet erosion studies, it was concluded that release of a soluble drug (chlorpheniramine maleate) and an insoluble drug (theophylline) from tablets containing low concentraions of xanthan gum was mainly via diffusion and erosion, respectively. Drug release from tablets containing xanthan gum was slightly faster in acidic media due to more rapid initial surface erosion than at higher pH. After hydration of the gum, drug release was essentially pH-independent. The amount released was directly proportional to the loading dose of drug and inversely proportional to gum concentration in tablets. Release profiles of chlorpheniramine maleate and theophylline remained unchanged after three months storage of the...
Canine stifle joint biomechanics associated with tibial plateau leveling osteotomy predicted by use of a computer model.

Objective—To evaluate effects of tibial plateau leveling osteotomy (TPLO) on canine stifle joint biomechanics in a cranial cruciate ligament (CrCL)–deficient stifle joint by use of a 3-D computer model simulating the stance phase of gait and to compare biomechanics in TPLO-managed, CrCL-intact, and CrCL-deficient stifle joints. Sample—Computer simulations of the pelvic limb of a Golden Retriever. Procedures—A previously developed computer model of the canine pelvic limb was used to simulate TPLO stabilization to achieve a tibial plateau angle (TPA) of 5° (baseline value) in a CrCL-deficient stifle joint. Sensitivity analysis was conducted for tibial fragment rotation of 13° to −3°. Ligament loads, relative tibial translation, and relative tibial rotation were determined and compared with values for CrCL-intact and CrCL-deficient stifle joints. Results—TPLO with a 5° TPA converted cranial tibial translation to caudal tibial translation and increased loads placed on the remaining stifle joint ligaments, com...
SU-FF-T-292: Monte Carlo Evaluation of Cerrobend Eye Shield in Electron Beam Treatment

Purpose: The purpose of this study was to evaluate and validate the shielding effect of a cerrobend eye shield using Monte Carlo simulation. Method and Materials: A customized cerrobend cylindrical eye shield was made and attached to a hemisphere plastic sheath to protect the lens during orbital lymphoma treatment with a 12 MeV electron beam from a Varian 2100C Linac. Film dosimetry was accomplished for open and shielded beams at 10×10 cm2 field size using a 30×30×30 cm3 solid water phantom. Monte Carlo simulation based on EGSnrc/DOSRZnrc code was performed to obtain the open and the shielded dose distributions. Comparisons between the film measurements and the simulations are presented. The dose distribution of a shielded eye with 1 cm bolus is calculated by both Philips Pinnacle treatment planning system and Monte Carlo simulation with the same geometric considerations. The two results were compared. Results: For the open field, the agreement between Monte Carlo simulation and film measurement was within 1%/1 mm for both percentage depth dose curves and cross beam profiles. For the shielded field, the agreement between simulation and film measurement was within 3%/2 mm for percentage depth dose curves and 2%/1mm for cross beam profiles. The treatment planning system could not provide reasonable results because of the high density of cerrobend. The simulation assured us that the dose to the lens is less than 10% of the tumor dose. Conclusion: For the dose distribution evaluation of orbital lymphoma treatments with shielding, film measurements and treatment planning system have limitations due to non-regular geometry and inadequate inhomogeneity correction for high Z materials. Monte Carlo simulations provide assurance of dose distribution to physicians with acceptable accuracy.
Planning for hand shape and arm transport when reaching for objects

Two early components of object manipulation are shaping the hand appropriately for functional interaction and transporting the arm with appropriate force and spatial precision to the target object. Three experiments addressed whether people plan these two components before the onset of reaching and if so, how the plans are coordinated. Subjects reached for and contacted a series of objects with one of four hand configurations: pinch, poke, palm, and clench. The required configuration was signaled by the object's color; in some conditions its structure provided a redundant cue. The time from object exposure to arm liftoff (reaction time: RT) and the time from liftoff to contact (movement time: MT) were recorded. In Experiment 1, a compatible stimulus-to-hand-shape mapping substantially facilitated RT but not MT, suggesting that the appropriate hand shape was planned prior to reaching. Experiment 2 showed that contact precision, as defined by the stability of the object's support plane, affected MT; a smaller RT effect also suggested some pre-movement planning of arm transport to accommodate precision demands. Experiment 3 combined compatibility and precision manipulations in a single task to test a model which proposes that planning for hand-shape and arm transport occur in parallel, with the onset of reaching deferred until the slower planning process is completed.
Differential antigen presentation of hepatitis B surface antigen on cell membranes of responder and nonresponder mice.

: In several systems it has been shown, that non-responsiveness to an antigen in mice of a particular haplotype is due to the lack of binding of an immunogenic peptide to class II molecules. Such studies have been done using detergent solubilized, affinity purified class II molecules. It has been reported, that the presence of certain phospholipids around class II molecules dramatically alters the extent of peptide binding to these molecules. It thus appears that the milieu in which the class II molecules are inserted influences to a considerable extent the level of peptide binding. Hence it is likely that the kinetics of binding of immunogenic peptides to class II on the cell surface, may be different from that of molecules inserted in detergent micelles. We therefore decided to test this by studying the binding of radiolabeled peptides to class II molecules on cell membranes. We report here a rapid and sensitive assay for peptide binding to murine class II molecules on cell membranes. Further, we have used this assay to study the nature of the interaction of immunogenic peptides and class II molecules on cell membranes of mice who are responders and non-responders to Hepatitis B surface Antigen (HBsAg). Interestingly, we find that immunogenic peptides bind in good correlation with their MHC restriction. We also observe that the HBsAg derived peptide which is unable to elicit a T cell response in the non-responder B10.M strain actually binds to the class II of the non-responder but fails to make a stable class II-peptide complex. We thus conclude that defective antigen presentation may be one of the possible explanations, underlying the mechanism of non-responsiveness.
A group counseling model for developing manhood among black male adolescents.

The session began with the showing of a videotape on successful African-American men in America. The audience was a combination of young black men and adult observers. After the audience watched the videotape, Dr. Lee demonstrated his model in a brief discussion with the young men. Later he explained the model to the adults.
The state of stress in the limb of the Split Mountain anticline, Utah: constraints placed by transected joints

Abstract Transected joints (i.e. systematic joints that strike at an angle to the present fold axis trend) occur on the flanks of Split Mountain, a Laramide anticline near the eastern end of the Uinta Mountains, Utah. The common orientation on both flanks for these WNW-striking joints is inconsistent with joints driven by a syn-folding stretch normal to the direction of highest curvature. A smaller dispersion of the poles to these transected joints occurs when they are rotated with bedding to their ‘pre-fold’ orientation. This dispersion of poles is inconsistent with a post-fold genesis in a regional stress field but permits the possibility that these WNW joints propagated as a systematic set prior to Laramide folding. A pre-fold interpretation is substantiated by a regional WNW-striking joint set within Cretaceous and older rocks in the surrounding Piceance, Uinta, and southeastern Sand Wash basins. During tilting accompanying the upfolding of Split Mountain, most joints of this WNW-striking regional set remain locked without slipping under a shear stress. Fracture toughness and frictional strength are two rock properties that serve to lock a joint until a critical resolved shear stress is achieved. A gravity load caused down-dip slip on some joints that were tilted to a dip of about 62°. This suggests that a local principal stress remained roughly vertical during bedding rotation. Assuming fracture strength and friction prevented slip on most joints during tilting, the ratio of least horizontal, S h , to vertical stress, S v , at the critical tilt angle was approximately 0.55.
The 26S Proteasome Is Required for Estrogen Receptor-α and Coactivator Turnover and for Efficient Estrogen Receptor-α Transactivation

Estrogen receptor-alpha (ER alpha) is downregulated in the presence of its cognate ligand, estradiol (E2), through the ubiquitin proteasome pathway. Here, we show that ubiquitin proteasome function is required for ER alpha to serve as a transcriptional activator. Deletion of the last 61 amino acids of ER alpha, including residues that form helix 12, abolishes ligand-mediated downregulation of the receptor as do point mutations in the ligand binding domain that impair coactivator binding. In addition, coactivators also are subject to degradation by the 26S proteasome, but their intrinsic transcriptional activity is not affected. These data provide evidence that protein interactions with ER alpha coactivator binding surfaces are important for ligand-mediated receptor down-regulation and suggest that receptor and coactivator turnover contributes to ER alpha transcriptional activity.
The parallel lives of angiogenesis and immunosuppression: cancer and other tales

Emerging evidence indicates that angiogenesis and immunosuppression frequently occur simultaneously in response to diverse stimuli. Here, we describe a fundamental biological programme that involves the activation of both angiogenesis and immunosuppressive responses, often through the same cell types or soluble factors. We suggest that the initiation of these responses is part of a physiological and homeostatic tissue repair programme, which can be co-opted in pathological states, notably by tumours. This view can help to devise new cancer therapies and may have implications for aseptic tissue injury, pathogen-mediated tissue destruction, chronic inflammation and even reproduction.
Performance of a kinetic energy density-dependent functional (VSXC) for predicting vibrational frequencies

Abstract We present a study of the performance of the VSXC functional for predicting vibrational frequencies and equilibrium geometries and compare the results with experiment and the B3LYP functional. The standard 6-31G ∗ and 6-311++G(3df,3pd) basis sets were used for both functionals. Scaling factors for obtaining fundamental vibrational frequencies have been derived using a least-squares approach. VSXC results compare favorably with experiment and those of B3LYP for both basis sets.
The role of familiarity in recognition

The role of familiarity in recognition was investigated by having subjects study a list of stimuli, some of which had been presented earlier in the experiment. The number of positive responses, both to targets and distractors, increased as a result of this familiarization process. This familiarization process had a greater effect on false alarms than on hits, so that recognition accuracy was lower for familiar stimuli than for relatively novel stimuli. This pattern of results differs from that found in most experiments studying the effects of linguistic word frequency on recognition.
Dissociation of cortical areas responsible for evoking excitatory and inhibitory responses in the small hand muscles

Noninvasive transcranial magnetic stimulation (TMS) of the brain using a focal eight-shaped coil with 100% stimulation output was performed in eleven healthy subjects to find out if excitatory and inhibitory responses in the small hand muscles could be dissociated. Motor evoked potentials (MEP) as well as silent periods (SP) were recorded from the right abductor pollicis brevis (APB), and first dorsal interosseus (FDI) muscles at rest and during weak voluntary contraction. Mapping of the cortical representation area was performed over different scalp locations on the left hemisphere. The cortical representation maps for ABP and FDI recorded during contraction covered much larger area and were more elongated in the anterior-posterior than in the medial-lateral direction compared to maps obtained during relaxation. The distribution maps for SPs covered larger scalp areas compared to the maps of MEPs obtained during voluntary contraction. Also during voluntary contraction the locations for evoking the longest SPs were not identical to locations for evoking the peak MEP amplitudes; the longest SPs were observed during stimulation of more medial and frontal locations compared to peak MEPs. Interestingly, stimulation of some locations resulted in the appearance of an isolated MEP without the following SP and in other locations an isolated SP was recorded. The areas for evoking isolated MEPs were in the center, whereas the areas for isolated SPs were located in the periphery of the map. Features such as exclusive locations for MEPs and SPs, and different locations for peak MEP amplitudes and longest SPs, suggest dissociation of the excitatory and inhibitory cortical processes evoked by transcranial magnetic stimulation during voluntary contraction.
Substitution of polybuffer for ampholytes in isoelectric focusing.

Abstract Polybuffer (Pharmacia) can be used in isoelectric focusing and two-dimensional gel electrophoresis of proteins. It is 1 16 th as expensive as ampholine-type synthetic carrier ampholytes.
Simple models for dynamic melting in an upwelling heterogeneous mantle column: Analytical solutions

Abstract Several lines of evidence suggest that the melt generation and segregation regions of the mantle are heterogeneous, consisting of chemically and lithologically distinct domains of variable size and dimension. Partial melting of such heterogeneous mantle source regions gives rise to a diverse range of basaltic magmas. In order to better assess the role of source heterogeneity during mantle melting, we have undertaken a theoretical study of trace element distribution and fractionation during concurrent melting and melt migration in an upwelling, chemically heterogeneous, two-porosity double lithology melting column. Analytical solutions for the abundance of a trace element in the matrix and channel were obtained under the assumptions that the porosity, melt and solid velocities, and solid–melt partition coefficients are constant and uniform. For simplicity, we neglected diffusion and dispersion in the melt. Chemical source heterogeneities of arbitrary size and shape were integrated into the simple melting models by allowing trace element abundance in the source region to vary as a function of time and space. Concurrent melting and melt migration in an upwelling heterogeneous mantle may be approximated as a quasi-steady state problem in which time-dependent concentration patterns produced by melting of heterogeneous source regions are superimposed on a reference steady-state concentration distribution established by melting of the ambient or background mantle. Chromatographic fractionation is especially important for the matrix melt and solid when chemical heterogeneities are involved during melting and melt migration in the mantle, giving rise to significant phase-shift between two incompatible trace elements in the matrix melt and scattered correlations among incompatible trace elements in residual peridotites. Mixing is the chief mass transfer process in the dunite channel where the chromatographic effect is negligible for most of the incompatible trace elements. The lack of chromatographic fractionation among incompatible trace elements and isotopic ratios in MORB suggests either most MORB are channel melts or mixing in magma conduit and chamber is very efficient such that the phase-shift is averaged out during magma transport and storage processes. Advection brings melt produced by smaller-degree of melting in the deeper part of the melting column to the overlying melting region, increasing the incompatible trace element abundance in the matrix and the channel. This advection-induced self-enrichment is especially important when heterogeneous sources are involved and may account for some of the enriched incompatible trace element patterns observed in residual peridotite that were previously interpreted to be a result of mantle metasomatism. Systematic studies of high-resolution spatially correlated mantle samples may help to constrain the melting history and the size and nature of chemical heterogeneities in the mantle.
Part four: Methods for evaluation of the role of fruits and wild greens in Shambaa diet: A case study 1

Abstract While most human societies make extensive use of wild greens and fruits in the diet, there have been few systematic studies of the extent to which such plants are actually consumed, or of their nutritional significance. Data gathered in the course of anthropological fieldwork among the Shambaa people of the Usambara Mountains, Tanzania, indicate that these plants are an important element in the local diet and contribute significantly to nutrition. Previous studies employing twenty‐four‐hour recall and household food inventories had slighted the role of these foods in the local diet. The employment of such methods as participant‐observation, intensive village surveys, and child‐following has clarified the dietary and nutritional role of these foods.
Quantum control of charge carriers in quantum wells

We present theoretical studies of the quantum control of charge carriers in a direct-current-biased (DC-biased) asymmetric double quantum well (ADQW). The objective in this work is to find the laser pulse that drives an electronic wave packet to maximum overlap with a target distribution in a chosen well at a chosen time. We use a genetic algorithm to determine the optimal parameters of the excitation pulses. The robustness of the control is analyzed with respect to the magnitude of the DC field, and two types of defects in the ADQW potential profile, a point defect and a notch. In all cases studied, the genetic algorithm is able to reoptimize the laser field to achieve the desired objective. Finally, we consider the effects of coupling the ADQW to a harmonic bath. We find that a coupling large enough to distort the effective potential significantly does not eliminate the control. Our results indicate that control in the ADQW is quite robust, which should make it a favorable system for further experimental study. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 393–402, 2000
Development of controlled porosity polymer-ceramic composite scaffolds via fused deposition modeling

This research is focused on development and fabrication of controlled porosity polymer-ceramic composite scaffolds, with 3-D interconnectivity designed to promote richer supply of blood, oxygen and nutrients for healthy in-growth of bone cells. Particulate-reinforced polymer-ceramic composites were developed by high shear mixing of polypropylene (PP) polymer and tricalcium phosphate (TCP) ceramic. Processing aids were used to improve plasticity and processibility to the composites. Controlled porosity scaffolds were fabricated via the fused deposition process, one of the commercially available rapid prototyping (RP) techniques. These porous scaffolds were characterized for their use as bone grafts in terms of physical, mechanical and biological properties. Hg-porosimetry was performed to determine pore size and their distribution. Scaffolds with different complex internal architectures were also fabricated using this composite material. Tensile properties of neat PP (as received), PP with processing aids (without TCP) and PP-TCP composite (with processing aids) were evaluated and compared using standard dog bone samples. Uniaxial compression tests were performed on cylindrical porous samples with an average pore size of 160 μm and varying vol.% porosity (36%, 48% and 52%). Samples with 36 vol.% porosity showed the best compressive strength of 12.7 MPa. Cytotoxicity and cell proliferation studies were conducted with a modified human osteoblast cell-line (HOB). Results showed that these samples were non-toxic with excellent cell growth during the first two weeks of in vitro testing.
DNA base modifications and membrane damage in cultured mammalian cells treated with iron ions

We investigated DNA base damage in mammalian cells exposed to exogenous iron ions in culture. Murine hybridoma cells were treated with Fe(II) ions at concentrations of 10 microM, 100 microM, and 1 mM. Chromatin was isolated from treated and control cells and analyzed by gas chromatography/mass spectrometry for DNA base damage. Ten modified DNA bases were identified in both Fe(II)-treated and control cells. The quantification of modified bases was achieved by isotope-dilution mass spectrometry. In Fe(II)-treated cells, the amounts of modified bases were increased significantly above the background levels found in control cells. Dimethyl sulfoxide at concentrations up to 1 M in the culture medium did not significantly inhibit the formation of modified DNA bases. A mathematical simulation used to evaluate the plausibility of DNA damage upon Fe(II) treatment predicted a dose-dependent response, which agreed with the experimental results. In addition, Fe(II) treatment of cells increased the cell membrane permeability and caused production of lipid peroxides. The nature of DNA base lesions suggests the involvement of the hydroxyl radical in their formation. The failure of dimethyl sulfoxide to inhibit their formation indicates a site-specific mechanism for DNA damage with involvement of DNA-bound metal ions. Fe(II) treatment of cells may increase the intracellular iron ion concentration and/or cause oxidative stress releasing metal ions from their storage sites with subsequent binding to DNA. Identified DNA base lesions may be promutagenic and play a role in pathologic processes associated with iron ions.