cssi/SciSciGPT-SciSciNet huggingface dataset:
Microflyers: inspiration from nature

Over the past decade, there has been considerable interest in miniaturizing aircraft to create a class of extremely small, robotic vehicles with a gross mass on the order of tens of grams and a dimension on the order of tens of centimeters. These are collectively refered to as micro aerial vehicles (MAVs) or microflyers. Because the size of microflyers is on the same order as that of small birds and large insects, engineers are turning to nature for inspiration. Bioinspired concepts make use of structural or aerodynamic mechanisms that are observed in insects and birds, such as elastic energy storage and unsteady aerodynamics. Biomimetic concepts attempt to replicate the form and function of natural flyers, such as flapping-wing propulsion and external appearance. This paper reviews recent developments in the area of man-made microflyers. The design space for microflyers will be described, along with fundamental physical limits to miniaturization. Key aerodynamic phenomena at the scale of microflyers will be highlighted. Because the focus is on bioinspiration and biomimetics, scaled-down versions of conventional aircraft, such as fixed wing micro air vehicles and microhelicopters will not be addressed. A few representative bioinspired and biomimetic microflyer concepts developed by researchers will be described in detail. Finally, some of the sensing mechanisms used by natural flyers that are being implemented in man-made microflyers will be discussed.
Double Laser Crystallization (DLC) of pre-patterned amorphous silicon film and amorphous silicon film with a patterned assisting SIO2 layer

In this study, pre-patterned amorphous silicon films are crystallized by the double laser crystallization (DLC) technique. Temperature distribution upon laser irradiation is modified by patterning the a-Si film, thus controlling the crystal growth. Patterns with a flattened concave feature is found to be favorable for large crystal growth with high localization, yielding grains with the size of 1.5 μm × 4 μm. As an alternate method (to pre-patterning the amorphous silicon film) for obtaining large crystal growth, double laser crystallization of amorphous silicon film with patterned SiO2 cap layer is proposed. The SiO2 layer assists the lateral growth of the crystals by acting as a thermal reservoir and slowing down the cooling rate, and additionally helps reduce the roughness of the polycrystalline surface to about 3nm (R.M.S.). With this alternate method, the grain width is increased from 0.5 μm to 1.5μm.Copyright © 2004 by ASME
Synthesis of a tritopic, third-generation bis(1-pyrazolyl)methane ligand and its silver(I) complex: Unexpected structure with high coordination numbers

Abstract The reaction of the new tritopic ligand C6H3[CH2OCH2CH(pz)2]3 (Ltri, pz = pyrazolyl ring), prepared to determine the types of complex architectures its metal complexes will form, with Ag(O3SCF3) yields {[AgLtri](O3SCF3)}n. The solid-state structure of this complex is a two-dimensional sheet in which each of the three bis(pyrazolyl)methane units coordinate three different symmetry equivalent Ag(I) cations, with each Ag(I) bonding to three different ligands. Because of a significant disorder in one “arm” of the ligand, approximately half of the Ag(I) cations are six-coordinate and the other half are five-coordinate. In the six-coordinate case, the Ag(I) is in a trigonal prismatic geometry and in the five-coordinate case the disordered bis(pyrazolyl)methane unit is in an unusual κ1-coordination mode. These structural types are very different from those observed with analogous multitopic poly(pyrazolyl)methane ligands, where cages and mononuclear metallacycles are observed.
Differences in young people's reports of sexual behaviors according to interview methodology: a randomized trial in India.

Objectives. We compared reports of sexual behaviors given in standard face-to-face interviews with reports given in audio computer-assisted self-interviews (ACASIs) and culturally specific interactive interviews among adolescents in India. We sought to determine which of the interview methods leads to higher reporting of sexual behaviors among economically disadvantaged 15–19-year-olds in urban India.Methods. We conducted a randomized trial in which each participant (583 boys and 475 girls) was assigned to 2 interview methods: face-to-face interview and ACASI or interactive interview. We used matched case–control analyses to assess differences in the individual’s reporting on the 2 methods.Results. Female participants consistently reported fewer sexual behaviors in ACASIs than in face-to-face interviews, whereas male participants’ reports differed according to type of sexual behavior and interview mode. Both male and female participants reported more sexual behaviors during interactive interviews than dur...
Isotope effects and the nature of selectivity in rhodium-catalyzed cyclopropanations.

The mechanism of the dirhodium tetracarboxylate catalyzed cyclopropanation of alkenes with both unsubstituted diazoacetates and vinyl- and phenyldiazoacetates was studied by a combination of 13C kinetic isotope effects and density functional theory calculations. The cyclopropanation of styrene with methyl phenyldiazoacetate catalyzed by Rh2(octanoate)4 exhibits a substantial 13C isotope effect (1.024) at the terminal olefinic carbon and a smaller isotope effect (1.003−1.004) at the internal olefinic carbon. This is consistent with a highly asynchronous cyclopropanation process. Very similar isotope effects were observed in a bisrhodium tetrakis[(S)-N-(dodecylbenzenesulfonyl)prolinate] (Rh2(S-DOSP)4 catalyzed reaction, suggesting that the chiral catalyst engages in a very similar cyclopropanation transition-state geometry. Cyclopropanation with ethyl diazoacetate was concluded to involve an earlier transition state, based on a smaller terminal olefinic isotope effect (1.012−1.015). Density functional theor...
Changes in the condyle and disc in response to distraction osteogenesis of the minipig mandible.

Abstract Purpose: Distraction osteogenesis (DO) is a commonly used technique for mandibular lengthening, but changes in the temporomandibular joint have not been well documented. The purpose of this study was to evaluate the effect of DO, at varying rates, on the mandibular condyle and articular disc. Materials and Methods: Semiburied distractors were placed via submandibular incisions in 15 minipigs. Two unoperated animals served as controls. The protocol consisted of 0 day latency and rates of 1, 2, or 4 mm/d for a 12-mm gap. After the animals were killed (0, 24, or 90 days), ipsilateral and contralateral condyles and discs were harvested and evaluated to determine changes in 1) condylar form and size, 2) condylar surface, and 3) the articular disc. Results: Articular surfaces of the condyles in control animals were smooth, with no irregularities or erosions. In animals undergoing distraction, ipsilateral condyles showed increasing changes in morphology and AP dimension, and surface contour irregularities as the DO rate increased. These changes were present, but to a lesser degree, in the contralateral condyles. Articular discs of both ipsilateral and contralateral sides showed variable thinning at the medial aspect at end DO. After 90 days, changes in the condyles and discs were reduced by remodeling except in the 4 mm/d DO groups. Conclusions: Results of this preliminary study indicate that gross changes occur in condyles and discs after unilateral mandibular DO. These changes are more severe at faster distraction rates (4 mm/d) and tend to resolve during neutral fixation when a rate of 1 mm/d is used. © 2002 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 60:1327-1333, 2002
Invited paper On multivalued logic design using exact integral calculus

The concept of integration for a multivalued logic (MVL) algebra was reported recently, and is extended to exact integration here. The necessary and sufficient conditions for the existence of an MVL function whose differential is exactly equal to the given differential expression, i.e., exact integral, and ways of obtaining such a function, if it exists, are presented. Exact integral calculus finds its application in the design of an MVL digital system.
A model of the surface binding energy for fcc copper-nickel alloy

Abstract An empirical model partitioning the surface binding energy among the three sets of nearest neighbors is presented for the face centered cubic lattice. The surface binding energy is then determined for each atom in the surface for the 100, 110 and 111 surface planes of a small uniform alloy crystal with surface atomic fractions attainable by ion implantation of the minor component into a pure elemental target. These surface binding energies per atom are then summed over the crystal surface and an average surface binding energy per atom is determined to ascertain the effect on the partial sputtering yields of each component in the alloy layer produced by ion implantation. The partial sputtering yield so calculated is compared with experimental data. This model has neglected the effect of the modified nuclear stopping power due to the ion implantation. The modified average surface binding energy as determined by these calculations does predict a shift in the partial sputtering yields toward the reported experimental values. A visual model of the modified energy surface suggests a higher probability for particular atoms to be sputtered from the surface leading to more pronounced modification of the average surface binding energy.
A linear-time algorithm for drawing a planar graph on a grid

Abstract We present a linear-time algorithm that, given an n -vertex planar graph G , finds an embedding of G into a (2 n − 4) × ( n − 2) grid such that the edges of G are straight-line segments.
Natural anchoring at the neutral point of category rating scales

Contextual theories of judgment assume that the rating of any stimulus depends on its relationship to a context of similar stimuli. For example, any specific act of behavior would be rated less favorably when considered in the context of good behaviors then when considered in the context of bad ones. However, two experiments suggest an absolute anchoring of the natural neutral point, an exception to this generalization. In Experiment 1, morally indifferent acts remained “neutral,” regardless of context; and in Experiment 2 the break-even or zero-point in a simulated game of chance was always rated “neutral.” In both experiments, contextual manipulations had powerful effects upon ratings of other stimuli, though never shifting them across the neutral point. Furthermore, both experiments suggest that neutral-point anchoring also affects the use of the most extreme categories in a manner that is unique to this phenomena. In Experiment 2 for example, the introduction of extremely positive “wins” not only made other wins seem less favorable while leaving ratings of the zero-point unchanged, but also made the most negative losses seem more favorable. It is as if the introduction of an extremely positive “win” also introduces the possibility of an extremely negative “loss.” Taken together these findings contradict the basic adaptation-level premise that the entire scale is determined by the neutral point; they are also inconsistent with the assumption of range theories that the scale is anchored by the endpoints of the range of stimuli actually experienced.
Modification of Voltage-Dependent Gating of Potassium Channels by Free Form of Tryptophan Side Chain

Indole constitutes a major component of the side chain of the amino acid tryptophan. Application of indole slows activation of voltage-dependent potassium channels and reduces steady-state conductance in a voltage- and concentration-dependent manner. The steep concentration dependence indicates that multiple indole molecules may interact with the channel. Indole does not noticeably change the unitary conductance or the mean open duration, however, it accelerates off-gating currents without altering on-gating currents. These properties of the modification of channel gating induced by indole are consistent with a model in which indole binds independently to every subunit of the channel complex to prevent the final concerted transition to the open state. We suggest that exogenously applied indole and side-chains of the tryptophan residues of the channel protein involved in activation may compete for the same effector position and that indole might be useful as a probe to study functional roles of tryptophan residues.
The refinement of probabilistic rule sets: sociopathic interactions

Abstract Probabilistic rules in a classification expert system can result in a sociopathic knowledge base , as a consequence of the assumption of conditional independence between observations and rule modularity. A sociopathic knowledge base has the property that all the rules are individually judged to be correct rules, yet a subset of the knowledge base gives better classification accuracy than the original knowledge base, independent of the amount of computational resources that are available. This paper describes how sociopathic interactions cause rule induction and refinement methods to converge to local optima with respect to maximizing classification accuracy. The problem of optimally refining sociopathic knowledge bases is modeled as a bipartite graph minimization problem and shown to be NP-hard. A heuristic rule refinement algorithm for sociopathic reduction, called SOCIO-REDUCER, is presented. Experimental results in a medical diagnosis domain show that it can reduce the diagnosis error rate by 10.5%.
High-Pressure Liquid Chromatography for Quantitation of Antimicrobial Agents

Several methods are currently available for quantitation of antimicrobial drugs in serum and body fluids, e.g., microbiological, radioenzymatic, and radioimmune assays. Recently, high-pressure liquid chromatography (HPLC) has been implemented for quantitation of a variety of drugs, including antimicrobial drugs. The general principles of chromatography, particularly in reference to HPLC, are reviewed. The methods and procedures for extraction, separation, detection, and quantitation of antimicrobial drugs by HPLC are discussed. Current HPLC techniques for measuring antimicrobial drugs in biological fluids are also summarized.
When Smoke Gets in Your Lungs

A major source of air pollution exposure in the developing world is smoke due to inefficient cooking with biomass fuels in poorly ventilated homes. Biomass fuel refers to any recently living plant- and/or animal-based material that is deliberately burned by humans as fuel, including wood, crop residues, and animal dung. The levels of exposure to particulate matter in such homes are often at least an order of magnitude higher than the highest concentrations that occur in the ambient air of the developed world. Because roughly half the world's population cooks daily with unprocessed biomass fuel, the potential public health impact is huge. The World Health Organization has estimated that indoor air pollution from solid fuel use is responsible for 2.6% of the total global burden of disease and between 1.5 and 2 million deaths each year, primarily due to acute lower respiratory infection in young children and chronic obstructive pulmonary disease in adult women. Major limitations of the existing epidemiologic literature include lack of actual exposure measurements, lack of longitudinal studies, inadequate exposure-response information, and few intervention studies. Ongoing research in Guatemala is attempting to address these data gaps.
Modification of smoking topography: A preliminary analysis+

Instructions were used to modify topographical characteristics of smoking behavior in a single-case multiple-baseline design experiment. Topographical components of puff frequency and puff duration were modified. Generalization to natural environment situations was unobtrusively assessed. Carbon monoxide levels, subjective enjoyment, and daily smoking rate also were observed. Results showed that instructions modified topographical components of smoking behavior in clinically significant directions and that these changes generalized.
Epidemiologic studies of microwave effects

This is a selective review of human epidemiologic studies and related information concerning biologic and health effects of microwave radiation. Following a description of the objectives and methods of epidemiology, the approach to microwave effects is considered and two recent but not yet published studies are described, namely, a study of U.S. naval personnel occupationally exposed to radar, and a study of American Embassy personnel in Moscow. Investigations of several reported or suspected adverse effects are assessed: ocular effects, nervous and behavioral effects, congenital anomalies, and cancer. Suggestions are offered for further epidemiologic research.
High resolution patterning in chemically amplified resists: the effect of film thickness

As thin film imaging becomes an accepted means of producing high-resolution microelectronics features, a host of new challenges has emerged. A dose dependence on resist thickness has been observed and systematically measured for chemically amplified resists exposed with 75 keV electron beam radiation. The required dose to print 100nm images increased as the thickness of the film decreased. A physiochemical explanation for this dependence was sought which included exploring thickness-induced variations in thermal characteristics of the resist film. Over the range of film thickness examined, 80-360nm, these parameters were deemed unlikely contributors to this phenomenon. Ultimately the data suggests that the dose variation with thickness may correlate to differences in the population of chemically effective electron with energies in the range of 10 to 100 eV that are responsible for the sensitization of electron beam resists.
Breeding systems of Ardisia Sw. (Myrsinaceae).

Five species (A. escallonioides Schltdl. & Cham., A. hirtella Lundell, A. elliptica Thunb., A. sieboldii Miq., and A. wallichii A.DC.) from three subgenera in the genus Ardisia (Myrsinaceae) were examined for self-compatibility, agamospermy, and autogamy using hand-pollination and pollinator-exclusion experiments on both garden plants and wild populations. All five species are self-compatible but not agamospermous. Four of the five species exhibited autogramy. Autogamy was strongly associated with stamen position, anther dehiscence type, protogyny, and inflorescence type. Because self-compatibility is widespread across different subgenera, it may be a general characteristic of the genus Ardisia. The potential impact of self-compatibility on the mating system and population genetic structure is discussed.
Gender differences in adolescents' reports of self-control problems

Gender differences among adolescents in patterns of endorsement of self-control problems were examined. Eleven potential problem areas were assessed. In six areas, significant departures from expected frequencies were observed. Proportionally more females than males reported difficulty in controlling their behavior in five out of six of the endorsed problem areas.
A Photoionization Detector for the Detection of Xenon Light

A photoionization detector is described with a high quantum efficiency at wavelengths shorter than about 2000 A. This instrument, coupled to a xenon gas scintillation proportional counter has an energy resolution of 9.5% FWHM at 6 keV. The vapor pressure and absorption coefficient of TMAE are measured and the prospects of an imaging gas scintillation proportional counter are discussed.
Rabbits in the fields: Temporal, spatial, and behavioral explanations of dryland crop failure in the Great Basin, 1912–1920

Abstract Records of dryland homesteaders in three parts of the Great Basin between 1912 and 1920 show that crop failures were common occurrences, and that failure was more often attributed to jackrabbits than to drought. These records demonstrate that most failures caused by rabbits conformed to well-defined temporal and spatial patterns, but they also make it clear that some losses can be explained only by specific actions taken by the farmers, their families, and neighbors.
A model for charged second class currents

A recent experiment [1 ] has reported a non-zero signal for second class currents [2] in the/3-decyas of several nuclear species. Second class currents have not yet, however, been observed in any particle physics experiment. In this paper we investigate some phenomenological consequences for ?article physics of a particular model for the second class current. Remarkably, withir the framework of the model, we are led to a second class current which couples to, the weak interactions with the same strength as the ordinary current, when the normalization is chosen in a particularly simple way. Second class currents do not naturally appear in the quark model. If they are large it could considerably complicate weak interaction theory; in particular, the weak and electromagnetic interactions could no longer generate only an SU(2) X U(1) as they do in the conventional theory. The second class current [3-5] *** by definition has the value -1 for the quant~lm number ((-1)IGp)((-1)J+ I), while the first class current has the value +I for this quantum number. The odd value for this combination is usually described as having the opposite G to the usual current. An ffpair, where fis a spin-½ fermion, has an
Patterns of the use of information for decision making by administrative staff of a university in Nigeria

Reports a study of the use of information for decision making by administrative staff at the Delta State University, Abraka, Nigeria. It explores the working experience of the respondents, sources of information for official decision making, areas of decisional information use, frequency of utilisation of adequate and relevant information for decision making, and problems encountered by the administrators while seeking information for making decisions. Concludes with recommendations which could help administrative staff improve their use of information for decision making.
Corrosion Effect on Structural Health Monitoring

A study has been carried out on the effect of a corrosion environment considering sea water as one is attempting to detect the location of an internal damage (notch) within an aluminum beam. The frequency variation is recorded experimentally and the eigenvectors are compared with those of unnotched specimens. A variety of corrosion times are evaluated. The scanning laser vibrometer is the primary tool used in this study to characterize the overall effects. It is possible to determine the extent of the internal notch, and to characterize the corrosion effect on the notch location by examining the change in curvature within the eigenvector. The overall effect on detection of internal damage due to corrosion becomes maximized at a time interval of two weeks. A simple finite element solution helped in initiating the experimental frequency determination.
Depression, service utilization, and treatment costs among Medicare elderly: gender differences.

ABSTRACT Objective: To compare gender differences in mood disorders, service utilization, and health care costs among a random sample of Medicare elderly beneficiaries of Tennessee. Data Sources: Medicare expenditure data from a 5% random sample of Tennessee Medicare beneficiaries (n = 35,673) were examined for 1991–1993. The physician reimbursement files provided data relative to ICD-9 diagnostic codes, physician visits, and the cost of physician services provided. Other service utilization and cost data were obtained for the sample from the outpatient, home health, skilled nursing, hospice and inpatient files. Study Design: The dependent variables were: (i) patients with ICD-9 diagnosis for a mood disorder (major depression and other depression), (ii) service utilization (number of outpatient visits, skilled nursing visits, home health visits, physician visits, emergency visits, and inpatient days), and (iii) health care costs (dollar amount of physician cost, outpatient cost, inpatient cost, total ment...
A unique photosynthetic reaction center from Heliobacterium chlorum

Abstract A previously unknown type of photosynthetic reaction center in the brownish-green bacterium Heliobacterium chlorum is described. The reaction center is tightly bound in a highly proteinaceous undifferentiated plasma membrane and contains bacteriochlorophyll g , which has major in vivo absorbancies at 788, 576 and 370 nm. The purified membrane shows a reversible photobleaching at 798 nm; the reaction center bacteriochlorophyll g is designated P798. A reversible photobleaching at 553 nm is assigned to photooxidation of a membrane-bound c -type cytochrome. The membrane structure, pigment composition and photochemical properties suggest that H. chlorum may represent a fifth family of anoxygenic photosynthetic procaryotes.
Coronary disease in mining communities in Marion County, West Virginia☆

Abstract Coronary disease has been studied in men aged 20–69 living in three mining towns in Marion County, West Virginia. The population was defined by a private census; 83 per cent of the men available in the age group were examined at a center. The examination included a standardized questionnaire on chest pain, heart and other illnesses, smoking habits and occupational details, a clinical examination of the cardiovascular system including blood pressure, a 12 lead resting electrocardiogram and a postero-anterior 14 in. × 17 in. chest X-ray. A blood sample one hour after a loading dose of glucose was also taken for a number of estimations including serum cholesterol, blood glucose and uric acid. An index of coronary disease based on certain pain characteristics and certain E.C.G. abnormalities was derived and the attributes of those so diagnosed as having coronary disease were compared with the rest of the population. There was no striking difference between the miners and ex-miners and the non-miners in the prevalence of cardiac pain or of E.C.G. abnormalities. The prevalence of cardiac pain and the frequency of E.C.G. changes were broadly similar to that found by others who have used similar standardized methods. Coronary disease which we have diagnosed by combining two sets of criteria (chest pain and E.C.G. abnormalities) is, however, appreciably more prevalent than that found by most investigators. This is more likely to be due to our combined diagnostic criteria than to any real difference in prevalence of disease in these towns; we do not think the population studied has an unusual experience of coronary disease. Of the characteristics of the coronary cases investigated, systolic blood pressure was consistently higher and ventilatory function consistently lower in the coronaries than in the others. Inconsistently higher skin fat measurements, serum cholesterol and blood sugar in the coronary group were also noted. A slightly higher proportion of ex-cigarette smokers and a lower proportion of non-smokers was found among the coronary group than among the others.
Characterizing system level energy consumption in mobile computing platforms

This paper approaches energy consumption characterization in mobile computing platforms by assessing energy consumption of "basic" application-level tasks, such as processing, input/output (disk, display, etc.), communication (transmission and reception over the network), and combinations thereof. Besides providing information on the energy consumption behavior of typical tasks performed by mobile computers, task-level energy characterization enables power management decisions, such as whether, in a distributed computation, the task at hand can be executed locally or should be assigned to a different machine (given the machine's current energy budget, the energy cost of executing the task locally, and the cost of sending the required information over the network to a peer). We employ a task-level energy consumption characterization benchmark that accounts for basic tasks such as processing, disk access (including reads and writes), terminal usage, and communication (transmission and reception). Using the benchmark, we perform an energy characterization case study using the Dell Latitude C600 running two versions of the Linux operating system.
Estimation of Fuel Use by Idling Commercial Trucks

This paper uses the recently published 2002 Vehicle Inventory and Use survey to determine the number of commercial trucks in the categories that are most likely to idle for periods of more than 0.5 h at a time. On the basis of estimated numbers of hours for both overnight idling by sleepers and long-duration idling by all size classes during their workdays, the total fuel use by idling trucks is estimated to be more than 2 billion gallons per year. Workday idling is determined to be a potentially much larger energy user than overnight idling, but data are required before any definitive conclusions can be reached. Existing technologies can reduce overnight idling, but development may be needed to reduce workday idling.
The central nervous organization underlying control of antagonistic muscles in the crayfish. I. types of command fibers

1. A limited number of “command” interneurons mediate the release of coordinated ganglionic output to antagonistic postural muscles in the crayfish abdomen. Graded contractions of these muscles are regulated by the frequency of discharge in several motoneurons, whose own discharge is in turn controlled by the level of activity in command fibers. 2. Different command fibers having a similar effect (i.e., flexion or extension) vary in the relative effectiveness with which they excite specific motoneurons. This selectivity is responsible for different rates of tension development. 3. Command fibers connect with the postural motor system in each segment in a bilaterally symmetrical fashion. Many of the same command elements also have unilateral or reciprocal effects on other motor systems, especially on those which control the swimmerets and uropods. 4. The reciprocity between flexors and extensors is inherent in the ganglionic organization. Activation or modulation of this ganglionic center is accomplished by the command interneurons, which in turn are activated by appropriate combinations of sensory inputs. A wide variety of postural adjustments may thus be controlled by a limited number of central neurons that make complex but specific output connections.
Stimuli-sensitive intrinsically disordered protein brushes

Grafting polymers onto surfaces at high density to yield polymer brush coatings is a widely employed strategy to reduce biofouling and interfacial friction. These brushes almost universally feature synthetic polymers, which are often heterogeneous and do not readily allow incorporation of chemical functionalities at precise sites along the constituent chains. To complement these synthetic systems, we introduce a biomimetic, recombinant intrinsically disordered protein that can assemble into an environment-sensitive brush. This macromolecule adopts an extended conformation and can be grafted to solid supports to form oriented protein brushes that swell and collapse dramatically with changes in solution pH and ionic strength. We illustrate the value of sequence specificity by using proteases with mutually orthogonal recognition sites to modulate brush height in situ to predictable values. This study demonstrates that stimuli-responsive brushes can be fabricated from proteins and introduces them as a new class of smart biomaterial building blocks.
MAYA BLUE AND PALYGORSKITE: A second possible pre-Columbian source

Maya Blue is an unusual blue pigment used on pottery, sculpture, and murals from the Preclassic to the Colonial period. Until the late 1960s, its composition was unknown, but chemists working in Spain, Belgium, Mexico, and the United States identified Maya Blue as a combination of indigo and the unusual clay mineral palygorskite (also called attapulgite). A source of palygorskite in the Maya area was unknown for years; then ethnoarchaeological research in the mid-1960s demonstrated that the contemporary Maya recognized the unique physical properties of palygorskite and used it as an additive for pottery temper and for curing certain types of illnesses. Because of its importance in Maya Blue, pre-Hispanic sources of the mineral were then suggested based on ethnoarchaeological data. One of these sources was the cenote in the town of Sacalum, Yucatan. This paper briefly reviews the history of the Maya Blue research from an anthropological perspective and presents evidence of a second possible pre-Hispanic mining site for palygorskite at Yo' Sah Kab near Ticul, Yucatan. Archaeological and technological approaches have demonstrated the use, distribution, composition, and characteristics of Maya Blue, but ethnoarchaeology has related it to Maya language and culture and to possible pre-Hispanic sources of one of its constituents, palygorskite.
Microstructural design of silicon nitride with improved fracture toughness: II. Effects of yttria and alumina additives

Significant improvements in the fracture resistance of self-reinforced silicon nitride ceramics have been obtained by tailoring the chemistry of the intergranular amorphous phase. First, the overall microstructure of the material was controlled by incorporation of a fixed amount of elongated s-Si3N4 seeds into the starting powder to regulate the size and fraction of the large reinforcing grains. With controlled microstructures, the interfacial debond strength between the reinforcement and the intergranular glass was optimized by varying the yttria-to-alumina ratio in the sintering additives. It was found that the steady-state fracture toughness value of these silicon nitrides increased with the Y:Al ratio of the oxide additives. The increased toughness was accompanied by a steeply rising R-curve and extensive interfacial debonding between the elongated s-Si3N4 grains and the intergranular glassy phase. Microstructural analyses indicate that the different fracture behavior is related to the Al (and O) content in the s´-SiAlON growth layer formed on the elongated s-Si3N4 grains during densification. The results imply that the interfacial bond strength is a function of the extent of Al and Si bonding with N and O in the adjoining phases with an abrupt structural/chemical interface achieved by reducing the Al concentration in both the intergranular phase and the s´-SiAlON growth layer. Analytical modeling revealed that the residual thermal expansion mismatch stress is not a dominant influence on the interfacial fracture behavior when a distinct s´-SiAlON growth layer forms. It is concluded that the fracture resistance of self-reinforced silicon nitrides can be improved by optimizing the sintering additives employed.
Maize R2R3 Myb Genes: Sequence Analysis Reveals Amplification in the Higher Plants

Transcription factors containing the Myb-homologous DNA-binding domain are widely found in eukaryotes. In plants, R2R3 Myb-domain proteins are involved in the control of form and metabolism. The Arabidopsis genome harbors >100 R2R3 Myb genes, but few have been found in monocots, animals, and fungi. Using RT-PCR from different maize organs, we cloned 480 fragments corresponding to a 42-44 residue-long sequence spanning the region between the conserved DNA-recognition helices (Myb(BRH)) of R2R3 Myb domains. We determined that maize expresses >80 different R2R3 Myb genes, and evolutionary distances among maize Myb(BRH) sequences indicate that most of the amplification of the R2R3 Myb gene family occurred after the origin of land plants but prior to the separation of monocots and dicots. In addition, evidence is provided for the very recent duplication of particular classes of R2R3 Myb genes in the grasses. Together, these findings render a novel line of evidence for the amplification of the R2R3 Myb gene family in the early history of land plants and suggest that maize provides a possible model system to examine the hypothesis that the expansion of Myb genes is associated with the regulation of novel plant cellular functions.
Limiting dilution analysis of virus-specific memory B cells by an ELISPOT assay

Many acute viral infections induce long-term, sometimes even life-long humoral immunity. To characterize this immune response, accurate quantitation of memory B cells and plasma cells is essential. Plasma cells can be quantitated directly ex vivo by virtue of their ability to spontaneously secrete antibody. Memory B cells on the other hand, do not spontaneously secrete antibody but require antigenic stimulation in order to proliferate and differentiate into antibody secreting cells (ASC). In this study, an ELISPOT-based limiting dilution assay (LDA) was developed for quantitating virus-specific B cell memory following acute lymphocytic choriomeningitis virus (LCMV) infection of adult mice. Antiviral memory B cell precursor (MBCp) frequencies were calculated from in vitro stimulated cultures using either a conventional ELISA-based LDA to measure accumulated virus-specific antibody in the culture medium or a new ELISPOT-based LDA that identifies the antibody-secreting daughter cells directly. In terms of sensitivity, the ELISPOT-based LDA and the ELISA-based LDA both calculated LCMV-specific MBCp frequencies to be approximately 1/2 x 10(4) spleen cells. However, compared to the 12 days of in vitro stimulation required to estimate MBCp frequencies by the ELISA-based LDA, the ELISPOT-based LDA required only 3-6 days of stimulation to quantitate MBCp frequencies. If cell division was blocked by gamma-irradiation or treatment with mitomycin C, the MBCp frequency dropped below detection (< 1 MBCp/10(6) cells), indicating that virus-specific B cells quantitated by this assay must both proliferate and differentiate into antibody secreting cells in order to be detected. Naive, uninfected mice did not have LCMV-specific memory B cells, demonstrating that only in vivo-generated antiviral B cells from LCMV-immune mice were detected by this assay. chi 2 analysis of the ELISPOT-based LDA showed that the MBCp frequency data fit a linear regression model (p = 0.0137), indicating single-hit kinetics in which only one cell type was limiting. These results indicate that the ELISPOT-based LDA provides a rapid and statistically accurate method to quantitate virus-specific B cells.
Asymmetric Behavior in Stem Cells

Asymmetry in the stem cell niche refers to the notion that daughter cells are different from each other. There is significant evidence that many stem cell divisions result in one daughter cell that is similar to the parent cell and, hence, necessarily allows for self-renewal of the stem cell pheno- type, whereas the other daughter cell is a differentiated or committed cell type. In this chapter we will discuss the role of asymmetry in stem cell divisions and the evidence that supports different asymmetric scenarios in different model systems. We first present the early asymmetric divisions that have been described in first divisions of the zygote and in ga- metogenesis. Next, we will discuss evidence of asymmetry in postnatal stem cells. Here we will describe two systems in particular - the hematopoietic system and muscle stem cells. Lastly, we will present a theory of the immortal strand hypothesis in which the role of DNA strand segregation is discussed as it relates to asymmetry in cell divisions and the protection of the self-renewing stem cell.
Diabetic nephropathy: Emerging biomarkers for risk assessment

Progression of diabetic nephropathy (DN) is commonly defined by an increase in albuminuria from normoalbuminuria to microalbuminuria and from microalbuminuria to macroalbuminuria. Although early detection of DN can prevent or slow its progression, a major difficulty in inducing remission in patients with early DN is the identification of biomarkers that could help identify patients more likely to progress to end-stage renal disease (ESRD). Traditional risk factors such as albuminuria do not effectively predict DN progression, and other predictors of DN have yet to be characterized and validated. The need for discovering sensitive and easily detectable biomarkers to monitor the decline in renal function and to separate progressors from nonprogressors of DN is therefore of paramount importance. Recently, microRNAs (miRNAs) have emerged as one such potential class of biomarkers. Mature miRNAs are a class of evolutionarily conserved, short (20–22 nucleotides long), noncoding RNA that are potent regulators of gene expression. After several synthesis and processing steps, mature miRNAs are loaded into the RNA-induced silencing complex, which directs the miRNAs to its target messenger RNAs (mRNAs). Once bound to its target mRNA, the RNA-induced silencing complex can facilitate several forms of transcriptional repression depending on the strength of the miRNA-mRNA interaction and seed-sequence/target site complementarity, ultimately resulting in the loss of protein expression (1). Thus, the recent discovery of …
Monitoring of Cytomegalovirus Viral Loads by Two Molecular Assays in Whole-Blood and Plasma Samples from Hematopoietic Stem Cell Transplant Recipients

Cytomegalovirus (CMV) viral loads in hematopoietic stem cell transplant (HSCT) recipients are typically monitored using quantitative molecular assays. The Roche Cobas AmpliPrep/Cobas TaqMan CMV test (Cobas CMV) has recently been cleared by the FDA for the monitoring of CMV viral loads in plasma samples from transplant patients. In this study, we compare and correlate the viral loads obtained by a laboratory-developed test (LC CMV) (using Roche analyte-specific reagents [ASR] on the LightCycler 2.0) on whole-blood specimens with those obtained on corresponding plasma and whole-blood specimens by the Cobas CMV assay. Testing was performed on 773 archived patient specimens. The strength of the agreement was good for the two assays performed on whole blood (κ = 0.6; 95% confidence interval [CI], 0.51 to 0.7) and moderate when the tests were performed on different sample types (κ = 0.54; 95% CI, 0.47 to 0.62 for the LC CMV whole blood [WB] assay versus Cobas plasma [PL], and κ = 0.57; 95% CI, 0.5 to 0.65 for the Cobas WB assay versus Cobas PL), although the difference was not statistically significant. Using a combination gold standard (i.e., a true positive was a specimen that was positive by two or more methods), the sensitivity and specificity of the assays were 78.8% and 99.3% for the LC CMV assay, 85.2% and 98.1% for the Cobas CMV WB assay, and 100% and 90.5% for Cobas CMV PL assay, respectively. A comparison of the CMV viral load trends in both plasma and whole blood from a few patients with multiple positive successive samples showed similar slopes, with differences in the slope ranging from 0.01 to 0.22. However, the absolute value for individual viral load differed markedly with whole-blood viral loads, being on average 0.5- to 1.22-log higher than those in plasma. The Cobas CMV assay provides a valid option for the monitoring of viral loads in transplant patients. Due to its increased sensitivity, the detection of CMV DNA in patients with low viral loads (i.e., those below limit of quantification [LOQ]) is increased with the Cobas CMV assay in plasma specimens. Longitudinal prospective studies will be needed to examine the clinical significance of these low-level viral loads.
Twelve tips for presenting a clinical problem solving exercise

Background: Lectures are moderately effective for teaching medical knowledge but generally fail at promoting clinical reasoning. In a clinical problem solving (CPS) conference, a clinician is prese...
Design and analysis of linear actuator for active vibration cancellation

This study was conducted to develop a permanent magnet (PM) linear actuator for active vibration cancellation in automotive applications. To meet the system requirements and physical constraints, the actuator was designed using the high energy density magnets, MAGNEQUENCH-3 (MQ3). The magnetic circuit of the actuator was modeled using finite element-based magnetic field analysis. The actuator was built and tested and the results confirmed the predicted performance. Because of the presently high cost of MQ3 magnets, a parametric study was then conducted to determine possible design trade-offs and the impact of using ferrite magnet material on actuator size and performance.
A novel mitofusin 2 mutation causes canine fetal-onset neuroaxonal dystrophy

We recently reported autosomal recessive fetal-onset neuroaxonal dystrophy (FNAD) in a large family of dogs that is not caused by mutation in the PLA2G6 locus (Fyfe et al., J Comp Neurol 518:3771–3784, 2010). Here, we report a genome-wide linkage analysis using 333 microsatellite markers to map canine FNAD to the telomeric end of chromosome 2. The interval of zero recombination was refined by single-nucleotide polymorphism (SNP) haplotype analysis to ~200 kb, and the included genes were sequenced. We found a homozygous 3-nucleotide deletion in exon 14 of mitofusin 2 (MFN2), predicting loss of a glutamate residue at position 539 in the protein of affected dogs. RT-PCR demonstrated near normal expression of the mutant mRNA, but MFN2 expression was undetectable to very low on western blots of affected dog brainstem, cerebrum, kidney, and cultured fibroblasts and by immunohistochemistry on brainstem sections. MFN2 is a multifunctional, membrane-bound GTPase of mitochondria and endoplasmic reticulum most commonly associated with human Charcot–Marie–Tooth disease type 2A2. The canine disorder extends the range of MFN2-associated phenotypes and suggests MFN2 as a candidate gene for rare cases of human FNAD.
A longitudinal analysis of nanotechnology literature: 1976–2004

Nanotechnology research and applications have experienced rapid growth in recent years. We assessed the status of nanotechnology research worldwide by applying bibliographic, content map, and citation network analysis to a data set of about 200,000 nanotechnology papers published in the Thomson Science Citation Index Expanded database (SCI) from 1976 to 2004. This longitudinal study shows a quasi-exponential growth of nanotechnology articles with an average annual growth rate of 20.7% after 1991. The United States had the largest contribution of nanotechnology research and China and Korea had the fastest growth rates. The largest institutional contributions were from the Chinese Academy of Sciences and the Russian Academy of Sciences. The high-impact papers generally described tools, theories, technologies, perspectives, and overviews of nanotechnology. From the top 20 institutions, based on the average number of paper citations in 1976–2004, 17 were in the Unites States, 2 in France and 1 in Germany. Content map analysis identified the evolution of the major topics researched from 1976 to 2004, including investigative tools, physical phenomena, and experiment environments. Both the country citation network and the institution citation network had relatively high clustering, indicating the existence of citation communities in the two networks, and specific patterns in forming citation communities. The United States, Germany, Japan, and China were major citation centers in nanotechnology research with close inter-citation relationships.