cssi/SciSciGPT-SciSciNet huggingface dataset:
History dependence of primary dendrite spacing during directional solidification of binary metallic alloys and interdendritic convection

Abstract Growth speed dependence of the primary dendrite spacing distribution, the maximum, the median and the minimum, has been examined in Al–4.1 wt% Cu, Pb–2.2 wt% Sb and Pb–5.8 wt% Sb alloys. History dependence of primary spacings has been studied by examining the spacing distributions after step-increase and step-decrease in the growth speed. The “branching-instability” process that determines the upper limit of the primary spacings is found to be less sluggish as compared with the “submerging process” that determines the lower spacing limit. In the absence of convection the minimum, the median and the maximum spacings show identical growth speed dependence, A ( V ) −0.22 . Interdendritic convection causes more reduction in the upper limit as compared with the lower limit; and it also reduces the extent of experimentally observed history dependence of the primary spacing.
Some new partial orderings on Sn and Sn×Sn

Abstract A new class of partial orderings on Sn, the set of permutations of {1,…,n}, is given. Each of these partial orderings is shown to be a subordering of a recently described partial ordering on Sn (Block, Chhetry, Fang and Sampson (1990)) which is related to Schriever's (1987) more associated ordering on bivariate distributions. Also given is an extension of three known partial orders on Sn to partial orders on Sn×Sn. These extensions facilitate the study of functions from Sn×Sn into R , which preser these partial orderings, thereby, providing a methodology for extending the notion of arrangement increasing functions.
Effect of additive length and chemistry on the morphology of blends of conjugated thiophenes and fullerene derivative acceptor molecules

Small molecule additives have been shown to increase the device efficiency of conjugated polymer (donor) and fullerene derivative (acceptor) based organic solar cells by modifying the morphology of the device active layer. In this paper we conduct a systematic study of how additives affect the donor-acceptor morphology using molecular dynamics simulations of blends of thiophene-based oligomers, mimicking poly(3-dodecylthiophene) (P3DDT) or poly(2,2′:5′,2”-3,3”-didocyl-terthiophene) (PTTT), and fullerene derivatives with additives of varying length and chemical functionalization, mimicking experimentally used additives like methyl ester additives, diiodooctane, and alkanedithiols. We find that functionalization of additives with end groups that are attracted to acceptor molecules are necessary to induce increased donor-acceptor macrophase separation. In blends where acceptors intercalate between oligomer alkyl side chains, functionalized additives decrease acceptor intercalation. Functionalized additives with shorter alkyl segments increase acceptor macrophase separation more than additives with same chemical functionalization but longer alkyl segments. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1046–1057
Updating workpiece geometry using robotic sensor information gathered during contact tasks

During robotic contact tasks, geometric information of the workpiece is used to specify the position of the robot’s hand on the workpiece and the direction of force control. This geometry is idealized in a typical CAD file, but due to manufacturing precision or wear, the actual workpiece geometry is inevitably deviated from the desired geometry. Furthermore, when the workpiece is mounted, position and orientation inaccuracies emerge. In this paper, we investigate two questions: (1) Can the workpiece geometry in the CAD file be used to control a robot in contact with an inaccurately placed workpiece?; and (2) Once the task is performed, how can the robot’s sensor information be used to update the geometry of the workpiece? A methodology is developed to solve robotic control problems with workpiece position and geometry inaccuracies. Once performed, the CAD file image is displaced to fit the sensed trajectory of the robot’s hand. Finally, the workpiece image geometry is modified using a least squares approximation to fit the sensed data more accurately. In the end, the robot performs the contact task while gathering information that is used to update the original CAD file geometry. The methodologies are demonstrated through a simulation experiment that requires a robot to shave a geometrically altered face that is inaccurately positioned.
Epigenetic toxicity of a mixture of polycyclic aromatic hydrocarbons on gap junctional intercellular communication before and after biodegradation

Polycyclic aromatic hydrocarbons (PAHs) are known carcinogens, but most research on their toxicity in the development of human-risk assessment models has focused on genotoxicity. Many nongenotoxic PAHs, however, have been shown to be epigenetically toxic by disrupting gap junctional intercellular communication (GJIC), an effect which has been affiliated with tumor promotion. We therefore used GJIC as an epigenetic biomarker to assess the toxic effect of a nonaqueous phase liquid (NAPL) mixture of PAHs commonly found in coal tar and creosote products. The NAPL mixture consisted of toluene, naphthalene, 1-methylnaphthalene, 2-ethylnaphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene, and pyrene. This mixture reversibly inhibited GJIC at a maximal and noncytotoxic dose of 60 μM. Inhibition occurred within 5 min, indicating a post-translational modification of gap junction proteins. Biodegradation of globules of this mixture suspended in mineral media by a microorganism isolated from creosote-conta...
Transient emission of screw dislocations from a dynamically-loaded interface crack

Abstract Exact transient solutions for the motion and arrest of a screw dislocation at an interface crack subjected to the diffraction of incident plane SH-waves are obtained, and then examined in light of a dislocation force-based emission criterion. It is found that, unless deceleration is allowed, dislocation arrest may be temporary. Expressions for the time of emission and the arrest distance are derived in terms of material properties such as the interface lattice friction, and a dimensionless variable related to the size of a zone of attraction at the crack edge. For both step-stress and sinusoidal incident SH-waves, the expressions show that emission will initiate in a minimum time at zero speed, and that emission at a critical speed can occur only after an infinite time. The magnitudes of the expressions indicate that the emission process is micromechanical in scale, and that incident wave frequencies may have to be in the MHz range in order to trigger emission. Study of the dynamic stress intensity factor shows that emission-generated crack edge shielding may not necessarily occur, and that emission will generally preclude purely brittle debonding.
Dynamic Optimization of Drivetrain Gear Ratio to Maximize Wind Turbine Power Generation—Part 1: System Model and Control Framework

Wind is considered to be one of the most promising resources in the renewable energy portfolio. Still, to make wind energy conversion more economically viable, it is necessary to extract greater power from the wind while minimizing the cost associated with the technology. This is particularly important for small wind turbines, which have the highest cost per kilowatt of energy produced. One solution would be a variable ratio gearbox (VRG) that can be integrated into the simple and low-cost fixed-speed induction generator. Through discrete variable rotor speed operation, the VRG-enabled system affects the wind speed ratio, the power coefficient, and ultimately the power produced. To maximize electrical production, mechanical braking is applied during the normal operation of the wind turbine. A strategy is used to select gear ratios (GRs) that produce torque slightly above the maximum amount the generator can accept while simultaneously applying the mechanical brake, so that full load production may be realized over greater ranges of the wind speed. To characterize the performance of the system, a 100 kW, fixed speed, stall-regulated wind turbine, has been developed for this study. The VRG-enabled wind turbine control system is presented in two papers. Part 1 focuses on the turbine simulation model, which includes the rotor, VRG-enabled drivetrain, disk brake, and electric generator. A technique for estimating the performance of a disk brake, in the wind turbine context, is also presented. Part 2 of the research will present a dynamic optimization algorithm that is used to establish the control protocol for competing performance objectives.
The vibrational spectrum of H2O3: An ab initio investigation

Theoretically determined frequencies and absorption intensities are reported for the vibrational spectra of the covalent HOOOH and hydrogen bonded HO...HOO intermediates that may form in the reaction of the hydroxyl and hydroperoxyl radicals. Basis sets of double‐zeta‐polarized quality, augmented by diffuse and second sets of polarization functions have been used with complete‐active‐space, self‐consistent‐field wave functions. The calculated harmonic vibrational frequencies of HOOOH have been corrected with empirical factors and presented in the form of a ‘‘stick’’ spectrum. The oxygen backbone vibrations, predicted to occur at 519, 760, and 870 cm−1, are well separated from most interferences, and may be the most useful for the species’ identification. In the case of the hydrogen bonded isomer, emphasis has been placed upon prediction of shifts in the intramolecular vibrational frequencies that take place upon formation of the complex. In particular, the HO stretch and HOO bend of HO2 are predicted to h...
Low-cost modification to the Copacabana method for spreading transformation mixtures

We have found the Copacabana method for the spreading of Escherichia coli transformations described earlier in this journal (1) to be very useful and have developed an inexpensive, timesaving, and convenient modification that we call the BARRY modification, for Beads Autoclaved in Reusable and ReadY tubes. In the Copacabana method, sterile glass beads are used to spread and disperse E. coli on solid media, replacing glass spreaders and containers of ethanol (1). A number of companies offer presterilized glass beads for this purpose, which are sold either in a dispenser bottle or in singleuse tubes. In place of presterilized beads, we purchase solid 4-mm glass beads. Instead of autoclaving the beads in 100-mL milk dilution bottles (1), we distribute four glass beads each into 2.0 mL tubes with screw caps. We have found that if the beads are dispensed into a weigh boat, a 0.2-mL PCR tube with an attached cap can be used to scoop up exactly four beads. The beads are easily transferred into the screw cap tubes, which are held in a microcentrifuge rack. Once the beads Low-cost modification to the Copacabana method for spreading transformation mixtures
Comparative efficacy of hemodialysis and hemoperfusion in severe theophylline intoxication.

Objective: To determine the comparative efficacy of hemoperfusion and hemodialysis for severe theophylline toxicity in concurrent case series. Methods: A 10-year, prospective, observational study was performed of consecutive patients referred to a regional poison control center with severe theophylline intoxication in whom either hemodialysis or hemoperfusion was used. The primary outcomes were 1) incidence of major theophylline toxicity (convulsions or life-threatening cardiac dysrhythmias) during or after each procedure, 2) calculated theophylline clearance, and 3) procedure-related complications. Results: Over the study period, 56 patients underwent hemodialysis or hemoperfusion as treatment of severe theophylline intoxication. Overall mean age was 40. 5 ± 22. 9 years. Mean peak serum theophylline concentration was 103. 3 ± 39. 1 μ g/mL (range 36 to 245 μ g/mL). Thirty patients (54%) were victims of acute theophylline intoxication, while 18 (32%) had chronic overmedication and 8 (14%) had acute-on-therapeutic intoxication. Thirty-nine patients (70%) underwent hemodialysis, while 17 (30%) underwent hemoperfusion. There were no significant intergroup differences in age (39. 4 vs 43. 0 yr), peak serum theophylline concentration (99. 5 vs 112. 1 μ g/mL), time to procedure (8. 4 vs 6. 3 hr), or duration of procedure (4. 1 vs 3. 7 hr). Thirty-three percent of the patients undergoing hemodialysis had major toxicity during or after the procedure, compared with 18% of those who received hemoperfusion (p = NS). Post-procedure serum theophylline concentrations were 26. 9 vs 30. 4 μ g/mL, corresponding to drug clearance rates of 185. 1 and 294. 8 mL/kg/hr (p = 0. 03). Procedural complications occurred in 3 patients who received hemoperfusion and consisted of bleeding diatheses and hypocalcemia. No complications occurred in patients receiving hemodialysis (p = 0. 007). Conclusions: These data confirm that hemoperfusion provides a higher theophylline clearance rate than hemodialysis. However, hemodialysis appears to have comparable efficacy in reducing the morbidity of severe theophylline intoxication and is associated with a lower rate of procedural complications.
Do dogs (Canis familiaris) show contagious yawning

We report an experimental investigation into whether domesticated dogs display contagious yawning. Fifteen dogs were shown video clips of (1) humans and (2) dogs displaying yawns and open-mouth expressions (not yawns) to investigate whether dogs showed contagious yawning to either of these social stimuli. Only one dog performed significantly more yawns during or shortly after viewing yawning videos than to the open-mouth videos, and most of these yawns occurred to the human videos. No dogs showed significantly more yawning to the open-mouth videos (human or dog). The percentage of dogs showing contagious yawning was less than chimpanzees and humans showing this behavior, and considerably less than a recently published report investigating this behavior in dogs (Joly-Mascheroni et al. in Biol Lett 4:446-448, 2008).
Acquired dermal melanocytosis: appearance during pregnancy.

Abstract We report the first case of acquired dermal melanocytosis (ADM) appearing during pregnancy. A 23-year-old Hispanic woman presented to the Dermatology Clinic of Columbia-Presbyterian Medical Center during the second trimester of pregnancy with a nonpalpable blue-gray patch with interspersed discrete brown macules on the right lower extremity. It had appeared during the first trimester of pregnancy. Cutaneous biopsy specimens revealed dermal melanocytes. A review of all reported cases of this rare dermatosis in the international literature is presented. (J Am Acad Dermatol 2001;45:609-13.)
Computation of the pressure inside bubbles and pores in Stokes flow

Numerical methods are discussed for computing the pressure inside a two- or three-dimensional inviscid bubble with negligible density suspended in Stokes flow, subject to a specified rate of expansion. In the case of flow past a solitary two- or three-dimensional bubble, the bubble pressure is found by solving an integral equation of the first kind for the normal derivative of the pressure on the side of the liquid over the free surface, while requiring that the pressure field decays at a rate that is faster than the potential due to a point source. In another approach, an explicit expression for the bubble pressure is derived by applying the reciprocal theorem for the flow around the bubble and the flow due to a point source situated inside the bubble. In the case of flow past, or due to the expansion or shrinkage of, a periodic lattice of bubbles, the bubble pressure is found by solving an integral equation of the second kind for the density of an interfacial distribution of point-source dipoles, while ensuring existence and uniqueness of solution by spectrum deflation. The new methods considerably simplify the computation of the bubble pressure by circumventing the evaluation of the finite part of hypersingular integrals. Results of numerical simulations illustrate the pressure developing inside a solitary two- and three-dimensional incompressible bubble suspended in simple shear flow, and the pressure developing inside a doubly periodic array of gaseous inclusions representing shrinking pores trapped in a sintered medium.
A conserved sequence element in ribonuclease III processing signals is not required for accurate in vitro enzymatic cleavage

Abstract Ribonuclease III of Escherichia coli is prominently involved in the endoribonucleolytic processing of cell and viral-encoded RNAs. Towards the goal of defining the RNA sequence and structural elements that establish specific catalytic cleavage of RNase III processing signals, this report demonstrates that a 60 nucleotide RNA (R1.1 RNA) containing the bacteriophage T7 R1.1 RNase III processing signal, can be generated by in vitro enzymatic transcription of a synthetic deoxyoligonucleotide and accurately cleaved in vitro by RNase III. Several R1.1 RNA sequence variants were prepared to contain point mutations in the internal loop which, on the basis of a hypothetical 'dsRNA mimicry' structural model of RNase III processing signals, would be predicted to inhibit cleavage by disrupting essential tertiary RNA-RNA interactions. These R1.1 sequence variants are accurately and efficiently cleaved in vitro by RNase III, indicating that the dsRNA mimicry structure, if it does exist, is not important for substrate reactivity. Also, we tested the functional importance of the strongly conserved CUU/GAA base-pair sequence by constructing R1.1 sequence variants containing base-pair changes within this element. These R1.1 variants are accurately cleaved at rates comparable to wild-type R1.1 RNA, indicating the nonessentiality of this conserved sequence element in establishing in vitro processing reactivity and selectivity.
Magnetic-field-induced alignment-to-orientation conversion in sodium

We report a detailed investigation of excited-state alignment-to-orientation conversion in the presence of an external magnetic field. This counterintuitive phenomenon occurs under intermediate-coupling conditions. A weak, linearly polarized, cw laser beam was used to excite and align the Na 3${\mathit{P}}_{3/2}$ state in an atomic beam along the z direction. The degree of circular polarization of the resulting fluorescence was detected along the z direction as a function of magnetic-field strength. The spectrally integrated transitions originating from individual F levels of the 3${\mathit{S}}_{1/2}$ state yield a maximum circular-polarization fraction of \ensuremath{\sim}40%; integrating the circular polarization over all the allowed 3${\mathit{S}}_{1/2}$-3${\mathit{P}}_{3/2}$ transitions gives rise to an \ensuremath{\sim}8% effect. The results are predicted by the Breit formula, which is in excellent agreement with our observations.
Persistent Illegal Logging in Costa Rica: The Role of Corruption Among Forestry Regulators

Costa Rica is known for its environmental accomplishments. However, a high amount of illegal logging has continued to occur across the country, threatening to make wooded areas less viable for harboring biodiversity and supplying lumber. This article examines how corruption among forestry regulators is one important factor that leads them to allow people to log illicitly. Focusing on Limon Province, especially its Amistad-Caribe Conservation Area, this study examines regulators’ corrupt behaviors, how the latter contribute to specific forms of illegal logging, and why regulators act in this manner. Data was collected though in-depth and anonymous interviews with experts from a variety of stakeholder groups. This most detailed look yet at corruption in Costa Rica’s forestry sector provides new understandings. Most importantly, it indicates that a serious failure to satisfy regulators’ material needs, including salary, equipment, funds and staff, is the key issue causing them to fall into corruption. Costa ...
Synthesis of the cobalt analogues of Roussin's red salt esters

Abstract Cobalt analogs of the Roussin’s red salt esters have been prepared by the reaction of organic thiol or selenol compounds with the readily prepared [Co(NO)2Cl]2. The compounds are unstable to light and decompose in ca. 1 week even in the dark at −78 °C. The IR spectra suggest that the compounds have C2v symmetry with the possibility of a folded Co2S2 rhombus about the S–S axis.
$CPT$ and Lorentz Tests in Hydrogen and Antihydrogen

Signals for $\mathrm{CPT}$ and Lorentz violation at the Planck scale may arise in hydrogen and antihydrogen spectroscopy. We show that certain $1S\ensuremath{-}2S$ and hyperfine transitions can exhibit theoretically detectable effects unsuppressed by any power of the fine-structure constant.
Characteristics of students who bring weapons to school

Purpose. This study explores the relationships between social, demographic, and behavioral characteristics and self-reported carrying of a weapon to school among middle school students. The results provide a statistical profile of youth most likely to bring weapons to school and help to identify characteristics that are only spuriously related to this behavior. Methods. Study respondents were part of an ongoing randomized evaluation of a school-based drug use prevention program in Illinois. Self-administered questionnaires were completed by 1,503 seventh and eighth graders in the spring of 1992. Results. Fifteen percent of respondents brought some type of weapon to school in the past month. In a multivariate logistic regression model, being male, not living with both parents, not feeling close to parents, drinking heavily, participating in fights, damaging school property, and perceiving that at least a few other students brought weapons to school, were significantly associated with weapon carrying. Victimization and fear for safety in school were not significantly associated with weapon carrying in the multivariate model. Conclusions. Study results suggest that both the structure and the dynamics of the family play an important role in weapon carrying behavior. Weapon carrying also appears to cluster with other deviant behaviors. Furthermore, the findings suggest that weapons are not brought to school because of a heightened need for protection, but rather may be in response to normative influences in school.
Maine: On the Cusp of the Forest Transition

Deforestation is a serious problem in many parts of the world. Recently, deforestation is being reversed in some areas, a process called the "forest transition." This article describes the historic changes occurring in Maine's forests, and discusses the implications of those changes. Large scale deforestation occurred as land was cleared for agriculture in the southern and central parts of the state; the forests in the north were heavily harvested by industry. Recently, a turnaround of sorts has occurred in the condition of the forests, and the latest [2005] forest inventory is quite optimistic. However, it is difficult to argue that a forest transition has occurred because improvements made by some forest landowners are counterbalanced by declines in forest conditions due to the activities of other landowners. As a result, the amount of forested land is likely to fall again as the acreage of agricultural land reverting to forest is overwhelmed by a larger amount of land being converted to housing and dev...
Clustering of Symbols Using Minimal Description Length

The clustering of glyphs (individual letters/characters/symbols) is typically the first step in document processing algorithms and a critical enabling technology for most historical document indexing techniques. In this work, we take a step back from current domain/language specialized research efforts to consider the problem from an agnostic perspective. In particular, we claim that, independent of the distance measure used, any method that attempts to cluster all the data is almost certainly doomed to failure. We explain this observation, and introduce a clustering method based on Minimum Description Length (MDL) that can overcome it.
A broadband analysis of the optical properties of silver nanoparticle films by in situ real time spectroscopic ellipsometry

A broadband analysis of the optical properties of silver nanoparticle films over the range from 0.75 to 6.5 eV was performed by applying in situ real-time spectroscopic ellipsometry (RTSE) during the nucleation, coalescence, and bulk thin film growth regimes. The dielectric functions of the particulate films were found to depend strongly on the particle size and film thickness from the nucleation regime throughout coalescence. These dependences were analyzed by separately characterizing the three types of transitions evident in the dielectric function: intraband, particle plasmon polariton, and interband. Throughout the film growth regimes, the thickness evolution of the amplitude, energy, and broadening parameter for each type of transition is discussed in view of the structural characteristics of the films, as corroborated ex situ by atomic force microscopy for films deposited over different time durations.
Anthropological Perspectives on Rural Mexico

Anthropological Perspectives on Rural Mexico. Cynthia Hewitt De Alcantara. Boston: Routledge and Hall, 1984. 245 pp. $59.95 (cloth). ISBN 0-7100-9923-1
Intra-specific variation in the social organization and ecology of Propithecus verreauxi

This paper presents information collected during an 18-month study of four groups of Propithecus verreauxi living in the north-west and south of Madagascar. Various aspects of the s
Structural analysis of glycopeptides by polyacrylamide gel electrophoresis.

Abstract This work describes the use of polyacrylamide gel electrophoresis to resolve fluorescein-derivatized asialoglycopeptides. Specific exoglycosidase digestion of pronase glycopeptides of fetuin generates a series of degradation products that are resolved by polyacrylamide gel electrophoresis and are visualized by photography. The logarithm of the relative electrophoretic mobility of each degraded glycopeptide is linearly correlated to the number of monosaccharide residues sequentially removed by exoglycosidases. Such an approach allows the quantitative evaluation of the number of saccharide moieties removed by each enzyme at a detection sensitivity of less than 20 pmol of each compound. Use of specific endoglycosidases results in the direct sizing of oligosaccharide chains.
Children at risk: perinatal events, developmental delays and the effects of a developmental stimulation program

Abstract This paper reports the findings of two studies done between 1977 and 1981 in the Philippines. The first study examined the performance of 911 children, with histories of perinatal risk events, on a restandardized Philippine (Metro-Manila) version of the Denver Developmental Screening Test (DDST) which was developed in 1980. This study established that the children performed significantly below Philippine norms. A second study, cognizant of the findings of the first, introduced nursing interventions designed to address some needs of preterm infants and their mothers. Findings suggest that development stimulation can significantly improve the developmental status of preterm infants.
Memory hierarchy performance measurement of commercial dual-core desktop processors

As chip multiprocessor (CMP) has become the mainstream in processor architectures, Intel and AMD have introduced their dual-core processors. In this paper, performance measurement on an Intel Core 2 Duo, an Intel Pentium D and an AMD Athlon 64x2 processor are reported. According to the design specifications, key derivations exist in the critical memory hierarchy architecture among these dual-core processors. In addition to the overall execution time and throughput measurement using both multi-program-med and multi-threaded workloads, this paper provides detailed analysis on the memory hierarchy performance and on the performance scalability between single and dual cores. Our results indicate that for better performance and scalability, it is important to have (1) fast cache-to-cache communication, (2) large L2 or shared capacity, (3) fast L2 to core latency, and (4) fair cache resource sharing. Three dual-core processors that we studied have shown benefits of some of these factors, but not all of them. Core 2 Duo has the best performance for most of the workloads because of its microarchitecture features such as the shared L2 cache. Pentium D shows the worst performance in many aspects due to its technology-remap of Pentium 4 without taking the advantage of on-chip communication.
Hot-isostatic pressing of U-10Zr by a coupled grain boundary diffusion and creep cavitation mechanism☆

Abstract To investigate the mechanical response of porous and swelling metallic fuel to cladding restraint, specimens of U-10 wt% Zr were prepared from UH3 + ZrH 2 and U + Zr powders. Specimens were sintered under argon to entrap gas and simulate fission gas bubbles and contained different amounts of rigid precipitates resulting from impurities in the starting powders. Hot-isostatic pressing (HIP) was performed at 600°C (α + δ-phase) and 700°C (γ-phase). The phenomenon of HIP is related to grain boundary diffusion and creep cavitation mechanisms for cavity growth during creep. Densification was not detected at 600°C, but occurred readily at 700°C. The driving force dependence at 700°C (n = 3.7 ± 0.5) and observed loading/ unloading transients are consistent with a creep-controlled HIP mechanism. The activation energy (187 ± 10 kJ/mol) agrees with a reported value for grain boundary diffusion of uranium in γ-U, consistent with a grain boundary diffusion-controlled mechanism. The overall mechanism thus appears to be coupled grain boundary diffusion and creep cavitation. The relevance to in-reactor densification under external pressure or contact stress is also discussed.
Sexual partner concurrency of urban male and female STD clinic patients: a qualitative study.

Partner concurrency (i.e., overlapping sexual partnerships) facilitates the spread of STDs, including HIV. The present study explored the context of and motivations for partner concurrency among patients recruited from an urban STD clinic. Eight focus groups were conducted with 59 patients (47% women; 77% African American). Qualitative analyses revealed five motivational themes related to the occurrence of concurrent partnerships for men and women. Participants reported these partnerships tend to occur: when people believe that sexual partners are unfaithful or cannot be trusted; when sexual satisfaction is low; when patients report the need for different partners to fulfill multiple needs; in retaliation for a partner’s concurrency; and when people wish to maintain a sexual relationship with an ex-partner who is the parent of a shared child. Four additional themes unique to men were identified. Men reported that they had multiple partners because this practice supports their sense of masculinity and is consistent with familial modeling and community norms, and because having multiple partners is “in a man’s nature.” Men also mentioned that the imbalance in the number of women-to-men in their sexual network facilitates partner concurrency. These findings can help prevention practitioners and researchers to develop interventions to reduce risk associated with partner concurrency.
Frequency of Error in American Students' Pronunciation of French

Author's summary.— An examination of frequency and type of error in student pronunciation of French may lead to improved methods for avoiding the commonest difficulties and applying corrective stress where it is most needed.
Good news from Gambia

The Gambia, formerly a slave port and, until 1965, a British colony, lies on the westernmost bulge of Africa, closest to the New World. Jan Morris recalls how in 1937, its capital, Bathurst (now Banjul), was likened by a visiting academic ‘to a water-logged sponge floating in a sea of its own excreta’ [ 13. Now the Gambia provides an up-market seaside destination for those tiring of Hawaii or the Costa de1 Sol. A reminder, however, of colonial days is a Medical Research Council laboratory, the presence of which enabled Hill et al. [2] to acquire evidence associating a particular human class I major histocompatibility complex (MHC) antigen, HLA B*5301, with resistance to severe malaria. A second recent report from this team [3] outlines a strategy that could lead to an understanding of the underlying mechanism of disease resistance and new possibilities for vaccination.
Fiction, indifference, and ontology

In this paper I outline an alternative to hermeneutic fictionalism, an alternative I call indifferentism, with the same advantages as hermeneutic fictionalism with respect to ontological issues but avoiding some of the problems that face fictionalism. the difference between indifferentism and fictionalism is this. the fictionalist about ordinary utterances of a sentence S holds, with more orthodox views, that the speaker in some sense commits herself to the truth of S. It is only that for the fictionalist this is truth in the relevant fiction. According to the indifferentist, by contrast, we are simply non-committal—or indifferent—with respect to some aspects of what is literally said in our assertive utterances (specifically, with respect to the ontologically committing aspects).
Pulse train based generation of tunable THz comb

We present a simple and novel scheme to generate a tunable THz frequency comb using a multi pulse excitation scheme, as well as a comb-like filter in the detection process.
Frames without Lenses: A Response to Hall's ‘What Will it Mean to be Green?’

To survey the volume of research on framing and productively connect it to an issue of immense importance to citizens, scholars, and activists such as climate change is commendable. To have done so...
Use of Growth Hormone Secretagogues to Prevent or Treat the Effects of Aging: Not Yet Ready for Prime Time

In this issue, Nass and colleagues report that at 1 year, an oral ghrelin mimetic increased pulsatile growth hormone secretion and morning insulin-like growth factor I concentration to that in heal...
Acculturation and perceived discrimination: Predictors of substance use trajectories from adolescence to emerging adulthood among Hispanics

Purpose Previous studies have documented associations between cultural factors and substance use among Hispanic adolescents. Negative cultural experiences such as discrimination have been associated with an increased risk of substance use among Hispanic adolescents, whereas positive cultural resources, such as maintenance of Hispanic cultural orientations, have shown protective effects. However, few studies have examined the continuing influence of cultural factors on substance use from adolescence to emerging adulthood.
Expression of functional mammalian P450 2E1 in hairy root cultures.

P450 2E1 is an important mammalian liver enzyme known to metabolize a wide range of compounds including several common environmental pollutants. The medicinal plant, Atropa belladonna, was transformed with Agrobacterium rhizogenes containing a binary vector with rabbit P450 2E1 in either the sense or antisense orientation. The resulting "hairy roots" were isolated and grown in liquid medium. Production of P450 2E1 protein was verified in the roots containing the 2E1 gene in the sense orientation. Transgenic and control root cultures were dosed with the environmental pollutant, trichloroethylene (TCE), and were analyzed for the TCE metabolites, chloral and trichloroethanol. The root cultures expressing the mammalian P450 2E1 had increased levels of the metabolites compared to the levels in the control roots. This method represents a quick way to screen transformants for expression of foreign genes before regeneration of whole plants, and also as a possible source of foreign protein for purification.
Did southerners favor slavery? Inferences from an analysis of prices in New Orleans, 1805–1860

During the years immediately following the American Revolution, it was common for Southern elites to express concerns about the morality or long-term viability of slavery. It is unclear, however, whether such expressions of anti-slavery sentiment were genuine, especially given the failure of so many slave owners to emancipate their slaves. In this paper, we show that there was a change in elite rhetoric about slavery, initiated by Whig politicians in the mid-1830s seeking a campaign issue in the South, in which anti-slavery rhetoric became linked to attempts by abolitionists to foment slave unrest, making anti-slavery an unsustainable position for the region’s politicians. Before that development, we contend that some planters believed that slavery might some day be abolished. After it, those concerns largely went away. We argue that the change in slave owners’ beliefs about the probability of abolition in the mid-1830s should have been reflected in slave prices at auction and test that claim using evidence from the New Orleans auction market.
Reliability of Heat Integration Systems

Abstract Heat integration of multiple processes is currently limited by concern over maintaining operability should a change in one or more process streams affect the heat recovery and operation of subsequent units. To obtain more efficient system designs, it is necessary to accommodate additional integration while preventing system failures. The first step in achieving this is to identify the failure modes of the system. This is followed by incorporating measures to prevent the individual failures leading to the failure of the system. Failure modes of a heat recovery system are discussed and suggestions to contain them are presented. Design considerations are also discussed along with factors that increase or decrease heat recovery system reliability.
Function of the posterior tibial tendon muscle.

Abstract The posterior tibial tendon muscle plays a critical role in the function of the foot. It is, with the exception of the triceps surae, the largest of the extrinsic foot muscles. It is called upon to provide a critical posturing and stabilizing function to the foot during gait. This review discusses the anatomy, physiology, functional characteristics, and measurement of the strength of this muscle.
Exercise testing and electron beam computed tomography in the evaluation of coronary artery disease

OBJECTIVES This study compared coronary artery calcium (CC) as detected by electron beam computed tomography (EBCT) with conventional stress testing in the evaluation of patients with symptoms suggestive of coronary artery disease (CAD). BACKGROUND Exercise electrocardiogram treadmill stress testing (treadmill-ECG) is limited by its requirement of a normal resting ECG and the ability of the patient to exercise adequately. The addition of myocardial imaging agents such as technetium improves the sensitivity and specificity but substantially increases the cost and prolongs the testing time. The use of EBCT provides a noninvasive and rapid method for identifying the presence and amount of CC, which has been shown to be related to atherosclerosis, and may provide additional information in combination with more traditional noninvasive testing methods. METHODS A total of 97 patients underwent technetium stress testing (technetium-stress), treadmill-ECG, and EBCT coronary scanning within three months of coronary angiography for the evaluation of chest pain. RESULTS The relative risk (RR) of obstructive angiographic CAD for an abnormal test was higher for EBCT (4.53) than either treadmill-ECG (1.72) or technetium-stress (1.96). The low specificity of EBCT (47%) was improved by the addition of treadmill-ECG (83%, p < 0.05). CONCLUSIONS Electron beam computed tomography has a higher diagnostic ability than either treadmill-ECG or technetium-stress for the detection of obstructive angiographic CAD. Electron beam computed tomography is an accurate and noninvasive alternative to traditional stress testing for the detection of obstructive CAD in symptomatic patients.
Self-encoded spread spectrum and Turbo coding

Self-encoded multiple access (SEMA) is a unique realization of random spread spectrum. As the term implies, the spreading code is obtained from the random digital information source instead of the traditional pseudo noise (PN) code generators. The time-varying random codes can provide additional security in wireless communications. Multirate transmissions or multi-level grade of services are also easily implementable in SEMA. In this paper, we analyze the performance of SEMA in additive white Gaussian noise (AWGN) channels and Rayleigh fading channels. Differential encoding eliminates the BER effect of error propagations due to receiver detection errors. The performance of SEMA approaches the random spread spectrum discussed in literature at high signal to noise ratios. For performance improvement, we employ multiuser detection and Turbo coding. We consider a downlink synchronous system such as base station to mobile communication though the analysis can be extended to uplink communications.
Evidence for Increased Exposure of the Notch1 Metalloprotease Cleavage Site upon Conversion to an Activated Conformation

Notch proteins are transmembrane receptors that normally adopt a resting state poised to undergo activating proteolysis upon ligand engagement. Receptor quiescence is maintained by three LIN12/Notch repeats (LNRs), which wrap around a heterodimerization domain (HD) divided by furin cleavage at site S1 during maturation. Ligand binding initiates signaling by inducing sensitivity of the HD to proteolysis at the regulated S2 cleavage site. Here, we used hydrogen exchange mass spectrometry to examine the solution dynamics of the Notch1 negative regulatory region in autoinhibited states before and after S1 cleavage, in a proteolytically sensitive “on” state, and in a complex with an inhibitory antibody. Conversion to the “on” state leads to accelerated deuteration in the S2 region and in nearby secondary structural elements within the HD. In contrast, complexation with the inhibitory antibody retards deuteration around the S2 site. Together, these studies reveal how S2 site exposure is promoted by receptor activation and suppressed by inhibitory antibodies.
An Iterative Variable-timestep Algorithm for Molecular Dynamics Simulations

A method for performing variable-timestep molecular dynamics integration is described, in which an iterative algorithm is used to select the largest timestep consistent with the desired simulation accuracy. Accuracy in this context is defined in terms of energy conservation, rather than trajectory correctness. Specifically, a timestep-independent measure of the rate of "diffusion" of the total energy is used. This variable timestep approach is compared to fixed-timestep integration for three different hydrocarbon systems (polyethylene, liquid benzene and ethylene), which are modeled with a reactive bond-order potential. These systems represent both equilibrium and highly non-equilibrium systems at temperatures ranging from 298 to 2500 K. The variable-timestep method is found to be approximately twice as computationally efficient as fixed-timestep integration for the non-equilibrium sputtering of polyethylene, and the two methods were competitive for the equilibrium systems. The algorithm requires the spec...
Regulatory variance of aspartate transcarbamoylase among strains ofYersinia enterocolitica andYersinia enterocolitica-like organisms

Aspartate transcarbamoylase (ATCase) has been isolated and characterized from 20 different strains ofYersinia enterocolitica andY. enterocolitica-like organisms. A variety of regulatory properties have emerged for the ATCases from the different strains. These regulatory properties may be used as a taxonomic tool to divideY. enterocolitica andY. enterocolitica-like organisms into separate groups. Results are in accord with the recent assignment ofY. enterocolitica andY. enterocolitica-like organisms to four DNA-relatedness groups and four correspondingYersinia species.
Kilauea iki lava lake: geophysical constraints on its present (1980) physical state

Abstract A model is presented representing the present-day (1980) configuration of Kilauea Iki lava lake. This interpretation is a synthesis of the results of drilling, thermal modelling, petrology and geophysical sensing experiments. According to this model, the crust of the lava lake is characterized by a thick two-phase convection-dominated zone and a singlephase (steam) dry-out zone. Geophysical measurements (namely electromagnetic sounding experiments) suggest the presence of an anomalous zone which is significantly thicker (more than 30 m thick at 40 m depth) than the zone of melt-slush (10 m thick at 54 m depth seen in petrological investigations of the drill core. This suggests that the geophysically active zone is caused by physical processes not directly related to the presence of magma or that the magma is thinly disseminated over a broader region than indicated in petrological inspections of recent (1979) drill cores. We cannot at this time rule out (or support) the possibility of a plexus of segregation veins distributed throughout the hightemperature region of the lake, particularly below the melt-slush region where information is sparse.
ECOLOGICAL THREAT AND PSYCHOLOGICAL VARIATION

Ecological threats impose substantial selective pressure throughout the animal kingdom, and drive the evolution of specific behavioral and social systems best suited for a given ecological niche. However, the specific role that ecological variables have played in the evolution of human behavior, cognition, and culture has only recently become a topic of rigorous empirical investigation. This paper considers the implications of one specific ecological variable—the threat of infectious disease—for individual behavior, cognition and, ultimately, the evolution of contemporary cultural differences. An emerging body of research conducted at multiple levels of analysis suggests that cross-cultural variation in the threat of disease may be responsible, at least in part, for cultural variation in personality, attitudes, and value systems. This psychological variation may also have downstream consequences for variation in institutions as well. Mechanisms that may account for these relationships and implications are discussed.
Image acquisition system for a hospital enterprise

Hospital enterprises are being created through mergers and acquisitions of existing hospitals. One area of interest in the PACS literature has been the integration of information systems and imaging systems. Hospital enterprises with multiple information and imaging systems provide new challenges to the integration task. This paper describes the requirements at the BJC Health System and a testbed system that is designed to acquire images from a number of different modalities and hospitals. This testbed system is integrated with Project Spectrum at BJC which is designed to provide a centralized clinical repository and a single desktop application for physician review of the patient chart (text, lab values, images).