cssi/SciSciGPT-SciSciNet huggingface dataset:
Black Feminist-Womanist Research Paradigm Toward a Culturally Relevant Research Model Focused on African American Girls

Black Feminist and Womanist theories are culturally based perspectives that take into consideration the contextual and interactive effects of herstory culture, race, class, gender, and other forms of oppression. These frameworks provide a contextualized understanding of African American girls’ experiences and perspectives. The purpose of this article is to provide an overview of the current status of research about African American girls. In addition, this article demonstrates the need for a theoretical perspective that can be used to produce research that accurately examines the lives of African American girls. Major themes of Black Feminist Thought and Womanism will serve as a viable theoretical framework for studying this population. Last, principles of a Black Feminist-Womanist research model will be defined.
Exploiting soil moisture information for adaptive error control in wireless underground sensor networks

Wireless underground sensor networks (WUSNs) have recently been investigated for a wide range of applications. One challenge in wireless underground communications is its high bit error rate, especially at long distances. In WUSNs, the communication quality is substantially affected by the environment, especially the soil moisture. Thus, the underground channel quality can be effectively estimated based on local soil moisture readings. By utilizing the local soil moisture values to estimate the channel quality, adaptive error control mechanisms can be implemented for underground nodes. In this paper, two error control mechanisms, adaptive-rate forward error control and adaptive transmit power control, are considered for WUSNs. The results indicate that compared to ARQ, adaptive FEC code can increase the ranges of soil moisture values within which the network is reliable by reducing the bit error rate. In addition, adaptive transmit power control can improve energy efficiency when a wide range of transmit power levels is available. Our evaluations show that to achieve 60m communication distance in practical soil settings, the output power of the transmitter should to be adjusted in a range of 0dBm to 25dBm to improve the energy efficiency of the underground nodes.
A radioimmunoassay of human circulatory dopamine-β-hydroxylase☆

Abstract A procedure for the radioimmunoassay of human circulatory dopamine-β-hydroxylase (DβH) using antibodies directed toward human DβH is described. A significant correlation between serum DβH activity and the amount of serum immunoreactive (IR) DβH was found in the analyzed population. The radioimmunoassay of serum DβH could be used in monitoring changes of sympathetic activity in various physiological and pathological states.
Robust control structure selection and control system design methods applied to distillation column control

A number of robust control theories are brought together for the purpose of developing systematic methods for control structure selection and controller design. As a case study, a high-purity distillation column separating an ideal binary mixture is considered. It is demonstrated that the structured singular value theory provides a convenient framework for the development of a practical, systematic control structure selection method. The control structure selection method is applied to the sensor selection problem for the high-purity distillation column. In addition, robust control and optimization techniques are combined into a control technique that incorporates such practical aspects as constraint handling and actuator/sensor failure tolerance, as well as robustness. >
Stability of Aeroelastic Airfoils with Camber Flexibility

M AXIMUM lift characteristics and vibratory loading of the rotor are limiting factors in rotorcraft performance [1]. To expand the range of helicopter capabilities, active control methods to improve performance and reduce vibratory loading are being developed. For example, Grohmann et al. [2] produced oscillatory trailing-edge deflections and active trailing-edge tabs by applying layers of piezoelectric fibers on the skin of an airfoil section and activating the piezoelectric fibers at frequencies ranging from ω∕Ω 2 to 6. In hover, aerodynamic pressures reduced the control authority by approximately 20%, indicating that aeroelastic effects must be included to produce an accurate aeroelastic analysis of the blade section. Gandhi et al. [3] designed and optimized a variable-camber blade section by integrating piezoelectric stacks into the blade structure and applying a compliant skin on the blade surface. Highly compliant materials are applied in the construction of active airfoils to reduce the work required to deform the airfoil. Flexibility in camber can adversely affect the stability characteristics of a rotor blade. To determine the effects of camber flexibility on aeroelastic stability, Murua et al. [4] conducted a two-dimensional numerical aeroelastic experiment using the aerodynamic model of Peters et al. for flexible airfoils [5] and included pitch, plunge, and parabolic camber modes. Numerical results indicated that camber effects alone can cause flutter and that the camber mode significantly influences stability boundaries when coupled with pitch and plunge modes. In forward flight and during maneuvers, the increased presence of transonic flow, dynamic stall, and wake effects add to the complexity of the physics. Thus, the solution of the Navier– Stokes equations is required to obtain accurate performance characteristics. The ability of a surface-conforming aeroelastic methodology formed from coupling an unsteady Reynolds-averaged Navier– Stokes (URANS) computational fluid dynamics (CFD) solver with a computational structural dynamics (CSD) code to predict pitch/ plunge and parabolic camber flutter speeds of a thin symmetrical airfoil in incompressible and compressible flow is demonstrated in this work. This CFD/CSD method is believed to be one of the first approaches that includes full-surface morphing for rotating blades in the current published literature.
Designing for selective reading with QuikScan views

Many people--especially knowledge workers--experience information overload, lack sufficient time to read, and therefore choose to read selectively within texts. QuikScan Views is a new Web-based reading environment that provides extensive support for selective reading. It is an enhancement of QuikScan, an empirically validated document format that employs a multiple summary approach to facilitate selective reading, enable quick access to specific ideas in the body of the document, and improve text recall. QuikScan Views provides a hyperlinked table of contents for global navigation, displays QuikScan summaries in a scrolling window (as well as within the body of the document), and adds an extra level of summarization by means of a hyperlinked structured abstract. A QuikScan Views document gives the reader choices of pathways through the document corresponding to the time the reader wishes to invest and the reader's desire to increase their recall of the document.
Hierarchical Fisher And Moment-Based Pattern Recognition

A two-level feature extraction classifier using a geometrical-moment feature space is described for multi-class distortion-invariant pattern recognition. The first-level classifier provides object class and aspect estimates using multi-class Fisher projections and optimized two-class Fisher projections in a hierarchical classifier. Aspect estimates are provided from ratios of the computed moments. The second-level classifier provides the final class estimate, distortion parameter estimates and the confidence of the estimates. Extensive test results on a ship image database are presented.
Infrared Spectroscopy of Highly Excited Vibrational Levels of Protonated Nitrogen, HN + 2

Abstract A difference frequency laser spectrometer along with velocity modulation was used to record the absorption spectrum of molecular ions produced in a glow discharge with a gas mixture of N2/H2/He in a ratio around 1/1/100. Thirty-two new hot bands of HN+2 associated with the ν1 fundamental hand have been observed and analyzed in the spectral region between 2900 and 3500 cm−1. Molecular constants have been determined by litting each observed band toa simple standard power series expansion as well as by using a simultaneous least-squares fit of all the observed bands. The determined molecular constants are believed to be the most complete and accurate available today. Some perturbations and high anharmonicity effects have been revealed. The determined vibrational temperatures associated with the ν1, ν2, and ν3 modes are 4000, 1550, and 3100 K (±10%), respectively. These values, much higher than the evaluated rotational temperature, i.e., 400 K (±10%), reflect our observation of highly excited vibrational levels of HN+2 ion. Some hypotheses on the ion formation and on the relaxation and excitation processes occurring in our discharge are used to comment upon this observation.
Small RNAs in transcriptional gene silencing and genome defence

Small RNA molecules of about 20–30 nucleotides have emerged as powerful regulators of gene expression and genome stability. Studies in fission yeast and multicellular organisms suggest that effector complexes, directed by small RNAs, target nascent chromatin-bound non-coding RNAs and recruit chromatin-modifying complexes. Interactions between small RNAs and nascent non-coding transcripts thus reveal a new mechanism for targeting chromatin-modifying complexes to specific chromosome regions and suggest possibilities for how the resultant chromatin states may be inherited during the process of chromosome duplication.
The Effect of Goal Conflict on Performance

The authors investigated the motivational effects of goal conflict in a complex goal performance setting. Goal conflict was found to have an indirect influence on performance through its relationship with goal commitment. Goal conflict was negatively associated with goal commitment when controlling for the other antecedents, including expectancy, self-efficacy, and need for achievement. As predicted, goal commitment and self-efficacy were related to goal-directed behaviors and goal-directed behaviors were related to performance. Performance was positively related to positive outcome emotions and negatively related to negative outcome emotions. The authors discuss the implications for the professional practitioner, theory development, and future research.
The poly(rU) coil: a minimum-energy model that matches experimental observations.

A model of the randomly coiling form of poly(rU) based on minimum-energy conformers of UpU is described. The blend of conformers is chosen to fit the CC rotational populations derived in nmr studies of UpU and poly(rU) and to match the experimental unperturbed dimensions of the poly(rU) chain. In addition, estimates of loop closure based on the model are comparable to the sizes of loops most frequently seen in model oligonucleotides. Approximately 60% of the conformers constituting the model are characterized by stacked, extended C2′-endo ω′ωψ = tg−g+ rotations. The remainder of the chain is described by equal numbers of C3′-endo A (ω′ωψ = g−g−g+) and Watson-Crick (ω′ωψ = g−tt) helical arrangements.
Circuits of power, circuits of pleasure: Sexual scripting in gay men’s bottom narratives

This article explores the meanings 18 HIV-negative gay male participants in San Francisco attributed to their positional identity as ‘bottoms’. In particular, I analyze two dominant, mutually const...
Go-and -V, come-and -V, go -V and come -V: A corpus-based account of deictic movement verb constructions

The present paper aims to complement recent work on deictic movement verb constructions by using a corpus-based approach to identify differences between the four deictic movement verb constructions: go-and-V, come-and-V, go-V and come-V, and to evaluate the proposal made in Nicolle (2007) that go/come-V developed from go/come-and-V in the context of imperative clauses. It will be shown that this is a possible scenario for the development of go-V from go-and-V, although come-V may have developed by analogy with go-V rather than independently from come-and-V. Finally, subjectification will be proposed as a motivating factor in the development of both go-V and come-V.
Activated polymorphonuclear cells promote injury and excitability of dorsal root ganglia neurons

Therapies aimed at depleting or blocking the migration of polymorphonuclear leukocytes (PMN or neutrophils) are partially successful in the treatment of neuroinflammatory conditions and in attenuating pain following peripheral nerve injury or subcutaneous inflammation. However, the functional effects of PMN on peripheral sensory neurons such as dorsal root ganglia (DRG) neurons are largely unknown. We hypothesized that PMN are detrimental to neuronal viability in culture and increase neuronal activity and excitability. We demonstrate that isolated peripheral PMN are initially in a relatively resting state but undergo internal oxidative burst and activation by an unknown mechanism within 10 min of co-culture with dissociated DRG cells. Co-culture for 24 h decreases neuronal count at a threshold 25 microm diam) neurons, as well as in capsaicin-sensitive neurons. Furthermore, small size isolectin B4-labeled neurons undergo hyperexcitability manifested as decreased current threshold and increased firing frequency. Although co-culture of PMN and DRG cells does not perfectly model neuroinflammatory conditions in vivo, these findings suggest that activated PMN can potentially aggravate neuronal injury and cause functional changes to peripheral sensory neurons. Distinguishing the beneficial from the detrimental effects of PMN on neurons may aid in the development of more effective drug therapies for neurological disorders involving neuroinflammation, including painful neuropathies.
Molecular Determinants of Scouting Behavior in Honey Bees

Little is known about the molecular basis of differences in behavior among individuals. Here we report consistent novelty-seeking behavior, across different contexts, among honey bees in their tendency to scout for food sources and nest sites, and we reveal some of the molecular underpinnings of this behavior relative to foragers that do not scout. Food scouts showed extensive differences in brain gene expression relative to other foragers, including differences related to catecholamine, glutamate, and γ-aminobutyric acid signaling. Octopamine and glutamate treatments increased the likelihood of scouting, whereas dopamine antagonist treatment decreased it. These findings demonstrate intriguing similarities in human and insect novelty seeking and suggest that this trait, which presumably evolved independently in these two lineages, may be subserved by conserved molecular components.
Thermoelectric Power of Dilute Cu-Ni Alloys in a Magnetic Field

The thermoelectric powers (TEP) of four dilute CuNi alloys and one CuCo alloy have been measured in the presence of a transverse magnetic field. The presence of the field did not induce any anomalous behavior in the TEP. There seems to be no systematic field effect in the temperature range of 4.2 to 20\ifmmode^\circ\else\textdegree\fi{}K, and the maximum change due to a 10-kOe field was 0.05 \ensuremath{\mu}V/\ifmmode^\circ\else\textdegree\fi{}K. The temperature dependence of the absolute TEP of the CuNi alloys suggested that the diffusion component might follow a Gorter-Nordheim relation. An analysis consistent with this relation and assuming an unsplit virtual state is presented.
Early Writing Deficits in Preschoolers With Oral Language Difficulties

The purpose of this study was to investigate whether preschool children with language impairments (LI), a group with documented reading difficulties, also experience writing difficulties. In addition, a purpose was to examine if the writing outcomes differed when children had concomitant cognitive deficits in addition to oral language problems. A group of 293 preschool children were administered an assessment battery that included measures to examine oral language, nonverbal cognition, emergent reading, and writing. Children were divided into four groups based on their language and cognitive performance. The findings from this study show that as early as preschool, children with weaker oral language skills lag behind their peers with stronger oral language skills in terms of their writing-related skills. Children with oral language and cognitive deficits performed more poorly than children whose deficits were confined to oral language. A child's cognitive ability also has an impact on emergent writing skills, but it appears to be moderated by oral language skills. These results are consistent with research documenting links between preschool language and emergent reading in children with a history of LI.
Marital status and female and male contraceptive sterilization in the United States.

Objective To examine female and male sterilization patterns in the United States based on marital status, and to determine if sociodemographic characteristics explain these patterns. Design Survival analysis of cross-sectional data from the female and male samples from the 2006–2010 National Survey of Family Growth. Setting Not applicable. Patient(s) The survey is designed to be representative of the US civilian noninstitutionalized population, ages 15–44 years. Intervention(s) None. Main Outcome Measure(s) Vasectomy and tubal sterilization. Result(s) In the United States, vasectomy is the near-exclusive domain of married men. Never-married and ever-married single men, and never-married cohabiting men, had a low relative risk (RR) of vasectomy (RR = 0.1, 0.3, and 0.0, respectively), compared with men in first marriages. Tubal sterilization was not limited to currently married, or even to ever-married women, although it was less common among never-married single women (RR = 0.2) and more common among women in higher-order marriages (RR = 1.8), compared with women in first marriages. In contrast to vasectomy, differential use of tubal sterilization by marital status was driven in large part by differences in parity. Conclusion(s) This study shows that being unmarried at the time of sterilization—an important risk factor for poststerilization regret—was much more common among women than men. In addition to contributing to the predominance of female, vs. male, sterilization, this pattern highlights the importance of educating women on the permanency of sterilization, and the opportunity to increase reliance on long-acting reversible contraceptive methods.
Acridine orange fluorescence in paraffin sections.

The technique of staining with acridine orange for fluorescence microscopy of fresh animal and plant cells, chiefly for the detection of ribonucleic acid in the cytoplasm, was brought to a high degree of perfection by Schummelfeder (1950) and has been developed further by Bertalanffy and Bickis (1956). Its employment for cancer detection in smears was reviewed by Bertalanffy, Masin and Masin in 1956.
Early Flower Bud Loss and Mepiquat Chloride Effects on Cotton Yield Distribution

Abscission or abortion of the initial cotton (Gossypium hirsutum L.) flower buds or bolls increases the importance of retaining fruit on adjacent or subsequent fruiting positions. Use of the plant growth regulator mepiquat chloride (MC) (N, N dimethylpiperidinium chloride) improves boll retention on lower reproductive branches (sympodia), reduces vegetative growth, and in some cases reduces upper sympodial productivity. Our objective was to determine the effect of doses and application timings of MC and different levels of early flower bud removal on within-plant yield distribution. Zero or an average of two or four flower buds located at first positions on lower sympodia were removed from each plant prior to MC applications at two field locations in 1992. This bud loss resulted in higher retention at second positions on lower sympodia and on slightly higher sympodia. Two biweekly doses of 24.5 g ha -1 of MC applied at early bloom also enhanced compensation and yield on lower sympodial second positions. Primarily at one location, four weekly MC doses of 12.25 g ha -1 each beginning when buds were 1 cm long resulted in increased monopodial branch yield when there was moderate early bud loss. Depending on field location, one or the other of the MC treatments reduced the number of fruiting positions and yield on higher sympodia when fruit retention on lower sympodia was high. Loss of early buds, which resulted in small increases in vegetative growth, ameliorated this effect. The biological responses produced by early bud loss and MC treatments interacted positively. After early bud loss, plants treated with MC generally improved compensation on lower sympodia without negative effects on upper sympodia.
The aging of rat liver as revealed by electron microscopic morphometry--I. Basic parameters.

Abstract One-, 12- and 27-month-old female rats (5 in each group) were investigated by means of point-counting morphometry at light and electron microscopic sampling levels. Morphometric parameters are given for single hepatocytes, per unit volume of tissue and as specific values, i.e. per 100 g body weight. Many liver parameters showed age-dependent changes between the young and adult or between the adult and old ages. The most important stereologic manifestation of aging was the very strong reduction of surface area, surface density and specific surface density values of rough endoplasmic reticulum between the adult and old groups. This finding explains the decreased protein synthetic activity of old rat liver. Other parameters also changed, however, e.g. in case of mitochondria the interpretation is difficult because of a considerable swelling observed only in the old animals. Lysosomal elements showed no significant age-dependent changes. Some methodical problems of morphometry are also discussed.
Before Antikythera: the First Underwater Archaeological Survey in Greece

The aim of this article is to introduce to the international bibliography a report submitted to the Archaeological Society of Athens by Ephor Christos Tsoundas in 1885 summarizing what was to be the first state-sponsored underwater archaeological survey in Greece, and potentially the first such survey in general. A brief introduction is followed by a translation of the decision to conduct the survey, as well as of the final report submitted the following year. The fascinating insight which Tsoundas demonstrates in the report allows us a glimpse of the beginnings of underwater archaeology at the worthy site of the Battle of Salamis. © 2006 The Author
Perspectives on Rehabilitation Research

Gordon WA. Perspectives on rehabilitation research. The author provides his perspectives on both the methodologic and funding challenges faced by rehabilitation researchers. His concerns are conveyed about the devaluing of rehabilitation research by federal funding agencies and Congress.
Serum gonadotropin and testosterone levels in uremic males undergoing intermittent dialysis

Abstract Twenty-six adult males with uremia due to chronic renal disease were studied to determine the circulating levels of gonadotropins. In some of these patients serum testosterone levels were also measured. Patients receiving intermittent hemodialysis had higher levels of luteinizing hormone (LH) than normals, uremic patients not receiving dialysis and patients on peritoneal dialysis. Serum testosterone levels tended to be low in uremic patients. No significant alterations in follicle-stimulating hormone (FSH) were observed in the groups studied. Uremia seems to effect Leydig cell function without producing an associated rise in gonadotropins with the exception of an increase in LH in patients on intermittent hemodialysis.
Aquaculture and environmental stewardship: Milford shellfish biology seminar—1991

For the past 11 years the annual Shellfish Biology Seminar at Milford CT has provided a unique forum for aquaculture scientists and industry officials to exchange information about estuaries facing increased pollution problems, especially Long Island Sound and the Great South Bay. Because these two areas are so rich in productivity and diversity, fish and shellfish farmers utilize their waters, shellfish beds, and shore land for hatcheries and grow-out facilities. These individuals seek better management of the coastal estuarine environment and its resources, providing a working example of environmental stewardship. In aquaculture, good science is required to understand the complex variables and interaction of estuarine currents, tides, temperature, and cycles of reproduction. Aquaculturists are beginning to understand the need for specific nutrients and how the wastes of one species can be utilized for enhanced production of another species. Over the years, this meeting has formed an amalgam of both the aquaculture industry and research scientists where both groups foster mutual environmental concern. Science is able to focus on the theoretical aspects of pollutant damage. while the aquaculture industry is able to define the problem and need for assistance to eliminate pollutants from their crops—shellfish and finfish. Overfishing is not an issue at these meetings, as the group accepts the damage already done to wild resources and seeks new technologies to grow food sources under controlled and stable market conditions. Therefore, it could be said that the seminar serves as a meeting ground where the theoretical knowledge of scientific study finds practical application in the industry and is fueled by the needs of that industry. This ideal blend of the two groups produces better management of the resource and a safer environment—the goal of stewardship.
Rate Modulated Pacing Based on Right Ventricular dP/dt: Quantitative Analysis of Chronotropic Response

Right ventricular contractility increases in response to catecholamine stimulation and greater ventricular preload, factors that increase with exercise workload. Thus, the maximum systolic dP/dt may be a potentially useful sensor to control the pacing rate of a permanent pacing system. The present study was designed to test the long-term performance of a permanent pacemaker that modulates pacing rate based on right ventricular dP/dt and to quantitatively analyze the chronotropic response characteristics of this sensor in a group of patients with widely varying structural heart diseases and degrees of hemodynamic impairment. A permanent pacing system incorporating a high fidelity pressure sensor in the lead for measurement of right ventricular dP/dt was implanted in 13 patients with atrial arrhythmias and AV block, including individuals with coronary artery disease, hypertension, severe obstructive pulmonary disease with prior pneumonectomy, atrial septal defect, dilated cardiomyopathy, restrictive cardiomyopathy, and mitral stenosis. Patients underwent paired treadmill exercise testing in the VVI and VVIR pacing modes with measurement of expired gas exchange and quantitative analysis of chronotropic response using the concept of metabolic reserve. The peak right ventricular dP/dt ranged from 238-891 mmHg/sec with a pulse pressure that ranged from 19-41 mmHg. There was a positive correlation between the right ventricular dP/dt and pulse pressure (r = 0.70, P = 0.012). The maximum pacing rate and VO2max were 72 +/- 6 beats/min and 12.61 +/- 4.0 cc O2/kg per minute during VVI pacing and increased to 124 +/- 18 beats/min and 15.89 +/- 5.9 cc O2/kg per minute in the VVIR pacing mode (P < 0.0003 and P < 0.002, respectively). The integrated area under the normalized rate response curve was 96.7 +/- 45.7% of expected during exercise and 100.1 +/- 43.4% of expected during recovery. One patient demonstrated an anomalous increase in pacing rate in response to a change in posture to the left lateral decubitus position. Thus, the peak positive right ventricular dP/dt is an effective rate control parameter for permanent pacing systems. The chronotropic response was proportional to metabolic workload during treadmill exercise in this study population with widely varying forms of structural heart disease.
Molecular characterization of a monoclonal antibody produced in response to a group C meningococcal polysaccharide peptide mimic

We have developed a monoclonal antibody, designated anti-anti-Id Ab3-2C4 which reacts with Neisseria meningitidis serogroup C polysaccharide (MCPS). Anti-anti-Id Ab3-2C4 was produced by immunizing Balb/C mice with a peptide mimic of MCPS. This monoclonal antibody reacts with native polysaccharide and its anti-idiotype antibody Ab2-6F9 by ELISA. The synthetic peptide mimic was constructed based on the sequence of the VHCDR3 region of the anti-idiotype Ab2-6F9. We compared the cDNA sequence of Ab3-2C4 to the sequence of idiotype antibody Ab1-1E4 produced in response to native MCPS. The predicted amino acid sequence of the unique VHCDR3 of anti-anti-Id Ab3-2C4 is similar to that of idiotype Ab1-1E4. Also the VHCDR3 of both antibodies is similar to some of the known or suggested carbohydrate binding motifs. A different VH gene family was utilized by Ab3-2C4 than by Ab1-1E4. These results suggest that immunization with the anti-idiotype-derived peptide mimic of the MCPS antigen stimulates the production of antibodies with a binding site structurally related to idiotype antibodies, even though the antibodies Ab1-1E4 and Ab3-2C4 are not related in gene families. Our results support the premise that the use of peptide antigens which are mimics of carbohydrates is an alternate vaccine strategy for polysaccharide antigens and results in an appropriate response.
Photopolymerized sol-gel frits for packed columns in capillary electrochromatography

Porous sol-gel frits are fabricated in a capillary column by filling it with a solution of 3-(trimethoxysilyl)propyl methacrylate, hydrochloric acid, water, toluene (porogen), and a photoinitiator (Irgacure 1800) and exposing it to UV light at 365 nm for 5 min. The separation column (30 cm x 75 microm I.D.) contains between the inlet and outlet frits a 15-cm packed segment filled with 5-microm silica particles modified with the chiral compound (S)-N-3,5-dinitrobenzoyl-1-naphthylglycine. A detection window (1 mm long) is placed immediately after the outlet frit. To demonstrate the performance of this chiral separation column, mixtures of 16 different amino acids (three of which are not naturally occurring) derivatized with the fluorogenic reagent 4-fluoro-7-nitro-2,1,3-benzoxadiazole were separated by capillary chromatography. The enantiomeric separation of the column results in a resolution ranging from 1.21 to 8.29, and a plate height ranging from 8.7 to 39 microm.
Origins of life: A comparison of theories and application to Mars

The field of study that deals with the origins of life does not have a consensus for a theory of life's origin. An analysis of the range of theories offered shows that they share some common features that may be reliable predictors when considering the possible origins of life on another planet. The fundamental datum dealing with the origins of life is that life appeared early in the history of the Earth, probably before 3.5 Ga and possibly before 3.8 Ga. What might be called the standard theory (the Oparin-Haldane theory) posits the production of organic molecules on the early Earth followed by chemical reactions that produced increased organic complexity leading eventually to organic life capable of reproduction, mutation, and selection using organic material as nutrients. A distinct class of other theories (panspermia theories) suggests that life was carried to Earth from elsewhere--these theories receive some support from recent work on planetary impact processes. Other alternatives to the standard model suggest that life arose as an inorganic (clay) form and/or that the initial energy source was not organic material but chemical energy or sunlight. We find that the entire range of current theories suggests that liquid water is the quintessential environmental criterion for both the origin and sustenance of life. It is therefore of interest that during the time that life appeared on Earth we have evidence for liquid water present on the surface of Mars.
INTRA-POPULATION DIFFERENTIATION IN ANNUAL PLANTS I. VERONICA PEREGRINA L. RAISED UNDER NON-COMPETITIVE CONDITIONS.

Early neo-Darwinian theory held that for differentiation to occur between populations, barriers to gene flow are needed which isolate gene pools from one another. However, several recent reviews point out that differentiation can occur without such barriers, particularly in plants (Jain and Bradshaw, 1966; Ehrlich and Raven, 1969; Bradshaw, 1972). These authors emphasize that if disruptive selection is strong enough, different adaptive modes can arise within one gene pool despite the mixing effect of gene exchange. In most studies, the environments discussed appear to provide very stringent selective forces, such as exposure to, versus protection from, saline conditions in maritime habitats (Gregor, 1930; Aston and Bradshaw, 1966), or high levels versus traces of heavy metals (Antonovics et al., 1971) or fertilizers (Snaydon and Davies, 1972) in soils. In most cases, natural populations do not span habitats which contrast so harshly, but occur over complex gradients of interacting physical and biotic conditions. Commonly the majority of a population resides within a given community but some peripheral individuals grow in another community. For example, at the interface of forest-grassland communities, some individuals of forest species may be found in the grassland, and vice versa. Are the peripheral individuals genetically the same as those in the main body of the population and did they survive by chance, or are they different from the majority, and adapted to the marginal conditions? Conversely, are individuals in the main body of a population characterized by features of adaptive value in their specific environment? The major goal of this work has been to investigate these questions in two populations of Veronica peregrina L. (Scrophulariaceae), each growing within and around the periphery of a temporary pool in Solano County, California.
Progress Of Erasable Phase-Change Materials

The current status of erasable phase-change recording materials is re-viewed. Using GeTeSn-based materials as examples, dynamic perform-ance data are presented along with discussions of the basic physical mechanisms determining media performance. For applications requiring limited number of cycles, phase-change materials have been developed to a very practical level.
Slow Detrapping Transients due to Gate and Drain Bias Stress in High Breakdown Voltage AlGaN/GaN HEMTs

Charge trapping and slow (from 10 s to >; 1000 s) detrapping in AlGaN/GaN high electron mobility transistors (HEMTs) designed for high breakdown voltages ( >; 1500 V) is studied through a combination of electrical, thermal, and optical methods to identify the impact of Al molefraction and passivation on trapping. Trapping due to 5-10 V drain bias stress in the on-state (Vgs = 0) is found to have significantly slower recovery, compared with trapping in the off-state (Vgs <; Vth, Vds = 0). Two different trapping components, i.e., TG1 (Ea = 0.6 eV) and TG2 (with negligible temperature dependence), in AlGaN dominate under gate bias stress in the off-state. Al0.15Ga0.85N shows much more vulnerability to trapping under gate stress in the absence of passivation than does AlGaN with a higher Al mole fraction. Under large drain bias, trapping is dominated by a much deeper trap TD. Detrapping under monochromatic light shows TD to have Ea 1.65 eV. Carbon doping in the buffer is shown to introduce threshold voltage shifts, unlike any of the other traps.
On the logical basis of the structuralist philosophy of science

At the present stage of the so called structuralist approach to the philosophy of science, there seems to be some difficulties which are purely logical. Since this approach has an increasing influence on philosophers and it seems to be potentially very fertile, it may be important to try to remove them. I have already criticized some of them in [7], but here I will make some positive suggestions which are more detailed than in that paper. By the structuralist (or set-theoretical) philosophy of science I mean, ac? cording to the current terminology, the approach whose basic principles can be found in Sneed [10], Stegm?ller [12], etc. It will be assumed here that the reader is familiar with it. These logical difficulties can be divided into two general groups. First, the structuralists claim that they use intuitive (naive) set theory as the framework in characterizing the logical structure and dynamics of empirical theories. However, intuitive set theory has to be used cautiously, as we have been taught by the set-theorists of this century. Thus the following problems can? not be ignored in the foundational studies of set theory: What kinds of entities can be intuitively regarded as sets? What set-theoretical operations can be consistently applied to different entities occurring in set theory? Now it seems that the structuralists have ignored (deliberately?) the advice of the set-theorists in these problems, with the result that their system is inconsis? tent. The basic set-theoretical trouble in the structuralist approach derives, roughly, from the fact that it attempts to replace sentences by collections of models without noticing that it can mean a change of entities which are sets for entities which are not. This does not mean of course that the structuralist system would not be useful. But it could be better to use intuitive set theory so that it would not lead into perspicuous contradictions and would better correspond to our more or less trained intuitions. Therefore, I will make some suggestions that will maintain, as I hope, the main lines of the structuralist approach. The second difficulty is related to model theory. The structuralists operate with concepts whose analogs can be found in general model theory. However,
2009 AFHVS presidential address: the steering question: challenges to achieving food system sustainability.

In this address I examine the challenges of achieving food system sustainability. Starting from the position that most people want a food system that is “sustainable” and that we have a great reservoir of unapplied technical knowledge applicable to increasing sustainability, I argue that the big issue is collective decision-making to accomplish the goal of sustainability. Using the metaphor of a sailing ship, I raise three questions about steering collectively toward sustainability: What do we want? What are our options? And, how do we decide among the options?
A neighboring optimal feedback control scheme for systems using discontinuous control

The calculation and implementation of the neighboring optimal feedback control law for multiinput, nonlinear dynamical systems, using discontinuous control, is discussed. An initialization procedure is described which removes the requirement that the neighboring initial state be in the neighborhood of the nominal initial state. This procedure is a bootstrap technique for determining the most appropriate control-law gain for the neighboring initial state. The mechanization of the neighboring control law described is closed loop in that the concept of time-to-go is utilized in the determination of the control-law gains appropriate for each neighboring state. The gains are chosen such that the time-to-go until the next predicted switch time or predicted final time is the same for both the neighboring and nominal trajectories. The procedure described is utilized to solve the minimum-time satellite attitude-acquisition problem.
Improving device performance and process manufacturability through the use of TCAD

The use of TCAD as a powerful tool for improving device performance and process manufacturability is describe din this paper. The ability for TCAD simulation to provide quick insight and understanding to better pMOS heavy doped drain extension design is illustrated. The impact of surface dielectric property and interface condition on the HDD diffusion profile, the transistor performance, and the transistor parametric variation is discussed through the use of SIMS profiles, simulation results, and silicon dat. Significant changes in HDD profile, transistor characteristics and parametric variability are attributed to surface oriented dopant diffusion. The severity of such changes can vary with varying surface dielectric properties. Through TCAD simulations, we postulate that the surface oriented dopant diffusion is mainly due to the existence of a super steep interstitial gradient (SSIG), in addition to SPE dopant transport effects. Monte Carlo implant simulations using UT-Marlowe and SIMS profiles how that higher-energy-lower-dose HDD implant would produce a better HDD diffusion profile of same junction depth than lower- energy-higher-dose HDD implant does, as a result of SSIG. SIMS experiments designed to reduce surface oriented diffusion by using Ge and F co-implant are discussed. The SIMS profiles show that Ge is able to reduce surface oriented dopant diffusion by steric effects, but F co- implant produces the best HDD profile.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The Frank-Kamenetskii problem revisited, part II: Gradient boundary conditions☆

Abstract The thermal explosion problem which was posed by Frank-Kamenetskii to explain ignition has been examined in Part I. In the present work, we extend the analysis to include the gradient boundary conditions. Cooling boundary conditions are shown to cause ignition when the steady state solutions occur within the unstable region found in the previous work of Part I. A three dimensional plot of characteristic parameters for the heating boundary conditions is found to form an unstable region that defines the critical conditions. The symmetrical temperature boundary condition studied in Part I is shown to be only a special case of the heating problem. A summary of the results obtained is presented here while the details of the study are published in Reference [1].
Numerical studies on plasma plume flows from a cluster of electric propulsion devices

Abstract Several hybrid fluid–particle simulations are performed to investigate the plasma plume flows from a cluster of Hall thrusters. These simulations adopt a detailed fluid electron model to describe electron properties. A general finite element solver is developed to solve for these electron properties, and the cathode geometry, facility effects, and vacuum chamber background pressure are included in the simulations; these are compared with available experimental data, and indicate that the cathode had effects on some flow property distributions. They also clearly display charge exchange collision effects and the clustering effects. There exist complex three-dimensional near field structures in the ion number density with Hall thrusters in operation. With four thrusters in operation, a severe impingement is expected right behind the cluster center. Compared with axisymmetric simulations, these three-dimensional simulations have several improvements. When compared with the Boltzmann relation, the detailed fluid electron model displays superiority in predicting the electron temperature as well.
Relationship between the measurement of accommodation and after-effect

Abstract After-effect and accommodation were measured for two types of magnetic materials: nanoparticle pure iron material and a commercial γFe 2 O 3 recording material. The time scale of the observation was from about 10–1000 s. The after-effect was measured by rapidly changing the applied field from positive saturation to a fixed value, H , which was subsequently unchanged for the duration of the measurement. The after-effect was proportional to the logarithm of time. The accommodation was found to be proportional to the logarithm of the number of cycles, and hence also to the logarithm of time. For both samples, it was found that the after-effect curve with the greatest slope occurs at the value of H given by the remanent coercivity, H ci , and not simply near the coercivity, H c , as previously reported. This is attributed to the fact that, when measuring the time-dependence in the customary manner, a change in the interaction field also causes an accommodation-like drift in the magnetization. Using a physically derived accommodation model, it has been shown that the maximum accommodation minor loop field extrema have a small separation compared to the major loop width, then the after-effect and accommodation slopes are nearly identical and the two phenomena are then difficult to distinguish from each other.
Nelative-Working Electron Beam Resist Based on Poly(methylmethacrylate)

Blends of polymethylmethacrylate (PMMA) and dipentaerythritol pentaacrylate (DPEPA) respond to electron beam exposure as negative resists, with sensitivity that increases with increasing DPEPA concentration. Blends of 80 wt. % PMMA (Mn 22,500) and 20 wt. % DPEPA exhibit an electron sensitivity of 4 μC/cm 2 (based on 50% of exposed film remaining) and a contrast (γ) of 1.2. Resolution of 0.25 μm has been demonstrated with this blend without the use of non-solvent rinses or plasma de-scumming. This superior resolution for a negative electron resist is attributed to the small degree of swelling of the PMMA host polymer. Increasing the molecular weight of the PMMA component to 450,000 (M w ) increases the sensitivity to 1 μC/cm 2 , but results in poorer resolution. Use of nearly monodisperse PMMA (M n ≈ M w = 29,000) improves the contrast to a γ value of 2.3 without affecting resolution or sensitivity relative to the blends with low molecular weight PMMA. Image formation in these blends is largely controlledby differential dissolution rates, with reactive plasticizer (DPEPA) enhancing dissolution in unexposed regions and inhibiting dissolution after exposure. The degree of polymerization and crosslinking of the plasticizer necessary for inhibiting dissolution rates is less than that required for complete insolubilization of the resist film. Thus, exposure at moderate doses results not only in a non-swelling image, but also one that is easily stripped with developing solvent after processing. This mechanism differs greatly from that of conventional crosslinking negative electron beam resists for which exposure renders the exposed regions insoluble in any developing solvent.
Molecular and Phylogenetic Analyses of the MADS-Box Gene Family in Tomato

MIKCc-type MADS-box genes encode key transcriptional regulators of a variety of developmental processes in Arabidopsis thaliana. However, there has been relatively little effort to systematically carry out comparative genomic or functional analyses of these genes across flowering plants. Here we describe a strategy to identify members of the MIKCc-type MADS-box gene family from any angiosperm species of interest. Using this approach, we have identified 24 MIKCc-type MADS-box genes in tomato, including 17 that have not previously been characterized. Using these sequences, we have performed phylogenetic analyses that indicate that there have been a number of gene duplication and loss events in tomato relative to Arabidopsis. We also describe the expression domains of these genes and compare these results with their cognates in Arabidopsis. These analyses demonstrate the utility of this approach for characterizing a large number of MIKCc-type MADS-box genes from any flowering plant species of interest and provide a framework for evolutionary comparisons of this important gene family across angiosperms.