cssi/SciSciGPT-SciSciNet huggingface dataset:
Reward Functioning Abnormalities in Adolescents at High Familial Risk for Depressive Disorders.

Abstract Background A parental history of major depressive disorder (MDD) is an established risk factor for MDD in youth, and clarifying the mechanisms related to familial risk transmission is critical. Aberrant reward processing is a promising biomarker of MDD risk; accordingly, the aim of this study was to test behavioral measures of reward responsiveness and underlying frontostriatal resting activity in healthy adolescents both with (high-risk) and without (low-risk) a maternal history of MDD. Methods Low-risk and high-risk 12- to 14-year-old adolescents completed a probabilistic reward task (n = 74 low-risk, n = 27 high-risk) and a resting-state functional magnetic resonance imaging scan (n = 61 low-risk, n = 25 high-risk). Group differences in response bias toward reward and resting ventral striatal and medial prefrontal cortex (mPFC) fractional amplitude of low-frequency fluctuations (fALFFs) were examined. Computational modeling was applied to dissociate reward sensitivity from learning rate. Results High-risk adolescents showed a blunted response bias compared with low-risk adolescents. Computational modeling analyses revealed that relative to low-risk adolescents, high-risk adolescents exhibited reduced reward sensitivity but similar learning rate. Although there were no group differences in ventral striatal and mPFC fALFFs, groups differed in their relationships between mPFC fALFFs and response bias. Specifically, among high-risk adolescents, higher mPFC fALFFs correlated with a blunted response bias, whereas there was no fALFFs–response bias relationship among low-risk youths. Conclusions High-risk adolescents exhibit reward functioning impairments, which are associated with mPFC fALFFs. The blunted response bias–mPFC fALFFs association may reflect an excessive mPFC-mediated suppression of reward-driven behavior, which may potentiate MDD risk.
Design Methodology for Distributed Large-Scale ERSFQ Bias Networks

Rapid single-flux quantum (RSFQ) circuits have recently attracted considerable attention as a promising cryogenic beyond CMOS technology for exascale computing. Energy-efficient RSFQ (ERSFQ) is an energy-efficient, inductive bias scheme for RSFQ circuits, where the power dissipation is drastically lowered by eliminating the bias resistors, while the cell library remains unchanged. An ERSFQ bias scheme requires the introduction of multiple circuit elements—current limiting Josephson junctions, bias inductors, and feeding Josephson transmission lines (FJTLs). In this article, parameter guidelines and design techniques for ERSFQ circuits are presented. The proposed guidelines enable more robust circuits resistant to severe variations in supplied bias currents. Trends are considered, and advantageous tradeoffs are discussed for the different components within a bias network. The guidelines provide a means to decrease the size of an FJTL and, thereby, reduce the physical area, power dissipation, and overall bias currents, supporting further increases in circuit complexity. A distributed approach to ERSFQ FJTL is also presented to simplify placement and minimize the effects of the parasitic inductance of the bias lines. This methodology and related circuit techniques are applicable to automating the synthesis of bias networks to enable large-scale ERSFQ circuits.
Non-singular "Gauss" black hole from non-locality: a simple model with a de Sitter core, mass gap, and no inner horizon

Cutting out an infinite tube around $r=0$ formally removes the Schwarzschild singularity, but without a physical mechanism this procedure seems ad hoc and artificial. In this Essay we provide such a mechanism by means of non-locality. Motivated by the Gauss law we define a suitable radius variable as the inverse of a regular non-local potential, and use this variable to model a non-singular black hole. The resulting geometry has a de Sitter core, but for generic values of the regulator there is no inner horizon, saving this model from potential issues via mass inflation. An outer horizon only exists for masses above a critical threshold, thereby reproducing the conjectured "mass gap" for black holes in non-local theories. The geometry's density and pressure terms decrease exponentially, thereby rendering it an almost-exact vacuum solution of the Einstein equations outside of astrophysical black holes.
Inhibition of the futalosine pathway for menaquinone biosynthesis suppresses Chlamydia trachomatis infection.

Chlamydia trachomatis, an obligate intracellular bacterium with limited metabolic capabilities, possesses the futalosine pathway for menaquinone biosynthesis. Futalosine pathway enzymes have promise as narrow-spectrum antibiotic targets, but the activity and essentiality of chlamydial menaquinone biosynthesis have yet to be established. In this work, menaquinone-7 (MK-7) was identified as a C. trachomatis-produced quinone through liquid chromatography-tandem mass spectrometry. An immunofluorescence-based assay revealed that treatment of C. trachomatis-infected HeLa cells with the futalosine pathway inhibitor docosahexaenoic acid (DHA) reduced inclusion number, inclusion size, and infectious progeny. Supplementation with MK-7 nanoparticles rescued the effect of DHA on inclusion number, indicating that the futalosine pathway is a target of DHA in this system. These results open the door for menaquinone biosynthesis inhibitors to be pursued in antichlamydial development.
Towards defining and advancing ‘Made in Africa Evaluation’

Background: Most evaluation in Africa is rooted in dominant neoliberal Western approaches. Imported Western evaluation frames may lack multicultural validity and can lead to wrong conclusions and poor development outcomes. They may also reinforce subjugation and cultural hegemony through neo-imperialism and colonisation of the imaginations of those concerned. The Made in Africa Evaluation (MAE) concept has received attention in recent years as a way to address this challenge. As a relatively nascent construct, however, interested scholars and professionals continue to seek to define and operationalise MAE more effectively. Objective: The objective of this study is to provide a working definition of MAE. Methods: We used the Delphi technique to solicit informed views from expert evaluators working in Africa. We interviewed two additional experts to triangulate and test the validity of those findings. We also tested the Delphi derived definition of MAE through the analysis of six illustrative evaluation reports. Finally, we asked the same panel of experts to complete a survey aimed at clarifying next key steps to advance the construct. Results: The results of our efforts to elucidate a concise definition of MAE yielded the following definition: Evaluation that is conducted based on African Evaluation Association (AfrEA) standards, using localised methods or approaches with the aim of aligning all evaluations to the lifestyles and needs of affected African peoples whilst also promoting African values. Conclusion: We posit that this working definition, however tentative, has the potential to influence the practice, study, and teaching of evaluation in Africa.
Recent Experimental Progress in Nuclear Astrophysics

Abstract Experimental nuclear astrophysics aims at determining the nuclear properties and reaction rates that impact our understanding of past and ongoing processes in the Universe. Owing to the large number of unique sites, conditions, and environments in which nuclear physics plays an important, if not dominant role, a wide variety of complementary experimental approaches are required. This in turn requires utilization of multiple facilities throughout the world in order to obtain the nuclear data of interest. Some recent experimental approaches and results are reviewed with an eye towards future facilities and emerging frontiers of nuclear astrophysics.
Rhodamine 123 requires carrier-mediated influx for its activity as a P-glycoprotein substrate in Caco-2 cells.

Purpose. The purpose of this work was to elucidate transport pathways of the P-glycoprotein (P-gp) substrates rhodamine 123 (R123) and doxorubicin across Caco-2 cells. Methods. Experiments were designed to identify saturable and nonsaturable transport processes and transport barriers for R123 and doxorubicin transport across Caco-2 cells. Confocal laser scanning microscopy (CLSM) imaged R123 transport under normal conditions and in the presence of the P-gp inhibitor, GW918 (used to abolish P-gp-mediated efflux activity). Results. R123 secretory P app (P app,BA) showed concentration dependence, whereas R123 absorptive P app (P app,AB) did not. Inhibition of P-gp efflux revealed that P-gp-mediated efflux had no effect on R123 or doxorubicin P app,AB, but enhanced R123 and doxorubicin P app,BA. In calcium-free medium, R123 P app,AB increased 15-fold, indicating intercellular junctions are a barrier to R123 absorption. CLSM of R123 fluorescence during absorptive transport under normal conditions and in the presence of GW918 was identical, and was limited to paracellular space, confirming that P-gp is not a barrier to R123 absorption. CLSM revealed that R123 fluorescence during secretory transport under normal conditions and in the presence of GW918 was localized intracellularly and in paracellular space. R123 and doxorubicin uptake across Caco-2 cells basolateral membrane was saturable. Conclusions. R123 absorptive transport occurs primarily by paracellular route, whereas R123 secretory transport involves influx across BL membrane mediated solely by a saturable process followed by apically directed efflux via P-gp. Doxorubicin utilizes similar transport pathways to cross Caco-2 cells.
Determining serpin conformational distributions with single molecule fluorescence.

Conformational plasticity is key to inhibitory serpin function, and this plasticity gives serpins relatively easy access to alternative, dysfunctional conformations. Thus, a given serpin population may contain both functional and dysfunctional proteins. Single molecule fluorescence (SMF), with its ability to interrogate one fluorescently labeled protein at a time, is a powerful method for elucidating conformational distributions and monitoring how these distributions change over time. SMF and related methods have been particularly valuable for characterizing serpin polymerization. Fluorescence correlation spectroscopy experiments have revealed a second lag phase during in vitro α(1)-antitrypsin polymerization associated with the formation of smaller oligomers that then condense to form longer polymers [Purkayastha, P., Klemke, J. W., Lavender, S., Oyola, R., Cooperman, B. S., and Gai, F. (2005). Alpha 1-antitrypsin polymerization: A fluorescence correlation spectroscopic study. Biochemistry44, 2642-2649.]. SMF studies of in vitro neuroserpin polymerization have confirmed that a monomeric intermediate is required for polymer formation while providing a test of proposed polymerization mechanisms [Chiou, A., Hagglof, P., Orte, A., Chen, A. Y., Dunne, P. D., Belorgey, D., Karlsson-Li, S., Lomas, D., and Klenerman, D. (2009). Probing neuroserpin polymerization and interaction with amyloid-beta peptides using single molecule fluorescence. Biophys. J.97, 2306-2315.]. SMF has also been used to monitor protease-serpin interactions. Single pair Forster resonance energy transfer studies of covalent protease-serpin complexes suggest that the extent of protease structural disruption in the complex is protease dependent [Liu, L., Mushero, N., Hedstrom, L., and Gershenson, A. (2006). Conformational distributions of protease-serpin complexes: A partially translocated complex. Biochemistry45, 10865-10872.]. SMF techniques are still evolving and the combination of SMF with encapsulation methods has the potential to provide more detailed information on the conformational changes associated with serpin polymerization, protease-serpin complex formation, and serpin folding.
Evaluation of Organic Corn Varieties

According to the USDA National Organic Program, certified organic farmers must source organic seed (seed from organically raised crops). The organic seed industry is currently growing in Iowa and the Midwest, and with this growth, organic growers are looking for university-based recommendations on organic varieties to use in Iowa. The Organic Agriculture Program at Iowa State University has been using organic seed at the Southeast Research Farm for 17 years with excellent results.
Rich Environments for Active Learning on the Web: Guidelines and Examples.

This paper provides guidelines for creating REALs (Rich Environments for Active Learning) on the World Wide Web and demonstrates how those guidelines have been applied in a variety of Web-based learning environment contexts. The paper is organized according to the following attributes of student-centered REALs: (1) promote intentional learning by encouraging the growth of student responsibility, initiative, decision making, and intentional learning, including support for transition to an online learning environment, setting goals, metacognitive awareness, and time management; (2) apply dynamic, generative learning activities that promote high level thinking processes (i.e., analysis, synthesis, problem solving, experimentation, creativity, and examination of topics from multiple perspectives) to help students integrate new and old knowledge and, thereby, create rich and complex knowledge structures, including creating and providing access to resources; (3) utilize authentic learning contexts to promote study and investigation, including contextualizing learning, making learning complex, increasing meaningfulness and realism of activities, and encouraging research; (4) encourage collaboration to cultivate an atmosphere supportive of knowledge building communities; and (5) reinforce reflection by embedding opportunities to reflect on the learning process as well as on the content acquired to promote both learning and metacognitive skill
Constraint-Driven Rank-Based Learning for Information Extraction

Most learning algorithms for undirected graphical models require complete inference over at least one instance before parameter updates can be made. SampleRank is a rank-based learning framework that alleviates this problem by updating the parameters during inference. Most semi-supervised learning algorithms also perform full inference on at least one instance before each parameter update. We extend SampleRank to semi-supervised learning in order to circumvent this computational bottleneck. Different approaches to incorporate unlabeled data and prior knowledge into this framework are explored. When evaluated on a standard information extraction dataset, our method significantly outperforms the supervised method, and matches results of a competing state-of-the-art semi-supervised learning approach.
Causas y consecuencias de la informalidad en el Perú

Partiendo de una definicion legal de informalidad, el presente trabajo estudia las causas de este fenomeno en general, concentrandose en particular en el analisis de la informalidad en el caso peruano. Primero ofrece una discusion de la definicion de informalidad y de las mediciones de esta, senalando ademas las razones por las cuales la informalidad generalizada debiera ser motivo de gran preocupacion. Luego analiza los determinantes principales de la informalidad y plantea que esta no tiene una causa unica, sino que es producto de la combinacion de servicios publicos deficientes, de un regimen normativo opresivo y de la debil capacidad de supervision y ejecucion del estado. Dicha combinacion resulta especialmente explosiva cuando el pais se caracteriza por tener bajos niveles educativos, fuertes presiones demograficas y estructuras productivas primarias. Finalmente, utilizando un analisis de regresion transversal entre paises, se evalua la relevancia empirica de cada uno de los determinantes de la informalidad, aplicando luego las relaciones estimadas al caso peruano para evaluar la relevancia que tendria cada uno de los mecanismos propuestos en cada pais especifico. Clasificacion JEL: K20, K30, H11, O17, O40.
Radial Distribution of Atomic and Molecular Gas in Disk Galaxies

The observed radial surface mass density distributions of both atomic and molecular gas in 15 nearby spiral galaxies are analyzed. They are found to be consistent with a disk evolution model in which molecular cloud formation and star formation follow prescriptions similar to that discussed by Young (1987). Based on these and the assumption of “local condition determination”, we propose a scaling law to describe large-scale gas distribution in disk galaxies of differing mass and size.
Direct Numerical Simulation and Simple Closure Theory for a Chemical Reaction in Homogeneous Turbulence

The direct numerical simulation of turbulent flows serves as a useful test of simple closure theories, since one can examine the dynamics of the concentration and veloCity fields in more detail than in laboratory experiments and learn how the interaction of turbulent motion and molecular diffusion affects the overall reaction rate. A brief review of the most popular methods available for full turbulence simulations is presented, and a demonstration of the usefulness of direct numerical simulation is given for simple single-point closure theories (viz., those of Toor and of Patterson) applied to the irreversible, second-order chemical reaction of initially unmixed reactants.
Using Reasonable Royalties to Value Patented Technology

In the last several years, commentators have expressed serious concerns with the state of the law governing awards of reasonable royalties as damages in patent infringement cases. Given these concerns, the proper assessment of royalties has been a recent, frequent topic for debate among economists and legal scholars. At the same time, all three branches of the federal government have studied ways to improve the law governing reasonable royalties. In this Article, I reframe the ongoing debate by identifying and exploring two basic paradigms for calculating reasonable royalties: valuing patent rights and valuing patented technology. The traditional paradigm, valuing patent rights, reflects a tort law make-whole conception of compensatory damages. Notably, however, the alternative paradigm, valuing patented technology, in various respects explains the course of the common law governing the method for calculating reasonable royalties, comports with the public policies identified by courts as guiding the award of reasonable royalties, and, moreover, if fully adopted may have significant benefits. I therefore consider several reforms that would tie the law governing reasonable royalty determinations even closer to the value of patented technology, and I highlight several open questions related to full adoption of this alternative paradigm.
A wireless ad hoc protocols comparison study: DSR, AODV and IWAR

Wireless ad hoc networks are relatively new and are gaining ground in research due to promises they offer. Wireless ad hoc networks do not require predefined configuration and have no fixed infrastructure. They are self-organizing and self-configuring networks. Several protocols have been developed that vary in the performance and complexity. Dynamic Source Routing (DSR) is a well-known pure on-demand protocol. It is a simple protocol and it was designed to have low overhead. But it does not select the optimal routes all the times. Ad Hoc On-Demand Distance-Vector (AODV) protocol is a wireless ad hoc protocol that makes its routing decision based on the distance vector. The Intelligent Wireless Ad hoc Routing (IWAR) is newly introduced protocol that it is also dynamic on-demand protocol. It implements more complex algorithm to select optimal routes and provide load balancing. This paper describes the DSR and AODV protocols, presents the design of the IWAR protocol, and compares the complexity, optimality, overhead traffic and fault tolerance of these protocols.
Myoglobin as a model system for designing heme protein based blood substitutes

The ligand binding properties and resistances to denaturation of >300 different site-directed mutants of sperm whale, pig, and human myoglobin have been examined over the past 15 years. This library of recombinant proteins has been used to derive chemical mechanisms for ligand binding and to examine the factors governing holo- and apoglobin stability. We have also examined the effects of mutagenesis on the dioxygenation of NO by MbO(2) to form NO(3)(-) and metMb. This reaction rapidly detoxifies NO and is a key physiological function of both myoglobins and hemoglobins. The mechanisms derived for O(2) binding and NO dioxygenation have been used to design safer, more efficient, and more stable heme protein-prototypes for use as O(2) delivery pharmaceuticals in transfusion therapy (i.e. blood substitutes). An interactive database is being developed (http://olsonnt1.bioc.rice.edu/web/myoglobinhome.asp) to allow rapid access to the ligand binding parameters, stability properties, and crystal structures of the entire set of recombinant myoglobins. The long-range goal is to use this library for developing general protein engineering principles and for designing individual heme proteins for specific pharmacological and industrial uses.
Suppression of Thermal Postbuckling and Nonlinear Panel Flutter Motions Using Piezoelectric Actuators

Active output feedback control of large amplitude nonlinear panel flutter at supersonic speeds with and without temperature effect is presented. A coupled structural-electrical modal formulation using finite elements is applied. Suppression of three types of panel response is studied: limit cycle oscillations, static thermal postbuckling, and chaotic motion. The controller, composed of a linear quadratic regulator and an extended Kalman filter, is developed and investigated. The extended Kalman filter considers the nonlinear state-space matrix and has a gain sequence evaluated online. The norms of the feedback control gain are employed for the optimal placement of piezoelectric actuators, and the norms of the Kalman filter estimation gain are used to validate the best locations for the sensors. A symmetric laminated composite plate at supersonic speeds with or without the influence of elevated temperatures is investigated. Two types of piezoelectric materials, PZT5A and macrofiber composite actuators, embedded in the composite panel are considered to suppress the nonlinear panel flutter. Simulation results show that the linear quadratic regulator/Kalman filter controller can suppress all three types of panel response with or without thermal effects.
Thine own self: True self-concept accessibility and meaning in life.

A number of philosophical and psychological theories suggest the true self is an important contributor to well-being. The present research examined whether the cognitive accessibility of the true self-concept would predict the experience of meaning in life. To ensure that any observed effects were due to the true self-concept rather than to the self-concept more generally, the authors used actual self-concept accessibility as a control variable in all studies. True and actual self-concepts were defined as including those traits that are enacted around close others vs. most others (Studies 1 through 3) or as traits that refer to "who you really are" vs. "who you are during most of your activities" (Studies 4 and 5), respectively. Studies 1, 2, and 4 showed that individual differences in true self-concept accessibility, but not differences in actual self-concept accessibility, predicted meaning in life. Studies 3 and 5 showed that priming traits related to the true self-concept enhanced perceptions of meaning in life. Implications for the study of the true self-concept and authenticity are discussed.
An assay to measure the affinity of proteins for microtubules by quantitative fluorescent microscopy

We report a fluorescence-based assay for measuring the affinity of microtubule binding proteins for microtubules. The affinity of any fluorescently tagged protein for taxol-stabilized microtubules can be measured with this assay. We describe the assay and provide a detailed protocol. Using this assay, we found that the affinity of the Dam1 complex for microtubules is decreased by the presence of free unpolymerized tubulin and is sensitive to the salt concentration in the binding buffer. These effects may account for the previous differences in binding affinities reported.
DETECTION OF ANTIBODIES REACTIVE WITH EHRLICHIA CHAFFEENSIS IN THE RACCOON

Antibodies reactive with Ehrlichia chaffeensis were detected in raccoon (Procyon lotor) serum samples by using an indirect immunofluorescence assay. Samples from 411 raccoons trapped in the southeastern United States from 1977 to 1999 were tested. Serologically reactive samples with reciprocal titers of ≥16 were detected from 83 raccoons (20%) from 13 of 16 counties in eight states, indicating that raccoons are commonly exposed to E. chaffeensis. Samples collected as early as 1977 were positive. A polymerase chain reaction assay specific for E. chaffeensis failed to detect the presence of ehrlichial DNA in serum samples from 20 representative seroreactive raccoons. Because of serologic cross-reactivity among antigens derived from different Ehrlichia spp., additional immunologic, molecular, or culture-based studies will be required to confirm E. chaffeensis infections of raccoons in the southeastern United States.
Contrôle génétique de la squelettogenèse

Les progres de la genetique ont permis d’etablir avec precision au cours de ces dix dernieres annees la succession des evenements moleculaires et cellulaires presidant a la mise en place du squelette. Dans l’embryon, les bourgeons squelettiques s’individualisent a partir de trois regions : le mesoderme de la plaque laterale, les somites et les cellules des cretes neurales. Cette specification des cellules mesenchymateuses est sous le controle de facteurs dits « organisateurs » FGF, BMP, ou Ihh dont l’alteration conduit a des troubles de la forme generale du squelette. Ces ebauches evoluent ensuite independamment, et suivent deux voies d’ossification tres distinctes : ossification dite membranaire, ou les cellules mesenchymateuses se differencient in situ en osteoblastes ; ossification endochondrale, ou une population centrale de chondrocytes se differencient et s’organisent en une plaque de croissance cartilagineuse, primordiale pour la croissance longitudinale des os. Chacun de ces processus d’ossification est tres etroitement controle par des facteurs de transcription (Sox-9, cbfa1), des facteurs de croissance et leurs recepteurs (FGFR3, PTHrP), chacun intervenant a une etape tres precise de la cascade moleculaire assurant la differenciation chondrocytaire et osteoblastique. L’alteration de la fonction de ces signaux, consequence de mutations souvent activatrices, entraine des anomalies du squelette correspondant a des maladies humaines.
THE MEASUREMENT OF SPATIAL CONTRAST SENSITIVITY IN CASES OF BLURRED VISION ASSOCIATED WITH CEREBRAL LESIONS

Thirty-five patients with known cerebral lesions complained of recently acquired blurred vision. None of them had evident oculomotor or pupillary abnormalities, and each had intact central fields and normal visual acuity by conventional standards. Examination of spatial contrast sensitivity was carried out with sinusoidal grating patterns, by determining the minimum contrast between alternate light and dark bars required to distinguish the pattern from a homogeneous field. This was done at each of several spatial frequencies which were established by varying the width of the bars and hence the coarseness of the pattern. The contrast sensitivities were plotted as "visuograms" which, by analogy to audiograms, record the sensitivities in comparison to normal standards. Of the 35 patients, most showed significant losses, amounting to greater than 50 per cent elevation of contrast thresholds. Eighteen showed high frequency losses; 11 had uniform reductions over the entire visible spatial frequency range and 6 had selective frequency losses in the intermediate frequency ranges. These defects in spatial contrast sensitivity, which were not predictable from standard acuity scores, indicate that the visual symptoms in our patients may have been caused by damage to frequency-selective neural elements in the central visual systems. The method may be used to advantage in clinical investigations as well as in physiological investigations of the functional pathways subserving central vision.
Modulation of pediatric brain tumor autophagy and chemosensitivity

Brain and spinal tumors are the second most common malignancies in childhood after leukemia, and they remain the leading cause of death from childhood cancer. Autophagy is a catabolic cellular process that is thought to regulate chemosensitivity, however its role in pediatric tumors is unknown. Here we present studies in pediatric medulloblastoma cell lines (DAOY, ONS76) and atypical teratoid/rhabdoid tumor cell lines (BT-16, BT-12) to test this role. Autophagy was inhibited using siRNA against autophagy-related genes ATG12 and ATG7 or pharmacologically induced or inhibited using rapamycin and chloroquine to test the effect of autophagy on chemosensitivity. Autophagic flux was measured using Western blot analysis of LC3-II and p62 and cell viability was determined using MTS assays and clonogenic growth. We found that when pediatric brain tumor cells under starvation stress, exposed to known autophagy inducers such as rapamycin, or treated with current chemotherapeutics (lomustine, cisplatin), all stimulate autophagy. Silencing ATG12 and ATG7 or exposure to a known autophagy inhibitor, chloroquine, could inhibit this autophagy increase; however, the effect of autophagy on tumor cell killing was small. These results may have clinical relevance in the future planning of therapeutic regimens for pediatric brain tumors.
Proteins Kinases: Chromatin-Associated Enzymes?

Protein kinases contribute to the regulation of gene expression by interacting with transcription factors that are recruited to the regulatory regions of genes. Previous studies investigated the role of protein kinases in transcription initiation. Here, we discuss new insights gleaned from recent work showing that kinases can also interact with chromatin throughout the entire transcribed region of target genes (Pokholok et al., 2006; Proft et al., 2006).
Slave Prices, the African Slave Trade, and Productivity in Eighteenth-Century South Carolina: A Reply

The comment by David Eltis, Frank Lewis, and David Richardson brings to the fore issues about productivity growth in slave-based economies, and about broader interpretations of those societies and their successor economies. Their assessment confirms that prices derived from probate inventories behaved like those derived from market transactions, suggesting that rich data available in probate inventories can be brought to bear on important issues in colonial economic history. We disagree, however, with their finding that slave productivity in the Lower South grew much more rapidly than we estimated. They maintain that our estimates of productivity growth are biased downward because the export price series we used to deflate the nominal slave prices rises too rapidly for two reasons.' First, they argue that the rice price we used for the period 17221731 is conceptually different from the price we used for the period after 1731. Second, they contend that Philadelphia rice prices, which were higher and rose more slowly than Charleston prices, would be a better measure of the prices received by rice producers. They also exaggerate the differences between their estimates and ours when they contend that "The lack of productivity growth is especially puzzling given our estimate that during the period 1722 to 1775 slave prices in South Carolina were increasing somewhat faster than in the Caribbean."2 Our finding of "the lack of productivity growth" to which they refer is for the entire period 1722 to 1800, not 1722 to 1775, a period when slave prices were rising rapidly. Their focus on the period down to the end of the century obscures an important point, namely that we also find slave productivity growth in the period before 1775. They alluded to this in a footnote, but it needs greater stress. We estimated that real slave prices rose between 1722-1724 and 1770-1774 at an annual rate of 0.8 percent, well above the 0.4 rate they report for the Caribbean. Although our estimated increase is well below the 1.65 percent annual rate of growth that they estimate for the Lower
Subunit composition of human blood group MN antigens

Abstract The mol. wt of highly purified blood group MN antigens from human erythrocytes depends on the method of isolation and the nature of the solvent. The mol. wt of the active repeating subunits isolated by gentle and non-dissociating procedures (pH 6·–7·2 and 23–25°C) was found to be 50,000 and 53,000 when dissolved in 9 M formamide and 5% ethanol-water, respectively. Isolation at pH > 7·8 or > 50°C yielded preparations with a mol. wt of 30,000; these latter, smaller, only weakly active molecules may be degradation or disruption products of strong bound dimers. Comparison of ‘native’ with artificially acetylated antigen indicate that both hydrogen and hydrophobic bonding contribute to stabilize the aggregate.
Coordination of the cell cycle is an important determinant of the syndrome of acute renal failure.

Recovery from injury is usually accompanied by cell replication, in which new cells replace those irreparably damaged. After acute renal failure, normally quiescent kidney cells enter the cell cycl...
Industrial Cowboys: Miller & Lux and the Transformation of the Far West, 1850-1920

Few industrial enterprises left a more enduring imprint on the American West than Miller & Lux, a vast meatpacking conglomerate started by two San Francisco butchers in 1858. "Industrial Cowboys" examines how Henry Miller and Charles Lux, two German immigrants, consolidated the West's most extensive land and water rights, swayed legislatures and courts, monopolized western beef markets, and imposed their corporate will on California's natural environment. Told with clarity and originality, this story uses one fascinating case study to illuminate the industrial development and environmental transformation of the American West during the late nineteenth and early twentieth centuries. The process by which two neighborhood butchers turned themselves into landed industrialists depended to an extraordinary degree on the acquisition, manipulation, and exploitation of natural resources.David Igler examines the broader impact that industrialism - as exemplified by Miller & Lux - had on landscapes and waterscapes, and on human as well as plant and animal life in the West. He also provides a rich discussion of the social relations engineered by Miller & Lux, from the dispossession of Californio rancheros to the ethnic segmentation of the firm's massive labor force. The book also covers such topics as land acquisition and reclamation, water politics, San Francisco's unique business environment, and the city's relation to its surrounding hinterlands. Above all, Igler highlights essential issues that resonate for us today: who holds the right and who has the power to engineer the landscape for market production?
Separation of center of mass in homogeneous magnetic fields

We show that a system of particles in a homogeneous magnetic field, with translation invariant interaction, has a constant of motion analogous to the total momentum when B = 0. Next, we consider the separation of the center of mass. When the total charge of the system is zero, the situation is similar to (but more complicated than) the B = 0 case. When the total charge is nonzero, the analysis is quite different. The two-body problem is worked out in some detail and we also state and prove a version of the HVZ theorem in homogeneous magnetic field.
Using Interstation Amplitude Correction Factors to Predict Regional Phase Amplitudes

Abstract Developing regional discriminants at any given seismic station requires a ground truth database of waveforms from both earthquakes and explosions. Recently installed stations used for seismic monitoring have no single-charge explosions on which to base discriminants. We have developed a procedure to map regional seismic amplitudes from surrogate stations, which have a long recording history, to newly installed operational stations. This procedure uses an interstation amplitude correction factor (IACF), computed using a set of commonly recorded calibration earthquakes between the surrogate and operational station pair, to predict seismic amplitudes at the new station using the IACF and historical explosion amplitudes from the surrogate station. We tested the method using an earthquake aftershock sequence in Pakistan recorded at the Kyrgyzstan broadband seismic network. The aftershocks had a range of depths and were clustered in a linear trend defining the fault rupture plane of the mainshock. We computed IACFs for all possible station combinations at KNET (45 combinations) for all events and then computed a mean IACF value for each station pair. Using the mean IACF values, we calculated predicted phase amplitudes at each station and compared the predictions to the actual values. The observed-predicted relationship performed well ( r 2 -values>0.8) for all phases and frequency bands. At frequencies above 6 Hz, the observed-predicted relationship showed more scatter, a trend not due to interstation distance, source depth, or spatial location of the calibration earthquakes. We were able to reduce scatter in the observed-predicted relationship by applying path corrections to the data, suggesting that sensitivities in differing paths between certain surrogate-operational station combinations do play a role in the effectiveness of the method. We used this methodology to predict explosion values at the Lop Nor nuclear test site in China using a suite of nearby calibration earthquakes to calculate IACF values. The results indicate good correlation between the observed and predicted amplitudes, suggesting that the method can be used to simulate explosion characteristics at stations that have never recorded explosions. Comparing the IACF values from the calibration dataset near Lop Nor to those calculated for the earthquakes in Pakistan, we see some similarity for certain station combinations; however, on the whole, there are differences that suggest that IACFs have a spatial variance and must be tuned to the region and path of interest for the method to be successful.
SPATIAL SEGREGATION OF CO2 FIXATION IN TRICHODESMIUM SPP.: LINKAGE TO N2 FIXATION POTENTIAL1

The aggregate-forming, nonheterocystous, filamentous blue-green alga (cyanobacteria) Trichodesmium spp. is a widespread and important planktonic N2 fixer and primary producer in tropical and subtropical oceans. It is unique among nonheterocystous genera because it conducts N2 and CO2 fixation (O2 evolution) simultaneously; a notable achievement, because O2 is a potent inhibitor of N2 fixation. Spatial and temporal CO2 fixation patterns were examined in trichomes and aggregates from natural and cultured populations, utilizing microautoradiographic detection of 14CO2 incorporation. Parallel N2 fixation (acetylene reduction) measurements were also made. Diel N2 and CO2 fixation patterns were similar, with co-optimization of both processes near midday. Microautoradiographs revealed several trichome-level 14CO2 incorporation patterns: 1)uniform, heavy labeling, 2)uniform, light labeling, 3) heavier labeling in distal as opposed, to proximal regions, and 4) virtually no labeling throughout. Similar patterns were observed in natural and cultured populations. Given previous immunochemical findings that N2 fixation potential is widespread in Trichodesmium spp. trichomes and aggregates, current results suggest a high degree of individuality, and possibly a “division of labor” in terms of CO2 fixation, among trichomes comprising active N2-fixing aggregates. Segregation of photosynthesis within and among trichomes facilitates simultaneous N2 and CO2 fixation in Trichodesmium spp. trichomes and aggregates.
Co-operative oscillations of bubbles

A closed cryogenic storage tank in space may contain several bubbles. It is shown that these bubbles can oscillate in volume with n-1 resonant frequencies for n bubbles. The resonances can be excited by a sudden change in pressure, such as withdrawing fluid or venting, or by motion of the vehicle. In situations in which the ac accelerations dominate, such as in large space structures, the potential for harmful coupling of these oscillations to the spacecraft structure must be examined. Experimental data are presented which support the theoretical predictions.
Quantitative Analysis of Actin Turnover in Listeria Comet Tails: Evidence for Catastrophic Filament Turnover

Rapid assembly and disassembly (turnover) of actin filaments in cytoplasm drives cell motility and shape remodeling. While many biochemical processes that facilitate filament turnover are understood in isolation, it remains unclear how they work together to promote filament turnover in cells. Here, we studied cellular mechanisms of actin filament turnover by combining quantitative microscopy with mathematical modeling. Using live cell imaging, we found that actin polymer mass decay in Listeria comet tails is very well fit by a simple exponential. By analyzing candidate filament turnover pathways using stochastic modeling, we found that exponential polymer mass decay is consistent with either slow treadmilling, slow Arp2/3-dissociation, or catastrophic bursts of disassembly, but is inconsistent with acceleration of filament turnover by severing. Imaging of single filaments in Xenopus egg extract provided evidence that disassembly by bursting dominates isolated filament turnover in a cytoplasmic context. Taken together, our results point to a pathway where filaments grow transiently from barbed ends, rapidly terminate growth to enter a long-lived stable state, and then undergo a catastrophic burst of disassembly. By keeping filament lengths largely constant over time, such catastrophic filament turnover may enable cellular actin assemblies to maintain their mechanical integrity as they are turning over.
MONTE CARLO VARIANCE REDUCTION WITH DETERMINISTIC IMPORTANCE FUNCTIONS

Abstract Recent trends in Monte Carlo code development have reflected a recognition of the benefits of using deterministic importance functions for Monte Carlo variance reduction. This paper offers a review of the use of deterministic importance functions for variance reduction of Monte Carlo simulations. Adjoint methodology and the concept of “importance” are presented, along with an explanation of their use for variance reduction. Relevant works from a number of different researchers are briefly reviewed. The authors' CADIS methodology for calculating consistent source biasing and weight window parameters based on deterministic importance functions is presented. Efforts to automate the generation and use of deterministic importance functions are briefly described, including an overview of the A3MCNP code. Finally, aspects of interest, including computational benefits, associated with using deterministic importance functions for Monte Carlo simulation of real-world problems are demonstrated.
The effects of reactant starvation and mass transfer in the rate measurement of fluid–solid reactions with small equilibrium constants

Abstract The purpose of this article is to analyze critically and quantitatively the effect of fluid reactant supply rates and mass transfer on the measurement of the rates of fluid–solid reactions, particularly those with small equilibrium constants. It is shown through a mathematical analysis that the measurement of the intrinsic kinetics of a reaction with a small equilibrium constant (a positive standard free energy of reaction) requires much larger rates of fluid reactant supply and mass transfer rates than that of a reaction with a large equilibrium constant. The overall reaction rate of the former also tends to be slow. Furthermore, the apparent activation energy of such a reaction approaches the standard enthalpy of reaction ( Δ H 0 ) , rather than the true activation energy of the chemical reaction.
Adsorption of cellulase components by leaf litter

The competitive adsorption of Trichoderma viride cellulase components to leaf litter was investigated to further elucidate the role of extracellular enzymes as mediators of decomposition processes. Litter analogs were prepared by acid-detergent digestion of senescent Pinus strobus (white pine), Quercus prinus (chestnut oak) and Cornus florida (flowering dogwood) leaves. Enzymatic cellulose digestion was used to produce litter analogs of higher lignin content. The white pine litter analogs had a high affinity for exocellulase and β-glucosidase. Chestnut oak litter preferentially bound endocellulase components and flowering dogwood litter displayed intermediate trends. Natural mixed-deciduous and white pine litters and humus had less capacity for immobilizing cellulase components. The adsorption data are consistent with available information on the binding of cellulase components to purified cellulose and with information on the cellulase activity patterns of decomposing leaf litter.
The Fundamental Organization of Cardiac Mitochondria as a Network of Coupled Oscillators

Mitochondria can behave as individual oscillators whose dynamics may obey collective, network properties. We have shown that cardiomyocytes exhibit high-amplitude, self-sustained, and synchronous oscillations of bioenergetic parameters when the mitochondrial network is stressed to a critical state. Computational studies suggested that additional low-amplitude, high-frequency oscillations were also possible. Herein, employing power spectral analysis, we show that the temporal behavior of mitochondrial membrane potential (ΔΨm) in cardiomyocytes under physiological conditions is oscillatory and characterized by a broad frequency distribution that obeys a homogeneous power law (1/fβ) with a spectral exponent, β = 1.74. Additionally, relative dispersional analysis shows that mitochondrial oscillatory dynamics exhibits long-term memory, characterized by an inverse power law that scales with a fractal dimension (Df) of 1.008, distinct from random behavior (Df = 1.5), over at least three orders of magnitude. Analysis of a computational model of the mitochondrial oscillator suggests that the mechanistic origin of the power law behavior is based on the inverse dependence of amplitude versus frequency of oscillation related to the balance between reactive oxygen species production and scavenging. The results demonstrate that cardiac mitochondria behave as a network of coupled oscillators under both physiological and pathophysiological conditions.