cssi/SciSciGPT-SciSciNet huggingface dataset:
Geometric Aspects of the Covariance Partial Realization Problem

In this paper, both Euclidean geometric and non-Euclidean geometric descriptions for the regions of the solution set to the covariance partial realization problem are discussed. In particular, it is shown that all the solution functions are located inside a Euclidean disk - the Weyl disk, and a non-Euclidean disk - the Apollonian disk. The radius of each disk depends on the norm of the parameterizing Schur functions. Moreover, it is pointed out that the well known maximum entropy solution is exactly the hyperbolic center of the Apollonian disk; while, the associated power spectral density function is the geometric mean center of the real region where the Weyl disk is projected to along the imaginary axis. Sensitivity analysis of the Weyl disk radius and Apollonian disk center due to the perturbation of the given finite covariance data is presented.
X-ray densitometry of shock-excited Richtmyer-Meshkov instability at an air-xenon interface

Experiments were performed in a vertical, square shock tube to study the development of the Richtmyer-Meshkov instability excited by the interaction of a shock wave with an air/xenon interface. The objective is to measure the mixing that occurs at the interface due to the instability. New flow visualization and densitometry techniques based on X-ray absorption by the xenon have been developed. Continuous interfaces between the gases are prepared by initially separating the gases with a metal plate which is retracted out of the tube prior to the release of the shock wave. Depending on the time elapsed between the end of plate retraction and shock arrival, the interface can be either quasisinusoidally or randomly perturbed. An X-ray 50 ns long flash is projected through the flow and a 20 × 25 cm X-ray negative is exposed at each run. The negatives are digitized and mean xenon-density profiles across the interfaces are generated by image processing methods developed specially for this purpose. The amplitude of the perturbations, the thickness of the diffuse interfaces and the growth rates of these two quantities are measured from the density profiles.
Principles and Methods of Law and Economics: HOW TO PRICE UNCERTAINTY: FINANCE

Much of law is about financial arrangements. This may be an understatement because all of private, and much of public, law rests on the idea that certain wrongs (torts, breaches, etc.) trigger financial compensation. Not all payments of a given amount are equal, however, because time and risk matter. This chapter explains how the value of a payment changes with time – what is called discounting or the time value of money – and how to adjust for the risk of future payments from businesses according to the Capital Asset Pricing Model . Legal analysis needs a sound understanding of these topics. The importance of financial knowledge is starkly visible in Meinhard v. Salmon because it involves an overtly financial relation. Salmon received a lucrative offer from Gerry, a business acquaintance. The offer could have expanded Salmon's business. Unbeknownst to Gerry, Salmon's business, which was the reason for their acquaintance, had a secret partner, Meinhard. If Gerry knew that Salmon operated in two capacities, as an individual and as a member of a partnership, then Gerry may have specified which of the two he selected as the recipient of his offer. Meinhard, the invisible partner, claimed the offer should be treated as made to the partnership. The case involved numerous payments at different points in time, illustrating the importance of discounting and valuation. The case is also an excellent example of the practical importance of valuation.
Innocents Beware: On Religion Clause Jurisprudence and the Negligent Retention or Hiring of Clergy

Over the past several decades, state and federal courts have been forced to consider the circumstances, if any, under which a religious organization might be held civilly liable for the tortious conduct of clergy in their employ. There is a clear divide separating the courts — some refuse to impose liability on the employers citing First Amendment concerns whereas others see no First Amendment impediment to the imposition of liability on religious institutions as long as the courts are applying secular law and are not delving into religious matters. This article discusses the developing jurisprudence regarding negligent hiring and retention of clergy by religious institutions, analyzing both the clear split within the lower courts and how Hosanna-Tabor Evangelical Lutheran Church and School v. Equal Employment Opportunity Commission might affect the developing case law. The article concludes that the Court must both clarify existing law at its earliest opportunity and forestall some of the broad interpretations that would otherwise result from some of the unfortunate language in Hosanna-Tabor.
Aristotle's Theory of Language and Meaning

Part I. Language and knowledge: 1. Meaning 2. Truth and necessary truth 3. Language of science 4. Three types of science Part II. Definition and Essence 5. Definition and ontology 6. Logos as Substance Part III. Cognition and Meaning 7. Phantasia and representation 8. Abstract thought and meaning 9. Conclusions Indexes.
Evaluating the activity of the RNA polymerase inhibitor myxopyronin B against Staphylococcus aureus

Myxopyronin B (MyxB) binds to the switch region of RNA polymerase (RNAP) and inhibits transcriptional initiation. To evaluate the potential development of MyxB as a novel class of antibiotic, we characterized the antimicrobial activity of MyxB against Staphylococcus aureus. Spontaneous MyxB resistance in S. aureus occurred at a frequency of 8 × 10−8, similar to that of rifampin. The MyxB-resistant mutants were found to be altered in single amino acid residues in the RNAP subunits that form the MyxB-binding site. In the presence of human serum albumin, the MyxB minimum inhibitory concentration against S. aureus increased drastically (≥128-fold) and 99.5% of MyxB was protein bound. Because of the high serum protein binding and resistance rate, we conclude that MyxB is not a viable starting point for antibiotic development.
Prospective Evaluation of Ventriculostomy Infections.

Introduction: Hospital-acquired infections associated with external drainage of ventricular cerebrospinal fluid (CSF) are a significant source of concern for the patients and the provider team alike. Traditional rates of ventriculostomy infection range from 10-17% in a time-dependent fashion. Changing physician and nursing practices fueled this concern over infections. Objective: We sought to prospectively identify the risk factors associated with ventriculostomy infections as part of a quality assurance project. Methods: One hundred consecutive patients were evaluated and data were collected on 91. The primary indications for ventriculostomy were subarachnoid hemorrhage (46%), intracerebral hemorrhage (24%), and trauma (22%). Variables prospectively evaluated included pre-incision antibiotics, sterile technique bundling, setting of placement (operating room versus intensive care unit), experience of operator (attending, resident, or physician assistant), catheter type (antibiotic impregnated or not), use of a post-insertion dressing, and in-dwell time of the catheter. Results: There was only one infection in 91 patients (1.1%). This infection occurred in a patient without an antibiotic-impregnated catheter that was inserted by a resident physician. Compliance with pre-insertion antibiotics was very high, but most other variables had modest deviations in compliance. Conclusion: Infection rate related to external ventricular drainage is very low. Our data suggest that non-antibiotic impregnated catheters may be associated with infection, but that other variables thought to be critical may be of less value.
Measuring the Effectiveness of Different Corporate Governance Systems: Toward a More Scientific Approach

Ever since publication of Berle and Means' 1932 classic, "The Modern Corporation and Private Property," many have believed that there are significant problems with the American system of corporate governance. In particular, the separation of ownership and control identified with the American publicly held corporation is said to produce an organizational structure in which shareholders face collective action problems that make it impossible for them effectively to monitor and discipline the management of the firms in which they have invested. Professional managers are said to be virtually unaccountable to shareholders. Recently scholars have suggested that institutional investors are the group most likely to resolve America's corporate governance problem. Other commentators, however, have questioned the merits of having institutional investors take a more active role in corporate governance. Roberta Romano, for example, has shown that public pension funds face political constraints that are likely to prevent them from serving very effectively as monitors of corporate mangers. As for corporate pension funds and financial institutions, it has long been recognized that these institutions face conflicts of interest that prevent them from serving as effective representatives of the interest of outside shareholders. Jack Coffee has pointed out that the kind of long-term, "relational" investing required to make institutional investors a voice in corporate governance may be too costly to such investors because it will require them to sacrifice liquidity. Jill Fisch has argues that institutional investors may not find it rational to engage in relational investing unless they are given special benefits such as special information about control.
A usability study of internet privacy policies for state and commercial websites

Increasingly, consumers are getting online to take advantage of the unprecedented convenience of accessing goods and services. However, there are still web barriers preventing some consumers from exploiting this opportunity. One of the main barriers is concern over the privacy of personal information when a consumer visits a website. To address this concern, the Federal Trade Commission has developed a set of Fair Information Practices Principles. Many web vendors use these principles to develop online privacy policies as a means of promoting consumer trust. This study assesses the contents and reading complexity of privacy policies posted by 40 state government and commercial sites. The principles set forth by the Federal Trade Commission are used as a basis for assessing the content of these policies. The findings show that for each of the principles, privacy policies lack content that could promote consumer trust. It was also found that the reading complexity of these policies posed a significant barrier because personal information was not well-defined, technical jargon lacked explanation, sentences were complex, and codes and regulations were quoted as part of information disclosure.
Molecular mechanisms for simvastatin-mediated enhancement of synaptic plasticity

Simvastatin (SV), a competitive inhibitor of 3-hydroxy-3-methylglutaryl CoA reductase and a widely prescribed treatment for hypercholesterolemia, exerts numerous positive pleiotropic effects that are thought to occur independent of its cholesterol-lowering properties. In previously published work, we have shown that chronic SV treatment rescues cognitive function in a transgenic mouse model of Alzheimer’s Disease, and enhances learning and memory in non-transgenic mice without affecting total brain cholesterol and amyloid-beta levels. More recently, we demonstrated the ability of SV to enhance long-term potentiation (LTP) in the CA1 region of the hippocampus in slices from wild type C57BL/6 mice via a mechanism dependent upon phosphatidylinositol 3-kinase (PI3-K)/Akt activation during LTP induction. The present study was conducted to better understand the molecular mechanisms underlying SV-induced enhancement of LTP. Specifically, it was found that inhibiting production of isoprenoid intermediates in the biosynthetic pathway for cholesterol triggers the downstream events leading to enhanced LTP. Interestingly, two major isoprenoid intermediates exhibit differential effects. Replenishment of farnesyl pyrophosphate, but not geranylgeranyl pyrophosphate, abolished the LTP-enhancing ability of SV. Parallel to this finding, inhibiting farnesylation, but not geranylgeranylation replicated the enhancement of LTP caused by SV. Finally, inhibiting farnesylation promotes the activation of Akt during the induction phase. Together, these results suggest that SV enhances LTP in CA1 by modulating isoprenylation-dependent molecular pathways downstream of farnesyl transferase. These findings will aid in the identification of novel therapeutic targets that modulate synaptic and cognitive function. Grant support: Supported by grants of NIH AG031846 and an Anonymous Philanthropic Foundation to L Li. Acknowledgements This study was supported by Program for Excellent talent in University of Chongqing (2010).
The Disconnect of Poor‐Urban Education: Equal Access and a Pedagogy of Risk Taking

In an age of educational accountability and school competition, the gap between current poor-urban school performance and standards of excellence remains glaringly obvious. As poor-urban schools scramble to “close the gap,” many abandon sound pedagogy, becoming entrenched in a curriculum where basic-skills worksheets are the primary method of educational delivery resulting in a disconnect between pedagogically sound educational practices and those very students that need it most. Two literacy pilot programs are discussed as applied examples showing that good teaching and accountability result in increases in early reading skills as measured by the Woodcock Reading Mastery Test-Revised (R.W. Woodcock, 1998). Results are discussed in light of raised teacher expectations, assessment-driven small class grouping, and active student learning. In a supportive, challenging environment, the basis for a pedagogy of risk taking emerges. © 2005 Wiley Periodicals, Inc. Psychol Schs 42: 855–863, 2005.
A review of cognitive teaching models

The purpose of this article is to review from an instructional-design (ID) perspective nine teaching programs developed by cognitive psychologists over the last ten years. Among these models, Collins' cognitive apprenticeship model has the most explicit prescriptions for instructional design. In the article, the cognitive apprenticeship model is analyzed, then components of the model are used as an organizing framework for understanding the remaining models. Differences in approach are noted between traditional ID prescriptions and the cognitive teaching models. Surprisingly, no design strategies were found to be common to all the model programs. Key differences among programs included: (1) problem solving versus skill orientation, (2) detailed versus broad cognitive task analysis, (3) learner versus system control, and (4) error-restricted versus error-driven instruction. The article concludes with an argument for the utility of continuing dialogue between cognitive psychologists and instructional designers.
Phorbol ester and Epstein-Barr virus dependent transformation of normal primary human skin epithelial cells.

Substantial evidence has implicated Epstein–Barr virus (EBV) in the aetiology of two human neoplasms, nasopharyngeal carcinoma (NPC) and Burkitt's lymphoma1,2. This is supported by the presence of high antibody titres to EBV early antigen and virus capsid antigen3,4, as well as antibody to two viral-associated enzymes, DNase and DNA polymerase5,6. Patients with NPC, particularly the undifferentiated form, are commonly found to have EBV DNA in the tumour2. Ito and others7–10 have presented strong epidemio-logical evidence that phorbol esters are related to the unusual geographic distribution of NPC in southeastern regions of China. There appears to be a close link between the widespread EBV infection of the Asian population and the distinct regional distribution in China of plants that produce diterpene ester11. Naturally occurring phorbol esters are produced by plants of the Euphor-biaceae and Thymelaeaceae, which are used as traditional herbal medicines12. Although it has been established that EBV can infect epithelial cells isolated from NPC as well as certain normal epithelial cells13–15, there has been no in vitro evidence that EBV induces neoplastic transformation in normal human epithelial cells with or without exposure to phorbol esters. We report here evidence that transformation of normal human epithelial cells results from exposure to infectious EBV and that transformation is dependent on the presence of phorbol esters.
State feedback for non-linear control systems

Abstract A theory of static state feedback for non-linear discrete-time systems is developed. The theory applies to non-linear systems possessing a recursive representation of the form x k+1 =ƒ(x k , uk ), where ƒ is a continuous function, and it deals with the construction of continuous state feedback functions that internally stabilize a given system. The theory yields an explicit method for the computation of stabilizing feedback functions, and several examples of the computation of such functions are provided.
Control of high-resolution Electrohydrodynamic jet printing

This paper discusses a run-to-run iterative learning control (ILC) algorithm for Electrohydrodynamic jet (E-jet) printing. E-jet printing is a nano-manufacturing process that uses electric field induced fluid jet printing through nano-scale nozzles for achieving better control and resolution than traditional jet-printing processes. The printing process is controlled by changing the voltage potential between the nozzle and the substrate. However, it is difficult to maintain constant operating conditions such as stand-off height during a run of the printing process. The change in operating conditions results in fluctuating jet frequency. For stabilizing the jetting frequency across a single run, we propose a proportional ILC algorithm. We determine the jetting frequency by recording the electric current pulses when ink droplets are released from the nozzle. The frequency profile obtained from current measurements is then used to shape the voltage profile across a run to compensate for changing operating conditions. Experimental results are presented to validate the proposed control method.
Five years later: how California community members acted on transformative learning achieved in a participatory planning process

This article examines whether participation in a collaborative planning process leads to change in attitudes and behaviours for process participants. This case examines the five-year impact on stakeholders from a Californian participatory process. In this case (1) transformative learning occurred during the process; (2) learning was sustained over time; (3) few participants reported long-term changes in their professional practices and personal lives; and (4) the organisation that convened the process provided no support to participants to act on what they learned via their participation. The case demonstrates that, if planners expect participants to take action based on process learning, continuing support is necessary.
Physical structure, genetic content and expression of the alkBAC operon.

We cloned sequences of the alk (alkane utilization) operon of Pseudomonas and characterized them physically and genetically. These sequences were used to construct a DNA restriction map of the alkBAC region. We physically mapped alk:: Tn7 insertions and ΔalkBA deletions, and we were able to show complementation or marker rescue of alk point mutations by cloned DNA sequences. Our results confirmed the existence of an operon containing structural loci encoding activities for membrane alkane hydroxylase component (alkB), soluble alkane hydroxylase component (alkA) and membrane alcohol dehydrogenase (alkC). Physical mapping of alkC::Tn7 insertions and complementation of alkC point mutations by cloned sequences from the alkBA region showed that we were previously mistaken in inferring the existence of a separate unlinked alkC cluster. Studies with an alkB-lacZ transcription fusion construct established that the operon is transcribed in the order alkBAC and is under positive regulation by alkR regulatory functions.
Variational and nonvariational principles in quantum transport calculations

A variational principle is not generally satisfied in steady-state quantum transport as opposed to the case of ground-state problems. We show that for a short-range potential, a functional for the scattering amplitude can be introduced that is stationary for arbitrary variations about the exact scattering wave function. However, except for the special case of spherically symmetric potentials, the functional does not satisfy any minimum principle even in linear response and for single-channel scattering. The absence of a minimum principle puts severe limitations on the choice of trial wave functions in transport calculations. Examples of electronic transport in selected quantum wires will be presented to illustrate the problem.
Laser photoelectron spectroscopy of vibrationally relaxed CH−2: A reinvestigation of the singlet–triplet splitting in methylene

The photoelectron spectrum of CH−2 has been reinvestigated using a new apparatus that incorporates a flowing afterglow ion source, providing vibrational and rotational cooling of the sample ions. Earlier photoelectron studies [J. Chem. Phys. 74, 5460 (1981)] employing gas discharge and sputter ion sources were plagued by hot CH−2 ions whose vibrational population distribution, for reasons not yet explicable, could not be detectably altered by modification of source conditions. In contrast, the spectrum of cooled CH−2 displays a markedly changed vibronic band intensity profile for the CH−2 (2B1) →−e− CH2(3B1) transition. These results enable several previously observed spectral features to be positively identified as vibrational hot bands. The new CH−2 photoelectron spectrum is consistent only with the methylene singlet–triplet splitting of approximately 9 kcal/mol determined by numerous recent experimental and theoretical studies.
Metastatic instability of murine tumor metastases: Dependence on tumor type

Fifteen metastatic lines derived in vivo from three syngeneic murine tumors, the sarcomas SA-NH and SA-4020 and the hepatic carcinoma HCA-I, were assessed for their stability of metastasis formation upon isotransplantation for several successive generations in syngeneic animals. Change in the metastatic phenotype was actively encouraged by a new procedure, the artificial selection for increased or decreased metastasis formation. Metastatic instability was dependent on tumor type, with five of six lines of tumor SA-NH, one of four lines of tumor SA-4020, and possibly one of five lines of HCA-I changing in lung metastasis formation. The instability of lung metastasis formation was also assessed by analyzing changes in the variance of the lines. Concomitant with a change in metastatic potential for lung metastasis, we observed a similar change for abdominal lymph node metastasis. We also report the selection of a less metastatic line. The variance of lung metastasis increased significantly only in the SA-NH lines. The instability of metastasis formation was attributed to genetic instability of metastatic cell lines.
Factorization of certain evolution operators using lie algebra: Convergence theorems

This work concerns convergence theorems with a sequence of ξ-approximants for exponential evolution operators with Lie operator arguments. A companion paper presents the formulation of the ξ-approximants. The theorems presented in this paper give the conditions which are sufficient for convergence of the sequences. Although the main emphasis will be on convergence properties of the one-dimensional case, the generalization to multidimensional cases is quite straightforward.
ONE-DIMENSIONAL PARTICLE VELOCITY PROBABILITY DENSITIES MEASURED IN TURBULENT GAS-PARTICLE DUCT FLOW

Abstract This paper presents measurements of the axial particle velocity probability densities made with a laser Doppler velocimeter in a 7·62 cm square duct. Spherical glass beads with mean particle diameters of 44 and 214 μm were studied at mean gas velocities near 30 m/sec. The particle-gas loading ratios were less than 1, and the Reynolds numbers close to 200,000. At all test section positions measured the particle velocity probability densities were approximately Gaussian in shape. The particle velocity intensities for the 214 μm particles were significantly greater than the gas velocity intensities at the duct center. It is felt that this was primarily a consequence of the particle size distribution variance.
Social Engagement and Depressive Symptoms in Late Life Longitudinal Findings

Objectives: The purpose is to investigate whether social engagement protects against depressive symptoms in older adults. Method: Three waves of data from a representative cohort study of community-dwelling adults aged 65 years and above from the New Haven Established Populations for the Epidemiologic Study of the Elderly are examined using random effects models. Results: Social engagement (an index combining social and productive activity) is associated with lower CES-D scores after adjustment for age, sex, time, education, marital status, health and functional status, and fitness activities. This association is generally constant with time, suggesting a cross-sectional association. In addition, social engagement is associated with change in depressive symptoms, but only among those with CES-D scores below 16 at baseline. Discussion: Social engagement is independently associated with depressive symptoms cross-sectionally. A longitudinal association is seen only among those not depressed at baseline.
Architectural alterations in rat cerebral microvessels after hypobaric hypoxia

We performed 3-dimensional studies of vascular casts of the microvasculature of the cerebral cortex of rats that were exposed to three weeks of hypobaric hypoxia and of control rats. Scanning electron microscopy of the casts gave the qualitative impression of increased vascularity of the cerebral cortex, particularly the deeper layers, in hypoxic rats. Quantitative analysis of capillary segment lengths revealed a significant shift in the frequency distribution to longer lengths (from 77 +/- 8 to 90 +/- 14 microns) in the deep, but not in the superficial, layers of the cerebral cortex of hypoxic rats. These findings agree with previous results reporting increased capillary density in the brain after exposure to prolonged hypobaric hypoxia and suggest that capillary segment elongation plays a role in the increased capillary density in the deeper layers of the cerebral cortex.
The Nucleus-Nucleus Potential.

Abstract Using the generator coordinate method to investigate the validity of the use of a potential to describe heavy ion elastic scattering, it is found that, under certain conditions, an effective potential exists. These conditions are generally satisfied by heavy ions, especially for the potential's tail. The potential obtained includes a kinetic energy contribution. The potential is further investigated using a density-dependent delta interaction.
Alkylation of inorganic oxo compounds and insights on preventing DNA damage

Metabolism of food- and tobacco-borne procarcinogens results in the exposure of DNA to toxic alkylating agents. These assaults can bring about DNA alkylation damage, mutations, and cancer. Dietary inorganic compounds such as selenium and vanadium are known to prevent cancer, possibly by reacting directly with alkylating agents, thereby preventing DNA damage. To understand potential interactions between oxo species and alkylating toxins, we reacted a series of alkylating agents with varied classes of oxo compounds (i.e., vanadates, selenate, phosphate, sulfate, acetate, nitrate, and nitrite). A new organic-soluble selenate, [(C6H5)4P]3(O3SeOCH2OSeO3)(HSeO4), was synthesized and characterized for these studies. Vanadates were found to convert ethylating agents into ethanol, whereas other anions formed esters upon alkylation. General trends show that oxo anions of the greatest charge density were the most reactive. These studies suggest that the design of new compounds for cancer prevention should incorporat...
Response to Letter Regarding Article, “Fibrinolysis for Intraventricular Hemorrhage: An Updated Meta-Analysis and Systematic Review of the Literature”

We thank Gaberel et al1 for their timely review of our recent meta-analysis regarding the use of intraventricular fibrinolysis for intraventricular hemorrhage (IVH). They have raised several points we would like to address. The major criticism they present is that the main difference between our meta-analysis and theirs is the inclusion of IVH because of other causes than spontaneous supratentorial intracerebral hemorrhage, namely IVH secondary to aneurysmal rupture. Although we agree that the underlying cause of IVH may impact mortality, we think that our analysis showed varying results because of several other important reasons. Their 2011 meta-analysis evaluated mortality in only 316 patients from 12 …
THE CYTOKINES INTERFERON-|[gamma]| (IFN-|[gamma]|) AND INTERLEUKIN 4 (IL-4) PROMOTE TRANSCYTOSIS OF SECRETORY IgA (SIgA) IN HUMAN EPITHELIAL CELLS IN VITRO

We have previously demonstrated that the HT-29 human coion carcinoma cell line expresses secretory component (SC), and that culture of these cells with IL-4 and with IFN-γ considerably augments the expression of SC in these cells. Our objective here was to ascertain if this is associated with increased transcytosis of SlgA across the enterocyte. Transparent Biopore membrane inserts were coated with human placental collagen matrix. The coated inserts were placed in 6 well cell cluster culture plates, 36 mm in diameter. On the following day. HT-29 cells maintained in RPMI 1640 were seeded in the inserts in a concentration of 107 cells/ml. RPMI 1640 only was placed in the outer well. Twenty four hours later the cells formed a macroscopic monolayer on the filter. lNF-γ and IL-4 were added in a concentration of 100u/ml each. Forty eight hours later, 125I-labelled monomeric IgA (mIgA) (control) and polymeric IgA (pIgA) (test) were added to the inserts. After 24 h, total and SC-associated radioactivity were measured in the fluid of the outer wells. It was found that SC-associatcd radioactivity was 3x higher in the pIg A wells than in the mIgA wells. It was also 3x higher when compared to filters coated with the CaCo 2 human carcinoma cell line, shown by us not to express SC.
Adjuvant therapy for pancreatic cancer: current status and future directions

This article summarizes the important past and ongoing adjuvant therapy trials for pancreatic cancer. The recent developments in the fields of radiosensitization, chemotherapy, and molecular-targeted therapy are outlined. Finally, the future study strategies for adjuvant therapy trials are discussed.
Electron microscopy of C-protein molecules from chicken skeletal muscle.

C-protein from chicken pectoralis muscle has been purified by sequential DEAE-Sephadex and hydroxyapatite chromatography and examined by transmission electron microscopy after spraying in glycerol onto mica and replicating by rotary shadowing with platinum. The most frequently observed particles were of three forms: rod-shaped, U-shaped and V-shaped. Within a size range of 15–40 nm these three groups accounted for 70% of over 800 particles categorized and measured. The remaining particles could not be classified. Since the relative abundance of each of these three forms was well in excess of any of the contaminating proteins detectable by SDS-polyacrylamide gel electrophoresis, we conclude that these variant forms represent C-protein molecules in differing conformations and/or deformations. Particles were observed which were intermediate between rod-shaped and tightly curved U-shaped forms, and between rod and acutely angled V-shaped forms. These results are compatible with a molecular model of a 32 nm × 3 nm flexible, rod-shaped C-protein monomer similar to one previously proposed from hydrodynamic studies and extend recent observations on the ultrastructure of cardiac C-protein. Infrequently, a discontinuously larger V-shaped form was seen, possibly representing a C-protein dimer.
SUPERFLUID FIELD THEORY

The very low temperature dynamics of an isotropic superfluid is derived from a repulsive bosonic field theory. The field theory is a fully dynamical generalization of the Ginzburg-Landau theory, which at zero temperature has semiclassical superfluid solutions. It is shown that supercurrent quenching occurs above some intrinsic critical velocity. The speed of first sound is calculated and the Landau criterion for a maximum superfluid velocity is derived. At finite temperature, the thermodynamic potential is computed, the order parameter and gap equations are derived, the origin of the Landau two-fluid model is identified and the thermomechanical effect is explained. This theory successfully describes many of the features of 4He well below the critical temperature, as well as relativistic generalizations.
Designing Cognitive Apprenticeships for Biomedical Engineering

This article explores challenges involved in developing effective and workable models for engineering education that emphasize the development of student cognitive skills over the delivery of specific course content. It chronicles efforts to systematically design engineering learning environments based on cognitive and learning science studies and then to optimize those environments through “design-based research.” It follows the evolutionary trajectory of curricular design efforts over four years using Problem-based Learning (PBL) in the Department of Biomedical Engineering at Georgia Tech, elucidating the activities, mistakes, realizations and the progressive refinements instituted towards the development of learning theory in the context of biomedical engineering. It argues for the need to scaffold students in the development of model-based reasoning throughout the engineering curricula.
Temperature and Gas Pressure Effects in Vertically Aligned Carbon Nanotube Growth from Fe−Mo Catalyst

Vertically aligned carbon nanotubes are grown from Al2O3-supported Fe−Mo catalyst in a hot filament chemical vapor deposition apparatus. We compare the effect of carbon nanotube growth on deposition of 0.5 and 1 nm thick Fe catalyst layers before and after deposition of 0.1 and 0.2 nm thick layers of Mo. We observe that the order of deposition plays a role in the height of the nanotube arrays, especially evident during growth at elevated reaction pressures where carbon flux is higher. We investigate the role of temperature and pressure on features of the nanotube arrays such as height, alignment, quality, volumetric density, and diameter distribution for each of the catalyst thicknesses and for each case of Fe/Mo and Mo/Fe. We compare our results to those obtained from carpets grown from pure Fe catalyst, and observe that a Mo cocatalyst can be advantageous regardless of how it is deposited. However, we find that the order of deposition plays a key role in the temperature and pressure range in which optim...
Microrefugia and species persistence in the Galápagos highlands: a 26,000-year paleoecological perspective

The Galapagos Islands are known to have experienced significant drought during the Quaternary. The loss of mesophytic upland habitats has been suggested to underlie the relatively lower endemism of upland compared with lowland plant assemblages. A fossil pollen record spanning the last 26,000 years from an upland bog on Santa Cruz Island, revealed the persistent presence of highland pollen and spore types during the last glacial maximum and a millennial-scale series of droughts in the mid Holocene. The absence of lowland taxa and presence of mesic taxa led to the conclusion that the highland flora of the Galapagos persisted during both these periods. The resiliency of the highland flora of the Galapagos to long-term drought contradicts an earlier hypothesis that an extinction of highland taxa occurred during the last glacial maximum and that rapid Holocene speciation created the modern plant assemblage within the last 10,000 years. Based on the palynological data, we suggest that, even during the height of glacial and Holocene droughts, cool sea-surface temperatures and strong trade-wind activity would have promoted persistent ground level cloudiness that provided the necessary moisture inputs to maintain microrefugia for mesophytic plants. Although moist conditions were maintained, the lack of precipitation caused the loss of open water habitat during such events, and accounts for the known extinctions of species such as Azolla sp., and Elatine sp., while other moisture dependent taxa, i.e. Cyathea weatherbyana, persisted.
Comprehensive measurements of the intermittency exponent in high Reynolds number turbulent flows

The intermittency exponent μ is determined from comprehensive measurements in the mixing layer (Rλ ≈ 2.0 × 103) and in the return channel (Rλ ≈ 3.2 × 103) of a large wind tunnel as well as in an atmospheric surface layer at Rλ ≈ (3.3–12.7) × 103. To estimate the value of μ and its dependence on Rλ and the flow conditions, different methods of data processing are applied to the same data base, i.e., μ is defined by its scaling behaviour in the inertial range of centered and non-centered correlation functions and spectra of energy dissipation, second order moments of r and lnr, etc. (Here Rλ is the Taylor microscale based Reynolds number, and r is the energy dissipation averaged over a segment of length r.) It is found that these methods do not define a unique value of μ but a set of different scaling exponents, and these exponents stay systematically different over the range of flow conditions which was studied. No tendency for these exponents to collapse is observed up to Rλ = 12.7 × 103.
KINETIC AND REACTIVE PROPERTIES OF ETHYLENE ON CLEAN AND HYDROGEN-COVERED Pd(111)

Several molecular adsorption states are identified following ethylene adsorption on clean and hydrogen-covered Pd(111) using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). Di-σ-bonded ethylene forms on clean Pd(111) desorbing with an activation energy of 80 kJ/mol at low coverages. The strong intermolecular lateral interactions considerably reduce the desorption temperature at higher coverages. Π-bonded ethylene is formed on hydrogen-covered Pd(111), where the proportion of π-bonded species increases with hydrogen coverage. This species converts to the more stable di-σ-bonded species on heating. Ethane formation is detected in TPD from hydrogen-precovered Pd(111), which is predominantly formed by reaction with π-bonded ethylene.
Assessment of fungicide systemicity in wheat using LC-MS/MS

BACKGROUND: Systemicity is an important attribute of fungicides that is difficult to measure in early-stage screening without labeling the compound with a radioisotope. A method of measuring translocation that does not require potent fungicidal activity or a radiolabel would guide identification of compounds with desirable attributes. RESULTS: The authors developed an analytical technique that mimics field application, using LC-MS/MS to screen compounds for translocation in wheat leaves. The method sorted commercial and experimental fungicides appropriately into systemic and non-systemic categories. A model using LC-MS/MS data was equivalent to a lipophilicity model and superior to a water solubility model at predicting compound systemicity. CONCLUSION: Early-stage compounds can be screened for systemicity on whole plants using LC-MS/MS. Copyright © 2008 Society of Chemical Industry
Phrenic responses to contralateral spinal stimulation in rats: effects of old age or chronic spinal hemisection.

Abstract Serotonin reveals ineffective spinal pathways from the C2-lateral funiculus to contralateral phrenic motoneurons in young adult rats with acute spinal hemisection. We tested the hypothesis that old age (1.5–2 years) or chronic hemisection (3–5 days) strengthens these pre-existing crossed spinal pathways. There were no consistent differences between young adult rats with acute hemisection versus young adult rats with chronic hemisection or old rat with acute hemisection except that one long-latency phrenic excitation could not be elicited in old rats. The results indicate that neither old age nor chronic hemisection strengthens crossed-spinal pathways, but that old age may selectively diminish spinal pathways involved in the neural control of breathing.
The effect of metal ions on arginase from the zebra mussel Dreissena polymorpha

Arginase (L-arginine amidinohydrolase, EC 3.5.3.1) is widely distributed in living organisms. The effect of metal ions on arginase was studied in the zebra mussel, a new exotic species of mollusk that was recently introduced into the Great Lakes. Arginase activity was found in both soluble and membrane-bound forms in the zebra mussel. Like all other arginases, zebra mussel arginase required Mn2+ for activity. In addition to Mn2+, arginase was also activated by Ni2+ and Co2+. The activation by Ni2+ was time dependent, unlike the activation by Mn2+ and Co2+. Several bivalent and trivalent metal ions were inhibitors of the enzyme. Dialysis of the soluble arginase with or without prior activation by Mn2+ caused a large loss in enzyme activity which could not be recovered by incubation with Mn2+, Ni2+, or Co2+. Arginase was inhibited by high concentrations of substrate, and the Km of the enzyme was similar with or without Mn2+, Ni2+, or Co2+.
Clinical involvement of mesenteric and antimesenteric borders of small bowel loops. II. Radiologic interpretation of pathologic alterations.

Many small bowel abnormalities selectively involve the mesenteric or antimesenteric borders of small intestinal loops solely or predominantly. This report documents the roentgen localization and diagnosis of a variety of intraabdominal disease states by their effects specifically on the mesenteric or antimesenteric margins of small bowel loops. The conditions with selective or predominant involvement of either the mesenteric or antimesenteric borders include diverticulosis, Meckel's diverticulum, intestinal duplication, seeded metastases, hematogeneous metastases, regional enteritis, lymphoma, and intestinal ischemia and intramural bleeding.
Rosiglitazone decreases albuminuria in type 2 diabetic patients.

Thiazolidinediones are insulin-sensitizing compounds that reduce plasma glucose and improve the lipid profile of type 2 diabetic patients. We determined the effect of rosiglitazone in 15 type 2 diabetic patients and compared these results to 14 randomly assigned placebo patients. After 3 months, the urinary albumin to creatinine ratio was significantly decreased, while the glucose metabolic clearance rate, during insulin clamp, was significantly increased by rosiglitazone compared to the placebo group. Fasting free fatty acid and tumor necrosis factor- α (TNF- α ) levels were significantly decreased, while the adiponectin concentration was significantly increased by rosiglitazone treatment. The percentage decrease in albuminuria correlated with the decrease in fasting plasma glucose, free fatty acids TNF- α and the increase in fat mass, plasma adiponectin, and glucose metabolic clearance rate. Stepwise linear regression analysis showed the decrease in TNF- α and the increase in adiponectin were independently associated with decreased albuminuria. Our study indicates that thiazolidinediones may be useful to prevent nephropathy in type 2 diabetic patients.
Stem cell therapy for ischemic heart disease: where are we?

Purpose of review Stem cell transplantation is currently generating a great deal of interest in the treatment of ischemic heart disease (IHD) as the replacement of akinetic scar tissue by viable myocardium should improve cardiac function, impede progressive left ventricular remodeling, and revascularize ischemic areas. Substantial work in stem cell therapy for ischemic heart disease has recently been reported. Recent findings Stem cell populations have been expanding. Most recently, induced pluripotent stem (iPS) cells have been discovered that have the potential to revolutionize stem cell therapy. Many of the efforts in stem cell therapy for ischemic heart disease have been inconclusive and often contradicting. Transdifferentiation of stem cells into cardiomyocytes remains controversial. The therapeutic effect of the stem cell seems consistent with paracrine function rather than transdifferentiation. Systemic and micromilieu factors appear to dictate the fate of implanted stem cells. Summary Although animal studies produce controversial results, and many basic questions remain unanswered, more and more clinical trials are underway. Consequently, researchers must begin to focus upon a few basic critical issues: the modulation of the systemic and microenvironment for stem cells in order to augment stem cell survival and transdifferentiation; the underlying mechanisms of stem cell therapy and the fate of stem cells; differentiation into myocytes or other terminal cell populations with favorable paracrine functions.
The lattice as allosteric effector: Structural studies of αβ- and γ-tubulin clarify the role of GTP in microtubule assembly

GTP-dependent microtubule polymerization dynamics are required for cell division and are accompanied by domain rearrangements in the polymerizing subunit, αβ-tubulin. Two opposing models describe the role of GTP and its relationship to conformational change in αβ-tubulin. The allosteric model posits that unpolymerized αβ-tubulin adopts a more polymerization-competent conformation upon GTP binding. The lattice model posits that conformational changes occur only upon recruitment into the growing lattice. Published data support a lattice model, but are largely indirect and so the allosteric model has prevailed. We present two independent solution probes of the conformation of αβ-tubulin, the 2.3 A crystal structure of γ-tubulin bound to GDP, and kinetic simulations to interpret the functional consequences of the structural data. These results (with our previous γ-tubulin:GTPγS structure) support the lattice model by demonstrating that major domain rearrangements do not occur in eukaryotic tubulins in response to GTP binding, and that the unpolymerized conformation of αβ-tubulin differs significantly from the polymerized one. Thus, geometric constraints of lateral self-assembly must drive αβ-tubulin conformational changes, whereas GTP plays a secondary role to tune the strength of longitudinal contacts within the microtubule lattice. αβ-Tubulin behaves like a bent spring, resisting straightening until forced to do so by GTP-mediated interactions with the growing microtubule. Kinetic simulations demonstrate that resistance to straightening opposes microtubule initiation by specifically destabilizing early assembly intermediates that are especially sensitive to the strength of lateral interactions. These data provide new insights into the molecular origins of dynamic microtubule behavior.
INCIDENCE AND NATURAL HISTORY OF CONTRALATERAL VESICOURETERAL REFLUX IN PATIENTS PRESENTING WITH UNILATERAL DISEASE

AbstractPurpose: The new onset of contralateral vesicoureteral reflux after the surgical correction of unilateral disease has been well documented and it is attributed to the surgical procedure. However, to our knowledge the spontaneous development of contralateral reflux in patients treated nonoperatively for unilateral disease has not been documented previously. We evaluated the incidence and natural history of contralateral reflux in children presenting with initially unilateral disease.Materials and Methods: We reviewed the records of 130 girls and 13 boys with a mean age of 29.1 months presenting with primary unilateral reflux between 1983 and 1996. The grade of and time to new onset contralateral reflux were noted. Whereas the initial radiological diagnosis relied on contrast voiding cystourethrography, followup evaluation included contrast and radionuclide voiding cystourethrography. The upper tracts were assessed by ultrasound and/or excretory urography, and cortical renal scans were performed sel...