cssi/SciSciGPT-SciSciNet huggingface dataset:
Observations of martian gullies and constraints on potential formation mechanisms

Abstract The discovery of presumably geologically recent gully features on Mars (Malin and Edgett, 2000, Science 288, 2330–2335) has spawned a wide variety of proposed theories of their origin including hypotheses of the type of erosive material. To test the validity of gully formation mechanisms, data from the Mars Global Surveyor spacecraft has been analyzed to uncover trends in the dimensional and physical properties of the gullies and their surrounding terrain. We located 106 Mars Orbiter Camera (MOC) images that contain clear evidence of gully landforms, distributed in the southern mid and high latitudes, and analyzed these images in combination with Mars Orbiter Laser Altimeter (MOLA) and Thermal Emission Spectrometer (TES) data to provide quantitative measurements of numerous gully characteristics. Parameters we measured include apparent source depth and distribution, vertical and horizontal dimensions, slopes, orientations, and present-day characteristics that affect local ground temperatures. We find that the number of gully systems normalized to the number of MOC images steadily declines as one moves poleward of 30° S, reaches a minimum value between 60°–63° S, and then again rises poleward of 63° S. All gully alcove heads occur within the upper one-third of the slope encompassing the gully and the alcove bases occur within the upper two-thirds of the slope. Also, the gully alcove heads occur typically within the first 200 meters of the overlying ridge with the exception of gullies equatorward of 40° S where some alcove heads reach a maximum depth of 1000 meters. While gullies exhibit complex slope orientation trends, gullies are found on all slope orientations at all the latitudes studied. Assuming thermal conductivities derived from TES measurements as well as modeled surface temperatures, we find that 79% of the gully alcove bases lie at depths where subsurface temperatures are greater than 273 K and 21% of the alcove bases lie within the solid water regime. Most of the gully alcoves lie outside the temperature–pressure phase stability of liquid CO2. Based on a comparison of measured gully features with predictions from the various models of gully formation, we find that models involving carbon dioxide, melting ground ice in the upper few meters of the soil, dry landslide, and surface snowmelt are the least likely to describe the formation of the martian gullies. Although some discrepancies still exist between prediction and observation, the shallow and deep aquifer models remain as the most plausible theories. Interior processes involving subsurface fluid sources are generally favored over exogenic processes such as wind and snowfall for explaining the origin of the martian gullies.
Graphitization of synthetic diamond by 193 nm laser light: Comparison of 12C-enriched diamonds with those of natural isotopic composition

Abstract Polished surfaces of diamonds of natural isotopic composition are transformed to graphite upon irradiation by ArF excimer laser light. The surface of a similar diamond made of enriched 12 C is not. A possible explanation involves a competition between graphitization and ablation in which the former is more strongly affected by the recently determined higher thermal diffusivity of 12 C diamond.
The HAMP Linker in Histidine Kinase Dimeric Receptors Is Critical for Symmetric Transmembrane Signal Transduction

The HAMP linker, a common structural element between a sensor and a transmitter module in various sensor proteins, plays an essential role in signal transduction. Here, by in vivo complementation experiments with Tar-EnvZ hybrid receptor mutants in which the HAMP linker forms a heterodimer with Tar and EnvZ-type subunits, we found that mutations at one linker only affect the function of EnvZ in the same subunit. However, the same mutations affect the EnvZ function of both subunits when only a Tar or EnvZ-type HAMP linker is used. These results suggest that intersubunit interactions in the HAMP linker normally mediate signal transduction through both subunits in a sensor dimer, whereas the signal is asymmetrically transduced through the linker in a heterodimer. This is the first demonstration that two HAMP linkers in a sensor dimer are functionally coupled for normal signal transduction; however, this functional coupling can be reduced when the HAMP linkers lose their symmetric nature.
DNCB reactivity and prognosis in 419 patients with malignant melanoma

Delayed cutaneous hypersensitivity to 2,3-dinitrochlorobenzene (DNCB) was tested in 419 patients with malignant melanoma to determine whether DNCB reactivity was associated with prognosis. At the time of definitive surgery, a positive DNCB test was seen in 82% of the patients in State I (regional lymph node histologically negative) and in 81% of patients in Stage II (regional lymph node positive). A positive DNCB test, obtained at the time of staging in patients with more advanced disease, was seen in 70% of patients in State III (metastases in, at most, on internal organ) and in 68% of patients in Stage IV (metastases in more internal organ). Using the chi 2 test, the trend of a decrease in DNCB reactivity from Stage I to Stage IV is significant (P less than 0.04). In regard to DNCB reactivity and prognosis, the following statistical differences (P less than 0.05) were obtained: In Stage II, the recurrence distribution for DNCB-positive patients is more favorable than for DNCB-negative patients (estimated median time to recurrence 16 vs. 7 months); the survival distribution again in Stage II was more favorable for DNCB-positive patients tha DNCB-negative patients (estimated survival time 31 vs. 18 months). When the group of State II patients was divided into subgroups with different prognoses (state of primary at the time of lymphadenectomy), a survival advantage was seen in all substages but was statistically significant (P less than 0.05) only in Stage II d (regional lymph node involvement diagnosed more than two months after resection of primary melanoma). The results of DNCB tests in patients with malignant melanoma correlate with stage of disease and, in Stage II, with prognosis.
Isolation and partial characterization of a Taenia taeniaeformis metacestode proteinase inhibitor

Abstract Suquet C. , Green-Edwards C. and Wes Leid R. 1984. Isolation and partial characterization of a Taenia taeniaeformis metacestode proteinase inhibitor. International Journal for Parasitology 14 : 165–172. A proteinase inhibitor from the metacestode of Taenia taeniaeformis was purified 136-fold to apparent homogeneity as evidenced by one Coomassie Blue protein staining band on 10% SDS slab gels under both reducing and non-reducing conditions. The apparent molecular weight under dissociating conditions was 19,500. This parasite protein inhibited esterolysis of TAME and BTEE by bovine pancreatic trypsin and chymotrypsin respectively in a time and dose-dependent manner. Proteolysis of casein by both enzymes was also inhibited in a time and dose-dependent manner. The parasite inhibitor was stable from pH 2.2 to 10.5 and was fully active after heating at 56 °C for 3 h. The proteases pronase and thermolysin, at concentrations of 1 mg ml −1 , completely inactivated the metacestode inhibitor. Two sulfhydryl proteases, papain and chymopapain, used at concentrations of 1 mg ml −1 were without effect. The irreversible proteinase inhibitors TLCK, TPCK and PMSF at concentrations up to 10 mM had no effect on the parasite inhibitor.
Effect of Calcium Status, Mass of Calcium Administered and Age on Ca45 Metabolism in the Rat

Summary(1) The fecal excretion of orally administered Ca45 is a sensitive indication of the calcium status of the rat; (2) placing normal rats on a low calcium diet for as little as 2 days greatly increased their ability to absorb Ca45 from the tract; (3) the specific activity of labeled calcium at the site of absorption had little effect upon its absorption; (4) in general, younger rats absorbed more Ca45 than did older ones although there was no significant difference between 6 1/2 and 16-month-old animals; (5) for meaningful studies of this type, interpretations must include consideration of exchange reactions, and care must be given to initial selection of diets and animals, preparation of animals for the experiment, and dietary management during the experimental period.
Spike detection in human muscle sympathetic nerve activity using the kurtosis of stationary wavelet transform coefficients.

Abstract The accurate assessment of autonomic sympathetic function is important in the diagnosis and study of various autonomic and cardiovascular disorders. Sympathetic function in humans can be assessed by recording the muscle sympathetic nerve activity, which is characterized by synchronous neuronal discharges separated by periods of neural silence dominated by colored Gaussian noise. The raw nerve activity is generally rectified, integrated, and quantified using the integrated burst rate or area. We propose an alternative quantification involving spike detection using a two-stage stationary wavelet transform (SWT) de-noising method. The SWT coefficients are first separated into noise-related and burst-related coefficients on the basis of their local kurtosis. The noise-related coefficients are then used to establish a threshold to identify spikes within the bursts. This method demonstrated better detection performance than an unsupervised amplitude discriminator and similar wavelet-based methods when confronted with simulated data of varying burst rate and signal to noise ratio. Additional validation on data acquired during a graded head-up tilt protocol revealed a strong correlation between the mean spike rate and the mean integrate burst rate (r = 0.85) and burst area rate (r = 0.91). In conclusion, the kurtosis-based wavelet de-noising technique is a potentially useful method of studying sympathetic nerve activity in humans.
Vesicular neurotransmitter transport and the presynaptic regulation of quantal size

Specific transport activities package classical neurotransmitters into secretory vesicles for release by regulated exocytosis, but the proteins responsible for the vesicular transport of neurotransmitters are still being identified. One family of proteins includes vesicular transporters for monoamines and acetylcholine. Genetic manipulation in cells and in mice now shows that changes in the expression of these proteins can alter the amount of neurotransmitter stored per synaptic vesicle, the amount released and behavior. Although the mechanisms responsible for regulating these transporters in vivo remains unknown, recent work has demonstrated the potential for regulation by changes in intrinsic activity and in location. In addition, a recently identified vesicular transporter for GABA defines a novel family of proteins that mediates the packaging of amino acid neurotransmitters.
Ethnic Differences in Drug Disposition and Response

Interindividual variability in drug response is a well-recognized problem resulting in both undertreatment and overtreatment of individuals receiving similar doses of drugs, with the potential for lack of therapeutic effect and for drug toxicity. The potential that interethnic differences might contribute to such interindividual variability in drug response has recently been recognized. Such interethnic differences in drug response may be due to either altered drug disposition or altered drug sensitivity among races at similar drug concentrations. In turn, such racial differences in drug disposition may be related to genetic or environmental factors, which are often difficult to separate.
Partition Regular Structures Contained in Large Sets Are Abundant

Furstenberg and Glasner have shown that for a particular notion of largeness in a group, namely piecewise syndeticity, if a set B is a large subset Z, then for any l?N, the set of length l arithmetic progressions lying entirely in B is large among the set of all length l aritmetic progressions. We extend this result to apply to infinitely many notions of largeness in arbitrary semigroups and to partition regular structures other than arithmetic progressions. We obtain, for example, similar results for the Hales?Jewett theorem.
A lidar technique to quantify surface deposition from atmospheric releases of bulk liquids

Abstract We show that a scanning, pulsed lidar can be used to quantify the time history and areal concentration of mass deposited on the ground from an elevated release of bulk liquid. Aircraft measurements, witness car depositions and evaporative modelling crudely support results from analysed lidar data.
Atrial plasmacytoma and hypercalcemia.

Objective: To describe a patient with hypercalcemia due to multiple myeloma and an associated atrial plasmacytoma. Methods: A case report is presented with clinical and laboratory findings. We review the differential diagnosis of hypercalcemia and discuss multiple myeloma and plasmacytomas. Results: A 48-year-old woman presented to the emergency department with lethargy after sustaining trauma to the head. She was found to have a subdural hematoma and a parietal intraparenchymal hemorrhage. She had a serum calcium level of 17.2 mg/dL (normal, 8.4 to 10.6), anemia, thrombocytopenia, and renal insufficiency. Serum protein electrophoresis revealed a monoclonal gammopathy, and a bone marrow biopsy specimen was consistent with multiple myeloma. The patient required surgical evacuation of her subdural hematoma. Postoperatively, multiple complications developed, including a supraventricular tachycardia. She did not regain consciousness, and ventilatory support was withdrawn. On autopsy, she was found to have dis...
The history of the concept of motivation.

Explanations and postulated mechanisms of motivation are traced from Hobbes to current cognitive formulations. Beginning with the hedonic principle, succeeding explanations of motivation have included drive theory, in terms of reflexive properties and in the Freudian notion of unconscious motivation, and current cognitive explanations, which have not yet been fully developed. It is hoped that the repeating cycle from rationality to irrationality and over again can be avoided in future explanations.
Predicting Postconcussion Syndrome after Minor Traumatic Brain Injury

BACKGROUND Up to 50% of patients with minor traumatic brain injury (mTBI) develop postconcussion syndrome (PCS). A decision rule to stratify risk for PCS is needed. OBJECTIVE To identify mTBI patients at low and high risk of PCS by comparing the predictive values of variables generated by logistic regression (LR) and recursive partitioning (RP). METHODS This was a prospective, observational study of 69 mTBI patients aged >16 years presenting to the emergency department of a university teaching hospital. Minor TBI was defined as loss of consciousness 24 on the Hopkins Verbal Learning A (HVLA) (by LR) and in 9% of those injured in sports scoring >22 on HVLA (RP). High risk: PCS occurred in 89% of women scoring <9 on the Digit Span test (LR) and in 92% of those injured via falls or motor vehicle collision scoring <11.5 on HVLB2 (RP). CONCLUSIONS Despite the high incidence of PCS, we were able to identify a low-risk subgroup with an average PCS risk of <10% and a high-risk subgroup with a PCS risk of approximately 90%. Combining results from LR and RP expanded the number of patients able to be classified as high/low risk. Prospective validation is necessary.
A criterion for significant common factor variance

Up to the present only empirical methods have been available for determining the number of factors to be extracted from a matrix of correlations. The problem has been confused by the implicit attitude that a matrix of intercorrelations between psychological variables has a rank which is determinable. A table of residuals always contains error variance and common factor variance. The extraction of successive factors increases the proportion of error variance remaining to common factor variance remaining, and a point is reached where the extraction of more dimensions would contain so much error variance that the common factor variance would be overshadowed. The critical value for this point is determined by probability theory and does not take into account the size of the residuals. Interpretation of the criterion is discussed.
T.S. Eliot and ideology

1. Historical background 2. The French connection 3. Orthodoxy and heresy 4. Architect of a Christian order 5. Visions and revisions 6. Eliot and the new criticism Conclusion Notes Index.
Assessing the potential for ash canopy tree replacement via current regeneration following emerald ash borer-caused mortality on southeastern Michigan landscapes

Abstract The emerald ash borer (EAB) has killed millions of ash trees in Michigan and at least fourteen other states since its first detection near its introduction point in metropolitan Detroit in 2002. Despite overstory ash mortality near 100% in many areas, ash seedling and saplings remain unaffected and provide the potential for ash re-establishment into the canopy of deciduous forests of the region. We examined the potential for ash re-establishment in areas of heavy mortality by measuring the status and change of ash regeneration at 45 sites across southeastern Lower Michigan in 2007 and 2009. Ash regeneration was found to be abundant in all forest types, particularly in the smallest height classes, though it was more abundant in ash species of upland forests compared to those of lowland forests. New seedlings 1–2 years old were less common than other regeneration size classes, and declined substantially between 2007 and 2009, suggesting a depletion of the ash seed bank in these forests. Regeneration density was not explained well by the presence of overstory ash prior to EAB introduction, suggesting that competitive interaction with other tree species in higher canopy strata is an important driver of ash regeneration density. Regeneration is sufficient to replenish overstory ash to pre-EAB levels in upland forests, though ecological changes caused by overstory ash mortality in lowland areas may affect local hydrology in a way that reduces opportunities for tree regeneration. Despite abundant ash regeneration, it remains unclear whether ash will recover to the overstory of forests in southeastern Michigan because of uncertainties in the future dynamics of EAB in the region.
Chevrel phases: An analysis of their metal-metal bonding and crystal chemistry

Abstract A useful measure of the total MoMo bonding in diverse phases containing Mo6Y8-type clusters (Y = S, Se, Cl, Br) is given by the Pauling bond order sum per electron ( PBO e ). These fall into two classes: (a) strongly bonded examples with PBO e values near 1.00 which contain either discrete clusters with extra outer (exo) atoms or infinite confacial clusters, and (b) the rhombohedral Mo6Ch8 and MxMo6Ch8 Chevrel phases with reduced PBO e values of 0.72–0.84 in which face-capping chalcogenide (Ch) must also fill exo positions. The matrix effect in the latter which is responsible for the reduced bond orders arises from a combination of particularly strong MoCh intercluster bonds and closed-shell ChCh repulsions [3.31 a (S), 3.38 a (Se)], which force an elongation of the Mo6 trigonal antiprism and reduce the MoMo bonding. There is no distinction between sulfide and selenide Chevrel phases in the degree of total MoMo bonding as expressed in bond orders. Changes in the structure on reduction are analyzed; the major effects come from loosening of the intercluster MoCh bonding and thence a decreased distortion (matrix effect) together with a flexing of the Mo6Ch8 host according to the size and charge of M. Distance considerations indicate substantial covalency between some M and Ch2, especially Pb and Ag, while cell volumes and MoCh2 distances suggest significant constriction occurs in phases with higher charged M, possibly owing to compression by the host lattice and coulombic contributions to binding. Evidence for MoM bonding with M = Fe, Co, Ni is also noted. Intercluster interactions and MoMo bonding in Mo6S6Br2 and in the mixed Mo6Ch8MonChm (n = 9,12) cluster phases are quite consistent with those in the Chevrel phases, the total MoMo bonding per electron increasing with cluster condensation owing principally to reduce ChCh repulsions.
Users’ perceptions of two types of hotel reservation Web sites

Abstract Building on the technology acceptance model (TAM), this study examined users’ perceptions of reservation Web sites: hotel-owned and third-party. As an experimental study, this study tested whether a modified variant of the TAM could be used to evaluate users’ perceptions of two different channels for hotel online reservations. Perceived usefulness was a key predictor of users’ attitudes toward using hotel-owned Web sites, while perceived ease of use was a key predictor of users’ attitudes toward using third-party Web sites. Both perceived playfulness and attitudes were two key predictors of users’ intentions to use hotel reservation Web sites. However, no significant differences in users’ perceptions were found between the two types of Web sites. Overall, users had more favorable attitudes and higher intentions to revisit third-party Web sites than hotel-owned Web sites.
On the independence from irrelevant alternatives in probabilistic choice models

Abstract Probabilistic choice models often invoke a behavioral assumption referred to as the independence from irrelevant alternatives. The implications of this condition have not been fully developed in probabilistic choice contexts. It is well known that nonpathological preferences may not exhibit the independence from irrelevant alternatives, which is apparently an assumption of convenience; and the obvious question is then whether the assumption is very restrictive. This paper addresses this question. A common model of probabilistic choice is constructed. A measure of the likelihood that independence from irrelevant alternatives holds is seen to arise naturally in this model. Given this measure, it is demonstrated that the condition will almost always fail to hold.
High Q Long-Range Surface Plasmon Polariton Modes in Sub-wavelength Metallic Microdisk Cavity

Metal-capped microdisk cavity supporting surface plasmon polaritons (SPP)-guided whispering gallery mode (WGM) can achieve higher cavity factor Q than traditional microdisk cavity in sub-wavelength dimensions. We have numerically analyzed the limiting factors on Q using finite difference time domain method. The Q of SPP-guided WGM is primarily limited by the loss of metal. A thin metal-sandwiched microdisk cavity supporting long-range surface plasmon polariton mode was proposed to reduce the metal loss. The proposed cavities have been shown to increase cavity Q by more than 15-fold and reduce threshold gain by more than threefold as opposed to traditional microdisk cavities.
ACCURATE DISCRETIZATION OF INCOMPRESSIBLE THREE-DIMENSIONAL NAVIER-STOKES EQUATIONS

In this article an accurate discretization of three-dimensional incompressible Navier-Stokes equations is derived with the finite analytic method (FAM). The finite analytic method incorporates the local analytic solutions to formulate the discrete algebraic representations of partial differential equations. A very accurate 27-point finite analytic discretization scheme can be derived from local analytic solutions of linearized three-dimensional convection-diffusion equations. Also, a computationally efficient 19-point finite analytic discretization scheme is derived utilizing the superposition of the local analytic solutions of linearized two-dimensional convection-diffusion equations. The accuracy of finite analytic discretization is analyzed. It is shown that using the 27-point scheme as an accurate benchmark case, the 19-paint finite analytic numerical solution is computationally efficient and accurately simulates both convection and diffusion. In this study it is also shown that, due to the analytic n...
Mandated Self-reporting of Ventilator-Associated Pneumonia Bundle and Catheter-Related Bloodstream Infection Bundle Compliance and Infection Rates

Importance As quality measures increasingly become tied to payment, evaluating the most effective ways to provide high-quality care becomes more important. Objectives To determine whether mandated reporting for ventilator and catheter bundle compliance is correlated with decreased infection rates, and to determine whether labor-intensive audits are correlated with compliance. Design, Setting, and Participants Multiyear retrospective review of aggregated data from all patients admitted to 15 intensive care units in a Veterans Affairs hospital setting (the Veterans Integrated Service Network 16) from 2009 to 2011. Exposures Ventilator-associated pneumonia and catheter-related bloodstream infections. Main Outcomes and Measures Mean rates of ventilator-associated pneumonia and catheter-related bloodstream infection were analyzed by year. Relationships between infection rates, self-reported compliance, and audits were analyzed by Pearson correlation. Results During the study period, ventilator-associated pneumonia decreased from 2.50 to 1.60 infections per 1000 ventilator days ( P = .07). The rate of pneumonia was not correlated with self-reported compliance overall ( R = 0.19) or by individual year (2009, R = 0.30; 2010, R = 0.24; 2011, R = 0.46); there was a correlation in cardiac intensive care units ( R = −0.70) but not other types of intensive care units (mixed, R = −0.18; medical, R = 0.42; surgical, R = 0.34). Catheter-related bloodstream infections decreased from 2.38 to 0.73 infections per 1000 catheter days ( P = .04). The rate of catheter infection was not correlated with self-reported compliance overall ( R = −0.18), by individual year (2009, R = −0.39; 2010, R = −0.42; 2011, R = 0.37), or by intensive care unit type (mixed, R = −0.19; cardiac, R = 0.55; medical, R = 0.17; surgical, R = −0.44). Conclusions and Relevance Current mandated self-reported compliance and audit measures are poorly correlated with decreased ventilator-associated pneumonia or catheter-related bloodstream infection.
Selecting the t Best of k Examinees Whose True Score Is Better Than a Standard

The paper considers the problem of selecting the t best of k normal populations and simultaneously determining whether the selected populations have a mean larger than a known standard. Illustrations are given for selecting the t best of k examinees when the binomial error model applies.
Multimedia in the Long Eighteenth Century

This paper describes a motivating digital humanities project for the analysis of music contained in more than 100,000 French and British works from the long eighteenth century along with the datasets, techniques and technology being developed to realize the initial goals. Additionally, the developed tools and an authoritative metadata repository will allow further analysis of paratext from other languages and time periods. Finally, a scholarly tool will be described that will provide resources for deeper study and allow for the more in-depth analysis of the evolution of published musical forms over time.
Correlation of Mira’s SiO Maser Properties

The v = 0, 1, and 2, J = 1-0 SiO maser spectra of Mira have been observed with high phase resolution over approximately three periods of the star. A time lag cross-correlation analysis of the integrated flux density and the velocity centroid of the emission indicates that the velocity structure varies in a consistent manner with emission during some oscillation periods of the star. Over two periods of the star the v = 1 integrated flux density and velocity centroid were correlated at the 0.67 level. The velocity centroid reached a maximum 0.066 phase earlier than the integrated flux density. These quantities were anticorrelated at the 0.71 level, with the velocity centroid reaching a minimum 0.59 phase earlier than the integrated flux density maximum. The other maser transitions show lower levels of correlation and other phase relationships. The velocity centroids of the spectra have been analyzed and compared with theoretical predictions of shock passage effects. These observations are relevant for kinematic models of the maser region and for maser-pumping models.
Cross-Modulation Interference Reduction for Pulse-Position Modulated UWB Signals

One of the popular modulation options that is used for ultra wideband (UWB) systems is pulse position modulation (PPM). In spite of many advantages of PPM, the cross-modulation interference (CMI) caused by multipath propagation degrades the performance of the UWB receivers when PPM modulation is used. In this paper, a technique for reducing the effect of CMI for PPM UWB signals is introduced. The proposed approach improves the performance of receivers greatly and eliminates the possibility of catastrophic errors. The proposed technique introduces variable modulation index instead of conventional fixed modulation index.
Monitoring Behavior: A Pilot Study Using an Ambulatory Eye-Tracker in Surgical Operating Rooms

Information provision is an important function of most technology interventions. Understanding human operators' patterns in consulting various information sources could provide insights into how displays should be designed. We tested the utility of an ambulatory eye-tracker in an operational setting for collecting data of monitoring behavior. Temporal patterns of eye-tracking data, coupled with the data on observed activities and events led to a model of monitoring that treats knowledge about the monitored process as a resource. In a semi-self-paced work environment, the operator could deploy the strategy of building up knowledge about the monitored process before anticipated high workload periods and reestablishing such knowledge immediately after high workload periods to replenish lost resources. Through measures of monitoring frequency and time series analysis, supportive evidence for the resource model was obtained from the eye-tracking data of the pilot study. The study successfully demonstrated the ...
Locally acyclic cluster algebras

Abstract This paper studies cluster algebras locally, by identifying a special class of localizations which are themselves cluster algebras. A ‘locally acyclic cluster algebra’ is a cluster algebra which admits a finite cover (in a geometric sense) by acyclic cluster algebras. Many important results about acyclic cluster algebras extend to locally acyclic cluster algebras (such as being finitely generated, integrally closed, and equaling their upper cluster algebra), as well as a result which is new even for acyclic cluster algebras (regularity over Q when the exchange matrix has full rank). Several techniques are developed for determining whether a cluster algebra is locally acyclic. Cluster algebras of marked surfaces with at least two boundary marked points are shown to be locally acyclic, providing a large class of examples of cluster algebras which are locally acyclic but not acyclic. Some specific examples are worked out in detail.
New Aptes Cross-linked Polymers from Poly(ethylene oxide)s and Cyanuric Chloride for Lithium Batteries

A new series of polymer electrolytes for use as membranes for lithium batteries are described. Electrolytes were made by polymerization between cyanuric chloride and diamino-terminated poly(ethylene oxide)s, followed by cross-linking via a sol-gel process. Thermal analysis and lithium conductivity of freestanding polymer films were studied. The effects of several variables on conductivity were investigated, such as length of backbone PEO chain, length of branching PEO chain, extent of branching, extent of cross-linking, salt content, and salt counterion. Polymer films with the highest percentage of PEO were found to be the most conductive, with a maximum lithium conductivity of 3.9 x 10(exp -5) S/cm at 25 C. Addition of plasticizer to the dry polymers increased conductivity by an order of magnitude.
Katalytische Aktivität von Enzymen mit modifiziertem aktivem Zentrum

Design und Aufbau von Peptiden und Proteinen mit neuartigen Bindungseigenschaften und neuartigem katalytischem Verhalten sind das Ziel des Protein-Engineerings1 . Eine Moglichkeit, dieses Ziel zu erreichen, ist die Umwandlung des aktiven Zentrums naturlicher Proteine, und zwar entweder durch ortsspezifische Mutagenese („site-directed mutagenesis”) oder durch chemische Modifizierung. Sofern durch solche Eingriffe die Tertiarstruktur nicht entscheidend verandert wird, sollte das Bindungszentrum des ursprunglichen Proteins wenigstens teilweise erhalten bleiben, so das das umgewandelte Enzym weiterhin Komplexe mit seinen Substraten bilden kann. Es sind viele Proteine mit Mutationen am aktiven Zentrum bekannt; dazu zahlt auch die von uns gewonnene Cystein-Mutante der alkalischen Phosphatase. Eine grundsatzliche Einschrankung der ortsspezifischen Mutagenese besteht darin, das nur die zwanzig naturlichen Aminosauren ausgetauscht werden konnen. Die alternative chemische Modifizierung ist schwierig durchzufuhren, wenn eine Aminosaure spezifisch durch eine andere ersetzt werden soll. Wir konnten jedoch zeigen, das Coenzymanaloga auf chemischem Weg in geeignete Positionen von Proteinen eingefuhrt und kovalent gebunden werden konnen. Dadurch wird die Gewinnung halbsynthetischer Enzyme moglich, deren katalytische Aktivitat sich grundlegend von der ihrer Vorlaufer-Proteine unterscheidet. Ein weiterer Zweig des Protein-Engineerings konzentriert sich auf Systeme, bei denen - in erster Naherung - die Faltung vernachlassigt werden kann und der Aufbau spezieller Sekundarstrukturen angestrebt wird. Beispiele aus unseren Arbeiten fur das erfolgreiche Design biologisch aktiver Peptide und Proteine auf diesem Weg sind Molekule, die die Eigenschaften von Apolipoproteinen, Toxinen und vielen Hormonen nachahmen. Vor kurzem haben wir begonnen, die beiden oben beschriebenen Moglichkeiten des Protein-Engineerings zu kombinieren. Auf diese Weise konnten kleine Enzyme wie Ribonuclease T1 und deren Strukturanaloga vollsynthetisch erhalten werden.
Organizational change in the Harvard College Library: A continued struggle for redefinition and renewal

Abstract In 1990, after years of status quo operations, the Harvard College Library began a process of unprecedented and intense change. This article chronicles and analyzes the change process, focusing on eight key success factors for strategic planning in an environment of continual change.
Dual fluorescence from an aromatic monoazine with close-lying 1n,π* and 1π,π* states

Abstract A variable-temperature fluorescence study of 3-methyl-2-aminopyridine in methylcyclohexane indicates that S2 emits at room temperature, while at 77 K S1 and S2 fluoresce. An out-of-plane vibrational mode (about 504 cm−1) in the low temperature emission spectrum indicates that vibronic coupling of 1n,π* and 1π,π* states is occurring. Interpretation of the behavior is supported by complete neglect of differential overlap—configuration interaction calculations, lifetime measurements and excitation spectra. The observed effect, which is due to close-lying 1n,π* and 1π,π* states, is shown to be absent in alcohol where the two states are sufficiently separated in energy.
Matrix Infrared Spectra and Density Functional Calculations of Manganese and Rhenium Carbonyl Neutral and Anion Complexes

Laser-ablated Mn and Re atoms and electrons react with CO upon co-condensation in excess argon and neon to produce carbonyl neutrals and anions. These species are identified through isotopic substitution, CCl4 doping to trap ablated electrons, and density functional theory isotopic frequency calculations. MnCO is identified at 1933.6 cm-1 in argon and at 1950.7 cm-1 in neon, which are in agreement with the gas phase 1955 ± 15 cm-1 photoelectron measurement. MnCO- is found at 1789.4 cm-1 in argon and 1807.5 cm-1 in neon. The Mn(CO)2 and Re(CO)2 dicarbonyls are major product absorptions. Annealing to allow further reaction of CO produces higher carbonyls including Mn2(CO)10 and Re2(CO)10 in solid argon. Argon and neon matrix experiments are compared for both metals.
Enhanced Bioremediation of Polycyclic Aromatic Hydrocarbons by Environmentally Friendly Techniques

Polycyclic aromatic hydrocarbons (PAHs) are recognized as a worldwide environmental contamination problem because of their intrinsic chemical stability, high resistance to various transformation processes, and toxicity property. Because of the wide distribution of the PAHs in the environment, human exposure to the PAHs is likely to occur from dermal contact, ingestion of particles, inhalation of airborne dust, or bioaccumulation in the food chains. Therefore, their remediation is considered indispensable for environmental clean up and human health. The objective of this article is to provide a quick review on toxicity of PAHs, biodegradation of PAHs, influence of selected environmental factors on PAHs biodegradation, selected techniques for enhancing biodegradation of PAHs, and a detailed description of two environmentally friendly techniques used in our laboratory for PAHs enhanced bioremediation. Finally, an overview on the green chemistry concept and its relevance to development of several environmental fingerprinting tools for predicting successful PAHs detoxification are discussed.
Numerical modeling of finned heat exchangers

Abstract A numerical investigation of annular finned tubes was performed using the computational fluid dynamics (CFD) software ANSYS FLUENT. The effects of fin spacing, fin height, fin thickness, and fin material on the overall heat transfer and pressure drop were determined for a single row of finned tubes in crossflow. As fin height (hf) increased, the predicted overall heat transfer increased. The magnitude of the increase in overall heat transfer was larger for smaller fin spacing (s). A similar trend was seen with the pressure drop – as the fin height increased the pressure drop increased with the magnitude of the increase being more significant for smaller fin spacings. For a fin spacing over tube diameter ratio of greater than one-third, the increase in pressure drop with fin height is very small. The effect of the fin thickness on heat transfer and pressure drop was much less significant than the fin spacing and fin height. Increasing the fin thickness showed minor increases in heat transfer and modest increases in pressure drop. While heat transfer also increased as the thermal conductivity of the material increased, the results showed relatively small differences in the heat transfer for plain carbon steel, aluminum, and copper. This is because the thermal resistance from convection became much larger than the thermal resistance from conduction in the fin. For s/hf > 1.5 the pressure drop remains relatively constant. On the other hand, the heat transfer shows a significant decrease as the ratio of s/hf goes from 1.5 to 6. This suggests that for the range of parameters used in the simulations, there is no value to designing a finned tube with s/hf > 1.5.
Weather Derivatives and Weather Risk Management

Weather derivatives are a relatively recent kind of financial product developed to manage weather risks, and currently the weather derivatives market is the fastest-growing derivative market. The development of weather derivatives represents one of the recent trends toward the convergence of insurance and finance. This article presents an overview of weather risks, weather derivatives, and the weather derivatives market, and examines the valuation of weather derivatives in an incomplete market, the hedging effectiveness of standardized weather derivatives, as well as optimal weather hedging with the consideration of basis risk and credit risk.
Optoelectronic Leak Detection System For Monitoring Subsea Structures

Leak detection and monitoring on subsea structures is an area of increasing interest for the detection and monitoring of production and control fluids for the oil and gas industry. Current techniques such as capacitive (dielectric) based measurement or passive acoustic systems have limitations and we report here an optoelectronic solution based upon fluorescence spectroscopy to provide a permanent monitoring solution. We report here a new class of optoelectronic subsea sensor for permanent, real time monitoring of hydrocarbon production systems. The system is capable of detecting small leaks of production or hydraulic fluid (ppm levels) over distances of 4-5 meters in a subsea environment. Ideally systems designed for such applications should be capable of working at depths of up to 3000m unattended for periods of 20+ years. The system uses advanced single emitter LED technology to meet the challenges of lifetime, power consumption, spatial coverage and delivery of a cost effective solution. The system is designed for permanent deployment on Christmas tree (XT), subsea processing systems (SPS) and associated equipment to provide enhanced leak detection capability.
Acute renal toxicity with combined use of amphotericin B and cyclosporine after marrow transplantation.

The role of cyclosporine alone or in combination with amphotericin B in the development of renal toxicity was evaluated in 47 marrow transplant recipients. Cyclosporine alone was given to 21 patients and 10 received cyclosporine plus amphotericin B. These were compared with 16 patients who received
EXTENDED SOURCE OF ENERGETIC COSMIC X RAYS

Cosmic X-ray source near direction of north galactic pole, noting empirical results from balloon observations
Structure-activity relationships of selective estrogen receptor modulators: modifications to the 2-arylbenzothiophene core of raloxifene

The 2-arylbenzothiophene raloxifene, 1, is a selective estrogen receptor modulator which is currently under clinical evaluation for the prevention and treatment of postmenopausal osteoporosis. A series of raloxifene analogs which contain modifications to the 2-arylbenzothiophene core have been prepared and evaluated for the ability to bind to the estrogen receptor and inhibit MCF-7 breast cancer cell proliferation in vitro. Their ability to function as tissue-selective estrogen agonists in vivo has been assayed in a short-term, ovariectomized (OVX) rat model with end points of serum cholesterol lowering, uterine weight gain, and uterine eosinophil peroxidase activity. These studies have demonstrated that (1) the 6-hydroxy and, to a lesser extent, the 4'-hydroxy substituents of raloxifene are important for receptor binding and in vitro activity, (2) small, highly electronegative 4'-substituents such as hydroxy, fluoro, and chloro are preferred both in vitro and in vivo, (3) increased steric bulk at the 4'-position leads to increased uterine stimulation in vivo, and (4) additional substitution of the 2-aryl moiety is tolerated while additional substitution at the 4-, 5-, or 7-position of the benzothiophene results in reduced biological activity. In addition, compounds in which the 2-aryl group is replaced by alkyl, cycloalkyl, and naphthyl substituents maintain a profile of in vitro and in vivo biological activity qualitatively similar to that of raloxifene. Several novel structural variants including 2-cyclohexyl, 2-naphthyl, and 6-carbomethoxy analogs also demonstrated efficacy in preventing bone loss in a chronic OVX rat model of postmenopausal osteopenia, at doses of 0.1-10 mg/kg.
Active dispersal of oribatid mites into young soils

Soil organisms contribute considerably to soil formation, fertility and microstructure of young soils. Oribatid mites as a part of the soil mesofauna are able to colonize young soils within a few years, but little is known about their dispersal pathways. In particular, the role of active dispersal during the colonization of young soils is almost unknown. The aims of the present study were (1) to determine the distance of active above-ground dispersal by oribatid mites in bare test plots with pure substrate using mini-pitfall traps in different distances to the source substrate (meadow), (2) to determine active below-ground movement using minicontainer traps in different distances to the meadow, (3) to calculate species-specific dispersal rates, and (4) to compare the contribution of wind-dispersal (investigated in a former study) as well as active above- and below-ground movement to the species assemblage dispersing into the bare plots. The results demonstrate that active migration occurs both above- as well as below-ground. From 31 species in the adjacent meadow, 17 immigrated into the bare test plots. The number of specimens and species actively moving above-ground significantly decreased with increasing distance along the bare substrate. Dispersal rates were species specific and varied between 0.3 and 2.1 cm/day. The number of specimens actively moving below-ground was low. However, relative to the low specimen number the number of species was high. Particularly members of the Suctobelbidae and Oppiidae actively moved into the bare plots below-ground. Dispersal mechanisms were found to be species specific, as about 32% of the registered species moved actively below-ground, 32% moved actively above-ground and about 26% combined active movement and passive wind-dispersal. In conclusion, active dispersal is an important dispersal mechanism in the colonization of young soils. However, several species combine different dispersal mechanisms, so that the number of possible dispersal pathways is one factor that determines specimen- and species-richness in a newly found habitat.
Timing and intensity of herbivory: Its influence on the performance of clonal woodland herbs

Herbaceous woodland species account for a significant amount of the biodiversity of temperate deciduous forests. A wide diversity of life-history strategies is known for woodland herbs, and several systems have been used to categorize the range of life-history characteristics. Clonal growth, one common feature of many woodland herbaceous species, provides several benefits including the ability to respond to disturbances by sharing resources among ramets. There is evidence that resource sharing is common among ramets of some species of woodland herbs but not others. Herbivory is a common form of disturbance among woodland herbs, but little is known about effects of the timing and intensity of herbivory. In this paper, we use an existing system of classification of life-history traits of clonal species to make predictions about how woodland herbs would respond to the timing and intensity of defoliation. Examples from a preliminary study in Maryland, USA, are used to demonstrate that the timing and intensity of herbivory can play an important role in determining patterns of future growth and resource allocation.
A structured introductory computer science course

A step-by-step presentation for the introductory computer science course which introduces the student to structured problem solving has been developed. By emphasizing the importance of “finding the pattern” and developing sequential algorithms from a top-down point of view, the students seem to have a better grasp on how to solve a problem, how to use a language, and how to apply what they have learned to later courses which use the computer.