cssi/SciSciGPT-SciSciNet huggingface dataset:
The PSU/UofC finite-element thermomechanical flowline model of ice-sheet evolution

Abstract Ice-sheet modeling to understand past changes and project future ones remains limited by uncertainties in key parameters as well as by shortage of computational resources. A fast two-dimensional dynamic/thermodynamic flowline ice-sheet model has been developed and benchmarked to complement three-dimensional models by allowing a more-thorough exploration of parameter space. A nonlinear Glen flow law with an exponent equal to 3 is assumed for ice. A diffusion formulation of the continuity equation for mass balance of ice sheets is employed. The ice-sheet model is coupled to an elastic lithosphere/relaxed asthenosphere isostatic bedrock model. Snow and superimposed ice thicknesses are determined using advective continuity equations. These thicknesses are then used in the parameterization of the surface accumulation and ablation rates under specified meteorological conditions constrained by ice- and ocean-core data. Heat-flow continuity is maintained by the time-dependent advection/diffusion equation in the ice and time-dependent diffusion equation in the underlying rock. We conduct the first benchmarking of which we are aware of a 2-D model against the European Ice-Sheet Modeling Initiative's (EISMINT) Level 2 and Level 3 intercomparison “Greenland” experiments. Appropriate behavior is simulated, with deviations from results of a three-dimensional model that are fully explainable as arising only from the change in dimensionality. Basal temperatures are quite accurate when compared to data and results from 3-D models.
Bernoulli numbers and trigonometric functions

In this survey article we develop some properties of the Bernoulli numbers and exhibit series expansions, for trigonometric and hyperbolic functions, whose coefficients are given in terms of these numbers. In particular, we present series expansion for the tangent, cotangent, cosecant and hyperbolic cotangent functions. As a consequence of these representations we obtain a formula for the sum of the series ?k 8= i(1/k2n ) for n = 1, 2 . . . . Hopefully the material of this paper will be useful in the teaching of many undergraduate courses.
Central neural stimulation of respiration by sodium salicylate.

Abstract Phernic nerve responses to intravenous administration of sodium salicylate were measured in anesthetized, paralyzed cats whose vagi and carotid sinus nerves had been cut. Three groups of animals were studied. One consisted of animals with intact central nervous systems. The other two were identical except that the spinal cords had been transected at either T 4 −T 5 or C 7 −T 1 . Salicylate led to a significant increase in respiration and whole body metabolism in all groups. Transection of the spinal cord had no effect on the magnitude of the respiratory response to salicylate. We also studied another group of animals in which salicylate was injected directly into the third cerebral ventricle. This led to a significant increase in respiration without an increase in whole body metabolism. We conclude that salicylate stimulates respiration by a mechanism other than one related to its ability to increase whole body metabolism and that this mechanism is located within the central nervous system.
Modular Design of Micropattern Geometry Achieves Combinatorial Enhancements in Cell Motility

Basic micropattern shapes, such as stripes and teardrops, affect individual facets of cell motility, such as migration speed and directional bias, respectively. Here, we test the idea that these individual effects on cell motility can be brought together to achieve multidimensional improvements in cell behavior through the modular reconstruction of the simpler “building block” micropatterns. While a modular design strategy is conceptually appealing, current evidence suggests that combining environmental cues, especially molecular cues, such as growth factors and matrix proteins, elicits a highly nonlinear, synergistic cell response. Here, we show that, unlike molecular cues, combining stripe and teardrop geometric cues into a hybrid, spear-shaped micropattern yields combinatorial benefits in cell speed, persistence, and directional bias. Furthermore, cell migration speed and persistence are enhanced in a predictable, additive manner on the modular spear-shaped design. Meanwhile, the spear micropattern als...
Central cord syndrome of cervical spinal cord injury: widespread changes in muscle recruitment studied by voluntary contractions and transcranial magnetic stimulation.

Muscle recruitment after central cord syndrome (CCS), a cervical spinal cord injury leading to a weaker motor function in the upper limbs versus the lower limbs, was examined in 14 individuals by means of voluntary muscle contractions and transcranial magnetic stimulation (TMS). Previously obtained data from able-bodied (AB) and non-CCS spinal cord injured subjects were used for comparison. Surface EMG was recorded from as many as six pairs of affected muscles. Individual muscle EMG activity was scored from 0 to 5. Cortical stimulation was applied while subjects maintained a weak contraction in each muscle. When CCS subjects attempted to produce a maximal voluntary contraction of an isolated muscle, this frequently resulted in cocontraction of nonsynergists in the same limb or/and in other limbs. Although the EMG scores in both upper and lower extremity muscles improved within postinjury time, in general, the lower extremity muscles, particularly the distal ones, demonstrated better recovery than the upper extremity muscles. CCS and AB subjects showed a similar high probability of "well-defined" responses to TMS (amplitude >150 microV) in all studied muscles. In contrast, latencies to TMS-evoked motor responses were prolonged by significant amounts after CCS. The delays in muscle responses were not significantly different from those observed in subjects with more severe cervical injury. Despite improvement in EMG scores, repeated measurements of TMS-evoked muscle response latencies in the same CCS subjects did not reveal significant shortening in central conduction latency. This argues against remyelination as an important contributor to the recovery process.
IL CIMITERO DI PRAGA: The Epistemic Implication between Lies and Reality:

This essay focuses on famous conspiracies and cunning forgeries contained in Umberto Eco's Il cimitero di Praga. Its purpose is to bring to the reader's attention the central function conspiracies and forgeries acquire in the entire work, and specifically in connection with the personal gains of the main protagonist, Simonini, and how his attitude in outwitting people, motivated by personal gains, exhibits a sort of Nietzschean will to power. In addition to the historical vicissitudes and the entertaining appeal comparable to a classic 19th century feuilleton novel, which the reader may effortlessly perceive at an ordinary level of reading, Eco uses conspiracies and forgeries to address a deep, epistemic problem staged between linguistic lies and reality. Il cimitero di Praga is a useful tool which makes the reader aware of this epistemic problem flowing between fiction and reality and how such a problem incapacitates the human ability to distinguish the one from the other. It is certainly not the remedy ...
General solution to the multiple-metallic-grooves scattering problem: the fast-polarization case.

The boundary value techniques in vector–field diffraction theories are generalized to describe electromagnetic scattering of plane waves by a finite number of parallel, rectangular grooves corrugated on a metallic (infinitely conducting) ground plane. Each of the grooves has its own feature size and location for representing a general grating structure in multilevel binary optics. The multiple-scattering matrix is derived for determining the scattering coefficients that lead to a fast convergence in the Bessel-function series representation of the scattered-field angular spectrum. The solution remains stable from the long-wavelength (the Rayleigh limit) to the short-wavelength region (the geometrical optics limit). It is found that any N-groove scattered field can be treated as the sum of N single-groove radiation fields and the cross-groove coupling fields. A coupling index is introduced to measure the coupling effect. Numerical examples of two, six, and twelve grooves are examined in different spectral regions. Plots of the coupling index are generated to show the feasibility of using pattern superposition for an approximate solution.
Fluctuation pressure on a bio-membrane confined within a parabolic potential well

A compliant bio-membrane with a nominally flat reference configuration is prone to random transverse deflections when placed in water, due primarily to the Brownian motion of the water molecules. On the average, these fluctuations result in a state of thermodynamic equilibrium between the entropic energy of the water and the total free energy of the membrane. When the membrane is in close proximity to a parallel surface, that surface restricts the fluctuations of the membrane which, in turn, results in an increase in its free energy. The amount of that increase depends on the degree of confinement, and the resulting gradient in free energy with degree of confinement implies the existence of a confining pressure. In the present study, we assume that the confinement is in the form of a continuous parabolic potential well resisting fluctuation. Analysis leads to a closed form expression for the mean pressure resulting from this confinement, and the results are discussed within the broader context of results in this area. In particular, the results provide insights into the roles of membrane stiffness, number of degrees of freedom in the model of the membrane and other system parameters.
Octaethylporphin films. II absorption and emission of amorphous films

Amorphous thin films of octaethylporphin have been prepared and are observed to crystallize over time if thicker than about 100 nm. Transmission spectra of amorphous films have a sharper Soret band than transmission spectra of crystalline films and lack the exciton band seen in crystalline films. The exciton band can be resolved in amorphous films by taking a difference spectrum between two amorphous films of different thickness. Fluorescence is observed from one impurity in amorphous films as compared to two impurities in crystalline films. This indicates a smaller exciton diffusion length in amorphous films as compared to crystalline films, consistent with the differences in the transmission spectra of the two kinds of film.
Effects of mestranol on blood pressure and norepinephrine in young normotensive and genetically hypertensive rats.

Abstract 1. Increases in blood pressure (B.P.) were found in 3-month-old normotensive and genetically hypertensive (GH) rats following administration of mestranol. 2. In normotensive rats a depletion in hypothalamic and adrenal NE accompanied the increase in B.P. which was found at the end of 3 weeks of drug treatment. 3. In GH rats, after an experimental period of 3 weeks, a decrease in cardiac NE occurred, while at the end of 6 weeks, a depletion in adrenal NE which was accompanied by the increase in B.P., was found.
Enhancing cancer screening in primary care: Rationale, design, analysis plan, and recruitment results

Colorectal cancer (CRC) is the third leading type of cancer and the third leading cause of cancer death in the United States. National policy-making organizations recognize and support a variety of CRC screening strategies among average-risk adults aged 50 and older based on strong evidence showing that screening decreases mortality from CRC and can also reduce the incidence of the disease. The goal of this study was to test a multi-level stepped intervention to increase CRC screening rates. We used a group-randomized trial design where the units of assignment were clinics and the units of observation were eligible patients receiving care at those clinics, with stratified random assignment of clinics to study conditions. The primary analysis was planned as a mixed-model logistic regression to account for the expected positive intraclass correlation associated with clinics. Our recruitment experience reflected the difficulties of conducting research in the real world where changes in economic conditions, staff turnover/layoff, inadequate medical records, and poor acceptance of research can significantly impact study plans. It demonstrated the problems that can emerge when procedures used in the study depart from those used in the pilot work to generate parameter estimates for power analysis. It also demonstrated the importance of allowing for attrition at the group and patient levels so that if recruitment falls short, it is possible to maintain adequate power with only a slight increase in the detectable difference. This experience should assist others planning group-randomized trials, whether in cancer screening or in other areas.
Imaging from the zero locations of far-field-intensity data

A new method is presented that allows the recovery of an image from those coordinates at which its power spectrum is zero. The coordinates of these zeros are points that are common to both the intensity data and the complex amplitude. The imaging method is based on a spectral estimation technique known as the prior discrete Fourier transform (PDFT, DFT using prior knowledge), which incorporates information about the image, such as a support constraint.
Abstract 1267: Metabolic sensor O-GlcNAc Transferase is a novel regulator of prostate cancer invasion and angiogenesis via regulation of FoxM1

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Cancer cells universally increase glucose and glutamine consumption, leading to the altered metabolic state known as the Warburg effect. One metabolic pathway highly dependent on glucose and glutamine is the Hexosamine Biosynthetic Pathway (HBP). Increased flux through the HBP leads to increases in the post-translational addition of O-linked-β-N-acetylglucosamine (O-GlcNAc) on a diverse population of nuclear and cytosolic proteins. A number of these target proteins are implicated in cancer, yet the role of O-GlcNAc modifications in cancer remains poorly defined. Here, we show that OGT is overexpressed in prostate cancer tissue compared to normal prostate epithelium and, that OGT protein and O-GlcNAc levels are elevated in prostate carcinoma cell lines compared to non-transformed prostate cells. Decreasing O-GlcNAc levels using OGT-targeted RNAi in the metastatic prostate cancer cell line PC3-ML inhibited growth in three-dimensional (3D) culture, as well as decreased colony formation in soft agar assays. Furthermore, decreasing O-GlcNAc levels was also associated with cell cycle arrest at G1 and increased expression of the CDK inhibitors p27 and p21. However, reducing O-GlcNAc levels in the non-tumorigenic prostate epithelial cell line RWPE-1 had minimal effects on growth in 3D culture. In addition to growth inhibition, reducing O-GlcNAcation in PC3-ML cells was associated with reduced expression of matrix metalloproteinase-2 (MMP-2), MMP-9 and vascular endothelial growth factor (VEGF), resulting in the inhibition of invasion and angiogenesis. OGT regulation of invasion and angiogenesis was dependent upon regulation of the oncogenic transcription factor FoxM1, as reducing OGT expression led to increased FoxM1 proteasomal degradation. Moreover, overexpression of a FoxM1 degradation-resistant mutant abrogated OGT RNAi inhibition of invasion, MMP levels, as well as angiogenesis and VEGF expression. Finally, the use of novel second-generation small molecule inhibitor of OGT led to the similar reduction in growth, invasion and inhibition of MMPs and VEGF levels. Current experiments are underway to test whether targeting OGT blocks prostate cancer metastasis. Altogether, these data suggest that as prostate cancer cells alter glucose and glutamine levels, O-GlcNAcation serves as nutrient sensitive modification contributing to oncogenesis and suggest that OGT is positioned as a novel target for therapeutic intervention for the treatment of human prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1267. doi:10.1158/1538-7445.AM2011-1267
The case for networked remote voting precincts

Voting in national elections from the comfort of one's home computer may never be practical or secure, but we argue that remote network voting can be both practical and secure. Provisional and postal absentee ballots, which trade some amount of anonymity for the ability to determine the eligibility of a distant voter, serve as a template for how electronic remote voting might proceed. We propose the "remote voting center": a government-operated facility located in embassies, consulates, and other remote areas where voters might normally need to vote by mail. Each remote voting center would maintain one or more electronic voting systems and a registration system. A voter presents identification to the registrar on site and is then directed to cast a ballot in a private electronic voting booth. The cast ballot is encrypted and forwarded to the registration system, where it is wrapped with the voter's identifying information. This double enclosure is signed by the voting center and posted publicly where it can be examined and canvassed by officials in the voter's home precinct. If and when the ballot is accepted, it can be combined with existing tallies using standard cryptographic techniques to preserve the voter's anonymity. The resulting system has privacy properties comparable to provisional voting in a local polling place, and represents an improvement over postal voting by offering the voter privacy in a supervised voting center.
Catalytic head-to-head alkyne dimerization to give Z-enynes.

Abstract The catalyst [Ir(biph)(PMe 3 ) 3 Cl] (biph = biphenyl-2,2′-diyl) gives head-to-head dimerization of 1-alkynes to the corresponding Z-enynes.
Oxygen Isotopic and Petrographic Evidence Relevant to the Origin of the Arkansas Novaculite

ABSTRACT O18 values for 73 chert samples from the Arkansas Novaculite (Devonian-Mississippian) range from + 17.8 to 33.7. Much of this variation is related to the effects of local metamorphism and isotopic impurities such as detrital quartz and clay minerals. Pure, unrecrystallized samples from the western outcrops in Oklahoma range from 30.3 to 33.7, whereas samples from Arkansas range from 25.1 to 29.7. As a group, west rn outcrops of the Novaculite are distinctly richer in O18. Petrographic and SEM examination of the O18-rich western samples reveal well preserved early diagenetic textures including abundant relict opal-CT lepispheres (now replaced by microquartz). Radiolaria and sponge spicules show well preserved morphologies. One western sample yielding the highest -value is microbrecciated, contains abundant dolomite rhombs and is laced with quartzine (length-slow chalcedony) suggesting silicification under evaporitic conditions. Samples from eastern localities display no evidence of early diagenetic textures, and radiolaria and sponge spicules are preserved only as petrographic ghosts. The isotopic and petrographic data can be interpreted in terms of a siliceous biogenic ooze deposited in environments ranging from supratidal to open marine. Shallow (platform?) deposition occurred in western areas with early silicification contributing to the preservation of diagenetic textures. Assuming that O18 of the diagenetic waters was within 1 of seawater the higher -values in the west reflect chert crystallization at isotopic temperatures of 20° to 29° C. The lower -values in the east suggest chert crystallization during deeper burial at isoto ic temperatures of 31° to 53° C, similar to burial diagenesis in Tertiary deep sea cherts.
Biological diversity conservation: A public policy perspective

While extinctions of individual species are part of a normal cycle, the current rate of extinctions should be a concern to us all. The maintenance of biological diversity is important for utilitarian reasons, quality of life considerations, and because biodiversity is important to sustainable regional economies. Single-species approaches are too limited to protect biodiversity at the landscape, habitat, and watershed levels. New approaches are necessary to deal with the complexity of biological diversity. The administration is using provisions in the Endangered Species Act to bring about broader multispecies habitat protection. The ecosystem approach provides a framework for ensuring that ecological considerations are taken into account, along with economic and social factors, and that all interested parties are able to participate in the decision-making process.
Primary systemic vasculitis in children in Estonia: a retrospective study from 2001-2010

Results 197 new cases of PSV were diagnosed during these years – HSP in 154, KD in 35, Churg-Staruss syndrome in 2, and polyarteritis nodosa in 3 cases, respectively. Wegener granulomatosis, microscopic polyangiitis and hypocomplementaemic urticarial vasculitis were all diagnosed in one patient. The age distribution ranged from 3 months to 16 years, in cases of KD – from 2 months to 13 years. 38% of all patients with HSP received short term corticosteroids. 91,4 % patients with KD received high dose intravenous immunoglobulin. Three children died during the follow up period (Wegener granulomatosis, polyarteritis nodosa, microscopic polyangiitis). Conclusions We determined the number of new cases of PSV within a hospital based population in Estonia. Despite the small population of Estonia we had the overall variety of PSV. HSP was the most common vasculitis, followed by KD. Other PSV were very rare in children in Estonia.
A report of fluorosis in the United States secondary to drinking well water

A 54-year-old female resident of Wellston, Okla, was found to have osteosclerosis on a routine chest roentgenogram. Subsequent investigation disclosed the cause of her osteosclerosis to be fluorosis secondary to the ingestion of well water containing 429 μmol/L of fluoride (recommended levels, 11 to 58 μmol/L). Water samples were also obtained from the 12 wells on properties adjacent to the index case. In three other wells, all at similar depths as the well of the index case, the fluoride concentration of the water was greater than 212 μmol/L. Urine samples from members of the four households who obtain their drinking water from these wells contained elevated urinary fluoride levels. Thus, fluorosis may develop in certain areas of the United States as a result of the natural occurrence of fluoride in the groundwater. Consequently, in known endemic areas, it would appear reasonable to measure the fluoride concentration of the well water at the time of drilling. (JAMA. 1991;265:486-488)
Relationship between the Clinical Performance Examination and Associated Variables.

��� ����*˘ � � � Purpose: The purpose of this study was to identify the causal relationship between the following variables: basic science score, written examination score (Internal medicine and Pediatrics), clinical clerkship score (Internal medicine and Pediatrics), and affective factors (self-efficacy, anxiety, and perception of preparedness). Methods: Forty-two medical students took the clinical performance examination (CPX) at the end of the first semester. One day before the CPX, the students completed a brief survey, which included 11 items that sampled their self-efficacy, preparedness and anxiety with regard to the CPX. The responses from the 38 identi fiable surveys (90%), out of 42, were analyzed for this study. Structural equation modeling techniques were used to test the relationships between the variables. The students' basic science scores, clinical clerkship scores, and written examination scores were considered for this study. Results: We found that self-efficacy influenced students' CPX scores indirectly through their preparedness and anxiety. Preparedness influenced students' CPX scores indirectly through their anxiety. Anxiety was predicated on self-efficacy directly or indirectly and it predicted CPX scores. The clinical clerkship scores affected the students' CPX scores indirectly. The written examination scores and basic science scores, however, did not impact the students' CPX scores directly or indirectly. The basic science scores, clinical clerkship scores, and written examination scores were not associated with self-efficacy. Conclusion: Our findings highlight the importance of clinical clerkship education and reasonable medical teaching methods in improving the student self-efficacy for the CPX.
Multi-band, multi-radio wireless LANs and PANs

Two trends are reshaping wireless personal area networks (WPANs) and wireless local area networks (WLANs). The first is the convergence of WPAN and WLAN functionality in mobile platforms; a single 802.11 radio will increasingly be used for both functions. The second is the availability of new unlicensed spectrum in the 60 GHz band and 600 MHz TV Whitespace band as well as new technology enhancing use of 5 GHz band. Radios that take advantage of this new spectrum and improved use of existing spectrum are being added to mobile platforms. This paper discusses these trends and looks at network and system architectures that take advantage of multi-band radios to provide increased connectivity and performance.
Alzheimer neurofibrillary change in subacute sclerosing panencephalitis

Abundant instances of Alzheimer neurofibrillary change (ANC) composed of tubules 200 nm wide and twisted into segments each 800 nm in length, indistinguishable from those of Alzheimer disease, were found in electron micrographs of the brain of a 15-year-old boy who died following subacute sclerosing panencephalitis (SSPE) of more than nine years' duration. The clinical picture was typical, CSF measles antibody titer was high, and there were characteristic electroencephalographic findings.
Management of the Patient with a Failed Renal Transplant

Summary The management of the failed renal transplant depends upon the clinical circumstances. In most instances of failure secondary to acute rejection or structural lesions, transplant nephrectomy is necessary. When failure is due to chronic rejection, grafts often can be left in place and removed only for the indications of fever, pain, swelling, infection, or refractory hypertension. Once dialysis has been reinstituted, immunosuppression should be tapered in accordance with standard principles; this often does not result in the need to remove the failed allograft so long as it is clinically quiet. The presence of a nonfunctioning graft does not preclude retransplantation. With the use of cyclosporine, the results of retransplantation are beginning to look similar to the statistics for first transplants. The quality of life in patients who have failed transplantation has not been definitely proven to be worse than that of patients on dialysis or those who have a functioning graft. However, patients with a failed transplant will need emotional support in their readjustment to dialysis.
New Species of Hypsilurus (Squamata: Agamidae) from Papua New Guinea

We describe a new species of agamid lizard of the genus Hypsilurus from northern Papua New Guinea. The new species is characterized by its small adult size, scalational features, small nuchal and dorsal crests, and distinctive dorsal color pattern of brown and white chevrons. It is a member of the H. godeffroyi species group, but otherwise, its closest relative is not obvious. The species is currently known from two of the outlying North Coast ranges, but following the pattern seen in several other species endemic to this region, it will likely prove to occur along much of the northern lowlands of New Guinea.
Daily heterosocial interactions of high and low socially anxious college students: A diary study*

Heterosocial anxiety has been assessed in a variety of ways, but little emphasis has been placed on collecting data in the person's social environment. The present study employed a behavioral diary to examine the daily heterosocial interactions of high- and low-socially-anxious students in the natural environment. Highanxious students participated in fewer interactions over a two-week period and reported higher anxiety, poorer performance, and less satisfaction with their performance than low-anxious students. Total and mean duration of interactions did not discriminate between groups, and subjects' sex made little difference. The impact of a variety of situational variables was also assessed. Issues regarding the use of heterosocial diaries for behavioral assessment are discussed.
Gastric mucosal biopsy via a nasogastric tube: a nonendoscopic method for diagnosing fundic and antral mucosal gastritis and Helicobacter pylori infection in man

Biopsy of the gastric mucosa is an integral part of a number of diagnostic and therapeutic gastroenterologic assessments. For example, biopsy of the gastric ant rum followed by urease testing or histologic examination is a sensitive method to detect Helicobacter pylori.1, 2 Histologic review of gastric mucosal biopsies is potentially useful in studies of other inflammatory gastric conditions and, possibly, in screening evaluations for gastric dysplasia. Gastric biopsy is also used in patients receiving long-term acid suppression with pro ton-pump inhibi tors to quan t i t a t e gastr ic mucosal endocr ine cell populations. 3, 4 Current ly , the most widely used me thod to obtain gastr ic mucosal biopsy specimens in h u m a n s is endoscopy. I f a mucosal lesion is present , biopsies wi th endoscopy m a y be directed toward the specific lesion. Endoscopy for the purpose of per forming r and o m mucosal biopsies :in a par t i cu la r region of the s tomach (e.g., fundic mucosa or an t ra l mucosa) is accurate , 5 bu t has a t least th ree d isadvantages . First , endoscopy requires in t ravenous sedation, wi th its potent ia l for r e sp i ra to ry depress ion and hypotension. 6 Second, endoscopy m a y lead to perfora t ion of the gut, a lbei t uncommonly. 6 Third, endoscopy is t ime-consuming and expensive, especially when one considers preprocedure p repara t ions and recovery room time. A less expensive, less t ime-consuming procedure t ha t does not requi re sedat ion might prove to be a more desirable a l te rna t ive to endoscopy for subjects in whom a r a n dom biopsy specimen from fundic or an t ra l mucosa is the sole objective. We therefore pos tu la ted t h a t mu-
Picosecond Studies of Primary Charge Separation in Bacterial Photosynthesis

With the aid of light and two coupled photosystems containing chlorophyll, green plants remove electrons from water, releasing O$\_{2}$, and convey them to CO$\_{2}$, reducing it to simple sugars and thence to carbohydrate. Photosynthetic bacteria operate more simply, employing a single photosystem. They reduce CO$_{2}$ but require substrates more easily oxidized than water, e.g. sulphide and succinate. Bacterial reaction centres free of the bulk chlorophyll that performs the light-harvesting function can be isolated. The reaction centre is the site where the electronic energy of the photoexcited molecule is converted to chemical potential. Thus bacterial reaction centres are ideal subjects for studying the details of this process by kinetic spectroscopy. Picosecond laser studies show that an electron is removed from the primary donor (a chlorophyll dimer) in 4 ps or less and transferred in several stages to the ubiquinone acceptor in ca. 200 ps. Remarkably, reverse electron transfer is several orders of magnitude slower. The paper discusses how Nature may have accomplished this.
Tunable dielectric constants and mechanical properties of PDMS and conducting polymer nanowire composites

A generic experimental procedure is presented in this work enabling the enhancement of the electrical responses of polydimethylsiloxane (PDMS) through incorporation of conducting polymer nanowires (CPNWs), while maintaining the desirable mechanical flexibility of PDMS. The dielectric constants of the composites are characterized by impedance measurements, and the effect of nanowire concentration is investigated by the percolation theory using a continuous hyperbolic tangent function. The viscoelastic properties of the composites are characterized by the stress relaxation nanoindentation tests, and the effect of nanowire concentration on the elastic modulus of composites is studied by the Wang-Pyrz model.
Cyclooxygenase-2 expression in esophageal epithelium before and after photodynamic therapy for Barrett’s esophagus with high-grade dysplasia or intramucosal carcinoma

Cyclooxygenase-2 expression is upregulated in Barrett’s esophagus and esophageal adenocarcinoma. Photodynamic therapy using porfimer sodium can result in ablation of dysplasia and intramucosal carcinoma, eradication of Barrett’s esophagus, and restitution of squamous epithelium. The aim of this study was to determine the effect of photodynamic therapy on cyclooxygenase-2 expression in esophageal epithelium. Paired pre- and post-photodynamic therapy biopsy samples from the same anatomical levels of 20 individuals who had undergone photodynamic therapy for Barrett’s esophagus with high-grade dysplasia and/or intramucosal carcinoma were immunostained using a cyclooxygenase-2 monoclonal antibody. Cyclooxygenase-2 expression was graded in squamous epithelium, Barrett’s esophagus, and neoplasia (if present) as follows: grade 0 (no staining), grade 1 (staining in 1–10% of cells), grade 2 (staining in 11–90% of cells), and grade 3 (staining in >90% of cells). Pre-photodynamic therapy median cyclooxygenase-2 expression was grade 2 (range 1–3) in neoplastic foci and grade 1 (range 1–3) in nondysplastic Barrett’s esophagus (P = 0.0009 for pairwise comparison). With the exception of a few cells staining in the basal epithelial layers, median cyclooxygenase-2 expression was graded as 0 (similar to controls) in both pre-photodynamic therapy squamous epithelium and post-photodynamic therapy neosquamous epithelium. This was significantly lower when compared to either neoplastic foci (P < 0.0001) or nondysplastic Barrett’s esophagus (P < 0.0001) pre-photodynamic therapy. Notably, in four patients with post-photodynamic therapy recurrent neoplasia, cyclooxygenase-2 expression returned to elevated levels. Cyclooxygenase-2 expression is elevated in Barrett’s esophagus with high-grade dysplasia or intramucosal carcinoma prior to photodynamic therapy. Following successful photodynamic therapy, cyclooxygenase-2 expression in neosquamous epithelium returns to a low baseline level similar to that observed in native esophageal squamous epithelium. Post-photodynamic therapy neoplastic recurrence is associated with elevated cyclooxygenase-2 expression. Prospective studies should determine whether cyclooxygenase inhibitors have a role as adjuvant therapy to prevent recurrence of Barrett’s esophagus following endoscopic therapy.
Reaction Versus Subsite Stereospecificity of Peptidylglycine α -Monooxygenase and Peptidylamidoglycolate Lyase, the Two Enzymes Involved in Peptide Amidation

Abstract Carboxyl-terminal amidation, a required post-translational modification for the bioactivation of many neuropeptides, entails sequential enzymatic action by peptidylglycine α-monooxygenase (PAM, EC 1.14.17.3) and peptidylamidoglycolate lyase (PGL, EC 4.3.2.5). The monooxygenase, PAM, first catalyzes conversion of a glycine-extended pro-peptide to the corresponding α-hydroxyglycine derivative, and the lyase, PGL, then catalyzes breakdown of this α-hydroxyglycine derivative to the amidated peptide plus glyoxylate. We have previously established that PAM and PGL exhibit tandem reaction stereospecificities, with PAM producing, and PGL being reactive toward, only α-hydroxyglycine derivatives of absolute configuration (S). We now demonstrate that PAM and PGL exhibit dramatically different subsite stereospecificities toward the residue at the penultimate position (the P2 residue) in both substrates and inhibitors. Incubation of Ac-L-Phe-Gly, Ac-L-Phe-L-Phe-Gly, or (S)-O-Ac-mandelyl-Gly with PAM results in complete conversion of these substrates to the corresponding α-hydroxylated products, whereas the corresponding X-D-Phe-Gly compounds undergo conversions of <1%. The KI of Ac-D-Phe-Gly is at least 700-fold higher than that of Ac-L-Phe-Gly, and the same pattern holds for other substrate stereoisomers. This S2 subsite stereospecificity of PAM also holds for competitive inhibitors; thus, the KI of 45 μM for Ac-L-Phe-OCH2CO2H increases to 2,247 μM for the -D-Phe- enantiomer. In contrast, incubation of PGL with Ac-L-Phe-α-hydroxy-Gly, Ac-D-Phe-α-hydroxy-Gly, (S)-O-Ac-mandelyl-α-hydroxy-Gly, or (R)-O-Ac-mandelyl-α-hydroxy-Gly results in facile enzymatic conversion of each of these compounds to their corresponding amide products. The simultaneous expression of high reaction stereospecificity and low S2subsite stereospecificity in the course of PGL catalysis was illustrated by a series of experiments in which enzymatic conversion of the diastereomers of Ac-L-Phe-α-hydroxy-Gly and Ac-D-Phe-α-hydroxy-Gly was monitored directly by HPLC. Kinetic parameters were determined for both substrates and potent competitive inhibitors of PGL, and the results confirm that, in sharp contrast to PAM, the configuration of the chiral moiety at the P2 position has virtually no effect on binding or catalysis. These results illustrate a case where catalytic domains, which must function sequentially (and with tandem reaction stereochemistry) in a given metabolic process, nevertheless exhibit sharply contrasting subsite stereospecificities toward the binding of substrates and inhibitors.
Teacher placement, mobility, and occupational choices after teaching

Teachers’ initial placement has important implications for student achievement and the distribution of teachers among schools. This paper combines data from a US Baccalaureate and Beyond longitudinal study with school and school district information from the Common Core of Data to study the effects of initial school placement on teacher mobility. Multinomial logit hazard analysis shows that higher salaries may help retain teachers in the field and improved working conditions may help reduce teacher mobility within the profession. Teachers who change careers do not necessarily earn higher salaries; the occupation choice affects earnings in the new job.
Patient comprehension of doctor-patient communication on discharge from the emergency department

An exit interview was conducted during March, 1994 on 314 patients treated and released from the Emergency Department at Kern Medical Center in Bakersfield, California. The questionnaire was designed to assess understanding of diagnosis, prescribed medications, additional instructions, and plans for follow-up care. The patients' own perceptions of the adequacy of communication and whom they considered the most important source of information were also determined. Overall, patients correctly identified 59% of their instructions. The performance of the English speaking and the Spanish speaking patients was compared. Spanish speaking patients scored significantly lower on all questions. The physician was identified by most patients (63.8%) as the source of the most information.
Treatment of onychomycosis using a submillisecond 1064-nm neodymium:yttrium-aluminum-garnet laser

Background Laser treatment has emerged as a novel treatment modality for onychomycosis. Objective We sought to determine thermal response and optical effects of a submillisecond neodymium:yttrium-aluminum-garnet (Nd:YAG) 1064-nm laser on common fungal nail pathogens, and the clinical efficacy and safety of the Nd:YAG 1064-nm laser on onychomycotic toenails. Methods A 4-part in vitro and in vivo study was conducted using a Nd:YAG 1064-nm laser. The first portion evaluated 3 different nail pathogens in suspension at 7 heat and time exposures. The second and third parts of the study irradiated pure fungal colonies. The final portion involved an in vivo treatment of toenails over 5 treatment sessions. Results A fungicidal effect for Trichophyton rubrum was seen at 50°C after 15 minutes, and for Epidermophyton floccosum at 50°C after 10 minutes. Limited growth of Scytalidium was seen at 55°C after 5 minutes. No inhibition was observed after laser treatment of fungal colonies or suspensions. In vivo treatment of toenails showed no improvement in Onychomycosis Severity Index score. Limitations The Nd:YAG 1064-nm laser was the only laser tested. Conclusions Laser treatment of onychomycosis was not related to thermal damage or direct laser effects. In vivo treatment did not result in onychomycosis cure.
On the Neggers-Stanley conjecture and the Eulerian polynomials

Abstract We prove combinatorially that theW-polynomials of naturally labeled graded posets of rank 1 or 2 (an antichain has rank 0) are unimodal, thus providing further supporting evidence for the Neggers–Stanley conjecture. For such posets we also obtain a combinatorial proof that theW-polynomials are symmetric. Combinatorial proofs that the Eulerian polynomials are log-concave and unimodal are given and we construct a simplicial complexΔwith the property that the Hilbert function of the exterior algebra modulo the Stanley–Reisner ideal ofΔis the sequence of Eulerian numbers, thus providing a combinatorial proof of a result of Brenti.
Minimal Dirac Fermionic Dark Matter with Nonzero Magnetic Dipole Moment

Abstract A neutral Dirac fermion ψ with a nonzero magnetic dipole moment is supplied as a singlet within the context of the standard model and is considered as a dark matter candidate near the electroweak scale ( 10 – 1000 GeV ). We discuss its dynamics with the ordinary matters through the magnetic dipole moment. The magnetic dipole moment constrained by the relic abundance may be as large as 10 − 18 – 10 − 17 e ⋅ cm . We show that the elastic scattering is due to a spin–spin interaction for the direct detections and the predictions are under experimental exclusion limits of the current direct detectors, XENON10 and CDMS II, and consider the possibility of dark matter detection in the future.
1380 RETINOPATHY OF PREMATURITY: FLUORESCEIN ANGIOGRAPHIC AND HISTOPATHOLOGIC STUDIES ON INFANTS RECEIVING HIGH AND LOW DOSES OF VITAMIN E

1380 RETINOPATHY OF PREMATURITY: FLUORESCEIN ANGIOGRAPHIC AND HISTOPATHOLOGIC STUDIES ON INFANTS RECEIVING HIGH AND LOW DOSES OF VITAMIN E
Optimal search algorithm for extrema of a discrete periodic bimodal function

Abstract This paper describes an optimal algorithm for searching for a minimum (or a maximum) of a discrete periodic bimodal function of period P. Recursive computing is used to prove the optimality of the search algorithm. An application of the algorithm for a clustering analysis of a data communication network is provided.
Pathophysiology of anorectal dysfunction.

Anorectal dysfunction is common among women. The onset is typically following childbirth and increases with aging. Frequently, women are too embarrassed by their symptoms to bring them to the attention of their health care providers, or if they choose to discuss the problem, they may encounter disinterest from the physician owing to inadequate understanding of diagnostic and therapeutic options. This article reviews the pathophysiology of the most common anorectal disorders affecting women. Diagnosis and treatment of these problems are covered elsewhere in this issue.
ACTH release evoked by electrical stimulation of brain stem and limbic system sites in the cat: The absence of ACTH release upon infundibular area stimulation.

Tissue in different parts of the brain stem and limbic system was electrically stimulated by the passage of electric current through electrodes implanted in the amygdala, hypothalamus, midbrain or medulla oblongata while plasma samples were collected for bioassay of ACTH concentration. The electrode placements were chosen so as to pass the stimulating currents through tissue in which reside neural structures implicated in control of ACTH release. Following stimulation of these structures, 3 different patterns of changes in plasma ACTH concentration occurred. Plasma ACTH levels rose promptly after stimulation at sites in the amygdaloid septal complex matching the rapidity of the response to hemorrhage or sciatic nerve stimulation. In contrast, after stimulation at sites in the medullary reticular formation, medial midbrain structures, lemniscal systems, or posterior lateral hypothalamus, the rise in plasma ACTH concentration was consistently delayed for 5–10 min, providing the basis for the suggestion that...
Eating bone or adding it : the Wnt pathway decides

An inhibitor of the Wnt signaling pathway mediates bone destruction in inflammatory arthritis. The inhibitor may be the key to understanding why in some joint diseases bone is destroyed and in others built up (pages 156–163).
Silicon micromirrors and their prospective application in the Next-Generation Space Telescope

This paper describes a potential application of silicon surface micromachined (SMM) mirrors to a space imaging application. We have developed micromirror arrays that can be individually addressed for potential use in a spectrometer planned for NASA's Next Generation Space Telescope (NGST), which will be launched later this decade. An array of micromirrors has been designed to replace a conventional fixed slit mask that is commonly used in spectrometer instruments. The fixed slit mask is used to select the desired portions of an incoming optical signal for analysis. These mirrors are designed to operate in two states, on and off, with the on position directing the signal into the instrument. Such an array of micromirrors can then be used as a "programmable" slit mask where portions of the incoming field of view can be selected in software.
Assessment of ensemble-based chemical data assimilation in an idealized setting

Abstract Data assimilation is the process of integrating observational data and model predictions to obtain an optimal representation of the state of the atmosphere. As more chemical observations in the troposphere are becoming available, chemical data assimilation is expected to play an essential role in air quality forecasting, similar to the role it has in numerical weather prediction (NWP). Considerable progress has been made recently in the development of variational tools for chemical data assimilation. In this paper, we assess the performance of the ensemble Kalman filter (EnKF). Results in an idealized setting show that EnKF is promising for chemical data assimilation.
The third law in Newton’s Waste book (or, the road less taken to the second law)

Abstract On the basis of evidence drawn from the Waste book, Westfall and Nicholas have argued that Newton arrived at his second law of motion by reflecting on the implications of the first law. I analyze another argument in the Waste book which reveals that Newton also arrived at the second law by another very different route. On this route, it is the consideration of the third law and the principle of conservation of motion—and not the first law—that prompts Newton to formulate the second law. The existence of these two routes is significant because each employs a distinct kind of reasoning about forces. Whereas the Nicholas–Westfall route via the principle of inertia bears the mark of Descartes’s influence, the alternative route proceeds from the action–reaction principle, which is widely regarded as an original Newtonian contribution to mechanics. In the course of exploring this alternate route to the second law, the origins and justification of the third law are examined.