cssi/SciSciGPT-SciSciNet huggingface dataset:
cis-Tetra­kis(μ-N-phenyl­acetamidato)-κ4N:O;κ4O:N-bis­[(benzo­nitrile-κN)rhodium(II)](Rh—Rh)

The complex molecule of the title compound, [Rh2{N(C6H5)COCH3}4(C6H5CN)2], exhibits crystallographically imposed centrosymmetry. The four acetamide ligands bridging the dirhodium core are arranged in a 2,2-cis manner, with two N atoms and two O atoms coordinating to the unique RhII atom cis to one another. The Neq—Rh—Rh—Oeq torsion angles on the acetamide bridges vary between 1.62 (4) and 1.78 (4)°. The Rh—Rh bond length is 2.4319 (3) A. The axial nitrile ligand completes the distorted octahedral coordination sphere and shows a non-linear coordination with an Rh—N—C bond angle of 167.14 (15)°, while the N—C bond length is 1.135 (3) A.
Scattering and internal fields of a microsphere that contains a saturable absorber: finite-difference time-domain simulations

Illumination intensities that are used to induce scattering and fluorescence in aerosols can be large enough to cause variations in the refractive index. Methods used to calculate the scattering from homogeneous particles may not be valid for these systems. We use the finite-difference time-domain method and an iterative technique to model scattering by microspheres that contain a saturable absorber. We illustrate this technique by calculating the scattering from spheres that contain tryptophan. We show the Mueller scattering matrices along with the internal intensity distributions for different incident intensities. The backscattering increases as the illumination intensity becomes large enough to saturate the absorption in regions of the sphere.
The cystic fibrosis therapeutics development network (CF TDN): a paradigm of a clinical trials network for genetic and orphan diseases

Clinical trials have become critical to the advancement of medical science and to the evolution of patient care in medicine. The science of clinical research has advanced from early studies in which treatment was assessed without controls to sophisticated multinational collaborative randomized, double-blind, placebo controlled trials of therapeutic interventions. To facilitate the advancement of clinical research, clinical trials networks have been developed to conduct multicenter studies. This review describes the history of clinical trials, clinical trials networks, and the goals of such networks in the United States. The Cystic Fibrosis Therapeutics Development Network, a network that represents the paradigm for genetic and orphan diseases, is described in detail. This network has been extremely successful in its first 3.5 years of existence conducting 18 different clinical trials in patients with Cystic Fibrosis. Unique aspects of the network include the use of internet applications for study conduct and communication, the development of statistical methodology to enhance the efficiency of clinical trial design, the development of outcome measures specific to Cystic Fibrosis, and the development of infrastructure necessary for expediting protocol development. In the current environment, clinical research faces significant challenges related to ensuring the safe and ethical conduct of clinical research while promoting fast and efficient clinical trials. To succeed and move forward to provide treatments and find cures for diseases, clinical trials networks must continue to evolve. The Cystic Fibrosis Therapeutics Development Network represents a network that has met this challenge and will continue to provide a venue for the safe and efficient conduct of clinical trials in Cystic Fibrosis.
Electrodeposition of Au-Cd alloy nanostructures on Au(111).

This report concerns an in-situ scanning tunneling microscopy study of the initial stages in the formation of a Au−Cd alloy on the Au(111) herringbone reconstruction. Although Au−Cd nanoclusters of alloy have been observed in sulfate electrolyte by this group, alloy “nanowires” were observed to form preferentially in the hcp regions between the sets of “soliton” walls of the reconstruction only in the presence of chloride. The nanowires were formed at −0.55 V versus 3 M Ag/AgCl, corresponding to Cd underpotential deposition (upd). Upd is electrodeposition at a potential prior to that needed to deposit the bulk element.
Peripheral blood mononuclear cells from AIDS patients release but do not respond to antigen-stimulated NK-activating lymphokines.

We have previously shown that streptococcal product (SP) extracted from the culture supernatants of Streptococcus pyogenes ATCC 19615 augments NK activity, partly by inducing the release of soluble factors from mononuclear cells. In this study we use SP as an NK stimulant to investigate the mechanism of NK depression in AIDS. We demonstrate that the NK activity of AIDS patients is lower than normal controls and can be significantly enhanced with SP, although not to control levels. The decreased cytotoxicity in AIDS is not due to a depletion of NK cells, nor to the depletion of lymphokines from CD4 cells that are directly involved in NK cell activation. PBMCs from patients with AIDS respond to SP, producing normal levels of NK-en-hancing substances in their supernatants. However, upon examining the ability of SP-induced supernatants from control cells to augment the NK activity of cells from AIDS patients, we find significantly less activity in AIDS cells than in control cells, suggesting an intrinsic effector dysfunction of NK cells in AIDS.
The effect of interferon-beta on mouse neural progenitor cell survival and differentiation.

Interferon-β (IFN-β) is a mainstay therapy for relapse-remitting multiple sclerosis (MS). However, the direct effects of IFN-β on the central nervous system (CNS) are not well understood. To determine whether IFN-β has direct neuroprotective effects on CNS cells, we treated adult mouse neural progenitor cells (NPCs) in vitro with IFN-β and examined the effects on proliferation, apoptosis, and differentiation. We found that mouse NPCs express high levels of IFNα/β receptor (IFNAR). In response to IFN-β treatment, no effect was observed on differentiation or proliferation. However, IFN-β treated mouse NPCs demonstrated decreased apoptosis upon growth factor withdrawal. Pathway-specific polymerase chain reaction (PCR) arrays demonstrated that IFN-β treatment upregulated the STAT 1 and 2 signaling pathway, as well as GFRA2, NOD1, Caspases 1 and 12, and TNFSF10. These results suggest that IFN-β can directly affect NPC survival, possibly playing a neuroprotective role in the CNS by modulating neurotrophic factors.
The formation of ultrafine ion H2O— H2SO4 aerosol particles through ion-induced nucleation process in the stratosphere

Abstract In this theory, we have demonstrated that ultrafine (angstrom size) prenucleation ion clusters comprise a segment of the overall nucleation size spectrum in the stratosphere. Also, the ion clusters exist in a spectrum attributable to certain favorable physical states. The distribution changes when the temperature and ambient water and sulfuric acid vapor pressures vary with altitude. Around 18 km, the spectrum of prenucleation embryo radii are in the range of 6.3 to 7.2 A. It is also observed that the average radius of the ion cluster spectrum decreases with altitude, while the weight percentage of sulfuric acid in the average ion cluster increases with altitude. A profile for the ion cluster spectrum and its variation with altitude is constructed. Under stratospheric conditions, growth to large aerosols by nucleation is negligible. A comparison of the characteristic interaction time for an ion-molecule reaction with that of an ion annihilation and recombination shows that ion nucleation is the favored process in forming ultrafine background aerosols. So prenucleation ion clusters will take the place of primary ions as the main participant in the ion recombination, ion annihilation, coagulation and condensation processes.
The Ca2+–calmodulin-dependent protein kinase cascade

The Ca2+-calmodulin-dependent protein kinase (CaM kinase) cascade includes three kinases: CaM-kinase kinase (CaMKK); and the CaM kinases CaMKI and CaMKIV, which are phosphorylated and activated by CaMKK. Members of this cascade respond to elevation of intracellular Ca2+ levels and are particularly abundant in brain and in T cells. CaMKK and CaMKIV localize both to the nucleus and to the cytoplasm, whereas CaMKI is only cytosolic. Nuclear CaMKIV regulates transcription through phosphorylation of several transcription factors, including CREB. In the cytoplasm, there is extensive cross-talk between CaMKK, CaMKIV and other signaling cascades, including those that involve the cAMP-dependent kinase (PKA), MAP kinases and protein kinase B (PKB; also known as Akt). Activation of PKB by CaMKK appears to be important in protection of neurons from programmed cell death during development.
Sarcoma of bone and soft tissue following treatment of Hodgkin's disease

Intensive chemotherapy and radiotherapy of Hodgkin's Disease has resulted in improved survival rates. With long-term follow-up, however, a risk of secondary malignancy in these individuals is now appreciated. The authors of this report have encountered five patients who developed bone or soft tissue sarcomata more than 5 years after treatment of Hodgkin's Disease. The four males and one female ranged in age from 14 to 74 years at the time of diagnosis of Hodgkin's disease. Two had received radiotherapy alone for treatment of Hodgkin's disease, two were treated with radiation and chemotherapy, and one received only chemotherapy. The latent period prior to diagnosis of sarcoma ranged from 6 to 11 years. There was one case each of neurofibrosarcoma, fibrosarcoma, osteosarcoma, liposarcoma and leiomyosarcoma. Four patients died within 1 year of the diagnosis of sarcoma. One is alive with no evidence of disease 2 years following diagnosis and surgical excision of the sarcoma. On the basis of the Massachusetts General Hospital experience in the treatment of Hodgkin's Disease, the authors calculate a risk of 0.9% of sarcoma occurring in five year survivors of Hodgkin's disease. Previously reported cases of sarcoma following treatment of Hodgkin's disease are summarized. The pertinent literature is reviewed.
Thermal and spectral studies of some divalent metal chelates of 2,4-dinitroso-1,3-naphthalenediol

Abstract The thermal and spectral properties of the chelates of 2,4-dinitroso-1,3-naphthalenediol with copper, cobalt, nickel, and zinc have been investigated. The decreasing order of thermal stability for the metal chelates in Ni > Co ≈ Zn > Cu. With the exception of the copper chelate, which exploded, the chelates decomposed slowly. They are compared to the corresponding chelates of 2,4-dinitrosoresorcinol.
Barriers to information technology in Latin America and the Caribbean: some options

Jorge Sabato, the Latin American scientist, predicted that ‘either Latin America dominates technology or through other countries technology will dominate Latin America’ (Sagasti 1984). This prediction might serve to point toward one of the objectives to challenge our countries of the Caribbean and Latin America in the coming century. To understand how hard we will have to work to achieve that goal we might look at the barriers to information technology in Latin America and the Caribbean.
Image acquisition and real-time processing in region-of-interest fluoroscopy with variation of source-to-image distance

An automatic ROI tracking system for the application of ROI fluoroscopy is designed. The methods for processing in real- time, generating binary masks, equalization of the display and the scheme for the image analysis to track ROI size are described. The initial results of the system tested on a torso phantom are reported and discussed. The system results in the appearance of an almost completely equalized real-time image and the method can be incorporated into x-ray fluoroscopy units with minimum modification. With the technology, ROI fluoroscopy can be applied to interventional or diagnostic procedures for practical patient dose reduction.
Phosphorus nutrition of White Rose potato in relation to growth and minerals of leaf and root tissues.

Abstract White Rose potato plants (Solanum tuberosum, L.) were grown outdoors, without tuber formation, in a modified Hoagland's nutrient solution with 9 treatments of KH2PO4 ranging from 0 to 4.0 mmoles per liter. Deficiency symptoms ranged from very severe to none at harvest after 27 days of growth. Growth of the potato plants increased with increased P supply and was associated with an increased P content of the plant tissues. The critical H2PO4‐P concentration at a 10% reduction of top growth, based on a second leaf analysis, was about 1,000 ppm for the petiole and terminal bladelet and about 1,200 ppm for the lateral bladelet, dry weight basis. Phosphorus nutrition had only a slight effect on the K, Na, Mg and NO3‐N concentrations of the root tissues but Ca increased as phosphate increased which suggests a calcium phosphate precipitation. Phosphorus stress lowered the K, Na, Ca, Mg and NO3‐N concentrations of the petiole tissues of the recently matured leaf which suggests that P increases salt accumu...
Interaction of α-adrenergic imidazolines with cardiac histamine H2-receptors

Abstract We have investigated in the isolated, perfused guinea pig heart whether the α-adrenergic imidazolines, tolazoline and tetrahydrozoline stimulate histamine H 2 -receptors directly or via the release of endogenous histamine. At 30°C neither tolazoline nor tetrahydrozoline released histamine. However, both increased heart rate, contractility, and decreased coronary vascular resistance as a function of dose. The H 2 -receptor antagonists cimetidine and tiotidine blocked the effects of tolazoline and tetrahydrozoline. The actions of tetrahydrozoline were confined to its l-isomer. At 37°C tolazoline, but not tetrahydrozoline, released histamine into the coronary perfusate. The maximum tolazoline-induced change in heart rate was 2.5–3.0 times greater than tetrahydrozoline's, in distinct contrast to their identical effect at 30°C. All other responses to the two drugs were the same at 30 and 37°C. Our results suggest that tolazoline and tetrahydrozoline directly stimulate histamine H 2 -receptors. Because of the differences in the structures of imidazolines and histamine, these findings have implications for the current hypothesis regarding histamine H 2 -receptor activation.
Automated test generation for engineering applications

In test generation based on model-checking, white-box test criteria are represented as trap conditions written in a temporal logic. A model checker is used to refute trap conditions with counter-examples. From a feasible counter-example test inputs are then generated. The major problems of applying this approach to engineering applications derive from the fact that engineering programs have an infinite state space and non-linear numerical computations. Our solution is to combine predicate abstraction (which reduces the state space) with a numerical decision procedure (which supports predicate abstraction by solving non-linear constraints) based on interval analysis. We have developed a prototype and applied it to MC/DC (Modified Condition/Decision Coverage) test case generation. We have used the prototype on a number of C modules taken from a conflict detection and avoidance system and from a Boeing 737 autopilot simulator. The modules range from tens of lines up to thousands of lines in size. Our experience shows that although in theory the inclusion of a decision procedure for non-linear arithmetic may lead to non-terminating behavior and false positives (as abstraction-based model checking already does), our prototype is able to automatically produce feasible counterexamples with only a few exceptions. Furthermore, the process runs with acceptable execution times, without requiring any other knowledge of the specification, and without tampering with the original C programs.
Thermochemistry of Gaseous Ethylsilanes and Their Radical Cations

The dissociation behavior of energy-selected tetraethylsilane, triethylsilane, and diethylsilane photocations is studied using the threshold photoelectron-photoion coincidence (TPEPICO) technique. In the 8–12. 5 eV photon energy range, 0 K dissociation onsets have been measured from the TPEPICO data. The dissociation channels observed include loss of ethane, hydrogen molecule, ethyl radical and hydrogen atom, depending upon the molecular ion under investigation. The thermochemistry of the molecular ions and dissociation fragments is obtained by an analysis that takes into account the kinetics and internal energy distributions of the ions. The various dissociation onsets permit the reevaluation of both neutral and ionic silane thermochemistry. We observed 298-K ethyl group values of 60±10 and 94±10 kJ mol−1 for neutral and ionic silanes, respectively. These values are considerably smaller than the previously reported values of 86 and 130 kJ mol−1, respectively. Finally, a Δ f H ∘ (298 K) of −141.5 ± 21 kJ/mol for neutral diethyl silane is derived from the dissociative ionization onset of diethylsilane.
What systems thinking can learn from history

A new concept of history would enable members of the systems community to reflect on two closely linked issues: teleology and a way of reasoning which arises out of it. In other words, by rethinking the role of a concept of history we will be able to grasp a sense of cultural purpose for a system or an organization and, next, be led into a way of reasoning which will direct the collective mind of such a system or organization as a whole.
Left Ventricular Dyssynchrony Assessment Using Myocardial Single-Photon Emission CT

Myocardial SPECT using standard procedure for perfusion imaging and phase analysis is a novel approach to left ventricular dyssynchrony assessment. Preliminary data suggest excellent repeatability and potential utility for guiding cardiac resynchronization therapy and elucidating mechanisms.
Representation space in a network of coupled chaotic oscillators with modulated synchronization

Abstract Statistics over an ensemble of chaotic oscillators are used to perform recognition among a set of 3-D paperclip objects. The homogeneous local connections resemble cortical column structure, while dynamic aspects such as temporal coding, fluctuating correlations, and population coding accord with recent physiological observations. The coupled map formalism targets mesoscopic dynamics, of units consisting of mixed excitatory–inhibitory populations. This paper focuses on aspects of the representation space. Multidimensional scaling reveals the clustering of objects in the representation space, and distortions of the clustering resulting from small shifts in one of the dynamical parameters of each recognizer are examined.
Operator theoretic invariants and the enumeration theory of Pólya and de Bruijn

Abstract It has been shown by M. Marcus and others that, in regard to combinatorial matrix functions and combinatorial inequalities, it is frequently fruitful to pass immediately from the consideration of permutations to the consideration of their tensor representations. Such an approach embeds the combinatorial arguments into the framework of linear algebra and frequently results in deeper theorems. It is interesting to note that certain basic combinatorial identities concerned with pattern enumeration and combinatorial generating functions can also be put into this framework. In this paper we consider one possible way of doing this.
Improving Information Exchange between the AGS and Its Experimenters

The increasing number of concurrently operating experiments and our expanding experimental areas are creating a need for more effective communications between the AGS and its users. Effective operation of a large accelerator complex such as the AGS requires the enthusiastic cooperation of all its support and experimental groups. In an effort to provide these groups with both instantaneous and long term machine information, we use area display boards, public address announcements, telephone communications and scheduling meetings. To complement these systems, a visual information network has been devised which provides machine status, performance data and scheduling information through the use of a closed circuit television system. The experimental groups on their part provide coded operational status information to the Main Control Room where it is processed and displayed. The chronological status of the AGS machine and of each of the experimental groups is recorded by a computer which periodically scans and records this information so that it may be analyzed and presented on command.
Transcriptional and posttranscriptional roles for p38 mitogen-activated protein kinase in upregulation of TNF-α expression by deoxynivalenol (vomitoxin)

Abstract Deoxynivalenol (DON, vomitoxin) is a trichothecene mycotoxin that potentially mediates toxicity by upregulating proinflammatory cytokine gene expression in vitro and in vivo. The purpose of this study was to test the hypothesis that DON-induced activation of mitogen-activated protein kinases (MAPKs) mediates transcriptional and posttranscriptional upregulation of TNF-α gene expression. RNAse protection assay revealed that DON at 100 to 500 ng/ml induced mRNA expression of TNF-α as well as IL-6, IFN-γ, TGFβ-1, and TGFβ-3 and that these effects were potentiated by 100 ng/ml lipopolysaccharide (LPS). DON was found to induce phosphorylation of p38 kinase, extracellular signal-regulated kinases (ERKs), and c-Jun amino terminal kinases (JNKs) in a dose-dependent manner in the RAW 264.7 murine macrophage model. A luciferase reporter gene driven by the murine TNF-α promoter was used to assess the role of various MAPKs on DON upregulation of TNF-α gene transcription. The p38 inhibitor SB203580 reduced induction of luciferase activity by DON, LPS, and DON + LPS. In addition, the ERK inhibitor PD 98059 blocked DON- and DON + LPS-induced luciferase activity whereas the JNK inhibitor impaired LPS- and DON + LPS-induced luciferase activity. To study the effects of MAPKs on DON-induced TNF-α mRNA stability, an asynchronous model was used whereby cells were pretreated with LPS for 4 h and the medium was removed. Following incubation with medium containing a transcription inhibitor, 5,6-dichloro-β- d -ribofuranosyl-benzimidazole, MAPK inhibitors and/or DON (250 ng/ml) cultures were monitored for TNF-α mRNA expression. DON-induced TNF-α mRNA stabilization was abrogated in the presence of SB 203580, whereas the stabilization by DON was not affected by PD 98059 or SP 600125. To verify the role of MAPKs in DON + LPS-induced TNF-α production, cells were incubated with LPS, DON, or LPS + DON for 18 h in the presence of inhibitors. ELISA of supernatant indicated that induction of TNF-α production by DON alone was significantly reduced by SB 203580 and PD 98059, whereas all three inhibitors blocked LPS- and DON + LPS-induced TNF-α production. Taken together, these results suggest that relative to DON-induced TNF-α mRNA expression, p38 and ERK activation contribute to DON-induced transcriptional upregulation whereas p38 plays a role in increasing mRNA stability.
Phylogenetic Relationships of the Glycolytic Enzyme, Glyceraldehyde-3-Phosphate Dehydrogenase, from Parabasalid Flagellates

Over 90% of the open reading frame of gap genes for glycolytic glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12) was obtained with PCR from five species of Parabasala. With gap1 from Trichomonas vaginalis obtained earlier, the data include two sequences each for three species. All sequences were colinear with T. vaginalis gap1 and shared with it as a synapomorphy a 10- to 11-residue insertion not found in any other gap and an S-loop with characteristic features of eubacterial GAPDH. All residues known to be highly conserved in this enzyme were present. The parabasalid sequences formed a robust monophyletic group in phylogenetic reconstructions with distance-based, maximum-parsimony, and maximum-likelihood methods. The two genes of the amphibian commensal, Trichomitus batrachorum, shared a common ancestor with the rest, which separate into two well-supported lineages. T. vaginalis and Tetratrichomonas gallinarum (both representatives of Trichomonadinae) formed one, while Monocercomonas sp. and Tritrichomonas foetus formed the other. These data agreed with and/or were close to published reconstructions based on other macromolecules. They did not support the ancestral position of Monocercomonas sp. proposed on the basis of morphological characteristics but confirmed an early emergence of Trichomitus batrachorum. The sequence pairs obtained from three species indicated either gene duplications subsequent to the divergence of the corresponding lineages or a strong gene conversion later in these lineages. The parabasalid clade was a robust part of the eubacterial radiation of GAPDH and showed no relationships to the clade that contained all other eukaryotic gap genes. The data clearly reveal that the members of this lineage use in their glycolytic pathway a GAPDH species with properties and an evolutionary history that are unique among all eukaryotes studied so far.
TOTAL CROSS SECTION FOR PROTON EXCITATION OF H ATOMS.

Abstract In this letter we give a simple expression for the total cross section for excitation to all discrete states of a hydrogen atom by a fast proton. This asymptotic expression is applicable for protons of energy equal to or greater than 25 keV.
American family building strategies in 1900: stopping or spacing.

Contemporary populations frequently space the births of children, and also attempt to stop childbearing after achieving a desired family size. While stopping behavior was evident in European populations in the late nineteenth century, little is known about the degree to which they attempted to space their children at specific interval lengths. This paper compares spacing patterns among various groups of white U.S. women in 1900, who were distinguished by varying family sizes and levels of fertility control. On the whole, there is little evidence of childspacing differences among native white populations, except for some very low parity women. The findings support the continued analysis of age patterns of fertility as the major means for determining the onset of conscious family limitation.
Cultural ecosystem services and economic development: World Heritage and early efforts at tourism in Albania

Abstract Albania actively promotes its World Heritage sites and other attributes of its cultural heritage, including local food and beverages, dance, tapestries and even its communist era, in its marketing efforts. Better information about the emergent tourism sector, particularly with regard to Albania׳s abundant potential in nurturing and capturing the value of its cultural ecosystem services, could help the country to better manage toward its economic development objectives. In this paper, results of a survey of international visitors to Mother Theresa International Airport, highlighting their expenditure patterns, activities, their assessment of their visit with a particular focus on natural and cultural tourism are reported. For example, the average additional willingness to pay to travel to Albania under current experiential conditions is €410. On average, respondents were willing to pay an additional €95 to the Albanian government to invest in Albanian natural and cultural ecosystem services. This potentially translates into an estimated €95 million per year to invest in Albania׳s cultural and natural heritage, or €42 million for culture and €53 million for nature. The results point to the very young stage of tourism development and may illuminate strategies to introduce international audiences to Albania through conferences or other business oriented travel.
Ranking of toxics release inventory chemicals using a level III fugacity model and toxicity

In an effort to lessen the environmental impact of chemicals discharged by industry, some countries rank chemicals according to mass released each year and then set environmental protection policy based upon this ranking. These rankings have driven industries and companies to change their process configurations and their chemical releases to reduce the release of higher ranking chemicals. But, chemicals that are higher ranked due to mass release may not be particularly toxic nor persistent in the environment; conversely, lower ranked chemicals may be substantially more toxic and persistent in the environment. The physical/chemical properties of forty five organic chemicals from the EPA's Toxic Release Inventory were used as inputs to a Level III fugacity model to estimate fate, transport, and steady state concentrations of chemicals in the environment. The resulting concentrations in the air and water, for each chemical, were determined using the fugacity model and were then compared with toxicity data, the ratio was used as an indication of the environmental impact of the release of each chemical. The chemicals were then ranked according to the degree of environmental impact and the results were compared to other ranking systems reported in the literature.
A computational study of carbon nanotube optoelectronic devices

Since the first demonstration of electroluminescence (EL) from a CNTFET about three year ago, significant progress has been achieved in CNT optoelectronics. We have developed semiclassical and quantum transport simulators for CNT optoelectronic devices. A self-consistent simulation, which couples a quantum treatment of the metal-CNT contacts to a semiclassical treatment of the channel, is performed to understand carrier transport and light emission in a CNT infrared emitter. The results show that when the channel is long, light emission significantly affects carrier transport, and reduces the source-drain current by a factor of 2 in ambipolar transport regime. The experimentally observed light-spot movement along the channel can be mostly understood and explained by a simple, semiclassical picture. The photoconductivity of carbon nanotube (CNT) Schottky barrier transistors is studied by solving the nonequilibrium Green's function transport equation. The model provides a detailed and coherent picture of electron-photon coupling and quantum transport effects. The photocurrent shows peaks at photon energies near the subband gaps, which can be engineered by controlling the CNT diameter. Electron-phonon coupling (i) slightly broadens the peaks, (ii) leads to phonon-assisted photocurrent at certain energy ranges, and (iii) changes the energy-resolved photocurrent. We also show that the metal/CNT barrier height has a much smaller effect on the photocurrent than on the dark current. We also show the important role of sub-bandgap impact ionization and excitation in CNT devices.
Selective Jamming Attacks in Wireless Networks

We address the problem of selective jamming attacks in wireless networks. In these attacks, the adversary selectively targets specific packets of "high" importance by exploiting his knowledge on the implementation details of network protocols at various layers of the protocol stack. We illustrate the impact of selective jamming on the network performance by illustrating various selective attacks against the TCP protocol. We show that such attacks can be launched by performing real-time packet classification at the physical layer. We examine the combination of cryptographic primitives with physical layer attributes for preventing real- time packet classification and neutralizing the inside knowledge of the attacker.
Time series prediction: statistical and neural techniques

In this paper we compare the performance of nonlinear neural network techniques to those of linear filtering techniques in the prediction of time series. Specifically, we compare the results of using the nonlinear systems, known as multilayer perceptron and radial basis function neural networks, with the results obtained using the conventional linear Wiener filter, Kalman filter and Widrow-Hoff adaptive filter in predicting future values of stationary and non- stationary time series. Our results indicate the performance of each type of system is heavily dependent upon the form of the time series being predicted and the size of the system used. In particular, the linear filters perform adequately for linear or near linear processes while the nonlinear systems perform better for nonlinear processes. Since the linear systems take much less time to be developed, they should be tried prior to using the nonlinear systems when the linearity properties of the time series process are unknown.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Use of vascular sealing devices (VasoSeal and Perclose) versus assisted manual compression (Femostop) in transcatheter coronary interventions requiring abciximab (ReoPro).

Transcatheter coronary interventions requiring abciximab (ReoPro) are associated with vascular access site complications. Several devices have been developed to aid in the closure of the femoral arteriotomy, including collagen plug devices (VasoSeal, Angio-Seal), percutaneous suture closure (Perclose), and aids to manual compression (Femostop). In 185 patients who received abciximab plus aspirin and heparin for transcatheter coronary interventions, we compared femoral arteriotomy closure by three different methods: VasoSeal, Perclose, and Femostop. A composite endpoint of late complications defined as an access site-related bleed or hematoma that required blood transfusion or an extended hospital stay, pseudoaneurysm, arteriovenous fistula, arterial or venous thrombosis was compared. VasoSeal was initially successful in 41/52 patients (78.8%). The 11 patients who failed to have adequate hemostasis with VasoSeal required manual compression aided by Femostop, but had no late complications. There was one access site infection and one fatal retroperitoneal hematoma unrelated to the vascular access site (surgically explored). There were no late complications. Perclose was successful in 48/56 patients (85.7%). One Perclose failure required surgical repair for an extensive arteriotomy. The other Perclose failure required manual compression aided by Femostop, but had no late complications. There were no access site infections requiring intravenous antibiotics. There was one retroperitoneal bleed that extended the patient's hospital stay and for which a blood transfusion was required. Femostop was successful in 77/77 patients (100%). There were no infections. Late complications occurred in four patients. These included three episodes of bleeding or hematomas requiring blood transfusion, and one pseudoaneurysm. Conclusion: In patients receiving abciximab in addition to aspirin and heparin, VasoSeal and Perclose are at least as safe as Femostop when used to achieve homeostasis after sheath removal. VasoSeal and Perclose have a significantly lower initial rate of successful hemostasis than Femostop. The numbers of late complications between the VasoSeal, Perclose, and Femostop groups were not significantly different. In those patients in whom VasoSeal or Perclose failed, no late complications occurred. Access site infections were no different between VasoSeal, Perclose, and Femostop. Cathet. Cardiovasc. Intervent. 47:143–147, 1999. © 1999 Wiley-Liss, Inc.
Crystal structure and dimerization equilibria of PcoC, a methionine-rich copper resistance protein from Escherichia coli

PcoC is a soluble periplasmic protein encoded by the plasmid-born pco copper resistance operon of Escherichia coli. Like PcoA, a multicopper oxidase encoded in the same locus and its chromosomal homolog CueO, PcoC contains unusual methionine rich sequences. Although essential for copper resistance, the functions of PcoC, PcoA, and their conserved methionine-rich sequences are not known. Similar methionine motifs observed in eukaryotic copper transporters have been proposed to bind copper, but there are no precedents for such metal binding sites in structurally characterized proteins. The high-resolution structures of apo PcoC, determined for both the native and selenomethionine-containing proteins, reveal a seven-stranded β barrel with the methionines unexpectedly housed on a solvent-exposed loop. Several potential metal-binding sites can be discerned by comparing the structures to spectroscopic data reported for copper-loaded PcoC. In the native structure, the methionine loop interacts with the same loop on a second molecule in the asymmetric unit. In the selenomethionine structure, the methionine loops are more exposed, forming hydrophobic patches on the protein surface. These two arrangements suggest that the methionine motifs might function in protein-protein interactions between PcoC molecules or with other methionine-rich proteins such as PcoA. Analytical ultracentrifugation data indicate that a weak monomer-dimer equilibrium exists in solution for the apo protein. Dimerization is significantly enhanced upon binding Cu(I) with a measured Δ(ΔG°)≤–8.0 kJ/mole, suggesting that copper might bind at the dimer interface.
Practical nuclear medicine for pediatricians. I. General principles and definitions.

This article surveys the principles behind pediatric nuclear medi cine in terms useful to the referring pediatrician, and illustrates the kinds of children's lesions for which nuclear medicine diagnosis is helpful. Subsequent articles in this series will deal in more de tail with the procedures, materials and results mentioned here.
A performance study of robust distributed load sharing strategies

In this paper, we examine a set of load sharing strategies that are robust to the unreliable state information that is often present in a distributed database system. In this environment, sites must solve the problem of how alternative sites should be selected to process incoming transactions, given that the information on which the decision is based exhibits varying degrees of obsolescence. A set of regression-based adaptive strategies is examined in which a feedback mechanism is used to compensate for obsolete information. Transaction response time under the different adaptive strategies is evaluated, and the reasons for these performance differences discussed. The key characteristic of the best regression strategy is that transaction site affinity is taken into consideration when adjusting for the effect of information obsolescence. >
Metacognition and False Recognition in Alzheimer's Disease: Further Exploration of the Distinctiveness Heuristic

The distinctiveness heuristic is a response mode in which participants expect to remember vivid details of an experience and make recognition decisions on the basis of this metacognitive expectation. The authors examined whether the distinctiveness heuristic could be engaged to reduce false recognition in a repetition-lag paradigm in patients with Alzheimer's disease (AD). Patients with AD were able to use the distinctiveness heuristic--though not selectively--and thus they showed reduction of both true and false recognition. The authors suggest that patients with AD can engage in decision strategies on the basis of the metacognitive expectation associated with use of the distinctiveness heuristic, but the patients' episodic memory impairment limits both the scope and effectiveness of such strategies.
A Bayesian pharmacometric approach for personalized medicine: a proof of concept study with simulated data

The objective of this research program is to optimize drug dose regimen for an individual, using minimally invasive clinical testing, in order to reduce both the total cost of treatment and the risk for over or under-medication using a Bayesian modeling approach. The challenge is to extract the PharmacoKinetic/PharmacoDynamic(PK/PD) parameters for an individual from population level plasma concentration information gathered in clinical trials along with one or two plasma samples from an individual and use these personalized parameters in determining most appropriate dose regimen for a specific patient. In this study we illustrate the plausibility of our methodology through a proof-of-concept study with simulated data.
Reciprocity-transposition-based sinusoidal pulsewidth modulation for diode-clamped multilevel converters

Modulation strategies for multilevel inverters have typically focused on synthesizing a desired set of three phase sinusoidal voltage waveforms using a fixed number of DC voltage levels. This results in the average current injection and hence the net power drawn from the multiple DC bus terminals to be unmatched and time varying. Subsequently, the DC-bus voltages are unregulated, requiring corrective control action to incorporated. In this paper, the principle of reciprocity transposition in introduced as a means for modeling the DC-bus current injection simultaneously as the modulation strategy is formulated. Furthermore, a new sinusoidal pulsewidth-modulation strategy that features constant and controllable current injection at the DC-bus terminals while maintaining output voltage waveform quality is introduced. The proposed strategy is general enough to be applied to converters with an even number of levels and an odd number of levels. Analytical results comparing the performance of the proposed modulator with a conventional multiple carrier modulator are presented for example multilevel converters with four and five levels. Computer simulation results verifying the analytical results are presented for a four-level converter.
Pipelining in algorithms with quantizer loops

High-speed implementation of signal processing algorithms for digital transmission is addressed. The internal feedback or recursion in these algorithms makes it difficult to implement recursive systems concurrently using either pipelining or parallelism. In the past, look-ahead computation techniques were successfully applied to create necessary concurrency in linear recursive and some nonlinear recursive operations (such as the add-compare-select operation). Novel computation approaches are proposed, and the look-ahead technique is extended to pipeline the feedback loops containing finite-level quantizers. Approaches to pipeline piecewise-linear recursive systems are presented. The proposed architectures are suitable for real-time high-speed implementation of quantizer loop operations where the levels of quantizer and the order of the loops are small. >
Growth in children and adolescents with juvenile idiopathic arthritis over 2 years of treatment with etanercept: results from the British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study

OBJECTIVES: Children with JIA can experience delayed and restricted growth. The objectives of this study were to investigate the influence of etanercept (ETN) on vertical growth and factors associated with improved growth in patients with JIA over the initial 2 years of treatment. METHODS: This analysis was restricted to ETN-treated patients in the British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study with complete height data recorded at baseline, 1 and 2 years. Height z-scores were calculated using the World Health Organization growth standards for age and gender. Change in height z-score was evaluated over time. Multivariable linear regression was used to identify factors associated with change in height z-score from baseline. RESULTS: A total of 191 ETN-treated patients were included: 65% female, median baseline age 11.0 years [interquartile range (IQR) 7.3-12.9], median disease duration 3.5 years (IQR 1.7-7.1). At baseline mean height z-score was -0.74 (s.d. 1.4). After 2 years mean height z-score increased to -0.45 (1.4) (change +0.29; P < 0.001). In multivariable analysis, factors associated with an improvement in height z-score included lower baseline height z-score [-0.110 per unit (95% CI -0.161, -0.059), P < 0.001] and no oral corticosteroid use at baseline [-0.192 (95% CI -0.343, -0.040), P = 0.013]. CONCLUSION: ETN therapy was associated with an improvement in height z-score over the first 2 years of therapy in this real-world cohort of children with severe JIA. The lack of a strong association of improvements in height with improvements in disease activity warrants further exploration.
Phenytoin Pharmacokinetics: Before and After Folic Acid Administration

Phenytoin (PHT) exhibits linear and Michaelis-Menten pharmacokinetics. PHT decreases serum folate; the vitamin folic acid (FA) is hypothesized to be a cofactor in the metabolism of PHT. The depletion of serum folate may explain the unpredictability of measured total serum PHT concentrations and time to steady state as compared with the Michaelis-Menten predictive calculations. We examined PHT pharmacokinetics before and after FA supplementation in 13 healthy male volunteers. The study was divided into two phases. Phase I determined V(max) (mg/day) and Km (micrograms/ml) of PHT to calculate PHT doses needed for the second phase. Phase II was a four-way cross-over study to examine the effect of 1 and 5 mg FA on total serum PHT concentrations 1 microgram/ml less and 5 micrograms/ml greater than the subject's Km, Km - 1 and Km + 5, respectively. Predicted versus measured total serum PHT concentrations, t90% (days to steady state), and the effect of FA were calculated for Km - 1 and Km + 5 before and after 1 or 5 mg FA. The measured total serum PHT concentration was always greater than the calculated concentration (p less than 0.05), and t90% was always longer than the calculated t90% (p less than 0.05) for Km - 1 before FA (all subjects decreased serum FA); the same was observed for Km + 5. If folate is assumed to be a cofactor in PHT metabolism, these results are expected, because depletion of the vitamin would indicate less folate to drive the metabolism of PHT, resulting in higher total serum PHT concentrations and longer time to reach steady state.(ABSTRACT TRUNCATED AT 250 WORDS)
The relationship between environmental change and the extinction of the nannoplankton Discoaster in the early Pleistocene

The long-ranging nannoplankton genus Discoaster went extinct in the early Pleistocene, one of the most significant events in the Cenozoic nannofossil record. The causal factors of this extinction are poorly constrained, at least partially because the ecology of Discoaster is not well understood. We investigate the relationship between the extinction and environmental changes by comparing a suite of high-resolution nannofossil assemblage data at four Ocean Drilling Program sites to published environmental proxy records. Through the use of multivariate analysis, we determine Discoaster shared environmental preferences with the extant species Florisphaera profunda which thrives in the lower photic zone near the nutricline in locations where the water column is stratified. We show that the last occurrence of Discoaster was globally diachronous, rather than synchronous as previously thought, and likely took place in the equatorial Atlantic Ocean. We propose that the demise of Discoaster was a two-stage process. A decrease in sea surface temperatures and increase in climate variability led to a global decline in Discoaster abundance. The extinction event itself correlates to shoaling of the nutricline as signified by a decrease in the carbon isotopic gradient between surface and thermocline foraminifera. We hypothesize that the combination of global cooling and a shoaling of the nutricline greatly reduced Discoaster's deepwater niche and contributed to its extinction. This may suggest that ocean stratification and the depth of the nutricline are important contributors to overall nannoplankton diversity.