cssi/SciSciGPT-SciSciNet huggingface dataset:
Immunosurveillance: Innate and Adaptive Antitumor Immunity

Publisher Summary This chapter discusses about the innate and adaptive anti-tumor responses. Normal cells are endowed with intricate machinery that affords protection against genotoxic stress induced by cell intrinsic and extrinsic insults, including the DNA replication errors, oxidative damage, microbial infection, and inflammation. The failure of the DNA damage response to resolve the single-stranded or double-stranded DNA breaks, poses a risk for malignant transformation. In such a context, the innate immune system functions as an extrinsic surveillance mechanism for genotoxic injury. The NKG2D ligands, which include the major histocompatibility complex (MHC) class I-related molecules, four UL16 binding proteins (ULBP1–4) in humans, and the retinoic acid-early (RAE) inducible gene products and H60 in rodents— are induced by DNA damage through a pathway involving ataxia telangiectasia mutated (ATM), ataxia telangiectasia and Rad3 related (ATR), Chk-1, and Chk-2. While such innate responses may contribute to tumor suppression, their aberrant activation may also prove deleterious when normal tissues are perturbed, as during autoimmunity or chronic inflammation.
Cost-effectiveness of influenza vaccination of adult cancer patients

6079 Background: Despite recommendations to immunize all patients at increased risk from underlying immunosuppressive disease against influenza, many insurance plans do not cover the vaccine. We an...
Biology of Myelodysplasia Clonality: Clinical Implications of Whole-Genome Sequencing

Abstract SCI-32 The discovery of acquired genetic mutations associated with myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) has rapidly expanded with the use of next-generation sequencing technologies. The distinction between MDS and de novo or secondary AML (arising after MDS) and therapeutic recommendations are largely based on the presence of morphologic dysplasia and the percentage of bone marrow myeloblasts. Using whole genome sequencing to define the allele burden of hundreds of mutations, our group has shown that nearly all the bone marrow cells in seven patients with MDS and secondary AML were clonally derived (∼85%), regardless of the myeloblast count. We now have experimental evidence suggesting that the vast majority of mutations in these samples are randomly acquired during aging (passenger mutations) and carried forward in a cell when it is transformed. By using all the validated mutations in a sample (passengers and drivers) we found that five of the seven MDS samples harbored two or more malignant clones and that all seven contained a founding clone that gave rise to subsequent daughter clones. Thus, the MDS bone marrow samples are a mosaic of several tumors with unique sets of mutations each shaped by the acquisition of a series of mutations and clonal diversification. Each clone contained at least one coding gene mutation, and we identified 11 recurrently mutated genes in the seven samples, including recently described mutations in U2AF1 , a spliceosome gene that is typically mutated in the MDS founding clone. In addition, the MDS founding clone always gave rise to the dominant secondary AML clone, suggesting that therapies targeting mutations in the founding clone may have benefit in treating both MDS and secondary AML. It is possible that therapeutic response and disease progression is driven not only by the presence of recurrent mutations, which have prognostic value, but also by the clone (i.e., founding and daughter) in which they arise. We are currently testing this hypothesis by monitoring the dynamic change in clone size, including driver mutation allele burdens, during treatment of patients with AML and MDS. Disclosures: No relevant conflicts of interest to declare.
Autobiography of an archive: a scholar’s passage to India, by Nicholas B. Dirks

Full disclosure: the author is an old, dear friend. That made it complicated to write this review. Perhaps I should have declined, but reading this fascinating account of one scholar’s archival ide...
A new HSP90 inhibitor as therapeutic agent for bladder cancer.

416Background: Hsp90 represents one of the most promising biological targets for the treatment of cancer, including bladder cancer. A number of Hsp90 inhibitors that target the N-terminal ATP-binding pocket have demonstrated potent antiproliferative effects. However, a major drawback is that they induce a prosurvival heat shock response (HSR). We demonstrate the effects of a novel Hsp90 beta selective inhibitor on bladder cancer cells, which shows potent antiproliferative effects without inducing HSR. Methods: Cell Titer-Glo luminescent anti-proliferative assay was used to determine the IC50 numbers in UC3 cells. Trypan Blue Cytotoxicity assay was performed for 24h treatment with increasing concentrations of the inhibitor. Effects of the cmpound on Hsp90’s client protein degradation were investigated by Western Blot. Results: This new compound exhibits potent anti-proliferative in bladder cancer cells. IC50 number is determined as 0.30 µM for UC3 cancer cells. The toxicity assay was also performed over UC...
Producing Octave-Wide Combs And Few-Cycle Pulses In The Mid-Infrared: Frequency Divide-And-Conquer Approach

Mid-IR frequency combs are produced via subharmonic OPO process where the fiber-laser pump comb is transposed to half its frequency and simultaneously spectrally augmented, thanks to enormous OPO gain bandwidth and massive spectral cross coupling.
The Method of Path Coefficients

The classical simple linear regression model involves one independent variable and one dependent (outcome) variable. Sewall Wright developed the method of path coefficients as a comprehensive approach to study the direct and indirect relationships between multiple independent variables and a dependent variable. The approach builds upon traditional regression analysis by building models that incorporate all hypothesized necessary and sufficient conditions and that better address temporal “cause-and-effect” associations. The net result of the method of path coefficients is the realization that many variables, some seemingly insignificant, may contribute directly or indirectly to given health and behavioral outcomes.
Severity of Illness Scoring Systems

The degree of illness of patients admitted to ICUs varies enormously. The severity of illness affects resource and manpower utilization, length of stay, complication rate, and outcome. To adequately compare and contrast critically ill patients, it is useful to quantitate the severity of their illness. To achieve this goal, a number of severity of illness scoring systems have been developed. Most of these scoring systems are based on the premise that the severity of a patient’s illness is related to the degree of physiological derangement of the major organ systems. Points are assigned according to the degree of derangement of readily available physiological variables, and a total score is then computed (Table 47-1; APACHE II scoring system). It is then assumed that for patients with similar disease processes the risk of death is related to the severity of illness score.
CraftML: 3D Modeling is Web Programming

We explore web programming as a new paradigm for programmatic 3D modeling. Most existing approaches subscribe to the imperative programming paradigm. While useful, there exists a gulf of evaluation between procedural steps and the intended structure. We present CraftML, a language providing a declarative syntax where the code is the structure. CraftML offers a rich set of programming features familiar to web developers of all skill levels, such as tags, hyperlinks, document object model, cascade style sheet, JQuery, string interpolation, template engine, data injection, and scalable vector graphics. We develop an online IDE to support CraftML development, with features such as live preview, search, module import, and parameterization. Using examples and case studies, we demonstrate that CraftML offers a low floor for beginners to make simple designs, a high ceiling for experts to build complex computational models, and wide walls to support many application domains such as education, data physicalization, tactile graphics, assistive devices, and mechanical components.
Extensibility of the supraspinatus muscle can be predicted by combining shear wave elastography and magnetic resonance imaging-measured quantitative metrics of stiffness and volumetric fat infiltration: A cadaveric study.

Abstract Background A torn rotator cuff tendon will retract over time causing changes in muscle properties and decreasing its extensibility, or deformation. During surgery, large tensile loads are applied to bring the torn tendon to the footprint. Poor muscle extensibility and large tensile stresses at the repair might lead to gap formation or re-tear of the repair. A quantitative evaluation of muscle properties could be used to predict the extensibility of the supraspinatus (SSP) muscle. Method Magnetic resonance imaging (MRI)-measured volumetric fat fraction and shear wave elastography (SWE)-measured elastic modulus of the SSP muscle were obtained on seventeen cadaveric shoulders. Experimental extensibility and stiffness were then measured by axially pulling the tendon up-to 60 N. Univariate and multivariate analyses were used to determine the correlation and contribution of fat fraction and elastic modulus to experimental outcomes. Findings SWE moduli negatively correlated with SSP muscle extensibility (r = 0.54–0.58, P ≤ 0.0259); fat fraction resulted in a positive correlation (r = 0.69, P = 0.0021). SWE measurements, solely, explained up to 34% and 33% of the variability in measured extensibility and stiffness, respectively. Fat Fraction, solely, explained 48% of the variability in extensibility and 36% of the variability in stiffness. These methods combined predicted up to 62% of the musculotendinous extensibility. Interpretation This study showed a comprehensive quantitative assessment of SSP muscle properties using SWE to estimate stiffness and MRI to measure fatty infiltration. The extensibility of the detached muscle/tendon unit was highly correlated to material properties of the muscle when these methods were used in combination.
Diagnostic Radiology Research Program Development

Providing recommendations regarding developing and maintaining radiology research and research training facilities is a difficult task because no two departments have the same goals, resources, commitment, faculty composition, or philosophy. There is no ideal model and every department must address issues specific to their own particular goals and needs. However, concern has been generated in the radiology community regarding the role, development, and expansion of research programs and many of the issues that need to be considered are germane to all departments. The primary purpose of this chapter is to provide information which may be of value to the reader charged with the responsibility of addressing research-related issues in a clinical radiology department.
Evolving macromodular molecular modeling system

This paper deals with the role digital computer building blocks, such as the “macromodules” developed at Washington University, St. Louis,2 can play in providing the scientist with flexible, high performance computing facilities. The development and use of a system for molecular modeling has been chosen for illustration.
Adapted tube cleaning practices to reduce particulate contamination at hydrogen fueling stations

Abstract The higher rate of component failure and downtime during initial operation in hydrogen stations is not well understood. The National Renewable Energy Laboratory (NREL) has been collecting failed components from retail and research hydrogen fueling stations in California and Colorado and analyzing them using an optical zoom and scanning electron microscope. The results show stainless steel metal particulate contamination. While it is difficult to definitively know the origin of the contaminants, a possible source of the metal particulates is improper tube cleaning practices. To understand the impact of different cleaning procedures, NREL performed an experiment to quantify the particulates introduced from newly cut tubes. The process of tube cutting, threading and beveling, which is performed most often during station fabrication, is shown to introduce metal contaminants and thus is an area that could benefit from improved cleaning practices. This paper shows how these particulates can be reduced, which could prevent station downtime and costly repair. These results are from the initial phase of a project in which NREL intends to further investigate the sources of particulate contamination in hydrogen stations.
In-situ irradiation tolerance investigation of high strength ultrafine tungsten-titanium carbide alloy

Abstract Refining grain size and adding alloying elements are two complementary approaches for enhancing the radiation tolerance of existing nuclear materials. Here, we present detailed in-situ irradiation research on defect evolution behavior and irradiation tolerance of ultrafine W-TiC alloys (thin foils) irradiated with 1 MeV Kr+2 at RT and 1073 K, and compare their overall performance to pure coarse grained tungsten. Loop Burgers vector was studied confirming the presence of loops whose population increased at high temperature. Loop density, average loop area, and overall damage are reported as a function of irradiation dose revealing distinct defect evolution behavior from pure materials. The overall damage generally followed the average loop size trend, which decreased with time for both temperatures, but was higher at 1073 K and attributed to biased vacancy sink behavior of the TiC dispersoids evidenced by large vacancy clusters on their interfaces. By comparison, the overall loop and void damage in pure tungsten was larger by a factor of six and two, respectively. The improved irradiation damage resistance in the alloys is thus attributed to the effect of dispersoids in 1) the enhancement in annihilating defects and mutual defect recombination due to both dispersoids and a higher grain boundary density; 2) decreasing the loop mobility, causing shrinkage and annihilation of loop density, which was confirmed via in-situ video. Several mechanisms are illustrated to describe the performance of the complex alloy system. The results motivate further experimental and modeling research that aims to understand the many different phenomena occurring at different time scales.
Instrumental variable analyses for causal inference: Application to multilevel analyses of the alliance-outcome relation.

AbstractObjective: To introduce readers to instrumental variable analyses for causal inferences using as an example a test of the hypothesis that the quality of the therapeutic alliance has a causa...
Magnetic resonance induced pseudoelectric field and giant current response in axion insulators

A quantized version of the magnetoelectric effect, known as the topological magnetoelectric effect, can exist in a time-reversal invariant topological insulator with all its surface states gapped out by magnetism. This topological phase, called the axion insulator phase, has been theoretically proposed but still lacks conclusive experimental evidence due to the small signal of topological magnetoelectric effect. In this work, we propose that the dynamical in-plane magnetization in an axion insulator can generate a pseudoelectric field, which acts on the surface state of topological insulator films and leads to the nonzero response current. Strikingly, we find that the current at magnetic resonance (either ferromagnetic or antiferromagnetic) is larger than that of topological magnetoelectric effect by several orders of magnitude and thereby serves as evidence to confirm the axion insulator phase in the candidate materials.
Matrix-Delivered Autologous Mesenchymal Stem Cell Therapy for Refractory Rectovaginal Crohn’s Fistulas

BACKGROUND Crohn's rectovaginal fistulizing disease remains notoriously difficult to treat. A phase I clinical trial to evaluate the safety and feasibility of a novel protocol using a mesenchymal stem cell (MSC)-coated Gore Bio-A fistula plug for the treatment of medically and surgically refractory Crohn's rectovaginal fistulas was conducted. METHODS Five patients underwent an autologous subcutaneous adipose tissue harvest via a 2-cm abdominal wall incision at time of exam under anesthesia (EUA) with seton placement. MSCs were isolated, expanded, and impregnated on the plug. After 6 weeks, patients returned to the operating room for placement of the MSC-coated plug. The primary end points were safety and feasibility; the secondary end point was clinical and radiographic healing at 6 months. RESULTS Five female patients (median age [range], 49 [38-53] years) with a median disease duration (range) of 23 (7-34) years who were on biologic (n = 5) or combination therapy (n = 3) had successful harvest and expansion of MSCs and delivery of the Gore Bio-A plug. There were no serious adverse events or adverse events related to the MSCs or plug during the 6-month follow-up. At 6 months, 3 patients had complete cessation of drainage, and 2 had >50% reduction in drainage; all had a persistent fistula tract identified on magnetic resonance imaging and EUA at 6 months. CONCLUSIONS Surgical placement of an autologous adipose-derived MSC-coated fistula plug in diverted patients with Crohn's rectovaginal fistulas was safe and feasible. All patients had a reduction in the size of their fistula tract, and 3 of 5 had cessation of drainage, but none achieved complete healing.This was a phase I clinical trial of autologous mesenchymal stem cells on a plug for rectovaginal Crohn's fistulas.
The Impact of a Positive, Self-Talk Statement on Public Speaking Anxiety

A positive, pre-speech self-talk experience was used to assess the influence on student performance anxiety in a variety of disciplines. The findings suggest that having students recite aloud a sel...
Diffusion and adoption of the surgical robot in urology

Over the last two decades, robotic surgery has become a mainstay in hospital systems around the world. Leading this charge has been Intuitive Surgical Inc.’s da Vinci robotic system (Sunnyvale, CA, USA). Through its innovative technology and unique revenue model, Intuitive has installed 4,986 robotic surgical systems worldwide in the last two decades. The rapid rate of adoption and diffusion of the surgical robot has been propelled by many important industry-specific factors. In this review, we propose a model that explains the successful adoption of robotic surgery due to its three core groups: the surgeon, the hospital administrator, and the patient.
Dendrite-free, wide temperature range lithium metal batteries enabled by hybrid network ionic liquids

Abstract Replacing liquid electrolytes with solid-state electrolytes is a promising approach to achieving practical applications of lithium metal batteries (LMBs). In this work, ionic liquid N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide (Pyr13FSI) was introduced into a hybrid network to obtain a series of gel polymer electrolytes (GPEs). Mechanical and electrochemical properties of the GPEs were tuned through controlling the network structure and ionic liquid contents, and ionic conductivity higher than 1 ​mS ​cm-1 at room temperature was achieved. The newly developed GPEs are flame-retardant and show excellent thermal and electrochemical stability as well as ultra-stability with lithium metal anode. Symmetrical lithium cells with the GPEs exhibit a stable cycling over 6800 ​h ​at a current density of 0.1 ​mA ​cm-2 and stable lithium stripping-plating at 1 ​mA ​cm-2, the highest current density reported for ionic liquid-based GPEs. Detailed correlation between mechanical properties, ionic conductivity and cell short-circuit time is discussed. Moreover, Li/LiFePO4 batteries with the obtained GPEs exhibit desirable cycling stability and rate performance over a wide temperature range from 0 ​°C to 90 ​°C, further suggesting that this new hybrid-network/ionic liquid GPE system has great potential for practical applications in next generation LMBs.
Educator Perceptions and Use of Technology in South African Schools

South African schools experience diverse access to educational technology. Further, South African educators have limited opportunities to attend educator professional development workshops focused ...
Abstract 15479: Adherence to Healthy Lifestyles Among Chinese Adults

Introduction: Healthy lifestyles are effective means to reduce premature deaths. However, comprehensive knowledge about adherence to multiple healthy lifestyles in Chinese adults is still lacking. ...
Nodal staging convergence for HPV- and HPV+ oropharyngeal carcinoma.

Background Modern disease staging systems have restructured human papillomavirus (HPV)-negative (HPV-) and HPV-positive (HPV+) oropharyngeal carcinoma (OPC) into distinct pathologic nodal systems. Given that quantitative lymph node (LN) burden is the dominant prognostic factor in most head and neck cancers, we investigated whether HPV- and HPV+ OPC warrant divergent pathologic nodal classification. Methods Multivariable Cox regression models of OPC surgical patients identified via U.S. cancer registry data were constructed to determine associations between survival and nodal characteristics. Nonlinear associations between metastatic LN number and survival were modeled with restricted cubic splines. Recursive partitioning analysis (RPA) was used to derive unbiased nodal schema. Results Mortality risk escalated continuously with each successive positive LN in both OPC subtypes, with analogous slope. Survival hazard increased by 18.5% (hazard ratio [HR], 1.19 [95% CI, 1.16-1.21]; P 5 LN+. Conclusion HPV- and HPV+ OPC exhibit parallel relationships between nodal characteristics and relative mortality. In both diseases, metastatic LN number represents the principal nodal covariate governing survival, with ENE being an influential secondary element. A consolidated OPC pathologic nodal staging system that is based on these covariates may best convey prognosis. Lay summary The current nodal staging system for oropharyngeal carcinoma (OPC) has divided human papillomavirus (HPV)-negative (HPV-) and HPV-positive (HPV+) OPC into distinct systems that rely upon criteria that establish them as separate entities, a complexity that may undermine the core objective of staging schema to clearly communicate prognosis. Our large-scale analysis revealed that HPV- and HPV+ pathologic nodal staging systems in fact mirror each other. Multiple analyses produced conspicuously similar nodal staging systems, with metastatic lymph node number and extranodal extension delineating the highest risk groups that shape prognosis. We propose unifying HPV- and HPV+ nodal systems to best streamline prognostication and maximize staging accuracy.
Abnormal neurological pupil index is associated with malignant cerebral edema after mechanical thrombectomy in large vessel occlusion patients

Malignant cerebral edema (MCE) is a feared complication in patients suffering from large vessel occlusion. Variables associated with the development of MCE have not been clearly elucidated. Use of pupillometry and the neurological pupil index (NPi) as an objective measure in patients undergoing mechanical thrombectomy (MT) has not been explored. We aim to evaluate variables significantly associated with MCE in patients that undergo MT and hypothesize that abnormal NPi is associated with MCE in this population. A retrospective analysis of patients with acute ischemic stroke who had undergone MT at our institution between 2017 and 2020 was performed. Baseline and outcome variables were collected, including NPi values from pupillometry readings of patients within 72 h after the MT. Patients were divided into two groups: MCE versus non-MCE group. A univariate and multivariate analysis was performed. Of 284 acute ischemic stroke patients, 64 (22.5%) developed MCE. Mean admission glucose (137 vs. 173; p < 0.0001), NIHSS on admission (17 vs. 24; p < 0.01), infarct core volume (27.9 vs. 17.9 mL; p = 0.0036), TICI score (p = 0.001), and number of passes (2.9 vs. 1.8; p < 0.0001) were significantly different between the groups. Pupillometry data was present for 64 patients (22.5%). Upon multivariate analysis, abnormal ipsilateral NPi (OR 21.80 95% CI 3.32–286.4; p = 0.007) and hemorrhagic conversion were independently associated with MCE. Abnormal NPi and hemorrhagic conversion are significantly associated with MCE in patients following MT. Further investigation is warranted to better define an association between NPi and patient outcomes in this patient population.
Production of 232 Pa from thorium

A procedure is described for the accelerator production of232Pa and its isolation in radiochemically pure form, suitable for isotope tracing of protactinium/thorium chemical separations.
Clinical Outcomes Following Dose-Escalated Proton Therapy for Skull-Base Chordoma.

Purpose To evaluate the effectiveness of external-beam proton therapy (PT) on local control and survival in patients with skull-base chordoma. Materials and methods We reviewed the medical records of patients with skull-base chordoma treated with definitive or adjuvant high-dose PT and updated their follow-up when feasible. We assessed overall survival, disease-specific survival, local control, and freedom from distant metastasis. Radiotherapy toxicities were scored using the Common Terminology Criteria for Adverse Events, version 4.0. Results A total 112 patients were analyzed, of whom 105 (94%) received PT and 7 (6%) received combined proton-photon therapy between 2007 and 2019. Eighty-seven patients (78%) underwent a subtotal resection, 22 (20%) a gross total resection, and 3 (3%) a biopsy alone. The median radiotherapy dose was 73.8 Gy radiobiologic equivalent (GyRBE; range, 69.6-74.4). Ninety patients (80%) had gross disease at radiotherapy and 7 (6%) were treated for locally recurrent disease following surgery. Median follow-up was 4.4 years (range, 0.4-12.6); for living patients, it was 4.6 years (range, 0.4-12.6), and for deceased patients, 4.1 years (range, 1.2-11.2). At 5 years after radiotherapy, the actuarial overall survival, disease-specific survival, local control, and freedom from distant metastasis rates were 78% (n = 87), 83% (n = 93), 74% (n = 83), and 99% (n = 111), respectively. The median time to local progression was 2.4 years (range, 0.8-7). Local control and disease-specific survival by resection status was 95% versus 70% (P = 0.28) and 100% versus 80% (P = 0.06) for gross total, versus subtotal, resection or biopsy alone, respectively. There were no serious acute toxicities (grade ≥ 3) related to radiotherapy. Conclusion High-dose PT alone or after surgical resection for skull-base chordoma reaffirms the favorable 5-year actuarial local control rate compared with conventional techniques with acceptable late-complication-free survival. Outcomes following gross total resection and adjuvant PT were excellent. Further follow-up of this cohort is necessary to better characterize long-term disease control and late toxicities.
Augmentative and Alternative Communication Course Design and Features: A Survey of Expert Faculty and Instructors.

Purpose Multiple surveys have been used to investigate augmentative and alternative communication (AAC) coursework offered in speech-language pathology programs in the last 3 decades. These studies primarily explored the availability of AAC courses and reported a limited number of course characteristics. Because few studies to date have specifically examined the AAC course design, the purpose of this study was to investigate the design and features of AAC coursework, such as learning objectives, course content, assignments, and readings and resources, currently taught in the United States. Method An online survey was developed and distributed to faculty or instructors with AAC expertise associated with 265 speech-language pathology programs in the United States. A total of 64 surveys were completed for a response rate of 24.2% (64/265). Quantitative and qualitative analyses were used to evaluate the survey data. Results Patterns are reported related to a number of course design elements and features, including enrollment, course delivery, learning objectives, content, case-based instruction, assignments, in-class activities, and readings and resources. Conclusions This study reports the design and features of AAC courses presently taught by faculty and instructor experts in the United States. The results have direct implications for faculty and instructors who teach AAC coursework and provide state-of-the-art information needed for continuous improvement of AAC preservice education. Resources and considerations are provided for scholarly teaching and evidence-based education.
Integration of the Ames Bioassay and Chemical Analyses in an Epidemiological Cancer Incidence Study

The development of the Ames bioassay as an instrument for assessing public health problems involving mutagenicity and potential carcinogenicity has resembled the development of other quantitative techniques for assessing public health problems. The Ames test has developed from a qualitative assay of samples in simple matrices into a quantitative determination of complicated environmental mixtures, and its results are now being integrated with human epidemiological studies. Originally, the Ames test was used primarily to determine whether or not a compound was mutagenic (Ames, 1971). Soon quantitative methods were introduced (Ames et al., 1975), and a significant correlation between mutagenicity in the Ames test and carcinogenicity in animal bioassays emerged (McCann et al., 1975). Shortly thereafter, the test was applied to environmental mixtures in the analysis of air particulate material (Pitts et al., 1977; Talcott and Wei, 1977). Currently, the Ames test is used to detect mutagens in a variety of media and sample types. The rapidly expanding list of applications includes drinking water, cigarette smoke, auto exhaust, foods, drugs, and urine (Holstein et al., 1979). Although not a quantitative test in the sense of having well-established precision and accuracy, the Ames bioassay yields results that indicate relative mutagenicity. Thus, it is appropriate to consider its use in epidemiological cancer studies.
On the recognition of tRNA by its aminoacyl-tRNA ligase.

Publisher Summary This chapter reviews that experiments testing the adaptor hypothesis have shown conclusively that mRNA translation by aminoacyl-tRNA is independent of the amino acid attached to the tRNA. This means that esterification of the tRNA, catalyzed by its aminoacyl-tRNA ligase, must be specific if mistaken insertions of amino acids into growing peptide chains are to be avoided. Therefore, a precise orientation of both the tRNA and the activated amino acid must occur on the enzyme in order for esterification of tRNA with the correct amino acid to occur. It discusses that the resolution of enzymatic dissection appears to be limited by the need for fragments sufficiently large to give the ordered structure required for recognition. Interpretation of results from chemical modification is always ambiguous to some extent and this approach by itself cannot solve the recognition problem. It provides very valuable information, particularly with regard to areas that can be altered without changing the activity. There is considerable hope that this technique can be combined with enzymatic dissection to narrow the region involved information of the specific recognition site. Acceptor stem sequences in particular are required to test the uniqueness of this area. Finally, since several tRNA's have been crystallized and crystallographic data is beginning to accumulate, it should be able to assess the magnitude of the technical difficulties that must be solved before it is hoped to “see” the groups involved in specific recognition.
Non-linear interfacial resistance in an indium-YBa2Cu3O7−x contact: Andreev-like behavior in a macroscopic interface

Abstract The current-voltage characteristics of an ultrasonically soldered indium contact made to polycrystalline YBa 2 Cu 3 O 7− x is reported. For temperatures below the superconducting transition temperature T c , the conductance is voltage dependent and has two distinct regimes, of high conductance σ 1 at low voltage and low conductance σ 2 at high voltage. Both the conductances and the break voltage increase rapidly for T T c with | dσ 1 dT| → ∞ at T c . The magnitude of the break voltage is roughly half the BCS superconducting energy gap. The excess high conductance is magnetic field dependent and can be eliminated in fields of ∼ 100 G. A field latched “off” state for the excess conductance has been observed. Much of the behavior suggests near ideal Andreev scattering, but under conditions where this would not be expected.
A theory of behavioral contrast

The reinforcers that maintain target instrumental responses also reinforce other responses that compete with them for expression. This competition, and its imbalance at points of transition between different schedules of reinforcement, causes behavioral contrast. The imbalance is caused by differences in the rates at which different responses come under the control of component stimuli. A model for this theory of behavioral contrast is constructed by expanding the coupling coefficient of MPR (Killeen, 1994). The coupling coefficient gives the degree of association of a reinforcer with the target response (as opposed to other competing responses). Competing responses, often identified as interim or adjunctive or superstitious behavior, are intrinsic to reinforcement schedules, especially interval schedules. In addition to that base-rate of competition, additional competing responses may spill over from the prior component, causing initial contrast; and they may be modulated by conditioned reinforcement or punishment from stimuli associated with subsequent component change, causing terminal contrast. A formalization of these hypotheses employed (a) a hysteresis model of off-target responses giving rise to initial contrast, and (b) a competing traces model of the suppression or enhancement of ongoing competitive responses by signals of following-schedule transition. The theory was applied to transient contrast, the following schedule effect, and the component duration effect.
Online access to NODC information services

Oceanographic data holdings of the National Oceanographic data Center (NODC) are large and varied. A goal at NODC is to provide timely information about those data to users by online computer access. Recently, NODC has developed a prototype system, called NOSIE (NODC Ocean Science Information Exchange), that includes descriptions of NODC data files, helps for sending or ordering data, interactive inventory summaries, and bulletin boards. NOSIE is a menu-driven, modular system to which information resources of various types can easily be added. It was designed using system software for screen management to provide a consistent look and feel during each session. Future plans are to expand inventory summaries, add detailed inventories, and make subsets of ocean files or special data sets directly accessible online. >
Effect of dopamine system activation on substantia nigra pars reticulata output neurons: variable single-unit responses in normal rats and inhibition in 6-hydroxydopamine-lesioned rats

Previous single-unit recording studies have revealed that randomly selected pars reticulata neurons respond in a highly variable and complex fashion to intravenous administration of the dopamine agonist, apomorphine. The current studies were undertaken (1) to assess whether the variable pattern of responses of reticulata neurons to intravenous apomorphine correlates with their sites of projection and (2) to determine how reticulata responses to apomorphine might be altered by the presence of striatal dopaminergic supersensitivity. Extracellular, single-unit recording studies were conducted in anesthetized, paralyzed rats. Pars reticulata neurons were identified by antidromic activation from either the ventromedial nucleus of the thalamus or superior colliculus. Neurons of both subpopulations exhibited similar, highly variable changes in firing rate during the 10-min period immediately following intravenous injection of 320 micrograms/kg of apomorphine, a dose of the drug considered sufficient to stimulate striatal postsynaptic dopamine receptors. These responses, which were not qualitatively different from those previously observed among reticulata cells not distinguished on the basis of projection site, could be reversed by subsequent administration of dopamine antagonist drugs. In contrast to the variable responses in normal animals, the same dose of apomorphine caused a rapid and usually total inhibition of pars reticulata cell firing in rats which received 6-hydroxydopamine lesions of the nigrostriatal dopamine pathway 6 to 8 weeks prior to recording experiments. These inhibitions of firing could also be reversed by administration of dopamine antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)
Production of High Intensity Electron Bunches for the SLAC Linear Collider.

This thesis describes the design and performance of a high intensity electron injecfor for the SLAC Linear Collider. Motivation for the collider and the specifications for the injector are discussed. An analytic theory of the bunching and capture of electrons by rf fields is discussed in the limit of low space charge and small signal. The design and performance of SLAC's main injector are described to illustrate a successful application of this theory. The bunching and capture of electrons by rf fields are then discussed in the limit of high space charge and large signal, and a description of the design of the collider injector follows. In the limit of high space charge forces and large rf signals, the beam dynamics are considerably more complex and numerical simulations are required to predict particle motion. A computer code which models the longitudinal dynamics of electrons in the presence of space charge and rf fields is described. The results of the simulations, the resulting collider injector design and the various components which make up the collider injector are described. These include the gun, subharmonic bunchers, traveling-wave buncher and velocity-of-light accelerator section. Finally, the performance of the injector is described including the beammore » intensity, bunch length, transverse emittance and energy spectrum. While the final operating conditions differ somewaht from the design, the performance of the collider injector is in good agreement with the numerical simulations and meets all of the collider specifications. 28 refs.« less
The right stuff? Teaching parallel computing

We consider the educational process with respect to parallel computing. Education in this area is provided by national supercomputing centers, a variety of manufacturers of parallel machines, within companies that use parallel machines, as well as by colleges and universities for both undergraduate and graduate students. The panel evaluates the current system, and debate potential (realistic) improvements that could be implemented in the short-term. >
Effects of Cytochalasin and Colcemid on Cortical Flow in Coelomocytes

Sea urchin coelomocytes naturally flatten on a substratum into a discoid morphology and display striking, centripetally directed cortical flow along the radii of the cell when viewed with time lapse, video enhanced microscopy. The rate of cortical flow averaged 4.5 Ftn/min in the peripheral most 10 pm of cytoplasm but slows considerably in the perinuclear region. Cytochakasin B causes: (1) the flow to stop, (2) the buildup of an actin filament-rich peripheral ridge of cytoskeletal material, (3) the centrifugal dissolution of a portion of the actin cytoskeleton, and (4) the contraction of other portions of the cytoskeleton into foci. Cytochalasin D (CD), on the other hand, causes the flowing actin meshwork to become severed from the edge of the cell and allows it to be drawn at least part way in towards the nucleus. A smaller peripheral ridge of actin filament buildup is also seen with CD. Colcemid induces another striking change in the cytoskeleton. The centripetal progression of the actin is not stopped by colcemid, but shortly after leaving the periphery of the cell, the linear elements within the flow become reoriented into arcs. The long axis of the arcs is roughly parallel with the cell’s edge. The effects of all three drugs are reversible, The results are discussed in light of other systems and potential mechanisms for cortical flow. 0 1993 Wiley-Liss, Inc.
A discussion and implementation of Brown's REX simplification algorithm

We discuss a simplification algorithm written by W. S. Brown [Bro69], which gives a normal form algorithm for a class of rational expressions merged with (perhaps complex) exponential expressions. Here we describe the algorithm as revised for implementation in the Maple Symbolic Computation System at the University of Waterloo [Cha83]. We provide some tests and comparisons with alternative systems.
Phase diagrams of Ti-Al-C, Ti-Y-O, Nb-Y-O, and Nb-Al-O at 1100°C

To develop suitable coating materials for A12O3 fibers used in Ti-based metal-matrix composites, the phase diagrams of Ti-Al-C, Ti-Y-O, Nb-Y-O, and Nb-Al-0 at 1100 °C were studied. The phase equilibrium samples were prepared by hot isostatic press (HIP), annealed, and then examined by x-ray diffraction (XRD). In the Al-Ti-C ternary, the present study was concentrated on the Ti-rich corner involving Ti, TiC, α2Ti3A1, and the ternary Pphase (T3AlC). The results show that at 1100 °C, β-(Ti, Al) is in equilibrium with TiC, but not in equilibrium with the Pphase as suggested by Schuster et al. In the Ti-Y-O, Nb-Y-O, and Nb-Al-0 ternary systems, the present study shows that Ti-Y2O3, Nb-Y2O3, and Nb-Al2O3 are in equilibrium at 1100 °C.
Talk of genetics and vice versa

Does our ability to talk lie in our genes? The suspicion is bolstered by the discovery of a gene that might affect how the brain circuitry needed for speech and language develops.
Path integrals and optical potentials for elastic and inelastic scattering

Abstract When relative degrees of freedom are taken to traverse a fixed trajectory R (τ), the properties of Feynman path integrals are used to derive a series expansion of the logarithm of the internal state elastic scattering amplitude in terms of the internal relative coupling potential. Likewise transition amplitudes for inelastic scattering are expressed in terms of an exponential of an infinite series of 2 x 2 matrices. These results represent a reordering of the usual perturbation series of time dependent quantum mechanics to obtain a series expansion in the exponential as well as truncation from the space of all channels to that of only one or two (or more, if necessary). When the relative degrees of freedom are to be treated quantum mechanically, R (τ) is now the integration variable in a Feynman path integral. The above noted exponentiated series then correspond to the exact optical potentials for elastic and inelastic scattering within the Feynman path integral formulation of quantum mechanics.
Iodine Hall Thruster Propellant Feed System for a CubeSat

The components required for an in-space iodine vapor-fed Hall effect thruster propellant management system are described. A laboratory apparatus was assembled and used to produce iodine vapor and control the flow through the application of heating to the propellant reservoir and through the adjustment of the opening in a proportional flow control valve. Changing of the reservoir temperature altered the flowrate on the timescale of minutes while adjustment of the proportional flow control valve changed the flowrate immediately without an overshoot or undershoot in flowrate with the requisite recovery time associated with thermal control systems. The flowrates tested spanned a range from 0-1.5 mg/s of iodine, which is sufficient to feed a 200-W Hall effect thruster.
Effects of four sorghum varieties on the longevity of the lesser rice weevil, Sitophilus oryzae (L.)

Abstract In this study, where sorghums which differed in seed hardness were used, it was found that the adult life span of the lesser rice weevil was affected by this characteristic. For three of the varieties tested, a short adult life was associated with increasing hardness of grain. The single exception noted was with RS-610, which has moderately hard seeds, but on which the weevils survived only 1 5 as long as on the hardest variety tested. At relative humidities below 83% the difference in life span between the hardest and softest varieties was proportionally greater. The decrease in life span caused by reduction of relative humidity alone was highly significant.
Comparison of blazed and laminar profile varied-line-spacing gratings

The performance of a beamline containing a blazed and a laminar grating is reported in this paper. Two varied line spacing (VLS) gratings are currently installed in the SRC High Energy Resolution Monochromator (HERMON). The blazed grating was ruled on a conventional ruling engine. The laminar profile grating was created holographically. The grating blanks were cut from a single spherical substrate having a figure error of less than 0.2 arcseconds RMS. The theoretical resolving power of 5000 to 10000 has been achieved in the energy range of 245 to 550 eV for the medium energy grating and 500 tol 150 eVfor the high energy grating indicating correct application of the polynomial groove density to the gratings. The groove profile for the laminar grating has been measured using atomic force microscopy and is in agreement with specifications. The beamline achieves near theoretical throughput throughout its scan range. A third grating which was designed to be blazed and ion etched is currently being evaluated.
Self-induced crosslinking of factor XIII.

Abstract Activated plasma factor XIII has been found to autopolymerize as a result of self-induced crosslinking. Only the “a” subunits are involved in the crosslinking process, an a 2 dimer being produced upon urea-SDS dissociation of the polymer. The dimerization can take place between a subunits whether or not these chains have been converted to a ∗ by thrombin. Taken in context with other properties of factor XIII, the autopolymerization phenomenon suggests interesting possibilities for its evolution and participation in vertebrate hemostasis.
Isolation and alpha-particle spectrometric determination of238Pu and239,240Pu in sediments

A simple method is described for the isolation and determination of plutonium isotopes in sediments. The method involves leaching of sample with nitric acid and subsequent separation of plutonium on an anion-exchange column. Major matrix elements and several potential radiochemical interferences are removed during 8M HNO3 sample loading on the column. Thorium is removed by thorough washing with 10M HCl. Plutonium (IV) is eluted with 4M HCl. Source for alpha-particle spectrometry is prepared by LaF3 coprecipitation technique at which stage a complete separation from uranium(VI) is also achieved. The entire analytical procedure is completed in about two days.