cssi/SciSciGPT-SciSciNet huggingface dataset:
Readmission and complications after robotic surgery: experience of 10,000 operations at a comprehensive cancer center

Evaluation of safety is of paramount importance with adoption of novel surgical technology. Although robotic surgery has become widely used in oncologic surgery, analysis of safety is lacking in comparison to traditional techniques. Standardized assessment of robotic surgical outcomes and adverse events following oncologic surgery is necessary for quality improvement with innovative technology. Between 2003 and 2016, 10,013 unique robotic operations were performed in 9,858 patients. Our prospectively maintained database was retrospectively reviewed for hospital readmissions and Clavien–Dindo grade ≥ 2 complications within 30 days. Multivariable logistic regression was used to identify predictors of surgical complications and hospital readmissions. Cases were stratified by discipline: genitourinary (n = 8240), gynecologic (n = 857), thoracic (n = 457), gastrointestinal (n = 322), hepatobiliary (n = 60), ear/nose/throat (n = 44) and general (n = 33). Intraoperative complications occurred in 42 surgeries (0.4%). Postoperative complications occurred in 946 patients [9.4%, highest grade 2 (n = 574), 3 (n = 288), 4 (n = 72), 5 (n = 10)]. Most frequent complications were ileus (154, 16.3%), anemia (91, 9.6%), cardiac arrhythmia (62, 6.6%), deep vein thrombosis/pulmonary embolus (47, 5.0%), wound infection (45, 4.8%) and urinary leak (43, 4.5%). 405 patients (4.0%) required readmission. Most common causes for hospital readmission were ileus (44, 10.9%), urinary leak (23, 5.7%), urinary tract infection (23, 5.7%), intra-abdominal abscess/fluid collection (23, 5.7%), and small bowel obstruction (19, 4.7%). On multivariable analysis, longer operative time and older age predicted complications and readmissions (p ≤ 0.02). Robotic-assisted surgery appears a safe for oncologic surgery with acceptable hospital readmission and complication rates. Older age and longer operative time were associated with complications and readmission.
Awareness of predatory publishing.

Scientific open-access publishing for dissemination of research studies has resulted in numerous internet-based journals, referred to as predatory journals. These journals have lax peer review standards, accept studies of poor quality and have no proper indexing of the published manuscripts. Richtig et al 1 observed that only 70% of 188 oncologists in Germany and Austria reported an understanding of predatory journals. However, even if they claimed to know about predatory journals, they may not be able to recognise one. We aimed to test a researcher’s ability to recognise a predatory journal using a survey study. We surveyed 1270 authors who published in predatory journals. We obtained the contact information of these authors …
Chapter 15 – Hearing

Publisher Summary The inner ear of fishes contains three sensory systems. Each of these sensory systems is specialized, based on specific accessory structures, to extract different physical properties of various mechanical stimuli: a system of one, two, or three semicircular canals that extract angular acceleration stimuli in the three cardinal planes; a system of one, two, or three maculae that extract linear acceleration from the environment; the auditory system is a highly variable set of sense organs that extracts sound from the environment. Any otolithic organ in the aquatic environment can presumably accomplish this by extracting near-field particle motion in a low frequency range. Additionally, a sensory organ of largely unexplored function, the papilla neglecta exists in many fishes. The swim bladder can also form direct connections with the ear. In the case of the herring this is achieved by two anterior extensions of the swim bladder to the utricle. These bubbles end in an osseous chamber near the utricle. This specialization may enable some herrings to perceive ultrasound frequencies.
Quality of Life in Patients with Low-Risk Papillary Thyroid Microcarcinoma: Active Surveillance Versus Immediate Surgery.

ABSTRACT Objective: This study aimed to compare the quality of life (QoL) and psychological issues of patients with papillary thyroid microcarcinoma (PMC) who were under active surveillance (AS) and those who underwent immediate surgery (OP). Methods: This was a cross-sectional study conducted on 347 patients with low-risk PMC who were under AS (n = 298) or who underwent OP (n = 49). They were asked to complete two questionnaires (thyroid cancer–specific health-related QoL [THYCA-QoL] and the Hospital Anxiety and Depression Scale [HADS]). The results between the AS and OP groups were compared. Results: The mean ages of patients in the AS and OP groups were 58.6 ± 12.5 and 58.4 ± 13.1 years (P =.94), respectively, and the male ratios were 34/298 (11%) and 2/49 (4.1%) (P =.14), respectively. The median follow-up periods from diagnosis in the AS and OP groups were 56.5 months (interquartile range [IQR], 32 to 88 months) and 84 months (IQR, 64 to 130 months) (P Conclusion: PMC patients in the OP group had more complaints and were more anxious and depressed than the AS group. These findings suggest that AS is a reasonable alternative to surgery for patients with low-risk PMC from the point of view of QoL and psychology. Abbreviations: AS = active surveillance; CI = confidence interval; HADS = Hospital Anxiety and Depression Scale; LT4 = levothyroxine; OP = immediate surgery; PMC = papillary microcarcinoma; PTC = papillary thyroid carcinoma; QoL = quality of life; STAI = State-Trait Anxiety Inventory; THYCA-QoL = thyroid cancer–specific health-related quality of life; TSH = thyrotropin
Sovereign Default and the Decline in Interest Rates

Sovereign debt yields have declined dramatically over the last half-century. Standard explanations, including aging populations and increases in asset demand from abroad, encounter difficulties when confronted with the full range of evidence. We propose an explanation based on a decline in inflation and default risk, which we argue is more consistent with the long-run nature of the interest rate decline. We show that a model with investment, inventory storage, and sovereign default captures the decline in interest rates, the stability of equity valuation ratios, and the recent reduction in investment and output growth coinciding with the binding zero lower bound.
Combined carbon flows through detritus, microbes, and animals in reference and experimentally enriched stream ecosystems.

Tracking carbon (C) flow through ecosystems requires quantification of myriad biophysical processes, including C routing through microbial and metazoan food webs. Yet detailed organic matter budgets are rarely combined with simultaneous measurement of C flows supporting microbial and animal production. Here, we synthesize concurrent data sets on organic matter, microbes, and macroinvertebrates from two detritus-based stream ecosystems, one of which was subject to experimental nitrogen (N) and phosphorus (P) enrichment. Our synthesis provides new insights into C flow through forest stream ecosystems. Over 3 yr, the reference stream showed a striking balance of inputs and outputs, with a mean surplus of only 7 g C·m-2 ·yr-1 (~1% of annual inputs), presumably stored in sediments as fine particulate organic matter (FPOM). In contrast, N and P enrichment over 2 yr resulted in severe deficits of C (-576 g C·m-2 ·yr-1 or ~170% of annual inputs), a shortfall presumably met by stored C. Our data set provides an ecosystem-based estimate of the fate of forest litter C at ambient nutrient concentrations: 6.2% was leached as dissolved organic C, 40.6% and 8.5% flowed to litter-associated fungi and bacteria, respectively, 7.5% was consumed by macroinvertebrates, 1.8% was exported as coarse particles, and the remainder (35.4%) was presumably fragmented by biophysical processes. Our calculations also allowed an estimate of inputs into the heterogeneous FPOM pool, which is otherwise difficult to obtain. At naturally low nutrient concentrations, 50.7% was derived from fragmented litter, 39.1% from microbial biomass (mostly fungal), and 10.2% from macroinvertebrate egesta. Nutrient addition drove large changes in C fluxes in the experimental stream, especially in flows of leaf litter to fungi (×1.7 pretreatment) and macroinvertebrates (×2.7), and of FPOM to hydrologic export (×2.6). Our results underscore the key roles of both microbes and metazoans in controlling C flow through detritus-based ecosystems, as well as how release from persistent nutrient limitation may perturb steady-state conditions of C inputs vs. outputs. Our analysis also suggests areas for future research, including assessing the relative importance of stored vs. recycled C in fueling detrital food webs subject to altered nutrient regimes and other global-change drivers.
Music Engagement and Episodic Memory among Middle-Aged and Older Adults: A National Cross-Sectional Analysis.

Objectives To determine whether music engagement influences middle-aged and older adults' performance on episodic memory tasks. Methods Secondary data analysis of a sample (N = 4,592) of cognitively healthy adults from the 2016 Health and Retirement Study were used for this study. Multivariable regression models were used to analyze the cross-sectional differences in performance on tasks of episodic memory between participants who listened to music (n= 3,659) or sang or played an instrument (n= 989). Results On average, participants recalled 10.3 words out of a possible 20. Regression analyses showed that both music listening and singing or playing an instrument were independently associated with significantly better episodic memory. Discussion The findings provide the first population-based evidence that music engagement is associated with better episodic memory among middle-aged and older adults. Future studies should examine whether the association is causal or has a dose response.
Using Twitter to Extend Your Department’s Outreach and Visibility

Social media platforms like Twitter offer benefits for promoting and sharing scientific research. Each user becomes an instant news source for their work, and are able to report lab updates, news, and discoveries in near real time, increasing the visibility and citations of one’s research and allowing for direct and public engagement with the scientific community. Additionally, such outreach has the possibility of strengthening collaboration and engagement within one’s academic department. However, amidst the noise of a billion profiles, how can you be heard and measure your impact? The NC State Department of Chemistry has adopted an amplification method that relies on promoting departmental news through collaboration between faculty (@NCStateChem) and student organization (@NCStateChemGSA) run accounts, which are then amplified through research lab or personal community member profiles. Here we share insights into one of our social media strategies for Twitter (#ChemPack) and provide an overview of our in-house amplification network monitoring impressions and engagement rate as a metric to assess our impact.
User perceptions of automated Truck-Mounted attenuators: Implications on work zone safety

Automated Truck-Mounted Attenuators (ATMAs) have the potential to improve work zone safety by removing the human driver out of a vehicle that is positioned in work zones to absorb impact from erran...
Transfusion in Elective Proximal Aortic Reconstruction: Where Do We Currently Stand?

Background Aortic procedures are associated with higher risks of bleeding, yet data regarding perioperative transfusion in this patient population are lacking. We evaluated transfusion patterns in patients undergoing proximal aortic surgery to provide a benchmark against which future standards can be assessed. Methods Between June 2014 and July 2017, 247 patients underwent elective aortic reconstruction for aneurysm. Patients with acute aortic syndrome, endocarditis, and/or prior cardiac surgery were excluded. Transfusion data were analyzed by type of operation: ascending aorta replacement ± aortic valve procedure (group 1, n = 122, 49.4%); aortic root replacement with a composite valve–graft conduit ± ascending aorta replacement (group 2, n = 93, 37.7%); valve-sparing aortic root replacement (VSARR) ± ascending aorta replacement (group 3, n = 32, 13.0%). Results Thirty-day mortality for the entire cohort was 2.02% (5 deaths). Overall, 75 patients (30.4%) did not require any transfusion of blood or other products. Patients in groups 1 and 3 were significantly more likely to avoid transfusion than those in group 2. Mean transfusion volume for any individual patient was modest; those who underwent VSARR (group 3) required less intraoperative red blood cells (RBC) than others. Intraoperative transfusion of RBC was independently associated with an increased risk of death at 30 days. Conclusions Elective proximal aortic reconstruction can be performed without the need for excessive utilization of blood products. Composite root replacement is associated with a greater need for transfusion than either VSARR or isolated replacement of the ascending aorta.
Remote targeted electrical stimulation

The ability to generate electric fields in deep tissues remotely, without surgically implanting electrodes, could transform diagnoses and treatments of nervous system disorders. Here, we show that focal electrostimulation effects can be elicited remotely by combining two noninvasive forms of energies---magnetic and focused ultrasonic fields. The approach, based in the Lorentz equation and referred to as Lstim, electrically stimulates specified tissue targets with the precision of deep brain or spinal cord stimulation, but does not require electrode implantation. Lstim potentiated the responses of human nerves, enhancing the neuromodulatory effects of ultrasound by 74% on average. The effects showed a double dissociation---a significant and substantial increase in nociceptive responses, yet a significant reduction in tactile responses. In line with the Lorentz equation, Lstim was only observed when nerves were oriented perpendicularly to the magnetic and ultrasonic fields. A sham condition showed no effects. Both the ultrasonic and the induced electric fields were well below the respective safety indices, and no detrimental effects were detected. Lstim uniquely integrates noninvasiveness, sharp focus, and the efficacy of electrical stimulation. The approach has the potential to provide a noninvasive tool to dissect brain function in humans and to diagnose the neural circuits involved in nervous system disorders. Moreover, this effect should be taken into account when ultrasound is applied inside MRI.
Subdomain Structure of Carbamyl Phosphate Synthetase

The overall biosynthetic reaction, catalyzed by carbamyl phosphate synthetase (CPSase, EC 6.3.5.5) occurs in a series of four partial reactions which are catalyzed by different domains or subunits of the enzyme and must be precisely coordinated.1
Radioimmunoassay Measurement of Secretin Half-Life in Man

High titer antibodies to secretin were produced in rabbits by immunization with purified porcine secretin (from GIH) conjugated to bovine serum albumin in complete Freund's adjuvant. Synthetic porcine secretin (from Squibb) was radiolabeled with 125 I using chloramine-T and radiosecretin was purified using talc-silica and fibrocellulose powder. Specificity of antibodies to secretin was extensively evaluated in studies examining (1) cross-reactivity with other naturally occurring hormones, (2) parallelism of serum dilutions and secretin standards, (3) quantitative recovery of secretin added to serum samples, and (4) changes in circulating immunoreactive secretin in response to intraduodenal acidification. The mean fasting serum secretin concentration in 10 dogs was 65 ± 5 (SEM) pg per ml and in 21 healthy human volunteers it was 69 ± 5 pg per ml. In response to intraduodenal instillation of 10 mEq of HCl, portal venous secretin concentrations increased from a mean fasting value of 52 to 450 pg per ml within 2 min; peripheral venous secretin increased from 66 to 229 pg per ml within 5 min. No significant changes in peripheral serum immunoreactive secretin concentrations were identified in dogs after a protein meal. Intravenously administered secretin in man disappeared from the circulation with mean half-life of 4.06 ± 0.82 (sem) min.
Charting Olfactory Maps

Receptors that guide olfactory neurons to the brain act not only at the starting point of signal transduction but also within the cell to trigger expression of other guidance molecules.
Silicon radiation detectors

The rapid progress of the past 20 years in silicon radiation detectors is reviewed. The availability of silicon as an almost ideal semiconductor material is one of the main reasons for this progress. The well-defined properties of the silicon-silicon dioxide interface allowed the development of detector structures beyond the structure of a classical diode detector, which was practically the only silicon detector structure 20 years ago. All new structures make use of an electric field parallel to the large surface of the detector. Improvements in the production of silicon detectors has lead to a substantial decrease of the detector leakage current. These detectors can achieve their best performance very close to or at room temperature.
Reports of Life Skills Training for Students with Intellectual Disabilities in and out of School.

Background Life skills can be critical to the success of individuals with intellectual disabilities (ID) in terms of postschool outcomes. Yet, research suggests a decreasing emphasis on the acquisition of life skills in school for students with ID, raising the question if students then receive training in these areas after graduation. Method This study represented a secondary analysis of the National Longitudinal Transition Study-2 data to understand the reported receipt of life skills instruction in school and out of school for individuals with mild and moderate/severe ID. Frequency distributions, significant tests and a t-test were used to understand receipt of life skills in and out of school for both individuals with mild and moderate/severe ID. Results The results suggest low-reported receipt of life skills instruction/training in school and postschool for individuals with mild ID, few students with moderate/severe ID report receiving life skills training out of school, and receipt of life skills instruction in school is not related to receipt of life skills training/therapy after school by either individuals with mild ID or moderate/severe ID. Conclusions Given the current educational policy situation (i.e. a predisposition towards inclusive general education placements for students with disabilities and participation in the accountability system for all students), educators who believe in the value of a life skills curriculum will need to be creative in its implementation and look towards transition plan and activities to provide students with the needed training. Regardless, teachers will need to rectify providing students with the academic skills they need to be successful on a general large-scale assessment with providing them with the life skills (e.g. independent living, daily living, financial) to be successful after school in employment and independent living.
Lack of influence of sickle cell trait on fertility and successful pregnancy.

Abstract Hemoglobin types have been determined in more than 1,900 Negro girls and women from Alachua County, Florida. Sickle cell trait had no discernible effect on fertility or abortion. Because of increasing survival of patients with homozygous hemoglobin (Hgb) S disease, the frequency of the sickle gene will probably become fairly stable in the United States. Large-scale screening programs to identify carriers of the sickle gene, combined with genetic counseling and family planning, are indicated if cases of sickle cell anemia are to be prevented in the future.
Deconstructing the risk principle

T he article by Zweig, Yahner, and Redcross (2011, this issue) is one of the strongest tests to date of the risk principle. Offenders were randomly assigned to a transitional jobs program. The risk of reoffending levels—high, medium, and low—were based on exogenous factors that were in place prior to the intervention. The results showed that the transitional job program reduced recidivism relative to control group participants for the high-risk offenders but not for the lowor medium-risk offenders. One of the few ways that Zweig et al. could have improved on their design would have been to use preexisting risk levels as a blocking variable and to assign offenders randomly to the intervention and control groups within each of these risk levels. In this policy essay, we accept the premise of the risk principle, but we pose certain questions that should be addressed by criminologists to further our understanding of the mechanisms at work, and to enhance its utility as a public policy tool. We start by deconstructing elements of the risk principle, acknowledging the original statement by Andrews, Bonta, and Hoge (1990). We also give credit to expositions by Lowenkamp and Latessa (2004) andLowenkamp, Latessa, andHolsinger (2006) in expressing the relationship among risk, supervision, and program intensity.
Comparative planetary mineralogy: V/(Cr + Al) systematics in chromite as an indicator of relative oxygen fugacity

As our contribution to the new "Oxygen in the Solar System" initiative of the Lunar and Planetary Institute and the NASA Cosmochemistry Program, we have been developing oxygen barometers based largely on behavior of V which can occur in four valence states V2+, V3+, V4+, and V5+, and record at least 8 orders of magnitude of fO2. Our first efforts in measuring these valence proportions were by XANES techniques in basaltic glasses from Earth, Moon, and Mars. We now address the behavior of V valence states in chromite in basalts from Earth, Moon, and Mars. We have been looking for a "V in chromite oxybarometer" that works with data collected by the electron microprobe and thus is readily accessible to a large segment of the planetary materials community. This paper describes very early results that will be refined over the next two years.
Empirical Transition Probability Indexing Sparse-Coding Belief Propagation (ETPI-SCoBeP) Genome Sequence Alignment:

The advance in human genome sequencing technology has significantly reduced the cost of data generation and overwhelms the computing capability of sequence analysis. Efficiency, efficacy, and scalability remain challenging in sequence alignment, which is an important and foundational operation for genome data analysis. In this paper, we propose a two-stage approach to tackle this problem. In the preprocessing step, we match blocks of reference and target sequences based on the similarities between their empirical transition probability distributions using belief propagation. We then conduct a refined match using our recently published sparse-coding belief propagation (SCoBeP) technique. Our experimental results demonstrated robustness in nucleotide sequence alignment, and our results are competitive to those of the SOAP aligner and the BWA algorithm. Moreover, compared to SCoBeP alignment, the proposed technique can handle sequences of much longer lengths.
Synthesis and secretion of proteins by released malarial parasites

Abstract Controlled mechanical homogenization of Plasmodium falciparum-infected erythrocytes releases parasites of a quality sufficient for studying the export of newly synthesized plasmodial proteins. Protein synthesis occurs within intact released parasites as defined by resistance of acid-insoluble incorporation of radiolabel to high levels of exogenously added EDTA, hexokinase, and RNaseA. While exogenously added ATP and erythrocyte cytosol were not essential for biosynthetic activity at levels comparable to that seen in infected erythrocytes, the addition of an extracellular ATP regenerating system (ARS) stimulated the synthesis of parasite proteins. Conversely, parasite viability and biosynthetic activity are decreased by the addition of a non-hydrolyzable ATP analogue (ATPγS), ADP, or ATP in the absence of a regenerating system. These data suggest a metabolic interdependence between extracellular energy metabolism and biosynthetic functions within the parasite. The export of a predominant subset of proteins was retarded in the presence of Brefeldin A, indicating the existence of a classical secretory pathway characteristic of that seen in higher eukaryotic cells. Interestingly, a Brefeldin A-insensitive component of export was also consistently observed; this may suggest the existence of an additional alternative secretory mechanism in malaria.
Optical design of two-mirror widefield cameras for large telescopes

Many large optical telescopes have a wide field camera as one of their primary instruments. Camera designs with all reflective surfaces are useful because they give stable image quality over a broad spectral band. Systems with two conic mirrors can correct the residual aberrations, field curvature and astigmatism, of Ritchey-Chretien telescopes. We present first- and third-order optical design relations which can facilitate the formation of design concepts during preliminary trade studies. We apply the relations to the Hubble Space Telescope in the design of a new wide field camera which compensates the existing spherical aberration, as well as the astigmatism and field curvature, of the telescope.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Management of a parturient with an acute exacerbation of idiopathic pulmonary haemosiderosis and posterior spinal instrumentation

Idiopathic pulmonary haemosiderosis (IPH) is a rare condition associated with diffuse alveolar haemorrhage and pulmonary fibrosis. We describe the anaesthetic management of a parturient with a history of posterior spinal fusion presenting with an acute exacerbation of IPH necessitating vaginal delivery at 34 weeks gestation. We used a spinal catheter for labour analgesia and bilevel positive airway pressure (BIPAP) ventilation to improve oxygenation during labour. An arterial line sited to allow frequent arterial blood gas sampling also facilitated continuous cardiac output monitoring. The use of a carefully titrated neuraxial block for analgesia, in conjunction with BIPAP, was associated with minimal haemodynamic and respiratory compromise during labour in this patient.
Latent Root Regression: Large Sample Analysis

Large sample properties of statistics used in latent root regression analysis are investigated by examining the matrix of correlations among the predictor and response variables as the sample size becomes infinite. The latent roots and latent vectors of the asymptotic correlation matrix are derived for specific model configurations of interest. From the study of the asymptotic latent roots and latent vectors, a new statistic is proposed for use in detecting nonpredictive multicollinearities.
PROBLEMS ON THE FRONTIERS BETWEEN GENERAL RELATIVITY AND DIFFERENTIAL GEOMETRY

The basic principles of general relativity are reviewed in brief outline. Some of the exact solutions of Einstein's equations are reviewed and new insights won from these solutions and new issues that have come to light in this way are cited. These issues are recapitulated in the context of differential geometry. (W.D.M.)
Comparison of Tetradic WAIS-III Short Forms in Predicting Full Scale IQ Scores in Neuropsychiatric Clinic Settings

Patients from two neuropsychology clinics (n = 283) were divided into model development (n = 189) and validation samples (n = 94) with proportional representation from each clinic. Three regression based models of four WAIS-III subtests were developed and cross-validated to evaluate their FSIQ estimation accuracy: (1) an optimized stepwise regression model derived from the development sample (Comprehension, Matrix Reasoning, Similarities, and Picture Arrangement), (2) an a priori WASI based model (Similarities, Matrix Reasoning, Vocabulary, and Block Design), and (3) an a priori model with relatively rapidly administered subtests from each Index Score factor of the WAIS-III (Information, Picture Completion, Arithmetic, and Digit Symbol-Coding). The models produced good (92 to 97%) FSIQ estimation accuracy within 10 points of FSIQ with none of these models performing significantly better than another. The utility of clinical use of short form FSIQ estimation is a function of accuracy needed versus administration time reduction and ease for the patient.
RON5 Is Critical for Organization and Function of the Toxoplasma Moving Junction Complex

Apicomplexans facilitate host cell invasion through formation of a tight-junction interface between parasite and host plasma membranes called the moving junction (MJ). A complex of the rhoptry neck proteins RONs 2/4/5/8 localize to the MJ during invasion where they are believed to provide a stable anchoring point for host penetration. During the initiation of invasion, the preformed MJ RON complex is injected into the host cell where RON2 spans the host plasma membrane while RONs 4/5/8 localize to its cytosolic face. While much attention has been directed toward an AMA1-RON2 interaction supposed to occur outside the cell, little is known about the functions of the MJ RONs positioned inside the host cell. Here we provide a detailed analysis of RON5 to resolve outstanding questions about MJ complex organization, assembly and function during invasion. Using a conditional knockdown approach, we show loss of RON5 results in complete degradation of RON2 and mistargeting of RON4 within the parasite secretory pathway, demonstrating that RON5 plays a key role in organization of the MJ RON complex. While RON8 is unaffected by knockdown of RON5, these parasites are unable to invade new host cells, providing the first genetic demonstration that RON5 plays a critical role in host cell penetration. Although invasion is not required for injection of rhoptry effectors into the host cytosol, parasites lacking RON5 also fail to form evacuoles suggesting an intact MJ complex is a prerequisite for secretion of rhoptry bulb contents. Additionally, while the MJ has been suggested to function in egress, disruption of the MJ complex by RON5 depletion does not impact this process. Finally, functional complementation of our conditional RON5 mutant reveals that while proteolytic separation of RON5 N- and C-terminal fragments is dispensable, a portion of the C-terminal domain is critical for RON2 stability and function in invasion.
Aggregation of many coupled consecutive first order reactions

Abstract This work investigates the behavior of a mixture in which many coupled irreversible consecutive first order reactions occur and examines the errors involved in representing it as a pseudo ternary system. It is shown that the behavior of the aggregated concentrations can differ in a qualitative manner from that of a single specie and that the functional form and the parameters of empirical rate expressions describing the grouped concentrations may depend on the composition as well as total concentration of the feed. Thus, empirical rate expressions may lead to pitfalls when the effective feed composition is changed due to mixing, recycle or variation in total pressure. It is shown that upper and lower bounds on the aggregated concentrations can be obtained from initial rate information. These bounds are used to predict the effects of mixing and recycle as well as to estimate the maximal errors associated with specific aggregation procedures. An analysis of the errors involved in aggregation of several organic isomers participating in consecutive substitution reactions is used to illustrate the applicability of the bounds.
THE DETERMINATION OF ZIRCONIUM IN AIR

A procedure is described for the analysis of air samples for zirconium. Calorimetric measurements of zirconium were made after isolation from air. (C.H.)
PFGE MAPPER: a tool to aid in the analysis of pulse field gel electrophoresis maps

Pulse field gel electrophoresis mapping is an important technique for characterizing large segments of DNA and constructing long-range restriction maps. We have developed a tool, PFGE MAPPER, to aid in the construction of pulse field electrophoresis gel maps. This tool helps construct pulse field gel maps from single and double digest experiments visualized by hybridization with single copy probes. The program is written in Think C and runs on Macintosh computers. An intuitive interface allows the user to interactively modify fragment sizes or errors, select fragments for analysis and recalculate the maps. Maps can be printed or saved for later viewing. After constructing and saving several maps in a region, PFGE MAPPER can be used to refine and extend the overall map by merging individual maps. This tool should be useful for constructing long-range restriction maps of genomic DNA and yeast artificial chromosomes.
Investigations of Angular Scattering and Multipath Properties of Tropospheric Propagation of Short Radio Waves beyond the Horizon

Experiments designed to investigate the potential communications capacity of uhf and shf tropospheric propagation beyond the radio horizon were conducted by the MIT Lincoln Laboratory on circuits of from 161 to 188 miles in length along the coastal regions of the northeastern United States. Some of these tests were made in cooperation with the Bell Telephone Laboratories and the late Major E. H. Armstrong. A study of the following aspects of tropospheric propagation was considered necessary in order to gain a better understanding of the factors involved in design of communications systems: 1. The extent of useful communication bandwidths. 2. Variation of uhf and shf median signal levels over a full seasonal cycle. 3. The range and rates of fading. 4. The effective gain of highly directional antenna systems. 5. The effect of multipath propagation on modulated signals. 6. The polarization properties of scattered fields. 7. The angular dependence of scattered fields. Such experiments made from 1953 to 1955 have confirmed the utility of tropospheric circuits for wide-band communication systems and have provided information useful in the evaluation of tropospheric propagation mechanisms.
Surgical shunts and TIPS for variceal decompression in the 1990s.

Abstract Background. In the 1990s, liver transplantations and transjugular intrahepatic portosystemic shunts (TIPS) have become the most common methods to decompress portal hypertension. This center has continued to use surgical shunts for variceal bleeding in good-risk patients who continue to bleed through endoscopic and pharmacologic treatment. This article reports this center's experience with surgical shunts and TIPS shunts from 1992 through 1999. Methods. Sixty-three patients (Child A, 43 patients; Child B, 20 patients) received surgical shunts: distal splenorenal, 54 patients; splenocaval, 4 patients; coronary caval, 1 patient; and mesocaval, 4 patients. Sixty-two patients had refractory variceal bleeding, and 1 patient had ascites with Budd-Chiari syndrome. Two hundred patients (Child A, 24 patients; Child B, 62 patients; Child C, 114 patients) received TIPS shunts. One hundred forty-nine patients had refractory variceal bleeding, and 51 patients had ascites, hydrothorax, or hepatorenal syndrome. Data were collected by prospective databases, protocol follow-up, and phone contact. Results. The 30-day mortality rate was 0% for surgical shunts and 26% for TIPS shunts; the overall survival rate was 86% (median follow-up, 36 months) for surgical shunts and 53% (median follow-up, 40 months) for TIPS shunts. For surgical shunts, the portal hypertensive rebleeding rate was 6.3%; the overall rebleeding rate was 14.3%. For TIPS shunts, the overall rebleeding rate was 25.5% (30-day, 9.4%; late, 22.4%). There were 4 reinterventions for surgical shunts (6.3%); the reintervention rate for TIPS shunts in the bleeding group was 33%, and the reintervention rate in the ascites group was 9.5%. Encephalopathy was severe in 3.1% of the shunt group and mild in 17.5%; this was not systematically evaluated in the TIPS shunts patients. Conclusions. Surgical shunts still have a role for patients whose condition was classified as Child A and B with refractory bleeding, who achieve excellent outcomes with low morbidity and mortality rates. TIPS shunts have been used in high-risk patients with significant early and late mortality rates and have been useful in the control of refractory bleeding and as a bridge to transplantation. The comparative role of TIPS shunts versus surgical shunt in patients whose condition was classified as Child A and B is under study in a randomized controlled trial. (Surgery 2000;128:540-7.)
Generation and synchronous tree-adjoining grammars

Tree-adjoining grammars (TAG) have been proposed as a formalism for generation based on the intuition that the extended domain of syntactic locality that TAGs provide should aid in localizing semantic dependencies as well, in turn serving as an aid to generation from semantic representations. We demonstrate that this intuition can be made concrete by using the formalism of synchronous tree-adjoining grammars. The use of synchronous TAGs for generation provides solutions to several problems with previous approaches to TAG generation. Furthermore, the semantic monotonicity requirement previously advocated for generation grammars as a computational aid is seen to be an inherent property of synchronous TAGs. Les grammaires ?arbres adjoints possedent un domaine de localite syntaxique etendu. A priori cette měme propriete permet aussi de localiser certaines dependences semantiques. Basees sur cette intuition, les grammaires ?arbres adjoints ont ete proposees comme formalisme pour la generation de texte. Dans ce papier, les auteurs montrent comment les grammaires ?arbres adjoints synchrones concretised cette intuition de maniere precise. L'utilisation des grammaires ?arbres adjoints synchrones resout plusieurs problemes lies a des approches precedentes pour la generation de texte. De plus, la monotonicite semantique, propriete souvent preferee pour la generation de texte, est inherente aux grammaires ?arbres adjoints synchrones.
A review of pedogenic zonation in well-drained soils of the Southern Circumpolar Region

Abstract The concept of zonality is used to link well-drained mineral soils and processes along a bioclimatic gradient extending from ca. 48° to 87° S, including southernmost Chile, the subantarctic islands, and maritime and continental Antarctica. The following environmental factors decline along this gradient: mean annual temperature and precipitation and the type and number of plant species. Six pedological zones (along with representative soils) are identified along the gradient: (1) Subantarctic Forest Zone (Podzol?), (2) Subantarctic Low Tundra zone, (3) Subantarctic High Tundra Zone (Subantarctic Brown soil, without permafrost), (4) Antarctic Sub-Polar Desert Zone (Subantarctic Brown soil, with permafrost), (5) Antarctic Polar Desert Zone (Red Ahumisol), and (6) Cold Desert Zone (Ahumisol). Zonal mineral soils in the Subantarctic Forest and Low Tundra Zones are rare, because large amounts of precipitation (>-2500 mm) and cool summers have led to thick accumulation of peat. Whereas the processes of rubification, melanization, and peat accumulation decline in relative magnitude southward, the processes of salinization and desert pavement formation increase in relative importance along this bioclimatic gradient. Carbonation and pervection (silt and clay migration) are maximized in the Subantarctic Tundra and Antarctic Polar Desert Zones. Because of the limited amount of land between 40° and 65° S and the presence of the Antarctic Convergence, comparable pedogenic zones occur at lower latitudes in the Southern than in the Northern Circumpolar Region.
The Heterogeneous Motility of the Lyme Disease Spirochete in Gelatin Mimics Dissemination through Tissue

The Lyme disease spirochete Borrelia burgdorferi exists in nature in an enzootic cycle that involves the arthropod vector Ixodes scapularis and mammalian reservoirs. To disseminate within and between these hosts, spirochetes must migrate through complex, polymeric environments such as the basement membrane of the tick midgut and the dermis of the mammal. To date, most research on the motility of B. burgdorferi has been done in media that do not resemble the tissue milieus that B. burgdorferi encounter in vivo. Here we show that the motility of Borrelia in gelatin matrices in vitro resembles the pathogen's movements in the chronically infected mouse dermis imaged by intra-vital microscopy. More specifically, B. burgdorferi motility in mouse dermis and gelatin is heterogeneous, with the bacteria transitioning between at least three different motility states that depend on transient adhesions to the matrix. We also show that B. burgdorferi is able to penetrate matrices with pore sizes much smaller than the diameter of the bacterium. We find a complex relationship between the swimming behavior of B. burgdorferi and the rheological properties of the gelatin, which cannot be accounted for by recent theoretical predictions for microorganism swimming in gels. Our results also emphasize the importance of considering borrelial adhesion as a dynamic rather than a static process.
Bouncing and cyclic string gas cosmologies

We show that, in the presence of a string gas, simple higher-derivative modifications to the effective action for gravity can lead to bouncing and cyclic cosmological models. The modifications bound the expansion rate and avoid singularities at finite times. In these models the scale factors can have long loitering phases that solve the horizon problem. Adding a potential for the dilaton gives a simple realization of the pre-big bang scenario. Entropy production in the cyclic phase drives an eventual transition to a radiation-dominated Universe. As a test of the Brandenberger-Vafa scenario, we comment on the probability of decompactifying three spatial dimensions in this class of models.
Activation Energy Asymptotics Applied to Burning Carbon Particles.

Abstract The method of activation energy asymptotics is used to describe the entire history of a carbon particle suddenly immersed in a hot oxidizing ambient. Under appropriate conditions, which are established by the analysis, the history of the particle is shown to consist principally of a heat-up period during which no significant chemical reaction takes place followed by a period involving diffusion-limited mass loss and terminating in complete particle consumption. Between these two extended periods brief ignition and postignition periods are described. The final demise of the particle occurs in a complex extinction period during which all the quantities describing the particle behavior undergo large variations.
Comparative microhabitat use of ecologically similar benthic fishes

Although benthic insectivorous fishes such as darters and sculpins represent a significant component of riffle communities, few studies have compared the habitat use of these non-related but ecologically similar fishes. The objectives of this study were to examine the habitat use of Etheostoma olmstedi (tessellated darter) compared to Cottus bairdi (mottled sculpin) in Nescopeck Creek and Cottus cognatus (slimy sculpin) in Jack's Creek, Pennsylvania through underwater observation. Etheostoma olmstedi occupied habitats with significantly deeper waters than those available, whereas adult and young of the year Cottus occupied habitats with significantly faster water velocities than those available. Canonical discriminant analysis revealed microhabitat partitioning between E. olmstedi and each Cottus species. Cottus bairdi and C. cognatus occupied significantly shallower habitats with faster water velocities than E. olmstedi. Sculpin species were observed most frequently under substrate whereas E. olmstedi occurred most frequently on the top surface of the substrate. Hurlbert's standardized niche breadth values indicated that C. bairdi and C. cognatus were habitat specialists with regard to water velocity measures, but exhibited generalistic patterns of depth and substrate size use. Etheostoma olmstedi was a habitat specialist with respect to depth, but exhibited generalistic patterns of resource use for substrate size. Differential habitat use by these benthic fishes is consistent with the hypothesis that resource partitioning facilitates species coexistence among stream fishes.
Evidence that science locus of control orientation can be modified through instruction

A desire to foster enduring, positive attitudes toward science teaching among elementary school teachers led to study of self-perceptions. On the basis of evidence for strong links between locus of control orientation and attitudes, an attempt was made to enhance internality through instruction. A quasiexperimental research strategy was employed to compare the effects of two instructional treatments, with pretest measures being used to check the initial equivalence of treatment groups, and analysis of covariance (ANCOVA) being used to test treatment effects. Both treatments incorporated strategies known to have positive effects on attitudes, but the experimental treatment was novel in its emphasis on self-management, goal clarification, and individualized course expectations. There was found by ANCOVA to be a significant (p ≦ 0.05) difference in science locus of control (SciLOC) orientation between groups following treatment, with subjects exposed to the experimental treatment exhibiting greater internality. Quantitative comprehension and subject age were employed as covariates of SciLOC orientation, and subject gender was employed as a moderator variable. Though the treatment effect is small, accounting for 3% of the variance in SciLOC orientation, control orientation is shown susceptible to educational intervention. These results encourage attention to teacher attitudes from a rather new perspective, and they raise several interesting research questions regarding instructional methods and the long-term effects of enhancing internality.
The basis for the molecular recognition and the selective time-gated luminescence detection of ATP and GTP by a lanthanide complex

Two molecular probes for the detection of nucleotides are presented. The positively charged [Tb-DOTAm-Phen]3+ responds only to purine nucleotides and selectively detects GTP and ATP over GDP/GMP and ADP/AMP, respectively. The neutral Eu-DOTA-Phen complex, on the other hand, is selective for purines over pyrimidines but does not distinguish between tri-, di- and monophosphate nucleotides. Both probes possess long luminescence lifetimes that readily enable time-gated experiments and complete removal of any autofluorescence background. The decrease of the Stern–Volmer constants with temperature is indicative of a static mechanism of quenching in agreement with the formation of a stacked phenanthridine–purine complex. The selectivity of the probes for purines over pyrimidines is due to a higher binding affinity and quenching ability of the more extended purines for the phenanthridine chromophore. The selectivity of the positively charged terbium complex for the tri- over the di- and mono-phosphate nucleotides is due to weak electrostatic interactions with the negatively charged phosphates of ATP and GTP, as evidenced by the lack of any selectivity for ATP/ADP/AMP or GTP/GDP/GMP by the neutral europium complex. Both the selective terbium complex and its non-responsive europium analog can be used concomitantly in the same solution as neither probe affects the response of the other. Simultaneous use of the two chemosensors enables more accurate ratiometric detection of ATP to ADP or GTP to GDP conversion and continuous monitoring of kinase reactions.