cssi/SciSciGPT-SciSciNet huggingface dataset:
Trivalent ion hydrolysis reactions. II: Analysis of electron density distributions in metal-oxygen bonds

Density functional theory calculations are applied to a series of trivalent hexaquo metal complexes to determine whether systematic properties exist in the electron density distribution of the metal−oxygen (M−O) bonds in relation to the proton binding energy. Bader metal ion charges, radii, and M−O bond critical point properties are computed and correlations are sought that transcend conventionally ascribed factors affecting hydrolysis behavior, such as position in the periodic table and d-orbital filling. Charge-to-radius relationships are found to be unimproved by these methods. At the M−O bond critical points, while no correlation could be established with the electron density, distinct trends in the proton binding energy are unveiled by the Laplacian, owing principally to systematics in the curvature |λ3| along the M−O bond path. The ellipticity of the bonds can reflect a π interaction between the metal cation and water ligands for metal cations in which the t2g d-orbital set is asymmetrically occupie...
We Can Cut Global Warming

It’s time to recognize that Global Warming is a FACT (visible in the NASA photo below), which means the U.S. needs to reduce our CO2 emissions by a national energy transition from oil and carbon to hydrogen and solar fuels. Don’t believe it? Just look at the photos and ask every “Global Warming denier” (especially President Trump) to explain the 300,000 square miles of sea-ice between the ice cap over the North Pole and the red line that melted between 1979 and 2012.
Prevalence of Specific Types of Pain Diagnoses in a Sample of United States Adults.

Background Patients with pain conditions place significant demands on health care services globally. Health economists have reported the annual economic cost of pain in the United States as high as $635 billion. A common challenge in treating patients suffering from chronic pain conditions is accurate diagnosis and treatment. Objective The aim of this study was to determine the modern-day prevalence of individual types of pain diagnoses in adults. Study design Retrospective analysis of Truven MarketScan® Commercial and Medicare Supplemental database. Setting United States patient population with a pain diagnoses from 2000 to 2012. Methods Multivariate analysis was used to determine the individual prevalence of specific types of pain diagnoses over a 13-year period. Patients We grouped the 6,575,999 patients with ICD-9 pain diagnoses into pain groupings. Results We determined the prevalence of pain groupings as back pain (74.7%), chronic pain (10.4%), complex regional pain syndrome (1.2%), degenerative spine disease (63.6%), limb pain (50.0%), neuritis/radiculitis (52.8%), and post-laminectomy syndrome (14.8%). Limitations Retrospective and non-randomized study, with a patient cohort that is weighted towards recent years and commercial insurance. Coding discrepancies that are recorded and collected for patients. Conclusions The demographic differences and similarities within the subgroups highlighted the concept that pain diagnoses should be considered as separate, but related entities. The present study helps us to better understand the frequency of specific pain diagnoses, and directs future studies to appropriately focus on pain diagnoses based on prevalence. This will allow increased understanding of the variation in pain diagnoses and prevent over-generalization in studies examining pain patients to more accurately reflect the varied subtypes and their economic impact.Duke University Institutional Review Board Protocol: 00053624Key words: Pain diagnoses, CRPS, neuritis, radiculitis, limb pain, degenerative spine disease, back pain, chronic pain, post-laminectomy pain, prevalence, MarketScan.
‘The people’ exposed: spatio-racial-affective alterity in Haitian popular protest

Beginning in 2013, urban Haitians staged several antigovernment protests that eventually led, in 2016, to the removal of President Michel Martelly without an elected successor. This protest movemen...
Glucose-6-phosphate dehydrogenase is not essential for K-Ras-driven tumor growth or metastasis

The enzyme glucose-6-phosphate dehydrogenase (G6PD) is a major contributor to NADPH production and redox homeostasis and its expression is upregulated and correlated with negative patient outcomes in multiple human cancer types. Despite these associations, whether G6PD is essential for tumor initiation, growth, or metastasis remains unclear. Here, we employ modern genetic tools to evaluate the role of G6PD in lung, breast, and colon cancer driven by oncogenic K-Ras. Human HCT116 colorectal cancer cells lacking G6PD exhibited metabolic indicators of oxidative stress, but developed into subcutaneous xenografts with growth comparable with that of wild-type controls. In a genetically engineered mouse model of non-small cell lung cancer driven by K-Ras G12D and p53 deficiency, G6PD knockout did not block formation or proliferation of primary lung tumors. In MDA-MB-231-derived human triple-negative breast cancer cells implanted as orthotopic xenografts, loss of G6PD modestly decreased primary site growth without ablating spontaneous metastasis to the lung and moderately impaired the ability of breast cancer cells to colonize the lung when delivered via tail vein injection. Thus, in the studied K-Ras tumor models, G6PD was not strictly essential for tumorigenesis and at most modestly promoted disease progression. SIGNIFICANCE: K-Ras-driven tumors can grow and metastasize even in the absence of the oxidative pentose pathway, a main NADPH production route.
A Demographic Framework for the 1932–1934 Famine in the Soviet Union

Research on the 1932–1934 famine in the Soviet Union (or Famine) has reached the point where some analytical and theoretical synthesis is needed. We present a framework that provides a structure fo...
Impact of parity on biomechanical risk factors for knee OA initiation.

Abstract Background Women are twice as likely as men to develop knee osteoarthritis (OA), and with it experience greater losses of physical function and disability. A change in the mechanical environment of the joint is a key initiating factor for knee OA. Differences in morphology, joint injury risk, and hormonal shifts in mid-life are often considered factors which increase OA risk for women. Pregnancy, a time of significant hormonal, morphological, and biomechanical change, has received comparably less attention. If morphological and biomechanical changes persist postpartum, this could increase OA risk for parous (childbearing) women. Research question Are lower limb gait mechanics different between healthy nulliparous (non-childbearing) and parous (childbearing) women? Methods Twenty-eight self-reported not pregnant female participants (14 parous, 14 nulliparous) were recruited for the study. Nulliparous participants had never given birth to a child. Parous participants had given birth to at least one full-term infant (37–42 weeks) without complications between one to five years before data collection. Motion capture of participants’ preferred, fast, and set (1.4 m/s) walking speeds was conducted. Repeated measures ANOVA were performed to test for significant group differences in joint kinematics and kinetics. Results There was a significant main effect of group indicating a larger knee flexion angle at toe off (p = 0.0002), smaller knee extension moment at heel strike (p = 0.0006), smaller first peak knee flexion moment (p = 0.040), and smaller peak hip adduction moment for the parous group compared to the nulliparous group (p = 0.003). Static Q-angle did not differ between groups. Significance Alteration in mechanics from the habitual loading pattern are thought to increase risk of OA. Smaller knee moments in post-partum women could alter the mechanical stimulus to cartilage, and should be investigated in conjunction with cartilage health measures to determine the link with OA initiation.
A 10-MHz DAB Hysteretic Control Switching Power Converter for 5G IoT Power Delivery

In this article, a 10-MHz switching power converter is introduced to satisfy stringent requirements on 5G mobile Internet-of-Things (IoTs) power delivery. To achieve nanosecond power flipping, the converter utilizes a double adaptive bound (DAB) hysteretic control to improve load transient performance. A synchronized dc resistance offset cancellation scheme is naturally embedded to enhance load regulation accuracy while retaining fixed frequency operation. The controller circuit can be easily reconfigured to achieve a power scalable operation, which facilitates the converter with adaptive system power delivery capability to achieve high efficiency over a wide power range. An integrated circuit prototype is fabricated using a 180-nm CMOS process with an active die area of 0.175 mm2, achieving a peak power density of 14.3 W/mm2. In response to 1 A/3 ns load increase/decrease between zero and maximum power, it achieves 1% settling time of 247 ns/387 ns with 31 mV/60 mV voltage droop, respectively. With a nominal switching frequency of 10 MHz, the switching frequency variations are controlled below 0.1% despite of the use of a hysteretic control. And the output regulation accuracy is improved with only 0.3% error. Thanks to the proposed power scalable reconfiguration and adaptive power delivery, the converter achieves above 80% efficiency over 99.9% of 2.5-W full power range with a peak efficiency of 91%.
Misunderstanding the First Nuclear Crisis with North Korea: The Inconvenient Science in Negotiations

In this chapter, Robert Gallucci highlights the review of one negotiation and agreement, which had political, technical, and scientific elements to it, which were poorly understood, when the policy was being debated. He suggests that the same may be true of other such agreements, be they bilateral strategic arms control agreements with the Russians or multilateral agreements of the kind negotiated with Iran. To draw useful lessons from the history of the first nuclear crisis with North Korea, we need to understand the scientific and technical issues that drove the negotiations between the DPRK and the United States in 1993 and 1994. But at four critical points during the negotiations, neither the press nor senior officials seemed to have understood the technology upon which decisions and assessments were being made. Complex issues were distorted to produce a simpler, more convenient narrative. This suggests that we should be careful in our analysis of this and other negotiations that turn on scientific calculations.
Measurement of flow maldistribution induced by the Ledinegg instability during boiling in thermally isolated parallel microchannels

Abstract Flow boiling in a network of heated parallel channels is prone to instabilities that can cause uneven flow distribution, thereby degrading the heat transfer performance of the system and limiting predictability. This study experimentally investigates flow maldistribution between two parallel microchannels that arises due to the Ledinegg instability. The channels are heated uniformly and are thermally isolated from each other, such that both channels are subjected to the same input power regardless of the flow distribution. The channels are hydrodynamically connected in parallel and deionized water is delivered at a constant total flow rate shared by both channels. Direct measurements of the flow rate, wall temperature, and pressure drop in individual channels are performed simultaneously with flow visualization. At low power levels, when both channels remain in the single-phase liquid regime, the flow is evenly distributed between the channels and they attain the same wall temperature. As the power is increased, boiling incipience in one of the channels triggers the Ledinegg instability, which causes the flow to become maldistributed and induces a temperature difference between the channels. The severity of flow maldistribution, as well as the temperature difference between the channels, grows with increasing power. In the most extreme condition measured in this study, 96.5% of the total flow rate is directed to the channel operating in the single-phase liquid regime, while the boiling channel is starved and receives just 3.5% of the flow. The quantitative account of the flow maldistribution and temperature non-uniformity presented here provides a mechanistic understanding of the effects of Ledinegg instability-induced flow maldistribution on the heat transfer characteristics of thermally isolated parallel microchannels.
Characteristics of At-Scale mHealth Projects in the Global South: A Case Study Approach

Mobile health (mHealth) has emerged as a popular practice due to the increasing penetration of mobile phones in low-resource environments. However, most of the data come from pilot studies, where the findings are drawn mostly from a single media use interface and short-term based, leaving us with a limited understanding about the long-term use and impact of these services. As the more programs and countries aim to establish scaled, sustainable mhealth programs, it is therefore important to study mHealth programs in more depth to understand what makes them successful. The goal of this study is to evaluate five mHealth projects at different levels of scale in five different countries to understand in what ways the scaled projects are similar or different than those that did not scale.
Assessing sub-grid variability within satellite pixels over urban regions using airborne mapping spectrometer measurements

Abstract. Sub-grid variability (SGV) in atmospheric trace gases within satellite pixels is a key issue in satellite design and interpretation and validation of retrieval products. However, characterizing this variability is challenging due to the lack of independent high-resolution measurements. Here we use tropospheric NO2 vertical column (VC) measurements from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument with a spatial resolution of about 250 m×250 m to quantify the normalized SGV (i.e., the standard deviation of the sub-grid GeoTASO values within the sampled satellite pixel divided by the mean of the sub-grid GeoTASO values within the same satellite pixel) for different hypothetical satellite pixel sizes over urban regions. We use the GeoTASO measurements over the Seoul Metropolitan Area (SMA) and Busan region of South Korea during the 2016 KORUS-AQ field campaign and over the Los Angeles Basin, USA, during the 2017 Student Airborne Research Program (SARP) field campaign. We find that the normalized SGV of NO2 VC increases with increasing satellite pixel sizes (from ∼10 % for 0.5 km×0.5 km pixel size to ∼35 % for 25 km×25 km pixel size), and this relationship holds for the three study regions, which are also within the domains of upcoming geostationary satellite air quality missions. We also quantify the temporal variability in the retrieved NO2 VC within the same hypothetical satellite pixels (represented by the difference of retrieved values at two or more different times in a day). For a given satellite pixel size, the temporal variability within the same satellite pixels increases with the sampling time difference over the SMA. For a given small (e.g., ≤4 h) sampling time difference within the same satellite pixels, the temporal variability in the retrieved NO2 VC increases with the increasing spatial resolution over the SMA, Busan region, and the Los Angeles Basin. The results of this study have implications for future satellite design and retrieval interpretation and validation when comparing pixel data with local observations. In addition, the analyses presented in this study are equally applicable in model evaluation when comparing model grid values to local observations. Results from the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) model indicate that the normalized satellite SGV of tropospheric NO2 VC calculated in this study could serve as an upper bound to the satellite SGV of other species (e.g., CO and SO2 ) that share common source(s) with NO2 but have relatively longer lifetime.
Phenotypic shifts following admixture in recombinant offspring of Arabidopsis thaliana

Admixture can act to expand genetic variation and generate new trait combinations or functional trait values compared to parental lines. We examined how admixture between geographically distinct and/or genetically distinct parental genotypes could create either expanded genetic variation or novel phenotypes in the recombinant individuals of a F2 population of Arabidopsis thaliana accessions. In three different experiments, we grew 13 F2’s of Arabidopsis that differ in the genetic distance and/or geographic location of their parental source. The experiments tested the response of F2 recombinant populations to drought, high temperature and overwintering in field conditions. We estimated a multi-trait phenotypic space based on phenology, growth and fitness traits using a non-metric multidimensional scaling analysis. We found that approximately half (51%) of the F2 recombinant populations across the different experiments shifted their phenotype and occupied a different phenotypic space than their parents. Fitness changes in shifted recombinant F2’s populations depended upon the experimental conditions. A shift in the phenotypic space was associated with an increase in fitness under drought conditions but the opposite was true under high temperature conditions where the non-shifted F2 recombinant populations had a higher fitness. Therefore, one recombinant event following admixture was sufficient to shift offspring phenotypes away from parental phenotypes in half of admixture events and the resulting phenotypic shifts could result in a fitness increase under specific environmental conditions. Our study provides experimental evidence that admixture can provide a rapid shift in plant phenotypes with a resulting increase in fitness suggesting that such events are an important mechanism for rapid evolution post-introduction.
Semantic predictability of implicit causality can affect referential form choice

Abstract Models of language comprehension show that predictable elements are easier to understand. Does predictability also guide production? While many models suggest it does (e.g., Arnold, 1998; Aylett & Turk, 2004; Levy & Jaeger, 2007; Jurafsky, Bell, Gregory, & Raymond, 2001; Mahowald, Fedorenko, Piantadosi, & Gibson; Orita, Vornov, Feldman & Daume, 2015; Tily & Piantadosi, 2009), several models suggest that it does not make speakers more likely to select pronouns (Fukumura & van Gompel, 2010; Kehler et al., 2008; Kehler & Rohde, 2013; Kehler & Rohde, 2019; Stevenson et al., 1994). Claims that predictability does not affect pronoun production are based on evidence that certain semantic roles are more likely to be re-mentioned in discourse, but speakers do not prefer pronouns for those event roles, especially when predictability stems from implicit causality estimates. These findings contrast with studies of transfer verbs, where goals are more predictable than sources, and speakers do use pronouns more for goals versus sources (Arnold, 2001; Rosa & Arnold, 2017). Our study takes a closer look at the predictability of implicit causes, using a novel experimental paradigm that is more contextualized than the methods used in previous studies. In two experiments, we find that implicit causality does affect pronominalization. This suggests that predictability may play a broad role in both reference production and language production more generally.
Towards Generalizable Network Anomaly Detection Models

Finding the root causes of network performance anomalies is critical to satisfy the quality of service requirements. In this paper, we introduce machine learning (ML) models to process TCP socket statistics to pinpoint underlying reasons of performance issues such as packet loss and jitter. More importantly, we introduce a novel feature engineering method to transform network-dependent metrics (e.g., total packet count and round trip time) in training datasets into network-independent forms to be able to transfer the models to new network settings without requiring to retrain them. Experimental results in various network settings show that the proposed feature engineering approach improves the performance of the models in previously unseen network settings from around 60% to nearly 90%. We believe ability to transfer ML models across networks will pave the way for wide adoption of ML solutions in production networks where collecting labeled data is not possible.
Labor Noncompete Agreements: Tool for Economic Efficiency or Means to Extract Value from Workers?:

A number of theoretical arguments have been offered in favor of noncompete provisions in labor agreements. While there has been considerable empirical research on the effects of those provisions, t...
Does Irrigation with Treated and Untreated Wastewater Increase Antimicrobial Resistance in Soil and Water: A Systematic Review

Population growth and water scarcity necessitate alternative agriculture practices, such as reusing wastewater for irrigation. Domestic wastewater has been used for irrigation for centuries in many historically low-income and arid countries and is becoming more widely used by high-income countries to augment water resources in an increasingly dry climate. Wastewater treatment processes are not fully effective in removing all contaminants, such as antimicrobial resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). Literature reviews on the impact of wastewater irrigation on antimicrobial resistance (AMR) in the environment have been inconclusive and mostly focused on treated wastewater. We conducted the first systematic review to assess the impact of irrigation with both treated or untreated domestic wastewater on ARB and ARGs in soil and adjacent water bodies. We screened titles/abstracts of 3002 articles, out of which 41 were screened in full text and 26 were included in this review. Of these, thirteen investigated irrigation with untreated wastewater, and nine found a positive association with ARB/ARGs in soil. Out of thirteen studies focused on treated wastewater, six found a positive association with ARB/ARGs while six found mixed/negative associations. Our findings demonstrate that irrigation with untreated wastewater increases AMR in soil and call for precautionary action by field workers, their families, and consumers when untreated wastewater is used to irrigate crops. The effect of irrigation with treated wastewater was more variable among the studies included in our review, highlighting the need to better understand to what extent AMR is disseminated through this practice. Future research should assess factors that modify the effect of wastewater irrigation on AMR in soil, such as the degree and type of wastewater treatment, and the duration and intensity of irrigation, to inform guidelines on the reuse of wastewater for irrigation.
Quantifying the Risk and Dosimetric Variables of Symptomatic Brainstem Injury After Proton Beam Radiation in Pediatric Brain Tumors.

Purpose/Objective(s) Brainstem toxicity after radiation is a devastating complication and a particular concern with proton radiation (RT), given the biological differences and range uncertainties at the distal edge of proton beam. Data from St. Jude's found a 3.7% risk of brainstem necrosis after photon-based RT, while the incidence with protons ranges from 0.7% - 31% across studies. We investigated the incidence and clinical correlates of brainstem injury in pediatric brain tumors treated with proton therapy. Materials/Methods All patients 30 Gy and/or Dmax > 50.4 Gy were included. We excluded patients with primary brainstem tumors. Symptomatic brainstem injury (SBI) was defined as any new or progressive cranial neuropathy, ataxia, dysmetria and/or motor weakness with corresponding radiographic abnormality within the brainstem and was graded per the NCI Common Terminology Criteria for Adverse Events v5.0 (Grade 2: moderate symptoms, corticosteroids indicated; Grade 3: severe symptoms, medical intervention indicated; Grade 4: life-threatening; urgent intervention; and Grade 5: death). Results A total of 595 patients were reviewed and 362 (medulloblastoma = 209, ependymoma = 86, ATRT = 43, pineoblastoma = 9, others = 15) met our inclusion criteria. Median age at RT was 5 years (range 0.7 – 17.9 years) and median prescribed RT dose was 54 CGyE (range 39.6 – 59.4 CGyE). Median follow up was 40 months (range 1 – 152). Ten patients (2.7%) developed SBI, at a median of 4 months after RT (range 1-6). Grades 2,3,4 and 5 brainstem injuries were seen in 3, 4, 2 and 1 patient respectively. Mean brainstem Dmax in SBI and non-SBI patients was 55.9 Gy and 54.8 Gy (P = 0.30), while the mean Dmean was 43.3 Gy and 43.2 Gy (P = 0.48) respectively. Most common symptoms of SBI were ataxia, slurred speech, 6th cranial nerve palsy and bulbar palsy. All SBI patients required steroids for 1-5 months, while grade 3-5 injuries were also treated with bevacizumab and/or hyperbaric oxygen therapy. Asymptomatic imaging changes within brainstem were seen in 47 patients (13%) at a median of 4 months after RT, most common findings being increased T2 flair, focal enhancement and encephalomalacia. In 2014, our institution started using strict brainstem dose constraints (Dmax ≤ 57 Gy, Dmean ≤ 52.4 Gy and V54 ≤ 10%). The incidence of SBI has decreased from 4.2% (2007-2013) to 0.7% (2014-2019) (P = 0.047) while asymptomatic imaging changes remain similar (11.6% vs 15.1%, P = 0.33). Patients with SBI had a higher V45, V50-52 and D15 -D50; while the Dmax, Dmean, V53-60 and D1- D10 were similar. Conclusion Our results suggest that there is a low risk of SBI after proton therapy for pediatric brain tumors. A lower incidence of SBI was seen after the use of strict brainstem dose constraints. Volumetric doses to brainstem may play a significant role in determining the risk of SBI and developing a dose response nomogram is warranted.
Effect of maternal predator exposure on the ability of stickleback offspring to generalize a learned colour–reward association

Maternal stress can have long-term negative consequences for offspring learning performance. However, it is unknown whether these maternal effects extend to the ability of offspring to apply previously learned information to new situations. In this study, we first demonstrate that juvenile threespine sticklebacks, Gasterosteus aculeatus, are indeed capable of generalizing an association between a colour and a food reward learned in one foraging context to a new foraging context (i.e. they can apply previously learned knowledge to a new situation). Next, we examined whether this ability to generalize was affected by maternal predator stress. We manipulated whether mothers were repeatedly chased by a model predator while yolking eggs (i.e. before spawning) and then assessed the learning performance of their juvenile offspring in groups and pairs using a colour discrimination task that associated a colour with a food reward. We found that maternal predator exposure affected the tendency of offspring to use social cues: offspring of predator-exposed mothers were faster at copying a leader's behaviour towards the rewarded colour than offspring of unexposed mothers. However, once the colour–reward association had been learned, offspring of predator-exposed and unexposed mothers were equally able to generalize their learned association to a new foraging task. These results suggest that offspring of predator-exposed mothers might be able to overcome learning deficits caused by maternal stress by relying more on social cues.
Conformational Constraints in the Design of Receptor Selective Peptides: Conformational Analysis and Molecular Dynamics

Efforts to understand the relationships between the three dimensional structure and topography of a peptide hormone or neuropeptide and its biological activities have been difficult due to the many conformations generally available to these natural products, and the complexity of the hormone-receptor interaction which involves at least three different conformational states in the course of information transfer (Hruby 1981a,b; Hruby and Hadley, 1986; Hruby et al., 1983). A major advance in this area has come with the development of conformational constraints, for example via cyclization (Kessler, 1982; Hruby, 1982, 1985), and their use in the design of more receptor selective, potent, and prolonged acting peptide analogues. A major goal in this area is the design of conformationally constrained analogues with stable conformations and high receptor specificity that can be used as templates to assess the topographical features which are important for ligand-receptor interaction and for transduction to produce a biological response. Strategies for accomplishing these goals are urgently needed. In this paper we will discuss two strategies which we believe can be utilized generally, but at different times, in the course of developing insights into the “biologically active” conformation for a peptide hormone or neurotransmitter.
The 2.7-Å crystal structure of Gα12 in complex with a regulator of G protein signaling homology (RH) domain (843.1)

Heterotrimeric G proteins Gα12 and Gα13 parse signals from G protein-coupled receptors at the cell surface to activation of RhoA through a subset of RhoA-specific exchange factors (RhoGEFs), includ...
The Power of Probabilism in Popperian FINite Learning (extended abstract)

We consider the capabilities of probabilistic FIN-type learners who must always produce programs (i.e., hypotheses) that halt on every input. We show that the structure of the learning capability of probabilistic and team learning with success ratio above 1/2 in PFIN-type learning is analogous to the structure observed in FIN-type learning. On the contrary, the structure of probabilistic and team learning with success ratio at or below 1/2 is more sparse for PFIN-type learning than FIN-type learning. For n ≥2, we show that the probabilistic hierarchy below 1/2 for PFIN-type learning is defined by the sequence 4n/9n−2, which has an accumulation point at 4/9. We also show that the power of redundancy at the accumulation point 4/9 is different from the one observed at 1/2. More interestingly, for the first time, we show the power of redundancy even at points that are not accumulation points.
Uncoupling of transpositional immunity from gamma delta transposition by a mutation at the end of gamma delta.

The transposon gamma delta, in common with other members of the Tn3 family, confers transpositional immunity, a phenomenon by which plasmids containing a single transposon end show reduced activity as targets for further insertion by the same element. We found that a copy of a mutant delta end, in which the two terminal base pairs (59 GG) were substituted with cytosines, conferred the same degree of immunity as the unaltered delta end. However, a transposon analog with the mutant delta end as its termini could not transpose. These results suggest that the binding of transposase to a site on a target replicon is sufficient to confer immunity and that immunity does not involve subsequent DNA transactions at the bound target site, analogous to the catalytic processes that occur at the transposon ends during transposition.
Effect of dietary monensin on ovarian response following gonadotropin treatment in prepuberal heifers.

Twenty prepuberal Charolais X Brahman-Hereford heifers were randomly assigned to be fed a concentrate containing either 0 mg (C) or 200 mg (M) monensin sodium/head/day. Coastal bermudagrass hay was fed ad libitum. Average daily gain was similar for the two groups. Each heifer received 1 mg of porcine follicle stimulating hormone (FSH-P) (Armour) at 0800 and 2000 hr on days 22 through 26 (10 mg total) and 2,500 IU human chorionic gonadotropin (HCG) on day 27. Flank laparotomy was performed on day 30, for examination of ovaries, and ovariectomy was performed on day 37. The average ovarian size +/- standard error at day 15 ws 3,730 +/- 66 mm3 and 1,848 +/- 55 mm3 for groups M and C, respectively (P < .025), as measured by rectal palpation. Numbers of ovulation sites measured on day 30 were 9.1 +/- 2.2 and 4.9 +/- 1.8 per heifer for groups M and C, respectively (P < .01). After ovariectomy on day 37, heifers fed M were found to have greater ovarian weight (P < .05), more corpora lutea (CL) (P < .05), greater total luteal weight (P < .05), more follicles (P < .01) and greater weight of follicular fluid (P < .05) and stroma (P < .025) than controls. CL were analyzed for progesterone content by spectrophotometric procedures. Heifers fed M had slightly larger CL (P < .10) with progesterone concentrations similar to those in CL from controls. This resulted in more luteal progesterone per CL and more luteal progesterone per heifer in the M heifers than in the controls. Prepuberal heifers fed M, which caused the expected shifts in rumen fermentation and volatile fatty acid production, exhibited an enhanced ovarian response to gonadotropins compared to that exhibited by controls.
An adaptive CMOS imager with time-based compressive active-pixel response

This paper presents an alternative to a logarithmic response CMOS imager that utilizes an in-pixel, time-based compressive map for capturing scenes with wide dynamic range. The imager employs a correlated double sampling technique that significantly reduces the effects of parasitic capacitance and mismatch in active-pixel circuits. An on-line adaptation technique that adjusts the parameter of the compressive map compensates for variable illumination conditions across different scenes, achieving large dynamic range. The proposed pixel architecture and algorithm have been implemented with relatively few transistors and with a fill factor of 17%. An imager consisting of an array of 110 /spl times/ 80 pixels has been designed and fabricated using a 0.5/spl mu/m CMOS process. Simulation and preliminary testing results demonstrate the functionality of the imager to adapt its response under different illumination conditions.
Improved Schottky barrier solar cells

Schottky barrier (SB) solar cells have been fabricated for solar energy conversion using GaAs and GaAs 0.78P0.22. Conversion efficiencies of 9% for air mass zero and 12% for terrestrial sun were observed for antireflection coated GaAs0.78P0.22 SB cells. The corresponding efficiencies for GaAs SB cells were 7% and 10%, respectively. These efficiencies are for cells with no interfacial layer effect. The short circuit current density for GaAs SB cells has been improved. The use of an ellipsometer to determine the optimum antireflection coating parameters is illustrated.
Grain size and dislocation density in recrystallized siliconiron

Abstract Grain size and dislocation density were determined for cold-worked and recrystallized specimens of 3.3 percent siliconiron alloy. Cold-work to 50 percent reduction in thickness and temperature to 1000°C were used to determine the dependence of grain size and dislocation density on the prior treatment. The smallest grain size obtained was approximately 0.001 inch as determined by the linear intercept technique. Dislocation densities were of the order of 10 6 per cm 2 and above for all specimens as determined by etch pit techniques and optical microscopy. Recrystallization was observed to require a temperature range of at least 100 deg C to be fully completed and the minimum grain size was not particularly sensitive to the amount of prior cold-work. Dislocation density in fully recrystallized specimens was observed to vary widely. The presence of dislocation tangles and subboundaries within individual recrystallized grains indicates a continuing problem in experimental work. This investigation has shown that the use of “grain size” alone as the controlling parameter for structurally dependent mechanical behavior of siliconiron is inadequate. The dislocation density and substructure are found to be unpredictable on the basis of recrystallization. It is suggested that during the preparation of test specimens more consideration be given to all structural variables.
Global Isochrons and Phase Sensitivity of Bursting Neurons

Phase sensitivity analysis is a powerful method for studying (asymptotically periodic) bursting neuron models. One popular way of capturing phase sensitivity is through the computation of isochrons---subsets of the state space that each converge to the same trajectory on the limit cycle. However, the computation of isochrons is notoriously difficult, especially for bursting neuron models. In [W. E. Sherwood and J. Guckenheimer, SIAM J. Appl. Dyn. Syst., 9 (2010), pp. 659--703], the phase sensitivity of the bursting Hindmarsh--Rose model is studied through the use of singular perturbation theory: cross sections of the isochrons of the full system are approximated by those of fast subsystems. In this paper, we complement the previous study, providing a detailed phase sensitivity analysis of the full (three-dimensional) system, including computations of the full (two-dimensional) isochrons. To our knowledge, this is the first such computation for a bursting neuron model. This was made possible thanks to the ...
Coherent two-photon resonance and Doppler-free population inversion

Doppler-free population inversion induced by coherent two-photon resonance is calculated analytically for a two-photon analog of the hyperbolic-secant pulse and numerically for a Gaussian, linearly chirped pulse. The numerical calculations are carried out for a two-photon resonance of a chirped ruby laser line with the $6{S}_{\frac{1}{2}}\ensuremath{\rightarrow}9{D}_{\frac{3}{2}}$ transition in Cs. Complete inversion is found when the fractional change in frequency during the pulse lies between 6 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}6}$ and 2 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}5}$. The coherent two-photon resonances are described by optical Bloch equations which are derived from a multiple-time-scale perturbation theory.
Bead-spring model of a polymer chain: A transient solution

With the Rouse-Zimm differential equation of the spring-bead model, the distribution function ofN + 1 beadsΨ(x, y, z,t) [here x denotes x0, x1,..., xN, and similarly for y and z] is explicitly solved with the two different initial conditions: the Gaussian and delta distribution functions. We find that although the mean end-to-end distances obtained from the two initial conditions are the same, the expressions of the mean square end-to-end distances are different. We also obtain the expression for the mean and mean square end-to-end distances analytically from the Langevin equation with the delta initial distribution function. With this analytic expression, we show that the statistical quantities obtained from the Monte Carlo calculation are consistent with those obtained from the Rouse-Zimm differential equation if a suitable length is chosen for the time increment.
Effects of oleic acid infusion on plasma free fatty acids and blood ketone bodies in the fasting rat.

Abstract Oleic acid emulsions stabilized with albumin were infused into fasted rats. Blood samples taken before and during infusion were analyzed for free fatty acids (FFA), ketone bodies, glucose, and insulin. Turnover rates of FFA and ketone bodies were also determined using constant infusion of radioactive tracers. During oleic acid infusions at a rate of 2 μmoles/min/100 g body weight, FFA concentrations increased for a short time and then decreased to preinfusion levels. The decreases in concentrations were due to decreases in the endogenous rates of appearance of FFA into the blood. When oleic acid was infused at a rate of 3.5 μmoles/min/100 g body weight, FFA concentrations increased and remained elevated throughout the infusion. Ketone body concentrations more than doubled during infusions at 2 and 3.5 μmoles/min/100 g body weight and showed no signs of decreasing even when FFA concentrations decreased. Insulin concentrations doubled during infusion and glucose concentrations decreased. Insulin injected during infusion had little effect on concentrations of FFA or ketone bodies. It was concluded that infusions of oleic acid inhibit adipose tissue lipolysis and increase blood ketone concentrations in intact fasted rats. The injection of insulin does not inhibit ketogenesis when blood FFA levels are maintained by infusion.
A COMPARISON OF LIPID AND LIPID/HYDROCOLLOID BASED COATINGS TO EVALUATE THEIR EFFECT ON POSTHARVEST QUALITY OF GREEN BELL PEPPERS

Maintaining quality of harvested fruit and vegetables is a challenge. The study investigated the effects of two lipid and lipid/hydrocolloid based coatings on maintaining post harvest quality of green bell peppers. Quality characteristics measured during the 4-week storage period included: respiratory rate, moisture content (weight loss), chlorophyll content, puncture force, ascorbic acid (AA) and dehydroascorbic acid (DHA)contents. No significant differences (P > 0.05) between uncoated and coated peppers were noted for respiration rate, puncture force, chlorophyll content, andAA. Significant differences (P Cette etude evalue l'effet de deux enrobages a base de lipides et de melange lipides/hydrocolloides sur le maintien de la qualite apres recolte de poivrons verts. Les caracteristiques de qualite mesurees pendant 4 semaines d'entreposage comprennent: le taux de respiration, la teneur en eau, en chlorophylle, en acide ascorbique et deshydroascorbique et la resistance a la perforation. Des differences significatives sont observees seulement pour les teneurs en eau et en acide deshydroascorbique entre les poivrons enrobes et non enrobes.
Studies in rapid precipitation of hydroxides of calcium and magnesium

Abstract Precipitation of calcium and magnesium hydroxide from aqueous solution was carried out using a modified Nielsen apparatus in which supersaturation was established by rapidly mixing two reactant solutions in steady flow. The supersaturations ( S o ) used were high enough to establish homogeneous nucleation. This was indicated by the observations: (a) the number of nuclei formed N was greater than 10 6 /mL, (b) the S o - N data were found to graph linearly on log( N )-[ log ( S o )] -2 coordinates, and (c) the product entities exhibited highly monodispersed size distributions. Electron microscopic examination revealed that the morphologies for both products were determined by crystallographic structure. The mechanism of growth was found to change abruptly but only after the period of active nucleation.
ESTIMATING THE TAX BENEFITS OF DEBT

The standard approach to valuing interest tax shields assumes that full tax benefits are realized on every dollar of interest deduction in every scenario. The approach presented in this paper takes account of the possibility that interest tax shields cannot be used in some scenarios, in part because of variations in the firm's profitability. Because of the dynamic nature of the tax code (e.g., tax-loss carrybacks and carryforwards), it is necessary to consider past and future taxable income when estimating today's effective marginal tax rate. The paper uses a series of numerical examples to show that (1) the incremental value of an extra dollar of interest deduction is equal to the marginal tax rate appropriate for that dollar; and (2) a firm's effective marginal tax rate (and therefore the marginal benefit of incremental interest deductions) can actually decline as the firm takes on additional debt. Based on marginal benefit functions for thousands of firms from 1980–1999, the author concludes that the tax benefits of debt averaged approximately 10% of firm value during the 1980s, while declining to around 8% in the 1990s. By taking maximum advantage of the interest tax shield, the average firm could have increased its value by approximately 15% over the 1980s and 1990s, suggesting that the consequences of being underlevered are significant. Surprisingly, many of the companies that appear best able to service debt (i.e., those with the lowest apparent costs of debt) use the least amount of debt, on average. Treasurers and CFOs should critically reevaluate their companies' debt policies and consider the benefits of additional leverage, even if taking on more debt causes their credit ratings to slip a notch.
Modeling methyl methacrylate free radical polymerization: Reaction in hydrophilic nanopores

Abstract Free radical polymerization of methyl methacrylate in nanopores has been shown to result in a decrease in the time for the onset of autoacceleration. In this work, we simplify our previous kinetic model of nanoconfined methyl methacrylate polymerization, which was based on the work of Verros and coworkers, and incorporate diffusion effects into the model using the Doolittle free volume theory. The simplified model well describes the experimental calorimetric conversion versus time data for isothermal bulk methyl methacrylate polymerization, capturing autoacceleration and the dependence of the limiting conversion on temperature. In order to model the reaction in nanopores, we assume that the diffusion coefficient scales with molecular size to the −3 power and with nanopore diameter to the 1.3 power. Experimental calorimetric conversion versus time data for polymerization in hydrophobic nanopores are well captured by the model, including the decrease in the time to reach autoacceleration with decreasing pore size. The scaling assumed is consistent with that predicted using molecular simulations for good solvent conditions by Avramova and Milchev and by Cui, Ding, and Chen. According to the fit of the experimental data, chain diffusivity is 20–50% of the bulk value in 13 nm-diameter pores.
Endothelial function in children and adolescents with mucopolysaccharidosis.

Background Although coronary artery pathology is a prominent feature of mucopolysaccharidosis (MPS), it may be underestimated by coronary angiography because of its diffuse nature. It is also generally assumed that cardiovascular risk is increased in MPS and reduced following hematopoietic stem cell transplantation (HSCT) or enzyme replacement therapy (ERT), but this has never been formally evaluated. Non-invasive methods of assessing vascular endothelial function may provide a measure of cardiovascular risk in MPS. We evaluated endothelial function, using digital reactive hyperemia, in youth with MPS and in healthy controls.
Effects of methylmercury on developing mouse cerebellar cortex

Methylmercury is known to cause neurologic impairment of the developing central nervous system in humans and in several animal models, but the nature of the injury that underlies the functional deficits is not clear. Treatment of 2-day-old mice with methylmercury at 8 mg Hg/kg resulted in brain concentrations of 2.7 μg Hg/g tissue and the following changes in the external granular layer of the cerebellar cortex 24 h after treatment. The total number of cells in five regions of the external granular layer was significantly reduced by methylmercury treatment (analysis of variance, P < 0.025). The mitotic activity of the external granular layer was not significantly altered by methylmercury. Rather, cells appeared to be injured or dying in the treated animals, as indicated by condensed nuclei. The number of cells with nuclei measuring ≤3 μm in diameter was increased after methylmercury (P < 0.002). The percentage of late mitotic figures (anaphase/mitotic figures) was also reduced in the methylmercury-treated animals (P < 0.002). The incomplete mitosis may contribute to the decreased cell number by causing cell death. This mitotic arrest, presumably due to loss of spindle microtubules, may be an important mechanism in methylmercury-caused neurotoxicity in developing animals.