cssi/SciSciGPT-SciSciNet huggingface dataset:
Gene drive inhibition by the anti-CRISPR proteins AcrIIA2 and AcrIIA4 in Saccharomyces cerevisiae

Given the widespread use and application of the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas gene editing system across many fields, a major focus has been the development, engineering and discovery of molecular means to precisely control and regulate the enzymatic function of the Cas9 nuclease. To date, a variety of Cas9 variants and fusion assemblies have been proposed to provide temporally inducible and spatially controlled editing functions. The discovery of a new class of ‘anti-CRISPR’ proteins, evolved from bacteriophage in response to the prokaryotic nuclease-based immune system, provides a new platform for control over genomic editing. One Cas9-based application of interest to the field of population control is that of the ‘gene drive’. Here, we demonstrate use of the AcrIIA2 and AcrIIA4 proteins to inhibit active gene drive systems in budding yeast. Furthermore, an unbiased mutational scan reveals that titration of Cas9 inhibition may be possible by modification of the anti-CRISPR primary sequence.
Development of the Artificial Womb

Prematurity is a global health problem representing one of the most significant causes of morbidity and mortality in children. The concept of an artificial womb has been explored as an innovation which could substantially improve clinical outcomes in preterm patients by offering the ability to support growth and development of the neonate in a manner consistent with fetal physiology. This review will address the contemporary literature exploring the development of the artificial womb, with a focus on promising new breakthroughs in the field. Our laboratory has reported the development of an artificial womb incorporating the critical components of intrauterine physiology, namely sterile fluidic incubation of the isolated fetus as well as perfusion and gas exchange using a pumpless extracorporeal circuit. We have demonstrated support of fetal lambs for up to 4 weeks with stable hemodynamics and normal growth and development. The artificial womb represents unprecedented potential for improvement in clinical outcomes in critically preterm infants. Recent studies have demonstrated promising results in preclinical animal models, supporting the translation of this technology to human clinical trials.
Learning to Recommend Tags for On-line Photos

Recommending text tags for on-line photos is useful for on-line photo services. We propose a novel approach to tag recommendation by utilizing both the underlying semantic correlation between visual contents and text tags and the tag popularity learnt from realistic on-line photos. We apply our approach to a database of real on-line photos and evaluate its performance by both objective and subjective evaluation. Experiwith ments demonstrate the improved performance of the proposed approach compared the state-of-the-art techniques in the literature.
Temporal Approximate Function Memoization

Improving the performance of applications is a core target of computer systems research and has led to the creation of various techniques. Among them is function memoization, an intuitive technique that, unfortunately, failed to live up to its promised potential. Traditional function memoization falls short mainly because it is input-based, meaning the system needs to pattern-match the current invocations inputs with previously seen ones to decide which memoized output value to return. This is often computationally intensive and only suitable for a limited set of functions. However, function calls often exhibit temporal value locality on their output. We capitalize on this observation to create the first output-based function memoization technique. We demonstrate that compiler-directed output-based memoization reduces energy and runtime by 50 to 75 percent (2-4x speedup) at the cost of a relatively small degradation of the applications output quality.
The Rise of Hierarchical Nanostructured Materials from Renewable Sources: Learning from Nature.

Mimicking Nature implies the use of bio-inspired hierarchical designs to manufacture nanostructured materials. Such materials should be produced from sustainable sources (e.g., biomass) and through simple processes that use mild conditions, enabling sustainable solutions. The combination of different types of nanomaterials and the implementation of different features at different length scales can provide synthetic hierarchical nanostructures that mimic natural materials, outperforming the properties of their constitutive building blocks. Taking recent developments in flow-assisted assembly of nanocellulose crystals as a starting point, we review the state of the art and provide future perspectives on the manufacture of hierarchical nanostructured materials from sustainable sources, assembly techniques, and potential applications.
Combining Biology and Chemistry for a New Take on Chemotherapy: Antibody-Drug Conjugates in Hematologic Malignancies.

This review is about the antibody-drug conjugate (ADC), a form of drug delivery consisting of a monoclonal antibody, linker, and cytotoxic payload. We summarize the history of ADC development, highlighting the three FDA-approved ADCs currently available. Gemtuzumab ozogamicin is a CD33-targeted ADC linked to calicheamicin. It is approved for CD33+ AML in the first line or the relapsed or refractory (R/R) setting. Brentuximab vedotin is a CD30-targeted ADC bound to MMAE. It is approved for the treatment of certain R/R CD30+ lymphomas. Recently, it has been approved for first line therapy with chemotherapy in advanced HL. Inotuzumab ozogamicin is a CD22-directed ADC attached to calicheamicin indicated for the treatment of adults with R/R B cell precursor ALL. Three ADCs have been approved for the treatment of various hematologic malignancies. We discuss the pertinent human trials that led to FDA approval. We include our perspectives about drug resistance, toxicities, and future development.
Atypical Communication Characteristics, Differential Diagnosis, and the Autism Spectrum Disorder Phenotype in Youth.

This study compared atypical communication characteristics (ACCs) in clinic-referred youth with and without autism spectrum disorder (ASD), identified subgroups based on different patterns of ACCs ...
Patient-specific noise power spectrum measurement via generative adversarial networks (Conference Presentation)

A deep learning Generative Adversarial Networks (GANs) were developed and validated to provide an accurate way of direct NPS estimation from a single patient CT scan. GANs were utilized to map a white noise input to a CT noise realization with correct CT noise correlations specific to a single local uniform ROI. To achieve this, a two-stage strategy was developed. In the pre-training stage, ensembles of 64x64 MBIR noise-only images of a quality assurance phantom were used as training samples to jointly train the generator and discriminator. They were fined-tuned using training samples from a single 101x101 ROI of an abdominal anthropomorphic phantom. Results from GANs and physical scans were compared in terms of its mean frequency and radial averaged NPS. This workflow was extended to a patient case where reference dose and 25% of reference dose CT scans were provided for fine-tuning. GANs generated noise-only image samples that are indistinguishable from physical measurement. The overall mean frequency discrepancy between NPS generated from GANs and those from physically acquired data was 0.2% for anthropomorphic phantom validation. The KL divergence for 1D radial averaged NPS profile of these two NPS acquisitions was 2.2×10^(-3). Statistical test indicates trained GANs generated equivalent NPS to physical scans. In clinical patient-specific NPS studies, it showed a distinction between the reference dose case and 25% of reference dose case. It was demonstrated the GANs characterized the properties of CT noise in terms of its mean frequency and 1D NPS profile shape.
Loss of Potential Aquatic-Terrestrial Subsidies Along the Missouri River Floodplain

The floodplains of large rivers have been heavily modified due to riparian development and channel modifications, both of which can eliminate shallow off-channel habitats. The importance of these habitats for aquatic organisms like fishes is well studied. However, loss of off-channel habitat also eliminates habitats for the production of emerging aquatic insects, which subsidize riparian consumers in terrestrial food webs. We used field collections of insect emergence, historical mapping, and statistical modeling to estimate the loss of insect emergence due to channel modifications along eight segments of the Missouri River (USA), encompassing 1566 river km, between 1890 and 2012. We estimate annual production of emerging aquatic insects declined by a median of 36,000 kgC (95% CrI: 3000 to 450,000) between 1890 and 2012 (a 34% loss), due to the loss of surface area in backwaters and related off-channel habitats. Under a conservative assumption that riparian birds obtain 24% of their annual energy budget from adult aquatic insects, this amount of insect loss would be enough to subsidize approximately 790,000 riparian woodland birds during the breeding and nesting period (May to August; 95% CrI: 57,000 to 10,000,000). Most of the loss is concentrated in the lower reaches of the Missouri River, which historically had a wide floodplain, a meandering channel, and a high density of off-channel habitats, but which were substantially reduced due to channelization and bank stabilization. Our results indicate that the loss of off-channel habitats in large river floodplains has the potential to substantially affect energy availability for riparian insectivores, further demonstrating the importance of maintaining and restoring these habitats for linked aquatic-terrestrial ecosystems.
Extrapolation in the scale of generalized reverse Hölder weights

We develop a theory of extrapolation for weights that satisfy a generalized reverse Holder inequality in the scale of Orlicz spaces. This extends previous results by Auscher and Martell (Adv Math 212(1):225–276, 2007) on limited range extrapolation. We then provide several applications of our extrapolation techniques. These applications include new results and new proofs of known results for two weight inequalities for linear and bilinear operators.
Rhinocerization: Political Activity and Allegiances of the Young Generation, 1935–1941

This chapter is about the moment of political conversion for certain Criterionists. Bejan examines four members of Criterion who sympathized with the Iron Guard (Eliade, Cioran, Noica, Sadova) and three who resisted (Comarnescu, Sebastian, Ionesco). The investigation of Sadova exposes how the National Theatre was used as a propaganda tool and how theater artists both contributed to and were affected by the political events. By the end of the 1930s, what Eliade fearfully termed ‘the time when we will no longer be free to do what we wish’ had arrived. War covered the globe, shattering accepted social norms and moral codes, including the laws of friendship. What Ionesco famously labeled ‘rhinocerization’ trumped previous existing individual loyalties and the joint effort to create culture.
The life and legend of James Watt: collaboration, natural philosophy, and the improvement of the steam engine

Writing in 1907, but casting his mind forward ‘thousands of years’, the French philosopher Henri Bergson prophesied that the steam engine ‘will perhaps be spoken of as we speak of the bronze or of ...
Nanowires Pin Neurons: a Nano ”Moon Landing“

Recently, Harvard University scientists initiated a nano "moon landing." They developed hairpin-like nanowires to land and pin neurons to study their inner signals without cellular damage, decoding the communication within and between neuron networks and providing tools for future brain disease studies.
Oil absorption capability of electrospun carbon nanofibrous membranes having porous and hollow nanostructures

Abstract Current commercial oil absorbents such as polypropylene based materials are lack of exciting absorption capability for oil spill cleanup. Designing economic, efficient and stable absorbent for oil spill is still a challenge. Herein three types of carbon nanofibrous membranes with porous and/or hollow individual carbon nanofibers from bicomponent and co-axial electrospinning were prepared and their morphology, porosity, surface property as well as oil absorption capacity and reusability were characterized and compared. The results indicated that the hollow structure from co-axial electrospinning does not play a favorable role in oil absorption. The reasons may be attributed to surface nature, pore volume and nanometer scale interconnected hollow channel/pore structure that are naturally associated with co-axial electrospinning.
Far‐red photons have equivalent efficiency to traditional photosynthetic photons: Implications for redefining photosynthetically active radiation

Far-red photons (701-750 nm) are abundant in sunlight but are considered inactive for photosynthesis and are thus excluded from the definition of photosynthetically active radiation (PAR; 400-700 nm). Several recent studies have shown that far-red photons synergistically interact with shorter wavelength photons to increase leaf photochemical efficiency. The value of far-red photons in canopy photosynthesis has not been studied. Here, we report the effects of far-red photons on single leaf and canopy photosynthesis in 14 diverse crop species. Adding far-red photons (up to 40%) to a background of shorter wavelength photons caused an increase in canopy photosynthesis equal to adding 400-700 nm photons. Far-red alone minimally increased photosynthesis. This indicates that far-red photons are equally efficient at driving canopy photosynthesis when acting synergistically with traditionally defined photosynthetic photons. Measurements made using LEDs with peak wavelength of 711, 723, or 746 nm showed that the magnitude of the effect was less at longer wavelengths. The consistent response among diverse species indicates that the mechanism is common in higher plants. These results suggest that far-red photons (701-750 nm) should be included in the definition of PAR.
Chapter 3 – Avalanche and Propagation Criteria

This chapter introduces various properties which are useful for a Boolean function which is to be used in a cryptographic algorithm. The general theme is that the outputs of a Boolean function must be as random as possible in order to avoid cryptanalytic attacks. There are various ways to measure this randomness, and several important ones are introduced in the chapter. First is the Strict Avalanche Criterion (SAC) and its extensions to SAC of order k (notation SAC(k)SAC(k)). Next come the propagation criteria of degree k (notation PC(k)PC(k)). The directional derivative of a Boolean function is introduced, and its connection to criterion PC(k)PC(k) is explained. It is useful to know how many functions can satisfy the various criteria, and the relevant counting results are discussed, including the cases where the functions are also assumed to be balanced. The chapter includes an extensive discussion of known methods to construct functions satisfying SAC(k)SAC(k) and PC(k)PC(k). As part of this, the class of Maiorana–McFarland functions (or MM functions) is introduced. These functions also occur in numerous other cryptographic contexts.
Hoya Saxa: An Interview with Dean Stephen Ray Mitchell

I recently sat down with Stephen Ray Mitchell, MD, MBA, MACP, FAAP, FACR, the Joseph Butenas Professor of Medical Education and Dean of medical education at Georgetown University School of Medicine. In October 2019, it was announced that Dr. Mitchell’s tenure as Dean of medical education, which began in May 2002, would end on June 30, 2020. In addition to his numerous accomplishments and improvements to the School of Medicine, he is a beloved teacher, friend, and colleague to students, faculty, and staff alike. I was privileged enough to talk to him about his voyage to medicine, time as Dean, and plans for the future.
The impact of funding for federally qualified health centers on utilization and emergency department visits in Massachusetts.

Importance Federally qualified health centers (FQHCs) receive federal funding to serve medically underserved areas and provide a range of services including comprehensive primary care, enabling services, and behavioral health care. Greater funding for FQHCs could increase the local availability of clinic-based care and help reduce more costly resource use, such as emergency department visits (ED). Objective To examine the impact of funding increases for FQHCs after the ACA on the use of FQHCs and EDs. Methods Retrospective study using the Massachusetts All Payer Claims Database (APCD) 2010-2013 that included APCD enrollees in 559 Massachusetts ZIP codes (N = 6,173,563 in 2010). We calculated shift-share predictions of changes in FQHC funding at the ZIP code-level for FQHCs that received Community Health Center funds in any year, 2010-13 (N = 31). Outcomes were the number of ZIP code enrollees with visits to FQHCs and EDs, overall and for emergent and non-emergent diagnoses. Results In 2010, 4% of study subjects visited a FQHC, and they were more likely to be younger, have Medicaid, and live in low-income areas. We found that a standard deviation increase in prior year FQHC funding (+31 percentage point (pp)) at the ZIP code level was associated with a 2.3pp (95% CI 0.7pp to 3.8pp) increase in enrollees with FQHC visits and a 1.3pp (95% CI -2.3pp to -0.3pp) decrease in enrollees with non-emergent ED visits, but no significant change in emergent ED visits (0.3pp, 95% CI -0.8pp to 1.4pp). Conclusions We found that areas exposed to greater FQHC funding increases had more growth in the number of enrollees seen by FQHCs and greater reductions in ED visits for non-emergent conditions. Investment in FQHCs could be a promising approach to increase access to care for underserved populations and reduce costly ED visits, especially for primary care treatable or non-emergent conditions.
Health Needs and Functional Disability Among Mail-Order Pharmacy Users in the US.

This cross-sectional study examines the health characteristics of individuals who use mail-order pharmacies.
The Effect Of Postnatal Glucocorticoids On Renal Function And Blood Pressure In Very Low Birth Weight Infants

Background: Steroids play a major role during prenatal and postnatal renal development and function. Many neonates require postnatal steroids to treat hypotension, severe respiratory distress and prevention and treatment of bronchopulmonary dysplasia. Steroids are highly potent drugs with known adverse effects on infant growth and lead to poor neurodevelopmental outcomes. We investigated the role of cumulative dose and duration of steroid use on renal function and blood pressure in VLBW infants. Methods: In a retrospective cohort study, medical records of all VLBW infants (Gestational Age ≤ 35 weeks, birthweight ≤ 1500 grams) admitted to a tertiary …
Radiation-Associated Sarcoma of the Breast in a Patient With a Germline Tumor Protein p53 Mutation.

Radiation-induced sarcoma of the breast is a rare complication that is primarily treated with surgical resection but in patients with advanced disease, a multimodality treatment approach is often required. This case report discusses a 37-year-old female with a history of a pT3N3M0, estrogen receptor (ER)+, progesterone receptor (PR)+, human epidermal growth factor receptor 2 (HER2)+, right breast cancer, and a germline tumor protein (TP) p53 mutation who underwent right modified radical mastectomy, adjuvant systemic therapy, and radiation therapy, and subsequently developed a radiation-induced sarcoma. The patient is a 37-year-old female who has a history of pT3N3M0, ER/PR+, HER2+, and right breast cancer diagnosed in 2014. At the time of diagnosis, she had locally advanced disease and underwent right modified radical mastectomy followed by adjuvant chemotherapy, radiation, delayed right breast implant-based reconstruction, and left breast augmentation with mastopexy. Upon completion of adjuvant chemotherapy, she was started on hormonal therapy. In February 2020, she underwent genetic testing given her early onset of breast cancer and was found to have a germline TP53 mutation. Routine MRI for breast implant evaluation showed two irregular enhancing masses with an additional satellite lesion in the right breast. Right breast ultrasound (US)-guided biopsy revealed two separate foci of high-grade pleomorphic fibroblastic/myofibroblastic sarcoma. Further staging workup with a whole-body MRI was negative for evidence of metastatic disease. Her case was discussed in multidisciplinary sarcoma tumor board and consensus was for surgical resection. She underwent radical resection of the right chest wall masses and subcutaneous tissue, removal of right breast implant and capsulectomy, and left breast mastectomy with left breast implant removal and capsulectomy. The final pathology revealed two separate foci of high-grade pleomorphic fibroblastic/myofibroblastic sarcoma, 1.2 cm and 1.1 cm in their greatest dimensions with negative margins. Her case was re-discussed in multidisciplinary sarcoma tumor board and due to T1 size of the tumors and the negative resection margins, close surveillance with annual whole-body MRI and quarterly chest MRI imaging was recommended. In patients with a germline TP53 mutation and breast cancer, the utilization of adjuvant radiotherapy should be considered cautiously given the increased risk of radiation-associated sarcoma.
Transfer of the pea symbiotic plasmid pJB5JI in nonsterile soil

Transfer of the pea (Pisum sativum L.) symbiotic plasmid pJB5JI between strains of rhizobia was examined in sterile and nonsterile silt loam soil. Sinorhizobium fredii USDA 201 and HH003 were used as plasmid donors, and symbiotic plasmid-cured Rhizobium leguminosarum 6015 was used as the recipient. The plasmid was carried but not expressed in S. fredii strains, whereas transfer of the plasmid to R. leguminosarum 6015 rendered the recipient capable of nodulating pea plants. Confirmation of plasmid transfer was obtained by acquisition of plasmid-encoded antibiotic resistance genes, nodulation of pea plants, and plasmid profiles. Plasmid transfer in nonsterile soil occurred at frequencies of up to 10 per recipient and appeared to be highest at soil temperatures and soil moisture levels optimal for rhizobial growth. Conjugation frequencies were usually higher in sterile soil than in nonsterile soil. In nonsterile soil, transconjugants were recovered only with strain USDA 201 as the plasmid donor. Increasing the inoculum levels of donor and recipient strains up to 10 cells g of soil increased the number of transconjugants; peak plasmid transfer frequencies, however, were found at the lower inoculum level of 10 cells g of soil. Plasmid transfer frequencies were raised in the presence of the pea rhizosphere or by additions of plant material. Transconjugants formed by the USDA 201(pJB5JI) x 6015 mating in soil formed effective nodules on peas.
Synaptonemal complex analysis of X-7 translocations in male mice

The synaptonemal complexes of surface-spread spermatocytes of mice heterozygous for one of two reciprocal translations (R3 and R5) between the X and chromosome 7 have been examined by light and electron microscopy (EM). The break points of R3 were determined to be at 70% of chromosome 7, as measured from the centromere, and at 22% of the X. Translocation quadrivalents were formed almost exclusively. The break points of R5 were at 21% of chromosome 7 as measured from the centromere, and at 83% of the X. There was little indication that the break in the X interfered with sex-chromosome synapsis between the 7X and Y. Univalent Y's were not observed in R3, and only seldom observed (8–14%) in R5. However, in contrast to R3, R5 formed quadrivalents relatively rarely (20% in the EM study of 100 nuclei), and heteromorphic bivalents of 7X-Y and X7-7 quite frequently (72%). Possible causes of this high bivalent frequency are discussed. Light-microscope (LM) analysis alone was found to be inadequate for interpreting synaptic configurations (quadrivalents vs. bivalents) in R5. The LM analysis was further complicated by the occurrence of nonhomologous synapsis in the heteromorphic bivalents of R5, a phenomenon easily recognized and interpreted in the EM portion of the study.
Managing Patient Appointments in Primary Care

In recent years, many US health care establishments have found themselves under increasing pressure to improve the cost-effectiveness of their operations in the face of tight competition, while maintaining high standards of care. Finding the best trade-off between these competing objectives is not an easy task, since the efforts to keep costs under control often result in over utilization of existing resources and, as a consequence, increased patient delays. The Institute of Medicine report Crossing the Quality Chasm: A New Health System for the 21 st Century identifies “timeliness” as one of six goals that should drive the redesign of the health care delivery system in the coming years. For many patients, primary care is one of the most important settings for their contact with the health care system. In this setting, an appointment mechanism directly determines “timeliness” of received care. In this chapter we introduce a simple model that describes the evolution of appointment backlogs in a primary office setting and describe how expected value and the variance of the daily demand for appointments influences backlog buildup. We also discuss the popular practice of advanced access, a newly proposed approach for reducing and eliminating appointment delays. In particular, we develop a set of guidelines that any primary care office should use in determining the patient panel size to support the advanced access approach. Our guidelines are illustrated through a set of examples based on the demand and supply data taken from the surveys of the American Academy of Family Practice as well as 2002 National Ambulatory Medical Care Survey.
The contribution of cognitive engineering to the effective design and use of information systems

On examine l'importance pour le fonctionnement d'un systeme d'une interface efficace entre l'homme et la machine
Surface electromyographic recording of volitional activity: a technique to detect partial motor conduction block.

Partial motor conduction block, an electrophysiological hallmark of demyelination, helps to identify acquired demyelinating neuropathies but its electrophysiological detection can be difficult. We report a technique that may be helpful in this regard. Twenty-five patients with partial motor conduction block secondary to acquired demyelinating polyneuropathy (ADP), 7 with amyotrophic lateral sclerosis (ALS), 7 with stroke, and 11 control subjects, were studied. Amplitude of compound muscle action potentials was recorded after distal electrical (E) stimulation and for volitionally (V) induced responses in 82 muscles. Mean ± SD V/E ratio was 12.3 ± 6.6 for ADP patients, 58.1 ± 17 for ALS patients, 11.4 ± 9 for stroke patients, and 55.4 ± 12.3 for controls. The V/E ratios for patients with partial motor conduction block and stroke were significantly reduced compared with ALS patients and healthy controls (P < 0.05). Surface electromyographic (EMG) recording for determination of the V/E ratio may be a useful technique for detection of a proximal conduction block if a central lesion or poor effort can be excluded. Further study of this novel technique is necessary. Muscle Nerve 27: 590–594, 2003
Quality Control of Cathode-Ray Tube Monitors for Medical Imaging Using a Simple Photometer

As computer monitors are used more in medical imaging and the use of picture archiving and communication system workstations with multiple monitors is increasing, quality control protocols become necessary to track subtle variations in performance characteristics. Several tests based on previously published work were applied to 10 monitors of three different types over a period of 5 months. Each test is explained, and the results are shown. For example, without corrective adjustments, 2 monitors from the same workstation showed a small but steady decline in maximum luminance of 8.1% and 7.6% over the course of 11 weeks that was not perceptible. From this experience, we took the first step toward developing a practical and useful quality control protocol. The proposed protocol requires only a photometer and the ability to generate the Society of Motion Picture and Television Engineers (SMPTE) test pattern, and takes approximately 5 minutes per monitor per week to gather data.
PHENOLOGY, SEED DISPERSAL, AND COLONIZATION IN MUNTINGIA CALABURA, A NEOTROPICAL PIONEER TREE

In this paper we describe the phenology, fruiting ecology, and colonization ability of a widespread neotropical pioneer tree, Muntingia calabura (Eleocarpaceae), in Costa Rican dry tropical forest. Individuals of M. calabura grow rapidly, flower at <2 yr age, and produce juicy red fruits containing thousands of tiny seeds that are eaten by a variety of frugivorous birds, bats, and monkeys. Although most individuals produce some flowers and fruit year-round, peak flowering occurs in the late dry season (April-May), and peak fruit availability occurs early in the wet season (May-June). Bats and parakeets are the maJor seed dispersers of M. calabura at our study site, and they concentrate their attention on this species at its fruit peak when few alternate fruits are available. Germinable M. calabura seeds accumulate in the forest soil in relatively high density in areas of high frugivore activity. M. calabura can quickly invade large disturbed areas with a high density of seedlings. Adult densities decline from thousands of individuals/ha to a few individuals/ha in a relatively few years. Clumps of M. calabura trees are replaced by later successional species in <30 yr. THE LIFE HISTORIES of colonizing plants are usually characterized by rapid growth, early reproductive maturity, high fecundity, short lifespans and genetic self-compatibility (Baker and Stebbins,1965;Harper,1977;Vasquez-Yanes,
A model for the turning snow ski

Abstract A model is developed to investigate the steady-state solutions of a turning snow ski. In computing equilibrium of the skier/ski system, two types of forces are assumed along the ski bottom: skidding forces , which arise when shearing a virgin snow surface, and carving forces , which maintain the curvature of the ski when it slides in its own track. Turn radius and speed are insufficient to specify a unique turn solution. To quantify the effects of different ski designs on the model, a range of possible solutions is calculated for each turn radius and speed and compared using two indices, one measuring the mechanical efficiency of the turn resulting from the energy dissipation of shearing the snow surface, and the second measuring the equilibrium solution sensitivity to human control and regulation. When possible solutions are mapped onto the plane of these two indices, a characteristic solution behavior emerges corroborating experimental results found using a model ski turning on astroturf. This behavior provides a quantitative basis for comparing different ski designs and proposing new design strategies.
Dst of the Carrington storm of 1859

Abstract The super-storm of 1859 gives an opportunity to apply models to predict Dst that have been exercised mostly on non-extreme cases. The exercise gains significance through a Bombay magnetogram that Tsurutani et al. (2003) recently published showing a negative H excursion of ∼1600 nT, which is unprecedented for the latitude of the station, and which presents difficulties of interpretation if the negative excursion is taken to be equivalent to Dst. Following a suggestion by Li et al. (2006) , we have replaced the original Bombay magnetogram, which has many points per hour during the interesting phase of the storm, by hourly averages, thereby constructing a time profile that is closer to a Dst profile as it is usually calculated. Then, the maximum H -depression is ∼−850 nT, which lies not so astonishingly outside the officially observed range. The Bombay magnetogram exhibits two major H -depressions, which we interpret to mean that the event was caused by a geoeffective ICME-sheath followed by a magnetic cloud across which the magnetic field rotated from north to south. On this interpretation, the ICME-sheath caused the extraordinary −1600 nT excursion in H . Then, the issue is whether this large excursion was produced by ionospheric currents (in which case it is not so exceptional) or by magnetospheric currents (in which case it is unprecedented)? To explore the second possibility, we use empirical models that relate the measured shock transit time to the ICME speed and peak magnetic field strength at 1 AU together with average pre-shock interplanetary conditions to construct geoeffective parameters throughout the ICME-sheath. We use the Burton et al. equation as modified by O’Brien and McPherron to calculate Dst. The resulting Dst profile lies reasonably close to hourly averaged Bombay magnetogram, especially if one uses the upper limit allowed for field strength in the ICME-sheath or if one discards the most extreme outlier of the Bombay measurements. We conclude that it is possible to interpret the Bombay magnetogram as having been produced by the magnetospheric currents.
Antennas for radiation measurements

RADIATION from diathermy, electronic heating, and other industrial devices is now subject to federal regulation. There is no commercial equipment available that is suitable for measuring electromagnetic fields at frequencies above 400 megacycles per second. The present procedure is to use the receiver-signal generator substitution method. This requires the use of a pickup device of known characteristics.
The U.S. Department of Energy’s Advanced Turbine Systems Program

Advanced Turbine Systems (ATS) are poised to capture the majority of new electric power generation capacity well into the next century. US Department of Energy (DOE) programs supporting the development of ATS technology will enable gas turbine manufacturers to provide ATS systems to the commercial marketplace at the turn of the next century. A progress report on the ATS Program will he presented in this paper. The technical challenges, advanced critical technology requirements, and system configurations meeting the goals of the program will be discussed. Progress has been made in the are as of materials, heat transfer, aerodynamics, and combustion. Applied research conducted by universities, industry, and Government has resulted in advanced designs and power cycle configurations to develop an ATS which operates on natural gas, coal, and biomass fuels. Details on the ATS Program research, development, and technology validation and readiness activities will be presented. The future direction of the program and relationship to other Government programs will be discussed in this paper.
InGaN/GaN Quantum Dot and Nanowire LEDs and Lasers

GaN-based InGaN/GaN self-organized quantum dots and InGaN quantum dots (disks) in GaN nanowires are important nanostructures with potential advantages over planar quantum wells, including luminescence at the longer visible wavelengths. We describe the epitaxy and characteristics of red-emitting InGaN/GaN quantum dot edge-emitting lasers and InGaN/GaN nanowire light emitting diodes, which can be used in a host of applications.
M2 subunit of ribonucleotide reductase is a target of cyclic AMP-dependent protein kinase

Cyclic AMP arrests T lymphocytes in the G1 phase of the cell cycle, and prolonged exposure results in cytolysis. Both of these effects require cyclic AMP-dependent protein kinase. We recently observed that some S49 mouse T lymphoma cell lines selected for hydroxyurea resistance were not arrested in G1 by cyclic AMP. Further analysis revealed that these cell lines were cyclic AMP-dependent protein kinase deficient, and conversely, other cyclic AMP-dependent protein kinase deficient cell lines not selected for hydroxyurea resistance were two- to threefold more hydroxyurea resistant. However, hydroxyurea is a specific inhibitor of ribonucleotide reductase and does not inhibit this kinase. We subsequently showed that cyclic AMP-dependent protein kinase will phosphorylate the M2 but not the M1 subunit of ribonucleotide reductase in vitro, and this phosphorylation will diminish CDP reductase activity. In vivo phosphorylation of M2 occurred under conditions similar to those that generate cell cycle arrest. We conclude that the M2 subunit of ribonucleotide reductase can be a target of cyclic AMP-dependent protein kinase. The phosphorylated enzyme has diminished activity, and this may play a role in cyclic AMP-induced lymphocyte cell cycle arrest.
Thalamic stimulation for primary writing tremor

We report a patient with primary writing tremor whose tremor was treated with thalamic stimulation. He had undergone trials of multiple oral medications with no benefit for his tremor. An electrode lead was implanted in the thalamic nucleus ventralis intermedius with nearly complete control of his tremor and no postoperative complications. We conclude that nucleus ventralis intermedius thalamic stimulation is safe and effective for primary writing tremor.
Spectrum of motor neuron diseases with HIV-1 infection

Background: The cause of sporadic motor neuron disease (MND) or amyotrophic lateral sclerosis (ALS) is unknown. During the last 20 years, at least 23 cases of MND have been reported in HIV-1 (HIV) seropositive individuals. Objective: To describe two patients with HIV infection and MND and to review the literature regarding HIV-associated MND. Setting: A multidisciplinary ALS center and Neuro-AIDS clinic at tertiary care university hospitals. Patients/Design: We prospectively studied two HIV-infected patients with motor neuron disease. A detailed review of the literature employing the PubMed search strategy revealed 23 additional cases of MND in HIV-infected persons. These were reviewed for comparison and contrast with the characteristics of sporadic classical MND. Results: The clinical features of MND in our two cases, mirrored that of the sporadic MND (upper and lower motor neuron disorder) and primary lateral sclerosis (PLS, isolated upper motor neuron disorder). The review of 23 previously reported patients with MND and HIV infection revealed that they could be categorized into clinically definite MND (6 cases) or clinically probable or possible MND (17 cases). MND commenced at different stages of the HIV; in 9 patients HIV infection was discovered contemporaneously with the diagnosis of MND. As in our one patient, 14 of 18 patients with HIV-associated MND syndrome receiving highly active antiretroviral therapy (HAART), demonstrated at least partial recovery of their motor deficit. Conclusions: A clinical picture similar to MND or PLS may occur in association with HIV infection. An aggressive HAART regimen to reduce viral load should be pursued in all such cases.
Bilayer stabilization of phosphatidylethanolamine by N-biotinylphosphatidylethanolamine.

Abstract We have examined the ability of biotinylated phosphatidylethanolamine and similar lipids to stabilize the bilayer phase of polymorphic dioleoylphosphatidylethanolamine (DOPE). Sonicated lipid mixtures were characterized in terms of their aggregation state, size and ability to encapsulate and retain the fluorescent dye, calcein. Titration of DOPE with N -biotinyl-PE indicated that stable liposomes could be produced by sonication of DOPE based dispersions containing N -biotinyl-PE at concentrations greater than 8 mol%. These liposomes were relatively small, could efficiently encapsulate calcein, and showed minimal leakage upon prolonged storage at 4°C. Maleimido-4-( p -Phenylbutyrate-PE (MPB-PE) was equally effective at stabilizing the bilayer phase of DOPE whereas N -dinitrophenyl-PE and N -(dinitrophenyl-caproyl)-PE were relatively poor stabilizers, requiring at least 15 mol% for stabilization at pH 7.4. Differential scanning calorimetry of dielaidoylphosphatidylethanolamine (DEPE)/ N -biotinyl-PE mixtures indicated that stabilizer concentrations as low as 2 mol% could abolish the L a /H ii phase transition of DEPE.
Crystal structure of a RuBisCO-like protein from the green sulfur bacterium Chlorobium tepidum.

Summary Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) catalyzes the incorporation of atmospheric CO 2 into ribulose 1,5-bisphosphate (RuBP). RuBisCOs are classified into four forms based on sequence similarity: forms I, II and III are bona fide RuBisCOs; form IV, also called the RuBisCO-like protein (RLP), lacks several of the substrate binding and catalytic residues and does not catalyze RuBP-dependent CO 2 fixation in vitro. To contribute to understanding the function of RLPs, we determined the crystal structure of the RLP from Chlorobium tepidum . The overall structure of the RLP is similar to the structures of the three other forms of RuBisCO; however, the active site is distinct from those of bona fide RuBisCOs and suggests that the RLP is possibly capable of catalyzing enolization but not carboxylation. Bioinformatic analysis of the protein functional linkages suggests that this RLP coevolved with enzymes of the bacteriochlorophyll biosynthesis pathway and may be involved in processes related to photosynthesis.
Preparation of a Class of Versatile, Chemoselective, and Amorphous Polyketoesters

A straightforward and versatile strategy for preparing a class of biodegradable and amorphous polyketoesters is reported. A series of ketone-containing diesters and diacids were combined with di(ethylene glycol) through condensation polymerization, achieving values of up to 10.1 × 103 g/mol. Glass transition temperatures ranged from −41 to −6 °C, rendering all of the materials liquid at room temperature. By including ketone groups in the repeat unit, facile postpolymerization modifications were possible by reaction with oxyamine-tethered ligands through the formation of an oxime linkage. Upon reaction with molecules that contain oxyamines, under mild conditions, these polymers can easily have a diverse set of side chains appended without coreagents or catalysts. The chemoselective oxime-forming coupling strategy is compatible with physiological conditions and can be done in the presence of a wide range of functional groups and biomolecules, including proteins and nucleic acids. We demonstrate the uti...
A Numerical Study on Influences of Hurricane Gloria (1985) on the Environment

Abstract The influence of Hurricane Gloria (1985) on the environment is investigated by comparing hurricane model integrations either including or excluding the hurricane in the initial condition. Results for three cases of Gloria at different states of development are presented. The hurricane's cumulative influence is identified as the differences between the hurricane and nonhurricane integrations. Throughout the integration period, area with sea level pressure differences exceeding 1 hPa in magnitude expanded in each of the three cases and was centered at the hurricane location. The influence radius of the storm, which was determined from the sea level pressure difference field, eventually reached approximately 1500 km in all cases. Comparisons of the sea level pressure differences among three cases showed that the expansion rate differed for each case but was only weakly related to the intensity or intensity change of the particular storm. The comparisons of the wind and temperature fields from the hu...
The Effect of Five Stocking Densities on Growth and Yield of Red Swamp Crawfish Procambarus clarkii

A 34-day study was conducted to estimate the effect of stocking density on growth, biomass, and yield of harvestable animals in red swamp crawfish, Procambarus clarkii (Girard). Juvenile crawfish were stocked at l, 2, 4, 8, and 16 crawfish per m2 into plastic-lined metal pools planted with rice (Oryza sativa) with three replicate pools at each density. Crawfish averaged 35 ± 1.5 mm (SE) total length at the time of stocking. Growth in total length and weight was significantly affected by density (P 75 mm total length) ranged from 100% at 1 per m2 to 0.7% at 16 per m2. Gross revenues per ha were projected for crawfish yields at each stocking density with and without a graded product.
Response of tertiary centres to pressure changes. Is there a mechano-electrical association?

Study objective – To investigate the mechanism of pressure related ventricular arrhythmias by examining them during atrioventricular (AV) block. Design – Complete AV block, where all ventricular beats are ectopic, was induced by AV node ablation and/or by toxic digitalisation, and rhythm changes were studied while arterial blood pressure was repeatedly raised and lowered. Subjects – 15 anaesthetised mongrel dogs, weight 15-28 kg, were used. AV block was induced in eight by chemical or mechanical ablation of the AV node. In five of these and in seven other dogs, 5.0-7.5 mg digoxin was also given. Measurements and results – Following AV block due to ablation, a heart rate increase (or no change) was found in 87.5% of 56 arterial pressure increases produced by elevation of an open arterial blood reservoir or by metaraminol infusion, but in only 21.8% of 55 pressure decreases caused by arterial bleeding (p≪0.001). Following AV block due to digitalisation, the equivalent figures were 96% of 50 pressure increases and 27.3% of 55 pressure decreases (p≪0.001). While arterial pressure was increased there was moderate acceleration of the escape rhythm, then appearance of premature ventricular beats, then non-sustained and finally sustained ventricular tachycardia. The reverse occurred, with some hysteresis, on decreasing the arterial pressure. In five of the digitalised animals, arterial pressure reduction to nearly zero caused reproducible sudden arrest, with resumption of the ordinary escape rhythm on increasing the pressure again. Conclusions – The findings suggest the possibility of two kinds of ectopic rhythm in AV block: the “normal” escape rhythm which is only moderately affected by arterial pressure changes; and an “abnormal” faster pressure dependent rhythm which is generated by high arterial pressure and abolished by pressure near zero, as if there were a mechano-electrical association. This abnormal rhythm may prevail completely in digitalis toxicity so that if cardiac arrest occurs, no automaticity can be expected to appear unless arterial pressure is raised.
The Free Radical Theory of Aging Is Dead. Long Live the Damage Theory

Abstract The free radical theory of aging posits that aging is caused by accumulation of damage inflicted by reactive oxygen species (ROS). Although this concept has been very useful in defining the contribution of oxidative damage to the aging process, an increasing number of studies contradict it. The idea that oxidative damage represents only one of many causes of aging also has limitations, as it does not explain causal relationships and inevitability of damage accumulation. Here, it is discussed that infidelity, heterogeneity, and imperfectness of each and every biological process may be responsible for the inevitable accumulation of by-products and other damage forms. Although ROS are prototypical by-products, their contribution to aging is governed by the metabolic organization of the cell, its protective systems, and genotype. These factors are controlled by natural selection and, like dietary and genetic interventions that extend lifespan, change the composition of cumulative damage and the rates...