bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-Temperature Transition of Normalized Carbon-Manganese Steels
Authors: Armstrong T. N. , Warner L. W.
Published: August 2009

In studying the literature on the properties of carbon and low-alloy steels at low temperatures (1), it will be noted that there does not appear to be particularly close agreement among different investigators on the effect of composition on transition temperature. Two of the most comprehensive reports (2, 3) give a clear indication of the effects of carbon and of manganese, although there is considerable doubt as to whether the specific quantitative values for each increment of carbon and of manganese derived from results in one of these papers would apply to commercial steels except under very limited conditions. The investigation reported here was undertaken to determine the energy-temperature relations for a number of carbon-manganese steels as one phase of a study of the effects of welding on the transition temperature. The objectives were, first, to attempt to resolve differences in published results of other studies and, second, to aid in the selection of a limited number of compositions for welding studies.
Effect of Specimen Width on the Notched Bar Impact Properties of Quenched-And-Tempered and Normalized Steels
Authors: Zeno R. S.
Published: August 2009

Data obtained from testing small specimens is commonly used by engineers in the design of large structures. Since the size and geometric configuration of a test specimen can greatly influence the test results, it is necessary to understand more about this effect and the limitations imposed in order to apply these test data sensibly. The present investigation was made to further the understanding of the effect of specimen geometry on the V-notch Charpy impact properties of oil-quenched-and-tempered E 9310 and normalized SAE 1020 steels. The general plan was to compare the impact properties of standard, one-half, and one-quarter width V-notch Charpy bars. The impact properties determined were the energy, fracture appearance, and contraction of area under the notch transition temperatures; energy per unit fracture area (under the notch); and energy per unit volume.
Reproducibility of Charpy Impact Test
Authors: Driscoll David E.
Published: August 2009

To demonstrate that the Charpy impact test is truly a reproducible test, a special heat of steel cut up to provide 18,000 blanks and heat treated to three energy levels was obtained by the Watertown Arsenal Laboratory. Two hundred specimens at each energy level were tested in Charpy machines manufactured by two different companies to obtain the deviation and average energy values. The remainder of the specimens are being used to check Charpy impact machines throughout the country to determine the causes of the variations encountered. Charts of some of the results obtained are shown and discussed.
Relaxation Properties of Steels and Super-Strength Alloys at Elevated Temperatures
Authors: Freeman James W. , Voorhees Howard R.
Published: August 2009

Tabulated data and graphical presentations summarize relaxation strengths for low-alloyed Mo-, Cr-, and V- bearing steels with numerous other composition modifications, 12 per cent Cr type steels with many compositional variations, a number of super-strength alloys, and cast iron. Residual stresses for relaxation to 100, 500, 1000 and 10,0000 hr are the main measure of relaxation strength. A lesser amount of data for the 10-hr relaxation strengths are given in some cases. The temperatures covered mainly range from 750 to 1100 F with data at 1200 to 1500 F for super-strength alloys. One set of data shows relaxation of high-strength carbon-steel wires at room temperature. The tabulated data also include chemical composition, heat treatment, mechanical properties at room temperatures, and limited creep data. The relaxation strengths are shown graphically to indicate the ranges of values for the individual alloys. In this form, the range in strength for a given alloy was frequently rather wide. This was found to be mainly due to variations in initial stress, heat treatment and major alloying elements. When sufficient data were available, graphical correlations were included to define the effect of these variables. It was very evident that direct comparison of relaxation strengths of different alloys could only be made on the basis of nearly similar initial stress. Curves of relaxation strength versus temperature on a reasonably comparative basis were developed in so far as possible for a single initial stress at each temperature. These initial stresses were arbitrarily based on those stresses for which most data were available. The comparative curves are also based on data for most usual conditions of heat treatment for each alloy. It is important to clearly understand that the level of relaxation strength indicated by the comparative curves would be different for any other initial stress in a majority of the materials tested and are therefore in no sense average strengths.
Introduction
Authors: Olmstead Paul S.
Published: August 2009

The Administrative Committee on Ultimate Consumer Goods of the American Society for Testing Materials has found that before meaningful tests can be devised for such goods, it is necessary to have a clear picture of what consumers want. It has been suggested that the way to find out is to interview a number of people. That this process is not as simple as we might expect is indicated time and again in this symposium. Interviews even when based on specific questions do not always provide correct answers. Sometimes, answers have been not only wrong but misleading. Since most of the evidence on this point has been obtained by people working in the Social Sciences, we have asked them to tell us why. What they have found out that might be of interest to us is considered in the second part of this symposium. We engineers should profit by their experience. In contrast, the first part of the symposium presents problems with which the engineer is more familiar. They represent cases where product tests have been or are being developed. The consumer involved happens to be a soldier. Otherwise, the problems are similar to some that are even now being considered by ASTM committees.
Introduction
Authors: Dickerson B. W.
Published: August 2009

The proper operation of water purification works, whether for potable, plant service, or boiler feed requires control. This control is based on analytical determination, all chemical, made on both the influent and effluent of the plant. The making of these entails laboratory personnel. In the treatment of industrial waste waters control is also necessary, entailing chemical and bacteriological analysis also made in the laboratory. In the past, standards of purity were low and the tests simple. Analytical procedures had not been developed that were extremely accurate and, as a consequence, water standards had to be low. Measurement could not be any better. Processes were also relatively simple, boiler pressures were low, and waste treatment for industrial effluents had not entered the picture. Manpower requirements were low both in quality and quantity.
Some Practical Aspects of the Measurement of pH, Electrical Conductivity, and Oxidation-Reduction Potential of Industrial Water
Authors: Rosenthal Robert
Published: August 2009

It is undoubtedly true that larger quantities of water are used in industry than the aggregate of all other materials. The variety of functions which water serves, as well as the circumstances under which testing of water quality is necessary, are proportionately numerous. The minimum chemical and physical requirements, including the presence and concentration of certain critical constituents, vary greatly from use to use. As a consequence, a proper selection of tests must be made on the basis of specific requirements dictated by the service. Where throughput is small or operations performed batchwise, periodic sampling and testing are usually adequate. However, the growth in complexity and size of industrial plants, particularly in the chemical, power, and process fields, has brought with it an ever-increasing rate of material flow, including water, which for closest control requires continuous automatic measurement of all significant variables. It is in this light that measuring equipment for pH, electrical conductivity, and oxidation-reduction potential and their limitations will be considered.
Continuous Measurement of Dissolved Gases in Water
Authors: Rummel J. K.
Published: August 2009

The continuous measurement of dissolved gases in water is discussed with special regard to selection of a method, the general methods which are available and the application of these methods to specific gases and conditions. Reference is made to the continuous measurement of dissolved oxygen, hydrogen, sulfur gases, methane, chlorine, and other gases found in water. It is observed that practical continuous recording apparatus has not been developed for all of the applicable methods which are mentioned.
Introduction
Authors: Burns Robert
Published: August 2009

Probably no facet of testing technology is more continuously dynamic than conditioning and its highly temperamental cousin, weathering. Although the weather has been with us for a long time all efforts to tame it have been singularly unsuccessful and all attempts to reproduce it quite discouraging to all but the intellectually stalwart. The fact remains that many of our highly useful engineering materials are affected by atmospheric influences, mostly adversely. Therefore it is obvious that the struggle to reproduce these influences is a vital part of our scientific endeavors and must proceed at any cost. Let us be frank: conditioning and weathering is no place for the weak-kneed, or the fellow who must see success around the corner. Mother Nature never relaxes her efforts to fool us. Those who have elected to reproduce her fantastic vagaries, including the authors of this Symposium, must be admired for the technological competence and dogged persistence which have resulted in a striking advancement of the frontiers of knowledge in a field notoriously difficult. Prime responsibility for establishment of standard conditioning and weathering procedures rests in the Technical Committees covering the various materials. The sponsor of this Symposium, Committee E-1 on Methods of Testing, is a Society-wide group having as one of its functions the dissemination of knowledge valuable to all committees. One of the purposes of the Symposium, perhaps its principal one, is to provide a broad picture of the art in terms of particular materials so that a technologist in paper, for example, will be exposed to the latest thinking in textiles, plastics, adhesives, coatings, etc.—thus not only advancing the art for all industry but minimizing duplication within the Society.
Air Conditioning in the Manufacture and Testing of Textiles
Authors: Brown R. H.
Published: August 2009

In the various textile manufacturing departments from opening to weaving or knitting, economical production and good product quality usually require the maintenance and automatic regulation of relative humidity at levels somewhere between 50 and 80 per cent. Temperature is usually maintained at 75 F or above for good fiber manipulation, the desirable maximum being largely a matter of comfort. Examples are given of the drying effect of heat and the cooling effect of evaporation. The benefits of air conditioning in the manufacture and testing of textiles are reviewed. Principal types and functions of humidifying and air conditioning systems suited to textile mill use are classified. The ASTM standard atmosphere for textile testing is defended.
Laboratory Air Conditioning
Authors: Stacey A. E.
Published: August 2009

The American Society for Testing Materials has through its Subcommittee 14 on Conditioning and Weathering of Committee E-1 on Methods of Testing specified the temperature and humidity for the conditioning and testing of many materials. In the majority of cases, the specified conditions are suitable not only for the materials being tested, but also for the comfort and efficiency of the laboratory personnel. Although the majority of the specified conditions may vary slightly from a standard laboratory condition of 23 C (73.4 F) and 50 per cent relative humidity, the same type of air conditioning equipment with slight variations would be applicable to all. There are, however, several types of laboratories with varying fundamental air conditioning requirements. These may be divided as follows: (1) the control laboratory, (2) the research laboratory, and (3) the development laboratory. Each of these has special problems from an air conditioning standpoint. Production control laboratories are standardized throughout. Day after day, the same procedures must be carried out on the same material in the same way. Everything possible is standardized. The same number of lights, the same number of personnel, the same heat-producing equipment, and in some cases the same number of exhaust hoods removing the same volume of conditioned air from the laboratory, are all constant. This is ideal from the standpoint of air conditioning, as the function of an air conditioning system is to absorb heat from all sources, maintain constant temperature, and humidity conditions, and supply ample ventilation to protect the health of the laboratory technicians. The more nearly constant the heat sources are, the simpler will be the control of temperature and humidity.
Accelerated Weathering Devices
Authors: Sawyer Roscoe H.
Published: August 2009

The preceding papers of this Symposium have shown that weather is composed of many separate factors such as light, temperature, and moisture. They have shown that although these weather factors show cyclical rhythm, the factors are subject to wide variation with time and place. These papers have also shown that materials exposed to the weather change usually for the worse and that the rates of change vary as the intensity of the weather factors vary. For most materials the changes brought about by exposure to the weather proceed slowly. The impatient laboratory worker is unwilling to await the outcome of normal weather exposure tests and has displayed great energy and ingenuity in the development of means of bringing weather into the laboratory and speeding up the changes weathering causes. The purpose of this paper is to discuss these efforts. One may assume that the cyclical behavior of weather was recognized long before man recognized the effect of weather on materials, but it seems safe to assume that both recognitions antedate written records. I have made no attempt to pursue this line of thought or to develop any history of early efforts to speed up and to control the process.
The Place of the Direct Shear Test in Soil Mechanics
Authors: Burmister Donald M.
Published: August 2009

The principal use of the direct shear test in soil and foundation work is the determination of the maximum shearing strength and angle of friction of soils for use in stability analyses. The angle of friction of a soil has been assumed to be an inherent property, which is not affected to any appreciable extent by the conditions imposed in the field during and subsequent to construction and by the test procedures used. The purpose of this paper is to show that it is most important to understand fully the fundamental concepts and mechanics of shearing phenomena and shear testing in order properly to make shearing tests and particularly to obtain and to use test results that have a direct and significant application to the stability problems under consideration. Consideration is given to the fundamental concepts of stress conditioning of the shearing strength characteristics of soils by consolidation under the initial stresses imposed upon the soils and to the character and influence of the stress and strain restraint conditions imposed in the direct shear test. A comparison is made with the probable restraint conditions inherent in natural situations and imposed by structures and construction operations. Applications are made which illustrate the necessity for and the practical importance and advantages of controlled test methods in direct shear testing.
The Use of the Direct Shear Testing Machine in Foundation Engineering Practice
Authors: Converse Frederick J.
Published: August 2009

The time element is frequently an important consideration in the practice of foundation engineering. Where the foundation soils are irregularly bedded and variable in character, many tests are needed, and the direct shear testing machine becomes a valuable tool for the determination of the variations in soil strength, because of the speed with which tests can be made. In order to insure accuracy, it is important that the design of the testing machine and the method of test be definitely established. It is urged that the development of such a standard be undertaken by the American Society for Testing Materials.
Harmony Perception: Harmoniousness is More Than the Sum of Interval Consonance
Authors: Cook Norman D.
Published: August 2009

ATTEMPTS TO EXPLAIN HARMONY PERCEPTION SINCE Helmholtz (1877/1954) have relied primarily on psychoacoustical models of the dissonance among the partials of chord tones. Those models are successful in explaining interval perception and the interval structure of common scales, but do not account for even the basics of triadic harmony. By introducing a 3-tone "tension" factor, I show how the sonority of the triads of diatonic music can be explained.Moreover, the relative size of the intervals among the partials in triads determines the major/minor modality of chords: major chords have a predominance of larger lower intervals, while minor chords have a predominance of smaller lower intervals. Finally, by invoking the "frequency code" known from linguistics and ethology, the positive/negative valence of the major/minor chords is shown to have an acoustical basis. I conclude that the perception of harmony can be explained by the acoustical structure of triads, without invoking cultural factors.
Adaptive Divergence in Experimental Populations ofPseudomonas fluorescens. IV. Genetic Constraints Guide Evolutionary Trajectories in a Parallel Adaptive Radiation
Authors: McDonald Michael J , Gehrig Stefanie M , Meintjes Peter L , Zhang Xue-Xian , Rainey Paul B
Published: August 2009

The capacity for phenotypic evolution is dependent upon complex webs of functional interactions that connect genotype and phenotype. Wrinkly spreader (WS) genotypes arise repeatedly during the course of a model Pseudomonas adaptive radiation. Previous work showed that the evolution of WS variation was explained in part by spontaneous mutations in wspF, a component of the Wsp-signaling module, but also drew attention to the existence of unknown mutational causes. Here, we identify two new mutational pathways (Aws and Mws) that allow realization of the WS phenotype: in common with the Wsp module these pathways contain a di-guanylate cyclase-encoding gene subject to negative regulation. Together, mutations in the Wsp, Aws, and Mws regulatory modules account for the spectrum of WS phenotype-generating mutations found among a collection of 26 spontaneously arising WS genotypes obtained from independent adaptive radiations. Despite a large number of potential mutational pathways, the repeated discovery of mutations in a small number of loci (parallel evolution) prompted the construction of an ancestral genotype devoid of known (Wsp, Aws, and Mws) regulatory modules to see whether the types derived from this genotype could converge upon the WS phenotype via a novel route. Such types—with equivalent fitness effects—did emerge, although they took significantly longer to do so. Together our data provide an explanation for why WS evolution follows a limited number of mutational pathways and show how genetic architecture can bias the molecular variation presented to selection.
Imprinting of the Y Chromosome Influences Dosage Compensation inroX1 roX2 Drosophila melanogaster
Authors: Menon Debashish U , Meller Victoria H
Published: August 2009

Drosophila melanogaster males have a well-characterized regulatory system that increases X-linked gene expression. This essential process restores the balance between X-linked and autosomal gene products in males. A complex composed of the male-specific lethal (MSL) proteins and RNA is recruited to the body of transcribed X-linked genes where it modifies chromatin to increase expression. The RNA components of this complex, roX1 and roX2 (RNA on the X1, RNA on the X2), are functionally redundant. Males mutated for both roX genes have dramatically reduced survival. We show that reversal of sex chromosome inheritance suppresses lethality in roX1 roX2 males. Genetic tests indicate that the effect on male survival depends upon the presence and source of the Y chromosome, revealing a germ line imprint that influences dosage compensation. Conventional paternal transmission of the Y chromosome enhances roX1 roX2 lethality, while maternal transmission of the Y chromosome suppresses lethality. roX1 roX2 males with both maternal and paternal Y chromosomes have very low survival, indicating dominance of the paternal imprint. In an otherwise wild-type male, the Y chromosome does not appreciably affect dosage compensation. The influence of the Y chromosome, clearly apparent in roX1 roX2 mutants, thus requires a sensitized genetic background. We believe that the Y chromosome is likely to act through modulation of a process that is defective in roX1 roX2 mutants: X chromosome recognition or chromatin modification by the MSL complex.
Telomerase Is Essential to Alleviate Pif1-Induced Replication Stress at Telomeres
Authors: Chang Michael , Luke Brian , Kraft Claudine , Li Zhijian , Peter Matthias , Lingner Joachim , Rothstein Rodney
Published: August 2009

Pif1, an evolutionarily conserved helicase, negatively regulates telomere length by removing telomerase from chromosome ends. Pif1 has also been implicated in DNA replication processes such as Okazaki fragment maturation and replication fork pausing. We find that overexpression of Saccharomyces cervisiae PIF1 results in dose-dependent growth inhibition. Strong overexpression causes relocalization of the DNA damage response factors Rfa1 and Mre11 into nuclear foci and activation of the Rad53 DNA damage checkpoint kinase, indicating that the toxicity is caused by accumulation of DNA damage. We screened the complete set of ∼4800 haploid gene deletion mutants and found that moderate overexpression of PIF1, which is only mildly toxic on its own, causes growth defects in strains with mutations in genes involved in DNA replication and the DNA damage response. Interestingly, we find that telomerase-deficient strains are also sensitive to PIF1 overexpression. Our data are consistent with a model whereby increased levels of Pif1 interfere with DNA replication, causing collapsed replication forks. At chromosome ends, collapsed forks result in truncated telomeres that must be rapidly elongated by telomerase to maintain viability.
Outcome of Extreme Prematurity: A Prospective Comparison of 2 Regional Cohorts Born 20 Years Apart
Authors: Bode Michelle M. , D'Eugenio Diane B. , Forsyth Nancy , Coleman Janice , Gross Caroline R. , Gross Steven J.
Published: August 2009

OBJECTIVE: To determine changes that have occurred over the past 20 years in perinatal characteristics, neonatal treatments, morbidities, and early neurodevelopmental outcomes of infants born at ≤30 weeks' gestation.

METHODS: This was a prospective regional study including all live-born infants ≤30 weeks' gestation born between July 1985 and June 1986 (cohort 1) and July 2005 and June 2006 (cohort 2). Sociodemographically matched term controls were recruited for each cohort. Perinatal characteristics, mortality rates, and survival with and without impairments at 24 months' corrected age were compared.

RESULTS: There was a 35% increase in the number of live-born preterm births (138 in cohort 1 and 187 in cohort 2) despite a >10% decline in total births in the region (P < .001). Assisted fertility (rarely available for mothers in cohort 1) was responsible for 20% of pregnancies in cohort 2. Survival to hospital discharge increased over 20 years from 82% to 93% (P = .002), primarily because of higher survival for infants born at <27 weeks' gestation (63% vs 88%; P = .004). Changes in management in cohort 2 included the use of surfactant (62% of infants) and increased use of postnatal steroids (39% vs 9%; P < .001), that were associated with a shorter median duration of mechanical ventilation (13 vs 21 days; P < .001); however, the incidence of bronchopulmonary dysplasia was higher in cohort 2 (56% vs 35%; P < .001). There was a significant decrease in incidence of severe ultrasound abnormalities from 17% in cohort 1 to 7% in cohort 2 (P = .008). At 24 months of age, 7% of cohort 1 and 5% of cohort 2 had an abnormal neurologic exam. Bayley cognitive scores were improved in cohort 2 (significantly closer to the mean of their controls). As a result, survival without severe neurodevelopmental impairment increased from 62% in cohort 1 to 81% in cohort 2 (P < .001).

CONCLUSION: Over 20 years, there has been a significant increase in live births at ≤30 weeks' gestational age, with a greater percentage of these neonates surviving without severe neurodevelopmental impairment at 24 months.
Glucose Metabolism in Overweight Hispanic Adolescents With and Without Polycystic Ovary Syndrome
Authors: Nur Marcela M. , Newman Ilana M. , Siqueira Lorena M.
Published: August 2009

OBJECTIVES: About one third of overweight women with polycystic ovary syndrome (PCOS) have either impaired glucose tolerance (IGT) or type 2 diabetes mellitus (DM) by the age of 30. We sought to determine if overweight Hispanic adolescents with PCOS are more likely to be insulin resistant and glucose intolerant than those without PCOS.

METHODS: A retrospective chart review of 101 subjects with PCOS and 40 without PCOS was conducted. Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), Quantitative Insulin Sensitivity Check Index (QUICKI), and fasting glucose/insulin ratio (FGIR) values were calculated by using fasting glucose and insulin levels. Insulin resistance (IR) was defined as a fasting insulin level of >15 μU/mL, a 2-hour insulin level of >75 μU/mL, a HOMA-IR value of >3.16, a QUICKI value of <0.357, and/or a FGIR value of <7.

RESULTS: Of the 101 overweight subjects with PCOS (BMI: 33.2 ± 5.9 kg/m2), 4 had IGT and 2 had DM versus none of the 40 subjects without PCOS (BMI: 32.4 ± 5.3 kg/m2). IR was more frequent in the overweight PCOS than in the overweight non-PCOS group (QUICKI: 68.4% vs 14.3%, P = .014) and FGIR (47.4% vs 0%, P = .024). Of the 6 subjects with glucose intolerance, only the QUICKI value was abnormal in all.

CONCLUSIONS: This retrospective study demonstrated that overweight Hispanic adolescents with PCOS had more IR, IGT and DM than their non-PCOS counterparts. As the QUICKI Index was abnormal in all subjects with IGT and DM, we suggest its use as the first step in deciding which overweight Hispanic adolescents with PCOS should be further tested with an OGTT.
Parents' Interest in Predictive Genetic Testing for Their Children When a Disease Has No Treatment
Authors: Tarini Beth A. , Singer Dianne , Clark Sarah J. , Davis Matthew M.
Published: August 2009

OBJECTIVE: The goal was to measure parents' interest in obtaining predictive genetic testing for their children for a disease that has no treatment.

METHODS: We conducted a nationally representative, Internet-based survey of parents. Parents received 2 vignettes describing hypothetical diseases without treatments. The first vignette described a disease in which symptoms were severe and timing of symptom onset was uncertain. The second vignette described a disease in which both symptom severity and timing of symptom onset were uncertain. Parents reported their interest in predictive genetic testing for their youngest child in each vignette by using a 5-point Likert scale. We collected information on parents' demographic features and parents' general opinions about genetic testing. We conducted logistic regression analyses to evaluate the independent associations between these factors and parents' interest in testing for both vignettes.

RESULTS: The response rate was 71%. For the first vignette, 35% of parents were definitely or probably interested in predictive genetic testing for their youngest child, 35% were unsure, and 31% were definitely or probably not interested. Responses were similar for the second vignette. More than one fourth of parents consistently expressed interest in testing in both vignettes.

CONCLUSIONS: Approximately one third of parents are interested in predictive genetic testing for their children, even for disorders with no treatment. Uncertainty about the severity of symptoms was not related to parents' testing preferences.
Cerebral Arteriopathy in Children With Neurofibromatosis Type 1
Authors: Rea David , Brandsema John F. , Armstrong Derek , Parkin Patricia C. , deVeber Gabrielle , MacGregor Daune , Logan William J. , Askalan Rand
Published: August 2009

OBJECTIVE: Cerebrovascular abnormalities are serious but underrecognized complications of neurofibromatosis type 1 (NF1). The aim of this study was to investigate the prevalence, clinical presentation, imaging findings, and prognosis of cerebral arteriopathies in childhood NF1.

METHODS: Patients followed at the NF1 clinic at the Hospital for Sick Children, Toronto, Ontario, Canada, between 1990 and 2007 were studied. Patients with confirmed NF1 diagnosis and neuroimaging results were included. All neuroimaging studies were reviewed for the presence of arteriopathy by 2 study pediatric neuroradiologists blinded to clinical information. Clinical records of children with cerebral arteriopathy were reviewed.

RESULTS: Among 419 children with confirmed NF1, 266 (63%) received neuroimaging. Among children with neuroimaging results, 17 had cerebral arteriopathy (minimum prevalence rate of 6%). Among the 35 patients who received magnetic resonance angiography (MRA), arteriopathy was more common in patients with NF1 with optic gliomas (11 of 21) compared with those without optic glioma (4 of 14). Forty-seven percent of children developed focal deficits months to years after the diagnosis of the arteriopathy. Follow-up at a mean of 7 years after diagnosis of arteriopathy showed that 35% (6 of 17) had progressive arteriopathy requiring revascularization surgery. Seven patients received aspirin for primary stroke prevention. On retrospective review of imaging studies, a mean delay of 51 months to clinical radiographic reporting of these findings was observed.

CONCLUSIONS: The prevalence of cerebral arteriopathy in children with NF1 in this study was at least 6% and was associated with young age and optic glioma. Arteriopathy causes stroke with resultant neurologic deficits. Medical and/or surgical interventions may prevent these complications. Therefore, the addition of vascular imaging (MRA/conventional angiography) to brain imaging studies for early detection of arteriopathy should be considered for children with NF1, particularly young patients with optic glioma.
Proton Transfer on the Molecular Surface of Proteins and Model Systems
Authors: Friedman Ran
Published: August 2009

Proton transfer (PT) reactions take place on the molecular surface of proteins, membranes, ionic polymers, and other molecules. The rates of the reactions can be followed experimentally, while the atomistic details can be elucidated by molecular modeling. This manuscript gives a brief overview of the use of computer simulations and molecular modeling, in conjuction with experiments, to study PT reactions on the surface of solvated molecules. An integrative approach is discussed, where molecular dynamics simulations are performed with a protein, and quantum‐mechanics‐based calculations are performed on a small molecule. The simulation results allow the identification of the necessary conditions that yield PT reactions on the molecular surface. The reactions are efficient when they involve a donor and acceptor located a few Å apart and under the influence of a negative electrostatic field. In proton‐pumping proteins, it is possible to identify such conditions a priori and locate proton‐attracting antenna domains without the need to mutate each potential donor and acceptor. Based on density functional theory calculations, the arrangement of water molecules that interconnect the donor and acceptor moieties is suggested as the rate‐limiting step for proton transfer on the molecular surface.
OHO Hydrogen Bond Geometries and NMR Chemical Shifts: From Equilibrium Structures to Geometric H/D Isotope Effects, with Applications for Water, Protonated Water, and Compressed Ice
Authors: Limbach Hans‐Heinrich , Tolstoy Peter M. , Pérez‐Hernández Natalia , Guo Jing , Shenderovich Ilya G. , Denisov Gleb S.
Published: August 2009

Hydrogen bond geometries and 1H NMR chemical shifts of OHO hydrogen‐bonded systems have been analyzed using an improved valence bond order model. This model predicts that the heavy atom hydrogen bond coordinate q2 = r1 + r2 is a function of the proton coordinate q1 = (r1 ‐ r2), where r1 and r2 represent the OH and the HO distances.

In the first part, it is shown that this correlation reproduces published equilibrium geometries of the Zundel cation H5O2+ as well as those of water clusters in the gas phase and embedded in the fullerene C180. Using the example of the water hexamer, it is shown that changing the level of calculation shifts the calculated geometries along the correlation curve, but not away from the curve. In order to take quantum zero‐point vibrational effects (QZPVE) into account, an empirical correction is proposed. It is shown that this correction properly describes the calculated classical and quantum hydrogen bond geometries of compressed ice as well as calculated geometric H/D isotope effects. The improved valence bond order model is used to analyze a large number of OHO hydrogen bond geometries contained in the Cambridge Structural Database.

In the second part, a relation between the geometries and the 1H NMR chemical shieldings of OHO hydrogen bonded systems is established using the valence bond order model. GIAO calculations of the isolated symmetric Zundel cation where H is located in the hydrogen bond center show only a small dependence of the chemical shifts on the O…O distance. This result is rationalized in terms of neighbor group effects and deshielding in the naked proton. The consequence is that the 1H NMR chemical shifts are not much affected by QZPVE. Calculations on water clusters indicate that the influence of the chemical environment of the OHO hydrogen bonds on their 1H NMR chemical shifts is smaller for the strong hydrogen bond regime but large for the weak hydrogen bond regime. A simple chemical shift vs. q1 relation is then used to calculate the average chemical shifts of water clusters in the regime of fast hydrogen bond exchange between hydrogen bonded and free OH groups. It is shown that average chemical shifts of about 6 ppm are possible as the clusters considered exhibit a broad distribution of stronger and weaker hydrogen bonds. The implications for water in organic solvents and for liquid water are discussed, based on published data on the 1H chemical shift distribution in the latter.
Excited‐State Proton Transfer in Chiral Environments: Photoracemization of BINOLs
Authors: Solntsev Kyril M. , Bartolo Elizabeth‐Ann , Pan George , Muller Gilles , Bommireddy Shruthi , Huppert Dan , Tolbert Laren M.
Published: August 2009

We have studied excited‐state proton transfer (ESPT) from chiral proton donors to chiral and achiral acceptors. The key role of the exergonicity of the reaction and the transition‐state position along the reaction coordinate for the existence of an enantiomeric effect was established. This effect was observed for “super” photoacids (ΔG ≪ 0) and vanished for endergonic reactions (ΔG > 0) where a “late” transition state similar to planar achiral binaphtholate anion occurs. As a result, photoracemization was observed, as confirmed by circular dichroism spectroscopy. The photoracemization effects were studied for several chiral photoacids (BINOLs and their ethers) and proton acceptors (amines, aminoalcohols, and water) using UV‐vis, steady‐state fluorescence, and time‐resolved fluorescence spectroscopies. The nature of the solvent and the proton acceptor, as well as the chemical structure of the BINOL, played a pivotal role in the photochemical reactivity of the system. Two proposed pathways competed for photoracemization: excited‐state inter‐ and intra‐molecular proton transfer, the former being more effective. Irradiation of the dimethoxy BINOL derivative, which lacks an acidic proton and cannot undergo ESPT, produced no appreciable reaction or racemization.
Cation‐Enhanced Deprotonation of Water by a Strong Photobase
Authors: Munitz Noga , Avital Yotam , Pines Dina , Nibbering Erik T. J. , Pines Ehud
Published: August 2009

We have used picosecond fluorescence spectroscopy to study the proton‐dissociation dynamics of bulk water and H2O molecules solvating Mg2+ ions in aqueous solutions. We have analyzed the photo‐initiated proton‐transfer reaction to a photobase 6‐aminoquinoline by the Collins‐Kimball approach and have modeled the ensuing bimolecular reaction dynamics by the Smoluchowski equation with radiation boundary conditions. We have found the on‐contact proton transfer rate to follow the Marcus free‐energy relation for proton transfer and estimate by this rate‐equilibrium correlation the considerable enhancement in the acidity of the water molecules solvating the Mg2+ ion. Our findings may be used in the study of metallo‐enzymes such as carbonic anhydrases (CAs), which catalyze the reversible addition reaction of OH− to CO2 by increasing the reactivity of the zinc‐bound water molecules by means of stabilizing the product of water dissociation, the OH− anion.
Visual impairment and blindness: an overview of prevalence and causes in Brazil
Authors: Salomão Solange R. , Mitsuhiro Márcia R. K. H. , Belfort Jr Rubens
Published: August 2009

Our purpose is to provide a summary overview of blindness and visual impairment on the context of recent Brazilian ocular epidemiologic studies. Synthesis of data from two cross-sectional population-based studies - the São Paulo Eye Study and the Refractive Error in School Children Study is presented. 3678 older adults and 2441 school children were examined between July 2004 and December 2005. Prevalence of blindness in older adults using presenting visual acuity was 1.51% decreasing to 1. 07% with refractive correction. The most common causes of blindness in older adults were retinal disorders, followed by cataract and glaucoma. In school children, the prevalence of uncorrected visual impairment was 4.82% decreasing to 0.41% with refractive correction. The most common cause of visual impairment in school children was uncorrected refractive error. Visual impairment and blindness in Brazil is an important public health problem. It is a significant problem in older Brazilians, reinforcing the need to implement prevention of blindness programs for elderly people with emphasis on those without schooling. In school-children cost-effective strategies are needed to address a readily treatable cause of vision impairment - prescription and provision of glasses.
Pregnancy and multiple sclerosis: the initial results from a Brazilian database
Authors: Fragoso Yara Dadalti , Finkelsztejn Alessandro , Comini-Frota Elizabeth Regina , Gama Paulo Diniz da , Grzesiuk Ansderson Kuntz , Khouri Jussara Mathias Netto , Alves-Leon Soniza Vieira , Morales Rogério de Rizo , Lana-Peixoto Marco Aurélio , Rocha Cristiane Franklin da
Published: August 2009

PURPOSE: Pregnancy management poses an extra challenge to physicians and their multiple sclerosis (MS) patients. There are few papers reporting databases on the subject. METHOD: Brazilian database from nine MS clinical and research units, with complete data on 47 pregnant women (49 pregnancies). RESULTS: Despite relatively high exposure to MS medications, no birth defects were reported. Low birth weight and prematurity were similar to those for developing countries. Three complications may have been associated with these medications, while three others were considered to be of purely obstetric nature. CONCLUSION: Our results confirm previous findings on lower relapse rate during pregnancy and add to the present literature informing on data related to drug exposure.
Psychiatric disorders in multiple sclerosis patients
Authors: Fazzito Mirella Martins , Jordy Sérgio Semeraro , Tilbery Charles Peter
Published: August 2009

Multiple sclerosis (MS) is a demyelinating disease showing variable clinical presentation. Optic neuritis is the most common symptom, followed by motor and sensitive manifestations. It is known that this disease may be related to several psychiatric disorders, especially depression. In this study we will discribe 5 cases of MS patients harboring psychiatric disorder related or unchained by the disease itself.
Comida de rua e intervenção: estratégias e propostas para o mundo em desenvolvimento
Authors: Cardoso Ryzia de Cassia Vieira , Santos Sandra Maria Chaves dos , Silva Edleuza Oliveira
Published: August 2009

Este trabalho tem por objetivo abordar estratégias de intervenção apresentadas para o segmento de comida de rua, com base em estudos e relatos nacionais e internacionais. Segundo a literatura, verifica-se um caráter abrangente das estratégias de intervenção, contemplando ações voltadas para vendedores, consumidores, recursos humanos da administração pública e para o desenvolvimento de tecnologias apropriadas. Em relação aos vendedores, as estratégias evidenciam a necessidade de regulação da atividade, do estabelecimento de normas, diretrizes ou códigos sanitários para a atividade e do treinamento para manipuladores e vendedores. Para os consumidores, as ações compreendem principalmente o desenvolvimento de programas educativos. Na esfera da administração pública, as estratégias voltam-se para a capacitação de recursos humanos. Quanto às tecnologias apropriadas, são identificadas duas possibilidades: a construção de centros especializados para venda da comida de rua e a melhoria dos pontos de venda já existentes. Conclui-se que, diante da expansão do comércio de comida de rua e do potencial de risco sanitário inerente, a literatura aponta estratégias para organização do setor, que podem subsidiar o desenvolvimento de políticas sociais para o segmento no Brasil.
Comparison of Craniofacial and Dentoalveolar Morphologies of Three Japanese Monozygotic Twin Pairs with Cleft Lip and/or Palate Discordancy
Authors: Moriyama Keiji , Motohashi Nobuyoshi , Kitamura Atsushi , Kuroda Takayuki
Published: August 2009

Objective

In this study, we analyzed the craniofacial and dentoalveolar morphologies of three pairs of monozygotic twins discordant for cleft lip and/or palate (CL/P) in order to evaluate the effects of environmental factors on growth and development.

Design

Craniofacial and dentoalveolar morphologies revealed by analyses of cephalograms and dental casts were compared for each pair of twins discordant for CUP.

Subjects

In case 1, the subjects were 10-year-old male twins, one of whom had a repaired unilateral cleft lip and alveolus and one of whom had an unrepaired unilateral cleft lip. In case 2, the subjects were 13-year-old female twins, one of whom had a repaired bilateral cleft lip and palate and one of whom had an unrepaired unilateral cleft lip. In case 3, the subjects were 9-year-old female twins, one of whom had a repaired unilateral cleft lip and palate and one of whom had no cleft.

Results

Cephalometric analysis disclosed distinguished intrapair differences in the maxillary and mandibular morphologies in cases 2 and 3. However, the tooth axes of the incisors in operated subjects were consistently influenced in all three cases. Dental cast analysis indicated that the shapes and sizes of the alveolar and dental arches in the operated subjects were affected in case 2 and, more severely, in case 3, while they looked fairly similar in case 1.

Conclusions

Cephalometric and dental cast analyses demonstrated characteristic intrapair differences between the twins discordant for CL/P according to each cleft type. These morphological differences indicate that surgical closure of clefts may have considerable effects on craniofacial and dentoalveolar growth and development in CL/P patients.
Approaches for Quantifying and Managing Diffuse Phosphorus Exports at the Farm/Small Catchment Scale
Authors: McDowell Richard W. , Nash David , George Anja , Wang Q. J. , Duncan Ruth
Published: August 2009

Quantifying and managing diffuse P losses from small catchments or at the farm scale requires detailed knowledge of farming practices and their interaction with catchment processes. However, detailed knowledge may not be available and hence modeling is required. This paper demonstrates two approaches to developing tools that assist P losses from New Zealand or Australian dairy farms. The first is largely empirical and separates sources of P within a paddock into soil, fertilizer, dung, and treading impacts (including damage to grazed pasture). This information is combined with expert knowledge of hydrological processes and potential point sources (e.g., stream crossings) to create a deterministic model that can be used to evaluate the most cost and labor efficient method of mitigating P losses. For instance, in one example, 45% of annual P lost was attributed to the application of superphosphate just before a runoff event for which a mitigation strategy could be to use a less water soluble P fertilizer. The second approach uses a combination of interviews, expert knowledge and relationships to develop a Bayesian Network that describes P exports. The knowledge integration process helped stakeholders develop a comprehensive understanding of the problem. The Network, presented in the form of a “cause and effect”, diagram provided a simple, visual representation of current knowledge that could be easily applied to individual circumstances and isolate factors having the greatest influence on P loss. Both approaches demonstrate that modeling P losses and mitigation strategies does not have to cover every process or permutation and that a degree of uncertainty can be handled to create a working model of P losses at a farm or small catchment scale.
Critical Evaluation of the Implementation of Mitigation Options for Phosphorus from Field to Catchment Scales
Authors: Maguire Rory O. , Rubæk Gitte H. , Haggard Brian E. , Foy Bob H.
Published: August 2009

Nutrient regulations have been developed over the past decades to limit anthropogenic inputs of phosphorus (P) to surface waters. All of the regulations were promulgated in response to decreased water quality, which was at least partially associated with agricultural non‐point source pollution. Improvements in water quality can take years, so the impacts of these regulations on water quality can not always be seen. Denmark has had nutrient management regulations aimed at achieving mass balance of P for 20 yr, and although great progress has been made, an average surplus of 11 kg P ha−1 remains. Northern Ireland is also trying to move toward mass balance, but decreases in inorganic P fertilizer use have been undermined by an increase in the use of feed concentrates. In the Chesapeake Bay watershed, which covers several states in the USA, a variety of best management practices are starting to have an effect on P losses from agriculture, but water quality has only improved slightly. Impairment to the supply of drinking water to the City of Tulsa Oklahoma led to a lawsuit that has greatly affected the management of poultry litter in the supplying watershed. This paper discusses the different regulations that have developed in these four regions, evaluates the strategies used to prevent non‐point source pollution of P, reports impacts on water quality, and looks for lessons that can be learned as we move forward.