bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of radiation‐induced grafting reactions. I. Polyethylene–styrene systems
Authors: Yasukawa T. , Takahashi T. , Murakami K. , Araki K. , Sasuga T. , Ohmichi H. 
Published: June 2004

AbstractBy means of bromine labeling and ESR, the grafting reactions of styrene onto preirradiated polyethylene have been investigated. Not all the radicals produced by irradiations participate in grafting reactions all together, but they are rendered active bit by bit by the swelling of crystalline parts of polyethylene. The growing rates for polystyryl graft chains at 20°C decrease from 4 monomer units/active site/sec to one‐fourth the initial value after 100 min. On the contrary, the average lifetimes increase from <103 sec to >2.6 × 103 sec. The number‐average molecular weight of graft chains also increases with reaction times and rises to 3.5 × 105 after 90 min at 20°C.
Poly(galacturonic acid)–bivalent metal complexes
Authors: Jellinek H. H. G. , Chen Pi‐Yao A. 
Published: June 2004

AbstractComplexation or stability constants have been determined for complexes of poly‐(galacturonic acid) with Cu, Cd, Zn, and Ni. The stability of complexation decreases as follows: Cu > Cd > Zn > Ni.
Studies in ring‐opening polymerization. II. Cyclohexane spiro‐5‐1,3,2‐dioxathiolan‐4‐one 2‐oxide
Authors: Blackbourn G. P. , Tighe B. J. 
Published: June 2004

AbstractThe effect of spiro cyclohexane substitution on the polymerizability of the 1,3,2‐dioxathiolan‐4‐one‐2‐oxide ring in various solvents has been examined. The steric hindrance of the cyclohexane ring inhibits the bimolecular chain propagation reaction which involves direct attack by a terminal hydroxyl group on the ring and which has been shown to occur in simpler dioxathiolan systems. The conjoined cyclohexane ring does not, however, markedly affect the “thermal” polymerization which occurs in nonhydroxylic solvents and in which chain propagation is thought to involve a reactive α‐lactone intermediate. The rate‐determining step in the sequence of reaction leading to polymer formation is a ring‐scission process in which sulfur dioxide is evolved and the α‐lactone intermediate formed. The values of the activation energy (25–30 kcal/mole) and frequency factor (1011–1013sec−1) associated with this reaction are, therefore, those which govern the the overall polymerization, since the subsequent steps are sensibly instantaneous. In the presence of adventitious traces of water the resultant polymer, poly(1‐hydroxycyclohexanecarboxylic acid) has one carboxyl and one hydroxyl endgroup per chain. Polymers having M̄n ∼ 15,000 are readily obtained; these are amorphous materials, in contrast to the analogous poly‐β‐ester and dialkyl‐substituted poly‐α‐esters which are crystalline. At temperatures in excess of 120°C a competitive first‐order fragmentation reaction leading to the formation of cyclohexanone, carbon monoxide, and sulfur dioxide was observed. Kinetic studies demonstrated that this reaction, which is characterized by an activation energy of ∼40 kcal/mole is unimportant, in the sense that it does not interfere with polymer formation at temperatures below 100°C.
Synthesis and chemical modification of hyperbranched polyethers with terminal hydroxy groups by the anionic ring‐opening polymerization of 3‐alkyl‐3‐hydroxymethyl oxetanes
Authors: Morita Ayako , Kudo Hiroto , Nishikubo Tadatomi 
Published: June 2004

AbstractThe anionic ring‐opening polymerization of oxetanes containing hydroxyl groups was carried out with potassium tert‐butoxide as an initiator in the presence of 18‐crown‐6‐ether in N‐methylpyrrolidinone at 180 °C; it yielded corresponding multifunctional hyperbranched polymers: poly(3‐ethyl‐3‐hydroxymethyloxetane)s, with number‐average molecular weights of 2200–4100 in 83–95% yields, and poly(3‐methyl‐3‐hydroxymethyloxetane)s, with number‐average molecular weights of 4600–5200 in 70–95% yields. The synthesized poly(3‐ethyl‐3‐hydroxymethyloxetane)s and poly(3‐methyl‐3‐hydroxymethyloxetane)s were hyperbranched polyethers containing an oxetane moiety and many hydroxy groups at the ends. The postpolymerization of poly(3‐ethyl‐3‐hydroxymethyloxetane)s was performed in the presence of potassium tert‐butoxide and 18‐crown‐6‐ether in N‐methylpyrrolidinone at 180 °C; it yielded corresponding polymers with higher molecular weights in good yields. The cationic polymerization of poly(3‐ethyl‐3‐hydroxymethyloxetane) derivatives was carried out with boron trifluoride etherate as an initiator and was followed by alkaline hydrolysis; this yielded a new branched polymer, a poly(hyperbranched polyether), with many pendant hydroxy groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3739–3750, 2004
Active‐layer spatial and temporal variability at European Russian Circumpolar‐Active‐Layer‐Monitoring (CALM) sites
Authors: Mazhitova G. , Malkova (Ananjeva) G. , Chestnykh O. , Zamolodchikov D. 
Published: June 2004

AbstractThree 100 × 100 m grids were established in European Russia in the framework of the Circumpolar‐Active‐Layer‐Monitoring (CALM) project. Records range from 4 to 7 years in length. The grids are in mineral soils with mean annual permafrost temperature from −0.5 to −2.5°C. The sites are known to be sensitive to decadal‐scale climatic changes. The grids differ in mean annual air temperature, but have similar thawing indices (DDT). Two grids with deeper annual thaw, separated by 400 km, reveal remarkable similarity in thaw depths, seasonal dynamics and interannual variability. All grids respond to thermal forcing rather consistently, although thaw increments caused by similar increases in DDT are smaller at the grid with the shallowest annual thaw. Stepwise multiple regression and other statistical analyses identified organic‐layer thickness and some, but not all, topographic features as the variables having explanatory power with respect to thaw‐depth variability. These and other variables examined do not, however, explain all the variability in the thaw depth. The effects of organic‐layer thickness on thaw depth are shown to change during the warm season. Copyright © 2004 John Wiley & Sons, Ltd.
Frost‐boil ecosystems: complex interactions between landforms, soils, vegetation and climate
Authors: Walker Donald A. , Epstein Howard E. , Gould William A. , Kelley Alexia M. , Kade Anja N. , Knudson Julie A. , Krantz William B. , Michaelson Gary , Peterson Rorik A. , Ping Chien‐Lu , Raynolds Martha K. , Romanovsky Vladimir E. , Shur Yuri 
Published: June 2004

AbstractFrost boils in northern Alaska vary from large, 2–3‐m diameter, barren non‐sorted circles to completely vegetated hummocks. Summer warmth increases southwards from the coast. Average thaw‐layer thickness shows the opposite trend. Frost heave shows no trend along the climate gradient but is affected by soil texture. Heave is greatest on frost boils with fine‐grained sediments. Biomass increases from 183 g m−2 at the coast to 813 g m−2 in the Arctic Foothills. An aggrading permafrost table is evident in most of the frost‐boil soil profiles, indicating that, over time, accumulation of plant biomass leads to reduced thaw‐layer thickness. A conceptual model suggests how vegetation affects the morphology of patterned ground forms. In the coldest parts of the High Arctic well‐developed frost boils do not form and there is little vegetation on frost boils or the inter‐boil areas. In the warmest parts of the Low Arctic, vegetation is usually sufficient to stabilize the frost boil soils. Frost boils play an important role in Arctic ecosystems functions, including the flux of trace gases to the atmosphere, flux of water and nutrients to streams, and the recycling of important nutrients to wildlife populations. Copyright © 2004 John Wiley & Sons, Ltd.
Meteorological control on interannual spatial and temporal variations in snow cover and ground thawing in two northeast Greenlandic Circumpolar‐Active‐Layer‐Monitoring (CALM) sites
Authors: Christiansen Hanne H. 
Published: June 2004

AbstractData on snow cover depletion and ground thawing at two sites at Zackenberg, in high arctic northeast Greenland, are presented from 1996 to 2002. Operation of the two Zackenberg Ecological Research Operations (ZERO) Circumpolar‐Active‐Layer‐Monitoring (ZEROCALM) sites is part of ZERO. Year‐round meteorological data from Zackenberg are also available from ZERO. The ZEROCALM1 site is located on flat ground, whereas ZEROCALM2 is a southward‐sloping site that includes a seasonal snowpatch, 750 m from ZEROCALM1. Average active‐layer thickness in the Zackenberg lowland is relatively consistent at 60 to 71 cm in flat parts of the landscape, but varies from 44 to 61 cm in snowpatch areas. The seasonal snow depletion and ground thaw in the two topographically different ZEROCALM sites are presented and their meteorological control discussed. Interannual variations in ground thawing are much larger at the ZEROCALM2 site compared to ZEROCALM1. Thawing at the ZEROCALM2 site was affected to a large degree by mid‐ to late‐winter wind conditions, while thaw at the ZEROCALM1 site was correlated with summer air temperature. Copyright © 2004 John Wiley & Sons, Ltd.
Stream ecosystem response to multiple experimental floods from a reservoir
Authors: Robinson Christopher T. , Uehlinger Urs , Monaghan Michael T. 
Published: June 2004

AbstractThe effects of multiple experimental floods in the same year on the ecology of a river (River Spöl) below a large reservoir were investigated. In the flood year (2000), three floods of different magnitude (10 m3/s on 15 June, 25 m3/s on 5 July, and 10 m3/s on 10 August) were implemented, each lasting 7–8 h. Regulated baseflow discharge was maintained at less than 2.5 m3/s. Samples of macroinvertebrates, periphyton, water chemistry, and seston were collected for one year (1999) before and then immediately before and after each flood in the Spöl and in an adjacent reference tributary (Val da l'Aqua). Samples also were collected periodically between floods to evaluate temporal response patterns. During two of the floods, suspended sediments and seston were measured at 30 min to 1 h intervals. Suspended sediment and seston reached peak concentrations within the first hour of each flood, then decreased within about 2 h. Peak seston and suspended sediment concentrations during each flood decreased by an order of magnitude from the July flood to the August flood. Two‐way ANOVA indicated significant flood effects on periphyton standing crops expressed as either chlorophyll a or ash‐free dry mass (AFDM). Recovery of periphyton following each flood appeared to be progressively slower after the later (July and August) floods. Seston chlorophyll levels also were lower following each flood, being significantly correlated to periphyton biomass. Two‐way ANOVA indicated that the floods significantly decreased macroinvertebrate taxonomic richness, density, and biomass. Taxa that decreased from the floods included the turbellarian Crenobia alpina and the gammarid Gammarus fossarum. Taxa that showed a fast recovery to the floods included the Chironomidae, Simuliidae, and Baetidae. Our data indicate a strong temporal effect of flood disturbance on benthic assemblages (periphyton and macroinvertebrates) below reservoirs that partly reflects species‐specific life histories and traits, and the cumulative effects of earlier floods. Copyright © 2004 John Wiley & Sons, Ltd.
Modelling effects of discharge on habitat quality and dispersal of juvenile humpback chub (Gila cypha) in the Colorado River, Grand Canyon
Authors: Korman Josh , Wiele Stephen M. , Torizzo Margaret 
Published: June 2004

AbstractA two‐dimensional hydrodynamic model was applied to seven study reaches in the Colorado River within Grand Canyon to examine how operation of Glen Canyon Dam has affected availability of suitable shoreline habitat and dispersal of juvenile humpback chub (Gila cypha). Suitable shoreline habitat typically declined with increasing discharges above 226–425 m3/ s, although the response varied among modelled reaches and was strongly dependent on local morphology. The area of suitable shoreline habitat over cover types that are preferred by juvenile humpback chub, however, stayed constant, and in some reaches, actually increased with discharge. In general, changes in discharge caused by impoundment tended to decrease availability of suitable shoreline habitat from September to February, but increased habitat availability in spring (May–June). Hourly variation in discharge from Glen Canyon Dam substantially reduced the amount of persistent shoreline habitat at all reaches. Changes in suitable shoreline habitat with discharge were shown to potentially bias historical catch per unit effort indices of native fish abundance up to fourfold. Physical retention of randomly placed particles simulating the movement of juvenile humpback chub in the study reaches tended to decline with increasing discharge, but the pattern varied considerably due to differences in the local morphology among reaches and the type of swimming behaviour modelled. Implications of these results to current hypotheses about the effects of Glen Canyon Dam on juvenile humpback chub survival in the mainstem Colorado River are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Challenging the assumption of habitat limitation: an example from centrarchid fishes over an intermediate spatial scale
Authors: Gutreuter Steve 
Published: June 2004

AbstractHabitat rehabilitation efforts are predicated on the frequently untested assumption that habitat is limiting to populations. These efforts are typically costly and will be ineffective if habitat is not limiting. Therefore it is important to assess, rather than assume, habitat limitation wherever habitat rehabilitation projects are considered. Catch‐count data from a standardized probability‐based stratified‐random monitoring programme were examined for indirect evidence of backwater habitat limitation by centrarchid fishes in the Upper Mississippi River System. The monitoring design enabled fitting statistical models of the association between mean catch at the spatial scale of tens of river kilometres and the percentage of contiguous aquatic area in backwater at least 1 m deep by maximizing a stratum‐area weighted negative binomial log‐likelihood function. Statistical models containing effects for backwater limitation failed to account for substantial variation in the data. However, 95% confidence intervals on the backwater parameter estimates excluded zero, indicating that population abundance may be limited by backwater prevalence where backwaters are extremely scarce. The combined results indicate, at most, a weak signal of backwater limitation where backwaters are extremely scarce in the lower reaches, but not elsewhere in the Upper Mississippi River System. This suggests that habitat restoration projects designed to increase the area of backwaters suitable for winter survival of centrarchids are unlikely to produce measurable benefits over intermediate spatial scales in much of the Upper Mississippi River System, and indicates the importance of correct identification of limiting processes. Published in 2004 by John Wiley & Sons, Ltd.
Foramen ovale changes in growth‐restricted fetuses
Authors: Kiserud T. , Chedid G. , Rasmussen S. 
Published: June 2004

AbstractObjectiveIn animal experiments hypoxemia induces an increased shunting through the fetal foramen ovale (FO). Based on the hypothesis that the FO is expanded to permit more flow, the aim of this study was to determine the size of the FO in growth‐restricted human fetuses.MethodsThirty‐one women with singleton pregnancies complicated with growth‐restriction (< 5th percentile) were examined at 24–39 weeks of gestation. The diameter between the FO valve and the atrial septum was determined during maximum excursion in a horizontal transverse section of the fetal heart, and the transverse diameter of the right atrium (RA) was noted. The pulsatility index (PI) was determined in the umbilical artery (UA) and absent or reversed end‐diastolic flow velocity was noted. The measurements were compared with a reference population using Z‐scores.ResultsIn comparison with normally grown fetuses, the growth‐restricted fetuses had a normal RA size (P = 0.08) but a smaller FO (P = 0.002), particularly when expressed as a relative size by the ratio FO/RA (P < 0.0001). This effect on the FO and FO/RA was seen mainly at < 32 weeks of gestation (P = 0.003 and P < 0.0001, respectively), and was not significant later in pregnancy. There was a tendency towards a negative relationship between relative size of the FO (FO/RA) and progressive placental compromise (overall P < 0.0001).ConclusionsGrowth‐restricted fetuses maintain a normally grown heart (expressed by the RA diameter) but a reduced FO diameter. The effect is seen before 32 weeks and tends to be more marked in fetuses with pronounced hemodynamic compromise of the placenta. This supports the theory that FO shunting is impaired in severely premature fetuses with placental compromise. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
A CASE OF HÆMOCHROMATOSIS.—THE RELATION OF HÆMOCHROMATOSIS TO BRONZED DIABETES
Authors: Opie Eugene L. 
Published: June 2004

(1) There exists a distinct morbid entity, hæmochromatosis, characterized by the widespread deposition of an iron-containing pigment in certain cells and an associated formation of iron-free pigments in a variety of localities in which pigment is found in moderate amount under physiological conditions.
(2) With the pigment accumulation there is degeneration and death of the containing cells and consequent interstitial inflammation, notably of the liver and pancreas, which become the seat of inflammatory changes accompanied by hypertrophy of the organ.
(3) When chronic interstitial pancreatitis has reached a certain grade of intensity diabetes ensues and is the terminal event in the disease.
CULTURES FROM THE BLOOD In SEPTICÆMIA, PNEUMONIA, MENINGITIS AND CHRONIC DISEASES
Authors: White Franklin Warren 
Published: June 2004

Our conclusions from the literature and our own experiments may be summarized as follows:
I. Blood for bacteriological examination during life should be taken directly from the veins and in considerable quantity.
II. Resorption of toxines is the most important feature in cases of sepsis; pyogenie bacteria invade the general circulation in a rather small proportion even of severe eases, and, as a rule, late in the course of the disease.
III. A general infection by the pnenmococcus can be demonstrated occasionally in the late stages of acute lobar pneumonia.
IV. The value of blood cultures as a means of diagnosis in obscure cases of sepsis is limited by the fact that invasion of the blood by the specific organism cannot be demonstrated during life in the majority of cases. Positive cultures are very valuable; negative cultures do not exclude local septic infections.
V. The detection of specific bacteria in the blood of cases of sepsis and of pneumonia gives a very unfavorable prognosis in most cases.
VI. General terminal infections with pyogenic cocci occasionally occur as an immediate cause of death in chronic disease. Local infections processes play this part more frequently.
VII. As far as our experiments have shown, invasion of the blood by bacteria during the death agony, with subsequent distribution of the genus to the organs by the circulation, is a rather uncommon occurrence.
VIII. Owing to the relative infrequency of agonal invasion, we believe that in the majority of cases where the autopsy is performed promptly after death, the bacteria which are found in the organs succeeded in reaching these organs previously to the death agony, and are associated with the course of the disease.
IX. The presence of bacteria in the organs of late autopsies is due in many cases to post-mortem extension from one organ to another, and in some cases to the post-mortem growth of small numbers of genus which were distributed to the organs by means of the circulation.
SEROLOGICAL RELATIONSHIPS OF TYPE-SPECIFIC AND DEGRADED PNEUMOCOCCI
Authors: Reimann Hobart A. 
Published: June 2004

1. Immune sera prepared with the degraded or variant forms of pneumococci (R strains) are similar in their reactions to sera prepared with the protein or cell solutions of pneumococci. They contain antibodies reactive with the protein of all types of pneumococci, but no antibodies reactive with the type-specific substances.
2. Pneumococci of the variant or R form, regardless of type derivation, are serologically identical and have the antigenic characteristics of pneumococcus protein. They evoke the species-specific and not the type-specific antibodies.
3. Antipneumococcus sera obtained by immunization with S strains may contain species-specific antibodies in addition to those which are type-specific. Each kind of antibody can be removed separately from these sera by selective absorption with the R or S strains of pneumococci.
A STUDY OF HEMOLYTIC STREPTOCOCCI IN ACUTE RHEUMATIC FEVER, WITH AN ANALYSIS OF THE ANTIGENIC RELATIONSHIPS EXISTING AMONG CERTAIN STRAINS
Authors: Andrewes Christopher H. , Derick Clifford L. , Swift Homer F. 
Published: June 2004

1. Thirteen strains of hemolytic streptococci isolated from patients with acute rheumatic fever did not show any evidence of being related serologically.
2. Strains of hemolytic streptococci exist which, although identical by the agglutination test, do not show complete reciprocal agglutinin absorption. Sera prepared from such related strains may show some protective power in mice against another member of the group.
3. Some strains of hemolytic streptococci may absorb agglutinins from a serum prepared against another strain, and yet may fail to be agglutinated by that serum.
4. None of 20 strains of hemolytic streptococci isolated in New York City in 1924, and 1925, corresponded serologically with Dochez, Avery, and Lancefield's 4 type strains or with Gordon's Type I strain.
THE PRODUCTION OF ALBUMINURIA BY RENAL VASOCONSTRICTION IN ANIMALS AND IN MAN
Authors: Starr Isaac 
Published: June 2004

Experiments are described which show that:
1. Transient albuminuria follows the infusion of small doses of adrenalin into rabbits, if prolonged over several minutes.
2. Agents causing renal vasoconstriction also cause transient albuminuria in anesthetized, eviscerated dogs.
3. Cats eliminate albumin after having been frightened or enraged.
4. The drug ephedrine, which commonly causes renal vasoconstriction in animals, has been tested in man. Transient albuminuria
CONCERNING THE STABILITY OF THE ACID-BASE EQUILIBRIUM OF THE BLOOD IN PREGNANT ANIMALS
Authors: MacNider William deB. 
Published: June 2004

1. The acid-base equilibrium of the blood as indicated by determinations of the reserve alkali of the blood remains constant in non-pregnant animals at different age periods. This statement does not imply that the acid-base balance of such animals at different age periods is a stable balance.
2. In pregnant animals of the same age periods as the control animals there may develop an instability of this equilibrium which is either associated with the occurrence of a renal injury and which may be looked upon as a retention phenomenon, or arises independently of such an injury. In this latter group of animals the disturbance in the equilibrium increases in frequency and is earlier in its appearance in the gestation period as the age of the organism increases.
3. In old and in senile pregnant animals some physiological mechanism other than that of the kidney becomes unable to stabilize the acid-base equilibrium of the blood with the result that as the pregnancy advances this physiological state of the organism (gestation) becomes pathological.