bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and Properties of Crystalline Polymers
Authors: Oppenlander George C. 
Published: October 2006

Through control of the crystallization process many polymers can be made to exhibit a broad spectrum of structural possibilities, ranging from a state of high disorder to one of high order. Emphasis has been placed on bulk-crystallized polymers which normally fall near the center of this spectrum. This was done in part because polymers are most commonly fabricated in this manner, and also because the amount of attention given in recent years to crystals grown from dilute solution has tended to obscure important aspects of the structure of bulk-crystallized polymers. Differences in the structure of the interlamellar regions account most reasonably for many of the variations in mechanical properties that crystalline polymers can be made to display.
The interlamellar amorphous model, proposed here as a structural model for bulk-crystallized polymers, largely neglects the lamellae themselves, because so little is known about the structure of the lamellae of bulk-crystallized polymers and how variations in lamellar structure can affect properties. This model is intended, therefore, as both a working hypothesis to aid further investigation and as an outline to be filled in as more is learned about the supramolecular structure of crystalline polymers.
Gene Flow and Population Differentiation
Authors: Endler John A. 
Published: October 2006

There are many possible spatial patterns of selection and gene flow that can produce a given cline structure; the actual geography of natural selection and gene flow must be worked out before an attempt is made to explain a given natural cline in terms of a model.
The results of experimental and theoretical models show that it is possible for local differentiation to evolve parapatrically in spite of considerable gene flow if the selection gradients are relatively uniform. Irregularities in environmental gradients increase the sensitivity of clines to the effects of gene flow in proportion to the increase in the differences in gene frequencies between the emigrants and the demes receiving the immigrants. It is not necessary for a sharp spatial environmental change to be present for distinct differentiation to occur. In some cases even a gentle environmental gradient can give rise to marked spatial differentiation along a genetically continuous series of demes; such environmental differences may be below the practical limits of resolution in field studies. Any asymmetry in gene flow does not lead to dedifferentiation if the environmental gradient is smooth; it merely shifts the position of the transition zone between the differentiated areas from that which would be expected if there were no asymmetry. Abrupt geographic differences in gene, genotype, or morph frequencies should not, therefore, be interpreted as evidence for environmental changes in the immediate vicinity of the steepest part of the cline; neither should they be interpreted as evidence for geographic barriers, sharp environmental differences, or sexual isolation among the differentiated groups of populations when there are no other sources of evidence for these phenomena. Gene flow may be unimportant in the differentiation of populations along environmental gradients.
The Keller Plan in Science Teaching
Authors: Kulik James A. , Carmichael Kevin , Kulik Chen-Lin 
Published: October 2006

A review of evaluative research on the Keller plan establishes the following points:
1) The Keller plan is an attractive teaching method to most students. In every published report, students rate the Keller plan much more favorably than teaching by lecture.
2) Self-pacing and interaction with tutors seem to be the features of the Keller courses most favored by students.
3) Several investigators report higher-than-average withdrawal rates for their Keller sections. The conditions that influence withdrawal and procrastination in Keller courses have been studied, and it seems possible to control procrastination and withdrawal through course design.
4) Content learning (as measured by final examinations) is adequate in Keller courses. In the published studies, final examination performance in Keller sections always equals, and usually exceeds, performance in lecture sessions.
5) Students almost invariably report that they learn more in PSI than in lecture courses, and also nearly always report putting more time and effort into the Keller courses.
Coal and the Present Energy Situation
Authors: Osborn Elburt F. 
Published: October 2006

To summarize, we must make greater use of coal, an energy resource that the nation has in great abundance, if we are to approach our former position of self-sufficiency in energy production.
The first step is to move immediately to replace the oil and gas used in electric generating plants with coal and to require that coal be used in fossil fuel electric plants planned or under construction in the next few years. The technology to remove sulfur and particulates from the stack gases is at hand, and therefore environmental regulations can be met.
Producing and transporting the required increased tonnages of coal are problems that can be met with appropriate incentives to the coal and transportation industries. Improved mining technology would be helpful but is not a requirement.
Oil and gas from coal should be in significant commercial production in about a decade. Underground, or in situ, gasification of coal, now in field tests, looks promising as a practical process for recovering the energy from coal, especially in deep or thick beds that cannot be mined efficiently.
Recoverable methane occurs in coal beds in the United States in an amount approximately equal to the total reserves of natural gas—about 260 trillion cubic feet. This large reserve of natural gas should be exploited as quickly as possible. Only minor investments in exploration and modest advances in technology are required.
Finally, as coal production is expanded. adequate planning and the most modern technology should be used to ensure that coal is extracted with maximum recovery and with minimum damage to the environment.
Abortion, Illegitimacy, and the American Birth Rate
Authors: Sklar June , Berkov Beth 
Published: October 2006

In sum, it appears that legal abortion depressed overall fertility, but particularly illegitimate fertility, by giving women an opportunity to terminate their pregnancies when other means of birth control either had not been used or had failed. If legalized abortion had not been available, an estimated additional 39,000 illegitimate babies and 28,000 legitimate babies would have been born in 1971 in the United States. While this makes up a small part of total births (3,500,000), the illegitimate births prevented represent almost one-tenth of all out-of-wedlock children born in the country in that year. In addition to preventing these births the legalization of abortion appears to have reduced the incidence of pregnancy-related marriages and thereby may have helped to limit subsequent marital disruption. Finally, legal abortion prevented large numbers of illegal abortions from occurring. Our data indicate that well over half—most likely between two-thirds and three-fourths—of all legal abortions in the United States in 1971 were replacements for illegal abortions.
Further declines in illegitimate birth rates for the country as a whole will depend, in considerable part, on the extent to which legal abortion becomes more readily available and more widely used. Theoretically, greater use of efficient contraception could also cause illegitimate fertility to decline. But there are many reasons why women do not use efficient contraception even when they know about it and have access to the materials. Even though the use of abortion throughout the nation is now legalized by the Supreme Court decision, this does not necessarily mean that services will in fact be everywhere more readily available. Our interstate analysis suggests that should the liberalization of abortion laws be reversed, not only would there be an upturn in illegal abortions and pregnancy-related marriages, but also a marked rise in illegitimacy, particularly among women who do not have the means to obtain an illegal abortion.
Biosynthesis and Function of Gangliosides
Authors: Fishman Peter H. , Brady Roscoe O. 
Published: October 2006

Gangliosides are unique acidic glycolipids that are selectively concentrated in the plasma membrane of cells. Surface labeling studies have demonstrated that at least a portion of the oligosaccharide chain of gangliosides extends beyond the hydrophobic region of the cell membrane, whereas the lipid moiety of gangliosides (ceramide) is imbedded in the membrane bilayer. It is becoming increasingly apparent that gangliosides participate in the internalization of environmental signals elicited by cholera toxin and glycoprotein hormones such as thyrotropic hormone and chorionic gonadotropin as well as other substances such as interferon and possibly serotonin. The mechanism by which cholera toxin binds to a specific ganglioside receptor on the cell surface and subsequently activates adenylate cyclase provides a model for the interaction of trophic agents with gangliosides. We would predict that analogous phenomena involving gangliosides will be discovered in brain.
The biosynthesis of gangliosides proceeds by the ordered sequential addition of sugars to the lipid moiety. These reactions are catalyzed by a cluster of membrane-bound glycosyltransferases. Any alteration in the activity or specificity of one of these enzymes will result in a dramatic change in the ganglioside pattern of an afflicted cell or organ. The drastic consequences that accompany abnormalities of ganglioside synthesis have been documented in a heritable metabolic disorder in vivo and in tumorigenic transformation of cells in vitro. In this article, we have attempted to unify these observations and to provide a reasonable interpretation of the role of gangliosides in mediating cell surface phenomena.
Marijuana and Driving in Real-Life Situations
Authors: Klonoff Harry 
Published: October 2006

It is evident that the smoking of marijuana by human subjects does have a detrimental effect on their driving skills and performance in a restricted driving area, and that this effect is even greater under normal conditions of driving on city streets. The effect of marijuana on driving is not uniform for all subjects, however, but is in fact bidirectional; whether or not a significant decline occurs in driving ability is dependent both on the subject's capacity to compensate and on the dose of marijuana. For those subjects who improved their performance, the explanation may lie in overcompensation and possibly the sedative effect of the drug.
Whereas the street portion of this study approximated normal driving conditions, it should be emphasized that the context of the driving experience even on city streets was experimental. The design of this study provided maximal safeguards in terms of a dual control vehicle and a driver observer; in addition, the subjects were professionally screened and, with rare exception, they were emotionally stable. Given the experimental setting and set, the safeguards, and the nature of the study sample, idiosyncratic behavior that might occur under normal driving conditions would be less likely to occur in a study such as this.
Other identified factors might lead to more stringent conclusions regarding the effects of marijuana on driving. The first is night driving, which may be more stressful. But an even more important unanswered question is the cumulative effect of alcohol and marijuana on driving (64 percent of the study sample reported using alcohol in combination with marijuana before driving). Third, the doses of marijuana used in this study were within the range of social marijuana usage; more heroic doses might be taken before driving. Fourth, the effect of marijuana on reactions and decisions during high speed is still another unknown.
What are the recommendations that emerge from this study? Driving under the influence of marijuana should be avoided as much as should driving under the influence of alcohol. More investigation is urgently required—and high priority should be given to studies that approximate normal conditions of driving and in which alcohol and marijuana are administered to the same subjects.
Potential for Converting Wood into Plastics
Authors: Goldstein Irving S. 
Published: October 2006

The conversion of wood into chemicals for the production of most of our synthetic plastics, fibers, and rubbers is technically feasible. With refinements in technology a large integrated plant utilizing all components of the wood for production of ethanol (to be further processed to ethylene and butadiene), phenols and furfural would be approaching economic feasibility as well at current petrochemical prices. If crude oil prices continue to climb at a faster rate than wood costs, the economic feasibility of chemicals for polymers from wood would become certain.
Although technical feasibility has not been established, synthetic oils from liquefaction of wood might serve as feedstocks for cracking to chemicals in the same way that crude oil is presently used.
The fulfillment of all our polymer needs from wood as a raw material should not place an impossible burden on our wood supply, but might actually improve the availability of wood for lumber, plywood and pulp by providing a use for less valuable wood which would allow reforestation and improved forest management.
Solar Structure and Terrestrial Weather
Authors: Wilcox John M. 
Published: October 2006

If there is indeed an effect of the variable sun on the weather, the physical cause for it remains quite elusive. We should keep in mind the possibility that there may be several causes and several effects. The situation may change through the 11-year sunspot cycle and the 22-year solar magnetic cycle, as well as on longer time scales.
Work is proceeding at a lively pace at the institutions mentioned in this article and at many others around the world. The Soviet Union has long had considerably more workers interested in this field than has any other country. A bilateral agreement between the Soviet Union and the United States has considerably increased the interactions between workers interested in this subject, including an exchange of extended visits between the two countries.
A detailed knowledge of solar causes of geomagnetic activity is only now beginning to emerge after many years of scientific efforts. This suggests that a possible successful solution to the sun-weather problem will require a similar magnitude of effort. We look forward with interest and optimism to the results of the next few years.
An Oxygen Key to the New Superconductors
Authors: Robinson Arthur L. 
Published: October 2006

First it was the physicists, then the chemists, and most recently the materials scientists and ceramists who have hastily included in their annual meetings symposia on the new high-temperature, ceramic superconductors. Below are briefings from the 1987 Spring Meeting of the Materials Research Society (MRS) that was held in Anaheim, California, from 21 to 24 April, 1 week before the American Ceramics Society's conclave in Pittsburgh.
With the initial wave of euphoria now past, the atmosphere in Anaheim was decidedly more professional than that of the now fabled ""Woodstock of Physics"" that was part of the American Physical Society's March Meeting in New York City only 5 weeks before. Nonetheless, perhaps 1500 materials researchers listened to 69 scheduled papers and several late walk-ons that were crammed into a 2-day symposium. With a martial strictness, cochairs Michael Schlüter of AT&T Bell Laboratories and Donald Gubser of the Naval Research Laboratory kept the talks to the allotted 10 minutes each.
Except for an impassioned presentation by Juei-Teng Chen of Wayne State University, who sought to convince listeners that a group there had seen dear signs of superconductivity at 240 K, which is ambient temperature during a cold night on the northern plains, no significant indications of room-temperature superconductivity were reported. The most skeptical view was that of Theodore Geballe of Stanford University, who suggested that some of the unreproducible signs seen in several laboratories could be due to something other than superconductivity, as similar effects disappeared in Stanford samples with repeated cycling between room and liquid-nitrogen temperature.
If there was one theme at the symposium, it was that oxygen is the key to the family of rare-earth-based ceramic materials now in hand that remain superconducting up to about 100 K.
The Production of Pure Absolute Alcohol with Calcium Carbide and Anhydrous Copper Sulphate
Authors: Lyons R. E. , Smith L. T. 
Published: October 2006

(1) The above is recommended as an economical, convenient and quick method for producing absolute alcohol on a laboratory scale.
If the distillation is executed with free flame, excessive or careless heating must be avoided near the end of the operation because of the copper acetylide in the residue.
(2) Calcium carbide is recommended over potassium permanganate or anhydrous copper sulphate as a qualitative reagent in detecting traces of water in alcohol.
Isolation and Properties of Chicken Erythrocyte Nuclei
Authors: Dounce Alexander L. , Lan Tien Ho 
Published: October 2006

(1) A method has been described for the isolation of chicken erythrocyte nuclei using saponin to lake the cells. Nuclei prepared by this method have been compared with nuclei prepared by the method of Laskowski and with nuclei prepared by a citric acid method, particularly in regard to respiration.
(2) The total lipid content of the nuclei is about 14 per cent. and the desoxyribonucleic acid content is about 45 per cent.
(3) A yellow pigment contained in the nuclei appears to be xanthophyll.
(4) A gel formed by the nuclei at pH 8.5 in the presence of ammonia and the absence of other cations is described.
Schwa Elision in Fast Speech: Segmental Deletion or Gestural Overlap?
Authors: Davidson Lisa 
Published: October 2006

AbstractPretonic schwa elision in fast speech (e.g. potato -› [pt]ato, demolish -›[dm]olish) has been studied by both phonologists and phoneticians to understandhow extralinguistic factors affect surface forms. Yet, both types of studies havemajor shortcomings. Phonological analyses attributing schwa elision to acrossthe-board segmental deletion have been based on researchers’ intuitions. Phoneticaccounts proposing that elision is best characterized as gestural overlap havebeen restricted to very few sequence types. In this study, 28 different [#CəC-]sequences are examined to define appropriate acoustic criteria for ‘elision’, toestablish whether elision is a deletion process or the endpoint of a continuum ofincreasing overlap, and to discover whether elision rates vary for individualspeakers. Results suggest that the acoustic patterns for elision are consistent withan overlap account. Individual speakers differ as to whether they increase elision
Effects of membrane and soluble EPCR on the hemostatic balance and endotoxemia in mice
Authors: Zheng Xunzhen , Li Weihong , Gu Jian-Ming , Qu Dongfeng , Ferrell Gary L. , Esmon Naomi L. , Esmon Charles T. 
Published: October 2006

Abstract
Recent studies have shown that endothelial protein C receptor (EPCR) polymorphisms and soluble EPCR levels are associated with thrombotic diseases. It is unknown whether membrane EPCR (mEPCR) heterozygosity and/or physiologically elevated sEPCR levels directly impact the hemostatic balance and the outcome of endotoxemia. In these studies, thrombin infusion experiments revealed that EPCR heterozygosity (Procr+/−) impaired protein C activation by approximately 30%. Infusion of factor Xa with phospholipid demonstrated that the Procr+/−genotype increased the coagulant response relative to wild-type mice. Challenge of the Procr+/− mice with lipopolysaccharide (LPS) did not significantly exaggerate their response compared with wild-type mice. We also generated mice in which one allele of full-length EPCR was replaced by sEPCR (Procrs/+). Compared with Procr+/− mice, Procrs/+ mice had 5-fold higher sEPCR and similar mEPCR levels. Procr+/− and Procrs/+ mice generated similar levels of activated protein C (APC) upon thrombin infusion. They also exhibited a similar coagulant response upon factor Xa/phospholipid infusion. Only supraphysiologic levels of sEPCR could influence protein C activation and exaggerate the coagulant response. In conclusion, mEPCR, but not physiologically elevated sEPCR, regulated protein C activation. Procr heterozygosity results in a mild increase of thrombosis tendency and little influence on the response to endotoxin.
Establishment of endolithic populations of extremophilic Cyanidiales (Rhodophyta)
Authors: Yoon Hwan Su , Ciniglia Claudia , Wu Min , Comeron Josep M , Pinto Gabriele , Pollio Antonino , Bhattacharya Debashish 
Published: October 2006

Abstract

Background
Cyanidiales are unicellular extremophilic red algae that inhabit acidic and high temperature sites around hot springs and have also adapted to life in endolithic and interlithic habitats. Comparative genomic analysis of Cyanidioschyzon merolae and Galdieria sulphuraria predicts that the latter may be more broadly distributed in extreme environments because its genome contains membrane transporters involved in the uptake of reduced carbon compounds that are absent from C. merolae. Analysis of an endolithic site in the Phlegrean Fields near Naples, Italy is consistent with this prediction showing this population to be comprised solely of the newly described lineage Galdieria-B and C. merolae to be limited to humid habitats. Here, we conducted an environmental PCR survey of another extreme environment in Tuscany, Italy and contrasted Cyanidiales population structure at endolithic and interlithic habitats in Naples and Tuscany.

Results
We find a second Galdieria lineage (Galdieria-A) in endolithic and interlithic habitats in Tuscany but surprisingly Cyanidium was also present at these sites. The photoautotrophic Cyanidium apparently survives below the rock surface where sufficient light is available for photosynthesis. C. merolae is absent from all endolithic and interlithic sites in Tuscany. Population genetic analyses of a partial calmodulin gene fragment suggest a recent establishment or recurrent gene flow between populations in Tuscany, whereas the highly structured Galdieria-B population in Naples likely originated from 2–3 founder events. We find evidence of several recombination events across the calmodulin gene, potentially indicating the presence of sexual reproduction in the Tuscany populations.

Conclusion
Our study provides important data regarding population structure in extreme endolithic environments and insights into how Cyanidiales may be established in and adapt to these hostile environments.