cssi/SciSciGPT-SciSciNet huggingface dataset:
Large scale chromosome structure and organization

Abstract New evidence has supported a growing consensus that the chromatin of mitotic chromosomes is organized into loop domains through interactions with non-histone proteins. The most abundant non-histone protein, DNA topoisomerase II, is required for chromosome condensation. In contrast, several other putative structural components in the chromosome scaffold fraction have been shown not to be chromosomal after all.
Fast, accurate evaluation of exact exchange: The occ-RI-K algorithm

Construction of the exact exchange matrix, K, is typically the rate-determining step in hybrid density functional theory, and therefore, new approaches with increased efficiency are highly desirable. We present a framework with potential for greatly improved efficiency by computing a compressed exchange matrix that yields the exact exchange energy, gradient, and direct inversion of the iterative subspace (DIIS) error vector. The compressed exchange matrix is constructed with one index in the compact molecular orbital basis and the other index in the full atomic orbital basis. To illustrate the advantages, we present a practical algorithm that uses this framework in conjunction with the resolution of the identity (RI) approximation. We demonstrate that convergence using this method, referred to hereafter as occupied orbital RI-K (occ-RI-K), in combination with the DIIS algorithm is well-behaved, that the accuracy of computed energetics is excellent (identical to conventional RI-K), and that significant speedups can be obtained over existing integral-direct and RI-K methods. For a 4400 basis function C68H22 hydrogen-terminated graphene fragment, our algorithm yields a 14 × speedup over the conventional algorithm and a speedup of 3.3 × over RI-K.
Cultural Relativism, Anthropology of

This article discusses views toward cultural relativism in the history of anthropology, from Franz Boas to the present. It shows the grounding of versions of relativism in the anthropological field experience of cultural diversity, and identifies the tensions between anthropology and more foundationalist philosophies. Yet it notes the openings toward more perspectival views in philosophy as well, and distinguishes between kinds of relativism in anthropological thought and practice. Debates argued over foundationalism and relativism too often draw on stereotyped depictions of the alternatives.
Keeping Off the Weight with DCs.

Long studied as modulators of insulin sensitivity, adipose tissue immune cells have recently been implicated in regulating fat mass and weight gain. In this issue of Immunity , Reisner and colleagues (2015) report that ablation of perforin-expressing dendritic cells induces T cell expansion, worsening autoimmunity and surprisingly increasing adiposity.
Data encoding based on the shape of the ferroelectric domains produced by using a scanning probe microscope tip

Ferroelectric materials are broadly considered for information storage due to the extremely high storage and information processing densities they enable. To date, ferroelectric based data storage has invariably relied on the formation of cylindrical domains, allowing for binary information encoding. Here we demonstrate and explore the potential of high-density encoding based on the domain morphology. We explore the domain morphogenesis during the tip-induced polarization switching by sequences of positive and negative pulses in a lithium niobate single-crystal and demonstrate the principles of information coding by the shape and size of the domains. We applied cross-correlation and neural network approaches for recognition of the switching sequence by the shape of the resulting domains and established optimal parameters for domain shape recognition. These studies both provide insight into the highly non-trivial mechanism of domain switching and potentially establish a new paradigm for multilevel information storage and content retrieval memory devices. Furthermore, this approach opens a pathway to exploration of domain switching mechanisms via shape analysis.
A Cosmological Constant from Gauge Field Instantons

Although all interactions in the Standard Model generate nonzero shifts of the vacuum energy and pressure, gravity does not interact with them. Assuming (i) that the reason why it is so breaks down at some scale $M_g$ and that (ii) the instanton-induced shifts at such scale generate the observed cosmological constant, we found that it then should happen at a (surprisingly small) scale $M_g\sim 10^3 TeV$.
Hybrid simulation testing of a self‐centering rocking steel braced frame system

SUMMARY The self-centering rocking steel frame is a seismic force resisting system in which a gap is allowed to form between a concentrically braced steel frame and the foundation. Downward vertical force applied to the rocking frame by post-tensioning acts to close the uplifting gap and thus produces a restoring force. A key feature of the system is replaceable energy-dissipating devices that act as structural fuses by producing high initial system stiffness and then yielding to dissipate energy from the input loading and protect the remaining portions of the structure from damage. In this research, a series of large-scale hybrid simulation tests were performed to investigate the seismic performance of the self-centering rocking steel frame and in particular, the ability of the controlled rocking system to self-center the entire building. The hybrid simulation experiments were conducted in conjunction with computational modules, one that simulated the destabilizing P-Δ effect and another module that simulated the hysteretic behavior of the rest of the building including simple composite steel/concrete shear beam-to-column connections and partition walls. These tests complement a series of quasi-static cyclic and dynamic shake table tests that have been conducted on this system in prior work. The hybrid simulation tests validated the expected seismic performance as the system was subjected to ground motions in excess of the maximum considered earthquake, produced virtually no residual drift after every ground motion, did not produce inelasticity in the steel frame or post-tensioning, and concentrated the inelasticity in fuse elements that were easily replaced. Copyright © 2014 John Wiley & Sons, Ltd.
Software Validation for Reliability

The sections in this article are 1 Categories of Reliability Measurements and Predictions 2 Definitions 3 Criteria for Safety 4 Risk Assessment 5 Approach to Prediction 6 Predictive Equations 7 Criterion for Optimally Selecting Failure Data 8 Relating Testing to Reliability and Quality 9 Making Safety Decisions 10 Summary of Predictions and Model Validation Keywords: Verification and validation; software reliability measurement and prediction; safety critical software; risk analysis
Exploring the world of ambulatory surgery

Abstract The 5th James H. Nicoll Memorial lecture was delivered at the 5th International Congress on Ambulatory Surgery, Boston, Massachusetts, 2003. A summary of historic events and modern concepts of care for the ambulatory surgical patient is summarized. Current guidelines of the American Society of Anesthesiologists were developed using an evidence-based model. Data, however, are lacking and conclusions based largely on consensus of experts. Morbidity and mortality are low frequency events. Large populations must be studied to identify and correct causative factors. Data from recent studies are noted and critiqued. Office-based surgery is a specific venue of concern.
Equations not preserved by complete extensions

In this paper we construct a representable relation algebra ~ and an equation which holds in ~ but fails in every complete extension of ~ . In particular, the equation fails in every perfect extension [3] and every completion [4] of ~ . We also outline how to carry out the same construction for cylindric algebras. For every finite n >3 there is a representable CAn and an equation which holds in that algebra but fails in every complete extension. This yields a negative answer to Problem 2 . !5 of [2].
Survival of Peas, Peaches, and Prenatal Pigs

Strategies for survival of a species take on many forms. Strange as it may seem, the peach, the pea, and the pig have evolved strategies with several similarities. The peach tree is loaded with blooms. Each twig has a flower every inch or so. Each flower is a potential peach with a seed. Not all flowers are pollinated successfully; thus, gaps appear in the array of little peaches on the twig. Each little peach requires about 10 cm of room on the stem if it hopes to be a full-sized peach. At a very early stage, a very significant portion of the little peaches shrivel and drop off. This is especially true for peaches that are not equally spaced and are very close to each other. The peach tree "knows" it cannot successfully support the number of peaches that originally set on the tree, so some little peaches have to go. Peaches too close to each other will sap nutrients from each other. The number of fully formed peas in a pod are also limited by the number of potential peas successfully fertilized, the length of the pod, and growing conditions. Even under the best of conditions, the number of survivors is reduced. Some peas are also very much smaller than others. This overproduction of potential young with subsequent reduction in numbers also takes place in the pig. Estrus recurs in the pig at 21 -day intervals. The number of eggs ovulated is about 15, with the number originating from each ovary rarely being equal. Eggs are fertilized within a few hours after ovulation. The embryos remain in the oviduct for about 48 hours after fertilization. The uterus is bicornuate, each horn is 150—225 cm long. The horns are joined at the body of the uterus; thus the uterus is one long tube. The embryos are moved from the oviduct to the tip of the uterine horn and then throughout the length of the uterine horns by uterine motility [I]. Embryos can be moved freely from one uterine horn to the other. Thus, if the number of embryos originating in one horn is markedly different from the number in the other horn, there is an opportunity to equalize the numbers in each horn. Movement of embryos is by uterine contractions because the embryos are only a few millimeters in diameter up to
Serial Section Electron Tomography: A Method for Three-Dimensional Reconstruction of Large Structures

We present a method for combining single axis tomography and serial sectioning techniques to derive a three-dimensional reconstruction of large structures at electron microscopic resolution. This serial-tomography method allows the use of sufficiently thin sections to achieve adequate resolution with electron tomography, yet enables the generation of large reconstructions with considerably fewer sections than would be required using a serial thin section reconstruction technique. Serial thick sections (1-2 microns) are cut through the structure of interest, tomographic volume reconstructions are obtained for each section from a single axis tilt series, and the resulting series of volumes are then aligned and combined to form a single large volume. The serial-tomography method is illustrated with several samples, including red blood cells, the Golgi apparatus, and a spiny dendrite of a cortical pyramidal neuron. In some of these samples, the reconstruction is compared to correlated light microscopic views. The resulting large volume reconstructions appear to represent accurately the size and shape of objects such as red blood cells and spiny dendrites. The continuity of complex, tortuous structures such as the Golgi apparatus is also maintained across serial volumes. These examples demonstrate that it is possible to align and link a series of tomographic volumes accurately and that serial-tomography is a useful method for reconstructing relatively large structures without resorting to large numbers of serial thin sections.
Comparison of thermotolerance of sun-exposed peel and shaded peel of ‘Fuji’ apple

Abstract The thermotolerance of the sun-exposed peel and the shaded peel of ‘Fuji’ apple ( Malus domestica Borkh.) fruit was evaluated by measuring pigments, chlorophyll a fluorescence transients and O 2 evolution or uptake after exposure to 25, 35, 40, 42, 44, 46 or 48 °C for 30 min in the dark. A major effect of heat stress at 46–48 °C on the chlorophyll a fluorescence transients was the appearance of a very clear K step at 200–300 μs for both peel types. The K step was slightly more pronounced in the sun-exposed peel than in the shaded peel, suggesting that the resistance of oxygen-evolving complex to heat stress is slightly lower in the sun-exposed peel than in the shaded peel. Minimal fluorescence ( F O ), relative to the value at 25 °C, increased to a greater extent in the shaded peel than in the sun-exposed peel after exposure to 46–48 °C, but the temperature dependencies of F O changes were similar for both peel types. Maximum quantum yield of PSII ( F V / F M ) decreased to a similar extent in the sun-exposed peel and the shaded peel as temperature rose from 25 to 44 °C, but the sun-exposed peel reached slightly lower values at 46–48 °C. Correspondingly, gross O 2 evolution rate, relative to that at 25 °C, was also slightly lower in the sun-exposed peel than in the shaded peel at 46–48 °C. In response to heat stress, the ratio of Q A -reducing reaction centers (RCs) to total RCs and the ratio of Q B -reducing RCs to Q A -reducing RCs decreased, but both of them decreased to lower values in the sun-exposed peel than in the shaded peel at 46–48 °C, indicating that the capacity of electron transfer between P 680 + and Q B via Q A was damaged to a greater extent in the sun-exposed peel than in the shaded peel. At each given temperature, dark respiration was similar between the two peel types. Overall, it appears that the exposure to higher surface temperature under high light does not make the sun-exposed peel more tolerant of heat stress than the shaded peel of apple fruit.
Estrogen Receptor-α Variant, ER-α36, is Involved in Tamoxifen Resistance and Estrogen Hypersensitivity

Antiestrogens such as tamoxifen (TAM) provided a successful treatment for estrogen receptor (ER)-positive breast cancer for the past four decades. However, most breast tumors are eventually resistant to TAM therapy. The molecular mechanisms underlying TAM resistance have not been well established. Recently, we reported that breast cancer patients with tumors expressing high concentrations of ER-α36, a variant of ER-α, benefited less from TAM therapy than those with low concentrations of ER-α36, suggesting that increased ER-α36 concentration is one of the underlying mechanisms of TAM resistance. Here, we investigated the function and underlying mechanism of ER-α36 in TAM resistance. We found that TAM increased ER-α36 concentrations, and TAM-resistant MCF7 cells expressed high concentrations of ER-α36. In addition, MCF7 cells with forced expression of recombinant ER-α36 and H3396 cells expressing high concentrations of endogenous ER-α36 were resistant to TAM. ER-α36 down-regulation in TAM-resistant cells with the short hairpinRNA method restored TAM sensitivity. We also found that TAM acted as a potent agonist by activating phosphorylation of the AKT kinase in ER-α36-expressing cells. Finally, we found that cells with high concentration of ER-α36 protein were hypersensitive to estrogen, activating ERK phosphorylation at picomolar range. Our results thus demonstrated that elevated ER-α36 concentration is one of the mechanisms by which ER-positive breast cancer cells escape TAM therapy and provided a rational to develop novel therapeutic approaches for TAM-resistant patients by targeting ER-α36.
Receptor specific probes for the study of Fcγ receptor specific function

Human leukocytes express three distinct families of receptors for the Fc region of IgG (Fc gamma R). We have prepared erythrocytes (E) coated with monoclonal anti-Fc gamma R antibodies for the study of receptor specific phagocytosis using biotin and streptavidin. In this technique, both the E and the monoclonal antibody (mAb) are biotinylated and coupling of the mAb to the E occurs through the use of streptavidin. The same biotin/streptavidin principle was used to prepare E coated with human IgG. Using this technique, receptor specific probes or probes coated with natural ligand (IgG) can be prepared rapidly with the use of small amounts of mAb or IgG. Finally, we have used these receptor specific probes to demonstrate that all three families of Fc gamma R (Fc gamma RI, Fc gamma RII and Fc gamma RIII) expressed on human monocytes and human macrophages are phagocytic receptors.
The tRNA genes punctuate the reading of genetic information in human mitochondrial DNA

Abstract A detailed transcription map of HeLa cell mitochondrial DNA (mtDNA) has been constructed by using the S1 protection technique to localize precisely the sequences coding for the ribosomal RNA (rRNA) and poly(A)-containing species on the physical map of the DNA. This transcription map has been correlated with the positions of the tRNA genes derived from the mtDNA sequence. It has been shown that, with the exception of the D loop and another small segment near the origin of replication, the mtDNA sequences are completely saturated by the rRNAs, poly(A)-containing RNAs and tRNAS coded for by the two strands. No evidence for intervening sequences has been found. The sequences coding for the individual poly(A)-containing RNA and rRNA species appear to be immediately contiguous on one side, and most frequently on both sides, to tRNA coding sequences. Furthermore, the H strand sequences coding for the two rRNAs, the poly(A)-containing RNAs and the tRNAs appear to be adjacent to each other, extending from coordinate 2100 to coordinate 95100 of the genome relative to the origin taken as 0100. The results are consistent with a model of transcription of the H strand in the form of a single molecule which is processed into mature RNA species by precise endonucleolytic cleavages, occurring in almost all cases immediately before and after a tRNA sequence. The tRNA sequences may play an important role as recognition signals in the processing of the primary transcripts.
The Retention Index of the Community College Survey of Student Engagement (CCSSE): How Meaningful Is It?

Institutional and student level data from the Florida Community Colleges were examined to explore the Retention Index of the Community College Survey of Student Engagement (CCSSE). A simple correlation and regression analysis was conducted to determine if the CCSSE Retention Index could be used to predict the institutional retention rate calculated for the state accountability measure. Student level data were used with a nested ANOVA to examine if there were mean differences in the CCSSE Retention Index scores of males and females of different racial groups when accounting for the potential influence of the institution attended. Mean differences were examined since differences in retention rates of these groups have been documented.
Social Group Work: International and Global Perspectives

This article reviews the literature on international social group work and makes some observations about the current state of the field. The authors used a multipronged search strategy to examine the literature on international social group work. These search strategies yielded approximately 1,000 abstracts and citations that were then reviewed closely for content related to social group work. The search revealed four broad categories of articles, book chapters, and conference presentations: (1) descriptive studies of social group work done in countries outside the United States; (2) surveys of practitioners, educators, or databases about social group work practices; (3) descriptions of the development of social group work models in non-U.S. countries; (4) cross-cultural comparisons of social work group model implementation in two or more specific countries; and (5) the implementation and delivery of group work training and educational models in an international/global context.
Derivation of regression formulae using the minimum cross-entropy principle

Abstract We derive expressions for linear regression directly by minimizing cross-entropy subject to the observational evidence. We also show that in the continuous case the MEP (minimum cross-entropy principle) reproduces relative frequency evidence a posteriori. These calculations support the exclusive use of the MEP for inductive inference.
Cancer of the bladder. Diagnosis and staging

Hematuria and frequency of urination not otherwise explained should suggest that a bladder tumor could be present. Excretory urography may increase one's suspicion. Cystoscopy and, when necessary, biopsy prove that a tumor exists. The stage, or microscopic extent, of the tumor largely governs the outlook when treatment appropriate to that stage is used. The stage consists of 5 histologic categories: non-invasion, invasion of submucosa (lamina propria), superficial muscle, deep muscle (with or without perivesical fat), and prostatic stroma or metastases. In general, cure seems probable in the first 2 stages, possible in the third, improbable in the fourth, and impossible in the fifth. Since the treatment selected depends largely on the stage of the tumor, the stage must be determined beforehand. The clinical assessment lacks the preciseness of the pathologic but becomes more accurate with increasing experience. Under general anesthesia bimanual examination and biopsy of the involved bladder wall will yield the most information.
A Mathematical Theory of Finite–Amplitude Rock–Folding

The problem of the finite-amplitude folding of an isolated, linearly viscous layer under compression and imbedded in a medium of lower viscosity is treated theoretically by using a variational method to derive finite difference equations which are solved on a digital computer. The problem depends on a single physical parameter, the ratio of the fold wavelength, L, to the "dominant wavelength" of the infinitesimal-amplitude treatment, L_d. Therefore, the natural range of physical parameters is covered by the computation of three folds, with L/L_d = 0, 1, and 4.6, up to a maximum dip of 90°. Significant differences in fold shape are found among the three folds; folds with higher L/L_d have sharper crests. Folds with L/L_d = 0 and L/L_d = 1 become fan folds at high amplitude. A description of the shape in terms of a harmonic analysis of inclination as a function of arc length shows this systematic variation with L/L_d and is relatively insensitive to the initial shape of the layer. This method of shape description is proposed as a convenient way of measuring the shape of natural folds. The infinitesimal-amplitude treatment does not predict fold-shape development satisfactorily beyond a limb-dip of 5°. A proposed extension of the treatment continues the wavelength-selection mechanism of the infinitesimal treatment up to a limb-dip of 15°; after this stage the wavelength-selection mechanism no longer operates and fold shape is mainly determined by L/L_d and limb-dip. Strain-rates and finite strains in the medium are calculated f or all stages of the L/L_d = 1 and L/L_d = 4.6 folds. At limb-dips greater than 45° the planes of maximum flattening and maximum flattening rat e show the characteristic orientation and fanning of axial-plane cleavage.
Identification of unique interactions between the flexible linker and the RecA-like domains of DEAD-box helicase Mss116

DEAD-box RNA helicases are ATP-dependent proteins implicated in nearly all aspects of RNA metabolism. The yeast DEAD-box helicase Mss116 is unique in its functions of splicing group I and group II introns and activating mRNA translation, but the structural understanding of why it performs these unique functions remains unclear. Here we used sequence analysis and molecular dynamics simulation to identify residues in the flexible linker specific for yeast Mss116, potentially associated with its unique functions. We first identified residues that are 100% conserved in Mss116 of different species of the Saccharomycetaceae family. The amino acids of these conserved residues were then compared with the amino acids of the corresponding residue positions of other RNA helicases to identify residues that have distinct amino acids from other DEAD-box proteins. Four residues in the flexible linker, i.e. N334, E335, P336 and H339, are conserved and Mss116-specific. Molecular dynamics simulation was conducted for the wild-type Mss116 structure and mutant models to examine mutational effects of the linker on the conformational equilibrium. Relatively short MD simulation runs (within 20 ns) were enough for us to observe mutational effects, suggesting serious structural perturbations by these mutations. The mutation of E335 depletes the interactions between E335 and K95 in domain 1. The interactions between N334/P336 and N496/I497 of domain 2 are also abolished by mutation. Our results suggest that tight interactions between the Mss116-specific flexible linker and the two RecA-like domains may be mechanically required to crimp RNA for the unique RNA processes of yeast Mss116.
Restricted Protein Intake and Avian Atherosclerosis

ALTHOUGH low-protein diets in the presence or absence of supplementary dietary cholesterol give rise to a marked hypercholesterolaemia in Leghorn cocks, nevertheless, we observed1,2 a reduction in the severity of abdominal atherosclerosis after 10 or 20 weeks on the experimental low-protein diets. We have examined the effects of prolonged restrictions (20 months) of protein intake in relation to plasma cholesterol, body composition and abdominal aortic and coronary atherosclerosis.
Cloning and characterization of Paramecium mitochondrial DNA replication initiation regions

Fragments containing the replication-initiation region of mitochondrial (mt) DNA from four species of Paramecium aurelia were ligated to the pBR322 plasmid and used to transform Escherichia coli. The criteria for identifying the desired mitochondrial DNA restriction fragments were based on the palindromic dimer structure of the replicative intermediate of this DNA. The nature of the cloned sequences was verified by hybridization to mitochondrial DNA fragments containing the initiation region, by determining the size of snapback renaturation products, and by determining the symmetry of restriction-endonuclease sites within the clones. Heterologous hybridization experiments showed that one species' initiation region is not homologous to the other three. Cleavage patterns of each of the clones by 18 different restriction enzymes were determined. There are no sites within approx. 250 bp of the center of the insert of any clone although there are numerous cleavages in more distal regions. These sites are generally symmetric about the center of the insert as expected for a palindromic structure. The characteristics of the cloned sequences support a proposed replication model for all four species studied.
1051-1 A Telemedicine Arrhythmia Analysis Tool for Rural Physicians

Introduction Rural health care practitioners are often faced with the task of interpreting complex heart rhythms. Usually these practitioners do not have specialized training in cardiology or ECG interpretation and available commercial systems for interpreting 12-lead ECG have been well-documented to perform rhythm analysis poorly. A computer-based tool is being developed in our laboratory that will provide rural health care practitioners with an automated system for interpreting complex arrhythmias. Methods A prototype system was developed using resources readily available in on the Internet: NCSA Mosaic, a hypermedia document browser; NCSA Collage, an interactive distributed white-board system; and GNU Ghostscript/Ghostview, a PostScript language interpretation system. The prototype was created by modifying and integrating the functionality of the individual systems into a single, easy to use system. The prototype was developed in Con UNIX workstations using the X display protocol and is based on the client-server model. The system may be accessed by any computer on the Internet with X display capability. On the client side, the system assists the user in scanning an ECG, identifying the waves in the scanned ECG, and transmitting the scanned ECG and annotations to the server. On the server side, the system analyzes the annotations using an knowledge-based rhythm analysis system being developed in our laboratory. The system produces a PostScript file containing the interpretation(s) and accompanying ladder diagrams and a case-specific help file containing detailed descriptions and therapeutic indications. These files are transmitted back to the user's computer and displayed to the user by the client-side of the system. The design of the system provides for an “on-line,” interactive consultation with a cardiologist. Results Development of the prototype system required 2.5 man-months of effort to complete. The prototype system is undergoing alpha testing. For the prototype stage, all interpretations of clinical records are overread by a clinical cardiologist prior to transmission to the user. Conclusions This system may be beneficial in increasing the level of care of patients in the rural setting by providing the ECG interpretation expertise of an experienced cardiologist to rural practitioners on demand, which may also lead to decreasing the cost of rural health care. In addition, the system may be modified for applications in other health care domains.
Pentasomy X with multiple dislocations.

We describe a pentasomy X (49,XXXXX) patient whose multiple dislocations led to a consideration of the Larsen syndrome. Review of the 11 reported cases of pentasomy X showed that elbow dislocations are known to occur in this syndrome. Our patient is the first to present hypoplasia of the glenoid process with consequent shoulder dislocation. Clinical and radiologic findings of previously reported cases of pentasomy X are reviewed.
Head-to-Head Prenyl Tranferases: Anti-Infective Drug Targets.

We report X-ray crystallographic structures of three inhibitors bound to dehydrosqualene synthase from Staphylococcus aureus: 1 (BPH-651), 2 (WC-9), and 3 (SQ-109). Compound 2 binds to the S2 site with its −SCN group surrounded by four hydrogen bond donors. With 1, we report two structures: in both, the quinuclidine headgroup binds in the allylic (S1) site with the side chain in S2, but in the presence of PPi and Mg2+, the quinuclidine’s cationic center interacts with PPi and three Mg2+, mimicking a transition state involved in diphosphate ionization. With 3, there are again two structures. In one, the geranyl side chain binds to either S1 or S2 and the adamantane headgroup binds to S1. In the second, the side chain binds to S2 while the headgroup binds to S1. These results provide structural clues for the mechanism and inhibition of the head-to-head prenyl transferases and should aid future drug design.
Nuclear ribosomal RNA genes and algal phylogeny--the Chlamydomonas example.

Abstract The nuclear ribosomal RNA genes (rDNA) of Chlamydomonas reinhardtii, C. moewusii and C. eugametos were examined with restriction endonuclease fragment and direct rRNA sequencing analyses. These comparative molecular data confirm similarity between C. moewusii and C. eugametos , and dissimilarity between the strains and C. reinhardtii For C. moewusii and C. eugametos , the fragment analysis of digests with 16 (six base pair recognition site) restriction endonucleases revealed either no or minor differences. These minor differences appear to be confined to length and site variation in the rapidly evolving intergenic spacer region of the algal rDNA repeat unit. In contrast, patterns of digests for C. reinhardtii were completely different from those of C. moewusii and C. eugametos for all enzymes tested. Over two regions of the 18S ribosomal RNA (spanning approx. 300 bases) in C. moewusii and C. eugametos , we observed three possible base substitutions and no insertion/deletion events. The same comparison between C. reinhardtii and C. moewusii (or C. eugametos ) revealed 31 base substitutions and eight insertion/deletion events. Overall, the rDNA comparisons support the proposed conspecificity of C. moewusii and C. eugametos , as well as the hypothesis that intraspeciflc variation in the algal ribosomal RNA coding region is minimal and that comparisons of rDNA sequences at higher taxonomic levels can be useful indicators of algal phylogeny. The degree of difference in the sequences of the 188 coding region between C. reinhardtii and C. moeurusii or C. eugametos is comparable to that between an angiosperm and Equisetum and may reflect an ancient divergence between two species in one algal genus. This possibility then raises the fundamental question of “How should molecular evolutionary data be used in the review of traditional concepts of taxonomy?”
Development of reasoning skills through participation in collaborative synchronous online discussions

This article investigates the effect of participation in synchronous online discussions on the development of individual reasoning as manifested in reflective essays. Students from a fourth-grade classroom engaged in a series of real-timeonline discussions. The format of the discussion was based on the Collaborative Reasoning approach which has clear guidelines and procedures. The results showed that compared to the students from the contrast classroom, the students who had experienced synchronous online discussions wrote essays with more satisfactory arguments, counterarguments, rebuttals, and textual information. In addition, they wrote longer essays which contained fewer irrelevant statements. These effects of online discussions were consistent between girls and boys and between shy and non-shy children. The students' uses of arguments and rebuttals, as well as the length of their essays, were adequately predicted by the frequency of their contributions in the discussions. The present study suggests th...
Complexes of trivalent phosphorus derivatives. XIV. Metal complexes of diphenylphosphinophenylacetylene

Abstract The following metal complexes of diphenylphosphinophenylacetylene ((C 6 H 5 ) 2 PCCC 6 H 5 ) were prepared by conventional methods: [(C 6 H 5 ) 2 PCCC 6 H 5 ] 3 CuCl, [(C 6 H 5 ) 2 PCCC 6 H 5 ]AuCl, [(C 6 H 5 ) 2 PCCC 6 H 5 ] 2 MCl 2 (M = Pd or Pt), [(C 6 H 5 ) 2 PCCC 6 H 5 ] 3 NiCO, [(C 6 H 5 ) 2 PCCC 6 H 5 RhCOCl] 2 , trans -[(C 6 H 5 ) 2 PCCC 6 H 5 ] 2 Fe(CO) 3 , trans -[(C 6 H 5 ) 2 PCCC 6 H 5 ] 2 Cr(CO) 4 , cis - and trans -[(C 6 H 5 ) 2 PCCC 6 H 5 ] 3 Cr(CO) 3 , cis -[(C 6 H 5 ) 2 PCCC 6 H 5 ] 3 M(CO) 3 , (M = Mo and W), C 5 H 5 Col 2 [C 6 H 5 ) 2 PCCC 6 H 5 ], C 5 H 5 FeCOBr[(C 6 H 5 ) 2 PCCC 6 H 5 ], and C 5 H 5 Mo(CO) 2 (COR)[(C 6 H 5 ) 2 PCCC 6 H 5 ] (R = CH 3 or C 6 H 5 CH 2 ). The reaction of cycloheptatrienentricarbonylchromium with (C 6 H 5 ) 2 PCCC 6 H 5 at room temperature yielded the expected cis -[(C 6 H 5 ) 2 PCCC 6 H 5 ] 3 Cr(CO) 3 but this reaction when carried out at 80° gave some of the corresponding trans -isomer as well as the cis -isomer thereby indicating a thermal rearrangement. Similarly, the reaction of norbornadienetetracarbonylchromium with (C 6 H 5 ) 2 PCCC 6 H 5 gave trans -[(C 6 H 5 ) 2 PCCC 6 H 5 ] 2 Cr(CO) 4 rather than the corresponding cis isomer. The infrared-active γ(CC) frequencies in the various metal complexes of diphenylphosphinophenylacetylene can be used as indicators of the relative amounts of retrodative π-bonding from filled metal d orbitals to the empty phosphorus d orbitals of the phosphine ligand. Using this frequency as an indicator, retrodative π-bonding is shown to be weaker in tetrahedral complexes than in octahedral, trigonal bipyramidal, or square planar complexes.
Absolute neutron flux measurements using an NE-110 scintillation counter

Abstract A neutron detector consisting of an NE-110 plastic scintillator has been calibrated for absolute neutron fluence measurements in the energy range 80 to 500 keV. Efficiencies were determined by Monte Carlo calculations. Comparisons of measured and calculated pulse height spectra are presented.
On internal organization in compressed random-access memories

The design of a compressed random-access memory (C-RAM) is considered. Using a C-RAM at the lowest level of a system's main-memory hierarchy, cache lines are stored in a compressed format and dynamically decompressed to handle cache misses at the next higher level of memory. The requirement that compression/decompression, address translation, and memory management be performed by hardware has implications for the directory structure and storage allocation designs used within the C-RAM. Various new approaches, summarized here, are necessary in these areas in order to have methods that are amenable to hardware implementation. Furthermore, there are numerous design issues for the directory and storage management architectures. We consider a number of these issues, and present the results of evaluations of various approaches using analytic methods and simulations. This research was done as part of a project to explore the feasibility of compressed-memory systems; it forms the basis for the memory organization of IBM Memory Expansion Technology (MXT).
Personality Attributes of Teachers in Organizational Climates.

AbstractThe purpose of this study was to ascertain, by means of responses to the Edwards Personal Reference Schedule, if personality patterns of elementary school teachers in schools possessing: Open Organizational Climates differed significantly from those of elementary school teachers in schools having Closed Organizational Climates. Through the use of the Organizational Climate Descriptive Questionnaire, a group of teachers (N=71) from schools having Open Organizational Climates and a group of teachers (N=99) from schools having Closed Organizational Climates were identified. Raw score profiles collected by administering the EPPS were tabulated for each of the subjects in the two groups and analyzed statistically through the use of the generalized F-test and the t-test. The F ratio was not significant of the acceptable .05 level of confidence. Teachers from schools having Open Climates did score significantly (P > .05) higher on the personality variables of intraception and abasement.
Sporadic dystrophic epidermolysis bullosa with concomitant atopic dermatitis

We describe a patient with sporadic dystrophic epidermolysis bullosa associated with well-documented atopic dermatitis. We discuss this case in relation to a newly described clinical subtype of epidermolysis bullosa known as epidermolysis bullosa pruriginosa, a dystrophic variant associated with prominent pruritus. The relations of this case of sporadic dystrophic epidermolysis bullosa with other dominantly inherited forms of dystrophic epidermolysis bullosa such as the Pasini variant, the pretibial variant, and Bart's syndrome are also discussed. The role of atopic dermatitis in exacerbating dystrophic epidermolysis bullosa in this patient raises an important consideration in the care of this group of patients.
Microbial biofilm formation in DUWS and their control using disinfectants.

Abstract Objectives Due to the presence of extended narrow bore tubing and long periods of stagnation, dental unit water systems (DUWs) can be prone to relatively high levels of microbial contamination, including the formation of biofilm and the presence of opportunistic pathogens, irrespective of the source and quality of the inflowing water. Whilst the European Union (EU) has yet to set a definitive microbiological guideline, the American Dental Association (ADA) has set a maximum of Study selection The review outlines the principal factors responsible for biofilm formation in DUWs and a number of mechanisms used for microbial control. Sources The source material contained in this review is taken from the peer-reviewed literature. Data A variety of disinfectants are available for use, but controlled laboratory and clinical studies have shown that they can vary markedly in their efficacy and suitability for use. Some products have been shown to successfully remove biofilm and consistently reduce the microbial load of out-flowing water to Conclusions The effective delivery of approved disinfectants can control the level of microorganisms in DUWs at acceptable levels.
Comments on "Measuring memory for source: Some theoretical assumptions and technical limitations"

Researchers must consider limitations and assumptions inherent in their measure of source monitoring when drawing conclusions, an important point raised by Murnane and Bayen (1998). However, the issues they raise do not invalidate the conclusions we draw from the findings reported in Henkel and Franklin (1998). Issues regarding conclusions about source monitoring performance, the relation between recognition and source accuracy, and the use of empirical and multinomial analyses are discussed.
An efficient and attack-resistant key agreement scheme for secure group communications in mobile ad-hoc networks

As a result of the growing popularity of wireless networks, in particular mobile ad hoc networks (MANET), security over such networks has become very important. Trust establishment, key management, authentication, and authorization are important areas that need to be thoroughly researched before security in MANETs becomes a reality. This work studies the problem of secure group communications (SGCs) and key management over MANETs. It identifies the key features of any SGC scheme over such networks. AUTH-CRTDH, an efficient key agreement scheme with authentication capability for SGC over MANETs, is proposed. Compared to the existing schemes, the proposed scheme has many desirable features such as contributory and efficient computation of group key, uniform work load for all members, few rounds of rekeying, efficient support for user dynamics, key agreement without member serialization and defense against the Man-in-the-Middle attack, and the Least Common Multiple (LCM) attack. These properties make the proposed scheme well suited for MANETs. The implementation results show that the proposed scheme is computationally efficient and scales well to a large number of mobile users. Copyright © 2007 John Wiley & Sons, Ltd.
House of Cards: The Academic Library Media Center in the Era of Streaming Video

In a time of increasing financial pressures on universities, the expense of library resources—and the potential for cost inflation—threaten the academic library collection. This article asks whether the academic library media center will be able to continue to offer a stable inventory of films, given the legal and commercial structures currently in place. It provides a history of the film industry’s interactions with its intermediaries, forecasts some of the obstacles to ongoing feature film affordability and access in libraries, offers strategies for librarians, and suggests some cause for hope.
Intramolecular electron transfer in cyanide-bridged ruthenium dimers

Abstract The absorption, luminescence, and transient-absorption spectra of [(bpy)(tpy)Ru II (CN)] + (bpy = 2,2′-bipyridine; tpy = 2,2′:6′2″-terpyridine) and [(bpy)(tpy)Ru II CNRu II,III (NH 3 ) 5 ] 3+,4+ have been measured. Metal-to-ligand charge-transfer (MLCT) excitation of the monomer produces an excited state that decays with a rate constant of 1.3 × 10 8 s −1 . Picosecond excitation of [(bpy)(tpy)Ru II CNRu II (NH 3 ) 5 ] 4+ does not lead to any detectable transients, indicating that relaxation rate constants are >10 12 s −1 . A transient attributed by [(bpy)(tpy .− )Ru II CNRu III (NH 3 ) 5 ] 3+ is observed following picosecond excitation of [(bpy)(tpy)Ru II CNRu II (NH 3 ) 5 ] 3+ ; this intermediate decays via intramolecular electron transfer with a rate constant of 3.8 × 10 10 s −1 . Quantum-mechanical descriptions of the nuclear reorganization accompanying electron transfer are required to explain the observed kinetics.
Near-Minimum Time, Closed-Loop Slewing of Flexible Spacecraft

The near-minimum time single-axis slewing of a flexible spacecraft with simultaneous suppression of vibration of elastic modes is considered. The hyperbolic tangent (tahh) function is used as a smooth approximation to the discontinuous sgn function occurring in the rigid body "bang-bang" control. Variable structure control concepts are used to identify the necessary characteristics of the control switching line. Simulations of the rest-to-rest and tracking maneuvers indicate that the elastic energy can be reduced by several orders of magnitude with only a modest increase in the maneuver time. Introduction M ANY future large space structures, due to mass con- traints, will be flexible. For the purpose of analysis these systems can be modeled with a large number of modes of vibration. For certain applications, it will be desirable that such a spacecraft be able to slew as rapidly as possible, within the operating limits of the control actuators. The problem of control design for rotational maneuver and vibration suppres- sion of flexible spacecraft has been addressed extensively.1'10 Optimal control theory can be applied to enforce quiescent terminal conditions on the flexible modes, usually by applying a quadratic cost function that weights the control rates and the states. The order of the system model grows rapidly as the number of flexible modes to be controlled is increased, mak- ing it impractical to attempt to control more than a few flexible modes. Furthermore, there is no rigorous means by which control magnitude constraints may be enforced. Al- though a feedback method such as the linear quadratic regula- tor (LQR) with terminal constraints9"11 is attractive because it can enforce quiescent conditions oh the elastic modes, its computational complexity is burdensome. The optimal control solution to the minimum time, single- axis, rotational maneuver problem for a rigid body gives a control scheme characterized by saturation of the control throughout the maneuver with at most one control switch that is instantaneous (bang-bang). Although not exactly achiev- able in physical systems, and even though the trajectories are extremely sensitive to variations in spacecraft parameters, this control law has wide application for rigid systems using on-off thrusters. When rigorously applied to flexible systems, how- ever, the result is typically multiple control switches and excessive excitation of the flexible modes of vibration. Previ- ous investigations of the near-time optimal maneuver for flexible systems7'8 are open-loop designs requiring extensive computational effort. An alternative is to compute the re- quired parameters for a number of initial conditions off-line and use table lookup and interpolation for a particular ma- neuver. This may involve excessive storage. We start with the assumption that the minimum time solution for a rigid space- craft can serve as an initial approximation to the near-mini- mum time solution for a flexible structure. In other words, we
Death Signals Changes in TFIID

In this issue of Molecular Cell, Bell et al. identify an isoform of hTAF(II)80 that is induced in response to several proapoptotic stimuli. The finding that extracellular signals can lead to changes in the subunit composition of TFIID provides an example of how regulated activity of the general transcription factors may contribute to inducible programs of gene expression.