Maximizing aesthetics of debilitated maxillary central incisors: a clinical case

With the advent of true "adhesive dentistry," practitioners have at their disposal new multi-purpose adhesive agents which bond to most dental substrates. These new adhesives have a high affinity for roughened or "microetched" surfaces, penetrating and wetting the surfaces to increase the bonding strength. The improved adhesion has altered treatment plans from previous years and has enabled clinicians to practice more constructive dentistry and replace only defective or missing tooth structure. The objective of this article is to present a case report to illustrate the utilization of one of the new bonding agents in an especially difficult clinical situation.     

UDP-glucose dehydrogenase from bovine liver: primary structure and relationship to other dehydrogenases

The primary structure of bovine liver UDP-glucose dehydrogenase (UDPGDH), a hexameric, NAD(+)-linked enzyme, has been determined at the protein level. The 52-kDa subunits are composed of 468 amino acid residues, with a free N-terminus and a Ser/Asn microhetergeneity at one position. The sequence shares 29.6% positional identity with GDP-mannose dehydrogenase from Pseudomonas, confirming a similarity earlier noted between active site peptides. This degree of similarity is comparable to the 31.1% identity vs. the UDPGDH from type A Streptococcus. Database searching also revealed similarities to a hypothetical sequence from Salmonella typhimurium and to "UDP-N-acetyl-mannosaminuronic acid dehydrogenase" from Escherichia coli. Pairwise identities between bovine UDPGDH and each of these sequences were all in the range of approximately 26-34%. Multiple alignment of all 5 sequences indicates common ancestry for these 4-electron-transferring enzymes. There are 27 strictly conserved residues, including a cysteine residue at position 275, earlier identified by chemical modification as the expected catalytic residue of the second half-reaction (conversion of UDP-aldehydoglucose to UDP-glucuronic acid), and 2 lysine residues, at positions 219 and 338, one of which may be the expected catalytic residue for the first half-reaction (conversion of UDP-glucose to UDP-aldehydoglucose). A GXGXXG pattern characteristic of the coenzyme-binding fold is found at positions 11-16, close to the N-terminus as with "short-chain" alcohol dehydrogenases.(ABSTRACT TRUNCATED AT 250 WORDS)     

A classification method to distinguish cell-specific responses elicited by current pulses in hippocampal CA1 pyramidal cells

The suprathreshold electrophysiological responses of pyramidal cells have been grouped into large classes such as bursting and spiking. However, it is not known whether, within a class, response variability ranges uniformly across all cells or whether each cell has a unique and consistent profile that can be differentiated. A major difficulty when comparing suprathreshold responses is that slight variations in spike timing in otherwise very similar traces render traditional metrics ineffective. To address these issues, we developed a novel distance measure based on fiducial points to quantify the similarity among traces with trains of action potentials and applied it together with classification techniques to a set of in vitro patch clamp recordings from CA1 pyramidal cells. We tested if responses to repeated current stimulation of a given cell would cluster together yet remain distinct from those of other cells. We found that depolarizing and hyperpolarizing current pulses elicited responses in each cell that clustered and were systematically distinguishable from responses in other cells. The fiducial-point distance measure was more effective than other methods based on spike times and voltage-gradient phase planes. Depolarizing traces were more reliably differentiated than hyperpolarizing traces, and combining both scores was even more effective. These results suggest that each CA1 pyramidal cell has unique properties that can be detected and quantified with methods discussed here. This uniqueness may be due to slight variations in morphology or membrane channel densities and kinetics, or to large, coordinated variations in these elements. Ascertaining the actual sources and their degree of variability is important when constructing network models of neural function to ensure that key mechanisms are robust in the face of variations within these ranges. The analytical tools presented here can assist in constructing detailed cell models to match experimental records to elucidate the sources of electrophysiological variability in neurons.     

Statistical modelling of communities and ecosystems using the LAMDA software tool

Understanding species interactions is critical to discovering community dynamics. Recently, statistical methods for estimating species interaction strengths from time series data have been developed based on multivariate auto-regressive first-order, or MAR(1), models. However, the complex coding required presents a substantial barrier for most ecologists. We have developed LAMBDA, a software program that allows users to easily fit MAR(1) models to multi-species time series data. The LAMBDA package covers: data input and transformation, selection of the interactions to include via a search algorithm and model selection, estimation of interaction parameters via conditional least squares (CLS) regression or two different maximum-likelihood (ML) algorithms, estimation of confidence intervals via bootstrapping, and computation of community stability properties using the estimated model. We describe performance tests on the variability of estimates, computation speed, and CLS versus ML estimation using simulated data.     

The influence of seat backrest angle on human performance during whole-body vibration

This study investigated the effects of reclined backrest angles on cognitive and psycho-motor tasks during exposure to vertical whole-body vibration. Twenty participants were each exposed to three test stimuli of vertical vibration: 2-8 Hz; 8-14 Hz and 14-20 Hz, plus a stationary control condition whilst seated on a vibration platform at five backrest angles: 0° (recumbent, supine) to 90° (upright). The vibration magnitude was 2.0 ms(-2) root-mean-square. The participants were seated at one of the backrest angles and exposed to each of the three vibration stimuli while performing a tracking and choice reaction time tasks; then they completed the NASA-TLX workload scales. Apart from 22.5° seat backrest angle for the tracking task, backrest angle did not adversely affect the performance during vibration. However, participants required increased effort to maintain performance during vibration relative to the stationary condition. These results suggest that undertaking tasks in an environment with vibration could increase workload and risk earlier onset of fatigue. PRACTITIONER SUMMARY: Current vibration standards provide guidance for assessing exposures for seated, standing and recumbent positions, but not for semi-recumbent postures. This paper reports new experimental data systematically investigating the effect of backrest angle on human performance. It demonstrates how workload is elevated with whole-body vibration, without getting affected by backrest angle.     

Supervisor Perspective on the Process and Outcome of Giving Easy, Difficult, or No Feedback to Supervisees.

Fifteen counseling center supervisors were interviewed about 3 instances related to important feedback with an intern supervisee: 1 in which the feedback was given easily, 1 in which it was given reluctantly or with difficulty, and another in which it was not given. Supervisors indicated that easy feedback was most often about clinical problems, was given directly, had positive effects, and was facilitated by supervisee openness. Difficult feedback was most often about clinical, personal, and professional issues, was given indirectly, had mixed impact, and was characterized by a lack of supervisee openness. Feedback not given was typically about personal and professional concerns and was hindered by a lack of supervisee openness. Supervisors indicated that there were negative effects of not having given the feedback and indicated that they would do it differently if they could. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ordered Mesoporous Silicate Structures as Potential Templates for Nanowire Growth

Mesoporous thin films are prepared using a simple sol–gel technique. Using lithographically patterned (100)‐orientated substrates and a dip‐coating method reproducible alignment of the pores across the substrate surface can be obtained. The pores preferentially align parallel to the long side of the channels etched into the surface. The channels within the aligned films are subsequently filled with cobalt (to form nanowire‐type structures) using a supercritical fluid inclusion technique, to allow high‐resolution imaging of the pore by using secondary electron microscopy. The channel structure imposes a strain on the mesoporous arrangement resulting in some variation in d‐spacings compared to simple films. The results indicate that the topographic structure can be used to engineer the placement and directionality of the pore structure and the potential of the aligned mesostructures are discussed.     

卫星运营商的C频段保卫战

本文为我们展现了一幅国际上卫星运营商与电信运营商在卫星C频段领域的争夺画面。由于技术与商业双重因素,C频段的争夺显得尤为激烈。首先,作者提到了C频段对于卫星运营商和电信运营商的价值所在,然后,作者希望通过这篇文章,通告用户在C频段上业务的规模和范围的原因,并建议政府肯定卫星C频段的业务的价值和重要的功能     

Languages and the computing profession

When involved in a project to develop an intermediary language, translators, interpreters, and linguists will need to work closely together, as grammar and vocabulary are closely interdependent. In this case, both must cope with the translation of many hundreds of wildly different languages. What role would computing professionals play in such a team? Given the project's purpose - to make general machine translation possible - computing professionals would be of vital importance, but in a supporting role. Using different approaches to evaluate the intermediate language and its use for a variety of languages would require a succession of translation programs.