bluuebunny/crossref_metadata_2025 huggingface dataset:
Easiest Routes and Slow Zones: How Fast Do I Go?: Speeds and Distances of Recreational and Expert Snowsport Participants
Authors: Dickson Tracey J. , Terwiel F. Anne , Waddington Gordon S. , Trathen Stephen D.
Published: May 2012

High speeds in snowsports have been associated with both the affective appeal as well as the risk of injury. Previous research of speeds of snowsport participants have been recorded on limited terrain or a single run using static radar guns or speed cameras. However, from a resort design and management perspective, more information is needed about areas of potential risk where there are a variety of users, skill levels, and speed. This exploratory research seeks to understand the actual and perceived distance and speeds traveled by a variety of snowsport participants over their day’s participation as well in resort-designated “slow zones.” A convenience sample of expert and recreational participants was recruited in a Western Canadian resort during the 2010–2011 season. A GPS-based data-logging device recorded speed, distance, duration, and location. Participants completed a questionnaire covering demographics, perceptions of maximum speed and distance traveled, and recommended speeds in slow zones. Data was collected over 102 sessions for alpine skiers, snowboarders, and telemarkers who traveled >4.5 km during their data-collection period: age range 9–80 years (x¯ = 42.0), 39.8 % females and 67.6 % advanced/expert. Total skiing/boarding time logged was 497 h (17 min–7 h, 38 min, x¯ = 4 h, 52 min) covering 4475 km (x¯ = 43.87 km). Estimates of distance traveled was 3–100 km (x¯ = 33.70 km, SD = 21.98 km). Maximum speeds recorded were 20.2–108.5 km/h (x¯ = 62.06 km/h); all but two recorded maximum speeds >23 km/h. Estimated maximum speeds ranged from 1–100 km/h (x¯ = 50.82 km/h). A paired sample t-test of estimated and actual maximum speeds was significant (p = .000). Participants’ recommendation for speeds in slow zones ranged from 5 to 60 km/h (x¯ = 23.8 km/h, mode = 30 km/h). Participants were generally unaware of the distances they traveled and the maximum speeds achieved, with most traveling in slow zones at speeds greater than their own recommendations.
Common Mechanisms of Hip Injury and Associated Hip Pathology in Professional Skiers and Snowboarders
Authors: Herzog Mackenzie M. , Briggs Karen K. , Philippon Marc J.
Published: May 2012

Hip injuries are common among athletes. Recent studies have analyzed hip pathology in many athletic populations; however, little research has been done on hip injuries and pathology among skiers and snowboarders. The purpose of this study is to review common mechanisms of hip injury and associated hip pathology in professional skiers and snowboarders. This study was institutional review board-approved. A retrospective database review was performed on all professional skiers and snowboarders who were evaluated by the senior author and underwent hip arthroscopy between 2005 and 2010 for debilitating hip pain. Professional skiers and snowboarders included athletes who compete at the professional level and instructors. Thirty-six painful hips were identified in 29 professionals (7 with bilateral involvement). Pathology and intra-operative findings were identified at time of index procedure. Subjective mechanism of injury was recorded. All data were prospectively collected and retrospectively reviewed. Twenty alpine skiers (4 bilateral), three Nordic skiers (2 bilateral), four snowboarders, and two aerialists (1 bilateral) were identified. A high-speed ski crash resulting in hip pain was the most common mechanism of injury (n = 14 hips), with all of those injuries occurring in racers and aerialists. All Nordic skiers (n = 5 hips) reported a gradual onset of hip pain with no specific injury. Three hip dislocations were reported by two alpine ski instructors and one alpine ski racer. All hips were found to have labral pathology and femoroacetabular impingement (FAI) at the time of index procedure. An Outerbridge grade IV chondral defect was treated with arthroscopic microfracture technique in five hips (14%). Seventeen hips (47%) were treated with capsular plication for hip instability. High-speed crashes are common mechanisms of hip injury. Labral pathology, FAI, and hip instability are frequent pathological arthroscopic findings in professional skiers and snowboarders.
An Effective Procedure for Calculating Weibull Production Yield with Mean Shift
Authors: Hsu Ya-Chen , Pearn W. L. , Li Yuan-Yi
Published: May 2012

Motorola, Inc. introduced its six sigma production quality initiative to the world in the 1980 s. Six sigma production quality is estimated by assuming a 1.5σ shift to the process mean. Bothe provided a statistical reason for considering such a shift in the normal process mean, and he also provided a much more accurate capability calculation to measure the production yield (Bothe, D. R., “Statistical Reason for the 1.5σ Shift,” Qual. Eng., Vol. 14(3), 2002, pp. 479–487). In this paper, we consider Weibull processes, which cover a wide class of non-normal processes. We calculate the mean shift adjustments under various sample sizes n and Weibull parameters, with the power fixed at 0.5. Then, we implement the derived results to develop an effective procedure to accurately calculate the production yield. Finally, to demonstrate the applicability of the proposed approach, the proposed procedure is applied to a real manufacturing process with mean shift.
Correlation Analysis of 2D Tomographic Images for Flaw Detection in Pavements
Authors: Hoegh Kyle , Khazanovich Lev
Published: May 2012

Ultrasonic tomography is an emerging method of nondestructive concrete pavement diagnostics which can be used for improved quality assurance/quality control during concrete pavement construction and assist in rehabilitation decision making. Detection of flaws using ultrasonic tomography requires significant effort and user expertise. To address these limitations, a quantitative method for determining the presence of defects in concrete pavements was developed. The proposed method is an adaptation of the recently developed impact-echo signature analysis method (IESA), which is used for comparison of impact-echo signals. The proposed two-dimensional ultrasonic tomography signature analysis (2D-UTSA) method was used to compare two-dimensional B-scans obtained using a commercial test system in field trials at the Minnesota Rd. Research Facility and the Federal Aviation Administration’s National Airport Pavement Test Facility. Analysis of the results showed that the 2D-UTSA method is capable of identifying subsurface defects.
The Assessment of Hand Volume Using a Modified Volumetric Technique
Authors: Tsang Kavin K. W. , Norte Grant E. , Hand James W.
Published: May 2012

Common methods of volumetric measurement include magnetic resonance imaging (MRI), bioelectrical impedance, Perometer, tape measure, and water volumetry. Methods driven with technology, i.e., MRI, provide results with high levels of precision while requiring sophisticated equipment and associated costs. More basic techniques, i.e., tape measure and water volumetry, require minimal equipment and costs but sacrifice on precision of results. Traditional water volumetric measurement is relatively inexpensive and simple to conduct but the precision of measurements can be limited by the quality and readability of the incorporated graduated cylinders. The objective of this study was to establish the reliability of a modified water volumetric technique on measurements of hand volume. Ten subjects with no previous volumetric measurement experience participated in the study. The reliability of this modified volumetric measurement procedure was demonstrated by an intraclass correlation coefficient [ICC (2, 1)] of 0.999. Furthermore, a standard error of measurement (SEM) of 1.68 ml was calculated for this procedure. Based on these results, we believe that the development of this modified volumetric technique provides clinicians with very reliable and precise measures of extremity volumes. Results from our current study continue to support the use of water volumetry as the gold standard in volumetric assessment and as such, the modified technique can be effectively utilized in both the research and clinical settings. We believe the modifications incorporated in our procedures are easily implemented and result in highly reliable measurements.
Application of Digital Image Correlation Technique in Experimental Study of the Creep Behavior and Time Dependent Damage of Natural Rock Salt
Authors: Yang Diansen , Chen Weizhong , Yang Jianping , Wu Guojun
Published: May 2012

The paper presents an experimental study on the creep behavior of a natural rock salt by means of digital image correlation (DIC) technique. To determine the creep rate and understand the creep mechanism of the rock salt, the time-dependent behavior of the material was studied at various scales (100 μm–1 cm) under different mechanical loading conditions. The results showed that the rock salt deformed at low constant stress. The strain rate at the macroscopic scale (cm) was about 10−9 s−1 at 11 MPa and it increased by an order of magnitude at 18 MPa. The strain rate at the mesoscopic scale (mm) depended on the microstructure, the boundary of subgrains deformed more rapidly than the subgrain, and the strain rate reached 10−7 s−1 at the interface of grains. The damage was identified by analyzing the full-field strain map and it was mainly caused by the open of cracks and it developed with the propagation of the cracks during creep tests.
System Identification of a Reinforced Concrete Building Using the Complex Mode Indicator Function and the Hilbert Transform Techniques
Authors: Gundes Bakir Pelin , Eksioglu Ender M. , Alkan Serhat
Published: May 2012

The complex mode indication function (CMIF) technique is a singular value decomposition enhancement of the classical peak picking (PP) technique. The disadvantages of the PP technique, namely, its inability to identify closely spaced modes, are largely resolved in CMIF due to the singular value decomposition. Recently, a frequency domain based technique that uses the biased frequency response functions obtained from the Hilbert transform of power spectral densities has been proposed. In this study, the PP, CMIF, and Hilbert transform techniques are successfully applied to the measured output data from a typical instrumented school building in Istanbul. The study clearly shows that the techniques can successfully identify the modal parameters and give similar results for the eigenfrequencies and mode shapes. However, there are some differences in the damping ratio estimates.
An Alternative Approach to Determine Material Characteristics Using Spherical Indentation and Neural Networks for Bulk Metals
Authors: Mahmoudi A. H. , Nourbakhsh S. H. , Amali R.
Published: May 2012

Material characteristics such as Young modulus, yield, and ultimate stresses are often considered as fundamental material parameters. Determination of material characteristics using the instrumented indentation test has gained interest among many researchers. The output of a spherical indentation test is usually the load-penetration (P-h) curve which is used to determine the Hollomon’s equation coefficients. Ideally, the elastic deformation of the sphere is to be excluded from the total displacement. However, the available techniques to omit the elastic deformation of the sphere are difficult-to-use and time consuming. In the present work, a noticeably simplified method is proposed to determine the load-displacement curve, preserving the required accuracy. The coefficients of Hollomon’s equation are then determined using the spherical indentation. The proposed method has also the ability to specify the unloading curve at each point of interest, even if the experimental data of the unloading procedure at that point is not available. Finally, by training a neural network and extracting the weights of its layers, an equation governing the network is presented explicitly. This expression makes the neural network easy to use. Furthermore, the proposed method is verified using the experimental results and method and experiment are shown to be in good agreement.
Parameters Estimation Under Step-Stress Life Test Based on Censored Data From Generalized Exponential Model
Authors: Ismail Ali A. , Abu-Youssef S. E.
Published: May 2012

This paper presents estimates of the parameters under step-stress partially accelerated life testing in the presence of censored data from generalized exponential distribution. The maximum likelihood procedure is used to derive point and asymptotic confidence interval estimations of the unknown parameters. Also, confidence bounds based on the log likelihood ratio are explored. The performance of the estimators is investigated numerically for different parameter values and different sample sizes in terms of their mean square error. A simulation study is made for illustrative purposes.
Solvothermal Synthesis of High Yield CdS Nanowires in Ethylenediamine
Authors: Hui Zhang , Guojun Song , Jianjiang Li
Published: May 2012

High yield CdS nanowires were synthesized by a solvothermal method using thiourea and cadmium nitrate tetrahydrate as precursors in ethylenediamine. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and UV-vis absorption spectroscopic techniques. XRD pattern indicates that the product is the hexagonal wurtzite CdS phase. SEM images show that the product is highly uniform CdS nanowires, and TEM images indicate that the diameter of the nanowires is about 50 nm and the length is up to several micrometers. Selected area electron diffraction (SAED) pattern reveals the as-prepared CdS nanowires’ single crystals with a preferential growth direction of (001). According to the experiments, the mechanism of the growth of CdS nanowires is discussed. The UV-vis absorption spectrum is shown to blueshift compared with that of bulk CdS due to the quantum size effect.
Responses of Austenitic Stainless Steel American Iron and Steel Institute (AISI) 303 (1.4305) Subjected to Different Environmental Conditions
Authors: Brnic Josip , Turkalj Goran , Canadija Marko , Lanc Domagoj , Krscanski Sanjin
Published: May 2012

In this paper some experimentally obtained results regarding mechanical properties at both low and elevated temperatures as well as short-time creep behavior of American Iron and Steel Institute (AISI) 303 (1.4305) austenitic stainless steel are presented. These results can be of importance in the design procedure for engineering components made of the considered material. The mentioned properties/strengths and short-time creep behavior were determined by uniaxial tests at different temperatures using materials testing machine. Impact energy was determined using the Charpy impact machine, while material hardness was determined using a universal hardness testing machine. For appropriate stress levels at selected temperatures, creep behavior modeling is displayed. Engineering fracture toughness assessment is based on experimentally obtained Charpy V-notch impact energy.
Influence of Drying and Wetting Cycles on SWCCs of Fine-Grained Soils
Authors: Jayanth Sneha , Iyer Kannan , Singh D. N.
Published: May 2012

The soil-water characteristics curve (SWCC) is greatly influenced by the path that is followed for suction measurement (i.e., drying or wetting path) and the number of cycles of these paths to which the soil is exposed. To evaluate the influence of these parameters, drying- and wetting-path SWCCs of three fine-grained soils were developed for single and multiple cycles by employing the Aquasorp® Isotherm generator. This device has been primarily employed for food products, powders, and amorphous materials for determination of their moisture sorption isotherm, which relates moisture content to water activity. As water activity can be mathematically related to soil suction, the Aquasorp® can be used for developing the SWCC. Hence, demonstrating the potential of the Aquasorp® for characterizing fine-grained soils becomes essential. The present study has been focused at highlighting the possible uncertainties associated with establishment of the SWCCs (both during drying and wetting paths) and the benefits and limitations of the Aquasorp® in achieving these objectives. Furthermore, by employing mercury intrusion porosimetry (MIP), the significance of capillarity on soil suction, which in turn governs the SWCC, has been demonstrated.
Evaluation of Durability of Stabilized Clay Specimens Using Different Laboratory Procedures
Authors: Khalife Roy , Solanki Pranshoo , Zaman Musharraf M.
Published: May 2012

In this comprehensive laboratory study, different tests—namely, investigations of the unconfined compressive strength (UCS) at the end of freeze-thaw/wet-dry (F-T/W-D) cycles, the resilient modulus (Mr) at the end of F-T/W-D cycles, vacuum saturation, and moisture susceptibility—were used to evaluate the durability of cementitiously stabilized subgrade soils. Two fat clays commonly encountered as subgrade soils in Oklahoma, Dennis and Lomill series, were utilized. These soils were stabilized with 6 % hydrated lime (or lime), 10 % class C fly ash (CFA), or 10 % cement kiln dust (CKD). Cylindrical specimens of three different sizes were compacted and cured for seven days. Then, Harvard miniature specimens were tested for UCS at the end of F-T/W-D cycles and moisture susceptibility (five-hour soaking). Additionally, cylindrical specimens were tested for Mr at the end of F-T and W-D cycles to evaluate the effect of F-T and W-D cycles on Mr. Furthermore, Proctor size specimens were tested for UCS after vacuum saturation. All the specimens showed a decrease in UCS values at the end of F-T cycles and vacuum saturation. In general, all the specimens tested in this study showed an increase in UCS values at the end of one W-D cycle. The Mr values of both raw and stabilized soil specimens were found to decrease with an increase in the number of F-T or W-D cycles. Both soils showed the maximum resistance to F-T and W-D cycles after being stabilized with 6 % lime, as compared to 10 % CFA and 10 % CKD. A similar trend was evident in both moisture susceptibility and vacuum saturation tests.
Discussion on “Influence of Feedback Control on Flexural Toughness of Fiber Reinforced Concrete in ASTM C1399 Tests,” by N. Banthia, S. Mindess, and Z. Jiang
Authors: Zollo Ronald F.
Published: May 2012

Having had a hand in leading the ASTM C09.42 Task Group involved with the development of C1399, the writer absorbed the referenced paper with more than usual interest. With respect due equally to the third listed author, the writer had previously enjoyed reading numerous other excellent works by each of the two first listed authors. However, this discussion may stimulate needed debate by voicing, and hopefully justifying, major disagreement with a number of comments that might be cause to question some of the paper’s conclusions.
Evaluating Process Yield for LED Assembly under Undetected Process Parameter Change
Authors: Tai Y. T.
Published: May 2012

The technology of light emitting diode (LED) assembly has become more popular due to the high demand for LED backlight modules, which can provide desirable characteristics such as a wide color gamut, a high dimming ratio, a long lifetime, and high power efficiency. For LED assembly processes, the distance between LEDs is one of the key parameters because the uniformity of an LED backlight module can be affected by it. In order to obtain good optical performance of an LED backlight module, the process yield of the parameter needs to be controlled well. Conventionally, process yields of LED assembly processes are evaluated using typical capability index methods under the essential assumption that the processes are stable. However, some inevitable process parameter changes regarding the distance between LEDs might exist on the shop floor. In order to evaluate the process yield more accurately, this paper presents an accommodated capability index method for process yield evaluation under undetected process parameter changes. For illustration purposes, an application is presented.
Microstructure Characterization of Mesoporous Materials by FE-SEM
Authors: Wei Wu , Ziwei Liu , Jiajie Hua , Yi Zeng , Yongsheng Li
Published: May 2012

Three types of mesoporous materials were observed directly by field emission-scanning electron microscopy (FE-SEM). The effects of accelerating voltage on these materials are discussed. Our results show that low-accelerating voltage could facilitate the observation of SBA-15 and TUD-1 mesoporous zeolite. However, as for mesoporous silica nano-spheres, high-accelerating voltage was helpful for the observation of surface structure.
Performance Evaluation and Loss Measures for the Deterioration Process
Authors: Shu Ming-Hung , Chen Peng-Jen
Published: May 2012

This paper considers a problem of loss measures and setup determination for a process under performance deterioration. Traditionally, to evaluate reliability and performance of the process, a binary-state model, a working (success) state or a failure state, is used to classify its conditions. However, in many cases, the process is deterioration over time, providing that a multiple-state model could be a more realistic model to capture the process deterioration conditions. Hence, the process under performance deterioration is considered as a general Markovian model, which means that its length of time staying in some state depends not only on its present state, but also on how long it has been in the present state. We present an integration method to find the probability function sojourning in each state at some point in time for this deterioration process. Based on probability functions of states, we first present a number of performance-evaluation methods. Then, we integrate a general class of loss functions to construct loss measures for assessing how severe the cost is that this process of deterioration causes at some point in time, as well as the cost over the entire deterioration process. With this measure, the setup time can be determined by the total expected cost over the operation period exceeding a preset threshold value. A tool-wear problem of the friction-drilling process is illustrated throughout the paper.
The Creep Testing Apparatus (CRETA): A New Testing Device for Measuring the Viscoelasticity of Joint Sealant
Authors: Li Qiang , Crowley Raphael W. , Bloomquist David B. , Roque Reynaldo
Published: May 2012

A new device, the Creep Testing Apparatus (CRETA), has been developed for use in determining the viscoelastic properties of joint sealant. Creep tests were conducted on two types of silicone sealant: self-leveling (SL) and non-self-leveling (NS). The results appear to indicate that the silicone sealant tested is a linear viscoelastic material and that its creep response does not appear to be sensitive to temperature variations from 0 °C to 60 °C. Further creep tests were conducted under artificial aging conditions. Hot water aging appears to cause both SL and NS sealant to become softer and more ductile. Freeze-thaw aging did not appear to have an effect on the viscoelastic properties. Oven aging did not appear to affect SL sealant, but it did cause NS sealant to become stiffer. These results might be useful in a long-term joint performance model.
Response to Discussion of “Influence of Feedback Control on Flexural Toughness of Fiber Reinforced Concrete in ASTM C1399 Tests” by N. Banthia, S. Mindess, and Z. Jiang
Authors: Banthia Nemy , Mindess S. , Jiang Z.
Published: May 2012

We would like to express our sincere thanks to Prof. Zollo for his very thoughtful comments on our paper. We are very aware of the seminal leadership of Prof. Zollo on the Task Group that developed C1399. We also fully agree with Prof. Zollo that these discussions are useful in improving our understanding of the limitations of C1399.
The association between CDC42 and caveolin-1 is involved in the regulation of capacitation and acrosome reaction of guinea pig and mouse sperm
Authors: Baltiérrez-Hoyos R , Roa-Espitia A L , Hernández-González E O
Published: May 2012

In the mammalian sperm, the acrosome reaction (AR) is considered to be a regulated secretion that is an essential requirement for physiological fertilization. The AR is the all-or-nothing secretion system that allows for multiple membrane fusion events. It is a Ca2+-regulated exocytosis reaction that has also been shown to be regulated by several signaling pathways. CDC42 has a central role in the regulated exocytosis through the activation of SNARE proteins and actin polymerization. Furthermore, the lipid raft protein caveolin-1 (CAV1) functions as a scaffold and guanine nucleotide dissociation inhibitor protein for CDC42, which is inactivated when associated with CAV1. CDC42 and other RHO proteins have been shown to localize in the acrosome region of mammalian sperm; however, their relationship with the AR is unknown. Here, we present the first evidence that CDC42 and CAV1 could be involved in the regulation of capacitation and the AR. Our findings show that CDC42 is activated early during capacitation, reaching an activation maximum after 20 min of capacitation. Spontaneous and progesterone-induced ARs were inhibited when sperm were capacitated in presence of secramine A, a specific CDC42 inhibitor. CAV1 and CDC42 were co-immunoprecipitated from the membranes of noncapacitated sperm; this association was reduced in capacitated sperm, and our data suggest that the phosphorylation (Tyr14) of CAV1 by c-Src is involved in such reductions. We suggest that CDC42 activation is favored by the disruption of the CAV1–CDC42 interaction, allowing for its participation in the regulation of capacitation and the AR.
Absence of seasonal changes in FSHR gene expression in the cat cumulus–oocyte complex in vivo and in vitro
Authors: Hobbs Rebecca J , Howard JoGayle , Wildt David E , Comizzoli Pierre
Published: May 2012

Domestic cat oocytes are seasonally sensitive to FSH. Compared with those collected during the breeding season, oocytes from the nonbreeding (NB) season require more FSH during in vitro maturation to achieve comparable developmental competence. This study tested the hypothesis that this seasonal variation was due to altered expression of FSH receptors (FSHR) and/or FSH-induced genes. Relative expression levels of FSHR mRNA and FSH-enhanced gene estrogen receptor β (ESR2) were measured by qPCR in whole ovaries and immature cumulus–oocyte complexes (COCs) isolated from cat ovaries during the natural breeding vs NB seasons. Expression levels of FSH-induced genes prostaglandin-endoperoxide synthase 2 (PTGS2), early growth response protein-1 (EGR1), and epidermal growth factor receptor (EGFR) were examined in mature COCs from both seasons that were a) recovered in vivo or b) matured in vitro with conventional (1 μg/ml) or high (10 μg/ml) FSH concentrations. Overall, FSHR mRNA levels were lower in whole ovaries during the NB compared with breeding season but were similar in immature COCs, whereas ESR2 levels did not differ in either group between intervals. We observed changes in PTGS2, EGR1, and EGFR mRNA expression patterns across maturation in COCs within but not between the two seasons. The lack of seasonal differentiation in FSH-related genes was not consistent with the decreased developmental capacity of oocytes fertilized during the NB season. These findings reveal that the seasonal decrease in cat oocyte sensitivity to FSH occurs both in vivo and in vitro. Furthermore, this decline is unrelated to changes in expression of FSHR mRNA or mRNA of FSH-induced genes in COCs from antral follicles.
New Negative Feedback Regulators of Egfr Signaling inDrosophila
Authors: Butchar Jonathan P , Cain Donna , Manivannan Sathiya N , McCue Andrea D , Bonanno Liana , Halula Sarah , Truesdell Sharon , Austin Christina L , Jacobsen Thomas L , Simcox Amanda
Published: May 2012

The highly conserved epidermal growth factor receptor (Egfr) pathway is required in all animals for normal development and homeostasis; consequently, aberrant Egfr signaling is implicated in a number of diseases. Genetic analysis of Drosophila melanogaster Egfr has contributed significantly to understanding this conserved pathway and led to the discovery of new components and targets. Here we used microarray analysis of third instar wing discs, in which Egfr signaling was perturbed, to identify new Egfr-responsive genes. Upregulated transcripts included five known targets, suggesting the approach was valid. We investigated the function of 29 previously uncharacterized genes, which had pronounced responses. The Egfr pathway is important for wing-vein patterning and using reverse genetic analysis we identified five genes that showed venation defects. Three of these genes are expressed in vein primordia and all showed transcriptional changes in response to altered Egfr activity consistent with being targets of the pathway. Genetic interactions with Egfr further linked two of the genes, Sulfated (Sulf1), an endosulfatase gene, and CG4096, an A  Disintegrin And Metalloproteinase with ThromboSpondin motifs (ADAMTS) gene, to the pathway. Sulf1 showed a strong genetic interaction with the neuregulin-like ligand vein (vn) and may influence binding of Vn to heparan-sulfated proteoglycans (HSPGs). How Drosophila Egfr activity is modulated by CG4096 is unknown, but interestingly vertebrate EGF ligands are regulated by a related ADAMTS protein. We suggest Sulf1 and CG4096 are negative feedback regulators of Egfr signaling that function in the extracellular space to influence ligand activity.
The mRNA Decay Pathway Regulates the Expression of the Flo11 Adhesin and Biofilm Formation inSaccharomyces cerevisiae
Authors: Lo Tricia L , Qu Yue , Uwamahoro Nathalie , Quenault Tara , Beilharz Traude H , Traven Ana
Published: May 2012

Regulation of the FLO11 adhesin is a model for gene expression control by extracellular signals and developmental switches. We establish that the major mRNA decay pathway regulates FLO11 expression. mRNA deadenylation of transcriptional repressors of FLO11 by the exonuclease Ccr4 keeps their levels low, thereby allowing FLO11 transcription.
The Contribution of the Y Chromosome to Hybrid Male Sterility in House Mice
Authors: Campbell Polly , Good Jeffrey M , Dean Matthew D , Tucker Priscilla K , Nachman Michael W
Published: May 2012

Hybrid sterility in the heterogametic sex is a common feature of speciation in animals. In house mice, the contribution of the Mus musculus musculus X chromosome to hybrid male sterility is large. It is not known, however, whether F1 male sterility is caused by X–Y or X-autosome incompatibilities or a combination of both. We investigated the contribution of the M. musculus domesticus Y chromosome to hybrid male sterility in a cross between wild-derived strains in which males with a M. m. musculus X chromosome and M. m. domesticus Y chromosome are partially sterile, while males from the reciprocal cross are reproductively normal. We used eight X introgression lines to combine different X chromosome genotypes with different Y chromosomes on an F1 autosomal background, and we measured a suite of male reproductive traits. Reproductive deficits were observed in most F1 males, regardless of Y chromosome genotype. Nonetheless, we found evidence for a negative interaction between the M. m. domesticus Y and an interval on the M. m. musculus X that resulted in abnormal sperm morphology. Therefore, although F1 male sterility appears to be caused mainly by X-autosome incompatibilities, X–Y incompatibilities contribute to some aspects of sterility.
Fibrinogen Adsorption on Hydroxyapatite, Carbonate Apatite and Gold Surfaces In Situ Detected by Quartz Crystal Microbalance with Resistance Technique
Authors: Yonekura Hiroshi , Tagaya Motohiro , Yoshioka Tomohiko , Ikoma Toshiyuki , Tanaka Junzo
Published: May 2012

When a biomaterial is implanted into the body, blood proteins adsorb on its surface and subsequently cells adhere via the protein adlayer. Thus, the understanding of protein adsorption and conformational change on the biomaterial surfaces is of great importance to control the biocompatibility such as antithrombotic properties and cell adhesion behaviors. In this study, we synthesized hydroxyapatite (HAp) and carbonate apatite (CAp) by a wet method. Then we successfully fabricated the HAp and CAp sensors for QCM-R by an electrophoretic deposition method. Adsorption behavior of proteins on the bone substitute material can be monitored by using these apatite sensors. Bovine serum albumin and fibrinogen were employed for the model proteins, and monitored the adsorption behavior on the HAp, CAp and reference gold (Au) sensors by the QCM-R technique. As a result, we revealed that fibrinogen and bovine serum albumin adsorbs on the gold surface by hydrophobic interaction, and adsorbs on the HAp and CAp surfaces mainly by electrostatic force. Besides, we revealed that fibrinogen adsorbs on the Au surface more rigid than on the HAp and CAp surfaces while bovine serum albumin adsorbs on the HAp and CAp surface more rigidly than on the Au surface.
Silicon Nanowires Obtained by Low Temperature Plasma-Based Chemical Vapor Deposition.
Authors: Puglisi R. A. , Mannino G. , Scalese S. , La Magna A. , Privitera V.
Published: May 2012

Silicon Nanowires (Si-NWs) are obtained by vapor-liquid-solid growth using an inductively coupled chemical vapor deposition system which works at temperatures lower than 400 °C. Gold nanodots are used as metal catalyst. The selective growth of Si-NWs on the gold nanodots is obtained by controlling the contribution coming from the uncatalyzed growth on the bare Si substrate. In this way the final NW length can be controlled, and it is not influenced by the thickness of the uncatalyzed layer. The important parameter ruling the NW growth is found to be the plasma power which governs the dissociation of the Si precursor gas. Final NW lengths of 1 μm are obtained at temperatures of 380 °C with a thickness of uncatalyzed layer equal to zero. Also the NW density is addressed in this work and it is optimised by increasing the gold equivalent thickness. The NW density is increased from 2.9×108 to 1.3×1010 cm-2, when the gold equivalent thickness passes from 1.8 nm to 2.2 nm.
Preparation and Characterization of Pb(Zr,Ti)O3 films prepared by a modified sol-gel route
Authors: Jiang Dan , Zhao Chen , Bu Shundong , Cheng Jinrong
Published: May 2012

Pb(Zr0.53Ti0.47)O3 (PZT) films have been fabricated on stainless steel substrates by a Polyvinylpirrolidone (PVP) modified sol-gel route. The single layer of about 0.26 μm was achieved by using the PVP-modified PZT sol, and Crack-free PZT films with thickness of up to 2.37 μm were fabricated by repeating the deposition process. The variations in crystallite orientation, microstructure, dielectric and ferroelectric properties of PZT films were investigated as a function of film thickness. Our results indicate that PZT films prepared on stainless steel substrates maintain good dielectric and ferroelectric properties.
Radial p-n Junction Solar Cells by Core-Shell Silicon Nanowire Arrays
Authors: Huang Tai-Yuan , Yen Ta-Jen
Published: May 2012

We first fabricated a p-type single-crystalline SiNW array as the core by statistic electroless metal deposition (SEMD) method[1]. This structure exhibits per excellent absorption efficiency without increasing the diffusion path, indicating 1.75 times greater performance than Si-based planar solar cells under the same condition[2]. Next, we employed a method of spin-on dopant (SOD) to fabricate an n-type layer as an external thin shell, which benefits to decouple the absorption of light from charge transport by allowing lateral diffusion of minority carriers to the p-n junction rather than many microns away as in Si bulk solar cells, and is suitable for our SiNW array with a hydrophilic surface. Finally, our SiNW-based solar cell possesses strong broadband absorption and low reflection from visible light to near IR, in which the highly light trapping mechanism stems from the effective medium theory (EMT) to demonstrate only less than 3% of total reflectance in the range of 500-1100 nm. It also shows conversion efficiency improvement of 20% compared with the planar single-crystalline Si solar cell by the same fabrication processes. The proposed novel photovoltaic device by our core-shell SiNW array revolutionizes the current architecture of solar cells, promising niche points of (1) better absorption, (2) self-antireflection, and (3) low-cost process.
Thiol coupling based synthesis of temperature-sensitive polymer–peptide conjugates with controlled architecture.
Authors: Guilbaud Jean-Baptiste , Miller Aline F. , Saiani Alberto
Published: May 2012

A synthetic strategy to couple selectively an ionic complementary thiol modified octapeptide, that is able to gel at low temperature, to the thermoresponsive polymer poly(N-isopropylacrylamide) (pNIPAAm) with controlled molecular weight and narrow polydispersity is described. The polymer was synthesized by atom transfer radical polymerization (ATRP) affording halogen functionalized chain ends. This allowed subsequent coupling to a thiol terminated ionic complementary octapeptide via nucleophile substitution. Results indicated that the peptide was covalently attached to the polymer and that both the coil-globule phase transition of pNIPAAm and the gelation properties of the peptide were retained in the conjugated product. This method provides a versatile route for the synthesis of a range of bioconjugate materials with controlled architecture and dual self-assembling and thermoresponsive behavior.
Pulsed Laser Assisted Polycrystalline Growth of Oxide Thin Films for Efficient Processing
Authors: Nakajima Tomohiko , Shinoda Kentaro , Tsuchiya Tetsuo
Published: May 2012

We have investigated the polycrystalline growth by means of an excimer laser assisted metal organic deposition process and the strategy for the efficient growth. It was revealed that the pulsed photo thermal heating properties must be controlled by changing the laser fluence according to the substrate properties, such as thermal diffusivity. The threshold of the teff value for initial crystal nucleation is approximately 70 ns for oxide thin films. For the fabrication of good quality films with high crystallinity and without a laser ablation of the film surface, it is necessary that the irradiated laser fluence is adjusted to the conditions of teff (efficient annealing time) > 70 ns and Tmax (maximum temperature) < Tm (melting point). Obtained oxide films by using the pulsed UV laser has large crystallite size, and it well functioned to enhance physical properties of films. For further efficient growth for polycrystalline growth of the oxide films, the starting solution containing nanoparticles is very useful: it is named as photo-reaction of nanoparticles process.
Can We Trust on the Thermal Analysis of Metal Organic Powders for thin film preparation?
Authors: Farjas Jordi , Sanchez-Rodriguez Daniel , Eloussifi Hichem , Hidalgo Raul Cruz , Roura Pere , Ricart Susagna , Puig Teresa , Obradors Xavier
Published: May 2012

Thermal analysis techniques are routinely applied to characterize the thermal behavior of metal organic precursors used for oxide film preparation. Since the mass of films is very low, researchers do their thermal analyses on powders and consider that the results are representative of films. We will show here that, in general, this assumption is not true. Several examples involving precursors of YBa2Cu3O7-x (Ba and Y trifluoroacetates and Ba propionate) will serve to appreciate that films can behave very differently than powders due to their enhanced heat and mass transport paths. Ultimately, we will demonstrate that, in some cases, relying on powders thermal analysis may lead to erroneous conclusions.
Characterization of Plasma Synthesized Vertical Carbon Nanofibers for Nanoelectronics Applications
Authors: Lee Jaesung , Feng Philip X.-L. , Kaul Anupama B.
Published: May 2012

We report on the material characterization of carbon nanofibers (CNFs) which are assembled into a three-dimensional (3D) configuration for making new nanoelectromechanical systems (NEMS). High-resolution scanning electron microscopy (SEM) and x-ray electron dispersive spectroscopy (XEDS) are employed to decipher the morphology and chemical compositions of the CNFs at various locations along individual CNFs grown on silicon (Si) and refractory nitride (NbTiN) substrates, respectively. The measured characteristics suggest interesting properties of the CNF bodies and their capping catalyst nanoparticles, and growth mechanisms on the two substrates. Laser irradiation on the CNFs seems to cause thermal oxidation and melting of catalyst nanoparticles. The structural morphology and chemical compositions of the CNFs revealed in this study should aid in the applications of the CNFs to nanoelectronics and NEMS.
Palliative Care in Advanced Cancer Patients: Waiting for Godot
Authors: Marchetti Paolo , Di Rocco Zorika Christiana
Published: May 2012

A study by Bruera et al. published in a recent issue of The Oncologist is discussed.
In Reply
Authors: Bruera Eduardo , Yennurajalingam Sriram
Published: May 2012

The authors comment on the discussions of their work published in a recent issue of The Oncologist.
Spatial clustering of habitat structure effects patterns of community composition and diversity
Authors: Altermatt Florian , Holyoak Marcel
Published: May 2012

Natural ecosystems often show highly productive habitats that are clustered in space. Environmental disturbances are also often nonrandomly distributed in space and are either intrinsically linked to habitat quality or independent in occurrence. Theoretical studies predict that configuration and aggregation of habitat patch quality and disturbances can affect metacommunity composition and diversity, but experimental evidence is largely lacking. In a metacommunity experiment, we tested the effects of spatially autocorrelated disturbance and spatial aggregation of patch quality on regional and local richness, among‐community dissimilarity, and community composition. We found that spatial aggregation of patch quality generally increased among‐community dissimilarity (based on two measures of β diversity) of communities containing protozoa and rotifers in microcosms. There were significant interacting effects of landscape structure and location of disturbances on β diversity, which depended in part on the specific β diversity measures used. Effects of disturbance on composition and richness in aggregated landscapes were generally dependent on distance and connectivity among habitat patches of different types. Our results also show that effects of disturbances in single patches cannot directly be extrapolated to the landscape scale: the predictions may be correct when only species richness is considered, but important changes in β diversity may be overlooked. There is a need for biodiversity and conservation studies to consider the spatial aggregation of habitat quality and disturbance, as well as connectivity among spatial aggregations.
Insect herbivores, density dependence, and the performance of the perennial herb Solanum carolinense
Authors: Underwood Nora , Halpern Stacey L.
Published: May 2012

How insect herbivores affect plant performance is of central importance to basic and applied ecology. A full understanding of herbivore effects on plant performance requires understanding interactions (if any) of herbivore effects with plant density and size because these interactions will be critical for determining how herbivores influence plant population size. However, few studies have considered these interactions, particularly over a wide enough range of densities to detect nonlinear effects. Here we ask whether plant density and herbivores influence plant performance linearly or nonlinearly, how plant density affects herbivore damage, and how herbivores alter density dependence in transitions between plant size classes. In a large field experiment, we manipulated the density of the herbaceous perennial plant Solanum carolinense and herbivore presence in a fully crossed design. We measured plant size, sexual reproduction, and damage to plants in two consecutive years, and asexual reproduction of new stems in the second year, allowing us to characterize both plant performance and rates of transition between plant size classes across years. We found nonlinear effects of plant density on damage. Damage by herbivores and plant density both influenced sexual and asexual reproduction of S. carolinense; these effects were mostly mediated via effects on plant size. Importantly, we found that herbivores altered the pattern of linear density dependence in some transition rates (including survival and asexual reproduction) between plant size classes. These results suggest that understanding the ecological or evolutionary effects of herbivores on plant populations requires consideration of plant density and plant size, because feedbacks between density, herbivores, and plant size may complicate longer‐term dynamics.
Contrasting effects of variable species recruitment on marine sessile communities
Authors: Sams Michael A. , Keough Michael J.
Published: May 2012

The species composition, density, and frequency of recruitment into any given habitat are highly variable in most biological systems that rely on dispersive propagules (larvae, seeds, spores, etc.). There are few direct experimental studies of how recruitment variation between single species influences the composition and assembly of whole communities in many of these systems. We manipulated recruitment of a variety of single taxa and followed their effects on the subsequent development of hard‐substrate communities of sessile animals living in temperate marine waters. The effects of recruitment on communities were complex. Patterns of recruitment of individual species influenced community structure, but these effects varied greatly depending on the identity of species recruits, the time of community development, and location across three different sites. Variable recruitment of arborescent bryozoans and didemnid ascidians had little effect on community structure. At one site, recruitment of the colonial ascidian Botryllus schlosseri had short‐lived effects on community structure, while barnacles had more persistent effects. At another site, recruitment of B. schlosseri and the bryozoan Watersipora subtorquata had strong persistent effects on community structure, dominating space where they recruited and influencing the abundances of a variety of different taxa. Differences in the effects of species recruitment on communities appear to be caused by differences between the ecology and life history of recruiting species as well as differences in background processes between sites. These results demonstrate that discrete recruitment events that vary between single species can be important drivers of community composition but are likely to be heavily influenced by the local environment, even within a single species.
Distinguishing between Lévy walks and strong alternative models
Authors: Reynolds A. M.
Published: May 2012

Lévy walks are a widely used but contentious model of animal movement patterns. They are contentious because they have been wrongly ascribed to some animal species through use of incorrect statistical methods and because they have not been adequately compared against strong alternative models, such as composite correlated random walks. This lack of comparison has been partly because the strong alternative models do not have simple likelihood functions. Here I show that power‐spectra and the distribution of the first significant digits (the leading non‐zero digits) of the step lengths can distinguish between Lévy walks and composite correlated random walks. Using these diagnostic tools, I bolster previous claims that honey bees use a movement strategy that can be approximated by Lévy walks when searching for their hive or for a food source.