bluuebunny/crossref_metadata_2025 huggingface dataset:
Semi-Submerged Propellers for Monohull Displacement Ships
Authors: Rains Dean A.
Published: December 2022

Generally, semi-submerged propellers are considered useful for planning and SES hulls. But their value for displacement hulls is explored in this document. Two attributes make this concept attractive: the good propulsive coefficient demonstrated by semi-submerged propellers and the possibility of minimizing hull appendage drag by deleting propeller shafting, hub and struts.

This investigation includes analysis of semi-submerged propeller designs suitable for a twin screw DD 963 Class destroyer. The performance is estimated for various diameters, amount of submergence and other parameters. An analysis of the merits of a cavitating versus fully-wetted blading is described. The analysis concludes that the aforementioned attributes are valid and the concept is attractive. A fully-wetted blade design is selected based on this study as well. Propeller channel tests are described which confirm propeller performance and a propulsive efficiency of 60 percent to 65 percent. All results are tabulated and discussed. The fully-wetted design. is determined as the best approach.

Fully self-propulsion tests for a DD 963 destroyer hull with twin semi-submerged propellers are reported. A 5 percent reduction in SHP at 20 knots is measured. All results are tabulated and discussed. A 10 percent reduction can be expected for an optimized propeller design. Noise tests have not been carried out yet, but they are proposed for future investigation. In conclusion, the work to date indicates that the concept is attractive for an energy-conserving propulsor design and should be further evaluated for monohull configurations.
Full Scale lcebreaking Stresses on Propellers of the Polar Star
Authors: Antonides Gary , Hagen Adrian , Langreck Don
Published: December 2022

The POLAR Class icebreakers were the first large high powered icebreakers to use controllable pitch (GP) propellers. During their first three years of operation, significant structural problems were encountered with the internal mechanisms of the propellers. The initial failures were due largely to lack of understanding the loads imposed on the propeller by ice.

The Coast Guard decided to have the internal components of the propellers redesigned and rebuilt with the maximum strength that could be fit inside the same hub. At the same time the David W. Taylor Naval Ship R&D Center (DTNSRDC) instrumented the links and propeller blades to make stress measurements while actually breaking ice.

This paper briefly discusses the structural failures, the failure analysis, the design changes, full scale trial instrumentation, stress measurements, and computerized analysis of stresses along with fatigue life estimates.

The loads are not high enough to cause yielding of any of the structural components of the redesigned propeller, but are high enough to cause some fatigue damage. A computer program was written to analyze the stress data; the results are being used for predicting fatigue life, and for obtaining a statistical representation of the loads applied.
Sizing Segmental Section--Commercially Available Propellers for Small Craft
Authors: Blount Donald L. , Hubble E. Nadine
Published: December 2022

Open water characteristics for segmental section propellers are synthesized as a function of pitch ratio, expanded area ratio and number of blades using modifications of the Wageningen B-Screw series polynomials. Thrust and torque limits in a cavitating environment are estimated from maximum thrust and torque load coefficients developed from the Gawn-Burrill cavitation data. Synthesized thrust and torque coefficients as functions of propeller advance coefficient and cavitation number are compared with experimental series data and with commercial propellers of the flat face, segmental section type tested in open water and under cavitating conditions.

A procedure for selection of propeller diameter and pitch ratio for best performance -- maximum efficiency and minimal cavitation -- is presented, with number of blades and expanded area ratio being preselected. The method is directed to selection of commercially available propellers for small craft, in lieu of more costly custom design propellers. Reference. is made to computer routines· for expediting propeller selection using synthesized performance data.
Propeller Induced Noise in Ships
Authors: Nilsson A. , Persson B. , Tyvand N. P.
Published: December 2022

The propeller noise induced in the accommodation spaces on as ship is a function of the acoustical source strength of the propeller ana of the response of the hull plates above the propeller. For a cavitating propeller the source strength is primarily determined by the volume variation of the cavity on each propeller blade. The cavitation volume can be calculated as function of the propeller geometry, propeller rpm and wake field. Provided the cavitation volume can be considered as being a monopole source the resulting source strength can be calculated as function of frequency.

Based on a simple plate theory the response of the hull plates can be predicted as function of the source strength of the propeller; or rather the incident pressure on the hull plates.

Predicted results of source strength and plate response are compared to full scale measurements. A few methods of how to reduce the power induced in the hull plates are discussed.
An Integral Prediction Method for Three-Dimensional Turbulent Boundary Layers on Rotating Blades
Authors: Groves Nancy C.
Published: December 2022

A general formulation of the boundary-layer computation scheme on the surface of a rotating blade is presented. Momentum-integral methods, together with the three-dimensional entrainment equation for a rotating disk, are used to calculate the three-dimensional turbulent boundary layer in an orthogonal streamline coordinate system: First-order. finite-difference methods are used to solve the resulting boundary-layer equations. The unknown variables are the streamwise momentum thickness, the shape parameter, and the streamline slope at the-surface. The boundary-layer calculation method is combined with existing geometrical and inviscid potential-flow computer codes for rotating blades to form an efficient turbulent boundary-layer computer code. For a given potential-flow solution, a typical boundary-layer computation requires less than 10 seconds computer time on the Burroughs 7700 high-speed computer. Boundary-layer predictions are presented for several rotating blades. Computed results are shown to be in agreement with experimental data for a simple rotating body. For the examples considered, displacement of the mid-chord point of a blade from a straight radial line is predicted to reduce the computed values of local skin friction coefficient, with an estimated increase in overall efficiency of about one percentage point.
Unravelling Humanitarian Narratives
Authors: Lokot Michelle
Published: December 2022

International humanitarian actors, such as non-governmental organisations (NGOs)
and United Nations agencies, often focus on gender norm change when conducting
gender analysis among refugees and internally displaced persons. Dominant
humanitarian narratives about gender in research reports, assessments and
technical guidance reveal an underlying belief that displacement is causative
– an external, intervening force. In such analysis, colonial and
neoliberal ideologies may influence how refugees’ lives are represented,
resulting in depictions of lack of modernity, tradition and culture as
overarching (yet ill-defined) forces, and women and girls as vulnerable by
default. Such analysis is frequently ahistorical, presented without analysis of
the pre-displacement situation. This paper explores and challenges humanitarian
narratives about gender norm change during displacement. It is based on feminist
ethnographic research in Jordan with Syrian women and men as well as interviews
with humanitarian workers. The paper demonstrates that assumptions about lack of
empowerment of Syrian women and men may be misguided, identifying both subtle
and more overt forms of Syrian women’s and men’s
resistance’ to expected norms. It urges humanitarian actors to use
‘resistance’ as an alternative to analysing
‘change’, recognise heterogeneity within populations, resist
‘rapid’ data collection, challenge paternalistic and colonial
stereotypes, and reflect complexity in analysis.
A Vehicle-Based Laser System for High-Resolution DEM Development – Performance Evaluation of System Components.
Authors:   Department of Biological and Agriculture Engineering, Kansas State University, Manhattan, Kansas, USA, Li Peng , Zhang Naiqian ,   Department of Biological and Agriculture Engineering, Kansas State University, Manhattan, Kansas, USA, Wagner Larry ,   USDA-Agricultural Research Service, Fort Collins, Colorado USA, Fox Fred ,   USDA-Agricultural Research Service, Fort Collins, Colorado USA, Oard Darrell ,   Department of Biological and Agriculture Engineering, Kansas State University, Manhattan, Kansas, USA, Lagae Hubert ,   USDA-Agricultural Research Service, Manhattan, Kansas USA, Han MIngqiang ,   Department of Biological and Agriculture Engineering, Kansas State University, Manhattan, Kansas, USA
Published: December 2022

Surface microtopography is quantified by the deviations in the direction of the normal vector of the surface. Soil microtopography is a major factor influencing soil erosion by water and wind. Surface microtopography can be accurately described using the Digital Elevation Model (DEM). In this study, a vehicle-based laser system was developed to generate high-resolution DEM data. The system consisted of five major components: a laser line scanner, a gyroscope sensor, a real-time kinematic GPS, a frame-rail mechanism, and a data acquisition and control unit. A series of experiments were conducted in the laboratory to evaluate the performance of the components. The result of distance measurements indicated that the system gave the most consistent distance measurement on a white paper. Static gyroscope sensor accuracy tests showed that angle measurement errors observed in combined pitch/roll rotations were larger than in single rotations. Within ±30º of single rotations, the measurement errors for pitch and roll angles were within 0.8º and 0.4º, respectively. The tests of the angular displacement on the linear rail showed that it slightly tilted towards the laser line scanner when it moved along the rail.
Escrevam porque as ditaduras não duram para sempre
Authors: Félix Loiva Otero , Silveira Daniela Oliveira
Published: December 2022

Obra que enfoca o período da ditadura civil-militar, inaugurado com outro golpe de Estado em 1964, a partir da trajetória de uma bravíssima mulher de lutas e realizações. Esta edição, além do novo prefácio e de uma revisão geral, conta com capítulo que discute as alterações histórica pelas quais o Brasil passou desde o fim dos governos Fernando Henrique Cardoso até o contexto atual.
Microstructure study of YBa2Cu3O7-δ thin film with synchrotron-based three-dimensional reciprocal space mapping
Authors: Yi Qi-Ru , Xiong Pei-Yu , Wang Huan-Hua , Li Gang , Wang Yun-Kai , Dong En-Yang , Chen Yu , Shen Zhi-Bang , Wu Yun , Yuan Jie , Jin Kui , Gao Chen ,   School of Physical Sciences, University of Chinese Academy of Science, Beijing 101408, China,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China,   Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
Published: December 2022

High-temperature superconducting films can be used for fabricating the cutting-edge high-temperature superconducting microwave devices because of their low microwave surface resistances. However, the microwave surface resistances of high-temperature superconducting materials are particularly sensitive to microstructure due to their special two-dimensional superconducting mechanisms and extremely short superconducting coherence lengths. To investigate the correlations between microstructure and microwave surface resistance of high-temperature superconducting materials, YBa2Cu3O7-δ (YBCO) films with different thickness are grown on (00l)-oriented MgO single-crystal substrates by using the pulsed laser deposition (PLD) technique. Electrical measurements reveal that their superconducting transition temperatures and room temperature resistances do not show significant difference. However, their microwave surface resistances in superconducting state display a significant difference. The characterizations of the microstructures of YBCO films by synchrotron radiation three-dimensional reciprocal space mapping(3D-RSM) technique show that the number of the grains with CuO2 face parallel to the surface (c crystals), and the consistency of grain orientation are the main causes for the difference in microwave surface resistance.
Lhx2 is a progenitor-intrinsic modulator of Sonic Hedgehog signaling during early retinal neurogenesis
Authors: Li Xiaodong , Gordon Patrick J , Gaynes John A , Fuller Alexandra W , Ringuette Randy , Santiago Clayton P , Wallace Valerie , Blackshaw Seth , Li Pulin , Levine Edward M
Published: December 2022

An important question in organogenesis is how tissue-specific transcription factors interact with signaling pathways. In some cases, transcription factors define the context for how signaling pathways elicit tissue- or cell-specific responses, and in others, they influence signaling through transcriptional regulation of signaling components or accessory factors. We previously showed that during optic vesicle patterning, the Lim-homeodomain transcription factor Lhx2 has a contextual role by linking the Sonic Hedgehog (Shh) pathway to downstream targets without regulating the pathway itself. Here, we show that during early retinal neurogenesis in mice, Lhx2 is a multilevel regulator of Shh signaling. Specifically, Lhx2 acts cell autonomously to control the expression of pathway genes required for efficient activation and maintenance of signaling in retinal progenitor cells. The Shh co-receptors Cdon and Gas1 are candidate direct targets of Lhx2 that mediate pathway activation, whereas Lhx2 directly or indirectly promotes the expression of other pathway components important for activation and sustained signaling. We also provide genetic evidence suggesting that Lhx2 has a contextual role by linking the Shh pathway to downstream targets. Through these interactions, Lhx2 establishes the competence for Shh signaling in retinal progenitors and the context for the pathway to promote early retinal neurogenesis. The temporally distinct interactions between Lhx2 and the Shh pathway in retinal development illustrate how transcription factors and signaling pathways adapt to meet stage-dependent requirements of tissue formation.
Uncertainty alters the balance between incremental learning and episodic memory
Authors: Nicholas Jonathan , Daw Nathaniel D , Shohamy Daphna
Published: December 2022

A key question in decision-making is how humans arbitrate between competing learning and memory systems to maximize reward. We address this question by probing the balance between the effects, on choice, of incremental trial-and-error learning versus episodic memories of individual events. Although a rich literature has studied incremental learning in isolation, the role of episodic memory in decision-making has only recently drawn focus, and little research disentangles their separate contributions. We hypothesized that the brain arbitrates rationally between these two systems, relying on each in circumstances to which it is most suited, as indicated by uncertainty. We tested this hypothesis by directly contrasting contributions of episodic and incremental influence to decisions, while manipulating the relative uncertainty of incremental learning using a well-established manipulation of reward volatility. Across two large, independent samples of young adults, participants traded these influences off rationally, depending more on episodic information when incremental summaries were more uncertain. These results support the proposal that the brain optimizes the balance between different forms of learning and memory according to their relative uncertainties and elucidate the circumstances under which episodic memory informs decisions.
M1 macrophage-derived extracellular vesicle containing tsRNA-5006c promotes osteogenic differentiation of aortic valve interstitial cells through regulating mitophagy
Authors: Xia Hao , Gao Mingjian , Chen Jun , Huang Guanshen , Xiang Xiuting , Wang Yuyan , Huang Zhaohui , Li Yongchun , Su Shuang , Zhao Zewei , Zeng Qingchun , Ruan Yunjun
Published: December 2022

Background

Osteogenic differentiation of aortic valve interstitial cells (AVICs) plays a key role in the calcific aortic valve disease progression. Extracellular vesicles (EVs)-derived from M1-polarized macrophages (M1-EVs) orchestrated intercellular communication by delivering non-coding RNAs such as tRNA-derived small RNAs (tsRNAs) is crucial for cardiovascular disease. However, the role and mechanism of M1-EVs tsRNAs in osteogenic differentiation of AVICs remains largely unclear.

Methods

M1-EVs and PBS treated-RAW 264.7 cell-derived EVs (NC-EVs) were incubated with AVICs and subjected to small RNA sequencing. Candidate tsRNA in M1-EVs was silenced to explore their effects on AVIC osteogenic differentiation and mitophagy.

Results

DiI-labeled M1-EVs were internalized by AVICs, resulting in significantly increased calcium nodule formation and expression of osteogenesis-related genes in AVICs, including RUNX2, BMP2, osteopontin, and SPP1, compared with NC-EVs. Small RNA sequencing revealed that 17 tsRNAs were significantly up-regulated such as tsRNA-5006c, while 28 tsRNAs were significantly down-regulated in M1-EVs compared with NC-EVs. Intriguingly, tsRNA-5006c-deleted M1-EVs treatment significantly reduced calcium nodule formation and expression of osteogenesis-related genes in AVICs relative to control group. Moreover, target genes of tsRNA-5006c were mainly involved in autophagy-related signaling pathways, such as MAPK, Ras, Wnt, and Hippo signaling pathway. Hallmarks of mitophagy activation in AVICs including mitophagosome formation, TMRM fluorescence, expression of LC3-II, BINP3, and PGC1α, were significantly elevated in the M1-EVs group compared with NC-EVs group, whereas M1-EVs tsRNA-5006c inhibitor led to a significant reduction in these indicators.

Conclusion

M1-EVs carried tsRNA-5006c regulates AVIC osteogenic differentiation from the perspective of mitophagy, and we provide a new target for the prevention and treatment of aortic valve calcification.
O impacto das competências humanas nas lideranças de equipes comerciais de pequenas e médias empresas voltadas para o agronegócio
Authors: Silvestre Marcos Antonio , Carrer Celso da Costa , Andrade Herlandí de Souza
Published: December 2022

Este é um projeto de pesquisa-ação em um estudo de caso com uma empresa do segmento de alimentos, que tem procurado sensibilizar, desenvolver e dar suporte ao importante papel das lideranças nas suas áreas comerciais distribuídas pelo Brasil, bem como conscientizá-las sobre o seu forte compromisso com o ambiente de negócio. Ambiente este que se apresenta em constante transformação e fortemente acelerado pela era digital, com soluções tecnológicas que avançam exponencialmente, na tentativa de tornar as empresas mais competitivas. De fato, esse ambiente sempre exigirá novas propostas, novas soluções para gerirmos times e organizações que concorrem num cenário caótico, onde se apresentam o vulnerável, o incerto, o complexo e o ambíguo, que exige destes líderes o exercício da resiliência, quiçá da antifragilidade, para lidar com toda essa imprevisibilidade.
Impactos da implantação da Lei Geral de proteção de dados pessoais no brasil: uma análise bibliométrica
Authors: Carvalho Hannibal Escobar Ramos Henriques de , Freitag Alberto Eduardo Besser , Santos Daiane Rodrigues dos
Published: December 2022

Com a criação da Lei Geral de Proteção de Dados Pessoais (LGPD) em 2018 e vigência a partir de agosto de 2020, a privacidade no Brasil começou a ser regulamentada. As organizações que atuam no Brasil, nacionais e internacionais, para evitar sanções regulatórias e impulsionar o crescimento de clientes, precisam adotar as melhores práticas para desenvolver e manter um programa eficaz de gerenciamento de privacidade e proteção de dados e assim evitar as penalizações e multas previstas. O tema é bastante atual no Brasil por tratar principalmente de questões de privacidade e utilização de dados pessoais para fins específicos. Hoje, a proteção de dados é um direito fundamental do cidadão. Visto o impacto e a importância da nova lei no Brasil, este artigo busca analisar publicações acadêmicas para apresentar um panorama atual. A metodologia aplicada foi uma análise bibliométrica, avaliando as produções científicas presentes nas bases Scopus, Web of Science, SciELO e Portal de Periódicos Capes. As palavras chaves utilizadas foram “LGPD”, “LGPDP” e “Lei Geral de Proteção de Dados” e o principal critério de pesquisa foi considerar publicações revisadas por pares. Os resultados obtidos mostraram que apesar de recente, o tema já é destaque na literatura acadêmica, com 91 publicações de 235 autores identificados em 61 periódicos científicos, abordando principalmente as áreas do direito, tecnologia e saúde.
Improved estimates for individual and population-level alcohol use in the United States, 1984-2020
Authors: Buckley Charlotte , Brennan Alan , Kerr William , Probst Charlotte , Puka Klajdi , Purshouse Robin , Rehm Jürgen
Published: December 2022

Aims:

While nationally representative alcohol surveys are a mainstay of public health monitoring, they underestimate consumption at the population level. This paper demonstrates how to adjust individual-level survey data using aggregated alcohol per capita (APC) data for improved individual- and population-level consumption estimates.

Design and methods:

For the period 1984-2020 data on self-reported alcohol consumption in the past 30 days were taken from the Behavioral Risk Factor Surveillance System (BRFSS) involving participants (18+ years) in the US. Monthly abstainers were re-allocated into lifetime abstainers, former drinkers and 12-month drinkers using the 2005 National Alcohol Survey data.  To correct for under-coverage of alcohol use, we triangulated APC and survey data by upshifting quantity (average grams/ day) and frequency (drinking days/week) of alcohol use based on national and state-level alcohol per capita data.

Findings

The corrections described above resulted in better correspondence between survey and APC data. Following our procedure, national estimates of alcohol quantity increased from 45% to 77% of APC estimates. Both quantity and frequency of alcohol use were upshifted; by upshifting to 90% of APC, we were able to fit trends and distributions in APC patterns for individual states and the US.

Conclusions:

An individual-level dataset which more accurately reflects the alcohol use of US citizens was achieved. This dataset will be invaluable as a research tool and for the planning and evaluation of alcohol control policies for the US. The methodology described can also be used to adjust individual-level alcohol survey data in other geographical settings.
Phytochemical Screening and Antimicrobial Potential of Halodule pinifolia
Authors: Mary S. Jenita Gnana , Bharathidasan R. , Ramamurthy V.
Published: December 2022

The study evaluate the phytochemical and antimicrobial potential of different extract of Halodule pinifolia. There are many potential groups of seagrass species that produce a variety of secondary metabolites. The seagrass species Halodule pinifolia, which is frequently found along the Thanjavur coastal area, was chosen for its bioactive potential. The agar diffusion method was used to test the seagrass extract's resistance to E. coli, B. subtilis, A. niger, and C. albicans. A aqueous seagrass extract was phytochemically screened and found to contain reducing sugars, alkaloids, saponins, phenolic compounds, flavonoids, and carbohydrates. According to the study's findings, the plant under study has broad-spectrum antimicrobial properties and may be an effective antioxidant for biological systems that are vulnerable to free radical-mediated reactions.
Study on the Valorization of Used Waste Oils as Fuel for the Firing of Clay Bricks in an Artisanal Kiln
Authors: Samah Ouro-Djobo Essoavana , N’wuitcha Kokou , Kongnine Damgou Mani , Kassegne Komlan Assogba
Published: December 2022

Used engine oil is a main source of oil contamination of waterways and can result in pollution of drinking water sources. Insoluble, persistent, slowly dergradable, it can contain toxic chemicals and heavy metals. Animals and birds from the polluted oil soil can be stuck. The present study aims to contribute to solving the environmental problem and energy saving purpose by recovering waste from the recycling of used oil to improve the firing of clay bricks. The waste from recycling used oil is collected and mixed with wood charcoal. This mixture is used as fuel in the artisanal kiln to fire the bricks. The temperature rises in the kiln, the cooling time and the quality of baked Clay Bricks are analyzed. The maximum temperature observed inside the kiln is 900°C in 36 hours of kiln operation when wood charcoal is used as fuel with a firing time of five (5) days and 1020°C in 80 hours when wood charcoal and “Chinese coal” (waste from the recycling of used oil) are used as fuel with a firing time of ten (10) days. This explains the longer cooling time than with wood charcoal alone as fuel. The firing of the bricks is perfect with both fuels, whereas, with wood charcoal alone as fuel, 15% of the bricks are unbaked. The bricks also have a very clean appearance. They have an average shrinkage of 1%, which is lower than the normative value of 3%, the average compressive strength is 16.5MPa which is higher than the normative value of 12.5MPa, and the water absorption is 40% which is lower than the normative value of 60%.

This combination of fuels reduces the use of wood charcoal, which in turn reduces deforestation and prevents air pollution and soil degradation through the dumping of waste oil in the environment.
Maintaining Efficiency and High Standards in A New Work Environment
Authors: Basko Lynn ,   Grand Canyon University
Published: December 2022

Since the COVID lockdown era, many faculty members have faced a change in a work situation, either changing working environments, changing modalities, or both. These changes can lead to stress and struggles with efficiency and maintaining high standards for students and self. This article describes research-based strategies I used throughout this experience to reduce stress and increase efficiency. I discovered these strategies through reflective practice and a literature review to support the ideas. Andragogy and the educational ergonomics model were used as theoretical foundations. These strategies included reflective practice, goal setting, creating a schedule, and staying connected with colleagues. This article describes how to implement these strategies to increase effectiveness and allow faculty members to focus their time on maintaining high standards for their students and their own work.
Molecular cloning of a novel C or γ type chemokine, SCM‐1
Authors: Yoshida Tetsuya , Imai Toshio , Kakizaki Mayumi , Nishimura Miyuki , Yoshie Osamu
Published: July 2002

From human PBMC stimulated with PHA, we have isolated cDNA clones encoding a novel cytokine named SCM‐1, which is significantly related to the CC and the CXC chemokines but has only the 2nd and the 4th of the four cysteines conserved in these proteins. Its gene is also distinctly mapped to human chromosome 1. SCM‐1 is strongly induced in human PBMC and Jurkat T cells by PHA stimulation. Among various human tissues, SCM‐1 is expressed most strongly in spleen. SCM‐1 is found to be 60.5% identical to lymphotactin, a recently described murine lymphocyte‐specific chemokine, which also retains only two cysteines. SCM‐1 and lymphotactin may thus represent the human and murine prototypes of a novel C or γ type chemokine family.
Cross‐linking of galectin 3, a galactose‐binding protein of mammalian cells, by tissue‐type transglutaminase
Authors: Mehul Bruno , Bawumia Sulemana , Colin Hughes R
Published: July 2002

The 30 kDa β‐galactoside‐binding protein of baby hamster kidney (BHK) cells [Mehul et al. (1994), J. Biol. Chem. 269, 18250–18258] homologous to galectin 3, a widely distributed mammlian lectin, has been found to be a substrate for tissue type transglutaminase, as shown by the incorporation in a calcium‐ and time‐dependent manner of 5‐(biotinamido) pentylamine in the presence of guinea pig liver transglutaminase. The amino‐terminal domain of hamster galectin 3, which is a repetitive sequence rich in glutamine, tyrosine, glycine and proline, is also an excellent substrate. A single lysine residue in the N‐terminal domain is an essential requirement for transglutaminase‐mediated oligomerization, and two equivalent glutamine residues present in identical sequence repeats within dhis domain appear to be involved as amine acceptors in cross‐linking reactions. Transglutaminase‐mediated cross‐linking of galectin 3 to itself or to matrix components may be one mechanism for stablisation of a multivalent binding form of the lectin in cell secretions or in extracellular matrices.
The pyruvate dehydrogenase complex of Saccharomyces cerevisiae is regulated by phosphorylation
Authors: James A.Gordon , Cook Ritchard M. , West Shauna M. , Lindsay J.Gordon
Published: July 2002

Mitochondria were isolated from Saccharomyces cerevisiae grown on different carbon sources prior to incubation with [γ‐32P]ATP. A major 46,000‐Mr phosphoprotein, corresponding in Mr value to the El α subunit of the yeast pyruvate dehydrogenase complex (PDC), was detected only in mitochondria isolated from cells grown on a fermentable carbon source such as galactose. Immunoprecipitation with subunit‐specific antiserum to the E1 component of mammalian or yeast PDC confirmed the identity of this polypeptide. PDC activity in isolated yeast mitochondria could be inactivated in an ATP‐dependent fashion and reactivated in the presence of Ca2+ ions.
Separation of Large Circular DNA by Electrophoresis in Agarose Gels
Authors: Cole Kenneth D. , Tellez Carlos M.
Published: July 2002

The electrophoresis of circular DNA, ranging in size from 4.4 kilobase pairs (kbp) to 220 kbp, was studied in agarose gels. Bacterial artificial chromosome (BAC) DNA was used as a source of large supercoiled and open circular (relaxed) forms. The open circles above approximately 50 kbp were trapped at the sample wells of 1% agarose gels during electrophoresis at 3 V/cm. Field inversion gel electrophoresis (FIGE) was used to relieve the trapping of the open circles in the gels. Using FIGE (30 s forward pulse time), open circles with sizes of 115 and 220 kbp required reverse pulse times of 3 and 6 s, respectively, to free the circles from open‐ended gel fibers. A minimum in the gel velocity of the open circles was measured at approximately 20 kbp. Open circles below approximately 20 kbp migrated slower than the supercoiled forms, and above 20 kbp the order was reversed. These results indicate that when the size of the open circles exceeded the average pore size of a gel and it was forced to span multiple pores, the open circles gained a mobility advantage. Decreasing the ionic strength of the electrophoresis buffer significantly decreased the mobility of the smaller circles and slightly increased the mobility of the larger circles.
Synthesis of a mordenite/ZSM-5/chabazite hydrophilic membrane on a tubular support. Application to the separation of a water–propanol mixture
Authors: A. Salomón Miguel , Coronas Joaquín , Menéndez Miguel , Santamaría Jesús
Published: July 2002

A selectivity of 71 is achieved in the separation of a gas phase water–propanol mixture, using a mordenite/ZSM-5/chabazite membrane that is hydrothermally synthesized onto the inner surface of a porous α-alumina tubular support.
Effects of surface treatments on Schottky barrier formation at metal/n-type CdTe contacts
Authors: Dharmadasa I. M. , Thornton J. M. , Williams R. H.
Published: July 2002

The nature of n-CdTe surfaces prepared by various chemical treatments has been studied by x-ray photoelectron spectroscopy. In parallel experiments Schottky barrier heights have been measured for Sb and Au contacts deposited on surfaces prepared in an identical manner. Reducing etches are found to leave the surface rich in Cd, and for these surfaces Sb and Au always produce barrier heights of 0.93±0.02 eV. Bromine in methanol solutions leaves the surface rich in Te and gives rise to two valued barrier heights of 0.93 and 0.72 eV. It is found that the probability of generating contacts with the higher value of barrier height increases as the surface becomes richer in Cd.
Theoretical gain in strained InGaAs/AlGaAs quantum wells including valence-band mixing effects
Authors: Corzine S. W. , Yan R. H. , Coldren L. A.
Published: July 2002

In this letter, we present the first detailed theoretical study of gain in strained InGaAs/AlGaAs quantum wells, taking into account the complex nature of the valence-subband structure, which must be included in any realistic model. We first compare the material gain as a function of carrier and radiative current density for a strained and unstrained quantum well. We then present calculations of theoretical differential gain, carrier density, and radiative current density at transparency as a function of indium mole fraction in the well.  
Joining of high current bulk Y-Ba-Cu-O superconductors
Authors: Salama K. , Selvamanickam V.
Published: July 2002

A new fabrication method which makes it possible to enlarge the size of small, but high quality, grain-aligned superconductors has been developed. This method involves solid state joining of high current density bulk YBa2Cu3Ox samples prepared by melt-processing. The joined samples exhibit superconductivity above 90 K and are found to be capable of carrying currents in excess of 150 A at 77 K. The interface of the joined samples is found to sustain current densities (Jc) in excess of 6000 A/cm2 at zero field and in excess of 4000 A/cm2 at 1.5 T. Also, the magnetic field dependence of Jc of the joined samples is similar to that of the individual samples. Since this joining method is not limited by the size of the superconductors that can be joined, the favorable transport and magnetic properties render this process suitable for applications requiring high temperature superconductors in bulk forms.
Surface analysis of a GaAs electron source using Rutherford backscattering spectroscopy
Authors: Calabrese R. , Guidi V. , Lenisa P. , Maciga B. , Ciullo G. , Della Mea G. , Egeni G. P. , Lamanna G. , Rigato V. , Rudello V. , Yang B. , Zandolin S. , Tecchio L.
Published: July 2002

We experimented with Rutherford backscattering spectroscopy to measure the amount of cesium on the surface of a GaAs photocathode activated in negative electron affinity (NEA) conditions. The surface analysis was performed both immediately after activation of the source in NEA condition and also some time after its total spoiling. Results showed that cesium did not desorb from the GaAs surface. With any further cesium feeding to reactivate the surface, the cesium accumulated on the surface until a saturation level was reached.
Ultralow-load hardness tester for use in a scanning electron microscope
Authors: Bangert H. , Wagendristel A.
Published: July 2002

A new ultramicrohardness tester for a load range between 2×10−2 and 5×10−5 N is described. The instrument is operated inside a scanning electron microscope. Load is applied and measured by means of electrical signals thus making fully automized experiments possible. Typical examples demonstrate the capability of the device and the general problem associated with ultra-low-load hardness testing. With experiments on thin films the complex situation for testing layered structures is shown and suggestions for a proper evaluation are given.
Apparatus for measuring elastic constants of single crystals by a resonance technique up to 1825 K
Authors: Goto Takayasu , Anderson Orson L.
Published: July 2002

By holding the rectangular parallelepiped specimen between long, thin alumina buffer rods, we can detect the resonance vibration of a specimen even at temperatures above 1800 K. This new technique, in combination with the theory for the calculation of the resonance frequency spectrum of a rectangular parallelepiped specimen, enables us to determine the high-temperature elastic properties of single-crystal materials. The first application of this new device was to determine the elastic stiffness constants of single-crystal corundum up to 1825 K.
X-ray mammography with synchrotron radiation
Authors: Burattini E. , Gambaccini M. , Marziani M. , Rimondi O. , Indovina P. L. , Pocek M. , Simonetti G. , Benassi M. , Tirelli C. , Passariello R.
Published: July 2002

For the first time in the literature, radiographs of breast phantoms were obtained using several monochromatic synchrotron radiation x-ray beams of selected energy in the range from 14 to 26 keV. In addition, after optimization of the photon energy as a function of the phantom thickness, several mammographs were obtained on surgically removed human breast specimens containing cancer nodules. Comparison between radiographs using a conventional x-ray unit and those obtained of the same specimens utilizing synchrotron monochromatic beams clearly shows that higher contrast and better resolution can be achieved with synchrotron radiation. These results demonstrate the possibility of obtaining radiographs of excised human breast tissue containing a greater amount of radiological information using synchrotron radiation.
A new technique for visualization of acoustic particle agglomeration
Authors: Hoffmann Thomas L. , Koopmann Gary H.
Published: July 2002

A new visualization technique is presented for microscopic particle trajectories displaying interaction and agglomeration phenomena in a high intensity acoustic field. The experiments are carried out in a small-scale observation chamber using a CCD camera in conjunction with a high resolution video system. A homogeneous acoustic velocity field is generated by two square, flat-membrane loudspeakers which comprise two opposing walls in the observation chamber. Glass microspheres (diameters 8.1 and 22.1 μm) and arbitrarily shaped quartz particles (diameter<50 μm) are used for the observation of interaction and agglomeration trajectories under the influence of an intense acoustic velocity field (1.2–0.53 m/s @400–900 Hz). The new technique allows the observation of the particles’ general motion as well as acoustically induced oscillations. The direction of propagation of a particle can be extracted by following its trajectory in a 2D laser lightsheet. Image processing of the digitized data allows the reconstruction of particle trajectories for time spans up to 0.5 s. From the images, the particle size can be estimated based on measurements of the acoustic entrainment factor. Most importantly, with the new experimental technique it is possible to resolve particle interaction and agglomeration processes caused by the acoustic field. The recorded digitized images show a number of different interaction phenomena as well as one distinct pattern that resembles the shape of a tuning fork (thus called the tuning fork agglomeration). The latter appears to be the predominant agglomeration mechanism leading to rapid particle approach and multiple, subsequent particle interactions at high frequencies and large acoustic velocities.
Diagnostic neutral beam and active spectroscopy requirements for the Alcator C-Mod tokamak (invited)
Authors: Marmar E. S. , Terry J. L. , Rowan W. L. , Wootton A. J.
Published: July 2002

Considerations are presented on the application of a diagnostic neutral beam to the Alcator C-Mod tokamak for active profile measurements of ion temperature, poloidal and toroidal rotation, impurity and minority species densities, and internal magnetic field. Calculations indicate that, for a typical 50 keV, 0.13 MW hydrogen beam, charge exchange recombination measurements for plasmas with line average densities up to 2.5×1020 m−3 will yield, with good signal-to-noise ratio and ∼1 cm spatial resolution, measurements of helium and low Z impurity density profiles with better than 1 ms time resolution, and ion temperature and rotation profiles with ∼1 ms time resolution. Motional Stark effect (MSE) measurements appear feasible over most of the operating density range of the device (at least up to 5×1020 m−3), also with ms time resolution. Spatial resolution of the MSE measurements will depend on the toroidal width of the beam and the angle of the view with respect to the beam; for a 5 cm wide beam with a 60° viewing angle, 2.5 cm spatial resolution is expected.
Stroboscopic microcontroller-based tachometer
Authors: Segovia Armando , Garduño Mayra , Longoria Luis C. , Diaz Arquimides
Published: July 2002

A noncontact tachometer capable of measuring rotational speeds up to 10 000 revolutions per minute using a small microcontroller (μC). The microcontroller contributes most of the electronics required for the tachometer, and simplifies the design substantially. The electronic design uses only commercial components, and the facilities provided by the μC lead to a simple and inexpensive appliance.
Quick measurement of nuclear magnetic resonance coil sensitivity with a single-loop probe
Authors: Ginefri Jean-Christophe , Durand Emmanuel , Darrasse Luc
Published: July 2002

The coil sensitivity for nuclear magnetic resonance (NMR) signal detection can be defined as B1/P, which represents the magnetic field that the coil induces per unit supplied power. An inductive probe was previously proposed to quickly evaluate the sensitivity of a tuned NMR coil. As this probe uses two loops, decoupled by means of a slight overlapping, it is not applicable to small NMR coils since the decoupling efficiency is limited by the loop dimensions. We present a new method, derived from the former, which uses a single-loop probe and allows accurate sensitivity mapping even for very small NMR coils. This new method proves to be in good agreement with both the theoretical formula and a reference method for assessing a simple coil’s sensitivity. We conclude that it is both reliable and particularly convenient for development and optimization of small coils for surface MR imaging.
Spectromicroscopy beamline at ELETTRA: Performances achieved at the end of commissioning
Authors: Barbo F. , Bertolo M. , Bianco A. , Cautero G. , Fontana S. , Johal T. K. , La Rosa S. , Margaritondo G. , Kaznacheyev K.
Published: July 2002

In the course of 1998, the Spectromicroscopy beamline at ELETTRA completed commissioning and succeeded in performing its first test experiments. The beamline is designed to perform photoemission experiments with high spatial resolution, which is obtained by focusing the radiation in a small spot on the sample by means of a multilayer-coated Schwarzschild Objective. Three objectives are currently available; these operate at photon energies of 74, 95, and 110 eV. A review is presented of the performances achieved together with an outlook on the future upgrades of the microscope. The smallest achievable spot size is currently 0.5 μm. At present, the limit to the spatial resolution is due to aberrations caused by figure errors of the objective. Typical counting rates in photoemission spectra, for example, on the Au 5d peak, are of the order of 104–105 counts per second with an energy resolution of the order of 100–200 meV. Among the first experiments in which p- and n-type GaAs layers of 0.25 μm thickness were imaged.
Structurally relaxed models of the Si(001)–SiO2 interface
Authors: Pasquarello Alfredo , Hybertsen Mark S. , Car Roberto
Published: July 2002

We present a first-principles investigation of the structural properties of two models for the Si(001)–SiO2 interface. The models derive from attaching tridymite, a crystalline form of SiO2, to Si(001), and then allowing for full relaxation. These models do not show electronic states in the silicon gap, as required by electrical experiments. They contain the three intermediate oxidation states of silicon, consistent with photoemission experiments. We study bond length and bond angle distributions and measures of local strain. The strain is localized to a transition region at the interface. Strain does not persist in the full oxide.
Defects and degradation in ZnO varistor
Authors: Lee Wei-I , Young Ruey-Ling
Published: July 2002

A systematic study of the defects in ZnO has been performed. The two commonly observed levels (L1, L2), located at around 0.15 and 0.24 eV under the conduction band, have been identified as native defects. The deep level transient spectroscopy depth profiling technique is applied on multilayer-chip-type ZnO varistors to determine the distribution profiles of these two levels. With higher densities near the grain boundary, L2 is unlikely to be zinc interstitials as some previous studies have assigned. Both L1 and L2 show no apparent correlation with the device degradation process. Instead, a complex defect or interface trap, related to impurities in the starting material, exhibits a much stronger correlation with the ZnO varistor’s stability.
Direct observation of the initial nucleation and epitaxial growth of metastable cubic GaN on (001) GaAs
Authors: Trampert A. , Brandt O. , Yang H. , Ploog K. H.
Published: July 2002

We report on the direct observation of the initial nucleation and the resulting microstructure of GaN deposited on GaAs(001) by plasma-assisted molecular beam epitaxy. Using high-resolution transmission electron microscopy, we demonstrate that, despite the extreme lattice mismatch between these two materials, GaN nucleates in the metastable cubic phase with a well-defined orientation relationship to the substrate and a sharp heteroboundary. The preference of the metastable phase in the initial stage of growth is discussed in connection with a coincidence lattice for the epitaxy-induced interface structure of the initial GaN nuclei.
Magnetoresistive sensor for weak magnetic fields
Authors: Moran Timothy J. , Dahlberg E. Dan
Published: July 2002

A new excitation technique is described for the measurement of weak magnetic fields (<0.01 Oe). The resistance variation of a magnetoresistive element due to an oscillating excitation field is converted into a voltage proportional to the environmental field. The excitation field amplitude is set large enough to saturate the magnetization during each half-cycle, greatly reducing hysteresis effects in the output signal. Both anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR) structures have been used to measure fields with sufficient accuracy for compass applications. Such devices could be made with extremely small dimensions and power requirements.
Extremely broadband AlGaAs/GaAs superluminescent diodes
Authors: Lin Ching-Fuh , Lee Bor-Lin
Published: July 2002

Extremely broadband AlGaAs/GaAs superluminescent diodes are fabricated on substrate with four quantum wells of different widths. By choosing 20, 33, 56, and 125 Å, respectively, for the four quantum wells, the spectrum could be broadened to several times that of the conventional superluminescent diodes. The measured spectra of the fabricated devices with such quantum-well structure show that the full-width at half-maximum spectral width could be as large as 915 Å.
Polarized electroluminescence from smectic mesophase
Authors: Tokuhisa Hiroaki , Era Masanao , Tsutsui Tetsuo
Published: July 2002

Electrically pumped light emission was observed from a smectic mesophase of liquid-crystalline oxadiazole; 2,5-hexyloxybiphenyl–hexyloxyphenyl–oxadiazole (HOBP-OXD), which exhibits high electron transport capability. The light-emitting diode consisted of the HOBP-OXD film, a copper phthalocyanine vacuum deposited film as a hole injection layer, and a tris-(8-hydroxyquinoline) aluminum vacuum deposited film as an electron injection layer. The emission was linearly polarized originating from highly oriented molecular textures in the smectic mesophase with a degree of orientational order of 0.32.