bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of vaginal erosion and vesicocutaneous fistula following midurethral transvaginal tape with PelviLace® for treatment of stress urinary incontinence
Authors: Cuzzone Daniel , Allen Brian , Rowin Craig , Tulikangas Paul , Babigian Alan
Published: March 2009

Stress urinary incontinence (SUI) is a common diagnosis that greatly impacts quality of life for many women. Current therapies implement the use of suburethral slings, either synthetic or xenografts, to remedy this condition. In this study, we report on a patient with SUI, treated with PelviLace® Biourethral Support, who suffered multiple issues postoperatively.
Protection against Radiation‐induced Testicular Damage in Swiss Albino Mice by Mentha piperita (Linn.)
Authors: Samarth Ravindra M. , Samarth Meenakshi
Published: March 2009

Abstract:  The protective effects of Mentha piperita leaf extract against radiation‐induced damage in testis of Swiss albino mice have been studied. Animals (Male Swiss albino mice) were given M. piperita leaf extract orally (1 g/kg body weight/day) for three consecutive days before radiation exposure (8 Gy γ‐radiation). Mice were autopsied at 1, 3, 7, 14, and 30 days after irradiation to evaluate the radiomodulatory effect in terms of histological alterations, lipid peroxidation, and acid and alkaline phosphatases levels in testis. Radiation treatment showed reduction in the testis weight during all days of observation, however, in the M. piperita leaf extract‐pretreated irradiated group there was a significant increase in testis weight. Radiation treatment induced moderate to severe testicular atrophy with degeneration of germ cells in seminiferous tubules. The tubules were shrunken and greatly depleted of germ cells. Sertoli cells with few germ cells were observed in the lumen. However, animals pre‐treated with M. piperita leaf extract and exposed to radiation showed normal testicular morphology with regular arrangement of germ cells and slight degeneration of seminiferous epithelium. Significant decreases in the lipid peroxidation and acid phosphatase level and increase in level of alkaline phosphatase were observed in testis. The M. piperita leaf extract showed high amount of phenolic content, flavonoids content and flavonols. The results of the present study suggest that M. piperita has a significant radioprotective effect and the amount of phenolic compounds, the content of flavonoids and flavonols of M. piperita leaf extract may be held responsible for radioprotective effect due to their antioxidant and radical scavenging activity.
3‐(3‐Ethylphenyl)‐2‐substituted hydrazino‐3H‐quinazolin‐4‐one Derivatives: New Class of Analgesic and Anti‐Inflammatory Agents
Authors: Alagarsamy V. , Raja Solomon V. , Sheorey R. V. , Jayakumar R.
Published: March 2009

A new series of 3‐(3‐ethylphenyl)‐2‐substituted hydrazino‐3H‐quinazolin‐4‐ones were synthesized by reacting the amino group of 2‐hydrazino‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one with a variety of aldehydes and ketones. The title compounds were investigated for analgesic, anti‐inflammatory and ulcerogenic index behavior. The compound 2‐(N′‐3‐pentylidene‐hydrazino)‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one (AS2) emerged as the most active compound in exhibiting analgesic activity and the compound 2‐(N′‐2‐pentylidene‐hydrazino)‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one (AS3) emerged as the most active compound in exhibiting anti‐inflammatory activity; and these compounds are moderately potent when compared with the reference standard diclofenac sodium. Interestingly, the test compounds showed only mild ulcerogenic potential when compared with aspirin.
No relationship between enzyme activity and structure of nucleotide binding site in sarcoplasmic reticulum Ca2+‐ATPase from short‐term stimulated rat muscle
Authors: Mishima T. , Kuratani M. , Kanzaki K. , Yamada T. , Matsunaga S. , Wada M.
Published: March 2009

Aim:  We examined whether structural alterations to the adenine nucleotide binding site (ANBS) within sarcoplasmic (endo) reticulum Ca2+‐ATPase (SERCA) would account for contraction‐induced changes in the catalytic activity of the enzyme as assessed in vitro.

Methods:  Repetitive contractions were induced in rat gastrocnemius by electrical nerve stimulation. Measurements of sarcoplasmic reticulum properties were performed on control and stimulated muscles immediately after or at 30 min after the cessation of 5‐min stimulation. In order to examine the properties at the ANBS, the binding capacity of SERCA to fluorescence isothiocyanate (FITC), a competitive inhibitor at the ANBS, was analysed in microsomes.

Results:  Short‐term electrical stimulation evoked a 23.9% and 32.6% decrease (P < 0.05) in SERCA activity and in the FITC binding capacity, respectively, in the superficial region of the muscle. Whereas SERCA activity reverted to normal levels during 30‐min recovery, a restoration of the FITC binding capacity did not occur.

Conclusion:  The discordant changes between the enzyme activity and the FITC binding suggest that, at least during recovery after exercise, changes in SERCA activity may not correlate closely with structural alterations to the ANBS within the enzyme.
Behavior of melon‐headed whales, Peponocephala electra, near oceanic islands
Authors: Brownell Jr. Robert L. , Ralls Katherine , Baumann‐Pickering Simone , Poole M. Michael
Published: March 2009

Abstract

Southall et al. (2006) concluded that a near mass stranding (MS) of melon‐headed whales (MHWs), Peponocephala electra, in Hanalei Bay, Kauai, Hawaii, on 3–4 July 2004, was likely related to the operation of mid‐frequency sonars (MFS). However, subsequent authors argued that the nearly simultaneous entry of MHWs into Sasanhaya Bay, Rota (∼5,740 km away) made this conclusion untenable. They suggested that both sightings, and other MSs of MHWs, could be related to lunar cycles. To resolve this question, we reviewed information on the biology and behavior of MHWs and compared the two sightings to observations of MHWs around Palmyra Atoll and Nuku Hiva, French Polynesia. We also tested for a relationship between observations and MSs of MHWs with lunar cycles. MHWs near many oceanic islands rest nearshore during the day and feed offshore in deeper water at night. The MHWs at Rota exhibited normal diurnal resting behavior as seen at Palmyra and Nuku Hiva, while those at Kauai showed milling behavior typically seen prior to MS events. Thus, these events were not similar. Neither observations nor MSs of MHWs were related to lunar cycles. Our review of MHW behavior strengthens the case that MFS use played a major role in the near MS in Hanalei Bay.
Thrombopoietin Is Essential for the Maintenance of Normal Hematopoiesis in Humans
Authors: BALLMAIER M. , GERMESHAUSEN M. , KRUKEMEIER S. , WELTE K.
Published: March 2009

Abstract: Recently, we and others could define the molecular cause of the rare disease congenital amegakaryocytic thrombocytopenia (CAMT) as mutations in the c‐mpl gene (Blood 97: 139, 2001). We proposed that c‐mpl mutations are the cause not only for the hypomegakaryocytic thrombocytopenia, but also for the development of an aplastic anemia (AA) in patients with CAMT. The effects of thrombopoietin (TPO) on early multipotent hematopoietic progenitors were elucidated by a recent series of in vitro and in vivo studies. Like CAMT patients, mice lacking the TPO receptor c‐Mpl demonstrate a major reduction of early hematopoietic progenitor cells of all lineages. However, these mice achieve a normal marrow cellularity and composition, despite the lack of megakaryocytes. On the other hand, the incidence of development of aplastic anemia in CAMT is not clear owing to difficult and not consistent diagnosis of this disease.
Telomeres in Hematopoietic Stem Cells
Authors: BAERLOCHER GABRIELA M. , RÖTH ALEXANDER , LANSDORP PETER M.
Published: March 2009

Abstract: Hematopoietic stem cells have an impressive regenerative potential, strikingly illustrated in transplantation experiments using limited number of cells. In mice, serial transplantation experiments suggest that individual hematopoietic cells are capable of extensive self‐renewal and that any possible limitations in the replicative potential of individual hematopoietic stem cells are not affecting normal blood cell formation. The situation with human hematopoietic stem cells is less clear. Unlike the situation in the mouse, the telomere length in nucleated human blood cells shows a remarkable decline with age. Furthermore, even partial telomerase deficiency in humans typically results in marrow failure, whereas complete lack of telomerase is tolerated up to several generations in the mouse. The decline in telomere length in human leukocytes with age follows a cubic function and is much higher in lymphocytes than in granulocytes. This finding suggests that, under normal circumstances, telomere loss is more likely to compromise the function of lymphocytes than the function of hematopoietic stem cells. To reconcile differences in telomere biology between man and mice, it has been proposed that telomere shortening evolved as a tumor suppressor mechanism in long‐lived species that may not exist in shorter‐lived mammals. According to this model, telomeres in human cells are intimately involved in signaling cell cycle progression and cell division. Most likely, a minimum number of telomere repeats is required at each telomere to prevent activation of a “telomere checkpoint” and allow cell cycle progression. Telomere length measurements appear useful to distinguish between depletion and exhaustion of hematopoietic stem cells as a cause of marrow failure.
Angiogenic Factors Reconstitute Hematopoiesis by Recruiting Stem Cells from Bone Marrow Microenvironment
Authors: RAFII SHAHIN , AVECILLA SCOTT , SHMELKOV SERGEY , SHIDO KOJI , TEJADA RAFAEL , MOORE MALCOLM A.S. , HEISSIG BEATE , HATTORI KOICHI
Published: March 2009

Abstract: The mechanism by which angiogenic factors recruit bone marrow (BM)‐derived quiescent endothelial and hematopoietic stem cells (HSCs) is not known. Here, we report that functional vascular endothelial growth factor receptor‐1 (VEGFR1, Flt‐1) is expressed on a subpopulation of human CD34+ and mouse Lin−Sca‐1+c‐Kit+ BM‐repopulating stem cells, conveying signals for recruitment of HSCs and reconstitution of hematopoiesis. Inhibition of VEGFR1 signaling, but not VEGFR2 (Flk‐1, KDR), blocked HSC cell cycling, differentiation and hematopoietic recovery after BM suppression, resulting in the demise of the treated mice. Plasma elevation of placental growth factor (PlGF), which signals through VEGFR1, but not VEGFR2, restored hematopoiesis during the early and late phases following BM suppression. The mechanism whereby PlGF enhanced early phases of BM recovery was mediated directly through rapid chemotaxis of readily available VEGFR1+ BM‐repopulating and progenitor cells. The late phase of hematopoietic recovery was driven by PlGF‐induced upregulation of matrix metalloproteinase‐9 (MMP‐9) in the BM, mediating the release of soluble Kit‐ligand (sKitL). sKitL increased proliferation and motility of HSCs and progenitor cells, thereby augmenting hematopoietic recovery. PlGF promotes recruitment of VEGFR1+ HSCs from a quiescent to a proliferative microenvironment within the BM, favoring differentiation, mobilization, and reconstitution of hematopoiesis.
Complement‐Fixing CD45 Monoclonal Antibodies to Facilitate Stem Cell Transplantation in Mouse and Man
Authors: BRENNER MALCOLM K. , WULF GERALD G. , RILL DONNA R. , LUO KANG‐LI , GOODELL MARGARET A. , MEI ZUYONG , KUEHNLE INGRID , BROWN MICHAEL P. , PULÉ MARTIN , HESLOP HELEN E. , KRANCE ROBERT A.
Published: March 2009

Abstract: Broadening the applicability of stem cell therapies requires safer preparative regimens for patients. The CD45 antigen is present on all cells of the hematopoietic lineage, and using a murine model, we determined whether a lytic CD45 monoclonal antibody could produce persistent aplasia and whether it could facilitate syngeneic or allogeneic stem cell engraftment. After its systemic administration, we found that all leukocyte subsets in peripheral blood were markedly diminished, but only the effect on the lymphoid compartment was sustained and marrow progenitor cells were spared from destruction. Given the transient effects of the monoclonal antibody on myelopoiesis and the more persistent effects on lymphopoiesis, we asked whether this agent could contribute to donor hemopoietic engraftment after subablative transplantation. Treatment with anti‐CD45 alone did not enhance syngeneic engraftment, consistent with its inability to destroy progenitor cells and permit competitive repopulation with syngeneic donor stem cells. By contrast, the combination of anti‐CD45 and an otherwise inactive dose of total‐body irradiation allowed engraftment of H2 fully allogeneic donor stem cells. We attribute this result to the recipient immunosuppression produced by depletion of CD45‐positive lymphocytes. We next assessed a pair of unconjugated rat anti‐human CD45 monoclonal antibodies (MAbs), YTH54.12 and YTH25.4, in a clinical trial in patients who were to receive stem cell transplantation for acute leukemia. The maximum tolerated dose of these MAbs, 400 μg/kg/day, produced a pattern of response identical to that seen in the mice, with marked reductions in circulating lymphoid and myeloid cells and sparing of early marrow progenitors. In two of three patients with active leukemia, the MAbs also produced a decrease in the percentage of leukemic blast cells in bone marrow. These pre‐clinical and clinical results warrant further evaluation of anti‐CD45 MAbs in subablative preparative regimens for stem cell transplantation.
From Embryos to Embryoid Bodies
Authors: DALEY GEORGE Q.
Published: March 2009

Abstract: Differentiation of embryonic stem (ES) cells in vitro yields abundant hematopoietic progenitors, but achieving stable hematopoietic engraftment of irradiated mice has proven difficult, begging the question of whether ES cells give rise to hematopoietic stem cells in vitro, and limiting the application of ES cells as experimental and therapeutic models. We have employed a number of hematopoietic regulatory genes to probe the nature and developmental potential of ES‐derived blood precursors. The chronic myeloid leukemia‐associated BCR/ABL oncoprotein transforms a novel class of ES‐derived embryonic hematopoietic stem cell that represents a common progenitor of primitive erythropoiesis and definitive lymphoid‐myeloid blood development. Expression of the homeobox gene HoxB4 generated normal, non‐leukemic hematopoietic progenitors that enabled long‐term, multilineage hematopoietic engraftment in primary and secondary mouse recipients. We have used these repopulating hematopoietic stem cells to model therapeutic transplantation from ES cells. We treated an immunodeficient Rag2−/− mouse by therapeutic cloning, that is, isogenic ES cell generation by somatic cell nuclear transfer, gene correction, and cell replacement therapy. Comparable approaches with human ES cells are being developed to lay the foundation for cellular therapies in patients with a variety of bone marrow diseases.
Transplanted Human Cord Blood Cells Give Rise to Hepatocytes in Engrafted Mice
Authors: ISHIKAWA FUMIHIKO , DRAKE CHRISTOPHER J. , YANG SU , FLEMING PAUL A. , MINAMIGUCHI HITOSHI , VISCONTI RICHARD P. , CROSBY CHRISTOPHER V. , ARGRAVES W. SCOTT , HARADA MINE , KEY L. LYNDON , LIVINGSTON ANNE G. , WINGARD JOHN R. , OGAWA MAKIO
Published: March 2009

Abstract: Recent studies suggest that rodent hepatocytes may be derived from hematopoietic stem cells. In the current study, the potential hematopoietic origin of hepatocytes was addressed using xenogeneic transplantation of human cord blood cells. CD34+ or CD45+ human cord blood cells were transplanted into “conditioned” newborn NOD/SCID/β2‐microglobulinnull mice. At 4 to 5 months post‐transplantation, livers of the recipient mice were cryosectioned and examined for evidence of human hepatocyte engraftment using RT‐PCR to detect human albumin mRNA, immunohistochemistry to detect human hepatocytic proteins, and fluorescence in situ hybridization (FISH) to detect the presence of human centromeric DNA. Analysis of the bone marrow of transplanted mice revealed that 21.0–45.9% of the cells were human CD45+ cells. FISH analysis of frozen sections of transplanted mouse liver revealed the presence of engrafted cells positive for human centromeric DNA. That engrafted human cells functioned as hepatocytes was indicated by the expression of human albumin mRNA, as judged by RT‐PCR. FISH analysis with human and mouse centromeric DNA probes excluded spontaneous cell fusion as the cause for the generation of human hepatocytes. Human cord blood cells can give rise to hepatocytes in a xenogeneic transplantation model. This model will be useful to further characterize the cord blood progenitors of hepatocytes.
Major Age‐Related Changes Of Mouse Hematopoietic Stem/Progenitor Cells
Authors: KIM MIJUNG , MOON HEE‐BOM , SPANGRUDE GERALD J.
Published: March 2009

Abstract: To study age‐related changes of mouse bone marrow (BM) cells and hematopoietic stem cells (HSCs), we isolated rhodamine‐123low (Rhlow) Thy1.1low Lin−Sca‐1+ (TLS) HSCs from the BM of old mice and compared their functional characteristics to cells of the same phenotype isolated from young mice. We observed impaired recovery of B lymphocytes and decreased self‐renewal in recipients of old Rhlow cells compared to young Rhlow cells. Blockade of Rh efflux using verapamil improved lymphoid reconstitution by enriched HSCs, and isolation of aged HSCs based on efflux of a fluorescent multi‐drug resistance (MDR) substrate (Bodipy‐verapamil) resulted in enrichment of HSC activity equivalent to that obtained with Rh. These observations suggest a complex relationship between MDR activity and HSC function during aging. To address whether the difference between young and aged donors was intrinsic to the HSC compartment or was due to a shift in HSC phenotype, we co‐transplanted normal BM derived from young or old donors and followed repopulation simultaneously in the same recipient animals. In a parallel experiment, we co‐transplanted HSCs purified from old donors with BM derived from young donors. In both experiments, transplants were given to both young and old recipients. The results show a clear defect in B‐cell engraftment from either BM or HSCs of old donors, irrespective of the age of the recipient. In contrast, myeloid engraftment was predominantly derived from BM or HSCs derived from aged donors, again irrespective of recipient age. These data suggest a stem cell basis for B‐cell immuno‐senescence and the increased incidence of myelocytic leukemia in elderly people.
Mesenchymal Stem Cells and Hematopoietic Stem Cell Transplantation
Authors: FIBBE WILLEM E. , NOORT WILLY A.
Published: March 2009

Abstract: Techniques have recently beome available to isolate and grow mesenchymal progenitors and to manipulate their growth under defined in vitro culture conditions. As a result mesenchymal stem cells can be rapidly expanded to numbers that are required for clinical application. This has allowed the clinical testing of culture‐expanded MSCs in the context of hematopoietic stem cell transplantation. In this paper we discuss the role of MSCs in hematopoietic engraftment after transplantation.
Temporal Annotation and Representation
Authors: Verhagen Marc , Moszkowicz Jessica L.
Published: March 2009

The goal of temporal annotation is to mark up all elements of a text that are relevant to the temporal interpretation of that text. As such, temporal annotation reveals part of the semantics of a text. We describe recent approaches to temporal annotation, focusing on the recently developed annotation language TimeML. In addition, we describe a couple of systems aimed at temporally parsing texts. We motivate the use of temporal annotation from a question answering viewpoint and describe some earlier insights from theoretical linguistics on what the temporal properties of language constructs are.
Isolation and characterization of microsatellites in the bird‐pollinated, autohexaploid, Eremophila glabra ssp. glabra (R.Br. (Ostenf.)) (Myoporaceae), an Australian endemic plant
Authors: ELLIOTT C. P.
Published: March 2009

Thirty‐eight microsatellite loci were developed for the bird pollinated, autohexaploid, Eremophila glabra ssp. glabra. A genomic library was screened with dinucleotide and trinucleotide sequence repeats. Polymorphism ranged from one to 21 alleles per locus. Twenty‐four loci exhibited null alleles, based on patterns of inheritance between maternal and progeny phenotypes. Cross‐species amplification of nine Eremophila species was successful for most primers, indicating wide applicability across the genus. These microsatellites will be used to study the gene flow patterns of fragmented populations of E. glabra ssp. glabra.
Cyanus triumfettii subsp. triumfettii (Compositae) does not occur in the western Carpathians and adjacent parts of Pannonia: karyological and morphological evidence
Authors: Olšavská Katarína , Perný Marián , Mártonfi Pavol , Hodálová Iva
Published: March 2009

The pronounced morphological variation of the Cyanus triumfettii group (syn. Centaurea triumfettii s. latissimo) in the western Carpathians and Pannonia has resulted in confusing and contradictory taxonomic treatments. We focus on the taxonomic identity of populations which have been treated as C. triumfettii subsp. triumfettii in this area. Karyological and morphological data were used to compare 47 populations (746 plants) from the western Carpatho–Pannonian area with 8 populations (105 plants) from the type locality of C. triumfettii subsp. triumfettii and its vicinity in the southern part of the western Alps. Chromosome counting and flow cytometry confirmed the diploid level for all analysed populations. Multivariate morphometric analyses revealed a clear separation between Alpine populations and populations in the western Carpathians and Pannonia. The results proved that C. triumfettii subsp. triumfettii does not occur in the western Carpathians and Pannonia. Instead, populations in this area are provisionally treated as C. triumfetti subsp. axillaris, C. triumfettii subsp. dominii and C. triumfettii subsp. strictus. The complex morphological variation of these subspecies is discussed and the need for further taxonomic studies is emphasized.
Pollen morphology of selected species of Allium (Alliaceae) distributed in Iran
Authors: Hosseinzadeh Namin Hooman , Saeidi Mehrvarz Shahryar , Zarre Shahin , Fritsch Reinhard
Published: March 2009

Pollen morphology of 19 species of Allium representing six subgenera and 12 sections, were studied. The following characters were recognized as important for separating taxa at different taxonomic ranks: the sulcus, presence or absence of perforations on the pollen surface, density of perforations, size of perforations and size of the pollen grains. Rugulate, rugulate–striate, and simple–perforate exine ornamentation were distinguished. The type of sulcus is very characteristic in A. subgen. Allium sect. Allium. The extended sulcus was not observed in any species the other sections of subgen. Allium studied here, such as sect. Caerulea (A.capitellatum), sect. Codonprasum (A.lenkoranicum and A.stamineum) and sect. Avulsea (A.rubellum and A.umblicatum). Imperforated pollen grains were observed in representatives of A. subgen. Reticulatobulbosa and subgen. Polyprason.
Carex qingliangensis sp. nov. (Cyperaceae) from Zhejiang, eastern China
Authors: Weng Dong‐Ming , Zhang Hong‐Wei , Xu Shui‐Feng , Jin Xiao‐Feng
Published: March 2009

Carex qingliangensis D. M. Weng, H. W. Zhang & S. F. Xu, a new species of the Cyperaceae from Zhejiang, China, is described with illustrations. The new species is morphologically similar to C. dolichostachya Hayata and C. tianmushanica C. Z. Zheng & X. F. Jin, but differs from the former in having perigynia sparsely pubescent and achenes constricted into a short neck at apex. It differs from the latter in having achenes not contracted in the middle part.
Establishing the Sri Lanka Clinical Trials Registry
Authors: Ranawaka Udaya K , Goonaratna Colvin
Published: March 2009

Recognizing the need for a national body for trial registration, the Sri Lanka Medical Association took up the challenge of setting up the Sri Lanka Clinical Trials Registry. The registry was established in November 2006, the first functioning trial registry in South Asia. The Sri Lanka Clinical Trials Registry is now a primary registry affiliated to the Registry Network of the International Clinical Trials Registry Platform of the World Health Organization. The Sri Lanka Clinical Trials Registry has not been a mere repository for trial data but has also had a positive influence on the research community in Sri Lanka.
Meta‐analysis of randomized trials for health care interventions: one for all?
Authors: Sun Xin , Guyatt Gordon
Published: March 2009

Meta‐analysis of randomized trials stands at the top of the epidemiological designs to test the effect of health care interventions. Ideally, it systematically and comprehensively collects the relevant randomized trials, and pools the trials to generate a single estimate of effects. However, the rationale for meta‐analysis may not always be thoughtfully considered, and overlooking underlying principles may cause illusions. This article revisits the rationale for meta‐analysis, discusses how meta‐analysis can be misleading, and summarizes approaches to critically and judiciously interpret and use the results of meta‐analysis.
Background, introduction and activity of the Japan Primary Registries Network
Authors: Shiokawa Tomonori
Published: March 2009

Regarding registration and publication of clinical trials, there are now three registry organizations in Japan; the University Hospital Medical Information Network (UMIN), the Japan Pharmaceutical Information Center (JAPIC) and the Japan Medical Association – Center for Clinical Trials (JMACCT). In addition, a portal site which supports searching for information on clinical trials in all three registries has been operated by the National Institute of Public Health (NIPH). After we established a cooperative system, we became a WHO Primary Registry on October 16, 2008 and announced this in Japan on the next day. This cooperation system is called the Japan Primary Registries Network (JPRN).

In order to show that this type of network works well as a Primary Registry, we are cooperating with global activities of World Health Organization's International Clinical Trial Registry Platform (WHO ICTRP) to promote clinical trials and propose appropriate idea to the world.
Directional Force Sensation by Asymmetric Oscillation From a Double-Layer Slider-Crank Mechanism
Authors: Amemiya Tomohiro , Maeda Taro
Published: March 2009

By subjecting a small object in a handheld device to periodic translational motion with asymmetric acceleration (accelerated more rapidly in one direction than in the other), the holder typically experiences the kinesthetic illusion of being pushed or pulled continuously by the held device. We have been investigating the effect because of its potential application to a handheld, nongrounded, haptic device that can convey a sense of a continuous translational force in one direction. A one-degree-of-freedom haptic device based on a double-layer slider-crank mechanism was constructed based on the results of our previous research. Our results with the new haptic device show that (i) humans perceive directed force sensation by asymmetric oscillation, (ii) 5 counts/s is the best frequency to generate the force sensation, (iii) the ratio of the gross weight of the device and the weight of the reciprocating mass should be at least 16% for effective force perception, and (iv) the force perception is the same with the device held in either hand.
Haptics-Enabled UAV Teleoperation Using Motion Capture Systems
Authors: Troy James J. , Erignac Charles A. , Murray Paul
Published: March 2009

This paper describes a system for direct position and orientation control of remotely piloted aerial vehicles using haptic force feedback. Motion capture hardware is used to provide real-time position and orientation information to the closed-loop flight control algorithm. A 3D simulation environment running in parallel with the vehicle control system provides real-time proximity/collision detection and flight volume constraints. Virtual coupling elements are used to connect a haptic user interface, the simulation environment, and the vehicle controller. An implementation of the system using an electrical radio controlled (RC) helicopter in an indoor environment is presented.
Exploring the Dimensions of Haptic Feedback Support in Manual Control
Authors: Abbink D. A. , Mulder M.
Published: March 2009

A promising way to support operators in a manual control task is to provide them with guiding feedback forces on the control device (e.g., the steering wheel). These additional forces can suggest a safe course of action, which operators can follow or over-rule. This paper explores the idea that the feedback forces can be designed not only to depend on a calculated error (i.e., force feedback) but also on the control device position (i.e., stiffness feedback). First, the fundamental properties of force and stiffness feedback are explained, and important parameters for designing beneficial haptic feedback are discussed. Then, in an experiment, the unassisted control of a second-order system (perturbed by a multisine disturbance) is compared with the same control task supported by four haptic feedback systems: weak and strong force feedback, both with and without additional stiffness feedback. Time and frequency-domain analyses are used to understand the changes in human control behavior. The experimental results indicate that—when well designed—stiffness feedback may raise error-rejection performance with the same level of control activity as during unassisted control. The findings may aid in the design of haptic feedback systems for automotive and aerospace applications, where human attention is still required in a visually overloaded environment.
Improved Haptic Fidelity Via Reduced Sampling Period With an FPGA-Based Real-Time Hardware Platform
Authors: O’Malley Marcia K. , Sevcik Kevin S. , Kopp Emilie
Published: March 2009

A haptic virtual environment is considered to be high-fidelity when the environment is perceived by the user to be realistic. For environments featuring rigid objects, perception of a high degree of realism often occurs when the free space of the simulated environment feels free and when surfaces intended to be rigid are perceived as such. Because virtual surfaces (often called virtual walls) are typically modeled as simple unilateral springs, the rigidity of the virtual surface depends on the stiffness of the spring model. For impedance-based haptic interfaces, the stiffness of the virtual surface is limited by the damping and friction inherent in the device, the sampling rate of the control loop, and the quantization of sensor data. If stiffnesses greater than the limit for a particular device are exceeded, the interaction between the human user and the virtual surface via the haptic device becomes nonpassive. We propose a computational platform that increases the sampling rate of the system, thereby increasing the maximum achievable virtual surface stiffness, and subsequently the fidelity of the rendered virtual surfaces. We describe the modification of a PHANToM Premium 1.0 commercial haptic interface to enable computation by a real-time operating system (RTOS) that utilizes a field programmable gate array (FPGA) for data acquisition between the haptic interface hardware and computer. Furthermore, we explore the performance of the FPGA serving as a standalone system for communication and computation. The RTOS system enables a sampling rate for the PHANToM that is 20 times greater than that achieved using the “out of the box” commercial hardware system, increasing the maximum achievable surface stiffness twofold. The FPGA platform enables sampling rates of up to 400 times greater, and stiffnesses over 6 times greater than those achieved with the commercial system. The proposed computational platforms will enable faster sampling rates for any haptic device, thereby improving the fidelity of virtual environments.
Experimental Evaluation of Shared Control for Rehabilitation of Fine Motor Skills
Authors: Srimathveeravalli Govindarajan , Gourishankar Venkatraghavan , Kumar Amrish , Kesavadas Thenkurussi
Published: March 2009

We present the experimental results contrasting virtual fixtures (VFs) with a new shared control (SC) technique for rehabilitation of fine motor skills. The SC assistance algorithm used haptic attributes as the control goal. VF provided assistance based on trajectory. Shapes were chosen from the Visual Motor Integration test book and were used to train candidate’s nondominant hand, using samples recorded from their dominant hand. The results were analyzed using time, trajectory, forces, shape of trajectory, and haptic profiles as metrics. The results indicate that performance of VF and SC were comparable for simple trajectories and SC performed better for complex trajectories.
Modeling Characteristics of an Operational Probabilistic Safety Assessment (PSA)
Authors: Anoba Richard C. , Khalil Yehia , Fluehr J. J. , Kellogg Richard , Hackerott Alan
Published: March 2009

Probabilistic Safety Assessments (PSAs) are increasingly being used as a tool for supporting the acceptabilty of design, procurement, construction, operation, and maintenance activities at nuclear power plants. Since the issuance of Generic Letter 88-20 [1] and subsequent Individual Plant Examinations (IPEs)/Individual Plant Examinations for External Events (IPEEEs) [2], the NRC has issued several Regulatory Guides such as RG 1.182 [3] to describe the use of PSA in risk informed regulation activities. The PSA models developed for the IPEs were typically based on a “snapshot” of the the risk profile at the nuclear power plant. The IPE models contain implicit assumptions and simplifications that limit the ability to realistically assess current issues. For example, IPE modeling assumptions related to plant configuration limit the ability to perform online equipment out-of-service assessments. The lack of model symmetry results in skewed risk results. IPE model simplifications related to initiating events have resulted in non-conservative estimates of risk impacts when equipment is removed from service. The IPE models also do not explicitly address all external events that are potentially risk significant as equipment is removed from service.
Analysis of Particle-Dispersed Composites Accounting Stochastically for Interfacial Damage
Authors: Chang Huajian , Nakagaki Michihiko
Published: March 2009

More and more composite materials have been being utilized in nuclear facilities. While the external loading applied, the stress in composite is concentrated, which is harmful and may cause interfacial damage. The debonding and sliding at the interface between matrix and particles are the most common phenomena. In this paper, a statistically elastoplastic constitutive model for particle-dispersed composites is developed by accounting stochastically for both interfacial damage and localized plasticity. The effects of damaged interface on the strain field in composite are considered in two ways. First, the damaged interface between the matrix and the particles makes the strain field inside inclusions is different from that of the particles with perfectly bonded interface. Second, it contributes an additional strain, which is due to the displacement jump at the matrix-inclusion interface. This additional is defined as an integration of displacement jumps between the matrix and the particles over their interface. In present paper, the first part is considered by using a modified Eshelby’s S-tensor. After deriving the local relative displacement distributions between matrix and inclusion at the interface, the second contribution of damaged interface to the average strain can be expressed in terms of the corresponding eigen-strain or the uniform external loading, by introducing the damage-relevant tensors, which are transformation tensors and tends to zero if interfacial damage does not take place. Both the tangential and normal discontinuities at the interface are independently modeled. The model uses statistic scheme with distribution functions in the stress/strain space, so that the meso-local effects of plastic deformation, interfacial damage and their interactions are accounted for. In order to verify the feasibility and performance of the proposed constitutive model, numerical calculations are carried out. It is found that the damaged interface conditions of debonding and/or sliding give detrimental effects on the overall properties of composites. Thus, the establishment of the most appropriate model describing properly the meso-local phenomena.
The REBUS Experimental Programme for Burn-Up Credit
Authors: D’hondt Pierre , van der Meer Klaas , Baeten Peter , Marloye Daniel , Lance Benoit , Basselier Jacques
Published: March 2009

An international programme called REBUS (REactivity tests for a direct evaluation of the Burn-Up credit on Selected irradiated LWR fuel bundles) for the investigation of the burn-up credit has been initiated by the Belgian Nuclear Research Center SCK•CEN and Belgonucle´aire with the support of USNRC, EdF from France, VGB, representing German nuclear utilities and NUPEC, representing the Japanese industry. The programme aims to establish a neutronic benchmark for reactor physics codes. This benchmark will qualify the codes to perform calculations of the burn-up credit. The benchmark exercise investigates the following fuel types with associated burn-up: • Reference 3.3% enriched UO2 fuel; • Fresh commercial PWR UO2 fuel; • Irradiated commercial PWR UO2 fuel (51 GWd/tM); • Fresh PWR MOX fuel; • Irradiated PWR MOX fuel (20 GWd/tM). Reactivity effects are measured in the critical facility VENUS. Fission rate and flux distributions in the experimental bundles will be determined. The accumulated burn-up of all rods is measured non-destructively in a relative way by gross gamma-scanning, while some rods are examined by gamma-spectrometry for an absolute determination of the burn-up. Some rods will be analyzed destructively with respect to accumulated burn-up, actinides content and TOP-19 fission products (i.e. those non-gaseous fission products that have most implications on the reactivity). Additionally some irradiated rods have undergone a profilometry and length determination. The experimental implementation of the programme has started in 2000 with major changes in the VENUS critical facility. Gamma scans, profilometry, length determination and gamma-spectrometry measurements on the MOX fuel have been performed. In the course of October 2001 the first fresh fuel configuration will be investigated. In the same period the commercial irradiated fuel will arrive at the SCK•CEN hot cells and will be refabricated into fuel rodlets of 1 meter length.
Experimental and Numerical Investigation of Gravity-Driven Pipe Flow With Cavitation
Authors: Giese Tobias , Laurien Eckart , Schwarz Wolfgang
Published: March 2009

Gravity driven pipe flows contain no risk of pump failure and are considered to be reliable even under accident conditions. However, accurate prediction methods are only available for single phase flow. In case of the occurrence of two-phase flow (caused e.g. by boiling or cavitation), a considerable reduction in mass flux can be observed. In this study, an experimental and numerical investigation of gravity driven two-phase pipe flow was performed in order to understand and model such flows. An experiment was conducted to analyse gravity driven flow of water near saturation temperature in a complex pipe consisting of several vertical and horizontal sections. The diameter was 100 mm with a driving height of 13 m between an elevated tank and the pipe outlet. The experiment shows that cavitation leads to formation of steam. The two-phase character of the flow causes a significant reduction of mass flux in comparison to a single phase flow case. The experimental flow rate was reproduced by one dimensional single and two phase flow analysis based on standard one dimensional methods including models for steam formation. The main part of this study consists of a three dimensional CFD analysis of the two phase flow. A three dimensional model for cavitation and recondensation phenomena based on thermal transport processes was developed, implemented and validated against our experimental data. Due to the fact that beside bubbly flow, also the stratified and droplet flow regimes occur, a new approach to model phase interaction terms of the Two-Fluid Model for mass, momentum and energy is presented. Thereby, the transition from one flow regime to another is taken into account. The experimental mass flow rate can be predicted with an accuracy of 10%. The three dimensional analysis of the flow situation demonstrates the influence of pipe elements such as horizontal and vertical sections, bends and valves of the pipe on the mass flux and the steam distribution. The analysis of secondary flows in bends emphases their importance for the steam distribution within the pipe, for the pressure loss and the average mass flux.
An Experimental Investigation of the Limiting Critical Quality and Its Impact on CHF in Horizontal and Vertical Tubes Cooled With Water and R-134a
Authors: Pioro I. L. , Doerffer S. S. , Cheng S. C.
Published: March 2009

An experimental study of the critical heat flux (CHF) and the associated limiting critical quality phenomenon has been conducted recently for horizontal and vertical tubes cooled with water and the refrigerant R-134a. The objective of this study is to compare the CHF and the associated limiting critical quality data obtained in horizontal and vertical tubes, in order to assess the effect of orientation on the CHF and the limiting critical quality. The investigated ranges of flow parameters in water (the R-134a equivalent values are given in brackets and have been transformed using the CHF fluid-to-fluid modeling relationships) are outlet pressure of 8 (1.31), 9 (1.48), 10 (1.67), 11 (1.84) and 12 (2.03) MPa; mass fluxes from 500 (350) to 4300 (3000) kg/m2s; and critical qualities from −0.1 to +0.9. A comparison of the data for a horizontal tube with those for a vertical tube shows a strong orientation effect on CHF and limiting critical quality for mass fluxes below 4300 kg/m2s in water (or below 3000 kg/m2s in R-134a). The orientation effect decreases with increasing mass flux. In general, at similar flow conditions, the limiting critical quality values in a horizontal tube are lower than those in a vertical tube. This phenomenon is affected by the flow parameters and the thermophysical properties of the working fluid (i.e., mainly the densities of liquid and vapor). A drop in CHF within the limiting critical quality region in a horizontal tube can be less significant than that in a vertical tube. These differences seem to be mainly due to the effect of the buoyancy force.
Integrated Risk-Informed Asset Management for Commercial Nuclear Power Stations
Authors: Liming James K. , Kee Ernest J.
Published: March 2009

The objective of this paper is to provide electric utilities with a concept for preparing and implementing integrated risk-informed asset management (RIAM) programs for power stations and generating companies. RIAM is a process by which analysts review historical performance and develop predictive logic models and data analyses to predict critical decision support figures-of-merit (or metrics) for generating station managers and electric utility company executives. These metrics include, but are not limited to, the following: profitability, projected revenue, projected costs, asset value, safety (catastrophic facility damage frequency and consequences, etc.), power production availability (capacity factor, etc.), efficiency (heat rate), and others. RIAM applies probabilistic safety assessment (PSA) techniques and generates predictions probabilistically so that metrics information can be supplied to managers in terms of probability distributions as well as point estimates. This enables the managers to apply the concept of “confidence levels” in their critical decision-making processes.
Development of Computer Program for Whole Core Thermal-Hydraulic Analysis of Fast Reactors
Authors: Ohshima Hiroyuki , Ohtaka Masahiko
Published: March 2009

A whole core thermal-hydraulic analysis program ACT was developed for the purpose of evaluating detailed in-core thermal-hydraulic phenomena of sodium cooled fast reactors under various reactor operation conditions. ACT consists of four kinds of calculation modules, i.e., fuel-assembly, inter-wrapper gap (core barrel), upper plenum and heat transport system modules. The latter two modules give proper boundary conditions for the reactor core thermal-hydraulic analysis. These four modules are coupled with each other by using MPI and calculate simultaneously on a cluster workstation. ACT was applied to analyzing a sodium experiment performed at JNC, which simulated the natural circulation decay heat removal under PRACS and DRACS operation condition. In the experiment, not only inter-wrapper flows but also reverses flows in the fuel assemblies were observed. ACT succeeded in simulating such complicated phenomena.
Static Converter for High Energy Utilization, Modular, Small Nuclear Power Plants
Authors: El-Genk Mohamed S. , Tournier Jean-Michel P.
Published: March 2009

This paper presents and analyzes the performance of high efficiency, high total energy utilization, static converters, which could be used in conjunction with small nuclear reactor plants in remote locations and in undersea applications, requiring little or no maintenance. The converters consist of a top cycle of Alkali Metal Thermal-to-Electric Conversion (AMTEC) units and PbTe thermoelectric (TE) bottom cycle. In addition to converting the reactor thermal power to electricity at 1150 K or less, at a thermodynamic efficiency in the low to mid thirties, the heat rejection from the TE bottom cycle could be used for space heating, industrial processing, or sea water desalination. The results indicated that for space heating applications, where the rejected thermal power from the TE bottom cycle is removed by natural convection of ambient air, a total utilization of the reactor thermal power of > 80% is possible. When operated at 1030 K, potassium AMTEC/TE converters are not only more efficient than the sodium AMTEC/TE converters but produce more electrical power. The present analysis showed that a single converter could be sized to produce up to 100 kWe and 70 kWe, for the Na-AMTEC/TE units when operating at 1150 K and the K-AMTEC/TE units when operating at 1030 K, respectively. Such modularity is an added advantage to the high-energy utilization of the present AMTEC/TE converters.
Effect of Loading Pattern on Thermal and Shielding Performance of a Spent Fuel Cask
Authors: McKinnon Mikal A. , Cuta Judith M. , Jenquin Urban P.
Published: March 2009

Two key considerations that must be addressed in licensing spent fuel storage systems are peak cladding temperatures and surface dose rates. Generally, storage systems are approved for a uniform loading of a design basis fuel. This analytical study addresses the effect of non-uniform loading patterns on peak fuel temperatures and cask surface dose rates. Three radial power distributions are considered: uniform loading, hotter assemblies in the center of the cask, and hotter assemblies near the wall of the cask. This paper summarizes the results of an analytical study [1] in which it was shown that, for the same total heat load in a cask, peak fuel temperatures are reduced by loading hotter assemblies around the outside of the cask’s basket. It was also shown that loading the hotter assemblies around the outside of the cask results in modest increases in surface dose rates.