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Sample records for initial microvessel density

  1. Microvessels Density in Uterine Leiomyosarcoma

    PubMed Central

    Bobiński, Marcin; Bednarek, Wiesława; Szumiło, Justyna; Cybulski, Marek; Polak, Grzegorz; Kotarski, Jan

    2015-01-01

    Uterine leiomyosarcomas (LMS) are rare tumors typically presenting rapid growth and unfavorable outcome. Nowadays the results of uterine LMS treatment do not meet expectations. Angiogenesis is one of processes investigated to be target for future treatment. The aim of the research was to assess microvessels density (MVD) in tumor samples collected from 50 patients with histological confirmed uterine leiomyosarcoma and to investigate statistical relations between MVD, patients survival, and FIGO stage of tumor. The assessment was carried out using immunohistochemistry methods with anti-CD34 antibody. No significant difference in MVD between FIGO stages was observed. Furthermore, contrary to many other malignancies, we found no significant relation between MVD and patients overall and 2-year survival. Results obtained in the study suggest that processes on vascular mimicry and mesenchymal to epithelial transition (MET) may play important role in development of LMS. No statistical relation between MVD and survival leads to conclusion that not only angiogenesis but other mechanisms as well should be taken into consideration in planning future research. PMID:26161403

  2. Predictive values of vascular endothelial growth factor and microvessel-density levels in initial biopsy for prostate cancer.

    PubMed

    Kervancioglu, Enis; Kosan, Murat; Erinanc, Hilal; Gonulalan, Umut; Oguzulgen, Ahmet Ibrahim; Coskun, Esra Zeynep; Ozkardes, Hakan

    2016-02-01

    Angiogenesis is an important factor in the development and progression of prostate cancer (PCA). We aimed to investigate the values of vascular-endothelial-growth-factor (VEGF) expression level and microvessel density (MVD) in the prediction of PCA diagnosis at repeated prostate biopsy (re-PBx). We retrospectively evaluated 167 patients with re-PBx according to elevated prostate-specific antigen levels, suspicious digital rectal examination, and the presence of premalignant lesions. Patients with PCA on re-PBx were included in the cancer group (n = 17). Patients with benign prostatic hyperplasia or normal tissues on re-PBx were included in the control group (n = 21). The groups were compared according to the expression level of VEGF and MVD in initial prostate biopsy. There was no statistically significant difference between groups according to age and serum prostate-specific-antigen values. The mean VEGF scores of the cancer and control groups were 232.64 ± 11.14 and 183.09 ± 14.56, respectively (p < 0.05). The mean MVD of the biopsy samples in the cancer and control groups were 246.47 ± 17.59 n/mm(2) and 197.33 ± 16.26 n/mm(2), respectively (p < 0.05). The cutoff values of VEGF scores and MVD were set as 200 and 215, respectively, for PCA detection in our study. Our results showed that the expression level of VEGF and MVD significantly increased in the initial prostate-biopsy samples of patients with PCA diagnosed with re-PBx. The evaluation of VEGF expression level and MVD might have an important value in the prediction of PCA at re-PBx. The expression level of VEGF and MVD should be kept in mind as PCA-related histopathological changes that indicate the increased angiogenesis in prostatic tissue.

  3. Obesity, insulin resistance, and microvessel density.

    PubMed

    Frisbee, Jefferson C

    2007-01-01

    The growing incidence and prevalence of the overweight/obese condition across developed economies worldwide has an enormous impact on increasing the risk for the development of impaired glycemic control or insulin resistance and ultimately peripheral vascular disease (PVD) in afflicted individuals. This places an enormous economic and social burden on these societies, in terms of additional health care costs and lost productivity and through a reduction in the quality of life of the individual owing, in part, to the progressive PVD. Characterized by an inability of the vascular systems to adequately perfuse tissues and organs relative to their metabolic demand, PVD is in part a function of a structural remodeling of the microvascular networks such that the density of microvessel and capillaries within tissues is reduced below that under normal conditions, with the potential for profound negative impacts on the processes of mass transport and exchange. The review discusses the severity of the obesity "epidemic" from the perspective of PVD and the effects of the development of the obese, insulin-resistant condition on tissue/organ microvessel density. Additional material is reviewed that addresses ameliorative treatments, primarily exercise training, on blunting microvessel loss in the obese, insulin-resistant individual, and on potential mechanistic contributors that warrant considerable future investigation.

  4. Intra-tumoural microvessel density in human solid tumours

    PubMed Central

    Hasan, J; Byers, R; Jayson, G C

    2002-01-01

    Over the last decade assessment of angiogenesis has emerged as a potentially useful biological prognostic and predictive factor in human solid tumours. With the development of highly specific endothelial markers that can be assessed in histological archival specimens, several quantitative studies have been performed in various solid tumours. The majority of published studies have shown a positive correlation between intra-tumoural microvessel density, a measure of tumour angiogenesis, and prognosis in solid tumours. A minority of studies have not demonstrated an association and this may be attributed to significant differences in the methodologies employed for sample selection, immunostaining techniques, vessel counting and statistical analysis, although a number of biological differences may account for the discrepancy. In this review we evaluate the quantification of angiogenesis by immunohistochemistry, the relationship between tumour vascularity and metastasis, and the clinicopathological studies correlating intra-tumoral microvessel density with prognosis and response to anti-cancer therapy. In view of the extensive nature of this retrospective body of data, comparative studies are needed to identify the optimum technique and endothelial antigens (activated or pan-endothelial antigens) but subsequently prospective studies that allocate treatment on the basis of microvessel density are required. British Journal of Cancer (2002) 86, 1566–1577. DOI: 10.1038/sj/bjc/6600315 www.bjcancer.com © 2002 Cancer Research UK PMID:12085206

  5. Evaluation of microvessel density and p53 expression in pancreatic adenocarcinoma

    PubMed Central

    Jureidini, Ricardo; da Cunha, José Eduardo Monteiro; Takeda, Flavio; Namur, Guilherme Naccache; Ribeiro, Thiago Costa; Patzina, Rosely; Figueira, Estela RR; Ribeiro, Ulysses; Bacchella, Telesforo; Cecconello, Ivan

    2016-01-01

    OBJECTIVE: To evaluate the prognostic significance of microvessel density and p53 expression in pancreatic cancer. METHODS: Between 2008 and 2012, 49 patients with pancreatic adenocarcinoma underwent resection with curative intention. The resected specimens were immunohistochemically stained with anti-p53 and anti-CD34 antibodies. Microvessel density was assessed by counting vessels within ten areas of each tumoral section a highpower microscope. RESULTS: The microvessel density ranged from 21.2 to 54.2 vessels/mm2. Positive nuclear staining for p53 was found in 20 patients (40.6%). The overall median survival rate after resection was 24.1 months and there were no differences in survival rates related to microvessel density or p53 positivity. Microvessel density was associated with tumor diameter greater than 3.0 cm and with R0 resection failure. CONCLUSIONS: Microvessel density was associated with R1 resection and with larger tumors. p53 expression was not correlated with intratumoral microvessel density in pancreatic adenocarcinoma. PMID:27438564

  6. Expression of EGFR and Microvessel Density in Middle Ear Cholesteatoma

    PubMed Central

    Jin, Bong Joon; Min, Hyun Jung; Jeong, Jin Hyeok; Park, Chul Won

    2011-01-01

    Objectives Cholesteatoma destructs bony tissue by the interactions between hyperproliferative epithelial cells and subepithelial inflammatory cells. The aim of this study was to evaluate the expression of epidermal growth factor receptor (EGFR) and microvessel density (MVD) in middle ear cholesteatoma tissue in an effort to determine the relationship between expression of EGFR and neovascularization. Methods We evaluated the expression of EGFR and MVD by immunohistochemical staining for CD31 and Factor VIII in 32 cholesteatoma tissue samples and 7 normal postauricular skin samples. We also analyzed the correlation between EGFR expression and MVD. Results The expression of EGFR was higher in cholesteatoma than in postauricular skin, but the difference was not statistically significant. EGFR was more highly expressed in the suprabasal layer than in the basal layer. Using CD31 and Factor VIII, we analyzed the MVD and found that it was significantly higher in cholesteatoma than in postauricular skin, and significantly correlated with the expression of EGFR. Conclusion Our results suggest that overexpression of EGFR and neovascularization are correlated with the growth of cholesteatoma. PMID:21716952

  7. EGFR and microvessel density in canine malignant mammary tumours.

    PubMed

    Carvalho, Maria Isabel; Guimarães, Maria João; Pires, Isabel; Prada, Justina; Silva-Carvalho, Ricardo; Lopes, Carlos; Queiroga, Felisbina L

    2013-12-01

    The epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase receptor which has been shown to have an important role in human breast cancer. Its role appears to be associated with increased angiogenesis and metastasis. In order to clarify its role in canine mammary tumours (CMT), 61 malignant neoplasms were studied by using immunohistochemistry, comparing expression of EGFR, microvessel density (MVD) by CD31 immunolabelling and characteristics of tumour aggressiveness. High EGFR immunoexpression was statistically significantly associated with tumour size, tumour necrosis, mitotic grade, histological grade of malignancy and clinical stage. High CD31 immunoreactivity was statistically significantly associated with tubule formation, histological grade of malignancy and clinical stage. A positive correlation between EGFR and CD31 immunoexpression (r = 0.843; P < 0.001) was also observed. Results suggest that an over-expression of EGFR may contribute to increased angiogenesis and aggression in malignant CMT, presenting the possibility of using EGFR inhibitors in the context of metastatic disease treatment. PMID:24091029

  8. Microvessel density is a prognostic marker of human gastric cancer

    PubMed Central

    Zhao, Hong-Chuan; Qin, Rong; Chen, Xiao-Xin; Sheng, Xia; Wu, Ji-Feng; Wang, Dao-Bin; Chen, Gui-Hua

    2006-01-01

    AIM: To investigate whether microvessel density (MVD) is related with prognosis in gastric cancer patients, and the expression of cyclooxygenase-2 (COX-2) and vessel endothelial growth factor (VEGF) so as to determine the possible role of COX-2 and VEGF in gastric cancer angiogenesis. METHODS: Forty-seven formalin-fixed paraffin-embedded tissue samples of gastric cancer were evaluated for COX-2, VEGF by immunohistochemical staining. To assess tumor angiogenesis, MVD was determined by immunohistochemical staining of endothelial protein factor VIII-related antigen. The relationship among COX-2 and VEGF expression, MVD, and clinicopathologic parameters was analyzed. RESULTS: Among the 67 samples, high MVD was significantly associated with lymph node metastasis and poor survival. Multivariate survival analysis showed that MVD value and lymph node metastasis were independent prognostic factors. The expression rate of COX-2 and VEGF was significantly higher than that of the adjacent tissues. COX-2 and VEGF expression in gastric cancer was significantly correlated with tumor differentiation and depth of invasion, but not with survival. The mean MVD value of COX-2 or VEGF positive tumors was higher than that of COX-2 or VEGF negative tumors. A significant correlation was found between the expressions of COX-2 and VEGF. CONCLUSION: MVD may be one of the important prognostic factors for gastric cancer patients. COX-2 and VEGF may play an important role in tumor progression by stimulating angiogenesis. VEGF might play a main role in the COX-2 angiogenic pathway. The inhibition of angiogenesis or COX-2, VEGF activity may have an important therapeutic benefit in the control of gastric cancer. PMID:17171787

  9. Continuous Low-Dose Temozolomide Chemotherapy and Microvessel Density in Recurrent Glioblastoma

    PubMed Central

    Woo, Jong-Yun; Yang, Seung Ho; Lee, Youn Soo; Lee, Su Youn; Kim, Jeana

    2015-01-01

    Objective The purpose of this study was to evaluate the clinical efficacy of continuous low-dose temozolomide (TMZ) chemotherapy for recurrent and TMZ-refractory glioblastoma multiforme (GBM) and to study the relationship between its efficacy and microvessel density within the tumor. Methods Thirty patients who had recurrent GBM following Stupp's regimen received TMZ daily at 50 mg/m2/day until tumor progression between 2007 and 2013. The median duration of continuous low-dose TMZ administration was 8 weeks (range, 2-64). Results The median progression-free survival (PFS) of continuous low-dose TMZ therapy was 2 months (range, 0.5-16). At 6 months, PFS was 20%. The median overall survival (OS) from the start of this therapy to death was 6 months (95% CI : 5.1-6.9). Microvessel density of recurrent tumor tissues obtained by reoperation of 17 patients was 22.7±24.1/mm2 (mean±standard deviation), and this was lower than that of the initial tumor (61.4±32.7/mm2) (p-value=0.001). It suggests that standard TMZ-chemoradiotherapy reduces the microvessel density within GBM and that recurrences develop in tumor cells with low metabolic burden. The efficacy of continuous low-dose TMZ could not be expected in recurrent GBM cells in poor angiogenic environments. Conclusion The efficacy of continuous low-dose TMZ chemotherapy is marginal. This study suggests the need to develop further treatment strategies for recurrent and TMZ-refractory GBM. PMID:26713142

  10. Flow cytometric quantification of tumour endothelial cells; an objective alternative for microvessel density assessment.

    PubMed

    Baeten, C I M; Wagstaff, J; Verhoeven, I C L; Hillen, H F P; Griffioen, A W

    2002-07-29

    Assessment of microvessel density by immunohistochemical staining is subject to a considerable inter-observer variation, and this has led to variability in correlation between microvessel density and clinical outcome in different studies. In order to improve the method of microvessel density measurement in tumour biopsies, we have developed a rapid, objective and quantitative method using flow cytometry on frozen tissues. Frozen tissue sections of archival tumour material were enzymatically digested. The single-cell suspension was stained for CD31 and CD34 for flow cytometry. The number of endothelial cells was quantified using light scatter- and fluorescence-characteristics. Tumour endothelial cells were detectable in a single cell suspension, and the percentage of endothelial cells detected in 32 colon carcinomas correlated highly (r=0.84, P<0.001) with the immunohistochemical assessment of microvessel density. Flow cytometric endothelial cells quantification was found to be more sensitive especially at lower levels of immunohistochemical microvessel density measurement. The current method was found to be applicable for various tumour types and has the major advantage that it provides a retrospective and quantitative approach to the angiogenic potential of tumours.

  11. Ontogenic increase in PGE2 and PGF2 alpha receptor density in brain microvessels of pigs.

    PubMed Central

    Li, D. Y.; Varma, D. R.; Chemtob, S.

    1994-01-01

    1. The hypothesis that the relative vasoconstrictor ineffectiveness of prostaglandin E2 (PGE2) and PGF2 alpha on cerebral vessels of newborn pigs might be due to fewer receptors for these prostanoids was tested by comparing receptors for PGE2 (EP) and PGF2 alpha (FP) in cerebral microvessels from newborn and adult pigs. 2. Specific binding of [3H]-PGE2 and [3H]-PGF2 alpha to membranes prepared from brain microvessels showed that EP and FP receptor density (Bmax) in tissues from newborn animals was less than 50% of that determined in tissues from adults. By contrast, estimates of affinity (KD) were unchanged. 3. Specifically bound [3H]-PGE2 to brain microvessels from both the newborn and adult was displaced by AH 6809 (EP1-selective antagonist) by 80-90%, and only by approximately 30-35% by both 11-deoxy PGE1 (EP2/EP3 agonist) and M&B 28,767 (EP3 agonist); butaprost (EP2 agonist) was completely ineffective. 4. PGE2, 17-phenyl trinor PGE2 (EP1 agonist), PGF2 alpha and fenprostalene (PGF2 alpha analogue) caused significantly less increase in inositol 1,4,5-triphosphate (IP3) in brain microvessels from the newborn than in those from adult pigs. The stimulation of IP3 by PGE2 and 17-phenyl trinor PGE2 was almost completely inhibited by the EP1 antagonist, AH 6809. 5. PGE2, 11-deoxy PGE1 and M&B 28,767 produced small reduction of adenosine 3':5'-cyclic monophosphate (cyclic AMP) production in adult vessels but no effect in newborn tissues. 6. The lower density of EP and FP receptors in microvessels of newborn pigs compared to adults may explain the reduced ability of PGE2 and PGF2 alpha to stimulate production of IP3 in tissues from newborn animals.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8032662

  12. Expression of inducible nitric oxide synthase and cyclooxygenase-2 in pancreatic adenocarcinoma: Correlation with microvessel density

    PubMed Central

    Kasper, Hans U.; Wolf, Hella; Drebber, Uta; Wolf, Helmut K.; Kern, Michael A.

    2004-01-01

    AIM: Cyclooxygenases (COX) are key enzymes for conversion of arachidonic acid to prostaglandins. Nitric oxide synthase (NOS) is the enzyme responsible for formation of nitric oxide. Both have constitutive and inducible isoforms. The inducible isoforms (iNOS and COX-2) are of great interest as regulators of tumor angiogenesis, tumorigenesis and inflammatory processes. This study was to clarify their role in pancreatic adenocarcinomas. METHODS: We investigated the immunohistochemical iNOS and COX-2 expression in 40 pancreatic ductal adenocarcinomas of different grade and stage. The results were compared with microvessel density and clinicopathological data. RESULTS: Twenty-one (52.5%) of the cases showed iNOS expression, 15 (37.5%) of the cases were positive for COX-2. The immunoreaction was heterogeneously distributed within the tumors. Staining intensity was different between the tumors. No correlation between iNOS and COX-2 expression was seen. There was no relationship with microvessel density. However, iNOS positive tumors developed more often distant metastases and the more malignant tumors showed a higher COX-2 expression. There was no correlation with other clinicopathological data. CONCLUSION: Approximately half of the cases expressed iNOS and COX-2. These two enzymes do not seem to be the key step in angiogenesis or carcinogenesis of pancreatic adenocarcinomas. Due to a low prevalence of COX-2 expression, chemoprevention of pancreatic carcinomas by COX-2 inhibitors can only achieve a limited success. PMID:15222037

  13. Prospective study of intratumoral microvessel density, p53 expression and survival in colorectal cancer

    PubMed Central

    Vermeulen, P B; Eynden, G G Van den; Huget, P; Goovaerts, G; Weyler, J; Lardon, F; Marck, E Van; Hubens, G; Dirix, L Y

    1999-01-01

    Adjuvant treatment of patients with colorectal cancer is hampered by a lack of reliable prognostic factors in addition to the clinicopathological staging system. A poorly defined but considerable fraction of Astler–Coller stage B patients will experience tumour recurrence, and some of the stage C patients will probably survive for a prolonged time after surgery without adjuvant treatment. Assessing parameters related to tumour angiogenesis has provided valuable prognostic information in different tumour types. The formation of new microvessels is part of the malignant phenotype in the majority of tumours. Alterations in tumour-suppressor genes, such as the p53 gene, or oncogenes, such as the ras gene, have been found to be responsible for changing the local balance of pro- and antiangiogenic factors in favour of the former. In this prospective study, intratumoral microvessel density (IMD) was assessed by immunostaining tissue sections for CD31 and counting individual microvessels in selected and highly vascular regions in specimens of 145 colorectal cancer patients. p53 protein overexpression was semiquantitatively determined after immunohistochemistry. In both uni- and multivariate analysis, high IMD was significantly associated with shorter survival in the patients undergoing surgery with curative intent (Astler–Coller stages A–C). p53 added prognostic power to IMD, both in Astler–Coller stage B and stage C patients. An association between IMD and mode of metastasis was also noted. High IMD was strongly associated with the incidence of haematogenous metastasis during follow-up, but not with the presence of lymphogenic metastasis observed at surgery. This study confirms the results of previous retrospective analyses of IMD and survival in colorectal cancer and warrants a clinical validation by randomizing stage B tumour patients with high IMD and p53 overexpression between adjuvant treatment or not. © 1999 Cancer Research Campaign PMID:9888475

  14. VEGF expression, microvessel density and dendritic cell decrease in thyroid cancer

    PubMed Central

    Gulubova, Maya; Ivanova, Koni; Ananiev, Julian; Gerenova, Julieta; Zdraveski, Aleksandar; Stoyanov, Hristo; Vlaykova, Tatyana

    2014-01-01

    Thyroid cancer is one of the five most common cancers in the age between 20 and 50 years. Many factors including the potent angiogenic vascular endothelial growth factor (VEGF) and different dendritic cell types are known to be related to thyroid tumourogenesis. The study was performed to address the expression of VEGF and microvessel density in thyroid cancers and to evaluate the effect of VEGF expression in thyroid tumour cells on the dendritic cells. We investigated 65 patients with different types of thyroid carcinomas: papillary (PTC), oncocytic (OTC), follicular (FTC) and anaplastic (ATC), immunohistochemically with antibodies against VEGF, CD1a, CD83, S100 and CD31. Our results suggest that the expression of VEGF is significantly more often in PTC than ATC (92.3% vs. 60.0%, p = 0.025). The microvessel density marked with CD31 in the tumour border of PTC was significantly higher as compared to FTC (p = 0.039), but not to ATC and OTC (p = 0.337 and 0.134). We found that CD1a- and CD83-positive cells were dispersed with variable density and in OC CD31+ vessel numbers were positively correlated with CD83+ dendritic cells in tumour stroma (R = 0.847, p = 0.016). We did not find statistically significant associations of the survival of patients with PTC after the surgical therapy with VEGF expression and MVD. In conclusion we may state that VEGF expression in tumour cells of thyroid cancer can induce neovascularization and suppress dendritic cells. PMID:26019537

  15. Involvement of mast cells and microvessels density in reactive lesions of oral cavity: A comparative immunohistochemical study.

    PubMed

    Ferreira, Stephany Vasco; Xavier, Flávia Caló Aquino; Freitas, Maria da Conceição Andrade de; Nunes, Fábio Daumas; Gurgel, Clarissa Araújo; Cangussu, Maria Cristina Teixeira; Martins, Manoela Domingues; Freitas, Valéria Souza; Dos Santos, Jean Nunes

    2016-09-01

    In view of the similarity of clinicopathological features between reactive lesions of the oral cavity, the objective of the present study was to investigate the density of MCs (mast cells) and microvessels in a series of these lesions. Thirty-seven cases of reactive lesions including fibrous hyperplasia (FH, n=10), inflammatory fibrous hyperplasia (IFH, n=10), peripheral giant cell lesion (PGCL, n=10) and lobular capillary hemangioma (LCH, n=7) were investigated using immunohistochemistry for mast cell tryptase and CD34. For comparative purposes, central giant cell lesions (CGCL, n=5) were included. A higher MC density was observed in LCH (37.01), while CGCL exhibited the lowest density (n=8.14). There was a significant difference in MC density when all reactive lesions were compared to CGCL (p=0.001). The largest mean density of microvessels was observed in LCH (n=21.69). The smallest number was observed in CGCL (n=6.24). There was a significant difference in microvessel density when the reactive lesions were compared to CGCL (p=0.003). There was a significant and direct correlation between the density of MCs and microvessels only for IFH (p=0.048) and CGCL (p=0.005). A significant and direct correlation between the mean density of MCs and microvessels was observed when the reactive lesions were analyzed as a whole (p=0.005). Our results suggest that mast cells contribute to the connective tissue framework and angiogenic function, as well as the development, of reactive lesions of the oral cavity, including FH, IFH, LCH and PGCL. PMID:27493102

  16. Involvement of mast cells and microvessels density in reactive lesions of oral cavity: A comparative immunohistochemical study.

    PubMed

    Ferreira, Stephany Vasco; Xavier, Flávia Caló Aquino; Freitas, Maria da Conceição Andrade de; Nunes, Fábio Daumas; Gurgel, Clarissa Araújo; Cangussu, Maria Cristina Teixeira; Martins, Manoela Domingues; Freitas, Valéria Souza; Dos Santos, Jean Nunes

    2016-09-01

    In view of the similarity of clinicopathological features between reactive lesions of the oral cavity, the objective of the present study was to investigate the density of MCs (mast cells) and microvessels in a series of these lesions. Thirty-seven cases of reactive lesions including fibrous hyperplasia (FH, n=10), inflammatory fibrous hyperplasia (IFH, n=10), peripheral giant cell lesion (PGCL, n=10) and lobular capillary hemangioma (LCH, n=7) were investigated using immunohistochemistry for mast cell tryptase and CD34. For comparative purposes, central giant cell lesions (CGCL, n=5) were included. A higher MC density was observed in LCH (37.01), while CGCL exhibited the lowest density (n=8.14). There was a significant difference in MC density when all reactive lesions were compared to CGCL (p=0.001). The largest mean density of microvessels was observed in LCH (n=21.69). The smallest number was observed in CGCL (n=6.24). There was a significant difference in microvessel density when the reactive lesions were compared to CGCL (p=0.003). There was a significant and direct correlation between the density of MCs and microvessels only for IFH (p=0.048) and CGCL (p=0.005). A significant and direct correlation between the mean density of MCs and microvessels was observed when the reactive lesions were analyzed as a whole (p=0.005). Our results suggest that mast cells contribute to the connective tissue framework and angiogenic function, as well as the development, of reactive lesions of the oral cavity, including FH, IFH, LCH and PGCL.

  17. Angiogenesis in Non-Hodgkin's Lymphoma: An Intercategory Comparison of Microvessel Density

    PubMed Central

    Aggarwal, Deepti; Srivastava, Gunjan; Gupta, Ruchika; Pant, Leela; Krishan, Gopal; Singh, Sompal

    2012-01-01

    Background. This study was aimed at comparing angiogenesis, seen as microvessel density (MVD) in subtypes of non-Hodgkin's lymphoma (NHL). Methods. In this study, 64 cases of NHL diagnosed over a three-year period were included along with 15 lymph node biopsies of reactive hyperplasia. NHLs were classified using REAL classification, and immunohistochemistry was performed for CD34 in all cases. CD34-stained sections were evaluated for “hot spots,” where MVD was assessed and expressed as per mm2. Appropriate statistical methods were applied. Results. There were 6 cases of well-differentiated lymphocytic lymphoma (SLL), 21 diffuse large B-cell lymphoma (DLBCL), 15 follicular lymphoma, 10 lymphoblastic lymphoma, 7 MALToma, and 5 peripheral T-cell lymphoma (PTCL). Mean MVD was highest in reactive hyperplasia (191.92 ± 12.16 per mm2) compared to all NHLs. Among NHLs, PTCL demonstrated the highest MVD (183.42 ± 8.24) followed by DLBCL (149.91 ± 13.68). A significant difference was found in MVD between reactive and individual lymphoma groups. SLL had significantly lower MVD than other lymphoma subtypes. Conclusion. Angiogenesis, assessed by MVD, showed significant differences among subtypes of NHL, especially the indolent types like SLL. The higher MVD in aggressive lymphomas like PTCL and DLBCL can potentially be utilized in targeted therapy with antiangiogenic drugs. PMID:22536524

  18. Probability density functions for axial ratios of sectioning profiles of anisotropically arranged elliptical microvessels.

    PubMed

    Krasnoperov, R A; Gerasimov, A N

    2009-06-01

    The article theoretically regards probability density functions (PDFs) for axial ratio (X/Y) of sectioning profiles of elliptical microvessels (MVs) arranged with anisotropy in a biological tissue volume. A technique for the PDF(X/Y) calculations in anisotropy of the elliptical MVs is described. The essence of this technique is introducing anisotropy in PDF(alpha,phi), i.e. the function of the joint distribution of the polar and planar angles alpha and phi, which define mutual orientation of the elliptical MVs and sectioning planes. With the aid of this technique, the anisotropy cases are studied with PDF(alpha,phi) given by pair combinations of the following distributions: (i) a uniform distribution of the angles alpha and/or phi, (ii) the angle alpha distribution with PDF(alpha)=sin alpha(alpha in [0,pi/2]), and (iii) Gaussian distributions of the alpha or phi values. Specifically, PDF(X/Y) curves are obtained for MVs with the true, or three-dimensional, axial ratio X(0)/Y(0)=2.0, and the anisotropy effects on the X/Y expected frequencies are analysed. Conclusions of this analysis, the PDF(X/Y) calculation technique, and the PDF(X/Y) curves obtained are useful for stereological reconstruction of anisotropically organised microcirculatory networks, with an ellipticity of their MVs being taken into consideration. PMID:19318110

  19. Levels of bone marrow microvessel density are crucial for evaluating the status of acute myeloid leukemia

    PubMed Central

    SONG, YANQIU; TAN, YAN; LIU, LIBO; WANG, QIAN; ZHU, JING; LIU, MIN

    2015-01-01

    The aim of the present study was to determine the efficacy of bone marrow microvessel density (BM-MVD) in the evaluation of the status of acute myeloid leukemia (AML). The levels of serum and bone marrow vascular endothelial growth factor (VEGF), and BM-MVD in 28 patients with AML, 10 patients with non-Hodgkin's lymphoma, 10 patients with anemia and 14 patients with AML that achieved complete remission for six months (AML-DFS) subsequent to chemotherapy were determined by ELISA and immunohistochemistry. The levels of serum VEGF in patients with hematological disorders were significantly increased compared with the levels in the healthy controls. The levels of BM VEGF and BM-MVD in AML patients were significantly higher compared with the levels in the patients with non-Hodgkin's lymphoma or anemia. Following chemotherapy, the levels of serum VEGF significantly increased and the levels of BM VEGF decreased in the AML patients, regardless of their therapeutic responses, compared with the levels prior to treatment. By contrast, the levels of BM-MVD in the AML patients were significantly reduced in the patients that completely recovered from AML (AML-DFS group), compared with those in other groups. The present data indicate that the levels of BM-MVD are valuable for evaluating the status of AML. PMID:26171001

  20. Angiogenesis of uterine cervical carcinoma: characterization by pharmacokinetic magnetic resonance parameters and histological microvessel density with correlation to lymphatic involvement.

    PubMed

    Hawighorst, H; Knapstein, P G; Weikel, W; Knopp, M V; Zuna, I; Knof, A; Brix, G; Schaeffer, U; Wilkens, C; Schoenberg, S O; Essig, M; Vaupel, P; van Kaick, G

    1997-11-01

    Dynamic studies of Gd-based contrast agents in magnetic resonance imaging (MRI) are increasingly being used for tumor characterization as well as therapy response monitoring. Because detailed knowledge regarding the pathophysiological properties, which in turn are responsible for differences in contrast enhancement, remains fairly undetermined, it was the aim of this project to: (a) examine the relationship between contrast-enhanced dynamic MRI-derived characteristics and histological microvessel density counts, a recognized surrogate of tumor angiogenesis, from primary or recurrent cancers of the uterine cervix; and (b) correlate these parameters with lymphatic involvement to characterize tumor aggressiveness in terms of lymphatic spread. Pharmacokinetic parameters (amplitude, A; exchange rate constant, k21) were calculated from a contrast-enhanced dynamic MRI series in 55 patients (ages 25-72 years; mean, 50 years) with biopsy-proven primary (n = 42) or recurrent (n = 13) uterine cervical cancer. Both pharmacokinetic parameters were correlated to histologically determined microvessel density counts (factor VIII-related antigen) and other pathological tumor characteristics obtained from the operative specimens after radical surgery. In addition, the magnetic resonance and histological data were correlated to the presence or absence of lymphatic system involvement. Pharmacokinetic MRI-derived parameters (A and k21) increased with increasing histological microvessel density counts with r = 0.41 and 0.50, respectively. Lymphatic involvement was more comprehensibly assessed by the pharmacokinetic parameter k21 compared with histological microvessel density, resulting in a higher sensitivity, overall accuracy, and comparable specificity. Contrast-enhanced MRI parameters might prove to be applicable for estimation of tumor angiogenesis in uterine cervical cancer; thus, MRI may become an additional tool to characterize malignant progression in terms of lymphatic

  1. Smaller Absolute Quantities but Greater Relative Densities of Microvessels Are Associated with Cerebellar Degeneration in Lurcher Mice

    PubMed Central

    Kolinko, Yaroslav; Cendelin, Jan; Kralickova, Milena; Tonar, Zbynek

    2016-01-01

    Degenerative affections of nerve tissues are often accompanied by changes of vascularization. In this regard, not much is known about hereditary cerebellar degeneration. In this study, we compared the vascularity of the individual cerebellar components and the mesencephalon of 3-month-old wild type mice (n = 5) and Lurcher mutant mice, which represent a model of hereditary olivocerebellar degeneration (n = 5). Paraformaldehyde-fixed brains were processed into 18-μm thick serial sections with random orientation. Microvessels were visualized using polyclonal rabbit anti-laminin antibodies. Then, the stacks comprised of three 5-μm thick optical sections were recorded using systematic uniform random sampling. Stereological assessment was conducted based on photo-documentation. We found that each of the cerebellar components has its own features of vascularity. The greatest number and length of vessels were found in the granular layer; the number of vessels was lower in the molecular layer, and the lowest number of vessels was observed in the cerebellar nuclei corresponding with their low volume. Nevertheless, the nuclei had the greatest density of blood vessels. The reduction of cerebellum volume in the Lurcher mice was accompanied by a reduction in vascularization in the individual cerebellar components, mainly in the cortex. Moreover, despite the lower density of microvessels in the Lurcher mice compared with the wild type mice, the relative density of microvessels in the cerebellar cortex and nuclei was greater in Lurcher mice. The complete primary morphometric data, in the form of continuous variables, is included as a supplement. Mapping of the cerebellar and midbrain microvessels has explanatory potential for studies using mouse models of neurodegeneration. PMID:27147979

  2. Slit2 overexpression results in increased microvessel density and lesion size in mice with induced endometriosis.

    PubMed

    Guo, Sun-Wei; Zheng, Yu; Lu, Yuan; Liu, Xishi; Geng, Jian-Guo

    2013-03-01

    We recently reported that Slit/Roundabout (ROBO) 1 pathway may be a constituent biomarker for recurrence of endometriosis, likely through promoting angiogenesis. In this study, we sought to determine as whether Slit2 overexpression can facilitate angiogenesis, increase lesion size, and induce hyperalgesia in mice with induced endometriosis. We used 30 Slit2 transgenic (S) and 29 wild-type (W) mice and cross-transplanted endometrial fragments from S to W (group SW) and vice versa (group WS), and also within the S and W (groups SS and WW, respectively), into the peritoneal cavity, inducing endometriosis. We also performed a sham surgery within both S and W mice (groups Sm and Wm, respectively). The size of the ectopic implants, microvessel density (MVD) and immunoreactivity to ROBO1, and vascular endothelial cell growth factor (VEGF) in ectopic and eutopic endometrium, along with hotplate and tail-flick tests in all mice, were then evaluated. We found that the induction of endometriosis resulted in generalized hyperalgesia, which was unaffected by Slit2 overexpression. Slit2 overexpression did increase the lesion size significantly and correlated positively with the MVD in ectopic and eutopic endometrium. Slit2 expression levels appear to correlate with the MVD, but not with VEGF immunoreactivity, in ectopic endometrium. Consequently, we conclude that Slit2 may play an important role in angiogenesis in endometriosis. The increased angiogenesis, as measured by MVD, but not VEGF immunoreactivity, likely resulted in increased lesion size in induced endometriosis. Thus, SLIT2/ROBO1 pathway may be a potential therapeutic target for treating endometriosis.

  3. Study of the Impact of Uterine Artery Embolization (UAE) on Endometrial Microvessel Density (MVD) and Angiogenesis

    SciTech Connect

    Tan Guosheng; Xiang Xianhong; Guo Wenbo; Zhang Bing; Chen Wei; Yang Jianyong

    2013-08-01

    PurposeTo investigate the influence of uterine artery embolization (UAE) on endometrial microvessel density (MVD) and angiogenesis.MethodsSixty female guinea pigs were divided into two groups, the control group (n = 15) and the UAE treatment group (n = 45). In the UAE group, tris-acryl gelatin microspheres were used to generate embolization. Animals were further divided into three subgroups, A1, A2, and A3 (n = 15 for each subgroup), with uterine specimens collected at 7-15, 16-30, and 31-45 days after UAE, respectively. Immunostaining for factor VIII and CD105 was performed to identify total endometrial MVD (MVD{sub FVIII}) and CD105-positive angiogenesis (MVD{sub CD105}) at the indicated time points after UAE.ResultsQuantitative analysis revealed that MVD{sub FVIII} significantly decreased in the A1 (11.40 {+-} 2.76, p < 0.05) and A2 (15.37 {+-} 3.06, p < 0.05) groups compared to the control group (19.40 {+-} 2.50), and was restored to normal in the A3 group (18.77 {+-} 2.69). UAE caused a temporal up-regulation of MVD{sub CD105}-positive angiogenesis in the A1 group (9.33 {+-} 2.37, p < 0.05) and the A2 group (11.63 {+-} 1.56, p < 0.05) compared to the control group (7.12 {+-} 1.67), and the MVD{sub CD105} value returned to normal in the A3 group (8.07 {+-} 1.97).ConclusionUAE caused a temporal decrease in endometrial MVD that reversed over time as a result of the increase of CD105-positive angiogenesis. Although the UAE-induced reduction of endometrial MVD was reversible, its long-term effect on endometrial receptivity still needs further study.

  4. Quantitative evaluation of microvessel density using CD34 in clinical variants of ameloblastoma: An immunohistochemical study

    PubMed Central

    Pereira, Treville; Dodal, Shashibhushan; Tamgadge, Avinash; Bhalerao, Sudhir; Tamgadge, Sandhya

    2016-01-01

    Background: Odontogenic epithelium plays an important role in the histogenesis of odontogenic tumors of the jaws. Ameloblastomas, which arise from odontogenic epithelium, are considered benign with little tendency to metastasize. Tumors require an adequate supply of oxygen and a way to remove their waste products. This can be achieved by angiogenesis. In situ quantification of the microvessel density (MVD) is a usual method for assessing angiogenesis. Moreover, angiogenesis may differ in subtypes of ameloblastomas and could play a role in determining the pattern of tumor growth. Aim: The aim of the present study was to demonstrate the expression of cluster of differentiation (CD34) in variants of ameloblastomas and to correlate and compare their expression to the aggressive behavior. Materials and Methods: A retrospective cross-sectional study which included forty paraffin blocks was conducted after obtaining ethical committee clearance. Ten cases of pyogenic granuloma were used as a positive control and thirty cases were of solid multicystic ameloblastoma (SMA), unicystic ameloblastoma (UA) and desmoplastic ameloblastomas. Angiogenesis was assessed using CD34 antigen and was immunohistochemically localized. Statistical analysis was carried out for comparative analysis with the help of ANOVA test, Kolmogorov–Smirnov test and least significance difference test. Results: A significant correlation was obtained between the MVD of all the three variants, i.e., SMA, UA and desmoplastic ameloblastomas which was statistically significant (P < 0.05). Conclusion: Increased MVD in the three variants, i.e., SMA, UA and desmoplastic ameloblastoma seen in the present study could suggest that the angiogenesis has an important role in tumor progression and aggressiveness of ameloblastomas. PMID:27194862

  5. Clinical prognostic values of vascular endothelial growth factor, microvessel density,and p53 expression in esophageal carcinomas.

    PubMed Central

    Ahn, Myung-Ju; Jang, Se-Jin; Park, Yong-Wook; Choi, Jung-Hye; Oh, Ho-Suk; Lee, Chul-Burm; Paik, Hong-Kyu; Park, Chan-Kum

    2002-01-01

    Vascular endothelial growth factor (VEGF) is known to play a key role in tumor angiogenesis. The tumor-suppressor gene p53 has been thought to regulate VEGF. We investigated the effect of VEGF on esophageal carcinoma and the correlation between VEGF and p53. Tissue samples were taken from 81 patients with esophageal carcinoma after surgery. VEGF and p53 expressions were examined by immunohistochemical staining. Microvessels in the tumor stained for CD34 antigen were also counted. VEGF and p53 expressions were observed in 51.3% (41/80) and 51.9% (41/79), respectively. The microvessel density was 70.9+/-6.7 (mean+/-SE) in VEGF-positive group and 68.7+/-5.1 in VEGF-negative group. However, no correlation was noted between VEGF and p53 expression. Whereas the tumor size, nodal status, depth of invasions, and tumor stage were associated with poor overall survival, VEGF expression or p53 expression was not. These results indicate that VEGF and p53 are highly expressed in esophageal carcinomas. Since the VEGF expression is not correlated with the p53 expression, microvessel density or clinicopathological findings, further studies with other angiogenic molecules are needed to determine the role in esophageal carcinomas. PMID:11961303

  6. Development and Validation of a Histological Method to Measure Microvessel Density in Whole-Slide Images of Cancer Tissue.

    PubMed

    Marien, Koen M; Croons, Valerie; Waumans, Yannick; Sluydts, Ellen; De Schepper, Stefanie; Andries, Luc; Waelput, Wim; Fransen, Erik; Vermeulen, Peter B; Kockx, Mark M; De Meyer, Guido R Y

    2016-01-01

    Despite all efforts made to develop predictive biomarkers for antiangiogenic therapies, no unambiguous markers have been identified so far. This is due to among others the lack of standardized tests. This study presents an improved microvessel density quantification method in tumor tissue based on stereological principles and using whole-slide images. Vessels in tissue sections of different cancer types were stained for CD31 by an automated and validated immunohistochemical staining method. The stained slides were digitized with a digital slide scanner. Systematic, uniform, random sampling of the regions of interest on the whole-slide images was performed semi-automatically with the previously published applications AutoTag and AutoSnap. Subsequently, an unbiased counting grid was combined with the images generated with these scripts. Up to six independent observers counted microvessels in up to four cancer types: colorectal carcinoma, glioblastoma multiforme, ovarian carcinoma and renal cell carcinoma. At first, inter-observer variability was found to be unacceptable. However, after a series of consensus training sessions and interim statistical analysis, counting rules were modified and inter-observer concordance improved considerably. Every CD31-positive object was counted, with exclusion of suspected CD31-positive monocytes, macrophages and tumor cells. Furthermore, if interconnected, stained objects were considered a single vessel. Ten regions of interest were sufficient for accurate microvessel density measurements. Intra-observer and inter-observer variability were low (intraclass correlation coefficient > 0.7) if the observers were adequately trained. PMID:27583442

  7. Development and Validation of a Histological Method to Measure Microvessel Density in Whole-Slide Images of Cancer Tissue

    PubMed Central

    Croons, Valerie; Waumans, Yannick; Sluydts, Ellen; De Schepper, Stefanie; Andries, Luc; Waelput, Wim; Fransen, Erik; Vermeulen, Peter B.; Kockx, Mark M.; De Meyer, Guido R. Y.

    2016-01-01

    Despite all efforts made to develop predictive biomarkers for antiangiogenic therapies, no unambiguous markers have been identified so far. This is due to among others the lack of standardized tests. This study presents an improved microvessel density quantification method in tumor tissue based on stereological principles and using whole-slide images. Vessels in tissue sections of different cancer types were stained for CD31 by an automated and validated immunohistochemical staining method. The stained slides were digitized with a digital slide scanner. Systematic, uniform, random sampling of the regions of interest on the whole-slide images was performed semi-automatically with the previously published applications AutoTag and AutoSnap. Subsequently, an unbiased counting grid was combined with the images generated with these scripts. Up to six independent observers counted microvessels in up to four cancer types: colorectal carcinoma, glioblastoma multiforme, ovarian carcinoma and renal cell carcinoma. At first, inter-observer variability was found to be unacceptable. However, after a series of consensus training sessions and interim statistical analysis, counting rules were modified and inter-observer concordance improved considerably. Every CD31-positive object was counted, with exclusion of suspected CD31-positive monocytes, macrophages and tumor cells. Furthermore, if interconnected, stained objects were considered a single vessel. Ten regions of interest were sufficient for accurate microvessel density measurements. Intra-observer and inter-observer variability were low (intraclass correlation coefficient > 0.7) if the observers were adequately trained. PMID:27583442

  8. Endocan-expressing microvessel density as a prognostic factor for survival in human gastric cancer

    PubMed Central

    Chang, Yuan; Niu, Wei; Lian, Pei-Long; Wang, Xian-Qiang; Meng, Zhi-Xin; Liu, Yi; Zhao, Rui

    2016-01-01

    AIM: To investigate the expression of endocan in tumour vessels and the relationships between endocan and the expression of vascular endothelial growth factor (VEGF) and prognosis in gastric cancer. METHODS: This study included 142 patients with confirmed gastric cancer in a single cancer centre between 2008 and 2009. Clinicopathologic features were determined, and an immunohistochemical analysis of endocan-expressing microvessel density (MVD) (endocan-MVD), VEGF and vascular endothelial growth factor receptor 2 (VEGFR2) was performed. Potential relationships between endocan-MVD and clinicopathological variables were assessed using a Student’s t-test or an analysis of variance test. Spearman’s rank correlation was applied to evaluate the relationship between endocan-MVD and the expression of VEGF/VEGFR2. Long-term survival of these patients was analysed using univariate and multivariate analyses. RESULTS: Positive staining of endocan was observed in most of the gastric cancer tissues (108/142) and in fewer of the normal gastric tissues. Endocan-MVD was not associated with gender or histological type (P > 0.05), while endocan-MVD was associated with tumour size, Borrmann type, tumour differentiation, tumour invasion, lymph node metastasis and TNM stage (P < 0.05). According to the Spearman’s rank correlation analysis, endocan-MVD had a positive correlation with VEGF (r = 0.167, P = 0.047) and VEGFR2 (r = 0.410, P = 0.000). The univariate analysis with a log-rank test indicated that the patients with a high level of endocan-MVD had a significantly poorer overall survival rate than those with a low level of endocan-MVD (17.9% vs 64.0%, P = 0.000). The multivariate analysis showed that a high level of endocan-MVD was a valuable prognostic factor. CONCLUSION: Endocan-MVD significantly correlates with the expression of VEGF and VEGFR2 and is a valuable prognostic factor for survival in human gastric cancer. PMID:27340359

  9. Continuous representation of tumor microvessel density and detection of angiogenic hotspots in histological whole-slide images.

    PubMed

    Kather, Jakob Nikolas; Marx, Alexander; Reyes-Aldasoro, Constantino Carlos; Schad, Lothar R; Zöllner, Frank Gerrit; Weis, Cleo-Aron

    2015-08-01

    Blood vessels in solid tumors are not randomly distributed, but are clustered in angiogenic hotspots. Tumor microvessel density (MVD) within these hotspots correlates with patient survival and is widely used both in diagnostic routine and in clinical trials. Still, these hotspots are usually subjectively defined. There is no unbiased, continuous and explicit representation of tumor vessel distribution in histological whole slide images. This shortcoming distorts angiogenesis measurements and may account for ambiguous results in the literature. In the present study, we describe and evaluate a new method that eliminates this bias and makes angiogenesis quantification more objective and more efficient. Our approach involves automatic slide scanning, automatic image analysis and spatial statistical analysis. By comparing a continuous MVD function of the actual sample to random point patterns, we introduce an objective criterion for hotspot detection: An angiogenic hotspot is defined as a clustering of blood vessels that is very unlikely to occur randomly. We evaluate the proposed method in N=11 images of human colorectal carcinoma samples and compare the results to a blinded human observer. For the first time, we demonstrate the existence of statistically significant hotspots in tumor images and provide a tool to accurately detect these hotspots.

  10. Continuous representation of tumor microvessel density and detection of angiogenic hotspots in histological whole-slide images

    PubMed Central

    Kather, Jakob Nikolas; Marx, Alexander; Reyes-Aldasoro, Constantino Carlos; Schad, Lothar R.; Zöllner, Frank Gerrit; Weis, Cleo-Aron

    2015-01-01

    Blood vessels in solid tumors are not randomly distributed, but are clustered in angiogenic hotspots. Tumor microvessel density (MVD) within these hotspots correlates with patient survival and is widely used both in diagnostic routine and in clinical trials. Still, these hotspots are usually subjectively defined. There is no unbiased, continuous and explicit representation of tumor vessel distribution in histological whole slide images. This shortcoming distorts angiogenesis measurements and may account for ambiguous results in the literature. In the present study, we describe and evaluate a new method that eliminates this bias and makes angiogenesis quantification more objective and more efficient. Our approach involves automatic slide scanning, automatic image analysis and spatial statistical analysis. By comparing a continuous MVD function of the actual sample to random point patterns, we introduce an objective criterion for hotspot detection: An angiogenic hotspot is defined as a clustering of blood vessels that is very unlikely to occur randomly. We evaluate the proposed method in N=11 images of human colorectal carcinoma samples and compare the results to a blinded human observer. For the first time, we demonstrate the existence of statistically significant hotspots in tumor images and provide a tool to accurately detect these hotspots. PMID:26061817

  11. Microvessel density and endothelial cell proliferation levels in colorectal liver metastases from patients given neo-adjuvant cytotoxic chemotherapy and bevacizumab.

    PubMed

    Eefsen, Rikke Løvendahl; Engelholm, Lars; Willemoe, Gro L; Van den Eynden, Gert G; Laerum, Ole Didrik; Christensen, Ib Jarle; Rolff, Hans Christian; Høyer-Hansen, Gunilla; Osterlind, Kell; Vainer, Ben; Illemann, Martin

    2016-04-01

    The treatment of patients with colorectal liver metastasis has improved significantly and first line therapy is often combined chemotherapy and bevacizumab, although it is unknown who responds to this regimen. Colorectal liver metastases grow in different histological growth patterns showing differences in angiogenesis. To identify possible response markers, histological markers of angiogenesis were assessed. Patients who underwent resection of colorectal liver metastasis at Rigshospitalet, Copenhagen, Denmark from 2007 to 2011 were included (n = 254) including untreated and patients treated with chemotherapy or chemotherapy plus bevacizumab. The resected liver metastases were characterised with respect to growth pattern, endothelial and tumour cell proliferation as well as microvessel density and tumour regression. Tumour regression grade of liver metastases differed significantly between untreated/chemotherapy treated patients in comparison to chemotherapy plus bevacizumab treated patients (both p < 0.0001). Microvessel density was decreased in liver metastases from patients treated with bevacizumab in comparison to those from untreated/chemotherapy-treated patients (p = 0.006/p = 0.002). Tumour cell proliferation assessed by Ki67 expression correlated to a shorter recurrence free survival in the total patient cohort. In conclusion, liver metastases from patients treated with neo-adjuvant chemotherapy and bevacizumab had significantly lower microvessel densities and tumour regression grades when compared to liver metastases from untreated or chemotherapy treated patients. This may indicate that bevacizumab treatment results in altered vascular biology and tumour viability, with possible tumour reducing effect.

  12. Hypoxia-Related Marker GLUT-1, CAIX, Proliferative Index and Microvessel Density in Canine Oral Malignant Neoplasia

    PubMed Central

    Meier, Valeria; Guscetti, Franco; Roos, Malgorzata; Ohlerth, Stefanie; Pruschy, Martin; Rohrer Bley, Carla

    2016-01-01

    For various types of tumor therapy, it is suggested that co-targeting of tumor microenvironment, mainly tumor vasculature, mediates tumor response mechanisms. Immunohistochemistry for glucose transporter-1 (GLUT-1), carbonic anhydrase-IX (CAIX), Ki-67, and von Willebrand factor VIII for microvessel density (MVD) were performed on formalin-fixed paraffin-embedded samples of canine oral malignant neoplasms. Polarographic oxygen measurements (median pO2) and perfusion data via contrast-enhanced power Doppler ultrasound (median vascularity, median blood volume) provided additional information. Ninety-two samples were analyzed: sarcomas (n = 32), carcinomas (n = 30), and malignant melanomas (n = 30). Polarographic oxygen and perfusion data was available in 22.8% (sarcomas n = 9, carcinomas n = 7, melanomas n = 5), and 27.1% (sarcomas n = 10, carcinomas n = 8, melanomas n = 7) of cases, respectively. GLUT-1 expression was detected in 46.7% of all samples, and was generally weak. CAIX expression was found in 34.8% of all samples. Median Ki-67 score and MVD count was 19% and 17, respectively. The evaluation of the GLUT-1 score and continuous data showed significantly lower GLUT-1 levels in sarcomas (mean 5.1%, SD 6.2) versus carcinomas and melanomas (mean 16.5%/ 19.0%, SD 17.3/ 20.9, p = 0.001). The expression of CAIX correlated mildly positively with GLUT-1 (p = 0.018, rho = 0.250) as well as with Ki-67 (p = 0.014, rho = 0.295). MVD showed a significantly lower level in melanomas (mean 12.6, SD 7.7) versus sarcomas and carcinomas (mean 21.8/ 26.9, SD 13.0/20.4, p = 0.001). Median vascularity and blood volume were significantly lower in sarcomas (mean 10.4%, SD 11.0, and mean 6.3%, SD 6.5, respectively) versus carcinomas (mean 39.2%, SD 16.4 and mean 33.0%, SD 25.6, respectively) and melanomas (mean 36.0%, SD 18.3, and 31.5%, SD 24.5). Between the 3 histological groups, there was neither a significant difference in the GLUT-1 and CAIX score and continuous data, nor the Ki

  13. The prognostic value of histopathologic grading parameters and microvessel density in patients with early squamous cell carcinoma of the uterine cervix.

    PubMed

    Graflund, Marianne; Sorbe, B; Hussein, A; Bryne, M; Karlsson, M

    2002-01-01

    The purpose of this study was to investigate the prognostic importance of clinical and histopathologic factors, including malignancy grading systems (MGS), partial index (PI), invasive front grading (IFG), and microvessel density. A complete geographic series of 172 early stage (FIGO I-II) cervical carcinomas treated by Wertheim-Meigs surgery during the period 1965-1990 was studied. The patients were followed up for at least 10 years. Significant prognostic factors for disease-free survival were lymph node status (P < 0.0000001), radical surgical margins (P = 0.00003), and tumor size (P = 0.008). In a multivariate Cox analysis it was shown that lymph node status was the single most important prognostic factor with regard to disease-free survival. The total MGS and the PI scores were highly significantly (P = 0.0001) associated with pelvic lymph node metastases and disease-free survival rate in squamous cell carcinomas. The MGS and the PI systems were superior to the IFG system in predicting lymph node metastases. The total IFG score was also a statistically highly significant (P = 0.003) prognostic factor with regard to disease-free survival in both univariate and multivariate analyses. Microvessel density was a nonsignificant prognostic factor. There was a highly significant (P = 0.002) association between vascular space invasion of tumor cells and the presence of lymph node metastases. In conclusion, histopathologic malignancy grading systems provide valuable prognostic information in patients with early stage squamous cell carcinomas of the uterine cervix. PMID:11860534

  14. Synthesis of oxadiazole-morpholine derivatives and manifestation of the repressed CD31 Microvessel Density (MVD) as tumoral angiogenic parameters in Dalton's Lymphoma.

    PubMed

    Al-Ghorbani, Mohammed; Vigneshwaran, V; Ranganatha, V Lakshmi; Prabhakar, B T; Khanum, Shaukath Ara

    2015-06-01

    A series of oxadiazole derivatives possessing morpholine 6a-l were synthesized by nucleophilic substitution reaction of key intermediates [1,3,4]-oxadiazole-2-thiol derivatives 5a-l with 4-(2-chloroethyl) morpholine. Compounds 6a-l were evaluated for their in vitro and in vivo antitumor potential in Dalton's Lymphoma Ascites (DLA) tumor cells. Among 6a-l series, compound 6a with concentration ∼8.5μM have shown extensive cytotoxicity in vitro and 85% reduction in tumor volume in vivo, attributing an excellent anti-proliferative capability towards the cancer cells. Compound 6a has extensively inhibited the Microvessel Density (MVD) or tumoral neovasculature which was evident from the CD31 immuno staining and peritoneal H&E staining. The major reason for the antiproliferative activity of compound 6a was due to the repression of tumor vasculature. PMID:26005956

  15. Increased expression of CD146 and microvessel density (MVD) in invasive micropapillary carcinoma of the breast: Comparative study with invasive ductal carcinoma-not otherwise specified.

    PubMed

    Li, Weidong; Yang, Dongling; Wang, Shuling; Guo, Xiaojing; Lang, Ronggang; Fan, Yu; Gu, Feng; Zhang, Xinmin; Niu, Yun; Yan, Xiyun; Fu, Li

    2011-12-15

    Invasive micropapillary carcinoma (IMPC) is a rare variant of ductal carcinoma of the breast, and is characterized by a high metastatic potential and an aggressive clinical course. Studies of CD146 expression and function in breast cancer remain scarce. The aim of this study was to evaluate the role of CD146 and microvessel density (MVD) in breast IMPC. CD146 mRNA expression and immunohistochemistry for CD146 and MVD measured by CD31 were assessed in 82 cases of IMPC and 137 cases of invasive ductal carcinoma, not otherwise specified (IDC-NOS). The mRNA level of CD146 in cancer specimens was higher in IMPC than in IDC-NOS. CD146 expression in tumor cells was up-regulated in IMPC as compared with that in IDC-NOS, and was positively correlated with histological grade, ER, PR status, and P53 expression in IMPC and IDC-NOS. CD146 expression in vascular endothelial cells was significantly higher than that in IDC, and was positively correlated with tumor progression in IMPC and IDC-NOS. MVD in IMPC was significantly higher than that in IDC. CD146 expression in tumor cells was positively correlated with that in vascular endothelial cells of IMPC and IDC-NOS. The association of CD146 expression with MVD and its correlation with progression in breast carcinoma indicated that CD146 is a potentially useful prognostic marker for breast cancer. CD146 could be a new drug target in the treatment of breast cancer.

  16. The Role of Lymphocyte to Monocyte Ratio, Microvessel Density and HiGH CD44 Tumor Cell Expression in Non Hodgkin Lymphomas.

    PubMed

    Jelicic, Jelena; Balint, Milena Todorovic; Jovanovic, Maja Perunicic; Boricic, Novica; Micev, Marjan; Stojsic, Jelena; Antic, Darko; Andjelic, Bosko; Bila, Jelena; Balint, Bela; Pavlovic, Sonja; Mihaljevic, Biljana

    2016-07-01

    Prognostic significance of immune microenvironment has been emphasized using the most advanced analysis, with consecutive attempts to reveal prognostic impact of this findings. The aim of this study was to compare and define prognostic significance of clinical parameters, microvessel density (MVD) in tumour tissue and expression of CD44s as adhesive molecule on tumour cells in diffuse large B cell lymphoma-DLBCL, primary central nervous system DLBCL-CNS DLBCL and follicular lymphoma-FL. A total of 202 histopathological samples (115 DLBCL/65 FL/22 CNS DLBCL) were evaluated. Overall response (complete/partial remission) was achieved in 81.3 % DLBCL patients, 81.8 % primary CNS DLBCL and 92.3 % FL. Absolute lymphocyte count-ALC/Absolute monocyte count-AMC >2.6 in DLBCL and ALC/AMC ≥ 4.7 in FL were associated with better event-free survival (EFS) and overall survival (OS) (p < 0.05). In DLBCL, MVD > 42 blood vessels/0.36 mm(2) correlated with primary resistant disease (p < 0.0001), poorer EFS and OS (p = 0.014). High CD44s expression in FL correlated with inferior EFS and OS (p < 0.01). In DLBCL, multivariate Cox regression analysis showed that ALC/AMC was independent parameter that affected OS (HR 3.27, 95 % CI 1.51-7.09, p = 0.003) along with the NCCN-IPI (HR 1.39, 95 % CI 1.08-1.79, p = 0.01). Furthermore, in FL, ALC/AMC mostly influenced OS (HR 5.21, 95 % CI 1.17-23.21, p = 0.03), followed with the FLIPI (HR 3.98, 95 % CI 1.06-14.95, p = 0.041). In DLBCL and FL, ALC/AMC is simple and robust tool that is, with current prognostic scores, able to define long-term survival and identify patients with inferior outcome. The introduction of immunochemotherapy might altered the prognostic significance of microenvionmental biomarkers (MVD and CD44s).

  17. Adrenergic receptors on cerebral microvessels in control and Parkinsonian subjects

    SciTech Connect

    Cash, R.; Lasbennes, F.; Sercombe, R.; Seylaz, J.; Agid, Y.

    1985-08-12

    The binding of adrenergic ligands (/sup 3/H-prazosin, /sup 3/H-clonidine, /sup 3/H-dihydroalprenolol) was studied on a preparation of cerebral microvessels in the prefrontal cortex and putamen of control and Parkinsonian subjects. The adrenergic receptor density in microvessels of control patients was less than 0.5% and 3.3% respectively of the total binding. A significant decrease in the number of alpha-1 binding sites was observed on microvessels in the putamen of patients with Parkinson's disease. 22 references, 2 tables.

  18. Developmental expression of the glucose transporter in brain microvessels

    SciTech Connect

    Hohimer, A.R.; Bissonnette, J.M.; Machida, C.M. )

    1990-02-26

    Brain microvessels were isolated from late gestation fetal (55-68 days), newborn (5-9 day old) and adult guinea pigs. Glucose transport was assessed by measuring the initial uptake of ({sup 3}H)-2-deoxy-D-glucose, a glucose analog that is transported and phosphorylated but not further metabolized. At 22C and substrate concentrations of 40 mM, uptakes were linear for 8 minutes. The data reported here were uptakes over the first 2 minutes. 2-deoxy-D-glucose uptake was 3.5 fold higher in newborn microvessels, 99.5{+-}18.4 (SEM) fmols/mg protein/2 minutes, compared to fetal, 27.8{+-}7.9. The number of glucose transporters was estimated using the ({sup 3}H) cytochalasin B which can be displaced by D-glucose (250 mM). Binding at 35 nM cytochalasin B was higher in newborn brain microvessels (8.2{+-}1.6 pmole/mg protein) than in fetal (3.4{+-}1.1) or adult (2.8{+-}0.6) brain microvessels. Initial RNA blot experiments using a cDNA for the brain/erythrocyte (HepG2) glucose transporter show increased expression in newborn microvessels compared to the fetus or the adult. The authors conclude that the brain microvessel glucose transporter is increased in the newborn period.

  19. Study of microvascular structure in keloid and hypertrophic scars: density of microvessels and the efficacy of three-dimensional vascular imaging.

    PubMed

    Kurokawa, Norifumi; Ueda, Koichi; Tsuji, Motomu

    2010-12-01

    We have investigated the blood vessels in keloids and hypertrophic scars, both morphologically and statistically. We also tried to construct three-dimensional images of blood vessels in a keloid and hypertrophic scar to clarify the vascular patterns. Keloids (n = 16) and hypertrophic scars (n = 12) were stained with haematoxylin and eosin, and immunostained with anti-CD31 antibody. The capillary density (number/1.0 mm(2)) and length of the major and minor axes were measured, and the major:minor axis ratio was calculated. Eighty serial sections were prepared from the preparations. Using image preparation software (Realia, INTAGE), the 80 input images were superimposed to construct a three-dimensional image of blood vessels in the tissue. We initially succeeded in constructing three-dimensional images of blood vessels in a keloid and hypertrophic scar. By statistical analysis of the vascular density and morphology, we clarified that there were fewer capillaries in keloids than in hypertrophic scars (p < 0.01), and that the vascular lumen was flattened. Capillaries in the central region of keloids tended to flat, compared with those in the marginal region. Three-dimensional images suggested that there was no microvascular communication in keloids; there was also an inadequate blood supply in keloid tissue. These findings may be a result of the growth of collagen and fibroblasts with keloid maturation.

  20. Blood flow and permeability in microvessels

    NASA Astrophysics Data System (ADS)

    Sugihara-Seki, Masako; Fu, Bingmei M.

    2005-07-01

    The mechanics of blood flow in microvessels and microvessel permeability are reviewed. In the first part, characteristics of blood flow in vivo and in vitro are described from a fluid-mechanical point of view, and mathematical models for blood flow in microvessels are presented. Possible causes of the increased flow resistance obtained in vivo compared to in vitro are examined, including the effects of irregularities of vessel lumen, the presence of endothelial surface glycocalyx and white blood cells. In the second part, the ultrastructural pathways and mechanisms whereby endothelial cells and the clefts between the cells modulate microvessel permeability to water and solutes are introduced. Previous and current models for microvessel permeability to water and solutes are reviewed. These models examine the role of structural components of interendothelial cleft, such as junction strands and surface glycocalyx, in the determination of water and solute transport across the microvessel walls. Transport models in the tissue space surrounding the microvessel are also described.

  1. Inosculation and perfusion of pre-vascularized tissue patches containing aligned human microvessels after myocardial infarction.

    PubMed

    Riemenschneider, Sonja B; Mattia, Donald J; Wendel, Jacqueline S; Schaefer, Jeremy A; Ye, Lei; Guzman, Pilar A; Tranquillo, Robert T

    2016-08-01

    A major goal of tissue engineering is the creation of pre-vascularized tissues that have a high density of organized microvessels that can be rapidly perfused following implantation. This is especially critical for highly metabolic tissues like myocardium, where a thick myocardial engineered tissue would require rapid perfusion within the first several days to survive transplantation. In the present work, tissue patches containing human microvessels that were either randomly oriented or aligned were placed acutely on rat hearts post-infarction and for each case it was determined whether rapid inosculation could occur and perfusion of the patch could be maintained for 6 days in an infarct environment. Patches containing self-assembled microvessels were formed by co-entrapment of human blood outgrowth endothelial cells and human pericytes in fibrin gel. Cell-induced gel contraction was mechanically-constrained resulting in samples with high densities of microvessels that were either randomly oriented (with 420 ± 140 lumens/mm(2)) or uniaxially aligned (with 940 ± 240 lumens/mm(2)) at the time of implantation. These patches were sutured onto the epicardial surface of the hearts of athymic rats following permanent ligation of the left anterior descending artery. In both aligned and randomly oriented microvessel patches, inosculation occurred and perfusion of the transplanted human microvessels was maintained, proving the in vivo vascularization potential of these engineered tissues. No difference was found in the number of human microvessels that were perfused in the randomly oriented (111 ± 75 perfused lumens/mm(2)) and aligned (173 ± 97 perfused lumens/mm(2)) patches. Our results demonstrate that tissue patches containing a high density of either aligned or randomly oriented human pre-formed microvessels achieve rapid perfusion in the myocardial infarct environment - a necessary first-step toward the creation of a thick, perfusable heart patch.

  2. A mathematical model for understanding fluid flow through engineered tissues containing microvessels.

    PubMed

    Morin, Kristen T; Lenz, Michelle S; Labat, Caroline A; Tranquillo, Robert T

    2015-05-01

    Knowledge is limited about fluid flow in tissues containing engineered microvessels, which can be substantially different in topology than native capillary networks. A need exists for a computational model that allows for flow through tissues dense in nonpercolating and possibly nonperfusable microvessels to be efficiently evaluated. A finite difference (FD) model based on Poiseuille flow through a distribution of straight tubes acting as point sources and sinks, and Darcy flow through the interstitium, was developed to describe fluid flow through a tissue containing engineered microvessels. Accuracy of the FD model was assessed by comparison to a finite element (FE) model for the case of a single tube. Because the case of interest is a tissue with microvessels aligned with the flow, accuracy was also assessed in depth for a corresponding 2D FD model. The potential utility of the 2D FD model was then explored by correlating metrics of flow through the model tissue to microvessel morphometric properties. The results indicate that the model can predict the density of perfused microvessels based on parameters that can be easily measured. PMID:25424905

  3. Shockwave compression of Argon gas at several initial densities

    NASA Astrophysics Data System (ADS)

    Dattelbaum, Dana; Goodwin, Peter; Garcia, Daniel; Gustavsen, Richard; Lang, John; Aslam, Tariq; Sheffield, Stephen; Gibson, Lloyd; Morris, John; Los Alamos National Laboratory Team

    2015-06-01

    Experimental data of the principal Hugoniot locus of gas-phase noble gases are rare. The majority of Hugoniot data is either from shock tube experiments on low-pressure gases or from plate impact experiments on cryogenic, liquefied gases. In both cases, physics regarding shock compressibility, thresholds for the on-set of ionization, and dissociation chemistry are difficult to infer for gases at intermediate densities. We have developed an experimental target for gas gun-driven plate impact experiments on gases at initial pressures between 200-1000 psi. Using optical velocimetry, we directly determine shock and particle velocities on the principal Hugoniot locus, as well as clearly differentiate ionization thresholds. The target design also results in multiply shocking the gas in a quasi-isentropic fashion yielding off-Hugoniot compression data. Using an impactor with higher impedance than the drive plate, we are able to achieve initial particle velocities well in excess of the impactor velocities. We will describe the results of plate impact experiments on Ar with initial densities between 0.02-0.05 g/cm3. By coupling optical fibers to the targets, we have measured the time-resolved optical emission, spectrally-resolved with a spectrometer coupled to an optical streak camera, and with a 5-color optical pyrometer for temperature determination. The experimental results are compared with hydrodynamic simulations using ideal gas and Sesame tabular equations of state.

  4. Relationship between Exploding Bridgewire & Spark Initiation of Low Density PETN

    NASA Astrophysics Data System (ADS)

    Lee, Elizabeth; Drake, Rod

    2015-06-01

    Recent work has shown that the energy delivered after bridgewire burst affects the function time of an EBW detonator. The spark which is formed post bridgewire burst is the means by which the remaining fireset energy is delivered into the detonator. Therefore, by studying the characteristics of spark-gap detonators insight into the contribution of spark initiation to the functioning of EBW detonators may be achieved. Spark initiation of low density explosives consists of; (i) spark formation, (ii) spark interaction with the bed, and (iii) ignition and growth of reaction. Experiments were performed in which beds of an inert simulant were used to study the formation and propagation of sparks. The effect of the spark on inert porous beds was studied over a limited delivered energy range. The disruption of the bed was found to be dependent on the particle size / pore structure of the bed. The effect of spark initiation on a low density PETN bed was then examined, the relationship between delivered energy and function time was found to be the same as for EBW detonators. This necessitated the development of electrical diagnostic techniques to measure the energy delivered to the spark.

  5. The expression of non-mast histamine in tumor associated microvessels in human colorectal cancers.

    PubMed

    Cui, Jing; Xu, Gang; Liu, Jinzhong; Pang, Zhigang; Florholmen, Jon; Cui, Guanglin

    2013-04-01

    Angiogenesis is essential for the growth, expansion and metastasis of human colorectal cancers (CRCs). Histamine produced by mast cells is a potent proangiogenic factor. However, the significance of non-mast cell expressing histamine in the tumor microenvironment remains unknown. In this study, we evaluated the histamine positive microvessels with the specific marker for biosynthesis of histamine L-histidine decarboxylase (HDC) in the CRC tumor microenvironment. The relationship between HDC positive microvessel density (HDC-MVD) and clinical pathological parameters was assessed. The results revealed that HDC-MVD in the tumor microenvironment of CRCs was significantly increased as compared with the controls. CRC patients with lymph node invasion had a particularly higher density of HDC-MVD than those without. The density of HDC-MVD accounted for ~79 % of CD34 positive MVD in CRCs and double IHC analysis demonstrated that these HDC positive microvessels were mostly CD34 positive microvessels and with a high proliferative activity. Our results suggest that histamine expressed in microvessels could be an additional cellular source and involved in the cancer invasion through promoting angiogenesis in human CRCs.

  6. Neurotransmitter Receptor Binding in Bovine Cerebral Microvessels

    NASA Astrophysics Data System (ADS)

    Peroutka, Stephen J.; Moskowitz, Michael A.; Reinhard, John F.; Synder, Solomon H.

    1980-05-01

    Purified preparations of microvessels from bovine cerebral cortex contain substantial levels of alpha-adrenergic, beta-adrenergic, and histamine 1 receptor binding sites but only negligible serotonin, muscarinic cholinergic, opiate, and benzodiazepine receptor binding. Norepinephrine and histamine may be endogenous regulators of the cerebral microcirculation at the observed receptors.

  7. Chronic ethanol treatment changes the number of beta-receptors in rat brain microvessels

    SciTech Connect

    Lucchi, L.; Cazzaniga, A.; Picotti, G.B.; Covelli, V.; Magnoni, M.S.; Borriero, L.; Spano, P.F.; Trabucchi, M.

    1984-01-01

    The effect of chronic ethanol consumption on the binding (125I)-iodohydroxybenzylpindolol to beta-adrenergic receptors in rat brain microvessels has been studied. The results show that chronic ethanol treatment increases the number of beta-receptors present in brain microvessels without changing the binding affinity of the binding site for the beta-adrenoceptor ligand. This effect is apparently not associated with changes in peripheral adrenergic tone, since no differences in platelet epinephrine or norepinephrine concentrations were found between ethanol-treated and control animals. An increase in beta-receptor density in brain microvessels might contribute to the alterations of cerebral blood flow and oxygen consumption reported during chronic ethanol intoxication.

  8. Structural and functional bases of laser-microvessels interaction

    NASA Astrophysics Data System (ADS)

    Kozlov, Valentine I.; Terman, Oleg A.; Builin, Vitalij; Lebedeva, Natalia A.; Samoilov, Nickolai

    1993-07-01

    Structural and functional microcirculatory changes in tissues and organs (muscles, liver, derma, epinephros, brain cortex) under various dosages and powers of laser irradiation in the red (633 nm) and near infrared (890 nm) spectrum regions have been studied in experiments and clinic. In case of nonsensitized tissues the `photoactivation' range of power densities and doses of laser irradiation has been established. We have identified a short-term reaction of microvessels and a long-term reaction (adaptation). The former consists of intensification of microcirculation and metabolism rise in parenchymatous cells; the latter is connected with neoangiogenesis acceleration. The intensification of the blood microcirculation includes a dilation of microvessels of all orders, an amplification of arteriolar vasomotions and an opening of `reserved' capillaries. Data on the structural reconstruction of myocytes and endotheliocytes have shown that the high differential parenchymatous cells and its membrane structures are sensitive to low energy laser irradiation and, on the other hand, under low energy laser irradiation there is an activation of synthetic processes in the cells. Thus, during the laser-tissue interaction in such complex system as human organism the microcirculation plays the key role among the other systems.

  9. Implanted Microvessels Progress through Distinct Neovascularization Phenotypes

    PubMed Central

    Nunes, Sara S.; Greer, Kevin A.; Stiening, Chad M.; Chen, Helen YS.; Kidd, Kameha R.; Schwartz, Mark A; Sullivan, Chris J.; Rekapally, Harish; Hoying, James B.

    2009-01-01

    We have previously demonstrated that implanted microvessels form a new microcirculation with minimal host-derived vessel investment. Our objective was to define the vascular phenotypes present during neovascularization in these implants and identify post-angiogenesis events. Morphological, functional and transcriptional assessments identified three distinct vascular phenotypes in the implants: sprouting angiogenesis, neovascular remodeling, and network maturation. A sprouting angiogenic phenotype appeared first, characterized by high proliferation and low mural cell coverage. This was followed by a neovascular remodeling phenotype characterized by a perfused, poorly organized neovascular network, reduced proliferation, and re-associated mural cells. The last phenotype included a vascular network organized into a stereotypical tree structure containing vessels with normal perivascular cell associations. In addition, proliferation was low and was restricted to the walls of larger microvessels. The transition from angiogenesis to neovascular remodeling coincided with the appearance of blood flow in the implant neovasculature. Analysis of vascular-specific and global gene expression indicates that the intermediate, neovascular remodeling phenotype is transcriptionally distinct from the other two phenotypes. Therefore, this vascular phenotype likely is not simply a transitional phenotype but a distinct vascular phenotype involving unique cellular and vascular processes. Furthermore, this neovascular remodeling phase may be a normal aspect of the general neovascularization process. Given that this phenotype is arguably dysfunctional, many of the microvasculatures present within compromised or diseased tissues may not represent a failure to progress appropriately through a normally occurring neovascularization phenotype. PMID:19833141

  10. Micropatterning and Assembly of 3D Microvessels.

    PubMed

    Roberts, Meredith A; Kotha, Surya S; Phong, Kiet T; Zheng, Ying

    2016-01-01

    In vitro platforms to study endothelial cells and vascular biology are largely limited to 2D endothelial cell culture, flow chambers with polymer or glass based substrates, and hydrogel-based tube formation assays. These assays, while informative, do not recapitulate lumen geometry, proper extracellular matrix, and multi-cellular proximity, which play key roles in modulating vascular function. This manuscript describes an injection molding method to generate engineered vessels with diameters on the order of 100 µm. Microvessels are fabricated by seeding endothelial cells in a microfluidic channel embedded within a native type I collagen hydrogel. By incorporating parenchymal cells within the collagen matrix prior to channel formation, specific tissue microenvironments can be modeled and studied. Additional modulations of hydrodynamic properties and media composition allow for control of complex vascular function within the desired microenvironment. This platform allows for the study of perivascular cell recruitment, blood-endothelium interactions, flow response, and tissue-microvascular interactions. Engineered microvessels offer the ability to isolate the influence from individual components of a vascular niche and precisely control its chemical, mechanical, and biological properties to study vascular biology in both health and disease. PMID:27685466

  11. Peculiarities of lymph flow in microvessels

    NASA Astrophysics Data System (ADS)

    Galanzha, Ekateryna I.; Brill, Gregory E.; Ulyanov, Sergey S.; Tuchin, Valery V.; Solov'eva, Anastasiya V.; Sedykh, Alexey V.

    2000-05-01

    In the present study the characteristics of lymph flow in microvessels are investigated in vivo by the speckle- interferometrical and biomicroscopic methods. Two parameters of the lymph flow velocity are determined. The first frequency-weighted spectral moment of Doppler signal (M1) was calculated. This parameter is proportional to lymph flow velocity. In the same regions of lymphatics the velocity of translational motion of the signal lymphocytes in the flow is assessed. The value of velocity and the parameter M1 essentially varied. The temporary dynamics of M1 indicated that the lymph flow had the alternating- translational character. Simultaneously the diameter of lymph microvessel, the amplitude and the rate of phasic contraction and the rate of valve functioning are registered. NG-nitro-L-arginine (L-NNA, 10-4 M), an inhibitor of nitric oxide synthase, is topically applied during 15 min. The application of L-NNA provoked the modulation of alternating-translational motion of lymph flow, the changes of diameters and rate of valve function and the stimulating of phasic contractions and the correlation between parameters of lymph microcirculation.

  12. Presence of norepinephrine and related enzymes in isolated brain microvessels.

    PubMed Central

    Lai, F M; Udenfriend, S; Spector, S

    1975-01-01

    Norepinephrine and the enzymes involved in its synthesis and degradation were found to be associated with isolated brain microvessels. The significance of these results are discussed with respect to adrenergic innervation of the cerebral microvessels and thereby neural regulation of the cerebral microcirculation. Images PMID:678

  13. Quantification of microvessels in canine lymph nodes.

    PubMed

    Tonar, Zbynĕk; Egger, Gunter F; Witter, Kirsti; Wolfesberger, Birgitt

    2008-10-01

    Quantification of microvessels in tumors is mostly based on counts of vessel profiles in tumor hot spots. Drawbacks of this method include low reproducibility and large interobserver variance, mainly as a result of individual differences in sampling of image fields for analysis. Our aim was to test an unbiased method for quantifying microvessels in healthy and tumorous lymph nodes of dogs. The endothelium of blood vessels was detected in paraffin sections by a combination of immunohistochemistry (von Willebrand factor) and lectin histochemistry (wheat germ agglutinin) in comparison with detection of basal laminae by laminin immunohistochemistry or silver impregnation. Systematic uniform random sampling of 50 image fields was performed during photo-documentation. An unbiased counting frame (area 113,600 microm(2)) was applied to each micrograph. The total area sampled from each node was 5.68 mm(2). Vessel profiles were counted according to stereological counting rules. Inter- and intraobserver variabilities were tested. The application of systematic uniform random sampling was compared with the counting of vessel profiles in hot spots. The unbiased estimate of the number of vessel profiles per unit area ranged from 100.5 +/- 44.0/mm(2) to 442.6 +/- 102.5/mm(2) in contrast to 264 +/- 72.2/mm(2) to 771.0 +/- 108.2/mm(2) in hot spots. The advantage of using systematic uniform random sampling is its reproducibility, with reasonable interobserver and low intraobserver variance. This method also allows for the possibility of using archival material, because staining quality is not limiting as it is for image analysis, and artifacts can easily be excluded. However, this method is comparatively time-consuming.

  14. Effect of osmolarity on potassium transport in isolated cerebral microvessels

    SciTech Connect

    Lin, J.D.

    1988-01-01

    Potassium transport in microvessels isolated from rat brain by a technique involving density gradient centrifugation was studied in HEPES buffer solutions of varying osmolarity from 200 to 420 mosmols, containing different concentration of sodium chloride, choline chloride, or sodium nitrate. The flux of /sup 86/Rb into and out of the endothelial cells was estimated. Potassium influx was very sensitive to the osmolarity of the medium. Ouabain-insensitive K-component was reduced in hypotonic medium and was increased in medium made hypertonic with sodium chloride or mannitol. Choline chloride replacement caused a large reduction in K influx. Potassium influx was significant decrease when nitrate is substituted for chloride ion in isotonic and hypertonic media, whereas a slight decrease was found in hypotonic medium. The decrease of K influx in the ion-replacement medium is due to a decrement of the ouabain-insensitive component. Potassium efflux was unchanged in hypotonic medium but was somewhat reduced in hypertonic medium. The marked effect of medium osmolarity of K fluxes suggests that these fluxes may be responsible for the volume regulatory K movements. The possible mechanism of changes of K flux under anisotonic media is also discussed.

  15. Ammonia inhibition on Arthrospira platensis in relation to the initial biomass density and pH.

    PubMed

    Markou, Giorgos; Vandamme, Dries; Muylaert, Koenraad

    2014-08-01

    In this study the combined effect of total ammoniacal nitrogen (TAN) concentration, initial biomass density and initial pH of the cultivation medium on growth of Arthrospira platensis was studied. The results indicate that TAN inhibition in relation to the initial biomass in unregulated pH cultures is neither a clearly biomass-independent nor biomass-dependent phenomenon. However, low biomass densities are more susceptible to ammonia inhibition than higher biomass densities. Higher biomass densities seems to mitigate ammonia inhibition through rapider assimilation of TAN. In all cases studied the growth rates were lower compared to the cultures with nitrate as nitrogen source. It was observed that at low TAN concentration, although no ammonia inhibition occured the growth rates were decreased due to nitrogen limitation. Low TAN concentration triggered the accumulation of carbohydrates affecting thus significantly the biomass composition. Ammonia losses from the cultivation system were also determined. Ammonia losses ranged between 17% and 80%. PMID:24926597

  16. Erythrocyte hemodynamics in stenotic microvessels: A numerical investigation

    NASA Astrophysics Data System (ADS)

    Wang, T.; Xing, Z. W.

    2013-10-01

    This paper presents a two-dimensional numerical investigation of deformation and motion of erythrocytes in stenotic microvessels using the immersed boundary-fictitious domain method. The erythrocytes were modeled as biconcave-shaped closed membranes filled with cytoplasm. We studied the biophysical characteristics of human erythrocytes traversing constricted microchannels with the narrowest cross-sectional diameter as small as 3 μm. The effects of essential parameters, namely, stenosis severity, shape of the erythrocytes, and erythrocyte membrane stiffness, were simulated and analyzed in this study. Moreover, simulations were performed to discuss conditions associated with the shape transitions of the cells along with the relative effects of radial position and initial orientation of erythrocytes, membrane stiffness, and plasma environments. The simulation results were compared with existing experiment findings whenever possible, and the physical insights obtained were discussed. The proposed model successfully simulated rheological behaviors of erythrocytes in microscale flow and thus is applicable to a large class of problems involving fluid flow with complex geometry and fluid-cell interactions. Our study would be helpful for further understanding of pathology of malaria and some other blood disorders.

  17. Erythrocyte hemodynamics in stenotic microvessels: A numerical investigation

    NASA Astrophysics Data System (ADS)

    Wang, Tong; Xing, Zhongwen

    2014-03-01

    This paper presents a two-dimensional numerical investigation of deformation and motion of erythrocytes in stenotic microvessels using the immersed boundary-fictitious domain method. The erythrocytes were modeled as biconcave-shaped closed membranes filled with cytoplasm. We studied the biophysical characteristics of human erythrocytes traversing constricted microchannels with the narrowest cross-sectional diameter as small as 3 μm. The effects of essential parameters, namely, stenosis severity, shape of the erythrocytes, and erythrocyte membrane stiffness, were simulated and analyzed in this study. Moreover, simulations were performed to discuss conditions associated with the shape transitions of the cells along with the relative effects of radial position and initial orientation of erythrocytes, membrane stiffness, and plasma environments. The simulation results were compared with existing experiment findings whenever possible, and the physical insights obtained were discussed. The proposed model successfully simulated rheological behaviors of erythrocytes in microscale flow and thus is applicable to a large class of problems involving fluid flow with complex geometry and fluid-cell interactions. Our study would be helpful for further understanding of pathology of malaria and some other blood disorders.

  18. RECONSTRUCTING THE INITIAL DENSITY FIELD OF THE LOCAL UNIVERSE: METHODS AND TESTS WITH MOCK CATALOGS

    SciTech Connect

    Wang Huiyuan; Mo, H. J.; Yang Xiaohu; Van den Bosch, Frank C.

    2013-07-20

    Our research objective in this paper is to reconstruct an initial linear density field, which follows the multivariate Gaussian distribution with variances given by the linear power spectrum of the current cold dark matter model and evolves through gravitational instabilities to the present-day density field in the local universe. For this purpose, we develop a Hamiltonian Markov Chain Monte Carlo method to obtain the linear density field from a posterior probability function that consists of two components: a prior of a Gaussian density field with a given linear spectrum and a likelihood term that is given by the current density field. The present-day density field can be reconstructed from galaxy groups using the method developed in Wang et al. Using a realistic mock Sloan Digital Sky Survey DR7, obtained by populating dark matter halos in the Millennium simulation (MS) with galaxies, we show that our method can effectively and accurately recover both the amplitudes and phases of the initial, linear density field. To examine the accuracy of our method, we use N-body simulations to evolve these reconstructed initial conditions to the present day. The resimulated density field thus obtained accurately matches the original density field of the MS in the density range 0.3{approx}<{rho}/ {rho}-bar {approx}<20 without any significant bias. In particular, the Fourier phases of the resimulated density fields are tightly correlated with those of the original simulation down to a scale corresponding to a wavenumber of {approx}1 h Mpc{sup -1}, much smaller than the translinear scale, which corresponds to a wavenumber of {approx}0.15 h Mpc{sup -1}.

  19. Physiological responses to acid stress by Saccharomyces cerevisiae when applying high initial cell density

    PubMed Central

    Guo, Zhong-peng; Olsson, Lisbeth

    2016-01-01

    High initial cell density is used to increase volumetric productivity and shorten production time in lignocellulosic hydrolysate fermentation. Comparison of physiological parameters in high initial cell density cultivation of Saccharomyces cerevisiae in the presence of acetic, formic, levulinic and cinnamic acids demonstrated general and acid-specific responses of cells. All the acids studied impaired growth and inhibited glycolytic flux, and caused oxidative stress and accumulation of trehalose. However, trehalose may play a role other than protecting yeast cells from acid-induced oxidative stress. Unlike the other acids, cinnamic acid did not cause depletion of cellular ATP, but abolished the growth of yeast on ethanol. Compared with low initial cell density, increasing initial cell density reduced the lag phase and improved the bioconversion yield of cinnamic acid during acid adaptation. In addition, yeast cells were able to grow at elevated concentrations of acid, probable due to the increase in phenotypic cell-to-cell heterogeneity in large inoculum size. Furthermore, the specific growth rate and the specific rates of glucose consumption and metabolite production were significantly lower than at low initial cell density, which was a result of the accumulation of a large fraction of cells that persisted in a viable but non-proliferating state. PMID:27620460

  20. Shock initiation experiments with ignition and growth modeling on low density HMX

    NASA Astrophysics Data System (ADS)

    Garcia, Frank; Vandersall, Kevin S.; Tarver, Craig M.

    2014-05-01

    Shock initiation experiments on low density (~1.2 and ~1.6 g/cm3) HMX were performed to obtain in-situ pressure gauge data, characterize the run-distance-to-detonation behavior, and provide a basis for Ignition and Growth reactive flow modeling. A 101 mm diameter gas gun was utilized to initiate the explosive charges with manganin piezoresistive pressure gauge packages placed between packed layers (~1.2 g/cm3) or sample disks pressed to low density (~1.6 g/cm3). The measured shock sensitivity of the ~1.2 g/cm3 HMX was similar to that previously measured by Sheffield et al. and the ~1.6 g/cm3 HMX was measured to be much less shock sensitive. Ignition and Growth model parameters were utilized that yielded good agreement with the experimental data at both initial densities.

  1. Shock Initiation Experiments with Ignition and Growth Modeling on Low Density Composition B

    NASA Astrophysics Data System (ADS)

    Vandersall, Kevin S.; Garcia, Frank; Tarver, Craig M.

    2015-06-01

    Shock initiation experiments on low density (~1.2 and ~1.5 g/cm3) Composition B were performed to obtain in-situ pressure gauge data, characterize the run-distance-to-detonation behavior, and provide a basis for Ignition and Growth reactive flow modeling. A 101 mm diameter gas gun was utilized to initiate the explosive charges with manganin piezoresistive pressure gauge packages placed between packed layers (~1.2 g/cm3) confined in Teflon rings or sample disks pressed to low density (~1.5 g/cm3) . The shock sensitivity was found to increase with decreasing density as expected. Ignition and Growth model parameters were derived that yielded reasonable agreement with the experimental data at both initial densities. The shock sensitivity at the tested densities will be compared to prior work published as near full density material. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work was funded in part by the Joint DoD-DOE Munitions Program.

  2. Low pressure shock initiation of porous HMX for two grain size distributions and two densities

    SciTech Connect

    Gustavsen, R.L.; Sheffield, S.A.; Alcon, R.R.

    1995-09-01

    Shock initiation measurements have been made on granular HMX (octotetramethylene tetranitrainine) for two particle size distributions and two densities. Samples were pressed to either 65% or 73% of crystal density from fine ({approx} 10 {mu}m grain size) and coarse (broad distribution of grain sizes peaking at {approx} 150 {mu}m) powders. Planar shocks of 0.2--1 GPa were generated by impacting gas gun driven projectiles on plastic targets containing the HMX. Wave profiles were measured at the input and output of the {approx} 3.9 mm thick HMX layer using electromagnetic particle velocity gauges. The initiation behavior for the two particle size distributions was very different. The coarse HMX began initiating at input pressures as low as 0.5 GPa. Transmitted wave profiles showed relatively slow reaction with most of the buildup occurring at the shock front. In contrast, the fine particle HMX did not begin to initiate at pressures below 0.9 GPa. When the fine powder did react, however, it did so much faster than the coarse HMX. These observations are consistent with commonly held ideas about bum rates being correlated to surface area, and initiation thresholds being correlated with the size and temperature of the hot spots created by shock passage. For each size, the higher density pressings were less sensitive than the lower density pressings.

  3. Correlations of neuronal and microvascular densities in murine cortex revealed by direct counting and colocalization of nuclei and vessels

    PubMed Central

    Tsai, Philbert S.; Kaufhold, John P.; Blinder, Pablo; Friedman, Beth; Drew, Patrick J.; Karten, Harvey J.; Lyden, Patrick D.; Kleinfeld, David

    2016-01-01

    It is well known that the density of neurons varies within the adult brain. In neocortex, this includes variations in neuronal density between different lamina as well as between different regions. Yet the concomitant variation of the microvessels is largely uncharted. Here we present automated histological, imaging, and analysis tools to simultaneously map the locations of all neuronal and non-neuronal nuclei and the centerlines and diameters of all blood vessels within thick slabs of neocortex from mice. Based on total inventory measurements of different cortical regions (~ 107 cells vectorized across brains), these methods revealed: (1) In three dimensions, the mean distance of the center of neuronal somata to the closest microvessel was 14 μm. (2) Volume samples within lamina of a given region show that the density of microvessels does not match the strong laminar variation in neuronal density. This holds for both agranular and granular cortex. (3) Volume samples in successive radii from the midline to the ventral-lateral edge, where each volume summed the number of cells and microvessels from the pia to the white matter, show a significant correlation between neuronal and microvessel densities. These data show that while neuronal and vascular densities do not track each other on the 100 μm scale of cortical lamina, they do track each other on the 1 – 10 mm scale of the cortical mantle. The absence of a disproportionate density of blood vessels in granular lamina is argued to be consistent with the initial locus of functional brain imaging signals. PMID:19923289

  4. LABORATORY CULTURE OF CHIRONOMUS TENTANS FOR USE IN TOXICITY TESTING: OPTIMUM INITIAL EGG STOCKING DENSITIES

    EPA Science Inventory

    This study was conducted to determine the effet of initial culture stocking density on: (1) post-hatch (larval) dry weight, body length and head-capsule width at 10 and 20 days; (2) time to emergence; (3) number and sex of emergent adults; (4) number of larvae and pupae at test t...

  5. Determination of an Initial Mesh Density for Finite Element Computations via Data Mining

    SciTech Connect

    Kanapady, R; Bathina, S K; Tamma, K K; Kamath, C; Kumar, V

    2001-07-23

    Numerical analysis software packages which employ a coarse first mesh or an inadequate initial mesh need to undergo a cumbersome and time consuming mesh refinement studies to obtain solutions with acceptable accuracy. Hence, it is critical for numerical methods such as finite element analysis to be able to determine a good initial mesh density for the subsequent finite element computations or as an input to a subsequent adaptive mesh generator. This paper explores the use of data mining techniques for obtaining an initial approximate finite element density that avoids significant trial and error to start finite element computations. As an illustration of proof of concept, a square plate which is simply supported at its edges and is subjected to a concentrated load is employed for the test case. Although simplistic, the present study provides insight into addressing the above considerations.

  6. Mechanics of smooth muscle in isolated single microvessels.

    PubMed

    Gore, R W; Davis, M J

    1984-01-01

    In vivo studies on frog mesenteric arterioles (4) indicate that segmental differences in the response of microvessels to physical and chemical stimuli can be explained simply in terms of the length-tension characteristics of vascular smooth muscle at different points along the vascular tree. Studies on single, isolated arterioles in vitro were initiated to examine more closely the validity of this explanation for regional response differences. This paper reports some of the results. First-, second-, and third-order arterioles (18-60 micron i.d.) were dissected from hamster cheek pouches. The vessels were cannulated with a modified Burg microperfusion system, and their mechanical properties studied using the methods described by Duling and Gore. Vessels were activated in four stages with K+ and norepinephrine. During activation, transmural pressures were adjusted to minimize vascular smooth-muscle shortening. Active pressure-diameter curves were recorded while adjusting transmural pressure through the range 5 to 400 cm H20 in 5-25 cm steps. Vessel dimensions were measured with a videomicrometer. Passive curves were obtained after equilibration overnight in Ca2+-free medium. The vessels were then fixed and prepared for histologic sectioning, and measurements of vessel-wall composition were made. The Laplace relationship was used to construct length-tension diagrams, and the histologic data were used to normalize the dimensional data to smooth-muscle lengths. Maximum active tension of second-order arterioles (1,170 dynes/cm) was two times previous values reported by Gore et al. This was due presumably to refinements in techniques and dissection procedures. Maximum active stress averaged 3.9 X 10(+6) dynes/cm2 for second-order arterioles. This number is identical to data obtained from hog carotid strips by Dillon et al.

  7. Breast Tenderness after Initiation of Conjugated Equine Estrogens and Mammographic Density Change

    PubMed Central

    Crandall, Carolyn J.; Aragaki, Aaron K.; Cauley, Jane A.; McTiernan, Anne; Manson, JoAnn E.; Anderson, Garnet L.; Wactawski-Wende, Jean; Chlebowski, Rowan T.

    2013-01-01

    Background We examined the association between new-onset breast tenderness and change in mammographic density after initiation of conjugated equine estrogens (CEE). Methods We analyzed baseline, year 1, and year 2 data from 695 participants of the Women's Health Initiative Estrogen + Progestin (daily CEE 0.625 mg + medroxyprogesterone acetate 2.5 mg [MPA] or placebo) and Estrogen-Alone (CEE 0.625 mg or placebo) trials who participated in the Mammogram Density Ancillary Study. Using multivariable repeated measures models, we analyzed the association between new-onset breast tenderness (i.e. absence of baseline tenderness and presence of tenderness at year 1 follow-up) and change from baseline in percent mammographic density. Results Active therapy increased the odds of new-onset breast tenderness (CEE + MPA vs. placebo risk ratio [RR] 3.01, 95% confidence interval [95% CI] 1.96-4.62; CEE vs. placebo RR 1.70, 95% CI 1.14-2.53). Among women assigned to CEE + MPA, mean increase in mammographic density was greater among participants reporting new-onset of breast tenderness than among participants without new-onset breast tenderness (11.3% vs. 3.9% at year 1, 9.4% vs. 3.2% at year 2, P < 0.001). Among women assigned to CEE alone, increase in mammographic density at year 1 follow-up was not significantly different in women with new-onset breast tenderness compared to women without new-onset breast tenderness (2.4% vs. 0.6% at year 1, 2.2% vs. 1.0% at year 2, P = 0.30). Conclusions The new-onset of breast tenderness after initiation of CEE + MPA, but not CEE alone, is associated with greater increases in mammographic density. PMID:21979747

  8. Specific binding of atrial natriuretic factor in brain microvessels

    SciTech Connect

    Chabrier, P.E.; Roubert, P.; Braquet, P.

    1987-04-01

    Cerebral capillaries constitute the blood-brain barrier. Studies of specific receptors (neurotransmitters or hormones) located on this structure can be performed by means of radioligand-binding techniques on isolated brain microvessels. The authors examined on pure bovine cerebral microvessel preparations the binding of atrial natriuretic factor (ANF), using /sup 125/I-labeled ANF. Saturation and competition experiments demonstrated the presence of a single class of ANF-binding sites with high affinity and with a binding capacity of 58 fmol/mg of protein. The binding of /sup 125/I-labeled ANF to brain microvessels is specific, reversible, and time dependent, as is shown by association-dissociation experiments. The demonstration of specific ANF-binding sites on brain microvessels supposes a physiological role of ANF on brain microvasculature. The coexistence of ANF and angiotensin II receptors on this cerebrovascular tissue suggests that the two circulating peptides may act as mutual antagonists in the regulation of brain microcirculation and/or blood-brain barrier function.

  9. Role of initial cell density of algal bioassay of toxic chemicals.

    PubMed

    Singh, Prashant Kumar; Shrivastava, Alok Kumar

    2016-07-01

    A variety of toxicants such as, metal ions, pesticides, dyes, etc. are continuously being introduced anthropogenically in the environment and adversely affect to the biotic component of the ecosystem. Therefore, the assessment of negative effects of these toxicants is required. However, toxicity assessment anticipated by chemical analysis are extremely poor, therefore the application of the living systems for the same is an excellent approach. Concentration of toxicant as well as cell density both influenced the result of the algal toxicity assay. Here, Scenedesmus sp, a very fast growing green microalgae was selected for study the effects of initial cell densities on the toxicity of Cu(II), Cd(II), Zn(II), paraquat and 2,4-D. Results demonstrated concentration dependent decrease in biomass and specific growth rate of Scenedesmus sp. on exposure of abovesaid toxicants. Paraquat and 2,4-D emerged as extremely toxic to the test alga which reflected from the lowest EC value and very steep decline in biomass was evident with increasing concentration of paraquat and 2,4-D in the medium. Result also demonstrated that initial cell density is a very important parameter than specific growth rate for algal bioassay of various toxicants. Present study clearly illustrated that the use of smaller cell density is always recommended for assaying toxicity of chemicals in algal assays. PMID:26593761

  10. A simple method to calculate first-passage time densities with arbitrary initial conditions

    NASA Astrophysics Data System (ADS)

    Nyberg, Markus; Ambjörnsson, Tobias; Lizana, Ludvig

    2016-06-01

    Numerous applications all the way from biology and physics to economics depend on the density of first crossings over a boundary. Motivated by the lack of general purpose analytical tools for computing first-passage time densities (FPTDs) for complex problems, we propose a new simple method based on the independent interval approximation (IIA). We generalise previous formulations of the IIA to include arbitrary initial conditions as well as to deal with discrete time and non-smooth continuous time processes. We derive a closed form expression for the FPTD in z and Laplace-transform space to a boundary in one dimension. Two classes of problems are analysed in detail: discrete time symmetric random walks (Markovian) and continuous time Gaussian stationary processes (Markovian and non-Markovian). Our results are in good agreement with Langevin dynamics simulations.

  11. Study of the stability of Z-pinch implosions with different initial density profiles

    SciTech Connect

    Rousskikh, A. G.; Zhigalin, A. S.; Labetskaya, N. A.; Chaikovsky, S. A.; Yushkov, G. Yu.; Oreshkin, V. I.; Batrakov, A. V.; Baksht, R. B.

    2014-05-15

    Stability of metal-puff Z pinches was studied experimentally. Experiments were carried out on a facility producing a load current up to 450 kA with a rise time of 450 ns. In a metal-puff Z pinch, the plasma shell is produced due to evaporation of the electrode material during the operation of a vacuum arc. In the experiment to be reported, a single-shell and a shell-on-jet pinch load with magnesium electrodes were used. Two-dimensional, 3 ns gated, visible-light images were taken at different times during the implosion. When the shell was formed from a collimated plasma flow with small radial divergence, Rayleigh–Taylor (RT) instability typical of gas-puff implosions was recorded. The RT instability was completely suppressed in a mode where the initial density distribution of the shell approached a tailored density profile [A. L. Velikovich et al., Phys. Rev. Lett. 77, 853 (1996)].

  12. Reduction of damage initiation density in fused silica optics via UV laser conditioning

    DOEpatents

    Peterson, John E.; Maricle, Stephen M.; Brusasco, Raymond M.; Penetrante, Bernardino M.

    2004-03-16

    The present invention provides a method for reducing the density of sites on the surface of fused silica optics that are prone to the initiation of laser-induced damage, resulting in optics which have far fewer catastrophic defects and are better capable of resisting optical deterioration upon exposure for a long period of time to a high-power laser beam having a wavelength of about 360 nm or less. The initiation of laser-induced damage is reduced by conditioning the optic at low fluences below levels that normally lead to catastrophic growth of damage. When the optic is then irradiated at its high fluence design limit, the concentration of catastrophic damage sites that form on the surface of the optic is greatly reduced.

  13. Current initiation in low-density foam z-pinch plasmas

    SciTech Connect

    Derzon, M.; Nash, T.; Allshouse, G.

    1996-07-01

    Low density agar and aerogel foams were tested as z-pinch loads on the SATURN accelerator. In these first experiments, we studied the initial plasma conditions by measuring the visible emission at early times with a framing camera and 1-D imaging. At later time, near the stagnation when the plasma is hotter, x-ray imaging and spectral diagnostics were used to characterize the plasma. Filamentation and arcing at the current contacts was observed. None of the implosions were uniform along the z-axis. The prime causes of these problems are believed to be the electrode contacts and the current return configuration and these are solvable. Periodic phenomena consistent with the formation of instabilities were observed on one shot, not on others, implying that there may be a way of controlling instabilities in the pinch. Many of the issues involving current initiation may be solvable. Solutions are discussed.

  14. Cystathionine γ-lyase is expressed in human atherosclerotic plaque microvessels and is involved in micro-angiogenesis

    PubMed Central

    van den Born, J. C.; Mencke, R.; Conroy, S.; Zeebregts, C. J.; van Goor, H.; Hillebrands, J. L.

    2016-01-01

    Atherosclerotic plaques are classically divided into stable and vulnerable plaques. Vulnerable plaques are prone to rupture with a risk for infarction. High intraplaque microvessel density predisposes to plaque vulnerability. Hydrogen sulfide (H2S) is a proangiogenic gasotransmitter which is endogenously produced by cystathionine γ-lyase (CSE), and is believed to have vasculoprotective effects. However, due to its proangiogenic effects, H2S may result in pathological angiogenesis in atherosclerotic plaques, thereby increasing plaque vulnerability. The aim of this study was to determine CSE expression pattern in atherosclerotic plaques, and investigate whether CSE is involved in micro-angiogenesis in vitro. Endarterectomy plaques were studied for CSE expression, and the role of CSE in micro-angiogenesis was studied in vitro. CSE is expressed in plaques with similar levels in both stable and vulnerable plaques. CSE co-localized with von Willebrand Factor-positive microvessel endothelial cells and alpha-smooth-muscle actin-positive SMCs. In vitro, inhibition of CSE in HMEC-1 reduced tube formation, cell viability/proliferation, and migration which was restored after culture in the presence of H2S donor GYY4137. CSE is expressed in intraplaque microvessels, and H2S is a stimulator of micro-angiogenesis in vitro. Due to this pro-angiogenic effect, high levels of CSE in atherosclerotic plaques may be a potential risk for plaque vulnerability. PMID:27708362

  15. Electron density profiles obtained from CHAMP GPS radio occultation measurements: Initial results from GFZ

    NASA Astrophysics Data System (ADS)

    Arras, Christina; Schmidt, Torsten; Lee, Woo-Kyoung; Wickert, Jens; Heise, Stefan; Beyerle, Georg; Rothacher, Markus; Jakowski, Norbert

    GPS radio occultation signals received by Low Earth Orbit satellites provide global information about vertical distribution of lower atmospheric parameters (e.g., temperature and water vapour) and electron density in the ionosphere. Since its launch in July 2000 the German geoscience satellite CHAMP has collected about 400,000 occultation measurements. These data form a first and unique long-term dataset of ionospheric profiles, but also of other geophysical variables as temperature, pressure and water vapour in the lower atmosphere. We present initial results of the ionospheric occultation data analyses at GFZ. Vertical electron density profiles from CHAMP are derived using a recently developed software package. To obtain electron densities from calibrated TEC (Total Electron Content) data the so-called onion peeling method is used. The application of this technique allows for the derivation of the electron density profile iteratively starting from the top altitude. The derived profiles are compared with corresponding data processed by UCAR (University Corporation of Atmospheric Research) and DLR Neustrelitz, but also with independent PLP (Planar Langmuir Probe) measurements from CHAMP. These investigations are complemented by case studies comparing the profiles with ground based ionosonde measurements. The high vertical resolution of the derived ionospheric profiles reveals thin vertical ionospheric structures such as sporadic E layers. We investigate the occurrence distribution of these layers in more detail. Sporadic E appears predominantly during summer in the lower ionosphere and has a considerable effect on the propagation of the GPS radio occultation signals. This feature is used to derive information on the altitude and on the intensity of these irregularities.

  16. Regional Heterogeneity of Cerebral Microvessels and Brain Susceptibility to Oxidative Stress

    PubMed Central

    Austin, Susan A.; Santhanam, Anantha Vijay R.; d’Uscio, Livius V.; Katusic, Zvonimir S.

    2015-01-01

    The hippocampus is one of the earliest and most affected regions in Alzheimer’s disease (AD), followed by the cortex while the cerebellum is largely spared. Importantly, endothelial dysfunction is a common feature of cerebral blood vessels in AD. In this study, we sought to determine if regional heterogeneity of cerebral microvessels might help explain the susceptibility of the hippocampus and cortex as compared to the cerebellum. We isolated microvessels from wild type mice from the cerebellum, cortex, and hippocampus to characterize their vascular phenotype. Superoxide anion was significantly higher in microvessels isolated from the cortex and hippocampus as compared to the cerebellum. Importantly, protein levels of NADPH oxidase (NOX)-2 and NOX-4 were significantly higher in the cortical and hippocampal microvessels as compared to microvessels from the cerebellum. In addition, expression of manganese superoxide dismutase protein was significantly lower in microvessels from the cortex and hippocampus as compared to cerebellum while other antioxidant enzymes were unchanged. There was no difference in eNOS protein expression between the microvessels of the three brain regions; however, bioavailability of tetrahydrobiopterin (BH4), an essential cofactor for eNOS activity, was significantly reduced in microvessels from the hippocampus and cortex as compared to the cerebellum. Higher levels of superoxide and reduced tetrahydrobiopterin bioavailability may help explain the vulnerability of the hippocampus and cortical microvessels to oxidative stress and development of endothelial dysfunction. PMID:26629821

  17. Shock initiation studies of low density HMX using electromagnetic particle velocity and PVDF stress gauges

    SciTech Connect

    Sheffield, S.A.; Gustavsen, R.L.; Alcon, R.R.; Graham, R.A.; Anderson, M.U.

    1993-09-01

    Magnetic particle velocity and PVDF stress rate gauges have been used to measure the shock response of low density octotetramethylene tetranitramine (HMX) (1.24 &/cm{sup 3}). In experiments done at LANL, magnetic particle velocity gauges were located on both sides of the explosive. In nearly identical experiments done at SNL, PVDF stress rate gauges were located at the same positions so both particle velocity and stress histories were obtained for a particular experimental condition. Unreacted Hugoniot data were obtained and an EOS was developed by combining methods used by Hayes, Sheffield and Mitchell (for describing the Hugoniot of HNS at various densities) with Hermann`s P-{alpha} model. Using this technique, it is only necessary to know some thermodynamic constants or the Hugoniot of the initially solid material and the porous material sound speed to obtain accurate unreacted Hugoniots for the porous explosive. Loading and reaction paths were established in the stress-particle velocity plane for some experimental conditions. This information was used to determine a global reaction rate of {approx} 0.13 {mu}s{sup {minus}1} for porous HMX shocked to 0.8 GPa. At low input stresses the transmitted wave profiles had long rise times (up to 1 {mu}s) due to the compaction processes.

  18. Evidence for top-heavy stellar initial mass functions with increasing density and decreasing metallicity

    NASA Astrophysics Data System (ADS)

    Marks, Michael; Kroupa, Pavel; Dabringhausen, Jörg; Pawlowski, Marcel S.

    2012-05-01

    Residual-gas expulsion after cluster formation has recently been shown to leave an imprint in the low-mass present-day stellar mass function (PDMF) which allowed the estimation of birth conditions of some Galactic globular clusters (GCs) such as mass, radius and star formation efficiency. We show that in order to explain their characteristics (masses, radii, metallicity and PDMF) their stellar initial mass function (IMF) must have been top heavy. It is found that the IMF is required to become more top heavy the lower the cluster metallicity and the larger the pre-GC cloud-core density are. The deduced trends are in qualitative agreement with theoretical expectation. The results are consistent with estimates of the shape of the high-mass end of the IMF in the Arches cluster, Westerlund 1, R136 and NGC 3603, as well as with the IMF independently constrained for ultra-compact dwarf galaxies (UCDs). The latter suggests that GCs and UCDs might have formed along the same channel or that UCDs formed via mergers of GCs. A Fundamental Plane is found which describes the variation of the IMF with density and metallicity of the pre-GC cloud cores. The implications for the evolution of galaxies and chemical enrichment over cosmological times are expected to be major.

  19. The Role of Surface Receptor Density in Surface-Initiated Polymerizations for Cancer Cell Isolation.

    PubMed

    Lilly, Jacob L; Berron, Brad J

    2016-06-01

    Fluid biopsies potentially offer a minimally invasive alternative to traditional tissue biopsies for the continual monitoring of metastatic cancer. Current established technologies for isolating circulating tumor cells (CTCs) suffer from poor purity and yield and require fixatives that preclude the collection of viable cells for longitudinal analyses of biological function. Antigen specific lysis (ASL) is a rapid, high-purity method of cell isolation based on targeted protective coatings on antigen-presenting cells and lysis depletion of unprotected antigen-negative cells. In ASL, photoinitiators are specifically labeled on cell surfaces that enable subsequent surface-initiated polymerization. Critically, the significant determinants of process yield have yet to be investigated for this emerging technology. In this work, we show that the labeling density of photoinitiators is strongly correlated with the yield of intact cells during ASL by flow cytometry analysis. Results suggest ASL is capable of delivering ∼25% of targeted cells after isolation using traditional antibody labeling approaches. Monomer formulations of two molecular weights of PEG-diacrylate (Mn ∼ 575 and 3500) are examined. The gelation response during ASL polymerization is also investigated via protein microarray analogues on planar glass. Finally, a density threshold of photoinitiator labeling required for protection during lysis is determined for both monomer formulations. These results indicate ASL is a promising technology for high yield CTC isolation for rare-cell function assays and fluid biopsies. PMID:27206735

  20. Self-similar space-time evolution of an initial density discontinuity

    SciTech Connect

    Rekaa, V. L.; Pécseli, H. L.; Trulsen, J. K.

    2013-07-15

    The space-time evolution of an initial step-like plasma density variation is studied. We give particular attention to formulate the problem in a way that opens for the possibility of realizing the conditions experimentally. After a short transient time interval of the order of the electron plasma period, the solution is self-similar as illustrated by a video where the space-time evolution is reduced to be a function of the ratio x/t. Solutions of this form are usually found for problems without characteristic length and time scales, in our case the quasi-neutral limit. By introducing ion collisions with neutrals into the numerical analysis, we introduce a length scale, the collisional mean free path. We study the breakdown of the self-similarity of the solution as the mean free path is made shorter than the system length. Analytical results are presented for charge exchange collisions, demonstrating a short time collisionless evolution with an ensuing long time diffusive relaxation of the initial perturbation. For large times, we find a diffusion equation as the limiting analytical form for a charge-exchange collisional plasma, with a diffusion coefficient defined as the square of the ion sound speed divided by the (constant) ion collision frequency. The ion-neutral collision frequency acts as a parameter that allows a collisionless result to be obtained in one limit, while the solution of a diffusion equation is recovered in the opposite limit of large collision frequencies.

  1. Density Functional Theory Study on OH-Initiated Atmospheric Oxidation of m-Xylene

    SciTech Connect

    Fan, Jiwen; Zhang, Renyi

    2008-05-08

    The OH-initiated oxidation reactions of m-xylene are investigated using density functional theory. The structures, energetics, and relative stability of the OH-m-xylene reaction intermediate radicals have been determined, and their activation barriers have been analyzed to assess the energetically favorable pathways to propagate the oxidation. OH addition occurs preferentially at the two ortho positions with the branching ratios of 0.97, 0.02, and 0.01 for ortho, meta, and ipso additions, respectively. The results reveal that the OH-m-xylene-O2 peroxy radicals preferentially cyclize to form bicyclic radicals under atmospheric conditions rather than reacting with NO to lead to ozone formation, and the decomposition to O2 and the hydroxyl m-xylene adduct is competitive with the cyclization process. The bicyclic radicals of m-xylene formed from the major OH-addition pathways (i.e., ortho positions) are more probable to form bicyclic peroxy radicals by reacting with O2. This study provides thermochemical and kinetic data of the OH-initiated reactions of m-xylene for assessment of the role of aromatic hydrocarbons in photochemical production of ozone, toxic products, and secondary organic aerosols.

  2. Flow-driven assembly of VWF fibres and webs in in vitro microvessels

    PubMed Central

    Zheng, Ying; Chen, Junmei; López, José A.

    2015-01-01

    Several systemic diseases, including thrombotic thrombocytopenic purpura, manifest much of their pathology through activation of endothelium and thrombotic occlusion of small blood vessels, often leading to multi-organ failure and death. Modelling these diseases is hampered by the complex three-dimensional architecture and flow patterns of the microvasculature. Here, we employ engineered microvessels of complex geometry to examine the pathological responses to endothelial activation. Our most striking finding is the capacity of endothelial-secreted von Willebrand factor (VWF) to assemble into thick bundles or complex meshes, depending on the vessel geometry and flow characteristics. Assembly is greatest in vessels of diameter ≤300 μm, with high shear stress or strong flow acceleration, and with sharp turns. VWF bundles and webs bind platelets, leukocytes and erythrocytes, obstructing blood flow and sometimes shearing passing erythrocytes. Our findings uncover the biophysical requirements for initiating microvascular thrombosis and suggest mechanisms for the onset and progression of microvascular diseases. PMID:26223854

  3. Adhesion of malignant mammary tumor cells MDA-MB-231 to microvessel wall increases microvascular permeability via degradation of endothelial surface glycocalyx

    PubMed Central

    Cai, Bin; Fan, Jie; Zeng, Min; Zhang, Lin

    2012-01-01

    To investigate the effect of tumor cell adhesion on microvascular permeability (P) in intact microvessels, we measured the adhesion rate of human mammary carcinoma MDA-MB-231, the hydraulic conductivity (Lp), the P, and reflection coefficient (σ) to albumin of the microvessels at the initial tumor cell adhesion and after ∼45 min cell perfusion in the postcapillary venules of rat mesentery in vivo. Rats (Sprague-Dawley, 250–300 g) were anesthetized with pentobarbital sodium given subcutaneously. A midline incision was made in the abdominal wall, and the mesentery was gently taken out and arranged on the surface of a glass coverslip for the measurement. An individual postcapillary venule was perfused with cells at a rate of ∼1 mm/s, which is the mean blood flow velocity in this type of microvessels. At the initial tumor cell adhesion, which was defined as one adherent cell in ∼100- to 145-μm vessel segment, Lp was 1.5-fold and P was 2.3-fold of their controls, and σ decreased from 0.92 to 0.64; after ∼45-min perfusion, the adhesion increased to ∼5 adherent cells in ∼100- to 145-μm vessel segment, while Lp increased to 2.8-fold, P to 5.7-fold of their controls, and σ decreased from 0.92 to 0.42. Combining these measured data with the predictions from a mathematical model for the interendothelial transport suggests that tumor cell adhesion to the microvessel wall degrades the endothelial surface glycocalyx (ESG) layer. This suggestion was confirmed by immunostaining of heparan sulfate of the ESG on the microvessel wall. Preserving of the ESG by a plasma glycoprotein orosomucoid decreased the P to albumin and reduced the tumor cell adhesion. PMID:22858626

  4. Perfusion Imaging of Focal Cortical Dysplasia Using Arterial Spin Labeling: Correlation With Histopathological Vascular Density

    PubMed Central

    Wintermark, Pia; Lechpammer, Mirna; Warfield, Simon K.; Kosaras, Bela; Takeoka, Masanori; Poduri, Annapurna; Madsen, Joseph R.; Bergin, Ann M.; Whalen, Stephen; Jensen, Frances E.

    2016-01-01

    Focal cortical dysplasia is the most common malformation of cortical development, causing intractable epilepsy. This study investigated the relationship between brain perfusion and microvessel density in 7 children with focal cortical dysplasia. The authors analyzed brain perfusion measurements obtained by magnetic resonance imaging of 2 of the children and the microvessel density of brain tissue specimens obtained by epilepsy surgery on all of the children. Brain perfusion was approximately 2 times higher in the area of focal cortical dysplasia compared to the contralateral side. The microvessel density was nearly double in the area of focal cortical dysplasia compared to the surrounding cortex that did not have morphological abnormalities. These findings suggest that hyperperfusion can be related to increased microvessel density in focal cortical dysplasia rather than only to seizures. Further investigations are needed to determine the relationship between brain perfusion, microvessel density, and seizure activity. PMID:23696629

  5. Magnetic resonance imaging of microvessels using iron-oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Olamaei, N.; Cheriet, F.; Martel, S.

    2013-03-01

    The visualization of microstructures including blood vessels with an inner overall cross-sectional area below approximately 200 μm remains beyond the capabilities of current clinical imaging modalities. But with magnetic resonance (MR) imaging, magnetic entities cause susceptibility artifacts in the images by disrupting the homogeneous magnetic field in a much larger scale than their actual size. As validated in this paper through simulation and in-vitro experiments, these artifacts can serve as a source of contrast, enabling microvessels with an inner diameter below the spatial resolution of any medical imaging modalities to be visualized using a clinical MR scanner. For such experiments, micron-sized agglomerations of iron-oxide (Fe3O4) nanoparticles were injected in microchannels with internal diameters of 200 and 50 μm equivalent to a narrower artery or a larger arteriole, and down to a smaller arteriole, respectively. The results show the feasibility of the proposed method for micro-particle detection and the visualization of microvessels using a 1.5 T clinical MR scanner. It was confirmed that the method is reproducible and accurate at the sub-pixel level.

  6. Quantitative study on appearance of microvessels in spectral endoscopic imaging

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hiroshi; Saito, Takaaki; Shiraishi, Yasushi; Arai, Fumihito; Morimoto, Yoshinori; Yuasa, Atsuko

    2015-03-01

    Increase in abnormal microvessels in the superficial mucosa is often relevant to diagnostic findings of neoplasia in digestive endoscopy; hence, observation of superficial vasculature is crucial for cancer diagnosis. To enhance the appearance of such vessels, several spectral endoscopic imaging techniques have been developed, such as narrow-band imaging and blue laser imaging. Both techniques exploit narrow-band blue light for the enhancement. The emergence of such spectral imaging techniques has increased the importance of understanding the relation of the light wavelength to the appearance of superficial vasculature, and thus a new method is desired for quantitative analysis of vessel visibility in relation to the actual structure in the tissue. Here, we developed microvessel-simulating phantoms that allowed quantitative evaluation of the appearance of 15-μm-thick vessels. We investigated the relation between the vascular contrast and light wavelength by the phantom measurements and also verified it in experiments with swine, where the endoscopically observed vascular contrast was investigated together with its real vascular depth and diameter obtained by microscopic observation of fluorescence-labeled vessels. Our study indicates that changing the spectral property even in the wavelength range of blue light may allow selective enhancement of the vascular depth for clinical use.

  7. High-latitude proton precipitation and light ion density profiles during the magnetic storm initial phase.

    NASA Technical Reports Server (NTRS)

    Burch, J. L.

    1973-01-01

    Measurements of precipitating protons and light ion densities by experiments on Ogo 4 indicate that widespread proton precipitation occurs in predawn hours during the magnetic storm initial phase from the latitude of the high-latitude ion trough, or plasmapause, up to latitudes greater than 75 deg. A softening of the proton spectrum is apparent as the plasmapause is approached. The separation of the low-latitude precipitation boundaries for 7.3-keV and 23.8-keV protons is less than about 1 deg, compared with a 3.6-deg separation that has been computed by using the formulas of Gendrin and Eather and Carovillano. Consideration of probable proton drift morphology leads to the conclusion that protons are injected in predawn hours, widespread precipitation occurring in the region outside the plasmapause. Protons less energetic than 7 keV drift eastward, whereas the more energetic protons drift westward, producing the observed dawn-dusk asymmetry for the lower-energy protons.

  8. Postsynaptic density-93 clusters Kv1 channels at axon initial segments independently of Caspr2.

    PubMed

    Ogawa, Yasuhiro; Horresh, Ido; Trimmer, James S; Bredt, David S; Peles, Elior; Rasband, Matthew N

    2008-05-28

    Postsynaptic density-93 (PSD-93)/Chapsyn-110 is a PDZ (PSD-95/Discs large/zona occludens-1) domain-containing membrane-associated guanylate kinase (MAGUK) that functions as a scaffold to assemble channels, receptors, and other signaling proteins at cell membranes. PSD-93 is highly enriched at synapses, but mice lacking this protein have no synaptic structural abnormalities, probably because of overlapping expression and redundancy with other MAGUKs. Consequently, the function of PSD-93 is not well understood. Here, we show that PSD-93, but not other MAGUKs, is enriched at the axon initial segment (AIS), where it colocalizes with Kv1.1, Kv1.2, Kv1.4, and Kvbeta2 subunit-containing K(+) channels, Caspr2, and TAG-1 (transient axonal glycoprotein-1). When coexpressed with Kv1 channels in heterologous cells, PSD-93 induces formation of large cell-surface clusters. Knockdown of PSD-93 in cultured hippocampal neurons by RNA interference disrupted Kv1 channel localization at the AIS. Similarly, PSD-93-/- mice failed to cluster Kv1 channels at the AIS of cortical and hippocampal neurons. In contrast, Caspr2, which mediates Kv1 channel clustering at the juxtaparanode, is not required for localization of Kv1 channels at the AIS. These results show PSD-93 mediates AIS accumulation of Kv1 channels independently of Caspr2. PMID:18509034

  9. THE INITIAL MASS FUNCTION AND THE SURFACE DENSITY PROFILE OF NGC 6231

    SciTech Connect

    Sung, Hwankyung; Sana, Hugues; Bessell, Michael S. E-mail: H.Sana@uva.nl

    2013-02-01

    We have performed new wide-field photometry of the young open cluster NGC 6231 to study the shape of the initial mass function (IMF) and mass segregation. We also investigated the reddening law toward NGC 6231 from optical to mid-infrared color excess ratios, and found that the total-to-selective extinction ratio is R{sub V} = 3.2, which is very close to the normal value. But many early-type stars in the cluster center show large color excess ratios. We derived the surface density profiles of four member groups, and found that they reach the surface density of field stars at about 10', regardless of stellar mass. The IMF of NGC 6231 is derived for the mass range 0.8-45 M{sub Sun }. The slope of the IMF of NGC 6231 ({Gamma} = -1.1 {+-} 0.1) is slightly shallower than the canonical value, but the difference is marginal. In addition, the mass function varies systematically, and is a strong function of radius-it is very shallow at the center, and very steep at the outer ring suggesting the cluster is mass segregated. We confirm the mass segregation for the massive stars (m {approx}> 8 M{sub Sun }) by a minimum spanning tree analysis. Using a Monte Carlo method, we estimate the total mass of NGC 6231 to be about 2.6 ({+-} 0.6) Multiplication-Sign 10{sup 3} M{sub Sun }. We constrain the age of NGC 6231 by comparison with evolutionary isochrones. The age of the low-mass stars ranges from 1 to 7 Myr with a slight peak at 3 Myr. However, the age of the high-mass stars depends on the adopted models and is 3.5 {+-} 0.5 Myr from the non-rotating or moderately rotating models of Brott et al. as well as the non-rotating models of Ekstroem et al. But the age is 4.0-7.0 Myr if the rotating models of Ekstroem et al. are adopted. This latter age is in excellent agreement with the timescale of ejection of the high-mass runaway star HD 153919 from NGC 6231, albeit the younger age cannot be entirely excluded.

  10. Beetle and plant density as cues initiating dispersal in two species of adult predaceous diving beetles.

    PubMed

    Yee, Donald A; Taylor, Stacy; Vamosi, Steven M

    2009-05-01

    Dispersal can influence population dynamics, species distributions, and community assembly, but few studies have attempted to determine the factors that affect dispersal of insects in natural populations. Consequently, little is known about how proximate factors affect the dispersal behavior of individuals or populations, or how an organism's behavior may change in light of such factors. Adult predaceous diving beetles are active dispersers and are important predators in isolated aquatic habitats. We conducted interrelated studies to determine how several factors affected dispersal in two common pond-inhabiting species in southern Alberta, Canada: Graphoderus occidentalis and Rhantus sericans. Specifically, we (1) experimentally tested the effect of plant and beetle densities on dispersal probabilities in ponds; (2) surveyed ponds and determined the relationships among beetle densities and plant densities and water depth; and (3) conducted laboratory trials to determine how beetle behavior changed in response to variation in plant densities, conspecific densities, food, and water depth. Our field experiment determined that both species exhibited density dependence, with higher beetle densities leading to higher dispersal probabilities. Low plant density also appeared to increase beetle dispersal. Consistent with our experimental results, densities of R. sericans in ponds were significantly related to plant density and varied also with water depth; G. occidentalis densities did not vary with either factor. In the laboratory, behavior varied with plant density only for R. sericans, which swam at low density but were sedentary at high density. Both species responded to depth, with high beetle densities eliciting beetles to spend more time in deeper water. The presence of food caused opposite responses for G. occidentalis between experiments. Behavioral changes in response to patch-level heterogeneity likely influence dispersal in natural populations and are expected

  11. Beetle and plant density as cues initiating dispersal in two species of adult predaceous diving beetles.

    PubMed

    Yee, Donald A; Taylor, Stacy; Vamosi, Steven M

    2009-05-01

    Dispersal can influence population dynamics, species distributions, and community assembly, but few studies have attempted to determine the factors that affect dispersal of insects in natural populations. Consequently, little is known about how proximate factors affect the dispersal behavior of individuals or populations, or how an organism's behavior may change in light of such factors. Adult predaceous diving beetles are active dispersers and are important predators in isolated aquatic habitats. We conducted interrelated studies to determine how several factors affected dispersal in two common pond-inhabiting species in southern Alberta, Canada: Graphoderus occidentalis and Rhantus sericans. Specifically, we (1) experimentally tested the effect of plant and beetle densities on dispersal probabilities in ponds; (2) surveyed ponds and determined the relationships among beetle densities and plant densities and water depth; and (3) conducted laboratory trials to determine how beetle behavior changed in response to variation in plant densities, conspecific densities, food, and water depth. Our field experiment determined that both species exhibited density dependence, with higher beetle densities leading to higher dispersal probabilities. Low plant density also appeared to increase beetle dispersal. Consistent with our experimental results, densities of R. sericans in ponds were significantly related to plant density and varied also with water depth; G. occidentalis densities did not vary with either factor. In the laboratory, behavior varied with plant density only for R. sericans, which swam at low density but were sedentary at high density. Both species responded to depth, with high beetle densities eliciting beetles to spend more time in deeper water. The presence of food caused opposite responses for G. occidentalis between experiments. Behavioral changes in response to patch-level heterogeneity likely influence dispersal in natural populations and are expected

  12. Bone Mineral Density Changes Among Women Initiating Blood Pressure Lowering Drugs: A SWAN Cohort Study

    PubMed Central

    Solomon, Daniel H.; Ruppert, Kristine; Zhao, Zhenping; Lian, YinJuan; Kuo, I-Hsin; Greendale, Gail A.; Finkelstein, Joel S.

    2016-01-01

    Purpose Several blood pressure lowering drugs may affect bone mineral density (BMD), leading to altered fracture risk. We examined the effect of blood pressure lowering drugs on BMD using data from the Study of Women’s Health Across the Nation. Methods We conducted a propensity score matched cohort study. Women were initiators of ACE inhibitors (ACEi), beta-blockers (BB), or thiazide diuretics (THZD). Their annualized BMD changes during the 14-years of observation were compared with non-users. Results Among the 2312 eligible women, we found 69 ACEi, 71 BB, and 74 THZD users who were matched by a propensity score with the same number of non-users. THZD users had a slower annual percent decline in BMD compared to nonusers at the femoral neck (FN) (−0.28% vs −0.88%; p = 0.008) and the spine (−0.74% vs −1.0%; p = 0.34), albeit not statistically significant. Annual percent changes in BMD among ACEi and BB users were similar to rates in non-users. In comparison with BB, THZD use was associated with a trend toward less annualized BMD loss at the spine (−0.35% vs −0.60%; p = 0.08) and a similar trend at the FN (−0.39% vs −0.64%; p = 0.08); in comparisons with ACEi, THZD was also associated with less loss at the FN (−0.48% vs −0.82%; p = 0.02), but not at the spine (−0.40% vs −0.56%; p = 0.23). Conclusions Neither ACEi nor BB were associated with improvements in BMD. THZD use was associated with less annualized loss of BMD compared with non-users, as well as compared with ACEi and BB. PMID:26449354

  13. Interaction of Angiogenic Microvessels with the Extracellular Matrix

    PubMed Central

    Krishnan, Laxminarayanan; Hoying, James B.; Nguyen, Hoa; Song, Helen; Weiss, Jeffrey A.

    2010-01-01

    The extracellular matrix (ECM) plays a critical role in angiogenesis by providing biochemical and positional cues as well as by mechanically influencing microvessel cell behavior. Considerable information is known concerning the biochemical cues relevant to angiogenesis, but less is known about the mechanical dynamics during active angiogenesis. The objective of this study was to characterize changes in the material properties of a simple angiogenic tissue before and during angiogenesis. During sprouting, there was an overall decrease in tissue stiffness followed by an increase during neovessel elongation. The fall in matrix stiffness coincided with peak MMP mRNA expression and elevated proteolytic activity. An elevated expression of genes for ECM componenets and cell-ECM interaction molecules and a subsequent drop in proteolytic activity (although enzyme levels remained elevated) coincided with the subsequent stiffening.. The results of this study show that the mechanical properties of a scaffold tissue may be actively modified during angiogenesis by the growing microvasculature. PMID:17933969

  14. Characterization of nerve and microvessel damage and recovery in type 1 diabetic mice after permanent femoral artery ligation.

    PubMed

    Lozeron, Pierre; Mantsounga, Chris S; Broqueres-You, Dong; Dohan, Anthony; Polivka, Marc; Deroide, Nicolas; Silvestre, Jean-Sébastien; Kubis, Nathalie; Lévy, Bernard I

    2015-09-01

    Neuropathy is the most common complication of the peripheral nervous system during the progression of diabetes. The pathophysiology is unclear but may involve microangiopathy, reduced endoneurial blood flow, and tissue ischemia. We used a mouse model of type 1 diabetes to study parallel alterations of nerves and microvessels following tissue ischemia. We designed an easily reproducible model of ischemic neuropathy induced by irreversible ligation of the femoral artery. We studied the evolution of behavioral function, epineurial and endoneurial vessel impairment, and large nerve myelinated fiber as well as small cutaneous unmyelinated fiber impairment for 1 month following the onset of ischemia. We observed a more severe hindlimb dysfunction and delayed recovery in diabetic animals. This was associated with reduced density of large arteries in the hindlimb and reduced sciatic nerve epineurial blood flow. A reduction in sciatic nerve endoneurial capillary density was also observed, associated with a reduction in small unmyelinated epidermal fiber number and large myelinated sciatic nerve fiber dysfunction. Moreover, vascular recovery was delayed, and nerve dysfunction was still present in diabetic animals at day 28. This easily reproducible model provides clear insight into the evolution over time of the impact of ischemia on nerve and microvessel homeostasis in the setting of diabetes. © 2015 Wiley Periodicals, Inc. PMID:25944265

  15. The dynamics of superclusters - Initial determination of the mass density of the universe at large scales

    NASA Technical Reports Server (NTRS)

    Ford, H. C.; Ciardullo, R.; Harms, R. J.; Bartko, F.

    1981-01-01

    The radial velocities of cluster members of two rich, large superclusters have been measured in order to probe the supercluster mass densities, and simple evolutionary models have been computed to place limits upon the mass density within each supercluster. These superclusters represent true physical associations of size of about 100 Mpc seen presently at an early stage of evolution. One supercluster is weakly bound, the other probably barely bound, but possibly marginally unbound. Gravity has noticeably slowed the Hubble expansion of both superclusters. Galaxy surface-density counts and the density enhancement of Abell clusters within each supercluster were used to derive the ratio of mass densities of the superclusters to the mean field mass density. The results strongly exclude a closed universe.

  16. Widefield in vivo spectral and fluorescence imaging microscopy of microvessel blood supply and oxygenation

    NASA Astrophysics Data System (ADS)

    Lee, Jennifer; Kozikowski, Raymond; Wankhede, Mamta; Sorg, Brian S.

    2011-02-01

    Abnormal microvascular function and angiogenesis are key components of various diseases that can contribute to the perpetuation of the disease. Several skin diseases and ophthalmic pathologies are characterized by hypervascularity, and in cancer the microvasculature of tumors is structurally and functionally abnormal. Thus, the microvasculature can be an important target for treatment of diseases characterized by abnormal microvasculature. Motivated largely by cancer research, significant effort has been devoted to research on drugs that target the microvasculature. Several vascular targeting drugs for cancer therapy are in clinical trials and approved for clinical use, and several off-label uses of these drugs have been reported for non-cancer diseases. The ability to image and measure parameters related to microvessel function preclinically in laboratory animals can be useful for development and comparison of vascular targeting drugs. For example, blood supply time measurements give information related to microvessel morphology and can be measured with first-pass fluorescence imaging. Hemoglobin saturation measurements give an indication of microvessel oxygen transport and can be measured with spectral imaging. While each measurement individually gives some information regarding microvessel function, the measurements together may yield even more information since theoretically microvessel morphology can influence microvessel oxygenation, especially in metabolically active tissue like tumors. However, these measurements have not yet been combined. In this study, we report the combination of blood supply time imaging and hemoglobin saturation imaging of microvessel networks in tumors using widefield fluorescence and spectral imaging, respectively. The correlation between the measurements in a mouse mammary tumor is analyzed.

  17. Predicting subsequent bone density response to intermittent cyclical therapy with etidronate from initial density response in patients with osteoporosis.

    PubMed

    Crilly, R G; Sebaldt, R J; Hodsman, A B; Adachi, J D; Brown, J P; Goldsmith, C H; Hanley, D A; Olszynski, W O; Ste-Marie, L G; Stephenson, G F

    2000-01-01

    We investigated whether an increase in lumbar spine bone mineral density (LS BMD) at 6 months or at 12 months could predict the response to intermittent cyclical therapy (ICT) with etidronate, defined in one of two ways: (i) an increase in LS BMD at 24 months (improvement) or (ii) an increase in LS BMD > or = 0.028 g/cm2 (significant improvement). The latter is a precision term calculated from test-retest values for LS BMD in osteoporotic patients. Two hundred and forty-seven patients (32 men; 5 premenopausal and 210 postmenopausal women) were followed for 24 months by dual-energy X-ray absorptiometry (DXA) and were not taking estrogen, calcitonin or fluoride during treatment with ICT-etidronate. One hundred and fifty patients had a LS BMD measurement after 6 months of treatment with ICT-etidronate and 205 patients had one at 12 months. Baseline characteristics (mean;SD) were as follows: age, 66;11 years; years since menopause, 21;10; number of vertebral fractures at baseline, 0.87;1.26; LS BMD T-score, -2.8; 1.2. After 24 months of treatment with ICT-etidronate, 81% of the patients had an improvement, and 55% had a significant improvement at the LS. Only 6% significantly lost bone (loss of 0.028 g/cm2 or more). The mean percent change from baseline in LS BMD was 5.1% (95% confidence interval 4.2% to 6.0%). The results for men and postmenopausal women were similar to those for the entire group. Accuracy and sensitivity were marginally, but not significantly, higher when response was predicted using 12 month versus 6 month LS BMD measurements. The positive predictive values of improvement at 6 or 12 months were 89% and 90% respectively for improvement at 24 months, and 66% and 68% for significant improvement at 24 months. Identification of nonresponders was less successful and similar at 6 months and 12 months. Forty percent and 39% of the patients, who had no improvement at 6 or 12 months respectively, also had no improvement at 24 months, i.e., were true negatives

  18. Relation of initial spacing and relative stand density indices to stand characteristics in a Douglas-fir plantation spacing trial

    USGS Publications Warehouse

    Curtis, Robert O.; Bansal, Sheel; Harrington, Constance A.

    2016-01-01

    This report presents updated information on a 1981 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) plantation spacing trial at 33 years from planting. Stand statistics at the most recent measurement were compared for initial spacing of 1 through 6 meters and associated relative densities. There was no clear relationship of spacing to top height. Diameter, live crown ratio, and percent survival increased with spacing; basal area and relative density decreased with increase in spacing. Volume in trees ≥ 4 cm diameter was greatest at 2 m spacing, while utilizable volume (trees ≥20 cm dbh) was greatest at 4 m spacing. Live crown ratio decreased and total crown projectional area increased with increasing relative density indices. Total crown projectional area was more closely related to relative density than to basal area.

  19. The effect of air density on atmospheric electric fields required for lightning initiation from a long airborne object

    NASA Astrophysics Data System (ADS)

    Bazelyan, E. M.; Aleksandrov, N. L.; Raizer, Yu. P.; Konchakov, A. M.

    2007-11-01

    The purpose of the work was to determine minimum atmospheric electric fields required for lightning initiation from an airborne vehicle at various altitudes up to 10 km. The problem was reduced to the determination of a condition for initiation of a viable positive leader from a conductive object in an ambient electric field. It was shown that, depending on air density and shape and dimensions of the object, critical atmospheric fields are governed by the condition for leader viability or that for corona onset. To establish quantitative criteria for reduced air densities, available observations of spark discharges in long laboratory gaps were analyzed, the effect of air density on leader velocity was discussed and evolution in time of the properties of plasma in the leader channel was numerically simulated. The results obtained were used to evaluate the effect of pressure on the quantitative relationships between the potential difference near the leader tip, leader current and its velocity; based on these relationships, criteria for steady development of a leader were determined for various air pressures. Atmospheric electric fields required for lightning initiation from rods and ellipsoidal objects of various dimensions were calculated at different air densities. It was shown that there is no simple way to extend critical ambient fields obtained for some given objects and pressures to other objects and pressures.

  20. The Effect of Air Density on Atmospheric Electric Fields Required for Lightning Initiation from a Long Airborne Object

    NASA Technical Reports Server (NTRS)

    Bazelyan, E. M.; Aleksandrov, N. L.; Raizer, Yu. Pl.; Konchankov, A. M.

    2006-01-01

    The purpose of the work was to determine minimum atmospheric electric fields required for lightning initiation from an airborne vehicle at various altitudes up to 10 km. The problem was reduced to the determination of a condition for initiation of a viable positive leader from a conductive object in an ambient electric field. It was shown that, depending on air density and shape and dimensions of the object, critical atmospheric fields are governed by the condition for leader viability or that for corona onset. To establish quantitative criteria for reduced air densities, available observations of spark discharges in long laboratory gaps were analyzed, the effect of air density on leader velocity was discussed and evolution in time of the properties of plasma in the leader channel was numerically simulated. The results obtained were used to evaluate the effect of pressure on the quantitative relationships between the potential difference near the leader tip, leader current and its velocity; based on these relationships, criteria for steady development of a leader were determined for various air pressures. Atmospheric electric fields required for lightning initiation from rods and ellipsoidal objects of various dimensions were calculated at different air densities. It was shown that there is no simple way to extend critical ambient fields obtained for some given objects and pressures to other objects and pressures.

  1. Identification of P-glycoprotein co-fractionating proteins and specific binding partners in rat brain microvessels.

    PubMed

    Tome, Margaret E; Schaefer, Charles P; Jacobs, Leigh M; Zhang, Yifeng; Herndon, Joseph M; Matty, Fabian O; Davis, Thomas P

    2015-07-01

    Drug delivery to the brain for the treatment of pathologies with a CNS component is a significant clinical challenge. P-glycoprotein (PgP), a drug efflux pump in the endothelial cell membrane, is a major factor in preventing therapeutics from crossing the blood-brain barrier (BBB). Identifying PgP regulatory mechanisms is key to developing agents to modulate PgP activity. Previously, we found that PgP trafficking was altered concomitant with increased PgP activity and disassembly of high molecular weight PgP-containing complexes during acute peripheral inflammatory pain. These data suggest that PgP activity is post-translationally regulated at the BBB. The goal of the current study was to identify proteins that co-localize with PgP in rat brain microvessel endothelial cell membrane microdomains and use the data to suggest potential regulatory mechanisms. Using new density gradients of microvessel homogenates, we identified two unique pools (1,2) of PgP in membrane fractions. Caveolar constituents, caveolin1, cavin1, and cavin2, co-localized with PgP in these fractions indicating the two pools contained caveolae. A chaperone (Hsc71), protein disulfide isomerase and endosomal/lysosomal sorting proteins (Rab5, Rab11a) also co-fractionated with PgP in the gradients. These data suggest signaling pathways with a potential role in post-translational regulation of PgP activity at the BBB. PMID:25832806

  2. Colonisation of the non-indigenous Pacific oyster crassostrea gigas determined by predation, size and initial settlement densities.

    PubMed

    Hedge, Luke H; Johnston, Emma L

    2014-01-01

    Survival of incipient non-indigenous populations is dramatically altered by early predation on new colonisers. These effects can be influenced by morphological traits, such as coloniser size and density. The Australian non-native Pacific Oyster Crassostrea gigas is generally more fecund and faster growing compared to the native Saccostrea glomerata found in the same habitat. It is therefore important to quantify how the two species differ in survival across coloniser density and predation gradients. This information could become pertinent to the management of wild and aquaculture populations of the non-native C. gigas. Using a field-based factorial experiment we model the survival of incipient populations of both the native S. glomerata and the non-indigenous C. gigas as a function of coloniser density, predator reduction and individual size. Unexpectedly, survival of the non-indigenous C. gigas increased compared to S. glomerata when individuals were larger. The proportional survival of newly colonised oyster populations also increased with larger initial populations, regardless of species identity. Further, predator reduction resulted in increased survival of both oyster species, irrespective of coloniser size or initial density. Here we quantitatively demonstrate the effects of recruit density and size on enhancing the survivability of incipient oyster populations.

  3. Spectral imaging reveals microvessel physiology and function from anastomoses to thromboses

    PubMed Central

    Wankhede, Mamta; Agarwal, Nikita; Fraga-Silva, Rodrigo A.; deDeugd, Casey; Raizada, Mohan K.; Oh, S. Paul; Sorg, Brian S.

    2010-01-01

    Abnormal microvascular physiology and function is common in many diseases. Numerous pathologies include hypervascularity, aberrant angiogenesis, or abnormal vascular remodeling among the characteristic features of the disease, and quantitative imaging and measurement of microvessel function can be important to increase understanding of these diseases. Several optical techniques are useful for direct imaging of microvascular function. Spectral imaging is one such technique that can be used to assess microvascular oxygen transport function with high spatial and temporal resolution in microvessel networks through measurements of hemoglobin saturation. We highlight novel observation made with our intravital microscopy spectral imaging system employed with mouse dorsal skin-fold window chambers for imaging hemoglobin saturation in microvessel networks. Specifically, we image acute oxygenation fluctuations in a tumor microvessel network, the development of arteriovenous malformations in a mouse model of hereditary hemorrhagic telangiectasia, and the formation of spontaneous and induced microvascular thromboses and occlusions. PMID:20210437

  4. Reactive flow modeling of initial density effect on divergence JB-9014 detonation driving

    NASA Astrophysics Data System (ADS)

    Yu, Xin; Huang, Kuibang; Zheng, Miao

    2016-06-01

    A serious of experiments were designed and the results were represented in this paper, in which 2mm thickness cooper shells were impacted by explosives named JB-9014 with different densities, and the surface velocities of the OFHC shells were measured. The comparison of experimental data shows the free surface velocity of the OFHC shell increase with the IHE density. Numerical modeling, which occupied phenomenological reactive flow rate model using the two-dimensional Lagrange hydrodynamic code, were carried out to simulate the above experiments, and empirical adjustments on detonation velocity and pressure and Pier Tang's adjustments on EOS of detonation products were both introduced in our numerical simulation work. The computational results agree well with that of experiments, and the numerical results with original parameters of products and the adjusted ones of JB-9014 could describe the density effect distinctly.

  5. Flow of Red Blood Cells in Stenosed Microvessels

    PubMed Central

    Vahidkhah, Koohyar; Balogh, Peter; Bagchi, Prosenjit

    2016-01-01

    A computational study is presented on the flow of deformable red blood cells in stenosed microvessels. It is observed that the Fahraeus-Lindqvist effect is significantly enhanced due to the presence of a stenosis. The apparent viscosity of blood is observed to increase by several folds when compared to non-stenosed vessels. An asymmetric distribution of the red blood cells, caused by geometric focusing in stenosed vessels, is observed to play a major role in the enhancement. The asymmetry in cell distribution also results in an asymmetry in average velocity and wall shear stress along the length of the stenosis. The discrete motion of the cells causes large time-dependent fluctuations in flow properties. The root-mean-square of flow rate fluctuations could be an order of magnitude higher than that in non-stenosed vessels. Several folds increase in Eulerian velocity fluctuation is also observed in the vicinity of the stenosis. Surprisingly, a transient flow reversal is observed upstream a stenosis but not downstream. The asymmetry and fluctuations in flow quantities and the flow reversal would not occur in absence of the cells. It is concluded that the flow physics and its physiological consequences are significantly different in micro- versus macrovascular stenosis. PMID:27319318

  6. Flow of Red Blood Cells in Stenosed Microvessels

    NASA Astrophysics Data System (ADS)

    Vahidkhah, Koohyar; Balogh, Peter; Bagchi, Prosenjit

    2016-06-01

    A computational study is presented on the flow of deformable red blood cells in stenosed microvessels. It is observed that the Fahraeus-Lindqvist effect is significantly enhanced due to the presence of a stenosis. The apparent viscosity of blood is observed to increase by several folds when compared to non-stenosed vessels. An asymmetric distribution of the red blood cells, caused by geometric focusing in stenosed vessels, is observed to play a major role in the enhancement. The asymmetry in cell distribution also results in an asymmetry in average velocity and wall shear stress along the length of the stenosis. The discrete motion of the cells causes large time-dependent fluctuations in flow properties. The root-mean-square of flow rate fluctuations could be an order of magnitude higher than that in non-stenosed vessels. Several folds increase in Eulerian velocity fluctuation is also observed in the vicinity of the stenosis. Surprisingly, a transient flow reversal is observed upstream a stenosis but not downstream. The asymmetry and fluctuations in flow quantities and the flow reversal would not occur in absence of the cells. It is concluded that the flow physics and its physiological consequences are significantly different in micro- versus macrovascular stenosis.

  7. Analysis of correlation between initial alveolar bone density and apical root resorption after 12 months of orthodontic treatment without extraction

    PubMed Central

    Scheibel, Paula Cabrini; Ramos, Adilson Luiz; Iwaki, Lilian Cristina Vessoni; Micheletti, Kelly Regina

    2014-01-01

    OBJECTIVE: The aim of the present study was to investigate the correlation between initial alveolar bone density of upper central incisors (ABD-UI) and external apical root resorption (EARR) after 12 months of orthodontic movement in cases without extraction. METHODS: A total of 47 orthodontic patients 11 years old or older were submitted to periapical radiography of upper incisors prior to treatment (T1) and after 12 months of treatment (T2). ABD-UI and EARR were measured by means of densitometry. RESULTS: No statistically significant correlation was found between initial ABD-UI and EARR at T2 (r = 0.149; p = 0.157). CONCLUSION: Based on the present findings, alveolar density assessed through periapical radiography is not predictive of root resorption after 12 months of orthodontic treatment in cases without extraction. PMID:25715722

  8. Influence of initial pesticide concentrations and plant population density on dimethomorph toxicity and removal by two duckweed species.

    PubMed

    Dosnon-Olette, Rachel; Couderchet, Michel; El Arfaoui, Achouak; Sayen, Stéphanie; Eullaffroy, Philippe

    2010-04-15

    Aquatic plants take up, transform and sequester organic contaminants and may therefore be used in phytoremediation for the removal of pollutants from wastewaters. A better understanding of factors affecting the rate of contaminant uptake by aquatic plants is needed to improve engineered systems for removal of pollutants from wastewaters. This work focused on the influence of initial concentrations of pesticide and population density of plants on toxicity and uptake of the fungicide dimethomorph by two duckweed species. An increased sensitivity to dimethomorph was observed with increasing duckweed population density. Less light, due to crowding, may explain this higher sensitivity and reduced removal rate. A positive relationship was also found between toxicity or contaminant uptake and initial pesticide concentration with a maximal removal of 41 and 26 microg g(-1) fresh weight of dimethomorph (at 600 microg L(-1) of dimethomorph and an initial density of 0.10g E-flask(-1)) by Lemna minor and Spirodela polyrhiza, respectively. This research also indicated that these aquatic plants can efficiently eliminate organic contaminants and may ultimately serve as phytoremediation agents in the natural environment.

  9. Exaggerated myocardial oxLDL amount and LOX-1 receptor over-expression associated with coronary microvessel inflammation in unstable angina.

    PubMed

    Neri Serneri, Gian Gastone; Coppo, Mirella; Bandinelli, Manuela; Paoletti, Paoletto; Toscano, Thomas; Micalizzi, Ezio; Chiostri, Marco; Boddi, Maria

    2013-02-01

    The pathophysiological relationship between coronary atherosclerosis and coronary microvessels remains undefined and the specific causative role of oxidatively modified low density lipoprotein (oxLDL) in human atherosclerosis is debated. The purposes of this study are to investigate whether coronary microvessels are involved in coronary atherosclerosis and whether increased myocardial oxLDL amount can be associated with coronary microvessel inflammation. A combination of immunohistochemical, RT-PCR and real-time PCR studies performed on myocardial biopsy specimens from patients with mitral stenosis (control hearts, CHs) and from unstable and stable angina patients (UAP and SAP), demonstrated that myocardial oxLDL was associated with a chronic low-grade inflammation in SAP and with a severe high grade inflammation in UAP. oxLDL amount was notably higher in UAP than in SAP and in UAP the high grade of inflammation was correlated with the increased amount of oxLDL in endothelial cells and macrophages. The exaggerated amount of oxLDL in UAP and the interaction of oxLDL with lectin-like oxLDL (LOX-1) receptor are amplified by the activation of transcriptional factor octamere 1 (OCT-1) with consequent activation of a series of inflammatory endothelial feed-back mechanisms resulting in LOX-1 gene over-expression, endothelial inflammation as well as uncontrolled nuclear factor kappa B (NFkB) activation. Moreover, in UAP genes for signal transducer and activator transcriptional factor 1α (STAT1α), angiotensin converting enzyme (ACE) and numerous pro-inflammatory cytokines were over-expressed. The present results may have clinical relevance because they show that coronary atherosclerosis is a disease not confined to the large arteries but involving the whole coronary tree. In UAP the exaggerated amount of myocardial oxLDL is associated with widespread high grade microvessel inflammation. PMID:23237633

  10. Characterization of atrial natriuretic peptide receptors in brain microvessel endothelial cells

    NASA Technical Reports Server (NTRS)

    Whitson, P. A.; Huls, M. H.; Sams, C. F.

    1991-01-01

    Atrial natriuretic peptide (ANP) binding and ANP-induced increases in cyclic guanosine monophosphate (cGMP) levels have been observed in brain microvessels (Chabrier et al., 1987; Steardo and Nathanson, 1987), suggesting that this fluid-regulating hormone may play a role in the fluid homeostasis of the brain. This study was initiated to characterize the ANP receptors in primary cultures of brain microvessel endothelial cells (BMECs). The apparent equilibrium dissociation constant, Kd, for ANP increased from 0.25 nM to 2.5 nM, and the number of ANP binding sites as determined by Scatchard analysis increased from 7,100 to 170,000 sites/cell between 2 and 10 days of culture following monolayer formation. Time- and concentration-dependent studies on the stimulation of cGMP levels by ANP indicated that guanylate cyclase-linked ANP receptors were present in BMECs. The relative abilities of ANP, brain natriuretic peptide (BNP), and a truncated analog of ANP containing amino acids 5-27 (ANP 5-27) to modulate the accumulation of cGMP was found to be ANP greater than BNP much greater than ANP 5-27. Affinity cross-linking with disuccinimidyl suberate and radiolabeled ANP followed by gel electrophoresis under reducing conditions demonstrated a single band corresponding to the 60-70 kD receptor, indicating the presence of the nonguanylate cyclase-linked ANP receptor. Radiolabeled ANP binding was examined in the presence of various concentrations of either ANP, BNP, or ANP 5-27 and suggested that a large proportion of the ANP receptors present in blood-brain barrier endothelial cells bind all of these ligands similarly. These data indicate both guanylate cyclase linked and nonguanylate cyclase linked receptors are present on BMECs and that a higher proportion of the nonguanylate cyclase linked receptors is expressed. This in vitro culture system may provide a valuable tool for the examination of ANP receptor expression and function in blood-brain barrier endothelial cells.

  11. An experimental investigation of the dynamics of submarine leveed channel initiation as sediment-laden density currents experience sudden unconfinement

    SciTech Connect

    Rowland, Joel C; Hilley, George E; Fildani, Andrea

    2009-01-01

    Leveed submarine channels play a critical role in the transfer of sediment from the upper continental slopes to interslope basins and ultimately deepwater settings. Despite a reasonable understanding of how these channels grow once established, how such channels initiate on previously unchannelized portions of the seafloor remains poorly understood. We conducted a series of experiments that elucidate the influence of excess density relative to flow velocity on the dynamics of, and depositional morphologies arising from, density currents undergoing sudden unconfinement across a sloped bed. Experimental currents transported only suspended sediment across a non-erodible substrate. Under flow conditions ranging from supercritical to subcritical (bulk Richardson numbers of 0.02 to 1.2) our experiments failed to produce deposits resembling or exhibiting the potential to evolve into self-formed leveed channels. In the absence of excess density, a submerged sediment-laden flow produced sharp crested lateral deposits bounding the margins of the flow for approximately a distance of two outlet widths down basin. These lateral deposits terminated in a centerline deposit that greatly exceeded marginal deposits in thickness. As excess density increased relative to the outlet velocity, the rate of lateral spreading of the flow increased relative to the downstream propagation of the density current, transitioning from a narrow flow aligned with the channel outlet to a broad radially expanding flow. Coincident with these changes in flow dynamics, the bounding lateral deposits extended for shorter distances, had lower, more poorly defined crests that were increasingly wider in separation than the initial outlet, and progressively became more oblong rather than linear. Based on our results, we conclude that leveed channels cannot initiate from sediment-laden density currents under strictly depositional conditions. Partial confinement of these currents appears to be necessary to

  12. Strain energy density: Distance criterion for the initiation of hydrogen-induced cracking of Alloy X-750

    SciTech Connect

    Hall, M.M. Jr.; Symons, D.M.; Kearns, J.J.

    1991-12-31

    A criterion for initiation of subcritical crack growth at blunt notches and sharp defects was developed and applied to hydrogen- induced cracking of the Ni-base superalloy X-750. Onset of crack growth is shown to occur when a critical strain energy density is attained at a distance from the notch and crack tips characteristic of the microstructure along the prospective crack path. Rising load crack growth initiation data were obtained using homogeneous hydrogen precharged notched and fatigue precracked bend specimens. Notch root radius, grain size and hydrogen concentration were varied. Crack growth initiation loads were dependent on both notch root radius and bulk precharged hydrogen concentration. These data were shown to be correlated using a critical strain energy at-a-distance (SEDAD) criterion. Furthermore, an elastic-plastic analysis of the strain energy distributions showed that the critical strain energy density value is attained at one grain diameter from the notch and fatigue precrack tips. Mechanical and microstructural aspects of crack growth process and relevance to hydrogen-induced cracking are discussed.

  13. Oxidized low-density lipoproteins upregulate proline oxidase to initiate ROS-dependent autophagy.

    PubMed

    Zabirnyk, Olga; Liu, Wei; Khalil, Shadi; Sharma, Anit; Phang, James M

    2010-03-01

    Epidemiological studies showed that high levels of oxidized low-density lipoproteins (oxLDLs) are associated with increased cancer risk. We examined the direct effect of physiologic concentrations oxLDL on cancer cells. OxLDLs were cytotoxic and activate both apoptosis and autophagy. OxLDLs have ligands for peroxisome proliferator-activated receptor gamma and upregulated proline oxidase (POX) through this nuclear receptor. We identified 7-ketocholesterol (7KC) as a main component responsible for the latter. To elucidate the role of POX in oxLDL-mediated cytotoxicity, we knocked down POX via small interfering RNA and found that this (i) further reduced viability of cancer cells treated with oxLDL; (ii) decreased oxLDL-associated reactive oxygen species generation; (iii) decreased autophagy measured via beclin-1 protein level and light-chain 3 protein (LC3)-I into LC3-II conversion. Using POX-expressing cell model, we established that single POX overexpression was sufficient to activate autophagy. Thus, it led to autophagosomes accumulation and increased conversion of LC3-I into LC3-II. Moreover, beclin-1 gene expression was directly dependent on POX catalytic activity, namely the generation of POX-dependent superoxide. We conclude that POX is critical in the cellular response to the noxious effects of oxLDL by activating protective autophagy.

  14. Initial Diagnostics and First Experimental Results of the Pulsed High Density (PHD) FRC Experiment*

    NASA Astrophysics Data System (ADS)

    Gota, Hiroshi

    2005-10-01

    The source region for the Pulsed High Density Experiment (PHDX) has been constructed, and Field-Reversed Configuration (FRC) plasmas are being produced. The several diagnostic systems include and axial array of 20 pairs of magnetic probes and flux loops, and a 64 channel array optical measurement system for visible bremstrahlung tomography. The tomographic system will be capable of reconstructing the plasma shape and mode structure, and will incorporate information from end-on imaging for improved resolution. This array consists of collimator, optical fiber, optical filter (λ=520 nm, FWHM= 1 to 10 nm), and Photomultiplier Tube (PMT). The tomographic system and magnetic loop array will be used to investigate the equilibrium and tilt stability of FRCs at high s/E (>3) where s is the ion collisionless skin depth and E is the plasma elongation. The separatrix radius (rs) of FRC plasma is determined by the excluded flux measurement, and it is found that rs=0.04-0.05 m (rs/rw=0.16-0.2) just after the RMF current drive start-up. The time sequence of separatrix shape relatively agrees with the result of that estimated from the line-integrated radiation intensity at different axial positions. We will present the result of both simulation and experimental results from measured FRC plasmas as well as future plans. *Research funded by the DOE Office of Fusion Energy Sciences

  15. Flow of a circulating tumor cell and red blood cells in microvessels

    NASA Astrophysics Data System (ADS)

    Takeishi, Naoki; Imai, Yohsuke; Yamaguchi, Takami; Ishikawa, Takuji

    2015-12-01

    Quantifying the behavior of circulating tumor cells (CTCs) in the blood stream is of fundamental importance for understanding metastasis. Here, we investigate the flow mode and velocity of CTCs interacting with red blood cells (RBCs) in various sized microvessels. The flow of leukocytes in microvessels has been described previously; a leukocyte forms a train with RBCs in small microvessels and exhibits margination in large microvessels. Important differences in the physical properties of leukocytes and CTCs result from size. The dimensions of leukocytes are similar to those of RBCs, but CTCs are significantly larger. We investigate numerically the size effects on the flow mode and the cell velocity, and we identify similarities and differences between leukocytes and CTCs. We find that a transition from train formation to margination occurs when (R -a ) /tR≈1 , where R is the vessel radius, a is the cell radius, and tR is the thickness of RBCs, but that the motion of RBCs differs from the case of leukocytes. Our results also show that the velocities of CTCs and leukocytes are larger than the average blood velocity, but only CTCs move faster than RBCs for microvessels of R /a ≈1.5 -2.0 . These findings are expected to be useful not only for understanding metastasis, but also for developing microfluidic devices.

  16. High-Density Transcriptional Initiation Signals Underline Genomic Islands in Bacteria

    PubMed Central

    Huang, Qianli; Cheng, Xuanjin; Cheung, Man Kit; Kiselev, Sergey S.; Ozoline, Olga N.; Kwan, Hoi Shan

    2012-01-01

    Genomic islands (GIs), frequently associated with the pathogenicity of bacteria and having a substantial influence on bacterial evolution, are groups of “alien” elements which probably undergo special temporal–spatial regulation in the host genome. Are there particular hallmark transcriptional signals for these “exotic” regions? We here explore the potential transcriptional signals that underline the GIs beyond the conventional views on basic sequence composition, such as codon usage and GC property bias. It showed that there is a significant enrichment of the transcription start positions (TSPs) in the GI regions compared to the whole genome of Salmonella enterica and Escherichia coli. There was up to a four-fold increase for the 70% GIs, implying high-density TSPs profile can potentially differentiate the GI regions. Based on this feature, we developed a new sliding window method GIST, Genomic-island Identification by Signals of Transcription, to identify these regions. Subsequently, we compared the known GI-associated features of the GIs detected by GIST and by the existing method Islandviewer to those of the whole genome. Our method demonstrates high sensitivity in detecting GIs harboring genes with biased GI-like function, preferred subcellular localization, skewed GC property, shorter gene length and biased “non-optimal” codon usage. The special transcriptional signals discovered here may contribute to the coordinate expression regulation of foreign genes. Finally, by using GIST, we detected many interesting GIs in the 2011 German E. coli O104:H4 outbreak strain TY-2482, including the microcin H47 system and gene cluster ycgXEFZ-ymgABC that activates the production of biofilm matrix. The aforesaid findings highlight the power of GIST to predict GIs with distinct intrinsic features to the genome. The heterogeneity of cumulative TSPs profiles may not only be a better identity for “alien” regions, but also provide hints to the special

  17. Initial oxidation of gallium arsenide (001)-β2(2 x 4) surface using density functional theory.

    PubMed

    Kim, Dae-Hee; Kim, Dae-Hyun; Kim, Yeong-Cheol

    2014-10-01

    The initial oxidation of a gallium arsenide (001)-β2(2 x 4) surface with an oxygen molecule was investigated using density functional theory. The oxygen molecule was adsorbed on the surface without any energy barrier. The dissociation of the oxygen molecule on the first arsenic layer had two dissociation paths; the inter-dimer and intra-dimer. The inter-dimer dissociation was the dominant dissociation path based on the energy barriers. The two dissociated oxygen atoms preferred breaking the arsenic-gallium back-bond to form arsenic-oxygen-gallium bonds. Our results are in good agreement with literature of the scanning tunneling microscope study.

  18. LIPUS promotes spinal fusion coupling proliferation of type H microvessels in bone

    PubMed Central

    Xu, Ximing; Wang, Fei; Yang, Yahong; Zhou, Xiaoyi; Cheng, Yajun; Wei, Xianzhao; Li, Ming

    2016-01-01

    Low-intensity pulsed ultrasound (LIPUS) has been found to accelerate spinal fusion. Type H microvessels are found in close relation with bone development. We analyzed the role of type H vessels in rat spinal fusion model intervened by LIPUS. It was found LIPUS could significantly accelerate bone fusion rate and enlarge bone callus. Osteoblasts were specifically located on the bone meshwork of the allograft, and were surrounded by type H microvessels. LIPUS could significantly increase the quantity of osteoblasts during spine fusion, which process was coupled with elevated angiogenesis of type H microvessels. Our results suggest that LIPUS may be a noninvasive adjuvant treatment modality in spinal fusion for clinical use. The treatment is recommended for usage for at least one month. PMID:26830666

  19. Relationship Between Crop Losses and Initial Population Densities of Meloidogyne arenaria in Winter-Grown Oriental Melon in Korea

    PubMed Central

    Kim, D.G.; Ferris, H.

    2002-01-01

    To determine the economic threshold level, oriental melon (Cucumis melo L. cv. Geumssaragi-euncheon) grafted on Shintozoa (Cucurbita maxima × Cu. moschata) was planted in plots (2 × 3 m) under a plastic film in February with a range of initial population densities (Pi) of Meloidogyne arenaria. The relationships of early, late, and total yield to Pi measured in September and January were adequately described by both linear regression and the Seinhorst damage model. Initial nematode densities in September in excess of 14 second-stage juveniles (J2)/100 cm³ soil caused losses in total yields that exceeded the economic threshold and indicate the need for fosthiazate nematicide treatment at current costs. Differences in yield-loss relationships to Pi between early- and late-season harvests enhance the resolution of the management decision and suggest approaches for optimizing returns. Determination of population levels for advisory purposes can be based on assay samples taken several months before planting, which allows time for implementation of management procedures. We introduce (i) an amendment of the economic threshold definition to reflect efficacy of the nematode management procedure under consideration, and (ii) the concept of profit limit as the nematode population at which net returns from the system will become negative. PMID:19265907

  20. A comparison of the effects of initializing different thermosphere-ionosphere model fields on storm time plasma density forecasts

    NASA Astrophysics Data System (ADS)

    Chartier, Alex T.; Jackson, David R.; Mitchell, Cathryn N.

    2013-11-01

    assimilation has been used successfully for real-time ionospheric specification, but it has not yet proved advantageous for forecasting. The most challenging and important ionospheric events to forecast are storms. The work presented here examines the effectiveness of data assimilation in a storm situation, where the initial conditions are known and the model is considered to be correct but the external solar and geomagnetic drivers are poorly specified. The aim is to determine whether data assimilation could be used to improve storm time forecast accuracy. The results show that, in the case of the storm of Halloween 2003, changes made to the model's initial thermospheric conditions improve electron density forecasts by at least 10% for 18 h, while changes to ionospheric fields alone result in >10% forecast accuracy improvement for less than 4 h. Further examination shows that the neutral composition is especially important to the accuracy of ionospheric electron density forecasts. Updating the neutral composition gives almost all the benefits of updating the complete thermospheric state. A comparison with real, globally distributed observations of vertical total electron content confirms that updating the thermospheric composition can improve forecast accuracy.

  1. The correlation between microvessel pathological changes of the endplate and degeneration of the intervertebral disc in diabetic rats

    PubMed Central

    CHEN, SEN; LIAO, MEIMEI; LI, JIANPING; PENG, HAO; XIONG, MIN

    2013-01-01

    In this study, the pathological microvessel changes to the endplate and the degeneration of the intervertebral disc of diabetic rats were examined in order to identify the possible mechanism by which diabetes mellitus (DM) induces degeneration of the intervertebral disc. A total of 30 Sprague-Dawley rats were randomly divided into two groups. DM was induced in one of the groups by streptozotocin (STZ) administration. The rats were sacrificed 4, 8 and 12 weeks later. Five rats from each group were sacrificed at each time interval and lumbar disc and endplate tissue were obtained from each rat. The histological changes, collagen expression, microvessel density (MVD) and apoptosis of the disc were investigated by different methods. The expression of collagen I in the diabetic DM group was higher compared to the control group at the three time points (P<0.01), in contrast to the expression of collagen II. The factor VIII-related antigen (FVIII RAg) was expressed in the control and DM groups, while its expression was relatively low in the DM group. The MVD of the DM group was smaller compared to that of the control group at the three time points (P<0.01). The apoptotic index (AI) in the diabetic group was significantly higher compared to that of the control group at the three time points (P<0.01). A negative correlation was observed between the MVD of the endplates and the notochordal cell AI in the two groups. Compared to the control group, the endplate MVD decreased and the cavity became smaller or disappeared in the diabetic rats. In conclusion, there was a negative correlation between MVD and degenerative changes of the intervertebral disc in diabetic rats. PMID:23408796

  2. Fully automated microvessel counting and hot spot selection by image processing of whole tumour sections in invasive breast cancer.

    PubMed Central

    Beliën, J A; Somi, S; de Jong, J S; van Diest, P J; Baak, J P

    1999-01-01

    BACKGROUND: Manual counting of microvessels is subjective and may lead to unacceptable interobserver variability, which may explain conflicting results. AIMS: To develop and test an automated method for microvessel counting and objective selection of the hot spot, based on image processing of whole sections, and to compare this with manual selection of a hot spot and counting of microvessels. METHODS: Microvessels were stained by CD31 immunohistochemistry in 10 cases of invasive breast cancer. The number of microvessels was counted manually in a subjectively selected hot spot, and also in the same complete tumour sections by interactive and automated image processing methods. An algorithm identified the hot spots from microvessel maps of the whole tumour section. RESULTS: No significant difference in manual microvessel counts was found between two observers within the same hot spot, and counts were significantly correlated. However, when the hot spot was reselected, significantly different results were found between repeated counts by the same observer. Counting all microvessels manually within the entire tumour section resulted in significantly different hot spots than manual counts in selected hot spots by the same observer. Within the entire tumour section no significant differences were found between the hot spots of the manual and automated methods using an automated microscope. The hot spot was found using an eight connective path search algorithm, was located at or near the border of the tumour, and (depending on the size of the hot spot) did not always contain the field with the largest number of microvessels. CONCLUSIONS: The automated counting of microvessels is preferable to the manual method because of the reduction in measurement time when the complete tumour is scanned, the greater accuracy and objectivity of hot spot selection, and the possibility of visual inspection and relocation of each measurement field afterwards. Images PMID:10450177

  3. Dependence of optimal initial density on laser parameters for multi-keV x-ray radiators generated by nanosecond laser-produced underdense plasma

    NASA Astrophysics Data System (ADS)

    Tu, Shao-yong; Yuan, Yong-teng; Hu, Guang-yue; Miao, Wen-yong; Zhao, Bin; Zheng, Jian; Jiang, Shao-en; Ding, Yong-kun

    2016-01-01

    Efficient multi-keV x-ray sources can be produced using nanosecond laser pulse-heated middle-Z underdense plasmas generated using gas or foam. Previous experimental results show that an optimal initial target density exists for efficient multi-keV x-ray emission at which the laser ionization wave is supersonic. Here we explore the influence of the laser intensity and the pulse duration on this optimal initial target density via a one-dimensional radiation hydrodynamic simulation. The simulation shows that the optimal initial density is sensitive to both the laser intensity and the pulse duration. However, the speed of the supersonic ionization wave at the end of the laser irradiation is always maintained at 1.5 to 1.7 times that of the ion acoustic wave under the optimal initial density conditions.

  4. Quenched dynamics in interacting one-dimensional systems: Appearance of current carrying steady states from initial domain wall density profiles

    NASA Astrophysics Data System (ADS)

    Lancaster, Jarrett; Gull, Emanuel; Mitra, Aditi

    2011-03-01

    Dynamics arising after an interaction quench in the quantum sine-Gordon model is studied for the case of a system initially prepared in a spatially inhomogeneous domain wall state. The time-evolution of the density, current and equal time correlation functions are studied using the truncated Wigner approximation (TWA) to which quantum corrections are added in order to set the limits on its validity. For weak to moderate strengths of the back-scattering interaction, the domain wall is found to spread out ballistically with the system within the light cone reaching a non-equilibrium steady-state characterized by a net current flow. A steady state current is also found to exist for a quench at the exactly solvable Luther-Emery point. The magnitude of the current decreases with increasing strength of the back-scattering interaction. The two-point correlation function of the variable canonically conjugate to the density reaches a steady state which is spatially oscillating at a wavelength which is inversely related to the current. This was was supported by NSF-DMR (Award no. 1004589).

  5. Observations of the Flux Density of Some Interplanetary Type II and Type III Radio Bursts and Initial Comparisons With Theory

    NASA Astrophysics Data System (ADS)

    Cairns, I. H.; Mohamed, A. A. A.; Hillan, D.; Robinson, P. A.

    2015-12-01

    The measured intensity of a radio signal depends on the effective antenna length, which may vary with (at least) the plasma properties and radiation frequency. Here the effective antenna lengths are estimated as a function of frequency for the RAD1 and RAD2 instruments on the WIND spacecraft when in SUM mode. This is done by calibrating against the known galactic background radiation spectrum after removal of receiver noise and thermal plasma noise where possible. Flux density spectra and lower limits to the maximum brightness temperature are determined for three type II and three type III radio bursts based on two calibration methods, one of which uses the effective antenna lengths as a function of frequency. The second calibration method uses Wind data for the relative flux in dB to equate the minimum flux observed with the galactic background and receiver noise. The results emphasize that the second method is more successful in obtaining calibrated type II and III fluxes. Calibrated flux densities obtained show that The type IIs have similar maximum flux densities to the type III events in this sample, but the type IIs are much more variable in frequency and time. Theoretical predictions are obtained for shocks moving with a suitable range of initial speeds and accelerations. Dynamic spectra are then predicted for the three selected type II events using the theory of Knock et al. [2001] and a simple, unstructured, solar wind model. Because of the continuous emission of 24-26 August 1998 that is present in a wide range from 100 MHz to 21 kHz, albeit with strongly varying intensity, a comparison between its observed and predicted dynamic spectra is presented. The agreement between theory and data is discussed and the implications described for future modeling.

  6. Stimulation of proteoglycans by IGF I and II in microvessel and large vessel endothelial cells

    SciTech Connect

    Bar, R.S.; Dake, B.L.; Stueck, S.

    1987-07-01

    Endothelial cells were cultured from bovine capillaries and pulmonary arteries, and the effect of insulinlike growth factor (IGF) I and II (multiplication-stimulating activity) and insulin on the synthesis of proteoglycans was determined. IGF I and II stimulated /sup 35/SO/sub 4/ incorporation into proteoglycans in a dose-dependent manner in both microvessel and pulmonary artery endothelial cells with maximum threefold increases. In pulmonary artery cells, the IGFs caused a general stimulation of all classes of glycosaminoglycan-containing proteoglycans. In microvessel endothelial cells, the IGFs appeared to preferentially increase heparan sulfate-containing proteoglycans. Insulin, at concentrations up to 10/sup -6/ M, had no effect on the synthesis of proteoglycans in either microvessel or pulmonary arterial endothelial cells. Thus, the IGFs stimulate the synthesis of proteoglycans in both microvessel and large vessel endothelial cells, a property that is not mimicked by insulin. Because vascular endothelial cells are bathed by IGFs in vivo, such IGF-mediated functions are likely to be significant in both the normal physiology of vascular endothelium and in disease states such as diabetes mellitus.

  7. Quantifying single microvessel permeability in isolated blood-perfused rat lung preparation.

    PubMed

    Kandasamy, Kathirvel; Parthasarathi, Kaushik

    2014-01-01

    The isolated blood-perfused lung preparation is widely used to visualize and define signaling in single microvessels. By coupling this preparation with real time imaging, it becomes feasible to determine permeability changes in individual pulmonary microvessels. Herein we describe steps to isolate rat lungs and perfuse them with autologous blood. Then, we outline steps to infuse fluorophores or agents via a microcatheter into a small lung region. Using these procedures described, we determined permeability increases in rat lung microvessels in response to infusions of bacterial lipopolysaccharide. The data revealed that lipopolysaccharide increased fluid leak across both venular and capillary microvessel segments. Thus, this method makes it possible to compare permeability responses among vascular segments and thus, define any heterogeneity in the response. While commonly used methods to define lung permeability require postprocessing of lung tissue samples, the use of real time imaging obviates this requirement as evident from the present method. Thus, the isolated lung preparation combined with real time imaging offers several advantages over traditional methods to determine lung microvascular permeability, yet is a straightforward method to develop and implement.

  8. Low-frequency ultrasound-mediated microvessel disruption combined with docetaxel to treat prostate carcinoma xenografts in nude mice: A novel type of chemoembolization

    PubMed Central

    Yang, Yu; Bai, Wenkun; Chen, Yini; Nan, Shuliang; Lin, Yanduan; Ying, Tao; Hu, Bing

    2016-01-01

    The aim of the present study was to investigate whether low-frequency ultrasound (US)-mediated microvessel disruption combined with docetaxel (DTX) can be used as a novel type of chemoembolization. Mice were assigned to four groups: i) The USMB group, treated with low-frequency US combined with microbubbles (USMB); ii) the DTX group, treated with DTX; iii) the USMB + DTX group, treated with combined therapy; and iv) the control group, which was untreated. Immediately after the first treatment, the average peak intensity (API) on contrast-enhanced US was calculated, and tumors were excised for hematoxylin and eosin (HE) staining. At 2 weeks post-treatment, the tumor volumes and wet weights were calculated, and tumors were excised for immunohistochemistry to calculate apoptotic index (AI), proliferative index (PI) and microvessel density (MVD) values. Immediately after the first treatment, in the DTX and control groups, the tumors demonstrated abundant perfusion enhancement, while in the USMB + DTX and USMB groups, blood perfusion of the tumors was interrupted. Compared with that of the control group, the API was significantly lower in the USMB + DTX USMB groups (all P<0.001). HE staining showed that tumor microvasculature was disrupted into flaky hematomas and severely dilated microvessels in the USMB + DTX and USMB groups. In the DTX and control groups, there was no distinct evidence of the disruption and dilation of blood microvessels. At the end of the treatment, the mean tumor inhibition ratio was 73.33, 46.67 and 33.33% for the USMB + DTX, DTX and USMB groups, respectively. The USMB + DTX group had the highest AI, and the lowest PI and MVD compared with the other groups, although the difference between the USMB + DTX and DTX groups with regard to PI and MVD was not significant (USMB + DTX vs. DTX group, P=0.345 and P=0.059, respectively). In conclusion, as a novel type of chemoembolization, USMB combined with DTX is more effective than USMB or DTX alone in

  9. Initial hepatic removal of chylomicron remnants is unaffected but endocytosis is delayed in mice lacking the low density lipoprotein receptor.

    PubMed Central

    Herz, J; Qiu, S Q; Oesterle, A; DeSilva, H V; Shafi, S; Havel, R J

    1995-01-01

    Two endocytic receptors, the low density lipoprotein (LDL) receptor (LDLR) and the LDLR-related protein (LRP), are thought to act in concert in the hepatic uptake of partially metabolized dietary lipoproteins, the chylomicron remnants. We have evaluated the role of these two receptors in the hepatic metabolism of chylomicron remnants in normal mice and in LDLR-deficient [LDLR (-/-)] mice. The rate of chylomicron remnant removal by the liver was normal up to 30 min after intravenous injection of chylomicrons into LDLR (-/-) mice and was unaffected by receptor-associated protein (RAP), a potent inhibitor of ligand binding to LRP. In contrast, endocytosis of the remnants by the hepatocytes, measured by their accumulation in the endosomal fraction and by the rate of hydrolysis of component cholesteryl esters, was dramatically reduced in the absence of the LDLR. Coadministration of RAP prevented the continuing hepatic removal of chylomicron remnants in LDL (-/-) mice after 30 min, consistent with blockade of the slow endocytosis by a RAP-sensitive process. Taken together with previous studies, our results are consistent with a model in which the initial hepatic removal of chylomicron remnants is primarily mediated by mechanisms that do not include LDLR or LRP, possibly involving glycosaminoglycan-bound hepatic lipase and apolipoprotein E. After the remnants bind to these alternative sites on the hepatocyte surface, endocytosis is predominantly mediated by the LDLR and also by a slower and less efficient backup process that is RAP sensitive and therefore most likely involves LRP. PMID:7753850

  10. Ultra-high Speed Optical Imaging of Ultrasound-activated Microbubbles in Mesenteric Microvessels

    NASA Astrophysics Data System (ADS)

    Chen, Hong

    Ultrasound contrast agent microbubbles have gained widespread applications in diagnostic and therapeutic ultrasound. Animal studies of bioeffects induced by ultrasound-activated microbubbles have demonstrated that microbubbles can cause microvessel damage. Much scientific attention has been attracted to such microvascular bioeffects, not only because of the related safety concerns, but also because of the potential useful applications of microbubbles in the intravascular delivery of drugs and genetic materials into target tissues. A significant challenge in using microbubbles in medical ultrasound is the lack of knowledge about how the microbubbles behave in blood vessels when exposed to ultrasound and how their interactions with ultrasound cause vascular damage. Although extensive studies were performed in the past to study the dynamics of microbubbles, most of those studies were performed in vitro and did not directly address the clinical environment in which microbubbles are injected into blood vessels. In this thesis work, a synchronized optical-acoustic system was set up for ultrahigh speed imaging of insonated microbubbles in microvessels. The recorded images revealed the formation of microjets penetrating the microbubbles, as well as vessel distention (motion outward against the surrounding tissue) and vessel invagination (motion inward toward the lumen) caused by the expansion and collapse of the microbubbles, respectively. Contrary to current paradigms which propose that microbubbles damage vessels either by distending them or by forming liquid jets impinging on them, microbubbles translation and jetting were in the direction away from the nearest vessel wall; furthermore, invagination typically exceeded distention in arterioles and venules. Vessel invagination was found to be associated with vascular damage. These studies suggest that vessel invagination may be a newly discovered potential mechanism for vascular damage by ultrasound-activated microbubbles

  11. Effect of heat transfer on rotating electroosmotic flow through a micro-vessel: haemodynamical applications

    NASA Astrophysics Data System (ADS)

    Sinha, A.; Mondal, A.; Shit, G. C.; Kundu, P. K.

    2016-08-01

    This paper theoretically analyzes the heat transfer characteristics associated with electroosmotic flow of blood through a micro-vessel having permeable walls. The analysis is based on the Debye-Hückel approximation for charge distributions and the Navier-Stokes equations are assumed to represent the flow field in a rotating system. The velocity slip condition at the vessel walls is taken into account. The essential features of the rotating electroosmotic flow of blood and associated heat transfer characteristics through a micro-vessel are clearly highlighted by the variation in the non-dimensional flow velocity, volumetric flow rate and non-dimensional temperature profiles. Moreover, the effect of Joule heating parameter and Prandtl number on the thermal transport characteristics are discussed thoroughly. The study reveals that the flow of blood is appreciably influenced by the elctroosmotic parameter as well as rotating Reynolds number.

  12. In Vitro Recapitulation of Functional Microvessels for the Study of Endothelial Shear Response, Nitric Oxide and [Ca2+]i

    PubMed Central

    He, Pingnian; Liu, Yuxin

    2015-01-01

    Microfluidic technologies enable in vitro studies to closely simulate in vivo microvessel environment with complexity. Such method overcomes certain constrains of the statically cultured endothelial monolayers and enables the cells grow under physiological range of shear flow with geometry similar to microvessels in vivo. However, there are still existing knowledge gaps and lack of convincing evidence to demonstrate and quantify key biological features of the microfluidic microvessels. In this paper, using advanced micromanufacturing and microfluidic technologies, we presented an engineered microvessel model that mimicked the dimensions and network structures of in vivo microvessels with a long-term and continuous perfusion capability, as well as high-resolution and real-time imaging capability. Through direct comparisons with studies conducted in intact microvessels, our results demonstrated that the cultured microvessels formed under perfused conditions recapitulated certain key features of the microvessels in vivo. In particular, primary human umbilical vein endothelial cells were successfully cultured the entire inner surfaces of the microchannel network with well-developed junctions indicated by VE-cadherin staining. The morphological and proliferative responses of endothelial cells to shear stresses were quantified under different flow conditions which was simulated with three-dimensional shear dependent numerical flow model. Furthermore, we successfully measured agonist-induced changes in intracellular Ca2+ concentration and nitric oxide production at individual endothelial cell levels using fluorescence imaging. The results were comparable to those derived from individually perfused intact venules. With in vivo validation of its functionalities, our microfluidic model demonstrates a great potential for biological applications and bridges the gaps between in vitro and in vivo microvascular research. PMID:25965067

  13. The Mechanical Effects of Ultrasound Contrast Agents on Micro-vessels

    NASA Astrophysics Data System (ADS)

    Hosseinkhah, N.; Hynynen, K.

    2011-09-01

    Ultrasound activated contrast agents inside microvessels induce mechanical effects on the vessel wall. It is important to use the bubbles safely and avoid rupturing the vessels. The objective of this work was to develop a three dimensional model of a bubble, blood and micro-vessels in order to investigate the mechanical effects (mainly the fluid shear stress and the circumferential stress) by a non-inertial microbubble on the vessel wall. A finite element method was used to solve for this model numerically. The blood vessel was simulated as having a viscoelastic, elastic or a rigid wall. Acoustic pressure and frequency were varied and the values for fluid shear stress and circumferential stress on the vessel wall were calculated. The circumferential stress could exceed the vascular strength in rigid microvessels if the applied acoustic pressure is above 260 kPa. Also the values for fluid shear stress are large enough to induce hemolysis or damage the cell membrane close to the oscillating bubble. Next, the streamlines and stagnation points are obtained for a rigid and a flexible vessel.

  14. Flow across microvessel walls through the endothelial surface glycocalyx and the interendothelial cleft

    NASA Astrophysics Data System (ADS)

    Sugihara-Seki, M.; Akinaga, T.; Itano, T.

    A mathematical model is presented for steady fluid flow across microvessel walls through a serial pathway consisting of the endothelial surface glycocalyx and the intercellular cleft between adjacent endothelial cells, with junction strands and their discontinuous gaps. The three-dimensional flow through the pathway from the vessel lumen to the tissue space has been computed numerically based on a Brinkman equation with appropriate values of the Darcy permeability. The predicted values of the hydraulic conductivity Lp, defined as the ratio of the flow rate per unit surface area of the vessel wall to the pressure drop across it, are close to experimental measurements for rat mesentery microvessels. If the values of the Darcy permeability for the surface glycocalyx are determined based on the regular arrangements of fibres with 6 nm radius and 8 nm spacing proposed recently from the detailed structural measurements, then the present study suggests that the surface glycocalyx could be much less resistant to flow compared to previous estimates by the one-dimensional flow analyses, and the intercellular cleft could be a major determinant of the hydraulic conductivity of the microvessel wall.

  15. Effect of the initial density and angular-velocity profiles of pre-stellar cores on the properties of young stellar objects

    NASA Astrophysics Data System (ADS)

    Vorobyov, Eduard I.

    2012-03-01

    The physical properties of young stellar objects are studied as functions of the initial spatial distributions of the gas surface density Σ and angular velocity Ω in pre-stellar cores using numerical hydrodynamic simulations. Two limiting cases are considered: spatially homogeneous cores with Σ = const and Ω = const and centrally concentrated cores with radius-dependent densities Σ ∝ r -1 and Ω ∝ r -1. The degree of gravitational instability and protostellar disk fragmentation is mostly determined by the initial core mass and the ratio of the rotational to the gravitational energy, and depends only weakly on the initial spatial configuration of pre-stellar cores, except for the earliest stages of evolution, when models with spatially homogeneous cores can be more gravitationally unstable. The accretion of disk matter onto a protostar also depends weakly on the initial distributions of Σ and Ω, with matter from the collapsing core falling onto the disk at a rate that is slightly higher in models with spatially homogeneous cores. An appreciable dependence of the disk mass, disk radius, and the disk-to-protostar mass ratio on the initial density and angular velocity profiles of the parent core is found only for class 0 young objects; this relationship is not systematic in the later I and II stages of stellar evolution. The mass of the central protostar depends weakly on the initial core configuration in all three evolutionary stages.

  16. Thrombin mitogenic responses and protein phosphorylation are different in cultured human endothelial cells derived from large and microvessels

    SciTech Connect

    Dupuy, E.; Bikfalvi, A.; Rendu, F.; Toledano, S.L.; Tobelem, G. )

    1989-12-01

    It is well established that thrombin induces various biological responses in endothelial cells derived from large vessels. However, little is known about the effects of thrombin on the microvasculature. Protein phosphorylation may be one of the mechanisms by which an extracellular stimulus initiates cellular events like proliferation. Therefore, we have compared the effects of either human alpha-thrombin or phorbol esters (TPA) on the proliferation or protein phosphorylation in endothelial cells derived from large vessels (umbilical vein, HUVEC) or microvessels (omental tissue, HOMEC). In HOMEC, thrombin did not stimulate cell proliferation and protein phosphorylation while TPA slightly reduced the cell proliferation and induced the phosphorylation of a 27-kDa protein. In contrast, in HUVEC, thrombin or TPA markedly enhanced the cell proliferation and stimulated the phosphorylation of a 59-kDa protein. These data indicate that endothelial cells from large and small vessels respond differently to thrombin and there is a complex and as yet unclear relationship between the proliferation and the protein phosphorylation induced by thrombin.

  17. High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

    SciTech Connect

    Wolfe, Adam R.; Atkinson, Rachel L.; Reddy, Jay P.; Debeb, Bisrat G.; Larson, Richard; Li, Li; Masuda, Hiroko; Brewer, Takae; Atkinson, Bradley J.; Brewster, Abeena; Ueno, Naoto T.; Woodward, Wendy A.

    2015-04-01

    Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients

  18. Population age and initial density in a patchy environment affect the occurrence of abrupt transitions in a birth-and-death model of Taylor's law

    USGS Publications Warehouse

    Jiang, Jiang; DeAngelis, Donald L.; Zhang, B.; Cohen, J.E.

    2014-01-01

    Taylor's power law describes an empirical relationship between the mean and variance of population densities in field data, in which the variance varies as a power, b, of the mean. Most studies report values of b varying between 1 and 2. However, Cohen (2014a) showed recently that smooth changes in environmental conditions in a model can lead to an abrupt, infinite change in b. To understand what factors can influence the occurrence of an abrupt change in b, we used both mathematical analysis and Monte Carlo samples from a model in which populations of the same species settled on patches, and each population followed independently a stochastic linear birth-and-death process. We investigated how the power relationship responds to a smooth change of population growth rate, under different sampling strategies, initial population density, and population age. We showed analytically that, if the initial populations differ only in density, and samples are taken from all patches after the same time period following a major invasion event, Taylor's law holds with exponent b=1, regardless of the population growth rate. If samples are taken at different times from patches that have the same initial population densities, we calculate an abrupt shift of b, as predicted by Cohen (2014a). The loss of linearity between log variance and log mean is a leading indicator of the abrupt shift. If both initial population densities and population ages vary among patches, estimates of b lie between 1 and 2, as in most empirical studies. But the value of b declines to ~1 as the system approaches a critical point. Our results can inform empirical studies that might be designed to demonstrate an abrupt shift in Taylor's law.

  19. Photoacoustic simulation of microvessel bleeding: spectral analysis and its implication for monitoring vascular-targeted treatments

    NASA Astrophysics Data System (ADS)

    Fadhel, Muhannad N.; Hysi, Eno; Zalev, Jason; Kolios, Michael C.

    2016-03-01

    The destruction of blood vessels is a commonly used cancer therapeutic strategy. Bleeding consequently follows and leads to the accumulation of blood in the interstitium. Photoacoustic (PA) imaging is well positioned to detect bleeding due to its sensitivity to hemoglobin. After treatment vascular disruption can occur within just a few hours, which leads to bleeding which might be detected using PA to assess therapeutic effectiveness. Deep micro-vessels cannot typically be resolved using acoustic-resolution PA. However, spectral analysis of PA signals may still permit assessment of bleeding. This paper introduces a theoretical model to simulate the PA signals from disrupted vessels using a fractal model. The fractal model uses bifurcated-cylinder bases to represent vascular trees. Vessels have circular absorption cross-sections. To mimic bleeding from blood vessels, the diffusion of hemoglobin from micro-vessels was simulated. The PA signals were computed and in the simulations were detected using a linear array transducer (30 MHz center frequency) for four different vascular trees (at 256 axial spatial locations/tree). The Fourier Transform of each beam-formed PA signal was computed and the power spectra were fitted to a straight line within the -6 dB bandwidth of the receiving transducer. When comparing the power spectra before and after simulated bleeding, the spectral slope and mid-band fit (MBF) parameters decreased by 0.12 dB/MHz and 2.12 dB, while the y-intercept did not change after 1 hour of simulated bleeding. The results suggest that spectral PA analysis is sensitive to changes in the concentration and spatial distribution of hemoglobin in tissue, and changes due to bleeding can be detected without the need to resolve individual vessels. The simulations support the applicability of PA imaging in cancer treatment monitoring by detecting micro-vessel disruption.

  20. Optical monitoring of oxygen tension in cortical microvessels with confocal microscopy

    PubMed Central

    Yaseen, Mohammad A.; Srinivasan, Vivek J.; Sakadžić, Sava; Wu, Weicheng; Ruvinskaya, Svetlana; Vinogradov, Sergei A.; Boas, DavidA

    2010-01-01

    Evaluating cerebral oxygenation is of critical importance for the understanding of brain function and several neuropathologies. Although several techniques exist for measuring cerebral oxygenation in vivo, the most widely accepted techniques offer limited spatial resolution. We have developed a confocal imaging system for minimally invasive measurement of oxygen tension (pO2) in cerebral microvessels with high spatial and temporal resolution. The system relies on the phosphorescence quenching method using exogenous porphyrin-based dendritic oxygen probes. Here we present high-resolution phosphorescence images of cortical microvasculature and temporal pO2 profiles from multiple locations in response to varied fraction of inspired oxygen and functional activation. PMID:20052157

  1. Characterization of atrial natriuretic peptide receptors in brain microvessel endothelial cells

    NASA Technical Reports Server (NTRS)

    Whitson, Peggy A.; Huls, M. H.; Sams, Clarence F.

    1989-01-01

    In view of the suggestions by Chabrier et al. (1987) and Steardo and Nathanson (1987) that atrial natriuretic peptide (ANP) may play a role in the fluid homeostasis of the brain, the ANP receptors in primary cultures of bovine brain microvessel endothelian cells were quantitated and characterized. Results of partition binding studies and the effect of cGMP additions indicated the presence of at least two types of ANP receptors, with the majority of the receptors being the nonguanylate cyclase coupled receptors. The presence of at least two ANP receptor types suggests an active role for ANP in regulating brain endothelial cell function.

  2. Modeling and Validation of the Thermal Response of TDI Encapsulating Foam as a function of Initial Density

    SciTech Connect

    Dodd, Amanda B.; Larsen, Marvin E.

    2014-09-01

    TDI foams of nominal density from 10 to 45 pound per cubic foot were decomposed within a heated stainless steel container. The pressure in the container and temperatures measured by thermocouples were recorded with each test proceeding to an allowed maximum pressure before venting. Two replicate tests for each of four densities and two orientations in gravity produced very consistent pressure histories. Some thermal responses demonstrate random sudden temperature increases due to decomposition product movement. The pressurization of the container due to the generation of gaseous products is more rapid for denser foams. When heating in the inverted orientation, where gravity is in the opposite direction of the applied heat flux, the liquefied decomposition products move towards the heated plate and the pressure rises more rapidly than in the upright configuration. This effect is present at all the densities tested but becomes more pronounced as density of the foam is decreased. A thermochemical material model implemented in a transient conduction model solved with the finite element method was compared to the test data. The expected uncertainty of the model was estimated using the mean value method and importance factors for the uncertain parameters were estimated. The model that was assessed does not consider the effect of liquefaction or movement of gases. The result of the comparison is that the model uncertainty estimates do not account for the variation in orientation (no gravitational affects are in the model) and therefore the pressure predictions are not distinguishable due to orientation. Temperature predictions were generally in good agreement with the experimental data. Predictions for response locations on the outside of the can benefit from reliable estimates associated with conduction in the metal. For the lighter foams, temperatures measured on the embedded component fall well with the estimated uncertainty intervals indicating the energy transport

  3. Direct phase selection of initial phases from single-wavelength anomalous dispersion (SAD) for the improvement of electron density and ab initio structure determination

    SciTech Connect

    Chen, Chung-De; Huang, Yen-Chieh; Chiang, Hsin-Lin; Hsieh, Yin-Cheng; Guan, Hong-Hsiang; Chuankhayan, Phimonphan; Chen, Chun-Jung

    2014-09-01

    A novel direct phase-selection method to select optimized phases from the ambiguous phases of a subset of reflections to replace the corresponding initial SAD phases has been developed. With the improved phases, the completeness of built residues of protein molecules is enhanced for efficient structure determination. Optimization of the initial phasing has been a decisive factor in the success of the subsequent electron-density modification, model building and structure determination of biological macromolecules using the single-wavelength anomalous dispersion (SAD) method. Two possible phase solutions (ϕ{sub 1} and ϕ{sub 2}) generated from two symmetric phase triangles in the Harker construction for the SAD method cause the well known phase ambiguity. A novel direct phase-selection method utilizing the θ{sub DS} list as a criterion to select optimized phases ϕ{sub am} from ϕ{sub 1} or ϕ{sub 2} of a subset of reflections with a high percentage of correct phases to replace the corresponding initial SAD phases ϕ{sub SAD} has been developed. Based on this work, reflections with an angle θ{sub DS} in the range 35–145° are selected for an optimized improvement, where θ{sub DS} is the angle between the initial phase ϕ{sub SAD} and a preliminary density-modification (DM) phase ϕ{sub DM}{sup NHL}. The results show that utilizing the additional direct phase-selection step prior to simple solvent flattening without phase combination using existing DM programs, such as RESOLVE or DM from CCP4, significantly improves the final phases in terms of increased correlation coefficients of electron-density maps and diminished mean phase errors. With the improved phases and density maps from the direct phase-selection method, the completeness of residues of protein molecules built with main chains and side chains is enhanced for efficient structure determination.

  4. Ultraviolet/Ozone as a Tool To Control Grafting Density in Surface-Initiated Controlled-Radical Polymerizations via Ablation of Bromine.

    PubMed

    Sheridan, Richard J; Orski, Sara V; Muramoto, Shin; Stafford, Christopher M; Beers, Kathryn L

    2016-08-16

    We used an ultraviolet-ozone (UVO) cleaner to create substrates for atom-transfer radical polymerization (ATRP) with varying surface initiator coverage. We collected complementary time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) measurements to investigate the precise chemical origin of the variation in grafting density. At short exposure times, the atomic composition underwent minor changes except for the relative amount of bromine. At longer UVO exposure times, there is clear evidence of exposure-dependent surface initiator oxidation. We interpret these data as evidence of a bromine ablation process within the UVO cleaner, with additional oxidative modification of the rest of the surface. We then used these substrates to create a series of poly(methyl methacrylate) (PMMA) brushes varying in grafting density, demonstrating the utility of this tool for the control of polymer brush density. The measured brush grafting densities were correlated with the bromine concentration measured by both ToF-SIMS and XPS. XPS and brush thicknesses correlated strongly, following an exponential decay with a half-life of 18 ± 1 s. PMID:27442615

  5. Ultraviolet/Ozone as a Tool To Control Grafting Density in Surface-Initiated Controlled-Radical Polymerizations via Ablation of Bromine.

    PubMed

    Sheridan, Richard J; Orski, Sara V; Muramoto, Shin; Stafford, Christopher M; Beers, Kathryn L

    2016-08-16

    We used an ultraviolet-ozone (UVO) cleaner to create substrates for atom-transfer radical polymerization (ATRP) with varying surface initiator coverage. We collected complementary time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) measurements to investigate the precise chemical origin of the variation in grafting density. At short exposure times, the atomic composition underwent minor changes except for the relative amount of bromine. At longer UVO exposure times, there is clear evidence of exposure-dependent surface initiator oxidation. We interpret these data as evidence of a bromine ablation process within the UVO cleaner, with additional oxidative modification of the rest of the surface. We then used these substrates to create a series of poly(methyl methacrylate) (PMMA) brushes varying in grafting density, demonstrating the utility of this tool for the control of polymer brush density. The measured brush grafting densities were correlated with the bromine concentration measured by both ToF-SIMS and XPS. XPS and brush thicknesses correlated strongly, following an exponential decay with a half-life of 18 ± 1 s.

  6. Magnetic targeting in the impermeable microvessel with two-phase fluid model--non-Newtonian characteristics of blood.

    PubMed

    Shaw, Sachin; Murthy, P V S N

    2010-09-01

    The present investigation deals with finding the trajectories of the drug dosed magnetic carrier particle in a microvessel with two-phase fluid model which is subjected to the external magnetic field. The radius of the microvessel is divided into the endothelial glycocalyx layer in which the blood is assumed to obey Newtonian character and a core and plug regions where the blood obeys the non-Newtonian Herschel-Bulkley character which is suitable for the microvessel of radius 50 microm. The carrier particles, bound with nanoparticles and drug molecules are injected into the vascular system upstream from malignant tissue, and captured at the tumor site using a local applied magnetic field. The applied magnetic field is produced by a cylindrical magnet positioned outside the body and near the tumor position. The expressions for the fluidic force for the carrier particle traversing in the two-phase fluid in the microvessel and the magnetic force due to the external magnetic field are obtained. Several factors that influence the magnetic targeting of the carrier particles in the microvasculature, such as the size of the carrier particle, the volume fraction of embedded magnetic nanoparticles, and the distance of separation of the magnet from the axis of the microvessel are considered in the present problem. An algorithm is given to solve the system of coupled equations for trajectories of the carrier particle in the invasive case. The trajectories of the carrier particle are found for both invasive and noninvasive targeting systems. A comparison is made between the trajectories in these cases. Also, the present results are compared with the data available for the impermeable microvessel with single-phase fluid flow. Also, a prediction of the capture of therapeutic magnetic nanoparticle in the impermeable microvasculature is made for different radii, distances and volume fractions in both the invasive and noninvasive cases. PMID:20478317

  7. Development and Characterization of In Vitro Microvessel Network and Quantitative Measurements of Endothelial [Ca2+]i and Nitric Oxide Production.

    PubMed

    Xu, Sulei; Li, Xiang; Liu, Yuxin; He, Pingnian

    2016-01-01

    Endothelial cells (ECs) lining the blood vessel walls in vivo are constantly exposed to flow, but cultured ECs are often grown under static conditions and exhibit a pro-inflammatory phenotype. Although the development of microfluidic devices has been embraced by engineers over two decades, their biological applications remain limited. A more physiologically relevant in vitro microvessel model validated by biological applications is important to advance the field and bridge the gaps between in vivo and in vitro studies. Here, we present detailed procedures for the development of cultured microvessel network using a microfluidic device with a long-term perfusion capability. We also demonstrate its applications for quantitative measurements of agonist-induced changes in EC [Ca(2+)]i and nitric oxide (NO) production in real time using confocal and conventional fluorescence microscopy. The formed microvessel network with continuous perfusion showed well-developed junctions between ECs. VE-cadherin distribution was closer to that observed in intact microvessels than statically cultured EC monolayers. ATP-induced transient increases in EC [Ca(2+)]i and NO production were quantitatively measured at individual cell levels, which validated the functionality of the cultured microvessels. This microfluidic device allows ECs to grow under a well-controlled, physiologically relevant flow, which makes the cell culture environment closer to in vivo than that in the conventional, static 2D cultures. The microchannel network design is highly versatile, and the fabrication process is simple and repeatable. The device can be easily integrated to the confocal or conventional microscopic system enabling high resolution imaging. Most importantly, because the cultured microvessel network can be formed by primary human ECs, this approach will serve as a useful tool to investigate how pathologically altered blood components from patient samples affect human ECs and provide insight into

  8. Ontogeny of ABC and SLC transporters in the microvessels of developing rat brain.

    PubMed

    Soares, Ricardo V; Do, Tuan M; Mabondzo, Aloïse; Pons, Gérard; Chhun, Stéphanie

    2016-04-01

    The blood-brain barrier (BBB) is responsible for the control of solutes' concentration in the brain. Tight junctions and multiple ATP-binding cassette (ABC) and SoLute Carrier (SLC) efflux transporters protect brain cells from xenobiotics, therefore reducing brain exposure to intentionally administered drugs. In epilepsy, polymorphisms and overexpression of efflux transporters genes could be associated with pharmacoresistance. The ontogeny of these efflux transporters should also be addressed because their expression during development may be related to different brain exposure to antiepileptic drugs in the immature brain. We detected statistically significant higher expression of Abcb1b and Slc16a1 genes, and lower expression of Abcb1a and Abcg2 genes between the post-natal day 14 (P14) and the adult rat microvessels. P-gP efflux activity was also shown to be lower in P14 rats when compared with the adults. The P-gP proteins coded by rodent genes Abcb1a and Abcb1b are known to have different substrate affinities. The role of the Abcg2 gene is less clear in pharmacoresistance in epilepsy, nonetheless the coded protein Bcrp is frequently associated with drug resistance. Finally, we observed a higher expression of the Mct1 transporter gene in the P14 rat brain microvessels. Accordingly to our results, we suppose that age may be another factor influencing brain exposure to antiepileptics as a consequence of different expression patterns of efflux transporters between the adult and immature BBB.

  9. A standalone perfusion platform for drug testing and target validation in micro-vessel networks.

    PubMed

    Zhang, Boyang; Peticone, Carlotta; Murthy, Shashi K; Radisic, Milica

    2013-01-01

    Studying the effects of pharmacological agents on human endothelium includes the routine use of cell monolayers cultivated in multi-well plates. This configuration fails to recapitulate the complex architecture of vascular networks in vivo and does not capture the relationship between shear stress (i.e. flow) experienced by the cells and dose of the applied pharmacological agents. Microfluidic platforms have been applied extensively to create vascular systems in vitro; however, they rely on bulky external hardware to operate, which hinders the wide application of microfluidic chips by non-microfluidic experts. Here, we have developed a standalone perfusion platform where multiple devices were perfused at a time with a single miniaturized peristaltic pump. Using the platform, multiple micro-vessel networks, that contained three levels of branching structures, were created by culturing endothelial cells within circular micro-channel networks mimicking the geometrical configuration of natural blood vessels. To demonstrate the feasibility of our platform for drug testing and validation assays, a drug induced nitric oxide assay was performed on the engineered micro-vessel network using a panel of vaso-active drugs (acetylcholine, phenylephrine, atorvastatin, and sildenafil), showing both flow and drug dose dependent responses. The interactive effects between flow and drug dose for sildenafil could not be captured by a simple straight rectangular channel coated with endothelial cells, but it was captured in a more physiological branching circular network. A monocyte adhesion assay was also demonstrated with and without stimulation by an inflammatory cytokine, tumor necrosis factor-α.

  10. Sphingosine-1-phosphate Maintains Normal Vascular Permeability by Preserving Endothelial Surface Glycocalyx in Intact Microvessels

    PubMed Central

    Zhang, Lin; Zeng, Min; Fan, Jie; Tarbell, John, M.; Curry, Fitz-Roy E.; Fu, Bingmei M.

    2016-01-01

    Objective Sphingosine-1-phosphate (S1P) was found to protect the endothelial surface glycocalyx (ESG) by inhibiting matrix metalloproteinase (MMP) activity-dependent shedding of ESG in cultured endothelial cell studies. We aimed to further test that S1P contributes to the maintenance of normal vascular permeability by protecting the ESG in intact microvessels. Methods We quantified the ESG in post-capillary venules of rat mesentery and measured the vascular permeability to albumin in the presence and absence of 1 μM S1P. We also measured permeability to albumin in the presence of MMP inhibitors and compared the measured permeability with those predicted by a transport model for the inter-endothelial cleft. Results We found that in the absence of S1P, the fluorescence intensity of the FITC-anti-heparan sulfate labeled ESG was ~10% of that in the presence of S1P, while the measured permeability to albumin was ~6.5 fold that in the presence of S1P. Similar results were observed with MMP inhibition. The predictions by the mathematical model further confirmed that S1P maintains microvascular permeability by preserving ESG. Conclusions Our results show that S1P contributes to the maintenance of normal vascular permeability by protecting the ESG in intact microvessels, consistent with parallel observation in cultured endothelial monolayers. PMID:27015105

  11. Modifying mixing and instability growth through the adjustment of initial conditions in a high-energy-density counter-propagating shear experiment on OMEGA

    SciTech Connect

    Merritt, E. C. Doss, F. W.; Loomis, E. N.; Flippo, K. A.; Kline, J. L.

    2015-06-15

    Counter-propagating shear experiments conducted at the OMEGA Laser Facility have been evaluating the effect of target initial conditions, specifically the characteristics of a tracer foil located at the shear boundary, on Kelvin-Helmholtz instability evolution and experiment transition toward nonlinearity and turbulence in the high-energy-density (HED) regime. Experiments are focused on both identifying and uncoupling the dependence of the model initial turbulent length scale in variable-density turbulence models of k-ϵ type on competing physical instability seed lengths as well as developing a path toward fully developed turbulent HED experiments. We present results from a series of experiments controllably and independently varying two initial types of scale lengths in the experiment: the thickness and surface roughness (surface perturbation scale spectrum) of a tracer layer at the shear interface. We show that decreasing the layer thickness and increasing the surface roughness both have the ability to increase the relative mixing in the system, and thus theoretically decrease the time required to begin transitioning to turbulence in the system. We also show that we can connect a change in observed mix width growth due to increased foil surface roughness to an analytically predicted change in model initial turbulent scale lengths.

  12. Modifying mixing and instability growth through the adjustment of initial conditions in a high-energy-density counter-propagating shear experiment on OMEGA

    SciTech Connect

    Merritt, E. C.; Doss, F. W.; Loomis, E. N.; Flippo, K. A.; Kline, J. L.

    2015-06-24

    Counter-propagating shear experiments conducted at the OMEGA Laser Facility have been evaluating the effect of target initial conditions, specifically the characteristics of a tracer foil located at the shear boundary, on Kelvin-Helmholtz instability evolution and experiment transition toward nonlinearity and turbulence in the high-energy-density (HED) regime. Experiments are focused on both identifying and uncoupling the dependence of the model initial turbulent length scale in variable-density turbulence models of k-ϵ type on competing physical instability seed lengths as well as developing a path toward fully developed turbulent HED experiments. We present results from a series of experiments controllably and independently varying two initial types of scale lengths in the experiment: the thickness and surface roughness (surface perturbation scale spectrum) of a tracer layer at the shear interface. We show that decreasing the layer thickness and increasing the surface roughness both have the ability to increase the relative mixing in the system, and thus theoretically decrease the time required to begin transitioning to turbulence in the system. In addition, we also show that we can connect a change in observed mix width growth due to increased foil surface roughness to an analytically predicted change in model initial turbulent scale lengths.

  13. Modifying mixing and instability growth through the adjustment of initial conditions in a high-energy-density counter-propagating shear experiment on OMEGA

    DOE PAGES

    Merritt, E. C.; Doss, F. W.; Loomis, E. N.; Flippo, K. A.; Kline, J. L.

    2015-06-24

    Counter-propagating shear experiments conducted at the OMEGA Laser Facility have been evaluating the effect of target initial conditions, specifically the characteristics of a tracer foil located at the shear boundary, on Kelvin-Helmholtz instability evolution and experiment transition toward nonlinearity and turbulence in the high-energy-density (HED) regime. Experiments are focused on both identifying and uncoupling the dependence of the model initial turbulent length scale in variable-density turbulence models of k-ϵ type on competing physical instability seed lengths as well as developing a path toward fully developed turbulent HED experiments. We present results from a series of experiments controllably and independently varyingmore » two initial types of scale lengths in the experiment: the thickness and surface roughness (surface perturbation scale spectrum) of a tracer layer at the shear interface. We show that decreasing the layer thickness and increasing the surface roughness both have the ability to increase the relative mixing in the system, and thus theoretically decrease the time required to begin transitioning to turbulence in the system. In addition, we also show that we can connect a change in observed mix width growth due to increased foil surface roughness to an analytically predicted change in model initial turbulent scale lengths.« less

  14. Transfection of the Human Heme Oxygenase Gene Into Rabbit Coronary Microvessel Endothelial Cells: Protective Effect Against Heme and Hemoglobin Toxicity

    NASA Astrophysics Data System (ADS)

    Abraham, N. G.; Lavrovsky, Y.; Schwartzman, M. L.; Stoltz, R. A.; Levere, R. D.; Gerritsen, M. E.

    1995-07-01

    Heme oxygenase (HO) is a stress protein and has been suggested to participate in defense mechanisms against agents that may induce oxidative injury such as metals, endotoxin, heme/hemoglobin, and various cytokines. Overexpression of HO in cells might therefore protect against oxidative stress produced by certain of these agents, specifically heme and hemoglobin, by catalyzing their degradation to bilirubin, which itself has antioxidant properties. We report here the successful in vitro transfection of rabbit coronary microvessel endothelial cells with a functioning gene encoding the human HO enzyme. A plasmid containing the cytomegalovirus promoter and the human HO cDNA complexed to cationic liposomes (Lipofectin) was used to transfect rabbit endothelial cells. Cells transfected with human HO exhibited an ≈3.0-fold increase in enzyme activity and expressed a severalfold induction of human HO mRNA as compared with endogenous rabbit HO mRNA. Transfected and nontransfected cells expressed factor VIII antigen and exhibited similar acetylated low-density lipoprotein uptake (two important features that characterize endothelial cells) with >85% of cells staining positive for each marker. Moreover, cells transfected with the human HO gene acquired substantial resistance to toxicity produced by exposure to recombinant hemoglobin and heme as compared with nontransfected cells. The protective effect of HO overexpression against heme/hemoglobin toxicity in endothelial cells shown in these studies provides direct evidence that the inductive response of human HO to such injurious stimuli represents an important tissue adaptive mechanism for moderating the severity of cell damage produced by these blood components.

  15. Direct phase selection of initial phases from single-wavelength anomalous dispersion (SAD) for the improvement of electron density and ab initio structure determination

    PubMed Central

    Chen, Chung-De; Huang, Yen-Chieh; Chiang, Hsin-Lin; Hsieh, Yin-Cheng; Guan, Hong-Hsiang; Chuankhayan, Phimonphan; Chen, Chun-Jung

    2014-01-01

    Optimization of the initial phasing has been a decisive factor in the success of the subsequent electron-density modification, model building and structure determination of biological macromolecules using the single-wavelength anomalous dispersion (SAD) method. Two possible phase solutions (ϕ1 and ϕ2) generated from two symmetric phase triangles in the Harker construction for the SAD method cause the well known phase ambiguity. A novel direct phase-selection method utilizing the θDS list as a criterion to select optimized phases ϕam from ϕ1 or ϕ2 of a subset of reflections with a high percentage of correct phases to replace the corresponding initial SAD phases ϕSAD has been developed. Based on this work, reflections with an angle θDS in the range 35–145° are selected for an optimized improvement, where θDS is the angle between the initial phase ϕSAD and a preliminary density-modification (DM) phase ϕDM NHL. The results show that utilizing the additional direct phase-selection step prior to simple solvent flattening without phase combination using existing DM programs, such as RESOLVE or DM from CCP4, significantly improves the final phases in terms of increased correlation coefficients of electron-density maps and diminished mean phase errors. With the improved phases and density maps from the direct phase-selection method, the completeness of residues of protein molecules built with main chains and side chains is enhanced for efficient structure determination. PMID:25195747

  16. Direct phase selection of initial phases from single-wavelength anomalous dispersion (SAD) for the improvement of electron density and ab initio structure determination.

    PubMed

    Chen, Chung-De; Huang, Yen-Chieh; Chiang, Hsin-Lin; Hsieh, Yin-Cheng; Guan, Hong-Hsiang; Chuankhayan, Phimonphan; Chen, Chun-Jung

    2014-09-01

    Optimization of the initial phasing has been a decisive factor in the success of the subsequent electron-density modification, model building and structure determination of biological macromolecules using the single-wavelength anomalous dispersion (SAD) method. Two possible phase solutions (φ1 and φ2) generated from two symmetric phase triangles in the Harker construction for the SAD method cause the well known phase ambiguity. A novel direct phase-selection method utilizing the θ(DS) list as a criterion to select optimized phases φ(am) from φ1 or φ2 of a subset of reflections with a high percentage of correct phases to replace the corresponding initial SAD phases φ(SAD) has been developed. Based on this work, reflections with an angle θ(DS) in the range 35-145° are selected for an optimized improvement, where θ(DS) is the angle between the initial phase φ(SAD) and a preliminary density-modification (DM) phase φ(DM)(NHL). The results show that utilizing the additional direct phase-selection step prior to simple solvent flattening without phase combination using existing DM programs, such as RESOLVE or DM from CCP4, significantly improves the final phases in terms of increased correlation coefficients of electron-density maps and diminished mean phase errors. With the improved phases and density maps from the direct phase-selection method, the completeness of residues of protein molecules built with main chains and side chains is enhanced for efficient structure determination.

  17. Modeling, design and validation of a novel microfluidic sensor for in-vitro isotonic measurement of microvessel contraction/dilation.

    PubMed

    Izzo, Ivano; Dario, Paolo

    2007-02-01

    The paper presents an innovative fluidic microdevice for in-vitro isotonic measurements of microvessel contraction/dilation. The proposed microdevice is based on the well-known fluid dynamic principle which correlates a geometrical change of a solid body immersed in a constant flow, with the differential pressure change induced in the flow itself. Indeed, a biochemically-induced change of microvessel diameter lead to a change of its hydraulic resistance which can be in-vitro measured by a differential pressure sensor. The novel microfluidic sensor has been modeled, designed and fabricated in order to properly implement this working principle. The fluidic scheme of the sensor consists of two pressure-sensorized chambers which are connected by a calibrated channel where the microvessel is placed. Experimental tests have been performed by using three microvessel passive simulators with different inner diameter (300, 600 and 800 microm), in order to validate the expected sensor functioning characterized by two sensitivities: the pressure drop S (PL) and the overall S 2-3 ones. Their measured values (S (PL,m)=2.132 mV/V/Pa, S (2-3,m)=0.787 mV/V/(mm3/s)/mm) confirm the validity of the proposed working principle and permit to be confident in a future application of the sensor in a clinical context.

  18. LASER BIOLOGY AND MEDICINE: Recording of lymph flow dynamics in microvessels using correlation properties of scattered coherent radiation

    NASA Astrophysics Data System (ADS)

    Fedosov, I. V.; Tuchin, Valerii V.; Galanzha, E. I.; Solov'eva, A. V.; Stepanova, T. V.

    2002-11-01

    The direction-sensitive method of microflow velocity measurements based on the space — time correlation properties of the dynamic speckle field is described and used for in vivo monitoring of lymph flow in the vessels of rat mesentery. The results of measurements are compared with the data obtained from functional video microscopy of the microvessel region.

  19. Phenomenon of formation of an acoustic field in the lumens of microvessels of the blood circulation system

    NASA Astrophysics Data System (ADS)

    Bagayev, Sergey N.; Zakharov, Vladimir N.; Orlov, Valery A.; Obraztsov, Yury D.; Panov, Sergey V.; Fomin, Yury N.

    2003-09-01

    In this paper, experimental results of investigations of the physical mechanism of transcapillary exchange by the method of phase sensitive laser spectroscopy of light scattering are presented. Acoustic oscillations of the walls of microvessels (arterioles, capillaries, and venules) which provide transcapillary exchange have been detected for the first time.

  20. Ontogeny of four blood-brain barrier markers: an immunocytochemical comparison of pial and cerebral cortical microvessels.

    PubMed Central

    Cassella, J P; Lawrenson, J G; Allt, G; Firth, J A

    1996-01-01

    Pial and cortical microvessels possess many blood-brain barrier (BBB) properties in common, including impermeability to electron dense tracers, high transendothelial electrical resistance and specialised endothelial cell ultrastructural features. To compare pial and cortical microvessels further, a developmental, immunocytochemical study was undertaken of 4 BBB markers in the rat: OX-47, EBA, GLUT-1 and s-laminin. The appearance of the markers was monitored from embryonic d 16, to postnatal and adult stages. Each of the 4 markers appeared simultaneously in both pial and cortical vessels. GLUT-1 and OX-47 were present in endothelial cells of the BBB from E 16 to the adult. EBA and s-laminin appeared from postnatal d 7 through to the adult. Pial microvessels lack the ensheathment of astrocytes which may be involved in the induction and/or maintenance of BBB markers in the cortex. It is possible that astrocyte-derived factors diffusing from the brain surface are responsible for induction of BBB properties in the pial microvessels. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 PMID:8886962

  1. Power densities and microbial communities of brewery wastewater-fed microbial fuel cells according to the initial substrates.

    PubMed

    Yu, Jaecheul; Park, Younghyun; Kim, Byunggoon; Lee, Taeho

    2015-01-01

    Single-chamber microbial fuel cells (MFCs) acclimated with glucose, butyrate, propionate, acetate, and a mixture of the four were operated with brewery wastewater (BWW) under a fed-batch mode. Glucose-fed MFC (GW-MFC) showed the highest maximum power density (PDmax) of 1,519 mW/m(2), followed in order by acetate-fed MFC (AW-MFC), mixed substrates-fed MFC (MW-MFC), butyrate-fed MFC (BW-MFC), and propionate-fed MFC (PW-MFC). After changing to BWW, power production was decreased for all MFCs. MFC acclimated with glucose showed the highest PDmax of 890 ± 12 mW/m(2), followed in order by MW-MFC, AW-MFC, BW-MFC, and PW-MFC. The PDmax in BWW-MFC, which was acclimated and operated with BWW, of 552 mW/m(2) was less than that of GW-MFC and MW-MFC but more than that of AW-MFC, BW-MFC, and PW-MFC. MFCs with fermentable substrates were less affected by the BWW. Gammaproteobacteria, including Pseudomonas sp., Acinetobacter sp. and Xanthomonas axonopodis, were found in all MFCs with pure substrates and Rubrivivax benzoatilyticus, thiobacillus sp. and Denitratisoma oestradiolicum belonging to Betaproteobacteria were newly detected in all MFCs when the substrate was changed to BWW.

  2. Power densities and microbial communities of brewery wastewater-fed microbial fuel cells according to the initial substrates.

    PubMed

    Yu, Jaecheul; Park, Younghyun; Kim, Byunggoon; Lee, Taeho

    2015-01-01

    Single-chamber microbial fuel cells (MFCs) acclimated with glucose, butyrate, propionate, acetate, and a mixture of the four were operated with brewery wastewater (BWW) under a fed-batch mode. Glucose-fed MFC (GW-MFC) showed the highest maximum power density (PDmax) of 1,519 mW/m(2), followed in order by acetate-fed MFC (AW-MFC), mixed substrates-fed MFC (MW-MFC), butyrate-fed MFC (BW-MFC), and propionate-fed MFC (PW-MFC). After changing to BWW, power production was decreased for all MFCs. MFC acclimated with glucose showed the highest PDmax of 890 ± 12 mW/m(2), followed in order by MW-MFC, AW-MFC, BW-MFC, and PW-MFC. The PDmax in BWW-MFC, which was acclimated and operated with BWW, of 552 mW/m(2) was less than that of GW-MFC and MW-MFC but more than that of AW-MFC, BW-MFC, and PW-MFC. MFCs with fermentable substrates were less affected by the BWW. Gammaproteobacteria, including Pseudomonas sp., Acinetobacter sp. and Xanthomonas axonopodis, were found in all MFCs with pure substrates and Rubrivivax benzoatilyticus, thiobacillus sp. and Denitratisoma oestradiolicum belonging to Betaproteobacteria were newly detected in all MFCs when the substrate was changed to BWW. PMID:24973903

  3. High energy emission of GRB 130821A: Constraining the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow

    SciTech Connect

    Liang, Yun-Feng; Zhou, Bei; He, Hao-Ning; Fan, Yi-Zhong; Wei, Da-Ming; Tam, Pak-Hin Thomas

    2014-02-01

    GRB 130821A was detected by Fermi-GBM/LAT, Konus-WIND, SPI-ACS/INTEGRAL, RHESSI and Mars Odyssey-HEND. Although the data of GRB 130821A are very limited, we show in this work that the high energy γ-ray emission (i.e., above 100 MeV) alone imposes tight constraint on the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow. The temporal behavior of the high energy γ-ray emission is consistent with the forward shock synchrotron radiation model, and the circum-burst medium likely has a constant-density profile. The Lorentz factor is about a few hundred, similar to other bright GRBs.

  4. Quenched dynamics in interacting one-dimensional systems: Appearance of current-carrying steady states from initial domain wall density profiles

    NASA Astrophysics Data System (ADS)

    Lancaster, Jarrett; Gull, Emanuel; Mitra, Aditi

    2010-12-01

    We investigate dynamics arising after an interaction quench in the quantum sine-Gordon model for a one-dimensional system initially prepared in a spatially inhomogeneous domain wall state. We study the time evolution of the density, current, and equal time correlation functions using the truncated Wigner approximation to which quantum corrections are added in order to set the limits on its validity. For weak to moderate strengths of the backscattering interaction, the domain wall spreads out ballistically with the system within the light cone reaching a nonequilibrium steady state characterized by a net current flow. A steady-state current exists for a quench at the exactly solvable Luther-Emery point. The magnitude of the current decreases with increasing strength of the backscattering interaction. The two-point correlation function of the variable canonically conjugate to the density reaches a spatially oscillating steady state at a wavelength inversely related to the current.

  5. Effect of Initial Population Density of Criconemella xenoplax on Reducing Sugars, Free Amino Acids, and Survival of Peach Seedlings over Time.

    PubMed

    Nyczepir, A P; Reilly, C C; Okie, W R

    1987-07-01

    Percentage of mortality, growth suppression, and changes in free amino acid and reducing sugar content in root and (or) stem tissue of Nemaguard peach seedlings were studied in the greenhouse in relation to time and eight different initial population densities (Pi) of Criconemella xenoplax. After 90 and 180 days, free amino acid content in root tissue significantly increased with increasing nematode numbers. Suppression of root volume, dry root and stem weight, height increase, plant survival, and content of reducing sugars in root tissue were detected at 180 and 270 days and following pruning. All criteria were negatively correlated with nematode Pi. Changes in growth, metabolic parameters, and survival percentage were attributed to Pi density of C. xenoplax, duration of the experiment, and nematode reproduction rate.

  6. [The impact of periodontal disease treatment on endothelium of sublingual microvessels].

    PubMed

    Grudyanov, A I; Tkacheva, O N; Khatagov, A T; Mustafina, F N; Gorshkov, A Yu

    2016-01-01

    The intactness degree of glycocalyx and the thickness of endothelium layer in sublingual microvessels was determined by means of darkfield microscopy and GlycoCheck RI software in 35 patients (19 men and 16 women, aged 35 to 65 years) with chronic generalized severe periodontitis before and after anti-inflammatory and surgical treatment. The patients were divided into two groups. The first group recieved only local anti-inflammatory therapy while patients of group 2 underwent surgical intervention on the periodontium in addition to local anti-inflammatory therapy. In both groups the changes of parameters of endothelial glycocalyx (EGC) in the early stages of treatment were not significant. In long terms the changes were not revealed in group 1, but in group 2 6 months after surgical treatment in all patients the decrease in the thickness of the permeable glycocalyx decreased and increase of the volume of red blood cells filling was observed. PMID:27636753

  7. In-vivo visualization of melanoma tumor microvessels and blood flow velocity changes accompanying tumor growth

    NASA Astrophysics Data System (ADS)

    Ishida, Hiroki; Hachiga, Tadashi; Andoh, Tsugunobu; Akiguchi, Shunsuke

    2012-11-01

    We demonstrate that using micro multipoint laser Doppler velocimetry (μ-MLDV) for noninvasive in-vivo imaging of blood vessels is useful for diagnosing malignant melanomas by comparison with visual diagnosis by dermoscopy. The blood flow velocity in microvessels varied during growth of melanomas transplanted in mouse ears. Mouse ears were observed by μ-MLDV up to 16 days after transplantation. The blood flow velocity in the tumor increased with increasing time and reached maximum of 4.5 mm/s at 9 days, which is more than twice that prior to transplantation. After 12 days, when the lesion had grown to an area of 6.6 mm2, we observed the formation of new blood vessels in the tumor. Finally, when the lesion had an area of 18 mm2 after 16 days, the flow velocity in the tumor decreased to approximately 3.2 mm/s.

  8. [The impact of periodontal disease treatment on endothelium of sublingual microvessels].

    PubMed

    Grudyanov, A I; Tkacheva, O N; Khatagov, A T; Mustafina, F N; Gorshkov, A Yu

    2016-01-01

    The intactness degree of glycocalyx and the thickness of endothelium layer in sublingual microvessels was determined by means of darkfield microscopy and GlycoCheck RI software in 35 patients (19 men and 16 women, aged 35 to 65 years) with chronic generalized severe periodontitis before and after anti-inflammatory and surgical treatment. The patients were divided into two groups. The first group recieved only local anti-inflammatory therapy while patients of group 2 underwent surgical intervention on the periodontium in addition to local anti-inflammatory therapy. In both groups the changes of parameters of endothelial glycocalyx (EGC) in the early stages of treatment were not significant. In long terms the changes were not revealed in group 1, but in group 2 6 months after surgical treatment in all patients the decrease in the thickness of the permeable glycocalyx decreased and increase of the volume of red blood cells filling was observed.

  9. Bone Mineral Density Changes Among Women Initiating Proton Pump Inhibitors or H2 Receptor Antagonists: A SWAN Cohort Study

    PubMed Central

    Solomon, Daniel H; Diem, Susan J; Ruppert, Kristine; Juan Lian, Yin; Liu, Chih-Chin; Wohlfart, Alyssa; Greendale, Gail A; Finkelstein, Joel S

    2015-01-01

    Proton pump inhibitors (PPIs) have been associated with diminished bone mineral density (BMD) and an increased risk of fracture; however, prior studies have not yielded consistent results, and many have suboptimal ascertainment of both PPI use and BMD. We used data from the Study of Women’s Health Across the Nation (SWAN), a multicenter, multi-ethnic, community-based longitudinal cohort study of women across the menopause transition to examine the association between annualized BMD changes and new use of PPIs. We compared changes in BMD in new PPI users with changes in BMD in new users of histamine 2 receptor antagonists (H2RAs) and with changes in BMD in subjects who did not use either class of medications. Mixed linear regression models included recognized risk factors for osteoporosis, including demographics, menopausal transition stage, body mass index (BMI), lifestyle factors, as well as comorbidities and concomitant medications. To provide further evidence for the validity of our analytic approach, we also examined the effects of hormone-replacement therapy (HT), a class of medications that should reduce bone loss, on changes in BMD as an internal positive control group. We identified 207 new users of PPIs, 185 new users of H2RAs, and 1,676 non-users. Study subjects had a mean age of 50 years and were followed for a median of 9.9 years. Adjusted models found no difference in the annualized BMD change at the lumbar spine, femoral neck, or total hip in PPI users compared with H2RA users or non-users. These results were robust to sensitivity analyses. BMD increased as expected in HT users, supporting the validity of our study design. These longitudinal analyses plus similar prior studies argue against an association between PPI use and BMD loss. PMID:25156141

  10. Bone mineral density changes among women initiating proton pump inhibitors or H2 receptor antagonists: a SWAN cohort study.

    PubMed

    Solomon, Daniel H; Diem, Susan J; Ruppert, Kristine; Lian, Yin Juan; Liu, Chih-Chin; Wohlfart, Alyssa; Greendale, Gail A; Finkelstein, Joel S

    2015-02-01

    Proton pump inhibitors (PPIs) have been associated with diminished bone mineral density (BMD) and an increased risk of fracture; however, prior studies have not yielded consistent results, and many have suboptimal ascertainment of both PPI use and BMD. We used data from the Study of Women's Health Across the Nation (SWAN), a multicenter, multi-ethnic, community-based longitudinal cohort study of women across the menopause transition to examine the association between annualized BMD changes and new use of PPIs. We compared changes in BMD in new PPI users with changes in BMD in new users of histamine 2 receptor antagonists (H2RAs) and with changes in BMD in subjects who did not use either class of medications. Mixed linear regression models included recognized risk factors for osteoporosis, including demographics, menopausal transition stage, body mass index (BMI), lifestyle factors, as well as comorbidities and concomitant medications. To provide further evidence for the validity of our analytic approach, we also examined the effects of hormone-replacement therapy (HT), a class of medications that should reduce bone loss, on changes in BMD as an internal positive control group. We identified 207 new users of PPIs, 185 new users of H2RAs, and 1,676 non-users. Study subjects had a mean age of 50 years and were followed for a median of 9.9 years. Adjusted models found no difference in the annualized BMD change at the lumbar spine, femoral neck, or total hip in PPI users compared with H2RA users or non-users. These results were robust to sensitivity analyses. BMD increased as expected in HT users, supporting the validity of our study design. These longitudinal analyses plus similar prior studies argue against an association between PPI use and BMD loss. PMID:25156141

  11. Microvessel count predicts metastatic disease and survival in non-small cell lung cancer.

    PubMed

    Fontanini, G; Bigini, D; Vignati, S; Basolo, F; Mussi, A; Lucchi, M; Chine, S; Angeletti, C A; Harris, A L; Bevilacqua, G

    1995-09-01

    The growth of newly formed vessels, or neoangiogenesis, represents an important step in both physiological and pathological situations: in particular, tumour growth and metastasis require angiogenesis. Microvessel count (MC), which represents a measure of tumour angiogenesis, has been associated with metastatic spread in cutaneous, mammary, prostatic, head and neck, and early-stage lung cancer. In this study, the role of tumour angiogenesis as a prognostic indicator was examined in 253 primary non-small lung cancer (NSCLC) patients. Microvessels were counted by highlighting endothelial cells with anti-Factor VIII monoclonal antibody (Mab) in methacarn-fixed tumour samples. In univariat analysis, MC (P< 0.000001), sex (P=0.0036), histotype (P < 0.014), tumour status (P <0.007), and vessel invasion (P < 0.019) were significantly related to hilar and/or mediastinal nodal involvement. However, in the stepwise logistic regression analysis, MC (P<0.000003) retained the most important influence on nodal metastasis. The overall survival analysis calculated by the Kaplan-Meier method revealed that tumours with high MC ( > 25 vessels/field) were significantly associated with increased death risk (log-rank test P = 0.00067; Cox's test P = 0.00046; Gehan's Wilcoxon test P = 0.00108). In 94 patients, the development of metastatic disease during follow-up was significantly related to MC. Indeed, patients who developed metastasis during follow-up showed a higher MC, either as a dichotomous (P = 0.01) or as a continuous (P = 0.003) variable, than patients who had developed no metastasis at the time of the analysis. Moreover, in the stepwise logistic regression analysis, MC retained the most important influence on distant metastases.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Effects of initial-fixed charge density on pH-sensitive hydrogels subjected to coupled pH and electric field stimuli: a meshless analysis.

    PubMed

    Ng, T Y; Li, Hua; Yew, Y K; Lam, K Y

    2007-04-01

    In this paper, we study the effects of initial fixed-charge density on the response behavior of pH-sensitive hydrogels subjected to coupled stimuli, namely, solution pH and externally applied electric field. This is the first instance in which a coupled stimuli numerical analysis has been carried out for these polymer gels, which are used as active sensing/actuating elements in advanced biomicroelectromechanical systems devices. In this work, a chemo-electro-mechanical formulation, termed the multi-effect-coupling pH-stimulus (MECpH) model, is first presented. This mathematical model takes into account the ionic species diffusion, electric potential coupling, and large mechanical deformation. In addition, a correlation between the diffusive hydrogen ions and fixed-charge groups on the hydrogel polymeric chains is established based on the Langmuir absorption isotherm, and incorporated accordingly into the MECpH model. To solve the resulting highly nonlinear and highly coupled partial differential equations of this mathematical model, the Hermite-Cloud method, a novel true meshless technique, is employed. To demonstrate the accuracy and robustness the MECpH model, computed numerical results are compared with experimental data available from literature. Following this validation, several numerical studies are carried out to investigate the effects of initial fixed-charge density on the volumetric variations of these pH-stimulus-responsive hydrogels when immersed in buffered solutions.

  13. Elucid—exploring the local universe with the reconstructed initial density field. I. Hamiltonian Markov chain Monte Carlo method with particle mesh dynamics

    SciTech Connect

    Wang, Huiyuan; Mo, H. J.; Yang, Xiaohu; Lin, W. P.; Jing, Y. P.

    2014-10-10

    Simulating the evolution of the local universe is important for studying galaxies and the intergalactic medium in a way free of cosmic variance. Here we present a method to reconstruct the initial linear density field from an input nonlinear density field, employing the Hamiltonian Markov Chain Monte Carlo (HMC) algorithm combined with Particle-mesh (PM) dynamics. The HMC+PM method is applied to cosmological simulations, and the reconstructed linear density fields are then evolved to the present day with N-body simulations. These constrained simulations accurately reproduce both the amplitudes and phases of the input simulations at various z. Using a PM model with a grid cell size of 0.75 h {sup –1} Mpc and 40 time steps in the HMC can recover more than half of the phase information down to a scale k ∼ 0.85 h Mpc{sup –1} at high z and to k ∼ 3.4 h Mpc{sup –1} at z = 0, which represents a significant improvement over similar reconstruction models in the literature, and indicates that our model can reconstruct the formation histories of cosmic structures over a large dynamical range. Adopting PM models with higher spatial and temporal resolutions yields even better reconstructions, suggesting that our method is limited more by the availability of computer resource than by principle. Dynamic models of structure evolution adopted in many earlier investigations can induce non-Gaussianity in the reconstructed linear density field, which in turn can cause large systematic deviations in the predicted halo mass function. Such deviations are greatly reduced or absent in our reconstruction.

  14. Model-based Characterization of the Parameters of Dissimilatory Sulfate Reduction Under the Effect of Different Initial Density of Desulfovibrio piger Vib-7 Bacterial Cells.

    PubMed

    Kushkevych, Ivan; Bolis, Marco; Bartos, Milan

    2015-01-01

    The objective of this study was to design a model of dissimilatory sulfate reduction process using the Verhulst function, with a particular focus on the kinetics of bacterial growth, sulfate and lactate consumption, and accumulation of hydrogen sulfide and acetate. The effect of the initial density (0.12±0.011, 0.25±0.024, 0.5±0.048 and 1.0±0.096 mg cells/ml of medium) of the sulfate-reducing bacteria Desulfovibrio piger Vib-7 on the growth and dissimilatory sulfate reduction was studied. The exponential growth phase of the D. piger Vib-7 was observed for 72 hours of cultivation at the (0.12 and 0.25 mg/ml) initial concentration of bacterial cells. Sulfate and lactate were consumed incompletely during this time. The increase in the initial concentration of cells to 0.5 and 1 mg/ml led to a shortening of the exponential bacterial growth phase and a shift to the stationary phase of the growth. In the case of 0.5 mg/ml seeding, the stationary growth phase was observed in the 36(th) hour of cultivation. The increase in the initial concentration of cells to 1 mg/ml led to the beginning of the stationary growth phase in 24th hours of cultivation. Under these conditions, sulfate and lactate were consumed completely in the 48th hour of cultivation. The kinetic analysis of the curves of bacterial growth and the process of dissimilatory sulfate reduction by D. piger Vib-7 was carried out. PMID:26668663

  15. Microbubble oscillating in a microvessel filled with viscous fluid: A finite element modeling study.

    PubMed

    Chen, Chuyi; Gu, Yuyang; Tu, Juan; Guo, Xiasheng; Zhang, Dong

    2016-03-01

    Understanding the dynamics of coated-microbubble oscillating in an elastic microvessel is important for effective and safe applications of ultrasound contrast agents (UCAs) in imaging and therapy. Numerical simulations are performed based on a two-dimensional (2D) asymmetric finite element model to investigate the influences of both acoustic driving parameters (e.g., pressure and frequency) and material properties (vessel size, microbubble shell visco-elastic parameters and fluid viscosity) on the dynamic interactions in the bubble-blood-vessel system. The results show that, the constrained effect of the blood vessel along the radial direction will induce the asymmetric bubble oscillation and vessel deformation, as well as shifting the bubble resonance frequency toward the higher frequency range. For a bubble (1.5-μm radius) activated by 1-MHz ultrasound pulses in a microvessel with a radius varying between 2 and 6.5 μm, up to 26.95 kPa shear stress could be generated on the vessel wall at a driving pressure of 0.2 MPa, which should be high enough to damage the vascular endothelial cells. The asymmetrical oscillation ratio of the bubble can be aggravated from 0.12% to 79.94% with the increasing acoustic driving pressure and blood viscosity, or the decreasing vessel size and microbubble shell visco-elastic properties. The maximum compression velocity on the bubble shell will be enhanced from 0.19 to 22.79 m/s by the increasing vessel size and acoustic pressure, or the decreasing microbubble shell visco-elasticity and blood viscosity. As the results, the peak values of microstreaming-induced shear stress on the vessel wall increases from 0.003 to 26.95 kPa and the deformation degree of vessel is raised from 1.01 to 1.49, due to the enhanced acoustic amplitude, or the decreasing vessel size, blood viscosity and microbubble shell visco-elasticity. Moreover, it also suggests that, among above impact parameters, microbubble resonance frequency and UCA shell elasticity

  16. In vivo evidence for antioxidant potential of estrogen in microvessels of female spontaneously hypertensive rats.

    PubMed

    Dantas, Ana Paula V; Tostes, Rita C A; Fortes, Zuleica B; Costa, Sonia G; Nigro, Dorothy; Carvalho, Maria Helena C

    2002-02-01

    In studies conducted in vitro, it has been demonstrated that estrogen has an antioxidant potential that may contribute to its protective effects on the cardiovascular system. However, the antioxidant effect of estrogen in vivo has not been demonstrated. To address this issue, in this study the effects of estrogen on oxidative stress were evaluated in microvessels studied in vivo. Oxidative stress was evaluated by using intravital microscopy in mesenteric arterioles from female spontaneously hypertensive rats (SHR) in physiological estrous (OE), ovariectomized (OVX), OVX treated with estradiol (E(2)), or estradiol + progesterone (E/P). The mesenteries were superfused with hydroethidine, a reduced and nonfluorescent precursor of ethidium bromide (EB). In the presence of reactive oxygen species, hydroethidine is transformed intracellularly in EB, which binds to DNA and can be detected by its red fluorescence. The percentage of EB-positive nuclei along the arteriolar wall in OVX (28.4 +/- 4.3) was significantly increased compared with OE (14.2 +/- 3.9; P<0.05). The OVX overproduction of oxyradicals was attenuated by E(2) (15.7 +/- 2.2) and E/P (14.8 +/- 0.8). Treatment with the superoxide dismutase mimetic MnTMPyP attenuated by 75% the oxidation of hydroethidine in both OE and OVX. Conversely, mannitol, that decomposes hydroxyl radical, and L-NAME, a nitric oxide synthase inhibitor, had no significant effects on hydroethidine oxidation. No differences on hydrogen peroxide plasma concentration were observed among the groups, suggesting that superoxide anion is the most likely oxyradical involved in the increased oxidative stress observed in OVX. The treatment of mesenteries with diphenyleneiodonium (DPI), an nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase inhibitor, but not with oxypurinol, a xanthine-oxidase inhibitor, produced a significant reduction of oxyradical generation in OVX microvessels and a slight decrease in those from OE. Chronic treatment of

  17. Emergent molecular theory of initiation of detonation: the effect of molecular and crystal structure on thermal stability of high density energy materials

    NASA Astrophysics Data System (ADS)

    Kukla, Maija; Tsyshevsky, Roman; Sharia, Onise

    The sensitivity to detonation initiation of high density energy materials along with their performance are two most important criteria for choosing the best material for explosive formulations, booster engines, detonators, etc. After numerous experimental and theoretical attempts to develop a single parameter describing sensitivity of different classes of energetic materials, one concludes that the complexity of physical and chemical explosive properties cannot be trivialized. We report here the results of our theoretical and computational studies of thermal decomposition mechanisms and kinetics of five classes of EM: pentaerythritol tetranitrate (PETN), nitramine cyclotetramethylene-tetranitramine (HMX), diamino-dinitroethene (DADNE), bis-(nitrofurazano)-furoxane (BNFF) and benchmark triamino-trinitrobenzene (TATB). Our modeling reveals how the thermal stability depends on the molecular structure of the material and how the crystal structure may additionally hinder or catalyze decomposition reactions. We will also discuss an effect of crystalline defects on sensitivity and performance of materials.

  18. The Role of Cyclic AMP in Normalizing the Function of Engineered Human Blood Microvessels in Microfluidic Collagen Gels

    PubMed Central

    Wong, Keith H. K.; Truslow, James G.; Tien, Joe

    2010-01-01

    Nearly all engineered tissues must eventually be vascularized to survive. To this end, we and others have recently developed methods to synthesize extracellular matrix-based scaffolds that contain open microfluidic networks. These scaffolds serve as templates for the formation of endothelial tubes that can be perfused; whether such microvascular structures are stable and/or functional is largely unknown. Here, we show that compounds that elevate intracellular concentrations of the second messenger cyclic AMP (cAMP) strongly normalize the phenotype of engineered human microvessels in microfluidic type I collagen gels. Cyclic AMP-elevating agents promoted vascular stability and barrier function, and reduced cellular turnover. Under conditions that induced the highest levels of cAMP, the physiology of engineered microvessels in vitro quantitatively mirrored that of native vessels in vivo. Computational analysis indicated that cAMP stabilized vessels partly via its enhancement of barrier function. PMID:20303168

  19. Use of the interior cavity of the P22 capsid for site-specific initiation of atom-transfer radical polymerization with high-density cargo loading.

    PubMed

    Lucon, Janice; Qazi, Shefah; Uchida, Masaki; Bedwell, Gregory J; LaFrance, Ben; Prevelige, Peter E; Douglas, Trevor

    2012-10-01

    Virus-like particles (VLPs) have emerged as important and versatile architectures for chemical manipulation in the development of functional hybrid nanostructures. Here we demonstrate a successful site-selective initiation of atom-transfer radical polymerization reactions to form an addressable polymer constrained within the interior cavity of a VLP. Potentially, this protein-polymer hybrid of P22 and cross-linked poly(2-aminoethyl methacrylate) could be useful as a new high-density delivery vehicle for the encapsulation and delivery of small-molecule cargos. In particular, the encapsulated polymer can act as a scaffold for the attachment of small functional molecules, such as fluorescein dye or the magnetic resonance imaging (MRI) contrast agent Gd-diethylenetriaminepentacetate, through reactions with its pendant primary amine groups. Using this approach, a significant increase in the labelling density of the VLP, compared to that of previous modifications of VLPs, can be achieved. These results highlight the use of multimeric protein-polymer conjugates for their potential utility in the development of VLP-based MRI contrast agents with the possibility of loading other cargos.

  20. At what levels of total low- or high-density lipoprotein cholesterol should diet/drug therapy be initiated? United States guidelines.

    PubMed

    LaRosa, J C

    1990-03-20

    Guidelines for the detection, evaluation and treatment of hypercholesterolemia in adults have been established in the United States. These guidelines recommend that total cholesterol levels be used for screening purposes. Total cholesterol levels greater than 240 mg/dl are considered "high," those from 200 to 239 mg/dl "borderline," and those less than 200 mg/dl "normal," regardless of the person's age or gender. All persons in the high category, as well as those in the borderline category who have other risk factors or established vascular disease, require measurements of low-density lipoprotein (LDL) cholesterol levels. LDL cholesterol levels are used to guide the selection of treatment. Patients with LDL cholesterol levels greater than 130 mg/dl are candidates for active diet therapy. Those whose LDL cholesterol levels are 160 to 190 mg/dl after 3 to 6 months of diet therapy are candidates for drug therapy. A high-density lipoprotein (HDL) level less than 35 mg/dl is considered a risk factor and may influence the level of LDL at which drug therapy is initiated. Some observers have expressed concern that these guidelines overemphasize LDL cholesterol at the expense of total cholesterol, HDL cholesterol and triglyceride levels. Nevertheless, the guidelines have been broadly accepted and currently serve as the basis for a widespread public-health education program.

  1. Coordinated regulation of nitrogen supply mode and initial cell density for energy storage compounds production with economized nitrogen utilization in a marine microalga Isochrysis zhangjiangensis.

    PubMed

    Chi, Lei; Yao, Changhong; Cao, Xupeng; Xue, Song

    2016-01-01

    Lipids and carbohydrates are main energy storage compounds (ESC) of microalgae under stressed conditions and they are potential feedstock for biofuel production. Yet, the sustainable and commercially successful production of ESC in microalgae needs to consider nitrogen utilization efficiency. Here the impact of different initial cell densities (ICDs) on ESC accumulation in Isochrysis zhangjiangensis under two nitrogen supply modes (an initially equal concentration of nitrogen per-cell in the medium (N1) and an equal total concentration of nitrogen in the culture system (N2)) were investigated. The results demonstrated that the highest ESC yield (1.36gL(-1)) at N1, which included a maximal nitrogen supply in the cultivation system, and the highest ESC content (66.5%) and ESC productivity per mass of nitrogen (3.28gg(-1) (N) day(-1)) at N2, were all obtained under a high ICD of 8.0×10(6)cellsmL(-1). Therefore I. zhangjiangensis qualifies for ESC-enriched biomass production with economized nitrogen utilization.

  2. Effects of crocin on reperfusion-induced oxidative/nitrative injury to cerebral microvessels after global cerebral ischemia.

    PubMed

    Zheng, Yong-Qiu; Liu, Jian-Xun; Wang, Jan-Nong; Xu, Li

    2007-03-23

    This paper studied the effects of crocin, a pharmacologically active component of Crocus sativus L., on ischemia/reperfusion (I/R) injury in mice cerebral microvessels. Transient global cerebral ischemia (20 min), followed by 24 h of reperfusion, significantly promoted the generation of nitric oxide (NO) and malondialdehyde (MDA) in cortical microvascular homogenates, as well as markedly reduced the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) and promoted the activity of nitric oxide synthase (NOs). Reperfusion for 24 h led to serous edema with substantial microvilli loss, vacuolation, membrane damage and mitochondrial injuries in cortical microvascular endothelial cells (CMEC). Furthermore, enhanced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and decreased expression of matrix metalloproteinase-9 (MMP-9) were detected in cortical microvessels after I (20 min)/R (24 h). Reperfusion for 24 h also induced membrane (functional) G protein-coupled receptor kinase 2 (GRK2) expression, while it reduced cytosol GRK2 expression. Pretreatment with crocin markedly inhibited oxidizing reactions and modulated the ultrastructure of CMEC in mice with 20 min of bilateral common carotid artery occlusion (BCCAO) followed by 24 h of reperfusion in vivo. Furthermore, crocin inhibited GRK2 translocation from the cytosol to the membrane and reduced ERK1/2 phosphorylation and MMP-9 expression in cortical microvessels. We propose that crocin protects the brain against excessive oxidative stress and constitutes a potential therapeutic candidate in transient global cerebral ischemia.

  3. Vascular Mechanics in Decellularized Aortas and Coronary Resistance Microvessels in Type 2 Diabetic db/db Mice.

    PubMed

    Anghelescu, Mircea; Tonniges, Jeffrey R; Calomeni, Ed; Shamhart, Patricia E; Agarwal, Gunjan; Gooch, Keith J; Trask, Aaron J

    2015-11-01

    We previously reported differences in stiffness between macro- and micro-vessels in type 2 diabetes (T2DM). The aim of this study was to define the mechanical properties of the ECM independent of vascular cells in coronary resistance micro-vessels (CRMs) and macro-vessels (aorta) in control Db/db and T2DM db/db mice. Passive vascular remodeling and mechanics were measured in both intact and decellularized CRMs and aortas from 0 to 125 mmHg. We observed no differences in intact control and diabetic aortic diameters, wall thicknesses, or stiffnesses (p > 0.05). Aortic decellularization caused a significant increase in internal and external diameters and incremental modulus over a range of pressures that occurred to a similar degree in T2DM. Differences in aortic diameters due to decellularization occurred at lower pressures (0-75 mmHg) and converged with intact aortas at higher, physiological pressures (100-125 mmHg). In contrast, CRM decellularization caused increased internal diameter and incremental modulus only in the db/db mice, but unlike the aorta, the intact and decellularized CRM curves were more parallel. These data suggest that (1) micro-vessels may be more sensitive to early adverse consequences of diabetes than macro-vessels and (2) the ECM is a structural limit in aortas, but not CRMs. PMID:25986954

  4. Control of in vivo microvessel ingrowth by modulation of biomaterial local architecture and chemistry

    SciTech Connect

    Sanders, Joan E.; Baker, Aaron B.; Golledge, Stephen

    2002-04-01

    We developed a method for controlling local architecture and chemistry simultaneously in biomaterial implants to control microvessel ingrowth in vivo. Porous polypropylene disks (5 mm in diameter and 40 um thick) were plasma-coated with a fluoropolymer and then laser-drilled with 50-*m-diameter holes through their thickness. We then oxidized the disks to create hydroxyl functionality on the exposed polypropylene (inside the holes). Acrylamide was grafted to the hydroxyl groups through polymerization in the presence of activating ceric ions. Staining with toluidine blue O demonstrated that grafting occurred only inside the holes. We used the Hoffman degradation reaction to convert the amide groups of acrylamide to amine groups, and then we used ethylene glycol diglycidyl ether to attach biomolecules of interest inside the holes: secreted protein acidic and rich in cysteine (SPARC) peptide Lys-Gly-His-Lys (KGHK; angiogenic), thrombospondin-2 (TSP; antiangiogenic), or albumin (rat; neutral). In vivo testing in a rat subcutaneous dorsum model for a 3-week interval demonstrated a greater vessel surface area (p = 0.032) and a greater number of vessels (p = 0.043) in tissue local to the holes with KGHKimmobilized disks than with TSP-immobilized disks. However, differences between KGHK-immobilized and albuminimmobilized disks were less significant (p = 0.120 and p = 0.289 for the vessel surface area and number of vessels, respectively). The developed methods have potential applications in biomaterial design applications for which selective neovascularization is desired.

  5. Selective capture of endothelial and perivascular cells from brain microvessels using laser capture microdissection.

    PubMed

    Kinnecom, Katie; Pachter, Joel S

    2005-12-01

    Laser capture microdissection (LCM) of the major cell types comprising brain microvessels offers a powerful technology to explore the molecular basis of the blood-brain barrier in health and disease. However, the ability to selectively retrieve endothelial or perivascular cells, without cross-contamination from the other, has proven difficult. Additionally, histochemical methods previously described for use with LCM have not allowed for identification of all the different size branches of the microvascular tree. Here, we describe a double immunostaining method, combining bright-field and fluorescence microscopy, and using an extensive dehydration with xylene, to clearly identify and spatially resolve endothelial from perivascular cells within all size microvascular branches in frozen brain sections. LCM of these sections, coupled with RNA analysis by reverse-transcription polymerase chain reaction, revealed that captured endothelial cells show endothelial markers but no detectable markers for astrocytes or smooth muscle cells/pericytes. Conversely, captured astrocytes or smooth muscle cells/pericytes demonstrate their respective markers, but not those of endothelial cells. This approach has applicability to microarray analysis, thereby enabling global gene profiling of the different cell types along the entirety of the brain microvascular tree.

  6. Tight junction protein expression and barrier properties of immortalized mouse brain microvessel endothelial cells.

    PubMed

    Brown, Rachel C; Morris, Andrew P; O'Neil, Roger G

    2007-01-26

    Understanding the molecular and biochemical mechanisms regulating the blood-brain barrier is aided by in vitro model systems. Many studies have used primary cultures of brain microvessel endothelial cells for this purpose. However, primary cultures limit the generation of material for molecular and biochemical assays since cells grow slowly, are prone to contamination by other neurovascular unit cells, and lose blood-brain barrier characteristics when passaged. To address these issues, immortalized cell lines have been generated. In these studies, we assessed the suitability of the immortalized mouse brain endothelial cell line, bEnd3, as a blood-brain barrier model. RT-PCR and immunofluorescence indicated expression of multiple tight junction proteins. bEnd3 cells formed barriers to radiolabeled sucrose, and responded like primary cultures to disrupting stimuli. Exposing cells to serum-free media on their basolateral side significantly decreased paracellular permeability; astrocyte-conditioned media did not enhance barrier properties. The serum-free media-induced decrease in permeability was correlated with an increase in claudin-5 and zonula occludens-1 immunofluorescence at cell-cell contracts. We conclude that bEnd3 cells are an attractive candidate as a model of the blood-brain barrier due to their rapid growth, maintenance of blood-brain barrier characteristics over repeated passages, formation of functional barriers and amenability to numerous molecular interventions.

  7. Tight junction protein expression and barrier properties of immortalized mouse brain microvessel endothelial cells.

    PubMed

    Brown, Rachel C; Morris, Andrew P; O'Neil, Roger G

    2007-01-26

    Understanding the molecular and biochemical mechanisms regulating the blood-brain barrier is aided by in vitro model systems. Many studies have used primary cultures of brain microvessel endothelial cells for this purpose. However, primary cultures limit the generation of material for molecular and biochemical assays since cells grow slowly, are prone to contamination by other neurovascular unit cells, and lose blood-brain barrier characteristics when passaged. To address these issues, immortalized cell lines have been generated. In these studies, we assessed the suitability of the immortalized mouse brain endothelial cell line, bEnd3, as a blood-brain barrier model. RT-PCR and immunofluorescence indicated expression of multiple tight junction proteins. bEnd3 cells formed barriers to radiolabeled sucrose, and responded like primary cultures to disrupting stimuli. Exposing cells to serum-free media on their basolateral side significantly decreased paracellular permeability; astrocyte-conditioned media did not enhance barrier properties. The serum-free media-induced decrease in permeability was correlated with an increase in claudin-5 and zonula occludens-1 immunofluorescence at cell-cell contracts. We conclude that bEnd3 cells are an attractive candidate as a model of the blood-brain barrier due to their rapid growth, maintenance of blood-brain barrier characteristics over repeated passages, formation of functional barriers and amenability to numerous molecular interventions. PMID:17169347

  8. The wall traction induced by flowing red blood cells in model microvessels and its potential mechanotransduction

    NASA Astrophysics Data System (ADS)

    Freund, Jonathan; Vermot, Julien

    2013-11-01

    There is evidence in early embryonic development, even well before advective oxygen transport is important, that the presence of red bloods cells per se trigger essential steps of normal vascular development. For example, showed that sequestration of blood cells early in the development of a mouse, such that the hematocrit is reduced, suppresses normal vascular network development. Vascular development also provides a model for remodeling and angiogenesis. We consider the transient stresses associated with blood cells flowing in model microvessels of comparable diameter to those at early stages of development (6 μm to 12 μm). A detailed simulation tool is used to show that passing blood cells present a significant fluctuating traction signature on the vessel wall, well above the mean stresses. This is particularly pronounced for slow flows (<= 50 μm/s) or small diameters (<= 7 μm), for which root-mean-square wall traction fluctuations can exceed their mean. These events potentially present mechanotranduction triggers that direct development or remodeling. Attenuation of such fluctuating tractions by a viscoelastic endothelial glycocalyx layer is also considered. NSF supported.

  9. Effects of noradrenaline and neuropeptide Y on rat mesenteric microvessel contraction.

    PubMed

    Chen, H; Fetscher, C; Schäfers, R F; Wambach, G; Philipp, T; Michel, M C

    1996-02-01

    We have studied the contractile effects of the sympathetic transmitter noradrenaline and its cotransmitter neuropeptide Y (NPY) given alone and in combination on isolated rat mesenteric resistance vessels (200-300 microns diameter). Noradrenaline and NPY each concentration-dependently contracted rat mesenteric microvessels (EC50 approximately equal to 800 nM and 10 nM, respectively), but noradrenaline caused considerably greater maximal effects than NPY (14.3 mN vs. 3.5 mN). A low antagonistic potency of yohimbine indicated that the response to noradrenaline did not involve alpha 2-adrenoceptors, and the subtype-selective antagonists 5-methylurapidil, tamsulosin and chloroethylclonidine indicated mediation via an alpha 1A-adrenoceptor. Shallow Schild regressions for prazosin and 5-methylurapidil indicated that an alpha 1-adrenoceptor subtype with relatively low prazosin affinity might additionally be involved. Studies with the NPY analogues PYY, [Leu31, Pro34] NPY and NPY18-36 demonstrated that NPY acted via a Y1 NPY receptor. In addition to its direct vasoconstricting effects NPY also lowered the noradrenaline EC50 but did not appreciably affect maximal noradrenaline responses indicating possible potentiation. The potentiating NPY response occurred with similar agonist potency as the direct contractile NPY effects and also via a Y1 NPY receptor. The Ca2+ entry blocker nitrendipine (300 nM) reduced direct contractile responses to noradrenaline and NPY but did not affect the potentiation response to NPY.

  10. Simulated two-dimensional red blood cell motion, deformation, and partitioning in microvessel bifurcations.

    PubMed

    Barber, Jared O; Alberding, Jonathan P; Restrepo, Juan M; Secomb, Timothy W

    2008-10-01

    Movement, deformation, and partitioning of mammalian red blood cells (RBCs) in diverging microvessel bifurcations are simulated using a two-dimensional, flexible-particle model. A set of viscoelastic elements represents the RBC membrane and the cytoplasm. Motion of isolated cells is considered, neglecting cell-to-cell interactions. Center-of-mass trajectories deviate from background flow streamlines due to migration of flexible cells towards the mother vessel centerline upstream of the bifurcation and due to flow perturbations caused by cell obstruction in the neighborhood of the bifurcation. RBC partitioning in the bifurcation is predicted by determining the RBC fraction entering each branch, for a given partition of total flow and for a given upstream distribution of RBCs. Typically, RBCs preferentially enter the higher-flow branch, leading to unequal discharge hematocrits in the downstream branches. This effect is increased by migration toward the centerline but decreased by the effects of obstruction. It is stronger for flexible cells than for rigid circular particles of corresponding size, and decreases with increasing parent vessel diameter. For unequally sized daughter vessels, partitioning is asymmetric, with RBCs tending to enter the smaller vessel. Partitioning is not significantly affected by branching angles. Model predictions are consistent with previous experimental results.

  11. Changes in Bone Mineral Density After Initiation of Antiretroviral Treatment With Tenofovir Disoproxil Fumarate/Emtricitabine Plus Atazanavir/Ritonavir, Darunavir/Ritonavir, or Raltegravir

    PubMed Central

    Brown, Todd T.; Moser, Carlee; Currier, Judith S.; Ribaudo, Heather J.; Rothenberg, Jennifer; Kelesidis, Theodoros; Yang, Otto; Dubé, Michael P.; Murphy, Robert L.; Stein, James H.; McComsey, Grace A.

    2015-01-01

    Background. Specific antiretroviral therapy (ART) medications and the severity of human immunodeficiency virus (HIV) disease before treatment contribute to bone mineral density (BMD) loss after ART initiation. Methods. We compared the percentage change in BMD over 96 weeks in 328 HIV-infected, treatment-naive individuals randomized equally to tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) plus atazanavir/ritonavir (ATV/r), darunavir/ritonavir (DRV/r), or raltegravir (RAL). We also determined whether baseline levels of inflammation markers and immune activation were independently associated with BMD loss. Results. At week 96, the mean percentage changes from baseline in spine and hip BMDs were similar in the protease inhibitor (PI) arms (spine: −4.0% in the ATV/r group vs −3.6% in the DRV/r [P = .42]; hip: −3.9% in the ATV/r group vs −3.4% in the DRV/r group [P = .36]) but were greater in the combined PI arms than in the RAL arm (spine: −3.8% vs −1.8% [P < .001]; hip: −3.7% vs −2.4% [P = .005]). In multivariable analyses, higher baseline concentrations of high-sensitivity C-reactive protein, interleukin 6, and soluble CD14 were associated with greater total hip BMD loss, whereas markers of CD4+ T-cell senescence and exhaustion (CD4+CD28−CD57+PD1+) and CD4+ T-cell activation (CD4+CD38+HLA-DR+) were associated with lumbar spine BMD loss. Conclusions. BMD losses 96 weeks after ART initiation were similar in magnitude among patients receiving PIs, ATV/r, or DRV/r but lowest among those receiving RAL. Inflammation and immune activation/senescence before ART initiation independently predicted subsequent BMD loss. PMID:25948863

  12. The Effects of Taoren-Honghua Herb Pair on Pathological Microvessel and Angiogenesis-Associated Signaling Pathway in Mice Model of CCl4-Induced Chronic Liver Disease.

    PubMed

    Xi, Shengyan; Yue, Lifeng; Shi, Mengmeng; Peng, Ying; Xu, Yangxinzi; Wang, Xinrong; Li, Qian; Kang, Zhijun; Li, Hanjing; Wang, Yanhui

    2016-01-01

    Chronic liver disease is one of the most common diseases that threaten human health. Effective treatment is still lacking in western medicine. Semen Persicae (Taoren) and Flos Carthami (Honghua) are known to relieve acute hepatic injury and inflammation, improve microcirculation, and reduce tissue fiber. The aim of our study is to investigate the potential mechanisms of Taoren-Honghua Herb Pair (THHP) in murine model of chronic liver disease caused by Carbon Tetrachloride (CCl4). Mice were randomly divided into seven groups: (1) blank, (2) model, (3) control (colchicine, 0.1 mg/kg), (4) THHP (5.53, 2.67, and 1.33 g/kg), and (5) Tao Hong Siwu Decoction (THSWD) (8.50 g/kg). Histological change and microvessels density were examined by microscopy. Hepatic function, serum fibrosis related factors, and hepatic vascular endothelial growth factor (VEGF) were measured with ELISA. VEGF, kinase insert domain-containing receptor (KDR), Flt-1, and Akt mRNA expression in hepatic tissue were determined with PCR. Tissues of Akt, pAkt, KDR, and Flt-1 were measured with western blotting. Data from this study showed that THHP improved hepatic function and restrained the hepatic inflammation and fibrosis. Its role in inhibiting pathological angiogenesis and hepatic fibrogenesis may be through affecting the angiogenesis-associated VEGF and its upstream and downstream signaling pathways. PMID:27293456

  13. The Effects of Taoren-Honghua Herb Pair on Pathological Microvessel and Angiogenesis-Associated Signaling Pathway in Mice Model of CCl4-Induced Chronic Liver Disease

    PubMed Central

    Xi, Shengyan; Yue, Lifeng; Shi, Mengmeng; Peng, Ying; Xu, Yangxinzi; Wang, Xinrong; Li, Qian; Kang, Zhijun; Li, Hanjing; Wang, Yanhui

    2016-01-01

    Chronic liver disease is one of the most common diseases that threaten human health. Effective treatment is still lacking in western medicine. Semen Persicae (Taoren) and Flos Carthami (Honghua) are known to relieve acute hepatic injury and inflammation, improve microcirculation, and reduce tissue fiber. The aim of our study is to investigate the potential mechanisms of Taoren-Honghua Herb Pair (THHP) in murine model of chronic liver disease caused by Carbon Tetrachloride (CCl4). Mice were randomly divided into seven groups: (1) blank, (2) model, (3) control (colchicine, 0.1 mg/kg), (4) THHP (5.53, 2.67, and 1.33 g/kg), and (5) Tao Hong Siwu Decoction (THSWD) (8.50 g/kg). Histological change and microvessels density were examined by microscopy. Hepatic function, serum fibrosis related factors, and hepatic vascular endothelial growth factor (VEGF) were measured with ELISA. VEGF, kinase insert domain-containing receptor (KDR), Flt-1, and Akt mRNA expression in hepatic tissue were determined with PCR. Tissues of Akt, pAkt, KDR, and Flt-1 were measured with western blotting. Data from this study showed that THHP improved hepatic function and restrained the hepatic inflammation and fibrosis. Its role in inhibiting pathological angiogenesis and hepatic fibrogenesis may be through affecting the angiogenesis-associated VEGF and its upstream and downstream signaling pathways. PMID:27293456

  14. Evidence for a non-universal stellar initial mass function in low-redshift high-density early-type galaxies

    NASA Astrophysics Data System (ADS)

    Dutton, Aaron A.; Mendel, J. Trevor; Simard, Luc

    2012-05-01

    We determine an absolute calibration of stellar mass-to-light ratios for the densest ≃3 per cent of early-type galaxies in the local Universe (redshift z≃ 0.08) from Sloan Digital Sky Survey (SDSS) Data Release 7. This sample of ˜4000 galaxies has, assuming a Chabrier initial mass function (IMF), effective stellar surface densities Σe > 2500 M⊙ pc-2, stellar population synthesis (SPS) stellar masses log10(MSPS/M⊙) < 10.8 and aperture velocity dispersions of ? (68 per cent range). In contrast to typical early-type galaxies, we show that these dense early-type galaxies follow the virial Fundamental Plane, which suggests that mass follows light. With the additional assumption that any dark matter does not follow the light, the dynamical masses of dense galaxies provide a direct measurement of stellar masses. Our dynamical masses (Mdyn), obtained from the spherical Jeans equations, are only weakly sensitive to the choice of anisotropy (β) due to the relatively large aperture of the SDSS fibre for these galaxies: Rap≃ 1.5Re. Assuming isotropic orbits (β= 0), we find a median log10(Mdyn/MSPS) = 0.233 ± 0.003, consistent with a Salpeter IMF, while more bottom-heavy IMFs and standard Milky Way IMFs are strongly disfavoured. Our results are consistent with, but do not require, a dependence of the IMF on dynamical mass or velocity dispersion. We find evidence for a colour dependence to the IMF such that redder galaxies have heavier IMFs with Mdyn/MSPS∝ (g-r)1.13 ± 0.09. This may reflect a more fundamental dependence of the IMF on the age or metallicity of a stellar population, or the density at which the stars formed.

  15. Non-Newtonian characteristics of peristaltic flow of blood in micro-vessels

    NASA Astrophysics Data System (ADS)

    Maiti, S.; Misra, J. C.

    2013-08-01

    Of concern in the paper is a generalized theoretical study of the non-Newtonian characteristics of peristaltic flow of blood through micro-vessels, e.g. arterioles. The vessel is considered to be of variable cross-section and blood to be a Herschel-Bulkley type of fluid. The progressive wave front of the peristaltic flow is supposed sinusoidal/straight section dominated (SSD) (expansion/contraction type); Reynolds number is considered to be small with reference to blood flow in the micro-circulatory system. The equations that govern the non-Newtonian peristaltic flow of blood are considered to be non-linear. The objective of the study has been to examine the effect of amplitude ratio, mean pressure gradient, yield stress and the power law index on the velocity distribution, wall shear stress, streamline pattern and trapping. It is observed that the numerical estimates for the aforesaid quantities in the case of peristaltic transport of blood in a channel are much different from those for flow in an axisymmetric vessel of circular cross-section. The study further shows that peristaltic pumping, flow velocity and wall shear stress are significantly altered due to the non-uniformity of the cross-sectional radius of blood vessels of the micro-circulatory system. Moreover, the magnitude of the amplitude ratio and the value of the fluid index are important parameters that affect the flow behaviour. Novel features of SSD wave propagation that affect the flow behaviour of blood have also been discussed.

  16. VEGF-121 preserves renal microvessel structure and ameliorates secondary renal disease following acute kidney injury

    PubMed Central

    Leonard, Ellen C.; Friedrich, Jessica L.; Basile, David P.

    2008-01-01

    Acute kidney injury induced by renal ischemia-reperfusion (I/R) compromises microvascular density and predisposes to chronic kidney disease (CKD) and sodium-dependent hypertension. VEGF-121 was administered to rats fed a standard (0.4%) sodium diet at various times following recovery from I/R injury for up to 35 days. VEGF-121 had no effect on the initial loss of renal function, as indicated by serum creatinine levels measured 24 h after injury. Serum creatinine levels declined thereafter, indicative of renal repair. Rats were then switched to an elevated (4.0%) sodium diet for an additional 28 days to induce CKD. The 4.0% sodium diet enhanced renal hypertrophy, interstitial volume, albuminuria, and cardiac hypertrophy relative to postischemic animals maintained on the 0.4% sodium diet. Administration of VEGF-121 from day 0 to 14, day 0 to 35, or day 3 to 35 after I/R suppressed the effects of sodium diet on CKD development, while delayed administration of VEGF-121 from day 21 to 35 had no effect. Endothelial nitric oxide synthase protein levels were upregulated in postischemic animals, and this effect was significantly increased by the 4.0% sodium diet but was not influenced by prior treatment with VEGF. Conversely, microvascular density was preserved in postischemic animals treated with VEGF-121 relative to vehicle-treated postischemic animals. These data suggest that early, but not delayed, treatment with VEGF-121 can preserve vascular structure after ischemia and influence chronic renal function in response to elevated sodium intake. PMID:18799550

  17. Low-fat, increased fruit, vegetable, and grain dietary pattern, fractures, and bone mineral density: the Women's Health Initiative Dietary Modification Trial123

    PubMed Central

    Wactawski-Wende, Jean; Wu, LieLing; Rodabough, Rebecca J; Watts, Nelson B; Tylavsky, Frances; Freeman, Ruth; Hendrix, Susan; Jackson, Rebecca

    2009-01-01

    Background: The effects of dietary changes on osteoporosis, low bone density, and frequent falls are unestablished. Objective: We assessed the effect of the Women's Health Initiative Dietary Modification low-fat and increased fruit, vegetable, and grain intervention on incident hip, total, and site-specific fractures and self-reported falls, and, in a subset, on bone mineral density (BMD). Design: Postmenopausal women (n = 48,835) aged 50–79 y (18.6% of minority race-ethnicity) were randomly assigned to receive the Dietary Modification intervention (40%, n = 19,541) (daily goal: ≤20% of energy as fat, ≥5 servings of vegetables and fruit, and ≥6 servings of grains) or to a comparison group that received no dietary changes (60%; n = 29,294). Results: After a mean 8.1 y of follow-up, 215 women in the intervention group and 285 women in the comparison group (annualized rate: 0.14% and 0.12%, respectively) experienced a hip fracture (hazard ratio: 1.12; 95% CI: 0.94, 1.34; P = 0.21). The intervention group (n = 5423; annualized rate: 3.44%) had a lower rate of reporting ≥2 falls than did the comparison group (n = 8695; annualized rate: 3.67%) (HR: 0.92; 95% CI: 0.89, 0.96; P < 0.01). There was a significant interaction according to hormone therapy use; those in the comparison group receiving hormone therapy had the lowest incidence of hip fracture. In a subset of 3951 women, hip BMD at years 3, 6, and 9 was 0.4–0.5% lower in the intervention group than in the comparison group (P = 0.003). Conclusions: A low-fat and increased fruit, vegetable, and grain diet intervention modestly reduced the risk of multiple falls and slightly lowered hip BMD but did not change the risk of osteoporotic fractures. This trial was registered at clinicaltrials.gov as NCT00000611. PMID:19403636

  18. Distal leg epidermal nerve fiber density as a surrogate marker of HIV-associated sensory neuropathy risk: risk factors and change following initial antiretroviral therapy.

    PubMed

    Shikuma, Cecilia M; Bennett, Kara; Ananworanich, Jintanat; Gerschenson, Mariana; Teeratakulpisarn, Nipat; Jadwattanakul, Tanate; DeGruttola, Victor; McArthur, Justin C; Ebenezer, Gigi; Chomchey, Nitiya; Praihirunkit, Pairoa; Hongchookiat, Piranun; Mathajittiphun, Pornpen; Nakamoto, Beau; Hauer, Peter; Phanuphak, Praphan; Phanuphak, Nittaya

    2015-10-01

    Distal leg epidermal nerve fiber density (ENFD) is a validated predictor of HIV sensory neuropathy (SN) risk. We assessed how ENFD is impacted by initiation of first-time antiretroviral therapy (ART) in subjects free of neuropathy and how it is altered when mitochondrial toxic nucleoside medications are used as part of ART. Serial changes in proximal thigh and distal leg ENFD were examined over 72 weeks in 150 Thai subjects randomized to a regimen of stavudine (d4T) switching to zidovudine (ZDV) at 24 weeks vs ZDV vs tenofovir (TDF) for the entire duration of study, all given in combination with nevirapine. We found individual variations in ENFD change, with almost equal number of subjects who decreased or increased their distal leg ENFD over 72 weeks and no relationship to nucleoside backbone or to development of neuropathic signs or symptoms. Lower baseline distal leg ENFD and greater increases in mitochondrial oxidative phosphorylation complex I (CI) activity were associated with larger increases in distal leg ENFD over 72 weeks. Distal leg ENFD correlated with body composition parameters (body surface area, body mass index, height) as well as with blood pressure measurements. Assessed together with a companion cross-sectional study, we found that mean distal leg ENFD in all HIV+ subjects was lower than in HIV- subjects but similar among HIV+ groups whether ART-naïve or on d4T with/without neuropathy/neuropathic symptoms. The utility of ENFD as a useful predictor of small unmyelinated nerve fiber damage and neuropathy risk in HIV may be limited in certain populations.

  19. Initial implementation of the conversion from the energy-subtracted CT number to electron density in tissue inhomogeneity corrections: An anthropomorphic phantom study of radiotherapy treatment planning

    SciTech Connect

    Tsukihara, Masayoshi; Noto, Yoshiyuki; Sasamoto, Ryuta; Hayakawa, Takahide; Saito, Masatoshi

    2015-03-15

    Purpose: To achieve accurate tissue inhomogeneity corrections in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted computed tomography (CT) number to an electron density (ΔHU–ρ{sub e} conversion), which provides a single linear relationship between ΔHU and ρ{sub e} over a wide range of ρ{sub e}. The purpose of this study is to present an initial implementation of the ΔHU–ρ{sub e} conversion method for a treatment planning system (TPS). In this paper, two example radiotherapy plans are used to evaluate the reliability of dose calculations in the ΔHU–ρ{sub e} conversion method. Methods: CT images were acquired using a clinical dual-source CT (DSCT) scanner operated in the dual-energy mode with two tube potential pairs and an additional tin (Sn) filter for the high-kV tube (80–140 kV/Sn and 100–140 kV/Sn). Single-energy CT using the same DSCT scanner was also performed at 120 kV to compare the ΔHU–ρ{sub e} conversion method with a conventional conversion from a CT number to ρ{sub e} (Hounsfield units, HU–ρ{sub e} conversion). Lookup tables for ρ{sub e} calibration were obtained from the CT image acquisitions for tissue substitutes in an electron density phantom (EDP). To investigate the beam-hardening effect on dosimetric uncertainties, two EDPs with different sizes (a body EDP and a head EDP) were used for the ρ{sub e} calibration. Each acquired lookup table was applied to two radiotherapy plans designed using the XiO TPS with the superposition algorithm for an anthropomorphic phantom. The first radiotherapy plan was for an oral cavity tumor and the second was for a lung tumor. Results: In both treatment plans, the performance of the ΔHU–ρ{sub e} conversion was superior to that of the conventional HU–ρ{sub e} conversion in terms of the reliability of dose calculations. Especially, for the oral tumor plan, which dealt with dentition and bony structures, treatment

  20. Endothelial Surface Glycocalyx Can Regulate Flow-Induced Nitric Oxide Production in Microvessels In Vivo

    PubMed Central

    Yen, Wanyi; Cai, Bin; Yang, Jinlin; Zhang, Lin; Zeng, Min; Tarbell, John M.; Fu, Bingmei M.

    2015-01-01

    Due to its unique location, the endothelial surface glycocalyx (ESG) at the luminal side of the microvessel wall may serve as a mechano-sensor and transducer of blood flow and thus regulate endothelial functions. To examine this role of the ESG, we used fluorescence microscopy to measure nitric oxide (NO) production in post-capillary venules and arterioles of rat mesentery under reduced (low) and normal (high) flow conditions, with and without enzyme pretreatment to remove heparan sulfate (HS) of the ESG and in the presence of an endothelial nitric oxide synthase (eNOS) inhibitor, NG-monomethyl-L-arginine (L-NMMA). Rats (SD, 250–300g) were anesthetized. The mesentery was gently taken out from the abdominal cavity and arranged on the surface of a glass coverslip for the measurement. An individual post-capillary venule or arteriole was cannulated and loaded for 45 min with 5 μM 4, 5-Diaminofluorescein diacetate, a membrane permeable fluorescent indictor for NO, then the NO production was measured for ~10 min under a low flow (~300 μm/s) and for ~60 min under a high flow (~1000 μm/s). In the 15 min after switching to the high flow, DAF-2-NO fluorescence intensity increased to 1.27-fold of its baseline, DAF-2-NO continuously increased under the high flow, to 1.53-fold of its baseline in 60 min. Inhibition of eNOS by 1 mM L-NMMA attenuated the flow-induced NO production to 1.13-fold in 15 min and 1.30-fold of its baseline in 60 min, respectively. In contrast, no significant increase in NO production was observed after switching to the high flow for 60 min when 1 h pretreatment with 50 mU/mL heparanase III to degrade the ESG was applied. Similar NO production was observed in arterioles under low and high flows and under eNOS inhibition. Our results suggest that ESG participates in endothelial cell mechanosensing and transduction through its heparan sulfate to activate eNOS. PMID:25575016

  1. Very different performance of the power Doppler modalities of several ultrasound machines ascertained by a microvessel flow phantom

    PubMed Central

    2013-01-01

    Introduction In many patients with rheumatoid arthritis (RA) subclinical disease activity can be detected with ultrasound (US), especially using power Doppler US (PDUS). However, PDUS may be highly dependent on the type of machine. This could create problems both in clinical trials and in daily clinical practice. To clarify how the PDUS signal differs between machines we created a microvessel flow phantom. Methods The flow phantom contained three microvessels (150, 1000, 2000 microns). A syringe pump was used to generate flows. Five US machines were used. Settings were optimised to assess the lowest detectable flow for each US machine. Results The minimal detectable flow velocities showed very large differences between the machines. Only two of the machines may be able to detect the very low flows in the capillaries of inflamed joints. There was no clear relation with price. One of the lower-end machines actually performed best in all three vessel sizes. Conclusions We created a flow phantom to test the sensitivity of US machines to very low flows in small vessels. The sensitivity of the power Doppler modalities of 5 different machines was very different. The differences found between the machines are probably caused by fundamental differences in processing of the PD signal or internal settings inaccessible to users. Machines considered for PDUS assessment of RA patients should be tested using a flow phantom similar to ours. Within studies, only a single machine type should be used. PMID:24286540

  2. Insulin-degrading enzyme in brain microvessels: proteolysis of amyloid {beta} vasculotropic variants and reduced activity in cerebral amyloid angiopathy.

    PubMed

    Morelli, Laura; Llovera, Ramiro E; Mathov, Irina; Lue, Lih-Fen; Frangione, Blas; Ghiso, Jorge; Castaño, Eduardo M

    2004-12-31

    The accumulation of amyloid beta (Abeta) in the walls of small vessels in the cerebral cortex is associated with diseases characterized by dementia or stroke. These include Alzheimer's disease, Down syndrome, and sporadic and hereditary cerebral amyloid angiopathies (CAAs) related to mutations within the Abeta sequence. A higher tendency of Abeta to aggregate, a defective clearance to the systemic circulation, and insufficient proteolytic removal have been proposed as mechanisms that lead to Abeta accumulation in the brain. By using immunoprecipitation and mass spectrometry, we show that insulin-degrading enzyme (IDE) from isolated human brain microvessels was capable of degrading (125)I-insulin and cleaved Abeta-(1-40) wild type and the genetic variants Abeta A21G (Flemish), Abeta E22Q (Dutch), and Abeta E22K (Italian) at the predicted sites. In microvessels from Alzheimer's disease cases with CAA, IDE protein levels showed a 44% increase as determined by sandwich enzyme-linked immunosorbent assay and Western blot. However, the activity of IDE upon radiolabeled insulin was significantly reduced in CAA as compared with age-matched controls. These results support the notion that a defect in Abeta proteolysis by IDE contributes to the accumulation of this peptide in the cortical microvasculature. Moreover they raise the possibility that IDE inhibition or inactivation is a pathogenic mechanism that may open novel strategies for the treatment of cerebrovascular Abeta amyloidoses. PMID:15489232

  3. A high-density wireless underground sensor network (WUSN) to quantify hydro-ecological interactions for a UK floodplain; project background and initial results

    NASA Astrophysics Data System (ADS)

    Verhoef, A.; Choudhary, B.; Morris, P. J.; McCann, J.

    2012-04-01

    Floodplain meadows support some of the most diverse vegetation in the UK, and also perform key ecosystem services, such as flood storage and sediment retention. However, the UK now has less than 1500 ha of this unique habitat remaining. In order to conserve and better exploit the services provided by this grassland, an improved understanding of its functioning is essential. Vegetation functioning and species composition are known to be tightly correlated to the hydrological regime, and related temperature and nutrient regime, but the mechanisms controlling these relationships are not well established. The FUSE* project aims to investigate the spatiotemporal variability in vegetation functioning (e.g. photosynthesis and transpiration) and plant community composition in a floodplain meadow near Oxford, UK (Yarnton Mead), and their relationship to key soil physical variables (soil temperature and moisture content), soil nutrient levels and the water- and energy-balance. A distributed high density Wireless Underground Sensor Network (WUSN) is in the process of being established on Yarnton Mead. The majority, or ideally all, of the sensing and transmitting components will be installed below-ground because Yarnton Mead is a SSSI (Site of Special Scientific Interest, due to its unique plant community) and because occasionally sheep or cattle are grazing on it, and that could damage the nodes. This prerequisite has implications for the maximum spacing between UG nodes and their communications technologies; in terms of signal strength, path losses and requirements for battery life. The success of underground wireless communication is highly dependent on the soil type and water content. This floodplain environment is particularly challenging in this context because the soil contains a large amount of clay near the surface and is therefore less favourable to EM wave propagation than sandy soils. Furthermore, due to high relative saturation levels (as a result of high

  4. Plasminogen Kringle 5 Induces Apoptosis of Brain Microvessel Endothelial Cells: Sensitization by Radiation and Requirement for GRP78 and LRP1

    PubMed Central

    McFarland, Braden C.; Stewart, Jerry; Hamza, Amal; Nordal, Robert; Davidson, Donald J.; Henkin, Jack; Gladson, Candece L.

    2009-01-01

    Recombinant plasminogen kringle 5 (rK5) has been shown to induce apoptosis of dermal microvessel endothelial cells (MvEC) in a manner that requires glucose-regulated protein 78 (GRP78). As we are interested in anti-angiogenic therapy for glioblastoma tumors, and the effectiveness of anti-angiogenic therapy can be enhanced when combined with radiation, we investigated the pro-apoptotic effects of rK5 combined with radiation on brain MvEC. We found that rK5 treatment of brain MvEC induced apoptosis in a dose- and time-dependent manner, and that prior irradiation significantly sensitized (500-fold) the cells to rK5-induced apoptosis. The rK5-induced apoptosis of both unirradiated and irradiated MvEC required expression of GRP78 and the low density lipoprotein receptor-related protein 1 (LRP1), a scavenger receptor, based on downregulation studies with small interfering RNA, and blocking studies with either a GRP78 antibody or a competitive inhibitor of ligand binding to LRP1. Furthermore, p38 MAP kinase was found to be a necessary downstream effector for rK5-induced apoptosis. These data suggest that irradiation sensitizes brain MvEC to the rK5-induced apoptosis and that this signal requires LRP1 internalization of GRP78 and the activation of p38 MAP kinase. Our findings suggest that prior irradiation would have a dose-sparing effect on rK5 anti-angiogenic therapy for brain tumors and further suggest that the effects of rK5 would be tumor-specific as the expression of GRP78 protein is upregulated on the brain MvEC in glioblastoma tumor biopsies as compared to the normal brain. PMID:19549899

  5. MicroRNA-155 Regulates ROS Production, NO Generation, Apoptosis and Multiple Functions of Human Brain Microvessel Endothelial Cells Under Physiological and Pathological Conditions.

    PubMed

    Liu, Yajing; Pan, Qunwen; Zhao, Yuhui; He, Caixia; Bi, Kexia; Chen, Yusen; Zhao, Bin; Chen, Yanfang; Ma, Xiaotang

    2015-12-01

    The microRNA-155 (miR155) regulates various functions of cells. Dysfunction or injury of endothelial cells (ECs) plays an important role in the pathogenesis of various vascular diseases. In this study, we investigated the role and potential mechanisms of miR155 in human brain microvessel endothelial cells (HBMECs) under physiological and pathological conditions. We detected the effects of miR155 silencing on ROS production, NO generation, apoptosis and functions of HBMECs at basal and in response to oxidized low density lipoprotein (ox-LDL). Western blot and q-PCR were used for analyzing the gene expression of epidermal growth factor receptor (EGFR)/extracellular regulated protein kinases (ERK)/p38 mitogen-activated protein kinase (p38 MAPK), phosphatidylinositol-3-kinase (PI3K) and serine/threonine kinase(Akt), activated caspase-3, and intercellular adhesion molecule-1 (ICAM-1). Results showed that under both basal and challenge situations: (1) Silencing of miR155 decreased apoptosis and reactive oxygen species (ROS) production of HBMECs, whereas, promoted nitric oxide (NO) generation. (2) Silencing of miR155 increased the proliferation, migration, and tube formation ability of HBMECs, while decreased cell adhesion ability. (3) Gene expression analyses showed that EGFR/ERK/p38 MAPK and PI3K/Akt were increased and that activated caspase-3 and ICAM-1 mRNA were decreased after knockdown of miR155. In conclusion, knockdown of miR155 could modulate ROS production, NO generation, apoptosis and function of HBMECs via regulating diverse gene expression, such as caspase-3, ICAM-1 and EGFR/ERK/p38 MAPK and PI3K/Akt pathways.

  6. Initial measurements of plasma current and electron density profiles using a polarimeter/interferometer (POINT) for long pulse operation in EAST (invited)

    NASA Astrophysics Data System (ADS)

    Liu, H. Q.; Qian, J. P.; Jie, Y. X.; Ding, W. X.; Brower, D. L.; Zou, Z. Y.; Li, W. M.; Lian, H.; Wang, S. X.; Yang, Y.; Zeng, L.; Lan, T.; Yao, Y.; Hu, L. Q.; Zhang, X. D.; Wan, B. N.

    2016-11-01

    A double-pass, radially viewing, far-infrared laser-based POlarimeter-INTerferometer (POINT) system utilizing the three-wave technique has been implemented for diagnosing the plasma current and electron density profiles in the Experimental Advanced Superconducting Tokamak (EAST). POINT has been operated routinely during the most recent experimental campaign and provides continuous 11 chord line-integrated Faraday effect and density measurement throughout the entire plasma discharge for all heating schemes and all plasma conditions (including ITER relevant scenario development). Reliability of both the polarimetric and interferometric measurements is demonstrated in 25 s plasmas with H-mode and 102 s long-pulse discharges. Current density, safety factor (q), and electron density profiles are reconstructed using equilibrium fitting code (EFIT) with POINT constraints for the plasma core.

  7. Velocimetry of red blood cells in microvessels by the dual-slit method: effect of velocity gradients.

    PubMed

    Roman, Sophie; Lorthois, Sylvie; Duru, Paul; Risso, Frédéric

    2012-11-01

    The dual-slit is a photometric technique used for the measurement of red blood cell (RBC) velocity in microvessels. Two photometric windows (slits) are positioned along the vessel. Because the light is modulated by the RBCs flowing through the microvessel, a time dependent signal is captured for each window. A time delay between the two signals is obtained by temporal cross correlation, and is used to deduce a velocity, knowing the distance between the two slits. Despite its wide use in the field of microvascular research, the velocity actually measured by this technique has not yet been unambiguously related to a relevant velocity scale of the flow (e.g. mean or maximal velocity) or to the blood flow rate. This is due to a lack of fundamental understanding of the measurement and also because such a relationship is crucially dependent on the non-uniform velocity distribution of RBCs in the direction parallel to the light beam, which is generally unknown. The aim of the present work is to clarify the physical significance of the velocity measured by the dual-slit technique. For that purpose, dual-slit measurements were performed on computer-generated image sequences of RBCs flowing in microvessels, which allowed all the parameters related to this technique to be precisely controlled. A parametric study determined the range of optimal parameters for the implementation of the dual-slit technique. In this range, it was shown that, whatever the parameters governing the flow, the measured velocity was the maximal RBC velocity found in the direction parallel to the light beam. This finding was then verified by working with image sequences of flowing RBCs acquired in PDMS micro-systems in vitro. Besides confirming the results and physical understanding gained from the study with computer generated images, this in vitro study showed that the profile of RBC maximal velocity across the channel was blunter than a parabolic profile, and exhibited a non-zero sliding velocity at

  8. Fucoidan Extracted from Hijiki Protects Brain Microvessel Endothelial Cells Against Diesel Exhaust Particle Exposure-Induced Disruption.

    PubMed

    Choi, Young-Sook; Eom, Sang-Yong; Kim, In-Soo; Ali, Syed F; Kleinman, Michael T; Kim, Yong-Dae; Kim, Heon

    2016-05-01

    This study was performed to evaluate the protective effects of fucoidan against the decreased function of primary cultured bovine brain microvessel endothelial cells (BBMECs) after exposure to diesel exhaust particles (DEPs). BBMECs were extracted from bovine brains and cultured until confluent. To evaluate the function of BBMECs, we performed a permeability test using cell-by-cell equipment and by Western blot analysis for zonular occludens-1 (ZO-1), which is a tight junction protein of BMECs, and evaluated oxidative stress in BBMECs using the DCFH-DA assay and the CUPRAC-BCS assay. The increased oxidative stress in BBMECs following DEP exposure was suppressed by fucoidan. In addition, permeability of BBMECs induced by DEP exposure was decreased by fucoidan treatment. Our results showed that fucoidan protects against BBMEC disruption induced by DEP exposure. This study provides evidence that fucoidan might protect the central nervous system (CNS) against DEP exposure.

  9. Silane-initiated nucleation in chemically active plasmas: validation of density functionals, mechanisms, and pressure-dependent variational transition state calculations.

    PubMed

    Bao, Junwei Lucas; Truhlar, Donald G

    2016-04-21

    The growth of anionic silicon hydride clusters is a critically important process in nanodusty plasmas. In the current study, we focus on the formation of homologs of silylene (Sin+1H2n+2(-), n = 3, 4) and silyl (SinH2n+1(-), n = 4, 5) anions via anion-neutral reaction pathways. Species like silyl or silylene anions and their related elementary reactions, which are involved in the formation of silicon hydride clusters, were not used in developing exchange-correlation (xc) density functionals (i.e., they were not included in the training set of semiempirical density functionals); therefore, we explored the accuracy of various widely used xc density functionals based on reaction energies and barrier heights. Among the 21 density functionals we tested, M06-2X has the best performance for a hybrid functional, and MN15-L has the best performance for a local functional. Thermal rate constants of the elementary reactions involved in the reaction mechanism are calculated using M06-2X and multistructural canonical variational transition state theory with the small-curvature tunneling approximation (MS-CVT/SCT). The pressure dependence of unimolecular isomerization reactions is treated with system-specific quantum RRK theory (SS-QRRK) and the Lindemann-Hinshelwood mechanism.

  10. Dynamics of Gram-negative bacteria population density in a soil in the course of the succession initiated by chitin and cellulose

    NASA Astrophysics Data System (ADS)

    Konstantin, Ivanov; Lubov, Polyanskaya

    2014-05-01

    The functions of actinomycetes in polymer destruction in soil traditionally considered as the dominant, compare to another groups of bacteria. Gram-positive bacteria also have ecological functions in destruction of soil organic matter. The role of Gram-negative bacteria has been researched in the microbial succession in terms of polymers destruction, which are widely spreads in soils: chitin and cellulose. The method with nalidixic acid as an inhibitor of DNA division of Gram-negative bacteria was modified. By modified method microbial succession of Gram-negative bacteria in the different horizons of a chernozem under aerobic and anaerobic conditions was researched. Chitin and cellulose as the source of nutrients with moistening was used in experiments. The introduction of chitin had no positive effect on the population density of Gram-negative bacteria in a chernozem, but it advanced the date of their appearance in microbial succession: the maximum of Gram-negative bacteria population density was registered on the 3rd- 7th day of the experiment with adding chitin. Compare to the control, which one was without any nutrient adding this dynamics registered much earlier. Consequently, the introduction of chitin as an additional source of nutrition promoted revealing of the Gram-negative bacteria in soil already at the early stages of the succession. In the course of the succession, when the fungal mycelium begins to die off, the actinomycetic mycelium increases in length, i.e., Gram-negative bacteria are replaced at this stage with Gram-positive ones, the leading role among which belongs to actinomycetes. The growth rate of Gram-negative bacteria is higher than that of actinomycetes, so they start chitin utilization at the early stages of the succession, whereas actinomycetes dominate at the late stages. The population density of Gram-negative bacteria was lower under the anaerobic conditions as compared with that in the aerobic ones. The population density of Gram

  11. Enhanced insulin binding to blood-brain barrier in vivo and to brain microvessels in vitro in newborn rabbits

    SciTech Connect

    Frank, H.J.; Jankovic-Vokes, T.; Pardridge, W.M.; Morris, W.L.

    1985-08-01

    Insulin is a known growth factor in nonneural tissue, and recent studies have shown that there are insulin receptors throughout the adult and fetal central nervous system. Since insulin has only limited access to the adult brain, this study was undertaken to determine if insulin has increased availability to the newborn brain where it may act as a neonatal brain growth promoter. In vivo brain uptake of SVI-insulin after a single-pass carotid injection was measured in newborn, 3-wk-old and 11-wk-old (adult) rabbits. The brain uptake index (BUI) relative to a THOH reference was 22.0 +/- 1.1% (mean +/- SEM) for newborn, 12.8 +/- 0.6% for 3-wk-old, and 6.5 +/- 0.1% for adults. Specific SVI-insulin binding to isolated cerebral microvessels was similarly increased in the newborn compared with the 3-wk-old and adult animals. Scatchard analysis revealed that the difference was due to an increase in receptor number with only minimal changes in the affinity. The increased availability of circulating insulin to the newborn brain was further corroborated by elevated CSF/serum and brain/serum insulin ratios in the newborn versus adult. These results suggest that insulin has increased access to the newborn brain where it may function as a growth factor.

  12. Isolation and growth of endothelial cells from the microvessels of the newborn human foreskin in cell culture.

    PubMed

    Davison, P M; Bensch, K; Karasek, M A

    1980-10-01

    A procedure for the isolation and in vitro cultivation of endothelial cells from the microvessels of the newborn human foreskin dermis is described. The epidermis was removed from foreskin tissue using a Castroviejo keratotome (0.1 mm shim). Endothelial cells were released from the dermal vessels by trypsinization of 5 mm2 sections of dermis at 37 degrees C for 40 min. Cells were expressed into Minimal Essential Medium (MEM) containing 10% pooled human serum, collected by centrifugation and plated onto either a plain plastic or a fibronectin treated culture surface. In primary culture the rate of endothelial cell proliferation was dependent upon serum type and concentration being optimal in 50% pooled human serum. High serum concentration in combination with pretreatment of the culture surface with fibronectin was required for maximal proliferation rate, for the cells to achieve confluence and for subcultivation. Primary and subcultured cells were characterized as endothelial by light microscopic, immunofluorescent (Factor VIII associated protein) and ultrastructural (Weibel-Palade body) criteria.

  13. Cilostazol inhibits leukocyte-endothelial cell interactions in murine microvessels after transient bilateral common carotid artery occlusion.

    PubMed

    Fukuoka, Takuya; Hayashi, Takeshi; Hirayama, Makiko; Maruyama, Hajime; Tanahashi, Norio

    2014-01-16

    Leukocyte behavior in the cerebral microvasculature following vessel occlusion has not been fully elucidated. The purpose of this study was to investigate the effects of cilostazol on leukocyte behavior (rolling and adhesion) in murine cerebral microvessels following transient bilateral carotid artery occlusion using intravital fluorescence microscopy. Four groups of mice were assigned: a sham group (n=16); an ischemia (induced by 15-min occlusion of bilateral common carotid arteries) and reperfusion (I/R) group (n=13); I/R+cilostazol (I/R+CZ3 mg/kg) group (I/R after oral administration of cilostazol at 3 mg/kg) (n=8); and I/R+cilostazol (I/R+CZ30 mg/kg) group (I/R after oral administration of cilostazol at 30 mg/kg) (n=12). Leukocytes labeled with 0.05% acridine orange were administered intravenously and their behavior was investigated at 3 and 6 h after reperfusion. Numbers of rolling or adherent leukocytes were expressed as the count per square millimeter per 30s. Numbers of rolling and adherent leukocytes at 3 and 6h after reperfusion were significantly higher in the I/R group than in the sham or I/R+CZ30 mg/kg groups in both pial veins (P<0.05) and pial arteries (P<0.05). Cilostazol (30 mg/kg) inhibited leukocyte-endothelial interactions following cerebral ischemia and reperfusion.

  14. Rational Design of Prevascularized Large 3D Tissue Constructs Using Computational Simulations and Biofabrication of Geometrically Controlled Microvessels.

    PubMed

    Arrigoni, Chiara; Bongio, Matilde; Talò, Giuseppe; Bersini, Simone; Enomoto, Junko; Fukuda, Junji; Moretti, Matteo

    2016-07-01

    A major challenge in the development of clinically relevant 3D tissue constructs is the formation of vascular networks for oxygenation, nutrient supply, and waste removal. To this end, this study implements a multimodal approach for the promotion of vessel-like structures formation in stiff fibrin hydrogels. Computational simulations have been performed to identify the easiest microchanneled configuration assuring normoxic conditions throughout thick cylindrical hydrogels (8 mm height, 6 mm ∅), showing that in our configuration a minimum of three microchannels (600 μm ∅), placed in a non-planar disposition, is required. Using small hydrogel bricks with oxygen distribution equal to the microchanneled configuration, this study demonstrates that among different culture conditions, co-culture of mesenchymal and endothelial cells supplemented with ANG-1 and VEGF leads to the most developed vascular network. Microchanneled hydrogels have been then cultured in the same conditions both statically and in a bioreactor for 7 d. Unexpectedly, the combination between shear forces and normoxic conditions is unable to promote microvascular networks formation in three-channeled hydrogels. Differently, application of either shear forces or normoxic conditions alone results in microvessels outgrowth. These results suggest that to induce angiogenesis in engineered constructs, complex interactions between several biochemical and biophysical parameters have to be modulated.

  15. Nuclear Factor of Activated T Cells Is Activated in the Endothelium of Retinal Microvessels in Diabetic Mice

    PubMed Central

    Zetterqvist, Anna V.; Blanco, Fabiana; Öhman, Jenny; Kotova, Olga; Berglund, Lisa M.; de Frutos Garcia, Sergio; Al-Naemi, Raed; Wigren, Maria; McGuire, Paul G.; Gonzalez Bosc, Laura V.; Gomez, Maria F.

    2015-01-01

    The pathogenesis of diabetic retinopathy (DR) remains unclear but hyperglycemia is an established risk factor. Endothelial dysfunction and changes in Ca2+ signaling have been shown to precede the onset of DR. We recently demonstrated that high extracellular glucose activates the Ca2+/calcineurin-dependent transcription factor NFAT in cerebral arteries and aorta, promoting the expression of inflammatory markers. Here we show, using confocal immunofluorescence, that NFAT is expressed in the endothelium of retinal microvessels and is readily activated by high glucose. This was inhibited by the NFAT blocker A-285222 as well as by the ectonucleotidase apyrase, suggesting a mechanism involving the release of extracellular nucleotides. Acute hyperglycemia induced by an IP-GTT (intraperitoneal glucose tolerance test) resulted in increased NFATc3 nuclear accumulation and NFAT-dependent transcriptional activity in retinal vessels of NFAT-luciferase reporter mice. In both Akita (Ins2+/−) and streptozotocin- (STZ-) induced diabetic mice, NFAT transcriptional activity was elevated in retinal vessels. In vivo inhibition of NFAT with A-285222 decreased the expression of OPN and ICAM-1 mRNA in retinal vessels, prevented a diabetes driven downregulation of anti-inflammatory IL-10 in retina, and abrogated the increased vascular permeability observed in diabetic mice. Results identify NFAT signaling as a putative target for treatment of microvascular complications in diabetes. PMID:25918731

  16. Lattice Boltzmann Simulation of One Particle Migrating in a Pulsating Flow in Microvessel

    NASA Astrophysics Data System (ADS)

    Qiu, Bing; Tan, Hui-Li; Li, Hua-Bing

    2011-10-01

    A lattice Boltzmann model of two dimensions is used to simulate the movement of a single rigid particle suspended in a pulsating flow in micro vessel. The particle is as big as a red blood cell, and the micro vessel is four times as wide as the diameter of the particle. It is found that Segré—Silberberg effect will not respond to the pulsation of the flow when the Reynolds number is relatively high. However, when the Reynolds number is low enough, Segré—Silberberg effect disappears. In the steady flow, different initial position leads to different equilibrium positions. In a pulsating flow, different frequencies of pulsation also cause different equilibrium positions. Particularly, when the frequency of pulsation is closed to the human heart rate, Segré—Silberberg effect presents again. The evolutions of velocity, rotation, and trajectory of the particle are investigated to find the dynamics of such abnormal phenomenon.

  17. Electrically Stimulated Antagonist Muscle Contraction Increased Muscle Mass and Bone Mineral Density of One Astronaut - Initial Verification on the International Space Station

    PubMed Central

    Takano, Yoshio; Yoshimitsu, Kazuhiro; Omoto, Masayuki; Hashida, Ryuki; Tagawa, Yoshihiko; Inada, Tomohisa; Yamada, Shin; Ohshima, Hiroshi

    2015-01-01

    . Conclusions These results showed the orbital operation capability and utility, and the preventive effect of HTS for an astronaut’s musculoskeletal atrophy. The initial flight data together with the ground data obtained so far will be utilized in the future planning of human space exploration. PMID:26296204

  18. Blast exposure causes dynamic microglial/macrophage responses and microdomains of brain microvessel dysfunction.

    PubMed

    Huber, B R; Meabon, J S; Hoffer, Z S; Zhang, J; Hoekstra, J G; Pagulayan, K F; McMillan, P J; Mayer, C L; Banks, W A; Kraemer, B C; Raskind, M A; McGavern, D B; Peskind, E R; Cook, D G

    2016-04-01

    Exposure to blast overpressure (BOP) is associated with behavioral, cognitive, and neuroimaging abnormalities. We investigated the dynamic responses of cortical vasculature and its relation to microglia/macrophage activation in mice using intravital two-photon microscopy following mild blast exposure. We found that blast caused vascular dysfunction evidenced by microdomains of aberrant vascular permeability. Microglial/macrophage activation was specifically associated with these restricted microdomains, as evidenced by rapid microglial process retraction, increased ameboid morphology, and escape of blood-borne Q-dot tracers that were internalized in microglial/macrophage cell bodies and phagosome-like compartments. Microdomains of cortical vascular disruption and microglial/macrophage activation were also associated with aberrant tight junction morphology that was more prominent after repetitive (3×) blast exposure. Repetitive, but not single, BOPs also caused TNFα elevation two weeks post-blast. In addition, following a single BOP we found that aberrantly phosphorylated tau rapidly accumulated in perivascular domains, but cleared within four hours, suggesting it was removed from the perivascular area, degraded, and/or dephosphorylated. Taken together these findings argue that mild blast exposure causes an evolving CNS insult that is initiated by discrete disturbances of vascular function, thereby setting the stage for more protracted and more widespread neuroinflammatory responses.

  19. Erythropoietin delivered via intra-arterial infusion reduces endoplasmic reticulum stress in brain microvessels of rats following cerebral ischemia and reperfusion.

    PubMed

    Zhao, Haiping; Wang, Rongliang; Wu, Xiaoning; Liang, Jia; Qi, Zhifeng; Liu, Xiangrong; Min, Lianqiu; Ji, Xunming; Luo, Yumin

    2015-03-01

    Local infusion of low dose erythropoietin (EPO) alleviates cerebral ischemia and reperfusion (I/R) injury in rats; however, the underlying molecular mechanisms are still unclear. The present study investigated the effect of low dose EPO treatment on I/R-induced endoplasmic reticulum (ER) stress in brain tissue and isolated microvessels in rodents. Sprague-Dawley rats were subjected to 2 h ischemia/24 h reperfusion by middle cerebral artery (MCA) occlusion, then administered fluorescein isothiocyanate-labeled EPO via MCA infusion (MCAI) or subcutaneous injection (SI) to compare the efficiency of two modes of delivery. Neurobehavioral deficits and infarct volume, and the expression of ER stress-associated proteins and apoptosis in brain tissue or isolated microvessels, as well as the transcriptional activity of 16 factors involved in ER stress and the unfolded protein response in brain tissue was asscessed. A higher EPO level in cerebrospinal fluid and brain tissue was observed in rats treated with EPO by MCAI (800 IU/kg) than by SI (5000 IU/kg). Moreover, neurobehavioral deficits and infarct volume were reduced in rats treated with EPO by MCAI and salubrinal. EPO suppressed the expression of ER stress signals glucose-regulated protein 78, activating transcription factor (ATF) 6α, and CCAAT enhancer-binding protein homologous protein (CHOP), as well as that of the pro-apoptotic protein caspase-3 in brain microvessels, and decreased the number of CHOP-positive, apoptotic neurons. EPO treatment also reduced the transcriptional activities of CHOP, forkhead box protein O1, and ATF4. These results provide evidence that low dose EPO treatment via MCAI provides neuroprotection following acute ischemic stroke by inhibiting the ER stress response. PMID:25626440

  20. Exogenous arachidonic acid mediates permeability of human brain microvessel endothelial cells through prostaglandin E2 activation of EP3 and EP4 receptors.

    PubMed

    Dalvi, Siddhartha; Nguyen, Hieu H; On, Ngoc; Mitchell, Ryan W; Aukema, Harold M; Miller, Donald W; Hatch, Grant M

    2015-12-01

    The blood-brain barrier, formed by microvessel endothelial cells, is the restrictive barrier between the brain parenchyma and the circulating blood. Arachidonic acid (ARA; 5,8,11,14-cis-eicosatetraenoic acid) is a conditionally essential polyunsaturated fatty acid [20:4(n-6)] and is a major constituent of brain lipids. The current study examined the transport processes for ARA in confluent monolayers of human brain microvascular endothelial cells (HBMEC). Addition of radioactive ARA to the apical compartment of HBMEC cultured on Transwell(®) inserts resulted in rapid incorporation of radioactivity into the basolateral medium. Knock down of fatty acid transport proteins did not alter ARA passage into the basolateral medium as a result of the rapid generation of prostaglandin E2 (PGE2 ), an eicosanoid known to facilitate opening of the blood-brain barrier. Permeability following ARA or PGE2 exposure was confirmed by an increased movement of fluorescein-labeled dextran from apical to basolateral medium. ARA-mediated permeability was attenuated by specific cyclooxygenase-2 inhibitors. EP3 and EP4 receptor antagonists attenuated the ARA-mediated permeability of HBMEC. The results indicate that ARA increases permeability of HBMEC monolayers likely via increased production of PGE2 which acts upon EP3 and EP4 receptors to mediate permeability. These observations may explain the rapid influx of ARA into the brain previously observed upon plasma infusion with ARA. The blood-brain barrier, formed by microvessel endothelial cells, is a restrictive barrier between the brain parenchyma and the circulating blood. Radiolabeled arachidonic acid (ARA) movement across, and monolayer permeability in the presence of ARA, was examined in confluent monolayers of primary human brain microvessel endothelial cells (HBMECs) cultured on Transwell(®) plates. Incubation of HBMECs with ARA resulted in a rapid increase in HBMEC monolayer permeability. The mechanism was mediated, in part

  1. A three-dimensional model of an ultrasound contrast agent gas bubble and its mechanical effects on microvessels.

    PubMed

    Hosseinkhah, N; Hynynen, K

    2012-02-01

    Ultrasound contrast agents inside a microvessel, when driven by ultrasound, oscillate and induce mechanical stresses on the vessel wall. These mechanical stresses can produce beneficial therapeutic effects but also induce vessel rupture if the stresses are too high. Therefore, it is important to use sufficiently low pressure amplitudes to avoid rupturing the vessels while still inducing the desired therapeutic effects. In this work, we developed a comprehensive three-dimensional model of a confined microbubble inside a vessel while considering the bubble shell properties, blood viscosity, vessel wall curvature and the mechanical properties of the vessel wall. Two bubble models with the assumption of a spherical symmetric bubble and a simple asymmetrical bubble were simulated. This work was validated with previous experimental results and enabled us to evaluate the microbubbles' behaviour and the resulting mechanical stresses induced on the vessel walls. In this study, the fluid shear and circumferential stresses were evaluated as indicators of the mechanical stresses. The effects of acoustical parameters, vessel viscoelasticity and rigidity, vessel/bubble size and off-centre bubbles on bubble behaviour and stresses on the vessel were investigated. The fluid shear and circumferential stresses acting on the vessel varied with time and location. As the frequency changed, the microbubble oscillated with the highest amplitude at its resonance frequency which was different from the resonance frequency of an unbound bubble. The bubble resonance frequency increased as the rigidity of a flexible vessel increased. The fluid shear and circumferential stresses peaked at frequencies above the bubble's resonance frequency. The more rigid the vessels were, the more damped the bubble oscillations. The synergistic effect of acoustic frequency and vessel elasticity had also been investigated since the circumferential stress showed either an increasing trend or a decreasing one

  2. A Comparative Performance Analysis of Total PSA, Percentage Free PSA, PSA Velocity, and PSA Density versus the Detection of Primary Circulating Prostate Cells in Predicting Initial Prostate Biopsy Findings in Chilean Men

    PubMed Central

    Murray, Nigel P.; Reyes, Eduardo; Orellana, Nelson; Fuentealba, Cynthia; Dueñas, Ricardo

    2014-01-01

    Introduction. PSA parameters have been used in an attempt to improve the diagnostic yield of prostate screening tests; the detection of primary malignant circulating prostate cells (CPCs) may improve the diagnostic yield of screening and therefore avoid unnecessary biopsies. Patients and Methods. Prospective study of all men undergoing initial prostate biopsy due to an elevated total serum PSA. Free percent PSA, PSA velocity, and PSA density were determined. Primary CPCs were detected using standard immunocytochemistry. A positive test for CPCs was defined as one cell PSA (+) P504S (+) in an 8 ml blood sample. Positive predictive and negative predictive values, specificity, and sensitivity were calculated for each test as well as the number of biopsies avoided and cancers missed. Results. 303 men participated in the study of whom 113/303 (37.3%) men had prostate cancer. Of the three PSA based parameters, free percent PSA was superior, sensitivity 70.8%, and specificity 67.4%. Primary CPCs detection had a sensitivity of 88.5% and a specificity of 88.4% avoiding 181 (59.7%) biopsies, detecting 93/95 (98%) of clinically significant cancers, and missing 13 (11.5%) low grade, small volume tumors. Conclusions. The use of primary CPCs as a sequential test could decrease the number of initial prostate biopsies missing those cancers which are treated by active observation. PMID:25101294

  3. Association of Maternal Antiangiogenic Profile at Birth With Early Postnatal Loss of Microvascular Density in Offspring of Hypertensive Pregnancies

    PubMed Central

    Yu, Grace Z.; Aye, Christina Y.L.; Lewandowski, Adam J.; Davis, Esther F.; Khoo, Cheen P.; Newton, Laura; Yang, Cheng T.; Al Haj Zen, Ayman; Simpson, Lisa J.; O’Brien, Kathryn; Cook, David A.; Granne, Ingrid; Kyriakou, Theodosios; Channon, Keith M.; Watt, Suzanne M.

    2016-01-01

    Offspring of hypertensive pregnancies are more likely to have microvascular rarefaction and increased blood pressure in later life. We tested the hypothesis that maternal angiogenic profile during a hypertensive pregnancy is associated with fetal vasculogenic capacity and abnormal postnatal microvascular remodeling. Infants (n=255) born after either hypertensive or normotensive pregnancies were recruited for quantification of postnatal dermal microvascular structure at birth and 3 months of age. Vasculogenic cell potential was assessed in umbilical vein endothelial cells from 55 offspring based on in vitro microvessel tube formation and proliferation assays. Maternal angiogenic profile (soluble fms-like tyrosine kinase-1, soluble endoglin, vascular endothelial growth factor, and placental growth factor) was measured from postpartum plasma samples to characterize severity of pregnancy disorder. At birth, offspring born after hypertensive pregnancy had similar microvessel density to those born after a normotensive pregnancy, but during the first 3 postnatal months, they had an almost 2-fold greater reduction in total vessel density (−17.7±16.4% versus −9.9±18.7%; P=0.002). This postnatal loss varied according to the vasculogenic capacity of the endothelial cells of the infant at birth (r=0.49; P=0.02). The degree of reduction in both in vitro and postnatal in vivo vascular development was proportional to levels of antiangiogenic factors in the maternal circulation. In conclusion, our data indicate that offspring born to hypertensive pregnancies have reduced vasculogenic capacity at birth that predicts microvessel density loss over the first 3 postnatal months. Degree of postnatal microvessel reduction is proportional to levels of antiangiogenic factors in the maternal circulation at birth. PMID:27456522

  4. Association of Maternal Antiangiogenic Profile at Birth With Early Postnatal Loss of Microvascular Density in Offspring of Hypertensive Pregnancies.

    PubMed

    Yu, Grace Z; Aye, Christina Y L; Lewandowski, Adam J; Davis, Esther F; Khoo, Cheen P; Newton, Laura; Yang, Cheng T; Al Haj Zen, Ayman; Simpson, Lisa J; O'Brien, Kathryn; Cook, David A; Granne, Ingrid; Kyriakou, Theodosios; Channon, Keith M; Watt, Suzanne M; Leeson, Paul

    2016-09-01

    Offspring of hypertensive pregnancies are more likely to have microvascular rarefaction and increased blood pressure in later life. We tested the hypothesis that maternal angiogenic profile during a hypertensive pregnancy is associated with fetal vasculogenic capacity and abnormal postnatal microvascular remodeling. Infants (n=255) born after either hypertensive or normotensive pregnancies were recruited for quantification of postnatal dermal microvascular structure at birth and 3 months of age. Vasculogenic cell potential was assessed in umbilical vein endothelial cells from 55 offspring based on in vitro microvessel tube formation and proliferation assays. Maternal angiogenic profile (soluble fms-like tyrosine kinase-1, soluble endoglin, vascular endothelial growth factor, and placental growth factor) was measured from postpartum plasma samples to characterize severity of pregnancy disorder. At birth, offspring born after hypertensive pregnancy had similar microvessel density to those born after a normotensive pregnancy, but during the first 3 postnatal months, they had an almost 2-fold greater reduction in total vessel density (-17.7±16.4% versus -9.9±18.7%; P=0.002). This postnatal loss varied according to the vasculogenic capacity of the endothelial cells of the infant at birth (r=0.49; P=0.02). The degree of reduction in both in vitro and postnatal in vivo vascular development was proportional to levels of antiangiogenic factors in the maternal circulation. In conclusion, our data indicate that offspring born to hypertensive pregnancies have reduced vasculogenic capacity at birth that predicts microvessel density loss over the first 3 postnatal months. Degree of postnatal microvessel reduction is proportional to levels of antiangiogenic factors in the maternal circulation at birth.

  5. Association of Maternal Antiangiogenic Profile at Birth With Early Postnatal Loss of Microvascular Density in Offspring of Hypertensive Pregnancies.

    PubMed

    Yu, Grace Z; Aye, Christina Y L; Lewandowski, Adam J; Davis, Esther F; Khoo, Cheen P; Newton, Laura; Yang, Cheng T; Al Haj Zen, Ayman; Simpson, Lisa J; O'Brien, Kathryn; Cook, David A; Granne, Ingrid; Kyriakou, Theodosios; Channon, Keith M; Watt, Suzanne M; Leeson, Paul

    2016-09-01

    Offspring of hypertensive pregnancies are more likely to have microvascular rarefaction and increased blood pressure in later life. We tested the hypothesis that maternal angiogenic profile during a hypertensive pregnancy is associated with fetal vasculogenic capacity and abnormal postnatal microvascular remodeling. Infants (n=255) born after either hypertensive or normotensive pregnancies were recruited for quantification of postnatal dermal microvascular structure at birth and 3 months of age. Vasculogenic cell potential was assessed in umbilical vein endothelial cells from 55 offspring based on in vitro microvessel tube formation and proliferation assays. Maternal angiogenic profile (soluble fms-like tyrosine kinase-1, soluble endoglin, vascular endothelial growth factor, and placental growth factor) was measured from postpartum plasma samples to characterize severity of pregnancy disorder. At birth, offspring born after hypertensive pregnancy had similar microvessel density to those born after a normotensive pregnancy, but during the first 3 postnatal months, they had an almost 2-fold greater reduction in total vessel density (-17.7±16.4% versus -9.9±18.7%; P=0.002). This postnatal loss varied according to the vasculogenic capacity of the endothelial cells of the infant at birth (r=0.49; P=0.02). The degree of reduction in both in vitro and postnatal in vivo vascular development was proportional to levels of antiangiogenic factors in the maternal circulation. In conclusion, our data indicate that offspring born to hypertensive pregnancies have reduced vasculogenic capacity at birth that predicts microvessel density loss over the first 3 postnatal months. Degree of postnatal microvessel reduction is proportional to levels of antiangiogenic factors in the maternal circulation at birth. PMID:27456522

  6. Production and increased detection of amyloid beta protein and amyloidogenic fragments in brain microvessels, meningeal vessels and choroid plexus in Alzheimer's disease.

    PubMed

    Kalaria, R N; Premkumar, D R; Pax, A B; Cohen, D L; Lieberburg, I

    1996-01-01

    Recent advances indicate soluble amyloid beta (A beta) protein is produced constitutively during normal metabolism of the amyloid precursor protein (APP). This has not been directly examined in human brain vascular tissues. Using a panel of well-characterized antibodies, here we show that increased amounts of soluble A beta were found in isolated vascular tissues from AD subjects compared to age-matched controls without significant Alzheimer pathology. Immunocytochemical analyses of isolated vessel preparations showed characteristic transverse patterns of A beta deposits in large vessels with smooth muscle, however, fine A beta deposits were apparent even in capillaries. A proportion of such A beta protein and potentially amyloidogenic carboxyl terminal fragments were released by solubilization and disruption of the vascular basement membrane by collagenase treatments. We further demonstrated by in vitro metabolic labelling that soluble A beta or an A beta-like peptide is associated and produced by cerebral microvessels, meningeal vessels and the choroid plexus isolated postmortem from human as well as rat brain. Compared to those from young rats, cerebral microvessels from aging rats showed increased release of carboxyl terminal fragments of APP and A beta-like peptide. Our observations provide the first direct demonstration that human vascular tissues produce soluble A beta, a product of the secretory pathway in APP processing. Our findings also suggest that aging associated alterations in the basement membranes are a factor in A beta accumulation that results in vascular amyloid deposition, the principal feature of cerebral amyloid angiopathy.

  7. Exogenous arachidonic acid mediates permeability of human brain microvessel endothelial cells through prostaglandin E2 activation of EP3 and EP4 receptors.

    PubMed

    Dalvi, Siddhartha; Nguyen, Hieu H; On, Ngoc; Mitchell, Ryan W; Aukema, Harold M; Miller, Donald W; Hatch, Grant M

    2015-12-01

    The blood-brain barrier, formed by microvessel endothelial cells, is the restrictive barrier between the brain parenchyma and the circulating blood. Arachidonic acid (ARA; 5,8,11,14-cis-eicosatetraenoic acid) is a conditionally essential polyunsaturated fatty acid [20:4(n-6)] and is a major constituent of brain lipids. The current study examined the transport processes for ARA in confluent monolayers of human brain microvascular endothelial cells (HBMEC). Addition of radioactive ARA to the apical compartment of HBMEC cultured on Transwell(®) inserts resulted in rapid incorporation of radioactivity into the basolateral medium. Knock down of fatty acid transport proteins did not alter ARA passage into the basolateral medium as a result of the rapid generation of prostaglandin E2 (PGE2 ), an eicosanoid known to facilitate opening of the blood-brain barrier. Permeability following ARA or PGE2 exposure was confirmed by an increased movement of fluorescein-labeled dextran from apical to basolateral medium. ARA-mediated permeability was attenuated by specific cyclooxygenase-2 inhibitors. EP3 and EP4 receptor antagonists attenuated the ARA-mediated permeability of HBMEC. The results indicate that ARA increases permeability of HBMEC monolayers likely via increased production of PGE2 which acts upon EP3 and EP4 receptors to mediate permeability. These observations may explain the rapid influx of ARA into the brain previously observed upon plasma infusion with ARA. The blood-brain barrier, formed by microvessel endothelial cells, is a restrictive barrier between the brain parenchyma and the circulating blood. Radiolabeled arachidonic acid (ARA) movement across, and monolayer permeability in the presence of ARA, was examined in confluent monolayers of primary human brain microvessel endothelial cells (HBMECs) cultured on Transwell(®) plates. Incubation of HBMECs with ARA resulted in a rapid increase in HBMEC monolayer permeability. The mechanism was mediated, in part

  8. High-grade glioma before and after treatment with radiation and Avastin: Initial observations

    PubMed Central

    Fischer, Ingeborg; Cunliffe, Clare H.; Bollo, Robert J.; Raza, Shahzad; Monoky, David; Chiriboga, Luis; Parker, Erik C.; Golfinos, John G.; Kelly, Patrick J.; Knopp, Edmond A.; Gruber, Michael L.; Zagzag, David; Narayana, Ashwatha

    2008-01-01

    We evaluate the effects of adjuvant treatment with the angiogenesis inhibitor Avastin (bevacizumab) on pathological tissue specimens of high-grade glioma. Tissue from five patients before and after treatment with Avastin was subjected to histological evaluation and compared to four control cases of glioma before and after similar treatment protocols not including bevacizumab. Clinical and radiographic data were reviewed. Histological analysis focused on microvessel density and vascular morphology, and expression patterns of vascular endothelial growth factor–A (VEGF-A) and the hematopoietic stem cell, mesenchymal, and cell motility markers CD34, smooth muscle actin, D2-40, and fascin. All patients with a decrease in microvessel density had a radiographic response, whereas no response was seen in the patients with increased microvessel density. Vascular morphology showed apparent “normalization” after Avastin treatment in two cases, with thin-walled and evenly distributed vessels. VEGF-A expression in tumor cells was increased in two cases and decreased in three and did not correlate with treatment response. There was a trend toward a relative increase of CD34, smooth muscle actin, D2-40, and fascin immunostaining following treatment with Avastin. Specimens from four patients with recurrent malignant gliomas before and after adjuvant treatment (not including bevacizumab) had features dissimilar from our study cases. We conclude that a change in vascular morphology can be observed following anti-angiogenic treatment. There seems to be no correlation between VEGF-A expression and clinical parameters. While the phenomena we describe may not be specific to Avastin, they demonstrate the potential of tissue-based analysis for the discovery of clinically relevant treatment response biomarkers. PMID:18697955

  9. Elevated oxidative stress, iron accumulation around microvessels and increased 4-hydroxynonenal immunostaining in zone 1 of the liver acinus in hypercholesterolemic rabbits.

    PubMed

    Ong, Wei-Yi; Jenner, Andrew M; Pan, Ning; Ong, Choon-Nam; Halliwell, Barry

    2009-03-01

    Rabbits were fed a diet containing 1% cholesterol for 8 weeks and the levels of iron and oxidized lipids in liver analysed using atomic absorption spectroscopy and gas chromatography-mass spectrometry. A non-significant trend to an increase in iron level, but significant increases in the lipid peroxidation products, F(2)-isoprostanes and the cholesterol oxidation products 7 beta hydroxycholesterol, 7 ketocholesterol and cholesterol 5,6-alpha epoxide were detected in the liver of the cholesterol-fed rabbits. Histological analysis showed greater accumulation of lipids by Sudan red labelling in hepatocytes of zone I than zones II and III of the liver acinus. The increase in lipids coincided with an increase in iron staining in macrophages around liver microvessels and increased immunostaining to melanotransferrin and the lipid peroxidation product, 4-hydroxynonenal (4-HNE), in zone 1. The results are suggestive of microvascular damage associated with iron accumulation and oxidative stress in the liver during hypercholesterolemia.

  10. [Morphological signs of mitochondrial cytopathy in skeletal muscles and micro-vessel walls in a patient with cerebral artery dissection associated with MELAS syndrome].

    PubMed

    Sakharova, A V; Kalashnikova, L A; Chaĭkovskaia, R P; Mir-Kasimov, M F; Nazarova, M A; Pykhtina, T N; Dobrynina, L A; Patrusheva, N L; Patrushev, L I; Protskiĭ, S V

    2012-01-01

    Skin and muscles biopsy specimens of a patient harboring A3243G mutation in mitochondrial DNA, with dissection of internal carotid and vertebral arteries, associated with MELAS were studied using histochemical and electron-microscopy techniques. Ragged red fibers, regional variability of SDH histochemical reaction, two types of morphologically atypical mitochondria and their aggregation were found in muscle. There was correlation between SDH histochemical staining and number of mitochondria revealed by electron microscopy in muscle tissue. Similar mitochondrial abnormality, their distribution and cell lesions followed by extra-cellular matrix mineralization were found in the blood vessel walls. In line with generalization of cytopathy process caused by gene mutation it can be supposed that changes found in skin and muscle microvessels also exist in large cerebral vessels causing the vessel wall "weakness", predisposing them to dissection.

  11. Putative CD133+ melanoma cancer stem cells induce initial angiogenesis in vivo.

    PubMed

    Zimmerer, Rüdiger M; Matthiesen, Peter; Kreher, Fritjof; Kampmann, Andreas; Spalthoff, Simon; Jehn, Philipp; Bittermann, Gido; Gellrich, Nils-Claudius; Tavassol, Frank

    2016-03-01

    Tumor angiogenesis is essential for tumor growth and metastasis, and is regulated by a complex network of various types of cells, chemokines, and stimulating factors. In contrast to sprouting angiogenesis, tumor angiogenesis is also influenced by hypoxia, inflammation, and the attraction of bone-marrow-derived cells. Recently, cancer stem cells have been reported to mimic vascularization by differentiating into endothelial cells and inducing vessel formation. In this study, the influence of cancer stem cells on initial angiogenesis was evaluated for the metastatic melanoma cell line D10. Following flow cytometry, CD133+ and CD133- cells were isolated using magnetic cell separation and different cell fractions were transferred to porcine gelatin sponges, which were implanted into the dorsal skinfold chamber of immunocompromised mice. Angiogenesis was analyzed based on microvessel density over a 10-day period using in vivo fluorescence microscopy, and the results were verified using immunohistology. CD133+ D10 cells showed a significant induction of early angiogenesis in vivo, contrary to CD133- D10 cells, unsorted D10 cells, and negative control. Neovascularization was confirmed by visualizing endothelial cells by immunohistology using an anti-CD31 antibody. Because CD133+ cells are rare in clinical specimens and hardly amenable to functional assays, the D10 cell line provides a suitable model to study the angiogenic potential of putative cancer stem cells and the leukocyte-endothelial cell interaction in the dorsal skinfold chamber in vivo. This cancer stem cell model might be useful in the development and evaluation of therapeutic agents targeting tumors.

  12. Intramolecular Nuclear Flux Densities

    NASA Astrophysics Data System (ADS)

    Barth, I.; Daniel, C.; Gindensperger, E.; Manz, J.; PéRez-Torres, J. F.; Schild, A.; Stemmle, C.; Sulzer, D.; Yang, Y.

    The topic of this survey article has seen a renaissance during the past couple of years. Here we present and extend the results for various phenomena which we have published from 2012-2014, with gratitude to our coauthors. The new phenomena include (a) the first reduced nuclear flux densities in vibrating diatomic molecules or ions which have been deduced from experimental pump-probe spectra; these "experimental" nuclear flux densities reveal several quantum effects including (b) the "quantum accordion", i.e., during the turn from bond stretch to bond compression, the diatomic system never stands still — instead, various parts of it with different bond lengths flow into opposite directions. (c) Wavepacket interferometry has been extended from nuclear densities to flux densities, again revealing new phenomena: For example, (d) a vibrating nuclear wave function with compact initial shape may split into two partial waves which run into opposite directions, thus causing interfering flux densities. (e) Tunneling in symmetric 1-dimensional double-well systems yields maximum values of the associated nuclear flux density just below the potential barrier; this is in marked contrast with negligible values of the nuclear density just below the barrier. (f) Nuclear flux densities of pseudorotating nuclei may induce huge magnetic fields. A common methodologic theme of all topics is the continuity equation which connects the time derivative of the nuclear density to the divergence of the flux density, subject to the proper boundary conditions. (g) Nearly identical nuclear densities with different boundary conditions may be related to entirely different flux densities, e.g., during tunneling in cyclic versus non-cyclic systems. The original continuity equation, density and flux density of all nuclei, or of all nuclear degrees of freedom, may be reduced to the corresponding quantities for just a single nucleus, or just a single degree of freedom.

  13. Density Visualization

    ERIC Educational Resources Information Center

    Keiter, Richard L.; Puzey, Whitney L.; Blitz, Erin A.

    2006-01-01

    Metal rods of high purity for many elements are now commercially available and may be used to construct a display of relative densities. We have constructed a display with nine metal rods (Mg, Al, Ti, V, Fe, Cu, Ag, Pb, and W) of equal mass whose densities vary from 1.74 to 19.3 g cm[superscript -3]. The relative densities of the metals may be…

  14. Research Initiatives

    Cancer.gov

    This page provides detailed information about currently funded RFA initiatives both led by DCCPS, and those led by other NIH Institutes and Centers (I/Cs) that include DCCPS as a partner. Each initiative includes a table of funded grants and a map that shows the location of funded institutions.

  15. Low Bone Density

    MedlinePlus

    ... Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your bone density ... people with normal bone density. Detecting Low Bone Density A bone density test will determine whether you ...

  16. Re-evaluation of the role of P-glycoprotein in in vitro drug permeability studies with the bovine brain microvessel endothelial cells.

    PubMed

    Hakkarainen, Jenni J; Rilla, Kirsi; Suhonen, Marjukka; Ruponen, Marika; Forsberg, Markus M

    2014-03-01

    1.  Currently available in vitro blood-brain barrier models all have recognized restrictions. In addition to leakiness, inconsistent data about P-glycoprotein mediated efflux limit the attractiveness of the primary bovine brain microvessel endothelial cells (BBMECs). Therefore, we re-evaluated the role of P-glycoprotein mediated efflux with two culture conditions in BBMECs for prediction of drug permeability of potential P-glycoprotein substrates. 2.  BBMECs were monocultured on filters on petri dishes and on filter inserts, and expression and localization of P-glycoprotein were compared by using western blot and confocal microscopy, respectively. The functionality of P-glycoprotein was assessed by using cellular uptake, calcein-AM and bidirectional transport assays. 3.  P-glycoprotein expression was higher in BBMECs cultured on filter inserts decreasing the permeability of digoxin and paclitaxel, but not the permeability of vinblastine. However, the monocultured BBMECs were not able to demonstrate efflux in the bidirectional transport assays. Under certain culture conditions, occludin may not be correctly located, perhaps explaining in part the leakiness of BBMECs. 4.  In conclusion, BBMECs, despite possessing a functional P-glycoprotein, under certain culture conditions may not be a suitable in vitro model for the bidirectional transport assays and for predicting the permeability of drugs and xenobiotics that are potential P-glycoprotein substrates.

  17. No Identical "Mesenchymal Stem Cells" at Different Times and Sites: Human Committed Progenitors of Distinct Origin and Differentiation Potential Are Incorporated as Adventitial Cells in Microvessels.

    PubMed

    Sacchetti, Benedetto; Funari, Alessia; Remoli, Cristina; Giannicola, Giuseppe; Kogler, Gesine; Liedtke, Stefanie; Cossu, Giulio; Serafini, Marta; Sampaolesi, Maurilio; Tagliafico, Enrico; Tenedini, Elena; Saggio, Isabella; Robey, Pamela G; Riminucci, Mara; Bianco, Paolo

    2016-06-14

    A widely shared view reads that mesenchymal stem/stromal cells ("MSCs") are ubiquitous in human connective tissues, can be defined by a common in vitro phenotype, share a skeletogenic potential as assessed by in vitro differentiation assays, and coincide with ubiquitous pericytes. Using stringent in vivo differentiation assays and transcriptome analysis, we show that human cell populations from different anatomical sources, regarded as "MSCs" based on these criteria and assumptions, actually differ widely in their transcriptomic signature and in vivo differentiation potential. In contrast, they share the capacity to guide the assembly of functional microvessels in vivo, regardless of their anatomical source, or in situ identity as perivascular or circulating cells. This analysis reveals that muscle pericytes, which are not spontaneously osteochondrogenic as previously claimed, may indeed coincide with an ectopic perivascular subset of committed myogenic cells similar to satellite cells. Cord blood-derived stromal cells, on the other hand, display the unique capacity to form cartilage in vivo spontaneously, in addition to an assayable osteogenic capacity. These data suggest the need to revise current misconceptions on the origin and function of so-called "MSCs," with important applicative implications. The data also support the view that rather than a uniform class of "MSCs," different mesoderm derivatives include distinct classes of tissue-specific committed progenitors, possibly of different developmental origin. PMID:27304917

  18. Recurrence and death in non-small cell lung carcinomas: a prognostic model using pathological parameters, microvessel count, and gene protein products.

    PubMed

    Fontanini, G; Vignati, S; Bigini, D; Mussi, A; Lucchi, M; Chiné, S; Angeletti, C A; Bevilacqua, G

    1996-06-01

    The 5-year survival rate of non-small cell lung carcinoma (NSCLC) has only marginally improved during the past two decades, despite advances in surgery and chemoradiotherapy. Major efforts are currently directed toward biological characterization of these tumors to define biomarkers able to add further prognostic information, thus improving new therapeutic protocols. We analyzed the predictive relevance of the microvessel count (MC), bcl-2 and p53 proteins, proliferative activity, and usual postsurgical parameters on recurrence and overall survival in a series of 70 patients with NSCLC. The expression of biological parameters (p53, bcl-2, proliferative activity, and MC) was detected using immunohistochemistry on paraffin-embedded and frozen sections from the tumors treated with surgical resection alone until relapse. In the univariate analysis, the histotype, tumor status, node status, p53, bcl-2, and MC have been shown to significantly affect progression and death. In the multiple logistic regression analysis, the MC (P < 0.000001), tumor status (P < 0.005), and node status (P < 0.0002) influenced the overall survival while prediction of relapse was strongly revealed by tumor status (P < 0.005), nodal metastatic involvement (P < 0.000001), and the assessment of the vascular count (P < 0.0004). These data have allowed the creation of a multivariate model which may add more information on risk of recurrence and death in patients with NSCLC and can form the basis for future randomized clinical trials.

  19. Modelling ionospheric density structures

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.; Sojka, J. J.

    1989-01-01

    Large-scale density structures are a common feature in the high-latitude ionsphere. The structures were observed in the dayside cusp, polar cap, and nocturnal auroral region over a range of altitudes, including the E-region, F-region and topside ionosphere. The origins, lifetimes and transport characteristics of large-scale density structures were studied with the aid of a three-dimensional, time-dependent ionospheric model. Blob creation due to particle precipitation, the effect that structured electric fields have on the ionosphere, and the lifetimes and transport characteristics of density structures for different seasonal, solar cycle, and interplanetary magnetic field (IMF) conditions were studied. The main conclusions drawn are: (1) the observed precipitation energy fluxes are sufficient for blob creation if the plasma is exposed to the precipitation for 5 to 10 minutes; (2) structured electric fields produce structured electron densities, ion temperatures, and ion composition; (3) the lifetime of an F-region density structure depends on several factors, including the initial location where it was formed, the magnitude of the perturbation, season, solar cycle and IMF; and (4) depending on the IMF, horizontal plasma convection can cause an initial structure to break up into multiple structures of various sizes, remain as a single distorted structure, or become stretched into elongated segments.

  20. Anatomic Distribution of Nerves and Microvascular Density in the Human Anterior Vaginal Wall: Prospective Study

    PubMed Central

    Li, Ting; Liao, Qinping; Zhang, Hong; Gao, Xuelian; Li, Xueying; Zhang, Miao

    2014-01-01

    Background The presence of the G-spot (an assumed erotic sensitive area in the anterior wall of the vagina) remains controversial. We explored the histomorphological basis of the G-spot. Methods Biopsies were drawn from a 12 o’clock direction in the distal- and proximal-third areas of the anterior vagina of 32 Chinese subjects. The total number of protein gene product 9.5–immunoreactive nerves and smooth muscle actin–immunoreactive blood vessels in each specimen was quantified using the avidin-biotin-peroxidase assay. Results Vaginal innervation was observed in the lamina propria and muscle layer of the anterior vaginal wall. The distal-third of the anterior vaginal wall had significantly richer small-nerve-fiber innervation in the lamina propria than the proximal-third (p = 0.000) and in the vaginal muscle layer (p = 0.006). There were abundant microvessels in the lamina propria and muscle layer, but no small vessels in the lamina propria and few in the muscle layer. Significant differences were noted in the number of microvessels when comparing the distal- with proximal-third parts in the lamina propria (p = 0.046) and muscle layer (p = 0.002). Conclusions Significantly increased density of nerves and microvessels in the distal-third of the anterior vaginal wall could be the histomorphological basis of the G-spot. Distal anterior vaginal repair could disrupt the normal anatomy, neurovascular supply and function of the G-spot, and cause sexual dysfunction. PMID:25379731

  1. SCB initiator

    DOEpatents

    Bickes, Jr., Robert W.; Renlund, Anita M.; Stanton, Philip L.

    1994-01-01

    A detonator for high explosives initiated by mechanical impact includes a cylindrical barrel, a layer of flyer material mechanically covering the barrel at one end, and a semiconductor bridge ignitor including a pair of electrically conductive pads connected by a semiconductor bridge. The bridge is in operational contact with the layer, whereby ignition of said bridge forces a portion of the layer through the barrel to detonate the explosive. Input means are provided for igniting the semiconductor bridge ignitor.

  2. SCB initiator

    DOEpatents

    Bickes Jr., Robert W.; Renlund, Anita M.; Stanton, Philip L.

    1994-11-01

    A detonator for high explosives initiated by mechanical impact includes a cylindrical barrel, a layer of flyer material mechanically covering the barrel at one end, and a semiconductor bridge ignitor including a pair of electrically conductive pads connected by a semiconductor bridge. The bridge is in operational contact with the layer, whereby ignition of said bridge forces a portion of the layer through the barrel to detonate the explosive. Input means are provided for igniting the semiconductor bridge ignitor.

  3. Environmental initiatives

    SciTech Connect

    James, R.C. Jr.

    1991-11-01

    J I Case, a leading worldwide maker of agricultural and construction equipment based in Racine, Wisconsin, is taking an aggressive and responsible approach to environmental issues. From integrated solid waste handling plans and Freon recovery initiatives, to special employee training programs and voluntary participation in the EPA's Industrial Toxics Program, Case is addressing environmental issues at its facilities and in its products. One of the key environmental initiatives at Case is the company's voluntary participation in the US EPA's Industrial Toxics Program, also known as the 33/50 Program. This program is an EPA pollution prevention initiative started in 1990 that is designed to reduce industrial toxics generation quickly through voluntary actions by industry. The program derives its name from the EPA's national reduction goals for 17 high priority toxic pollutants - 33 percent reduction by 1992 and 50 percent by 1995. As a result, the Pryor Foundry has slashed its emissions of industrial toxic pollutants by 98 percent, from over 350,000 pounds (159 metric tons) in 1988 to around 5,000 pounds (2.27 metric tons) in 1991, with a projected reduction to only 750 pounds (340 kilograms) by 1995.

  4. Optimization of low-frequency low-intensity ultrasound-mediated microvessel disruption on prostate cancer xenografts in nude mice using an orthogonal experimental design

    PubMed Central

    YANG, YU; BAI, WENKUN; CHEN, YINI; LIN, YANDUAN; HU, BING

    2015-01-01

    The present study aimed to provide a complete exploration of the effect of sound intensity, frequency, duty cycle, microbubble volume and irradiation time on low-frequency low-intensity ultrasound (US)-mediated microvessel disruption, and to identify an optimal combination of the five factors that maximize the blockage effect. An orthogonal experimental design approach was used. Enhanced US imaging and acoustic quantification were performed to assess tumor blood perfusion. In the confirmatory test, in addition to acoustic quantification, the specimens of the tumor were stained with hematoxylin and eosin and observed using light microscopy. The results revealed that sound intensity, frequency, duty cycle, microbubble volume and irradiation time had a significant effect on the average peak intensity (API). The extent of the impact of the variables on the API was in the following order: Sound intensity; frequency; duty cycle; microbubble volume; and irradiation time. The optimum conditions were found to be as follows: Sound intensity, 1.00 W/cm2; frequency, 20 Hz; duty cycle, 40%; microbubble volume, 0.20 ml; and irradiation time, 3 min. In the confirmatory test, the API was 19.97±2.66 immediately subsequent to treatment, and histological examination revealed signs of tumor blood vessel injury in the optimum parameter combination group. In conclusion, the Taguchi L18 (3)6 orthogonal array design was successfully applied for determining the optimal parameter combination of API following treatment. Under the optimum orthogonal design condition, a minimum API of 19.97±2.66 subsequent to low-frequency and low-intensity mediated blood perfusion blockage was obtained. PMID:26722279

  5. Methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxypyrovalerone (MDPV) induce differential cytotoxic effects in bovine brain microvessel endothelial cells.

    PubMed

    Rosas-Hernandez, Hector; Cuevas, Elvis; Lantz, Susan M; Rice, Kenner C; Gannon, Brenda M; Fantegrossi, William E; Gonzalez, Carmen; Paule, Merle G; Ali, Syed F

    2016-08-26

    Designer drugs such as synthetic psychostimulants are indicative of a worldwide problem of drug abuse and addiction. In addition to methamphetamine (METH), these drugs include 3,4-methylenedioxy-methamphetamine (MDMA) and commercial preparations of synthetic cathinones including 3,4-methylenedioxypyrovalerone (MDPV), typically referred to as "bath salts." These psychostimulants exert neurotoxic effects by altering monoamine systems in the brain. Additionally, METH and MDMA adversely affect the integrity of the blood-brain barrier (BBB): there are no current reports on the effects of MDPV on the BBB. The aim of this study was to compare the effects of METH, MDMA and MDPV on bovine brain microvessel endothelial cells (bBMVECs), an accepted in vitro model of the BBB. Confluent bBMVEC monolayers were treated with METH, MDMA and MDPV (0.5mM-2.5mM) for 24h. METH and MDMA increased lactate dehydrogenase release only at the highest concentration (2.5mM), whereas MDPV induced cytotoxicity at all concentrations. MDMA and METH decreased cellular proliferation only at 2.5mM, with similar effects observed after MDPV exposures starting at 1mM. Only MDPV increased reactive oxygen species production at all concentrations tested whereas all 3 drugs increased nitric oxide production. Morphological analysis revealed different patterns of compound-induced cell damage. METH induced vacuole formation at 1mM and disruption of the monolayer at 2.5mM. MDMA induced disruption of the endothelial monolayer from 1mM without vacuolization. On the other hand, MDPV induced monolayer disruption at doses ≥0.5mM without vacuole formation; at 2.5mM, the few remaining cells lacked endothelial morphology. These data suggest that even though these synthetic psychostimulants alter monoaminergic systems, they each induce BBB toxicity by different mechanisms with MDPV being the most toxic. PMID:27320055

  6. Recombinant interleukin-1β dilates steelhead trout coronary microvessels: effect of temperature and role of the endothelium, nitric oxide and prostaglandins

    PubMed Central

    Costa, Isabel A. S. F.; Hein, Travis W.; Secombes, Christopher J.; Gamperl, A. Kurt

    2015-01-01

    ABSTRACT Interleukin (IL)-1β is associated with hypotension and cardiovascular collapse in mammals during heat stroke, and the mRNA expression of this pro-inflammatory cytokine increases dramatically in the blood of Atlantic cod (Gadus morhua) at high temperatures. These data suggest that release of IL-1β at high temperatures negatively impacts fish cardiovascular function and could be a primary determinant of upper thermal tolerance in this taxa. Thus, we measured the concentration-dependent response of isolated steelhead trout (Oncorhynchus mykiss) coronary microvessels (<150 μm in diameter) to recombinant (r) IL-1β at two temperatures (10 and 20°C). Recombinant IL-1β induced a concentration-dependent vasodilation with vessel diameter increasing by approximately 8 and 30% at 10−8 and 10−7 mol l−1, respectively. However, this effect was not temperature dependent. Both vessel denudation and cyclooxygenase blockade (by indomethacin), but not the nitric oxide (NO) antagonist L-NIO, inhibited the vasodilator effect of rIL-1β. In contrast, the concentration-dependent dilation caused by the endothelium-dependent calcium ionophore A23187 was completely abolished by L-NIO and indomethacin, suggesting that both NO and prostaglandin signaling mechanisms exist in the trout coronary microvasculature. These data: (1) are the first to demonstrate a functional link between the immune and cardiovascular systems in fishes; (2) suggest that IL-1β release at high temperatures may reduce systemic vascular resistance, and thus, the capacity of fish to maintain blood pressure; and (3) provide evidence that both NO and prostaglandins play a role in regulating coronary vascular tone, and thus, blood flow. PMID:26026045

  7. Nanomolar aluminum induces expression of the inflammatory systemic biomarker C-reactive protein (CRP) in human brain microvessel endothelial cells (hBMECs).

    PubMed

    Alexandrov, Peter N; Kruck, Theodore P A; Lukiw, Walter J

    2015-11-01

    C-reactive protein (CRP; also known as pentraxin 1, PTX1), a 224 amino acid soluble serum protein organized into a novel pentameric ring-shaped structure, is a highly sensitive pathogenic biomarker for systemic inflammation. High CRP levels are found in practically every known inflammatory state, and elevated CRP levels indicate an increased risk for several common age-related human degenerative disorders, including cardiovascular disease, cancer, diabetes, and Alzheimer's disease (AD). While the majority of CRP is synthesized in the liver for secretion into the systemic circulation, it has recently been discovered that an appreciable amount of CRP is synthesized in highly specialized endothelial cells that line the vasculature of the brain and central nervous system (CNS). These highly specialized cells, the major cell type lining the human CNS vasculature, are known as human brain microvessel endothelial cells (hBMECs). In the current pilot study we examined (i) CRP levels in human serum obtained from AD and age-matched control patients; and (ii) analyzed the effects of nanomolar aluminum sulfate on CRP expression in primary hBMECs. The three major findings in this short communication are: (i) that CRP is up-regulated in AD serum; (ii) that CRP serum levels increased in parallel with AD progression; and (iii) for the first time show that nanomolar aluminum potently up-regulates CRP expression in hBMECs to many times its 'basal abundance'. The results suggest that aluminum-induced CRP may in part contribute to a pathophysiological state associated with a chronic systemic inflammation of the human vasculature.

  8. The relationship between microvessel count and the expression of vascular endothelial growth factor, p53, and K-ras in non-small cell lung cancer.

    PubMed Central

    Kang, Y. H.; Kim, K. S.; Yu, Y. K.; Lim, S. C.; Kim, Y. C.; Park, K. O.

    2001-01-01

    Using immunohistochemical staining, we studied the relationship between the microvessel count (MC) and the expression of K-ras, mutant p53 protein, and vascular endothelial growth factor (VEGF) in 61 surgically resected non-small cell lung cancers (NSCLC) (42 squamous cell carcinoma, 14 adenocarcinoma, 2 large cell carcinoma, 2 adenosquamous carcinoma, and 1 mucoepidermoid carcinoma). MC of the tumors with lymph node (LN) metastasis was significantly higher than that of tumors without LN metastasis (66.1+/-23.1 vs. 33.8+/-13.1, p<0.05). VEGF was positive in 54 patients (88.5%). MC was 58.1+/-25.2 (mean+/-S.D.) in a x200 field, and it was significantly higher in VEGF(+) tumors than in VEGF(-) tumors (61.4+/-23.7 vs. 32.9+/-23.8, p<0.05). VEGF expression was higher in K-ras-positive or mutant p53-positive tumors than in negative tumors (p<0.05). MC was significantly higher in K-ras(+) tumors than in K-ras(-) tumors, although it did not differ according to the level of mutant p53 protein expression. Survival did not differ with VEGF, mutant p53, or K-ras expression, or the level of MC. In conclusion, there is a flow of molecular alterations from K-ras and p53, to VEGF expression, leading to angiogenesis and ultimately lymph node metastasis. Correlations between variables in close approximation and the lack of prognostic significance of individual molecular alterations suggest that tumorigenesis and metastasis are multifactorial processes. PMID:11511786

  9. Methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxypyrovalerone (MDPV) induce differential cytotoxic effects in bovine brain microvessel endothelial cells.

    PubMed

    Rosas-Hernandez, Hector; Cuevas, Elvis; Lantz, Susan M; Rice, Kenner C; Gannon, Brenda M; Fantegrossi, William E; Gonzalez, Carmen; Paule, Merle G; Ali, Syed F

    2016-08-26

    Designer drugs such as synthetic psychostimulants are indicative of a worldwide problem of drug abuse and addiction. In addition to methamphetamine (METH), these drugs include 3,4-methylenedioxy-methamphetamine (MDMA) and commercial preparations of synthetic cathinones including 3,4-methylenedioxypyrovalerone (MDPV), typically referred to as "bath salts." These psychostimulants exert neurotoxic effects by altering monoamine systems in the brain. Additionally, METH and MDMA adversely affect the integrity of the blood-brain barrier (BBB): there are no current reports on the effects of MDPV on the BBB. The aim of this study was to compare the effects of METH, MDMA and MDPV on bovine brain microvessel endothelial cells (bBMVECs), an accepted in vitro model of the BBB. Confluent bBMVEC monolayers were treated with METH, MDMA and MDPV (0.5mM-2.5mM) for 24h. METH and MDMA increased lactate dehydrogenase release only at the highest concentration (2.5mM), whereas MDPV induced cytotoxicity at all concentrations. MDMA and METH decreased cellular proliferation only at 2.5mM, with similar effects observed after MDPV exposures starting at 1mM. Only MDPV increased reactive oxygen species production at all concentrations tested whereas all 3 drugs increased nitric oxide production. Morphological analysis revealed different patterns of compound-induced cell damage. METH induced vacuole formation at 1mM and disruption of the monolayer at 2.5mM. MDMA induced disruption of the endothelial monolayer from 1mM without vacuolization. On the other hand, MDPV induced monolayer disruption at doses ≥0.5mM without vacuole formation; at 2.5mM, the few remaining cells lacked endothelial morphology. These data suggest that even though these synthetic psychostimulants alter monoaminergic systems, they each induce BBB toxicity by different mechanisms with MDPV being the most toxic.

  10. Decreased expression of organic cation transporters, Oct1 and Oct2, in brain microvessels and its implication to MPTP-induced dopaminergic toxicity in aged mice.

    PubMed

    Wu, Kuo-Chen; Lu, Ya-Hsuan; Peng, Yi-Hsuan; Tsai, Ting-Fen; Kao, Yu-Han; Yang, Hui-Ting; Lin, Chun-Jung

    2015-01-01

    This study was to investigate the influence of age on the expression of organic cation transporters (OCTs) that belong to the SLC22 family in brain microvessels (BMVs) and its implications for 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic toxicity in mice. Here, we showed that Oct1 and Oct2, but not Oct3, mRNAs were detected and enriched (compared with cerebral cortex) in BMVs of C57BL/6 (B6) mice using reverse transcription-quantitative PCR (RT-qPCR), and immunofluorescence analysis further revealed that Oct1 and Oct2 proteins were colocalized with endothelial markers. Both the mRNA and protein levels of Oct1 and Oct2 were reduced in aged mice. After an intraperitoneal administration of MPTP, brain extracellular levels of MPTP and 1-methyl-4-phenyl-pyridinium (MPP(+)) were much lower in aged mice and in Oct1/2(-/-) mice compared with younger mice and wild-type control mice, respectively. Knockout of Oct1/Oct2 protected Oct1/2(-/-) mice from MPTP-induced neurotoxicity, whereas the loss of tyrosine hydroxylase (TH)-positive neurons was slightly greater in aged than in younger mice. However, intrastriatal infusion of low-dose MPTP caused more severe dopaminergic toxicity in the substantia nigra of both aged mice and Oct1/2(-/-) mice. These findings show that age-dependent downregulation or knockout of Oct1/Oct2 in BMVs may reduce the transport of MPTP, which, in part, affects its dopaminergic toxicity. PMID:25248837

  11. Openness initiative

    SciTech Connect

    Duncan, S.S.

    1995-12-31

    Although antinuclear campaigns seem to be effective, public communication and education efforts on low-level radioactive waste have mixed results. Attempts at public information programs on low-level radioactive waste still focus on influencing public opinion. A question then is: {open_quotes}Is it preferable to have a program focus on public education that will empower individuals to make informed decisions rather than trying to influence them in their decisions?{close_quotes} To address this question, a case study with both quantitative and qualitative data will be used. The Ohio Low-Level Radioactive Waste Education Program has a goal to provide people with information they want/need to make their own decisions. The program initiated its efforts by conducting a statewide survey to determine information needed by people and where they turned for that information. This presentation reports data from the survey and then explores the program development process in which programs were designed and presented using the information. Pre and post data from the programs reveal attitude and knowledge shifts.

  12. Stereoselective Regulation of P-gp Activity by Clausenamide Enantiomers in Caco-2, KB/KBv and Brain Microvessel Endothelial Cells

    PubMed Central

    Zhu, Chuan-jiang; Hua, Fang; Zhu, Xiao-lu; Li, Meng; Wang, Hong-xu; Yu, Xiao-ming; Li, Yan

    2015-01-01

    The (−)- and (+)-clausenamide (CLA) enantiomers have different pharmacokinetic effects in animals, but their association with putative stereoselective regulation of P-glycoprotein (P-gp) remains unclear. Using three cells expressing P-gp—Caco-2, KBv and rat brain microvessel endothelial cells(RBMEC), this study investigated the association of CLA enantiomers with P-gp. The results showed that the rhodamine 123 (Rh123) accumulation, an indicator of P-gp activity, in Caco-2, KBv and RBMECs was increased by (−)CLA (1 or 5 μmol/L) at 8.2%–28.5%, but reduced by (+)CLA at 11.7%–25.9%, showing stereoselectivity in their regulation of P-gp activity. Following co-treatment of these cells with each CLA enantiomer and verapamil as a P-gp inhibitor, the (+)-isomer clearly antagonized the inhibitory effects of verapamil on P-gp efflux, whereas the (−)-isomer had slightly synergistic or additive effects. When higher concentrations (5 or 10 μmol/L) of CLA enantiomers were added, the stimulatory effects of the (+)-isomer were converted into inhibitory ones, leading to an enhanced intracellular uptake of Rh123 by 24.5%–58.2%; but (−)-isomer kept its inhibition to P-gp activity, causing 30.0%–63.0% increase in the Rh123 uptake. The biphasic effects of (+)CLA were confirmed by CLA uptake in the Caco-2 cells. (+)CLA at 1 μmol/L had significantly lower intracellular uptake than (−)CLA with a ratio[(−)/(+)] of 2.593, which was decreased to 2.167 and 1.893 after CLA concentrations increased to 2.5 and 5 μmol/L. Besides, in the non-induced KB cells, (+)CLA(5 μmol/L) upregulated P-gp expression at 54.5% relative to vehicle control, and decreased Rh123 accumulation by 28.2%, while (−)CLA(5 μmol/L) downregulated P-gp expression at 15.9% and increased Rh123 accumulation by 18.0%. These results suggested that (−)CLA could be a P-gp inhibitor and (+)CLA could be a modulator with concentration-dependent biphasic effects on P-gp activity, which may result in drug

  13. The initiation of free radical peroxidation of low-density lipoproteins by glucose and its metabolite methylglyoxal: a common molecular mechanism of vascular wall injure in atherosclerosis and diabetes.

    PubMed

    Lankin, Vadim; Konovalova, Galina; Tikhaze, Alla; Shumaev, Konstantin; Kumskova, Elena; Viigimaa, Margus

    2014-10-01

    It was found that glucose in the range of concentrations 12.5-100 mM stimulated Cu(2+)-mediated free radical peroxidation of low-density lipoproteins (LDL) from human blood plasma. Considering the kinetic parameters of LDL peroxidation we proposed that intensification of this process may be caused by formation of free radical intermediates of glucose auto-oxidation. Addition of SOD to the medium inhibited LDL oxidation, indicating the formation of superoxide anion-radicals under autoxidation of glucose. Similarly, SOD inhibited free radical peroxidation of liposomes from egg lecithin in the presence of glucose that confirms the generation of superoxide radicals under co-oxidation of unsaturated lipids and glucose. Normalization of glucose level in the blood of patients with type 2 diabetes mellitus during therapy was accompanied by a significant decrease in LDL oxidation in vivo (the decrease in primary and secondary lipoperoxidation products). The formation of superoxide anion-radicals was observed during interaction of aminoacid L-lysine with a product of glucose oxidative metabolism-methylglyoxal, but not with a product of lipoperoxidation malonyldialdehyde. In accordance with the foregoing the administration of sugar-lowering drug metformin, which binds and utilizes methylglyoxal, caused a stronger inhibition of LDL peroxidation in the blood of patients with diabetes mellitus, probably due to decrease in methylglyoxal-dependent generation of superoxide anion-radicals. Based on the results we set out the hypothesis about autocatalytic mechanism of free radical reactions involving natural dicarbonyls and suppose the common molecular mechanism of vascular wall injury in atherosclerosis and diabetes. PMID:24997046

  14. Degenerate density perturbation theory

    NASA Astrophysics Data System (ADS)

    Palenik, Mark C.; Dunlap, Brett I.

    2016-09-01

    Fractional occupation numbers can be used in density functional theory to create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate eigenvalues. We develop the corresponding perturbation theory and apply it to a system of Nd degenerate electrons in a harmonic oscillator potential. The order-by-order expansions of both the fractional occupation numbers and unitary transformations within the degenerate subspace are determined by the requirement that a differentiable map exists connecting the initial and perturbed states. Using the X α exchange-correlation (XC) functional, we find an analytic solution for the first-order density and first- through third-order energies as a function of α , with and without a self-interaction correction. The fact that the XC Hessian is not positive definite plays an important role in the behavior of the occupation numbers.

  15. EUROANDRILL Initiative

    NASA Astrophysics Data System (ADS)

    Florindo, Fabio; Steering Committee, Euroandrill

    2010-05-01

    EuroANDRILL is a new initiative to create a European network with the goal to increase future involvement of European countries in the ANDRILL [ANtarctic geological DRILLing] Programme. Antarctica has been heavily glaciated for approximately 34 million years, but its ice sheets have fluctuated considerably and are one of the major driving forces for changes in climate throughout the Cenozoic Era. The spatial scale and temporal pattern of these fluctuations is subject to considerable debate. Understanding the response of large ice masses to climatic forcing is of vital importance because ice volume variations drive global sea level changes and also alter the capacity of ice sheets and sea-ice to act as major heat sinks/insulators. It is particularly important to assess the stability of the cryosphere in the face of rising CO2 levels, as modelling of the climate shift from a warm, vegetated Antarctica to a cold, ice-covered state 34 million years ago suggests a powerful greenhouse gas influence. As Antarctica is the major driver of Earth's climate and sea level, much effort has been expended in deriving models of its behaviour. Some of these models have been successfully validated against modern conditions. EuroANDRILL will provide a coherent, integrated platform for European leadership and involvement in the international ANDRILL programme. The coordination and networking provided by EuroANDRILL will seek to expand participation by European nations, institutions, and individual scientists in the study of the geologic history of the polar regions and their paleoclimatic significance. During the IPY, ANDRILL has been a highly visible and successful programme. This programme seeks to expand on this legacy beyond the IPY and make these contributions sustainable in the European Research Area through networking of research projects and future planning efforts, which establish Europe as a key player in future polar sediment and rock drilling. EuroANDRILL is set up under

  16. Microdrill Initiative - Initial Market Evaluation

    SciTech Connect

    Spears & Associates, Inc

    2003-07-01

    The U.S. Department of Energy (DOE) is launching a major research and development initiative to create a small, fast, inexpensive and environmentally friendly rig for drilling 5000 feet boreholes to investigate potential oil and gas reservoirs. DOE wishes to get input from petroleum industry operators, service companies and equipment suppliers on the operation and application of this coiled-tubing-based drilling unit. To that end, DOE has asked Spears & Associates, Inc. (SAI) to prepare a special state-of-the-market report and assist during a DOE-sponsored project-scoping workshop in Albuquerque near the end of April 2003. The scope of the project is four-fold: (1) Evaluate the history, status and future of demand for very small bore-hole drilling; (2) Measure the market for coiled tubing drilling and describe the state-of-the-art; (3) Identify companies and individuals who should have an interest in micro drilling and invite them to the DOE workshop; and (4) Participate in 3 concurrent workshop sessions, record and evaluate participant comments and report workshop conclusions.

  17. GALIC: Galaxy initial conditions construction

    NASA Astrophysics Data System (ADS)

    Yurin, Denis; Springel, Volker

    2014-08-01

    GalIC (GALaxy Initial Conditions) is an implementation of an iterative method to construct steady state composite halo-disk-bulge galaxy models with prescribed density distribution and velocity anisotropy that can be used as initial conditions for N-body simulations. The code is parallelized for distributed memory based on MPI. While running, GalIC produces "snapshot files" that can be used as initial conditions files. GalIC supports the three file formats ('type1' format, the slightly improved 'type2' format, and an HDF5 format) of the GADGET (ascl:0003.001) code for its output snapshot files.

  18. The dynamics of variable-density turbulence

    SciTech Connect

    Sandoval, D.L.

    1995-11-01

    The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field, is in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations. In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For the case of buoyancy-generated turbulence, variable-density departures from the Boussinesq approximation are studied. The results of the buoyancy-generated turbulence are compared with variable-density model predictions. Both a one-point (engineering) model and a two-point (spectral) model are tested against the numerical data. Some deficiencies in these variable-density models are discussed and modifications are suggested.

  19. The dynamics of variable-density turbulence

    SciTech Connect

    Sandoval, D.L.

    1995-11-01

    The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field is, in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations (such that the Boussinesq approximation is not valid). In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For this case, the pdf of the density becomes asymmetric about its mean value during the early stages of its evolution. It is argued that these asymmetries in the pdf of the density field are due to different entrainment rates, into the mixing region, that favor the high speed fluid.

  20. Evaluation of epidermal growth factor-related growth factors and receptors and of neoangiogenesis in completely resected stage I-IIIA non-small-cell lung cancer: amphiregulin and microvessel count are independent prognostic indicators of survival.

    PubMed

    Fontanini, G; De Laurentiis, M; Vignati, S; Chinè, S; Lucchi, M; Silvestri, V; Mussi, A; De Placido, S; Tortora, G; Bianco, A R; Gullick, W; Angeletti, C A; Bevilacqua, G; Ciardiello, F

    1998-01-01

    We have determined the expression of transforming growth factor alpha (TGF alpha), amphiregulin (AR), CRIPTO, the epidermal growth factor receptor (EGFR), erbB-2, erbB-3, and tumor angiogenesis in a series of 195 patients with stage I-IIIA non-small cell lung cancer (NSCLC) treated with radical surgery to define their usefulness as prognostic indicators of survival. A variable degree of specific staining in cancer cells was observed for the three growth factors and for the three growth factor receptors in the majority of NSCLC patients. A statistically significant association between overexpression of TGF alpha, AR, and CRIPTO was observed. Enhanced expression of AR was significantly correlated with enhanced expression of erbB-2 and advanced T-stage. A direct association was also detected for overexpression of TGF alpha and of erbB-2 or erbB-3, respectively. Sex, tumor size, nodal status, stage, microvessel count, as a measure of neovascularization, and AR overexpression significantly correlated with overall survival at univariate analysis. In a Cox multivariate analysis, the only characteristics with an independent prognostic effect on OAS were microvessel count [relative hazard (RH), 6.61; P < 0.00001), nodal status (RH, 1.59; P = 0.0013), and AR overexpression (RH, 1.72; P = 0.02). These results suggest that evaluation of neoangiogenesis and of certain growth factors, such as AR, can be useful in addition to conventional pathological staging to select high-risk NSCLC patients who may benefit from post-surgical systemic therapies.

  1. Significance of microvascular density (MVD) in cervical cancer recurrence.

    PubMed

    Cantu De León, D; Lopez-Graniel, C; Frias Mendivil, M; Chanona Vilchis, G; Gomez, C; De La Garza Salazar, J

    2003-01-01

    The purpose of this retrospective study of 118 patients with squamous cell cervical cancer from January 1990 to December 1993 was to evaluate angiogenesis as predictive factor of recurrence in cervical cancer stages II-III treated with standard radiotherapy. Microvessel density (MVD) was evaluated and correlated with other prognostic factors. MVD was greater than 20 in 67.8% of patients with recurrence (P = 0.002) in comparison to 39% of patients without. Disease-free survival was shorter in stage IIA and MVD >20 (P = 0.0193) as well as for stage IIB (P < 0.05 ), but not for IIIB (P = 0.1613 ). Global survival was significantly shorter when MVD was >20 (P = 0.0316). For stage IIA and MVD >20 survival was shorter (P = 0.0008) for stage IIB (P < 0.05) but not for IIIB (P = 0.14). Patients younger than 40 years and MVD >20 had poorer disease-free interval and survival (P = 0.0029). MVD in patients with squamous cell cervical cancer stage II and age younger than 40 may play a role in predicting recurrence and survival. PMID:14675324

  2. Direct laser initiation of PETN

    SciTech Connect

    Early, J. W.; Kennedy, J. E.

    2001-01-01

    In the early 1970s Yang and Menichelli demonstrated that direct laser illumination of low-density secondary explosive prr:ssings through a transparent window could produce detonation. 'The energy requirement for threshold initiation of detonation was reduced when a thin metal coating of metal covered the side of the window against which the low-density explosive was pressed. We have obtained experimental results that are in general agreement with the results of Renllund, Stanton and Trott (1 989) and recent: work by Nagayama, hou and Nakahara (2001). We report exploration of the effects of laser beam diameter, PEiTN density and specific surface area, and thickness of a titanium coating on the window.

  3. TFTR initial operations

    SciTech Connect

    Young, K.M.; Bell, M.; Blanchard, W.R.; Bretz, N.; Cecchi, J.; Coonrod, J.; Davis, S.; Dylla, H.F.; Efthimion, P.C.; Fonck, R.

    1983-11-01

    The Tokamak Fusion Test Reactor (TFTR) has operated since December 1982 with ohmically heated plasmas. Routine operation with feedback control of plasma current, position, and density has been obtained for plasmas with I/sub p/ approx. = 800 kA, a = 68 cm, R = 250 cm, and B/sub t/ = 27 kG. A maximum plasma current of 1 MA was achieved with q approx. = 2.5. Energy confinement times of approx. 150 msec were measured for hydrogen and deuterium plasmas with anti n/sub e/ approx. = 2 x 10/sup 13/ cm/sup -3/, T/sub e/ (0) approx. = 1.5 keV, T/sub i/ (0) approx. = 1.5 keV, and Z/sub eff/ approx. = 3. The preliminary results suggest a size-cubed scaling from PLT and are consistent with Alcator C scaling where tau approx. nR/sup 2/a. Initial measurements of plasma disruption characteristics indicate current decay rates of approx. 800 kA in 8 ms which is within the TFTR design requirement of 3 MA in 3 ms.

  4. Density perturbation theory

    SciTech Connect

    Palenik, Mark C.; Dunlap, Brett I.

    2015-07-28

    Despite the fundamental importance of electron density in density functional theory, perturbations are still usually dealt with using Hartree-Fock-like orbital equations known as coupled-perturbed Kohn-Sham (CPKS). As an alternative, we develop a perturbation theory that solves for the perturbed density directly, removing the need for CPKS. This replaces CPKS with a true Hohenberg-Kohn density perturbation theory. In CPKS, the perturbed density is found in the basis of products of occupied and virtual orbitals, which becomes ever more over-complete as the size of the orbital basis set increases. In our method, the perturbation to the density is expanded in terms of a series of density basis functions and found directly. It is possible to solve for the density in such a way that it makes the total energy stationary even if the density basis is incomplete.

  5. Initialized Fractional Calculus

    NASA Technical Reports Server (NTRS)

    Lorenzo, Carl F.; Hartley, Tom T.

    2000-01-01

    This paper demonstrates the need for a nonconstant initialization for the fractional calculus and establishes a basic definition set for the initialized fractional differintegral. This definition set allows the formalization of an initialized fractional calculus. Two basis calculi are considered; the Riemann-Liouville and the Grunwald fractional calculi. Two forms of initialization, terminal and side are developed.

  6. A Dastardly Density Deed.

    ERIC Educational Resources Information Center

    Shaw, Mike

    2003-01-01

    Integrates story telling into a science activity on the density of liquids in order to increase student interest. Shows the relationship between mass and volume ratio and how they determine density. Includes teacher notes. (YDS)

  7. Direct Density Derivative Estimation.

    PubMed

    Sasaki, Hiroaki; Noh, Yung-Kyun; Niu, Gang; Sugiyama, Masashi

    2016-06-01

    Estimating the derivatives of probability density functions is an essential step in statistical data analysis. A naive approach to estimate the derivatives is to first perform density estimation and then compute its derivatives. However, this approach can be unreliable because a good density estimator does not necessarily mean a good density derivative estimator. To cope with this problem, in this letter, we propose a novel method that directly estimates density derivatives without going through density estimation. The proposed method provides computationally efficient estimation for the derivatives of any order on multidimensional data with a hyperparameter tuning method and achieves the optimal parametric convergence rate. We further discuss an extension of the proposed method by applying regularized multitask learning and a general framework for density derivative estimation based on Bregman divergences. Applications of the proposed method to nonparametric Kullback-Leibler divergence approximation and bandwidth matrix selection in kernel density estimation are also explored. PMID:27140943

  8. The antithrombotic effect of potent bifunctional thrombin inhibitors based on hirudin sequence, P551 and P532, on He-Ne laser-induced thrombosis in rat mesenteric microvessels.

    PubMed

    Yamashita, T; Tsuda, Y; Konishi, Y; Okada, Y; Matsuoka, A; Giddings, J C; Yamamoto, J

    1998-06-01

    The antithrombotic effect of potent synthetic bifunctional non-substrate type thrombin inhibitors based on hirudin sequences, P551 and P532, on Helium-Neon laser-induced thrombosis was investigated in rat mesenteric microvessels and compared with other types of thrombin inhibitors. P551 and P532, when given intravenously, inhibited platelet-rich thrombus formation in both arterioles and venules in a dose-dependent manner. The inhibitory effect was maximal immediately after intravenous administration and persisted for 20-30 minutes in both arterioles and venules. The minimal effective doses of P551 and P532 were 1.0 mg/ kg (intravenously) in both. However, the time course of the antithrombotic effect was not in keeping with the inhibitory effect measured by an activated partial thromboplastin time and was similar to other types of inhibitors in spite of different half-lives. The current findings show that P551 and P532 had significant inhibitory effects on platelet-rich thrombus formation and suggest that these bifunctional thrombin inhibitors could be potent antithrombotic agents. PMID:9694241

  9. Density distributions in nuclei

    NASA Astrophysics Data System (ADS)

    Strutinsky, V. M.; Magner, A. G.; Denisov, V. Yu.

    1985-03-01

    Density distribution across the nuclear surface is obtained in the approximation of relatively sharp nuclear edge. It is used to determine dynamical parts of the density relevant to density vibration resonances. Results of the simple calculations are in close agreement with detailed microscopic theories.

  10. Crowding and Density

    ERIC Educational Resources Information Center

    Design and Environment, 1972

    1972-01-01

    Three-part report pinpointing problems and uncovering solutions for the dual concepts of density (ratio of people to space) and crowding (psychological response to density). Section one, A Primer on Crowding,'' reviews new psychological and social findings; section two, Density in the Suburbs,'' shows conflict between status quo and increased…

  11. The Concept of Density

    ERIC Educational Resources Information Center

    Hawkes, Stephen J.

    2004-01-01

    Students are aware of the theoretical or abstract concept of density, but fail to understand its practical implication in that the thickness concentrated in a solid object is what constitutes density. A study of the density concept reveals its very practical and qualitative nature, and the students must look beyond theoretical equations to…

  12. Incidentalomas: initial management.

    PubMed

    Hitzeman, Nathan; Cotton, Erin

    2014-12-01

    Incidentalomas are increasingly common findings on radiologic studies, causing worry for physicians and patients. Physicians should consider the risk of discovering incidentalomas when contemplating imaging. Patients may assume that incidentalomas are cancer, and may not be aware of the radiation risks associated with repeat imaging. Once incidentalomas are detected, appropriate management is dependent on an informed patient's wishes and the clinical situation. Guidelines are provided for the initial management of eight incidentalomas (pituitary, thyroid, pulmonary, hepatic, pancreatic, adrenal, renal, and ovarian). Patients presenting with pituitary incidentalomas should undergo pituitary-specific magnetic resonance imaging if the lesion is 1 cm or larger, or if it abuts the optic chiasm. Thyroid incidentalomas are ubiquitous, but nodules larger than 1 to 2 cm are of greater concern. Worrisome pulmonary incidentalomas are those larger than 8 mm or those with irregular borders, eccentric calcifications, or low density. However, current guidelines recommend that even pulmonary incidentalomas as small as 4 mm be followed. Solid hepatic incidentalomas 5 mm or larger should be monitored closely, and multiphasic scanning is helpful. Pancreatic cystic neoplasms have malignant potential, and surgery is recommended for pancreatic cysts larger than 3 cm with suspicious features. Adrenal lesions larger than 4 cm are usually biopsied. The Bosniak classification is a well-accepted means of triaging renal incidentalomas. Lesions at category IIF or greater require serial monitoring or surgery. Benign or probably benign ovarian cysts 3 cm or smaller in premenopausal women or 1 cm or smaller in postmenopausal women do not require follow-up. Ovarian cysts with thickened walls or septa, or solid components with blood flow, should be managed closely.

  13. Glennan Microsystems Initiative

    NASA Technical Reports Server (NTRS)

    Brillson, Leonard J.

    2002-01-01

    During the 2001-2002 award period, we performed research on Pt/Ti/bare 6H-SiC and bare 4H-SiC interfaces in order to identify their electronic properties as a function of surface preparation. The overall aim of this work is to optimize the electronic properties of metal contacts to SiC as well as the active SiC material itself as a function of surface preparation and subsequent processing. Initially, this work has involved identifying bare surface, subsurface, and metal induced gap states at the metal-SiC contact and correlating energies and densities of deep levels with Schottky barrier heights. We used low energy electron-excited nanoluminescence (LEEN) spectroscopy, X-ray photoemission spectroscopy (XPS), and Secondary Ion Mass Spectrometry (SIMS) in order to correlate electronic states and energy bands with chemical composition, bonding, and crystal structure. A major development has been the discovery of polytype transformations that occur in 4H-SiC under standard microelectronic process conditions used to fabricate SiC devices. Our results are consistent with the stacking fault generation, defect formation, and consequent degradation of SiC recently reported for state-of-the-art ABB commercial diodes under localized electrical stress. Our results highlight the importance of -optimizing process conditions and material properties - anneal times, temperatures and doping to control such structural changes within epitaxial SiC layers. Thus far, we have established threshold times and temperatures beyond which 4H-SiC exhibits 3C-SiC transformation bands for a subset of dopant concentrations and process conditions. On the basis of this temperature time behavior, we have been able to establish an activation energy of approximately 2.5 eV for polytype transformation and dislocation motion. Work continues to establish the fundamental mechanisms underlying the polytype changes and its dependence on material parameters.

  14. Densities of Galcatic Center Clouds

    NASA Astrophysics Data System (ADS)

    Barnes, Jonathan; Mills, Elisabeth A. C.; Morris, Mark

    2015-01-01

    The central 300 parsecs of the Galaxy is full of giant molecular clouds containing 107 solar masses worth of gas. However, our Galactic center is not forming as many stars as we think it can, based on the amount of molecular gas in this region. By studying the densities of the Galactic center clouds we hope to better understand why there is not much star formation occurring. Using data from the Green Bank and MOPRA telescopes we have observed multiple rotation transitions of HC3N and its 13C isotopologues. By measuring the integrated intensity of the HC3N we are able to calculate the densities of these giant molecular clouds. The measured intensities are used with a radiative transfer code called RADEX, to determine volume densities. Our initial results suggest that there may be either less dense or cooler gas in these clouds that previously thought. If there is a significant quantity of gas less dense than 104 molecules/cm3, this could explain the lack of ongoing star formation in these clouds, and might also suggest a shorter timescale for dynamical disruption of theses clouds. In the future, we plan to improve these results by observing additional HC3N transitions, allowing us better to constrain the relative contributions of multiple temperature and density components in Galactic center clouds.

  15. Densities of Galactic Center Clouds

    NASA Astrophysics Data System (ADS)

    Barnes, Jonathan; Mills, Elisabeth A. C.; Morris, Mark R.

    2015-04-01

    The central 300 parsecs of the Galaxy is full of giant molecular clouds containing 107 solar masses worth of gas. However, our Galactic center is not forming as many stars as we think it can, based on the amount of molecular gas in this region. By studying the densities of the Galactic center clouds we hope to better understand why there is not much star formation occurring. Using data from the Green Bank and MOPRA telescopes we have observed multiple rotation transitions of HC3N and its 13C isotopologues. By measuring the integrated intensity of the HC3 N we are able to calculate the densities of these giant molecular clouds. The measured intensities are used with a radiative transfer code called RADEX, to determine volume densities. Our initial results suggest that there may be either less dense or cooler gas in these clouds that previously thought. If there is a significant quantity of gas less dense than 104 molecules/cm3 , this could explain the lack of ongoing star formation in these clouds, and might also suggest a shorter timescale for dynamical disruption of theses clouds. In the future, we plan to improve these results by observing additional HC3N transitions, allowing us better to constrain the relative contributions of multiple temperature and density components in Galactic center clouds.

  16. Hydrodynamics from Landau initial conditions

    SciTech Connect

    Sen, Abhisek; Gerhard, Jochen; Torrieri, Giorgio; Read jr, Kenneth F.; Wong, Cheuk-Yin

    2015-01-01

    We investigate ideal hydrodynamic evolution, with Landau initial conditions, both in a semi-analytical 1+1D approach and in a numerical code incorporating event-by-event variation with many events and transverse density inhomogeneities. The object of the calculation is to test how fast would a Landau initial condition transition to a commonly used boost-invariant expansion. We show that the transition to boost-invariant flow occurs too late for realistic setups, with corrections of O (20 - 30%) expected at freezeout for most scenarios. Moreover, the deviation from boost-invariance is correlated with both transverse flow and elliptic flow, with the more highly transversely flowing regions also showing the most violation of boost invariance. Therefore, if longitudinal flow is not fully developed at the early stages of heavy ion collisions, 2+1 dimensional hydrodynamics is inadequate to extract transport coefficients of the quark-gluon plasma. Based on [1, 2

  17. On the initial state and consistency relations

    SciTech Connect

    Berezhiani, Lasha; Khoury, Justin E-mail: jkhoury@sas.upenn.edu

    2014-09-01

    We study the effect of the initial state on the consistency conditions for adiabatic perturbations. In order to be consistent with the constraints of General Relativity, the initial state must be diffeomorphism invariant. As a result, we show that initial wavefunctional/density matrix has to satisfy a Slavnov-Taylor identity similar to that of the action. We then investigate the precise ways in which modified initial states can lead to violations of the consistency relations. We find two independent sources of violations: i) the state can include initial non-Gaussianities; ii) even if the initial state is Gaussian, such as a Bogoliubov state, the modified 2-point function can modify the q-vector → 0 analyticity properties of the vertex functional and result in violations of the consistency relations.

  18. Initial conditions and sampling for multifield inflation

    SciTech Connect

    Easther, Richard; Price, Layne C. E-mail: lpri691@aucklanduni.ac.nz

    2013-07-01

    We investigate the initial conditions problem for multifield inflation. In these scenarios the pre-inflationary dynamics can be chaotic, increasing the sensitivity of the onset of inflation to the initial data even in the homogeneous limit. To analyze physically equivalent scenarios we compare initial conditions at fixed energy. This ensures that each trajectory is counted once and only once, since the energy density decreases monotonically. We present a full analysis of hybrid inflation that reveals a greater degree of long range order in the set of ''successful'' initial conditions than was previously apparent. In addition, we explore the effective smoothing scale for the fractal set of successful initial conditions induced by the finite duration of the pre-inflationary phase. The role of the prior information used to specify the initial data is discussed in terms of Bayesian sampling.

  19. Strategic Initiatives and Goals.

    ERIC Educational Resources Information Center

    Howard Community Coll., Columbia, MD.

    This document outlines Howard Community College's (HCC) six strategic initiatives and goals. Each of the strategic initiatives is presented, along with a context for the statement and a list of goals to be achieved in support of the overall initiative. First, HCC will be a learning community that provides possibilities for learning that address…

  20. APEC Smart Grid Initiative

    SciTech Connect

    Bloyd, Cary N.

    2012-03-01

    This brief paper describes the activities of the Asia Pacific Economic Cooperation (APEC) Smart Grid Initiative (ASGI) which is being led by the U.S. and developed by the APEC Energy Working Group. In the paper, I describe the origin of the initiative and briefly mention the four major elements of the initiative along with existing APEC projects which support it.

  1. Initiation of vascular development.

    PubMed

    Ohashi-Ito, Kyoko; Fukuda, Hiroo

    2014-06-01

    The initiation of vascular development occurs during embryogenesis and the development of lateral organs, such as lateral roots and leaves. Understanding the mechanism underlying the initiation of vascular development has been an important goal of plant biologists. Auxin flow is a crucial factor involved in the initiation of vascular development. In addition, recent studies have identified key factors that regulate the establishment of vascular initial cells in embryos and roots. In this review, we summarize the recent findings in this field and discuss the initiation of vascular development.

  2. Initial Events in Bacterial Transcription Initiation

    PubMed Central

    Ruff, Emily F.; Record, M. Thomas; Artsimovitch, Irina

    2015-01-01

    Transcription initiation is a highly regulated step of gene expression. Here, we discuss the series of large conformational changes set in motion by initial specific binding of bacterial RNA polymerase (RNAP) to promoter DNA and their relevance for regulation. Bending and wrapping of the upstream duplex facilitates bending of the downstream duplex into the active site cleft, nucleating opening of 13 bp in the cleft. The rate-determining opening step, driven by binding free energy, forms an unstable open complex, probably with the template strand in the active site. At some promoters, this initial open complex is greatly stabilized by rearrangements of the discriminator region between the −10 element and +1 base of the nontemplate strand and of mobile in-cleft and downstream elements of RNAP. The rate of open complex formation is regulated by effects on the rapidly-reversible steps preceding DNA opening, while open complex lifetime is regulated by effects on the stabilization of the initial open complex. Intrinsic DNA opening-closing appears less regulated. This noncovalent mechanism and its regulation exhibit many analogies to mechanisms of enzyme catalysis. PMID:26023916

  3. Update of axion CDM energy density

    SciTech Connect

    Huh, Ji-Haeng

    2008-11-23

    We update cosmological bound on axion model. The contribution from the anharmonic effect and the newly introduced initial overshoot correction are considered. We present an explicit formula for the axion relic density in terms of the QCD scale {lambda}{sub QCD}, the current quark masses m{sub q}'s and the Peccei-Quinn scale F{sub a}, including firstly introduced 1.85 factor which is from the initial overshoot.

  4. FTY720 Protects Cardiac Microvessels of Diabetes: A Critical Role of S1P1/3 in Diabetic Heart Disease

    PubMed Central

    Wei, Liping; Gao, Haokao; Zhang, Rongqing; Tao, Ling; Cao, Feng; Wang, Haichang

    2012-01-01

    Background: Diabetes is associated with an increased risk of cardiac microvascular disease. The mechanisms by which this damage occurs are unknown. However, research suggests that signaling through the sphingosine-1-phosphates receptor 1 and 3 (S1P1/3) by FTY720, a sphiongolipid drug that is structually similar to SIP, may play a role in the treatment on cardiac microvascular dysfunction in diabetes. We hypothesized that FTY720 might exert the cardioprotective effects of S1P1 and S1P3 viaprotein kinase C-beta (PKCβ II) signaling pathway. Methodology/Principal Findings: Transthoracic echocardiography was performed to detect the change of cardiac function. Scanning and transmission electron microscope with lanthanum tracer were used to determine microvascular ultrastructure and permeability in vivo. Apoptosis was detected by TUNEL and CD31 dual labeling in paraffin-embedded sections. Laser capture miscrodissection was used to assess cardiac micovascular endothelial cells (CMECs) in vivo. RT-PCR and Western blot analysis were used to determine the mRNA levels and protein expression of S1P1, S1P3, and PKCβ II. In the diabetic rats vs. controls, cardiac capillaries showed significantly higher density; CD31 positive endothelial cells were significantly reduced; the apoptosis index of cardiac endothlial cells was significantly higher. And FTY720 could increase the expressional level of S1P1 and boost S1P3 trasnslocation from membrane to nuclear, then ameliorate cardiac microvascular barrier impairment and pathologic angiogenesis induced by diabetes. In addition, overexpression of PKCβ II significantly decreased the protective effect of FTY720. Conclusions: Our study represents that the deregulation of S1P1 and S1P3 is an important signalresponsible for cardiac microvascular dysfunction in diabetes. FTY720 might be competent to serve as a potential therapeutic approach for diabetic heart disease through ameliorating cardiac microvascular barrier impairment and

  5. Neutral depletion and the helicon density limit

    SciTech Connect

    Magee, R. M.; Galante, M. E.; Carr, J. Jr.; Lusk, G.; McCarren, D. W.; Scime, E. E.

    2013-12-15

    It is straightforward to create fully ionized plasmas with modest rf power in a helicon. It is difficult, however, to create plasmas with density >10{sup 20} m{sup −3}, because neutral depletion leads to a lack of fuel. In order to address this density limit, we present fast (1 MHz), time-resolved measurements of the neutral density at and downstream from the rf antenna in krypton helicon plasmas. At the start of the discharge, the neutral density underneath the antenna is reduced to 1% of its initial value in 15 μs. The ionization rate inferred from these data implies that the electron temperature near the antenna is much higher than the electron temperature measured downstream. Neutral density measurements made downstream from the antenna show much slower depletion, requiring 14 ms to decrease by a factor of 1/e. Furthermore, the downstream depletion appears to be due to neutral pumping rather than ionization.

  6. Average density in cosmology

    SciTech Connect

    Bonnor, W.B.

    1987-05-01

    The Einstein-Straus (1945) vacuole is here used to represent a bound cluster of galaxies embedded in a standard pressure-free cosmological model, and the average density of the cluster is compared with the density of the surrounding cosmic fluid. The two are nearly but not quite equal, and the more condensed the cluster, the greater the difference. A theoretical consequence of the discrepancy between the two densities is discussed. 25 references.

  7. Visualization of electronic density

    DOE PAGES

    Grosso, Bastien; Cooper, Valentino R.; Pine, Polina; Hashibon, Adham; Yaish, Yuval; Adler, Joan

    2015-04-22

    An atom’s volume depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent numerical algorithms and packages to calculate it for other materials. 3D visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. We explore several approaches to 3D charge density visualization, including the extension of an anaglyphic stereo visualization application based on the AViz package to larger structures such as nanotubes. We will describe motivations and potential applications of these tools for answering interesting questions about nanotube properties.

  8. Martian drainage densities

    USGS Publications Warehouse

    Carr, M.H.; Chuang, F.C.

    1997-01-01

    Drainage densities on Mars range from zero over large areas of volcanic plains to 0.3-0.5 km-1 locally on some volcanoes. These values refer to geologic units, not to drainage basins, as is normal for terrestrial drainage densities. The highest values are close to the lowest terrestrial values derived by similar techniques. Drainage densities were determined for every geologic unit portrayed on the 1:15,000,000 geologic map of Mars. Except for volcanoes the geologic unit with the highest drainage density is the dissected Noachian plains with a drainage density of 0.0074 km-1. The average drainage density for Noachian units is 0.0032 km-1, for Hesperian units is 0.00047 km-1, and for Amazonian units is 0.00007 km-1, excluding the volcanoes. These values are 2-3 orders of magnitude lower than typical terrestrial densities as determined by similar techniques from Landsat images. The low drainage densities, despite a cumulative record that spans billions of years, indicate that compared with the Earth, the channel-forming processes have been very inefficient or have operated only rarely or that the surface is extremely permeable. The high drainage density on volcanoes is attributed to a local cause, such as hydrothermal activity, rather than to a global cause such as climate change. Copyright. Published in 1997 by the American Geophysical Union.

  9. Spatial mismatch between the Na+ flux and spike initiation in axon initial segment.

    PubMed

    Baranauskas, Gytis; David, Yaron; Fleidervish, Ilya A

    2013-03-01

    It is widely believed that, in cortical pyramidal cells, action potentials (APs) initiate in the distal portion of axon initial segment (AIS) because that is where Na(+) channel density is highest. To investigate the relationship between the density of Na(+) channels and the spatiotemporal pattern of AP initiation, we simultaneously recorded Na(+) flux and action currents along the proximal axonal length. We found that functional Na(+) channel density is approximately four times lower in the AP trigger zone than in the middle of the AIS, where it is highest. Computational analysis of AP initiation revealed a paradoxical mismatch between the AP threshold and Na(+) channel density, which could be explained by the lopsided capacitive load imposed on the proximal end of the AIS by the somatodendritic compartment. Favorable conditions for AP initiation are therefore achieved in the distal AIS portion, close to the edge of myelin, where the current source-load ratio is highest. Our findings suggest that cable properties play a central role in determining where the AP starts, such that small plastic changes in the local AIS Na(+) channel density could have a large influence on neuronal excitability as a whole.

  10. Shock Initiation and Equation of State of Ammonium Nitrate

    NASA Astrophysics Data System (ADS)

    Robbins, David; Sheffield, Steve; Dattelbaum, Dana; Chellappa, Raja; Velisavljevic, Nenad

    2013-06-01

    Ammonium nitrate (AN) is a widely used fertilizer and mining explosive commonly found in ammonium nitrate-fuel oil. Neat AN is a non-ideal explosive with measured detonation velocities approaching 4 km/s. Previously, we reported a thermodynamically-complete equation of state for AN based on its maximum density, and showed that near-full density AN did not initiate when subjected to shock input conditions up to 22 GPa. In this work, we extend these initial results, by presenting new Hugoniot data for intermediate density neat AN obtained from gas gun-driven plate impact experiments. AN at densities from 1.8 to 1.5 g/cm3 were impacted into LiF windows using a two-stage light gas gun. Dual VISARs were used to measure the interfacial particle velocity wave profile as a function of time following impact. The new Hugoniot data, in addition to updates to thermodynamic parameters derived from structural analysis and vibrational spectroscopy measurements in high pressure diamond anvil cell experiments, are used to refine the unreacted EOS for AN. Furthermore, shock initiation of neat AN was observed as the initial porosity increased (density decreased). Insights into the relationship(s) between initial density and shock initiation sensitivity are also presented, from evidence of shock initiation in the particle velocity profiles obtained for the lower density AN samples.

  11. Density-dependent covariant energy density functionals

    SciTech Connect

    Lalazissis, G. A.

    2012-10-20

    Relativistic nuclear energy density functionals are applied to the description of a variety of nuclear structure phenomena at and away fromstability line. Isoscalar monopole, isovector dipole and isoscalar quadrupole giant resonances are calculated using fully self-consistent relativistic quasiparticle randomphase approximation, based on the relativistic Hartree-Bogoliubovmodel. The impact of pairing correlations on the fission barriers in heavy and superheavy nuclei is examined. The role of pion in constructing desnity functionals is also investigated.

  12. Progress in Initiator Modeling

    SciTech Connect

    Hrousis, C A; Christensen, J S

    2009-05-04

    There is great interest in applying magnetohydrodynamic (MHD) simulation techniques to the designs of electrical high explosive (HE) initiators, for the purpose of better understanding a design's sensitivities, optimizing its performance, and/or predicting its useful lifetime. Two MHD-capable LLNL codes, CALE and ALE3D, are being used to simulate the process of ohmic heating, vaporization, and plasma formation in the bridge of an initiator, be it an exploding bridgewire (EBW), exploding bridgefoil (EBF) or slapper type initiator. The initiation of the HE is simulated using Tarver Ignition & Growth reactive flow models. 1-D, 2-D and 3-D models have been constructed and studied. The models provide some intuitive explanation of the initiation process and are useful for evaluating the potential impact of identified aging mechanisms (such as the growth of intermetallic compounds or powder sintering). The end product of this work is a simulation capability for evaluating margin in proposed, modified or aged initiation system designs.

  13. Density in a Bottle.

    ERIC Educational Resources Information Center

    Roser, Charles E.; McCluskey, Catherine L.

    1998-01-01

    Explains how the Canadian soft drink Orbitz can be used for explorations of density in the classroom. The drink has colored spheres suspended throughout that have a density close to that of the liquid. Presents a hands-on activity that can be easily done in two parts. (DDR)

  14. Variable Density Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Variable Density Tunnel in operation. Man at far right is probably Harold J. 'Cannonball' Tuner, longtime safety officer, who started with Curtiss in the teens. This view of the Variable Density Tunnel clearly shows the layout of the Tunnel's surroundings, as well as the plumbing and power needs of the this innovative research tool.

  15. Who initiates emergency commitments?

    PubMed

    Christy, Annette; Handelsman, Jessica B; Hanson, Ardis; Ochshorn, Ezra

    2010-04-01

    Florida's Mental Health Act was amended in 2005 and 2006 to include licensed mental health counselors and licensed marriage and family therapists, respectively, to the list of professionals authorized to initiate emergency commitments. The present study evaluates the volume of involuntary emergency commitments by type of initiator for a 5 year period. The results indicate that allowing licensed mental health counselors and licensed marriage and family therapist to initiate emergency commitments has not been related to increased numbers of emergency commitments or a higher proportion of emergency commitments being initiated by mental health professionals. Potential policy and fiscal implications, as well as future directions for research, are discussed. PMID:19597746

  16. Positive streamers in air of varying density: experiments on the scaling of the excitation density

    NASA Astrophysics Data System (ADS)

    Dubrovin, D.; Nijdam, S.; Clevis, T. T. J.; Heijmans, L. C. J.; Ebert, U.; Yair, Y.; Price, C.

    2015-02-01

    Streamers are rapidly extending ionized finger-like structures that dominate the initial breakdown of large gas volumes in the presence of a sufficiently strong electric field. Their macroscopic parameters are described by simple scaling relations, where the densities of electrons and of excited molecules in the active streamer front scale as the square of the density of the neutral gas. In this work we estimate the absolute density of nitrogen molecules, excited to the C3Πu state that emit photons in the 2P-N2 band, by radiometrically calibrated short exposure intensified imaging. We test several pressures (100, 200 and 400 mbar) in artificial air at room temperature. Our results provide a first confirmation for the scaling of the density of excited species with the gas density. The method proposed here is particularly suitable to characterize the excitation densities in sprite streamers in the atmosphere.

  17. Analysis of microvascular density in early gastric carcinoma using magnifying endoscopy with narrow-band imaging

    PubMed Central

    Kawamura, Masashi; Naganuma, Hiroshi; Shibuya, Rie; Kikuchi, Tatsuya; Sakai, Yoshitaka; Nagasaki, Futoshi; Nomura, Eiki; Suzuki, Noriaki; Saito, Eri

    2016-01-01

    Background and study aims: Intramucosal vascular density differs between differentiated and undifferentiated type gastric carcinomas. This study aimed to evaluate the microvascular density characteristics of these two types of carcinoma using magnifying endoscopy with narrow-band imaging (ME-NBI). Patients and methods: In total, 42 differentiated and 10 undifferentiated types were evaluated. The microvessels observed using ME-NBI were extracted from stored still images and the microvascular density in the two carcinoma types was analyzed. Histological vascular density in resected specimens was also evaluated using CD34 immunostaining. Results: There were significant differences between the microvascular density in the differentiated and undifferentiated types of carcinoma (10.02 ± 4.72 % vs 4.02 ± 0.40 %; P < 0.001) using ME-NBI. Vascular density assessed histologically also differed significantly between differentiated and undifferentiated types in both the whole mucosal (5.81 ± 3.17 % vs 3.25 ± 1.21 %) and the superficial mucosal layers (0 – 100 μm) (6.38 ± 3.73 % vs 3.66 ± 1.46 %). However, the vascular density in the surrounding non-carcinomatous mucosa assessed using ME-NBI and histologically, was significantly lower in the differentiated than in the undifferentiated types (P < 0.001). There was good agreement between ME-NBI and histologically assessed microvascular density in both the whole (r = 0.740; P < 0.001) and superficial mucosal layers (r = 0.764; P < 0.001). White opaque substance (WOS) was seen in eight patients who had the differentiated type carcinoma. In almost all cases with WOS, the appearance of the carcinoma was discolored. Conclusions: There was a close relationship between ME-NBI assessed microvascular density and histologically assessed vascular density in the mucosal layer. Microvascular density differed significantly between the differentiated and undifferentiated

  18. The cosmological dependence of cluster density profiles

    NASA Astrophysics Data System (ADS)

    Crone, Mary M.; Evrard, August E.; Richstone, Douglas O.

    1994-10-01

    We use N-body simulations to study the shape of mean cluster density and velocity profiles in the nonlinear regime formed via gravitational instability. The dependence of the final structure on both cosmology and initial density field is examined, using a grid of cosmologies and scale-free initial power spectra P(k) varies as kn. Einstein-de Sitter, open (Omega0 = 0.2 and 0.1) and flat, low density (Omega0 = 0.2 lambda0 = 0.8) models are examined, with initial spectral indices n = -2, -1 and 0. For each model, we stack clusters in an appropriately scaled manner to define an average density profile in the nonlinear regime. The profiles are well fit by a power law rho(r) varies as r-alpha for radii whereat the local density contrast is between 100 and 3000. This covers 99% of the cluster volume. We find a clear trend toward steeper slopes (larger alphas) with both increasing n and decreasing Omega0. The Omega0 dependence is partially masked by the n dependence; there is degeneracy in the values of alpha between the Einstein-de Sitter and flat, low-density cosmologies. However, the profile slopes in the open models are consistently higher than the Omega = 1 values for the range of n examined. Cluster density profiles are thus potentially useful cosmological diagnostics. We find no evidence for a constant density core in any of the models, although the density profiles do tend to flatten at small radii. Much of the flattening is due to the force softening required by the simulations. An attempt is made to recover the unsoftened profiles assuming angular momentum invariance. The recovered profiles in Einstein-de Sitter cosmologies are consistent with a pure power law up to the highest density contrasts (106) accessible with our resolution. The low-density models show significant deviation from a power law above density contrasts approximately 105. We interpret this curvature as reflecting the non-scale-invariant nature of the background cosmology in these models. These

  19. The cosmological dependence of cluster density profiles

    NASA Technical Reports Server (NTRS)

    Crone, Mary M.; Evrard, August E.; Richstone, Douglas O.

    1994-01-01

    We use N-body simulations to study the shape of mean cluster density and velocity profiles in the nonlinear regime formed via gravitational instability. The dependence of the final structure on both cosmology and initial density field is examined, using a grid of cosmologies and scale-free initial power spectra P(k) varies as k(exp n). Einstein-de Sitter, open (Omega(sub 0) = 0.2 and 0.1) and flat, low density (Omega(sub 0) = 0.2 lambda(sub 0) = 0.8) models are examined, with initial spectral indices n = -2, -1 and 0. For each model, we stack clusters in an appropriately scaled manner to define an average density profile in the nonlinear regime. The profiles are well fit by a power law rho(r) varies as r(exp -alpha) for radii whereat the local density contrast is between 100 and 3000. This covers 99% of the cluster volume. We find a clear trend toward steeper slopes (larger alphas) with both increasing n and decreasing Omega(sub 0). The Omega(sub 0) dependence is partially masked by the n dependence; there is degeneracy in the values of alpha between the Einstein-de Sitter and flat, low-density cosmologies. However, the profile slopes in the open models are consistently higher than the Omega = 1 values for the range of n examined. Cluster density profiles are thus potentially useful cosmological diagnostics. We find no evidence for a constant density core in any of the models, although the density profiles do tend to flatten at small radii. Much of the flattening is due to the force softening required by the simulations. An attempt is made to recover the unsoftened profiles assuming angular momentum invariance. The recovered profiles in Einstein-de Sitter cosmologies are consistent with a pure power law up to the highest density contrasts (10(exp 6)) accessible with our resolution. The low-density models show significant deviation from a power law above density contrasts approximately 10(exp 5). We interpret this curvature as reflecting the non

  20. Cell density determines epithelial migration in culture.

    PubMed Central

    Rosen, P; Misfeldt, D S

    1980-01-01

    The dog kidney epithelial cell line (MDCK) has been shown to exhibit a density-correlated inhibition of growth at approxmately 6.6 X 10(5) cells per cm2. When a confluent monolayer at its maximal density was wounded by removal of a wide swath of cells, migration of the cell sheet into the denuded area occurred. Precise measurements of the rate of migration for 5 day showed that the cells accelerated at a uniform rate of 0.24 micrometer . hr-2 and, by extrapolation, possessed an apparent initial velocity of 2.8 micrometer . hr-1 at the time of wounding. The apparent initial velocity was considered to be the result of a brief (< 10 hr) and rapid acceleration dependent on cell density. To verify this, wounds were made at different densities below the maximum. In these experiments, the cells did not migrate until a "threshold" density of 2.0 X 10(5) cells per cm2 was reached regardless of the density at the time of wounding. At the threshold density, the cell sheet began to accelerate at the previously measured rate (0.24 micrometer . hr-2). Any increase in density by cell division was balanced by cell migration, so that the same threshold density was maintained by the migrating cells. Each migrating cell sustained the movement of the cell sheet at a constant rate of acceleration. It is proposed that an acceleration is, in general, characteristic of the vectorial movement of an epithelial cell sheet. Images PMID:6933523

  1. Illinois: Prevention Initiative

    ERIC Educational Resources Information Center

    Center for Law and Social Policy, Inc. (CLASP), 2012

    2012-01-01

    The Illinois Prevention Initiative provides grants to home-based and center-based programs to expand access to the Early Head Start (EHS) model as well as other birth to 3 models. The goal is to serve additional children birth to age 3 and help grantees increase program quality. The initiative to expand access to EHS and other models was…

  2. Prioritizing Scientific Initiatives.

    ERIC Educational Resources Information Center

    Bahcall, John N.

    1991-01-01

    Discussed is the way in which a limited number of astronomy research initiatives were chosen and prioritized based on a consensus of members from the Astronomy and Astrophysics Survey Committee. A list of recommended equipment initiatives and estimated costs is provided. (KR)

  3. Critical Density Interaction Studies

    SciTech Connect

    Young, P; Baldis, H A; Cheung, P; Rozmus, W; Kruer, W; Wilks, S; Crowley, S; Mori, W; Hansen, C

    2001-02-14

    Experiments have been performed to study the propagation of intense laser pulses to high plasma densities. The issue of self-focusing and filamentation of the laser pulse as well as developing predictive capability of absorption processes and x-ray conversion efficiencies is important for numerous programs at the Laboratory, particularly Laser Program (Fast Ignitor and direct-drive ICF) and D&NT (radiography, high energy backlighters and laser cutting). Processes such as resonance absorption, profile modification, linear mode conversion, filamentation and stimulated Brillouin scattering can occur near the critical density and can have important effects on the coupling of laser light to solid targets. A combination of experiments have been used to study the propagation of laser light to high plasma densities and the interaction physics of intense laser pulses with solid targets. Nonparaxial fluid codes to study nonstationary behavior of filamentation and stimulated Brillouin scattering at high densities have also been developed as part of this project.

  4. Genetics of Bone Density

    MedlinePlus

    ... study linked 32 novel genetic regions to bone mineral density. The findings may help researchers understand why ... or treating osteoporosis. Bones are made of a mineral and protein scaffold filled with bone cells. Bone ...

  5. Variable-Density Tunnel

    NASA Technical Reports Server (NTRS)

    1921-01-01

    Wind Tunnel #2, building interior. Reinforced concrete foundation for Variable-Density Tunnel (VDT) under construction. The tank and contents weighed about 100 tons. Negative on roll #1 of copy negatives returned by National Archives on 70mm film rolls.

  6. Density on Dry Land.

    ERIC Educational Resources Information Center

    Libarkin, Julie C.; Crockett, Cynthia D.; Sadler, Philip M.

    2003-01-01

    Presents activities to dispel student misconceptions about density, particularly as it applies to buoyancy. Finds that misconceptions fall under three categories: (1) size; (2) shape; and (3) material. (NB)

  7. Nutrient Density Scores.

    ERIC Educational Resources Information Center

    Dickinson, Annette; Thompson, William T.

    1979-01-01

    Announces a nutrient density food scoring system called the Index of Nutritional Quality (INQ). It expresses the ratio between the percent RDA of a nutrient and the percent daily allowance of calories in a food. (Author/SA)

  8. The local mass density

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.

    1974-01-01

    An improved mass-luminosity relation for faint main-sequence stars derived from recently revised masses for some faint double stars is presented. The total local mass density is increased to nearly 0.2 solar masses per cu pc. This estimate is as large as the mass density required by Oort's (1965) dynamical analysis of stellar motions perpendicular to the galactic plane if the mass is concentrated in a narrow layer.

  9. Shock compression of low-density foams

    SciTech Connect

    Holmes, N.C.

    1993-07-01

    Shock compression of very low density micro-cellular materials allows entirely new regimes of hot fluid states to be investigated experimentally. Using a two-stage light-gas gun to generate strong shocks, temperatures of several eV are readily achieved at densities of roughly 0.5--1 g/cm{sup 3} in large, uniform volumes. The conditions in these hot, expanded fluids are readily found using the Hugoniot jump conditions. We will briefly describe the basic methodology for sample preparation and experimental measurement of shock velocities. We present data for several materials over a range of initial densities. This paper will explore the applications of these methods for investigations of equations of state and phase diagrams, spectroscopy, and plasma physics. Finally, we discus the need for future work on these and related low-density materials.

  10. Negative Ion Density Fronts

    SciTech Connect

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  11. Autonomous aircraft initiative study

    NASA Technical Reports Server (NTRS)

    Hewett, Marle D.

    1991-01-01

    The results of a consulting effort to aid NASA Ames-Dryden in defining a new initiative in aircraft automation are described. The initiative described is a multi-year, multi-center technology development and flight demonstration program. The initiative features the further development of technologies in aircraft automation already being pursued at multiple NASA centers and Department of Defense (DoD) research and Development (R and D) facilities. The proposed initiative involves the development of technologies in intelligent systems, guidance, control, software development, airborne computing, navigation, communications, sensors, unmanned vehicles, and air traffic control. It involves the integration and implementation of these technologies to the extent necessary to conduct selected and incremental flight demonstrations.

  12. The RAS Initiative

    Cancer.gov

    NCI established the RAS Initiative to explore innovative approaches for attacking the proteins encoded by mutant forms of RAS genes and to ultimately create effective, new therapies for RAS-related cancers.

  13. RAS Initiative - Community Outreach

    Cancer.gov

    Through community and technical collaborations, workshops and symposia, and the distribution of reference reagents, the RAS Initiative seeks to increase the sharing of knowledge and resources essential to defeating cancers caused by mutant RAS genes.

  14. Advanced Concepts Research Initiative

    EPA Science Inventory

    This initiative is investigating various approaches to controlling and treating wet-weather flow (WWF) discharges in the urban watershed. WWF, including combined sewer overflow (CSO), sanitary sewer overflow (SSO) and stormwater discharges are leading causes of receiving water q...

  15. RAS Initiative - Events

    Cancer.gov

    The NCI RAS Initiative has organized multiple events with outside experts to discuss how the latest scientific and technological breakthroughs can be applied to discover vulnerabilities in RAS-driven cancers.

  16. Piezoelectrically Initiated Pyrotechnic Igniter

    NASA Technical Reports Server (NTRS)

    Quince, Asia; Dutton, Maureen; Hicks, Robert; Burnham, Karen

    2013-01-01

    This innovation consists of a pyrotechnic initiator and piezoelectric initiation system. The device will be capable of being initiated mechanically; resisting initiation by EMF, RF, and EMI (electromagnetic field, radio frequency, and electromagnetic interference, respectively); and initiating in water environments and space environments. Current devices of this nature are initiated by the mechanical action of a firing pin against a primer. Primers historically are prone to failure. These failures are commonly known as misfires or hang-fires. In many cases, the primer shows the dent where the firing pin struck the primer, but the primer failed to fire. In devices such as "T" handles, which are commonly used to initiate the blowout of canopies, loss of function of the device may result in loss of crew. In devices such as flares or smoke generators, failure can result in failure to spot a downed pilot. The piezoelectrically initiated ignition system consists of a pyrotechnic device that plugs into a mechanical system (activator), which on activation, generates a high-voltage spark. The activator, when released, will strike a stack of electrically linked piezo crystals, generating a high-voltage, low-amperage current that is then conducted to the pyro-initiator. Within the initiator, an electrode releases a spark that passes through a pyrotechnic first-fire mixture, causing it to combust. The combustion of the first-fire initiates a primary pyrotechnic or explosive powder. If used in a "T" handle, the primary would ramp the speed of burn up to the speed of sound, generating a shock wave that would cause a high explosive to go "high order." In a flare or smoke generator, the secondary would produce the heat necessary to ignite the pyrotechnic mixture. The piezo activator subsystem is redundant in that a second stack of crystals would be struck at the same time with the same activation force, doubling the probability of a first strike spark generation. If the first

  17. Initiation of Subduction at Relic Arcs

    NASA Astrophysics Data System (ADS)

    Gurnis, M.; Leng, W.

    2014-12-01

    Plate tectonics have been well established for tens of years, but how subduction initiates over tectonic history remains obscure. It has been proposed that passive margins may be a possible place for subduction initiation, but there is no obvious Cenozoic example of such a scenario, including along the passive margins of the Atlantic Ocean. With a computational method that follows the deformation of a visco-elasto-plastic medium, here we show that a favourable locale for subduction initiation is the juxtaposition of an old oceanic plate adjacent to a young, but relic arc. The probable enrichment of quartz in the middle to lower arc crust leads to two major factors which may have induced subduction initiation. One is the compositional density difference between the relic arc crust and the oceanic lithospheric mantle; the other is the significantly weakened lithosphere strength due to the rheology of wet quartz. With such a setup, we observe spontaneous subduction initiation within a few million years. The evidence that Izu-Bonin-Mariana and Tonga-Kermedec subduction zones both initiate adjacent to relic island arcs supports our conclusions. Our results provide an explanation for the rarity of subduction initiation at the passive margins. The continental lithosphere is typically old and cold. Consequently, the thermal effects cancel the compositional buoyancy contrast between the continental crust and the oceanic lithospheric mantle, making subduction initiation difficult at passive margins.

  18. Degenerate Open Shell Density Perturbation Theory

    NASA Astrophysics Data System (ADS)

    Palenik, Mark; Dunlap, Brett

    The density perturbation theory (DPT) methodology we have developed applies the Hohenberg-Kohn theorem to perturbations in density functional theory. At each order, the energy is directly minimized with respect to the density at all lower orders. The difference between the perturbed and unperturbed densities is expanded in terms of a finite number of basis functions, and a single matrix inversion in this space reduces the complexity of the problem to that of non-interacting perturbation theory. For open-shell systems with symmetry, however, the situation becomes more complex. Typically, the perturbation will break the symmetry leading to a zeroth-order shift in the Kohn-Sham potential. Because the symmetry breaking is independent of the strength of the perturbation, the mapping from the initial to the perturbed KS potential is discontinuous and techniques from perturbation theory for noninteracting particles fail. We describe a rigorous formulation of DPT for use in systems that display an initial degeneracy, such as atoms and Fe55Cp*12 clusters and present initial calculations on these systems.

  19. Initial data for general relativistic SPH

    NASA Astrophysics Data System (ADS)

    Pérez, J. P. Cruz; Cervera, J. A. González

    2013-07-01

    The initial data generation in numerical simulations is an important issue for numerical methods. In particular in Smoothed Particle Hydrodynamic (SPH), acceptance-rejection method is one of the most frequently used for generating the position of the nodes. In this work we present the transformation law of probabilities as an alternative method for density profiles distributed spherically. As a physical application we generate a distribution of data for a density profile in steady-state accretion around a Schwarzschild black hole showing the convergence of the method.

  20. Electron density and gas density measurements in a millimeter-wave discharge

    NASA Astrophysics Data System (ADS)

    Schaub, S. C.; Hummelt, J. S.; Guss, W. C.; Shapiro, M. A.; Temkin, R. J.

    2016-08-01

    Electron density and neutral gas density have been measured in a non-equilibrium air breakdown plasma using optical emission spectroscopy and two-dimensional laser interferometry, respectively. A plasma was created with a focused high frequency microwave beam in air. Experiments were run with 110 GHz and 124.5 GHz microwaves at powers up to 1.2 MW. Microwave pulses were 3 μs long at 110 GHz and 2.2 μs long at 124.5 GHz. Electron density was measured over a pressure range of 25 to 700 Torr as the input microwave power was varied. Electron density was found to be close to the critical density, where the collisional plasma frequency is equal to the microwave frequency, over the pressure range studied and to vary weakly with input power. Neutral gas density was measured over a pressure range from 150 to 750 Torr at power levels high above the threshold for initiating breakdown. The two-dimensional structure of the neutral gas density was resolved. Intense, localized heating was found to occur hundreds of nanoseconds after visible plasma formed. This heating led to neutral gas density reductions of greater than 80% where peak plasma densities occurred. Spatial structure and temporal dynamics of gas heating at atmospheric pressure were found to agree well with published numerical simulations.

  1. Platelet size and density affect shear-induced thrombus formation in tortuous arterioles

    NASA Astrophysics Data System (ADS)

    Chesnutt, Jennifer K. W.; Han, Hai-Chao

    2013-10-01

    Thrombosis accounts for 80% of deaths in patients with diabetes mellitus. Diabetic patients demonstrate tortuous microvessels and larger than normal platelets. Large platelets are associated with increased platelet activation and thrombosis, but the physical effects of large platelets in the microscale processes of thrombus formation are not clear. Therefore, the objective of this study was to determine the physical effects of mean platelet volume (MPV), mean platelet density (MPD) and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A computational model of the transport, shear-induced activation, collision, adhesion and aggregation of individual platelets was used to simulate platelet interactions and thrombus formation in tortuous arterioles. Our results showed that an increase in MPV resulted in a larger number of activated platelets, though MPD and level of tortuosity made little difference on platelet activation. Platelets with normal MPD yielded the lowest amount of mural thrombus. With platelets of normal MPD, the amount of mural thrombus decreased with increasing level of tortuosity but did not have a simple monotonic relationship with MPV. The physical mechanisms associated with MPV, MPD and arteriole tortuosity play important roles in platelet activation and thrombus formation.

  2. High-resolution tomographic imaging of microvessels

    NASA Astrophysics Data System (ADS)

    Müller, Bert; Lang, Sabrina; Dominietto, Marco; Rudin, Markus; Schulz, Georg; Deyhle, Hans; Germann, Marco; Pfeiffer, Franz; David, Christian; Weitkamp, Timm

    2008-08-01

    Cancer belongs to the primary diseases these days. Although different successful treatments including surgery, chemical, pharmacological, and radiation therapies are established, the aggressive proliferation of cancerous cells and the related formation of blood vessels has to be better understood to develop more powerful strategies against the different kinds of cancer. Angiogenesis is one of the crucial steps for the survival and metastasis formation of malignant tumors. Although therapeutic strategies attempting to inhibit these processes are being developed, the biological regulation is still unclear. This study concentrates on the three-dimensional morphology of vessels formed in a mouse tumor xenograft model post mortem. Synchrotron radiation-based micro computed tomography (SRμCT) could provide the necessary information that is essential for validating the simulations. Using mouse and human brain tissue, the different approaches to extract the vessel tree from SRμCT data are discussed. These approaches include corrosion casting, the application of contrast agents such as barium sulfate, tissue embedding, all of them regarded as materials science based. Alternatively, phase contrast tomography was used, which gave rise to promising results but still not reaches the spatial resolution to uncover the smallest capillaries.

  3. Particle conservation in dynamical density functional theory

    NASA Astrophysics Data System (ADS)

    de las Heras, Daniel; Brader, Joseph M.; Fortini, Andrea; Schmidt, Matthias

    2016-06-01

    We present the exact adiabatic theory for the dynamics of the inhomogeneous density distribution of a classical fluid. Erroneous particle number fluctuations of dynamical density functional theory are absent, both for canonical and grand canonical initial conditions. We obtain the canonical free energy functional, which yields the adiabatic interparticle forces of overdamped Brownian motion. Using an exact and one of the most advanced approximate hard core free energy functionals, we obtain excellent agreement with simulations. The theory applies to finite systems in and out of equilibrium.

  4. Particle conservation in dynamical density functional theory.

    PubMed

    de Las Heras, Daniel; Brader, Joseph M; Fortini, Andrea; Schmidt, Matthias

    2016-06-22

    We present the exact adiabatic theory for the dynamics of the inhomogeneous density distribution of a classical fluid. Erroneous particle number fluctuations of dynamical density functional theory are absent, both for canonical and grand canonical initial conditions. We obtain the canonical free energy functional, which yields the adiabatic interparticle forces of overdamped Brownian motion. Using an exact and one of the most advanced approximate hard core free energy functionals, we obtain excellent agreement with simulations. The theory applies to finite systems in and out of equilibrium.

  5. Density variations in thermoelectrics

    SciTech Connect

    Mahan, G. D.

    2000-05-15

    Equations are solved to give the variations in temperature, density, and potential, when a solid has electrical currents, heat currents, and particle diffusion. Solutions are presented in one dimension for currents down a bar. These solutions are used to calculate the efficiency of a thermoelectric refrigerator, which is optimized to give the coefficient of performance (COP). The COP depends upon the temperature difference {delta}T, but does not depend upon the density difference {delta}n between the two ends of the bar. (c) 2000 American Institute of Physics.

  6. Density Equalizing Map Projections

    1995-07-01

    A geographic map is mathematically transformed so that the subareas of the map are proportional to a given quantity such as population. In other words, population density is equalized over the entire map. The transformed map can be used as a display tool, or it can be statistically analyzed. For example, cases of disease plotted on the transformed map should be uniformly distributed at random, if disease rates are everywhere equal. Geographic clusters of diseasemore » can be readily identified, and their statistical significance determined, on a density equalized map.« less

  7. Research on diabatic initialization

    NASA Technical Reports Server (NTRS)

    Kashara, Akira

    1993-01-01

    The objective of this research is to contribute to the improvement of the analyses of irrotational wind and moisture fields in the tropics through advancement in the technique of initialization, incorporating diabatic effects and use of satellite-derived, radiometric imagery data that are not used currently by operational centers. Significant accomplishments during the period of May 1991 - April 1992 in research involving the following are presented: impact of tropical initialization upon the spin-up of precipitation forecasts; and a unified approach to diabatic initialization for improvement in the analysis of divergence and water vapor fields in the tropics. Focus of current research and plans for next year are discussed with respect to the topics of controlling the precipitation over shoot during the early part of a numerical forecast and the use of satellite imagery data for improvement of the tropical analysis.

  8. Civil space technology initiative

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Civil Space Technology Initiative (CSTI) is a major, focused, space technology program of the Office of Aeronautics, Exploration and Technology (OAET) of NASA. The program was initiated to advance technology beyond basic research in order to expand and enhance system and vehicle capabilities for near-term missions. CSTI takes critical technologies to the point at which a user can confidently incorporate the new or expanded capabilities into relatively near-term, high-priority NASA missions. In particular, the CSTI program emphasizes technologies necessary for reliable and efficient access to and operation in Earth orbit as well as for support of scientific missions from Earth orbit.

  9. Clean Coal Power Initiative

    SciTech Connect

    Doug Bartlett; Rob James; John McDermott; Neel Parikh; Sanjay Patnaik; Camilla Podowski

    2006-03-31

    This report is the fifth quarterly Technical Progress Report submitted by NeuCo, Incorporated, under Award Identification Number, DE-FC26-04NT41768. This award is part of the Clean Coal Power Initiative (''CCPI''), the ten-year, $2B initiative to demonstrate new clean coal technologies in the field. This report is one of the required reports listed in Attachment B Federal Assistance Reporting Checklist, part of the Cooperative Agreement. The report covers the award period January 1, 2006 - March 31, 2006 and NeuCo's efforts within design, development, and deployment of on-line optimization systems during that period.

  10. Material and Optical Densities

    ERIC Educational Resources Information Center

    Gluck, Paul

    2007-01-01

    The bending of a laser beam in a medium with a density and refractive index gradient in the same direction has been described previously. When a transparent container is half filled with a salt or sugar solution and an equal amount of water is floated on top of it, then diffusion will create a concentration gradient from top to bottom. A laser…

  11. Density in Liquids.

    ERIC Educational Resources Information Center

    Nesin, Gert; Barrow, Lloyd H.

    1984-01-01

    Describes a fourth-grade unit on density which introduces a concept useful in the study of chemistry and procedures appropriate to the chemistry laboratory. The hands-on activities, which use simple equipment and household substances, are at the level of thinking Piaget describes as concrete operational. (BC)

  12. Multiple density layered insulator

    DOEpatents

    Alger, Terry W.

    1994-01-01

    A multiple density layered insulator for use with a laser is disclosed wh provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation.

  13. Multiple density layered insulator

    DOEpatents

    Alger, T.W.

    1994-09-06

    A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.

  14. Incident meteoroid flux density

    NASA Technical Reports Server (NTRS)

    Badadjanov, P. B.; Bibarsov, R. SH.; Getman, V. S.; Kolmakov, V. M.

    1987-01-01

    Complex photographic and radar meteor observations were carried out. Using the available observational data, the density of incident flux of meteoroids was estimated over a wide mass range of 0.001 to 100 g. To avoid the influence of apparatus selectivity a special technique was applied. The main characteristics of this technique are given and discussed.

  15. Energy in density gradient

    SciTech Connect

    Vranjes, J.; Kono, M.

    2015-01-15

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work, the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindrical configuration. This is of practical importance for drift wave instability in various plasmas, and, in particular, in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit volume (per second) in quiet regions in the corona. Consequently, within the life-time of a magnetic structure such energy losses can easily be compensated by the stochastic drift wave heating.

  16. Culture systems: embryo density.

    PubMed

    Reed, Michael L

    2012-01-01

    Embryo density is defined as the embryo-to-volume ratio achieved during in vitro culture; in other words, it is the number of embryos in a defined volume of culture medium. The same density can be achieved by manipulating either the number of embryos in a given volume of medium, or manipulating the volume of the medium for a given number of embryos: for example, a microdrop with five embryos in a 50 μl volume under oil has the same embryo-to-volume ratio (1:10 μl) as a microdrop with one embryo in a 10 μl volume under oil (1:10 μl). Increased embryo density can improve mammalian embryo development in vitro; however, the mechanism(s) responsible for this effect may be different with respect to which method is used to increase embryo density.Standard, flat sterile plastic petri dishes are the most common, traditional platform for embryo culture. Microdrops under a mineral oil overlay can be prepared to control embryo density, but it is critical that dish preparation is consistent, where appropriate techniques are applied to prevent microdrop dehydration during preparation, and results of any data collection are reliable, and repeatable. There are newer dishes available from several manufacturers that are specifically designed for embryo culture; most are readily available for use with human embryos. The concept behind these newer dishes relies on fabrication of conical and smaller volume wells into the dish design, so that embryos rest at the lowest point in the wells, and where putative embryotrophic factors may concentrate.Embryo density is not usually considered by the embryologist as a technique in and of itself; rather, the decision to culture embryos in groups or individually is protocol-driven, and is based more on convenience or the need to collect data on individual embryos. Embryo density can be controlled, and as such, it can be utilized as a simple, yet effective tool to improve in vitro development of human embryos. PMID:22829380

  17. Prestellar cores: initial orbit and boundary

    NASA Astrophysics Data System (ADS)

    Horedt, G. P.

    2016-06-01

    The initial orbit of a prestellar core in the resisting intercore medium is found to be an elliptic spiral round the mass centre of the parent molecular cloud (clump), with exponentially decreasing semiaxes, high constant eccentricity, and constant period. Prestellar cores are stable against perturbations caused by the parent cloud, if the corresponding mean density contrast is larger than about 10. This value defines the safe boundary of a prestellar core within its parent cloud and is in accordance with observations.

  18. Partition density functional theory

    NASA Astrophysics Data System (ADS)

    Nafziger, Jonathan

    Partition density functional theory (PDFT) is a method for dividing a molecular electronic structure calculation into fragment calculations. The molecular density and energy corresponding to Kohn Sham density-functional theory (KS-DFT) may be exactly recovered from these fragments. Each fragment acts as an isolated system except for the influence of a global one-body 'partition' potential which deforms the fragment densities. In this work, the developments of PDFT are put into the context of other fragment-based density functional methods. We developed three numerical implementations of PDFT: One within the NWChem computational chemistry package using basis sets, and the other two developed from scratch using real-space grids. It is shown that all three of these programs can exactly reproduce a KS-DFT calculation via fragment calculations. The first of our in-house codes handles non-interacting electrons in arbitrary one-dimensional potentials with any number of fragments. This code is used to explore how the exact partition potential changes for different partitionings of the same system and also to study features which determine which systems yield non-integer PDFT occupations and which systems are locked into integer PDFT occupations. The second in-house code, CADMium, performs real-space calculations of diatomic molecules. Features of the exact partition potential are studied for a variety of cases and an analytical formula determining singularities in the partition potential is derived. We introduce an approximation for the non-additive kinetic energy and show how this quantity can be computed exactly. Finally a PDFT functional is developed to address the issues of static correlation and delocalization errors in approximations within DFT. The functional is applied to the dissociation of H2 + and H2.

  19. Investigations of initiation spot size effects

    SciTech Connect

    Clarke, Steven A; Akinci, Adrian A; Leichty, Gary; Schaffer, Timothy; Murphy, Michael J; Munger, Alan; Thomas, Keith A

    2010-01-01

    As explosive components become smaller, a greater understanding of the effect of initiation spot size on detonation becomes increasingly critical. A series of tests of the effect of initiation spot size will be described. A series of DOI (direct optical initiation) detonators with initiation spots sizes from {approx}50 um to 1000um have been tested to determine laser parameters for threshold firing of low density PETN pressings. Results will be compared with theoretical predictions. Outputs of the initiation source (DOI ablation) have been characterized by a suite of diagnostics including PDV and schlieren imaging. Outputs of complete detonators have been characterized using PDV, streak, and/or schlieren imaging. At present, we have not found the expected change in the threshold energy to spot size relationship for DOI type detonators found in similar earlier for projectiles, slappers and EBWs. New detonators designs (Type C) are currently being tested that will allow the determination of the threshold for spot sizes from 250 um to 105um, where we hope to see change in the threshold vs. spot size relationship. Also, one test of an extremely small diameter spot size (50um) has resulted in preliminary NoGo only results even at energy densities as much as 8 times the energy density of the threshold results presented here. This gives preliminary evidence that 50um spot may be beyond the critical initiation diameter. The constant threshold energy to spot size relationship in the data to date does however still give some insight into the initiation mechanism of DOI detonators. If the DOI initiation mechanism were a 1D mechanism similar to a slapper or a flyer impact, the expected inflection point in the graph would have been between 300um and 500um diameter spot size, within the range of the data presented here. The lack of that inflection point indicates that the DOI initiation mechanism is more likely a 2D mechanism similar to a sphere or rod projectile. We expect to

  20. Mixed-Initiative Clustering

    ERIC Educational Resources Information Center

    Huang, Yifen

    2010-01-01

    Mixed-initiative clustering is a task where a user and a machine work collaboratively to analyze a large set of documents. We hypothesize that a user and a machine can both learn better clustering models through enriched communication and interactive learning from each other. The first contribution or this thesis is providing a framework of…

  1. Best Practices & Outstanding Initiatives

    ERIC Educational Resources Information Center

    Training, 2011

    2011-01-01

    In this article, "Training" editors recognize innovative and successful learning and development programs and practices. They share best practices from Automatic Data Processing, Inc., Farmers Insurance Group, FedEx Express, InterContinental Hotels Group, and Oakwood Temporary Housing. They also present the outstanding initiatives of EMD Serono,…

  2. The SEED Initiative

    ERIC Educational Resources Information Center

    Teich, Carolyn R.

    2011-01-01

    Committed to fulfilling the promise of the green economy, the American Association of Community Colleges (AACC) launched the Sustainability Education and Economic Development (SEED) initiative (www.theseedcenter.org) in October 2010. The project advances sustainability and clean energy workforce development practices at community colleges by…

  3. Envisioning Effective Laptop Initiatives

    ERIC Educational Resources Information Center

    Clausen, Jon M.; Britten, Jody; Ring, Gail

    2008-01-01

    A recent survey of 74 building-level school administrators in Indiana challenged many of the assumptions regarding 1:1 laptop initiatives and how 1:1 access would affect teaching and learning. It also revealed disturbing realities regarding instructional practices of teachers, as well as efforts to improve school technology integration. The intent…

  4. Funds Fuel Graduation Initiatives

    ERIC Educational Resources Information Center

    Gewertz, Catherine

    2010-01-01

    In the first wave of funding under a revitalized high school graduation initiative, the U.S. Department of Education is betting nearly $50 million that it can help states and school districts find better ways to hang onto students who might drop out and bring back those who have disappeared without diplomas. Twenty-nine states and districts won…

  5. Focusing educational initiatives

    NASA Technical Reports Server (NTRS)

    Parks, George K.

    1990-01-01

    The United States will soon be facing a critical shortage of aerospace scientists and engineers. To address this problem, Space Grant Colleges can assist in focusing interest in existing educational initiatives and in creating new educational opportunities, particularly for women and underrepresented minorities.

  6. Clean Energy Manufacturing Initiative

    SciTech Connect

    2013-04-01

    The initiative will strategically focus and rally EERE’s clean energy technology offices and Advanced Manufacturing Office around the urgent competitive opportunity for the United States to be the leader in the clean energy manufacturing industries and jobs of today and tomorrow.

  7. Monolithic exploding foil initiator

    DOEpatents

    Welle, Eric J; Vianco, Paul T; Headley, Paul S; Jarrell, Jason A; Garrity, J. Emmett; Shelton, Keegan P; Marley, Stephen K

    2012-10-23

    A monolithic exploding foil initiator (EFI) or slapper detonator and the method for making the monolithic EFI wherein the exploding bridge and the dielectric from which the flyer will be generated are integrated directly onto the header. In some embodiments, the barrel is directly integrated directly onto the header.

  8. Transformative Change Initiative

    ERIC Educational Resources Information Center

    Bragg, D. D.; Kirby, C.; Witt, M. A.; Richie, D.; Mix, S.; Feldbaum, M.; Liu, S.; Mason, M.

    2014-01-01

    The Transformative Change Initiative (TCI) is dedicated to assisting community colleges to scale up innovation in the form of guided pathways, programs of study, and evidence-based strategies to improve student outcomes and program, organization, and system performance. The impetus for TCI is the Trade Adjustment Assistance Community College and…

  9. Global healthy backpack initiatives.

    PubMed

    Jayaratne, Kapila; Jacobs, Karen; Fernando, Dulitha

    2012-01-01

    Schoolbag use by children is a global common concern.. Children carry school books and other amenities in their school bags. Global evidence indicates that daily load carried by school children may have negative health implications. Backpack as a school bag model, is the healthiest way of load carriage for school children. Several initiatives have been launched world over to minimize unhealthy consequences resulting from schoolbags. Based on a situation analysis, Sri Lanka implemented a national healthy schoolbag campaign by joint efforts of Ministries of Health and Education. Actions were contemplated on; strategies for bag weight reduction, introduction of an ergonomically modeled schoolbag and bag behaviour change. New strategies were introduced with awareness campaigns to policy makers, bag manufacturers, parents, teachers and children. Four million schoolchildren benefitted. In 2000, the backpack strategy of "Pack it Light, Wear it Right" was started as a public health initiative in the United States by the American Occupational Therapy Association (AOTA). Over the last eleven years, thousands of occupational therapy practitioners and students participated in educational programs and outreach activities. In 2004, modeled after the success AOTA initiative, the Icelandic Occupational Therapy Association launched a national backpack awareness initiative. This article shares examples of practices that could be implemented in any context to the promote health of children.

  10. Initiating Change in Schools.

    ERIC Educational Resources Information Center

    Bowers, Bruce C.

    1990-01-01

    Schools are expected not only to conserve society's values and standards, but to be dynamic organizations with built-in mechanisms for incorporating rapid, far-reaching change. Although change is unlikely unless at least one highly motivated individual assumes the role of initial change agent, lasting change requires more than the efforts of a…

  11. Taking Initiative on Writing

    ERIC Educational Resources Information Center

    Gere, Anne Ruggles

    2010-01-01

    A strong schoolwide writing program supports learning across disciplines and provides a focus for collaboration and professional development for all teachers. The elements for schoolwide writing initiatives include: (1) Setting schoolwide goals for student achievement in writing; (2) Developing and implementing action steps that address both…

  12. Harmonization Initiatives in Europe

    PubMed Central

    2016-01-01

    Introduction Modern medicine is more and more based on protocols and guidelines; clinical laboratory data play very often a relevant role in these documents and for this reason the need for their harmonization is increasing. To achieve harmonized results the harmonization process must not be limited to only the analytical part, but has to include the pre- and the post-analytical phases. Results To fulfill this need the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) has started several initiatives. A Working Group on harmonization of the total testing process (WG-H) has been created with the aims of: 1) surveying and summarizing national European and pan European harmonization initiatives; 2) promoting and coordinating the dissemination of especially promising harmonization initiatives among the EFLM member societies; and 3) taking initiatives to harmonize nomenclature, units and reference intervals at a European level. The activity of the WG started this year with a questionnaire targeted at surveying the status of various harmonization activities, especially those in the pre- and post-analytical phase categories, among the European laboratory medicine societies. Conclusions Based on the results of the questionnaire, some activities promoting the dissemination of best practice in blood sampling, sample storage and transportation, in collaboration with WG on the pre-analytical phase, will be promoted, and initiatives to spread to all the European countries the use of SI units in reporting, will be undertaken. Moreover, EFLM has created a Task and Finish Group on standardization of the color coding for blood collection tube closures that is actively working to accomplish this difficult task through collaboration with manufacturers. PMID:27683503

  13. Next generation initiation techniques

    NASA Technical Reports Server (NTRS)

    Warner, Tom; Derber, John; Zupanski, Milija; Cohn, Steve; Verlinde, Hans

    1993-01-01

    Four-dimensional data assimilation strategies can generally be classified as either current or next generation, depending upon whether they are used operationally or not. Current-generation data-assimilation techniques are those that are presently used routinely in operational-forecasting or research applications. They can be classified into the following categories: intermittent assimilation, Newtonian relaxation, and physical initialization. It should be noted that these techniques are the subject of continued research, and their improvement will parallel the development of next generation techniques described by the other speakers. Next generation assimilation techniques are those that are under development but are not yet used operationally. Most of these procedures are derived from control theory or variational methods and primarily represent continuous assimilation approaches, in which the data and model dynamics are 'fitted' to each other in an optimal way. Another 'next generation' category is the initialization of convective-scale models. Intermittent assimilation systems use an objective analysis to combine all observations within a time window that is centered on the analysis time. Continuous first-generation assimilation systems are usually based on the Newtonian-relaxation or 'nudging' techniques. Physical initialization procedures generally involve the use of standard or nonstandard data to force some physical process in the model during an assimilation period. Under the topic of next-generation assimilation techniques, variational approaches are currently being actively developed. Variational approaches seek to minimize a cost or penalty function which measures a model's fit to observations, background fields and other imposed constraints. Alternatively, the Kalman filter technique, which is also under investigation as a data assimilation procedure for numerical weather prediction, can yield acceptable initial conditions for mesoscale models. The

  14. Universal density profile for cosmic voids.

    PubMed

    Hamaus, Nico; Sutter, P M; Wandelt, Benjamin D

    2014-06-27

    We present a simple empirical function for the average density profile of cosmic voids, identified via the watershed technique in ΛCDM N-body simulations. This function is universal across void size and redshift, accurately describing a large radial range of scales around void centers with only two free parameters. In analogy to halo density profiles, these parameters describe the scale radius and the central density of voids. While we initially start with a more general four-parameter model, we find two of its parameters to be redundant, as they follow linear trends with the scale radius in two distinct regimes of the void sample, separated by its compensation scale. Assuming linear theory, we derive an analytic formula for the velocity profile of voids and find an excellent agreement with the numerical data as well. In our companion paper [Sutter et al., arXiv:1309.5087 [Mon. Not. R. Astron. Soc. (to be published)

  15. Universal Density Profile for Cosmic Voids

    NASA Astrophysics Data System (ADS)

    Hamaus, Nico; Sutter, P. M.; Wandelt, Benjamin D.

    2014-06-01

    We present a simple empirical function for the average density profile of cosmic voids, identified via the watershed technique in ΛCDM N-body simulations. This function is universal across void size and redshift, accurately describing a large radial range of scales around void centers with only two free parameters. In analogy to halo density profiles, these parameters describe the scale radius and the central density of voids. While we initially start with a more general four-parameter model, we find two of its parameters to be redundant, as they follow linear trends with the scale radius in two distinct regimes of the void sample, separated by its compensation scale. Assuming linear theory, we derive an analytic formula for the velocity profile of voids and find an excellent agreement with the numerical data as well. In our companion paper [Sutter et al., arXiv:1309.5087 [Mon. Not. R. Astron. Soc. (to be published)

  16. Material Release at High-Energy Densities

    NASA Astrophysics Data System (ADS)

    Nilson, P. M.; Betti, R.; Meyerhofer, D. D.; Shvydky, A.; Solodov, A. A.; Jaanimagi, P. A.; Froula, D. H.

    2013-10-01

    High-energy-density matter releases after an inertial time, creating nonideal plasmas with unique thermodynamic properties. Picosecond-resolution x-ray radiography and flash (100-ps) x-ray penumbral imaging were used to measure the release of metal targets heated by a powerful flux of energetic electrons or protons generated by the OMEGA EP Laser System. The data show target decompression over a nanosecond period after the initial target-heating phase. The measured plasma density profiles and target-release speeds were used to infer the pressure-density release isentropes. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  17. Extracting primordial density fluctuations

    PubMed

    Gawiser; Silk

    1998-05-29

    The combination of detections of anisotropy in cosmic microwave background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by three orders of magnitude. These data are found to be inconsistent with the predictions of several popular cosmological models. Agreement between the data and the cold + hot dark matter model, however, suggests that a significant fraction of the matter in the universe may consist of massive neutrinos.

  18. High power density targets

    NASA Astrophysics Data System (ADS)

    Pellemoine, Frederique

    2013-12-01

    In the context of new generation rare isotope beam facilities based on high-power heavy-ion accelerators and in-flight separation of the reaction products, the design of the rare isotope production targets is a major challenge. In order to provide high-purity beams for science, high resolution is required in the rare isotope separation. This demands a small beam spot on the production target which, together with the short range of heavy ions in matter, leads to very high power densities inside the target material. This paper gives an overview of the challenges associated with this high power density, discusses radiation damage issues in targets exposed to heavy ion beams, and presents recent developments to meet some of these challenges through different projects: FAIR, RIBF and FRIB which is the most challenging. Extensive use of Finite Element Analysis (FEA) has been made at all facilities to specify critical target parameters and R&D work at FRIB successfully retired two major risks related to high-power density and heavy-ion induced radiation damage.

  19. Gravity wave initiated convection

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1990-01-01

    The vertical velocity of convection initiated by gravity waves was investigated. In one particular case, the convective motion-initiated and supported by the gravity wave-induced activity (excluding contributions made by other mechanisms) reached its maximum value about one hour before the production of the funnel clouds. In another case, both rawinsonde and geosynchronous satellite imagery were used to study the life cycles of severe convective storms. Cloud modelling with input sounding data and rapid-scan imagery from GOES were used to investigate storm cloud formation, development and dissipation in terms of growth and collapse of cloud tops, as well as, the life cycles of the penetration of overshooting turrets above the tropopause. The results based on these two approaches are presented and discussed.

  20. Arc initiation in cathodic arc plasma sources

    DOEpatents

    Anders, Andre

    2002-01-01

    A "triggerless" arc initiation method and apparatus is based on simply switching the arc supply voltage to the electrodes (anode and cathode). Neither a mechanical trigger electrode nor a high voltage flashover from a trigger electrode is required. A conducting path between the anode and cathode is provided, which allows a hot spot to form at a location where the path connects to the cathode. While the conductive path is eroded by the cathode spot action, plasma deposition ensures the ongoing repair of the conducting path. Arc initiation is achieved by simply applying the relatively low voltage of the arc power supply, e.g. 500 V-1 kV, with the insulator between the anode and cathode coated with a conducting layer and the current at the layer-cathode interface concentrated at one or a few contact points. The local power density at these contact points is sufficient for plasma production and thus arc initiation. A conductive surface layer, such as graphite or the material being deposited, is formed on the surface of the insulator which separates the cathode from the anode. The mechanism of plasma production (and arc initiation) is based on explosive destruction of the layer-cathode interface caused by joule heating. The current flow between the thin insulator coating and cathode occurs at only a few contact points so the current density is high.

  1. The space exploration initiative

    NASA Technical Reports Server (NTRS)

    Priest, Pete

    1991-01-01

    A number of view graph charts are presented which outline the presentation. Outlined are reasons for going to Mars, why it is necessary to go to the Moon first, and the presidential decision on the space exploration initiative. Other representative charts are entitled: Lunar transportation system requirement drivers; Mars transportation system requirement drivers; National space policy goals; Exploration hardware needed; Mars mission profile; Science on the Moon and Mars; and Two independent reviews.

  2. International perspectives and initiatives.

    PubMed

    Murphy, Jeannette

    2007-03-01

    This article introduces a new column which will explore the way different regions and nation states are dealing with the challenges of managing health information. The intention is to draw together trends which are relevant to both health science librarians and health informatics professionals. This inaugural piece maps out the territory. It provides a rationale for the column, along with evidence of current initiatives to articulate a global perspective on the application of communication and information technologies to health information. PMID:17331146

  3. National accelerated coated conductor initiative

    NASA Astrophysics Data System (ADS)

    Hawsey, Robert A.; Peterson, Dean E.

    2002-01-01

    The national Accelerated Coated Conductor Initiative (ACCI) is committed to assuring continued U.S. leadership in the development of high-temperature superconducting (HTS) wire for electric power and other applications of national interest. Increased energy efficiency, power density, and power-to-weight ratio are just a few of the tangible benefits that will be possible if today's meter lengths of HTS wire based upon the compound yttrium-barium-copper-oxygen (YBCO) can be scaled up by U.S. industry to kilometer lengths. This paper presents an evaluation of the current state of the development of coated conductor technology and a vision for its future. The challenges that U.S. Department of Energy (DOE) laboratories and their industrial and university partners face will be presented against the backdrop of the history of superconductivity program achievements. It is the purpose of this initiative to accelerate the development, commercialization, and application of high temperature superconductors through joint efforts among DOE laboratories, American industry, and universities, so that future challenges of the electric power industry can be met. Based on their advances in HTS coated conductor development in a program funded by the DOE's Office of Power Technologies, Los Alamos and Oak Ridge National Laboratories lead and support this effort by improving their own capabilities, including equipment, facilities, and technical expertise. Each laboratory has, in 2001, acquired new laboratory space, new capital equipment, and new personnel with the goal of working closely with U.S. companies to take technologies invented in the labs and demonstrated in 1-m lengths and transfer these technologies to the commercial sector. The present status of the performance of the second-generation YBCO wires will be described, and the future plans of the national laboratories will be presented. Opportunities for collaboration are discussed, as well. .

  4. Gedanken densities and exact constraints in density functional theory

    SciTech Connect

    Perdew, John P.; Ruzsinszky, Adrienn; Sun, Jianwei; Burke, Kieron

    2014-05-14

    Approximations to the exact density functional for the exchange-correlation energy of a many-electron ground state can be constructed by satisfying constraints that are universal, i.e., valid for all electron densities. Gedanken densities are designed for the purpose of this construction, but need not be realistic. The uniform electron gas is an old gedanken density. Here, we propose a spherical two-electron gedanken density in which the dimensionless density gradient can be an arbitrary positive constant wherever the density is non-zero. The Lieb-Oxford lower bound on the exchange energy can be satisfied within a generalized gradient approximation (GGA) by bounding its enhancement factor or simplest GGA exchange-energy density. This enhancement-factor bound is well known to be sufficient, but our gedanken density shows that it is also necessary. The conventional exact exchange-energy density satisfies no such local bound, but energy densities are not unique, and the simplest GGA exchange-energy density is not an approximation to it. We further derive a strongly and optimally tightened bound on the exchange enhancement factor of a two-electron density, which is satisfied by the local density approximation but is violated by all published GGA's or meta-GGA’s. Finally, some consequences of the non-uniform density-scaling behavior for the asymptotics of the exchange enhancement factor of a GGA or meta-GGA are given.

  5. Density Gradients in Chemistry Teaching

    ERIC Educational Resources Information Center

    Miller, P. J.

    1972-01-01

    Outlines experiments in which a density gradient might be used to advantage. A density gradient consists of a column of liquid, the composition and density of which varies along its length. The procedure can be used in analysis of solutions and mixtures and in density measures of solids. (Author/TS)

  6. ON THE INITIAL CONDITIONS FOR STAR FORMATION AND THE INITIAL MASS FUNCTION

    SciTech Connect

    Elmegreen, Bruce G.

    2011-04-10

    Density probability distribution functions (PDFs) for turbulent self-gravitating clouds should be convolutions of the local log-normal PDF, which depends on the local average density {rho}{sub ave} and Mach number M, and the PDFs for {rho}{sub ave} and M, which depend on the overall cloud structure. When self-gravity drives a cloud to increased central density, the total PDF develops an extended tail. If there is a critical density or column density for star formation, then the fraction of the local mass exceeding this threshold becomes higher near the cloud center. These elements of cloud structure should be in place before significant star formation begins. Then the efficiency is high so that bound clusters form rapidly, and the stellar initial mass function (IMF) has an imprint in the gas before destructive radiation from young stars can erase it. The IMF could arise from a power-law distribution of mass for cloud structure. These structures should form stars down to the thermal Jeans mass M{sub J} at each density in excess of a threshold. The high-density tail of the PDF, combined with additional fragmentation in each star-forming core, extends the IMF into the brown dwarf regime. The core fragmentation process is distinct from the cloud structuring process and introduces an independent core fragmentation mass function (CFMF). The CFMF would show up primarily below the IMF peak.

  7. Gulf Petro Initiative

    SciTech Connect

    Fathi Boukadi

    2011-02-05

    In this report, technologies for petroleum production and exploration enhancement in deepwater and mature fields are developed through basic and applied research by: (1) Designing new fluids to efficiently drill deepwater wells that can not be cost-effectively drilled with current technologies. The new fluids will be heavy liquid foams that have low-density at shallow dept to avoid formation breakdown and high density at drilling depth to control formation pressure. The goal of this project is to provide industry with formulations of new fluids for reducing casing programs and thus well construction cost in deepwater development. (2) Studying the effects of flue gas/CO{sub 2} huff n puff on incremental oil recovery in Louisiana oilfields bearing light oil. An artificial neural network (ANN) model will be developed and used to map recovery efficiencies for candidate reservoirs in Louisiana. (3) Arriving at a quantitative understanding for the three-dimensional controlled-source electromagnetic (CSEM) geophysical response of typical Gulf of Mexico hydrocarbon reservoirs. We will seek to make available tools for the qualitative, rapid interpretation of marine CSEM signatures, and tools for efficient, three-dimensional subsurface conductivity modeling.

  8. Simulation of Initiation in Hexanitrostilbene

    NASA Astrophysics Data System (ADS)

    Thompson, Aidan; Shan, Tzu-Ray; Yarrington, Cole; Wixom, Ryan

    We report on the effect of isolated voids and pairs of nearby voids on hot spot formation, growth and chemical reaction initiation in hexanitrostilbene (HNS) crystals subjected to shock loading. Large-scale, reactive molecular dynamics simulations are performed using the reactive force field (ReaxFF) as implemented in the LAMMPS software. The ReaxFF force field description for HNS has been validated previously by comparing the isothermal equation of state to available diamond anvil cell (DAC) measurements and density function theory (DFT) calculations. Micron-scale molecular dynamics simulations of a supported shockwave propagating in HNS crystal along the [010] orientation are performed (up = 1.25 km/s, Us =4.0 km/s, P = 11GPa.) We compare the effect on hot spot formation and growth rate of isolated cylindrical voids up to 0.1 µm in size with that of two 50nm voids set 100nm apart. Results from the micron-scale atomistic simulations are compared with hydrodynamics simulations. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lock- heed Martin Corporation, for the U.S. DOE National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  9. Density-dependent acoustic properties of PBX 9502

    SciTech Connect

    Brown, Geoffrey W; Thompson, Darla G; Deluca, Racci; Hartline, Ernest L; Hagelberg, Stephanie I

    2009-07-31

    We have measured the longitudinal and shear acoustic velocities of PBX 9502 as a function of density for die-pressed samples over the range 1.795 g/cc to 1.888 g/cc. The density dependence of the velocities is linear. Thermal cycling of PBX 9502 is known to induce irreversible volume growth. We have measured this volume growth dependence on density for a subset of the pressed parts and find that the most growth occurs for the samples with lowest initial density. The acoustic velocity changes due to the volume growth are significant and reflect damage in the samples.

  10. Initial blood storage experiment

    NASA Technical Reports Server (NTRS)

    Surgenor, Douglas MACN.

    1988-01-01

    The design of the Initial Blood Storage Experiment (IBSE) was based upon a carefully controlled comparison between identical sets of human blood cell suspensions - red cells, white cell, and platelets - one set of which was transported aboard the Columbia on a 6 day 11 hour mission, and the other held on the ground. Both sets were carried inside stainless steel dewars within specially fabricated flight hardware. Individual bags of cell suspensions were randomly assigned with respect to ground vs orbit status, dewar chamber, and specific location within the dewar. To foster optimal preservation, each cell type was held under specific optimal conditions of pH, ionic strength, solute concentration, gas tension, and temperature. An added variable in this initial experiment was provided by the use of three different polymer/plasticizer formulations for the sealed bags which held the blood cells. At termination of the experiment, aliquots of the suspensions, identified only by code, were distributed to be assayed. Assays were selected to constitute a broad survey of cellular properties and thereby maximize the chances of detection of gravitational effects. A total of 74 different outcome measurements were reported for statistical analysis. When the measurements were completed, the results were entered into the IBSE data base, at which time the data were matched with the original blood bag numbers to determine their status with respect to polymer/plasticizer type, orbit status (orbit or ground), and storage position within the experimental hardware. The data were studied by analysis of variance. Initially, type of bag and orbital status were main factors; later more detailed analyses were made on specific issues such as position in the hardware and specific plastic. If the analysis of variance indicated a statistical significance at the 5 percent level the corresponding p-value was reported.

  11. Through bulkhead initiator studies

    SciTech Connect

    Begeal, D.R.

    1997-03-01

    This report describes recent work done to demonstrate feasibility of a fail-safe Through Bulkhead Initiator with minimum dimensions and suitable for use in cyclical thermal environments. Much of the ground work for a fail-safe TBI was previously done by A.C. Schwartz. This study is an expansion of Schwartz`s work to evaluate devices with bulkheads of 304 stainless steel and Inconel 718; explosive donors of PETN, BNCP, and a 0.005 inch thick steel flying plate donor traveling at 2.6 mm/{micro}s; and explosive acceptors of PETN and BNCP. Bulkhead thickness were evaluated in the range of 0.040 to 0.180 inch. The explosive acceptors initiated a small HMX pellet to drive a 0.005 inch thick steel flying plate, and VISAR histories of the HMX-driven flying plates were the measure of acceptable performance. A companion set of samples used a PMMA acceptor to measure the particle velocities at the bulkhead/PMMA interface with VISAR. These data were used to compute the input pressure to the acceptor explosives in an attempt to measure initiation threshold. Unfortunately, the range of bulkhead thicknesses tested did not give any failures, thus the threshold was not determined. It was found that either explosive or the flying plate would perform as a TBI in the bulkhead thickness range tested. The optimum TBI is about 0.060 inches thick, and steel bulkheads seem to be more structurally sound than those made of Inconel. That is, cross section views of the Inconel bulkheads showed it to be more prone to stress cracking than was the 304 stainless steel. Both PETN and BNCP showed good performance when tested at {minus}65 F following thermal cycling of {minus}65 F to +165 F. Analysis of the TBI function times showed that BNCP acceptor explosives were undergoing the classical deflagration to detonation process. The PETN acceptors were undergoing prompt detonation.

  12. High Energy Density Capacitors

    SciTech Connect

    2010-07-01

    BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.

  13. Human Research Initiative (HRI)

    NASA Technical Reports Server (NTRS)

    Motil, Brian

    2003-01-01

    A code U initiative starting in the FY04 budget includes specific funding for 'Phase Change' and 'Multiphase Flow Research' on the ISS. NASA GRC developed a concept for two facilities based on funding/schedule constraints: 1) Two Phase Flow Facility (TphiFFy) which assumes integrating into FIR; 2) Contact Line Dynamics Experiment Facility (CLiDE) which assumes integration into MSG. Each facility will accommodate multiple experiments conducted by NRA selected PIs with an overall goal of enabling specific NASA strategic objectives. There may also be a significant ground-based component.

  14. Feedback stabilization initiative

    SciTech Connect

    1997-06-01

    Much progress has been made in attaining high confinement regimes in magnetic confinement devices. These operating modes tend to be transient, however, due to the onset of MHD instabilities, and their stabilization is critical for improved performance at steady state. This report describes the Feedback Stabilization Initiative (FSI), a broad-based, multi-institutional effort to develop and implement methods for raising the achievable plasma betas through active MHD feedback stabilization. A key element in this proposed effort is the Feedback Stabilization Experiment (FSX), a medium-sized, national facility that would be specifically dedicated to demonstrating beta improvement in reactor relevant plasmas by using a variety of MHD feedback stabilization schemes.

  15. UNLV Nuclear Hydrogen Initiative

    SciTech Connect

    Hechanova, Anthony E.; Johnson, Allen; O'Toole, Brendan; Trabia, Mohamed; Peterson, Per

    2012-10-25

    Evaluation of the Crack growth rate (CGR) of Alloy 617 and Alloy 276 under constant K at ambient temperature has been completed. Creep deformation of Alloy 230 at different temperature range and load level has been completed and heat to heat variation has been noticed. Creep deformation study of Alloy 276 has been completed under an applied initial stress level of 10% of yield stress at 950ºC. The grain size evaluation of the tested creep specimens of Alloy 276 has been completed.

  16. Advanced Monitoring systems initiative

    SciTech Connect

    R.J. Venedam; E.O. Hohman; C.F. Lohrstorfer; S.J. Weeks; J.B. Jones; W.J. Haas

    2004-09-30

    The Advanced Monitoring Systems Initiative (AMSI) actively searches for promising technologies and aggressively moves them from the research bench into DOE/NNSA end-user applications. There is a large unfulfilled need for an active element that reaches out to identify and recruit emerging sensor technologies into the test and evaluation function. Sensor research is ubiquitous, with the seeds of many novel concepts originating in the university systems, but at present these novel concepts do not move quickly and efficiently into real test environments. AMSI is a widely recognized, self-sustaining ''business'' accelerating the selection, development, testing, evaluation, and deployment of advanced monitoring systems and components.

  17. Hanford tanks initiative plan

    SciTech Connect

    McKinney, K.E.

    1997-07-01

    Abstract: The Hanford Tanks Initiative (HTI) is a five-year project resulting from the technical and financial partnership of the U.S. Department of Energy`s Office of Waste Management (EM-30) and Office of Science and Technology Development (EM-50). The HTI project accelerates activities to gain key technical, cost performance, and regulatory information on two high-level waste tanks. The HTI will provide a basis for design and regulatory decisions affecting the remainder of the Tank Waste Remediation System`s tank waste retrieval Program.

  18. Stirling to Flight Initiative

    NASA Technical Reports Server (NTRS)

    Hibbard, Kenneth E.; Mason, Lee S.; Ndu, Obi; Smith, Clayton; Withrow, James P.

    2016-01-01

    Flight (S2F) initiative with the objective of developing a 100-500 We Stirling generator system. Additionally, a different approach is being devised for this initiative to avoid pitfalls of the past, and apply lessons learned from the recent ASRG experience. Two key aspects of this initiative are a Stirling System Technology Maturation Effort, and a Surrogate Mission Team (SMT) intended to provide clear mission pull and requirements context. The S2F project seeks to lead directly into a DOE flight system development of a new SRG. This paper will detail the proposed S2F initiative, and provide specifics on the key efforts designed to pave a forward path for bringing Stirling technology to flight.

  19. Initiation of slug flow

    SciTech Connect

    Hanratty, T.J.; Woods, B.D.

    1995-12-31

    The initiation of slug flow in a horizontal pipe can be predicted either by considering the stability of a slug or by considering the stability of a stratified flow. Measurements of the shedding rate of slugs are used to define necessary conditions for the existence of a slug. Recent results show that slugs develop from an unstable stratified flow through the evolution of small wavelength waves into large wavelength waves that have the possibility of growing to form a slug. The mechanism appears to be quite different for fluids with viscosities close to water than for fluids with large viscosities (20 centipoise).

  20. Shock initiation experiments on ratchet grown PBX 9502

    SciTech Connect

    Gustavsen, Richard L; Thompson, Darla G; Olinger, Barton W; Deluca, Racci; Bartram, Brian D; Pierce, Timothy H; Sanchez, Nathaniel J

    2010-01-01

    This study compares the shock initiation behavior of PBX 9502 pressed to less than nominal density (nominal density is 1.890 {+-} 0.005 g/cm{sup 3}) with PBX 9502 pressed to nominal density and then ''ratchet grown'' to low density. PBX 9502 is an insensitive plastic bonded explosive consisting of 95 weight % dry-aminated tri-amino-tri-nitro-benzene (TATB) and 5 weight % Kel-F 800 plastic binder. ''Ratchet growth'' - an irreversible increase in specific volume - occurs when an explosive based on TATB is temperature cycled. The design of our study is as follows: PBX 9502, all from the same lot, received the following four treatments. Samples in the first group were pressed to less than nominal density. These were not ratchet grown and used as a baseline. Samples in the second group were pressed to nominal density and then ratchet grown by temperature cycling 30 times between -54 C and +80 C. Samples in the final group were pressed to nominal density and cut into 100 mm by 25.4 mm diameter cylinders. During thermal cycling the cylinders were axially constrained by a 100 psi load. Samples for shock initiation experiments were cut perpendicular (disks) and parallel (slabs) to the axial load. The four sample groups can be summarized with the terms pressed low, ratchet grown/no load, axial load/disks, and axial load/slabs. All samples were shock initiated with nearly identical inputs in plate impact experiments carried out on a gas gun. Wave profiles were measured after propagation through 3, 4, 5, and 6 mm of explosive. Side by side comparison of wave profiles from different samples is used as a measure of relative sensitivity. All reduced density samples were more shock sensitive than nominal density PBX 9502. Differences in shock sensitivity between ratchet grown and pressed to low density PBX 9502 were small, but the low density pressings are slightly more sensitive than the ratchet grown samples.

  1. Effects of density on growth, metamorphosis, and survivorship in tadpoles of Scaphiopus holbrooki

    SciTech Connect

    Semlitsch, R.D.; Caldwell, J.P.

    1982-08-01

    Density-dependent aspects of growth, metamorphosis, and survivorship of Scaphiopus holbrooki tadpoles were examined in the laboratory under two experimental regimes. In the first density experiment, the growth index (W) of tadpoles decreased exponentially with density. Mean growth rate varied from 0.023 mL/d at the lowest density to 0.006 mL/d at the highest density. The mean number of days to metamorphic climax was positively associated with the initial density treatment: 27 d at the lowest density to 86 d at the highest density. The body size of tadpoles at metamorphosis showed a concave curvilinear relationship to initial density, indicating tadpoles at the highest densities are apparently capable to growth recovery once released from density stress. The survival of tadpoles decreased exponentially with initial density, from 90% at the lowest density to 20% at the highest initial density. In the second experiment a cross-classified design was used to examine the effects of density and duration of treatment (time) on growth and metamorphosis. Density and time had significant effects on body size at metamorphosis and days to metamorphosis. There was no significant interaction between density and time. These results indicate that the inhibitory effect of density stress varies with the duration of the stress. Scaphiopus holbrooki tadpoles exhibit developmental traits (rapid growth, short larval period, small body size at metamorphosis) that should be favored by natural selection in high density habitats. Dispersability may be a mechanism whereby S. holbrooki can minimize the detrimental effects of density stress.

  2. Precision flyer initiator

    DOEpatents

    Frank, Alan M.; Lee, Ronald S.

    1998-01-01

    A precision flyer initiator forms a substantially spherical detonation wave in a high explosive (HE) pellet. An explosive driver, such as a detonating cord, a wire bridge circuit or a small explosive, is detonated. A flyer material is sandwiched between the explosive driver and an end of a barrel that contains an inner channel. A projectile or "flyer" is sheared from the flyer material by the force of the explosive driver and projected through the inner channel. The flyer than strikes the HE pellet, which is supported above a second end of the barrel by a spacer ring. A gap or shock decoupling material delays the shock wave in the barrel from predetonating the HE pellet before the flyer. A spherical detonation wave is formed in the HE pellet. Thus, a shock wave traveling through the barrel fails to reach the HE pellet before the flyer strikes the HE pellet. The precision flyer initiator can be used in mining devices, well-drilling devices and anti-tank devices.

  3. Precision flyer initiator

    DOEpatents

    Frank, A.M.; Lee, R.S.

    1998-05-26

    A precision flyer initiator forms a substantially spherical detonation wave in a high explosive (HE) pellet. An explosive driver, such as a detonating cord, a wire bridge circuit or a small explosive, is detonated. A flyer material is sandwiched between the explosive driver and an end of a barrel that contains an inner channel. A projectile or ``flyer`` is sheared from the flyer material by the force of the explosive driver and projected through the inner channel. The flyer than strikes the HE pellet, which is supported above a second end of the barrel by a spacer ring. A gap or shock decoupling material delays the shock wave in the barrel from predetonating the HE pellet before the flyer. A spherical detonation wave is formed in the HE pellet. Thus, a shock wave traveling through the barrel fails to reach the HE pellet before the flyer strikes the HE pellet. The precision flyer initiator can be used in mining devices, well-drilling devices and anti-tank devices. 10 figs.

  4. Global cancer research initiative.

    PubMed

    Love, Richard R

    2010-05-03

    Cancer is an increasing problem for low- and middle-income countries undergoing an epidemiologic transition from dominantly acute communicable disease to more frequent chronic disease with increased public health successes in the former domain. Progress against cancer in high-income countries has been modest and has come at enormous expense. There are several well-conceived global policy and planning initiatives which, with adequate political will, can favorably impact the growing global cancer challenges. Most financial resources for cancer, however, are spent on diagnosis and management of patients with disease in circumstances where specific knowledge about effective approaches is significantly limited, and the majority of interventions, other than surgery, are not cost-effective in resource-limited countries by global standards. In summary, how to intervene effectively on a global scale for the majority of citizens who develop cancer is poorly defined. In contrast to technology-transfer approaches, markedly increased clinical research activities are more likely to benefit cancer sufferers. In these contexts, a global cancer research initiative is proposed, and mechanisms for realizing such an effort are suggested.

  5. Brazilian Nanotechnology Initiative

    NASA Astrophysics Data System (ADS)

    Fazzio, Adalberto

    2015-03-01

    In Brazil there is intense research activity in nanotechnology, most of these developed in universities and research institutes. The Brazilian Nanotechnology Initiative (BNI) aims to integrate government actions to promote the competitiveness of the Brazilian industry. This initiative is founded on support for research and development in the laboratories of the National Laboratories for Nanotechnology (SisNANO), starting from an improvement in infrastructure and opening of laboratories for users of academia and business, promoting interaction and transfer knowledge between academia and business. Country currently has 26 thematic networks of nanotechnology, 16 -Virtual-National Institutes of Technology, seven National- Laboratories and 18 Associate Laboratories, which comprise the SisNANO. Seeking to expand and share governance with other government actors, the Interministries Committee for Nanotechnology was set up, composed of 10 ministries, and has the task of coordinating the entire program of the Federal Government Nanotechnology.Cooperation activities are an important part of BNI. Currently Brazil has cooperation programs with U.S., China, Canada and European Union among others. Recently, Brazil decided to join the European NanoReg program where 60 research groups are joining efforts to provide protocols and standards that can help regulatory agencies and governments.

  6. Humane Neonatal Care Initiative.

    PubMed

    Levin, A

    1999-04-01

    The author has worked for many years in experimental departments in the former Soviet health system. Now, with integration into the western health system, many questions are being asked about high-technology neonatal medicine and whether it is sufficiently humane. The Baby Friendly Hospital Initiative (BFHI) movement is well known all over the world, but unfortunately it is only used for healthy children in maternity hospitals. A paradoxical situation has been created: the routines of maternity wards comply with the BFHI, whereas a neonatal intensive care unit in the same hospital may not meet the requirements of the BFHI. BFHI mainly cover breastfeeding in maternity hospitals. Humane Neonatal Care Initiatives include minimum aggressive therapy, minimum contact between sick newborns and medical staff, and maximum contact with mothers; the number of tests and examinations should be reduced to a minimum. Eleven steps towards the improvement of psychosocial and medical care in units for sick newborns are presented. This article is intended to provoke serious discussion. PMID:10342526

  7. Combat Wound Initiative program.

    PubMed

    Stojadinovic, Alexander; Elster, Eric; Potter, Benjamin K; Davis, Thomas A; Tadaki, Doug K; Brown, Trevor S; Ahlers, Stephen; Attinger, Christopher E; Andersen, Romney C; Burris, David; Centeno, Jose; Champion, Hunter; Crumbley, David R; Denobile, John; Duga, Michael; Dunne, James R; Eberhardt, John; Ennis, William J; Forsberg, Jonathan A; Hawksworth, Jason; Helling, Thomas S; Lazarus, Gerald S; Milner, Stephen M; Mullick, Florabel G; Owner, Christopher R; Pasquina, Paul F; Patel, Chirag R; Peoples, George E; Nissan, Aviram; Ring, Michael; Sandberg, Glenn D; Schaden, Wolfgang; Schultz, Gregory S; Scofield, Tom; Shawen, Scott B; Sheppard, Forest R; Stannard, James P; Weina, Peter J; Zenilman, Jonathan M

    2010-07-01

    The Combat Wound Initiative (CWI) program is a collaborative, multidisciplinary, and interservice public-private partnership that provides personalized, state-of-the-art, and complex wound care via targeted clinical and translational research. The CWI uses a bench-to-bedside approach to translational research, including the rapid development of a human extracorporeal shock wave therapy (ESWT) study in complex wounds after establishing the potential efficacy, biologic mechanisms, and safety of this treatment modality in a murine model. Additional clinical trials include the prospective use of clinical data, serum and wound biomarkers, and wound gene expression profiles to predict wound healing/failure and additional clinical patient outcomes following combat-related trauma. These clinical research data are analyzed using machine-based learning algorithms to develop predictive treatment models to guide clinical decision-making. Future CWI directions include additional clinical trials and study centers and the refinement and deployment of our genetically driven, personalized medicine initiative to provide patient-specific care across multiple medical disciplines, with an emphasis on combat casualty care. PMID:23634474

  8. Initiatives for proliferation prevention

    SciTech Connect

    1997-04-01

    Preventing the proliferation of weapons of mass destruction is a central part of US national security policy. A principal instrument of the Department of Energy`s (DOE`s) program for securing weapons of mass destruction technology and expertise and removing incentives for scientists, engineers and technicians in the newly independent states (NIS) of the former Soviet Union to go to rogue countries or assist terrorist groups is the Initiatives for Proliferation Prevention (IPP). IPP was initiated pursuant to the 1994 Foreign Operations Appropriations Act. IPP is a nonproliferation program with a commercialization strategy. IPP seeks to enhance US national security and to achieve nonproliferation objectives by engaging scientists, engineers and technicians from former NIS weapons institutes; redirecting their activities in cooperatively-developed, commercially viable non-weapons related projects. These projects lead to commercial and economic benefits for both the NIS and the US IPP projects are funded in Russian, Ukraine, Kazakhstan and Belarus. This booklet offers an overview of the IPP program as well as a sampling of some of the projects which are currently underway.

  9. Instrumented Pipeline Initiative

    SciTech Connect

    Thomas Piro; Michael Ream

    2010-07-31

    This report summarizes technical progress achieved during the cooperative agreement between Concurrent Technologies Corporation (CTC) and U.S. Department of Energy to address the need for a for low-cost monitoring and inspection sensor system as identified in the Department of Energy (DOE) National Gas Infrastructure Research & Development (R&D) Delivery Reliability Program Roadmap.. The Instrumented Pipeline Initiative (IPI) achieved the objective by researching technologies for the monitoring of pipeline delivery integrity, through a ubiquitous network of sensors and controllers to detect and diagnose incipient defects, leaks, and failures. This report is organized by tasks as detailed in the Statement of Project Objectives (SOPO). The sections all state the objective and approach before detailing results of work.

  10. The Knowledge Stealing Initiative?

    NASA Technical Reports Server (NTRS)

    Goshorn, Larry

    2005-01-01

    I have the honor of being on the Academy of Program and Project Leadership (APPL) Knowledge Sharing Feedback and Assessment Team (FAA), and as such, I am privileged to receive the feedback written by many of you as attendees of the Project Management (PM) Master s Forums. It is the intent of the FAA Team and APPL leadership to use this feedback as a tool for continuous program improvement. As a retired (sort of) PM in the payload contracting industry, I'm a big supporter of NASA s Knowledge Sharing Initiative (KSI), especially the Master's Forums. I really enjoy participating in them. Unfortunately I had to miss the 8th forum in Pasadena this past Spring, but I did get the feedback package for the Assessment Team work. So here I was, reviewing twelve pages of comments, reflections, learning notes and critiques from attendees of the 8th forum.

  11. The Gossamer Initiative

    NASA Technical Reports Server (NTRS)

    Chmielewski, Artur B.; Moore, Chris; Howard, Rick

    2000-01-01

    The Gossamer Spacecraft Initiative is a new NASA program to begin long-range development of enabling technologies for very large, ultra-lightweight structures and apertures. Large apertures include optical, infrared and submillimeter telescopes, "photon buckets" for optical communications and "non-coherent" imaging, solar concentrators, and radio frequency antennas. Developments in the very large ultra-light structures will be forces on one of their most challenging applications-solar sails. The sail structures will include both 3-axis stabilizing and spinning. Gossamer spacecraft technology will eventually allow NASA to undertake bold new missions of discovery, such as searching for the signs of life on planets orbiting nearby stars and sailing through space on beams of light of places beyond our solar system.

  12. Congress initiates science study

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    The U.S. House of Representatives announced in October a year-long study to review the nation's science and technology policy and the government's role in funding scientific research. The Science Policy Study, led by Rep. Vernon Ehlers (R-MI), is the first comprehensive review by Congress since 1985—a time when the Cold War still was being fought and the Internet was largely unknown.At a workshop to discuss the initiative, House Science Committee Chair James Sensenbrenner, Jr., told about 30 scientists and policy experts that the challenge is “to develop a new, sensible, coherent long-range science and technology policy, including a review of our nation's science and math education programs.”

  13. Breckinridge Project, initial effort

    SciTech Connect

    None, None

    1982-09-01

    Report III, Volume 1 contains those specifications numbered A through J, as follows: General Specifications (A); Specifications for Pressure Vessels (C); Specifications for Tanks (D); Specifications for Exchangers (E); Specifications for Fired Heaters (F); Specifications for Pumps and Drivers (G); and Specifications for Instrumentation (J). The standard specifications of Bechtel Petroleum Incorporated have been amended as necessary to reflect the specific requirements of the Breckinridge Project, and the more stringent specifications of Ashland Synthetic Fuels, Inc. These standard specifications are available to the Initial Effort (Phase Zero) work performed by all contractors and subcontractors. Report III, Volume 1 also contains the unique specifications prepared for Plants 8, 15, and 27. These specifications will be substantially reviewed during Phase I of the project, and modified as necessary for use during the engineering, procurement, and construction of this project.

  14. MONTANA PALLADIUM RESEARCH INITIATIVE

    SciTech Connect

    Peters, John; McCloskey, Jay; Douglas, Trevor; Young, Mark; Snyder, Stuart; Gurney, Brian

    2012-05-09

    Project Objective: The overarching objective of the Montana Palladium Research Initiative is to perform scientific research on the properties and uses of palladium in the context of the U.S. Department of Energy's Hydrogen, Fuel Cells and Infrastructure Technologies Program. The purpose of the research will be to explore possible palladium as an alternative to platinum in hydrogen-economy applications. To achieve this objective, the Initiatives activities will focus on several cutting-edge research approaches across a range of disciplines, including metallurgy, biomimetics, instrumentation development, and systems analysis. Background: Platinum-group elements (PGEs) play significant roles in processing hydrogen, an element that shows high potential to address this need in the U.S. and the world for inexpensive, reliable, clean energy. Platinum, however, is a very expensive component of current and planned systems, so less-expensive alternatives that have similar physical properties are being sought. To this end, several tasks have been defined under the rubric of the Montana Palladium Research Iniative. This broad swath of activities will allow progress on several fronts. The membrane-related activities of Task 1 employs state-of-the-art and leading-edge technologies to develop new, ceramic-substrate metallic membranes for the production of high-purity hydrogen, and develop techniques for the production of thin, defect-free platinum group element catalytic membranes for energy production and pollution control. The biomimetic work in Task 2 explores the use of substrate-attached hydrogen-producing enzymes and the encapsulation of palladium in virion-based protein coats to determine their utility for distributed hydrogen production. Task 3 work involves developing laser-induced breakdown spectroscopy (LIBS) as a real-time, in situ diagnostic technique to characterize PGEs nanoparticles for process monitoring and control. The systems engineering work in task 4 will

  15. The Enzyme Function Initiative.

    PubMed

    Gerlt, John A; Allen, Karen N; Almo, Steven C; Armstrong, Richard N; Babbitt, Patricia C; Cronan, John E; Dunaway-Mariano, Debra; Imker, Heidi J; Jacobson, Matthew P; Minor, Wladek; Poulter, C Dale; Raushel, Frank M; Sali, Andrej; Shoichet, Brian K; Sweedler, Jonathan V

    2011-11-22

    The Enzyme Function Initiative (EFI) was recently established to address the challenge of assigning reliable functions to enzymes discovered in bacterial genome projects; in this Current Topic, we review the structure and operations of the EFI. The EFI includes the Superfamily/Genome, Protein, Structure, Computation, and Data/Dissemination Cores that provide the infrastructure for reliably predicting the in vitro functions of unknown enzymes. The initial targets for functional assignment are selected from five functionally diverse superfamilies (amidohydrolase, enolase, glutathione transferase, haloalkanoic acid dehalogenase, and isoprenoid synthase), with five superfamily specific Bridging Projects experimentally testing the predicted in vitro enzymatic activities. The EFI also includes the Microbiology Core that evaluates the in vivo context of in vitro enzymatic functions and confirms the functional predictions of the EFI. The deliverables of the EFI to the scientific community include (1) development of a large-scale, multidisciplinary sequence/structure-based strategy for functional assignment of unknown enzymes discovered in genome projects (target selection, protein production, structure determination, computation, experimental enzymology, microbiology, and structure-based annotation), (2) dissemination of the strategy to the community via publications, collaborations, workshops, and symposia, (3) computational and bioinformatic tools for using the strategy, (4) provision of experimental protocols and/or reagents for enzyme production and characterization, and (5) dissemination of data via the EFI's Website, http://enzymefunction.org. The realization of multidisciplinary strategies for functional assignment will begin to define the full metabolic diversity that exists in nature and will impact basic biochemical and evolutionary understanding, as well as a wide range of applications of central importance to industrial, medicinal, and pharmaceutical efforts.

  16. Generating random density matrices

    NASA Astrophysics Data System (ADS)

    Życzkowski, Karol; Penson, Karol A.; Nechita, Ion; Collins, Benoît

    2011-06-01

    We study various methods to generate ensembles of random density matrices of a fixed size N, obtained by partial trace of pure states on composite systems. Structured ensembles of random pure states, invariant with respect to local unitary transformations are introduced. To analyze statistical properties of quantum entanglement in bi-partite systems we analyze the distribution of Schmidt coefficients of random pure states. Such a distribution is derived in the case of a superposition of k random maximally entangled states. For another ensemble, obtained by performing selective measurements in a maximally entangled basis on a multi-partite system, we show that this distribution is given by the Fuss-Catalan law and find the average entanglement entropy. A more general class of structured ensembles proposed, containing also the case of Bures, forms an extension of the standard ensemble of structureless random pure states, described asymptotically, as N → ∞, by the Marchenko-Pastur distribution.

  17. Low density microcellular foams

    DOEpatents

    LeMay, J.D.

    1991-11-19

    Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 [mu]m is produced. Also disclosed are the foams produced by the process. 8 figures.

  18. Low density microcellular foams

    DOEpatents

    LeMay, James D.

    1991-01-01

    Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

  19. Low density microcellular foams

    DOEpatents

    LeMay, James D.

    1992-01-01

    Disclosed is a process of producing microcellular from which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

  20. Variable-Density Tunnel

    NASA Technical Reports Server (NTRS)

    1921-01-01

    The outside pressure shell for the Variable-Density Tunnel (VDT). The shell, or 'tank' as it was called, was built in the Newport News Shipyard and traveled by barge to Langley. The tank could withstand a working pressure of 21 atmospheres. Elton Miller described it in NACA TR No. 227 (pp. 411-412): 'It is built of steel plates lapped and riveted according to the usual practice in steam boiler construction, although, because of the size of the tank and the high working pressure, the construction is unusually heavy. There is a cylindrical body portion of 2-1/8 inch (53.98 millimeters) steel plate with hemispherical ends 1-1/4 inches (31.75 millimeters) in thickness.'

  1. Interstellar Electron Density Spectra

    NASA Astrophysics Data System (ADS)

    Lambert, Hendrick Clark

    This study concerns the investigation of the form of the wavenumber spectrum of the Galactic electron density fluctuations through an examination of the scattering of the radio pulses emitted by pulsars as they propagate through the diffuse ionized interstellar gas. A widely used model for the electron density spectrum is based on the simple power-law: Pne(q)∝ q-β, where β = 11/3 is usually assumed, corresponding to Kolmogorov's turbulence spectrum. The simple Kolmogorov model provides satisfactory agreement for observations along many lines of sight; however, major inconsistencies remain. The inconsistencies suggest that an increase in the ratio of the power between the high (10-8[ m]-1≤ q<=10-7[ m]-1) and low (10-13[ m]-1≤ q<=10-12[ m]-1) wavenumbers is needed. This enhancement in the ratio can in turn be achieved by either including an inner scale, corresponding to a dissipation scale for the turbulent cascade, in the Kolmogorov spectrum or by considering steeper spectra. Spectra with spectral exponents β > 4 have been in general rejected based on observations of pulsar refractive scintillations. The special case of β = 4 has been given little attention and is analyzed in detail. Physically, this 'β = 4' model corresponds to the random distribution, both in location and orientation, of discrete objects with relatively sharp boundaries across the line of sight. An outer scale is included in the model to account for the average size of such objects. We compare the predictions of the inner-scale and β = 4 models both with published observations and observations we made as part of this investigation. We conclude that the form of the wavenumber spectrum is dependent on the line of sight. We propose a composite spectrum featuring a uniform background turbulence in presence of randomly distributed discrete objects, as modeled by the β = model.

  2. Low density microcellular foams

    DOEpatents

    Aubert, J.H.; Clough, R.L.; Curro, J.G.; Quintana, C.A.; Russick, E.M.; Shaw, M.T.

    1985-10-02

    Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the reusltant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 ..mu..m and a volume such that the foams have a length greater than 1 cm are provided.

  3. Low density microcellular foams

    DOEpatents

    Aubert, James H.; Clough, Roger L.; Curro, John G.; Quintana, Carlos A.; Russick, Edward M.; Shaw, Montgomery T.

    1987-01-01

    Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the resultant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Means for subjecting such a solvent to one-dimensional cooling are also provided. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 .mu.m and a volume such that the foams have a length greater than 1 cm are provided.

  4. Kazakhstan Space Weather Initiative

    NASA Astrophysics Data System (ADS)

    Kryakunova, Olga

    2012-07-01

    Kazakhstan experimental complex is a center of experimental study of space weather. This complex is situated near Almaty, Kazakhstan and includes experimental setup for registration of cosmic ray intensity (neutron monitor) at altitude of 3340 m above sea level, geomagnetic observatory and setup for registration of solar flux density with frequency of 1 and 3 GHz with 1 second time resolution. Results of space environment monitoring in real time are accessible via Internet. This experimental information is used for space weather investigations and different cosmic ray effects. Almaty mountain cosmic ray station is one of the most suitable and sensitive stations for investigation and forecasting of the dangerous situations for satellites; for this reason Almaty cosmic ray station is included in the world-wide neutron monitor network for the real-time monitoring of the space weather conditions and European Database NMDB (www.nmdb.eu). All data are represented on the web-site of the Institute of Ionosphere (www.ionos.kz) in real time. Since July, 2006 the space environment prediction laboratory represents the forecast of geomagnetic activity every day on the same site (www.ionos.kz/?q=en/node/21).

  5. Steric Effects of the Initiator Substituent Position on the Externally Initiated Polymerization of 2-Bromo-5-iodo-3-hexylthiophene

    SciTech Connect

    Doubina, Natalia; Paniagua, Sergio A.; Soldatova, Alexandra V.; Jen, Alex K. Y.; Marder, Seth R.; Luscombe, Christine K.

    2011-01-12

    Externally initiated polymerization of 2-bromo-3-hexyl-5-iodothiophene was attempted from four aryl and thiophene based small molecule initiators functionalized with a phosphonate moiety. Initiated poly(3-hexylthiophene) product was obtained in various yields depending on the nature of the initiating molecule. Reaction intermediates for the oxidative addition and the ligand exchange steps were analyzed utilizing both experimental and theoretical methods. It was observed that an ortho substituent plays a crucial role in the outcome of the polymerization mechanism and that aryl based initiators are generally more stable than thiophene based initiators. Density functional theory (DFT) calculations revealed the importance of the steric effects on the success of the externally initiated chain growth polymerization mechanism.

  6. Intermolecular electrostatic energies using density fitting.

    PubMed

    Cisneros, G Andrés; Piquemal, Jean-Philip; Darden, Thomas A

    2005-07-22

    A method is presented to calculate the electron-electron and nuclear-electron intermolecular Coulomb interaction energy between two molecules by separately fitting the unperturbed molecular electron density of each monomer. This method is based on the variational Coulomb fitting method which relies on the expansion of the ab initio molecular electron density in site-centered auxiliary basis sets. By expanding the electron density of each monomer in this way the integral expressions for the intermolecular electrostatic calculations are simplified, lowering the operation count as well as the memory usage. Furthermore, this method allows the calculation of intermolecular Coulomb interactions with any level of theory from which a one-electron density matrix can be obtained. Our implementation is initially tested by calculating molecular properties with the density fitting method using three different auxiliary basis sets and comparing them to results obtained from ab initio calculations. These properties include dipoles for a series of molecules, as well as the molecular electrostatic potential and electric field for water. Subsequently, the intermolecular electrostatic energy is tested by calculating ten stationary points on the water dimer potential-energy surface. Results are presented for electron densities obtained at four different levels of theory using two different basis sets, fitted with three auxiliary basis sets. Additionally, a one-dimensional electrostatic energy surface scan is performed for four different systems (H2O dimer, Mg2+-H2O, Cu+-H2O, and n-methyl-formamide dimer). Our results show a very good agreement with ab initio calculations for all properties as well as interaction energies.

  7. Local-density-driven clustered star formation

    NASA Astrophysics Data System (ADS)

    Parmentier, G.; Pfalzner, S.

    2013-01-01

    Context. A positive power-law trend between the local surface densities of molecular gas, Σgas, and young stellar objects, Σ ⋆ , in molecular clouds of the solar neighbourhood has recently been identified. How it relates to the properties of embedded clusters, in particular to the recently established radius-density relation, has so far not been investigated. Aims: We model the development of the stellar component of molecular clumps as a function of time and initial local volume density. Our study provides a coherent framework able to explain both the molecular-cloud and embedded-cluster relations quoted above. Methods: We associate the observed volume density gradient of molecular clumps to a density-dependent free-fall time. The molecular clump star formation history is obtained by applying a constant star formation efficiency per free-fall time, ɛff. Results: For the volume density profiles typical of observed molecular clumps (i.e. power-law slope ≃ -1.7), our model gives a star-gas surface-density relation of the form Σ⋆ ∝ Σgas2, which agrees very well with the observations. Taking the case of a molecular clump of mass M0 ≃ 104 M⊙ and radius R ≃ 6 pc experiencing star formation during 2 Myr, we derive what star formation efficiency per free-fall time matches the normalizations of the observed and predicted (Σ ⋆ , Σgas) relations best. We find ɛff ≃ 0.1. We show that the observed growth of embedded clusters, embodied by their radius-density relation, corresponds to a surface density threshold being applied to developing star-forming regions. The consequences of our model in terms of cluster survivability after residual star-forming gas expulsion are that, owing to the locally high star formation efficiency in the inner part of star-forming regions, global star formation efficiency as low as 10% can lead to the formation of bound gas-free star clusters.

  8. Shock Initiation of Damaged Explosives

    SciTech Connect

    Chidester, S K; Vandersall, K S; Tarver, C M

    2009-10-22

    Explosive and propellant charges are subjected to various mechanical and thermal insults that can increase their sensitivity over the course of their lifetimes. To quantify this effect, shock initiation experiments were performed on mechanically and thermally damaged LX-04 (85% HMX, 15% Viton by weight) and PBX 9502 (95% TATB, 5% Kel-F by weight) to obtain in-situ manganin pressure gauge data and run distances to detonation at various shock pressures. We report the behavior of the HMX-based explosive LX-04 that was damaged mechanically by applying a compressive load of 600 psi for 20,000 cycles, thus creating many small narrow cracks, or by cutting wedge shaped parts that were then loosely reassembled, thus creating a few large cracks. The thermally damaged LX-04 charges were heated to 190 C for long enough for the beta to delta solid - solid phase transition to occur, and then cooled to ambient temperature. Mechanically damaged LX-04 exhibited only slightly increased shock sensitivity, while thermally damaged LX-04 was much more shock sensitive. Similarly, the insensitive explosive PBX 9502 was mechanically damaged using the same two techniques. Since PBX 9502 does not undergo a solid - solid phase transition but does undergo irreversible or 'rachet' growth when thermally cycled, thermal damage to PBX 9502 was induced by this procedure. As for LX-04, the thermally damaged PBX 9502 demonstrated a greater shock sensitivity than mechanically damaged PBX 9502. The Ignition and Growth reactive flow model calculated the increased sensitivities by igniting more damaged LX-04 and PBX 9502 near the shock front based on the measured densities (porosities) of the damaged charges.

  9. Research initiatives in Mauritius.

    PubMed

    Persand, Sharveen

    2005-01-15

    Mauritius forms part of the Mascarene Islands of the Indian Ocean and is situated ca. 700 km to the east of Madagascar at latitude 20 degrees S and longitude 57.5 degrees E. Mauritius has jurisdiction over a proclaimed Exclusive Economic Zone that stretches over 1,900,000 km2. This extensive area holds an immense potential for exploration and presents a wide range of scientific and industrial challenges and opportunities. At present, ocean-related activities are undertaken by various governmental and para-statal institutions as well as non-governmental organizations. Mauritius recognizes the need to coordinate all efforts in order to eliminate wasteful duplication and focus on potential for development, and this has seen the establishment of different forums and committees. This paper gives a brief overview of the different institutions involved in marine science and oceanography in Mauritius and lists the major projects that are being undertaken as well as some of the projects or new research initiatives that are in the pipeline.

  10. Scientific Component Technology Initiative

    SciTech Connect

    Kohn, S; Bosl, B; Dahlgren, T; Kumfert, G; Smith, S

    2003-02-07

    The laboratory has invested a significant amount of resources towards the development of high-performance scientific simulation software, including numerical libraries, visualization, steering, software frameworks, and physics packages. Unfortunately, because this software was not designed for interoperability and re-use, it is often difficult to share these sophisticated software packages among applications due to differences in implementation language, programming style, or calling interfaces. This LDRD Strategic Initiative investigated and developed software component technology for high-performance parallel scientific computing to address problems of complexity, re-use, and interoperability for laboratory software. Component technology is an extension of scripting and object-oriented software development techniques that specifically focuses on the needs of software interoperability. Component approaches based on CORBA, COM, and Java technologies are widely used in industry; however, they do not support massively parallel applications in science and engineering. Our research focused on the unique requirements of scientific computing on ASCI-class machines, such as fast in-process connections among components, language interoperability for scientific languages, and data distribution support for massively parallel SPMD components.

  11. Research initiatives in Mauritius.

    PubMed

    Persand, Sharveen

    2005-01-15

    Mauritius forms part of the Mascarene Islands of the Indian Ocean and is situated ca. 700 km to the east of Madagascar at latitude 20 degrees S and longitude 57.5 degrees E. Mauritius has jurisdiction over a proclaimed Exclusive Economic Zone that stretches over 1,900,000 km2. This extensive area holds an immense potential for exploration and presents a wide range of scientific and industrial challenges and opportunities. At present, ocean-related activities are undertaken by various governmental and para-statal institutions as well as non-governmental organizations. Mauritius recognizes the need to coordinate all efforts in order to eliminate wasteful duplication and focus on potential for development, and this has seen the establishment of different forums and committees. This paper gives a brief overview of the different institutions involved in marine science and oceanography in Mauritius and lists the major projects that are being undertaken as well as some of the projects or new research initiatives that are in the pipeline. PMID:15598638

  12. Urban Environment Initiative

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The Urban Environment Initiative (UEI), has been established as part of a Cooperative Agreement with the National Aeronautics and Space Administration (NASA). The UEI is part of NASA's overall High Performance Computing and Communications (HPCC) and the Information Infrastructure Technology Applications (IITA) programs. The goal of the UEI is to provide public access to Earth Science information and promote its use with a focus on the environment of urban areas. This goal will be accomplished through collaborative efforts of the UEI team with both community-based and local/regional governmental organizations. The UEI team is comprised of four organizations representing private industry, NASA, and universities: Prime Technologies Service Corporation, NASA's Minority University Space Interdisciplinary Network (MU-SPIN) California State University, at Los Angeles, and Central State University (Wilberforce, OH). "Urban Environment" refers to the web of environmental, economic, and social factors that combine to create the urban world in which we live. Examples of these factors are population distribution, neighborhood demographic profiles, economic resources, business activities, location and concentration of environmental hazards and various pollutants, proximity and level of urban services, which form the basis of the urban environment and ultimately affect our lives and experiences. The use of Geographic Information Systems (GIS) and remote sensing allows data to be visualized in the forms of maps and spatial images. The use of these tools allow analysis of information about urban environments. Also included are descriptions of the four query types which will assist in understanding the maps.

  13. Reorientation of elongated particles at density interfaces.

    PubMed

    Doostmohammadi, A; Ardekani, A M

    2014-09-01

    Density interfaces in the water column are ubiquitously found in oceans and lakes. Interaction of settling particles with pycnoclines plays a pivotal function in nutrient transport between ocean layers and settling rates of marine particles. We perform direct numerical simulations of an elongated particle settling through a density interface and scrutinize the role of stratification on the settling dynamics. It is found that the presence of the density interface tends to turn the long axis of an elongated particle parallel to the settling direction, which is dramatically different from its counterpart in a homogeneous fluid. Although broadside-on settling of the elongated particle is enhanced upon approaching the interface, the long axis rotates toward the settling direction as the particle passes through the interface. We quantify turning couples due to stratification effects, which counteract the pressure-induced torques due to the fluid inertia. A similar behavior is observed for different initial orientations of the particle. It is shown that the reorientation of an elongated particle occurs in both sharp and linear density stratifications. PMID:25314535

  14. Density sensitive hashing.

    PubMed

    Jin, Zhongming; Li, Cheng; Lin, Yue; Cai, Deng

    2014-08-01

    Nearest neighbor search is a fundamental problem in various research fields like machine learning, data mining and pattern recognition. Recently, hashing-based approaches, for example, locality sensitive hashing (LSH), are proved to be effective for scalable high dimensional nearest neighbor search. Many hashing algorithms found their theoretic root in random projection. Since these algorithms generate the hash tables (projections) randomly, a large number of hash tables (i.e., long codewords) are required in order to achieve both high precision and recall. To address this limitation, we propose a novel hashing algorithm called density sensitive hashing (DSH) in this paper. DSH can be regarded as an extension of LSH. By exploring the geometric structure of the data, DSH avoids the purely random projections selection and uses those projective functions which best agree with the distribution of the data. Extensive experimental results on real-world data sets have shown that the proposed method achieves better performance compared to the state-of-the-art hashing approaches.

  15. Density of intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Slabe, Melissa E.

    1990-01-01

    The density of Amoco P-55, P-75, P-100, and P-120 pitch-based graphite fibers and their intercalation compounds with bromine, iodine monochloride, and copper (II) chloride have been measured using a density gradient column. The distribution of densities within a fiber type is found to be a sensitive indicator of the quality of the intercalation reaction. In all cases the density was found to increase, indicating that the mass added to the graphite is dominant over fiber expansion. Density increases are small (less than 10 percent) giving credence to a model of the intercalated graphite fibers which have regions which are intercalated and regions which are not.

  16. Density of intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Slabe, Melissa E.

    1989-01-01

    The density of Amoco P-55, P-75, P-100, and P-120 pitch-based graphite fibers and their intercalation compounds with bromine, iodine monochloride, and copper (II) chloride have been measured using a density gradient column. The distribution of densities within a fiber type is found to be a sensitive indicator of the quality of the intercalation reaction. In all cases the density was found to increase, indicating that the mass added to the graphite is dominant over fiber expansion. Density increases are small (less than 10 percent) giving credence to a model of the intercalated graphite fibers which have regions which are intercalated and regions which are not.

  17. Carbon nanotube growth density control

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  18. Two-point density correlations of quasicondensates in free expansion

    SciTech Connect

    Manz, S.; Buecker, R.; Betz, T.; Koller, Ch.; Schmiedmayer, J.; Hofferberth, S.; Demler, E.; Mazets, I. E.; Imambekov, A.; Perrin, A.; Schumm, T.

    2010-03-15

    We measure the two-point density correlation function of freely expanding quasicondensates in the weakly interacting quasi-one-dimensional (1D) regime. While initially suppressed in the trap, density fluctuations emerge gradually during expansion as a result of initial phase fluctuations present in the trapped quasicondensate. Asymptotically, they are governed by the thermal coherence length of the system. Our measurements take place in an intermediate regime where density correlations are related to near-field diffraction effects and anomalous correlations play an important role. Comparison with a recent theoretical approach described by Imambekov et al. yields good agreement with our experimental results and shows that density correlations can be used for thermometry of quasicondensates.

  19. Density matters: The semiconservative replication of DNA

    PubMed Central

    Hanawalt, Philip C.

    2004-01-01

    The semiconservative mode of DNA replication was originally documented through the classic density labeling experiments of Matthew Meselson and Franklin W. Stahl, as communicated to PNAS by Max Delbrück in May 1958. The ultimate value of their novel approach has extended far beyond the initial implications from that elegant study, through more than four decades of research on DNA replication, recombination, and repair. I provide here a short historical commentary and then an account of some developments in the field of DNA replication, which closely followed the Meselson–Stahl experiment. These developments include the application of density labeling to discover the repair replication of damaged DNA, a “nonconservative” mode of synthesis in which faulty sections of DNA are replaced. PMID:15608066

  20. Density matters: the semiconservative replication of DNA.

    PubMed

    Hanawalt, Philip C

    2004-12-28

    The semiconservative mode of DNA replication was originally documented through the classic density labeling experiments of Matthew Meselson and Franklin W. Stahl, as communicated to PNAS by Max Delbruck in May 1958. The ultimate value of their novel approach has extended far beyond the initial implications from that elegant study, through more than four decades of research on DNA replication, recombination, and repair. I provide here a short historical commentary and then an account of some developments in the field of DNA replication, which closely followed the Meselson-Stahl experiment. These developments include the application of density labeling to discover the repair replication of damaged DNA, a "nonconservative" mode of synthesis in which faulty sections of DNA are replaced.

  1. Density of Mars' south polar layered deposits.

    PubMed

    Zuber, Maria T; Phillips, Roger J; Andrews-Hanna, Jeffrey C; Asmar, Sami W; Konopliv, Alexander S; Lemoine, Frank G; Plaut, Jeffrey J; Smith, David E; Smrekar, Suzanne E

    2007-09-21

    Both poles of Mars are hidden beneath caps of layered ice. We calculated the density of the south polar layered deposits by combining the gravity field obtained from initial results of radio tracking of the Mars Reconnaissance Orbiter with existing surface topography from the Mars Orbiter Laser Altimeter on the Mars Global Surveyor spacecraft and basal topography from the Mars Advanced Radar for Subsurface and Ionospheric Sounding on the Mars Express spacecraft. The results indicate a best-fit density of 1220 kilograms per cubic meter, which is consistent with water ice that has approximately 15% admixed dust. The results demonstrate that the deposits are probably composed of relatively clean water ice and also refine the martian surface-water inventory.

  2. Morphology driven density distribution estimation for small bodies

    NASA Astrophysics Data System (ADS)

    Takahashi, Yu; Scheeres, D. J.

    2014-05-01

    We explore methods to detect and characterize the internal mass distribution of small bodies using the gravity field and shape of the body as data, both of which are determined from orbit determination process. The discrepancies in the spherical harmonic coefficients are compared between the measured gravity field and the gravity field generated by homogeneous density assumption. The discrepancies are shown for six different heterogeneous density distribution models and two small bodies, namely 1999 KW4 and Castalia. Using these differences, a constraint is enforced on the internal density distribution of an asteroid, creating an archive of characteristics associated with the same-degree spherical harmonic coefficients. Following the initial characterization of the heterogeneous density distribution models, a generalized density estimation method to recover the hypothetical (i.e., nominal) density distribution of the body is considered. We propose this method as the block density estimation, which dissects the entire body into small slivers and blocks, each homogeneous within itself, to estimate their density values. Significant similarities are observed between the block model and mass concentrations. However, the block model does not suffer errors from shape mismodeling, and the number of blocks can be controlled with ease to yield a unique solution to the density distribution. The results show that the block density estimation approximates the given gravity field well, yielding higher accuracy as the resolution of the density map is increased. The estimated density distribution also computes the surface potential and acceleration within 10% for the particular cases tested in the simulations, the accuracy that is not achievable with the conventional spherical harmonic gravity field. The block density estimation can be a useful tool for recovering the internal density distribution of small bodies for scientific reasons and for mapping out the gravity field

  3. Gamma densitometer for measuring Pu density in fuel tubes

    SciTech Connect

    Winn, W.G.

    1982-01-01

    A fuel-gamma-densitometer (FGD) has been developed to examine nondestructively the uniformity of plutonium in aluminum-clad fuel tubes at the Savannah River Plant (SRP). The monitoring technique is ..gamma..-ray spectroscopy with a lead-collimated Ge(Li) detector. Plutonium density is correlated with the measured intensity of the 208 keV ..gamma..-ray from /sup 237/U (7d) of the /sup 241/Pu (15y) decay chain. The FGD measures the plutonium density within 0.125- or 0.25-inch-diameter areas of the 0.133- to 0.183-inch-thick tube walls. Each measurement yields a density ratio that relates the plutonium density of the measured area to the plutonium density in normal regions of the tube. The technique was used to appraise a series of fuel tubes to be irradated in an SRP reactor. High-density plutonium areas were initially identified by x-ray methods and then examined quantitatively with the FGD. The FGD reliably tested fuel tubes and yielded density ratios over a range of 0.0 to 2.5. FGD measurements examined (1) nonuniform plutonium densities or hot spots, (2) uniform high-density patches, and (3) plutonium density distribution in thin cladding regions. Measurements for tubes with known plutonium density agreed with predictions to within 2%. Attenuation measurements of the 208-keV ..gamma..-ray passage through the tube walls agreed to within 2 to 3% of calculated predictions. Collimator leakage measurements agreed with model calculations that predicted less than a 1.5% effect on plutonium density ratios. Finally, FGD measurements correlated well with x-ray transmission and fluoroscopic measurements. The data analysis for density ratios involved a small correction of about 10% for ..gamma..-shielding within the fuel tube. For hot spot examinations, limited information for this correction dictated a density ratio uncertainty of 3 to 5%.

  4. The Initial Physical Conditions of Kepler-36 b and c

    NASA Astrophysics Data System (ADS)

    Owen, James E.; Morton, Timothy. D.

    2016-03-01

    The Kepler-36 planetary system consists of two exoplanets at similar separations (0.115 and 0.128 au), which have dramatically different densities. The inner planet has a density consistent with an Earth-like composition, while the outer planet is extremely low density, such that it must contain a voluminous H/He envelope. Such a density difference would pose a problem for any formation mechanism if their current densities were representative of their composition at formation. However, both planets are at close enough separations to have undergone significant evaporation in the past. We constrain the core mass, core composition, initial envelope mass, and initial cooling time of each planet using evaporation models conditioned on their present-day masses and radii, as inferred from Kepler photometry and transit timing analysis. The inner planet is consistent with being an evaporatively stripped core, while the outer planet has retained some of its initial envelope due to its higher core mass. Therefore, both planets could have had a similar formation pathway, with the inner planet having an initial envelope-mass fraction of ≲10% and core mass of ˜4.4 M⊕, while the outer had an initial envelope-mass fraction of the order of 15%-30% and core mass ˜7.3 M⊕. Finally, our results indicate that the outer planet had a long (≳30 Myr) initial cooling time, much longer than would naively be predicted from simple timescale arguments. The long initial cooling time could be evidence for a dramatic early cooling episode such as the recently proposed “boil-off” process.

  5. 40 CFR 63.5395 - How do I measure the density of a finish?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Initial Compliance Requirements § 63.5395 How do I measure the density of a finish? (a) To determine the density of a finish, the reference method is EPA Method 24 of appendix A of 40 CFR part 60. You may use... 40 Protection of Environment 12 2011-07-01 2009-07-01 true How do I measure the density of...

  6. 40 CFR 63.5395 - How do I measure the density of a finish?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and Initial Compliance Requirements § 63.5395 How do I measure the density of a finish? (a) To determine the density of a finish, the reference method is EPA Method 24 of appendix A of 40 CFR part 60... 40 Protection of Environment 13 2014-07-01 2014-07-01 false How do I measure the density of...

  7. 40 CFR 63.5395 - How do I measure the density of a finish?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and Initial Compliance Requirements § 63.5395 How do I measure the density of a finish? (a) To determine the density of a finish, the reference method is EPA Method 24 of appendix A of 40 CFR part 60... 40 Protection of Environment 13 2012-07-01 2012-07-01 false How do I measure the density of...

  8. 40 CFR 63.5395 - How do I measure the density of a finish?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... and Initial Compliance Requirements § 63.5395 How do I measure the density of a finish? (a) To determine the density of a finish, the reference method is EPA Method 24 of appendix A of 40 CFR part 60... 40 Protection of Environment 13 2013-07-01 2012-07-01 true How do I measure the density of...

  9. Method for determining transport critical current densities and flux penetration depth in bulk superconductors

    NASA Technical Reports Server (NTRS)

    Israelsson, Ulf E. (Inventor); Strayer, Donald M. (Inventor)

    1992-01-01

    A contact-less method for determining transport critical current density and flux penetration depth in bulk superconductor material. A compressor having a hollow interior and a plunger for selectively reducing the free space area for distribution of the magnetic flux therein are formed of superconductor material. Analytical relationships, based upon the critical state model, Maxwell's equations and geometrical relationships define transport critical current density and flux penetration depth in terms of the initial trapped magnetic flux density and the ratio between initial and final magnetic flux densities whereby data may be reliably determined by means of the simple test apparatus for evaluating the current density and flux penetration depth.

  10. Initial Radionuclide Inventories

    SciTech Connect

    Miller, H

    2005-07-12

    The purpose of this analysis is to provide an initial radionuclide inventory (in grams per waste package) and associated uncertainty distributions for use in the Total System Performance Assessment for the License Application (TSPA-LA) in support of the license application for the repository at Yucca Mountain, Nevada. This document is intended for use in postclosure analysis only. Bounding waste stream information and data were collected that capture probable limits. For commercially generated waste, this analysis considers alternative waste stream projections to bound the characteristics of wastes likely to be encountered using arrival scenarios that potentially impact the commercial spent nuclear fuel (CSNF) waste stream. For TSPA-LA, this radionuclide inventory analysis considers U.S. Department of Energy (DOE) high-level radioactive waste (DHLW) glass and two types of spent nuclear fuel (SNF): CSNF and DOE-owned (DSNF). These wastes are placed in two groups of waste packages: the CSNF waste package and the codisposal waste package (CDSP), which are designated to contain DHLW glass and DSNF, or DHLW glass only. The radionuclide inventory for naval SNF is provided separately in the classified ''Naval Nuclear Propulsion Program Technical Support Document'' for the License Application. As noted previously, the radionuclide inventory data presented here is intended only for TSPA-LA postclosure calculations. It is not applicable to preclosure safety calculations. Safe storage, transportation, and ultimate disposal of these wastes require safety analyses to support the design and licensing of repository equipment and facilities. These analyses will require radionuclide inventories to represent the radioactive source term that must be accommodated during handling, storage and disposition of these wastes. This analysis uses the best available information to identify the radionuclide inventory that is expected at the last year of last emplacement, currently identified as

  11. Initial Radionuclide Inventories

    SciTech Connect

    H. Miller

    2004-09-19

    The purpose of this analysis is to provide an initial radionuclide inventory (in grams per waste package) and associated uncertainty distributions for use in the Total System Performance Assessment for the License Application (TSPA-LA) in support of the license application for the repository at Yucca Mountain, Nevada. This document is intended for use in postclosure analysis only. Bounding waste stream information and data were collected that capture probable limits. For commercially generated waste, this analysis considers alternative waste stream projections to bound the characteristics of wastes likely to be encountered using arrival scenarios that potentially impact the commercial spent nuclear fuel (CSNF) waste stream. For TSPA-LA, this radionuclide inventory analysis considers U.S. Department of Energy (DOE) high-level radioactive waste (DHLW) glass and two types of spent nuclear fuel (SNF): CSNF and DOE-owned (DSNF). These wastes are placed in two groups of waste packages: the CSNF waste package and the codisposal waste package (CDSP), which are designated to contain DHLW glass and DSNF, or DHLW glass only. The radionuclide inventory for naval SNF is provided separately in the classified ''Naval Nuclear Propulsion Program Technical Support Document'' for the License Application. As noted previously, the radionuclide inventory data presented here is intended only for TSPA-LA postclosure calculations. It is not applicable to preclosure safety calculations. Safe storage, transportation, and ultimate disposal of these wastes require safety analyses to support the design and licensing of repository equipment and facilities. These analyses will require radionuclide inventories to represent the radioactive source term that must be accommodated during handling, storage and disposition of these wastes. This analysis uses the best available information to identify the radionuclide inventory that is expected at the last year of last emplacement, currently identified as

  12. Initial Cladding Condition

    SciTech Connect

    E. Siegmann

    2000-08-22

    The purpose of this analysis is to describe the condition of commercial Zircaloy clad fuel as it is received at the Yucca Mountain Project (YMP) site. Most commercial nuclear fuel is encased in Zircaloy cladding. This analysis is developed to describe cladding degradation from the expected failure modes. This includes reactor operation impacts including incipient failures, potential degradation after reactor operation during spent fuel storage in pool and dry storage and impacts due to transportation. Degradation modes include cladding creep, and delayed hydride cracking during dry storage and transportation. Mechanical stresses from fuel handling and transportation vibrations are also included. This Analysis and Model Report (AMR) does not address any potential damage to assemblies that might occur at the YMP surface facilities. Ranges and uncertainties have been defined. This analysis will be the initial boundary condition for the analysis of cladding degradation inside the repository. In accordance with AP-2.13Q, ''Technical Product Development Planning'', a work plan (CRWMS M&O 2000c) was developed, issued, and utilized in the preparation of this document. There are constraints, caveats and limitations to this analysis. This cladding degradation analysis is based on commercial Pressurized Water Reactor (PWR) fuel with Zircaloy cladding but is applicable to Boiling Water Reactor (BWR) fuel. Reactor operating experience for both PWRs and BWRs is used to establish fuel reliability from reactor operation. It is limited to fuel exposed to normal operation and anticipated operational occurrences (i.e. events which are anticipated to occur within a reactor lifetime), and not to fuel that has been exposed to severe accidents. Fuel burnup projections have been limited to the current commercial reactor licensing environment with restrictions on fuel enrichment, oxide coating thickness and rod plenum pressures. The information provided in this analysis will be used in

  13. Breckinridge Project, initial effort

    SciTech Connect

    1982-01-01

    This report presents an overview of the Breckinridge Project and summarizes the results achieved during the development phase of the project performed under a Cooperative Agreement with the United States Department of Energy. The Breckinridge Project provides for the design, construction and operation of a 50,000 barrel per day coal liquefaction facility in Breckinridge County, Kentucky. The development of the basic technology used in the Breckinridge Project dates back to the late 1950's and the invention by Hydrocarbon Research, Inc., (HRI) of the ebullated-bed reactor and the H-OIL process. The H-COAL process is based on the H-OIL technology. This coal liquefaction process produces clean low-sulfur petroleum substitutes suitable for most types of hydrocarbon-based fuel and chemical uses regardless of the sulfur content of the coal. A large H-COAL Pilot Plant in operation at Catlettsburg, Kentucky, is converting 220 tons of coal per day into 600 barrels of distillate products by catalytic hydrogenation. The estimated capital cost of the commercial facility is $3.17 billion, and the associated out-of-pocket operating cost is $18 per barrel, both in January 1981 dollars. Financial analysis shows the project to be an attractive investment under certain leveraged conditions which are possible through the assistance of the Synthetic Fuels Corporation. Ashland Synthetic Fuels, Inc. is currently working with the Synthetic Fuels Corporation and potential partners to develop financing for the commercial venture. Critical permits are being obtained and an Environmental Impact Statement is being prepared pursuant to initiating site preparation in early 1983. Commercial operations are expected to start up in early 1988.

  14. Whistler and FLR density calibration

    NASA Astrophysics Data System (ADS)

    Lichtenberger, János; Vellante, Massimo; Heilig, Balázs; Ferencz, Csaba; Regi, Mauro; Clilverd, Mark; Juhász, Lilla

    2014-05-01

    One of the major objective in PLASMON (http://plasmon.elte.hu) project is to provide plasma densities for data assimilative modeling of plasmasphere from two ground based measurements: whistlers and field line resonances (FLRs). The whistler inversion method used in this procedure includes various model, including wave propagation, magnetic field, field aligned density distribution and equatorial electron density models. The latter one is a special one used for multiple-path whistler groups. As one can obtain electron densities from whistler inversion and plasma mass densities from FLRs, the ion composition would be required to connect the to dataset (that are intended to use in the plasmasphere model), which is rarely known or available. Therefore we have developed a method for cross calibration of the data from two sources. It is based on physics based and experimental field aligned plasma density distribution models as well as on comparison with in situ wave and density (IMAGE and Van Allen Probes) measurements.

  15. Sustainable Forest Bioenergy Initiative

    SciTech Connect

    Breger, Dwayne; Rizzo, Rob

    2011-09-20

    In the state’s Electricity Restructuring Act of 1998, the Commonwealth of Massachusetts recognized the opportunity and strategic benefits to diversifying its electric generation capacity with renewable energy. Through this legislation, the Commonwealth established one of the nation’s first Renewable Energy Portfolio Standard (RPS) programs, mandating the increasing use of renewable resources in its energy mix. Bioenergy, meeting low emissions and advanced technology standards, was recognized as an eligible renewable energy technology. Stimulated by the state’s RPS program, several project development groups have been looking seriously at building large woody biomass generation units in western Massachusetts to utilize the woody biomass resource. As a direct result of this development, numerous stakeholders have raised concerns and have prompted the state to take a leadership position in pursuing a science based analysis of biomass impacts on forest and carbon emissions, and proceed through a rulemaking process to establish prudent policy to support biomass development which can contribute to the state’s carbon reduction commitments and maintain safeguards for forest sustainability. The Massachusetts Sustainable Forest Bioenergy Initiative (SFBI) was funded by the Department of Energy and started by the Department of Energy Resources before these contentious biomass issues were fully raised in the state, and continued throughout the substantive periods of this policy development. Thereby, while SFBI maintained its focus on the initially proposed Scope of Work, some aspects of this scope were expanded or realigned to meet the needs for groundbreaking research and policy development being advanced by DOER. SFBI provided DOER and the Commonwealth with a foundation of state specific information on biomass technology and the biomass industry and markets, the most comprehensive biomass fuel supply assessment for the region, the economic development impact

  16. The ion composition of cooling, variable-density interstellar gas

    NASA Astrophysics Data System (ADS)

    Suchkov, A. A.; Shchekinov, Y. A.

    1986-06-01

    The ion composition of rarefied interstellar gas cooling from about one million K to about 10,000 K is calculated. The time dependence of logarithmic relative ion densities is determined in an isobaric-cooling model and in a model with an initial adiabatic expansion. It is shown that so long as T is greater than 10,000 K, the N(C IV)/N(O VI) ion density ratio may be used to test the origin of nonstable behavior.

  17. Relativistic Plasmas in Low Density Environments

    SciTech Connect

    Rudnick, Lawrence

    2009-12-18

    We have been developing techniques over the last several years to identify and study relativistic plasmas in low density environments. These relativistic plasmas may be the best or only available indicators of diffuse baryons in portions of the Warm-Hot Intergalactic Medium outside of rich galaxy clusters. Studying such faint radio synchrotron sources requires removal of confusion from both background radio galaxies and the foreground Milky Way. In these proceedings, we briefly summarize the techniques we are developing and some of our initial results. Our discoveries likely represent the ''tip of the iceberg'' to be exploited by the nascent generation of radio telescopes.

  18. National Take-Back Initiative

    MedlinePlus

    ... Physicians Drug Disposal Information Drug and Chemical Information E-commerce Initiatives Federal Agencies & Related Links Federal Register Notices ... Physicians Drug Disposal Information Drug and Chemical Information E-commerce Initiatives Federal Agencies & Related Links Federal Register Notices ...

  19. The national geomagnetic initiative

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Earth's magnetic field, through its variability over a spectrum of spatial and temporal scales, contains fundamental information on the solid Earth and geospace environment (the latter comprising the atmosphere, ionosphere, and magnetosphere). Integrated studies of the geomagnetic field have the potential to address a wide range of important processes in the deep mantle and core, asthenosphere, lithosphere, oceans, and the solar-terrestrial environment. These studies have direct applications to important societal problems, including resource assessment and exploration, natural hazard mitigation, safe navigation, and the maintenance and survivability of communications and power systems on the ground and in space. Studies of the Earth's magnetic field are supported by a variety of federal and state agencies as well as by private industry. Both basic and applied research is presently supported by several federal agencies, including the National Science Foundation (NSF), U.S. Geological Survey (USGS), U.S. Department of Energy (DOE), National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and U.S. Department of Defense (DOD) (through the Navy, Air Force, and Defense Mapping Agency). Although each agency has a unique, well-defined mission in geomagnetic studies, many areas of interest overlap. For example, NASA, the Navy, and USGS collaborate closely in the development of main field reference models. NASA, NSF, and the Air Force collaborate in space physics. These interagency linkages need to be strengthened. Over the past decade, new opportunities for fundamental advances in geomagnetic research have emerged as a result of three factors: well-posed, first-order scientific questions; increased interrelation of research activities dealing with geomagnetic phenomena; and recent developments in technology. These new opportunities can be exploited through a national geomagnetic initiative to define objectives and

  20. Comparison of density determination of liquid samples by density meters

    NASA Astrophysics Data System (ADS)

    Buchner, C.; Wolf, H.; Vámossy, C.; Lorefice, S.; Lenard, E.; Spohr, I.; Mares, G.; Perkin, M.; Parlic-Risovic, T.; Grue, L.-L.; Tammik, K.; van Andel, I.; Zelenka, Z.

    2016-01-01

    Hydrostatic density determinations of liquids as reference material are mainly performed by National Metrology Institutes to provide means for calibrating or checking liquid density measuring instruments such as oscillation-type density meters. These density meters are used by most of the metrology institutes for their calibration and scientific work. The aim of this project was to compare the results of the liquid density determination by oscillating density meters of the participating laboratories. The results were linked to CCM.D.K-2 partly via Project EURAMET.M.D.K-2 (1019) "Comparison of liquid density standards" by hydrostatic weighing piloted by BEV in 2008. In this comparison pentadecane, water and of oil with a high viscosity were measured at atmospheric pressure using oscillation type density meter. The temperature range was from 15 °C to 40 °C. The measurement results were in some cases discrepant. Further studies, comparisons are essential to explore the capability and uncertainty of the density meters Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  1. Influence of initial conditions on compressible vorticity dynamics

    NASA Astrophysics Data System (ADS)

    Virk, D.; Hussain, F.

    1993-11-01

    Prompted by the lack of a unique choice of pressure ( P) and density (ρ) fields for a compressible free vortex and by the observed dependence of turbulence dynamics on initial P and ρ in compressible simulations, we address the effects of initial conditions on the evolution of a single vortex, on the prototypical phenomenon of vortex reconnection, and on two-dimensional turbulence. Two previous choices of initial conditions used for numerical simulations of compressible turbulence have been: (i) both P and ρ uniform (constant initial conditions, CIC), and (ii) uniform ρ with P determined from the Poisson equation (constant density initial conditions, CDIC). We find these initial conditions to be inappropriate for compressible vorticity dynamics studies. Specifically, in compressible reconnection, the effects of baroclinic vorticity generation and shocklet formation cancel each other during early evolution for CDIC, thus leading to almost incompressible behavior. Although CIC captures compressibility effects, it incorrectly changes the initial vorticity distribution by introducing strong acoustic transients, thereby significantly altering the evolving dynamics. Here, a new initial condition, called polytropic initial condition (PIC), is proposed, for which the Poisson equation is solved for initially polytropically related P and ρ fields. PIC provides P and ρ distributions within vortices which are consistent with those observed in shock-wedge interaction experiment and also leads to compressible solutions with no acoustic transients. At low Mach number ( M), we show that the effects of all these three initial conditions can be predicted by low- M asymptotic theories of the Navier-Stokes equations. At high M, it is shown here that inappropriate initial conditions may alter the evolutionary dynamics and, hence, lead to wrong conclusions regarding compressibility effects. We argue that PIC is a more appropriate choice.

  2. High Power Density Motors

    NASA Technical Reports Server (NTRS)

    Kascak, Daniel J.

    2004-01-01

    With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

  3. Density Fluctuations in Liquid Water

    NASA Astrophysics Data System (ADS)

    English, Niall J.; Tse, John S.

    2011-01-01

    The density distributions and fluctuations in grids of varying size in liquid water at ambient pressure, both above the freezing point and in the supercooled state, are analyzed from the trajectories obtained from large-scale molecular dynamics simulations. It is found that the occurrence of low- and high-density regions (LDL and HDL) is transient and their respective residence times are dependent on the size of the simulated system. The spatial extent of density-density correlation is found to be within 7 Å or less. The temporal existence of LDL and HDL arises as a result of natural density fluctuations of an equilibrium system. The density of bulk water at ambient conditions is homogenous.

  4. Modeling Tumor Invasion: Effects of Native Vascularity and Tumor Metabolism

    NASA Astrophysics Data System (ADS)

    Gawlinski, Edward

    2001-03-01

    A hybrid cellular automaton model is described and used to simulate early tumor growth and examine the roles of host tissue vascular density and tumor metabolism in the ability of a small number of monoclonal transformed cells to develop into an invasive tumor. The model incorporates normal cells, tumor cells, necrotic or empty space, and a random network of native microvessels as components of a cellular automaton state vector. Diffusion of glucose and lactic acid (the latter resulting from the tumor's excessive reliance on anaerobic metabolism) to and from the microvessels, and their utilization or production by cells, is modeled through the solution of differential equations. In this way, the cells and microvessels affect the extracellular concentrations of glucose and acid which, in turn, affect the rules governing the evolution of the automaton's state vector. Simulations of the model demonstrate that: (i) high tumor acid production is favorable for tumor growth and invasion, however for every acid production rate, there exists a range of optimal microvessel densities (leading to a local pH favorable to tumor but not to normal cells) for which growth and invasion is most effective, (ii) at vascular densities below this range, both tumor and normal cells die due to excessively low pH, (iii) for vascular densities above the optimal range the microvessel network is highly efficient at removing acid and therefore the tumor cells lose their advantage over normal cells gained by high local acid concentration. While significant spatial gradients of glucose formed, no regions of detrimentally poor glucose perfusion (for either cell type) were observed, regardless of microvessel density. Depending on metabolic phenotype, a variety of tumor morphologies similar to those clinically observed were realized in the simulations. Lastly, a sharp transition (analogous to that of the adenoma-carcinoma sequence) between states of initial tumor confinement and efficient

  5. Canonical density matrix perturbation theory.

    PubMed

    Niklasson, Anders M N; Cawkwell, M J; Rubensson, Emanuel H; Rudberg, Elias

    2015-12-01

    Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equations as in density-functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large nonmetallic materials and metals at high temperatures. PMID:26764847

  6. Density waves in granular flow

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.; Flekkøy, E.; Nagel, K.; Peng, G.; Ristow, G.

    Ample experimental evidence has shown the existence of spontaneous density waves in granular material flowing through pipes or hoppers. Using Molecular Dynamics Simulations we show that several types of waves exist and find that these density fluctuations follow a 1/f spectrum. We compare this behaviour to deterministic one-dimensional traffic models. If positions and velocities are continuous variables the model shows self-organized criticality driven by the slowest car. We also present Lattice Gas and Boltzmann Lattice Models which reproduce the experimentally observed effects. Density waves are spontaneously generated when the viscosity has a nonlinear dependence on density which characterizes granular flow.

  7. SOP - Determination of Requirement Density

    SciTech Connect

    Reynolds, John G.; Martz, Jr., Harry E.

    2010-10-26

    The purpose of this Standard Operating Procedure (SOP) is to give guidelines on how to determine the density of a sample that will be used as the requirement density. This will be the requirement density of record for the specimens examined by Micro CT and EDS measurements. This density will then be set as the formulation requirement for radiography measurements. This SOP is referred to in TP 48— Preparation of Hydrogen Peroxide/Icing Sugar Specimens for X-ray Measurements by J. G. Reynolds and H. E. Martz.

  8. The surface density of haloes

    NASA Astrophysics Data System (ADS)

    Del Popolo, A.; Lee, Xi-Guo

    We study the correlation between the central surface density and the core radius of the dark matter haloes of galaxies and clusters of galaxies. We find that the surface density within the halo characteristic radius r* is not a universal quantity as claimed by some authors (e.g., Milgrom 2009), but it correlates with several physical quantities (e.g., the halo mass M200, and the magnitude MB). The slope of the surface density-mass relation is 0.18 ± 0.05, leaving small room to the possibility of a constant surface density. Finally, we compare the results with MOND predictions.

  9. Density Estimation with Mercer Kernels

    NASA Technical Reports Server (NTRS)

    Macready, William G.

    2003-01-01

    We present a new method for density estimation based on Mercer kernels. The density estimate can be understood as the density induced on a data manifold by a mixture of Gaussians fit in a feature space. As is usual, the feature space and data manifold are defined with any suitable positive-definite kernel function. We modify the standard EM algorithm for mixtures of Gaussians to infer the parameters of the density. One benefit of the approach is it's conceptual simplicity, and uniform applicability over many different types of data. Preliminary results are presented for a number of simple problems.

  10. Canonical density matrix perturbation theory.

    PubMed

    Niklasson, Anders M N; Cawkwell, M J; Rubensson, Emanuel H; Rudberg, Elias

    2015-12-01

    Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equations as in density-functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large nonmetallic materials and metals at high temperatures.

  11. Current density and state density in diluted magnetic semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Pérez Merchancano, S. T.; Paredes Gutiérrez, H.; Zuñiga, J. A.

    2016-02-01

    We study in this paper the spin-polarized current density components in diluted magnetic semiconductor tunnelling diodes with different sample geometries. We calculate the resonant JxV and the density of states. The differential conductance curves are analyzed as functions of the applied voltage and the magnetic potential strength induced by the magnetic ions.

  12. Florida Hydrogen Initiative

    SciTech Connect

    Block, David L

    2013-06-30

    The Florida Hydrogen Initiative (FHI) was a research, development and demonstration hydrogen and fuel cell program. The FHI program objectives were to develop Florida?s hydrogen and fuel cell infrastructure and to assist DOE in its hydrogen and fuel cell activities The FHI program funded 12 RD&D projects as follows: Hydrogen Refueling Infrastructure and Rental Car Strategies -- L. Lines, Rollins College This project analyzes strategies for Florida's early stage adaptation of hydrogen-powered public transportation. In particular, the report investigates urban and statewide network of refueling stations and the feasibility of establishing a hydrogen rental-car fleet based in Orlando. Methanol Fuel Cell Vehicle Charging Station at Florida Atlantic University ? M. Fuchs, EnerFuel, Inc. The project objectives were to design, and demonstrate a 10 kWnet proton exchange membrane fuel cell stationary power plant operating on methanol, to achieve an electrical energy efficiency of 32% and to demonstrate transient response time of less than 3 milliseconds. Assessment of Public Understanding of the Hydrogen Economy Through Science Center Exhibits, J. Newman, Orlando Science Center The project objective was to design and build an interactive Science Center exhibit called: ?H2Now: the Great Hydrogen Xchange?. On-site Reformation of Diesel Fuel for Hydrogen Fueling Station Applications ? A. Raissi, Florida Solar Energy Center This project developed an on-demand forecourt hydrogen production technology by catalytically converting high-sulfur hydrocarbon fuels to an essentially sulfur-free gas. The removal of sulfur from reformate is critical since most catalysts used for the steam reformation have limited sulfur tolerance. Chemochromic Hydrogen Leak Detectors for Safety Monitoring ? N. Mohajeri and N. Muradov, Florida Solar Energy Center This project developed and demonstrated a cost-effective and highly selective chemochromic (visual) hydrogen leak detector for safety monitoring

  13. Density limits investigation and high density operation in EAST tokamak

    NASA Astrophysics Data System (ADS)

    Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Liu, Haiqing; Jie, Yinxian; Wang, Shouxin; Li, Jiahong; Duan, Yanming; Li, Miaohui; Li, Yongchun; Zhang, Ling; Ye, Yang; Yang, Qingquan; Zhang, Tao; Cheng, Yingjie; Xu, Jichan; Wang, Liang; Xu, Liqing; Zhao, Hailin; Wang, Fudi; Lin, Shiyao; Wu, Bin; Lyu, Bo; Xu, Guosheng; Gao, Xiang; Shi, Tonghui; He, Kaiyang; Lan, Heng; Chu, Nan; Cao, Bin; Sun, Zhen; Zuo, Guizhong; Ren, Jun; Zhuang, Huidong; Li, Changzheng; Yuan, Xiaolin; Yu, Yaowei; Wang, Houyin; Chen, Yue; Wu, Jinhua; EAST Team

    2016-05-01

    Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H  →  L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of 0.8∼ 0.9{{n}\\text{GW}} . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H  →  L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density (>2.8× {{10}19} {{\\text{m}}-3} ) is favorable for suppressing the beam shine through NBI. High density H-mode up to 5.3× {{10}19}{{\\text{m}}-3}~≤ft(∼ 0.8{{n}\\text{GW}}\\right) could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93{{n}\\text{GW}} stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.

  14. FOREWORD: Special issue on density

    NASA Astrophysics Data System (ADS)

    Fujii, Kenichi

    2004-04-01

    This special issue on density was undertaken to provide readers with an overview of the present state of the density standards for solids, liquids and gases, as well as the technologies developed for measuring density. This issue also includes topics on the refractive index of gases and on techniques used for calibrating hydrometers so that almost all areas concerned with density standards are covered in four review articles and seven original articles, most of which describe current research being conducted at national metrology institutes (NMIs). A review article was invited from the Ruhr-Universität Bochum to highlight research on the magnetic suspension densimeters. In metrology, the determinations of the volume of a weight and the density of air are of primary importance in establishing a mass standard because the effect of the buoyancy force of air acting on the weight must be known accurately to determine the mass of the weight. A density standard has therefore been developed at many NMIs with a close relation to the mass standard. Hydrostatic weighing is widely used to measure the volume of a solid. The most conventional hydrostatic weighing method uses water as a primary density standard for measuring the volume of a solid. A brief history of the determination of the density of water is therefore given in a review article, as well as a recommended value for the density of water with a specified isotopic abundance. The most modern technique for hydrostatic weighing uses a solid density standard instead of water. For this purpose, optical interferometers for measuring the diameters of silicon spheres have been developed to convert the length standard into the volume standard with a small uncertainty. A review article is therefore dedicated to describing the state-of-the-art optical interferometers developed for silicon spheres. Relative combined standard uncertainties of several parts in 108 have been achieved today for measuring the volume and density of

  15. Consistent Initial Conditions for the DNS of Compressible Turbulence

    NASA Technical Reports Server (NTRS)

    Ristorcelli, J. R.; Blaisdell, G. A.

    1996-01-01

    Relationships between diverse thermodynamic quantities appropriate to weakly compressible turbulence are derived. It is shown that for turbulence of a finite turbulent Mach number there is a finite element of compressibility. A methodology for generating initial conditions for the fluctuating pressure, density and dilatational velocity is given which is consistent with finite Mach number effects. Use of these initial conditions gives rise to a smooth development of the flow, in contrast to cases in which these fields are specified arbitrarily or set to zero. Comparisons of the effect of different types of initial conditions are made using direct numerical simulation of decaying isotropic turbulence.

  16. 14 CFR 93.215 - Initial allocation of slots.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Carrier IFR Operations at High Density Traffic Airports § 93.215 Initial allocation of slots. (a) Each air... of the air carrier and commuter operator scheduling committees, shall be allocated those slots... records of the scheduling committees, shall be allocated in conformity with those records. The...

  17. 14 CFR 93.215 - Initial allocation of slots.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Allocation of Commuter and Air Carrier IFR Operations at High Density Traffic Airports § 93.215 Initial allocation of slots. (a) Each air... of the air carrier and commuter operator scheduling committees, shall be allocated those...

  18. 14 CFR 93.215 - Initial allocation of slots.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Allocation of Commuter and Air Carrier IFR Operations at High Density Traffic Airports § 93.215 Initial allocation of slots. (a) Each air... of the air carrier and commuter operator scheduling committees, shall be allocated those...

  19. Precision Orbit Derived Atmospheric Density: Development and Performance

    NASA Astrophysics Data System (ADS)

    McLaughlin, C.; Hiatt, A.; Lechtenberg, T.; Fattig, E.; Mehta, P.

    2012-09-01

    derived density estimates. However, major variations in density are observed in the POE derived densities. These POE derived densities in combination with other data sources can be assimilated into physics based general circulation models of the thermosphere and ionosphere with the possibility of providing improved density forecasts for satellite drag analysis. POE derived density estimates were initially developed using CHAMP and GRACE data so comparisons could be made with accelerometer derived density estimates. This paper presents the results of the most extensive calibration of POE derived densities compared to accelerometer derived densities and provides the reasoning for selecting certain parameters in the estimation process. The factors taken into account for these selections are the cross correlation and RMS performance compared to the accelerometer derived densities and the output of the ballistic coefficient estimation that occurs simultaneously with the density estimation. This paper also presents the complete data set of CHAMP and GRACE results and shows that the POE derived densities match the accelerometer densities better than empirical models or DCA. This paves the way to expand the POE derived densities to include other satellites with quality GPS and/or satellite laser ranging observations.

  20. Nonideal detonation regimes in low density explosives

    NASA Astrophysics Data System (ADS)

    Ershov, A. P.; Kashkarov, A. O.; Pruuel, E. R.; Satonkina, N. P.; Sil'vestrov, V. V.; Yunoshev, A. S.; Plastinin, A. V.

    2016-02-01

    Measurements using Velocity Interferometer System for Any Reflector (VISAR) were performed for three high explosives at densities slightly above the natural loose-packed densities. The velocity histories at the explosive/window interface demonstrate that the grain size of the explosives plays an important role. Fine-grained materials produced rather smooth records with reduced von Neumann spike amplitudes. For commercial coarse-grained specimens, the chemical spike (if detectable) was more pronounced. This difference can be explained as a manifestation of partial burn up. In fine-grained explosives, which are more sensitive, the reaction can proceed partly within the compression front, which leads to a lower initial shock amplitude. The reaction zone was shorter in fine-grained materials because of higher density of hot spots. The noise level was generally higher for the coarse-grained explosives, which is a natural stochastic effect of the highly non-uniform flow of the heterogeneous medium. These results correlate with our previous data of electrical conductivity diagnostics. Instead of the classical Zel'dovich-von Neumann-Döring profiles, violent oscillations around the Chapman-Jouguet level were observed in about half of the shots using coarse-grained materials. We suggest that these unusual records may point to a different detonation wave propagation mechanism.

  1. High energy density electrochemical cell

    NASA Technical Reports Server (NTRS)

    Byrne, J. J.; Williams, D. L.

    1970-01-01

    Primary cell has an anode of lithium, a cathode containing dihaloisocyanuric acid, and a nonaqueous electrolyte comprised of a solution of lithium perchlorate in methyl formate. It produces an energy density of 213 watt hrs/lb and can achieve a high current density.

  2. Density-orbital embedding theory

    SciTech Connect

    Gritsenko, O. V.; Visscher, L.

    2010-09-15

    In the article density-orbital embedding (DOE) theory is proposed. DOE is based on the concept of density orbital (DO), which is a generalization of the square root of the density for real functions and fractional electron numbers. The basic feature of DOE is the representation of the total supermolecular density {rho}{sub s} as the square of the sum of the DO {phi}{sub a}, which represents the active subsystem A and the square root of the frozen density {rho}{sub f} of the environment F. The correct {rho}{sub s} is obtained with {phi}{sub a} being negative in the regions in which {rho}{sub f} might exceed {rho}{sub s}. This makes it possible to obtain the correct {rho}{sub s} with a broad range of the input frozen densities {rho}{sub f} so that DOE resolves the problem of the frozen-density admissibility of the current frozen-density embedding theory. The DOE Euler equation for the DO {phi}{sub a} is derived with the characteristic embedding potential representing the effect of the environment. The DO square {phi}{sub a}{sup 2} is determined from the orbitals of the effective Kohn-Sham (KS) system. Self-consistent solution of the corresponding one-electron KS equations yields not only {phi}{sub a}{sup 2}, but also the DO {phi}{sub a} itself.

  3. Chronic acceleration and brain density

    NASA Technical Reports Server (NTRS)

    Hoffman, L. F.; Smith, A. H.

    1982-01-01

    Tests carried out on rabbits show that the effect of chronic acceleration is not uniform among the various tissues studied. Although body mass is reduced by the treatment, as expected, no change is apparent in brain mass or in the density of cerebrospinal fluid. Acceleration-induced changes are encountered in tissue density, the myocardium exhibiting a transient increase followed by an exponential decrease toward a limit and the brain showing an arithmetic increase in density with continued exposure to 2.5 G. The data are seen as suggesting that a specific brain load is not a regulated phenomenon and that no physiological processes occur to attenuate the increased load imposed by the hyperdynamic environment. An equation is derived indicating that the stimulus potential per unit of brain load increases with body size, even though brain density decreases and cerebrospinal fluid density increases.

  4. Detecting Density Variations and Nanovoids

    SciTech Connect

    Miller, Michael K; Longstreth-Spoor, L.; Kelton, K. F.

    2011-01-01

    A combination of simulated and experimental data has been used to investigate the size range of nanovoids that can be detected in atom probe tomography data. Simulated atom probe tomography data have revealed that nanovoids as small as 1 nm in diameter can be detected in atom probe tomography data with the use of iso-density surfaces. Iso-density surfaces may be used to quantify the size, morphology and number density of nanovoids and other variations in density in atom probe tomography data. Experimental data from an aluminum-yttrium-iron metallic glass ribbon have revealed the effectiveness of this approach. Combining iso-density surfaces with atom maps also permits the segregation of solute to the nanovoids to be investigated. Field ion microscopy and thin section atom maps have also been used to detect pores and larger voids.

  5. Initiation Pressure Thresholds from Three Sources

    SciTech Connect

    Souers, P C; Vitello, P

    2007-02-28

    Pressure thresholds are minimum pressures needed to start explosive initiation that ends in detonation. We obtain pressure thresholds from three sources. Run-to-detonation times are the poorest source but the fitting of a function gives rough results. Flyer-induced initiation gives the best results because the initial conditions are the best known. However, very thick flyers are needed to give the lowest, asymptotic pressure thresholds used in modern models and this kind of data is rarely available. Gap test data is in much larger supply but the various test sizes and materials are confusing. We find that explosive pressures are almost the same if the distance in the gap test spacers are in units of donor explosive radius. Calculated half-width time pulses in the spacers may be used to create a pressure-time curve similar to that of the flyers. The very-large Eglin gap tests give asymptotic thresholds comparable to extrapolated flyer results. The three sources are assembled into a much-expanded set of near-asymptotic pressure thresholds. These thresholds vary greatly with density: for TATB/LX-17/PBX 9502, we find values of 4.9 and 8.7 GPa at 1.80 and 1.90 g/cm{sup 3}, respectively.

  6. Initiation into Adolescent Marijuana Use.

    ERIC Educational Resources Information Center

    Brook, Judith S.; And Others

    1980-01-01

    This longitudinal study examined the relationship of three domains (personality/attitudinal orientations, peer relationships, and family socialization factors) with initiation into adolescent marihuana use. (Author/DB)

  7. Low bone mineral density in Friedreich ataxia.

    PubMed

    Eigentler, Andreas; Nachbauer, Wolfgang; Donnemiller, Eveline; Poewe, Werner; Gasser, Rudolf W; Boesch, Sylvia

    2014-10-01

    Friedreich ataxia (FRDA) is the most common inherited neurodegenerative ataxia. Apart from predominant neurological features an involvement of the skeletal system in terms of scoliosis and foot deformities is frequent. Disease-related falls, mobility restrictions, and wheelchair-dependency in later disease stages might additionally compromise bone structure in FRDA. The aim of this pilot study was to systematically evaluate the bone status in a representative FRDA cohort. Twenty-eight FRDA patients became enrolled in this cross-sectional study. Neurological assessment, a questionnaire comprising the history of fractures and osteoporosis as well as osteodensitometric measurements complemented with general and bone-specific laboratory parameters were performed. The WHO Fracture Risk Assessment tool (FRAX®) was applied, calculating the 10-year risk of suffering an osteoporotic fracture. Six patients (21.4 %) presented with a bone mineral density below the expected range for age in at least one of the examined sites (femoral neck, lumbar spine, and forearm) irrespective of their gender. Corresponding Z scores were significantly lower compared to normative values for the femoral neck and lumbar spine. Vitamin D status was insufficient in 11 and deficient in 8 FRDA patients. There was a strong negative correlation between ataxia severity, GAA repeat expansion and bone density in the femoral neck of FRDA patients. This is the first report of an increased rate of low bone mineral density in FRDA. Given the increased risk of falls, this data rectifies routine bone mineral density measurements in FRDA which may help to initiate therapeutic interventions to prevent this condition.

  8. Attractor comparisons based on density

    SciTech Connect

    Carroll, T. L.

    2015-01-15

    Recognizing a chaotic attractor can be seen as a problem in pattern recognition. Some feature vector must be extracted from the attractor and used to compare to other attractors. The field of machine learning has many methods for extracting feature vectors, including clustering methods, decision trees, support vector machines, and many others. In this work, feature vectors are created by representing the attractor as a density in phase space and creating polynomials based on this density. Density is useful in itself because it is a one dimensional function of phase space position, but representing an attractor as a density is also a way to reduce the size of a large data set before analyzing it with graph theory methods, which can be computationally intensive. The density computation in this paper is also fast to execute. In this paper, as a demonstration of the usefulness of density, the density is used directly to construct phase space polynomials for comparing attractors. Comparisons between attractors could be useful for tracking changes in an experiment when the underlying equations are too complicated for vector field modeling.

  9. Maps of current density using density-functional methods

    NASA Astrophysics Data System (ADS)

    Soncini, A.; Teale, A. M.; Helgaker, T.; de Proft, F.; Tozer, D. J.

    2008-08-01

    The performance of several density-functional theory (DFT) methods for the calculation of current densities induced by a uniform magnetic field is examined. Calculations are performed using the BLYP and KT3 generalized-gradient approximations, together with the B3LYP hybrid functional. For the latter, both conventional and optimized effective potential (OEP) approaches are used. Results are also determined from coupled-cluster singles-and-doubles (CCSD) electron densities by a DFT constrained search procedure using the approach of Wu and Yang (WY). The current densities are calculated within the CTOCD-DZ2 distributed origin approach. Comparisons are made with results from Hartree-Fock (HF) theory. Several small molecules for which correlation is known to be especially important in the calculation of magnetic response properties are considered-namely, O3, CO, PN, and H2CO. As examples of aromatic and antiaromatic systems, benzene and planarized cyclooctatetraene molecules are considered, with specific attention paid to the ring current phenomenon and its Kohn-Sham orbital origin. Finally, the o-benzyne molecule is considered as a computationally challenging case. The HF and DFT induced current maps show qualitative differences, while among the DFT methods the maps show a similar qualitative structure. To assess quantitative differences in the calculated current densities with different methods, the maximal moduli of the induced current densities are compared and integration of the current densities to yield shielding constants is performed. In general, the maximal modulus is reduced in moving from HF to B3LYP and BLYP, and further reduced in moving to KT3, OEP(B3LYP), and WY(CCSD). The latter three methods offer the most accurate shielding constants in comparison with both experimental and ab initio data and hence the more reliable route to DFT calculation of induced current density in molecules.

  10. iDensity: an automatic Gabor filter-based algorithm for breast density assessment

    NASA Astrophysics Data System (ADS)

    Gamdonkar, Ziba; Tay, Kevin; Ryder, Will; Brennan, Patrick C.; Mello-Thoms, Claudia

    2015-03-01

    Abstract Although many semi-automated and automated algorithms for breast density assessment have been recently proposed, none of these have been widely accepted. In this study a novel automated algorithm, named iDensity, inspired by the human visual system is proposed for classifying mammograms into four breast density categories corresponding to the Breast Imaging Reporting and Data System (BI-RADS). For each BI-RADS category 80 cases were taken from the normal volumes of the Digital Database for Screening Mammography (DDSM). For each case only the left medio-lateral oblique was utilized. After image calibration using the provided tables of each scanner in the DDSM, the pectoral muscle and background were removed. Images were filtered by a median filter and down sampled. Images were then filtered by a filter bank consisting of Gabor filters in six orientations and 3 scales, as well as a Gaussian filter. Three gray level histogram-based features and three second order statistics features were extracted from each filtered image. Using the extracted features, mammograms were separated initially separated into two groups, low or high density, then in a second stage, the low density group was subdivided into BI-RADS I or II, and the high density group into BI-RADS III or IV. The algorithm achieved a sensitivity of 95% and specificity of 94% in the first stage, sensitivity of 89% and specificity of 95% when classifying BIRADS I and II cases, and a sensitivity of 88% and 91% specificity when classifying BI-RADS III and IV.

  11. Nebraska: Early Head Start Initiative

    ERIC Educational Resources Information Center

    Center for Law and Social Policy, Inc. (CLASP), 2012

    2012-01-01

    Since 1999, Nebraska's Early Head Start Infant/Toddler Quality Initiative has supported Early Head Start (EHS) and community child care partnerships to improve the quality and professionalism of infant and toddler care. EHS programs apply to receive funding to establish partnerships with center-based or home-based child care.The initiative has…

  12. Two black hole initial data

    SciTech Connect

    Leski, Szymon

    2005-06-15

    The Misner initial data are a standard example of time-symmetric initial data with two apparent horizons. Compact formulae describing such data are presented in the cases of equal or nonequal masses (i.e. isometric or nonisometric horizons). The interaction energy in the 'Schwarzschild + test-particle' limit of the Misner data is analyzed.

  13. Education as Initiation into Practices

    ERIC Educational Resources Information Center

    Smeyers, Paul; Burbules, Nicholas C.

    2006-01-01

    In this essay, Paul Smeyers and Nicholas Burbules reexamine the concept of "practice" and propose a new way of conceiving it that does justice to the idea that education is in some sense an initiation into practices without endorsing either the conservative and reproductive conception of what initiation entails or the radically social…

  14. Washington State's Student Achievement Initiative

    ERIC Educational Resources Information Center

    Pettitt, Maureen; Prince, David

    2010-01-01

    This article describes Washington State's Student Achievement Initiative, an accountability system implemented in 2005-06 that measures students' gains in college readiness, college credits earned, and degree or certificate completion. The goal of the initiative is to increase educational attainment by focusing on the critical momentum points…

  15. Career Technical Education Pathways Initiative

    ERIC Educational Resources Information Center

    California Community Colleges, Chancellor's Office, 2013

    2013-01-01

    California's education system--the largest in the United States--is an essential resource for ensuring strong economic growth in the state. The Career Technical Education Pathways Initiative (referred to as the Initiative in this report), which became law in 2005, brings together community colleges, K-12 school districts, employers, organized…

  16. Volcanogenic Massive Sulfide Deposit Density

    USGS Publications Warehouse

    Mosier, Dan L.; Singer, Donald A.; Berger, Vladimir I.

    2007-01-01

    A mineral-deposit density model for volcanogenic massive sulfide deposits was constructed from 38 well-explored control areas from around the world. Control areas contain at least one exposed volcanogenic massive sulfide deposit. The control areas used in this study contain 150 kuroko, 14 Urals, and 25 Cyprus massive sulfide subtypes of volcanogenic massive sulfide deposits. For each control area, extent of permissive rock, number of exposed volcanogenic massive sulfide deposits, map scale, deposit age, and deposit density were determined. The frequency distribution of deposit densities in these 38 control areas provides probabilistic estimates of the number of deposits for tracts that are permissive for volcanogenic massive sulfide deposits-90 percent of the control areas have densities of 100 or more deposits per 100,000 square kilometers, 50 percent of the control areas have densities of 700 or more deposits per 100,000 square kilometers, and 10 percent of the control areas have densities of 3,700 or more deposits per 100,000 square kilometers. Both map scale and the size of the control area are shown to be predictors of deposit density. Probabilistic estimates of the number of volcanogenic massive sulfide deposits can be made by conditioning the estimates on sizes of permissive area. The model constructed for this study provides a powerful tool for estimating the number of undiscovered volcanogenic massive sulfide deposits when conducting resource assessments. The value of these deposit densities is due to the consistency of these models with the grade and tonnage and the descriptive models. Mineral-deposit density models combined with grade and tonnage models allow reasonable estimates of the number, size, and grades of volcanogenic massive sulfide deposits to be made.

  17. Density Estimations in Laboratory Debris Flow Experiments

    NASA Astrophysics Data System (ADS)

    Queiroz de Oliveira, Gustavo; Kulisch, Helmut; Malcherek, Andreas; Fischer, Jan-Thomas; Pudasaini, Shiva P.

    2016-04-01

    Bulk density and its variation is an important physical quantity to estimate the solid-liquid fractions in two-phase debris flows. Here we present mass and flow depth measurements for experiments performed in a large-scale laboratory set up. Once the mixture is released and it moves down the inclined channel, measurements allow us to determine the bulk density evolution throughout the debris flow. Flow depths are determined by ultrasonic pulse reflection, and the mass is measured with a total normal force sensor. The data were obtained at 50 Hz. The initial two phase material was composed of 350 kg debris with water content of 40%. A very fine pebble with mean particle diameter of 3 mm, particle density of 2760 kg/m³ and bulk density of 1400 kg/m³ in dry condition was chosen as the solid material. Measurements reveal that the debris bulk density remains high from the head to the middle of the debris body whereas it drops substantially at the tail. This indicates lower water content at the tail, compared to the head and the middle portion of the debris body. This means that the solid and fluid fractions are varying strongly in a non-linear manner along the flow path, and from the head to the tail of the debris mass. Importantly, this spatial-temporal density variation plays a crucial role in determining the impact forces associated with the dynamics of the flow. Our setup allows for investigating different two phase material compositions, including large fluid fractions, with high resolutions. The considered experimental set up may enable us to transfer the observed phenomena to natural large-scale events. Furthermore, the measurement data allows evaluating results of numerical two-phase mass flow simulations. These experiments are parts of the project avaflow.org that intends to develop a GIS-based open source computational tool to describe wide spectrum of rapid geophysical mass flows, including avalanches and real two-phase debris flows down complex natural

  18. Density of very small meteoroids

    NASA Astrophysics Data System (ADS)

    Kikwaya Eluo, Jean-Baptiste

    2015-08-01

    Knowing the density of meteoroids helps to determine the physical structure and gives insight into the composition of their parent bodies. The density of meteoroids can provide clues to their origins, whether cometary or asteroidal. Density helps also to characterize the risk meteoroids may pose to artificial satellites.Ceplecha (1968) calculated the density of small meteoroids based on a parameter KB (meteoroid beginning height) and classified them in four categories (A,B,C,D) with densities going from 2700 to 180 kgm-3.Babadzhanov(2002) applied a model based on quasi-continuous fragmentation (QCF) on 413 photographic Super-Schmidt meteors by solely fitting their light curves. Their densities range from 400 to 7800 kgm-3. Bellot Rubio et al. (2002) analyzed the same 413 photographic meteors assuming the single body theory based on meteoroid dynamical properties and found densities ranging from 400 to 4800 kgm-3. A thermal erosion model was used by Borovicka et al. (2007) to analyze, simultaneously, the observed decelerations and light curves of six Draconid meteors. The density was found to be 300 kgm-3, consistent with the fact that the Draconid meteors are porous aggregates of grains associated with the Jupiter-family-comet 21P/Giacobini-Zinner (Jacchia, L.G., 1950).We used the Campbell-Brown and Koschny (2004) model of meteoroid ablation to determine the density of faint meteoroids from the analysis of both observed decelerations and light curves of meteoroids (Kikwaya et al., 2009; Kikwaya et al., 2011). Our work was based on a collection of six and ninety-two sporadic meteors. The grain masses used in the modeling ranged from 10-12 Kg to 10-9 Kg. We computed the orbit of each meteoroid and determined its Tisserand parameter. We found that meteoroids with asteroidal orbits have bulk densities ranging from 3000-5000 kgm-3. Meteoroids consistent with HTC/NIC parents have bulk densities from 400 kgm-3 to 1600 kg m-3. JFC meteoroids were found to have surprisingly

  19. Density in a Planetary Exosphere

    NASA Technical Reports Server (NTRS)

    Herring, Jackson; Kyle, Herbert L.

    1961-01-01

    A discussion of the Opik-Singer theory of the density of a planetary exosphere is presented. Their density formula permits the calculation of the depth of the exosphere. Since the correctness of their derivation of the basic formula for the density distribution has been questioned, an alternate method based directly on Liouville's theorem is given. It is concluded that the Opik-Singer formula seems valid for the ballistic component of the exosphere; but for a complete description of the planetary exosphere, the ionized and bound-orbit components must also be included.

  20. Fragmentation and densities of meteoroids

    NASA Technical Reports Server (NTRS)

    Babadzhanov, Pulat B.

    1992-01-01

    Photographic observations of meteors carried out in Dushanbe by the method of instantaneous exposure have shown clearly that meteoroids entering the Earth's atmosphere are subjected to different types of fragmentation. The quasi-continuous fragmentation of meteoroids is mostly widespread. Using the physical theory of meteors which takes into account the quasi-continuous fragmentation of meteoroids and on the basis of light curves of meteors the densities of meteoroids of different streams have been determined. The results enable us to conclude that the densities of meteoroids are over an order of magnitude higher than they have been assumed before. Moreover they are close to the densities of carbonaceous and ordinary chondrites.

  1. Phenomenological Relativistic Energy Density Functionals

    SciTech Connect

    Lalazissis, G. A.; Kartzikos, S.; Niksic, T.; Paar, N.; Vretenar, D.; Ring, P.

    2009-08-26

    The framework of relativistic nuclear energy density functionals is applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of beta-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure is explored using the fully consistent quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. Recent applications of energy density functionals with explicit density dependence of the meson-nucleon couplings are presented.

  2. FOREWORD: Special issue on density

    NASA Astrophysics Data System (ADS)

    Fujii, Kenichi

    2004-04-01

    This special issue on density was undertaken to provide readers with an overview of the present state of the density standards for solids, liquids and gases, as well as the technologies developed for measuring density. This issue also includes topics on the refractive index of gases and on techniques used for calibrating hydrometers so that almost all areas concerned with density standards are covered in four review articles and seven original articles, most of which describe current research being conducted at national metrology institutes (NMIs). A review article was invited from the Ruhr-Universität Bochum to highlight research on the magnetic suspension densimeters. In metrology, the determinations of the volume of a weight and the density of air are of primary importance in establishing a mass standard because the effect of the buoyancy force of air acting on the weight must be known accurately to determine the mass of the weight. A density standard has therefore been developed at many NMIs with a close relation to the mass standard. Hydrostatic weighing is widely used to measure the volume of a solid. The most conventional hydrostatic weighing method uses water as a primary density standard for measuring the volume of a solid. A brief history of the determination of the density of water is therefore given in a review article, as well as a recommended value for the density of water with a specified isotopic abundance. The most modern technique for hydrostatic weighing uses a solid density standard instead of water. For this purpose, optical interferometers for measuring the diameters of silicon spheres have been developed to convert the length standard into the volume standard with a small uncertainty. A review article is therefore dedicated to describing the state-of-the-art optical interferometers developed for silicon spheres. Relative combined standard uncertainties of several parts in 108 have been achieved today for measuring the volume and density of

  3. Density and pair-density scaling for deriving the Euler equation in density-functional and pair-density-functional theory

    SciTech Connect

    Nagy, A.

    2011-09-15

    A link between density and pair density functional theories is presented. Density and pair density scaling are used to derive the Euler equation in both theories. Density scaling provides a constructive way of obtaining approximations for the Pauli potential. The Pauli potential (energy) of the density functional theory is expressed as the difference of the scaled and original exchange-correlation potentials (energies).

  4. Low density metal hydride foams

    DOEpatents

    Maienschein, Jon L.; Barry, Patrick E.

    1991-01-01

    Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam.

  5. Density waves in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.; Lissauer, J. J.; Shu, F. H.

    1981-08-01

    Certain radial brightness variations in the outer Cassini division of Saturn's rings may be spiral density waves driven by Saturn's large moon Iapetus, in which case a value of approximately 16 g/sq cm for the surface density is calculated in the region where the waves are seen. The kinematic viscosity in the same region is approximately 170 sq cm/s and the vertical scale height of the ring is estimated to be a maximum of approximately 40 m.

  6. OMI Global Tropospheric Bromine Oxide (BrO) Column Densities: Algorithm, Retrieval and Initial Validation

    NASA Astrophysics Data System (ADS)

    Suleiman, R. M.; Chance, K.; Liu, X.; Kurosu, T. P.; Gonzalez Abad, G.

    2014-12-01

    We present and discuss a detailed description of the retrieval algorithms for the OMI BrO product. The BrO algorithms are based on direct fitting of radiances from 319.0-347.5 nm. Radiances are modeled from the solar irradiance, attenuated and adjusted by contributions from the target gas and interfering gases, rotational Raman scattering, undersampling, additive and multiplicative closure polynomials and a common mode spectrum. The version of the algorithm used for both BrO includes relevant changes with respect to the operational code, including the fit of the O2-O2 collisional complex, updates in the high resolution solar reference spectrum, updates in spectroscopy, an updated Air Mass Factor (AMF) calculation scheme, and the inclusion of scattering weights and vertical profiles in the level 2 products. Updates to the algorithms include accurate scattering weights and air mass factor calculations, scattering weights and profiles in outputs and available cross sections. We include retrieval parameter and window optimization to reduce the interference from O3, HCHO, O2-O2, SO2, improve fitting accuracy and uncertainty, reduce striping, and improve the long-term stability. We validate OMI BrO with ground-based measurements from Harestua and with chemical transport model simulations. We analyze the global distribution and seasonal variation of BrO and investigate BrO emissions from volcanoes and salt lakes.

  7. LOW-ENERGY NUCLEAR PHYSICS NATIONAL HPC INITIATIVE: BUILDING A UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL (UNEDF)

    SciTech Connect

    Bulgac, A

    2013-03-27

    This document is a summary of the physics research carried out by the University of Washington centered group. Attached are reports for the previous years as well as the full exit report of the entire UNEDF collaboration.

  8. Cell-cycle-specific initiation of replication.

    PubMed

    Nordström, K; Austin, S J

    1993-11-01

    The following characteristics are relevant when replication of chromosomes and plasmids is discussed in relation to the cell cycle: the timing or replication, the selection of molecules for replication, and the coordination of multiple initiation events within a single cell cycle. Several fundamentally different methods have been used to study these processes: Meselson-Stahl density-shift experiments, experiments with the so-called 'baby machine', sorting of cells according to size, and flow cytometry. The evidence for precise timing and co-ordination of chromosome replication in Escherichia coli is overwhelming. Similarly, the high-copy-number plasmid ColE1 and the low-copy-number plasmids R1/R100 without any doubt replicate randomly throughout the cell cycle. Data about the low-copy-number plasmids F and P1 are conflicting. This calls for new types of experiments and for a better understanding of how these plasmids control their replication and partitioning.

  9. The initiation of post-synaptic protrusions

    PubMed Central

    Hotulainen, Pirta; Saarikangas, Juha

    2016-01-01

    ABSTRACT The post-synaptic spines of neuronal dendrites are highly elaborate membrane protrusions. Their anatomy, stability and density are intimately linked to cognitive performance. The morphological transitions of spines are powered by coordinated polymerization of actin filaments against the plasma membrane, but how the membrane-associated polymerization is spatially and temporally regulated has remained ill defined. Here, we discuss our recent findings showing that dendritic spines can be initiated by direct membrane bending by the I-BAR protein MIM/Mtss1. This lipid phosphatidylinositol (PI(4,5)P2) signaling-activated membrane bending coordinated spatial actin assembly and promoted spine formation. From recent advances, we formulate a general model to discuss how spatially concentrated protein-lipid microdomains formed by multivalent interactions between lipids and actin/membrane regulatory proteins might launch cell protrusions. PMID:27489575

  10. Direct experimental determination of spectral densities of molecular complexes

    NASA Astrophysics Data System (ADS)

    Pachón, Leonardo A.; Brumer, Paul

    2014-11-01

    Determining the spectral density of a molecular system immersed in a proteomic scaffold and in contact to a solvent is a fundamental challenge in the coarse-grained description of, e.g., electron and energy transfer dynamics. Once the spectral density is characterized, all the time scales are captured and no artificial separation between fast and slow processes need to be invoked. Based on the fluorescence Stokes shift function, we utilize a simple and robust strategy to extract the spectral density of a number of molecular complexes from available experimental data. Specifically, we show that experimental data for dye molecules in several solvents, amino acid proteins in water, and some photochemical systems (e.g., rhodopsin and green fluorescence proteins), are well described by a three-parameter family of sub-Ohmic spectral densities that are characterized by a fast initial Gaussian-like decay followed by a slow algebraic-like decay rate at long times.

  11. Direct experimental determination of spectral densities of molecular complexes

    SciTech Connect

    Pachón, Leonardo A.; Brumer, Paul

    2014-11-07

    Determining the spectral density of a molecular system immersed in a proteomic scaffold and in contact to a solvent is a fundamental challenge in the coarse-grained description of, e.g., electron and energy transfer dynamics. Once the spectral density is characterized, all the time scales are captured and no artificial separation between fast and slow processes need to be invoked. Based on the fluorescence Stokes shift function, we utilize a simple and robust strategy to extract the spectral density of a number of molecular complexes from available experimental data. Specifically, we show that experimental data for dye molecules in several solvents, amino acid proteins in water, and some photochemical systems (e.g., rhodopsin and green fluorescence proteins), are well described by a three-parameter family of sub-Ohmic spectral densities that are characterized by a fast initial Gaussian-like decay followed by a slow algebraic-like decay rate at long times.

  12. General performance of density functionals.

    PubMed

    Sousa, Sérgio Filipe; Fernandes, Pedro Alexandrino; Ramos, Maria João

    2007-10-25

    The density functional theory (DFT) foundations date from the 1920s with the work of Thomas and Fermi, but it was after the work of Hohenberg, Kohn, and Sham in the 1960s, and particularly with the appearance of the B3LYP functional in the early 1990s, that the widespread application of DFT has become a reality. DFT is less computationally demanding than other computational methods with a similar accuracy, being able to include electron correlation in the calculations at a fraction of time of post-Hartree-Fock methodologies. In this review we provide a brief outline of the density functional theory and of the historic development of the field, focusing later on the several types of density functionals currently available, and finishing with a detailed analysis of the performance of DFT across a wide range of chemical properties and system types, reviewed from the most recent benchmarking studies, which encompass several well-established density functionals together with the most recent efforts in the field. Globally, an overall picture of the level of performance of the plethora of currently available density functionals for each chemical property is drawn, with particular attention being dedicated to the relative performance of the popular B3LYP density functional.

  13. Interferometric Observations of Lightning Initiation

    NASA Astrophysics Data System (ADS)

    Rison, W.; Krehbiel, P. R.; Stock, M.; Edens, H. E.; Shao, X. M.; Thomas, R. J.; Stanley, M. A.

    2014-12-01

    Observations of the initial parts of lightning flashes close to Langmuir Laboratory in central New Mexico appear to show the lightning initiation process. The observations were made on August 5, 2013, from a number of flashes within 5 km of the New Mexico Tech broadband VHF interferometer (INTF). In addition to the INTF, the flashes were observed by the Langmuir Laboratory Lightning Mapping Array (LMA), and by close fast and slow antennas. For those flashes where the powers of the initial sources detected by the LMA were stronger than about 5 dBW (4 watts), the INTF observations showed that the initial LMA source was associated with a previously unidentified form of fast positive breakdown. No activity was detected prior to the positive breakdown, either by the sensitive INTF or fast electric measurements. The VHF radiation and electric field changes develop simultaneously, and the INTF shows a positive breakdown which propagates about one hundred meters. This and other features of the observations indicate that the breakdown occurs in virgin air and is produced by dielectric streamer processes in localized regions of strong electric fields. We observed both normal intracloud and cloud-to-ground discharges to be initiated by such breakdown. After the fast positive breakdown died out, the INTF showed continuous negative breakdown at the start of the positive channel, which subsequently developed into a negative leader propagating in the opposite direction of the initial positive breakdown. The results are fundamentally consistent with those obtained from modelling studies by Liu et al. (Phys. Rev. Lett.109, 025002, 2012), in which positive sprite streamers were shown to be initiated by purely dielectric breakdown, without the need of an initiating event such as a cosmic ray or energetic electron avalanches. We speculate that all lightning flashes are initiated by the fast positive events.

  14. Stochastic dynamics of cancer initiation

    NASA Astrophysics Data System (ADS)

    Foo, Jasmine; Leder, Kevin; Michor, Franziska

    2011-02-01

    Most human cancer types result from the accumulation of multiple genetic and epigenetic alterations in a single cell. Once the first change (or changes) have arisen, tumorigenesis is initiated and the subsequent emergence of additional alterations drives progression to more aggressive and ultimately invasive phenotypes. Elucidation of the dynamics of cancer initiation is of importance for an understanding of tumor evolution and cancer incidence data. In this paper, we develop a novel mathematical framework to study the processes of cancer initiation. Cells at risk of accumulating oncogenic mutations are organized into small compartments of cells and proliferate according to a stochastic process. During each cell division, an (epi)genetic alteration may arise which leads to a random fitness change, drawn from a probability distribution. Cancer is initiated when a cell gains a fitness sufficiently high to escape from the homeostatic mechanisms of the cell compartment. To investigate cancer initiation during a human lifetime, a 'race' between this fitness process and the aging process of the patient is considered; the latter is modeled as a second stochastic Markov process in an aging dimension. This model allows us to investigate the dynamics of cancer initiation and its dependence on the mutational fitness distribution. Our framework also provides a methodology to assess the effects of different life expectancy distributions on lifetime cancer incidence. We apply this methodology to colorectal tumorigenesis while considering life expectancy data of the US population to inform the dynamics of the aging process. We study how the probability of cancer initiation prior to death, the time until cancer initiation, and the mutational profile of the cancer-initiating cell depends on the shape of the mutational fitness distribution and life expectancy of the population.

  15. Thin-film optical initiator

    DOEpatents

    Erickson, Kenneth L.

    2001-01-01

    A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film. The resultant thin-film optical initiator system also comprises a fiber-optic cable connected to a low-energy laser source, an output charge, and an initiator housing. The reactive thin film, which may contain very thin embedded layers or be a co-deposit of a light-absorbing material such as carbon, absorbs the incident laser light, is volumetrically heated, and explodes against the output charge, imparting about 5 to 20 times more energy than in the incident laser pulse.

  16. Federal government expands compliance initiatives.

    PubMed

    Dugan, J K

    1997-09-01

    In 1995, the Federal government initiated Operation Restore Trust to increase enforcement of fraud and abuse regulations in Medicare and Medicaid programs. With the success of the original initiative, the government is expanding the project to additional states and program areas. The initial scrutiny of home health agencies, nursing homes, hospice care, and durable medical equipment is being expanded to managed care plans and acute care hospitals with an eye toward DRG creep. To manage this increased enforcement activity, healthcare organizations should institute comprehensive corporate compliance programs. Such programs should provide a framework that delineates responsibilities and provides a systematic means to resolve issues in a timely manner. PMID:10170318

  17. Federal government expands compliance initiatives.

    PubMed

    Dugan, J K

    1997-09-01

    In 1995, the Federal government initiated Operation Restore Trust to increase enforcement of fraud and abuse regulations in Medicare and Medicaid programs. With the success of the original initiative, the government is expanding the project to additional states and program areas. The initial scrutiny of home health agencies, nursing homes, hospice care, and durable medical equipment is being expanded to managed care plans and acute care hospitals with an eye toward DRG creep. To manage this increased enforcement activity, healthcare organizations should institute comprehensive corporate compliance programs. Such programs should provide a framework that delineates responsibilities and provides a systematic means to resolve issues in a timely manner.

  18. Density Distributions of Cyclotrimethylenetrinitramines (RDX)

    SciTech Connect

    Hoffman, D M

    2002-03-19

    As part of the US Army Foreign Comparative Testing (FCT) program the density distributions of six samples of class 1 RDX were measured using the density gradient technique. This technique was used in an attempt to distinguish between RDX crystallized by a French manufacturer (designated insensitive or IRDX) from RDX manufactured at Holston Army Ammunition Plant (HAAP), the current source of RDX for Department of Defense (DoD). Two samples from different lots of French IRDX had an average density of 1.7958 {+-} 0.0008 g/cc. The theoretical density of a perfect RDX crystal is 1.806 g/cc. This yields 99.43% of the theoretical maximum density (TMD). For two HAAP RDX lots the average density was 1.786 {+-} 0.002 g/cc, only 98.89% TMD. Several other techniques were used for preliminary characterization of one lot of French IRDX and two lot of HAAP RDX. Light scattering, SEM and polarized optical microscopy (POM) showed that SNPE and Holston RDX had the appropriate particle size distribution for Class 1 RDX. High performance liquid chromatography showed quantities of HMX in HAAP RDX. French IRDX also showed a 1.1 C higher melting point compared to HAAP RDX in the differential scanning calorimetry (DSC) consistent with no melting point depression due to the HMX contaminant. A second part of the program involved characterization of Holston RDX recrystallized using the French process. After reprocessing the average density of the Holston RDX was increased to 1.7907 g/cc. Apparently HMX in RDX can act as a nucleating agent in the French RDX recrystallization process. The French IRDX contained no HMX, which is assumed to account for its higher density and narrower density distribution. Reprocessing of RDX from Holston improved the average density compared to the original Holston RDX, but the resulting HIRDX was not as dense as the original French IRDX. Recrystallized Holston IRDX crystals were much larger (3-500 {micro}m or more) then either the original class 1 HAAP RDX or

  19. Step initiation in Parkinson's disease: influence of initial stance conditions.

    PubMed

    Rocchi, Laura; Chiari, Lorenzo; Mancini, Martina; Carlson-Kuhta, Patricia; Gross, Anne; Horak, Fay B

    2006-10-01

    In this study, we investigated how the size of preparatory postural adjustments prior to step initiation, and step length and velocity depend on initial stance width in patients with Parkinson's disease (PD) both in the ON and OFF levodopa states and in healthy elderly subjects. Twenty-one subjects with idiopathic PD and 24 age-matched healthy control subjects took two steps starting with feet on a two-plate force-platform, from either narrow or wide stance width. We measured how the magnitude of anticipatory postural adjustments (APA) and step characteristics scaled with stance width. Results showed that preparation for step initiation from wide stance was associated with a larger lateral and backward center of pressure (CoP) displacement than from narrow stance. Velocity and length of the first step were also sensitive to initial stance conditions, probably in relation with the differences in the corresponding APA. On the contrary, the duration of APA was not significantly affected by initial stance width, but it was longer in PD compared to healthy subjects, and speeded up by levodopa. Although subjects with PD did scale up the size of their APA with stance width, they had much more difficulty initiating a step from a wide stance than from a narrow stance, as shown by the greater differences from control subjects in the magnitude of the APA. Our results support the hypothesis that PD subjects maintain a narrow stance as a compensation for their inability to sufficiently increase the size of their lateral APA to allow fast step initiation in wide stance.

  20. Microenergetic Shock Initiation Studies on Deposited Films of PETN

    NASA Astrophysics Data System (ADS)

    Tappan, Alexander S.; Wixom, Ryan R.; Trott, Wayne M.; Long, Gregory T.; Knepper, Robert; Brundage, Aaron L.; Jones, David A.

    2009-06-01

    Films of the high explosive PETN (pentaerythritol tetranitrate) up to 500-μm thick have been deposited through physical vapor deposition, with the intent of creating well-defined samples for shock-initiation studies. PETN films were characterized with surface profilometry, scanning electron microscopy, x-ray diffraction, and focused ion beam nanotomography. These high-density films were subjected to strong shocks in both the in-plane and out-of-plane orientations. Initiation behavior was monitored with high-speed framing and streak camera photography. Direct initiation with a donor explosive (either RDX with binder, or CL-20 with binder) was possible in both orientations, but with the addition of a thin aluminum buffer plate (in-plane configuration only), initiation proved to be difficult due to the attenuated shock and the high density of the PETN films. Mesoscale models of microenergetic samples were created using the shock physics code CTH and compared with experimental results. The results of these experiments will be discussed in the context of small sample geometry, deposited film morphology, and density.