Science.gov

Sample records for ivory shell babylonia

  1. Impact of Tributyltin and Triphenyltin on Ivory Shell (Babylonia japonica) Populations

    PubMed Central

    Horiguchi, Toshihiro; Kojima, Mitsuhiro; Hamada, Fumihiko; Kajikawa, Akira; Shiraishi, Hiroaki; Morita, Masatoshi; Shimizu, Makoto

    2006-01-01

    We histopathologically examined gonads and chemically determined organotin compounds in tissues of the ivory shell, Babylonia japonica. Imposex (a superimposition of male-type genital organs on females) occurred in approximately 80–90% of B. japonica specimens that we examined, with the penis and vas deferens both well developed. No oviduct blockage by vas deferens formation was observed. Ovarian spermatogenesis and suppressed ovarian maturation were observed in the females that exhibited imposex, although no histopathological abnormalities were found in males. Tissue distributions of organotin compounds [tributyltin (TBT), triphenyltin (TPhT), and their metabolites] were different for butyltins and phenyltins; a remarkably high accumulation of TBT was observed in the ctenidium, osphradium, and heart, whereas high concentrations of TPhT were detected in the ovary and digestive gland. More than one-third of TBT accumulated in the digestive glands of both males and females, followed by the testis, ctenidium, muscle, and heart tissues in males and in the muscle, ovary, ctenidium, and head tissues (including the central nervous system ganglia) in females. In both males and females, more than half of total TPhT accumulated in the digestive glands, followed by the gonads. The next highest values were in the muscle, ctenidium, and heart tissues in males and in the muscle, oviduct, and head tissues in females. Both TBT and TPhT concentrations in the gonads were positively correlated with penis length in females. Our findings strongly suggest that reproductive failure in adult females accompanied by imposex, possibly induced by TBT and TPhT from antifouling paints, may have caused the marked decline of B. japonica populations in Japan. PMID:16818241

  2. Turris babylonia; re-evaluation of a species complex and description of Turris assyria, new species

    PubMed Central

    Olivera, Baldomero M.; Seronay, Romell A.; Fedosov, Alexander E.

    2012-01-01

    Turris babylonia (Linnaeus, 1758) is the designated type species of Turris, the nominate genus of the family Turridae. This species has unusual taxonomic significance, since the family Turridae is a large biodiverse group that has been highly problematic in its taxonomy. In this article, we address the identity of Turris babylonia: molecular data presented here and expanded elsewhere demonstrate that two distinctive varieties with divergent shell morphology, both conventionally assigned to Turris babylonia, are in fact different species. We describe one of the forms as Turris assyria, new species. Thus, specimens previously assigned to Turris babylonia now comprise at least two taxa, Turris babylonia and Turris assyria; it remains possible that each is a multi-species complex. Some of the numerous varieties and morphologically divergent forms in each complex may prove not to be conspecific with the two species, each precisely defined in this work by a specific barcode sequence. PMID:23133790

  3. Ivory Basements and Ivory Towers

    ERIC Educational Resources Information Center

    Fitzgerald, Tanya

    2012-01-01

    The metaphors of the ivory tower and ivory basement are used in this chapter to reflect how many women understand and experience the academy. The ivory tower signifies a place that is protected, a place of privilege and authority and a place removed from the outside world (and consequently the rigours of the market place). The ivory tower, by…

  4. Ivory Snowmen

    ERIC Educational Resources Information Center

    Mueller, Ann

    2005-01-01

    Recalling memories from her own third grade art classes, Ann Mueller, recreated an updated version for her students showing her students how to make snow scenes from Ivory Snow flakes. She showed students the video, The Snowman based on Raymond Briggs's book of the same name. Its beautiful images spur the imagination, and the musical score is…

  5. The complete mitochondrial genome of Babylonia borneensis (Gastropoda: Neogastropoda: Buccinidae).

    PubMed

    Sung, Chia-Hsuan; Tseng, Chen-Te; Wang, Liang-Jong; Li, Yu-Chi; Lu, Jenn-Kan

    2016-09-01

    The complete mitochondrial genome sequence of the Babylonia borneensis is reported for the first time in this study. The length of genome was 15 556 bp, including 13 protein-coding genes, 2 ribosomal RNA genes and 22 transfer RNA genes. The nucleotide composition of the mitogenome showed AT-rich feature, with the AT content of 68.2%. Comparison of the identity of the B. borneensis mitogenome with B. areolata, B. lani and B. lutosa was 87.5%, 87.4% and 86.9%, respectively. The construction of phylogenetic tree showed high bootstrap support value. Babylonia borneensis grouped together with other Babylons and the lineages of Buccinidae was strongly supported. In this study, our results could provide a further understanding in the phylogenetic relationships of the Neogastropoda. PMID:27158871

  6. The Ivory Tower Revisited

    ERIC Educational Resources Information Center

    Chantler, Abigail

    2016-01-01

    The corollary of the concept of the "ivory tower", as reflected in the writings of Plato and Newman amongst others, was, paradoxically, the vital importance of the university for wider society. Nevertheless from the mid-twentieth century, the esteem in which a "liberal" university education was held was diminished by rising…

  7. Structure of ivory.

    PubMed

    Locke, Michael

    2008-04-01

    Profiles with all orientations have been used to visualize the 3D structure of ivory from tusks of elephant, mammoth, walrus, hippopotamus, pig (bush, boar, and warthog), sperm whale, killer whale, and narwhal. Polished, forming, fractured, aged, and stained surfaces were prepared for microscopy using epi-illumination. Tusks have a minor peripheral component, the cementum, a soft derivative of the enamel layer, and a main core of dentine=ivory. The dentine is composed of a matrix of particles 5-20 microm in diameter in a ground substance containing dentinal tubules about 5 microm in diameter with a center to center spacing of 10-20 microm. Dentinal tubules may be straight (most) or curly (pigs). The main findings relate to the way that dentinal tubules align in sheets to form microlaminae in the length of the tusk. Microlaminae are sheets of laterally aligned dentinal tubules. They are axial but may be radial (most), angled to the forming face (pigs and hippopotamus canines), or radial but helical (narwhals). Within the microlaminae the dentinal tubules may be radial, angled to the axis (whales, walrus, and pigs), or may change their orientation from one microlamina to the next in helicoids (canines of hippopotamuses, incisors of proboscidea). In the nonbanded, featureless ivories from the hippopotamus incisors, the dentinal tubules form radial microlamina from which the arrangements in other ivories can be derived. In the canines of hippopotamuses and incisors of proboscidea, the dentinal tubule orientation changes incrementally from one microlamina to the next in a helicoid, a stack of dentinal tubules that change their orientation by 180 degrees anticlockwise. Dentinal tubules having different orientations are laid down concurrently, not layer by layer as in most examples of helicoidal architecture (e.g., insect cuticle). In proboscidean ivory, the microlaminae are radial, normal to the banding of growth layers marking the plane of deposition. They form radial

  8. Ultrastructure of oogenesis in imposex females of Babylonia areolata (Caenogastropoda: Buccinidae)

    NASA Astrophysics Data System (ADS)

    Muenpo, C.; Suwanjarat, J.; Klepal, W.

    2011-09-01

    During a tributyltin (TBT)-exposure experiment, the ultrastructural features of oogenesis have been examined in TBT-induced imposex females of Babylonia areolata and compared with those of the normal female. The results obtained from such experiment demonstrates that B. areolata exhibits a low to moderate intensity of imposex because all VDSI values are never higher than 3. Ultrastructures of germ cell development including oogonia, pre-vitellogenic, early vitellogenic, late vitellogenic and mature oocytes show that oogenesis in imposex female is similar to that of normal females except for the presence of numerous lipid droplets in the cytoplasm of the oocytes and the follicle cells in imposex females, indicating the degeneration of their oocytes. Vitellogenesis in B. areolata involves both auto- and heterosynthetic processes that resemble those of the basal gastropods and the pulmonates. In addition, the presence of cortical granules and microvilli are unique structures of this species.

  9. [Cadmium bioaccumulation and its toxicity in Babylonia areolata under different nutritional status].

    PubMed

    Xue, Ming; Ke, Cai-Huan

    2012-07-01

    An indoor exposure experiment with juvenile Babylonia areolata was conducted to study its survival, growth, cadmium (Cd) accumulation, metallothionein (MT) induction, and glycogen content as well as the DNA integrity of hepatopancreas tissue. The juveniles were starved or fed with mussel (Perna viridis) or clamworm (Perinereis aibuhitensis), and exposed to 50 microg x L(-1) of Cd2+ for 10 weeks. Prolonged starvation and simultaneous exposure to Cd reduced the survival rate of B. areolata, and its glycogen was mobilized in great extent. Feeding with P. viridis or P. aibuhitensis helped the B. areolata to combat Cd toxicity and lessen mortality. After exposed to Cd, the damage of the DNA integrity of hepatopancreas tissue for the B. areolata fed with P. viridis or P. aibuhitensis could be recovered with time, but not for the starved B. areolata. Prolonged starvation caused tissue atrophy and led to Cd accumulation and MT increase, while feeding with P. viridis or P. aibuhitensis increased the B. areolata mass and lowered the Cd accumulation and MT level because of the tissue dilution effect. The B. areolata fed with P. viridis had better growth and lower Cd content than that fed with P. aibuhitensis. This study indicated that starvation intensified the toxicity of Cd to B. areolata, while prey type had significant effects on the growth rate of the B. areolata and indirectly affected its Cd accumulation, MT induction, and glycogen consumption. It was suggested that when using gastropods such as B. areolata as the indicator species to monitor marine environmental pollution, it would be necessary to consider the effects of habitat ecological data including food richness and prey type. Moreover, in the high-density cultivation of B. areolata in factory, rational feeding and periodic measurement of Cd concentration in seawater should be made. PMID:23173475

  10. Education by Television in the Ivory Coast.

    ERIC Educational Resources Information Center

    Valerien, Jean

    1981-01-01

    The management, administration, production, and broadcasting of educational television are discussed and evaluated with respect to its use in elementary education, training of teachers, and out-of-school education in the Ivory Coast during the 1970s. (CHC)

  11. Dissecting the Illegal Ivory Trade: An Analysis of Ivory Seizures Data

    PubMed Central

    Underwood, Fiona M.; Burn, Robert W.; Milliken, Tom

    2013-01-01

    Reliable evidence of trends in the illegal ivory trade is important for informing decision making for elephants but it is difficult to obtain due to the covert nature of the trade. The Elephant Trade Information System, a global database of reported seizures of illegal ivory, holds the only extensive information on illicit trade available. However inherent biases in seizure data make it difficult to infer trends; countries differ in their ability to make and report seizures and these differences cannot be directly measured. We developed a new modelling framework to provide quantitative evidence on trends in the illegal ivory trade from seizures data. The framework used Bayesian hierarchical latent variable models to reduce bias in seizures data by identifying proxy variables that describe the variability in seizure and reporting rates between countries and over time. Models produced bias-adjusted smoothed estimates of relative trends in illegal ivory activity for raw and worked ivory in three weight classes. Activity is represented by two indicators describing the number of illegal ivory transactions – Transactions Index – and the total weight of illegal ivory transactions – Weights Index – at global, regional or national levels. Globally, activity was found to be rapidly increasing and at its highest level for 16 years, more than doubling from 2007 to 2011 and tripling from 1998 to 2011. Over 70% of the Transactions Index is from shipments of worked ivory weighing less than 10 kg and the rapid increase since 2007 is mainly due to increased consumption in China. Over 70% of the Weights Index is from shipments of raw ivory weighing at least 100 kg mainly moving from Central and East Africa to Southeast and East Asia. The results tie together recent findings on trends in poaching rates, declining populations and consumption and provide detailed evidence to inform international decision making on elephants. PMID:24250744

  12. Dissecting the illegal ivory trade: an analysis of ivory seizures data.

    PubMed

    Underwood, Fiona M; Burn, Robert W; Milliken, Tom

    2013-01-01

    Reliable evidence of trends in the illegal ivory trade is important for informing decision making for elephants but it is difficult to obtain due to the covert nature of the trade. The Elephant Trade Information System, a global database of reported seizures of illegal ivory, holds the only extensive information on illicit trade available. However inherent biases in seizure data make it difficult to infer trends; countries differ in their ability to make and report seizures and these differences cannot be directly measured. We developed a new modelling framework to provide quantitative evidence on trends in the illegal ivory trade from seizures data. The framework used Bayesian hierarchical latent variable models to reduce bias in seizures data by identifying proxy variables that describe the variability in seizure and reporting rates between countries and over time. Models produced bias-adjusted smoothed estimates of relative trends in illegal ivory activity for raw and worked ivory in three weight classes. Activity is represented by two indicators describing the number of illegal ivory transactions--Transactions Index--and the total weight of illegal ivory transactions--Weights Index--at global, regional or national levels. Globally, activity was found to be rapidly increasing and at its highest level for 16 years, more than doubling from 2007 to 2011 and tripling from 1998 to 2011. Over 70% of the Transactions Index is from shipments of worked ivory weighing less than 10 kg and the rapid increase since 2007 is mainly due to increased consumption in China. Over 70% of the Weights Index is from shipments of raw ivory weighing at least 100 kg mainly moving from Central and East Africa to Southeast and East Asia. The results tie together recent findings on trends in poaching rates, declining populations and consumption and provide detailed evidence to inform international decision making on elephants. PMID:24250744

  13. Taking the Plunge off the Ivory Tower.

    ERIC Educational Resources Information Center

    Mauzerall, Jorgette

    1997-01-01

    Relates the experiences of a white academic teaching in a black rural state college--a plunge into the world of black experience which shocked the academic. States that everything was different--students' names, their manner of dress, their reaction to the O.J. Simpson verdict. Finds that leaving the ivory tower was not easy, but the job exceeded…

  14. Using morphometric and analytical techniques to characterize elephant ivory.

    PubMed

    Singh, Rina Rani; Goyal, Surendra Prakash; Khanna, Param Pal; Mukherjee, Pulok Kumar; Sukumar, Raman

    2006-10-16

    There is a need to characterize Asian elephant ivory and compare with African ivory for controlling illegal trade and implementation of national and international laws. In this paper, we characterize ivory of Asian and African elephants using Schreger angle measurements, elemental analysis {X-ray fluorescence (XRF), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and inductively coupled plasma-mass spectroscopy (ICP-MS)} and isotopic analysis. We recorded Schreger angle characteristics of elephant ivory at three different zones in ivory samples of African (n=12) and Asian (n=28) elephants. The Schreger angle ranged from 32 degrees to 145 degrees and 30 degrees to 153 degrees in Asian and African ivory, respectively. Elemental analysis (for Asian and African ivory) by XRF, ICP-AES and ICP-MS provided preliminary data. We attempted to ascertain source of origin of Asian elephant ivory similarly as in African ivory based on isotopes of carbon, nitrogen and strontium. We determined isotopic ratios of carbon (n=31) and nitrogen (n=31) corresponding to diet and rainfall, respectively. Reference ivory samples from five areas within India were analyzed using collagen and powder sample and the latter was found more suitable for forensic analysis. During our preliminary analysis, the range of delta13C values (-13.6+/-0.15 per thousand and -25.6+/-0.15 per thousand) and delta15N values (10.2+/-0.15 per thousand and 3.5+/-0.15 per thousand) were noted. PMID:16891073

  15. Antimicrobial activities of the tissue extracts of Babylonia spirata Linnaeus, 1758 (Mollusca: Gastropoda) from Thazhanguda, southeast coast of India

    PubMed Central

    Periyasamy, N; Srinivasan, M; Balakrishnan, S

    2012-01-01

    Objective To investigate the antimicrobial activity of the tissue extracts of Babylonia spirata (B. spirata) against nine bacterial and three fungal pathogens. Methods Crude extract of gastropod was tested for inhibition of bacterial and fungal growth. Antibacterial assay was carried out by disc diffusion method and in vitro antifungal activity was determined against Czapex Dox agar. The antimicrobial activity was measured accordingly based on the inhibition zone around the disc impregnated with gastropod extract. Molecular size of muscle protein was determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). And fourier transform infrared spectroscopy (FTIR) spectro photometry analysis was also studied. Results The maximum inhibition zone (12 mm) was observed against Pseudomonas aeruginosa in the crude ethanol extract of B. spirata and the minimum inhibition zone (2 mm) was noticed against Staphylococcus aureus in the crude methanol extract of B. spirata. Water extract of B. spirata showed the highest activity against Vibrio parahaemolyticus, Staphylococcus aureus and Candida albicans. Ethanol, acetone, methanol, chloroform and water extracts showed antimicrobial activity against almost all the bacteria and fungus. Compared with water extracts, ethanol and methanol extracts showed higher activity against all pathogens. The molecular weight of protein of the gastropod sample ranged from 2-110 kDa on SDS-PAGE. FTIR analysis revealed the presence of bioactive compounds signals at different ranges. Conclusions The research shows that the great medicinal value of the gastropod muscle of B. spirata may be due to high quality of antimicrobial compounds. PMID:23569831

  16. Phillips goes subsea trees in Ivory Coast

    SciTech Connect

    Bryngelson, R.H.

    1982-11-15

    Describes installation of 3 wet, diver-assist trees, in the Espoir field offshore Ivory Coast, as part of Phillips Petroleum's plans to use 5 satellite wells with downhole completion equipment and subsea production trees. Simplicity in design and attention to training has resulted in an installation time of about 3 weeks for one of the largest subsea trees in the industry. Presents diagram showing the converted jackup, Dan Duke drilling unit, which supports equipment to handle production from subsea wells.

  17. Button botany: plasmodesmata in vegetable ivory.

    PubMed

    Witztum, Allan; Wayne, Randy

    2012-07-01

    The hard endosperm of species of the palm genus Phytelephas (elephant plant), known as vegetable ivory, was used in the manufacture of buttons in the nineteenth century, the early twentieth century, and again in more recent times. Here, we show that the pathways for intercellular communication, including the cytoplasm in opposite pits and the plasmodesmata that traverse the cell wall, can be visualized in century-old inexpensive buttons that are readily available in antique shops. PMID:21887607

  18. [Implementation of palliative care in Ivory Coast].

    PubMed

    Coulibaly, J Didi-Kouko; Datie, A-M; Binlin-Dadie, R; Kouame, I; N'guessan, Zc; Barouan, M-C; Koffi, E; Coulibaly, I; Mensah, J; Yenou, H Memain; Dedomey, E; Echimane, Ka; Plo, Kj; Kouassi, B

    2009-05-01

    Ivory Coast adhered to the strategy of the primary cares of health whose leading principles served basis to the definition of the National politics of sanitary development, exposed in the National plan of sanitary development 1996-2005. The improvement of the quality of the cares is the main objective of this plan. The attack of this objective cannot make itself without the hold in account of the palliative cares that are a component of the cares for the patients affected by chronic and incurable affections, since the diagnosis until the death and even after the death. Conscious of the necessity to develop the palliative cares to improve the quality of life of the patients and their families, the ministry in charge of health, in collaboration with the partners to the development, initiated a project of development of the palliative care in Ivory Coast. It is about an innovating gait in Ivory Coast concerning politics of health. This work has for goal to present the big lines and the setting in which this politics has been put in place. PMID:19423486

  19. Geographic variation of stable isotopes in African elephant ivory

    NASA Astrophysics Data System (ADS)

    Ziegler, S.; Merker, S.; Jacob, D.

    2012-04-01

    In 1989, the international community listed the African elephant in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) thus prohibiting commercial ivory trade. Recent surveillance data show that the illegal trade in ivory has been growing worldwide. Long-term preservation of many of the African elephant populations can be supported with a control mechanism that helps with the implementation of remedial conservation action. Therefore, setting up a reference database that predicts the origin of ivory specimens can assist in determining smuggling routes and the provenance of illegal ivory. Our research builds on earlier work to seek an appropriate method for determining the area of origin for individual tusks. Several researchers have shown that the provenance of elephant ivory can be traced by its isotopic composition, but this is the first attempt to produce an integrated isotopic reference database of elephant ivory provenance. We applied a combination of various routine geochemical analyses to measure the stable isotope ratios of hydrogen, carbon, nitrogen, oxygen, and sulphur. Up to now, we analysed 606 ivory samples of known geographical origin from African range states, museums and private collections, comprising 22 African elephant range states. The isotopic measurements were superimposed with data layers from vegetation, geology and climate. A regression function for the isotope composition of the water isotopes in precipitation and collagen in ivory was developed to overcome the problem of imprecise origin of some of the sampled material. Multivariate statistics, such as nearest neighborhood and discriminate analysis were applied to eventually allow a statistical determination of the provenance for ivory of unknown origin. Our results suggest that the combination of isotopic parameters have the potential to provide predictable and complementary markers for estimating the origin of seized elephant ivory.

  20. Ivory vertebra: imaging findings in different diagnoses*

    PubMed Central

    Braun, Richard Andreas; Milito, Carlos Felipe do Rego Barros; Goldman, Suzan Menasce; Fernandes, Eloy de Ávila

    2016-01-01

    Low back pain is often managed at all levels of healthcare. In general, diagnostic investigation begins with radiography of the lumbar spine. In addition to the most common findings, radiologists can identify increased density of a vertebral body, referred to as ivory vertebra. The objective of this study was to describe the main diseases that can present with this radiologic sign, such as Hodgkin lymphoma, Paget's disease, metastatic prostate cancer, breast cancer, and osteomyelitis. It is extremely important that radiologists be aware of this finding in order to inform the requesting physician of the possible etiologies, given that it can be the initial radiologic presentation for these diseases. PMID:27141135

  1. Ivory vertebra: imaging findings in different diagnoses.

    PubMed

    Braun, Richard Andreas; Milito, Carlos Felipe do Rego Barros; Goldman, Suzan Menasce; Fernandes, Eloy de Ávila

    2016-01-01

    Low back pain is often managed at all levels of healthcare. In general, diagnostic investigation begins with radiography of the lumbar spine. In addition to the most common findings, radiologists can identify increased density of a vertebral body, referred to as ivory vertebra. The objective of this study was to describe the main diseases that can present with this radiologic sign, such as Hodgkin lymphoma, Paget's disease, metastatic prostate cancer, breast cancer, and osteomyelitis. It is extremely important that radiologists be aware of this finding in order to inform the requesting physician of the possible etiologies, given that it can be the initial radiologic presentation for these diseases. PMID:27141135

  2. New data on selected Ivory Coast tektites.

    NASA Technical Reports Server (NTRS)

    Cuttitta, F.; Carron, M. K.; Annell, C. S.

    1972-01-01

    Fourteen Ivory Coast tektites exhibit a range of bulk indices of refraction of 1.5156 to 1.5217 plus or minus 0.0004 and of bulk specific gravities of 2.428 to 2.502 plus or minus 0.005. Seven of these Ivory Coast (IVC) tektites were analyzed for major and minor element content. Compared to tektites from other strewn fields, their SiO2 content is low (67.2-69.1%), Al2O3 relatively high (15.8-16.8%), and total iron relatively high but with a more restricted range (6.3-6.8% as FeO). Their lime content is low (0.71-1.35%) compared to Australasian tektites but their MgO/CaO ratio (about 3.1) is unusually high. All other tektite groups have Na2O/K2O ratios less than unity, but the Na2O/K2O ratio of the IVC tektites is slightly greater than unity. Their K/Rb ratios range from 200 to 256 and average 227.

  3. [Diabetes in Ivory Coast: special epidemiological features].

    PubMed

    Oga, A S S; Tebi, A; Aka, J; Adouéni, K V; Malan, K A; Kouadio, L P; Lokrou, A

    2006-06-01

    Within less than a quarter century diabetes has become a health problem in developing countries. In Africa this metabolic disorder is found in a wide variety of sometimes atypical forms. The purpose of this study was to highlight the special epidemiological features of medically diagnosed diabetes in Ivory Coast. Data from the files of 10320 African patients who presented at a major national outpatient care centre between January 1, 1991 and December 31, 2000 were compiled and analyzed. Findings showed that morbidity gradually increased from 30 to 49 years then stabilized from 50 to 69 years with a higher rate in males between 30 and 49 years. One of the five national ethnic groups appeared to be most affected and two appeared to be relatively unaffected. On the basis of several criteria, 5968 patients were classified as type 1 in 11.8% of cases, type 2 without excess body weight in 48.7% and type 2 with excess body weight in 39.5%. The second of these identified groups was characterized by intermediate-discovered glycaemia and older age at diagnosis. Epidemiological features included age of occurrence and higher morbidity in young male patients, probable higher premature mortality, likely links with socio-cultural environmental factors and existence of two type 2 subgroups. This profile underlines the challenges of screening, management and prevention of diabetes in Ivory Coast. PMID:16924814

  4. Getting The Faculty Out of Its Ivory Tower

    ERIC Educational Resources Information Center

    Hopp, Joyce W.

    1976-01-01

    Planning and implementing a community health education practicum for undergraduate students serves to involve faculty in the actual delivery of health services, and effectively breaks down "Ivory Tower" isolation. (MB)

  5. New data on selected Ivory Coast tektites

    USGS Publications Warehouse

    Cuttitta, F.; Carron, M.K.; Annell, C.S.

    1972-01-01

    Fourteen Ivory Coast tektites exhibit a range of bulk indices of refraction of 1.5156 to 1.5217 ?? 0.0004 and of bulk specific gravities of 2.428 to 2.502 ??0.005. Seven of these Ivory Coast (IVC) tektites were analyzed for major and minor element content. Compared to tektites from other strewn fields, their SiO2 content is low (67.2-69.1 %), A12O3 relatively high (15.8-16.8 %), and total iron relatively high but with a more restricted range (6.3-6.8 % as FeO). Their lime content is low (0.71-1.35%) compared to Australasian tektites but their MgO CaO ratio (about 3.1) is unusually high. All other tektite groups have Na2O K2O ratios less than unity, but the Na2O K2O ratio of the IVC tektites is slightly greater than unity. Their K Rb ratios range from 200 to 256 and average 227, which is higher than those determined for Australasian tektites, but similar to some obtained for moldavites. The Li content (41-48 ppm) is about the same as that of the Australasian tektites, but the Cs and Rb are lower, being 1.9 to 2.9 and 57 to 86 ppm, respectively. The IVC tektites are high in Cr (260-375 ppm), Co (19-25 ppm) and Ni (101-167 ppm), and particularly in Pb (<10-18 ppm), Cu (13-21 ppm) and Ga (14-23 ppm). The high Cr Ni ratios of the IVC tektites (range 2-3.6) are similar to those found for australites, philippinites and thailandites, but not the javanites and indochinites. Evaluation of these and other reported data show that compositional similarities between the IVC tektites and green or black Bosumtwi Crater glasses strongly support the hypothesis of a common impact origin-i.e. the Bosumtwi Crater site. Comparison of the IVC tektite composition with those of returned lunar materials (gabbros, basalts, breccia and soils) do not support a lunar origin for the Ivory Coast tektites. ?? 1972.

  6. Infrasound from lightning measured in Ivory Coast

    NASA Astrophysics Data System (ADS)

    Farges, T.; Matoza, R. S.

    2011-12-01

    It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. More than two thirds (42) of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes, ...). Some of the IMS stations are located where worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS infrasound station has been installed in Ivory Coast for 8 years. The optical space-based instrument OTD measured a rate of 10-20 flashes/km^2/year in that country and showed strong seasonal variations (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 3 years of data (2005-2008).

  7. Geochemistry and age of Ivory Coast tektites and microtektites

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Bottomley, Richard; Glass, Billy P.; Storzer, Dieter

    1997-04-01

    Ivory Coast tektites were first reported in 1934 from a geographically restricted area at Ivory Coast, West Africa. Although some additional specimens have been found later, the total number remains small (a few hundred). The Bosumtwi impact crater in Ghana is most likely the source crater for the Ivory Coast tektites, based on the finding that the tektites and the crater have the same age as well as similar isotopic and chemical compositions. In addition to tektites on land, microtektites were found in (so far) eleven deep-sea cores off the West African coast, between about 9°N and 11°S and 0° and 23°W, defining the extent of the Ivory Coast tektite strewn field. In this study we analyzed eleven Ivory Coast tektites for their major and trace element composition, studied their petrographical characteristics, provided major element data for 111 microtektites, and major and trace element data for four microtektites. We determined the 40Ar sbnd 39Ar step-heating age of five Ivory Coast tektites and four microtektites and obtained fission-track dates for ten tektites and one Bosumtwi impact glass. The tektites have very small intersample and intrasample variations of their major and trace element composition. 111 Ivory Coast microtektites from eleven cores were analyzed for their major element compositional range. Their compositional range is significantly wider than that of the Ivory Coast tektites, but the majority of all microtektites have compositions very similar to those of the tektites (within a factor of 1.2). Trace element compositions of the tektites also show little variation between samples. The samples do not show any distinct Eu anomaly in the REE patterns. This characteristic, as well as the high absolute REE abundances and La NYb N ratios of about 8, indicate that Archean rocks are plausible source rocks. The major and trace element contents of four individually analyzed Ivory Coast microtektites show compositions that are very similar to those of

  8. Phillips goes subsea trees in Ivory Coast

    SciTech Connect

    Bryngelson, R.H.

    1982-11-15

    Describes installation of 3 satellite subsea trees in 500 ft of water from a semisubmersible drilling rig. These wet, diver-assist trees are part of Phillips Petroleum's early development and production program (EDPP) for the Espoir field offshore Ivory Coast, with plans calling for 5 satellite wells with downhole completion equipment and subsea production trees. Diagram shows how a converted jackup, Dan Duke, supports equipment to handle production from subsea wells. Table gives time breakdown of subsea tree installation. Before mobilizing the subsea trees, control system, and tubulars to the rig, a study of deck layout, payloads, and traffic patterns was performed. Concludes that, based on experience in this project and the cost differences between purchase and installation costs, final success is 90% dependent on informed and trained field personnel after engineering, design, and manufacturing; attention to installation procedures and training of field and operational personnel are as critical or more critical than design changes to equipment; and selection of a supplier for high technology equipment, based on a low bid alone, may not translate into lower installation costs.

  9. The oldest rock of Ivory Coast

    NASA Astrophysics Data System (ADS)

    Kouamelan, Alain Nicaise; Djro, Sagbrou Chérubin; Allialy, Marc Ephrem; Paquette, Jean-Louis; Peucat, Jean-Jacques

    2015-03-01

    The tonalitic gneiss of Balmer (TGB), in the SASCA area of south-western Ivory Coast, previously dated at 3141 ± 2 Ma using the single zircon evaporation method, is regarded as a relic of Archean rock within the Paleoproterozoic (Birimian) formation of the West African Craton (WAC). We present new geochronological data for the TGB using the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method. We obtain a U-Pb age of 3207 ± 7 Ma for abundant zircons extracted from the tonalitic gneiss, and interpret this age as that of the magmatic protolith because of the igneous-type homogeneous zircon population. Certain magmatic zircon edges and some round zircons define an upper intercept age of 3155 ± 17 Ma which could represent overgrowths during gneissification. It appears that the TGB was not affected by the events posterior to its genesis, i.e. the Liberian (2.9-2.7 Ga) and Eburnean (2.4-2.0 Ga) events. Additionally, the TGB proves to be a juvenile Leonian rock, as indicated by the Nd model age of 3456 Ma, and could also constitute the protolith of the granulitic grey gneisses and charnockites of the Man area, which are 150-400 Ma younger.

  10. Infrasound from lightning measured in Ivory Coast

    NASA Astrophysics Data System (ADS)

    Farges, T.; Millet, C.; Matoza, R. S.

    2012-04-01

    It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. More than two thirds (42) of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes, …). Some of the IMS stations are located where worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS infrasound station has been installed in Ivory Coast for 9 years. The lightning rate of this region is 10-20 flashes/km2/year from space-based instrument OTD (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 4 years of data (2005-2009). For short lightning distances (less than 20 km), up to 60 % of lightning detected by WWLLN has been one-to-one correlated

  11. Illegal killing for ivory drives global decline in African elephants.

    PubMed

    Wittemyer, George; Northrup, Joseph M; Blanc, Julian; Douglas-Hamilton, Iain; Omondi, Patrick; Burnham, Kenneth P

    2014-09-01

    Illegal wildlife trade has reached alarming levels globally, extirpating populations of commercially valuable species. As a driver of biodiversity loss, quantifying illegal harvest is essential for conservation and sociopolitical affairs but notoriously difficult. Here we combine field-based carcass monitoring with fine-scale demographic data from an intensively studied wild African elephant population in Samburu, Kenya, to partition mortality into natural and illegal causes. We then expand our analytical framework to model illegal killing rates and population trends of elephants at regional and continental scales using carcass data collected by a Convention on International Trade in Endangered Species program. At the intensively monitored site, illegal killing increased markedly after 2008 and was correlated strongly with the local black market ivory price and increased seizures of ivory destined for China. More broadly, results from application to continental data indicated illegal killing levels were unsustainable for the species between 2010 and 2012, peaking to ∼ 8% in 2011 which extrapolates to ∼ 40,000 elephants illegally killed and a probable species reduction of ∼ 3% that year. Preliminary data from 2013 indicate overharvesting continued. In contrast to the rest of Africa, our analysis corroborates that Central African forest elephants experienced decline throughout the last decade. These results provide the most comprehensive assessment of illegal ivory harvest to date and confirm that current ivory consumption is not sustainable. Further, our approach provides a powerful basis to determine cryptic mortality and gain understanding of the demography of at-risk species. PMID:25136107

  12. Illegal killing for ivory drives global decline in African elephants

    PubMed Central

    Wittemyer, George; Northrup, Joseph M.; Blanc, Julian; Douglas-Hamilton, Iain; Omondi, Patrick; Burnham, Kenneth P.

    2014-01-01

    Illegal wildlife trade has reached alarming levels globally, extirpating populations of commercially valuable species. As a driver of biodiversity loss, quantifying illegal harvest is essential for conservation and sociopolitical affairs but notoriously difficult. Here we combine field-based carcass monitoring with fine-scale demographic data from an intensively studied wild African elephant population in Samburu, Kenya, to partition mortality into natural and illegal causes. We then expand our analytical framework to model illegal killing rates and population trends of elephants at regional and continental scales using carcass data collected by a Convention on International Trade in Endangered Species program. At the intensively monitored site, illegal killing increased markedly after 2008 and was correlated strongly with the local black market ivory price and increased seizures of ivory destined for China. More broadly, results from application to continental data indicated illegal killing levels were unsustainable for the species between 2010 and 2012, peaking to ∼8% in 2011 which extrapolates to ∼40,000 elephants illegally killed and a probable species reduction of ∼3% that year. Preliminary data from 2013 indicate overharvesting continued. In contrast to the rest of Africa, our analysis corroborates that Central African forest elephants experienced decline throughout the last decade. These results provide the most comprehensive assessment of illegal ivory harvest to date and confirm that current ivory consumption is not sustainable. Further, our approach provides a powerful basis to determine cryptic mortality and gain understanding of the demography of at-risk species. PMID:25136107

  13. Nursing research's ivory tower was knocked down long ago.

    PubMed

    Read, Susan

    2016-04-20

    As a retired research nurse whose career spanned nearly 50 years, I am well qualified to challenge the view that nursing research used to consist of 'obscure studies carried out in distant ivory towers' with little connection to actual nurses (editorial, April 6). PMID:27097203

  14. What it is like to live in the Ivory Coast

    SciTech Connect

    Liddell, W.W.

    1981-09-01

    Exploration and production activity is increasing in the Ivory Coast on the strength of a small discovery by Exxon in 1977 and unofficial reports that Phillips has found a field in deep water which approaches Prudhoe Bay in size. Phillips is bringing five offshore rigs into Ivoirian waters.

  15. Domestication of the Ivory Tower: Institutional Adaptation to Cultural Distance.

    ERIC Educational Resources Information Center

    Barnhardt, Ray

    2002-01-01

    Examines the experiences of Native and non-Native Alaskan teacher educators in rural Alaska, describing opportunities for capitalizing on field settings available to faculty at any university. Discusses reasons for putting faculty in the field, looking at field-based training for Native teachers, the "ivory tower" versus the real world,…

  16. Secondary School Alternatives in the Ivory Coast: Considerations.

    ERIC Educational Resources Information Center

    McAnany, Emile G.

    Intended to provide information for Ivorian decision makers, this paper presents an overview of technological alternatives for the delivery of instruction at the post-primary level and their accompanying costs. Five alternatives for regular secondary education as it now exists in the Ivory Coast are reviewed: traditional, audiovisual-traditional,…

  17. Oxygen isotope studies of ivory coast tektites and impactite glass from the bosumtwi crater, ghana.

    PubMed

    Taylor, H P; Epstein, S

    1966-07-01

    Oxygen isotope analyses were obtained for six Ivory Coast tektites, two samples of Bosumtwi Crater glass, and two new moldavites. The Ivory Coast tektites are 2 to 5 per mil richer in oxygen-18 than other known tektites, and they are similar in oxygen-18 content to the impactite glass from the nearby Bosumtwi Crater. These data are compatible with a terrestrial origin for the Ivory Coast tektites. PMID:17831505

  18. Fourier-transform Raman spectroscopy of ivory: II. Spectroscopic analysis and assignments

    NASA Astrophysics Data System (ADS)

    Edwards, H. G. M.; Farwell, D. W.; Holder, J. M.; Lawson, E. E.

    1997-11-01

    The FT-Raman spectra of African and Asian elephant and woolly mammoth ivory are reported and comprehensive molecular vibrational assignments are proposed. Since ivory is composed of proteinaceous collagen embedded in an inorganic matrix of carbonated hydroxyapatite, the Raman spectrum of pure natural collagen recorded under similar conditions aids the identification of the vibrational modes. Several bands are identified which could be used for the Raman spectroscopic characterisation of the mammalian ivories studied.

  19. Fourier-transform Raman spectra of ivory III: identification of mammalian specimens

    NASA Astrophysics Data System (ADS)

    Edwards, H. G. M.; Farwell, D. W.; Holder, J. M.; Lawson, E. E.

    1997-11-01

    The FT-Raman spectra of six mammalian ivories, other than elephant and mammoth, are presented and spectral differences formulated into a protocol for the identification of animal species from the ivory samples. In this study, sperm whale, walrus, wart hog, narwhal, hippopotamus and domestic pig are considered. The results, which are obtained non-destructively from a variety of specimens, suggest that FT-Raman spectroscopy provides a potentially useful method for the identification of mammalian ivory.

  20. 76 FR 15047 - Port of Ivory, LLC-Operation Exemption-Line of Railroad in Tulare County, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-18

    ... Surface Transportation Board Port of Ivory, LLC--Operation Exemption--Line of Railroad in Tulare County, CA Port of Ivory, LLC (Port), a limited liability company and noncarrier, has filed a verified notice... Valley Railroad Company (SJVR) at a point known as Ivory (milepost 232.3 on SJVR's Exeter...

  1. Geographic variations in the composition of ivory of the African elephant (Loxodonta africana).

    PubMed

    Raubenheimer, E J; Brown, J M; Rama, D B; Dreyer, M J; Smith, P D; Dauth, J

    1998-08-01

    Tracing the source of origin of illegal ivory will contribute to the identification of poorly managed game parks and facilitate steps taken to prevent the African elephant from becoming extinct. This study was aimed at establishing a database on the composition of ivory obtained from elephant sanctuary areas in Southern Africa. Fragments of elephant ivory from seven geographically distinct areas in South Africa, Namibia and Botswana were analysed for inorganic and organic content. A total of 20 elements was detected in the inorganic fraction of ivory, some in concentrations as low as 0.25 microg/g. The concentrations of calcium, phosphate, magnesium, fluoride, cobalt and zinc showed statistically significant differences (p < 0.007) between ivory obtained from different regions. Analyses of the organic fraction identified 17 amino acids. Ivory from arid regions showed significantly lower proline plus hydroxyproline content and under-hydroxylation of lysine residues. This study indicates that chemical analyses of ivory could be beneficial in tracing the source of illegal ivory. PMID:9758047

  2. Ivory vertebra on 18F-sodium fluoride scan: an old sign in a new modality.

    PubMed

    Oldan, Jorge Daniel; Kuzminski, Samuel; James, Olga

    2014-11-01

    We report a case of ivory vertebra on 18F-sodium fluoride. A prostate cancer patient had a 18F-sodium fluoride PET scan to evaluate overall spread of disease. In addition to other findings of metastatic disease, the patient had an ivory vertebra. PMID:24566404

  3. The Influence of Predisposing, Enabling and Need Factors on Condom Use in Ivory Coast

    ERIC Educational Resources Information Center

    Ngamini Ngui, Andre

    2010-01-01

    The main objective of this study was to identify key determinants of condom use in Ivory Coast. Data stem from Ivory Coast Demographic Health Survey (DHS) conducted by ORC Macro in 2005 among a representative sample of 9,686 persons aged 15 - 49. Following the behavioral model, we use logistic regression to assess the effect of predisposing,…

  4. 75 FR 53012 - Culturally Significant Object Imported for Exhibition Determinations: “Ivory Mirror Case”

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-30

    ... Culturally Significant Object Imported for Exhibition Determinations: ``Ivory Mirror Case'' SUMMARY: Notice..., I hereby determine that the object to be included in the exhibition ``Ivory Mirror Case,'' imported from abroad for temporary exhibition within the United States, is of cultural significance. The...

  5. Detection of Mycobacterium ulcerans DNA in the Environment, Ivory Coast

    PubMed Central

    Tian, Roger Bi Diangoné; Niamké, Sébastian; Tissot-Dupont, Hervé; Drancourt, Michel

    2016-01-01

    Background Ivory Coast is a West African country with the highest reported cases of Buruli ulcer, a disabling subcutaneous infection due to Mycobacterium ulcerans. However, the prevalence of environmental M. ulcerans is poorly known in this country. Methods We collected 496 environmental specimens consisting of soil (n = 100), stagnant water (n = 200), plants (n = 100) and animal feces (n = 96) in Ivory Coast over five months in the dry and wet seasons in regions which are free of Buruli ulcer (control group A; 250 specimens) and in regions where the Buruli ulcer is endemic (group B; 246 specimens). After appropriate total DNA extraction incorporating an internal control, the M. ulcerans IS2404 and KR-B gene were amplified by real-time PCR in samples. In parallel, a calibration curve was done for M. ulcerans Agy99 IS2404 and KR-B gene. Results Of 460 samples free of PCR inhibition, a positive real-time PCR detection of insertion sequence IS2404 and KR-B gene was observed in 1/230 specimens in control group A versus 9/230 specimens in group B (P = 0.02; Fisher exact test). Positive specimens comprised seven stagnant water specimens, two feces specimens confirmed to be of Thryonomys swinderianus (agouti) origin by real-time PCR of the cytb gene; and one soil specimen. Extrapolation from the calibration curves indicated low inoculums ranging from 1 to 102 mycobacteria/mL. Conclusion This study confirms the presence of M. ulcerans in the watery environment surrounding patients with Buruli ulcer in Ivory Coast. It suggests that the agouti, which is in close contacts with populations, could play a role in the environmental cycle of M. ulcerans, as previously suggested for the closely related possums in Australia. PMID:26982581

  6. Biodegradation of ivory (natural apatite): possible involvement of fungal activity in biodeterioration of the Lewis Chessmen.

    PubMed

    Pinzari, Flavia; Tate, James; Bicchieri, Marina; Rhee, Young Joon; Gadd, Geoffrey Michael

    2013-04-01

    Fungal biodeterioration of ivory was investigated with in vitro inoculation of samples obtained from boar and walrus tusks with the fungi Aspergillus niger and Serpula himantioides, species of known geoactive abilities. A combination of light and scanning electron microscopy together with associated analytical techniques was used to characterize fungal interactions with the ivory, including changes in ivory composition, dissolution and tunnelling, and the formation of new biominerals. The research was aimed at providing further understanding of the potential roles of fungi in the colonization and deterioration of ivory in terrestrial environments, but also contributes to our knowledge regarding the possible origins of the surface damage observed on early medieval sculptures made largely from walrus tusks, referred to as 'the Lewis hoard of gaming pieces', that were presumably produced for playing chess. The experiments have shown that the possibility of damage to ivory being caused by fungi is realistic. Scanning electron microscopy revealed penetration of fungal hyphae within cracks in the walrus tusk that showed also widespread tunnelling by fungal hyphae as well as 'fungal footprints' where the surface was etched as a consequence of mycelial colonization. Similar phenomena were observed with boar tusk ivory, while production of metabolites could lead to complete dissolution of the sample. Colonization of ivory and/or exposure to fungal activity lead to extensive secondary biomineral formation, and this was identified as calcium oxalate, mainly as the monohydrate, whewellite. PMID:23157656

  7. Using DNA to track the origin of the largest ivory seizure since the 1989 trade ban

    PubMed Central

    Wasser, Samuel K.; Mailand, Celia; Booth, Rebecca; Mutayoba, Benezeth; Kisamo, Emily; Clark, Bill; Stephens, Matthew

    2007-01-01

    The illegal ivory trade recently intensified to the highest levels ever reported. Policing this trafficking has been hampered by the inability to reliably determine geographic origin of contraband ivory. Ivory can be smuggled across multiple international borders and along numerous trade routes, making poaching hotspots and potential trade routes difficult to identify. This fluidity also makes it difficult to refute a country's denial of poaching problems. We extend an innovative DNA assignment method to determine the geographic origin(s) of large elephant ivory seizures. A Voronoi tessellation method is used that utilizes genetic similarities across tusks to simultaneously infer the origin of multiple samples that could have one or more common origin(s). We show that this joint analysis performs better than sample-by-sample methods in assigning sample clusters of known origin. The joint method is then used to infer the geographic origin of the largest ivory seizure since the 1989 ivory trade ban. Wildlife authorities initially suspected that this ivory came from multiple locations across forest and savanna Africa. However, we show that the ivory was entirely from savanna elephants, most probably originating from a narrow east-to-west band of southern Africa, centered on Zambia. These findings enabled law enforcement to focus their investigation to a smaller area and fewer trade routes and led to changes within the Zambian government to improve antipoaching efforts. Such outcomes demonstrate the potential of genetic analyses to help combat the expanding wildlife trade by identifying origin(s) of large seizures of contraband ivory. Broader applications to wildlife trade are discussed. PMID:17360505

  8. Using DNA to track the origin of the largest ivory seizure since the 1989 trade ban.

    PubMed

    Wasser, Samuel K; Mailand, Celia; Booth, Rebecca; Mutayoba, Benezeth; Kisamo, Emily; Clark, Bill; Stephens, Matthew

    2007-03-01

    The illegal ivory trade recently intensified to the highest levels ever reported. Policing this trafficking has been hampered by the inability to reliably determine geographic origin of contraband ivory. Ivory can be smuggled across multiple international borders and along numerous trade routes, making poaching hotspots and potential trade routes difficult to identify. This fluidity also makes it difficult to refute a country's denial of poaching problems. We extend an innovative DNA assignment method to determine the geographic origin(s) of large elephant ivory seizures. A Voronoi tessellation method is used that utilizes genetic similarities across tusks to simultaneously infer the origin of multiple samples that could have one or more common origin(s). We show that this joint analysis performs better than sample-by-sample methods in assigning sample clusters of known origin. The joint method is then used to infer the geographic origin of the largest ivory seizure since the 1989 ivory trade ban. Wildlife authorities initially suspected that this ivory came from multiple locations across forest and savanna Africa. However, we show that the ivory was entirely from savanna elephants, most probably originating from a narrow east-to-west band of southern Africa, centered on Zambia. These findings enabled law enforcement to focus their investigation to a smaller area and fewer trade routes and led to changes within the Zambian government to improve antipoaching efforts. Such outcomes demonstrate the potential of genetic analyses to help combat the expanding wildlife trade by identifying origin(s) of large seizures of contraband ivory. Broader applications to wildlife trade are discussed. PMID:17360505

  9. Legal ivory trade in a corrupt world and its impact on African elephant populations.

    PubMed

    Bennett, Elizabeth L

    2015-02-01

    Illegal hunting of African elephants (Loxodonta africana) for ivory is causing rapid declines in their populations. Since 2007, illegal ivory trade has more than doubled. African elephants are facing the most serious conservation crisis since 1989, when international trade was banned. One solution proposed is establishment of a controlled legal trade in ivory. High prices for ivory mean that the incentives to obtain large quantities are high, but the quantity of tusks available for trade are biologically constrained. Within that context, effective management of a legal ivory trade would require robust systems to be in place to ensure that ivory from illegally killed elephants cannot be laundered into a legal market. At present, that is not feasible due to corruption among government officials charged with implementing wildlife-related legislation. With organized criminal enterprises involved along the whole commodity chain, corruption enables the laundering of illegal ivory into legal or potentially legal markets. Poachers and traffickers can rapidly pay their way out of trouble, so the financial incentives to break the law heavily outweigh those of abiding by it. Maintaining reliable permitting systems and leak-proof chains of custody in this context is challenging, and effective management breaks down. Once illegal ivory has entered the legal trade, it is difficult or impossible for enforcement officers to know what is legal and illegal. Addressing corruption throughout a trade network that permeates countries across the globe will take decades, if it can ever be achieved. That will be too late for wild African elephants at current rates of loss. If we are to conserve remaining wild populations, we must close all markets because, under current levels of corruption, they cannot be controlled in a way that does not provide opportunities for illegal ivory being laundered into legal markets. PMID:25103555

  10. Ivory Harvesting Pressure on the Genome of the African Elephant: A Phenotypic Shift to Tusklessness.

    PubMed

    Raubenheimer, Erich J; Miniggio, Hilde D

    2016-09-01

    The unique chequered pattern of elephant ivory has made it a desired commodity for the production of various works of art. The demand however outstrips the supply and with soaring prices, illegal tusk harvesting is thriving on the African continent. Formal restrictions placed on trade in elephant products have been ineffective in reversing the rapid decline in elephant numbers. We are presently facing the reality of extinction of free roaming elephant on the African continent. This paper describes the histogenesis of the chequered pattern, the genomic impact of ivory harvesting on the phenotype of breeding herds, and the contribution of science to tracing the origin of illegal ivory. PMID:26920555

  11. Glassy Objects (Microtektites?) from Deep-Sea Sediments near the Ivory Coast.

    PubMed

    Glass, B P

    1968-08-30

    Glassy objects of spherical, oval, dumbbell, teardrop, and irregular shapes have been found in a deep-sea sediment core taken off the Ivory Coast. They occur in a layer of sediment that was apparently deposited about 800,000 years ago. Their geographic location, appearance, and physical properties suggest that they are microtektites and that they are related to the tektite-strewn field of the Ivory Coast. PMID:17812117

  12. Annual Movement Patterns of Endangered Ivory Gulls: The Importance of Sea Ice

    PubMed Central

    Spencer, Nora C.; Gilchrist, H. Grant; Mallory, Mark L.

    2014-01-01

    The ivory gull (Pagophila eburnea) is an endangered seabird that spends its entire year in the Arctic environment. In the past three decades, threats from various sources have contributed to a >70% decline in Canada. To assess the annual habitat needs of this species, we attached satellite transmitters to 12 ivory gulls on Seymour Island, Nunavut in 2010, which provided up to four breeding seasons of tracking data. Analysis of migratory behaviour revealed considerable individual variation of post-breeding migratory route selection. Ivory gulls traveled a median of 74 days during post-breeding migration, but only 18 days during pre-breeding migration. In contrast to predictions, ivory gulls did not use the Greenland coast during migratory periods. Ivory gulls overwintered near the ice edge in Davis Strait, but also used the Labrador Sea in late February and March. We suggest that the timing of formation and recession and extent of sea ice plays a large role in ivory gull distribution and migratory timing. PMID:25551556

  13. The diffraction grating in the Ivory optomechanical modeling tools

    NASA Astrophysics Data System (ADS)

    Hatheway, Alson E.

    2013-09-01

    In imaging spectrometers it is important that both the image of the far-field object and the image of the slit be stable on the detector plane. Lenses and mirrors contribute to the motions of these images but motions of the diffraction grating also have their own influences on these image motions. This paper develops the vector equations for the images (spectra) of the diffraction grating and derives their optomechanical influence coefficients from them. The Ivory Optomechanical Modeling Tools integrates the diffraction grating into the larger optical imaging system and formats the whole system's influence coefficients suitably for both spreadsheet and finite element analysis methods. Their application is illustrated in an example of a spectrometer exposed to both static and dynamic disturbances.

  14. Innovative production system goes in off Ivory Coast

    SciTech Connect

    Childers, M.; Barnes, J. |

    1995-07-17

    The phased field development of the Lion and Panthere fields, offshore the Ivory Coast, includes a small floating production, storage, and offloading (FPSO) tanker with minimal processing capability as an early oil production system (EPS). For the long-term production scheme, the FPSO will be replaced by a converted jack up mobile offshore production system (MOPS) with full process equipment. The development also includes guyed-caisson well platforms, pipeline export for natural gas to fuel an onshore power plant, and a floating storage and offloading (FSO) tanker for oil export. Pipeline export for oil is a future possibility. This array of innovative strategies and techniques seldom has been brought together in a single project. The paper describes the development plan, early oil, jack up MOPS, and transport and installation.

  15. Science education in rural America: Adaptations for the ivory tower

    NASA Astrophysics Data System (ADS)

    van Doren, Gregory S.

    This thesis illustrated what can happen when academic culture disconnects from the cultures surrounding it. It showed that formal school environments are not always the best places to learn. A discussion of the debate between coherence and fragmentation learning theories illustrated academic chasms and a mindset that science education must originate from within ivory towers to be valued. Rationales for place-based science education were developed. Two National Science Foundation initiatives were compared and contrasted for relevance to Native Science education (a) Informal Science Education and (b) Science Education for New Civic Engagement and Responsibilities. A National Science Foundation instrument, known as the Self-Assessment of Learning Gains, was selected to field-test measures of learning science outside of university science courses. Principles of chemistry were taught in community workshops, and those participant self-assessments were compared to self-assessments of students in introductory chemistry courses at two universities. University students consistently claimed the greatest learning gains, in the post-course survey, for the same areas that they claimed to have the greatest understanding, in the pre-course survey. The workshop participant responses differed, depending upon location of the learning environment. When held in a university laboratory, ideas were not related to other cultures, even when a Native Elder was present to describe those relationships. When held in a cultural center, those relationships were among the highest learning gains claimed. One of the instrument's greatest assets was the ability to measure reactions, level 4 of Bennett's (1976) hierarchy of evidence for program evaluation. A long-term commitment to informal science education (not short-term exhibits or programs), combined with negotiated place-based education was recommended as a crucially needed initiative, if relationships between universities and Native American

  16. Ivory Coast-Ghana margin: model of a transform margin

    SciTech Connect

    Mascle, J.; Blarez, E.

    1987-05-01

    The authors present a marine study of the eastern Ivory Coast-Ghana continental margins which they consider one of the most spectacular extinct transform margins. This margin has been created during Early-Lower Cretaceous time and has not been submitted to any major geodynamic reactivation since its fabric. Based on this example, they propose to consider during the evolution of the transform margin four main and successive stages. Shearing contact is first active between two probably thick continental crusts and then between progressively thinning continental crusts. This leads to the creation of specific geological structures such as pull-apart graben, elongated fault lineaments, major fault scarps, shear folds, and marginal ridges. After the final continental breakup, a hot center (the mid-oceanic ridge axis) is progressively drifting along the newly created margin. The contact between two lithospheres of different nature should necessarily induce, by thermal exchanges, vertical crustal readjustments. Finally, the transform margin remains directly adjacent to a hot but cooling oceanic lithosphere; its subsidence behavior should then progressively be comparable to the thermal subsidence of classic rifted margins.

  17. Energy assessment of Ivory Coast, Morocco, Nigeria, and Senegal

    SciTech Connect

    Ghirardi, A.; Sathaye, J.; Goering, P.

    1986-11-01

    This report is an overview of the energy market in four West African countries: The Ivory Coast, Morocco, Nigeria, and Senegal. We feel these countries are representative of the West African region. Together they account for 75% of the total energy use in West Africa, 78% of GDP, and 76% of population. The purpose of the study is to analyze the evolution of energy demand in the context of the general socio-economic background of the region. The study also examines energy supply and trade related to the energy sector. The analysis focuses on the study of commercial fuels. Although we have reviewed studies of wood, solar, wind, and agricultural residues, we leave out detailed discussions of these non-commercial energy forms. The first part of the report is an assessment of the trends in energy demand in the four study countries. We discuss the main factors driving energy demand sector by sector. This is followed by a review of the primary energy resources of the countries, and of the capacity for production of secondary fuels. The last section looks at energy trade, with particular emphasis on the role of the United States.

  18. On the occurrence of gold mineralizations in southeastern Ivory Coast

    NASA Astrophysics Data System (ADS)

    Kadio, E.; Coulibaly, Y.; Allialy, M. E.; Kouamelan, A. N.; Pothin, K. B. K.

    2010-07-01

    Gold mineralizations are known to occur in the Paleoproterozoic (Birimian) formations of the Aboisso area, southeastern Ivory Coast. These formations, which have been structured during the Eburnean orogeny, mainly consist of volcanic, volcaniclastic and sedimentary rocks intruded by granitic, basic and ultrabasic plutons. Exploration of these terranes has revealed numerous gold mineralizations, the most significant of which are located in the Aféma shear zone. Four distinct types of mineralizations can be distinguished based on the typology of the host rocks. These include mineralizations enclosed in highly silicified volcanic rocks (type 1), mineralizations closely related to intense silicification of metasedimentary rocks (type 2), mineralizations associated with silicified polygenic conglomerates (type 3), and mineralizations encountered in brecciated and silicified zones within a metadiorite sill (type 4). Gold is observed either as free gold, or in association with pyrite, arsenopyrite, sphalerite, chalcopyrite, ±pyrrhotite, ±galena, ±anatase, ±monazite, ±magnetite. Gold and the various sulfides are mostly of hydrothermal epigenetic origin. The fact that the gold mineralizations occurs in brecciated and silicified zones around granitoid intrusions clearly indicates that post-magmatic hydrothermal activity and tectonics exerted a major control during the mineralization process.

  19. [Traditional health practitioners and epilepsies in Ivory Coast].

    PubMed

    François, A A; Elisée, B K; Christian, T A; Armel, K H; Any, G; Tchwa, A M; Constance, Y A

    2014-01-01

    We report the results of a descriptive 3-month observational study concerning the experience and knowledge about epilepsy of 30 traditional health practitioners in the Ivory Coast. Most respondents were men over 30 years of age. They had an average of 14.3 years of professional experience. More than half of respondents (54%) had not attended school. All traditional practitioners knew that epilepsy was a brain disease. For 83.3% of them, the disease was supernatural, due to a curse. These traditional healers knew all the clinical manifestations of generalized tonico-clonic seizure. For over 72% of them, noise, presence of a public, nervousness and coffee consumption were factors favoring seizures. Sixty percent of the traditional healers still believed in the contagiousness of epilepsy, and all claimed to cure it by traditional treatment. Most all healers (97%) used plant products, but only 10% released the name of the plants used (Rubiaceae or Lamiaceae families). This survey highlights the urgency of awareness campaigns and the need for training of Ivorian traditional healers and the necessity to improve the collaboration between modern and traditional medicine. PMID:25193012

  20. [Obstetrical activity of a regional hospital center in the northern Ivory Coast].

    PubMed

    Ribault, L

    1989-05-01

    Rupture of the uterus remains, in some countries, a frequent occurrence. This report of the obstetrical activity of a Regional Hospital Center in the Ivory Coast, demonstrates all the difficulties of a disconcerting pathology for visiting physicians, not used to this type of accident in Europe. PMID:2544976

  1. Lassa virus isolates from Mali and the Ivory Coast represent an emerging fifth lineage

    PubMed Central

    Manning, John T.; Forrester, Naomi; Paessler, Slobodan

    2015-01-01

    Previous imported cases of Lassa fever (LF) into the United Kingdom from the Ivory Coast and Mali, as well as the detection of Lassa virus (LASV) among the Mastomys natalensis population within Mali has led to the suggestion that the endemic area for LF is expanding. Initial phylogenetic analyses arrange isolates from Mali and the Ivory Coast separately from the classical lineage IV isolates taken from Sierra Leone, Guinea, and Liberia. The availability of full genome sequences continues to increase, allowing for a more complete phylogenetic comparison of the isolates from Mali and the Ivory Coast to the other existing isolates. In this study, we utilized a Bayesian approach to infer the demographic histories of each LASV isolate for which the full sequence was available. Our results indicate that the isolates from Mali and the Ivory Coast group separately from the isolates of lineage IV, comprising a distinct fifth lineage. The split between lineages IV and V is estimated to have occurred around 200–300 years ago, which coincides with the colonial period of West Africa. PMID:26483768

  2. Asians in the Ivory Tower: Dilemmas of Racial Inequality in American Higher Education. Multicultural Education Series

    ERIC Educational Resources Information Center

    Teranishi, Robert T.

    2010-01-01

    Highly respected scholar Robert Teranishi draws on his vast research to present this timely and compelling examination of the experience of Asian Americans in higher education. "Asians in the Ivory Tower" explores why and how Asian Americans and Pacific Islanders (AAPIs) are important to our nation's higher education priorities and places the…

  3. Nurturing and Validating Indigenous Epistemologies in Higher Education: Comment on "Domestication of the Ivory Tower."

    ERIC Educational Resources Information Center

    Romero, Mary Eunice

    2002-01-01

    Responds to a paper that focused on the "domestication of the ivory tower" and that highlighted indigenous, field-based education associated with higher education institutions in Alaska. Shares two stories that illustrate what indigenous students often encounter in higher education, places of learning that frequently devalue or ignore their world…

  4. Dating ivory by determination of 14C, 90Sr and 228/232Th.

    PubMed

    Schmied, Stefanie A K; Brunnermeier, Matthias J; Schupfner, Robert; Wolfbeis, Otto S

    2012-09-10

    A method is described to determine the time of death of elephants. This is accomplished by analysis of the radionuclides 14C, 90Sr and 228/232Th in known samples of ivory, and in samples of unknown age. The reliability of this method is considerably increased by multi nuclide analysis. PMID:22717552

  5. Combating the illegal trade in African elephant ivory with DNA forensics.

    PubMed

    Wasser, Samuel K; Joseph Clark, William; Drori, Ofir; Stephen Kisamo, Emily; Mailand, Celia; Mutayoba, Benezeth; Stephens, Matthew

    2008-08-01

    International wildlife crime is burgeoning in this climate of global trade. We contend that the most effective way to contain this illegal trade is to determine where the wildlife is being removed. This allows authorities to direct law enforcement to poaching hot spots, potentially stops trade before the wildlife is actually killed, prevents countries from denying their poaching problems at home, and thwarts trade before it enters into an increasingly complex web of international criminal activity. Forensic tools have been limited in their ability to determine product origin because the information they can provide typically begins only at the point of shipment. DNA assignment analyses can determine product origin, but its use has been limited by the inability to assign samples to locations where reference samples do not exist. We applied new DNA assignment methods that can determine the geographic origin(s) of wildlife products from anywhere within its range. We used these methods to examine the geographic origin(s) of 2 strings of seizures involving large volumes of elephant ivory, 1 string seized in Singapore and Malawi and the other in Hong Kong and Cameroon. These ivory traffickers may comprise 2 of the largest poaching rings in Africa. In both cases all ivory seized in the string had common origins, which indicates that crime syndicates are targeting specific populations for intense exploitation. This result contradicts the dominant belief that dealers are using a decentralized plan of procuring ivory stocks as they became available across Africa. Large quantities of ivory were then moved, in multiple shipments, through an intermediate country prior to shipment to Asia, as a risk-reduction strategy that distances the dealer from the poaching locale. These smuggling strategies could not have been detected by forensic information, which typically begins only at the shipping source. PMID:18786100

  6. [History of an epidemiological route between Ivory Coast and Burkina Faso: the case of the Koudougou sleeping sickness foci].

    PubMed

    Kiendrébéogo, D; Kambiré, R; Jamonneau, V; Lingué, K; Solano, P; Courtin, F

    2012-11-01

    In the first half of the XXth century, while Upper-Volta (now Burkina Faso) was suffering a terrible epidemic of sleeping sickness, the French colonial administration encouraged the movement of people from Upper-Volta to Ivory Coast to meet their demands for labour. This led to the establishment of Mossi villages, such as those of Koudougou, in the Ivorian forest with populations originating from areas of Upper-Volta that were not only densely populated but also severely affected by sleeping sickness. Since 2000, most cases of sleeping sickness in the Koudougou district of Burkina Faso have been in people originally from Ivory Coast. Who are they? Where did they settle in Burkina Faso? Where do they come from in Ivory Coast? After having retraced the epidemiological history of Koudougou villages in Burkina Faso and Ivory Coast, the history of ten cases of sleeping sickness detected passively at Koudougou hospital since 2000 were analysed. All cases originated from the forest area of Ivory Coast. Understanding the spread of sleeping sickness between Burkina Faso and Ivory Coast will assist in the identification of areas of disease risk. PMID:23193525

  7. Genetic population study of Y-chromosome markers in Benin and Ivory Coast ethnic groups.

    PubMed

    Fortes-Lima, Cesar; Brucato, Nicolas; Croze, Myriam; Bellis, Gil; Schiavinato, Stephanie; Massougbodji, Achille; Migot-Nabias, Florence; Dugoujon, Jean-Michel

    2015-11-01

    Ninety-six single nucleotide polymorphisms (SNPs) and seventeen short tandem repeat (STRs) were investigated on the Y-chromosome of 288 unrelated healthy individuals from populations in Benin (Bariba, Yoruba, and Fon) and the Ivory Coast (Ahizi and Yacouba). We performed a multidimensional scaling analysis based on FST and RST genetic distances using a large extensive database of sub-Saharan African populations. There is more genetic homogeneity in Ivory Coast populations compared with populations from Benin. Notably, the Beninese Yoruba are significantly differentiated from neighbouring groups, but also from the Yoruba from Nigeria (FST>0.05; P<0.01). The Y-chromosome dataset presented here provides new valuable data to understand the complex genetic diversity and human male demographic events in West Africa. PMID:26275614

  8. Osmium isotopes in Ivory Coast tektites: Confirmation of a meteoritic component and rhenium depletion

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Shirey, Steven B.

    1993-03-01

    The sensitive negative thermal ionization mass spectrometry method was used for the measurement of concentrations and isotopic ratios of osmium and rhenium in four Ivory Coast tektites. These tektites have crustal major and trace element composition, as well as large negative epsilonNd(-20) and positive epsilonSr(+260 to +300) which are characteristic for old continental crust. Os concentrations ranging from 0.09 to 0.30 ppb were found, clearly much higher than average crustal values, Os-187/Os-186 ratios of about 1.2-1.7, and low Re-187/Os-186 ratios. These results show unambiguously the existence of a meteoritic component (on the order of 0.06%) in the Ivory Coast tektites. Low Re abundances are the result of fractionation of Re during the impact.

  9. Osmium isotopes in Ivory Coast tektites: Confirmation of a meteoritic component and rhenium depletion

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Shirey, Steven B.

    1993-01-01

    The sensitive negative thermal ionization mass spectrometry method was used for the measurement of concentrations and isotopic ratios of osmium and rhenium in four Ivory Coast tektites. These tektites have crustal major and trace element composition, as well as large negative epsilon(sub Nd)(-20) and positive epsilon(sub Sr)(+260 to +300) which are characteristic for old continental crust. Os concentrations ranging from 0.09 to 0.30 ppb were found, clearly much higher than average crustal values, Os-187/Os-186 ratios of about 1.2-1.7, and low Re-187/Os-186 ratios. These results show unambiguously the existence of a meteoritic component (on the order of 0.06%) in the Ivory Coast tektites. Low Re abundances are the result of fractionation of Re during the impact.

  10. Heat induced transformation of fossil mastodon ivory into turquoise 'odontolite'. Structural and elemental characterisation

    NASA Astrophysics Data System (ADS)

    Reiche, I.; Vignaud, C.; Menu, M.

    2000-10-01

    The present work deals with the structural and elemental analysis of turquoise mineral imitations as 'odontolite' or bone turquoise by transmission electron microscopy (TEM), scanning electron microscopy (SEM-EDX) and particle induced X-ray and γ-ray emission (PIXE-PIGE). The aim of the work is to evidence the former deliberate transformation of fossilised ivory by man in order to transform them into semi-precious stones. We show that the crystal structure of 'odontolite' artefacts consisting of fluorapatite (Ca 5(PO 4) 3F) corresponds to that of heated fossil mastodon ivory (12-15 million years old). Metallic traces detected by PIXE-PIGE in these 'odontolites' are discussed in order to explain their role for coloration. Other more greenish turquoise imitations have a bone-like structure and composition, and carbonate-hydroxylapatite. The presence of copper salts at the surface is responsible for their green coloration.

  11. Rapidly increasing methyl mercury in endangered ivory gull (Pagophila eburnea) feathers over a 130 year record

    PubMed Central

    Bond, Alexander L.; Hobson, Keith A.; Branfireun, Brian A.

    2015-01-01

    Mercury (Hg) is increasing in marine food webs, especially at high latitudes. The bioaccumulation and biomagnification of methyl mercury (MeHg) has serious effects on wildlife, and is most evident in apex predators. The MeHg body burden in birds is the balance of ingestion and excretion, and MeHg in feathers is an effective indicator of overall MeHg burden. Ivory gulls (Pagophila eburnea), which consume ice-associated prey and scavenge marine mammal carcasses, have the highest egg Hg concentrations of any Arctic bird, and the species has declined by more than 80% since the 1980s in Canada. We used feathers from museum specimens from the Canadian Arctic and western Greenland to assess whether exposure to MeHg by ivory gulls increased from 1877 to 2007. Based on constant feather stable-isotope (δ13C, δ15N) values, there was no significant change in ivory gulls' diet over this period, but feather MeHg concentrations increased 45× (from 0.09 to 4.11 µg g−1 in adults). This dramatic change in the absence of a dietary shift is clear evidence of the impact of anthropogenic Hg on this high-latitude threatened species. Bioavailable Hg is expected to increase in the Arctic, raising concern for continued population declines in high-latitude species that are far from sources of environmental contaminants. PMID:25788594

  12. Genotoxicity testing with the somatic white-ivory system in the eye of Drosophila melanogaster.

    PubMed

    Würgler, F E; Kägi, A

    1991-05-01

    The white-ivory test in Drosophila melanogaster is designed to detect chemically induced reversions of the sex-linked, recessive unstable eye-color mutation white-ivory to the wild-type form. After exposure of larvae reversions are detectable as clones of red facets in the eye of newly enclosed adult flies. Tester strains containing a quadruplication of the white-ivory gene on the X-chromosome(s) were used. In a strain with males carrying 4 copies of the gene and females carrying 8 copies of the gene, spontaneous reversions occurred proportional to the gene copy number. In contrast to this, chemically induced reversions occurred only 1.36 times more frequently in females (carrying 8 copies of the gene) than in males (carrying 4 copies). Since chemicals inducing different lesions in DNA (bleomycin, cyclophosphamide, daunomycin, diethyl sulfate and 7,12-dimethylbenz[a]anthracene) did induce statistically significant frequencies of reversions the test appears to be capable of detecting a wide variety of genotoxic chemicals with different modes of action. The recombinogen strychnine did not induce reversions. PMID:1903508

  13. A Sustainable Substitute for Ivory: the Jarina Seed from the Amazon

    PubMed Central

    Chu, Yinghao; Meyers A, Marc A.; Wang, Bin; Yang, Wen; Jung, Jae-Young; Coimbra, Carlos F. M.

    2015-01-01

    The dried endosperm of the seed of Phytelephas sp is widely used for artisanal work in the Amazon region due to its favorable mechanical properties and pleasant appearance that resemble elephant ivory. While the seeds have enjoyed popularity and limited use by selected industries (e.g., military uniform buttons and piano keys) and handicraft applications, little is known about the mechanical properties and structure of this sustainable material. This work is the first to characterize the dried Jarina endosperm and to investigate its functionality as a viable substitute for elephant ivory. Structural analysis of typical seeds reveals the prevalence of tubules that align in rings and radiate from the (usually hollow) core of the seed. This seed, in the absence of a reinforcement structure or mineral phase, possesses mechanical properties slightly inferior to elephant ivory and selected plastics, while retaining the visual appeal of a naturally occurring material. A synthetic structure inspired on the seed is created and suggestions for further development are discussed. PMID:26399626

  14. Wage rentals for reproducible human capital: evidence from Ghana and the Ivory Coast.

    PubMed

    Paul Schultz, T

    2003-12-01

    Education, child nutrition, adult health/nutrition, and labor mobility are critical factors in achieving recent sustained growth in factor productivity. To compare the contribution of these four human capital inputs, an expanded specification of the wage function is estimated from household (LSMS) surveys of the Ivory Coast and Ghana. Specification tests assess whether the human capital inputs are exogenous, and instrumental variable techniques are used to estimate the wage function. Smaller panels from the Ivory Coast imply the magnitude of measurement error in the human capital inputs and provide more efficient instruments to estimate the wage equation. The conclusion emerges that weight-for-height and height are endogenous, particularly prone to measurement error, and heterogeneous in their effects on wages. Overall returns to these four forms of human capital are similar within each country for men and women, but education and migration returns are higher in the more rapidly growing Ivory Coast, and the wage effects of child nutrition proxied by height are greater in poorer, more malnourished Ghana. PMID:15463983

  15. A Sustainable Substitute for Ivory: the Jarina Seed from the Amazon

    NASA Astrophysics Data System (ADS)

    Chu, Yinghao; Meyers A, Marc A.; Wang, Bin; Yang, Wen; Jung, Jae-Young; Coimbra, Carlos F. M.

    2015-09-01

    The dried endosperm of the seed of Phytelephas sp is widely used for artisanal work in the Amazon region due to its favorable mechanical properties and pleasant appearance that resemble elephant ivory. While the seeds have enjoyed popularity and limited use by selected industries (e.g., military uniform buttons and piano keys) and handicraft applications, little is known about the mechanical properties and structure of this sustainable material. This work is the first to characterize the dried Jarina endosperm and to investigate its functionality as a viable substitute for elephant ivory. Structural analysis of typical seeds reveals the prevalence of tubules that align in rings and radiate from the (usually hollow) core of the seed. This seed, in the absence of a reinforcement structure or mineral phase, possesses mechanical properties slightly inferior to elephant ivory and selected plastics, while retaining the visual appeal of a naturally occurring material. A synthetic structure inspired on the seed is created and suggestions for further development are discussed.

  16. A Sustainable Substitute for Ivory: the Jarina Seed from the Amazon.

    PubMed

    Chu, Yinghao; Meyers, A Marc A; Wang, Bin; Yang, Wen; Jung, Jae-Young; Coimbra, Carlos F M

    2015-01-01

    The dried endosperm of the seed of Phytelephas sp is widely used for artisanal work in the Amazon region due to its favorable mechanical properties and pleasant appearance that resemble elephant ivory. While the seeds have enjoyed popularity and limited use by selected industries (e.g., military uniform buttons and piano keys) and handicraft applications, little is known about the mechanical properties and structure of this sustainable material. This work is the first to characterize the dried Jarina endosperm and to investigate its functionality as a viable substitute for elephant ivory. Structural analysis of typical seeds reveals the prevalence of tubules that align in rings and radiate from the (usually hollow) core of the seed. This seed, in the absence of a reinforcement structure or mineral phase, possesses mechanical properties slightly inferior to elephant ivory and selected plastics, while retaining the visual appeal of a naturally occurring material. A synthetic structure inspired on the seed is created and suggestions for further development are discussed. PMID:26399626

  17. Rapidly increasing methyl mercury in endangered ivory gull (Pagophila eburnea) feathers over a 130 year record.

    PubMed

    Bond, Alexander L; Hobson, Keith A; Branfireun, Brian A

    2015-04-22

    Mercury (Hg) is increasing in marine food webs, especially at high latitudes. The bioaccumulation and biomagnification of methyl mercury (MeHg) has serious effects on wildlife, and is most evident in apex predators. The MeHg body burden in birds is the balance of ingestion and excretion, and MeHg in feathers is an effective indicator of overall MeHg burden. Ivory gulls (Pagophila eburnea), which consume ice-associated prey and scavenge marine mammal carcasses, have the highest egg Hg concentrations of any Arctic bird, and the species has declined by more than 80% since the 1980s in Canada. We used feathers from museum specimens from the Canadian Arctic and western Greenland to assess whether exposure to MeHg by ivory gulls increased from 1877 to 2007. Based on constant feather stable-isotope (δ(13)C, δ(15)N) values, there was no significant change in ivory gulls' diet over this period, but feather MeHg concentrations increased 45× (from 0.09 to 4.11 µg g(-1) in adults). This dramatic change in the absence of a dietary shift is clear evidence of the impact of anthropogenic Hg on this high-latitude threatened species. Bioavailable Hg is expected to increase in the Arctic, raising concern for continued population declines in high-latitude species that are far from sources of environmental contaminants. PMID:25788594

  18. MVC Shell

    SciTech Connect

    Benz, Zachary; McCain, Jonathan; Bauer, Travis

    2008-06-03

    Provides the shell of a plugin based application environment that builds on MVC Framework to allow one to rapidly construct an application by using a collection of plugins. The MVC Shell is implemented in C# as a .NET 2.0 application that can then be used as a shell for building a plugin based application. The infrastructure allows for dynamically processing a specified collection of plugins in order to determine the functionality of the application, where all plugins operate within the context of the underlying MVC Framework environment.

  19. MVC Shell

    Energy Science and Technology Software Center (ESTSC)

    2008-06-03

    Provides the shell of a plugin based application environment that builds on MVC Framework to allow one to rapidly construct an application by using a collection of plugins. The MVC Shell is implemented in C# as a .NET 2.0 application that can then be used as a shell for building a plugin based application. The infrastructure allows for dynamically processing a specified collection of plugins in order to determine the functionality of the application, wheremore » all plugins operate within the context of the underlying MVC Framework environment.« less

  20. Levels and trends of organochlorines and brominated flame retardants in ivory gull eggs from the Canadian Arctic, 1976 to 2004.

    PubMed

    Braune, Birgit M; Mallory, Mark L; Grant Gilchrist, H; Letcher, Robert J; Drouillard, Ken G

    2007-06-01

    The ivory gull (Pagophila eburnea) is a circumpolar marine bird which has recently been listed as an endangered species in Canada. To determine whether contaminants may be playing a role in the population decline of this species, ivory gull eggs collected in 1976, 1987 and 2004 from Seymour Island in the Canadian Arctic were analyzed for organochlorines, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and non-ortho PCBs. This study also provides the first account of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs) and polybrominated biphenyls (PBBs) in ivory gulls. The most quantitatively abundant legacy organochlorines found in the ivory gull eggs were p,p'-DDE, SigmaPCB and oxychlordane. Concentrations of the organochlorines analyzed either decreased or showed little change between 1976 and 2004. Concentrations of SigmaPCDD in ivory gull eggs were greater than SigmaPCDF, and the non-ortho PCBs (primarily PCB-126) contributed the largest fraction to the total TEQ value in all years sampled. Concentrations of PCDDs, PCDFs and SigmaTEQ decreased from 1976 to 2004. In contrast, concentrations of the PBDEs steadily increased between 1976 and 2004 driven primarily by increases in BDE-47. Although concentrations of the persistent chlorinated compounds (i.e. organochlorine pesticides, PCBs, PCDDs, PCDFs) reported in this study were below published toxicological threshold values for eggs of wild birds, we cannot rule out the possibility of synergistic/additive, sublethal effects. Very few studies have been carried out to evaluate the exposure-effect relationship of the persistent brominated compounds in avian species. Given the scarcity of information on toxicity threshold levels for PBBs and PBDEs in avian species, coupled with the trend toward increasing concentrations in ivory gulls, continued monitoring and further toxicological studies of these compounds are warranted. PMID:17412396

  1. CONSERVATION. Genetic assignment of large seizures of elephant ivory reveals Africa's major poaching hotspots.

    PubMed

    Wasser, S K; Brown, L; Mailand, C; Mondol, S; Clark, W; Laurie, C; Weir, B S

    2015-07-01

    Poaching of elephants is now occurring at rates that threaten African populations with extinction. Identifying the number and location of Africa's major poaching hotspots may assist efforts to end poaching and facilitate recovery of elephant populations. We genetically assign origin to 28 large ivory seizures (≥0.5 metric tons) made between 1996 and 2014, also testing assignment accuracy. Results suggest that the major poaching hotspots in Africa may be currently concentrated in as few as two areas. Increasing law enforcement in these two hotspots could help curtail future elephant losses across Africa and disrupt this organized transnational crime. PMID:26089357

  2. Shelled opisthobranchs.

    PubMed

    Mikkelsen, Paula M

    2002-01-01

    In his contributions to the monographic series "Manual of Conchology", Henry Pilsbry reviewed the subgroup Tectibranchiata, comprising those opisthobranch snails that (at least primitively) still possess a shell (Pilsbry, 1894-1896). Exemplified by the Cephalaspidea (bubble shells), others included in this group at Pilsbry's time and since were Anaspidea (sea hares) and the shelled members of Notaspidea (side-gilled slugs) and Sacoglossa (leaf slugs). Pilsbry (and others since his time) considered tectibranchs to be the "root stock" from which more advanced gastropods such as Nudibranchia and Pulmonata were derived. Tectibranch systematics is firmly based on conchology and most species were originally described from empty shells. However, soft-anatomical characters were acknowledged quite early on as equally important in tectibranchs, due to the reduction of their shells and their evolutionary proximity to unshelled gastropods. Today, Tectibranchiata is not recognized as a natural taxon although the word "tectibranch" (like "prosobranch" and "mesogastropod") continues in vernacular use. Shelled opisthobranchs have been redistributed among various taxa, including several new ones--the unresolved basal opisthobranchs (Architectibranchia) and the "lower Heterobranchia", an enigmatic and currently much-studied group of families considered basal to all of Euthyneura (Opisthobranchia and landsnails (Pulmonata)). Despite their polyphyletic status, shelled opisthobranchs remain important subjects in evolutionary studies of gastropods--as the most basal members of nearly every opisthobranch clade and as organisms with mosaic combinations of primitive and derived features within evolutionary "trends" (e.g., loss of the shell, detorsion, concentration of the nervous system, ecological specialization, etc.). Although they play a pivotal role, the shelled opisthobranchs have received minimal attention in more comprehensive gastropod studies, often relegated to token

  3. Assigning African elephant DNA to geographic region of origin: Applications to the ivory trade

    PubMed Central

    Wasser, Samuel K.; Shedlock, Andrew M.; Comstock, Kenine; Ostrander, Elaine A.; Mutayoba, Benezeth; Stephens, Matthew

    2004-01-01

    Resurgence of illicit trade in African elephant ivory is placing the elephant at renewed risk. Regulation of this trade could be vastly improved by the ability to verify the geographic origin of tusks. We address this need by developing a combined genetic and statistical method to determine the origin of poached ivory. Our statistical approach exploits a smoothing method to estimate geographic-specific allele frequencies over the entire African elephants' range for 16 microsatellite loci, using 315 tissue and 84 scat samples from forest (Loxodonta africana cyclotis) and savannah (Loxodonta africana africana) elephants at 28 locations. These geographic-specific allele frequency estimates are used to infer the geographic origin of DNA samples, such as could be obtained from tusks of unknown origin. We demonstrate that our method alleviates several problems associated with standard assignment methods in this context, and the absolute accuracy of our method is high. Continent-wide, 50% of samples were located within 500 km, and 80% within 932 km of their actual place of origin. Accuracy varied by region (median accuracies: West Africa, 135 km; Central Savannah, 286 km; Central Forest, 411 km; South, 535 km; and East, 697 km). In some cases, allele frequencies vary considerably over small geographic regions, making much finer discriminations possible and suggesting that resolution could be further improved by collection of samples from locations not represented in our study. PMID:15459317

  4. Oryctes monoceros trapping with synthetic pheromone and palm material in Ivory Coast.

    PubMed

    Allou, Kouassi; Morin, Jean-Paul; Kouassi, Philippe; N'klo, François Hala; Rochat, Didier

    2006-08-01

    Oryctes monoceros is the most serious pest in coconut plantations, causing up to 40% damage in tropical Africa, especially in Ivory Coast. With a view to reducing pest populations by olfactory trapping, field trials were carried out to assess the efficiency of a synthetic aggregation pheromone: ethyl 4-methyloctanoate (1), 4-methyloctanoic acid (2), a related volatile produced by males, and decaying palm material, either oil palm empty fruit bunches (EFB) or pieces of coconut wood (CW) of various ages. Vertical polyvinyl chloride tube traps (2 x 0.16 m with two openings in the upper half), embedded in the soil, were more efficient than 30-L pail traps 1.5 m above ground. EFB, which were inactive alone, synergized captures with synthetic pheromone. CW was more effective than EFB in comparative trials. Compound 2 did not catch any beetles when assessed with EFB, and reduced catches by 1 + EFB when tested at >10% with the pheromone. Trapping over 6 mo in 2002 and 2003 in a 19-ha coconut plot inside a 4,000-ha oil palm estate reduced damage from 3.8% in 2001 to 0.5% in 2002, then to 0.2% in 2003. Damage was 0.0% in 2004 with routine trapping using 32 traps, which caught 3369 beetles in 9 mo. The results are discussed in relation to other Dynastid palm pests and coconut protection in Ivory Coast. PMID:16900429

  5. Evolution of a Paleoproterozoic “weak type” orogeny in the West African Craton (Ivory Coast)

    NASA Astrophysics Data System (ADS)

    Vidal, M.; Gumiaux, C.; Cagnard, F.; Pouclet, A.; Ouattara, G.; Pichon, M.

    2009-11-01

    The Paleoproterozoic domain of the Ivory Coast lies in the central part of the West African Craton (WAC) and is mainly constituted by TTG, greenstones, supracrustal rocks and leucogranites. A compilation of metamorphic and radiometric data highlights that: i) metamorphic conditions are rather homogeneous through the domain, without important metamorphic jumps, ii) HP-LT assemblages are absent and iii) important volumes of magmas emplaced during the overall Paleoproterozoic orogeny suggesting the occurrence of long-lived rather hot geotherms. Results of the structural analysis, focused on three areas within the Ivory Coast, suggest that the deformation is homogeneous and distributed through the Paleoproterozoic domain. In details, results of this study point out the long-lived character of vertical movements during the Eburnean orogeny with a two folds evolution. The first stage is characterized by the development of "domes and basins" geometries without any boundary tectonic forces and the second stage is marked by coeval diapiric movements and horizontal regional-scale shortening. These features suggest that the crust is affected by vertical movements during the overall orogeny. The Eburnean orogen can then be considered as an example of long-lived Paleoproterozoic "weak type" orogen.

  6. Serological survey of canine leptospirosis in three countries of tropical Africa: Sudan, Gabon and Ivory Coast.

    PubMed

    Roqueplo, Cédric; Marié, Jean-Lou; André-Fontaine, Geneviève; Kodjo, Angeli; Davoust, Bernard

    2015-02-01

    A cross-sectional survey was conducted to estimate the presence of leptospiral antibodies among 475 dogs from three countries of tropical Africa: Sudan (n=62), Gabon (n=255) and Ivory Coast (n=158). Sixteen reference strains belonging to seven serogroups were used as antigen in the microscopic agglutination test. Overall, considering titres ≥1:40, 453 samples were positive towards one or several serovars of pathogenic leptospires. Focusing on high titres, i.e. ≥1:320, the seroprevalence was 40.8%. In Gabon, the seroprevalence was higher in rural areas than in an urban environment (p<0.001). In Ivory Coast, the seroprevalence for serogroups Icterohaemorrhagiae and Canicola was not statistically different according to the vaccinal status. Predominant serogroups varied according to the countries but Grippotyphosa and Sejroë were the most common, while Icterohaemorragiae and Canicola were dominant in Sudan. In these three countries, dogs are heavily exposed to pathogenic Leptospira and humans living in the same environment are also at risk of infection. PMID:25467033

  7. The Case of the Ivory-Billed Woodpecker: The Scientific Process and How It Relates to Everyday Life

    ERIC Educational Resources Information Center

    Stanger-Hall, Kathrin; Merriam, Jennifer; Greuling, Ruth Ann

    2007-01-01

    In this case study, based on the reported rediscovery of the Ivory-billed Woodpecker in April 2005, students examine a real-world example of the scientific process and explore the practical implications of their conclusions. The case tells the story of Brad Murky, a student and research assistant who must decide whether the available evidence is…

  8. [Schilbetrematoides manizani n. sp. (Dactylogyridea) monogenean parasite of Schilbe mandibularis (Günther, 1867) (Schilbeidae) in the Ivory Coast].

    PubMed

    N'Douba, V; Lambert, A; Pariselle, A; Euzet, L

    2000-06-01

    The authors describe a new species in the genus Schilbetrematoides Kritsky & Kulo, 1992 from the gills of Schilbe mandibularis (Günther, 1867) (Schilbeidae) caught in the rivers Bia and Agneby in Ivory Coast. S. manizani n. sp. differs from S. pseudodactylogyrus Kritsky & Kulo, 1992, a parasite of Schilbe intermedius Rüppell, 1832 by having morphologically distinct gripi. PMID:10887660

  9. How Much Ivory Does This Tower Need? What We Spend on, and Get from, Higher Education. Policy Analysis. No. 686

    ERIC Educational Resources Information Center

    McCluskey, Neal

    2011-01-01

    It is commonly asserted, especially by people within higher education, that the American Ivory Tower is strapped for cash and tightfisted taxpayers are to blame. Taxpayer support for postsecondary education has long been in decline, this narrative goes, and has forced schools to continually raise tuition to make up for the losses. Tallying…

  10. Shell Games.

    ERIC Educational Resources Information Center

    Atkinson, Bill

    1982-01-01

    The author critiques the program design and educational aspects of the Shell Games, a program developed by Apple Computer, Inc., which can be used by the teacher to design objective tests for adaptation to specific assessment needs. (For related articles, see EC 142 959-962.) (Author)

  11. Vibration of Shells

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.

    1973-01-01

    The vibrational characteristics and mechanical properties of shell structures are discussed. The subjects presented are: (1) fundamental equations of thin shell theory, (2) characteristics of thin circular cylindrical shells, (3) complicating effects in circular cylindrical shells, (4) noncircular cylindrical shell properties, (5) characteristics of spherical shells, and (6) solution of three-dimensional equations of motion for cylinders.

  12. Building Atoms Shell by Shell.

    ERIC Educational Resources Information Center

    Sussman, Beverly

    1993-01-01

    Describes an atom-building activity where students construct three-dimensional models of atoms using a styrofoam ball as the nucleus and pom-poms, gum drops, minimarshmallows, or other small items of two different colors to represent protons and neutrons attached. Rings of various sizes with pom-poms attached represent electron shells and…

  13. Shell worlds

    NASA Astrophysics Data System (ADS)

    Roy, Kenneth I.; Kennedy, Robert G., III; Fields, David E.

    2013-02-01

    The traditional concept of terraforming assumes ready availability of candidate planets with acceptable qualities: orbiting a star in its "Goldilocks zone", liquid water, enough mass, years longer than days, magnetic field, etc. But even stipulating affordable interstellar travel, we still might never find a good candidate elsewhere. Whatever we found likely would require centuries of heavy terraforming, just as Mars or Venus would here. Our increasing appreciation of the ubiquity of life suggests that any terra nova would already possess it. We would then face the dilemma of introducing alien life forms (us, our microbes) into another living world. Instead, we propose a novel method to create habitable environments for humanity by enclosing airless, sterile, otherwise useless planets, moons, and even large asteroids within engineered shells, which avoids the conundrum. These shells are subject to two opposing internal stresses: compression due to the primary's gravity, and tension from atmospheric pressure contained inside. By careful design, these two cancel each other resulting in zero net shell stress. Beneath the shell an Earth-like environment could be created similar in almost all respects to that of Home, except for gravity, regardless of the distance to the sun or other star. Englobing a small planet, moon, or even a dwarf planet like Ceres, would require astronomical amounts of material (quadrillions of tons) and energy, plus a great deal of time. It would be a quantum leap in difficulty over building Dyson Dots or industrializing our solar system, perhaps comparable to a mission across interstellar space with a living crew within their lifetime. But when accomplished, these constructs would be complete (albeit small) worlds, not merely large habitats. They could be stable across historic timescales, possibly geologic. Each would contain a full, self-sustaining ecology, which might evolve in curious directions over time. This has interesting implications

  14. Allele and haplotype diversity of X-chromosomal STRs in Ivory Coast.

    PubMed

    Pasino, Serena; Caratti, Stefano; Del Pero, Massimiliano; Santovito, Alfredo; Torre, Carlo; Robino, Carlo

    2011-09-01

    Twenty-one X-chromosomal short tandem repeat (STR) loci, including the six clusters of linked markers DXS10148-DXS10135-DXS8378 (Xp22), DXS7132-DXS10079-DXS10074 (Xq12), DXS6801-DXS6809-DXS6789 (Xq21), DXS7424-DXS101 (Xq22), DXS10103-HPRTB-DXS10101 (Xq26), DXS8377-DXS10146-DXS10134-DXS7423 (Xq28) and the loci DXS6800, GATA172D05 and DXS10011 were typed in a population sample from Ivory Coast (n=125; 51 men and 74 women). Allele and haplotype frequencies as well as linkage disequilibrium data for kinship calculations are provided. On the whole, no significant differences in the genetic variability of X-STR markers were observed between Ivorians and other sub-Saharan African populations belonging to the Niger-Kordofanian linguistic group. PMID:21717153

  15. Retrospective Study of a Series of 20 Ivory Prostheses in the Treatment of Trapeziometacarpal Osteoarthritis.

    PubMed

    Spaans, Anne J; van Minnen, L Paul; Weijns, Marieke E; Braakenburg, Assa; van der Molen, Aebele B Mink

    2016-05-01

    Background Many surgical treatment options for osteoarthritis (OA) of the trapeziometacarpal (TMC) joint exist. However, no procedure has been proven superior. Good results have been described for TMC joint replacement. Purpose To analyze the results of the Ivory prosthesis in the treatment of symptomatic TMC OA. Patients and Methods A retrospective single-center follow-up study was performed. Visual analogue scale (VAS) for pain, Disabilities of the Arm, Shoulder and Hand (DASH) score, Michigan Hand Outcomes Questionnaire (MHQ), active range of motion, strength, and radiological outcomes were assessed and analyzed. Differences between the operated and nonoperated hand were analyzed using paired t-tests. Twenty patients were included with a mean follow-up duration of 37.0 months. Results Patients experienced minimal pain with a mean VAS pain score of 1.9. DASH and MHQ scores indicated mild to moderate impairments. Eighty-five percent of patients assessed the operation excellent or good. Significant differences were found in measurements of extension and palmar thumb abduction in favor of the contralateral hand. No significant differences in strength between both hands were found. Two patients had a dislocation of the prosthesis; one patient required open reduction and tightening of the joint capsule. The other dislocation was treated with trapeziectomy and interposition of a fascia lata allograft. One patient had a collapse of the trapezium requiring a revision procedure. Conclusion Ivory prosthesis TMC arthroplasty can achieve good results in patients with symptomatic isolated TMC OA. In this series, however, revision surgery was required in 3 of 20 cases. PMID:27104079

  16. Female genital mutilation and intimate partner violence in the Ivory Coast

    PubMed Central

    2014-01-01

    Background Serious forms of violence against women include Female Genital Mutilation (FGM) and Intimate Partner Violence (IPV). The aim of this study was to determine if FGM is associated with IPV, using data obtained from the Demographic and Health Survey (DHS) 2012 in Ivory Coast. Methods Participants for this study were drawn from the 2011-12 Ivory Coast Demographic and Health Survey (CDHS), a nationally representative sample of 10060 women aged 15 to 49 years. The analysis of this paper is restricted to the sample of women who responded to the FGM and domestic violence modules (N = 5005). Results The lifetime prevalence of physical violence was 24.8%, sexual violence, 5.7%, and emotional violence, 19.0%, and the prevalence of any lifetime IPV was 32.1%. In all, 40.6% reported female genital cutting or mutilation (FGM). Women reporting FGM were two times as likely to experience sexual IPV (AOR: 1.96, CI: 1.29-2.98), while other subtypes of IPV were higher in women reporting FGM but they were not significant. Of the socio-demographic covariates, urban residence and having a primary education were associated with most subtypes of IPV, while being a Muslim seemed protective from any type, sexual and emotional IPV. Having seen the father beating the mother was positively associated with most IPV subtypes, and having been diagnosed with a sexually transmitted infection (STI) in the previous 12 months was associated with physical and sexual IPV. Conclusion Significant rates of FGM and IPV were found among this sample of Ivorian women calling for the need for multiple strategies to reduce FGM and IPV. PMID:24451017

  17. Origins and dispersal of the mitochondrial DNA region V 9 bp deletion and insertion in Nigeria and the Ivory Coast

    SciTech Connect

    Merriwether, D.A.; Huston, S.L.; Bunker, C.A.

    1994-09-01

    An intergenic region V Mitochondrial DNA (mtDNA) 9 bp deletion located between the genes for tRNA{sup LYS} and cytochrome oxidase II was discovered in a small percentage of Nigerian and Ivory Coast natives. Previously this deletion has been described as Asian-specific and has been reported throughout the New World, Asia, S.E. Asia, and the Pacific Islands at frequencies ranging from 0% to 100%. In the New World and the Pacific Islands, the deletion is almost always accompanied by an Hae III restriction site gain at nt 16517. All 9 occurrences of the deletion observed in Africa (from four different populations) co-occur with the Hae III 16517 site gain, indicating that the African deletion probably shares a common origin with the deletion described as {open_quotes}Asian-specific{close_quotes}. The deletion was found in Benin and Sokoto, Nigeria in 2/54 Edo Bini, 1/2 Edo Ishan, 3/99 Hausa, 0/18 Fulani, and 0/16 other Nigerians. The deletion was also detected in 3/115 Ivory Coast natives from Abidjan. A 9 bp insertion (triplication) was observed in 1/115 Ivory Coast natives. The triplicated individual also possessed the Hae III 16517 site gain. The fragment containing the African deletion was sequenced and found to be identical in sequence to the Asian deletion region. D-loop sequence of nts 15975 to 00048 revealed that 2 of the 3 Ivory Coast deleted individuals and 1 of the 6 Nigerians deleted (Hausa) had a T-C transition at nt position 16189 which is common in New World-deleted individuals. These results raise the possibility that the occurrence of this deletion predates the separation of Asian and African populations from a common ancestral populations, or that the deletion has occurred more than once in human evolution. Either explanation requires that caution be exercised when using the 9 bp deletion as a population marker.

  18. Infrasound from lightning measured in Ivory Coast from 2004 to 2014

    NASA Astrophysics Data System (ADS)

    Farges, Thomas; Le Pichon, Alexis; Ceranna, Lars; Diawara, Adama

    2016-04-01

    It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. 80 % of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes …). Some of the IMS stations are located where lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. Assink et al. (2008) and Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within 300 km. One-to-one correlation is possible when the thunderstorm is within about 75 km from the station. When the lightning flash occurs within 20 km, it is also possible to rebuild the 3D geometry of the discharges when the network size is less than 100 m (Arechiga et al., 2011; Gallin, 2014). An IMS infrasound station has been installed in Ivory Coast since 2002. The lightning rate of this region is 10-20 flashes/km²/year from space-based instrument OTD (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 10 years of data (2005-2014). Correlation between infrasound having a mean frequency higher than 1 Hz and lightning flashes detected by the World Wide Lightning Location Network (WWLLN) is systematically looked for. One-to-one correlation is obtained for flashes occurring within about 100 km. An exponential decrease of the

  19. The retrieval of fingerprint friction ridge detail from elephant ivory using reduced-scale magnetic and non-magnetic powdering materials.

    PubMed

    Weston-Ford, Kelly A; Moseley, Mark L; Hall, Lisa J; Marsh, Nicholas P; Morgan, Ruth M; Barron, Leon P

    2016-01-01

    An evaluation of reduced-size particle powdering methods for the recovery of usable fingermark ridge detail from elephant ivory is presented herein for the first time as a practical and cost-effective tool in forensic analysis. Of two reduced-size powder material types tested, powders with particle sizes ≤ 40 μm offered better chances of recovering ridge detail from unpolished ivory in comparison to a conventional powder material. The quality of developed ridge detail of these powders was also assessed for comparison and automated search suitability. Powder materials and the enhanced ridge detail on ivory were analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy and interactions between their constituents and the ivory discussed. The effect of ageing on the quality of ridge detail recovered showed that the best quality was obtained within 1 week. However, some ridge detail could still be developed up to 28 days after deposition. Cyanoacrylate and fluorescently-labelled cyanoacrylate fuming of ridge detail on ivory was explored and was less effective than reduced-scale powdering in general. This research contributes to the understanding and potential application of smaller scale powdering materials for the development of ridge detail on hard, semi-porous biological material typically seized in wildlife-related crimes. PMID:26746820

  20. Methodological aspects of the white-ivory assay of Drosophila melanogaster.

    PubMed

    Ferreiro, J A; Sierra, L M; Comendador, M A

    1995-10-01

    The white-ivory somatic assay of Drosophila melanogaster was developed to detect genotoxic agents which induce loss of a tandem duplication. Although the mechanism of this loss is not known, some suggestions point to intrachromosomal recombination as the main reversion mechanism. Since the few papers published to date on this assay present controversial methodologies, prior to a larger study of chemicals with different mechanisms of action, we have carried out an analysis to optimize some conditions of this assay. For this purpose, we have used three different strains and four well characterized mutagenic chemicals: N-ethyl-N-nitrosourea (ENU), methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS) and hexamethyl phosphoramide (HMPA). The results obtained allow us to conclude that: (i) the best strain for this assay is C(1)DX,y,f/Dp(1:1:1:1)wi,y2, although the use of strain FM6,l(1)66a/Dp(1:1:1:1)wi,y2;st/st could be considered for some mechanistical studies; (ii) developmental reasons make it necessary to use as estimate of reversion frequency the proportion of eyes showing at least one spot; (iii) reversion frequency cannot be used as estimate of mutation efficiency, neither can spot size evaluate time of spot induction; (iv) the four chemicals clearly induce loss of the wi duplication; according to their activities they rank ENU > HMPA > MMS approximately EMS. PMID:7477046

  1. Detection of a meteoritic component in ivory coast tektites with rhenium-osmium isotopes.

    PubMed

    Koeberl, C; Shirey, S B

    1993-07-30

    Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. (i) The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. (ii) Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. (iii) Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost. PMID:17758170

  2. Detection of a meteoritic component in Ivory Coast tektites with rhenium-osmium isotopes

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Shirey, Steven B.

    1993-07-01

    Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost.

  3. Mapping Potential Ivory Billed Woodpecker Habitat using Lidar and Hyperspectral Data Fusion

    NASA Astrophysics Data System (ADS)

    Swatantran, A.; Dubayah, R.; Hofton, M.; Blair, J. B.; Handley, L.

    2008-12-01

    Multisensor fusion is a powerful approach towards characterizing forest structure for effective management of wildlife habitats. The rediscovery of the Ivory Billed Woodpecker in 2005 reinforced the need to map and conserve suitable habitat for the previously thought extinct bird. In this study we fused waveform lidar and hyperspectral data to map potential habitat for the woodpecker along the Lower Mississippi Valley of Arkansas. Laser Vegetation Imaging Sensor (LVIS) data was processed to produce high-resolution forest structure maps. We used multiple endmember spectral mixture analysis (MESMA) to map stressed and dead vegetation from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data. LVIS and AVIRIS maps were fused to identify habitat hot-spots based on historical records of habitat preferences of the bird. Results indicate several small hotspots in the bottomland hardwood forests, but very few large and continuous patches qualify as potential woodpecker habitat. Results from this study are expected to aid search efforts for the woodpecker and also provide useful insights into lidar fusion for large scale habitat mapping.

  4. Regulation of business activities of petroleum contractors in Cameroon, Congo, Gabon, and Ivory Coast

    SciTech Connect

    Frilet, M.; Newman, J.

    1982-03-01

    Foreign companies engaging in business in Cameroon, Congo, Gabon, and Ivory Coast are subject to a broad range of regulations. This article deals only with those aspects of the regulations that are most important to petroleum contractors intending to engage in business in these countries. The regulator scheme actually applicable in a given case will depend on the legal structure through which a corporation operates. An American corporation may envisage engaging in business on a long-term basis through a local subsidiary or branch. On the other hand, it may wish only to perform temporary activities pursuant to one or more fixed-duration contracts with petroleum companies operating in one of countries. Each of these situations is dealt with. Common features of each area of regulation were described and the differences in regulations were presented. These topics were included: exchange control regulation, corporate forms of business association, authorization to engage in business, requirement of government or local participation in capital, investment code incentives, labor law requirements, taxation of corporations, taxation of profits, taxation of income from movable capital, taxation of amounts paid abroad as technical assistance fees, royalties and similar compensation, turnover taxes, payroll taxes, taxation of business performed without forming a local company or branch, taxation of employees and Social Security contributions. (DP)

  5. Three-dimensional seismic interpretation: Espoir Field area, offshore Ivory Coast

    SciTech Connect

    Grillot, L.R.; Anderton, P.W.; Haselton, T.M.; Dermargne, J.F.

    1986-05-01

    The Espoir oil field, located approximately 13 km offshore Ivory Coast, was discovered in 1980 by a joint venture comprised of Phillips Petroleum Company, AGIP, SEDCO Energy, and PETROCI. Following the discovery, a three-dimensional seismic survey was recorded by GSI in 1981-1982 to provide detailed seismic coverage of Espoir field and adjacent features. The seismic program consisted of 7700 line-km of data acquired in a single survey area that is located on the edge of the continental shelf and extends into deep water. In comparison with previous two-dimensional seismic surveys, the three-dimensional data provided several improvements in interpretation and mapping including: (1) sharper definition of structural features, (2) reliable correlations of horizons and fault traces between closely spaced tracks, (3) detailed time contour maps from time-slice sections, and (4) improved velocity model for depth conversion. The improved mapping helped us identify additional well locations; the results of these wells compared favorably with the interpretation made prior to drilling.

  6. The Sefwi-Comoé belt Ghana/Ivory Coast : a major crustal shear zone ?

    NASA Astrophysics Data System (ADS)

    Jessell, Mark

    2010-05-01

    The Palaeoproterozoic Sefwi-Comoé region that straddles Ghana and the Ivory Coast in West Africa has been characterised as resulting from a combination of compression and simple shear during late synkinematic leucogranite intrusion. The analysis of regional geophysical datasets allows us to better define the geometry of the major lithostratigraphic packages and their structural contacts in this region. This analysis reveals a series of well defined leucogranites intrusions enveloped by high strain zones. Recent finite element modelling of two-phase aggregates has shown that we can analyse the geometry of these systems both in terms of their finite defomation and their mechanical contrast. We interpret the geometries we see in the Sefwi-Comoé region as reflecting the activity of a major crustal deformation zone which was dominated by simple shear. The comparison with the modelling suggests a finite shear strain of approximately 5 gamma, which in turn implies a lateral displacement of 400 km across the belt. Our analysis suggests that the leucogranites were already acting as more rigid bodies during the (dextral?) shearing, suggesting that their emplacement was predominantly pre-kinematic, and which has implications for their potential subsequent remobilization by gravitational forces.

  7. Draft Genome Sequences of Two Closely Related Aflatoxigenic Aspergillus Species Obtained from the Ivory Coast.

    PubMed

    Moore, Geromy G; Mack, Brian M; Beltz, Shannon B

    2016-03-01

    Aspergillus ochraceoroseus and Aspergillus rambellii were isolated from soil detritus in Taï National Park, Ivory Coast, Africa. The Type strain for each species happens to be the only representative ever sampled. Both species secrete copious amounts of aflatoxin B1 and sterigmatocystin, because each of their genomes contains clustered genes for biosynthesis of these mycotoxins. We sequenced their genomes using a personal genome machine and found them to be smaller in size (A. ochraceoroseus = 23.9 Mb and A. rambellii = 26.1 Mb), as well as in numbers of predicted genes (7,837 and 7,807, respectively), compared to other sequenced Aspergilli. Our findings also showed that the A. ochraceoroseus Type strain contains a single MAT1-1 gene, while the Type strain of A. rambellii contains a single MAT1-2 gene, indicating that these species are heterothallic (self-infertile). These draft genomes will be useful for understanding the genes and pathways necessary for the cosynthesis of these two toxic secondary metabolites as well as the evolution of these pathways in aflatoxigenic fungi. PMID:26637470

  8. [Smoking in the African setting (Abidjan, Ivory coast): patient knowledge, attitude and behavior].

    PubMed

    Koffi, N; Kouassi, B; Horo, K; Kouakou, Y G M; N'Gom, A; Toloba, Y; Bouzid, S; Aka-Danguy, E

    2004-09-01

    Recent studies on smoking conducted in the ivory coast have been sparse despite increasingly aggressive tobacco company campaigns. The purpose of this prospective study was to examine the influence of medical specialty on patient knowledge, attitude and smoking behavior among people consulting three university hospitals in Abidjan. The inquiry was performed with a questionnaire concerning a comparative series of 180 subjects (90 patients in each sample). Overall, the series included 16.10% active smokers, 15.60% former smokers, and 68.30% non-smokers, with no difference between the groups. The well-known feature of smoking with friends was main reason cited for beginning smoking. Three quarters of patients (75.9%) had attempted to stop smoking. Information about smoking was obtained from the media. The hospital was involved little in acquiring knowledge about smoking. Type of specialist consultation (hospital units providing care for smoking-related disease or not) had little influence. Hospital units should become more involved in the anti-smoking campaign. Consultations on cessation of smoking should be instituted in a country with highly aggressive smoking advertisements. PMID:15545950

  9. Taxonomic diversity and structure of benthic macroinvertebrates in Aby Lagoon (Ivory Coast, West Africa).

    PubMed

    Kouadio, K N; Diomandé, D; Ouattara, A; Koné, Y J M; Gourène, G

    2008-09-15

    The benthic macroinvertebrates of Aby lagoon (West Africa: Ivory coast) was studied during four seasons (high dry season, high rainy season, low dry season and low rainy season, respectively) from June 2006 to March 2007. The distribution of the benthic macroinvertebrates species was recorded at 13 stations on the whole of the lagoon. A total of 62 taxa of benthic macroinvertebrates belonging to 28 families and 10 orders were listed. The molluscs and crustaceans dominate qualitatively by adding up 51 and 24%, respectively of the total number of organisms. Five taxa (Corbula trigona (20%), Pachymelania aurita (12%), Clibernhardius cooki (7%), Oligochaeta (7%) and Crassostrea gasar (6%) accounted for 52% of total abundance. Classification analysis used to perform the characterisation of the lagoon on the basis of benthic macroinvertebrates showed the existence of four main clusters in which the seasonal pattern in benthic macroinvertebrates were very similar in the four seasons. In contrast the species richness and diversity indices were significantly different. Furthermore these indices where higher in the stations closer to the sea and surrounded by mangrove trees (southern area) compared to the inland ones. PMID:19137831

  10. Uncertain sightings and the extinction of the Ivory-billed Woodpecker.

    PubMed

    Solow, Andrew; Smith, Woollcott; Burgman, Mark; Rout, Tracy; Wintle, Brendan; Roberts, David

    2012-02-01

    The extinction of a species can be inferred from a record of its sightings. Existing methods for doing so assume that all sightings in the record are valid. Often, however, there are sightings of uncertain validity. To date, uncertain sightings have been treated in an ad hoc way, either excluding them from the record or including them as if they were certain. We developed a Bayesian method that formally accounts for such uncertain sightings. The method assumes that valid and invalid sightings follow independent Poisson processes and use noninformative prior distributions for the rate of valid sightings and for a measure of the quality of uncertain sightings. We applied the method to a recently published record of sightings of the Ivory-billed Woodpecker (Campephilus principalis). This record covers the period 1897-2010 and contains 39 sightings classified as certain and 29 classified as uncertain. The Bayes factor in favor of extinction was 4.03, which constitutes substantial support for extinction. The posterior distribution of the time of extinction has 3 main modes in 1944, 1952, and 1988. The method can be applied to sighting records of other purportedly extinct species. PMID:21967229

  11. A giant, complex fronto-ethmoidal ivory osteoma: Surgical technique in a resource-limited practice

    PubMed Central

    Adeleye, Amos Olufemi

    2010-01-01

    Background: Unlike small and medium size fronto-ethmoidal osteomas which are amenable to surgical excision through limited craniofacial openings, giant lesions require extensive and complex craniofacial dissection, and post lesionectomy reconstruction using an array of modern-day surgical adjuncts. This is a report of our surgical technique for the successful and esthetically fair operative resection of a giant fronto-ethmoidal osteoma in a difficult practice setting. Case Description: A 32-year-old Nigerian lady harbored a giant complex fronto-ethmoidal ivory osteoma. Deploying our understanding of modern-day advanced microsurgical anatomy and technique of skull base surgery, but under severe resource limitations, a radical total surgical resection was performed and an esthetically fair post lesionectomy reconstruction was achieved. The patient remains tumor-free in 20 months, so far, of postoperative follow-up. Conclusions: Even under severe resource limitations, inventive adaptations of modern-day skull base surgery techniques can facilitate hitherto unusual functional and esthetically successful resection of giant osteomas of the fronto-ethmoidal sinus complex. PMID:21245944

  12. The spatiotemporal pattern of earthworm community in the grass savannas of Lamto (Ivory Coast)

    PubMed Central

    Lavelle, Patrick

    2015-01-01

    Abstract Background The impact of earthworms on both soil physical properties and soil organic matter dynamics has been well documented (Lavelle and Spain 2001). There is a wealth of literature dedicated to the biological mechanisms at work or to empirical approaches based on field data. Assessing the functional role of a species or community implies establishing both time and space scales at which it is effectively the primary determinant of the process(es) at hand. In that context, space-time data analyses are powerful tools to process community data collected on numerous occasions but are, however, not widely disseminated in the community of ecologists. Although computer resources are available, one difficulty is that ad hoc field data are not always easily available which hinders the percolation of the methods. New information We provide the results of a 5 dates survey of earthworm community in a grass savanna of Lamto (Ivory Coast) conducted between 1995 and 1997. At each sampling date, earthworm community was assessed by hand-sorting a set of 100 soil monoliths distributed on a regular grid of 5 m mesh. These data were analyzed in Rossi (2003a) and are published here with the aim that they could be reanalyzed using new statistical tools (e.g. MEM analyses see Jiménez et al. 2014) or serve as example for researchers that train on space-time statistical methods. PMID:26696763

  13. Couples, PMTCT programs and infant feeding decision-making in Ivory Coast.

    PubMed

    Tijou Traoré, Annick; Querre, Madina; Brou, Hermann; Leroy, Valériane; Desclaux, Alice; Desgrées-du-Loû, Annabel

    2009-09-01

    In Sub-Saharan Africa, prevention of HIV pediatric infection due to breastfeeding requires turning to alternatives to prolonged breastfeeding: artificial feeding or exclusive breastfeeding with early weaning. Choosing a preventive option and applying it does not only depend upon the mother but also on the father and more specifically on couple interactions. To date, not enough studies have considered this question. In Abidjan, Ivory Coast, HIV-positive women and their infants were followed over two years in Ditrame Plus, a prevention of mother-to-child transmission (PMTCT) project. Using data from this project and from interviews conducted with couples and women, we analyzed the construction of decisions and practices concerning the application of preventive infant feeding options. Differences may be found between women and men in discourses regarding their attitudes, which are in part related to their conceptions of motherhood and fatherhood. We found that when men know their wife is HIV positive and are involved in the PMTCT project, they play an active role in applying the advice received. However, women do not always need the support of their spouse to undertake preventative behaviour. The project team also plays an important role in the adoption of such by women and men. The implementation of preventive options is a complex process in which three groups of actors (women, men and the project team) interact. In order to optimize PMTCT programs for couples, it is essential that this dynamic be taken into account. PMID:19586699

  14. Analgesic and antiinflammatory activities of an extract from Parkia biglobosa used in traditional medicine in the Ivory Coast.

    PubMed

    Kouadio, F; Kanko, C; Juge, M; Grimaud, N; Jean, A; N'Guessan, Y T; Petit, J Y

    2000-12-01

    In the Ivory coast, Parkia biglobosa (Mimosaceae) is used in traditional medicine as an analgesic drug, especially against dental pain. Of the three extracts obtained from the plant bark, the hexane fraction was studied to determine its analgesic and/or antiinflammatory activities. The results show that this extract possesses a marked analgesic activity when evaluated with the abdominal writhing test in mice, but, like paracetamol, was ineffective with the hot-plate method, a feature suggesting a peripheral mechanism of action. This activity was accompanied by an antiinflammatory effect, somewhat weaker than the analgesic one. PMID:11114002

  15. [Description of three new monogenean gill parasites from Mormyrus rume (Valenciennes, 1846) (Teleostei: Mormyridae) in Ivory Coast].

    PubMed

    Blahoua, K G; Pariselle, A; N'Douba, V; Kone, T; Kouassi, N J

    2009-03-01

    The study of the gill parasites from elephant fish Mormyrus rume Valenciennes, 1846 (Teleostei: Mormyridae) from the Ayamé man-made Lake (Ivory Coast) revealed the presence of three new monogenean species of the genus Bouixella Euzet & Dossou, 1976, which can be mainly distinguished from all other species of the genus by the morphology and the size of the sclerotised parts of the haptor (dorsal and ventral anchor, dorsal and ventral bar) and by the size and the structure of the male copulatory organ. In this paper, descriptions of Bouixella gorei n. sp., Bouixella yaoi n. sp. and Bouvixella koutouani n. sp. are given. PMID:19353952

  16. Additional data in support of the quadruplicated white-ivory reversion system to test for somatic genotoxicity in Drosophila melanogaster.

    PubMed

    Xamena, N; Egido, A; Velázquez, A; Creus, A; Marcos, R

    1991-06-01

    Cyclophosphamide, ethyl methanesulfonate, propyleneimine and tritiated water were tested in a new short-term somatic mutation bioassay, previously described by Green and coworkers (1986), to evaluate the suitability of the quadruplicated white-ivory system of Drosophila melanogaster for genotoxicity testing of chemicals. A 2.9-kb tandemly duplicated sequence of w+ within a w+ gene is responsible for the white-ivory phenotype. Reversion of wi to w+ is, in general, associated with the loss of the appended 2.9 kb or other alterations affecting this duplicated region. The appearance of light (white or nearly white) phenotypes could be due to the loss of some wi copies. Thus, in the eyes of adult males resulting from treated larvae, we can detect 2 types of sectors (red and light) on the orange-yellow background. Our results indicate that the genetic system used in this somatic assay is sensitive to the genotoxic effects of the 4 compounds tested. All 4 compounds tested were positive. Tritiated water had weak effects, cyclophosphamide was characterized by small revertant clones and ethyl methanesulfonate and propyleneimine by large clone size. From the available data, we feel that the wi system can be considered of potential value for genotoxicity testing. PMID:1646957

  17. Oxygen isotopes as tracers of tektite source rocks: an example from the Ivory Coast tektites and Lake Bosumtwi Crater

    NASA Astrophysics Data System (ADS)

    Blum, Joel D.; Koeberl, Christian; Chamberlain, C. Page

    1993-03-01

    Oxygen isotope studies of tektites and impact glasses provide an important tool to help in identifying the target lithologies for terrestrial impacts, including the K-T boundary impact. However, such studies may be complicated by modification of the original oxygen isotope values of some source rocks during the tektite formation process either by vapor fractionation or incorporation of meteoric water. To further investigate the relationship between the oxygen isotopic composition of tektites and their source rocks, Ivory Coast tektites and samples of impact glasses and bedrock lithologies from the Bosumtwi Crater in Ghana--which is widely believed to be the source crater for the Ivory Coast tektites--were studied. Our preliminary results suggest that the phyllites and metagraywackes from the Bosumtwi Crater were the predominant source materials for the impact glasses and tektites and that no significant oxygen isotope modification (less than 1 percent delta(O-18)) took place during impact melting. This contrasts with previous studies of moldavites and Australasian tektites and their sedimentary source materials which suggests a 4 to 5 percent lowering of delta(O-18) due to meteoric water incorporation during impact melting.

  18. Oxygen isotopes as tracers of tektite source rocks: An example from the Ivory Coast tektites and Lake Bosumtwi Crater

    NASA Technical Reports Server (NTRS)

    Blum, Joel D.; Koeberl, Christian; Chamberlain, C. Page

    1993-01-01

    Oxygen isotope studies of tektites and impact glasses provide an important tool to help in identifying the target lithologies for terrestrial impacts, including the K-T boundary impact. However, such studies may be complicated by modification of the original oxygen isotope values of some source rocks during the tektite formation process either by vapor fractionation or incorporation of meteoric water. To further investigate the relationship between the oxygen isotopic composition of tektites and their source rocks, Ivory Coast tektites and samples of impact glasses and bedrock lithologies from the Bosumtwi Crater in Ghana--which is widely believed to be the source crater for the Ivory Coast tektites--were studied. Our preliminary results suggest that the phyllites and metagraywackes from the Bosumtwi Crater were the predominant source materials for the impact glasses and tektites and that no significant oxygen isotope modification (less than 1 percent delta(O-18)) took place during impact melting. This contrasts with previous studies of moldavites and Australasian tektites and their sedimentary source materials which suggests a 4 to 5 percent lowering of delta(O-18) due to meteoric water incorporation during impact melting.

  19. Age assessment of ivory by analysis of 14C and 90Sr to determine whether there is an antique on hand.

    PubMed

    Schmied, Stefanie A K; Brunnermeier, Matthias J; Schupfner, Robert; Wolfbeis, Otto S

    2011-04-15

    A method is described to determine whether an elephant has died before 1955 or not. This is accomplished by determination of the radionuclides (14)C and (90)Sr in artifacts made of ivory. The reliability of this method is considerably increased by double nuclide analysis and therefore is applicable for judicial expert opinions. PMID:21371831

  20. Bridging the Gap: From Ivory to Corporate Tower. Proceedings of the ABCA Midwest Regional Conference (Ames, Iowa, April 19-20, 1984).

    ERIC Educational Resources Information Center

    Pearson, Patricia, Ed.

    Proceedings drawn from a conference on business communication, the 21 papers in this collection are grouped under the headings Corporate Tower Views, Bridging the Gap, and Ivory Tower Views to better reflect the joint concerns of professional communicators on the job as well as the concerns of those who teach business communication. Among the…

  1. The Red Light in the Ivory Tower: Contexts and Implications of Entrepreneurial Education. Counterpoints: Studies in the Postmodern Theory of Education. Volume 401

    ERIC Educational Resources Information Center

    Breault, Donna Adair; Callejo Perez, David M.

    2012-01-01

    "The Red Light in the Ivory Tower: Contexts and Implications of Entrepreneurial Education" critically analyzes the operational behaviors of prestigious and prestige-seeking universities, particularly within the context of budget shortfalls and increasing competition. The book challenges entrepreneurial activities within universities by exploring…

  2. Welcoming Blue-Collar Scholars into the Ivory Tower: Developing Class-Conscious Strategies for Student Success. Series on Special Student Populations

    ERIC Educational Resources Information Center

    Soria, Krista M.

    2015-01-01

    "Welcoming Blue-Collar Scholars Into the Ivory Tower" is the first volume in a new book series designed to explore how institutional policies, practices, and cultures shape learning, development, and success for students who have been historically underserved or given limited consideration in the design of higher education contexts.…

  3. Non-invasive quantitative micro-PIXE-RBS/EBS/EBS imaging reveals the lost polychromy and gilding of the Neo-Assyrian ivories from the Louvre collection.

    PubMed

    Albéric, Marie; Müller, Katharina; Pichon, Laurent; Lemasson, Quentin; Moignard, Brice; Pacheco, Claire; Fontan, Elisabeth; Reiche, Ina

    2015-05-01

    Antique objects are known to have been brightly colored. However, the appearance of these objects has changed over time and paint traces are rarely preserved. The surface of ivory objects (8th century B.C., Syria) from the Louvre museum collection (Paris) have been non-invasively studied by simultaneous particle-induced X-ray emission (PIXE) and Rutherford and elastic backscattering spectrometry (RBS/EBS) micro-imaging at the AGLAE facility (C2RMF, Paris). Qualitative 2D chemical images of elements ranging from Na to Pb on the surface of the ancient ivory carvings provide evidence of lost polychromy and gilding. Quantitative PIXE data of specific areas allow discrimination between traces of sediments and former polychromy. Different shades of blue can be differentiated from particular Pb/Cu ratios. The characterization of gilding based on RBS data demonstrates the exceptional technological skills of the Phoenician craftsmen supposed to have carved the Arslan Tash ivories. More precise reconstructions of the original polychromy compared to previous studies and a criterion for the authentication of ancient gilded ivory object are proposed. PMID:25770612

  4. Petrology and geochemistry of target rocks from the Bosumtwi impact structure, Ghana, and comparison with Ivory Coast tektites

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Reimold, Wolf Uwe; Blum, Joel D.; Chamberlain, C. Page

    1998-06-01

    The 10.5 km diameter Bosumtwi crater in Ghana, West Africa, is the most likely source crater for the Ivory Coast tektites, as the tektites and the crater have the same age (1.07 Ma), and there are close similarities between the isotopic and chemical compositions of the tektites and crater rocks. The crater is excavated in 2.1-2.2 Ga old metasediments and metavolcanics of the Birimian Supergroup. Here we present the first integrated petrographic and geochemical study of rocks from the Bosumtwi impact crater. A variety of target rocks from the Bosumtwi impact structure were selected to represent the major rock types that have been described before, resulting in four groups: shale, phyllite-graywacke, and two different types of granites (from dispersed dikes and from the so-called Pepiakese intrusion at the northeastern side of the crater). These rocks were analyzed for their major and trace element composition and their petrographic characteristics. In addition, representative samples were also analyzed for their O, Sr, and Nd isotopic compositions. The target rocks do not show any unambiguous evidence of shock metamorphism (i.e., planar deformation features, PDFs). Distinct impact-characteristic shock effects (PDFs) were identified only in clasts within suevite-derived melt fragments. The compositional range of the target rocks is significantly wider than that of the Ivory Coast tektites, but overlap the tektite compositions. A best-fit line for the Bosumtwi crater rocks in a Rb-Sr isotope evolution diagram yields an "age" of 1.98 Ga, and an initial 87Sr/ 86Sr ratio of 0.701, which is close to results previously obtained for granitoid intrusions in the Birimian of Ghana. Our Nd isotopic data yield depleted mantle model ages ranging from 2.16 to 2.64 Ga, and ɛ Nd values of -17.2 to -25.9‰. Harmonic least-squares (HMX) mixing calculations were able to reproduce the composition of Ivory Coast tektites from a mixture of Bosumtwi country rocks that include about 70

  5. Shell Worlds: The Question of Shell Stability

    NASA Astrophysics Data System (ADS)

    Roy, K. L.; Kennedy, R. G., III; Fields, D. E.

    The initial idea of shell worlds was first proposed in the January 2009 edition of JBIS. In that paper the stability of the shell around a central world was not discussed at any length except to say that it was stable due to forces induced by gravity. This paper demonstrates in a qualitative and quantitative manner that a material shell supported by atmospheric pressure around a moon or small planet is indeed stable and does not require active measures to remain centered, provided that the central body is large enough. The minimal size of the central body to provide this stability is discussed.

  6. Living Kidney Donor Transplantation in a Resource-limited Country: The Ivory Coast Experience.

    PubMed

    Ackoundou-N'Guessan, C; Hoang, A D; Ben Abdallah, T; Gnionsahe, D A; Dollo, I; Ripoche, C; Coulibaly, N; Aye, D Y; N'Guessan, F Y; Diby Kouame, B; Guei, C M; Tia, M W; Amekoudji, Y; Lagou, D A

    2015-01-01

    Renal transplantation that offers a good quality of life still is not performed by the majority of countries of black Africa. We started a pilot project of renal transplantation in Ivory Coast 2 years ago. The present paper reports the preliminary results, difficulties related to the program, and perspectives regarding its expansion. Ten living related kidney transplantations have been performed over a 2-year period. Recipients and their respective donors were male. The mean age of the recipients was 42.8 years (22-57), and the mean age of the donors was 29.4 years (22-43). The mean number of mismatches was 3.2 (0-6). None was immunized. Recipients and donors were all EBV IgG positive and CMV IgG positive. All but 1 case were induced with basiliximab. The mean graft and patient survival time was 16.6 months (6-26). The mean cold ischemic time was 2.27 hours (1-3.32). The mean serum creatinine at discharge was 241.87 μmol/L (115.18-1063.2), at 6 months was 117.20 μmol/l (95.6-139.9), at 12 months was 104.55 μmol/L (62.02-132.9), and at 24 months was 104.55 μmol/L (62.02-132.9). The mean cyclosporine through level (C0) at 6 months was 137.57 ng/mL (70-366), at 12 months was 117.33 ng/mL (62-197), and at 24 months was 78 ng/mL. The mean cyclosporine 2-hour post-administration concentration levels (C2) at 6 months was 764.9 ng/mL (430-1421), at 12 months was 937.17 ng/mL (483-1292), and at 24 months was 690.66 ng/mL (488-853). Main complications were sepsis, adenovirus hemorrhagic cystitis, new-onset diabetes after transplantation, delayed graft function, polycythemia, and cytomegalovirus infection. No clinical rejection was diagnosed over the 2-year period. Patient and graft survival was 100% at a mean post-transplantation time of approximately 16.6 months. PMID:26293016

  7. Fluctuating shells under pressure

    PubMed Central

    Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

    2012-01-01

    Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558

  8. Multiple shell fusion targets

    DOEpatents

    Lindl, J.D.; Bangerter, R.O.

    1975-10-31

    Multiple shell fusion targets for use with electron beam and ion beam implosion systems are described. The multiple shell targets are of the low-power type and use a separate relatively low Z, low density ablator at large radius for the outer shell, which reduces the focusing and power requirements of the implosion system while maintaining reasonable aspect ratios. The targets use a high Z, high density pusher shell placed at a much smaller radius in order to obtain an aspect ratio small enough to protect against fluid instability. Velocity multiplication between these shells further lowers the power requirements. Careful tuning of the power profile and intershell density results in a low entropy implosion which allows breakeven at low powers. For example, with ion beams as a power source, breakeven at 10-20 Terrawatts with 10 MeV alpha particles for imploding a multiple shell target can be accomplished.

  9. Imperfection Insensitive Thin Shells

    NASA Astrophysics Data System (ADS)

    Ning, Xin

    The buckling of axially compressed cylindrical shells and externally pressurized spherical shells is extremely sensitive to even very small geometric imperfections. In practice this issue is addressed by either using overly conservative knockdown factors, while keeping perfect axial or spherical symmetry, or adding closely and equally spaced stiffeners on shell surface. The influence of imperfection-sensitivity is mitigated, but the shells designed from these approaches are either too heavy or very expensive and are still sensitive to imperfections. Despite their drawbacks, these approaches have been used for more than half a century. This thesis proposes a novel method to design imperfection-insensitive cylindrical shells subject to axial compression. Instead of following the classical paths, focused on axially symmetric or high-order rotationally symmetric cross-sections, the method in this thesis adopts optimal symmetry-breaking wavy cross-sections (wavy shells). The avoidance of imperfection sensitivity is achieved by searching with an evolutionary algorithm for smooth cross-sectional shapes that maximize the minimum among the buckling loads of geometrically perfect and imperfect wavy shells. It is found that the shells designed through this approach can achieve higher critical stresses and knockdown factors than any previously known monocoque cylindrical shells. It is also found that these shells have superior mass efficiency to almost all previously reported stiffened shells. Experimental studies on a design of composite wavy shell obtained through the proposed method are presented in this thesis. A method of making composite wavy shells and a photogrametry technique of measuring full-field geometric imperfections have been developed. Numerical predictions based on the measured geometric imperfections match remarkably well with the experiments. Experimental results confirm that the wavy shells are not sensitive to imperfections and can carry axial compression

  10. Iridescence color of shells

    NASA Astrophysics Data System (ADS)

    Liu, Yan

    2002-06-01

    Some shells from both salt water and fresh water show the phenomenon of iridescence color. Pearls and mother-of-pearls also display this phenomenon. In the past, the cause of the iridescence color was attributed to interference. A scanning electron microscope (SEM) was used to study the surface structure of the shell of the mollusk Pinctada Margaritifera. There is a groove structure of reflection grating on the surface area in where the iridescence color appears. An optic experiment with a laser obtained a diffraction pattern produced by the reflection grating structure of the shell. The study led to a conclusion that the iridescence color of the shell is caused by diffraction. A SEM image of the shells of an abalone Haliotis Rufescens (red abalone) showed a statistically regularly arranged tile structure that serves as a two-dimensional grating. This grating structure causes the iridescence color of the shell of red abalone. The dominant color of the iridescence of shells is caused by the uneven grating efficiency in the visible wavelength range when a shell functions as a reflection grating. The wavelength of the dominant color should be at or near the wavelength of the maximum efficiency of the grating.

  11. [An Extremely Rare Case of Penetrating Head Injury Caused by a Nasal Implant Made of an Ivory Chip and a Review of the Literature].

    PubMed

    Miyahara, Makiko; Okamoto, Koichiro; Tamai, Yuta; Aishima, Kaoru; Inoue, Masato; Ohno, Hiroyasu; Hara, Tetsuo; Matsubayashi, Shigemi

    2016-06-01

    Although penetrating head injuries are very rare in Japan, an extremely rare case is reported in which an ivory chip, embedded in the subcutaneous tissue by a cosmetic rhinoplasty, penetrated the cranium. A 69-year-old woman with a psychiatric disorder suddenly jumped down from a window and bruised her face. The ivory chip went into her left frontal lobe via the frontal sinus. At surgery, it was completely removed via the nasion. There were no postoperative complications after adequate frontal sinus repair and closure of dura mater with a piece of pericranium. The literature dealing with Japanese penetrating head injuries was also reviewed. (Received May 27, 2015; Accepted December 1, 2015; Published June 1, 2016). PMID:27279165

  12. Prevalence of Newcastle disease virus and infectious bronchitis virus in avian influenza negative birds from live bird markets and backyard and commercial farms in Ivory-Coast.

    PubMed

    Kouakou, A V; Kouakou, V; Kouakou, C; Godji, P; Kouassi, A L; Krou, H A; Langeois, Q; Webby, R J; Ducatez, M F; Couacy-Hymann, E

    2015-10-01

    Newcastle disease (ND) and infectious bronchitis (IB) are two major viral diseases affecting the respiratory tracts of birds and whose impact on African poultry is still poorly known. In the present study we aimed at assessing NDV and IBV prevalences in Ivory-Coast by molecular screening of >22,000 avian swabs by nested PCR and by serology testing of close to 2000 avian sera from 2010 through 2012. The NDV and IBV seroprevalences over the study period reached 22% and 72%, respectively. We found 14.7% pooled swabs positive by PCR for NDV and 14.6% for IBV. Both pathogens are therefore endemic in Ivory-Coast. Economic losses associated with NDV and IBV infections still need to be evaluated. PMID:26412525

  13. Cohesive Elements for Shells

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Camanho, Pedro P.; Turon, Albert

    2007-01-01

    A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design.

  14. Applications of spherical shells

    NASA Technical Reports Server (NTRS)

    Wang, T. G.

    1985-01-01

    A new technique of producing hollow spheres of many materials at a very rapid rate, at very low cost, and with high reproducibility of shell diameter and wall thickness has been developed. Shells formed of metal or of other solid materials are expected to find numerous technical and industrial applications. For example, metal shells might be used as inertial confinement fusion targets, or as the principal constituents in lightweight structural materials for NASA Space Stations or DOD large antennas and mirrors, or be employed as containers for phase-change heat-storage media, or serve as containers for hazardous materials, or be employed as catalytic surface agents.

  15. Failure of Viral Shells

    NASA Astrophysics Data System (ADS)

    Klug, William S.; Bruinsma, Robijn F.; Michel, Jean-Philippe; Knobler, Charles M.; Ivanovska, Irena L.; Schmidt, Christoph F.; Wuite, Gijs J. L.

    2006-12-01

    We report a combined theoretical and experimental study of the structural failure of viral shells under mechanical stress. We find that discontinuities in the force-indentation curve associated with failure should appear when the so-called Föppl von Kármán (FvK) number exceeds a critical value. A nanoindentation study of a viral shell subject to a soft-mode instability, where the stiffness of the shell decreases with increasing pH, confirms the predicted onset of failure as a function of the FvK number.

  16. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, T.P.

    1991-11-26

    A process is disclosed for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry. 3 figures.

  17. C-Shell Cookbook

    NASA Astrophysics Data System (ADS)

    Currie, Malcolm J.

    This cookbook describes the fundamentals of writing scripts using the UNIX C shell. It shows how to combine Starlink and private applications with shell commands and constructs to create powerful and time-saving tools for performing repetitive jobs, creating data-processing pipelines, and encapsulating useful recipes. The cookbook aims to give practical and reassuring examples to at least get you started without having to consult a UNIX manual. However, it does not offer a comprehensive description of C-shell syntax to prevent you from being overwhelmed or intimidated. The topics covered are: how to run a script, defining shell variables, prompting, arithmetic and string processing, passing information between Starlink applications, obtaining dataset attributes and FITS header information, processing multiple files and filename modification, command-line arguments and options, and loops. There is also a glossary.

  18. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, Thomas P.

    1991-01-01

    A process for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry.

  19. Shell forming system

    NASA Technical Reports Server (NTRS)

    Kendall, Jr., James M. (Inventor); Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor)

    1990-01-01

    Hollow shells of high uniformity are formed by emitting liquid through an outer nozzle and gas through an inner nozzle, to form a hollow extrusion, by flowing the gas at a velocity between about 1.3 and 10 times the liquid velocity. The natural breakup rate of the extrusion can be increased to decrease shell size by applying periodic perturbations to one of the materials prior to exiting the nozzles, to a nozzle, or to the extrusion.

  20. Shells and Patterns

    ERIC Educational Resources Information Center

    Sutley, Jane

    2009-01-01

    "Shells and Patterns" was a project the author felt would easily put smiles on the faces of her fifth-graders, and teach them about unity and the use of watercolor pencils as well. It was thrilling to see the excitement in her students as they made their line drawings of shells come to life. For the most part, they quickly got the hang of…

  1. Evolving dust shells

    SciTech Connect

    Siegel, H.P.

    1981-06-15

    The reduction of the Arnowitt-Deser-Misner canonical formulation of general relativity developed in the first paper of this series is applied to the full time-evolution problem for spherically symmetric charged dust shells. Detailed pictures of shell evolution are produced. Among other things, it is found that under certain well-defined circumstances the asymptotically flat spacelike hypersurfaces of constant time ''pinch off'' and become completely closed, the closure point being a locally naked singularity.

  2. Stress Localization in Elastic Shells

    NASA Astrophysics Data System (ADS)

    Selden, Sarah; Evans, Arthur; Bende, Nakul; Hayward, Ryan; Santangelo, Christian

    Upon indentation, thin shells react by localizing strain energy in polygonal structures as opposed to a uniform axisymmetric distribution. While the formation of these localized structures are well-characterized for perfect shells, a change in shell thickness or the introduction of a crease fundamentally changes the nature of the shell deformation. We perform finite element simulations, in tandem with experiments to explore the effect of different shell geometries on the energy landscape. We find that the crease induces a new symmetry-breaking localization that does not appear in perfect shells, and we explore the deformation characteristics of the creased shell over a wide range of crease radii, and crease orientations.

  3. Off-shell CHY amplitudes

    NASA Astrophysics Data System (ADS)

    Lam, C. S.; Yao, York-Peng

    2016-06-01

    The Cachazo-He-Yuan (CHY) formula for on-shell scattering amplitudes is extended off-shell. The off-shell amplitudes (amputated Green's functions) are Möbius invariant, and have the same momentum poles as the on-shell amplitudes. The working principles which drive the modifications to the scattering equations are mainly Möbius covariance and energy momentum conservation in off-shell kinematics. The same technique is also used to obtain off-shell massive scalars. A simple off-shell extension of the CHY gauge formula which is Möbius invariant is proposed, but its true nature awaits further study.

  4. A new genus of Metadilepididae (Cestoda: Cyclophyllidea) parasitic in Terpsiphone rufiventer (Aves: Muscicapidae) from the Ivory Coast.

    PubMed

    Mariaux, J; Bona, F V; Vaucher, C

    1992-04-01

    Pseudadelphoscolex eburnensis, a new genus and species of metadilepidid Cyclophyllidea parasitic in the red-bellied paradise flycatcher, Terpsiphone rufiventer, from the Ivory Coast, is described. The new species is characterized by davaineidlike rostellar hooks, absence of a rostellar pouch, a huge cirrus pouch in gravid proglottids, a bilobed uterus that becomes progressively reticular, absence of a paruterine organ, and eggs with an internal coat forming a crescentic protuberance outside the embryophore. The presence of a single row of rostellar hooks together with the lack of spines on the sucker and the structure and position of the uterus exclude this new material from Davaineidae. It cannot be placed in Dilepididae due to the lack of a rostellar pouch or in Paruterinidae because of the lack of a paruterine organ. The position of the excretory ducts in relation to the genital pores and the alternance of these pores are the main characters used to exclude this new species from the known genera of Metadilepididae. The diversity of forms of Metadilepididae in intertropical terrestrial birds is increased, and the validity of this taxon is strengthened. PMID:1313500

  5. [Several yellow fever cases in an endemic area in Ivory Coast: serological and epidemiological evidence (author's transl)].

    PubMed

    Chippaux, A; Chippaux-Hyppolite, C l; Monteny-Vandervorst, N; Souloumiac-Deprez, D

    1981-01-01

    1 - More than hundred febrile haemorrhagic jaundice cases with an unexpectedly high number of death happened in the north-west of the Ivory Coast between October 1977 and December 1977. It was the end of the rainy season and in this area, yellow fever is a dreadful eventuality. 2 - Epidemiological and serological survey was immediately carried out. Presence of numerous yellow fever potential vectors was well known and has been noticed in September 1977; there were some left in December 1977. Therefore no virus was isolated either in September or further. 3 - Haemagglutination-inhibition, complement-fixation and neutralization tests were performed with six flavivirus antigens, i.e. yellow fever, Wesselsbron, West Nile, Ntaya, Uganda S and Zika. 2 or 3 sera from 29 patients and 49 school children who have recent jaundice history, sometimes with haemorrhagic symptoms, were available. Single sera from 52 young rural workers and 402 inhabitants of surrounding villages were examined too. 4 - By the way of clinical, epidemiological, serological evidence, authors concluded 21 cases were certainly yellow fever. Evidence of 2 other cases was demonstrated by specific micropathological features. Furthermore, by serological results, 20 were probably yellow fever, 15 were inconclusive and 476 certainly not. 5 - Authors discussed some specific difficulties of yellow fever retrospective diagnosis in flavivirus endemic area. PMID:6268925

  6. Multi-Shell Hollow Nanogels with Responsive Shell Permeability

    NASA Astrophysics Data System (ADS)

    Schmid, Andreas J.; Dubbert, Janine; Rudov, Andrey A.; Pedersen, Jan Skov; Lindner, Peter; Karg, Matthias; Potemkin, Igor I.; Richtering, Walter

    2016-03-01

    We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity.

  7. Multi-Shell Hollow Nanogels with Responsive Shell Permeability

    PubMed Central

    Schmid, Andreas J.; Dubbert, Janine; Rudov, Andrey A.; Pedersen, Jan Skov; Lindner, Peter; Karg, Matthias; Potemkin, Igor I.; Richtering, Walter

    2016-01-01

    We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity. PMID:26984478

  8. Multi-Shell Hollow Nanogels with Responsive Shell Permeability.

    PubMed

    Schmid, Andreas J; Dubbert, Janine; Rudov, Andrey A; Pedersen, Jan Skov; Lindner, Peter; Karg, Matthias; Potemkin, Igor I; Richtering, Walter

    2016-01-01

    We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity. PMID:26984478

  9. Shell Biorefinery: Dream or Reality?

    PubMed

    Chen, Xi; Yang, Huiying; Yan, Ning

    2016-09-12

    Shell biorefinery, referring to the fractionation of crustacean shells into their major components and the transformation of each component into value-added chemicals and materials, has attracted growing attention in recent years. Since the large quantities of waste shells remain underexploited, their valorization can potentially bring both ecological and economic benefits. This Review provides an overview of the current status of shell biorefinery. It first describes the structural features of crustacean shells, including their composition and their interactions. Then, various fractionation methods for the shells are introduced. The last section is dedicated to the valorization of chitin and its derivatives for chemicals, porous carbon materials and functional polymers. PMID:27484462

  10. Oyster shell conveyor used to lift shells from the dock ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oyster shell conveyor used to lift shells from the dock into the receiving room housed in the 1965 concrete block addition. - J.C. Lore Oyster House, 14430 Solomons Island Road, Solomons, Calvert County, MD

  11. Resource Wars and Conflict Ivory: The Impact of Civil Conflict on Elephants in the Democratic Republic of Congo - The Case of the Okapi Reserve

    PubMed Central

    Beyers, Rene L.; Hart, John A.; Sinclair, Anthony R. E.; Grossmann, Falk; Klinkenberg, Brian; Dino, Simeon

    2011-01-01

    Human conflict generally has substantial negative impacts on wildlife and conservation. The recent civil war (1995-2006) in the Democratic Republic of Congo (DRC) resulted in a significant loss of wildlife, including elephants, due to institutional collapse, lawlessness and unbridled exploitation of natural resources such as minerals, wood, ivory and bushmeat. We used data from distance sampling surveys conducted before and after the war in a protected forest, the Okapi Faunal Reserve, to document changes in elephant abundance and distribution. We employed Generalized Additive Models to relate changes in elephant distribution to human and environmental factors. Populations declined by nearly fifty percent coinciding with a major increase in elephant poaching as indicated by reports of ivory trade during the war. Our results suggest that humans influenced elephant distribution far more than habitat, both before and after the war, but post-war models explained more of the variation. Elephant abundance declined more, closer to the park boundary and to areas of intense human activity. After the war, elephant densities were relatively higher in the centre of the park where they were better protected, suggesting that this area may have acted as a refuge. In other sites in Eastern DRC, where no protection was provided, elephants were even more decimated. Post-war dynamics, such as weakened institutions, human movements and availability of weapons, continue to affect elephants. Survival of remaining populations and recovery will be determined by these persistent factors and by new threats associated with growing human populations and exploitation of natural resources. Prioritizing wildlife protection, curbing illegal trade in ivory and bushmeat, and strengthening national institutions and organizations in charge of conservation will be crucial to counter these threats. PMID:22096529

  12. Resource wars and conflict ivory: the impact of civil conflict on elephants in the Democratic Republic of Congo--the case of the Okapi Reserve.

    PubMed

    Beyers, Rene L; Hart, John A; Sinclair, Anthony R E; Grossmann, Falk; Klinkenberg, Brian; Dino, Simeon

    2011-01-01

    Human conflict generally has substantial negative impacts on wildlife and conservation. The recent civil war (1995-2006) in the Democratic Republic of Congo (DRC) resulted in a significant loss of wildlife, including elephants, due to institutional collapse, lawlessness and unbridled exploitation of natural resources such as minerals, wood, ivory and bushmeat. We used data from distance sampling surveys conducted before and after the war in a protected forest, the Okapi Faunal Reserve, to document changes in elephant abundance and distribution. We employed Generalized Additive Models to relate changes in elephant distribution to human and environmental factors. Populations declined by nearly fifty percent coinciding with a major increase in elephant poaching as indicated by reports of ivory trade during the war. Our results suggest that humans influenced elephant distribution far more than habitat, both before and after the war, but post-war models explained more of the variation. Elephant abundance declined more, closer to the park boundary and to areas of intense human activity. After the war, elephant densities were relatively higher in the centre of the park where they were better protected, suggesting that this area may have acted as a refuge. In other sites in Eastern DRC, where no protection was provided, elephants were even more decimated. Post-war dynamics, such as weakened institutions, human movements and availability of weapons, continue to affect elephants. Survival of remaining populations and recovery will be determined by these persistent factors and by new threats associated with growing human populations and exploitation of natural resources. Prioritizing wildlife protection, curbing illegal trade in ivory and bushmeat, and strengthening national institutions and organizations in charge of conservation will be crucial to counter these threats. PMID:22096529

  13. Impact of vertical structure on water mass circulation in a tropical lagoon (Ebrié, Ivory Coast)

    NASA Astrophysics Data System (ADS)

    Brenon, Isabelle; Audouin, Olivier; Pouvreau, Nicolas; Maurin, Jean-Christophe

    2009-09-01

    A one-dimensional vertical model has been developed to simulate the water mass circulation along the vertical structure in all deep coastal areas. The model has hydrodynamic and transport components solved using finite difference scheme. The one-dimensional vertical model results are coupled to the vertically averaged two-dimensional model results at each point of a horizontal grid. A theoretical salinity profile is introduced for each vertically integrated value obtained from the 2DH model results. A viscosity profile, simulating a viscosity value close to zero at the surface and with large viscosity gradients, is applied along the water column. The model is applied to the Vridi channel, connecting the Ebrié lagoon to the sea (Ivory Coast). The response of the Ebrié lagoon is studied in terms of inflow and outflow of water in the system through the Vridi channel. Due to the abrupt variation of the surface slope, vertical velocities along the water column show an anticlockwise spiral from bottom to surface during a tidal cycle. Due to the bottom friction and to the vertical viscosity profile, velocities decrease from surface to bottom. However, the freshwater inflow slows down the tidal propagation during the flood and causes the surface velocity to be smaller than the bottom velocity at mid-tide. Close to the bottom, velocities follow an anticlockwise movement due to the tidal propagation. At the water surface, velocities follow only an alternative movement of either ebb or flood, along the channel direction. No cross shore velocities can develop at the surface in the channel.

  14. Seasonal variability of carbon dioxide and methane in the rivers and lagoons of Ivory Coast (West Africa)

    NASA Astrophysics Data System (ADS)

    Koné, Y. J. M.; Abril, G.; Delille, B.; Borges, A. V.

    2009-04-01

    We report a data-set of carbon dioxide (CO2) and dissolved methane (CH4) in three rivers (Bia, Tanoé and Comoé) and five lagoons (Tendo, Aby, Ebrié, Potou and Grand-Lahou) of Ivory Coast (West Africa), during the four main climatic seasons (high dry season, high rainy season, low dry season and low rainy season). The surface waters of the three rivers were oversaturated in CO2 and CH4 with respect to atmospheric equilibrium, the seasonal variability of CO2 and CH4 seemed to be largely controlled by dilution during the flooding period. The strong correlation of CH4 concentrations with the partial pressure of CO2 (pCO2) confirm the dominance of a continental sources (from soils) for both CO2 and CH4 in these rivers. The largest CH4 over-saturations and diffusive air-water CH4 fluxes were observed in the Tendo and Aby lagoons that are permanently stratified systems (unlike the other 3 lagoons), leading to anoxic bottom waters favorable for a large CH4 production. In addition, these two stratified lagoons showed low pCO2 values due to high primary production, which suggests an efficient transfer of organic matter across the pycnocline. As a result, the stratified Tendo and Aby lagoons were respectively, a low source of CO2 to the atmosphere and a sink of atmospheric CO2 while the other 3 well-mixed lagoons were strong sources of CO2 to the atmosphere but lower sources of CH4 to the atmosphere.

  15. Shell Creek Summers

    ERIC Educational Resources Information Center

    Seier, Mark; Goedeken, Suzy

    2005-01-01

    In 2002 Shell Creek Watershed Improvement Group turned to the Newman Grove Public Schools' science department to help educate the public on water quality in the watershed and to establish a monitoring system that would be used to improve surface and groundwater quality in the creek's watershed. Nebraska Department of Environmental Quality provided…

  16. Shell Higher Olefins Process.

    ERIC Educational Resources Information Center

    Lutz, E. F.

    1986-01-01

    Shows how olefin isomerization and the exotic olefin metathesis reaction can be harnessed in industrial processes. Indicates that the Shell Higher Olefins Process makes use of organometallic catalysts to manufacture alpha-olefins and internal carbon-11 through carbon-14 alkenes in a flexible fashion that can be adjusted to market needs. (JN)

  17. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a distance of more than one-fourth the circumference of the shell, measured in the direction of the crack....

  18. Les sous-prefectures de Sikensi et Dabakala, Cote-d'Ivoire. (The Regions of Sikensi and Dabakala, Ivory Coast.) Method de preparation de la carte scolaire: etudes de cas 9.

    ERIC Educational Resources Information Center

    Hallak, J.; And Others

    This volume contains the results of the first study of the problems associated with using educational television in curriculum planning in the Ivory Coast. The study was conducted in two districts of this African country, one relatively developed and situated in the southern part of the country, and the other more characteristic of the poorer…

  19. Optimum shell design.

    NASA Technical Reports Server (NTRS)

    Salama, A. M.; Ross, R. G., Jr.

    1973-01-01

    Comparison of two methods, namely Nedler and Mead's (1965) simplex method and Davidon's (1959) variable metric method, for achieving optimum design in terms of minimum weight for rotational shells under certain constraints. The superiority of one of the methods over the other is shown to depend, among other things, upon the form of the function to be minimized, and whether or not it is continuous everywhere in values and derivatives.

  20. Groundwater Pathways In Fractured Heterogeneous Granitic Aquifers - A Hydrochemistry Survey In The Sassandra Watershed (Inland Ivory Coast

    NASA Astrophysics Data System (ADS)

    Yao, T.; Fouche, O.

    2008-12-01

    Hydrogeochemical data and Landsat images are used to characterize the groundwater flow in a complex fractured granitic aquifer system located at the South-West of Ivory Coast (West Africa). The specific processing of the Landsat ETM+ images allows producing a detailed map of faults having length more than 3 km. The map is integrated with other data sources into a geographical information system (GIS) in order to identify areas favourable to groundwater sampling in fractured rock. The results of statistical analyses, as applied to hydrochemical data set clearly indicate that the groundwater of the study region is principally of Ca-Mg-HCO3 and Na-K-HCO3 types. The Ca-HCO3 type waters occur in areas of recharge (generally topographically higher area) i.e. where recharge occurs relatively fast. These waters generally have lower pH and EC values. The recharge occurs through preferential pathways such as alongside dykes and sills and the various fracture and joint patterns that transect the study area. The Na- HCO3 and Na-SO4 type waters occur in discharging and static regimes (the lower lying areas) where evaporation and cation exchange are the dominant processes. Ground waters are mostly oxidizing in character, and clearly unsaturated with respect to calcite, reflecting the small amount of carbonate in the aquifer. A few samples are reducing, with low NO3 and high dissolved Fe2+ and Mn2+ concentration and occur in the valley area. These reducing waters are thought to have experienced a deeper circulation and longer residence time in which reducing reactions have proceeded, with groundwater discharge along the valleys bottom. The chemistry of major ions, here applied to fractured aquifers, turns to be a powerful tool when carefully compared with a map of fault traces. We obtain a sufficient knowledge of the aquifer heterogeneity prior to realize a zoning of the region, based on cells with homogeneous hydrodynamic behaviour in which local permeability ellipses are

  1. Palaeoclimatic and deforestation effect on the coastal fresh groundwater resources of SE Ivory Coast from isotopic and chemical evidence

    NASA Astrophysics Data System (ADS)

    Adiaffi, Bernard; Marlin, Christelle; Oga, Yéï Marie Solange; Massault, Marc; Noret, Aurelie; Biemi, Jean

    2009-05-01

    SummaryIn the South-east of the Ivory Coast, two aquifer systems have been studied in the sedimentary deposits at the South and in the fractured bedrock at the North of the study area (5-6°N, 2.40-4.40°W) : (1) the Continental Terminal (CT) and (2) the Paleoproterozoïc Bedrock (PB). In the studied area, the vegetation cover has undergone significant changes since 1955 in addition to climate change. Rainforests have gradually disappeared due to natural and anthropological deforestation. The impact of deforestation on groundwater of the PB and on the CT has been studied by a geochemical approach. Stable isotopes ( 18O, 2H and 13C) contents, radiocarbon ( 14C) contents and chemical data (major ions) have been measured on a set of 25 groundwater samples. The residence time of the groundwaters is estimated with the 14C using two models: (i) the model of well-mixed reservoir (WMR model) and (ii) the piston flow model (PF model). The range of the PB groundwater residence time (15,200-8300 to ˜300-100 a BP) for both models shows that the recharge has started at the beginning of the post-glacial period whereas the CT aquifer recharge is much more recent (from 300 a BP to today). The PB groundwater provides information about paleoclimatic conditions that occurred over the studied area during the late Pleistocene. The low contents indicate cold and/or more humid conditions of recharge. During that period, the low content of 13C is consistent with a vegetation cover dominated by rainforest (C 3 plants). After the 20th century, the progressive evolution of vegetation cover from forest to cultivated plants and grasses is shown by the enrichment of groundwater in 13C (C 3 plants to C 4 plants). The relatively high mineralization level (mean of 143.7 mg L -1) and high δ18O- δ2H values of modern PB groundwater reflect of a recharge process that is slowed by a thick layer (16.3-72.5 m) of weathered formations above the PB formations. Groundwaters of the CT aquifer are

  2. Shell structure from nuclear observables

    NASA Astrophysics Data System (ADS)

    Bentley, I.; Rodríguez, Y. Colón; Cunningham, S.; Aprahamian, A.

    2016-04-01

    The appearance and disappearance of shells and subshells are determined using a previously introduced method of structural analysis. This work extends the approach and applies it to protons, in addition to neutrons, in an attempt to provide a more complete understanding of shell structure in nuclei. Experimental observables including the mean-square charge radius, as well as other spectroscopic and mass related quantities are analyzed for extrema. This analysis also uses differential observables among adjacent even-even nuclei to serve as the derivatives for these quantities of interest. Local extrema in these quantities indicate shell structure and the lack of local extrema indicate missing shell closures. The shell structure of low-mass nuclei is inconsistent likely as a consequence of the single-particle structure. Additionally, multiple shell features occurring in midshell regions are determined by combining information from two or more observables. Our results near stability complement previous observations further out.

  3. The structure of circumstellar shells

    NASA Technical Reports Server (NTRS)

    Fix, John D.

    1993-01-01

    This document provides a report on research activities carried out with the support of NASA grant NAG 5-1174, the Structure of Circumstellar Shells, funded under the Astrophysics Data Program. The research carried out with the support of this grant is a study of the properties of circumstellar dust shells for which spectra are available through IRAS low resolution spectrometry (LRS). This research consisted of the development and application of models of axisymmetric circumstellar shells and a preliminary survey of the applicability of neural nets for analysis of the IRAS LRS spectra of circumstellar dust shells.

  4. Automated shell theory for rotating structures (ASTROS)

    NASA Technical Reports Server (NTRS)

    Foster, B. J.; Thomas, J. M.

    1971-01-01

    A computer program for analyzing axisymmetric shells with inertial forces caused by rotation about the shell axis is developed by revising the STARS II shell program. The basic capabilities of the STARS II shell program, such as the treatment of the branched shells, stiffened wall construction, and thermal gradients, are retained.

  5. STUDIES ON SHELL FORMATION

    PubMed Central

    Watabe, Norimitsu; Wilbur, Karl M.

    1961-01-01

    Details of crystal growth in the calcitostracum of Crassostrea virginica have been studied with the purpose of analyzing the formation of the overlapping rows of oriented tabular crystals characteristic of this part of the shell. Crystal elongation, orientation, and dendritic growth suggest the presence of strong concentration gradients in a thin layer of solution in which crystallization occurs. Formation of the overlapping rows can be explained by three processes observed in the shell: a two-dimensional tree-like dendritic growth in which one set of crystal branchings creeps over an adjacent set of branchings; three-dimensional dendritic growth; and growth by dislocation of crystal surfaces. Multilayers of crystals may thus be formed at one time. This is favored by infrequent secretion of a covering organic matrix which would inhibit crystal growth. The transitional zone covering the outer part of the calcitostracum and the inner part of the prismatic region is generally characterized by aggregates of small crystals with definite orientation. Growth in this zone appears to take place in a relatively homogeneous state of solution without strong concentration gradients. Thin membranes and bands of organic matrix were commonly observed in the transitional zone bordering the prismatic region. The membrane showed a very fine oriented network pattern. PMID:13783329

  6. Studies on Shell Formation

    PubMed Central

    Watabe, Norimitsu; Sharp, D. Gordon; Wilbur, Karl M.

    1958-01-01

    Electron microscope observations have been made by means of the replica method on growth processes of calcite crystals of the nacreous layer of the shell of the oyster, Crassostrea virginica. Layer formation is initiated by the secretion of a conchiolin matrix and the deposition of rounded crystal seeds on or in this material. In some areas crystal seeds are elongate and within a given area show a similar orientation, probably due to slower deposition. The seeds appear to increase in size by dendritic growth, and smaller seeds become incorporated into larger ones which come into contact to form a single layer. With further growth, crystals overlap, forming a step-like arrangement. The direction of growth is frequently different in neighboring regions. Crystal seeds deposited on crystal surfaces are usually elongate and oriented. Well developed crystals have a tabular idiomorphic form and are parallel in their growth. Rounded and irregular crystals were also observed. The crystals show reticular structure with units of the order of 100 A and striations corresponding with the rhombohedral axes of the crystals. The role of the mantle is discussed in relation to the growth patterns of crystals and shell structure. PMID:13549499

  7. Hi shells, supershells, shell-like objects, and ''worms''

    SciTech Connect

    Heiles, C.

    1984-08-01

    We present photographic representations of the combination of two Hi surveys, so as to eliminate the survey boundaries at Vertical BarbVertical Bar = 10/sup 0/. We also present high-contrast photographs for particular velocities to exhibit weak Hi features. All of these photographs were used to prepare a new list of Hi shells, supershells, and shell-like objects. We discuss the structure of three shell-like objects that are associated with high-velocity gas, and with gas at all velocities that is associated with radio continuum loops I, II, and III. We use spatial filtering to find wiggly gas filaments: ''worms'': crawling away from the galactic plane in the inner Galaxy. The ''worms'' are probably parts of shells that are open at the top; such shells should be good sources of hot gas for the galactic halo.

  8. Time-resolved microscopy reveals the driving mechanism of particle formation during ultrashort pulse laser ablation of dentin-like ivory

    NASA Astrophysics Data System (ADS)

    Domke, Matthias; Gavrilova, Anna; Rapp, Stephan; Frentzen, Matthias; Meister, Joerg; Huber, Heinz P.

    2015-07-01

    In dental health care, the application of ultrashort laser pulses enables dental tissue ablation free from thermal side effects, such as melting and cracking. However, these laser types create undesired micro- and nanoparticles, which might cause a health risk for the patient or surgeon. The aim of this study was to investigate the driving mechanisms of micro- and nanoparticle formation during ultrashort pulse laser ablation of dental tissue. Time-resolved microscopy was chosen to observe the ablation dynamics of mammoth ivory after irradiation with 660 fs laser pulses. The results suggest that nanoparticles might arise in the excited region. The thermal expansion of the excited material induces high pressure in the surrounding bulk tissue, generating a pressure wave. The rarefaction wave behind this pressure wave causes spallation, leading to ejection of microparticles.

  9. Time-resolved microscopy reveals the driving mechanism of particle formation during ultrashort pulse laser ablation of dentin-like ivory.

    PubMed

    Domke, Matthias; Gavrilova, Anna; Rapp, Stephan; Frentzen, Matthias; Meister, Joerg; Huber, Heinz P

    2015-07-01

    In dental health care, the application of ultrashort laser pulses enables dental tissue ablation free from thermal side effects, such as melting and cracking. However, these laser types create undesired micro- and nanoparticles, which might cause a health risk for the patient or surgeon. The aim of this study was to investigate the driving mechanisms of micro- and nanoparticle formation during ultrashort pulse laser ablation of dental tissue. Time-resolved microscopy was chosen to observe the ablation dynamics of mammoth ivory after irradiation with 660 fs laser pulses. The results suggest that nanoparticles might arise in the excited region. The thermal expansion of the excited material induces high pressure in the surrounding bulk tissue, generating a pressure wave. The rarefaction wave behind this pressure wave causes spallation, leading to ejection of microparticles. PMID:26172613

  10. Biomechanics of turtle shells: how whole shells fail in compression.

    PubMed

    Magwene, Paul M; Socha, John J

    2013-02-01

    Turtle shells are a form of armor that provides varying degrees of protection against predation. Although this function of the shell as armor is widely appreciated, the mechanical limits of protection and the modes of failure when subjected to breaking stresses have not been well explored. We studied the mechanical properties of whole shells and of isolated bony tissues and sutures in four species of turtles (Trachemys scripta, Malaclemys terrapin, Chrysemys picta, and Terrapene carolina) using a combination of structural and mechanical tests. Structural properties were evaluated by subjecting whole shells to compressive and point loads in order to quantify maximum load, work to failure, and relative shell deformations. The mechanical properties of bone and sutures from the plastral region of the shell were evaluated using three-point bending experiments. Analysis of whole shell structural properties suggests that small shells undergo relatively greater deformations before failure than do large shells and similar amounts of energy are required to induce failure under both point and compressive loads. Location of failures occurred far more often at sulci than at sutures (representing the margins of the epidermal scutes and the underlying bones, respectively), suggesting that the small grooves in the bone created by the sulci introduce zones of weakness in the shell. Values for bending strength, ultimate bending strain, Young's modulus, and energy absorption, calculated from the three-point bending data, indicate that sutures are relatively weaker than the surrounding bone, but are able to absorb similar amounts of energy due to higher ultimate strain values. PMID:23203474

  11. Biomineralisation in Mollusc shells

    NASA Astrophysics Data System (ADS)

    Dauphin, Y.; Cuif, J. P.; Salomé, M.; Williams, C. T.

    2009-04-01

    The main components of Mollusc shells are carbonate minerals: calcite and aragonite. ACC is present in larval stages. Calcite and aragonite can be secreted simultaneously by the mantle. Despite the small number of varieties, the arrangement of the mineral components is diverse, and dependant upon the taxonomy. They are also associated with organic components much more diverse, the diversity of which reflects the large taxonomic diversity. From TGA analyses, the organic content (water included) is high (>5% in some layers). The biomineralisation process is not a passive precipitation process, but is strongly controlled by the organism. The biological-genetic control is shown by the constancy of the arrangement of the layers, the mineralogy and the microstructure in a given species. Microstructural units (i.e. tablets, prisms etc.) have shapes that do not occur in non-biogenic counterparts. Nacreous tablets, for example, are flattened on their crystallographic c axis, which is normally the axis of maximum growth rate for non-biogenic aragonite. Morever, their inner structure is species-specific: the arrangements of nacreous tablets in Gastropoda - Cephalopoda, and in Bivalvia differ, and the inner arrangement of the nacreous tablets is different in ectocochlear and endocochlear Cephalopoda. The organic-mineral ratios also differ in the various layers of a shell. Differences in chemical composition also demonstrates the biological-genetic control: for example, aragonite has a low Sr content unknown in non-biogenic samples; two aragonitic layers in a shell have different Sr and Mg contents, S is higher in calcitic layers. Decalcification releases soluble (SOM) and insoluble (IOM) organic components. Insoluble components form the main part of the intercrystalline membranes, and contain proteins, polysaccharides and lipids. Soluble phases are present within the crystals and the intercrystalline membranes. These phases are composed of more or less glycosylated proteins

  12. detached_shells_carbon_stars

    NASA Astrophysics Data System (ADS)

    Hony, Sacha; Bouwman, Jeroen; Waters, Laurens

    2004-09-01

    We propose to obtain 19-37 micrometer IRS spectra of the detached shells around nearby carbon-stars. We have selected a small (11) sample of bright, well studied, carbon-stars with known detached shells. The sample covers a range of angular diameters of the detached shells from 8-200" and stellar effective temperatures between 800-2600 K. With the spectra of the dust in the detached shell we aim to establish: i) The location of the shell. ii) The chemistry of the shell in order to constrain it's origin. iii) Test the MgS identification for the ``30'' micrometer emission feature. iv) Determine observationally the relationship between the ``30'' micrometer feature peak-position and the distance to the star. These observations will contribute greatly to the understanding AGB-star mass loss, in general, and the phenomenon of detached shells around carbon-stars, in particular. They will also be used to develop a diagnostic tool that allows to study detached shell properties of distant carbon-stars, that cannot be spatially resolved, based on their IR spectrum alone. The total requested time is 2.5h.

  13. Foam shell cryogenic ICF target

    DOEpatents

    Darling, Dale H.

    1987-01-01

    A uniform cryogenic layer of DT fuel is maintained in a fusion target having a low density, small pore size, low Z rigid foam shell saturated with liquid DT fuel. Capillary action prevents gravitational slumping of the fuel layer. The saturated shell may be cooled to produce a solid fuel layer.

  14. Manufacturing Complicated Shells And Liners

    NASA Technical Reports Server (NTRS)

    Sobol, Paul J.; Faucher, Joseph E.

    1993-01-01

    Explosive forming, wax filling, and any one of welding, diffusion bonding, or brazing used in method of manufacturing large, complicated shell-and-liner vessels or structures. Method conceived for manufacture of film-cooled rocket nozzles but applicable to joining large coaxial shells and liners in general.

  15. The role of savannas in the terrestrial Si cycle: A case-study from Lamto, Ivory Coast

    NASA Astrophysics Data System (ADS)

    Alexandre, Anne; Bouvet, Mickael; Abbadie, Luc

    2011-08-01

    Savannas currently occupy a fifth of the earth's land surface and are predicted to expand in the next few centuries at the expense of tropical forests, mainly as a result of deforestation and human fires. Can such a vegetation trend impact, through changes in plant Si cycling, the lithogenic silicon (LSi) release into soils (through chemical weathering) and the net dissolved Si (DSi) outputs from soils to stream water (through chemical denudation)? The first step of an investigation requires quantifying the net Si fluxes involved in the plant/soil system. Here, a schematic steady-state Si cycle, established for a tropical humid savanna (Lamto, Ivory Coast) that developed on a ferruginous soil and is subjected to annual fires, is presented. Erosion was assumed to be insignificant. LSi and biogenic Si (BSi under the form of phytoliths) pools were measured, and Si fluxes were estimated from Si concentrations and mass balance calculation. Identification of plant and soil phytoliths indicated that the soil BSi pool is in equilibrium with the current BSi input by the savanna. In the soil column, mixing between a young rapidly recycled BSi pool and an old stable BSi pool is attested by a mixing line equation. Storage of the old BSi pool is assimilated as a BSi output from the plant/soil system. A BSi output additionally occurs after annual fires, when ashes are exported. Both BSi outputs decrease as much the BSi dissolution. In order to uptake constant DSi flux, the savanna increases by three to eight times the net LSi release, depending upon the post-fire ash exportation scenario. A comparison between savanna and rainforest Si cycles that maximizes the differences in plant/soil systems and minimizes differences in climate is presented. The comparison revealed that BSi storage is higher in the savanna soil than in the rainforest soil, mainly due to BSi production that is twice higher in the savanna (127 vs 67 kg/ha/yr). The resulting LSi release that is enhanced by plant

  16. The role of savannas in the terrestrial Si cycle: A case-study from Lamto, Ivory Coast

    NASA Astrophysics Data System (ADS)

    Alexandre, A. E.; Abbadie, L.

    2011-12-01

    Savannas currently occupy a fifth of the earth's land surface and are predicted to expand in the next few centuries at the expense of tropical forests, mainly as a result of deforestation and human fires. Can such a vegetation trend impact, through changes in plant Si cycling, the lithogenic silicon (LSi) release into soils (through chemical weathering) and the net dissolved Si (DSi) outputs from soils to stream water (through chemical denudation)? The first step of an investigation requires quantifying the net Si fluxes involved in the plant/soil system. Here, a schematic steady-state Si cycle, established for a tropical humid savanna (Lamto, Ivory Coast) that developed on a ferruginous soil and is subjected to annual fires, is presented. Erosion was assumed to be insignificant. LSi and biogenic Si (BSi under the form of phytoliths) pools were measured, and Si fluxes were estimated from Si concentrations and mass balance calculation. Identification of plant and soil phytoliths indicated that the soil BSi pool is in equilibrium with the current BSi input by the savanna. In the soil column, mixing between a young rapidly recycled BSi pool and an old stable BSi pool is attested by a mixing line equation. Storage of the old BSi pool is assimilated as a BSi output from the plant/soil system. A BSi output additionally occurs after annual fires, when ashes are exported. Both BSi outputs decrease as much the BSi dissolution. In order to uptake constant DSi flux, the savanna increases by three to eight times the net LSi release, depending upon the post-fire ash exportation scenario. A comparison between savanna and rainforest Si cycles that maximizes the differences in plant/soil systems and minimizes differences in climate is presented. The comparison revealed that BSi storage is higher in the savanna soil than in the rainforest soil, mainly due to BSi production that is twice higher in the savanna (127 vs 67 kg/ha/yr). The resulting LSi release that is enhanced by plant

  17. Palaeoproterozoic high-pressure granulite overprint of the Archaean continental crust: evidence for homogeneous crustal thickening (Man Rise, Ivory Coast)

    NASA Astrophysics Data System (ADS)

    Pitra, Pavel; Kouamelan, Alain N.; Ballèvre, Michel; Peucat, Jean-Jacques

    2010-05-01

    The character of mountain building processes in the Palaeoproterozoic times is subject to much debate. The local observation of Barrovian-type assemblages and high-pressure granulite relics in the Man Rise (Côte d'Ivoire), led some authors to argue that Eburnean (Palaeoproterozoic) reworking of the Archaean basement was achieved by modern-style thrust-dominated tectonics (e.g., Feybesse & Milési, 1994). However, it has been suggested that crustal thickening and subsequent exhumation of high-pressure crustal rocks can be achieved by virtue of homogeneous, fold-dominated deformation of hot crustal domains even in Phanerozoic orogenic belts (e.g., Schulmann et al., 2002; 2008). We describe a mafic granulite of the Kouibli area (Archaean part of the Man Rise, western Ivory Coast) that displays a primary assemblage (M1) containing garnet, diopsidic clinopyroxene, red-brown pargasitic amphibole, plagioclase (andesine), rutile, ilmenite and quartz. This assemblage is associated with a subvertical regional foliation. Symplectites that develop at the expense of the M1 assemblage contain orthopyroxene, clinopyroxene, plagioclase (bytownite), green pargasitic amphibole, ilmenite and magnetite (M2). Multiequilibrium thermobarometric calculations and P-T pseudosections calculated with THERMOCALC suggest granulite-facies conditions of ca. 13 kbar, 850°C and <7 kbar, 700-800°C for M1 and M2, respectively. In agreement with the qualitative information obtained from reaction textures and chemical zoning of minerals, this suggests an evolution dominated by decompression accompanied by moderate cooling. A Sm-Nd garnet - whole-rock age of 2.03 Ga determined on this sample indicates that this evolution occurred during the Palaeoproterozoic. We argue that from the geodynamic point of view the observed features are best explained by homogeneous thickening of the margin of the Archaean craton, re-heated and softened due to the accretion of hot, juvenile Palaeoproterozoic crust, as

  18. Improved Connector Shell for Cable Shields

    NASA Technical Reports Server (NTRS)

    Prisk, A. L.; Rotta, J. W., Jr.

    1983-01-01

    Cable connector shell improves electrostatic and electromagnetic shielding by electrically connecting cable braid around entire circumference. Connector cable braid is slipped over ferrule and sleeve is slipped over braid, clamping it tightly to shell. Connector shell completely shields cable conductors.

  19. Core-shell nanostructured catalysts.

    PubMed

    Zhang, Qiao; Lee, Ilkeun; Joo, Ji Bong; Zaera, Francisco; Yin, Yadong

    2013-08-20

    Novel nanotechnologies have allowed great improvements in the syn-thesis of catalysts with well-controlled size, shape, and surface properties. Transition metal nanostructures with specific sizes and shapes, for instance, have shown great promise as catalysts with high selectivities and relative ease of recycling. Researchers have already demonstrated new selective catalysis with solution-dispersed or supported-metal nanocatalysts, in some cases applied to new types of reactions. Several challenges remain, however, particularly in improving the structural stability of the catalytic active phase. Core-shell nanostructures are nanoparticles encapsulated and protected by an outer shell that isolates the nanoparticles and prevents their migration and coalescence during the catalytic reactions. The synthesis and characterization of effective core-shell catalysts has been at the center of our research efforts and is the focus of this Account. Efficient core-shell catalysts require porous shells that allow free access of chemical species from the outside to the surface of nanocatalysts. For this purpose, we have developed a surface-protected etching process to prepare mesoporous silica and titania shells with controllable porosity. In certain cases, we can tune catalytic reaction rates by adjusting the porosity of the outer shell. We also designed and successfully applied a silica-protected calcination method to prepare crystalline shells with high surface area, using anatase titania as a model system. We achieved a high degree of control over the crystallinity and porosity of the anatase shells, allowing for the systematic optimization of their photocatalytic activity. Core-shell nanostructures also provide a great opportunity for controlling the interaction among the different components in ways that might boost structural stability or catalytic activity. For example, we fabricated a SiO₂/Au/N-doped TiO₂ core-shell photocatalyst with a sandwich structure that showed

  20. Shell forming apparatus

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Granett, Dan (Inventor); Akutagawa, Wesley M. (Inventor)

    1987-01-01

    A nozzle assembly is described for use in a system that forms small gas-filled shells, which avoids the need for holding a miniature inner nozzle precisely concentric with a miniature outer nozzle. The outer nozzle has a diameter which is less than about 0.7 millimeter, which results in fluid passing through the nozzle having a progressively greater velocity at locations progressively further from the walls of the outer nozzle across most of the nozzle. This highly variable velocity profile automatically forces gas to the center of the outer nozzle. The end of the inner nozzle, which emits gas, is spaced upstream from the tip of the outer nozzle, to provide a distance along which to center the gas. This self-centering characteristic permits the inner nozzle to be positioned so its axis is not concentric with the axis of the outer nozzle.

  1. Composite shell spacecraft seat

    NASA Technical Reports Server (NTRS)

    Barackman, Victor J. (Inventor); Pulley, John K. (Inventor); Simon, Xavier D. (Inventor); McKee, Sandra D. (Inventor)

    2008-01-01

    A two-part seat (10) providing full body support that is specific for each crew member (30) on an individual basis. The two-part construction for the seat (10) can accommodate many sizes and shapes for crewmembers (30) because it is reconfigurable and therefore reusable for subsequent flights. The first component of the two-part seat construction is a composite shell (12) that surrounds the crewmember's entire body and is generically fitted to their general size in height and weight. The second component of the two-part seat (10) is a cushion (20) that conforms exactly to the specific crewmember's entire body and gives total body support in more complex environment.

  2. Leaving the Ivory Tower

    ERIC Educational Resources Information Center

    DeCarlo, Carmine

    2010-01-01

    It all began with casual conversation between a university supervisor and classroom teachers and approval to use an unused classroom at a local elementary school. The space became the hub of an exciting professional development (PD) opportunity for classroom teachers. This article describes how hosting an on-site university science methods course…

  3. Scaling the Ivory Tower

    ERIC Educational Resources Information Center

    Watson, Jamal Eric

    2011-01-01

    It used to be that newly minted Ph.D.s had to establish themselves and cut their academic teeth at less competitive colleges and universities. That was certainly true for young Black scholars. The prospects of landing a coveted teaching position at one of the nation's eight Ivy League institutions were dim. In the years leading up to the Civil…

  4. Ebony and Ivory

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image from the Mars Exploration Rover Opportunity's front hazard-avoidance camera focuses on a target called 'Goal 5.' Goal 5, examined during the 'Eagle Crater' soil survey, is a wind-rippled spot on the upper part of the crater , which the miniature thermal emission spectrometer shows is higher in hematite content compared to other soils within the crater. The light soil in the center of the image is referred to as 'Lanikai' -- an inspiration from the white sand beaches of Hawaii. The dark soil is referred to as 'Punaluu' after the black sand Hawaiian beaches.

  5. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Downs, R. L.; Ebner, M. A.; Nolen, R. L., Jr.

    1981-01-01

    Highly-uniform, hollow glass spheres (shells), which are used for inertial confinement fusion targets, were formed from metal-organic gel powder feedstock in a vertical furnace. As a result of the rapid pyrolysis caused by the furnace, the gel is transformed to a shell in five distinct stages: (a) surface closure of the porous gel; (b) generation of a closed-cell foam structure in the gel; (c) spheridization of the gel and further expansion of the foam; (d) coalescence of the closed-cell foam to a single-void shell; and (e) fining of the glass shell. The heat transfer from the furnace to the falling gel particle was modeled to determine the effective heating rate of the gel. The model predicts the temperature history for a particle as a function of mass, dimensions, specific heat, and absorptance as well as furnace temperature profile and thermal conductivity of the furnace gas. A model was developed that predicts the gravity-induced degradation of shell concentricity in falling molten shells as a function of shell characteristics and time.

  6. Crack problems in cylindrical and spherical shells

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1976-01-01

    Standard plate or shell theories were used as a starting point to study the fracture problems in thin-walled cylindrical and spherical shells, assuming that the plane of the crack is perpendicular to the surface of the sheet. Since recent studies have shown that local shell curvatures may have a rather considerable effect on the stress intensity factor, the crack problem was considered in conjunction with a shell rather than a plate theory. The material was assumed to be isotropic and homogeneous, so that approximate solutions may be obtained by approximating the local shell crack geometry with an ideal shell which has a solution, namely a spherical shell with a meridional crack, a cylindrical shell with a circumferential crack, or a cylindrical shell with an axial crack. A method of solution for the specially orthotropic shells containing a crack was described; symmetric and skew-symmetric problems are considered in cylindrical shells with an axial crack.

  7. Optimum rotationally symmetric shells for flywheel rotors

    SciTech Connect

    Blake, Henry W.

    2000-01-01

    A flywheel rim support formed from two shell halves. Each of the shell halves has a disc connected to the central shaft. A first shell element connects to the disc at an interface. A second shell element connects to the first shell element. The second shell element has a plurality of meridional slits. A cylindrical shell element connects to the second shell element. The cylindrical shell element connects to the inner surface of the flywheel rim. A flywheel rim support having a disc connected an outer diameter of a shaft. Two optimally shaped shell elements connect to the optimally shaped disc at an interface. The interface defines a discontinuity in a meridional slope of said support. A cylindrical shell element connects to the two shell elements. The cylindrical shell element has an outer surface for connecting to the inner surface of the flywheel rim. A flywheel rim casing includes an annular shell connected to the central shaft. The annular shell connects to the flywheel rim. A composite shell surrounds the shaft, annular shell and flywheel rim.

  8. MicroShell Minimalist Shell for Xilinx Microprocessors

    NASA Technical Reports Server (NTRS)

    Werne, Thomas A.

    2011-01-01

    MicroShell is a lightweight shell environment for engineers and software developers working with embedded microprocessors in Xilinx FPGAs. (MicroShell has also been successfully ported to run on ARM Cortex-M1 microprocessors in Actel ProASIC3 FPGAs, but without project-integration support.) Micro Shell decreases the time spent performing initial tests of field-programmable gate array (FPGA) designs, simplifies running customizable one-time-only experiments, and provides a familiar-feeling command-line interface. The program comes with a collection of useful functions and enables the designer to add an unlimited number of custom commands, which are callable from the command-line. The commands are parameterizable (using the C-based command-line parameter idiom), so the designer can use one function to exercise hardware with different values. Also, since many hardware peripherals instantiated in FPGAs have reasonably simple register-mapped I/O interfaces, the engineer can edit and view hardware parameter settings at any time without stopping the processor. MicroShell comes with a set of support scripts that interface seamlessly with Xilinx's EDK tool. Adding an instance of MicroShell to a project is as simple as marking a check box in a library configuration dialog box and specifying a software project directory. The support scripts then examine the hardware design, build design-specific functions, conditionally include processor-specific functions, and complete the compilation process. For code-size constrained designs, most of the stock functionality can be excluded from the compiled library. When all of the configurable options are removed from the binary, MicroShell has an unoptimized memory footprint of about 4.8 kB and a size-optimized footprint of about 2.3 kB. Since MicroShell allows unfettered access to all processor-accessible memory locations, it is possible to perform live patching on a running system. This can be useful, for instance, if a bug is

  9. Comparative study of shell swab and shell crush methods for the recovery of Salmonella from shell eggs.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swabbing (SW) is the standard methodology for the recovery of resident microorganisms from shell eggs in Japan. A comparative study of shell swab (SW) and a shell crush (CR) technique was performed to recover the laboratory-inoculated Salmonella from shell eggs. It was found that the recovery of ...

  10. K-shell and L-shell plasma spectroscopy experiments

    SciTech Connect

    Charatis, G. )

    1990-10-01

    Detailed atomic level populations in high temperature and dense plasmas have become increasingly important in laser generated plasmas. Certain spectral line intensity ratios are density-dependent while others are temperature-dependent. Both can be used to extract information concerning population kinetics and ion level populations. In order to be useful these dependencies must be characterized by independent means. In laser produced plasmas this can be done via holographic interferometry for electron density determinations and via the slope of the H-like free-bound continuum of K-shell lines for electron temperature determinations. The characterization of density- and temperature-dependent L-shell lines can be accomplished in ionization balance experiments in which laser irradiance is varied on targets which contain both K-shell and L-shell emitters. The K-shell free-bound continua provide the local temperature determination while holographic interferometry yields density profile information, from which the temperature and density dependent L-shell lines can be characterized. This paper discusses these concepts.

  11. Studies on Shell Formation

    PubMed Central

    Tsujii, Tadashi; Sharp, D. Gordon; Wilbur, Karl M.

    1958-01-01

    The submicroscopic structure of the growing surface of the shell of the oyster, Crassostrea virginica, was studied by means of shadowed replicas. The outer edge of the prismatic region consists of a fine grained matrix enclosing crystals, the surfaces of which show a finely pebbled structure. Crystal size varies continously from 0.01 µ to 8 µ. The matrix surface shows no evidence of fibrous structure. The outer portions of the prismatic region exhibit a tile-like arrangement of large crystals separated by granular matrix 0.02 to 0.08 µ in thickness. The exposed crystal surfaces have indentations of varying form which appear as roughly parallel grooves spaced at intervals of approximately 0.3 µ. The final form of this region is believed to result from the random distribution of crystal seeds, which grow without orientation and through coalescence and growth come into contact, producing polygonal areas. The crystal arrangement of the nacreous region is one of overlapping rows of crystals in side to side contact, and with one end of each crystal free, permitting continued increase in length. Crystal angles and plane indices are presented. PMID:13549498

  12. Insulative laser shell coupler

    DOEpatents

    Arnold, P.A.; Anderson, A.T.; Alger, T.W.

    1994-09-20

    A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dielectric break ring, and a pair of threaded ring sections is disclosed. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections. 4 figs.

  13. Insulative laser shell coupler

    DOEpatents

    Arnold, Phillip A.; Anderson, Andrew T.; Alger, Terry W.

    1994-01-01

    A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dialectric break ring, and a pair of threaded ring sections. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections.

  14. Recovery of Salmonella from commercial shell eggs by shell rinse and shell crush methodologies.

    PubMed

    Musgrove, M T; Jones, D R; Northcutt, J K; Harrison, M A; Cox, N A; Ingram, K D; Hinton, A J

    2005-12-01

    Salmonella is the most important human pathogen associated with shell eggs. Salmonella Enteritidis is the serotype most often implicated in outbreaks, although other serotypes have been recovered from eggs and from the commercial shell egg washing environment. Many sample methods are used to recover microorganisms from eggshells and membranes. A shell rinse and modified shell-and-membrane crush method for recovery of Salmonella were compared. Eggs were collected from 3 commercial shell-washing facilities (X, Y, and Z) during 3 visits. Twelve eggs were collected from each of 10 to 12 locations along the egg processing chain. After being transported back to the laboratory, each egg was sampled first by a shell rinse method and then by a shell crush method. For each technique (rinse or crush), 2 pools of 5 eggs per location sampled were selectively enriched for the recovery of Salmonella. Presumptive samples positive for Salmonella were confirmed serologically. Overall, there were 10.1% (40/396) Salmonella-positive pooled samples. Salmonella were recovered by the shell rinse and shell crush techniques (4.8 vs. 5.3%, respectively). Plant X yielded 21.5% Salmonella positives, whereas less than 5% of samples from plants Y and Z were found to be contaminated with the organism (4.2 and 4.5%, respectively). Salmonella was recovered more often from unwashed eggs (15.8%) than from washed eggs (8.3%). For some eggs, Salmonella was only recovered by one of the methods. Use of both approaches in the same experiment increased sampling sensitivity, although in most cases, crushing provided more sensitive Salmonella recovery. PMID:16479955

  15. Collapsing thin shells with rotation

    NASA Astrophysics Data System (ADS)

    Delsate, Térence; Rocha, Jorge V.; Santarelli, Raphael

    2014-06-01

    We construct exact solutions describing the motion of rotating thin shells in a fully backreacted five-dimensional rotating black hole spacetime. The radial equation of motion follows from the Darmois-Israel junction conditions, where both interior and exterior geometries are taken to be equal angular momenta Myers-Perry solutions. We show that rotation generates anisotropic pressures and momentum along the shell. Gravitational collapse scenarios including rotation are analyzed and a new class of stationary solutions is introduced. Energy conditions for the anisotropic matter shell are briefly discussed. We find that the weak energy condition is not violated for the collapse scenario where the shell starts at rest from infinity, nor for the new class of stationary solutions in anti-de Sitter. We further prove that the cosmic censorship conjecture is always satisfied in our setup.

  16. Shell Scores with Interactive Video.

    ERIC Educational Resources Information Center

    Zemke, Ron

    1991-01-01

    Documents Shell Oil's success with interactive video training (IVT) and identifies the costs involved in this long-term investment. Provides guidelines for judging the effectiveness of IVT programs. (SK)

  17. Intergalactic shells at large redshift

    NASA Technical Reports Server (NTRS)

    Shull, J. M.; Silk, J.

    1981-01-01

    The intergalactic shells produced by galactic explosions at large redshift, whose interiors cool by inverse Compton scattering off the cosmic background radiation, have a characteristic angular size of about 1 arcmin at peak brightness. At z values lower than 2, the shells typically have a radius of 0.5 Mpc, a velocity of about 50 km/sec, a metal abundance of about 0.0001 of cosmic values, and strong radiation in H I(Lyman-alpha), He II 304 A, and the IR fine-structure lines of C II and Si II. The predicted extragalactic background emission from many shells, strongly peaked toward the UV, sets an upper limit to the number of exploding sources at z values of about 10. Shell absorption lines of H I, C II, Si II, and Fe II, which may be seen at more recent epochs in quasar spectra, may probe otherwise invisible explosions in the early universe.

  18. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  19. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  20. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  1. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  2. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  3. Nematic textures in spherical shells

    NASA Astrophysics Data System (ADS)

    Vitelli, V.; Nelson, D. R.

    2006-08-01

    The equilibrium texture of nematic shells is studied as a function of their thickness. For ultrathin shells the ground state has four short (1)/(2) disclination lines but, as the thickness of the film increases, a three-dimensional escaped configuration composed of two pairs of half-hedgehogs becomes energetically favorable. We derive an exact solution for the nematic ground state in the one Frank constant approximation and study the stability of the corresponding texture against thermal fluctuations.

  4. Tri-soft shell technique.

    PubMed

    Arshinoff, Steve A; Norman, Richard

    2013-08-01

    Soft-shell techniques exist for lower viscosity dispersive with higher viscosity cohesive ophthalmic viscosurgical devices (OVDs) (soft-shell technique [SST]), viscoadaptive OVDs with balanced salt solution (ultimate soft-shell technique), intraoperative floppy-iris syndrome (soft-shell bridge), and many specific modifications for disinserted zonular fibers, frayed iris strands, Fuchs endothelial dystrophy, small holes in the posterior capsule with protruding vitreous, capsular dye use, and others. Soft-shell techniques exist because it is rheologically impossible to control the surgical environment with a single OVD as well as with an ordered combination of rheologically different OVDs. Surgeons frequently confuse these techniques because of their multitude. This paper unifies all SSTs into a single improved tri-soft shell technique (TSST), from which basic specific applications to unusual circumstances are simple and intuitive. As shown with previous SSTs, the TSST allows surgeons to perform complex tasks with greater surgical facility and to protect endothelial cells better than with single OVDs. PMID:23889867

  5. XPRT: An expert system shell

    SciTech Connect

    Cochrell, G.D.

    1988-09-01

    XPRT is a rule-based expert system shell written in the C programming language. This report contains a detailed description of the commands available in XPRT and also describes the syntax rules needed to construct a knowledge base. The shell's source code uses standard ANSI C, which allows it to run on any computer that can compile a C program. The executable code occupies 70K of PC memory. XPRT's inference engine can be commanded to backward chain or forward chain. Heuristics may be employed to reduce the search space of knowledge base rules. XPRT can read and write external files and spawn processes. The shell is mainly a symbolic processor but can handle numerical data as well. A mechanism of weighted facts and rules is used as an approach for handling uncertainty. XPRT is a no-frills shell with some very practical commands. The shell was used to write an expert system that is currently scheduling over a dozen software programs to maintain and manage a large departmental database. XPRT continues to evolve, and our organization is finding the shell to be a valuable programming tool. 6 refs.

  6. Paleoclimatic and deforestation effect on the chemical and isotopic composition of the coastal fresh groundwater resources of South-east Ivory Coast

    NASA Astrophysics Data System (ADS)

    Adiaffi, B.; Marlin, C.; Yei, O. M.-S.; Massault, M.; Noret, A.; Biemi, J.

    2009-04-01

    Since a half of century, the forest surface area of the South Ivory Coast has been decreased for the benefit of agriculture (15 000 km2 in 1993 versus 83 000 km2 in 1955-1958). This area also undergoes climate change. Vegetation cover has gradually changed from rainforests (C3 plants) to savanna (C4 plants) and agricultural plants. In the Abidjan area (5.00-6.00°N, 2.40-4.40°W), the mean rainfall amount and temperature value evolve during the 20th century (1912 mm/year and 26.3°C/year during the first decennial to 1613 mm/year and 26.9°C/year during the last ten years). The Paleoproterozoïc fractured bedrock (PB) and the Continental Terminal (CT) deposits groundwater are studied to show the climate change and deforestation effect on the area groundwater resources using stable isotopes (18O, 2H and 13C) contents, radiocarbon (14C) contents and chemical data on a set of 25 groundwater samples. The residence time of the groundwaters is estimated by the 14C using two models: (i) the model of well-mixed reservoir (WMR model) and (ii) the piston flow model (PF model). The range of the PB groundwater residence time (15 000 - 8 000 to ~ 300 - 100 a BP) for both models shows that the recharge has started at the beginning of the post-glacial period whereas the CT aquifer recharge is much more recent (from 300 a BP to today). The PB groundwater provides information about paleoclimatic conditions that occurred over the studied area during the late Pleistocene. It is demonstrated, through this study, that the evolution of vegetation cover (from forests to savanna and agriculture plants) is shown in groundwater by the trend in 13C content from old groundwater (confined bedrock groundwater: residence time of ~ 15 000 a BP) to the recent groundwater (unconfined bedrock groundwater and CT groundwater: residence times: ~ 300 a BP and lower than 100 a BP, respectively). The δ18O and δ2H values also increase with time from the beginning of the post-glacial period (~ 15 000 a BP

  7. Assessment of Mycotoxin Exposure in Côte d’ivoire (Ivory Coast) Through Multi-Biomarker Analysis and Possible Correlation with Food Consumption Patterns

    PubMed Central

    Kouadio, James Halbin; Lattanzio, Veronica M. T.; Ouattara, Djeneba; Kouakou, Brou; Visconti, Angelo

    2014-01-01

    Scope: The aim of the presented study was to investigate the mycotoxin exposure of Ivorian population related to the consumption patterns of maize, peanuts, millet, and cassava product (attiéké). Materials and Methods: Maize flour samples (n = 51) were purchased from all Abidjan local markets, in the south of Ivory Coast, and urine (n = 99) was collected during the same reference period (July–September 2011) from volunteers living in Abidjan and Daloa cities. Reversed-phase liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometry (LC-ESI-MS/MS) was used to analyze aflatoxins (AFB1, AFB2, AFG1, and AFG2), ochratoxin A (OTA), fumonisins (FB1, FB2), deoxynivalenol (DON), zearalenone (ZEA), and T-2 and HT-2 toxins in maize flour samples, and their relevant biomarkers (AFM1, DON, DON + de-epoxydeoxynivalenol (DOM-1), FB1, α-zearalenol (ZOL), β-ZOL, and OTA) in urine samples. Results: Critical maize contamination was observed by AFs occurrence (total AFs 4.5 – 330.0 μg/kg) while OTA was found in 13% of samples analyzed. AFM1 was detected in 40% of urines samples (0.06 – 14.11 ng/ml), OTA in 37% (0.01 – 0.42 ng/ml), FB1 in 27% (0.07 to 15.31 ng/ml) and, DON was found in 21% of samples at levels up to 10.0 ng/ml. The correlation coefficients (R2) obtained by plotting the percentage of biomarker occurrence (positive samples) versus the frequency of food consumption revealed maize, peanuts, millet and attiéké were strongly linked to AFB1 and OTA exposure with values of R2 ranged from 0.462 to 0.956. Conclusion: The present study provided data on mycotoxin risk in Ivory Coast, revealing a frequent co-exposure to the major mycotoxins such as AFs, OTA, and fumonisins, which appeared to be related to the frequency of peanuts, maize, millet and attiéké consumption. PMID:25948962

  8. Semiclassical environment of collapsing shells

    NASA Astrophysics Data System (ADS)

    Banerjee, Kinjal; Paranjape, Aseem

    2009-12-01

    We explore in detail the semiclassical environment of collapsing shells of matter, and determine the semiclassical flux measured by a variety of observers. This study is a preliminary step in a broader investigation of thermodynamic properties of the geometry of collapsing objects. Specifically, in this paper we consider spherically symmetric null and timelike collapsing shells which form an event horizon, and calculate the flux measured by observers both inside and outside the shell, and both inside and outside the event horizon, and find nontrivial results in most of the cases. Additionally, we also investigate the environment of a shell which collapses but does not form a horizon, halting at some radius larger than the Schwarzschild radius, and find that such an object generically gives rise to a pulse of radiation which is sharply peaked as it travels inwards and is reflected at the origin, and eventually emerges from the shell in a thermalized form. Our results have potential consequences in addressing questions pertaining, e.g. to black hole entropy and backreaction.

  9. Foam shell project: Progress report

    SciTech Connect

    Overturf, G.; Reibold, B.; Cook, B.; Schroen-Carey, D.

    1994-03-25

    The authors report on their work to produce a foam shell target for two possible applications: (1) as liquid-layered cryogenic target on Omega Upgrade, and (2) as a back-up design for the NIF. This target consists of a roughly 1 mm diameter and 100 {mu}m thick spherical low-density foam shell surrounding a central void. The foam will be slightly overfilled with liquid D{sub 2} or DT, the overfilled excess being symmetrically distributed on the inside of the shell and supported by thermal gradient techniques. The outside of the foam is overcoated with full density polymer which must be topologically smooth. The technology for manufacturing this style of foam shell involves microencapsulation techniques and has been developed by the Japanese at ILE. Their goal is to determine whether this technology can be successfully adapted to meet US ICF objectives. To this end a program of foam shell development has been initiated at LLNL in collaboration with both the General Atomics DOE Target Fabrication Contract Corporation and the Target Fabrication Group at LLE.

  10. Vibration of perforated cylindrical shells

    NASA Astrophysics Data System (ADS)

    Cousseau, Peter L.

    For a credible design of an inertial confinement fusion (ICF) target chamber, the vibration characteristics of the chamber must be completely understood. Target chambers are usually cylindrical or spherical in shape and contain hundreds of perforations (called ports) to allow access to the inside of the chamber. The fusion reaction within the chamber creates a uniform impulsive loading, which the chamber walls must be designed to contain. Also prior to an implosion, a delicate alignment process of the drivers and diagnostics takes place. The vibration of the chamber from rotating machinery, e.g., vacuum pumps, and ambient sources must be completely understood and accounted for during these alignment procedures. This dissertation examines the vibration characteristics of perforated cylindrical shells. Because the target chambers' thickness-to-radius ratio is small, such chambers can be modeled as thin shells. Included in the text is a literature review of perforated plates and shells and examples of the use of perforated structures in constructed and proposed ICF target chambers. The natural frequencies and corresponding mode shapes of perforated and unperforated cylindrical shells are studied analytically, numerically (via finite elements) and experimentally. Conclusions and comparisons between the different solution methods are made for both the perforated and unperforated cases. In addition, the dynamic response of perforated cylindrical shells to an axisymmetric impulsive loading has been identified. A demonstration showing how the convolution integral can be used to determine the response of a cylinder to a non-impulsive loading is presented.

  11. Statistical mechanics of thin spherical shells

    NASA Astrophysics Data System (ADS)

    Kosmrlj, Andrej; Nelson, David R.

    We explore how thermal fluctuations affect the mechanics of thin amorphous spherical shells via renormalization group calculations. It is well known that for flat solid membranes thermal fluctuations effectively increase the bending rigidity and reduce the bulk and shear moduli. This is still true for spherical shells. However, the additional coupling between the shell curvature, the local in-plane stretching modes and the local out-of-plane undulations leads to novel phenomena. In spherical shells thermal fluctuations effectively produce negative surface tension, which is equivalent to applying external pressure. We find that small spherical shells are stable, but for sufficiently large shells this thermally generated ``pressure'' becomes big enough to crush spherical shells. Such shells can be reinflated by increasing internal pressure, where the effective shell size grows non-linearly as a function of internal pressure with a power law exponent characteristic for thermally fluctuating flat membranes under uniform tension.

  12. [Assessment of a programme of prevention of mother-to-child transmission of HIV in Abidjan, Ivory Coast (1999-20002)].

    PubMed

    Coulibaly, M; Noba, V; Rey, J-L; Msellati, P; Ekpini, R; Chambon, J-F; Malkin, J-E

    2006-02-01

    The purpose of this article is to report the results of a programme for prevention of mother-to-child transmission (PMCT) of HIV conducted from 1999 to 2002 by the PNLS in Abidjan, Ivory Coast. This programme was supported by grants from the Fonds de solidarité international (FSTI) and the Glaxo Smith Kline (GSK) Foundation. After pre- and posttest counselling, pregnant women from 4 PMI centres underwent screening for HIV. Seropositive women were offered short course AZT and the possibility of financial assistance for breast-feeding. All programme activities were carried out in close cooperation with association members. A total of 22466 tests were given and 18116 women returned for results. Among the 1829 seropositive women to whom PMCT intervention was proposed, 667 received short course AZT. The rate of transmission at 18 months was 162%. In addition 69 mothers and 28 children eligible for ARV therapy benefited from tritherapy. Limiting factors, at each phase, and efficacy of intervention were analyzed. PMID:16615616

  13. Emissions and concentrations of hydrogen sulfide in the air of the tropical forest of the Ivory Coast and of temperate regions in France

    SciTech Connect

    Delmas, R.; Baudet, J.; Servant, J.; Baziard, Y.

    1980-08-20

    Atmospheric H/sub 2/S was measured by a fluorometric method (sensitivity 10 ng). In France, for aerated soils the emissions were between 0.8 and 27 ..mu..g m/sup -2/ h/sup -1/ H/sub 2/S (average 5 ..mu..g m/sup -2/ h/sup -1/). The soil temperature is an important factor governing this emission. The H/sub 2/S concentrations in the air ranged from 0.017 to 0.17 ..mu..g m/sup -3/ (average 0.080 ..mu..g m/sup -3/). In the Ivory Coast the H/sub 2/S emissions were estimated between 30 and 300 ..mu..g m/sup -2/ h/sup -1/. The measured concentrations of H/sub 2/S in the air at ground level ranged from 0.10 to 8.7 ..mu..g m/sup -3/. The relative importance of the measured emissions for anoxic soils of the humid equatorial forests in the global S cycle is discussed.

  14. Shell corrections in stopping powers

    NASA Astrophysics Data System (ADS)

    Bichsel, H.

    2002-05-01

    One of the theories of the electronic stopping power S for fast light ions was derived by Bethe. The algorithm currently used for the calculation of S includes terms known as the mean excitation energy I, the shell correction, the Barkas correction, and the Bloch correction. These terms are described here. For the calculation of the shell corrections an atomic model is used, which is more realistic than the hydrogenic approximation used so far. A comparison is made with similar calculations in which the local plasma approximation is utilized. Close agreement with the experimental data for protons with energies from 0.3 to 10 MeV traversing Al and Si is found without the need for adjustable parameters for the shell corrections.

  15. Asymptotic safety goes on shell

    NASA Astrophysics Data System (ADS)

    Benedetti, Dario

    2012-01-01

    It is well known in quantum field theory that the off-shell effective action depends on the gauge choice and field parametrization used in calculating it. Nevertheless, the typical scheme in which the scenario of asymptotically safe gravity is investigated is an off-shell version of the functional renormalization group equation. Working with the Einstein-Hilbert truncation as a test bed, we develop a new scheme for the analysis of asymptotically safe gravity in which the on-shell part of the effective action is singled out and we show that the beta function for the essential coupling has no explicit gauge dependence. In order to reach our goal, we introduce several technical novelties, including a different decomposition of the metric fluctuations, a new implementation of the ghost sector and a new cut-off scheme. We find a nontrivial fixed point, with a value of the cosmological constant that is independent of the gauge-fixing parameters.

  16. Chemical Analysis Of Beryllium Shells

    SciTech Connect

    Gunther, J; Cook, R

    2005-11-17

    There is a need to understand the level of high-Z impurities in Beryllium shells prepared by sputter coating. The Ignition Point Design Requirements state the following: ''Except for allowed ingredients, as listed in the ablator composition entries, the ablator material in all layers shall contain sufficiently low impurity levels that the sum over all impurities of atom fraction*Z{sup 2} shall be less than or equal to 0.2''. This is a tight specification that requires careful materials analysis. Early in the first quarter of FY06, we undertook a study of Be shell impurities via ICP-MS{sup 2} and determined that the impurity levels in the sputtered shells are very close to the specification.

  17. Shell model Monte Carlo methods

    SciTech Connect

    Koonin, S.E.; Dean, D.J.

    1996-10-01

    We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, thermal behavior of {gamma}-soft nuclei, and calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. 87 refs.

  18. Shell may expand detergent alcohols

    SciTech Connect

    1996-10-23

    Shell Chemical is studying plans to expand detergent alcohols capacity in the US, CW has learned. The company is considering adding capacity for about 80 million lbs/year. If the project is approved, it would be implemented at the company`s Geismar, LA site. Shell will make a final decision on whether to proceed with the project within six months. It has been rumored to be considering a capacity addition as a result of tightening supply of natural and synthetic detergent alcohols.

  19. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Nolen, R. L., Jr.; Ebner, M. A.; Downs, R. L.

    1980-01-01

    A heat transfer model was developed that mathematically describes the heating and calculates the thermal history of a gel particle in free-fall through the furnace. The model parameters that greatly affect the calculations were found to be gel particle mass, geometry, specific heat, and furnace gas. Empirical testing of the model has commenced. The code calculations and the initial empirical testing results both indicate that the gel-to-shell transformation occurs early and rapidly in the thermal history of the gel particle, and that for current work the heat transfer rate is not a limitation in shell production.

  20. On Closed Shells in Nuclei

    DOE R&D Accomplishments Database

    Mayer, M. G.

    1948-02-01

    It has been suggested in the past that special numbers of neutrons or protons in the nucleus form a particularly stable configuration.{sup1} The complete evidence for this has never been summarized, nor is it generally recognized how convincing this evidence is. That 20 neutrons or protons (Ca{sup40}) form a closed shell is predicted by the Hartree model. A number of calculations support this fact.{sup2} These considerations will not be repeated here. In this paper, the experimental facts indicating a particular stability of shells of 50 and 82 protons and of 50, 82, and 126 neutrons will be listed.

  1. The Shell-Model Code NuShellX@MSU

    SciTech Connect

    Brown, B.A.; Rae, W.D.M.

    2014-06-15

    Use of the code NuShellX@MSU is outlined. It connects to the ENSDF data files for automatic comparisons to energy level data. Operator overlaps provide predictions for spectroscopic factors, two-nucleon transfer amplitudes, nuclear moments, gamma decay and beta decay.

  2. Method and apparatus for an inflatable shell

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J. (Inventor)

    2012-01-01

    A method of assembling an inflatable shell of a structure comprises folding a plurality of shell sections about a set of fold lines and integrating the plurality of shell sections together with one another to form the shell. In another embodiment, an inflatable shell comprises a plurality of shell sections, each shell section having two pairs of fold lines for folding into stowage comprising a first gore section having a plurality of first gore panels layered and collectively folded about at a first set of fold lines. Each layer of the first gore panels and second gore panels are configured such that, once the first gore panel and second gore panel are attached to one another at the respective side edges of each panel, the lines of attachment forming a second set of fold lines for the shell section. A system and method for fabricating gore panels is also disclosed.

  3. Shell Games: Uncovering Periodic Properties.

    ERIC Educational Resources Information Center

    Lamb, William G.

    1983-01-01

    Describes activities (demonstrations/experiments) used to introduce history of periodic properties--without electrons, orbitals, filling shells, or any conception of atoms beyond Dalton's model. Activities supplement first chapter in a currently available chemistry text. Indicates potential danger of experiments if proper safety precautions are…

  4. Solutocapillary convection in spherical shells

    NASA Astrophysics Data System (ADS)

    Subramanian, Pravin; Zebib, Abdelfattah; McQuillan, Barry

    2005-01-01

    A linear stability study of solutocapillary driven Marangoni instabilities in small spherical shells is presented. The shells contain a binary fluid with an evaporating solvent. The viscosity is a strong function of the solvent concentration, the inner surface of the shell is assumed impermeable and stress free, while nonlinear boundary conditions are modeled and prescribed at the receding outer boundary. A time-dependent diffusive state is possible and may lose stability through the Marangoni mechanism due to surface tension dependence on solvent concentration (buoyant forces are negligible in this microscale problem). A frozen-time or quasisteady state linear stability analysis is performed to compute the critical Reynolds number and degree of surface harmonics, as well as the maximum growth rate of perturbations at specified parameters. The development of maximum growth rates in time was also computed by solving the initial value problem with random initial conditions. Results from both approaches are in good agreement except at short times where there is dependence on initial conditions. The physical problem models the manufacturing of spherical shells used as targets in inertial confinement fusion experiments where perfect sphericity is demanded for efficient fusion ignition. It is proposed that the Marangoni instability might be the source of observed surface roughness. Comparisons with the available experiments are made with reasonable qualitative and quantitative agreement.

  5. Shell structures for biogas plants

    SciTech Connect

    Sasse, L.

    1982-01-01

    The shell structures designed for biogas plants of the fixed-dome type by the Bremen Overseas Research and Development Association are described. Biogas digesters of the design described have been successfully tested in Rwanda and India without structural or contractural problems.

  6. Recent advances in shell theory. [application of asymptotic approach to thin walled shells

    NASA Technical Reports Server (NTRS)

    Simmonds, J. G.

    1976-01-01

    The results reviewed are divided into two categories: those that relate two-dimensional shell theory to three-dimensional elasticity theory and those concerned with shell theory per se. In the second category results for general elastic systems that carry over, by specialization or analogy, to shells and results that are unique to shell theory itself are considered.

  7. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  8. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  9. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  10. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  11. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds...

  12. Developments in Cylindrical Shell Stability Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Starnes, James H., Jr.

    1998-01-01

    Today high-performance computing systems and new analytical and numerical techniques enable engineers to explore the use of advanced materials for shell design. This paper reviews some of the historical developments of shell buckling analysis and design. The paper concludes by identifying key research directions for reliable and robust methods development in shell stability analysis and design.

  13. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  14. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  15. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  16. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  17. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  18. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ....2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a... Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT FRESH FRUITS, VEGETABLES AND OTHER PRODUCTS 1 2...

  19. Vibrations of cantilevered circular cylindrical shells Shallow versus deep shell theory

    NASA Technical Reports Server (NTRS)

    Lee, J. K.; Leissa, A. W.; Wang, A. J.

    1983-01-01

    Free vibrations of cantilevered circular cylindrical shells having rectangular planforms are studied in this paper by means of the Ritz method. The deep shell theory of Novozhilov and Goldenveizer is used and compared with the usual shallow shell theory for a wide range of shell parameters. A thorough convergence study is presented along with comparisons to previously published finite element solutions and experimental results. Accurately computed frequency parameters and mode shapes for various shell configurations are presented. The present paper appears to be the first comprehensive study presenting rigorous comparisons between the two shell theories in dealing with free vibrations of cantilevered cylindrical shells.

  20. Shell Model Depiction of Isospin Mixing in sd Shell

    SciTech Connect

    Lam, Yi Hua; Smirnova, Nadya A.; Caurier, Etienne

    2011-11-30

    We constructed a new empirical isospin-symmetry breaking (ISB) Hamiltonian in the sd(1s{sub 1/2}, 0d{sub 5/2} and 0d{sub 3/2}) shell-model space. In this contribution, we present its application to two important case studies: (i){beta}-delayed proton emission from {sup 22}Al and (ii) isospin-mixing correction to superallowed 0{sup +}{yields}0{sup +}{beta}-decay ft-values.

  1. Climate change sensitivity of the African ivory nut palm, Hyphaene petersiana Klotzsch ex Mart. (Arecaceae) - a keystone species in SE Africa

    NASA Astrophysics Data System (ADS)

    Blach-Overgaard, A.; Svenning, J.-C.; Balslev, H.

    2009-11-01

    Africa is the most vulnerable continent to future climate change. Profound changes are projected for southwestern Africa with increased drying, notably with delayed onset of the rainy season in September-November, and temperature increases in all seasons. The projected climate changes combined with land-use changes are thought to constitute the main threats to biodiversity in the 21st century. To be able to predict the potential impact on biodiversity, it is crucial to achieve a better insight into the controls of contemporary species ranges. Using species distribution modeling, we assessed the climate sensitivity of the key-stone palm species Hyphaene petersiana (African ivory nut palm) in southern Africa. We tested the relative roles of climate vs. non-climatic range-controls and found that climate had a clear effect on the range of H. petersiana and that especially water-related variables (annual precipitation and precipitation driest quarter) were of high importance. Nevertheless, latitude was the overall most dominant variable, reflecting spatial constraints on the continental-scale distribution. Of the remaining non-climatic factors, soil type and human influence were as important as the climatic factors. A future decrease in annual precipitation below 400 mm and hydrological changes towards drier conditions could cause a dramatic decline in H. petersiana populations, while the influence of temperature changes is less clear. The ongoing, unsustainable utilization pressures on this palm species by humans and livestock are likely to exacerbate the negative effect of future climate changes on its populations, especially, given the expected human population increase in Africa.

  2. On chaotic behavior of gravitating stellar shells.

    PubMed

    Barkov, M V; Bisnovatyi-Kogan, G S; Neishtadt, A I; Belinski, V A

    2005-03-01

    Motion of two gravitating spherical stellar shells around a massive central body is considered. Each shell consists of point particles with the same specific angular momenta and energies. In the case when one can neglect the influence of gravitation of one ("light") shell onto another ("heavy") shell ("restricted problem") the structure of the phase space is described. The scaling laws for the measure of the domain of chaotic motion and for the minimal energy of the light shell sufficient for its escape to infinity are obtained. PMID:15836258

  3. Pressure Shell Approach to Integrated Environmental Protection

    NASA Technical Reports Server (NTRS)

    Kennedy, Kriss J.

    2011-01-01

    The next generation of exploration mission human systems will require environmental protection such as radiation protection that is effective and efficient. In order to continue human exploration, habitat systems will require special shells to protect astronauts from hostile environments. The Pressure Shell Approach to integrated environmental (radiation) protection is a multi-layer shell that can be used for multifunctional environmental protection. Self-healing, self-repairing nano technologies and sensors are incorporated into the shell. This shell consists of multiple layers that can be tailored for specific environmental protection needs. Mainly, this innovation focuses on protecting crew from exposure to micrometeorites, thermal, solar flares, and galactic cosmic ray (GCR) radiation. The Pressure Shell Approach consists of a micrometeoroid and secondary ejecta protection layer; a thin, composite shell placed in between two layers that is non-structural; an open cavity layer that can be filled with water, regolith, or polyethylene foam; a thicker composite shell that is a structural load bearing that is placed between two layers; and a bladder coating on the interior composite shell. This multi-layer shell creates an effective radiation protection system. Most of its layers can be designed with the materials necessary for specific environments. In situ materials such as water or regolith can be added to the shell design for supplemental radiation protection.

  4. Turbine blade with spar and shell

    DOEpatents

    Davies, Daniel O.; Peterson, Ross H.

    2012-04-24

    A turbine blade with a spar and shell construction in which the spar and the shell are both secured within two platform halves. The spar and the shell each include outward extending ledges on the bottom ends that fit within grooves formed on the inner sides of the platform halves to secure the spar and the shell against radial movement when the two platform halves are joined. The shell is also secured to the spar by hooks extending from the shell that slide into grooves formed on the outer surface of the spar. The hooks form a serpentine flow cooling passage between the shell and the spar. The spar includes cooling holes on the lower end in the leading edge region to discharge cooling air supplied through the platform root and into the leading edge cooling channel.

  5. The shell coal gasification process

    SciTech Connect

    Koenders, L.O.M.; Zuideveld, P.O.

    1995-12-01

    Future Integrated Coal Gasification Combined Cycle (ICGCC) power plants will have superior environmental performance and efficiency. The Shell Coal Gasification Process (SCGP) is a clean coal technology, which can convert a wide range of coals into clean syngas for high efficiency electricity generation in an ICGCC plant. SCGP flexibility has been demonstrated for high-rank bituminous coals to low rank lignites and petroleum coke, and the process is well suited for combined cycle power generation, resulting in efficiencies of 42 to 46% (LHV), depending on choice of coal and gas turbine efficiency. In the Netherlands, a 250 MWe coal gasification combined cycle plant based on Shell technology has been built by Demkolec, a development partnership of the Dutch Electricity Generating Board (N.V. Sep). The construction of the unit was completed end 1993 and is now followed by start-up and a 3 year demonstration period, after that the plant will be part of the Dutch electricity generating system.

  6. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Nolen, R. L.; Downs, R. L.; Ebner, M. A.

    1982-01-01

    Highly-uniform, hollow glass spheres, which are used for inertial-confinement fusion targets, are formed from metal-organic gel powder feedstock in a drop-tower furnace. The modelling of this gel-to-sphere transformation has consisted of three phases: gel thermochemistry, furnance-to-gel heat transfer, and gravity-driven degradation of the concentricity of the molten shell. The heat transfer from the furnace to the free-falling gel particle was modelled with forced convection. The gel mass, dimensions, and specific heat as well as furnace temperature profile and furnace gas conductivity, were controlled variables. This model has been experimentally verified. In the third phase, a mathematical model was developed to describe the gravity-driven degradation of concentricity in molten glass shells.

  7. Atomic inner-shell transitions

    NASA Technical Reports Server (NTRS)

    Crasemann, B.; Chen, M. H.; Mark, H.

    1984-01-01

    Atomic inner-shell processes have quite different characteristics, in several important aspects, from processes in the optical regime. Energies are large, e.g., the 1s binding energy reaches 100 keV at Z = 87; relativistic and quantum-electrodynamic effects therefore are strong. Radiationless transitions vastly dominate over photon emission in most cases. Isolated inner-shell vacancies have pronounced single-particle character, with correlations generally contributing only approximately 1 eV to the 1s and 2p binding energies; the structure of such systems is thus well tractable by independent-particle self-consistent-field atomic models. For systems containing multiple deep inner-shell vacancies, or for highly stripped ions, the importance of relativistic intermediate coupling and configuration interaction becomes pronounced. Cancellation of the Coulomb interaction can lead to strong manifestations of the Breit interaction in such phenomena as multiplet splitting and hypersatellite X-ray shifts. Unique opportunities arise for the test of theory.

  8. Cracked shells under skew-symmetric loading

    NASA Technical Reports Server (NTRS)

    Lelale, F.

    1982-01-01

    A shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and antiplane elasticity solutions. Extensive results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform inplane shearing, out of plane shearing, and torsion. The effect of orthotropy on the results is also studied.

  9. Flow past a porous approximate spherical shell

    NASA Astrophysics Data System (ADS)

    Srinivasacharya, D.

    2007-07-01

    In this paper, the creeping flow of an incompressible viscous liquid past a porous approximate spherical shell is considered. The flow in the free fluid region outside the shell and in the cavity region of the shell is governed by the Navier Stokes equation. The flow within the porous annulus region of the shell is governed by Darcy’s Law. The boundary conditions used at the interface are continuity of the normal velocity, continuity of the pressure and Beavers and Joseph slip condition. An exact solution for the problem is obtained. An expression for the drag on the porous approximate spherical shell is obtained. The drag experienced by the shell is evaluated numerically for several values of the parameters governing the flow.

  10. SPSM and its application in cylindrical shells

    NASA Astrophysics Data System (ADS)

    Nie, Wu; Zhou, Su-Lian; Peng, Hui

    2008-03-01

    In naval architectures, the structure of prismatic shell is used widely. But there is no suitable method to analyze this kind of structure. Stiffened prismatic shell method (SPSM) presented in this paper, is one of the harmonic semi-analytic methods. Theoretically, strong stiffened structure can be analyzed economically and accurately. SPSM is based on the analytical solution of the governing differential equations for orthotropic cylindrical shells. In these differential equations, the torsional stiffness, bending stiffness and the exact position of each stiffener are taken into account with the Heaviside singular function. An algorithm is introduced, in which the actions of stiffeners on shells are replaced by external loads at each stiffener position. Stiffened shells can be computed as non-stiffened shells. Eventually, the displacement solution of the equations is acquired by the introduction of Green function. The stresses in a corrugated transverse bulkhead without pier base of an oil tanker are computed by using SPSM.

  11. Thermal stresses in thick laminated composite shells

    NASA Technical Reports Server (NTRS)

    Yuan, F. G.

    1993-01-01

    The paper provides an analytical formulation to investigate the thermomechanical behavior of thick composite shells subjected to a temperature distribution which varies arbitrarily in the radial direction. For illustrative purposes, shells under uniform temperature change are presented. It is found that thermal twist would occur even for symmetric laminated shells. Under uniform temperature rise, results for off-axis graphite/epoxy shells show that extensional-shear coupling can cause tensile radial stress throughout the shell and tensile hoop stress in the inner region. Laminated graphite/epoxy shells can exhibit negative effective thermal expansion coefficients in the longitudinal and transverse directions. Finally, the stacking sequence has a strong influence on the thermal stress distributions.

  12. Shell boosts recovery at Kernridge

    SciTech Connect

    Moore, S.

    1984-01-01

    Since acquiring the Kernridge property in December 1979, Shell Oil Co. has drilled more than 1,800 wells and steadily increased production from 42,000 to 89,000 b/d of oil. Currently, the Kernridge Production Division of Shell California Production Inc. (SCPI), a newly formed subsidiary of Shell Oil Co., is operator for the property. The property covers approximately 35,000 mostly contiguous net acres, with production concentrated mainly on about 5,500 net acres. SCPI's four major fields in the area are the North and South Belridge, Lost Hills, and Antelope Hills. Most of the production comes from the North and South Belridge fields, which were previously held by the Belridge Oil Co. Productive horizons in the fields are the Tulare, Diatomite, Brown Shale, Antelope Shale, 64 Zone, and Agua sand. The Tulare and Diatomite are the two major reservoirs SCPI is developing. The Tulare, encountered between 400 and 1,300 ft, is made up of fine- to coarse-grained, unconsolidated sands with interbedded shales and silt stones and contains 13 /sup 0/ API oil. Using steam drive as the main recovery method, SCPI estimates an ultimate recovery from the Tulare formation of about 60% of the original 1 billion barrels in place. The Diatomite horizon, found between 800 and 3,500 ft and containing light, 28 /sup 0/ API oil, has high porosity (more than 60%), low permeability (less than 1 md), and natural fractures. Because of the Diatomite's low permeability, fracture stimulation is being used to increase well productivity. SCPI anticipates that approximately 5% of the almost 2 billion barrels of oil originally in place will be recovered by primary production.

  13. Boson shells harboring charged black holes

    SciTech Connect

    Kleihaus, Burkhard; Kunz, Jutta; Laemmerzahl, Claus; List, Meike

    2010-11-15

    We consider boson shells in scalar electrodynamics coupled to Einstein gravity. The interior of the shells can be empty space, or harbor a black hole or a naked singularity. We analyze the properties of these types of solutions and determine their domains of existence. We investigate the energy conditions and present mass formulae for the composite black hole-boson shell systems. We demonstrate that these types of solutions violate black hole uniqueness.

  14. Monodisperse functional colloidosomes with tailored nanoparticle shells.

    PubMed

    Sander, J S; Studart, A R

    2011-04-01

    We report the assembly of monodisperse colloidosomes containing a wide range of functional nanoparticles in the outer shell using a double emulsion templating method in a microfluidic device. By selecting nanoparticles of specific functionalities, hollow capsules with inert, magnetic, photocatalytic, and potentially biocompatible and piezoelectric shells are easily obtained. Proper control over the surface chemistry of the nanoparticles forming the shell and of the liquid interfaces involved is key to enable the assembly of colloidosomes using this double emulsification route. PMID:21384846

  15. Electron Shell as a Resonator

    NASA Astrophysics Data System (ADS)

    Karpeshin, F. F.

    2002-11-01

    Main principles of the resonance effect arising in the electron shells in interaction of the nuclei with electromagnetic radiation are analyzed and presented in the historical aspect. Principles of NEET are considered from a more general position, as compared to how this is usually presented. Characteristic features of NEET and its reverse, TEEN, as internal conversion processes are analyzed, and ways are offered of inducing them by laser radiation. The ambivalent role of the Pauli exclusion principles in NEET and TEEN processes is investigated.

  16. The fragmentation of expanding shells - I. Limitations of the thin-shell approximation

    NASA Astrophysics Data System (ADS)

    Dale, James E.; Wünsch, Richard; Whitworth, Anthony; Palouš, Jan

    2009-09-01

    We investigate the gravitational fragmentation of expanding shells in the context of the linear thin-shell analysis. We make use of two very different numerical schemes; the FLASH adaptive mesh refinement code and a version of the Benz smoothed particle hydrodynamics code. We find that the agreement between the two codes is excellent. We use our numerical results to test the thin-shell approximation and we find that the external pressure applied to the shell has a strong effect on the fragmentation process. In cases where shells are not pressure-confined, the shells thicken as they expand and hydrodynamic flows perpendicular to the plane of the shell suppress fragmentation at short wavelengths. If the shells are pressure-confined internally and externally, so that their thickness remains approximately constant during their expansion, the agreement with the analytical solution is better.

  17. Thin-shell instability in collisionless plasma

    NASA Astrophysics Data System (ADS)

    Dieckmann, M. E.; Ahmed, H.; Doria, D.; Sarri, G.; Walder, R.; Folini, D.; Bret, A.; Ynnerman, A.; Borghesi, M.

    2015-09-01

    Thin-shell instability is one process which can generate entangled structures in astrophysical plasma on collisional (fluid) scales. It is driven by a spatially varying imbalance between the ram pressure of the inflowing upstream plasma and the downstream's thermal pressure at a nonplanar shock. Here we show by means of a particle-in-cell simulation that an analog process can destabilize a thin shell formed by two interpenetrating, unmagnetized, and collisionless plasma clouds. The amplitude of the shell's spatial modulation grows and saturates after about ten inverse proton plasma frequencies, when the shell consists of connected piecewise linear patches.

  18. Plans for Double Shell Experiments on NIF

    NASA Astrophysics Data System (ADS)

    Montgomery, D. S.; Daughton, W. S.; Gunderson, M. A.; Simakov, A. N.; Wilson, D. C.; Watt, R. G.; Kline, J. L.; Hayes, A. C.; Herrmann, H. W.; Boswell, M.; Danly, C. R.; Merrill, F. E.; Batha, S. H.; Amendt, P. A.; Milovich, J. L.; Robey, H. F.

    2015-11-01

    Double-shells are an alternative approach to achieving indirect drive ignition. These targets consist of a low-Z ablatively-driven outer shell that impacts a high-Z inner shell filled with DT fuel. In contrast to single-shell designs, double-shell targets burn the fuel via volume ignition, albeit with a lower gain. While double-shell capsules are complicated to fabricate, their design includes several beneficial metrics such as a low convergence pusher (C.R. < 10), low implosion speed (~ 250 km/s), a simple few-ns laser drive in a vacuum hohlraum, less sensitivity to hohlraum asymmetries, and low expected laser-plasma instabilities. We present preliminary double-shell capsule designs for NIF using a cryogenic gas DT fill which are optimized for yield and minimized for fall-line mix. Challenges will be discussed, as well as uncertainties and trade-offs in the physics issues compared to single-shells. A development path for double-shell experiments on NIF will be presented. Work performed under the auspices of DOE by LANL under contract DE-AC52-06NA25396.

  19. Core/shell colloidal semiconductor nanoplatelets.

    PubMed

    Mahler, Benoit; Nadal, Brice; Bouet, Cecile; Patriarche, Gilles; Dubertret, Benoit

    2012-11-14

    We have recently synthesized atomically flat semiconductor colloidal nanoplatelets with quasi 2D geometry. Here, we show that core/shell nanoplatelets can be obtained with a 2D geometry that is conserved. The epitaxial growth of the shell semiconductor is performed at room temperature. We report the detailed synthesis of CdSe/CdS and CdSe/CdZnS structures with different shell thicknesses. The shell growth is characterized both spectroscopically and structurally. In particular, the core/shell structure appears very clearly on high-resolution, high-angle annular dark-field transmission electron microscope images, thanks to the difference of atomic density between the core and the shell. When the nanoplatelets stand on their edge, we can precisely count the number of atomic planes forming the core and the shell. This provides a direct measurement, with atomic precision, of the core nanoplatelets thickness. The constraints exerted by the shell growth on the core is analyzed using global phase analysis. The core/shell nanoplatelets we obtained have narrow emission spectra with full-width at half-maximum close to 20 nm, and quantum yield that can reach 60%. PMID:23057684

  20. Fracture Mitigation Strategies in Gastropod Shells

    NASA Astrophysics Data System (ADS)

    Salinas, Christopher; Kisailus, David

    2013-04-01

    For hundreds of millions of years, gastropods have been evolving, modifying their external calcified shells for defense against shell-breaking and drilling predators. They have evolved primarily to use two different aragonitic microstructures: the evolutionary older Nacre (mother of pearl) structure and the more recently developed crossed-lamellar structure. By using both of these structures, gastropods are able to produce shells that are significantly tougher then geologic aragonite. However, the crossed-lamellar structure allows for a wider variety of shell morphologies, ensuring its increasing presence since the Mesozoic Marine Revolution more than 200 million years ago.

  1. Shell appraising deepwater discovery off Philippines

    SciTech Connect

    Scherer, M. ); Lambers, E.J.T.; Steffens, G.S. )

    1993-05-10

    Shell International Petroleum Co. Ltd. negotiated a farmout in 1990 from Occidental International Exploration and Production Co. for Block SC-38 in the South China Sea off Palawan, Philippines, following Oxy's discovery of gas in 1989 in a Miocene Nido limestone buildup. Under the terms of the farmout agreement, Shell became operator with a 50% share. Following the disappointing well North Iloc 1, Shell was successful in finding oil and gas in Malampaya 1. Water 700-1,000 m deep, remoteness, and adverse weather conditions have imposed major challenges for offshore operations. The paper describes the tectonic setting; the Nido limestone play; the Malampaya discovery; and Shell's appraisal studies.

  2. Carbon isotopes in mollusk shell carbonates

    NASA Astrophysics Data System (ADS)

    McConnaughey, Ted A.; Gillikin, David Paul

    2008-10-01

    Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod shell carbonates. Land snails construct their shells mainly from respired CO2, and shell δ13C reflects the local mix of C3 and C4 plants consumed. Shell δ13C is typically >10‰ heavier than diet, probably because respiratory gas exchange discards CO2, and retains the isotopically heavier HCO3 -. Respired CO2 contributes less to the shells of aquatic mollusks, because CO2/O2 ratios are usually higher in water than in air, leading to more replacement of respired CO2 by environmental CO2. Fluid exchange with the environment also brings additional dissolved inorganic carbon (DIC) into the calcification site. Shell δ13C is typically a few ‰ lower than ambient DIC, and often decreases with age. Shell δ13C retains clues about processes such as ecosystem metabolism and estuarine mixing. Ca2+ ATPase-based models of calcification physiology developed for corals and algae likely apply to mollusks, too, but lower pH and carbonic anhydrase at the calcification site probably suppress kinetic isotope effects. Carbon isotopes in biogenic carbonates are clearly complex, but cautious interpretation can provide a wealth of information, especially after vital effects are better understood.

  3. Material with core-shell structure

    DOEpatents

    Luhrs, Claudia; Richard, Monique N.; Dehne, Aaron; Phillips, Jonathan; Stamm, Kimber L.; Fanson, Paul T.

    2011-11-15

    Disclosed is a material having a composite particle, the composite particle including an outer shell and a core. The core is made from a lithium alloying material and the outer shell has an inner volume that is greater in size than the core of the lithium alloying material. In some instances, the outer mean diameter of the outer shell is less than 500 nanometers and the core occupies between 5 and 99% of the inner volume. In addition, the outer shell can have an average wall thickness of less than 100 nanometers.

  4. Transitional nuclei near shell closures

    SciTech Connect

    Mukherjee, G.

    2014-08-14

    High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.

  5. Lead behavior in abalone shell

    NASA Astrophysics Data System (ADS)

    Hirao, Yoshimitsu; Matsumoto, Akikazu; Yamakawa, Hiroshi; Maeda, Masaru; Kimura, Kan

    1994-08-01

    In order to gain information about the behavior of heavy metals in biological assimilation processes in a marine food chain and to investigate the possibility that lead pollution in a marine environment can be estimated by measurement of a small number of key materials from such a food chain, muscle and shell were analyzed from abalone ( Haliotis) from a shallow water locality in a Japanese coastal region. Lead concentrations in muscle were about 26 ppb for abalone of approximately 3 years old and decreased systematically with increasing age of animals sampled, to about 3.3 ppb for a specimen approximately 8 years old. Lead concentrations in shell material gradually decreased also, from 150 ppb to 82 ppb in the oldest specimen. The decrease of concentration in tissues with increasing age indicates that a mechanism for exclusion of lead during tissue growth becomes more efficient with age. Along the food chain in which abalone is the final stage, lead was enriched at the first stage, from seawater to algae, by a factor of 100. Lead was diminished at all subsequent stages of the chain. Tissue of artificially cultured abalone had four times higher lead values compared to abalone grown in natural conditions, and this appears to reflect the fact that lead concentration was three times higher in seawater in the cultured environment.

  6. Lead behavior in abalone shell

    SciTech Connect

    Hirao, Yoshimitsu; Matsumoto, Akikazu; Kimura, Kan ); Yamakawa, Hiroshi; Maeda, Masaru )

    1994-08-01

    In order to gain information about the behavior of heavy metals in biological assimilation processes in a marine food chain and to investigate the possibility that lead pollution in a marine environment can be estimated by measurement of a small number of key materials from such a food chain, muscle and shell were analyzed from abalone (Haliotis) from a shallow water locality in a Japanese coastal region. Lead concentrations in muscle were about 26 ppb for abalone approximately 3 years old and decreased systematically with increasing age of animals sampled, to about 3.3 ppb for a specimen approximately 8 years old. Lead concentrations in shell material gradually decreased also, from 150 ppb to 82 ppb in the oldest specimen. The decrease of concentration in tissues with increasing age indicates that a mechanism for exclusion of lead during tissue growth becomes more efficient with age. Along the food chain in which abalone is the final stage, lead was enriched at the first stage, from seawater to algae, by a factor of 100. Lead was diminished at all subsequent stages of the chain. Tissue of artificially cultured abalone had four times higher lead values compared to abalone grown in natural conditions, and this appears to reflect the fact that lead concentration was three times higher in seawater in the cultured environment.

  7. Apparatus and methods for installing, removing and adjusting an inner turbine shell section relative to an outer turbine shell section

    DOEpatents

    Leach, David; Bergendahl, Peter Allen; Waldo, Stuart Forrest; Smith, Robert Leroy; Phelps, Robert Kim

    2001-01-01

    A turbine includes upper and lower inner shell sections mounting the nozzles and shrouds and which inner shell is supported by pins secured to a surrounding outer shell. To disassemble the turbine for access to the inner shell sections and rotor, an alignment fixture is secured to the lower outer shell section and has pins engaging the inner shell section. To disassemble the turbine, the inner shell weight is transferred to the lower outer shell section via the alignment fixture and cradle pins. Roller assemblies are inserted through access openings vacated by support pins to permit rotation of the lower inner shell section out of and into the lower outer shell section during disassembly and assembly. The alignment fixture includes adjusting rods for adjusting the inner shell axially, vertically, laterally and about a lateral axis. A roller over-cage is provided to rotate the inner shell and a dummy shell to facilitate assembly and disassembly in the field.

  8. Layzer type models for pressure driven shells

    SciTech Connect

    Hurricane, O A

    2004-09-16

    Models for the nonlinear instability of finite thickness shells driven by pressure are constructed in the style of Layzer. Equations for both Cartesian and cylindrically convergent/divergent geometries are derived. The resulting equations are appropriate for incompressible shells with unity Atwood number. Predictions from the equations compare well with two-dimensional simulations.

  9. Isothermal Circumstellar Dust Shell Model for Teaching

    ERIC Educational Resources Information Center

    Robinson, G.; Towers, I. N.; Jovanoski, Z.

    2009-01-01

    We introduce a model of radiative transfer in circumstellar dust shells. By assuming that the shell is both isothermal and its thickness is small compared to its radius, the model is simple enough for students to grasp and yet still provides a quantitative description of the relevant physical features. The isothermal model can be used in a…

  10. A Well-Defined Bipolar Outflow Shell

    NASA Astrophysics Data System (ADS)

    Xie, Taoling; Goldsmith, Paul F.; Patel, Nimesh

    1992-12-01

    A well-defined "eggplant-shaped" thin shell is revealed in the Mon R2 central core region by CO and (13) CO J=1-0 maps obtained with QUARRY. This thin shell outlines the extended blue lobe of the massive bipolar outflow. The projected length and width of the shell are about 5.7 pc and 2.5 pc respectively, and the averaged projected thickness of the shell is ~ 0.3 pc. The shape of this shell can be satisfactorily accounted for quantitatively in terms of limb-brightening within the framework of the Shu et al shell model with radially directed wind, although the model seems to be oversimplified with respect to the complexity that our data reveal. The outflow shell's symmetry axis is estimated to be inclined by ~ 70(deg) with respect to the line of sight. We suggest that the coincident blue- and red-shifted emission and the bending of the red-shifted lobe are the result of the red-shifted shell being compressed, rather than having a second bipolar outflow aligned roughly perpendicular to the axis of the first bipolar outflow.

  11. Torsion and transverse sensing of conical shells

    NASA Astrophysics Data System (ADS)

    Li, H.; Chen, Z. B.; Tzou, H. S.

    2010-10-01

    Conical shells are widely used as payload/rocket adapters in rocket fairing systems. Generally, the conical shells are clamped at the major end and free at the minor end, where the payload is mounted. This study focuses on the dynamic sensing of conical shells with fix-free boundary conditions (BCs) by using distributed piezoelectric helical sensors. Two types of motion are studied, i.e., the transverse modes and the torsion modes. The shear-type sensors for shells sensing are presented first. Formulations of sensing signals of a general shell of revolution are presented, and then simplified to conical shells. For sensing of transverse vibrations, thin piezoelectric sensors are laminated on the top surface. Two types of sensor distribution are considered: a fully distributed and a helical or diagonal laminated. The total signal consists of four components resulting from the four strain components, and each of them is evaluated in detail. For sensing of torsion vibrations, a meridional polarized shear-type sensor with side electrodes is layered on the top surface of the shell structure. Sensing signals of natural shell modes are also evaluated. Analyses show that, in low order modes, the sensing signals induced by the circumferential membrane strains are the primary components of the total signal generations. The numerical results indicate the optimal location of the sensors. The proposed method is capable of determining the modal participation factors, while the testing signal is available; it is also capable of determining the mode shapes by using several distributed sensor segments.

  12. Thick-shell nanocrystal quantum dots

    SciTech Connect

    Hollingsworth, Jennifer A.; Chen, Yongfen; Klimov, Victor I.; Htoon, Han; Vela, Javier

    2011-05-03

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  13. A Geometric Theory of Nonlinear Morphoelastic Shells

    NASA Astrophysics Data System (ADS)

    Sadik, Souhayl; Angoshtari, Arzhang; Goriely, Alain; Yavari, Arash

    2016-08-01

    Many thin three-dimensional elastic bodies can be reduced to elastic shells: two-dimensional elastic bodies whose reference shape is not necessarily flat. More generally, morphoelastic shells are elastic shells that can remodel and grow in time. These idealized objects are suitable models for many physical, engineering, and biological systems. Here, we formulate a general geometric theory of nonlinear morphoelastic shells that describes both the evolution of the body shape, viewed as an orientable surface, as well as its intrinsic material properties such as its reference curvatures. In this geometric theory, bulk growth is modeled using an evolving referential configuration for the shell, the so-called material manifold. Geometric quantities attached to the surface, such as the first and second fundamental forms, are obtained from the metric of the three-dimensional body and its evolution. The governing dynamical equations for the body are obtained from variational consideration by assuming that both fundamental forms on the material manifold are dynamical variables in a Lagrangian field theory. In the case where growth can be modeled by a Rayleigh potential, we also obtain the governing equations for growth in the form of kinetic equations coupling the evolution of the first and the second fundamental forms with the state of stress of the shell. We apply these ideas to obtain stress-free growth fields of a planar sheet, the time evolution of a morphoelastic circular cylindrical shell subject to time-dependent internal pressure, and the residual stress of a morphoelastic planar circular shell.

  14. Microbial Populations Associated with Restricted Shell Eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Restricted shell eggs are found in all shell egg processing facilities. The manner with which companies handle them can vary greatly. In most cases, restricted eggs are diverted to further processing. Some facilities do not rewash eggs, choosing instead to include dirts in restricted eggs. Eggs ...

  15. Semiclassical shell structure in rotating Fermi systems

    SciTech Connect

    Magner, A. G.; Sitdikov, A. S.; Khamzin, A. A.; Bartel, J.

    2010-06-15

    The collective moment of inertia is derived analytically within the cranking model for any rotational frequency of the harmonic-oscillator potential well and at a finite temperature. Semiclassical shell-structure components of the collective moment of inertia are obtained for any potential by using the periodic-orbit theory. We found semiclassically their relation to the free-energy shell corrections through the shell-structure components of the rigid-body moment of inertia of the statistically equilibrium rotation in terms of short periodic orbits. The shell effects in the moment of inertia exponentially disappear with increasing temperature. For the case of the harmonic-oscillator potential, one observes a perfect agreement of the semiclassical and quantum shell-structure components of the free energy and the moment of inertia for several critical bifurcation deformations and several temperatures.

  16. Engineered Magnetic Core-Shell Structures.

    PubMed

    Alavi Nikje, Mir Mohammad; Vakili, Maryam

    2015-01-01

    In recent years, engineered magnetic core-shell structures are playing an important role in the wide range of various applications. These magnetic core-shell structures have attracted considerable attention because of their unique properties and various applications. Also, the synthesis of engineered magnetic core-shell structures has attracted practical interest because of potential applications in areas such as ferrofluids, medical imaging, drug targeting and delivery, cancer therapy, separations, and catalysis. So far a large number of engineered magnetic core-shell structures have been successfully synthesized. This review article focuses on the recent progress in synthesis and characterization of engineered magnetic core-shell structures. Also, this review gives a brief description of the various application of these structures. It is hoped that this review will play some small part in helping future developments in important field. PMID:26377655

  17. Electroformation of uranium hemispherical shells

    SciTech Connect

    Marshall, S.L.; Redey, L.; Vandegrift, G.F.; Vissers, D.R.

    1989-11-01

    This effort was directed at developing an electrochemical process for forming uniform and dendrite-free deposits of uranium from molten salts. This process is to be used for the electroformation of free-standing hemispherical shells of uranium for nuclear applications. Electrodeposition of uranium onto a substrate was accomplished with a fused chloride mixture containing 42 wt% UCl{sub 3} and a fused chloride-fluoride mixture containing 4 wt % UF{sub 4}. Under pulsed potential control at 504{degree}C, the chloride-fluoride mixture yielded the widest range of plating conditions for which dendrites could be avoided. Bipolar current pulse plating with both electrolytes gave good results, and successful application of this technique to a large tubular cathode has been demonstrated. 24 refs., 10 figs.

  18. The EOS TPC analysis shell

    SciTech Connect

    Olson, D.L.

    1991-03-01

    Key features of the general purpose event-based-data analysis shell (TAS) for the EOS TPC at LBL are described including the code development/code management procedures used. The architecture is designed with a view towards a distributed and multi-processing environment. TAS is interfaced seamlessly with the CERN PAW program and provides a consistent environment for both on-line and off-line analysis. The data model used is relational tables and the data structure definitions are maintained in a commercial database (INFORMIX). The interface for analysis modules is specified and enhances group participation in the development process. The use of commercial database as a data dictionary for both the table definitions and parameters used in the TAS kernel is extremely useful and productive. 6 refs., 4 figs.

  19. Faraday Wave Turbulence on a Spherical Liquid Shell

    NASA Astrophysics Data System (ADS)

    Holt, R. Glynn; Trinh, Eugene H.

    1996-08-01

    Millimeter-radius liquid shells are acoustically levitated in an ultrasonic field. Capillary waves are observed on the shells. At low energies (minimal acoustic amplitude, thick shell) a resonance is observed between the symmetric and antisymmetric thin film oscillation modes. At high energies (high acoustic pressure, thin shell) the shell becomes fully covered with high-amplitude waves. Temporal spectra of scattered light from the shell in this regime exhibit a power-law decay indicative of turbulence.

  20. Faraday Wave Turbulence on a Spherical Liquid Shell

    NASA Technical Reports Server (NTRS)

    Holt, R. Glynn; Trinh, Eugene H.

    1996-01-01

    Millimeter-radius liquid shells are acoustically levitated in an ultrasonic field. Capillary waves are observed on the shells. At low energies (minimal acoustic amplitude, thick shell) a resonance is observed between the symmetric and antisymmetric thin film oscillation modes. At high energies (high acoustic pressure, thin shell) the shell becomes fully covered with high-amplitude waves. Temporal spectra of scattered light from the shell in this regime exhibit a power-law decay indicative of turbulence.

  1. Comparison of somatic reversions between the ivory allele and transposon-caused mutant alleles at the white locus of Drosophila melanogaster after larval treatment with X rays and ethyl methanesulfonate

    SciTech Connect

    Ryo, H.; Yoo, M.A.; Fujikawa, K.; Kondo, S.

    1985-07-01

    Somatic reversion of strains with the ivory (wi) allele, a mutation associated with a tandem duplication of a DNA sequence at the white locus, increased with the age of larvae at the time of X-irradiation as expected from the increase in the number of target cells. In contrast, two independently isolated strains with unstable w+ loci associated with insertion of transposable elements showed higher reversion frequencies after treatment with X rays or ethyl methanesulfonate (EMS) at early larval stages than at late stages. Nevertheless, both the wi strain and the two unstable w+ strains reverted at nearly equal rates after treatment with X rays or EMS at early larval stages. Possible similarity in hot spot structure for the high reversibility of the two types of mutations is discussed in relation to production of presumed mutator-type cofactors specific to the transposon-caused mutations at early larval stages.

  2. Chemistry and processing of polymer shells

    NASA Astrophysics Data System (ADS)

    Alfonso, Emmanuel Limjuco

    The fabrication of high-quality spherical shells, used as fuel capsules in fusion experiments, is essential to the progress of the inertial confinement fusion program. Two types of shell were produced: (1) Polystyrene shells were made in a microencapsulation method. The yield, diameter, wall thickness, vacuole content, and surface finish were determined for shells prepared with an organic phase of toluene and 1,2-dichloroethane with polystyrene concentrations varied from 5 to 13 wt% and an internal water phase that sometimes contained surfactants. (2) Polyimide shells were made by vapor-phase deposition onto depolymerizable spherical mandrels. High-aspect-ratio polyimide shells with diameters ranging from 700 to 1000 mum and wall thicknesses from 2 to 13 mum have been fabricated. Estimates of the composition, surface roughness, burst and buckle pressures, elastic modulus, tensile strength, permeability, and film stress have been obtained. These shells have been characterized in terms of morphological properties: the shell dimensions (diameter and wall thickness), sphericity, wall structure, outer and inner surface finish, and transparency. The structure of the outer surface and wall cross section varied strongly with the processing conditions (e.g., deposition temperatures, system pressure), while the inner surface was shown to be very smooth. The transparency of near-stoichiometric polyimide shells and flat films was demonstrated. Rutherford backscattering and nuclear resonance analysis techniques were used to provide the elemental composition and density, which were very near the theoretical values. Polyimide shells' minimum tensile strengths and moduli were determined from burst and buckle pressure tests. The tensile strength approached that reported for Kapton-HN film. The elastic moduli varied with processing conditions. The vapor-deposited polyimide was found to possess mechanical strength properties similar to commercially available polyimides. The room

  3. Probabilistic Dynamic Buckling of Smart Composite Shells

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Abumeri, Galib H.

    2007-01-01

    A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of intraply hybrid composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right next to the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10% at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

  4. Probabilistic Dynamic Buckling of Smart Composite Shells

    NASA Technical Reports Server (NTRS)

    Abumeri, Galib H.; Chamis, Christos C.

    2003-01-01

    A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right below the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10 percent at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

  5. Photon upconversion in core-shell nanoparticles.

    PubMed

    Chen, Xian; Peng, Denfeng; Ju, Qiang; Wang, Feng

    2015-03-21

    Photon upconversion generally results from a series of successive electronic transitions within complex energy levels of lanthanide ions that are embedded in the lattice of a crystalline solid. In conventional lanthanide-doped upconversion nanoparticles, the dopant ions homogeneously distributed in the host lattice are readily accessible to surface quenchers and lose their excitation energy, giving rise to weak and susceptible emissions. Therefore, present studies on upconversion are mainly focused on core-shell nanoparticles comprising spatially confined dopant ions. By doping upconverting lanthanide ions in the interior of a core-shell nanoparticle, the upconversion emission can be substantially enhanced, and the optical integrity of the nanoparticles can be largely preserved. Optically active shells are also frequently employed to impart multiple functionalities to upconversion nanoparticles. Intriguingly, the core-shell design introduces the possibility of constructing novel upconversion nanoparticles by exploiting the energy exchange interactions across the core-shell interface. In this tutorial review, we highlight recent advances in the development of upconversion core-shell nanoparticles, with particular emphasis on the emerging strategies for regulating the interplay of dopant interactions through core-shell nanostructural engineering that leads to unprecedented upconversion properties. The improved control over photon energy conversion will open up new opportunities for biological and energy applications. PMID:25058157

  6. Geographical variation in shell shape of the pod razor shell Ensis siliqua (Bivalvia: Pharidae)

    NASA Astrophysics Data System (ADS)

    Rufino, Marta M.; Vasconcelos, Paulo; Pereira, Fábio; Fernández-Tajes, Juan; Darriba, Susana; Méndez, Josefina; Gaspar, Miguel B.

    2013-03-01

    The present study assessed the existence of variation in the shell shape of the pod razor shell ( Ensis siliqua) throughout its distributional range in the north-eastern Atlantic. Shells of E. siliqua caught at seven collecting sites (three in Portugal, three in Spain and one in Ireland) were studied by geometric morphometric methods, using both landmark- and contour-based methods. Both approaches (landmarks inside the valves and shell outline) discriminated the shells from Aveiro (centre of Portugal) and Strangford Lough (Ireland) from those caught in the nearby localities (remaining Portuguese and Spanish sites, maximum distance of 550 km by sea). Landmark analysis revealed that shells from Aveiro were more similar to shells from Ireland (~1,500 km far away). Contour analysis revealed that shells from Aveiro had a shape with a comparatively larger height-to-width ratio, whereas shells from Ireland showed a slightly more curved outline than in the remaining sites. Landmark- and contour-based methods provided coherent complementary information, confirming the usefulness of geometric morphometric analyses for discerning differences in shell shape among populations of E. siliqua. A brief review of previous applications of geometric morphometric methods to modern bivalve species is also provided.

  7. A comparison of shell theories for large-amplitude vibrations of circular cylindrical shells: Lagrangian approach

    NASA Astrophysics Data System (ADS)

    Amabili, M.

    2003-07-01

    Large-amplitude (geometrically non-linear) vibrations of circular cylindrical shells subjected to radial harmonic excitation in the spectral neighbourhood of the lowest resonances are investigated. The Lagrange equations of motion are obtained by an energy approach, retaining damping through Rayleigh's dissipation function. Four different non-linear thin shell theories, namely Donnell's, Sanders-Koiter, Flügge-Lur'e-Byrne and Novozhilov's theories, which neglect rotary inertia and shear deformation, are used to calculate the elastic strain energy. The formulation is also valid for orthotropic and symmetric cross-ply laminated composite shells. The large-amplitude response of perfect and imperfect, simply supported circular cylindrical shells to harmonic excitation in the spectral neighbourhood of the lowest natural frequency is computed for all these shell theories. Numerical responses obtained by using these four non-linear shell theories are also compared to results obtained by using the Donnell's non-linear shallow-shell equation of motion. A validation of calculations by comparison with experimental results is also performed. Both empty and fluid-filled shells are investigated by using a potential fluid model. The effects of radial pressure and axial load are also studied. Boundary conditions for simply supported shells are exactly satisfied. Different expansions involving from 14 to 48 generalized co-ordinates, associated with natural modes of simply supported shells, are used. The non-linear equations of motion are studied by using a code based on an arclength continuation method allowing bifurcation analysis.

  8. The Ivory Tower Under Siege.

    ERIC Educational Resources Information Center

    Smith-Mello, Michal

    Increasing public dissatisfaction with the cost and quality of higher education is creating pressure for fundamental change. Higher education is not as certain to produce a higher standard of living as it used to be, and costs are rising faster than the rate of inflation. Declining state contributions to higher education have shifted the financial…

  9. Alone in the Ivory Tower

    ERIC Educational Resources Information Center

    Wolfinger, Nicholas H.; Goulden, Marc; Mason, Mary Ann

    2010-01-01

    The authors use data from the 2000 Census Public Use Microdata Sample to examine the likelihood of a birth event, defined as the household presence of a child younger than 2 years, for male and female professionals. Physicians have the highest rate of birth events, followed in order by attorneys and academics. Within each profession men have more…

  10. Caring in the Ivory Tower

    ERIC Educational Resources Information Center

    O'Brien, Leigh M.

    2010-01-01

    In this paper I argue that the teacher educators who deliberately create and nurture caring teacher-student relationships, despite the many challenges, benefit both themselves and their students in several ways. Although the notion that teachers should care for their students is not new, it may well be that professors too seldom "communicate"…

  11. Color fields on the light-shell

    NASA Astrophysics Data System (ADS)

    Georgi, Howard; Kestin, Greg; Sajjad, Aqil

    2016-02-01

    We study the classical color radiation from very high energy collisions that produce colored particles. In the extreme high energy limit, the classical color fields are confined to a light-shell expanding at c and are associated with a non-linear σ-model on the 2D light-shell with specific symmetry breaking terms. We argue that the quantum version of this picture exhibits asymptotic freedom and may be a useful starting point for an effective light-shell theory of the structure between the jets at a very high energy collider.

  12. On the vibration of axisymmetric shells

    NASA Astrophysics Data System (ADS)

    Heppler, G. R.; Wahl, L.

    1989-05-01

    The application of nonconventional basis functions to the linear vibration problem is explored. By employing shell coordinates the elements allow the exact geometrical modelling of shells of revolution with arbitrary meridians and the elements are able to reproduce strain free states under an arbitrary rigid body motion due to the use of these special basis functions. A generalization of the Reissner Mindlin plate theories is used because they have a broader range of applicability than the usual thin/shallow shell theories and also the trial functions need only be of class C(sup 0). The geometry treated is a hyperbola of revolution, in two configurations.

  13. Thermoluminescence analysis of irradiated oyster shells.

    PubMed

    Cruz-Zaragoza, E; Marcazzó, J; Della Monaca, S; Boniglia, C; Gargiulo, R; Bortolin, E

    2012-12-01

    This paper reports the thermoluminescence (TL) analysis performed on the oyster shells powder. TL response of (60)Co gamma-rays irradiated samples were studied in the range from 80 Gy to 8 kGy doses. TL signal of irradiated shell powder was higher as compared to the unirradiated control samples, which allowed to identify the irradiated oysters. Results show that the oyster shells have good TL properties and can be useful for the identification of irradiated seafood as well as for the evaluation of the treatment dose. PMID:22341648

  14. The off-shell c-map

    NASA Astrophysics Data System (ADS)

    Banerjee, Nabamita; de Wit, Bernard; Katmadas, Stefanos

    2016-01-01

    The off-shell version of the c-map is presented, based on a systematic off-shell reduction from four to three space-time dimensions for supergravity theories with eight supercharges. In the reduction, the R-symmetry group is enhanced to local [SU(2)× SU(2)]/{{Z}}_2=SO(4) and the c-map is effected by a parity transformation in the internal space that interchanges the two SU(2) factors. Vector and tensor supermultiplets are each others conjugate under the c-map and both can be dualized in three dimensions to (on-shell) hypermultiplets.

  15. Photon propagator in light-shell gauge

    NASA Astrophysics Data System (ADS)

    Georgi, Howard; Kestin, Greg; Sajjad, Aqil

    2016-05-01

    We derive the photon propagator in light-shell gauge (LSG) vμAμ=0 , where vμ=(1,r ^ ) μ . This gauge is an important ingredient of the light-shell effective theory—an effective theory for describing high energy jet processes on a 2-dimensional spherical shell expanding at the speed of light around the point of the initial collision producing the jets. Since LSG is a noncovariant gauge, we cannot calculate the LSG propagator by using the standard procedure for covariant gauges. We therefore employ a new technique for computing the propagator, which we hope may be of relevance in other gauges as well.

  16. Laminated anisotropic reinforced plastic plates and shells

    NASA Technical Reports Server (NTRS)

    Korolev, V. I.

    1981-01-01

    Basic technical theories and engineering calculation equations for anisotropic plates and shells made of rigid reinforced plastics, mainly laminated fiberglass, are presented and discussed. Solutions are given for many problems of design of structural plates and shells, including curved sections and tanks, as well as two chapters on selection of the optimum materials, are given. Accounting for interlayer shearing and transverse separation, which are new engineering properties, are discussed. Application of the results obtained to thin three ply plates and shells wth a light elastic filler is presented and discussed.

  17. Synthesis of stiffened shells of revolution

    NASA Technical Reports Server (NTRS)

    Thornton, W. A.

    1974-01-01

    Computer programs for the synthesis of shells of various configurations were developed. The conditions considered are: (1) uniform shells (mainly cones) using a membrane buckling analysis, (2) completely uniform shells (cones, spheres, toroidal segments) using linear bending prebuckling analysis, and (3) revision of second design process to reduce the number of design variables to about 30 by considering piecewise uniform designs. A perturbation formula was derived and this allows exact derivatives of the general buckling load to be computed with little additional computer time.

  18. Vacuum energy of a spherical plasma shell

    SciTech Connect

    Bordag, M.; Khusnutdinov, N.

    2008-04-15

    We consider the vacuum energy of the electromagnetic field interacting with a spherical plasma shell together with a model for the classical motion of the shell. We calculate the heat kernel coefficients, especially that for the TM mode, and carry out the renormalization by redefining the parameters of the classical model. It turns out that this is possible and results in a model which, in the limit of the plasma shell becoming an ideal conductor, reproduces the vacuum energy found by Boyer in 1968.

  19. Gross shell structure of moments of inertia

    SciTech Connect

    Deleplanque, M.A.; Frauendorf, S.; Pashkevich, V.V.; Chu, S.Y.; Unzhakova, A.

    2002-07-01

    Average yrast moments of inertia at high spins, where the pairing correlations are expected to be largely absent, were found to deviate from the rigid-body values. This indicates that shell effects contribute to the moment of inertia. We discuss the gross dependence of moments of inertia and shell energies on the neutron number in terms of the semiclassical periodic orbit theory. We show that the ground-state shell energies, nuclear deformations and deviations from rigid-body moments of inertia are all due to the same periodic orbits.

  20. Magnetic-Plasmonic Core-Shell Nanoparticles

    PubMed Central

    Levin, Carly S.; Hofmann, Cristina; Ali, Tamer A.; Kelly, Anna T.; Morosan, Emilia; Nordlander, Peter; Whitmire, Kenton H.; Halas, Naomi J.

    2013-01-01

    Nanoparticles composed of magnetic cores with continuous Au shell layers simultaneously possess both magnetic and plasmonic properties. Faceted and tetracubic nanocrystals consisting of wüstite with magnetite-rich corners and edges retain magnetic properties when coated with an Au shell layer, with the composite nanostructures showing ferrimagnetic behavior. The plasmonic properties are profoundly influenced by the high dielectric constant of the mixed-iron-oxide nanocrystalline core. A comprehensive theoretical analysis that examines the geometric plasmon tunability over a range of core permittivities enables us to identify the dielectric properties of the mixed-oxide magnetic core directly from the plasmonic behavior of the core-shell nanoparticle. PMID:19441794

  1. THE PYTHON SHELL FOR THE ORBIT CODE

    SciTech Connect

    Shishlo, Andrei P; Gorlov, Timofey V; Holmes, Jeffrey A

    2009-01-01

    A development of a Python driver shell for the ORBIT simulation code is presented. The original ORBIT code uses the SuperCode shell to organize accelerator-related simulations. It is outdated, unsupported, and it is an obstacle to future code development. The necessity and consequences of replacing the old shell language are discussed. A set of core modules and extensions that are currently in PyORBIT are presented. They include particle containers, parsers for MAD and SAD lattice files, a Python wrapper for MPI libraries, space charge calculators, TEAPOT trackers, and a laser stripping extension module.

  2. Effective Interactions from No Core Shell Model

    SciTech Connect

    Dikmen, E.; Lisetskiy, A. F.; Barrett, B. R.; Navratil, P.; Vary, J. P.

    2008-11-11

    We construct the many-body effective Hamiltonian for pf-shell by carrying out 2({Dirac_h}/2{pi}){omega}. NCSM calculations at the 2-body cluster level. We demonstrate how the effective Hamiltonian derived from realistic nucleon-nucleon (NN) potentials for the 2({Dirac_h}/2{pi}){omega} NCSM space should be modified to properly account for the many-body correlations produced by truncating to the major pf-shell. We obtain two-body effective interactions for the pf-shell by using direct projection and use them to reproduce the results of large scale NCSM for other light Ca isotopes.

  3. Comparison on pore development of activated carbon produced from palm shell and coconut shell.

    PubMed

    Daud, Wan Mohd Ashri Wan; Ali, Wan Shabuddin Wan

    2004-05-01

    A series of experiments were conducted to compare the pore development in palm-shell and coconut-shell-based activated carbons produced under identical experimental conditions. Carbonization and activation processes were carried out at 850 degrees C using a fluidized bed reactor. Within the range of burn-off studied, at any burn-off, the micropore and mesopore volumes created in palm-shell-based activated carbon were always higher than those of coconut-shell-based activated carbon. On macropore volume, for palm-shell-based activated carbon, the volume increased with increase in burn-off up to 30% and then decreased. However, for coconut-shell-based activated carbon, the change in macropore volume with burn-off was almost negligible but the absolute macropore volume decreased with burn-off. PMID:14987722

  4. Membrane Shell Reflector Segment Antenna

    NASA Technical Reports Server (NTRS)

    Fang, Houfei; Im, Eastwood; Lin, John; Moore, James

    2012-01-01

    The mesh reflector is the only type of large, in-space deployable antenna that has successfully flown in space. However, state-of-the-art large deployable mesh antenna systems are RF-frequency-limited by both global shape accuracy and local surface quality. The limitations of mesh reflectors stem from two factors. First, at higher frequencies, the porosity and surface roughness of the mesh results in loss and scattering of the signal. Second, the mesh material does not have any bending stiffness and thus cannot be formed into true parabolic (or other desired) shapes. To advance the deployable reflector technology at high RF frequencies from the current state-of-the-art, significant improvements need to be made in three major aspects: a high-stability and highprecision deployable truss; a continuously curved RF reflecting surface (the function of the surface as well as its first derivative are both continuous); and the RF reflecting surface should be made of a continuous material. To meet these three requirements, the Membrane Shell Reflector Segment (MSRS) antenna was developed.

  5. Sensitivity and Uncertainty Analysis Shell

    Energy Science and Technology Software Center (ESTSC)

    1999-04-20

    SUNS (Sensitivity and Uncertainty Analysis Shell) is a 32-bit application that runs under Windows 95/98 and Windows NT. It is designed to aid in statistical analyses for a broad range of applications. The class of problems for which SUNS is suitable is generally defined by two requirements: 1. A computer code is developed or acquired that models some processes for which input is uncertain and the user is interested in statistical analysis of the outputmore » of that code. 2. The statistical analysis of interest can be accomplished using the Monte Carlo analysis. The implementation then requires that the user identify which input to the process model is to be manipulated for statistical analysis. With this information, the changes required to loosely couple SUNS with the process model can be completed. SUNS is then used to generate the required statistical sample and the user-supplied process model analyses the sample. The SUNS post processor displays statistical results from any existing file that contains sampled input and output values.« less

  6. Shape Transformations of Epithelial Shells.

    PubMed

    Misra, Mahim; Audoly, Basile; Kevrekidis, Ioannis G; Shvartsman, Stanislav Y

    2016-04-12

    Regulated deformations of epithelial sheets are frequently foreshadowed by patterning of their mechanical properties. The connection between patterns of cell properties and the emerging tissue deformations is studied in multiple experimental systems, but the general principles remain poorly understood. For instance, it is in general unclear what determines the direction in which the patterned sheet is going to bend and whether the resulting shape transformation will be discontinuous or smooth. Here these questions are explored computationally, using vertex models of epithelial shells assembled from prismlike cells. In response to rings and patches of apical cell contractility, model epithelia smoothly deform into invaginated or evaginated shapes similar to those observed in embryos and tissue organoids. Most of the observed effects can be captured by a simpler model with polygonal cells, modified to include the effects of the apicobasal polarity and natural curvature of epithelia. Our models can be readily extended to include the effects of multiple constraints and used to describe a wide range of morphogenetic processes. PMID:27074691

  7. Oyster Shell Proteins Originate from Multiple Organs and Their Probable Transport Pathway to the Shell Formation Front

    PubMed Central

    Zhu, Yabing; Du, Yishuai; Song, Xiaorui; Chen, Yuanxin; Huang, Ronglian; Que, Huayong; Fang, Xiaodong; Zhang, Guofan

    2013-01-01

    Mollusk shell is one kind of potential biomaterial, but its vague mineralization mechanism hinders its further application. Mollusk shell matrix proteins are important functional components that are embedded in the shell, which play important roles in shell formation. The proteome of the oyster shell had been determined based on the oyster genome sequence by our group and gives the chance for further deep study in this area. The classical model of shell formation posits that the shell proteins are mantle-secreted. But, in this study, we further analyzed the shell proteome data in combination with organ transcriptome data and we found that the shell proteins may be produced by multiple organs though the mantle is still the most important organ for shell formation. To identify the transport pathways of these shell proteins not in classical model of shell formation, we conducted a shell damage experiment and we determined the shell-related gene set to identify the possible transport pathways from multiple organs to the shell formation front. We also found that there may exist a remodeling mechanism in the process of shell formation. Based on these results along with some published results, we proposed a new immature model, which will help us think about the mechanism of shell formation in a different way. PMID:23840499

  8. Shell deformation studies using holographic interferometry

    NASA Technical Reports Server (NTRS)

    Parmerter, R. R.

    1974-01-01

    The buckling of shallow spherical shells under pressure has been the subject of many theoretical and experimental papers. Experimental data above the theoretical buckling load of Huang have given rise to speculation that shallow shell theory may not adequately predict the stability of nonsymmetric modes in higher-rise shells which are normally classified as shallow by the Reissner criterion. This article considers holographic interferometry as a noncontact, high-resolution method of measuring prebuckling deformations. Prebuckling deformations of a lambda = 9, h/b = 0.038 shell are Fourier-analyzed. Buckling is found to occur in an N = 5 mode as predicted by Huang's theory. The N = 4 mode was unusually stable, suggesting that even at this low value of h/b, stabilizing effects may be at work.

  9. Wireless energy transfer between anisotropic metamaterials shells

    SciTech Connect

    Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José

    2014-06-15

    The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted.

  10. Nuclear Quadrupole Moments and Nuclear Shell Structure

    DOE R&D Accomplishments Database

    Townes, C. H.; Foley, H. M.; Low, W.

    1950-06-23

    Describes a simple model, based on nuclear shell considerations, which leads to the proper behavior of known nuclear quadrupole moments, although predictions of the magnitudes of some quadrupole moments are seriously in error.

  11. On the Calculation of Shallow Shells

    NASA Technical Reports Server (NTRS)

    Ambartsumyan, S. A.

    1956-01-01

    This paper considers a sufficiently thin shallow shell of nonzero Gaussian curvature. It also presents a system of symmetrically constructed differential equations, constructed by the mixed method through the stress function and the displpacement function.

  12. Indentation of pressurized viscoplastic polymer spherical shells

    NASA Astrophysics Data System (ADS)

    Tvergaard, V.; Needleman, A.

    2016-08-01

    The indentation response of polymer spherical shells is investigated. Finite deformation analyses are carried out with the polymer characterized as a viscoelastic/viscoplastic solid. Both pressurized and unpressurized shells are considered. Attention is restricted to axisymmetric deformations with a conical indenter. The response is analyzed for various values of the shell thickness to radius ratio and various values of the internal pressure. Two sets of material parameters are considered: one set having network stiffening at a moderate strain and the other having no network stiffening until very large strains are attained. The transition from an indentation type mode of deformation to a structural mode of deformation involving bending that occurs as the indentation depth increases is studied. The results show the effects of shell thickness, internal pressure and polymer constitutive characterization on this transition and on the deformation modes in each of these regimes.

  13. SU(3) in shell-model calculations

    SciTech Connect

    Millener, D.J.

    1991-10-01

    The essential steps in the formalism for performing multi-shell calculations in an SU(3) basis are outlined and examples of applications in which the SU(3) classification aids in the physical interpretation of structure calculation are given.

  14. Shell Eggs from Farm to Table

    MedlinePlus

    ... and stored and transported under refrigeration and ambient temperature of no greater than 45 °F. USDA also ... transported under refrigeration at an ambient (surrounding) air temperature not to exceed 45 °F; All packed shell ...

  15. The stability of a collisionless cosmological shell

    NASA Technical Reports Server (NTRS)

    White, Simon D. M.; Ostriker, J. P.

    1990-01-01

    The P3 M technique is used here to simulate the evolution of collisionless shells in an Omega = 1 universe. Starting from the spherical similarity solution, a bootstrap technique is used to follow the evolution over very large expansion factors. It is found that the overall structure follows the similarity solution for a long period during which bound clumps grow within the shell. At late times the growth of structure depends on induced velocity perturbations in material outside the shell. If such perturbations are suppressed, structure on the shell becomes self-similar. When induced motions in the background medium are included, the evolution at late times is dominated by large-scale modes as predicted by linear stability analysis. The stable final state appears to consist of one or two massive clumps on the edge of a spherical void. The possible application of these results to the origin of galaxies and large-scale structure is discussed.

  16. Damping control of 'smart' piezoelectric shell structures

    NASA Astrophysics Data System (ADS)

    Tzou, H. S.

    Advanced 'smart' structures with self-sensation and control capabilities have attracted much attention in recent years. 'Smart' piezoelectric structures (conventional structures integrated with piezoelectric sensor and actuator elements) possessing self-monitoring and adaptive static and/or dynamic characteristics are very promising in many applications. This paper presents a study on 'smart' piezoelectric shell structures. A generic piezoelastic vibration theory for a thin piezoelectric shell continuum made of a hexagonal piezoelectric material is first derived. Piezoelastic system equation and electrostatic charge equation are formulated using Hamilton's principle and Kirchhoff-Love thin shell assumptions. Dynamic adaptivity, damping control, of a simply supported cylindrical shell structure is demonstrated in a case study. It shows that the system damping increases with the increase of feedback voltage for odd modes. The control scheme is ineffective for all even modes because of the symmetrical boundary conditions.

  17. Shell nuclear explosions in degenerate dwarfs

    NASA Astrophysics Data System (ADS)

    Kuznetsov, O. A.; Tutukov, A. V.; Chechetkin, V. M.

    1989-08-01

    Numerical gas dynamics simulations are used to study shell nuclear explosions of degenerate carbon-oxygen dwarfs with masses of 1.17, 1.36, and 1.42 solar masses. It is assumed that the calorific capacity of the burning shell matter is between 5 X 10 to the 17th and 5 X 10 to the 18th erg/g. It is shown that, at a low calorific capacity, a remnant may form if the mass of the shell is less than 90 percent of the mass of the degenerate dwarf. In the case of high calorific capacity, a remnant may form only if the mass of the shell is less than half of the dwarf's mass.

  18. Experimental study of upper sd shell nuclei and evolution of sd-fp shell gap

    SciTech Connect

    Sarkar, M. Saha

    2012-06-27

    The intruder orbitals from the fp shell play important role in the structure of nuclei around the line of stability in the upper sd shell. Experimentally we have studied {sup 35}Cl, {sup 30}P, {sup 36}Cl, {sup 37}Ar and {sup 34}Cl in this mass region using the INGA setup. Large basis cross-shell shell model calculations have indicated the need for change of the sd-fp energy gap for reliable reproduction of negative parity and high spin positive parity states. Indication of population of states of large deformation has been found in our data. Theoretical interpretation of these states has been discussed.

  19. Shell-model study for neutron-rich sd-shell nuclei

    SciTech Connect

    Kaneko, Kazunari; Sun Yang; Mizusaki, Takahiro; Hasegawa, Munetake

    2011-01-15

    The microscopic structure of neutron-rich sd-shell nuclei is investigated by using the spherical-shell model in the sd-pf valence space with the extended pairing plus quadrupole-quadrupole forces accompanied by the monopole interaction (EPQQM). The calculation reproduces systematically the known energy levels for even-even and odd-mass nuclei including the recent data for {sup 43}S, {sup 46}S, and {sup 47}Ar. In particular, the erosion of the N=28 shell closure in {sup 42}Si can be explained. Our EPQQM results are compared with other shell-model calculations with the SDPF-NR and SDPF-U effective interactions.

  20. A circumferential crack in a cylindrical shell under tension.

    NASA Technical Reports Server (NTRS)

    Duncan-Fama, M. E.; Sanders, J. L., Jr.

    1972-01-01

    A closed cylindrical shell under uniform internal pressure has a slit around a portion of its circumference. Linear shallow shell theory predicts inverse square-root-type singularities in certain of the stresses at the crack tips. This paper reports the computed strength of these singularities for different values of a dimensionless parameter based on crack length, shell radius and shell thickness.

  1. Static structural analysis of shell-type structures

    NASA Technical Reports Server (NTRS)

    Baker, E. H.; Cappelli, A. P.; Kovalevsky, L.; Rish, F. L.; Verrette, R. M.

    1968-01-01

    Shell analysis manual provides methods for determining static deflections and internal load and stress distributions in shells under various loading conditions, and methods of analyzing static instability of shell structures. Also included are methods for determining the lightest shell wall for various constructions.

  2. Double shell tank waste analysis plan

    SciTech Connect

    Mulkey, C.H.; Jones, J.M.

    1994-12-15

    Waste analysis plan for the double shell tanks. SD-WM-EV-053 is Superseding SD-WM-EV-057.This document provides the plan for obtaining information needed for the safe waste handling and storage of waste in the Double Shell Tank Systems. In Particular it addresses analysis necessary to manage waste according to Washington Administrative Code 173-303 and Title 40, parts 264 and 265 of the Code of Federal Regulations.

  3. Singular Shell Embedded into a Cosmological Model

    NASA Astrophysics Data System (ADS)

    Grøn, Øyvind; Rippis, Peter D.

    2003-12-01

    We generalize Israel's formalism to cover singular shells embedded in a non-vacuum Universe. That is, we deduce the relativistic equation of motion for a thin shell embedded in a Schwarzschild/Friedmann-Lemaître-Robertson-Walker spacetime. Also, we review the embedding of a Schwarzschild mass into a cosmological model using ``curvature'' coordinates and give solutions with (Sch/FLRW) and without the embedded mass (FLRW).

  4. Structural durability of stiffened composite shells

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Rivers, James M.; Murthy, Pappu L. N.; Chamis, Christos C.

    1992-01-01

    The durability of a stiffened composite cylindrical shell panel is investigated under several loading conditions. An integrated computer code is utilized for the simulation of load induced structural degradation. Damage initiation, growth, and accumulation up to the stage of propagation to fracture are included in the computational simulation. Results indicate significant differences in the degradation paths for different loading cases. The effects of combined loading on structural durability and ultimate structural strength of a stiffened shell are assessed.

  5. Trapping of intense light in hollow shell

    SciTech Connect

    Luan, Shixia; Yu, Wei; Yu, M. Y.; Weng, Suming; Wang, Jingwei; Xu, Han; Zhuo, Hongbin; Wong, A. Y.

    2015-09-15

    A small hollow shell for trapping laser light is proposed. Two-dimensional particle-in-cell simulation shows that under appropriate laser and plasma conditions a part of the radiation fields of an intense short laser pulse can enter the cavity of a small shell through an over-critical density plasma in an adjacent guide channel and become trapped. The trapped light evolves into a circulating radial wave pattern until its energy is dissipated.

  6. Experiments on shells under base excitation

    NASA Astrophysics Data System (ADS)

    Pellicano, Francesco; Barbieri, Marco; Zippo, Antonio; Strozzi, Matteo

    2016-05-01

    The aim of the present paper is a deep experimental investigation of the nonlinear dynamics of circular cylindrical shells. The specific problem regards the response of circular cylindrical shells subjected to base excitation. The shells are mounted on a shaking table that furnishes a vertical vibration parallel to the cylinder axis; a heavy rigid disk is mounted on the top of the shells. The base vibration induces a rigid body motion, which mainly causes huge inertia forces exerted by the top disk to the shell. In-plane stresses due to the aforementioned inertias give rise to impressively large vibration on the shell. An extremely violent dynamic phenomenon suddenly appears as the excitation frequency varies up and down close to the linear resonant frequency of the first axisymmetric mode. The dynamics are deeply investigated by varying excitation level and frequency. Moreover, in order to generalise the investigation, two different geometries are analysed. The paper furnishes a complete dynamic scenario by means of: (i) amplitude frequency diagrams, (ii) bifurcation diagrams, (iii) time histories and spectra, (iv) phase portraits and Poincaré maps. It is to be stressed that all the results presented here are experimental.

  7. Buckling of conical shell with local imperfections

    NASA Technical Reports Server (NTRS)

    Cooper, P. A.; Dexter, C. B.

    1974-01-01

    Small geometric imperfections in thin-walled shell structures can cause large reductions in buckling strength. Most imperfections found in structures are neither axisymmetric nor have the shape of buckling modes but rather occur locally. This report presents the results of a study of the effect of local imperfections on the critical buckling load of a specific axially compressed thin-walled conical shell. The buckling calculations were performed by using a two-dimensional shell analysis program referred to as the STAGS (Structural Analysis of General Shells) computer code, which has no axisymmetry restrictions. Results show that the buckling load found from a bifurcation buckling analysis is highly dependent on the circumferential arc length of the imperfection type studied. As the circumferential arc length of the imperfection is increased, a reduction of up to 50 percent of the critical load of the perfect shell can occur. The buckling load of the cone with an axisymmetric imperfections is nearly equal to the buckling load of imperfections which extended 60 deg or more around the circumference, but would give a highly conservative estimate of the buckling load of a shell with an imperfection of a more local nature.

  8. Core-Shell Structured Magnetic Ternary Nanocubes

    SciTech Connect

    Wang, Lingyan; Wang, Xin; Luo, Jin; Wanjala, Bridgid N.; Wang, Chong M.; Chernova, Natalya; Engelhard, Mark H.; Liu, Yao; Bae, In-Tae; Zhong, Chuan-Jian

    2010-12-01

    While transition metal-doped ferrite nanoparticles constitute an important class of soft magnetic nanomaterials with spinel structures, the ability to control the shape and composition would enable a wide range of applications in homogeneous or heterogeneous reactions such as catalysis and magnetic separation of biomolecules. This report describes novel findings of an investigation of core-shell structured MnZn ferrite nanocubes synthesized in organic solvents by manipulating the reaction temperature and capping agent composition in the absence of the conventionally-used reducing agents. The core-shell structure of the highly-monodispersed nanocubes (~20 nm) are shown to consist of an Fe3O4 core and an (Mn0.5Zn0.5)(Fe0.9, Mn1.1)O4 shell. In comparison with Fe3O4 and other binary ferrite nanoparticles, the core-shell structured nanocubes were shown to display magnetic properties regulated by a combination of the core-shell composition, leading to a higher coercivity (~350 Oe) and field-cool/zero-field-cool characteristics drastically different from many regular MnZn ferrite nanoparticles. The findings are discussed in terms of the unique core-shell composition, the understanding of which has important implication to the exploration of this class of soft magnetic nanomaterials in many potential applications such as magnetic resonance imaging, fuel cells, and batteries.

  9. New developments of the nuclear shell model

    NASA Astrophysics Data System (ADS)

    Poves, Alfredo

    2002-04-01

    More than fifty years ago, the independent particle model of the nucleus was proposed by M. Goeppert-Mayer and H. Jensen. The label "shell model" has since changed meaning and nowadays it applies mainly to the description of the nucleus that results of the mixing of many Slater determinants by an effective "in medium" interaction, usually limited to one and two-body terms. The advent of efficient new algorithms to solve the secular problem, together with the increase in speed and storage capacity of modern computers, has brought into the reach of large scale shell model calculations entire regions of nuclei and of nuclear phenomena traditionally considered to be out of the shell model realm. This enormous extension of its field of practical applications has occurred simultaneously with a regain of experimental interest in the nuclear spectroscopy, in particular in very neutron rich and N=Z nuclei. The shell model work in large model spaces demands a very complete understanding of the effective nuclear interaction, a basic goal of the nuclear theory. Besides, the huge increase of dimensionality that occurs when many valence orbits and valence particles are involved, is a formidable challenge for both the direct diagonalization shell model codes and for the many different approximations, based most often in physically guided truncations of the full shell model basis. In this talk I aim to transmit the effervescence of the field by highlighting the most important recent advances and applications.

  10. Batdorf parameter for the spherical shells tectonics

    NASA Astrophysics Data System (ADS)

    Kikuchi, Kazuhei; Nagahama, Hiroyuki

    2015-04-01

    The buckling phenomena of the subducting lithosphere due to the sphericity of the earth has been studied as spherical shell tectonics which happen the megaquake along the boundary of subducting lithosphere. The earthquake scale is decided by slab length or arc length. However, a relationship between slab length and the normalized hydrostatic pressure along the bottom circumferential edge of a hemispherical shell has not been clear yet. So, by using the data set of the geometrical parameters for subducting lithosphere andBuckingham's Pi-theorem, we found out a new linear relationship between Batdorf parameter Z = L2(l - v2)0.5/(Rh) for the measurement of the slab length L and the normalized hydrostatic pressure along the bottom circumferential edge of a hemispherical shell Q = qRL2/(π2D), where D = Eh3/[12(1 - v2)] with E = modulus of elasticity of lithosphere, R is Earth radius, q is the hydrostatic pressure along the bottom circumferential edge of a hemispherical shell, and h is the thickness of subducting lithosphere. In the engineering sciences, a similar relationship between Batdorf parameter for the panel length and normalized hydrostatic pressure was proposed for the buckling of partially liquid-filled circular cylindrical shells under hydrostatic pressure. Moreover, by previous researches, the slab length is approximately proportional to the arc length or the lithosphere thickness related to lithosphere age. Therefore, the Batdorf parameter for subducting lithosphere is an important parameter for the spherical shells tectonics.

  11. Distributed neural signals on parabolic cylindrical shells

    NASA Astrophysics Data System (ADS)

    Hu, S. D.; Li, H.; Tzou, H. S.

    2013-06-01

    Parabolic cylindrical shells are commonly used as key components in communication antennas, space telescopes, solar collectors, etc. This study focuses on distributed modal neural sensing signals on a flexible simply-supported parabolic cylindrical shell panel. The parabolic cylindrical shell is fully laminated with a piezoelectric layer on its outer surface and the piezoelectric layer is segmented into infinitesimal elements (neurons) to investigate the microscopic distributed neural sensing signals. Since the dominant vibration component of the shell is usually the transverse oscillation, a new transverse mode shape function is defined. Two shell cases, i.e., the ratio of the meridian height to the half span distance of a parabola at 1:4 (shallow) and 1:1 (deep), are studied to reveal the curvature effect to the neural sensing signals. Studies suggest that the membrane signal component dominates for lower natural modes and the bending signal component dominates for higher natural modes. The meridional membrane and bending signal components are mostly concentrated on the high-curvature areas, while the longitudinal bending component is mostly concentrated on the relatively flat areas. The concentration behavior becomes more prominent as the parabolic cylindrical shell deepens, primarily resulting from the enhanced membrane effect due to the increased curvature.

  12. Non-planar on-shell diagrams

    NASA Astrophysics Data System (ADS)

    Franco, Sebastián; Galloni, Daniele; Penante, Brenda; Wen, Congkao

    2015-06-01

    We initiate a systematic study of non-planar on-shell diagrams in SYM and develop powerful technology for doing so. We introduce canonical variables generalizing face variables, which make the d log form of the on-shell form explicit. We make significant progress towards a general classification of arbitrary on-shell diagrams by means of two classes of combinatorial objects: generalized matching and matroid polytopes. We propose a boundary measurement that connects general on-shell diagrams to the Grassmannian. Our proposal exhibits two important and non-trivial properties: positivity in the planar case and it matches the combinatorial description of the diagrams in terms of generalized matroid polytopes. Interestingly, non-planar diagrams exhibit novel phenomena, such as the emergence of constraints on Plücker coordinates beyond Plücker relations when deleting edges, which are neatly captured by the generalized matching and matroid polytopes. This behavior is tied to the existence of a new type of poles in the on-shell form at which combinations of Plücker coordinates vanish. Finally, we introduce a prescription, applicable beyond the MHV case, for writing the on-shell form as a function of minors directly from the graph.

  13. "Auctoritas" psychiatric expert system shell.

    PubMed

    Kovács, M; Juranovics, J

    1995-01-01

    We present a short description of a complex psychiatric computer expert system, including functions that help the physicians and the hospital staff in the administrative, diagnostic, therapeutic, statistical, and scientific work. There are separate data-storing, health insurance-supporting, or simple advisory programs, but we can not avail a system--in our country--that provides us with all these functions together. Hence the aim of our program is to produce a universal computer system that makes the patients' long distance follow-up possible. Our diagnostic expert system shell, which is appropriate for using the symptoms and criteria scheme of the internationally accepted diagnostic systems such as DSM and ICD, helps to archive homogeneous, up-to-date psychiatric nosology; this is essential for the correct diagnostic, statistical, and scientific work. Let us introduce our expert system. It consists of four parts: administration, diagnostic decision support system, activities concerning treatment, and statistics. The part called "Administration" contains all data about actual and emitted in-patients and out-patients, including their particulars and data necessary for health insurance (duration of treatment, diagnosis); here we find and edit medical documents. The most important part of the "Auctoritas" system is the "Diagnostic decision support system." In practice, expert systems use decision trees with yes-no logic, fuzzy logic, and pattern matching on the basis of the method of deduction; and backward chaining or forward chaining on the basis of the direction of deduction. Our system uses the methods of fuzzy logic and backward chaining. In other medical disciplines, good results are achieved by applying the pattern matching method; to make validity and verification researches, however, these systems are inappropriate. The diagnoses relying on the up-to-date psychiatric diagnostic systems--DSM-IV and ICD-X--are based on classical logic and can be correctly

  14. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Shell-height standard. 648.50 Section 648... Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for in-shell scallops that may be landed, or possessed at or after landing, is 3.5 inches (8.9...

  15. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Shell-height standard. 648.50 Section 648... Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for in-shell scallops that may be landed, or possessed at or after landing, is 3.5 inches (8.9...

  16. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Shell-height standard. 648.50 Section 648... Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for in-shell scallops that may be landed, or possessed at or after landing, is 3.5 inches (8.9...

  17. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Shell-height standard. 648.50 Section 648... Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for in-shell scallops that may be landed, or possessed at or after landing, is 3.5 inches (8.9...

  18. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Shell-height standard. 648.50 Section 648... Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for in-shell scallops that may be landed, or possessed at or after landing, is 3.5 inches (8.9...

  19. Sound Transmission through Two Concentric Cylindrical Sandwich Shells

    NASA Technical Reports Server (NTRS)

    Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

    1996-01-01

    This paper solves the problem of sound transmission through a system of two infinite concentric cylindrical sandwich shells. The shells are surrounded by external and internal fluid media and there is fluid (air) in the annular space between them. An oblique plane sound wave is incident upon the surface of the outer shell. A uniform flow is moving with a constant velocity in the external fluid medium. Classical thin shell theory is applied to the inner shell and first-order shear deformation theory is applied to the outer shell. A closed form for transmission loss is derived based on modal analysis. Investigations have been made for the impedance of both shells and the transmission loss through the shells from the exterior into the interior. Results are compared for double sandwich shells and single sandwich shells. This study shows that: (1) the impedance of the inner shell is much smaller than that of the outer shell so that the transmission loss is almost the same in both the annular space and the interior cavity of the shells; (2) the two concentric sandwich shells can produce an appreciable increase of transmission loss over single sandwich shells especially in the high frequency range; and (3) design guidelines may be derived with respect to the noise reduction requirement and the pressure in the annular space at a mid-frequency range.

  20. Nanostructure and composition of bivalve shells

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Soldati, A. L.; Wirth, R.; Huth, J.; Wehrmeister, U.; Hofmeister, W.

    2009-04-01

    Shells and pearls of unionid mussels (Hyriopsis cumingii, Margaritifera margaritifera, Diplodon chilensis patagonicus) were studied by high resolution microbeam methods and -computer tomography to gather insight into the nanostructure and chemical composition of nacre and prism layers. Natural and cultured pearls are formed by many mollusc species and their generation is very similar to that of shells resulting in identical prismatic and nacreous structures of shells and pearls. Basic difference is, however that pearl culturing methods induce biomineralisation of CaCO3 around a crystalline bead which results in a reverse structural organisation compared to bivalve shells. Bivalve shell growth starts from a thick organic matrix (the periostracum; Eyster and Morse, 1984) which is followed towards the inside by two variously thick layers consisting of prismatic CaCO3 aggregations and layers of CaCO3 platelets, respectively. Platelets and prisms are individually covered by a chitinous organic matrix which lends structural support and is thought to exert control over the mineralization process. The minerals within the organic sheaths are highly-aligned poly-twinned crystals with a slightly distorted lattice due to inclusions of organic molecules (Pokroy et al., 2006). Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Raman Microscopy analyses of the shells and pearls show that both structures, prisms and platelets, consist of nanometre-sized organic membrane-coated granules of CaCO3 (Jacob et al., 2008). In the vicinity of the periostracum, the granules consist of amorphous calcium carbonate (ACC), but the crystallinity increases with increasing distance from the periostracum. The transition from disordered (amorphous) to crystalline CaCO3 is gradual within a few micrometers and coincides with a decrease in porosity. Concentrations of sulphur and phosphorus are higher in ACC than in aragonite indicating a

  1. Thin Shell Manufacturing for large Wavefront correctors

    NASA Astrophysics Data System (ADS)

    Ruch, Eric; Poutriquet, Florence

    2011-09-01

    One of the major key elements in large adaptive optical systems is the thin shell, used as a deformable mirror. Although the optical prescriptions are relaxed with respect to a passive mirror, especially in the low spatial frequency domain, other requirements, such as the cosmetic defects (scratch & dig), the tight control of the thickness uniformity and of course the fragility of the piece having an aspect ratio up to 1000:1, generate new problems during the manufacturing, testing and handling of such optics. Moreover, the optical surface has to be tested in two different ways: a classical optical test bench allows us to create a surface map of the mirror. This map is then computed to determine the force required by the actuators to flatten the mirror and this becomes also a specification for polishing and implies a good interaction with the voice coil manufacturer. More than twenty years ago Sagem - Reosc developed the first meter class thin shell for early adaptive optics experiments. Since then, large thin shell have been used as the optical part in composite mirrors and more recently the aspheric shell for the VLT Deformable Secondary Mirror has been polished and prototypes, up to scale 1, of the E-ELT M4 Adaptive Mirror have been delivered to ESO in 2010. This paper will present some recent results in the manufacturing and testing technologies of large this shell, especially focusing on the development of the 1,1 meter convex aspherical shell for the VLT M2 mirror and on the results obtained on the largest thin shell produced so far (2,5 meter in diameter) developed as a demonstrator for the future E-ELT M4.

  2. Simplified dispersion curves for circular cylindrical shells using shallow shell theory

    NASA Astrophysics Data System (ADS)

    Sarkar, Abhijit; Sonti, Venkata R.

    2009-04-01

    An alternative derivation of the dispersion relation for the transverse vibration of a circular cylindrical shell is presented. The use of the shallow shell theory model leads to a simpler derivation of the same result. Further, the applicability of the dispersion relation is extended to the axisymmetric mode and the high frequency beam mode.

  3. Comparative study of the shell development of hard- and soft-shelled turtles

    PubMed Central

    Nagashima, Hiroshi; Shibata, Masahiro; Taniguchi, Mari; Ueno, Shintaro; Kamezaki, Naoki; Sato, Noboru

    2014-01-01

    The turtle shell provides a fascinating model for the investigation of the evolutionary modifications of developmental mechanisms. Different conclusions have been put forth for its development, and it is suggested that one of the causes of the disagreement could be the differences in the species of the turtles used – the differences between hard-shelled turtles and soft-shelled turtles. To elucidate the cause of the difference, we compared the turtle shell development in the two groups of turtle. In the dorsal shell development, these two turtle groups shared the gene expression profile that is required for formation, and shared similar spatial organization of the anatomical elements during development. Thus, both turtles formed the dorsal shell through a folding of the lateral body wall, and the Wnt signaling pathway appears to have been involved in the development. The ventral portion of the shell, on the other hand, contains massive dermal bones. Although expression of HNK-1 epitope has suggested that the trunk neural crest contributed to the dermal bones in the hard-shelled turtles, it was not expressed in the initial anlage of the skeletons in either of the types of turtle. Hence, no evidence was found that would support a neural crest origin. PMID:24754673

  4. Shell-in-Shell TiO2 hollow microspheres and optimized application in light-trapping perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Sun, Hongxia; Ruan, Peng; Bao, Zhongqiu; Chen, Lei; Zhou, Xingfu

    2015-02-01

    The shell-in-shell structured TiO2 hollow microspheres with enhanced light scattering ability were synthesized via a facile one step hydrothermal process. The diameter of the microsphere is about 1.5 μm, the core of the unique shell-in-shell structure is composed of TiO2 nanoparticles with a diameter of about 15 nm, while the shell is constructed with ∼50 nm TiO2 nanocubes. The hollow space between the outer shell and the inner shell is about 230 nm. The formation mechanism of the unique shell-in-shell structure is interpreted. The design and the optimized application of shell-in-shell structured TiO2 hollow microspheres in the light-trapping perovskite solar cells are also investigated. Owing to the light scattering properties of the shell-in-shell structure of the hollow microsphere, the optimized photoelectrode exhibits an enhanced photoelectric conversion efficiency of 4.29% using perovskite CH3NH3PbI3 as the sensitizer. The shell-in-shell hollow TiO2 microsphere shows a 21.2% increase in conversion efficiency when compared with P25 nanoparticels photoanode. The conversion efficiency enhancement is mainly attributed to the increase of short-current density induced by the light scattering effect.

  5. Size-selective yolk-shell nanoreactors with nanometer-thin porous polymer shells.

    PubMed

    Jia, Ying; Shmakov, Sergey N; Register, Paul; Pinkhassik, Eugene

    2015-09-01

    Yolk-shell nanoreactors with metal nanoparticle core and ultrathin porous polymer shells are effective catalysts for heterogeneous reactions. Polymer shells provide size-selectivity and improved reusability of catalyst. Nanocapsules with single-nanometer porous shells are prepared by vesicle-templated directed assembly. Metal nanoparticles are formed either by selective initiation in pre-fabricated nanocapsules or simultaneously with the creation of a crosslinked polymer shell. In this study, we investigated the oxidation of benzyl alcohol and benzaldehyde catalyzed by gold nanoparticles and hydrogenation of cyclohexene catalyzed by platinum nanoparticles. Comparison of newly created nanoreactors with commercially available nanoparticles revealed superior reusability and size selectivity in nanoreactors while showing no negative effect on reaction kinetics. PMID:26223572

  6. Lithography-free shell-substrate isolation for core-shell GaAs nanowires.

    PubMed

    Haggren, Tuomas; Perros, Alexander Pyymaki; Jiang, Hua; Huhtio, Teppo; Kakko, Joona-Pekko; Dhaka, Veer; Kauppinen, Esko; Lipsanen, Harri

    2016-07-01

    A facile and scalable lithography-free technique(5) for the rapid construction of GaAs core-shell nanowires incorporating shell isolation from the substrate is reported. The process is based on interrupting NW growth and applying a thin spin-on-glass (SOG) layer to the base of the NWs and resuming core-shell NW growth. NW growth occurred in an atmospheric pressure metalorganic vapour phase epitaxy (MOVPE) system with gold nanoparticles used as catalysts for the vapour-liquid-solid growth. It is shown that NW axial core growth and radial shell growth can be resumed after interruption and even exposure to air. The SOG residues and native oxide layer that forms on the NW surface are shown to prevent or perturb resumption of epitaxial NW growth if not removed. Both HF etching and in situ annealing of the air-exposed NWs in the MOVPE were shown to remove the SOG residues and native oxide layer. While both procedures are shown capable of removing the native oxide and enabling resumption of epitaxial NW growth, in situ annealing produced the best results and allowed construction of pristine core-shell NWs. No growth occurred on SOG and it was observed that axial NW growth was more rapid when a SOG layer covered the substrate. The fabricated p-core/n-shell NWs exhibited diode behaviour upon electrical testing. The isolation of the NW shells from the substrate was confirmed by scanning electron microscopy and electrical measurements. The crystal quality of the regrown core-shell NWs was verified with a high resolution transmission electron microscope. The reported technique potentially provides a pathway using MOVPE for scalable and high-throughput production of shell-substrate isolated core-shell NWs on an industrial scale. PMID:27242347

  7. Lithography-free shell-substrate isolation for core–shell GaAs nanowires

    NASA Astrophysics Data System (ADS)

    Haggren, Tuomas; Pyymaki Perros, Alexander; Jiang, Hua; Huhtio, Teppo; Kakko, Joona-Pekko; Dhaka, Veer; Kauppinen, Esko; Lipsanen, Harri

    2016-07-01

    A facile and scalable lithography-free technique5 for the rapid construction of GaAs core–shell nanowires incorporating shell isolation from the substrate is reported. The process is based on interrupting NW growth and applying a thin spin-on-glass (SOG) layer to the base of the NWs and resuming core–shell NW growth. NW growth occurred in an atmospheric pressure metalorganic vapour phase epitaxy (MOVPE) system with gold nanoparticles used as catalysts for the vapour‑liquid‑solid growth. It is shown that NW axial core growth and radial shell growth can be resumed after interruption and even exposure to air. The SOG residues and native oxide layer that forms on the NW surface are shown to prevent or perturb resumption of epitaxial NW growth if not removed. Both HF etching and in situ annealing of the air-exposed NWs in the MOVPE were shown to remove the SOG residues and native oxide layer. While both procedures are shown capable of removing the native oxide and enabling resumption of epitaxial NW growth, in situ annealing produced the best results and allowed construction of pristine core–shell NWs. No growth occurred on SOG and it was observed that axial NW growth was more rapid when a SOG layer covered the substrate. The fabricated p-core/n-shell NWs exhibited diode behaviour upon electrical testing. The isolation of the NW shells from the substrate was confirmed by scanning electron microscopy and electrical measurements. The crystal quality of the regrown core–shell NWs was verified with a high resolution transmission electron microscope. The reported technique potentially provides a pathway using MOVPE for scalable and high-throughput production of shell-substrate isolated core–shell NWs on an industrial scale.

  8. Hollow Pollen Shells to Enhance Drug Delivery

    PubMed Central

    Diego-Taboada, Alberto; Beckett, Stephen T.; Atkin, Stephen L.; Mackenzie, Grahame

    2014-01-01

    Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

  9. Thick or Thin Ice Shell on Europa?

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Scientists are all but certain that Europa has an ocean underneath its icy surface, but they do not know how thick this ice might be. This artist concept illustrates two possible cut-away views through Europa's ice shell. In both, heat escapes, possibly volcanically, from Europa's rocky mantle and is carried upward by buoyant oceanic currents. If the heat from below is intense and the ice shell is thin enough (left), the ice shell can directly melt, causing what are called 'chaos' on Europa, regions of what appear to be broken, rotated and tilted ice blocks. On the other hand, if the ice shell is sufficiently thick (right), the less intense interior heat will be transferred to the warmer ice at the bottom of the shell, and additional heat is generated by tidal squeezing of the warmer ice. This warmer ice will slowly rise, flowing as glaciers do on Earth, and the slow but steady motion may also disrupt the extremely cold, brittle ice at the surface. Europa is no larger than Earth's moon, and its internal heating stems from its eccentric orbit about Jupiter, seen in the distance. As tides raised by Jupiter in Europa's ocean rise and fall, they may cause cracking, additional heating and even venting of water vapor into the airless sky above Europa's icy surface. (Artwork by Michael Carroll.)

  10. Hollow pollen shells to enhance drug delivery.

    PubMed

    Diego-Taboada, Alberto; Beckett, Stephen T; Atkin, Stephen L; Mackenzie, Grahame

    2014-01-01

    Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

  11. Folding of non-Euclidean curved shells

    NASA Astrophysics Data System (ADS)

    Bende, Nakul; Evans, Arthur; Innes-Gold, Sarah; Marin, Luis; Cohen, Itai; Santangelo, Christian; Hayward, Ryan

    2015-03-01

    Origami-based folding of 2D sheets has been of recent interest for a variety of applications ranging from deployable structures to self-folding robots. Though folding of planar sheets follows well-established principles, folding of curved shells involves an added level of complexity due to the inherent influence of curvature on mechanics. In this study, we use principles from differential geometry and thin shell mechanics to establish fundamental rules that govern folding of prototypical creased shells. In particular, we show how the normal curvature of a crease line controls whether the deformation is smooth or discontinuous, and investigate the influence of shell thickness and boundary conditions. We show that snap-folding of shells provides a route to rapid actuation on time-scales dictated by the speed of sound. The simple geometric design principles developed can be applied at any length-scale, offering potential for bio-inspired soft actuators for tunable optics, microfluidics, and robotics. This work was funded by the National Science Foundation through EFRI ODISSEI-1240441 with additional support to S.I.-G. through the UMass MRSEC DMR-0820506 REU program.

  12. Removable inner turbine shell with bucket tip clearance control

    DOEpatents

    Sexton, Brendan F.; Knuijt, Hans M.; Eldrid, Sacheverel Q.; Myers, Albert; Coneybeer, Kyle E.; Johnson, David Martin; Kellock, Iain R.

    2000-01-01

    A turbine includes a plurality of inner shell sections mounting first and second stage nozzle and shroud portions. The inner shell sections are pinned to an outer containment shell formed of sections to preclude circumferential movement of the inner shell relative to the outer shell and enable thermal expansion and contraction of the inner shell relative to the outer shell. Positive bucket tip clearance control is afforded by passing a thermal medium about the inner shell in heat transfer relation with the shrouds about the first and second stage bucket tips, the thermal medium being provided from a source of heating/cooling fluid independent of the turbine. Access is provided to the rotor and turbine buckets by removing the outer and inner shell sections.

  13. Structural Assessment of Advanced Composite Tow-Steered Shells

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Stanford, Bret K.; Hrinda, Glenn A.; Wang, Zhuosong; Martin, Robert a.; Kim, H. Alicia

    2013-01-01

    The structural performance of two advanced composite tow-steered shells, manufactured using a fiber placement system, is assessed using both experimental and analytical methods. The fiber orientation angles vary continuously around the shell circumference from 10 degrees on the shell crown and keel, to 45 degrees on the shell sides. The two shells differ in that one shell has the full 24-tow course applied during each pass of the fiber placement system, while the second shell uses the fiber placement system s tow drop/add capability to achieve a more uniform shell wall thickness. The shells are tested in axial compression, and estimates of their prebuckling axial stiffnesses and bifurcation buckling loads are predicted using linear finite element analyses. These preliminary predictions compare well with the test results, with an average agreement of approximately 10 percent.

  14. Do freshwater mussel shells record road-salt pollution?

    NASA Astrophysics Data System (ADS)

    O'Neil, Dane D.; Gillikin, David P.

    2014-11-01

    Road-salt pollution in streams in the Northeastern United States has become a major concern, but historical data are scarce. Freshwater bivalve shells have the ability to record past environmental information, and may act as archives of road-salt pollution. We sampled Elliptio complanata shells from four streams, as well as specimens collected in 1877. Average [Na/Ca]shell was highest in modern shells from the stream with the highest sodium concentrations, and low in shells collected from this same stream in 1877 as well as in the shells from other streams, suggesting that [Na/Ca]shell serves as a proxy for road-salt pollution. We expected higher [Na/Ca]shell in winter and spring. However, high-resolution [Na/Ca]shell analyses along the growth axis of one shell did not reveal any clear subannual patterns, which could be the result of shell growth cessation in winter and/or during periods of high stream sodium concentrations. Therefore, bulk [Na/Ca]shell analysis from multiple shells can be used as a proxy of large changes in stream sodium concentrations, but high-resolution variations in stream sodium concentrations do not seem to be recorded in the shells.

  15. Do freshwater mussel shells record road-salt pollution?

    PubMed Central

    O'Neil, Dane D.; Gillikin, David P.

    2014-01-01

    Road-salt pollution in streams in the Northeastern United States has become a major concern, but historical data are scarce. Freshwater bivalve shells have the ability to record past environmental information, and may act as archives of road-salt pollution. We sampled Elliptio complanata shells from four streams, as well as specimens collected in 1877. Average [Na/Ca]shell was highest in modern shells from the stream with the highest sodium concentrations, and low in shells collected from this same stream in 1877 as well as in the shells from other streams, suggesting that [Na/Ca]shell serves as a proxy for road-salt pollution. We expected higher [Na/Ca]shell in winter and spring. However, high-resolution [Na/Ca]shell analyses along the growth axis of one shell did not reveal any clear subannual patterns, which could be the result of shell growth cessation in winter and/or during periods of high stream sodium concentrations. Therefore, bulk [Na/Ca]shell analysis from multiple shells can be used as a proxy of large changes in stream sodium concentrations, but high-resolution variations in stream sodium concentrations do not seem to be recorded in the shells. PMID:25418687

  16. Single crystal U-Pb zircon age and Sr-Nd isotopic composition of impactites from the Bosumtwi impact structure, Ghana: Comparison with country rocks and Ivory Coast tektites.

    PubMed

    Ferrière, Ludovic; Koeberl, Christian; Thöni, Martin; Liang, Chen

    2010-08-01

    The 1.07 Myr old Bosumtwi impact structure (Ghana), excavated in 2.1-2.2 Gyr old supracrustal rocks of the Birimian Supergroup, was drilled in 2004. Here, we present single crystal U-Pb zircon ages from a suevite and two meta-graywacke samples recovered from the central uplift (drill core LB-08A), which yield an upper Concordia intercept age of ca. 2145 ± 82 Ma, in very good agreement with previous geochronological data for the West African Craton rocks in Ghana. Whole rock Rb-Sr and Sm-Nd isotope data of six suevites (five from inside the crater and one from outside the northern crater rim), three meta-graywacke, and two phyllite samples from core LB-08A are also presented, providing further insights into the timing of the metamorphism and a possibly related isotopic redistribution of the Bosumtwi crater rocks. Our Rb-Sr and Sm-Nd data show also that the suevites are mixtures of meta-greywacke and phyllite (and possibly a very low amount of granite). A comparison of our new isotopic data with literature data for the Ivory Coast tektites allows to better constrain the parent material of the Ivory Coast tektites (i.e., distal impactites), which is thought to consist of a mixture of metasedimentary rocks (and possibly granite), but with a higher proportion of phyllite (and shale) than the suevites (i.e., proximal impactites). When plotted in a Rb/Sr isochron diagram, the sample data points (n = 29, including literature data) scatter along a regression line, whose slope corresponds to an age of 1846 ± 160 Ma, with an initial Sr isotope ratio of 0.703 ± 0.002. However, due to the extensive alteration of some of the investigated samples and the lithological diversity of the source material, this age, which is in close agreement with a possible "metamorphic age" of ∼ 1.8-1.9 Ga tentatively derived from our U-Pb dating of zircons, is difficult to consider as a reliable metamorphic age. It may perhaps reflect a common ancient source whose Rb-Sr isotope

  17. Single crystal U–Pb zircon age and Sr–Nd isotopic composition of impactites from the Bosumtwi impact structure, Ghana: Comparison with country rocks and Ivory Coast tektites

    PubMed Central

    Ferrière, Ludovic; Koeberl, Christian; Thöni, Martin; Liang, Chen

    2010-01-01

    The 1.07 Myr old Bosumtwi impact structure (Ghana), excavated in 2.1–2.2 Gyr old supracrustal rocks of the Birimian Supergroup, was drilled in 2004. Here, we present single crystal U–Pb zircon ages from a suevite and two meta-graywacke samples recovered from the central uplift (drill core LB-08A), which yield an upper Concordia intercept age of ca. 2145 ± 82 Ma, in very good agreement with previous geochronological data for the West African Craton rocks in Ghana. Whole rock Rb–Sr and Sm–Nd isotope data of six suevites (five from inside the crater and one from outside the northern crater rim), three meta-graywacke, and two phyllite samples from core LB-08A are also presented, providing further insights into the timing of the metamorphism and a possibly related isotopic redistribution of the Bosumtwi crater rocks. Our Rb–Sr and Sm–Nd data show also that the suevites are mixtures of meta-greywacke and phyllite (and possibly a very low amount of granite). A comparison of our new isotopic data with literature data for the Ivory Coast tektites allows to better constrain the parent material of the Ivory Coast tektites (i.e., distal impactites), which is thought to consist of a mixture of metasedimentary rocks (and possibly granite), but with a higher proportion of phyllite (and shale) than the suevites (i.e., proximal impactites). When plotted in a Rb/Sr isochron diagram, the sample data points (n = 29, including literature data) scatter along a regression line, whose slope corresponds to an age of 1846 ± 160 Ma, with an initial Sr isotope ratio of 0.703 ± 0.002. However, due to the extensive alteration of some of the investigated samples and the lithological diversity of the source material, this age, which is in close agreement with a possible “metamorphic age” of ∼ 1.8–1.9 Ga tentatively derived from our U–Pb dating of zircons, is difficult to consider as a reliable metamorphic age. It may perhaps reflect a common ancient source

  18. FInal Report - Investment Casting Shell Cracking

    SciTech Connect

    Von Richards

    2003-12-01

    This project made a significant contribution to the understanding of the investment casting shell cracking problem. The effects of wax properties on the occurrence of shell cracking were demonstrated and can be measured. The properties measured include coefficient of thermal expansion, heating rate and crystallinity of the structure. The important features of production molds and materials properties have been indicated by case study analysis and fractography of low strength test bars. It was found that stress risers in shell cavity design were important and that typical critical flaws were either oversize particles or large pores just behind the prime coat. It was also found that the true effect of fugitive polymer fibers was not permeability increase, but rather a toughening mechanism due to crack deflection.

  19. Damage Tolerance of Large Shell Structures

    NASA Technical Reports Server (NTRS)

    Minnetyan, L.; Chamis, C. C.

    1999-01-01

    Progressive damage and fracture of large shell structures is investigated. A computer model is used for the assessment of structural response, progressive fracture resistance, and defect/damage tolerance characteristics. Critical locations of a stiffened conical shell segment are identified. Defective and defect-free computer models are simulated to evaluate structural damage/defect tolerance. Safe pressurization levels are assessed for the retention of structural integrity at the presence of damage/ defects. Damage initiation, growth, accumulation, and propagation to fracture are included in the simulations. Damage propagation and burst pressures for defective and defect-free shells are compared to evaluate damage tolerance. Design implications with regard to defect and damage tolerance of a large steel pressure vessel are examined.

  20. Modeling of microencapsulated polymer shell solidification

    SciTech Connect

    Boone, T.; Cheung, L.; Nelson, D.; Soane, D.; Wilemski, G.; Cook, R.

    1995-03-08

    A finite element transport model has been developed and implemented to complement experimental efforts to improve the quality of ICF target shells produced via controlled-mass microencapsulation. The model provides an efficient means to explore the effect of processing variables on the dynamics of shell dimensions, concentricity, and phase behavior. Comparisons with experiments showed that the model successfully predicts the evolution of wall thinning and core/wall density differences. The model was used to efficiently explore and identify initial wall compositions and processing temperatures which resulted in concentricity improvements from 65 to 99%. The evolution of trace amounts of water entering into the shell wall was also tracked in the simulations. Comparisons with phase envelope estimations from modified UNIFAP calculations suggest that the water content trajectory approaches the two-phase region where vacuole formation via microphase separation may occur.

  1. COMPLETE SURFACE MAPPING OF ICF SHELLS

    SciTech Connect

    STEPHENS,R.B; OLSON,D; HUANG,H; GIBSON,J.B

    2003-06-01

    OAK-B135 Inertial confinement fusion shells have previously been evaluated on the basis of microscopic examination for local defects and limited surface profiling to represent their average fluctuation power. Since defects are local, and don't always have visible edges, this approach both misses some important fluctuations and doesn't properly represent the spatially dependent surface fluctuation power. they have taken the first step toward correcting this problem by demonstrating the capability to completely map the surface of a NIF shell with the resolution to account for all modes. This allows complete accounting of all the surface fluctuations. In the future this capability could be used for valuable shells to generate a complete r({theta},{psi}) surface map for accurate 3-D modeling of a shot.

  2. The microindentation behavior of several mollusk shells

    SciTech Connect

    Laraia, V.J.; Heuer, A.H. . Dept. of Materials Science and Engineering)

    1990-01-01

    An investigation of the relationship between structure and mechanical behavior is reported for mollusk shells employing foliated, nacreous, and crossed-lamellar structures by microindentation in the Knoop and Vickers geometries. Indentation damage zones develop crack systems that reflect the micro-architecture. For the crosed-lamellar structure, the system of cracks about the indentation normally developed in a brittle material is suppressed. Previous reports that shells are harder than the corresponding minerals, calcite and aragonite, are confirmed, but it is found that this effect can be strongly dependent on orientation. This anomalous hardness is not an artifact of the indentation test technique, since scratch tests confirm the relative hardness of shell over the mineral. It is suggested that microstructural organization is of central importance in producing this hardness, as opposed to intrinsic properties of the mineral or matrix phases. 17 refs., 6 figs., 1 tab.

  3. Spline Approximation of Thin Shell Dynamics

    NASA Technical Reports Server (NTRS)

    delRosario, R. C. H.; Smith, R. C.

    1996-01-01

    A spline-based method for approximating thin shell dynamics is presented here. While the method is developed in the context of the Donnell-Mushtari thin shell equations, it can be easily extended to the Byrne-Flugge-Lur'ye equations or other models for shells of revolution as warranted by applications. The primary requirements for the method include accuracy, flexibility and efficiency in smart material applications. To accomplish this, the method was designed to be flexible with regard to boundary conditions, material nonhomogeneities due to sensors and actuators, and inputs from smart material actuators such as piezoceramic patches. The accuracy of the method was also of primary concern, both to guarantee full resolution of structural dynamics and to facilitate the development of PDE-based controllers which ultimately require real-time implementation. Several numerical examples provide initial evidence demonstrating the efficacy of the method.

  4. Single-Molecule Solvation-Shell Sensing

    NASA Astrophysics Data System (ADS)

    Leary, E.; Höbenreich, H.; Higgins, S. J.; van Zalinge, H.; Haiss, W.; Nichols, R. J.; Finch, C. M.; Grace, I.; Lambert, C. J.; McGrath, R.; Smerdon, J.

    2009-02-01

    We present a new route to single-molecule sensing via solvation shells surrounding a current-carrying backbone molecule. As an example, we show that the presence of a water solvation shell “gates” the conductance of a family of oligothiophene-containing molecular wires, and that the longer the oligothiophene, the larger is the effect. For the longest example studied, the molecular conductance is over 2 orders of magnitude larger in the presence of a shell comprising just 10 water molecules. A first principles theoretical investigation of electron transport through the molecules, using the nonequilibrium Green’s function method, shows that water molecules interact directly with the thiophene rings, significantly shifting transport resonances and greatly increasing the conductance. This reversible effect is confirmed experimentally through conductance measurements performed in the presence of moist air and dry argon.

  5. Locally adaptive method to define coordination shell.

    PubMed

    Higham, Jonathan; Henchman, Richard H

    2016-08-28

    An algorithm is presented to define a particle's coordination shell for any collection of particles. It requires only the particles' positions and no pre-existing knowledge or parameters beyond those already in the force field. A particle's shell is taken to be all particles that are not blocked by any other particle and not further away than a blocked particle. Because blocking is based on two distances and an angle for triplets of particles, it is called the relative angular distance (RAD) algorithm. RAD is applied to Lennard-Jones particles in molecular dynamics simulations of crystalline, liquid, and gaseous phases at various temperatures and densities. RAD coordination shells agree well with those from a cut-off in the radial distribution function for the crystals and liquids and are slightly higher for the gas. PMID:27586905

  6. Shell nebulae around luminous evolved stars

    NASA Technical Reports Server (NTRS)

    Dufour, Reginald J.

    1989-01-01

    Shell nebulae around luminous Population I Wolf-Rayet, Of, and P-Cygni stars are astrophysically interesting since they are indicators of pre-supernova mass loss and how such massive stars prepare their surrounding interstellar medium prior to explosion. Some twenty-odd such nebulae are known, for which detailed study of their morphological and spectroscopic characteristics have only begun in this decade. In this paper, some of these characteristics are reviewed in general, and new observations are reported. Emphasis has been placed on several 'prototype 'objects (NGC 7635, NGC 2359, NGC 6888, and the Eta Carinae condensations) to illustrate the varied massive-star mass-loss, the physics of their winds and shell ejecta, and related nucleosynthesis effects in the compositions of the winds and shells.

  7. Spherical shell model description of rotational motion

    SciTech Connect

    Zuker, A.P.; Retamosa, J.; Poves, A.; Caurier, E.

    1995-10-01

    Exact diagonalizations with a realistic interaction show that configurations with four neutrons in a major shell and four protons in another---or the same---major shell, behave systematically as backbending rotors. The dominance of the {ital q}{center_dot}{ital q} component of the interaction is related to an approximate ``quasi-SU3`` symmetry. It is suggested that the onset of rotational motion in the rare earth nuclei is due to the promotion of the eight particle blocks to the major shells above the ones currently filling. Assuming a ``pseudo-SU3`` coupling for the particles in the lower orbits, it is possible to account remarkably well for the observed {ital B}({ital E}2) rates at the beginning of the region.

  8. Adaptive piezoelectric shell structures: theory and experiments

    NASA Astrophysics Data System (ADS)

    Tzou, H. S.; Zhong, J. P.

    1993-07-01

    Active "smart" space and mechanical structures with adaptive dynamic characteristics have long been interested in a variety of high-performance systems, e.g. flexible space structures, flexible robots, "smart" machines etc. In this paper, an active adaptive structure made of piezoelectric materials is proposed and evaluated. Electromechanical equations of motion and generalised boundary conditions of a generic piezoelectric shell subjected to mechanical and electrical excitations are derived using Hamilton's principle and the linear piezoelectric theory. The structural adaptivity is achieved by a voltage feedback (open or closed loops) utilising the converse piezoelectric effect. Applications of the theory is demonstrated in a bimorph beam case and a cylindrical shell case. Frequency manipulation of the bimorph beam is studied theoretically and experimentally. Damping control of the cylindrical shell via in-plane membrane forces is also investigated.

  9. Nova shell observation of V2275 Cyg

    NASA Astrophysics Data System (ADS)

    Esenoglu, Hasan H.; Balman, Solen; Saygac, A. Talat

    2016-07-01

    We present a recent search for nova shell of V2275 Cyg after its eruption of 9 years, using narrow bands of H-alpha, OIII and H-alpha-continuum images taken with RTT150 telescope at TUG. They were taken in November 2nd, 2010 with exposures of 600sec. There is uncertain in the literature whether the nova shell is visible in H-alpha. In this work the nova disappears on frame of OIII (wavelengt of 500.7nm with band width of 5nm) when it is faint apparent on the frames of both H-alpha and H-alpha continuum. We will calculate a new angular diameter of the nova shell by using the nebular expantion method if the data allow to measure seeing values of the nova and neighbor stars.

  10. Working and Net Available Shell Storage Capacity

    EIA Publications

    2016-01-01

    Working and Net Available Shell Storage Capacity is the U.S. Energy Information Administration’s (EIA) report containing storage capacity data for crude oil, petroleum products, and selected biofuels. The report includes tables detailing working and net available shell storage capacity by type of facility, product, and Petroleum Administration for Defense District (PAD District). Net available shell storage capacity is broken down further to show the percent for exclusive use by facility operators and the percent leased to others. Crude oil storage capacity data are also provided for Cushing, Oklahoma, an important crude oil market center. Data are released twice each year near the end of May (data for March 31) and near the end of November (data for September 30).

  11. Inner shell radial pin geometry and mounting arrangement

    DOEpatents

    Leach, David; Bergendahl, Peter Allen

    2002-01-01

    Circumferentially spaced arrays of support pins are disposed through access openings in an outer turbine shell and have projections received in recesses in forward and aft sections of an inner turbine shell supported from the outer shell. The projections have arcuate sides in a circumferential direction affording line contacts with the side walls of the recesses and are spaced from end faces of the recesses, enabling radial and axial expansion and contraction of the inner shell relative to the outer shell. All loads are taken up in a tangential direction by the outer shell with the support pins taking no radial loadings.

  12. Triggered Snap-Through of Bistable Shells

    NASA Astrophysics Data System (ADS)

    Cai, Yijie; Huang, Shicheng; Trase, Ian; Hu, Nan; Chen, Zi

    Elastic bistable shells are common structures in nature and engineering, such as the lobes of the Venus flytrap or the surface of a toy jumping poppers. Despite their ubiquity, the parameters that control the bistability of such structures are not well understood. In this study, we explore how the geometrical features of radially symmetric elastic shells affect the shape and potential energy of a shell's stable states, and how to tune certain parameters in order to generate a snap-through transition from a convex semi-stable state to concave stable state. We fabricated a series of elastic shells with varying geometric parameters out of silicone rubber and measured the resulting potential energy in the semi-stable state. Finite element simulations were also conducted in order to determine the deformation and stress in the shells during snap-through. It was found that the energy of the semi-stable state is controlled by only two geometric parameters and a dimensionless ratio. We also noted two distinct transitions during snap-through, one between monostability and semi-bistability (the state a popper toy is in before it snaps-through and jumps), and a second transition between semi-bistability and true bistability. This work shows that it is possible to use a set of simple parameters to tailor the energy landscape of an elastic shell in order to generate complex trigger motions for their potential use in smart applications. Z.C. acknowledge support from Society in Science-Branco Weiss Fellowship, administered by ETH Zurich.

  13. Static spherically symmetric thin shell wormhole colliding with a spherical thin shell

    NASA Astrophysics Data System (ADS)

    Wang, Xiaobao; Gao, Sijie

    2016-03-01

    We consider a static spherically symmetric thin shell wormhole that collides with another thin shell consisting of ordinary matter. By employing the geometrical constraint, which leads to the conservation of energy and momentum, we show that the state after the collision can be solved from the initial data. In the low speed approximation, the solutions are rather simple. The shell may either bounce back or pass through the wormhole. In either case, the wormhole shrinks right after the collision. In the "bouncing" case, a surprising result is that the radial speeds before and after the collision satisfy an addition law, which is independent of other parameters of the wormhole and the shell. Once the shell passes through the wormhole, we find that the shell always expands. However, the expansion rate is the same as its collapsing rate right before the collision. Finally, we find the solution for the shell moving together with the wormhole. This work sheds light on the interaction between wormholes and matter.

  14. What's in a Shell? - Interactions of Chemistry and Structure at Submicron Levels in Bivalve Shells

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Piazolo, S.; Trimby, P.

    2014-12-01

    The wide geographical distribution of bivalve shells makes them much favoured paleoclimate proxy archives. However, they are amongst the materials most affected by physiological effects, making the correct deciphering of these archives a challenging task. Shell building plans are usually hierarchic, thus optimizing mechanical properties. However, different structures common to certain bivalve families, such as the prism-nacre or the crossed-lamellar structures, are assembled from very different building blocks. These structural differences coincide with chemical and crystallographic differences suggesting critically different formation mechanisms within the bivalve class. Most importantly some bivalves form their shells from amorphous calcium carbonate that crystallizes in situ once assembled into the shell. We present new correlated multi-scale structural and compositional data for different shell bivalve shell structures such as nacre-prism, cross-lamellar intermediate structures. Data are obtained using EBSD, FIB-assisted TEM and Transmission Kikuchi Diffraction combined with Nano-SIMS and Raman Microspectrometry and suggest that formation from amorphous phases is widespread and results in different calcium carbonate polymorphs to be present in the shell with distinct chemical compositions. The results highlight the complex nature of the biomaterials, which has consequences for the precision and accuracy of paleotemperature calculations.

  15. Simulation of the stress computation in shells

    NASA Technical Reports Server (NTRS)

    Salama, M.; Utku, S.

    1978-01-01

    A self-teaching computer program is described, whereby the stresses in thin shells can be computed with good accuracy using the best fit approach. The program is designed for use in interactive game mode to allow the structural engineer to learn about (1) the major sources of difficulties and associated errors in the computation of stresses in thin shells, (2) possible ways to reduce the errors, and (3) trade-off between computational cost and accuracy. Included are derivation of the computational approach, program description, and several examples illustrating the program usage.

  16. Fast optimization of static axisymmetric shell structures

    NASA Astrophysics Data System (ADS)

    Jacoby, Jeffrey

    An axisymmetric shell optimization procedure is developed which is a fast, user-friendly and practical tool for design use in disciplines including aerospace, mechanical and civil engineering. The shape and thickness of a shell can be optimized to minimize shell mass, mass/volume ratio or stress with constraints imposed on von Mises stress and local buckling. The procedure was created with the aid of the GENOPT optimization development system (Dr. D. Bushnell, Lockheed Missiles and Space Co) and uses the FAST1 shell analysis program (Prof. C. R. Steele, Stanford University) to perform the constraint analysis. The optimization method used is the modified method of feasible directions. The procedure is fast because exact analysis methods allow complex shells to be modelled with only a few large shell elements and still retain a sufficiently accurate solution. This is of particular advantage near shell boundaries and intersections which can have small regions of very detailed variation in the solution. Finite element methods would require many small elements to capture accurately this detail with a resulting increase in computation time and model complexity. Reducing the complexity of the model also reduces the size of the required input and contributes to the simplicity of the procedure. Optimization design variables are the radial and axial coordinates of nodes and the shape parameters and thicknesses of the elements. Thickness distribution within an element can be optimized by specifying the thickness at evenly spaced control points. Spline interpolation is used to provide a smooth thickness variation between the control points. An effective method is developed for reducing the number of required stress constraint equations. Various shells have been optimized and include models for comparison with published results. Shape, thickness and shape/thickness optimization has been performed on examples including a simple aerobrake, sphere-nozzle intersections, ring

  17. Computation of Thin-Walled Prismatic Shells

    NASA Technical Reports Server (NTRS)

    Vlasov, V. Z.

    1949-01-01

    We consider a prismatic shell consisting of a finite number of narrow rectangular plates and having in the cross-section a finite number of closed contours (fig. 1(a)). We shall assume that the rectangular plates composing the shell are rigidly joined so that there is no motion of any kind of one plate relative to the others meeting at a given connecting line. The position of a point on the middle prismatic surface is considered to be defined by the coordinate z, the distance to a certain initial cross-section z = O, end the coordinate s determining its position on the contour of the cross-section.

  18. Shell model for buoyancy-driven turbulence.

    PubMed

    Kumar, Abhishek; Verma, Mahendra K

    2015-04-01

    In this paper we present a unified shell model for stably stratified and convective turbulence. Numerical simulation of this model for stably stratified flow shows Bolgiano-Obukhbov scaling in which the kinetic energy spectrum varies as k(-11/5). The shell model of convective turbulence yields Kolmogorov's spectrum. These results are consistent with the energy flux and energy feed due to buoyancy, and are in good agreement with direct numerical simulations of Kumar et al. [Phys. Rev. E 90, 023016 (2014)]. PMID:25974587

  19. Distribution of neutrino fluxes from pulsar shells

    NASA Astrophysics Data System (ADS)

    Shapiro, M. M.; Silberberg, R.

    According to a model considered by Berezinsky and Prilutsky (1976), a young, dense supernova shell can be a powerful source of high-energy neutrinos. In this model, ultra-high energy protons and other nuclei are accelerated at the central pulsar. The protons interact in the supernova shell and generate cascades of mesons, which in turn yield neutrinos upon decay. The pulsar luminosity function based on all the observed Galactic pulsars is considered. It is found that the high-energy neutrinos from supernovae in the Milky Way Galaxy should be readily detectable. The corresponding pulsars would be relatively low-powered pulsars.

  20. Carbon nanotube core graphitic shell hybrid fibers.

    PubMed

    Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

    2013-12-23

    A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

  1. Shell hoop prestress generated by welding

    SciTech Connect

    Meuser, R.B.

    1991-03-01

    For some magnet designs it is desirable to generate a prestress, approaching the yield strength, in the shell surrounding the yoke. If that prestress can be generated by weld shrinkage, then more expensive methods of prestressing can be avoided. Shell-to-yoke friction can reduce the prestress, so it is desirable to minimize it. A quick-and-dirty test was performed to address these matters. While the scatter of the data was large, it appears that weld shrinkage can indeed generate the required prestress. The scatter was too large to give any information about the friction, however. The experiment raised more questions than it answered. 1 fig., 4 tabs.

  2. Stability analysis of dynamic thin shells

    NASA Astrophysics Data System (ADS)

    Lobo, Francisco S. N.; Crawford, Paulo

    2005-11-01

    We analyse the stability of generic spherically symmetric thin shells to linearized perturbations around static solutions. We include the momentum flux term in the conservation identity, deduced from the 'ADM' constraint and the Lanczos equations. Following the Ishak Lake analysis, we deduce a master equation which dictates the stable equilibrium configurations. Considering the transparency condition, we study the stability of thin shells around black holes, showing that our analysis is in agreement with previous results. Applying the analysis to traversable wormhole geometries, by considering specific choices for the form function, we deduce stability regions and find that the latter may be significantly increased by considering appropriate choices for the redshift function.

  3. Comparative study of shell swab and shell crush methods for the recovery of Salmonella from shell eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Egg associated Salmonella Enteritidis outbreaks have been a major cause of foodborne illness in Japan as well as in the United States and several European countries. Researchers have been attempting to develop a rapid and highly sensitive method for the recovery of microorganisms from shell eggs. ...

  4. Low Dimensional Models of Shell Vibrations. Parametrically Excited Vibrations of Cylinder Shells

    NASA Astrophysics Data System (ADS)

    Popov, A. A.; Thompson, J. M. T.; McRobie, F. A.

    1998-01-01

    Vibrations of cylindrical shells parametrically excited by axial forcing are considered. The governing system of two coupled non-linear partial differential equations is discretized by using Lagrange equations. The computation is simplified significantly by the application of computer algebra and as a result low dimensional models of shell vibrations are readily obtained. After applying numerical continuation techniques and ideas from dynamical systems theory, complete bifurcation diagrams are constructed. The principal aim is to investigate the interaction between different modes of shell vibration. Results for system models with two of the lowest modes are discussed.

  5. Fabrication and photocatalytic properties of SnO2 double-shelled and triple-shelled hollow spheres

    NASA Astrophysics Data System (ADS)

    Niu, Shanshan; Wang, Yong; Lu, Shan; Wang, Dongxia; Wang, Ping

    2016-06-01

    SnO2 double-shelled and triple-shelled hollow spheres were tailored by adjusting concentration of tin (IV) chloride solution during the process of the tin (IV) ions infused carbonaceous spheres. The structures of these SnO2 multi-shelled hollow spheres were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and their possible formation mechanism were also discussed. In virtue of triple-shelled hollow porous structure and higher specific surface area, SnO2 triple-shelled hollow spheres exhibited enhanced photocatalytic properties compared to SnO2 double-shelled hollow spheres.

  6. Cosmic Shell-Seekers Find a Beauty

    NASA Astrophysics Data System (ADS)

    2005-04-01

    Two scientists have discovered a distinctive shell of hot gas around the site of a distant supernova explosion by combining 150 hours of archived data collected by NASA's Chandra X-ray Observatory. This discovery is a significant step forward in solving a decades-old puzzle as to why some stellar explosions display shells and others do not. "The likely answer is that the explosion of every massive star sends a sonic boom rumbling through interstellar space," said Samar Safi-Harb of the University of Manitoba in Winnipeg, Canada, who is a coauthor with Heather Matheson on a paper describing the research that appears in the journal Advances in Space Research. "It's just that, some of the shells are harder to find than others because of the environment where the explosion occurs." The shell marks a sonic boom, or shock wave, generated by the supernova. Gas is heated to millions of degrees by the shock wave and produces X-rays, but little visible light. By examining the properties of the shell with an X-ray telescope, astronomers can work back to deduce the age (a few thousand years), and energy of the explosion, as well as information about the state of the star a million years before it exploded. Animation of a Supernova Explosion Animation of a Supernova Explosion It is likely that the star that produced the supernova remnant and shell was about 10 times as massive as the Sun. The absence of a detectable shell around this and similar supernova remnants had led astronomers to speculate that another, weaker type of explosion had occurred there. Now this hypothesis seems unlikely. Although many supernovas leave behind bright shells, others do not. This supernova remnant, identified as G21.5-0.9 by radio astronomers 30 years ago, was considered to be one that had no shell. A diffuse cloud of X-rays around the source was detected about 5 years ago by another group of astronomers and independently by Safi-Harb and colleagues using Chandra, but it took the careful

  7. Vibrations of moderately thick shallow spherical shells at large amplitudes

    NASA Astrophysics Data System (ADS)

    Sathyamoorthy, M.

    1994-04-01

    A shallow shell theory is presented for the geometrically nonlinear analysis of moderately thick isotropic spherical shells. Effects of transverse shear deformation and rotatory inertia are included in the governing equations of motion by means of tracing constants. When these effects are ignored, the governing equations readily reduce to those applicable for thin shallow spherical shells. Solutions to the system of thick shell equations are obtained by means of Galerkin's method and the numerical Runge-Kutta procedure. Numerical results are presented for certain cases of shallow spherical shells considering different geometric shell parameters. Transverse shear and rotatory inertia effects are found to be important in linear as well as nonlinear responses of shallow spherical shells. The nonlinear frequency-amplitude behavior is of the softening type for shallow spherical shells and of the hardening type for circular plates. Frequency ratios are lower at any given amplitude when the effects of transverse shear and rotatory inertia are included in the analysis.

  8. MOND implications for spectral line profiles of shell galaxies: shell formation history and mass-velocity scaling relations

    NASA Astrophysics Data System (ADS)

    Bílek, M.; Jungwiert, B.; Ebrová, I.; Bartošková, K.

    2015-03-01

    Context. Many ellipticals are surrounded by round stellar shells probably stemming from minor mergers. A new method for constraining gravitational potential in elliptical galaxies has recently been suggested. It uses the spectral line profiles of these shells to measure the circular velocity at the edge of the shell and the expansion velocity of the shell itself. MOND is an alternative to the dark matter framework aiming to solve the missing mass problem. Aims: We study how the circular and expansion velocities behave in MOND for large shells. Methods: The asymptotic behavior for infinitely large shells is derived analytically. The applicability of the asymptotic results for finitely sized shells is studied numerically on a grid of galaxies modeled with Sérsic spheres. Results: Circular velocity settles asymptotically at a value determined by the baryonic mass of the galaxy forming the baryonic Tully-Fisher relation known for disk galaxies. Shell expansion velocity also becomes asymptotically constant. The expansion velocities of large shells form a multibranched analogy to the baryonic Tully-Fisher relation, together with the galactic baryonic masses. For many - but not all - shell galaxies, the asymptotic values of these two types of velocities are reached under the effective radius. If MOND is assumed to work in ellipticals, then the shell spectra allow many details of the history to be revealed about the formation of the shell system, including its age. The results pertaining to circular velocities apply to all elliptical galaxies, not only those with shells.

  9. On Newton’s shell theorem

    NASA Astrophysics Data System (ADS)

    Borghi, Riccardo

    2014-03-01

    In the present letter, Newton’s theorem for the gravitational field outside a uniform spherical shell is considered. In particular, a purely geometric proof of proposition LXXI/theorem XXXI of Newton’s Principia, which is suitable for undergraduates and even skilled high-school students, is proposed. Minimal knowledge of elementary calculus and three-dimensional Euclidean geometry are required.

  10. Shell seeks modifications to Mosconi sale

    SciTech Connect

    Chynoweth, E.

    1993-01-06

    Privatization of Argentina's Petroquimica General Mosconi (PGM; Buenos Aires) got under way at the end of last years with three companies submitting technical bids. The interested parties are Shell Compania Argentina de Petroleo SA, Diamond Shamrock, and Panam - a group of local companies including Perez Companc, Laboratorios Phoenix, and Quitral. The technical bids include terms of reference and plans for PGM. Shell has sent a letter to the minister in charge of privatization saying it would not present its economic bid, due January 28, unless changes are made in the sale concerning feedstock supply contracts with state oil group YPF. Shell is concerned about the impact of YPF, which supplies PGM most feedstocks. Tender conditions state YPF will retain 30% of PGM, which will be renamed Petroquimica Platense, and will be the exclusive supplier of feestocks and one of the main buyers of product. Government authorities say no decision has been taken relating to Shell's request to change the contract, but they are reviewing the situation. Other bidders made no objections about the proposed conditions. The government is selling 64% of PGM, YPF will retain 30%, and the remainder will go to the workforce.

  11. Sanitation in the Shell Egg Processing Environment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hazard analysis and critical control programs (HACCP) will eventually be required for commercial shell egg processing plants. Sanitation is an essential prerequisite program for HACCP and is based upon current Good Manufacturing Practices (cGMPs) as listed in the Code of Federal Regulations. Good ...

  12. On the Theory of Thin Shallow Shells

    NASA Technical Reports Server (NTRS)

    Nazarov, A. A.

    1956-01-01

    This report is concerned with the theory of thin shallow shells. It does not employ the lines of curvature as the coordinate system, but employs "almost cartesian coordinates" or the coordinates obtained by cutting the surface into two mutually orthogonal systems of parallel planes.

  13. Torrefaction of pomaces and nut shells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Technical: Apple, grape, olive, and tomato pomaces as well as almond and walnut shells were torrefied at different temperatures and times in a muffle furnace. The fiber content and thermal stability of the raw byproducts were examined using fiber analysis and thermogravimetric analysis (TGA), respec...

  14. The 'shell effect': music from environmental noise

    NASA Astrophysics Data System (ADS)

    Diodati, Paolo

    2005-02-01

    The 'shell effect' can be used to play music with a pleasant and characteristic timbre. If you place a sensitive microphone at the rim of pipes of suitable length and diameter to obtain resonance frequencies, ambient noise will produce musical notes. The corresponding optical effect, i.e. extracting visible light from ambient radiation considered dark by the human eye, is also discussed.

  15. Orthotropic rotation-free thin shell elements

    NASA Astrophysics Data System (ADS)

    Munglani, Gautam; Vetter, Roman; Wittel, Falk K.; Herrmann, Hans J.

    2015-11-01

    A method to simulate orthotropic behaviour in thin shell finite elements is proposed. The approach is based on the transformation of shape function derivatives, resulting in a new orthogonal basis aligned to a specified preferred direction for all elements. This transformation is carried out solely in the undeformed state leaving minimal additional impact on the computational effort expended to simulate orthotropic materials compared to isotropic, resulting in a straightforward and highly efficient implementation. This method is implemented for rotation-free triangular shells using the finite element framework built on the Kirchhoff-Love theory employing subdivision surfaces. The accuracy of this approach is demonstrated using the deformation of a pinched hemispherical shell (with a 18° hole) standard benchmark. To showcase the efficiency of this implementation, the wrinkling of orthotropic sheets under shear displacement is analyzed. It is found that orthotropic subdivision shells are able to capture the wrinkling behavior of sheets accurately for coarse meshes without the use of an additional wrinkling model.

  16. Dynamical Disorder in the DNA Hydration Shell.

    PubMed

    Duboué-Dijon, Elise; Fogarty, Aoife C; Hynes, James T; Laage, Damien

    2016-06-22

    The reorientation and hydrogen-bond dynamics of water molecules within the hydration shell of a B-DNA dodecamer, which are of interest for many of its biochemical functions, are investigated via molecular dynamics simulations and an analytic jump model, which provide valuable new molecular level insights into these dynamics. Different sources of heterogeneity in the hydration shell dynamics are determined. First, a pronounced spatial heterogeneity is found at the DNA interface and explained via the jump model by the diversity in local DNA interfacial topographies and DNA-water H-bond interactions. While most of the hydration shell is moderately retarded with respect to the bulk, some water molecules confined in the narrow minor groove exhibit very slow dynamics. An additional source of heterogeneity is found to be caused by the DNA conformational fluctuations, which modulate the water dynamics. The groove widening aids the approach of, and the jump to, a new water H-bond partner. This temporal heterogeneity is especially strong in the minor groove, where groove width fluctuations occur on the same time scale as the water H-bond rearrangements, leading to a strong dynamical disorder. The usual simplifying assumption that hydration shell dynamics is much faster than DNA dynamics is thus not valid; our results show that biomolecular conformational fluctuations are essential to facilitate the water motions and accelerate the hydration dynamics in confined groove sites. PMID:27240107

  17. Polarimetry of nacre in iridescent shells

    NASA Astrophysics Data System (ADS)

    Metzler, R. A.; Burgess, C.; Regan, B.; Spano, S.; Galvez, E. J.

    2014-09-01

    We investigate the light transmitted or reflected from nacre (mother of pearl) taken from the iridescent shell of the bivalve Pinctad a fucata. These nacre surfaces have a rich structure, composed of aragonite crystals arranged as tablets or bricks, 5 μm wide and 400-500 nm thick, surrounded by 30nm thick organic mortar. The light reflected from these shell surfaces, or transmitted through thin polished layers, is rich in its polarization content, exhibiting a space dependent variation in the state of polarization with a high density of polarization singularities. Our goal is to use the polarization information to infer the structure of the biominerals and the role of the organic layer in determining the orientation of the crystals. In the experiments we send the light from a laser with a uniform state of polarization onto the shell, and analyze the light that is either transmitted or reflected, depending on the type of experiment, imaging it after its passage through polarization filters. We use the images from distinct filters to obtain the Stokes parameters, and hence the state of polarization, of each image point. We also construct the Mueller matrix for each imaged point, via 36 measurements. We do this for distinct physical and chemical treatments of the shell sample. Preliminary data shows that the organic layer may be responsible for organizing a multi-crystalline arrangement of aragonite tablets.

  18. BOWOOSS: bionic optimized wood shells with sustainability

    NASA Astrophysics Data System (ADS)

    Pohl, Göran

    2011-04-01

    In architecture, shell construction is used for the most efficient, large spatial structures. Until now the use of wood rather played a marginal role, implementing those examples of architecture, although this material offers manifold advantages, especially against the background of accelerating shortage of resources and increasing requirements concerning the energy balance. Regarding the implementation of shells, nature offers a wide range of suggestions. The focus of the examinations is on the shells of marine plankton, especially of diatoms, whose richness in species promises the discovery of entirely new construction principles. The project is targeting at transferring advantageous features of these organisms on industrial produced, modular wood shell structures. Currently a transfer of these structures in CAD - models is taking place, helping to perform stress analysis by computational methods. Micro as well as macro structures are the subject of diverse consideration, allowing to draw the necessary conclusions for an architectural design. The insights of these tests are the basis for the development of physical models on different scales, which are used to verify the different approaches. Another important aim which is promoted in the project is to enhance the competitiveness of timber construction. Downsizing of the prefabricated structural elements leads to considerable lower transportation costs as abnormal loads can be avoided as far as possible and means of transportation can be loaded with higher efficiency so that an important contribution to the sustainability in the field of architecture can also be made.

  19. Helium-Shell Nucleosynthesis and Extinct Radioactivities

    NASA Astrophysics Data System (ADS)

    Meyer, B. S.; The, L.-S.; Clayton, D. D.; El Eid, M. F.

    2004-03-01

    We present details of explosive nucleosynthesis in the helium-burning shell of a 25 solar mass star. We describe the production of short-lived radioactivities in this environment. We finally describe how to access the details of our calculations over the world-wide web.

  20. PEANUT SHELL FUEL FOR THE GAMBIA

    EPA Science Inventory

    The project will develop a household-scale human-powered briquette maker that will convert peanut shells into an efficient cooking fuel. The briquette maker will be designed such that it can be manufactured and used in The Gambia.

  1. Shell corrections, magic numbers, and mean field

    SciTech Connect

    Denisov, V. Yu.

    2007-02-15

    It is shown that the positions of deep local minima of shell corrections associated with magic numbers in the region of superheavy nuclei depend on the parameters of the central and spin-orbit mean-field potentials. The accuracy of nuclear-mass predictions made within various models for superheavy nuclei is analyzed.

  2. On-Shell Methods in Perturbative QCD

    SciTech Connect

    Bern, Zvi; Dixon, Lance J.; Kosower, David A.

    2007-04-25

    We review on-shell methods for computing multi-parton scattering amplitudes in perturbative QCD, utilizing their unitarity and factorization properties. We focus on aspects which are useful for the construction of one-loop amplitudes needed for phenomenological studies at the Large Hadron Collider.

  3. Continuous representation for shell models of turbulence

    NASA Astrophysics Data System (ADS)

    Mailybaev, Alexei A.

    2015-07-01

    In this work we construct and analyze continuous hydrodynamic models in one space dimension, which are induced by shell models of turbulence. After Fourier transformation, such continuous models split into an infinite number of uncoupled subsystems, which are all identical to the same shell model. The two shell models, which allow such a construction, are considered: the dyadic (Desnyansky-Novikov) model with the intershell ratio λ = 23/2 and the Sabra model of turbulence with λ = \\sqrt{2+\\sqrt{5}} ≈ 2.058 . The continuous models allow for understanding of various properties of shell model solutions and provide their interpretation in physical space. We show that the asymptotic solutions of the dyadic model with Kolmogorov scaling correspond to the shocks (discontinuities) for the induced continuous solutions in physical space, and the finite-time blowup together with its viscous regularization follow the scenario similar to the Burgers equation. For the Sabra model, we provide the physical space representation for blowup solutions and intermittent turbulent dynamics.

  4. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN...

  5. Oyster shell calcium induced parotid swelling

    PubMed Central

    Palaniappan, Muthiah; Selvarajan, Sandhiya; Srinivasamurthy, Sureshkumar; Chandrasekaran, Adithan

    2014-01-01

    A 59 year old female consumer was started on therapy with oyster shell calcium in combination with vitamin D3 and she presented with swelling below the ear, after two doses. She stopped the drug by herself and the swelling disappeared in one day. She started the drug one day after recovery and again she developed the swelling. She was advised to stop the drug with a suggestion to take lemon to enhance parotid secretion and the swelling subsided. Calcium plays major role in salivary secretion and studies have shown reduced parotid secretion in rats, deficient of vitamin D. But in humans involvement of calcium and vitamin D3 in parotid secretion is unknown. However, the patient had no history of reaction though she had previously taken vitamin D3 with calcium carbonate which was not from oyster shell. Hence, we ruled out vitamin D3 in this reaction and suspecting oyster shell calcium as a culprit. This adverse drug reaction (ADR) was assessed using World Health Organization (WHO) causality assessment, Naranjo's and Hartwig severity scales. As per WHO causality assessment scale, the ADR was classified as “certain”. This reaction was analyzed as per Naranjo's algorithm and was classified as probable. According to Hartwig's severity scale the reaction was rated as mild. Our case is an example of a mild but rare adverse effect of oyster shell calcium carbonate which is widely used. PMID:25422569

  6. Quality and Composition of Retail Shell Eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Consumers are becoming more aware of their food choices. As part of this movement, sourcing and production information is often desired for agricultural products. Furthermore, products associated with added health benefits are also becoming more common in the marketplace. The US shell egg industr...

  7. Measurement and calculation of L-shell transitions in M-shell iron ions

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, P.; Lepson, J. K.; Díaz, F.; Ishikawa, Y.; Träbert, E.

    2013-09-01

    We have made high-resolution measurements of the iron L-shell emission near 15 Å using the EBIT-I electron beam ion trap at Livermore that exhibit L-shell transitions from autoionizing levels in Fe13+, Fe14+ and Fe15+ ions. The observed L-shell iron spectra were modeled using the flexible atomic code augmented with transition energies produced by calculations based on the relativistic multi-reference Møller-Plesset (MRMP) perturbation theory, allowing us to identify multiple M-shell iron lines. Our measured values for the Fe XV emission lines are in excellent agreement with a recent measurement using the BESSY-II synchrotron but the present measurements have somewhat higher accuracy. Our MRMP calculations are compared to earlier calculations using the many-body perturbation theory approach, and we find good agreement for some but not all transitions.

  8. Cracking the Si Shell Growth in Hexagonal GaP-Si Core-Shell Nanowires.

    PubMed

    Conesa-Boj, S; Hauge, H I T; Verheijen, M A; Assali, S; Li, A; Bakkers, E P A M; Fontcuberta i Morral, A

    2015-05-13

    Semiconductor nanowires have increased the palette of possible heterostructures thanks to their more effective strain relaxation. Among these, core-shell heterostructures are much more sensitive to strain than axial ones. It is now accepted that the formation of misfit dislocations depends both on the lattice mismatch and relative dimensions of the core and the shell. Here, we show for the first time the existence of a new kind of defect in core-shell nanowires: cracks. These defects do not originate from a lattice mismatch (we demonstrate their appearance in an essentially zero-mismatch system) but from the thermal history during the growth of the nanowires. Crack defects lead to the development of secondary defects, such as type-I1 stacking faults and Frank-type dislocations. These results provide crucial information with important implications for the optimized synthesis of nanowire-based core-shell heterostructures. PMID:25922878

  9. Interior remodeling of the shell by a gastropod mollusc

    PubMed Central

    Kohn, Alan J.; Myers, Elizabeth R.; Meenakshi, V. R.

    1979-01-01

    As the Conus shell grows by spiraling of the outer lip around the axis, profound internal shell dissolution thins the walls of the protected penultimate whorl from several millimeters to <50μm. Shell material is added to the inside of the spire and the anterior part of the columella. The resulting shell has a uniformly thick last whorl and thickened spire that enhance defense against crushing predators and a greatly expanded interior living space for the animal. Images PMID:16592680

  10. Method to produce large, uniform hollow spherical shells

    DOEpatents

    Hendricks, Charles D.

    1985-01-01

    Large, uniform hollow spherical shells are produced by forming uniform size drops of heat decomposable or vaporizable material, evaporating the drops to form dried particles, coating the dried particles with a layer of shell forming material, and heating the composite particles to melt the outer layer and decompose or vaporize the inner particle to form an expanding inner gas bubble which expands the outer layer. By cycling the temperature and pressure on the hollow shells, spherical shells with uniform walls are produced.

  11. (Plasmonic Metal Core)/(Semiconductor Shell) Nanostructures

    NASA Astrophysics Data System (ADS)

    Fang, Caihong

    Over the past several years, integration of metal nanocrystals that can support localized surface plasmon has been demonstrated as one of the most promising methods to the improvement of the light-harvesting efficiency of semiconductors. Ag and Au nanocrystals have been extensively hybridized with semiconductors by either deposition or anchoring. However, metal nanocrystals tend to aggregate, reshape, detach, or grow into large nanocrystals, leading to a loss of the unique properties seen in the original nanocrystals. Fortunately, core/shell nanostructures, circumventing the aforementioned problems, have been demonstrated to exhibit superior photoactivities. To further improve the light-harvesting applications of (plasmonic metal core)/(semiconductor shell) nanostructures, it is vital to understand the plasmonic and structural evolutions during the preparation processes, design novel hybrid nanostructures, and improve their light-harvesting performances. In this thesis, I therefore studied the plasmonic and structural evolutions during the formation of (Ag core)/(Ag2S shell) nanostructures. Moreover, I also prepared (noble metal core)/(TiO2 shell) nanostructures and investigated their plasmonic properties and photon-harvesting applications. Clear understanding of the sulfidation process can enable fine control of the plasmonic properties as well as the structural composition of Ag/Ag 2S nanomaterials. Therefore, I investigated the plasmonic and structural variations during the sulfidation process of Ag nanocubes both experimentally and numerically. The sulfidation reactions were carried out at both the ensemble and single-particle levels. Electrodynamic simulations were also employed to study the variations of the plasmonic properties and plasmon modes. Both experiment and simulation results revealed that sulfidation initiates at the vertices of Ag nanocubes. Ag nanocubes are then gradually truncated and each nanocube becomes a nanosphere eventually. The cubic

  12. Searching for nova shells around cataclysmic variables

    NASA Astrophysics Data System (ADS)

    Sahman, D. I.; Dhillon, V. S.; Knigge, C.; Marsh, T. R.

    2015-08-01

    We present the results of a search for nova shells around 101 cataclysmic variables (CVs), using H α images taken with the 4.2-m William Herschel Telescope (WHT) and the 2.5-m Isaac Newton Telescope Photometric H α Survey of the Northern Galactic Plane (IPHAS). Both telescopes are located on La Palma. We concentrated our WHT search on nova-like variables, whilst our IPHAS search covered all CVs in the IPHAS footprint. We found one shell out of the 24 nova-like variables we examined. The newly discovered shell is around V1315 Aql and has a radius of ˜2.5 arcmin, indicative of a nova eruption approximately 120 yr ago. This result is consistent with the idea that the high mass-transfer rate exhibited by nova-like variables is due to enhanced irradiation of the secondary by the hot white dwarf following a recent nova eruption. The implications of our observations for the lifetime of the nova-like variable phase are discussed. We also examined four asynchronous polars, but found no new shells around any of them, so we are unable to confirm that a recent nova eruption is the cause of the asynchronicity in the white dwarf spin. We find tentative evidence of a faint shell around the dwarf nova V1363 Cyg. In addition, we find evidence for a light echo around the nova V2275 Cyg, which erupted in 2001, indicative of an earlier nova eruption ˜300 yr ago, making V2275 Cyg a possible recurrent nova.

  13. SHELL - PRESSURE VOLUME PROPERTIES OF METALLIC BELLOWS

    NASA Technical Reports Server (NTRS)

    Kiefling, L.

    1994-01-01

    A majority of the liquid-fueled rocket vehicles developed in the past have been plagued by an instability known as POGO. The POGO phenomenon involves dynamics of the vehicle structure, dynamics of the propellant in the feedline, and the engine dynamic transfer function. Each of these three items must be accurately known in order to determine stability. Metallic bellows are commonly used as segments of propellant feedlines for rocket-propelled vehicles to accommodate temperature-induced length variations, manufacturing tolerances, and gimbaling of the engines. These bellows sections deform radially and change volume when internal pressure varies, and the magnitude of such deformation is much higher than that for the straight, cylindrical segments of the line. The greater flexibility of the bellows decreases the frequency of acoustic oscillations in the line. Calculating elastic stiffness is difficult due to the radial deformation of a bellows section. SHELL was developed specifically to calculate changes in volume of a bellows due to changes in internal pressure. Input to the program consists of tables describing the material, the geometry of the convolutions and loading. The output gives displacements and volume change that can be used for POGO or waterhammer analysis. SHELL is written in standard FORTRAN 77. This program was originally developed on a Univac 1100 series computer and has been successfully implemented on IBM 370 series computers running MVS and DEC VAX series computers running VMS. The main memory requirement for running SHELL under VMS is 116K. The program source code, IBM JCL for compiling and running SHELL, and sample input are provided with the program. SHELL is available on a 9-track 1600 BPI ASCII CARD IMAGE magnetic tape. This program was developed in 1989. IBM is a trademark of International Business Machines Corporation. DEC, VAX and VMS are registered trademarks of Digital Equipment Corporation. Univac 1100 is a trademark of Unisys

  14. Porous Core-Shell Nanostructures for Catalytic Applications

    NASA Astrophysics Data System (ADS)

    Ewers, Trevor David

    Porous core-shell nanostructures have recently received much attention for their enhanced thermal stability. They show great potential in the field of catalysis, as reactant gases can diffuse in and out of the porous shell while the core particle is protected from sintering, a process in which particles coalesce to form larger particles. Sintering is a large problem in industry and is the primary cause of irreversible deactivation. Despite the obvious advantages of high thermal stability, porous core-shell nanoparticles can be developed to have additional interactive properties from the combination of the core and shell together, rather than just the core particle alone. This dissertation focuses on developing new porous core-shell systems in which both the core and shell take part in catalysis. Two types of systems are explored; (1) yolk-shell nanostructures with reducible oxide shells formed using the Kirkendall effect and (2) ceramic-based porous oxide shells formed using sol-gel chemistry. Of the Kirkendall-based systems, Au FexOy and Cu CoO were synthesized and studied for catalytic applications. Additionally, ZnO was explored as a potential shelling material. Sol-gel work focused on optimizing synthetic methods to allow for coating of small gold particles, which remains a challenge today. Mixed metal oxides were explored as a shelling material to make dual catalysts in which the product of a reaction on the core particle becomes a reactant within the shell.

  15. 41 CFR 102-85.120 - What is shell Rent?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is shell Rent? 102-85.120 Section 102-85.120 Public Contracts and Property Management Federal Property Management... GSA SPACE Rent Charges § 102-85.120 What is shell Rent? Shell Rent is that portion of GSA Rent...

  16. 46 CFR 174.225 - Hull penetrations and shell connections.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection...

  17. 46 CFR 174.225 - Hull penetrations and shell connections.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection...

  18. 46 CFR 174.225 - Hull penetrations and shell connections.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection...

  19. 46 CFR 174.225 - Hull penetrations and shell connections.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection...

  20. 46 CFR 174.225 - Hull penetrations and shell connections.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection...

  1. Imperfection sensitivity of pressured buckling of biopolymer spherical shells

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Ru, C. Q.

    2016-06-01

    Imperfection sensitivity is essential for mechanical behavior of biopolymer shells [such as ultrasound contrast agents (UCAs) and spherical viruses] characterized by high geometric heterogeneity. In this work, an imperfection sensitivity analysis is conducted based on a refined shell model recently developed for spherical biopolymer shells of high structural heterogeneity and thickness nonuniformity. The influence of related parameters (including the ratio of radius to average shell thickness, the ratio of transverse shear modulus to in-plane shear modulus, and the ratio of effective bending thickness to average shell thickness) on imperfection sensitivity is examined for pressured buckling. Our results show that the ratio of effective bending thickness to average shell thickness has a major effect on the imperfection sensitivity, while the effect of the ratio of transverse shear modulus to in-plane shear modulus is usually negligible. For example, with physically realistic parameters for typical imperfect spherical biopolymer shells, the present model predicts that actual maximum external pressure could be reduced to as low as 60% of that of a perfect UCA spherical shell or 55%-65% of that of a perfect spherical virus shell, respectively. The moderate imperfection sensitivity of spherical biopolymer shells with physically realistic imperfection is largely attributed to the fact that biopolymer shells are relatively thicker (defined by smaller radius-to-thickness ratio) and therefore practically realistic imperfection amplitude normalized by thickness is very small as compared to that of classical elastic thin shells which have much larger radius-to-thickness ratio.

  2. Pseudo-Symmetry and Majorana Operators in pf-Shell

    SciTech Connect

    Valencia, J. P.; Wu, H. C.

    2007-10-26

    The Majorana operator of the pseudo ds-shell preserves the SU-tilde(4) symmetry, and in a unified manner it reproduces reasonably well the ground state energies of the nine nuclei in this shell. The study of {beta} decay in the same shell provides further support for the SU-tilde(4) symmetry.

  3. Leathery Hull Peanuts – Effect on Shelling Performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When shelling peanuts from the 2012 peanut crop, various shellers experienced diminished shelling plant throughput when shelling peanuts harvested from isolated geographical regions. Shellers reported a reduction of 25-30% throughput of the first stage sheller bank with significant increases in spli...

  4. Shells. Modified Primary. Revised. Anchorage School District Elementary Science Program.

    ERIC Educational Resources Information Center

    Defendorf, Jean, Ed.

    This publication provides information and activities for teaching about seashells and process skills including observing, classifying, collecting and interpreting data, inferring, measuring, and predicting. There are 10 lessons. Lessons 1 through 5 deal with an introduction to shells, why animals have shells, observing and classifying shells, the…

  5. Glass shell manufacturing in space. [residual gases in spherical shells made from metal-organic gels

    NASA Technical Reports Server (NTRS)

    Nolen, R. J.; Ebner, M. A.; Downs, R. L.

    1980-01-01

    Residual gases always found in glass shells are CO2, O2 and N2. In those cases where high water vapor pressure is maintained in the furnace, water is also found in the shells. Other evidence for the existence of water in shells is the presence of water-induced surface weathering of the interior shell surface. Water and CO2 are the predominant volatiles generated by the pyrolysis of both inorganic and hydrolyzed metal-organic gels. The pyrolysates of unhydrolyzed metal-organic gels also contain, in addition to water and CO2, significant levels of organic volatiles, such as ethanol and some hydrocarbons; on complete oxidation, these produce CO2 and water as well. Water is most likely the initial blowing agent, it is produced copiously during the initial stages of heating. In the later stages, CO2 becomes the dominant gas as H2O is lost at increasing rates. Water in the shell arises mainly from gel dehydration, CO2 by sodium bicarbonate/carbonate decomposition and carbon oxidation, and O2 and N2 by permeation of the ambient furnace air through the molten shell wall.

  6. Shell matrix proteins of the clam, Mya truncata: Roles beyond shell formation through proteomic study.

    PubMed

    Arivalagan, Jaison; Marie, Benjamin; Sleight, Victoria A; Clark, Melody S; Berland, Sophie; Marie, Arul

    2016-06-01

    Mya truncata, a soft shell clam, is presented as a new model to study biomineralization through a proteomics approach. In this study, the shell and mantle tissue were analysed in order to retrieve knowledge about the secretion of shell matrix proteins (SMPs). Out of 67 and 127 shell and mantle proteins respectively, 16 were found in both shell and mantle. Bioinformatic analysis of SMP sequences for domain prediction revealed the presence of several new domains such as fucolectin tachylectin-4 pentraxin-1 (FTP), scavenger receptor, alpha-2-macroglobulin (α2 M), lipocalin and myosin tail along with previously reported SMP domains such as chitinase, carbonic anhydrase, tyrosinase, sushi, and chitin binding. Interestingly, these newly predicted domains are attributed with molecular functions other than biomineralization. These findings suggest that shells may not only act as protective armour from predatory action, but could also actively be related to other functions such as immunity. In this context, the roles of SMPs in biomineralization need to be looked in a new perspective. PMID:27068305

  7. Scattering amplitudes with off-shell quarks

    NASA Astrophysics Data System (ADS)

    van Hameren, A.; Kutak, K.; Salwa, T.

    2013-11-01

    We present a prescription to calculate manifestly gauge invariant tree-level scattering amplitudes for arbitrary scattering processes with off-shell initial-state quarks within the kinematics of high-energy scattering. Consider the embedding of the process, in which the off-shell u-quark is replaced by an auxiliary quark qA, and an auxiliary photon γA is added in final state. The momentum flow is as if qA carries momentum k1 and the momentum of γA is identical to 0. γA only interacts via Eq. (3), and qA further only interacts with gluons via normal quark-gluon vertices. qA-line propagators are interpreted as iℓ̸1/(2ℓ1ṡp), and are diagonal in color space. Sum the squared amplitude over helicities of the auxiliary photon. For one helicity, simultaneously assign to the external qA-quark and to γA the spinor and polarization vector |ℓ1], {<ℓ1|γμ|ℓ2]}/{√{2}[ℓ1|ℓ2]}, and for the other helicity assign |ℓ1>, {<ℓ2|γμ|ℓ1]}/{√{2}<ℓ2|ℓ1>}. Multiply the amplitude with √{-x1k12/2}. For the rest, normal Feynman rules apply.Some remarks are at order. Regarding the momentum flow, we stress, as in [20], that momentum components proportional to k1 do not contribute in the eikonal propagators, and there is a freedom in the choice of the momenta flowing through qA-lines.Regarding the sum over helicities, one might argue that only one of them leads to a non-zero result for given helicity of the final-state quark, but there may, for example, be several identical such quarks in the final state with different helicities.In case of more than one quark in the final state with the same flavor as the off-shell quark, the rules as such admit graphs with γA-propagators. These must be omitted. They do not survive the limit Λ→∞ in the derivation, since the γA-propagators are suppressed by 1/Λ.The rules regarding the qA-line could be elaborated further like in [20], leading to simplified vertices for gluons attached to this line and reducing the

  8. Shells on lattice-mismatched colloidal spheres, cubes, and peanuts

    NASA Astrophysics Data System (ADS)

    Sindoro, Melinda; Granick, Steve

    2015-03-01

    Cavities form spontaneously due to geometrical frustration when crystalline shells is gradually grown on non-linear surfaces. This we conclude experimentally from growing lattice mismatched shells on colloidal spheres, cubes, and peanuts, all of them providing different local curvature. According to the core shape, the underlying interfacial curvature promotes different cavity formation which we can follow over time. The resulting spatio-temporal heterogeneity adds up to a propagation of an increasingly strong mechanical stress at the core-shell interface, inducing core-shells transformation to yolk-shells.

  9. Accurate stress resultants equations for laminated composite deep thick shells

    SciTech Connect

    Qatu, M.S.

    1995-11-01

    This paper derives accurate equations for the normal and shear force as well as bending and twisting moment resultants for laminated composite deep, thick shells. The stress resultant equations for laminated composite thick shells are shown to be different from those of plates. This is due to the fact the stresses over the thickness of the shell have to be integrated on a trapezoidal-like shell element to obtain the stress resultants. Numerical results are obtained and showed that accurate stress resultants are needed for laminated composite deep thick shells, especially if the curvature is not spherical.

  10. Sound transmission into a laminated composite cylindrical shell

    NASA Technical Reports Server (NTRS)

    Koval, L. R.

    1980-01-01

    In the context of the transmission of airborne noise into an aircraft fuselage, a mathematical model is presented for the transmission of an oblique plane sound wave into a laminated composite circular cylindrical shell. Numerical results are obtained for geometry typical of a narrow-bodied jet transport. Results indicate that from the viewpoint of noise attenuation on laminated composite shell does not appear to offer any significant advantage over an aluminum shell. However, the transmission loss of a laminated composite shell is sensitive to the orientation of the fibers and this suggests the possibility of using a laminated composite shell to tailor the noise attenuation characteristics to meet a specific need.

  11. Method of fabricating nested shells and resulting product

    DOEpatents

    Henderson, Timothy M.; Kool, Lawrence B.

    1982-01-01

    A multiple shell structure and a method of manufacturing such structure wherein a hollow glass microsphere is surface treated in an organosilane solution so as to render the shell outer surface hydrophobic. The surface treated glass shell is then suspended in the oil phase of an oil-aqueous phase dispersion. The oil phase includes an organic film-forming monomer, a polymerization initiator and a blowing agent. A polymeric film forms at each phase boundary of the dispersion and is then expanded in a blowing operation so as to form an outer homogeneously integral monocellular substantially spherical thermoplastic shell encapsulating an inner glass shell of lesser diameter.

  12. Ocean acidification alters the material properties of Mytilus edulis shells.

    PubMed

    Fitzer, Susan C; Zhu, Wenzhong; Tanner, K Elizabeth; Phoenix, Vernon R; Kamenos, Nicholas A; Cusack, Maggie

    2015-02-01

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature. PMID:25540244

  13. Ocean acidification alters the material properties of Mytilus edulis shells

    PubMed Central

    Fitzer, Susan C.; Zhu, Wenzhong; Tanner, K. Elizabeth; Phoenix, Vernon R.; Kamenos, Nicholas A.; Cusack, Maggie

    2015-01-01

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature. PMID:25540244

  14. A Method for Quantifying, Visualising, and Analysing Gastropod Shell Form

    PubMed Central

    Liew, Thor-Seng; Schilthuizen, Menno

    2016-01-01

    Quantitative analysis of organismal form is an important component for almost every branch of biology. Although generally considered an easily-measurable structure, the quantification of gastropod shell form is still a challenge because many shells lack homologous structures and have a spiral form that is difficult to capture with linear measurements. In view of this, we adopt the idea of theoretical modelling of shell form, in which the shell form is the product of aperture ontogeny profiles in terms of aperture growth trajectory that is quantified as curvature and torsion, and of aperture form that is represented by size and shape. We develop a workflow for the analysis of shell forms based on the aperture ontogeny profile, starting from the procedure of data preparation (retopologising the shell model), via data acquisition (calculation of aperture growth trajectory, aperture form and ontogeny axis), and data presentation (qualitative comparison between shell forms) and ending with data analysis (quantitative comparison between shell forms). We evaluate our methods on representative shells of the genera Opisthostoma and Plectostoma, which exhibit great variability in shell form. The outcome suggests that our method is a robust, reproducible, and versatile approach for the analysis of shell form. Finally, we propose several potential applications of our methods in functional morphology, theoretical modelling, taxonomy, and evolutionary biology. PMID:27280463

  15. A predictive model of shell morphology in CdSe/CdS core/shell quantum dots

    NASA Astrophysics Data System (ADS)

    Gong, Ke; Kelley, David F.

    2014-11-01

    Lattice mismatch in core/shell nanoparticles occurs when the core and shell materials have different lattice parameters. When there is a significant lattice mismatch, a coherent core-shell interface results in substantial lattice strain energy, which can affect the shell morphology. The shell can be of uniform thickness or can be rough, having thin and thick regions. A smooth shell minimizes the surface energy at the expense of increased lattice strain energy and a rough shell does the opposite. A quantitative treatment of the lattice strain energy in determining the shell morphology of CdSe/CdS core/shell nanoparticles is presented here. We use the inhomogeneity in hole tunneling rates through the shell to adsorbed hole acceptors to quantify the extent of shell thickness inhomogeneity. The results can be understood in terms of a model based on elastic continuum calculations, which indicate that the lattice strain energy depends on both core size and shell thickness. The model assumes thermodynamic equilibrium, i.e., that the shell morphology corresponds to a minimum total (lattice strain plus surface) energy. Comparison with the experimental results indicates that CdSe/CdS nanoparticles undergo an abrupt transition from smooth to rough shells when the total lattice strain energy exceeds about 27 eV or the strain energy density exceeds 0.59 eV/nm2. We also find that the predictions of this model are not followed for CdSe/CdS nanoparticles when the shell is deposited at very low temperature and therefore equilibrium is not established.

  16. A predictive model of shell morphology in CdSe/CdS core/shell quantum dots

    SciTech Connect

    Gong, Ke; Kelley, David F.

    2014-11-21

    Lattice mismatch in core/shell nanoparticles occurs when the core and shell materials have different lattice parameters. When there is a significant lattice mismatch, a coherent core-shell interface results in substantial lattice strain energy, which can affect the shell morphology. The shell can be of uniform thickness or can be rough, having thin and thick regions. A smooth shell minimizes the surface energy at the expense of increased lattice strain energy and a rough shell does the opposite. A quantitative treatment of the lattice strain energy in determining the shell morphology of CdSe/CdS core/shell nanoparticles is presented here. We use the inhomogeneity in hole tunneling rates through the shell to adsorbed hole acceptors to quantify the extent of shell thickness inhomogeneity. The results can be understood in terms of a model based on elastic continuum calculations, which indicate that the lattice strain energy depends on both core size and shell thickness. The model assumes thermodynamic equilibrium, i.e., that the shell morphology corresponds to a minimum total (lattice strain plus surface) energy. Comparison with the experimental results indicates that CdSe/CdS nanoparticles undergo an abrupt transition from smooth to rough shells when the total lattice strain energy exceeds about 27 eV or the strain energy density exceeds 0.59 eV/nm{sup 2}. We also find that the predictions of this model are not followed for CdSe/CdS nanoparticles when the shell is deposited at very low temperature and therefore equilibrium is not established.

  17. Theoretical and Observational Aspects of Expanding H I Shells

    NASA Astrophysics Data System (ADS)

    Cazzolato, François; Pineault, Serge

    2005-06-01

    We have modeled H I shells expanding into a homogeneous medium in order to explain some of their observational peculiarities. Such peculiarities include difficult-to-observe caps, the presence of stationary rings, expansion velocity determination problems, inaccurate mass measurements, and a systematic discrepancy between H I missing masses and shell masses. Velocity dispersion within the shell, in the form of either thermal or turbulent motions, has been found to be the likely major cause for the absence of observable caps and the presence of stationary rings, hence explaining the apparent lack of ring transition. We discuss different methods generally used to calculate H I shell masses and show that, if one does not take into account the varying shape of the H I background local to the shell, shell masses are likely to be underestimated by a significant factor whose value depends on the relative shell thickness and the ratio of the dispersion to the expansion velocity.

  18. Geometrically nonlinear analysis of layered composite plates and shells

    NASA Technical Reports Server (NTRS)

    Chao, W. C.; Reddy, J. N.

    1983-01-01

    A degenerated three dimensional finite element, based on the incremental total Lagrangian formulation of a three dimensional layered anisotropic medium was developed. Its use in the geometrically nonlinear, static and dynamic, analysis of layered composite plates and shells is demonstrated. A two dimenisonal finite element based on the Sanders shell theory with the von Karman (nonlinear) strains was developed. It is shown that the deflections obtained by the 2D shell element deviate from those obtained by the more accurate 3D element for deep shells. The 3D degenerated element can be used to model general shells that are not necessarily doubly curved. The 3D degenerated element is computationally more demanding than the 2D shell theory element for a given problem. It is found that the 3D element is an efficient element for the analysis of layered composite plates and shells undergoing large displacements and transient motion.

  19. Vibration of cylindrical shells of bimodulus composite materials

    NASA Astrophysics Data System (ADS)

    Bert, C. W.; Kumar, M.

    1982-03-01

    A theory is formulated for the small amplitude free vibration of thick, circular cylindrical shells laminated of bimodulus composite materials, which have different elastic properties depending upon whether the fiber-direction strain is tensile or compressive. The theory used is the dynamic, shear deformable (moderately thick shell) analog of the Sanders best first approximation thin shell theory. By means of tracers, the analysis can be reduced to that of various simpler shell theories, namely Love's first approximation, and Donnell's shallow shell theory. As an example of the application of the theory, a closed form solution is presented for a freely supported panel or complete shell. To validate the analysis, numerical results are compared with existing results for various special cases. Also, the effects of the various shell theories, thickness shear flexibility, and bimodulus action are investigated.

  20. Soft template synthesis of yolk/silica shell particles.

    PubMed

    Wu, Xue-Jun; Xu, Dongsheng

    2010-04-01

    Yolk/shell particles possess a unique structure that is composed of hollow shells that encapsulate other particles but with an interstitial space between them. These structures are different from core/shell particles in that the core particles are freely movable in the shell. Yolk/shell particles combine the properties of each component, and can find potential applications in catalysis, lithium ion batteries, and biosensors. In this Research News article, a soft-template-assisted method for the preparation of yolk/silica shell particles is presented. The demonstrated method is simple and general, and can produce hollow silica spheres incorporated with different particles independent of their diameters, geometry, and composition. Furthermore, yolk/mesoporous silica shell particles and multishelled particles are also prepared through optimization of the experimental conditions. Finally, potential applications of these particles are discussed. PMID:20437501

  1. Cloaking by shells with radially inhomogeneous anisotropic permittivity.

    PubMed

    Reshetnyak, V Yu; Pinkevych, I P; Sluckin, T J; Evans, D R

    2016-01-25

    We model electromagnetic cloaking of a spherical or cylindrical nanoparticle enclosed by an optically anisotropic and optically inhomogeneous symmetric shell, by examining its electric response in a quasi-static uniform electric field. When the components of the shell permittivity are radially anisotropic and power-law dependent (ε~r(m)) whereris distance to the shell center, and m a positive or negative exponent which can be varied), the problem is analytically tractable. Formulas are calculated for the degree of cloaking in the general case, allowing the determination of a dielectric condition for the shells to be used as an invisibility cloak. Ideal cloaking is known to require that homogeneous shells exhibit an infinite ratio of tangential and radial components of the shell permittivity, but for radially inhomogeneous shells ideal cloaking can occur even for finite values of this ratio. PMID:26832575

  2. Determination of shell content in palm kernel cake.

    PubMed

    Siew, W L

    1996-01-01

    A method for determining shell in palm kernel cake (PKC) is described. This simple and rapid method requires little pretreatment compared with the method currently used in PKC trade, in which the sample undergoes defatting, acid and alkali digestion, and washing, before a chloroform-alcohol solution is used to separate the shells. In the proposed method, only defatting the sample is required. The shells are separated by the density difference between the shell and PKC in a potassium iodide solution. Recoveries of at least 93% were obtained, and the correlation coefficient between the actual shell content and the determined shell content was 0.999, with gradients of 0.97 and 0.98 for fine and coarse shell, respectively. PMID:8620115

  3. Symmetries and deformations in the spherical shell model

    NASA Astrophysics Data System (ADS)

    Van Isacker, P.; Pittel, S.

    2016-02-01

    We discuss symmetries of the spherical shell model that make contact with the geometric collective model of Bohr and Mottelson. The most celebrated symmetry of this kind is SU(3), which is the basis of Elliott’s model of rotation. It corresponds to a deformed mean field induced by a quadrupole interaction in a single major oscillator shell N and can be generalized to include several major shells. As such, Elliott’s SU(3) model establishes the link between the spherical shell model and the (quadrupole component of the) geometric collective model. We introduce the analogue symmetry induced by an octupole interaction in two major oscillator shells N-1 and N, leading to an octupole-deformed solution of the spherical shell model. We show that in the limit of large oscillator shells, N\\to ∞ , the algebraic octupole interaction tends to that of the geometric collective model.

  4. Exchange bias in Ag/FeCo/Ag core/shell/shell nanoparticles due to partial oxidation of FeCo intermediate shell

    NASA Astrophysics Data System (ADS)

    Takahashi, Mari; Mohan, Priyank; Mott, Derrick M.; Maenosono, Shinya

    2016-03-01

    Recently we developed magnetic-plasmonic Ag/FeCo/Ag core/shell/shell nanoparticles for the purpose of biological applications. In these heterostructured nanoparticles, exchange bias is observed as a result of the formation of an interface between ferromagnetic FeCo and antiferromagnetic CoxFe1-xO due to the partial oxidation of the FeCo intermediate shell. In this study we thoroughly characterized the surface oxide layer of the FeCo shell by XPS, XRD and SQUID magnetometer.

  5. Spherical nematic shells with a threefold valence.

    PubMed

    Koning, Vinzenz; Lopez-Leon, Teresa; Darmon, Alexandre; Fernandez-Nieves, Alberto; Vitelli, V

    2016-07-01

    We present a theoretical study of the energetics of thin nematic shells with two charge-one-half defects and one charge-one defect. We determine the optimal arrangement: the defects are located on a great circle at the vertices of an isosceles triangle with angles of 66^{∘} at the charge-one-half defects and a distinct angle of 48^{∘}, consistent with experimental findings. We also analyze thermal fluctuations around this ground state and estimate the energy as a function of thickness. We find that the energy of the three-defect shell is close to the energy of other known configurations having two charge-one and four charge-one-half defects. This finding, together with the large energy barriers separating one configuration from the others, explains their observation in experiments as well as their long-time stability. PMID:27575194

  6. Spherical nematic shells with a threefold valence

    NASA Astrophysics Data System (ADS)

    Koning, Vinzenz; Lopez-Leon, Teresa; Darmon, Alexandre; Fernandez-Nieves, Alberto; Vitelli, V.

    2016-07-01

    We present a theoretical study of the energetics of thin nematic shells with two charge-one-half defects and one charge-one defect. We determine the optimal arrangement: the defects are located on a great circle at the vertices of an isosceles triangle with angles of 66∘ at the charge-one-half defects and a distinct angle of 48∘, consistent with experimental findings. We also analyze thermal fluctuations around this ground state and estimate the energy as a function of thickness. We find that the energy of the three-defect shell is close to the energy of other known configurations having two charge-one and four charge-one-half defects. This finding, together with the large energy barriers separating one configuration from the others, explains their observation in experiments as well as their long-time stability.

  7. No-Core Shell Model and Reactions

    SciTech Connect

    Navratil, Petr; Ormand, W. Erich; Caurier, Etienne; Bertulani, Carlos

    2005-10-14

    There has been a significant progress in ab initio approaches to the structure of light nuclei. Starting from realistic two- and three-nucleon interactions the ab initio no-core shell model (NCSM) can predict low-lying levels in p-shell nuclei. It is a challenging task to extend ab initio methods to describe nuclear reactions. In this contribution, we present a brief overview of the NCSM with examples of recent applications as well as the first steps taken toward nuclear reaction applications. In particular, we discuss cross section calculations of p+6Li and 6He+p scattering as well as a calculation of the astrophysically important 7Be(p,{gamma})8B S-factor.

  8. Transverse shear stiffness of laminated anisotropic shells

    NASA Technical Reports Server (NTRS)

    Cohen, G. A.

    1978-01-01

    Equations are derived for the transverse shear stiffness of laminated anisotropic shells. Without making assumptions for thickness distribution for either transverse shear stresses or strains, constitutive equations for the transverse shear deformation theory of anisotropic heterogeneous shells are found. The equations are based on Taylor series expansions about a generic point for stress resultants and couples, identically satisfying plate equilibrium equations. These equations are used to find statically correct expressions for in-surface stresses, transverse shear stresses, and the area density of transverse shear strain energy, in terms of transverse shear stress resultants and redundants. The application of Castigliano's theorem of least work minimizes shear strain energy with respect to the redundants. Examples are presented for several laminated walls. Good agreement is found between the results and those of exact three-dimensional elasticity solutions for the cylindrical bending of a plate.

  9. Nuclear level density: Shell-model approach

    NASA Astrophysics Data System (ADS)

    Sen'kov, Roman; Zelevinsky, Vladimir

    2016-06-01

    Knowledge of the nuclear level density is necessary for understanding various reactions, including those in the stellar environment. Usually the combinatorics of a Fermi gas plus pairing is used for finding the level density. Recently a practical algorithm avoiding diagonalization of huge matrices was developed for calculating the density of many-body nuclear energy levels with certain quantum numbers for a full shell-model Hamiltonian. The underlying physics is that of quantum chaos and intrinsic thermalization in a closed system of interacting particles. We briefly explain this algorithm and, when possible, demonstrate the agreement of the results with those derived from exact diagonalization. The resulting level density is much smoother than that coming from conventional mean-field combinatorics. We study the role of various components of residual interactions in the process of thermalization, stressing the influence of incoherent collision-like processes. The shell-model results for the traditionally used parameters are also compared with standard phenomenological approaches.

  10. Practical applications of substructuring in shell dynamics

    SciTech Connect

    Sane, A.D.; Bitner, J.L.

    1982-01-01

    Transient dynamic stress analysis of large shell structures is often required in many industrial designs. The asymmetry features of the structure often require a full three dimensional analysis. The difficulties experienced in performing the dynamic analysis of such large and complex structures result from economic feasibility and limitations on the available computer core memory. Substructuring techniques provide a way of overcoming these difficulties. The advantages and features associated with substructuring methods are discussed in general terms. The technique is then applied to perform a transient dynamic analysis of a typical shell structure. The discussion of the example problem focused to highlight the economy, flexibility and the data handling aspects of this method. The example problem demonstrates that this method can be applied with success to a wide range of structural dynamic problems and results in significant cost savings.

  11. Gravity and on-shell probe actions

    NASA Astrophysics Data System (ADS)

    Ferrari, Frank; Rovai, Antonin

    2016-08-01

    In any gravitational theory and in a wide class of background space-times, we argue that there exists a simple, yet profound, relation between the on-shell Euclidean gravitational action and the on-shell Euclidean action of probes. The probes can be, for instance, charged particles or branes. The relation is tightly related to the thermodynamic nature of gravity. We provide precise checks of the relation in several examples, which include both asymptotically flat and asymptotically AdS space-times, with particle, D-brane and M-brane probes. Perfect consistency is found in all cases, including in a highly non-trivial example including α'-corrections.

  12. Shell model for warm rotating nuclei

    SciTech Connect

    Matsuo, M.; Yoshida, K.; Dossing, T.

    1996-12-31

    Utilizing a shell model which combines the cranked Nilsson mean-field and the residual surface and volume delta two-body forces, the authors discuss the onset of rotational damping in normal- and super-deformed nuclei. Calculation for a typical normal deformed nucleus {sup 168}Yb indicates that the rotational damping sets in at around 0.8 MeV above the yrast line, and about 30 rotational bands of various length exists at a given rotational frequency, in overall agreement with experimental findings. It is predicted that the onset of rotational damping changes significantly in different superdeformed nuclei due to the variety of the shell gaps and single-particle orbits associated with the superdeformed mean-field.

  13. Robust Microcompartments with Hydrophobically Gated Shells.

    PubMed

    Sander, Jonathan S; Steinacher, Mathias; Loiseau, Eve; Demirörs, Ahmet F; Zanini, Michele; Isa, Lucio; Studart, André R

    2015-06-30

    We report on robust synthetic microcompartments with hydrophobically gated shells that can reversibly swell and contract multiple times upon external stimuli. The gating mechanism relies on a hydrophilic-hydrophobic transition of a polymer layer that is grafted on inorganic colloidosomes using atom-transfer radical polymerization. As a result of such a transition, the initially tight hydrophobic shell becomes permeable to the diffusion of hydrophilic solutes across the microcompartment walls. Surprisingly, the microcompartments are strong enough to retain their spherical shape during several swelling and contraction cycles. This provides a powerful alternative platform for the creation of synthetic microreactors and protocells that interact with the surrounding media through a simple gating mechanism and are sufficiently robust for further engineering of increasingly complex compartmentalized structures. PMID:26061672

  14. Geodesic defect anchoring on nematic shells.

    PubMed

    Mirantsev, Leonid V; Sonnet, André M; Virga, Epifanio G

    2012-08-01

    Nematic shells are colloidal particles coated with nematic liquid crystal molecules, which may freely glide and rotate on the colloid's surface while keeping their long axis on the local tangent plane. Molecular dynamics simulations on a nanoscopic spherical shell indicate that under appropriate adhesion conditions for the molecules on the equator, the equilibrium nematic texture exhibits at each pole a pair of +1/2 defects so close to one another to be treated as one +1 defect. Spirals connect the polar defects, though the continuum limit of the interaction potential would not feature any elastic anisotropy. A molecular averaging justifies an anchoring defect energy that feels the geodesics emanating from the defect. All our observations are explained by such a geodesic anchoring, which vanishes on flat manifolds. PMID:23005713

  15. Multifunctional composite core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Wei, Suying; Wang, Qiang; Zhu, Jiahua; Sun, Luyi; Lin, Hongfei; Guo, Zhanhu

    2011-11-01

    In this review paper, the state-of-the-art knowledge of the core-shell multifunctional nanoparticles (MNPs), especially with unique physiochemical properties, is presented. The synthesis methods were summarized from the aspects of both the advantages and the demerits. The core includes the inexpensive and easily oxidized metals and the noble shells include the relatively noble metals, carbon, silica, other oxides, and polymers. The properties including magnetic, optical, anti-corrosion and the surface chemistry of the NPs are thoroughly reviewed. The current status of the applications is reviewed with the detailed examples including the catalysis, giant magnetoresistance (GMR) sensing, electromagnetic interface shielding or microwave absorption, biomedical drug delivery, and the environmental remediation.

  16. No-Core Shell Model and Reactions

    SciTech Connect

    Navratil, P; Ormand, W E; Caurier, E; Bertulani, C

    2005-04-29

    There has been a significant progress in ab initio approaches to the structure of light nuclei. Starting from realistic two- and three-nucleon interactions the ab initio no-core shell model (NCSM) can predict low-lying levels in p-shell nuclei. It is a challenging task to extend ab initio methods to describe nuclear reactions. In this contribution, we present a brief overview of the NCSM with examples of recent applications as well as the first steps taken toward nuclear reaction applications. In particular, we discuss cross section calculations of p+{sup 6}Li and {sup 6}He+p scattering as well as a calculation of the astrophysically important {sup 7}Be(p, {gamma}){sup 8}B S-factor.

  17. Shape coexistence: the shell model view

    NASA Astrophysics Data System (ADS)

    Poves, A.

    2016-02-01

    We shall discuss the meaning of the ‘nuclear shape’ in the laboratory frame proper to the spherical shell model. A brief historical promenade will bring us from Elliott’s SU3 breakthrough to today’s large scale shell model calculations. A section is devoted to the algebraic model which extends drastically the field of applicability of Elliot’s SU3, providing a precious heuristic guidance for the exploration of collectivity in the nuclear chart. Shape coexistence and shape mixing will be shown to occur as the result of the competition between the main actors in the nuclear dynamics; the spherical mean field, and the pairing and quadrupole-quadrupole interactions. These ideas will be illustrated with examples in magic nuclei (40Ca and 68Ni); neutron rich semi-magic (32Mg, and 64Cr); and in proton rich N = Z (72Kr).

  18. Understanding nuclei in the upper sd - shell

    SciTech Connect

    Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta; Kshetri, Ritesh; Sarkar, S.

    2014-08-14

    Nuclei in the upper-sd shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A ≃ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.

  19. Nonlinear axisymmetric flexural vibration of spherical shells

    NASA Technical Reports Server (NTRS)

    Kunieda, H.

    1972-01-01

    Axisymmetric responses are presented of a nonshallow thin-walled spherical shell on the basis of nonlinear bending theory. An ordinary differential equation with nonlinearity of quadratic as well as cubic terms associated with variable time is derived. The derivation is based on the assumption that the deflection mode is the sum of four Legendre polynomials, and the Galerkin procedure is applied. The equation is solved by asymptotic expansion, and a first approximate solution is adopted. Unstable regions of this solution are discussed.

  20. Thin-shell wormholes: Linearization stability

    SciTech Connect

    Poisson, E.; Visser, M.

    1995-12-15

    The class of spherically symmetric thin-shell wormholes provides a particularly elegant collection of exemplars for the study of traversable Lorentzian wormholes. In the present paper we consider linearized (spherically symmetric) perturbations around some assumed static solution of the Einstein field equations. This permits us to relate stability issues to the (linearized) equation of state of the exotic matter which is located at the wormhole throat. {copyright} 1995 The American Physical Society.

  1. On Closed Shells in Nuclei. II

    DOE R&D Accomplishments Database

    Mayer, M. G.

    1949-04-01

    Discussion on the use of spins and magnetic moments of the even-odd nuclei by Feenberg and Nordheim to determine the angular momentum of the eigenfunction of the odd particle; discussion of prevalence of isomerism in certain regions of the isotope chart; tabulated data on levels of square well potential, spectroscopic levels, spin term, number of states, shells and known spins and orbital assignments.

  2. Shell Measuring Machine. History and Status Report

    SciTech Connect

    Birchler, Wilbur D.; Fresquez, Philip R.

    2000-06-01

    Commercialization of the Ring Rotacon Shell Measuring Machine project is a CRADA (NO. LA98C10358) between The University of California (Los Alamos National Laboratory) and Moore Tool Company, Bridgeport, CT. The actual work started on this CRADA in December of 1998. Several meetings were held with the interested parties (Los Alamos, Oak Ridge, Moore Tool, and the University of North Carolina). The results of these meetings were that the original Ring Rotacon did not measure up to the requirements of the Department of Energy and private industry, and a new configuration was investigated. This new configuration (Shell Measuring Machine [SMM]) much better fits the needs of all parties. The work accomplished on the Shell Measuring Machine in FY 99 includes the following; Specifications for size and weight were developed; Performance error budgets were established; Designs were developed; Analyses were performed (stiffness and natural frequency); Existing part designs were compared to the working SMM volume; Peer reviews were conducted; Controller requirements were studied; Fixture requirements were evaluated; and Machine motions were analyzed. The consensus of the Peer Review Committee was that the new configuration has the potential to satisfy the shell inspection needs of Department of Energy as well as several commercial customers. They recommended that more analyses be performed on error budgets, structural stiffness, natural frequency, and thermal effects and that operational processes be developed. Several design issues need to be addressed. They are the type of bearings utilized to support the tables (air bearings or mechanical roller type bearings), the selection of the probes, the design of the probe sliding mechanisms, and the design of the upper table positioning mechanism. Each item has several possible solutions, and more work is required to obtain the best design. This report includes the background and technical objectives; minutes of the working

  3. Jess, the Java expert system shell

    SciTech Connect

    Friedman-Hill, E.J.

    1997-11-01

    This report describes Jess, a clone of the popular CLIPS expert system shell written entirely in Java. Jess supports the development of rule-based expert systems which can be tightly coupled to code written in the powerful, portable Java language. The syntax of the Jess language is discussed, and a comprehensive list of supported functions is presented. A guide to extending Jess by writing Java code is also included.

  4. Fossil dust shells around luminous supergiants

    NASA Technical Reports Server (NTRS)

    Stothers, R.

    1975-01-01

    The observed frequency with which infrared excesses appear in F, G, and K supergiants of luminosity class Ia supports the idea that these excesses arise in a 'fossil' circumstellar dust shell that was formed during a prior M-super-giant phase of evolution. The required leftward evolution of the star on the H-R diagram would then imply that the Ledoux, rather than the Schwarzschild, criterion for convective mixing is the correct criterion to use in stellar evolution calculations.

  5. The creation of AGB fallback shells

    NASA Astrophysics Data System (ADS)

    Chen, Zhuo; Frank, Adam; Blackman, Eric G.; Nordhaus, Jason

    2016-04-01

    The possibility that mass ejected during Asymptotic Giant Branch (AGB) stellar evolution phases falls back towards the star has been suggested in applications ranging from the formation of accretion discs to the powering of late-thermal pulses. In this paper, we seek to explicate the properties of fallback flow trajectories from mass-loss events. We focus on a transient phase of mass ejection with sub-escape speeds, followed by a phase of a typical AGB wind. We solve the problem using both hydrodynamic simulations and a simplified one-dimensional analytic model that matches the simulations. For a given set of initial wind characteristics, we find a critical shell velocity that distinguishes between `shell fallback' and `shell escape'. We discuss the relevance of our results for both single and binary AGB stars. In particular, we discuss how our results help to frame further studies of fallback as a mechanism for forming the substantial population of observed post-AGB stars with dusty discs.

  6. Gas distribution and starbursts in shell galaxies

    NASA Technical Reports Server (NTRS)

    Weil, Melinda L.; Hernquist, Lars

    1993-01-01

    Detailed maps of most elliptical galaxies reveal that, whereas the greatest part of their luminous mass originates from a smooth distribution with a surface brightness approximated by a de Vaucouleurs law, a small percentage of their light is contributed by low surface brightness distortions termed 'fine structures'. The sharp-edged features called 'shells' are successfully reproduced by merger and infall models involving accretion from less massive companions. In this context, dwarf spheroidal and compact disk galaxies are likely progenitors of these stellar phenomena. However, it is probable that the sources of shell-forming material also contain significant amounts of gas. This component may play an important role in constraining the formation and evolution of shell galaxies. To investigate the effects of the gaseous component, numerical simulations were performed to study the tidal disruption of dwarf galaxies containing both gas and stars by more massive primaries, and the evolution of the ensuing debris. The calculations were performed with a hybrid N-body/hydrodynamics code. Collisionless matter is evolved using a conventional N-body technique and gas is treated using smoothed particle hydrodynamics in which self-gravitating fluid elements are represented as particles evolving according to Lagrangian hydrodynamic equations. An isothermal equation of state is employed so the gas remains at a temperature 104 K. Owing to the large mass ratio between the primary and companion, the primary is modeled as a rigid potential and the self-gravity of both galaxies is neglected.

  7. Fossorial Origin of the Turtle Shell.

    PubMed

    Lyson, Tyler R; Rubidge, Bruce S; Scheyer, Torsten M; de Queiroz, Kevin; Schachner, Emma R; Smith, Roger M H; Botha-Brink, Jennifer; Bever, G S

    2016-07-25

    The turtle shell is a complex structure that currently serves a largely protective function in this iconically slow-moving group [1]. Developmental [2, 3] and fossil [4-7] data indicate that one of the first steps toward the shelled body plan was broadening of the ribs (approximately 50 my before the completed shell [5]). Broadened ribs alone provide little protection [8] and confer significant locomotory [9, 10] and respiratory [9, 11] costs. They increase thoracic rigidity [8], which decreases speed of locomotion due to shortened stride length [10], and they inhibit effective costal ventilation [9, 11]. New fossil material of the oldest hypothesized stem turtle, Eunotosaurus africanus [12] (260 mya) [13, 14] from the Karoo Basin of South Africa, indicates the initiation of rib broadening was an adaptive response to fossoriality. Similar to extant fossorial taxa [8], the broad ribs of Eunotosaurus provide an intrinsically stable base on which to operate a powerful forelimb digging mechanism. Numerous fossorial correlates [15-17] are expressed throughout Eunotosaurus' skeleton. Most of these features are widely distributed along the turtle stem and into the crown clade, indicating the common ancestor of Eunotosaurus and modern turtles possessed a body plan significantly influenced by digging. The adaptations related to fossoriality likely facilitated movement of stem turtles into aquatic environments early in the groups' evolutionary history, and this ecology may have played an important role in stem turtles surviving the Permian/Triassic extinction event. PMID:27426515

  8. Improved Shell models for screened Coulomb balls

    NASA Astrophysics Data System (ADS)

    Bonitz, M.; Kaehlert, H.; Henning, C.; Baumgartner, H.; Filinov, A.

    2006-10-01

    Spherical Coulomb crystals in dusty plasmas [1] are well described by an isotropic Yukawa-type pair interaction and an external parabolic confinement as was shown by extensive molecular dynamics simulations [2]. A much simpler description is possible with analytical shell models which have been derived for Yukawas plasmas in [3,4]. Here we analyze improved Yukawa shell models which include correlations along the lines proposed for Coulomb crystals in [5]. The shell configurations are efficiently evaluated using a Monte Carlo procedure. [1] O. Arp, A. Piel and A. Melzer, Phys. Rev. Lett. 93, 165004 (2004). [2] M. Bonitz, D. Block, O. Arp, V. Golunychiy, H. Baumgartner, P. Ludwig, A. Piel and A. Filinov, Phys. Rev. Lett. 96, 075001 (2006). [3] H. Totsuji, C. Totsuji, T. Ogawa, and K. Tsuruta, Phys. Rev. E 71, 045401 (2005). [4] C. Henning, M. Bonitz, A. Piel, P. Ludwig, H. Baumgartner, V. Golubnichiy, and D. Block, submitted to Phys. Rev. E [5] W.D. Kraeft and M. Bonitz, J. Phys. Conf. Ser. 35, 94 (2006).

  9. Buckling analysis of cylindrical shells with cracks

    SciTech Connect

    Limam, A.; Jullien, J.F.; Ouayou, B.S.

    1995-12-31

    In many areas of aeronautical nuclear and civil engineering practice, large thin-walled structural panels are increasingly becoming characteristic architectural features. Indeed, nuclear reactor vessels and cryogenic tanks of a launcher, for instance, are made up of several thin-walled panels welded together. Instability and buckling phenomenon present over-riding constraints on the design process. In addition, the presence of joints which are very often the origin of surface fissures poses increasing dangers on the overall stability of these structures. This research deals with the analysis of the effects of cracks on the behavior of cylindrical shells subject to external pressure. The study was divided into two major parts. In the first part, experiments were carried out with shells without cracks, in order to obtain reference data. A numerical study of various models explains the experimental results and shows the combined effect of the geometric imperfections and boundary conditions on the critical load. The second part focused on several experimental tests and numerical simulations on shells with in- depth fissures as a function of their population, orientation, length and position with respect to the welds or joints. The agreement between numerical and experimental results confirms the new possibility to design with the aid of the finite element program under the condition that the calculations are carried out by means of an appropriate numerical method.

  10. Hanford Site single-shell tank roadmap

    SciTech Connect

    Not Available

    1991-04-01

    The Hanford Site Single-Shell Tank Roadmap covers the near-term waste management activities to ensure safe interim storage of 140 million liters of waste. It also addresses the environmental restoration activities to close the 6 single-shell tank operable units, which include 149 single-shell tanks. These tanks were constructed starting in the 1940`s. Sixty-six tanks have leaked or are assumed to be leaking. This Roadmap has highlighted the need for integrated planning and resource allocation. The June 1990 Five-Year Plan did not address the tank safety concerns that evolved since its publication. Potential impacts to Tri-Party Agreement milestones for characterization, stabilization and isolation, technology development/demonstration, and closure will be examined in greater detail to strengthen the technical decision basis and to minimize consequences. The Roadmap indicates the advantage of accelerating characterization programs, technology evaluations, and supplemental environmental impact statement preparation. Working with regulators and expanded public outreach programs are essential to successful completion of this activity.

  11. Shell particles, trials, tribulations and triumphs

    SciTech Connect

    Guiochon, Georges A; Gritti, Fabrice

    2011-01-01

    The concept of pellicular particles was imagined by Horvath and Lipsky fifty years ago. They were initially intended for the analysis of macromolecules. Later, shell particles were prepared. The rational behind this concept was to improve column efficiency by shortening the pathways that analyte molecules must travel and, so doing, to improve their mass transfer kinetics. Several brands of superficially porous particles were developed and became popular in the 1970s. However, the major improvements in the manufacturing of high-quality, fully porous particles, that took place in the same time, particularly by making them finer and more homogeneous, hampered the success of shell particles, which eventually disappeared. Recently, the pressing needs to improve analytical throughputs forced particle manufacturers to find a better compromise between the demands for higher column efficiency that require short diffusion paths of analyte molecules in columns and the need for columns that can be operated with the conventional instruments for liquid chromatography, which operate with moderate column back-pressures. This lead to the apparition of a new generation of columns packed with shell particles, which bring chromatographic columns to a level of efficiency undreamed of a few years ago. This evolution is reviewed, the reason that motivated it, and the consequences of their success are discussed.

  12. Oxide Shell Reduction and Magnetic Property Changes in Core-Shell Fe Nanoclusters under Ion Irradiation

    SciTech Connect

    Sundararajan, Jennifer A.; Kaur, Maninder; Jiang, Weilin; McCloy, John S.; Qiang, You

    2014-02-12

    Ion irradiation effects are studied on the Fe-based core-shell nanocluster (NC) films with core as Fe and shell as Fe3O4/FeO. These NC films were were deposited on Si substrates to thickness of ~0.5 micrometers using a NC deposition system. The films were irradiated at room temperature with 5.5 MeV Si2+ ions to ion fluences of 1015 and 1016 ions/cm2. It is found that the irradiation induces grain growth, Fe valence reduction in the shell, and crystallization of Fe3N. The nature and mechanism of oxide shell reduction and composition dependence after irradiation were studied by synthesizing additional NC films of Fe3O4 and FeO+Fe3N and irradiating them under the same conditions. The presence of nanocrystalline Fe is found to be a major factor for the oxide shell reduction. The surface morphologies of these films show dramatic changes in the microstructures due to cluster growth and agglomeration as a result of ion irradiation.

  13. Shock-Sensitivity in Shell-Like Structures: With Simulations of Spherical Shell Buckling

    NASA Astrophysics Data System (ADS)

    Thompson, J. Michael T.; Sieber, Jan

    Under increasing compression, an unbuckled shell is in a metastable state which becomes increasingly precarious as the buckling load is approached. So to induce premature buckling, a lateral disturbance will have to overcome a decreasing energy barrier which reaches zero at buckling. Two archetypal problems that exhibit a severe form of this behavior are the axially-compressed cylindrical shell and the externally pressurized spherical shell. Focusing on the cylinder, a nondestructive technique was recently proposed to estimate the “shock-sensitivity” of a laboratory specimen using a lateral probe to measure the nonlinear load-deflection characteristic. If a symmetry-breaking bifurcation is encountered on the path, computer simulations showed how this can be suppressed by a controlled secondary probe. Here, we extend our understanding by assessing in general terms how a single control can capture remote saddle solutions: in particular, how a symmetric probe could locate an asymmetric solution. Then, more specifically, we analyze the spherical shell with point and ring probes, to test the procedure under challenging conditions to assess its range of applicability. Rather than a bifurcation, the spherical shell offers the challenge of a destabilizing fold (limit point) under the rigid control of the probe.

  14. Oxide shell reduction and magnetic property changes in core-shell Fe nanoclusters under ion irradiation

    SciTech Connect

    Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You; Jiang, Weilin; McCloy, John S.

    2014-05-07

    Ion irradiation effects are studied on the Fe-based core-shell nanocluster (NC) films with core as Fe and shell as Fe{sub 3}O{sub 4}/Fe{sub 3}N. These NC films were deposited on Si substrates to thickness of ∼0.5 μm using a NC deposition system. The films were irradiated at room temperature with 5.5 MeV Si{sup 2+} ions to ion fluences of 10{sup 15} and 10{sup 16} ions/cm{sup 2}. It is found that the irradiation induces grain growth, Fe valence reduction in the shell, and crystallization or growth of Fe{sub 3}N. The film retained its Fe-core and its ferromagnetic properties after irradiation. The nature and mechanism of oxide shell reduction and composition dependence after irradiation were studied by synthesizing additional NC films of Fe{sub 3}O{sub 4} and FeO + Fe{sub 3}N and irradiating them under the same conditions. The presence of nanocrystalline Fe is found to be a major factor for the oxide shell reduction. The surface morphologies of these films show dramatic changes in the microstructures due to cluster growth and agglomeration as a result of ion irradiation.

  15. Switching closed-shell to open-shell phenalenyl: toward designing electroactive materials.

    PubMed

    Pariyar, Anand; Vijaykumar, Gonela; Bhunia, Mrinal; Dey, Suman Kr; Singh, Santosh K; Kurungot, Sreekumar; Mandal, Swadhin K

    2015-05-13

    Open-shell phenalenyl chemistry started more than half a century back, and the first solid-state phenalenyl radical was realized only 15 years ago highlighting the synthetic challenges associated in stabilizing carbon-based radical chemistry, though it has great promise as building blocks for molecular electronics and multifunctional materials. Alternatively, stable closed-shell phenalenyl has tremendous potential as it can be utilized to create an in situ open-shell state by external spin injection. In the present study, we have designed a closed-shell phenalenyl-based iron(III) complex, Fe(III)(PLY)3 (PLY-H = 9-hydroxyphenalenone) displaying an excellent electrocatalytic property as cathode material for one compartment membraneless H2O2 fuel cell. The power density output of Fe(III)(PLY)3 is nearly 15-fold higher than the structurally related model compound Fe(III)(acac)3 (acac = acetylacetonate) and nearly 140-fold higher than an earlier reported mononuclear Fe(III) complex, Fe(III)(Pc)Cl (Pc = pthalocyaninate), highlighting the role of switchable closed-shell phenalenyl moiety for electron-transfer process in designing electroactive materials. PMID:25933051

  16. Nanostructued core-shell Sn nanowires @ CNTs with controllable thickness of CNT shells for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Zhong, Yu; Li, Xifei; Zhang, Yong; Li, Ruying; Cai, Mei; Sun, Xueliang

    2015-03-01

    Core-shell structure of Sn nanowires encapsulated in amorphous carbon nanotubes (Sn@CNTs) with controlled thickness of CNT shells was in situ prepared via chemical vapor deposition (CVD) method. The thickness of CNT shells was accurately controlled from 4 to 99 nm by using different growth time, flow rate of hydrocarbon gas (C2H4) and synthesis temperature. The microstructure and composition of the coaxial Sn@CNTs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM) techniques. Moreover, the Sn@CNTs were studied as anode materials for Li-ion batteries and showed excellent cycle performance. The capacity was affected by the thickness of outer CNT shells: thick CNT shells contributed to a better retention while thin CNT shells led to a higher capacity. The thin CNT shell of 6 nm presented the highest capacity around 630 mAh g-1.

  17. Comparison of the effect of two excipients (karite nut butter and vaseline) on the efficacy of Cocos nucifera, Elaeis guineensis and Carapa procera oil-based repellents formulations against mosquitoes biting in Ivory Coast.

    PubMed

    Konan, Y L; Sylla, M S; Doannio, J M; Traoré, S

    2003-06-01

    Repellents in the form of dermal pomades are recommended as a protection against awakening and bedtime mosquito bites. If synthesis repellents are available, they are nevertheless not common and the prices remain out of reach for the communities concerned. The people therefore have to resort more and more to traditional concoctions, some of which have been shown to be effective. After demonstrating that oil-based formulations (lotions, creams, pomades) of Cocos nucifera (coconut), Elaeis guineensis (oil palm) and Carapa procera (gobi) were effective against mosquitoes, it became necessary to study the impact of the two excipients used in their manufacture, on the effectiveness of the repellents. Experiments were carried with Anopheles gambiae and Aedes aegypti under lobaratory conditions and any other mosquitoes collected under field conditions in Ivory Coast. The laboratory results indicate that the average protection times obtained with formulations with karite nut butter as excipient (54.8 +/- 37.0 mn and 74.6 +/- 26.4 mn respectively on An. gambiae and Ae. aegypti) are higher than those recorded with vaseline as excipient (respectively 42.7 +/- 30.0 mn and 60.8 +/- 33.9 mn). On the other hand, under field conditions, the biting rate percentage reduction obtained with the products with karite nut butter and vaseline excipient were similar (respectively 29.8% and 35.9% for all mosquitoes collected and 45.7% and 47.4% against An. gambiae). Nevertheless, the use of karite nut butter on repellent products should be encouraged because its sale price is very lower (10 time less) than the vaseline's. PMID:12847928

  18. Silica-metal core-shell nanostructures.

    PubMed

    Jankiewicz, B J; Jamiola, D; Choma, J; Jaroniec, M

    2012-01-15

    Silica-metal nanostructures consisting of silica cores and metal nanoshells attract a lot of attention because of their unique properties and potential applications ranging from catalysis and biosensing to optical devices and medicine. The important feature of these nanostructures is the possibility of controlling their properties by the variation of their geometry, shell morphology and shell material. This review is devoted to silica-noble metal core-shell nanostructures; specifically, it outlines the main methods used for the preparation and surface modification of silica particles and presents the major strategies for the formation of metal nanoshells on the modified silica particles. A special emphasis is given to the Stöber method, which is relatively simple, effective and well verified for the synthesis of large and highly uniform silica particles (with diameters from 100 nm to a few microns). Next, the surface chemistry of these particles is discussed with a special focus on the attachment of specific organic groups such as aminopropyl or mercaptopropyl groups, which interact strongly with metal species. Finally, the synthesis, characterization and application of various silica-metal core-shell nanostructures are reviewed, especially in relation to the siliceous cores with gold or silver nanoshells. Nowadays, gold is most often used metal for the formation of nanoshells due to its beneficial properties for many applications. However, other metals such as silver, platinum, palladium, nickel and copper were also used for fabrication of core-shell nanostructures. Silica-metal nanostructures can be prepared using various methods, for instance, (i) growth of metal nanoshells on the siliceous cores with deposited metal nanoparticles, (ii) reduction of metal species accompanied by precipitation of metal nanoparticles on the modified silica cores, and (iii) formation of metal nanoshells under ultrasonic conditions. A special emphasis is given to the seed

  19. Effects of Shell-Buckling Knockdown Factors in Large Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Hrinda, Glenn A.

    2012-01-01

    Shell-buckling knockdown factors (SBKF) have been used in large cylindrical shell structures to account for uncertainty in buckling loads. As the diameter of the cylinder increases, achieving the manufacturing tolerances becomes increasingly more difficult. Knockdown factors account for manufacturing imperfections in the shell geometry by decreasing the allowable buckling load of the cylinder. In this paper, large-diameter (33 ft) cylinders are investigated by using various SBKF's. An investigation that is based on finite-element analysis (FEA) is used to develop design sensitivity relationships. Different manufacturing imperfections are modeled into a perfect cylinder to investigate the effects of these imperfections on buckling. The analysis results may be applicable to large- diameter rockets, cylindrical tower structures, bulk storage tanks, and silos.

  20. Waltzing route toward double-helix formation in cholesteric shells.

    PubMed

    Darmon, Alexandre; Benzaquen, Michael; Seč, David; Čopar, Simon; Dauchot, Olivier; Lopez-Leon, Teresa

    2016-08-23

    Liquid crystals, when confined to a spherical shell, offer fascinating possibilities for producing artificial mesoscopic atoms, which could then self-assemble into materials structured at a nanoscale, such as photonic crystals or metamaterials. The spherical curvature of the shell imposes topological constraints in the molecular ordering of the liquid crystal, resulting in the formation of defects. Controlling the number of defects, that is, the shell valency, and their positions, is a key success factor for the realization of those materials. Liquid crystals with helical cholesteric order offer a promising, yet unexplored way of controlling the shell defect configuration. In this paper, we study cholesteric shells with monovalent and bivalent defect configurations. By bringing together experiments and numerical simulations, we show that the defects appearing in these two configurations have a complex inner structure, as recently reported for simulated droplets. Bivalent shells possess two highly structured defects, which are composed of a number of smaller defect rings that pile up through the shell. Monovalent shells have a single radial defect, which is composed of two nonsingular defect lines that wind around each other in a double-helix structure. The stability of the bivalent configuration against the monovalent one is controlled by c = h/p, where h is the shell thickness and p the cholesteric helical pitch. By playing with the shell geometry, we can trigger the transition between the two configurations. This transition involves a fascinating waltz dynamics, where the two defects come closer while turning around each other. PMID:27493221

  1. Layer-by-Layer Proteomic Analysis of Mytilus galloprovincialis Shell

    PubMed Central

    Wang, Xin-xing; Bao, Lin-fei; Fan, Mei-hua; Li, Xiao-min; Wu, Chang-wen; Xia, Shu-wei

    2015-01-01

    Bivalve shell is a biomineralized tissue with various layers/microstructures and excellent mechanical properties. Shell matrix proteins (SMPs) pervade and envelop the mineral crystals and play essential roles in biomineralization. Despite that Mytilus is an economically important bivalve, only few proteomic studies have been performed for the shell, and current knowledge of the SMP set responsible for different shell layers of Mytilus remains largely patchy. In this study, we observed that Mytilus galloprovincialis shell contained three layers, including nacre, fibrous prism, and myostracum that is involved in shell-muscle attachment. A parallel proteomic analysis was performed for these three layers. By combining LC-MS/MS analysis with Mytilus EST database interrogations, a whole set of 113 proteins was identified, and the distribution of these proteins in different shell layers followed a mosaic pattern. For each layer, about a half of identified proteins are unique and the others are shared by two or all of three layers. This is the first description of the protein set exclusive to nacre, myostracum, and fibrous prism in Mytilus shell. Moreover, most of identified proteins in the present study are novel SMPs, which greatly extended biomineralization-related protein data of Mytilus. These results are useful, on one hand, for understanding the roles of SMPs in the deposition of different shell layers. On the other hand, the identified protein set of myostracum provides candidates for further exploring the mechanism of adductor muscle-shell attachment. PMID:26218932

  2. Testing MOND gravity in the shell galaxy NGC 3923

    NASA Astrophysics Data System (ADS)

    Bílek, M.; Jungwiert, B.; Jílková, L.; Ebrová, I.; Bartošková, K.; Křížek, M.

    2013-11-01

    Context. The elliptical galaxy NGC 3923 is surrounded by numerous stellar shells that are concentric arcs centered on the Galactic core. They are very likely a result of a minor merger and they consist of stars in nearly radial orbits. For a given potential, the shell radii at a given time after the merger can be calculated and compared to observations. The MOdified Newtonian Dynamics (MOND) is a theory that aims to solve the missing mass problem by modifying the laws of classical dynamics in the limit of small accelerations. Hernquist & Quinn (1987, ApJ, 312, 1) claimed that the shell distribution of NGC 3923 contradicted MOND, but Milgrom (1988, ApJ, 332, 86) found several substantial insufficiencies in their work. Aims: We test whether the observed shell distribution in NGC 3923 is consistent with MOND using the current observational knowledge of the shell number and positions and of the host galaxy surface brightness profile, which supersede the data available in the 1980s when the last (and negative) tests of MOND viability were performed on NGC 3923. Methods: Using the 3.6 μm bandpass image of NGC 3923 from the Spitzer space telescope we construct the mass profile of the galaxy. The evolution of shell radii in MOND is then computed using analytical formulae. We use 27 currently observed shells and allow for their multi-generation formation, unlike the Hernquist & Quinn one-generation model that used the 18 shells known at the time. Results: Our model reproduces the observed shell radii with a maximum deviation of ~5% for 25 out of 27 known shells while keeping a reasonable formation scenario. A multi-generation nature of the shell system, resulting from successive passages of the surviving core of the tidally disrupted dwarf galaxy, is one of key ingredients of our scenario supported by the extreme shell radial range. The 25 reproduced shells are interpreted as belonging to three generations.

  3. The shell organic matrix of the crossed lamellar queen conch shell (Strombus gigas).

    PubMed

    Osuna-Mascaró, Antonio; Cruz-Bustos, Teresa; Benhamada, Sana; Guichard, Nathalie; Marie, Benjamin; Plasseraud, Laurent; Corneillat, Marion; Alcaraz, Gérard; Checa, Antonio; Marin, Frédéric

    2014-02-01

    In molluscs, the shell organic matrix comprises a large set of biomineral-occluded proteins, glycoproteins and polysaccharides that are secreted by the calcifying mantle epithelium, and are supposed to display several functions related to the synthesis of the shell. In the present paper, we have characterized biochemically the shell matrix associated to the crossed-lamellar structure of the giant queen conch Strombus gigas. The acid-soluble (ASM) and acid-insoluble (AIM) matrices represent an extremely minor fraction of the shell. Both are constituted of polydisperse and of few discrete proteins among which three fractions, obtained by preparative SDS-PAGE and named 1P3, 2P3 and 3P3, are dominant and were further characterized. Compared to other matrices, the acid-soluble matrix is weakly glycosylated (3%) and among the discrete components, only 3P3 seems noticeably glycosylated. The monosaccharide composition of the ASM shows that mannose represents the main monosaccharide. To our knowledge, this is the first report of a high ratio of this sugar in a skeletal matrix. Furthermore, the ASM interacts with the in vitro crystallization of calcium carbonate, but this interaction is moderate. It differs from that of the isolated 1P3 fraction but is similar to that of the 2P3 and 3P3 fractions. At last, antibodies developed from the 3P3 fraction were used to localize this fraction within the shell by immunogold. This study is the first one aiming at characterizing the organic matrix associated to the crossed-lamellar structure of the queen conch shell. PMID:24291423

  4. An investigation of ab initio shell-model interactions derived by no-core shell model

    NASA Astrophysics Data System (ADS)

    Wang, XiaoBao; Dong, GuoXiang; Li, QingFeng; Shen, CaiWan; Yu, ShaoYing

    2016-09-01

    The microscopic shell-model effective interactions are mainly based on the many-body perturbation theory (MBPT), the first work of which can be traced to Brown and Kuo's first attempt in 1966, derived from the Hamada-Johnston nucleon-nucleon potential. However, the convergence of the MBPT is still unclear. On the other hand, ab initio theories, such as Green's function Monte Carlo (GFMC), no-core shell model (NCSM), and coupled-cluster theory with single and double excitations (CCSD), have made many progress in recent years. However, due to the increasing demanding of computing resources, these ab initio applications are usually limited to nuclei with mass up to A = 16. Recently, people have realized the ab initio construction of valence-space effective interactions, which is obtained through a second-time renormalization, or to be more exactly, projecting the full-manybody Hamiltonian into core, one-body, and two-body cluster parts. In this paper, we present the investigation of such ab initio shell-model interactions, by the recent derived sd-shell effective interactions based on effective J-matrix Inverse Scattering Potential (JISP) and chiral effective-field theory (EFT) through NCSM. In this work, we have seen the similarity between the ab initio shellmodel interactions and the interactions obtained by MBPT or by empirical fitting. Without the inclusion of three-body (3-bd) force, the ab initio shell-model interactions still share similar defects with the microscopic interactions by MBPT, i.e., T = 1 channel is more attractive while T = 0 channel is more repulsive than empirical interactions. The progress to include more many-body correlations and 3-bd force is still badly needed, to see whether such efforts of ab initio shell-model interactions can reach similar precision as the interactions fitted to experimental data.

  5. Effects on Salmonella shell contamination and trans-shell penetration of coating hens' eggs with chitosan.

    PubMed

    Leleu, S; Herman, L; Heyndrickx, M; De Reu, K; Michiels, C W; De Baerdemaeker, J; Messens, W

    2011-01-31

    Chitosan is a biopolymer with antimicrobial activity and film-forming properties. In this study, the effects on Salmonella shell contamination and trans-shell penetration of coating hens' eggs with chitosan was evaluated. A chitosan was selected from eight types (four non-commercial and four commercial) based on its antimicrobial activity against Salmonella enterica serovar Enteritidis (S. Enteritidis). For this purpose, a contact plate method was developed and chitosans were applied at a concentration of 0.25% (w/v). A commercial type with a molecular weight of 310-375 kDa and a deacetylation degree of 75% that reduced S. Enteritidis by 0.71 log(10) colony forming units compared to the control (without chitosan) was selected for further studies. The chitosan was shown to have antimicrobial activity against other egg borne bacteria, i.e., Acinetobacter baumannii, Alcaligenes sp., Carnobacterium sp., Pseudomonas sp., Serratia marcescens and Staphylococcus warneri, and against S. enterica serovar Typhimurium, Escherichia coli and Listeria monocytogenes. The effects of various concentrations of the selected chitosan (0.25%, 1% and 2%) on Salmonella shell contamination and trans-shell penetration were assessed using the agar molding technique. Effective reduction of eggshell contamination could not be demonstrated, but trans-shell penetration was significantly reduced in the presence of a 2% chitosan eggshell coating, with only 6.1% of the eggs being penetrated compared to 24.5% of the uncoated eggs. It was concluded that the 2% chitosan coating has the potential to reduce contamination of egg contents resulting from trans-shell penetration by S. Enteritidis. PMID:21146239

  6. Jacobi no-core shell model for p-shell nuclei

    NASA Astrophysics Data System (ADS)

    Liebig, S.; Meißner, U.-G.; Nogga, A.

    2016-04-01

    We introduce an algorithm to obtain coefficients of fractional parentage for light p-shell nuclei. The coefficients enable one to use Jacobi coordinates in no-core shell model calculations separating off the center-of-mass motion. Fully antisymmetrized basis states are given together with recoupling coefficients that allow one to apply two- and three-nucleon operators. As an example, we study the dependence on the harmonic oscillator frequency of 3H, 4He, 6He, 6Li and 7Li and extract their binding and excitation energies. The coefficients will be made openly accessible as HDF5 data files.

  7. Synthesis and Characterization of Monodisperse Metallodielectric SiO2@Pt@SiO2 Core-Shell-Shell Particles.

    PubMed

    Petrov, Alexey; Lehmann, Hauke; Finsel, Maik; Klinke, Christian; Weller, Horst; Vossmeyer, Tobias

    2016-01-26

    Metallodielectric nanostructured core-shell-shell particles are particularly desirable for enabling novel types of optical components, including narrow-band absorbers, narrow-band photodetectors, and thermal emitters, as well as new types of sensors and catalysts. Here, we present a facile approach for the preparation of submicron SiO2@Pt@SiO2 core-shell-shell particles. As shown by transmission and scanning electron microscopy, the first steps of this approach allow for the deposition of closed and almost perfectly smooth platinum shells onto silica cores via a seeded growth mechanism. By choosing appropriate conditions, the shell thickness could be adjusted precisely, ranging from ∼3 to ∼32 nm. As determined by X-ray diffraction, the crystalline domain sizes of the polycrystalline metal shells were ∼4 nm, regardless of the shell thickness. The platinum content of the particles was determined by atomic absorption spectroscopy and for thin shells consistent with a dense metal layer of the TEM-measured thickness. In addition, we show that the roughness of the platinum shell strongly depends on the storage time of the gold seeds used to initiate reductive platinum deposition. Further, using polyvinylpyrrolidone as adhesion layer, it was possible to coat the metallic shells with very homogeneous and smooth insulating silica shells of well-controlled thicknesses between ∼2 and ∼43 nm. After depositing the particles onto silicon substrates equipped with interdigitated electrode structures, the metallic character of the SiO2@Pt particles and the insulating character of the SiO2 shells of the SiO2@Pt@SiO2 particles were successfully demonstrated by charge transport measurements at variable temperatures. PMID:26731341

  8. Gravitationally collapsing shells in (2+1) dimensions

    SciTech Connect

    Mann, Robert B.; Oh, John J.

    2006-12-15

    We study gravitationally collapsing models of pressureless dust, fluids with pressure, and the generalized Chaplygin gas (GCG) shell in (2+1)-dimensional spacetimes. Various collapse scenarios are investigated under a variety of the background configurations such as anti-de Sitter (AdS) black hole, de Sitter (dS) space, flat and AdS space with a conical deficit. As with the case of a disk of dust, we find that the collapse of a dust shell coincides with the Oppenheimer-Snyder type collapse to a black hole provided the initial density is sufficiently large. We also find - for all types of shell - that collapse to a naked singularity is possible under a broad variety of initial conditions. For shells with pressure this singularity can occur for a finite radius of the shell. We also find that GCG shells exhibit diverse collapse scenarios, which can be easily demonstrated by an effective potential analysis.

  9. Small bending and stretching of sandwich-type shells

    NASA Technical Reports Server (NTRS)

    Reissner, Eric

    1950-01-01

    A theory has been developed for small bending and stretching of sandwich-type shells. This theory is an extension of the known theory of homogeneous thin elastic shells. It was found that two effects are important in the present problem, which are not normally of importance in the theory of curved shells: (1) the effect of transverse shear deformation and (2) the effect of transverse normal stress deformation. The first of these two effects has been known to be of importance in the theory of plates and beams. The second effect was found to occur in a manner which is typical for shells and has no counterpart in flat-plate theory. The general results of this report have been applied to the solution of problems concerning flat plates, circular rings, circular cylindrical shells, and spherical shells. In each case numerical examples have been given, illustrating the magnitude of the effects of transverse shear and normal stress deformation.

  10. Shell Buckling Design Criteria Based on Manufacturing Imperfection Signatures

    NASA Technical Reports Server (NTRS)

    Hilburger, Mark W.; Nemeth, Michael P.; Starnes, James H., Jr.

    2004-01-01

    An analysis-based approach .for developing shell-buckling design criteria for laminated-composite cylindrical shells that accurately accounts for the effects of initial geometric imperfections is presented. With this approach, measured initial geometric imperfection data from six graphite-epoxy shells are used to determine a manufacturing-process-specific imperfection signature for these shells. This imperfection signature is then used as input into nonlinear finite-element analyses. The imperfection signature represents a "first-approximation" mean imperfection shape that is suitable for developing preliminary-design data. Comparisons of test data and analytical results obtained by using several different imperfection shapes are presented for selected shells. Overall, the results indicate that the analysis-based approach presented for developing reliable preliminary-design criteria has the potential to provide improved, less conservative buckling-load estimates, and to reduce the weight and cost of developing buckling-resistant shell structures.

  11. Cracked shells under skew-symmetric loading. [Reissner theory

    NASA Technical Reports Server (NTRS)

    Delale, F.

    1981-01-01

    The general problem of a shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and anti-plane elasticity solutions. Results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform in-plane shearing, out of plane shearing, and torsion. The problem is formulated for specially orthostropic materials, therefore, the effect of orthotropy on the results is also studied.

  12. Air Blast-Induced Vibration of a Laminated Spherical Shell

    NASA Astrophysics Data System (ADS)

    Yzgüksel, Hzgüseyin Murat; Türkmen, Halit S.

    The scope of this study is to investigate the dynamic behavior of a laminated spherical shell subjected to air blast load. The shell structure considered here is a hemisphere in shape and made of a glass/epoxy laminated composite material. The blast experiments are performed on the spherical shell. The strain-time history of the center of the spherical shell panel is obtained experimentally. The blast loaded spherical shell is also modeled and analyzed using ANSYS finite element software. The static analysis is performed to characterize the material. The dynamic response of the spherical shell panel obtained numerically is compared to the experimental results. It is observed that the response frequency corresponds to the higher vibration modes of the panel. The qualitative agreement is found between the numerical and experimental results.

  13. Fossil shell emission in dying radio loud AGNs

    NASA Astrophysics Data System (ADS)

    Kino, M.; Ito, H.; Kawakatu, N.; Orienti, M.; Nagai, H.; Wajima, K.; Itoh, R.

    2016-02-01

    We investigate shell emission associated with dying radio loud AGNs. First, based on our recent work by Ito et al. (2015), we describe the dynamical and spectral evolution of shells after stopping the jet energy injection. We find that the shell emission overwhelms that of the radio lobes soon after stopping the jet energy injection because fresh electrons are continuously supplied into the shell via the forward shock, while the radio lobes rapidly fade out without jet energy injection. We find that such fossil shells can be a new class of target sources for SKA telescope. Next, we apply the model to the nearby radio source 3C84. Then, we find that the fossil shell emission in 3C84 is less luminous in the radio band while it is bright in the TeV γ-ray band and can be detectable by CTA. Data from STELLA

  14. Tunable Diacetylene Polymerized Shell Microbubbles as Ultrasound Contrast Agents

    PubMed Central

    Park, Yoonjee; Luce, Adam C.; Whitaker, Ragnhild D.; Amin, Bhumica; Cabodi, Mario; Nap, Rikkert J.; Szleifer, Igal; Cleveland, Robin O.; Nagy, Jon O.; Wong, Joyce Y.

    2012-01-01

    Monodisperse gas microbubbles, encapsulated with a shell of photopolymerizable diacetylene lipids and phospholipids, were produced by microfluidic flow focusing, for use as ultrasound contrast agents. The stability of the polymerized shell microbubbles against both aggregation and gas dissolution under physiological conditions was studied. Polyethylene glycol (PEG) 5000, which was attached to the diacetylene lipids, was predicted by molecular theory to provide more steric hindrance against aggregation than PEG 2000 and this was confirmed experimentally. The polymerized shell microbubbles were found to have higher shell-resistance than nonpolymerizable shell microbubbles and commercially available microbubbles (Vevo MicroMarker). The acoustic stability under 7.5 MHz ultrasound insonation was significantly greater than for the two comparison microbubbles. The acoustic stability was tunable by varying the amount of diacetylene lipid. Thus, our polymerized shell microbubbles are a promising platform for ultrasound contrast agents. PMID:22260537

  15. Modelling apical constriction in epithelia using elastic shell theory.

    PubMed

    Jones, Gareth Wyn; Chapman, S Jonathan

    2010-06-01

    Apical constriction is one of the fundamental mechanisms by which embryonic tissue is deformed, giving rise to the shape and form of the fully-developed organism. The mechanism involves a contraction of fibres embedded in the apical side of epithelial tissues, leading to an invagination or folding of the cell sheet. In this article the phenomenon is modelled mechanically by describing the epithelial sheet as an elastic shell, which contains a surface representing the continuous mesh formed from the embedded fibres. Allowing this mesh to contract, an enhanced shell theory is developed in which the stiffness and bending tensors of the shell are modified to include the fibres' stiffness, and in which the active effects of the contraction appear as body forces in the shell equilibrium equations. Numerical examples are presented at the end, including the bending of a plate and a cylindrical shell (modelling neurulation) and the invagination of a spherical shell (modelling simple gastrulation). PMID:19859751

  16. Sound Transmission through a Cylindrical Sandwich Shell with Honeycomb Core

    NASA Technical Reports Server (NTRS)

    Tang, Yvette Y.; Robinson, Jay H.; Silcox, Richard J.

    1996-01-01

    Sound transmission through an infinite cylindrical sandwich shell is studied in the context of the transmission of airborne sound into aircraft interiors. The cylindrical shell is immersed in fluid media and excited by an oblique incident plane sound wave. The internal and external fluids are different and there is uniform airflow in the external fluid medium. An explicit expression of transmission loss is derived in terms of modal impedance of the fluids and the shell. The results show the effects of (a) the incident angles of the plane wave; (b) the flight conditions of Mach number and altitude of the aircraft; (c) the ratios between the core thickness and the total thickness of the shell; and (d) the structural loss factors on the transmission loss. Comparisons of the transmission loss are made among different shell constructions and different shell theories.

  17. Effects of Internal Configuration on Afterburner Shell Temperatures

    NASA Technical Reports Server (NTRS)

    Conrad, E William; Jansen, Emmert T

    1952-01-01

    A brief investigation was conducted in the altitude wind tunnel to determine the extent to which the afterburner shell cooling problem could be alleviated by internal configuration changes. Data were obtained with and without a cooling liner installed and for variations in the radial fuel distribution and in the radial distribution in flame-seat area. Consideration is given to the effects on both shell temperature and afterburner performance. In the range of fuel-air ratio investigated, the use of a cooling liner resulted in substantial reductions in shell temperature with no penalty in performance. Appreciable reductions in afterburner shell temperature were made possible by control of the radial fuel distribution; however, the effects on performance are uncertain and may depend on other variables not investigated. No direct relation was found between shell temperature and the clearance between the flame holder and the shell; however, some cooling effect may possibly be achieved by varying the clearance.

  18. The structure of the dust shells around IRC +10216

    NASA Astrophysics Data System (ADS)

    Sloan, G. C.; Egan, M. P.

    1995-05-01

    We have investigated IRC +10216 using a long-slit mid-infrared spectrometer and modeling the circumstellar dust with a radiative transfer algorithm. Maximum entropy reconstructions of the spectral images made with the slit oriented north/south and east/west reveal three components. Two shells of cool carbon-rich dust are seen, as well as a region of blue emission between the shells, approximately 1 sec north of the central source. The dust shell structure agrees well with previous interferometric observations: a circularly symmetric inner shell enclosed within an outer shell elongated roughly north/south. The blue emission appears to arise from a region of small grains of radiatively heated amorphous carbon and implies that the polar regions of the inner shell are optically thinner that the equatorial regions.

  19. Modelling of the collision of two viscoelastic spherical shells

    NASA Astrophysics Data System (ADS)

    Rossikhin, Yury A.; Shitikova, Marina V.; Manh, Duong Tuan

    2016-03-01

    In the present paper, the collision of two viscoelastic spherical shells is investigated using the wave theory of impact. The model developed here suggests that after the moment of impact quasi-longitudinal and quasi-transverse shock waves are generated, which then propagate along the spherical shells. The solution behind the wave fronts is constructed with the help of the theory of discontinuities. Since the local bearing of the materials of the colliding viscoelastic shells is taken into account, the solution in the contact domain is found via the modified Hertz contact theory involving the operator representation of viscoelastic analogs of Young's modulus and Poisson's ratio. The collision of two elastic spherical shells is considered first, and then using Volterra correspondence principle, according to which the elastic constants in the governing equations should be replaced by the corresponding viscoelastic operators, the solution obtained for elastic shells is extended over the case of viscoelastic shells.

  20. Distribution and shell selection by two hermit crabs in different habitats on Egyptian Red Sea Coast

    NASA Astrophysics Data System (ADS)

    El-Kareem Ismail, Tarek Gad

    2010-05-01

    The present work aims to assess the spatial distribution, analyze shell utilization, shell fitness and determine the effect of coexistence of two hermit crabs Calcinus latens and Clibanarius signatus on used shell resources in various habitats on the Red Sea Coast. Also, to determine the choice of shells and investigate the shell species preference of C. latens and C. signatus in the laboratory. The hermit crabs C. latens and C. signatus were found to occupy shells of 39 gastropod species. The most commonly occupied gastropod shells are those belonging to genera Strombus, Nerita, Cerithium and Planaxis. The results showed that crab individuals utilized mainly the shell with elongate aperture. Laboratory experiments showed that two crab species preferred shells of Strombus followed by Cerithium and Nerita when offered shells of nearly similar size (optimal). Crab individuals showed a significant preference for optimal sized shells when given suboptimal shells as an alternative choice. Also, the hermit crabs avoid damaged shells when given a choice of optimal sized damaged shell and optimal sized intact one. In addition, two hermit crab species chose shells of smaller than optimal size when given a choice of damaged optimal sized shells and smaller intact ones. On the other hand, field observations showed that most crab individuals lived in adequate sized shells. The present data conclude that shell selection by hermit crabs C. latens and C. signatus depends mostly on shell internal volume, shell quality and shell aperture size than other factors, because they provide a maximum protection for hermit crabs.