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Sample records for fissured formations

  1. Effect of Local Crystallographic Texture on the Fissure Formation During Charpy Impact Testing of Low-Carbon Steel

    NASA Astrophysics Data System (ADS)

    Ghosh, Abhijit; Patra, Sudipta; Chatterjee, Arya; Chakrabarti, Debalay

    2016-06-01

    The severity of the formation of fissures (also known as splitting or delamination) on the fracture surface of Charpy impact-tested samples of a low-carbon steel has been found to increase with the decrease in finish rolling temperature [1093 K to 923 K (820 °C to 650 °C)]. Combined scanning electron microscopy and electron back-scattered diffraction study revealed that crystallographic texture was the prime factor responsible for the fissure formation. Through-thickness texture band composed of cube [Normal Direction (ND)║<001>] and gamma [ND║<111>] orientations developed during the inter-critical rolling treatment. Strain incompatibility between these two texture bands causes fissure cracking on the main fracture plane. A new approach based on the angle between {001} planes of neighboring crystals has been employed in order to estimate the `effective grain size,' which is used to determine the cleavage fracture stress on different planes of a sample. The severity of fissure formation was found to be directly related to the difference in cleavage fracture stress between the `main fracture plane' and `fissure plane.' Clustering of ferrite grains having cube texture promoted the fissure crack propagation along the transverse `fissure plane,' by increasing the `effective grain size' and decreasing the cleavage fracture stress on that plane.

  2. Coseismic Pit Crater, Normal Fault, and Extensional Fissure Formation in Unconsolidated Sediment and Basalt in Northern Iceland

    NASA Astrophysics Data System (ADS)

    Ferrill, D. A.; Wyrick, D. Y.; Smart, K. J.

    2008-12-01

    Two rifting-related seismic events in 1975 and 1978 along the Mid-Atlantic Ridge near the northern coast of Iceland produced an array of surface deformation features in Holocene basalt flows and overlying unconsolidated sediments. New field mapping and aerial photograph interpretation is coupled with analysis of maps of seismic activity and level-line survey results to constrain the timing, style, and magnitude of this deformation. Fault scarps and fissures in basalts can be traced laterally down a gentle northward dip projecting into unconsolidated braided stream deposits, providing an impressive view of the deformation style in the two contrasting mechanical layers. We report on detailed field mapping of two of these laterally traceable structures conducted in the summer of 2008 and analysis of a suite of aerial photographs from 1958 to 1998. Map-scale structures in the basalts with little or no sedimentary cover include (i) fault scarps, (ii) fissures, and (iii) locally-developed gentle dip away from the related normal fault. Dilation of faults and extension fractures in the basalt has led to rock toppling and rock fall causing widening of fissures. Wedging of toppled rock blocks at the tops of fissures has locally produced keystone arches and bridges across the tops of open fissures. Different stages in the progression of fissure formation and collapse, including (i) fissure, (ii) widened fissure with cavern, (iii) localized collapse pit, and (iv) elongate collapsed fissure, can be observed over along-strike distances of 10's of meters. Where unconsolidated sand and gravel deposits >3 m thick cover the basalts (200 m to the north along strike) structural geomorphologic features are dominated by (i) grabens, (ii) pit craters, and (iii) elongate troughs. Graben-bounding normal faults cutting the sedimentary cover in many cases have displacements >1 m. Pit craters have cone to bowl shapes, commonly occur within grabens, and have depths up to 2.8 m. The mapped

  3. Anal Fissure

    PubMed Central

    Beaty, Jennifer Sam; Shashidharan, M.

    2016-01-01

    Anal fissure (fissure-in-ano) is a very common anorectal condition. The exact etiology of this condition is debated; however, there is a clear association with elevated internal anal sphincter pressures. Though hard bowel movements are implicated in fissure etiology, they are not universally present in patients with anal fissures. Half of all patients with fissures heal with nonoperative management such as high fiber diet, sitz baths, and pharmacological agents. When nonoperative management fails, surgical treatment with lateral internal sphincterotomy has a high success rate. In this chapter, we will review the symptoms, pathophysiology, and management of anal fissures. PMID:26929749

  4. Anal fissure

    MedlinePlus

    ... bath 2 to 3 times a day. The water should cover only the hips and buttocks. If the anal fissures do not go away with home care methods, treatment may involve: Botox injections into the muscle in the anus (anal sphincter) ...

  5. [Perianal fistula and anal fissure].

    PubMed

    Heitland, W

    2012-12-01

    CRYPTOGLANDULAR ANAL FISTULA: Perianal abscesses are caused by cryptoglandular infections. Not every abscess will end in a fistula. The formation of a fistula is determined by the anatomy of the anal sphincter and perianal fistulas will not heal on their own. The therapy of a fistula is oriented between a more aggressive approach (operation) and a conservative treatment with fibrin glue or a plug. Definitive healing and the development of incontinence are the most important key points. ANAL FISSURES: Acute anal fissures should be treated conservatively by topical ointments, consisting of nitrates, calcium channel blockers and if all else fails by botulinum toxin. Treatment of chronic fissures will start conservatively but operative options are necessary in many cases. Operation of first choice is fissurectomy, including excision of fibrotic margins, curettage of the base and excision of the sentinel pile and anal polyps. Lateral internal sphincterotomy is associated with a certain degree of incontinence and needs critical long-term observation.

  6. Anal fissure - slideshow

    MedlinePlus

    ... anatomy URL of this page: //medlineplus.gov/ency/presentations/100154.htm Anal fissure - series—Normal anatomy To use the sharing features on this page, please enable JavaScript. Go to slide 1 out of 4 Go to slide 2 ...

  7. Growing Hemorrhagic Choroidal Fissure Cyst

    PubMed Central

    Gelal, Fazıl; Gurkan, Gokhan; Feran, Hamit

    2016-01-01

    Choroidal fissure cysts are often incidentally discovered. They are usually asymptomatic. The authors report a case of growing and hemorrhagic choroidal fissure cyst which was treated surgically. A 22-year-old female presented with headache. Cranial MRI showed a left-sided choroidal fissure cyst. Follow-up MRI showed that the size of the cyst had increased gradually. Twenty months later, the patient was admitted to our emergency department with severe headache. MRI and CT showed an intracystic hematoma. Although such cysts usually have a benign course without symptoms and progression, they may rarely present with intracystic hemorrhage, enlargement of the cyst and increasing symptomatology. PMID:26962426

  8. Hyrtl fissure: a historical thriller.

    PubMed

    Mudry, Albert

    2009-06-01

    Hyrtl fissure is an anatomic landmark allowing a transient embryonic communication between the subarachnoid space and the middle ear. It is an eponym characterized by the absence of a known original description. The aim of this study was to try to find and explain the origin of the use of this eponym. Numerous references and original publications were studied to finally demonstrate that Joseph Hyrtl was not able to describe this fissure in the mid-19th century.

  9. Abnormal vasculature interferes with optic fissure closure in lmo2 mutant zebrafish embryos.

    PubMed

    Weiss, Omri; Kaufman, Rivka; Michaeli, Natali; Inbal, Adi

    2012-09-15

    Ocular coloboma is a potentially blinding congenital eye malformation caused by failure of optic fissure closure during early embryogenesis. The optic fissure is a ventral groove that forms during optic cup morphogenesis, and through which hyaloid artery and vein enter and leave the developing eye, respectively. After hyaloid artery and vein formation, the optic fissure closes around them. The mechanisms underlying optic fissure closure are poorly understood, and whether and how this process is influenced by hyaloid vessel development is unknown. Here we show that a loss-of-function mutation in lmo2, a gene specifically required for hematopoiesis and vascular development, results in failure of optic fissure closure in zebrafish. Analysis of ocular blood vessels in lmo2 mutants reveals that some vessels are severely dilated, including the hyaloid vein. Remarkably, reducing vessel size leads to rescue of optic fissure phenotype. Our results reveal a new mechanism leading to coloboma, whereby malformed blood vessels interfere with eye morphogenesis.

  10. Shallow Subsurface Structures of Volcanic Fissures

    NASA Astrophysics Data System (ADS)

    Parcheta, C. E.; Nash, J.; Mitchell, K. L.; Parness, A.

    2015-12-01

    Volcanic fissure vents are a difficult geologic feature to quantify. They are often too thin to document in detail with seismology or remote geophysical methods. Additionally, lava flows, lava drain back, or collapsed rampart blocks typically conceal a fissure's surface expression. For exposed fissures, quantifying the surface (let along sub0surface) geometric expression can become an overwhelming and time-consuming task given the non-uniform distribution of wall irregularities, drain back textures, and the larger scale sinuosity of the whole fissure system. We developed (and previously presented) VolcanoBot to acquire robust characteristic data of fissure geometries by going inside accessible fissures after an eruption ends and the fissure cools off to <50 C. Data from VolcanoBot documents the fissure conduit geometry with a near-IR structured light sensor, and reproduces the 3d structures to cm-scale accuracy. Here we present a comparison of shallow subsurface structures (<30 m depth) within the Mauna Ulu fissure system and their counterpart features at the vent-to-ground-surface interface. While we have not mapped enough length of the fissure to document sinuosity at depth, we see a self-similar pattern of irregularities on the fissure walls throughout the entire shallow subsurface, implying a fracture mechanical origin similar to faults. These irregularities are, on average, 1 m across and protrude 30 cm into the drained fissure. This is significantly larger than the 10% wall roughness addressed in the engineering literature on fluid dynamics, and implies that magma fluid dynamics during fissure eruptions are probably not as passive nor as simple as previously thought. In some locations, it is possible to match piercing points across the fissure walls, where the dike broke the wall rock in order to propagate upwards, yet in other locations there are erosional cavities, again, implying complex fluid dynamics in the shallow sub-surface during fissure eruptions.

  11. Flow characteristics and sealing ability of fissure sealants.

    PubMed

    Barnes, D M; Kihn, P; von Fraunhofer, J A; Elsabach, A

    2000-01-01

    This study evaluated the relationship between fissure sealant viscosity, leakage prevention and the incidence of void formation of five commercially available pit-and-fissure sealants. Seventy-two intact, caries free human pre-molars and molars were divided into six test groups of 12 teeth each. All teeth were cleaned with a flour of pumice prophylaxis followed by etching for 60 seconds with 37% H3PO4, rinsing for 30 seconds and drying with oil-free air. Five commercial, light-cured fissure sealants and an unfilled version of one sealant were applied following manufacturers' instructions. Teeth were thermal cycled for 5000 cycles from 5-50 degrees C with a one-minute dwell time at each temperature. Silver nitrate staining followed by mesiodistal sectioning was performed. Leakage and void formation were evaluated at X50 optical magnification. Viscosity was assessed by syringing the fissure sealants into short pipettes, allowing free flow for 30 seconds and then light curing for one minute. The length of unfilled capillary was measured with a Vernier gauge. All experimental data was subjected to a one-way ANOVA, and where differences were detected, they were identified by a post hoc Tukey hsd test at a priori alpha = 0.05. Based on the conditions of the study, viscosity and flow characteristics had no effect on sealing ability or void formation.

  12. Fissure seal or fluoride varnish?

    PubMed

    Deery, Christopher

    2016-09-01

    Data sourcesCochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, the US National Institutes of Health Trials Register and the World Health Organization (WHO) Clinical Trials Registry PlatformStudy selectionRandomised controlled trials (RCTs) with at least 12 months follow-up, in which fissure sealants, or fissure sealants together with fluoride varnishes, were compared with fluoride varnishes alone for preventing caries in occlusal surfaces of permanent teeth of children and adolescents.Data extraction and synthesisTwo reviewers independently screened search results, extracted data and assessed risk of bias of included studies. Studies were grouped and analysed on the basis of sealant material type (resin-based sealant and glass ionomer-based sealant, glass ionomer and resin-modified glass ionomer) and different follow-up periods. Odds ratio were calculated for caries or no caries on occlusal surfaces of permanent molar teeth. Mean differences were calculated for continuous outcomes and data. Evidence quality was assessed using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) methods.ResultsEight RCTs involving a total of 1747 children aged five to ten years of age were included. Three trials compared resin-based fissure sealant versus fluoride varnish. Results from two studies (358 children) after two years were combined. Sealants prevented more caries, pooled odds ratio (OR) = 0.69 (95%CI; 0.50 to 0.94). One trial with follow-up at four and nine years found that the caries-preventive benefit for sealants was maintained, with 26% of sealed teeth and 55.8% of varnished teeth having developed caries at nine years. Evidence for glass-ionomer sealants was of low quality. One split-mouth trial analysing 92 children at two-year follow-up found a significant difference in favour of resin-based fissure sealant together with fluoride varnish compared with fluoride varnish only (OR

  13. Sylvian Fissure Dermoid Cyst - A Rare case

    PubMed Central

    Anand, Deepak; Soin, Divya; Garg, Ravinder

    2014-01-01

    Intracranial dermoid cysts are rare tumours which usually occur in the midline. Sylvian fissure is a very unusual site for this lesion. This case presents a patient with unruptured dermoid cyst in the left sylvian fissure who was operated successfully without any residual deficit. PMID:25386502

  14. Modeling of earth fissures caused by land subsidence due to groundwater withdrawal

    NASA Astrophysics Data System (ADS)

    Panda, B. B.; Rucker, M. L.; Fergason, K. C.

    2015-11-01

    Land subsidence and earth fissures are phenomena related to groundwater withdrawal in a sedimentary basin. If the rock basement or basin lithology is irregular, both vertical and horizontal displacements can be induced due to differential settlement and tensile stresses appearing in the soil mass. If the differential settlement is of sufficient magnitude, earth fissuring can occur within tensile zones. The magnitudes of compaction and fissure geometry are closely related to the thickness and skeletal compressibility of fine-grained sediments within the aquifer system. Land subsidence and earth fissuring were modeled by employing a two-dimensional (2-D) coupled seepage and stress-strain finite element analysis. The basin bedrock geometry, lithological variation, measurements of surface displacements, and changes in hydraulic head were the critical input parameter for the subsidence modeling. Simulation results indicate that strain had exceeded the approximate threshold for fissure formation of 0.02 to 0.06 % in the area of the identified fissures. The numerical model was used to predict future subsidence and potential earth fissures for flood control structures within the metro Phoenix area.

  15. Cadherin-mediated cell adhesion is critical for the closing of the mouse optic fissure.

    PubMed

    Chen, Shuyi; Lewis, Brandy; Moran, Andrea; Xie, Ting

    2012-01-01

    Coloboma is a congenital disease that contributes significantly to childhood blindness. It results from the failure in closing the optic fissure, a transient opening on the ventral side of the developing eye. Although human and mouse genetic studies have identified a number of genes associated with coloboma, the detailed cellular mechanisms underlying the optic fissure closure and coloboma formation remain largely undefined. N-cadherin-mediated cell adhesion has been shown to be important for the optic fissure closure in zebrafish, but it remains to be determined experimentally how cell-cell adhesions are involved in the mammalian optic fissure closing process. α-Catenin is required for cell adhesion mediated by all of the classic cadherin molecules, including N-cadherin. In this study, we used the Cre-mediated conditional knockout technique to specifically delete α-catenin from the developing mouse eye to show that it is required for the successful closing of the optic fissure. In α-catenin conditional mutant optic cups, the major cell fates, including the optic fissure margin, neural retina and retinal pigmented epithelium, are specified normally, and the retinal progenitor cells proliferate normally. However, adherens junctions components, including N-cadherin, β-catenin and filamentous actin, fail to accumulate on the apical side of α-catenin mutant retinal progenitor cells, where adherens junctions are normally abundant, and the organization of the neural retina and the optic fissure margin is disrupted. Finally, the α-catenin mutant retina gradually degenerates in the adult mouse eye. Therefore, our results show that α-catenin-mediated cell adhesion and cell organization are important for the fissure closure in mice, and further suggest that genes that regulate cell adhesion may underlie certain coloboma cases in humans.

  16. Thoracoscopic anterior ‘fissure first’ technique for left lung cancer with an incomplete fissure

    PubMed Central

    Samejima, Joji; Matsuura, Yosuke; Nakao, Masayuki; Uehara, Hirofumi; Nakagawa, Ken; Masuda, Munetaka; Okumura, Sakae

    2016-01-01

    Background Dealing with incomplete lung fissures during thoracoscopic surgery is difficult. Our objective was to evaluate the efficacy and safety of a thoracoscopic anterior ‘fissure first’ technique for dealing with incomplete left lung fissures. Methods One hundred and seventy patients underwent left upper lobectomy or left lower lobectomy between April 2008 and July 2014. Of these, 34 patients underwent surgery using a thoracoscopic anterior ‘fissure first’ technique for incomplete fissures (group A) and 136 underwent surgery using a conventional thoracoscopic method for unfused fissures (group B). A four-port complete thoracoscopic approach was used in all patients. After completion of the fissure, hilar lymphadenectomy was performed in the conventional manner. Results There were no significant differences between the two groups in operating time, blood loss, or duration of chest tube drainage. Patients in group A required more staple cartridges than those in group B (mean number of cartridges, 2.4 vs. 1.1; P<0.01). The two groups did not significantly differ with regard to the prevalence of air leaks (12% vs. 4%; P=0.11), either prolonged or delayed. Conclusions We found that a thoracoscopic anterior ‘fissure first’ technique for left lung cancer with an incomplete fissure enabled hilar lymphadenectomy to be performed in the conventional manner without any increase in the prevalence of air leaks, operating time, or duration of chest tube drainage. This technique should be considered for use in left upper lobectomy or left lower lobectomy in patients with an incomplete fissure. PMID:28066589

  17. Enceladus Near-Fissure Surface Temperatures

    NASA Astrophysics Data System (ADS)

    Howell, Robert R.; Goguen, J. D.; Spencer, J. R.

    2013-10-01

    Recently reported Cassini VIMS observations of thermal emission from the Enceladus south-pole fissures (Goguen et al. 2013) when combined with previous longer wavelength Cassini CIRS observations (Spencer et al. 2006) allow us to better constrain the highest temperatures present, but also require more detailed modeling of the processes which control those highest temperatures. The simplest interpretation of the VIMS observations is that the 3-5 µm thermal radiation comes from the walls within a fissure, rather than the adjacent surface. But as part of investigating that latter alternative it became clear that very high sublimation rates are implied by some predicted surface temperatures. Abramov and Spencer (2009) produced models of the expected surface temperature distribution, assuming conduction of heat through the ice, balanced by thermal radiation at the surface. However as temperature is raised, at 186K sublimation cooling equals radiation, and because it depends exponentially on temperature, it quickly dominates. We have found that including the surface sublimation cooling suppresses the higher temperatures. Regardless of the fissure temperature, surface temperatures above 200K can only be maintained by conduction within a few tens of centimeters of the assumed fissure wall. The high sublimation erosion rates (0.25 m/yr at 180K, rising to over 100 m/yr at 220K) imply that the fixed boundaries we have previously assumed are unrealistic. If these surface temperatures are maintained then either a sublimation lag of non-ice components will accumulate, inhibiting sublimation, or the geometry of the fissure vent will rapidly change. However the rate of change will be limited by the available heat provided by conduction. We are now developing numerical models with moving boundary conditions to explore the time evolution. The simplest result may be that the lip of the fissure erodes back till it no longer remains in thermal contact with the rising vapor which

  18. Robust pulmonary lobe segmentation against incomplete fissures

    NASA Astrophysics Data System (ADS)

    Gu, Suicheng; Zheng, Qingfeng; Siegfried, Jill; Pu, Jiantao

    2012-03-01

    As important anatomical landmarks of the human lung, accurate lobe segmentation may be useful for characterizing specific lung diseases (e.g., inflammatory, granulomatous, and neoplastic diseases). A number of investigations showed that pulmonary fissures were often incomplete in image depiction, thereby leading to the computerized identification of individual lobes a challenging task. Our purpose is to develop a fully automated algorithm for accurate identification of individual lobes regardless of the integrity of pulmonary fissures. The underlying idea of the developed lobe segmentation scheme is to use piecewise planes to approximate the detected fissures. After a rotation and a global smoothing, a number of small planes were fitted using local fissures points. The local surfaces are finally combined for lobe segmentation using a quadratic B-spline weighting strategy to assure that the segmentation is smooth. The performance of the developed scheme was assessed by comparing with a manually created reference standard on a dataset of 30 lung CT examinations. These examinations covered a number of lung diseases and were selected from a large chronic obstructive pulmonary disease (COPD) dataset. The results indicate that our scheme of lobe segmentation is efficient and accurate against incomplete fissures.

  19. Identification of the pleural fissures with computed tomography

    SciTech Connect

    Marks, B.W.; Kuhns, L.R.

    1982-04-01

    The pleural fissures can be identified as avascular planes within the pulmonary parenchyma on CT scans. A retrospective analysis of 23 consecutive scans was conducted to consider identification of fissures. On 21% of the axial images, a ''ground glass'' band was identified within the avascular plane, probably due to partial volume averaging of the pleural fissure with the adjacent lung. The pleural fissures could be identified in 84% of cases.

  20. Tensions and Fissures: The Politics of Standardised Testing and Accountability in Ontario, 1995-2015

    ERIC Educational Resources Information Center

    Pinto, Laura Elizabeth

    2016-01-01

    While Ontario has received international accolades for its enactment of province-wide standardised testing upon the formation of the Education Quality and Accountability Office (EQAO), a closer look at provincial assessments over a 20-year span reveals successes as well as systemic tensions and fissures. The purpose of this paper is twofold.…

  1. Influence of matrix diffusion and exchange reactions on radiocarbon ages in fissured carbonate aquifers

    SciTech Connect

    Maloszewski, P. ); Zuber, A. )

    1991-08-01

    The parallel fissure model coupled with the equation of diffusion into the matrix and with exchange reaction equations has been used to derive a simple formula for estimating the influence of matrix porosity and reaction parameters on the determination of radiocarbon ages in fissured carbonate rocks. Examples of evidently too great radiocarbon ages in carbonate formations, which are not explainable by models for the initial {sup 14}C corrections, can easily be explained by this formula. Parameters obtained for a chalk formation from a known multitracer experiment combined with a pumping test suggest a possibility of {sup 14}C ages more than three orders of magnitude greater than the ages which would be observed if the radiocarbon transport took place only in the mobile water in the fissures. It is shown that contrary to the solute movement on a small scale and with a variable input, the large-scale movement, characteristic for the {sup 14}C dating, does not necessarily require the knowledge of kinetic parameters, because they may be replaced by the distribution coefficient. Discordant tritium and {sup 14}C concentrations are commonly interpreted as a proof of mixing either in the aquifer or at the discharge site. For fissured carbonate formations, however, an alternative explanation is given by the derived model showing a considerable delay of {sup 14}C with respect to nonsorbable tracers.

  2. Hydraulic fracturing in tight, fissured media

    SciTech Connect

    Warpinski, N.R. )

    1991-02-01

    Large volumes of natural gas are found in tight, fissured reservoirs. Hydraulic fracturing can enhance recovery, but many complications, such as pressure-sensitive or accelerated leakoff, damage, and complex fracturing, arise during treatment of such reservoirs. This paper reports that special procedures generally should be considered during breakdown and fracturing of these reservoirs. In addition, the use of alternative stimulation strategies may be beneficial.

  3. Earth Fissures in Su-Xi-Chang Region, Jiangsu, China

    NASA Astrophysics Data System (ADS)

    Wang, Guang-ya; You, Greg; Zhu, Jin-qi; Yu, Jun; Li, Wei

    2016-11-01

    The earth fissures in the Su-Xi-Chang area are caused by differential land subsidence due to long-term excessive groundwater withdrawal and controlled by the bedrock ridge or cliff underlying. There have been more than 15 earth fissures in the area since 1989. The field investigations have lasted for more than 20 years. The earth fissures generally have a main fissure and a number of secondary ones parallel to the main one. The main fissure (crack) has a scarp, is steeply dipping, and can be more than 2000 m long. Geophysical surveys (2D or 3D seismic investigation, controlled source audio frequency magnetotelluric sounding, and electric sounding) combined with geological drilling are effective for the investigation of earth fissures. Geodetic leveling is effective to monitor the ground deformation across the earth fissure, so is the extensometer for the opening of the fissure. The activities of earth fissures are directly related to different stages of land subsidence and controlled by geological abnormalities. Most earth fissures in the area are still active.

  4. Lung fissure detection in CT images using global minimal paths

    NASA Astrophysics Data System (ADS)

    Appia, Vikram; Patil, Uday; Das, Bipul

    2010-03-01

    Pulmonary fissures separate human lungs into five distinct regions called lobes. Detection of fissure is essential for localization of the lobar distribution of lung diseases, surgical planning and follow-up. Treatment planning also requires calculation of the lobe volume. This volume estimation mandates accurate segmentation of the fissures. Presence of other structures (like vessels) near the fissure, along with its high variational probability in terms of position, shape etc. makes the lobe segmentation a challenging task. Also, false incomplete fissures and occurrence of diseases add to the complications of fissure detection. In this paper, we propose a semi-automated fissure segmentation algorithm using a minimal path approach on CT images. An energy function is defined such that the path integral over the fissure is the global minimum. Based on a few user defined points on a single slice of the CT image, the proposed algorithm minimizes a 2D energy function on the sagital slice computed using (a) intensity (b) distance of the vasculature, (c) curvature in 2D, (d) continuity in 3D. The fissure is the infimum energy path between a representative point on the fissure and nearest lung boundary point in this energy domain. The algorithm has been tested on 10 CT volume datasets acquired from GE scanners at multiple clinical sites. The datasets span through different pathological conditions and varying imaging artifacts.

  5. [Fissure sealants--5 years of use].

    PubMed

    Azul, A M

    1990-01-01

    This study assesses the caries prevalence, retention and cost-effectiveness of a pit and fissure sealant in a children population with 622 cases, 5 years after a single application of an auto-polymerized sealant to permanent molars. The status of the sealant and the presence of caries or restaurations on the sealed teeth was assessed. In a self-controlled group of children, the prevalence of disease (caries and restaurations) was also assessed in non-sealed teeth, for comparison. The sealant application was compared with Class I-restauration with amalgam for cost-effectiveness analysis.

  6. A Geophysical Study of Fissures in Pahrump, Nevada

    NASA Astrophysics Data System (ADS)

    Hirsch, A. C.; McEwan, M. J.; Howley, R. A.; Mehling, J. B.; Snelson, C. M.; Drohan, P.

    2004-12-01

    Earth fissures are surface expressions of deep fracturing subsidence systems caused by groundwater withdrawl greater than aquifer recharge. This type of subsidence is most common in arid environments of the south western U.S. such as, Las Vegas, NV, Phoenix, AZ, and areas in New Mexico. In addition, fissures have recently been identified in the Pahrump Valley in southwestern Nevada just west of Las Vegas. The city of Pahrump has experienced an increase in population and economic growth. This growth has lead to a higher demand in the use of the areas natural resources. One major concern is groundwater pumping and over-watering of the land surface. Pahrump has experienced significant differential subsidence within the valley causing significant structural damage to infrastructure. This differential subsidence is most readily identified by its surface expression as fissures. Earth fissures are not only shallow surface features but can be 10's of meters deep and 100's of meters long. These ground failures can be exacerbated by faults at depth, shallow bedrock, and/or differential compaction. However, the most significant cause is from groundwater withdrawl. Several geophysical methods were performed on the fissures to better understand their subsurface expression, trend, and ultimately their affect on the city of Pahrump. Seismic refraction, reflection, ground penetrating radar (GPR), and gravity measurements were performed on the fissures and surrounding area including local faults. Our initial studies show the fissures propagating for long distances, in a variety of shapes, and trending in a north-south direction. Initial GPR studies show high fissure reflections at approximately 1 and 1.5 meters along with general slumping features below these reflections. Fissures are an unmitigatable problem. Our results will help identify fissures in the area that do not have a surface expression as well as mapping the current fissures and their extent. These results can be used

  7. Fine Mapping and Introgressing a Fissure Resistance Locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice (Oryza sativa L.) kernel fissuring is a major concern of both rice producers and millers. Fissures are small cracks in rice kernels that increase breakage among kernels when transported or milled, which decrease the value of processed rice. This study employed molecular gene tagging methods to ...

  8. Impact de la preparation des anodes crues et des conditions de cuisson sur la fissuration dans des anodes denses

    NASA Astrophysics Data System (ADS)

    Amrani, Salah

    La fabrication de l'aluminium est realisee dans une cellule d'electrolyse, et cette operation utilise des anodes en carbone. L'evaluation de la qualite de ces anodes reste indispensable avant leur utilisation. La presence des fissures dans les anodes provoque une perturbation du procede l'electrolyse et une diminution de sa performance. Ce projet a ete entrepris pour determiner l'impact des differents parametres de procedes de fabrication des anodes sur la fissuration des anodes denses. Ces parametres incluent ceux de la fabrication des anodes crues, des proprietes des matieres premieres et de la cuisson. Une recherche bibliographique a ete effectuee sur tous les aspects de la fissuration des anodes en carbone pour compiler les travaux anterieurs. Une methodologie detaillee a ete mise au point pour faciliter le deroulement des travaux et atteindre les objectifs vises. La majorite de ce document est reservee pour la discussion des resultats obtenus au laboratoire de l'UQAC et au niveau industriel. Concernant les etudes realisees a l'UQAC, une partie des travaux experimentaux est reservee a la recherche des differents mecanismes de fissuration dans les anodes denses utilisees dans l'industrie d'aluminium. L'approche etait d'abord basee sur la caracterisation qualitative du mecanisme de la fissuration en surface et en profondeur. Puis, une caracterisation quantitative a ete realisee pour la determination de la distribution de la largeur de la fissure sur toute sa longueur, ainsi que le pourcentage de sa surface par rapport a la surface totale de l'echantillon. Cette etude a ete realisee par le biais de la technique d'analyse d'image utilisee pour caracteriser la fissuration d'un echantillon d'anode cuite. L'analyse surfacique et en profondeur de cet echantillon a permis de voir clairement la formation des fissures sur une grande partie de la surface analysee. L'autre partie des travaux est basee sur la caracterisation des defauts dans des echantillons d'anodes crues

  9. Effect of an Antibacterial Monomer on the Antibacterial Activity of a Pit-and-Fissure Sealant

    PubMed Central

    Dong, Yan; Zhang, Ling; Sun, Xiang; Liu, Zhengya; Guo, Huihui; Huang, Li; Chen, Jihua

    2016-01-01

    Resin-based pit-and-fissure sealants are often used to form a barrier on the occlusal surface of molars to treat caries lesions; however, bacteria can remain in the pit and fissures without detection, increasing the risk of secondary caries. Sealants with antimicrobial properties or microbial repellent actions might be advantageous. The aim of this study was to assess the inhibitory effect of a 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB)-incorporated sealant against Streptococcus mutans. MAE-DB (4% wt) was incorporated into a commercially available sealant, Eco-S resin-based pit-and-fissure sealant (Vericom Co., Ltd., Korea); a sealant without MAE-DB served as a negative control, and Clinpro™ Sealant (3M™ ESPE™), a fluoride-releasing resin, was used as a commercial control. The effects of the cured sealants and their eluents on the growth of S. mutans were determined according to colony-forming unit counts and metabolic tests. The effects of the cured sealants on the adherence and membrane integrity of S. mutans were investigated using confocal laser-scanning microscopy (CLSM) in conjunction with fluorescent indicators. Compared with the negative control and commercial control, the cured MAE-DB-incorporated pit-and-fissure sealant exhibited a significant inhibitory effect on the growth of S. mutans (P < 0.05), whereas the eluents did not show any detectable antibacterial activity. The commercial control also showed no detectable bactericidal activity. Moreover, the aged experimental material retained its property of contact inhibition of biofilm formation. The fluorescence analysis of CLSM images demonstrated that the cured MAE-DB-incorporated sealant could hamper the adherence of S. mutans and exert a detrimental effect on bacterial membrane integrity. The incorporation of MAE-DB can render a pit-and-fissure sealant with contact antibacterial activity after polymerization via influencing the growth, adherence, and membrane integrity of S

  10. Tongue fissure extraction and classification using hyperspectral imaging technology.

    PubMed

    Li, Qingli; Wang, Yiting; Liu, Hongying; Sun, Zhen; Liu, Zhi

    2010-04-10

    Tongue fissures, an important feature on the tongue surface, may be pathologically related to some diseases. Most existing tongue fissure extraction methods use tongue images captured by traditional charge coupled device cameras. However, these conventional methods cannot be used for an accurate analysis of the tongue surface due to limited information from the images. To solve this, a hyperspectral tongue imager is used to capture tongue images instead of a digital camera. New algorithms for automatic tongue fissure extraction and classification, based on hyperspectral images, are presented. Both spectral and spatial information of the tongue surface is used to segment the tongue body and extract tongue fissures. Then a classification algorithm based on a hidden Markov model is used to classify tongue fissures into 12 typical categories. Results of the experiment show that the new method has good performance in terms of the classification rates of correctness.

  11. Hawaiian fissure fountains 1: decoding deposits-episode 1 of the 1969-1974 Mauna Ulu eruption

    USGS Publications Warehouse

    Parcheta, C.E.; Houghton, B.F.; Swanson, D.A.

    2012-01-01

    Deposits from episode 1 of the 1969–1974 Mauna Ulu eruption of Kīlauea provide an exceptional opportunity to study processes of low intensity Hawaiian fissure fountains. Episode 1 lava flows passed through dense forest that had little impact on flow dynamics; in contrast, the pattern of spatter preservation was strongly influenced by the forest (through the formation of tree molds) and the preexisting topography. A low, near-continuous spatter rampart is present upwind and upslope, on the north side of the fissure. Most of the pyroclastic products, however, fell downwind to the south of the fissure, but little was preserved due to two processes: (1) incorporation of proximal spatter in rheomorphic lava flows 10–20 m from the vents, and (2) the downslope transport of cooler spatter falling on top of these flows beyond 20 m from vent. The lava flow field itself shows a complex history. Initially, discharge from the fissure exceeded the transport capacity of the southern drainage pathways, and lava ponded dynamically to a maximum height of 4 m for 40–120 min, until fountains began to decline. During declining discharge, lava flowed both southward away from the fissure and increasingly back into the vents. There is a clear “lava-shed” or delineation between where lava drained northwards back into the fissure, and where it continued flowing to the south. The 1969 deposits suggest that care is needed when products of less well-documented eruptions are analyzed, as postdepositional transport of spatter may preclude the formation of classic paired (symmetrical) ramparts.

  12. King's Bowl Pit Crater, Lava Field and Eruptive Fissure, Idaho - A Multipurpose Volcanic Planetary Analog

    NASA Astrophysics Data System (ADS)

    Hughes, S. S.; Garry, B.; Kobs-Nawotniak, S. E.; Sears, D. W. G.; Borg, C.; Elphic, R. C.; Haberle, C. W.; Kobayashi, L.; Lim, D. S. S.; Sears, H.; Skok, J. R.; Heldmann, J. L.

    2014-12-01

    King's Bowl (KB) and its associated eruptive fissure and lava field on the eastern Snake River Plain, is being investigated by the NASA SSERVI FINESSE (Field Investigations to Enable Solar System Science and Exploration) team as a planetary analog to similar pits on the Moon, Mars and Vesta. The 2,220 ± 100 BP basaltic eruption in Craters of the Moon National Monument and Preserve represents early stages of low shield growth, which was aborted when magma supply was cut off. Compared to mature shields, KB is miniscule, with ~0.02 km3 of lava over ~3 km2, yet the ~6 km long series of fissures, cracks and pits are well-preserved for analog studies of volcanic processes. The termination of eruption was likely related to proximity of the 2,270 ± 50 BP eruption of the much larger Wapi lava field (~5.5 km3 over 325 km2 area) on the same rift. Our investigation extends early work by R. Greeley and colleagues, focusing on imagery, compositional variations, ejecta distribution, dGPS profiles and LiDAR scans of features related to: (1) fissure eruptions - spatter ramparts, cones, feeder dikes, extension cracks; (2) lava lake formation - surface morphology, squeeze-ups, slab pahoehoe lava mounds, lava drain-back, flow lobe overlaps; and (3) phreatic steam blasts - explosion pits, ejecta blankets of ash and blocks. Preliminary results indicate multiple fissure eruptions and growth of a basin-filled lava lake up to ~ 10 m thick with outflow sheet lava flows. Remnant mounds of original lake crust reveal an early high lava lake level, which subsided as much as 5 m as the molten interior drained back into the fissure system. Rapid loss of magma supply led to the collapse of fissure walls allowing groundwater influx that triggered multiple steam blasts along at least 500 m. Early blasts occurred while lake magma pressure was still high enough to produce squeeze-ups when penetrated by ejecta blocks. The King's Bowl pit crater exemplifies processes of a small, but highly energetic

  13. Differential compaction mechanism for earth fissures near Casa Grande, Arizona.

    USGS Publications Warehouse

    Jachens, R.C.; Holzer, T.L.

    1982-01-01

    Precise gravity measurements indicate that earth fissures or tension cracks caused by ground-water withdrawal within a 10km2 area SE of Casa Grande are associated with relief on the buried interface between the alluvial aquifer and underlying bedrock. These relations suggest that the fissures are forming in response to localized differential compaction caused by localized variations of aquifer-system thickness. -from Authors

  14. Hardness testing of some fissure-sealing materials.

    PubMed

    Ulvestad, H

    1977-11-01

    The mechanical properties of fissure-sealing materials are of significant importance for their durability, i.e. their wear resistance. One of the methods of evaluating a material's resistance to attrition is to apply a hardness test. In the present investigation, the surface hardness of some fissure-sealing materials was tested. Sealants made from diluted composite materials and with inclusion of inorganic filler particles appeared to have a considerable higher surface hardness than the other sealing materials tested.

  15. Implications of ground-deformation measurements across earth fissures in subsidence areas in the southwestern USA

    USGS Publications Warehouse

    Holzer, Thomas L.

    2010-01-01

    Ground deformation was monitored at earth fissures in areas of land subsidence induced by groundwater extraction in the southwestern United States. The ground deformation is consistent with the mechanism that fissures are caused by horizontal strains generated by bending of overburden in response to localized differential compaction. Subsidence profiles indicated that localized differential subsidence occurred across the fissures and that maximum convex-upward curvature was at the fissure. The overall shape of the profile stayed similar with time, and maximum curvature remained stationary at the fissure. Horizontal displacements were largest near the fissure, and generally were small to negligible away from the fissure. Maximum tensile horizontal strains were at the fissure and coincided with maximum curvature in the subsidence profiles. Horizontal tensile strain continued to accumulate at fissures after they formed with rates of opening ranging from 30 to 120 microstrain/year at fissures in Arizona.

  16. Potential for aquifer compaction, land subsidence, and earth fissures in the Tucson basin, Pima County, Arizona

    USGS Publications Warehouse

    Anderson, S.R.

    1987-01-01

    In 1979 the U.S. Geological Survey, in cooperation with the city of Tucson, began an investigation of aquifer compaction and its effects in the Tucson basin, including the potential hazards of aquifer compaction and subsequent damage to engineered structures, roads, water supply systems, gaslines, and sewage systems. Groundwater is the main source of water for irrigation, public supply, and industry. Pumping has exceeded recharge for several decades, and declines in groundwater levels have occurred in parts of the basin. In places, water level declines have resulted in small amounts of aquifer compaction and land subsidence. Further water level declines in parts of the Tucson basin may result in large amounts of aquifer compaction and land subsidence. Differential land subsidence may, in places, be accompanied by the formation of earth fissures. Aquifer compaction, land subsidence, and earth fissures can damage or affect the functional capability of manmade features. Specifically, aquifer compaction may damage wells, fissures may damage engineered structures, and differential land subsidence may affect structures such as sewers and water-supply systems that are dependent on gravity for their operation. (USGS)

  17. Laser fluorescence detection of demineralization in artificial occlusal fissures.

    PubMed

    Ferreira Zandoná, A G; Analoui, M; Schemehorn, B R; Eckert, G J; Stookey, G K

    1998-01-01

    Laser fluorescence (LF) has been used previously to detect early smooth-surface lesions. Although its use for detection of occlusal demineralization has been implicated, it has not been demonstrated. The aim of this study was to determine whether LF could detect demineralization in the base of artificial fissures. To employ LF for detection of occlusal demineralization an apparatus was devised to direct laser light into fissures and simultaneously detect fluorescence from the base of the fissures. Three groups (n = 40/group) of differing fissure types were prepared (straight wall, converging and diverging wall) with either a sound or lesioned base. One half of each group was examined with LF and dye-enhanced LF (DELF); the other half was examined with LF, exposed to plaque, examined with LF and DELF, air-polished and examined with DELF. All images were scored twice as either (1) carious; (2) sound, or (3) undetermined, by a group of 3 examiners. For fissures without plaque, the average sensitivity was higher for DELF (0.76) than for LF (0.54) (p < 0.05). Likewise, the average specificity was higher for DELF (0.64) than for LF (0.29) (p < 0.05). In the presence of plaque, sensitivity was higher for DELF (0.91) compared to LF (0.43); however, specificity was lower for DELF (0.05) compared to LF (0.55). When the fissures were air-polished and then examined with DELF, sensitivity averaged 0.82 (p < 0.05), and specificity increased consistently (average 0.51, p < 0.05). It was concluded that, in the absence of plaque, DELF was a better diagnostic tool than LF for detection of demineralization in artificial fissures.

  18. Open Fissure Folds record coseismic loading and postseismic stress relaxation

    NASA Astrophysics Data System (ADS)

    Nüchter, Jens-Alexander

    2015-03-01

    Open Fissure Folds hosted by high pressure/low temperature metamorphic rocks of south Evia (Greece) are introduced, their structural and microstructural record is analysed, and a mechanical model is proposed. Open Fissure Folds are preserved as at least two parallel folded quartz-feldspar veins separated by narrow buckled rock columns. The veins originated as tensile cracks that propagated in the middle crust driven by high differential stress. Features diagnostic for Open Fissure Folds indicate that the rock columns represented the layers of high viscosity, and not the veins as consistently reported in many previous studies on folded veins. This record is taken to indicate that buckling of the rock columns initiated after arrest of the fractures and terminated prior to complete vein sealing. Accordingly, mechanical decoupling by open fissures allowed for buckling of the rock columns in response to episodic creep of the host rocks according to stress relaxation, as expected for postseismic deformation in the earthquake cycle. I propose that the parental fractures propagated in response to quasi-instantaneous coseismic loading of the middle crust. Buckling was attributed to transient postseismic creep and stress relaxation. Complete sealing of the veins occurred when stresses were largely relaxed. Each Open Fissure Fold records the stress and strain history of a single earthquake.

  19. Marginal Microleakage of Conventional Fissure Sealants and Self-Adhering Flowable Composite as Fissure Sealant in Permanent Teeth

    PubMed Central

    Rahimian-Imam, Sara; Fayazi, Mohammad Reza

    2015-01-01

    Objectives: Application of sealants is a safe and effective way to prevent occlusal caries in the posterior teeth. A successful sealant therapy depends on good isolation. Decreased steps of adhesive application may enable proper isolation and use of self-adhering flowable composites for sealant therapy. This study sought to compare the marginal microleakage of fissure sealants and self-adhering flowable composites in permanent teeth. Materials and Methods: This in vitro, experimental study was conducted on 60 extracted human premolar teeth. The teeth were divided randomly into two groups of 30. In the first group, fissure sealant (Clinpro, 3M ESPE, USA) was placed on the teeth. In the second group, self-adhering flowable composite (Vertise Flow, Kerr, USA) was applied as the sealant. Then, both groups were immersed in 0.5% fuchsin dye solution for 24 hours. Sectioned samples were observed with a stereomicroscope for the extent of dye penetration. Data were analyzed using SPSS 21 and the Mann-Whitney test (P<0.05). Results: Microleakage in the fissure sealant group was significantly higher than that in the self-adhering flowable composite group (P<0.001). Conclusion: Microleakage was less using self-adhering flowable composite compared to conventional fissure sealant; therefore, self-adhering flowable composite can be used as a suitable fissure sealant in permanent teeth. PMID:26884777

  20. Engineering a robotic approach to mapping exposed volcanic fissures

    NASA Astrophysics Data System (ADS)

    Parcheta, C. E.; Parness, A.; Mitchell, K. L.

    2014-12-01

    Field geology provides a framework for advanced computer models and theoretical calculations of volcanic systems. Some field terrains, though, are poorly preserved or accessible, making documentation, quantification, and investigation impossible. Over 200 volcanologists at the 2012 Kona Chapman Conference on volcanology agreed that and important step forward in the field over the next 100 years should address the realistic size and shape of volcanic conduits. The 1969 Mauna Ulu eruption of Kīlauea provides a unique opportunity to document volcanic fissure conduits, thus, we have an ideal location to begin addressing this topic and provide data on these geometries. Exposed fissures can be mapped with robotics using machine vision. In order to test the hypothesis that fissures have irregularities with depth that will influence their fluid dynamical behavior, we must first map the fissure vents and shallow conduit to deci- or centimeter scale. We have designed, constructed, and field-tested the first version of a robotic device that will image an exposed volcanic fissure in three dimensions. The design phase included three steps: 1) create the payload harness and protective shell to prevent damage to the electronics and robot, 2) construct a circuit board to have the electronics communicate with a surface-based computer, and 3) prototype wheel shapes that can handle a variety of volcanic rock textures. The robot's mechanical parts were built using 3d printing, milling, casting and laser cutting techniques, and the electronics were assembled from off the shelf components. The testing phase took place at Mauna Ulu, Kīlauea, Hawai'i, from May 5 - 9, 2014. Many valuable design lessons were learned during the week, and the first ever 3D map from inside a volcanic fissure were successfully collected. Three vents had between 25% and 95% of their internal surfaces imaged. A fourth location, a non-eruptive crack (possibly a fault line) had two transects imaging the textures

  1. Hemorrhoids and anal fissures in inflammatory bowel disease.

    PubMed

    D'Ugo, S; Stasi, E; Gaspari, A L; Sileri, P

    2015-12-01

    Perianal disease is a common complication of inflammatory bowel disease (IBD). It includes different conditions from more severe and potentially disabling ones, such as abscesses and fistulas, to more benign conditions such as hemorrhoids, skin tags and fissures. Most literature has been focused on anal sepsis and fistulae, as they carry the majority of disease burden and often alter the natural course of the disease. Hemorrhoids and anal fissures in patients with IBD have been overlooked, although they can represent a challenging problem. The management of hemorrhoids and fissures in IBD patients may be difficult and may significantly differ compared to the non-affected population. Historically surgery was firmly obstructed, and hemorrhoidectomy or sphincterotomy in patients with associated diagnosis of IBD was considered harmful, although literature data is scant and based on small series. Various authors reported an incidence of postoperative complications higher in IBD than in the general populations, with potential severe events. Considering that a spontaneous healing is possible, the first line management should be a medical therapy. In patients non-responding to conservative measures it is possible a judicious choice of surgical options on a highly selective basis; this can lead to acceptable results, but the risk of possible complications needs to be considered. In this review it is analyzed the current literature on the incidence, symptoms and treatment options of hemorrhoids and anal fissures in patients with Crohn's disease and ulcerative colitis.

  2. Dental Pit and Fissure Sealants: Implications for School Health Personnel.

    ERIC Educational Resources Information Center

    McCormack-Brown, K. R.; And Others

    1989-01-01

    To promote good personal hygiene practices in students, school health personnel must be informed about dental pit and fissure sealants and related programs. Adoption and maintenance of such programs may depend on the success of school health personnel in educating administrators and policymakers. (SM)

  3. Palpebral fissure changes after monobloc frontofacial advancement in faciocraniosynostosis.

    PubMed

    Cruz, Antonio Augusto V; Akaishi, Patricia Mitiko S; Arnaud, Eric; Marchac, Daniel; Renier, Dominique

    2008-01-01

    There is virtually no literature on the effect of correction of syndromal faciocraniosynostosis with monobloc advancement on the palpebral fissure shape. Using image processing software, we measured the effect of monobloc advancement on the position of the upper and lower eyelids as well as the palpebral fissure slant in a series of 18 patients with syndromal faciocraniosynostosis who had undergone surgery for correction of orbital and midface hypoplasia. For both eyes of each patient, 3 variables were measured on the pre- and postoperative photographs: the linear distances between the upper and lower eyelid margins, the pupil center and the angle between the inner and outer canthi. The globe protrusion was also measured on axial computed tomography scans before and after surgery. The results indicate that the exorbitism reduction induced by monobloc advancement is accompanied by a diminution of the distance between both eyelids and the pupil center. However, the downward slant of the palpebral fissure is increased after surgery. The data suggest that the lower and upper eyelid retraction seen preoperatively in the majority of patients with faciocraniosynostosis tend to be corrected when the frontofacial region is advanced by the monobloc. On the other hand, the surgery tends to lower the outer canthus, increasing the negative slant of the fissure. The postoperative changes induced by the frontofacial monobloc advancement need to be taken into account when the surgery is going to be performed.

  4. New method opens opportunity to proactively select for fissure resistance in early breeding generations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    WANTED: New rice varieties improved for resistance to kernel fissuring. Rice kernel fissuring is one of the leading causes of reduced milling yield. Any reduction in fissuring can result in direct increases in yield and profit for both producers and millers. While most U.S. rice varieties yield a...

  5. Selection for fissure resistance now made possible in early breeding generations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice kernel fissuring is one of the leading causes of milling yield losses. Any reduction in fissuring can result in direct increases in yield and profit for both producers and millers. While most U.S. rice varieties yield around 55% head rice, the fissure-resistant varieties ‘Cypress’, ‘Saber’ an...

  6. Basaltic fissure eruptions, plume heights, and atmospheric aerosols

    NASA Technical Reports Server (NTRS)

    Stothers, R. B.; Wolff, J. A.; Self, S.; Rampino, M. R.

    1986-01-01

    Convective plumes that rise above Hawaiian-style fire fountains consist of volcanic gases, aerosols, fine ash, and entrained heated air. Plume theory has been applied to observational estimates of the rate of thermal energy release from large fire fountains. The theoretically predicted heights of maintained plumes agree very well with the heights found from actual observations. Predicted plume heights for both central-vent (point-source) and fissure (line-source) eruptions indicate a stratospheric penetration by plumes that form over vents with very high magma-production rates. Flood basalt fissure eruptions that produce individual lava flows with volumes greater than 100 cu km at very high mass eruption rates are capable of injecting large quantities of sulfate aerosols into the lower stratosphere, with potentially drastic short-term atmospheric consequences, like acid precipitation, darkening of the sky, and climatic cooling.

  7. Interaction between central volcanoes and fissure swarms along divergent plate boundaries: an example from Askja Volcano, Northern Iceland.

    NASA Astrophysics Data System (ADS)

    Trippanera, Daniele; Ruch, Joel; Acocella, Valerio; Urbani, Stefano; Thordarson, Thor

    2016-04-01

    Central volcanoes located along divergent plate boundaries are typically part of a larger volcanic system that consists of a central edifice and a fissure swarm through which magma propagates and spreads plates apart. Regional normal faults and graben structures develop within the volcanic system, also dissecting portions of the central volcano with ring-faults faults and eruptive fissures related to the caldera structure. Both the fissure swarm and the caldera structure influence the pathway of the ascending magma, however, the influences of the structures on magma propagation and vice versa are not well defined and understood. Here we aim to understand the relationship between the activity of the central volcano structures (e.g. caldera ring faults, radial dykes and cone sheets) and those of the fissure swarm (e.g. regional normal faults, regional dikes). We focus on Askja volcano, located in the Northern Volcanic Zone of Iceland. It is comprised of three nested calderas, largely filled in with subaerial basaltic lava flows and surrounded by a massive hyaloclastite mountain on the Eastern side. Formation of the youngest, the Öskjuvatn caldera, was initiated during the 1874-1876 rifting episode on the Askja system. This major event was followed by several localized radial and circumferential magmatic intrusions taking place along the new-formed caldera ring fault, as well as intruding in the fissure swarm related to the regional tectonics. In order to characterize the influence of the caldera structure on the regional tectonics, we analysed the structural framework of the caldera and direct surroundings using remote sensing (optical imagery and high resolution DEM from TanDEM-X data). Then we made detailed field measurements (500 data) by analysing azimuth, dip, and opening of eruptive fissures, dikes, faults and extension fractures. Both remote sensing and field measurements have been then integrated producing a detailed structural map of Askja. Our results show

  8. Injectabilite des coulis de ciment dans des milieux fissures

    NASA Astrophysics Data System (ADS)

    Mnif, Thameur

    Le travail presente ici est un bilan du travaux de recherche effectues sur l'injectabilite des coulis de ciment dans lu milieux fissures. Un certain nombre de coulis a base de ciment Portland et microfin ont ete selectionnes afin de caracteriser leur capacite a penetrer des milieux fissures. Une partie des essais a ete menee en laboratoire. L'etude rheologique des differents melanges a permis de tester l'influence de l'ajout de superplastifiant et/ou de fumee de silice sur la distribution granulometrique des coulis et par consequent sur leur capacite a injecter des colonnes de sable simulant un milieu fissure donne. La classe granulometrique d'un coulis, sa stabilite et sa fluidite sont apparus comme les trois facteurs principaux pour la reussite d'une injection. Un facteur de finesse a ete defini au cours de cette etude: base sur la classe granulometrique du ciment et sa stabilite, il peut entrer dans la formulation theorique du debit d'injection avant application sur chantier. La deuxieme et derniere partie de l'etude presente les resultats de deux projets de recherche sur l'injection realises sur chantier. L'injection de dalles de beton fissurees a permis le suivi de l'evolution des pressions avec la distance au point d'injection. L'injection de murs de maconnerie a caractere historique a montre l'importance de la definition de criteres de performance des coulis a utiliser pour traiter un milieu donne et pour un objectif donne. Plusieurs melanges peuvent ainsi etre predefinis et mis a disposition sur le chantier. La complementarite des ciments traditionnels et des ciments microfins devient alors un atout important. Le choix d'utilisation de ces melanges est fonction du terrain rencontre. En conclusion, cette recherche etablit une methodologie pour la selection des coulis a base de ciment et des pressions d'injection en fonction de l'ouverture des fissures ou joints de construction.

  9. Modeling plaque fissuring and dissection during balloon angioplasty intervention.

    PubMed

    Gasser, T Christian; Holzapfel, Gerhard A

    2007-05-01

    Balloon angioplasty intervention is traumatic to arterial tissue. Fracture mechanisms such as plaque fissuring and/or dissection occur and constitute major contributions to the lumen enlargement. However, these types of mechanically-based traumatization of arterial tissue are also contributing factors to both acute procedural complications and chronic restenosis of the treatment site. We propose physical and finite element models, which are generally useable to trace fissuring and/or dissection in atherosclerotic plaques during balloon angioplasty interventions. The arterial wall is described as an anisotropic, heterogeneous, highly deformable, nearly incompressible body, whereas tissue failure is captured by a strong discontinuity kinematics and a novel cohesive zone model. The numerical implementation is based on the partition of unity finite element method and the interface element method. The later is used to link together meshes of the different tissue components. The balloon angioplasty-based failure mechanisms are numerically studied in 3D by means of an atherosclerotic-prone human external iliac artery, with a type V lesion. Image-based 3D geometry is generated and tissue-specific material properties are considered. Numerical results show that in a primary phase the plaque fissures at both shoulders of the fibrous cap and stops at the lamina elastica interna. In a secondary phase, local dissections between the intima and the media develop at the fibrous cap location with the smallest thickness. The predicted results indicate that plaque fissuring and dissection cause localized mechanical trauma, but prevent the main portion of the stenosis from high stress, and hence from continuous tissue damage.

  10. The architecture and shallow conduits of Laki-type pyroclastic cones: insights into a basaltic fissure eruption

    NASA Astrophysics Data System (ADS)

    Reynolds, P.; Brown, R. J.; Thordarson, T.; Llewellin, E. W.

    2016-05-01

    Pyroclastic cones built along basaltic fissures provide important volcanological information, but it is often difficult to examine the early-erupted products due to burial by later products. Furthermore, it is rare to see the link between the feeder dyke and overlying cone fully exposed. In this study, we detail the architecture of a hybrid spatter cone, scoria half-cone and feeder dyke that has been dissected to below the pre-eruption surface by glacial floods. The cones were constructed during the 6-8 ka Rauðuborgir-Kvensöðul fissure eruption in North Iceland during Hawaiian- and Strombolian-style activities. Widening of their feeder dyke in the shallow sub-surface to produce an upward flaring morphology was accommodated by country rock removal and elastic host rock deformation. Ballistic calculations and stratigraphic relationships indicate that the scoria half-cone was constructed early in the eruption from the deposits of a lava fountain ~100 m high. A decline in fountain height and the generation of abundant welded deposits resulted in the formation of a nested spatter cone within the scoria half-cone. The cones are similar in structure and size to the hybrid scoria and spatter cones produced during the 15-km3 1783 Laki eruption and serve as a valuable window into the construction of pyroclastic edifices during basaltic fissure eruptions.

  11. The fissure: interlobar collateral ventilation and implications for endoscopic therapy in emphysema.

    PubMed

    Koster, Theodoor David; Slebos, Dirk-Jan

    2016-01-01

    In patients with severe emphysema, bronchoscopic lung volume reduction using one-way valves is a promising therapeutic option to improve lung function and quality of life. The goal of this treatment is to achieve a complete lobar atelectasis. In a significant proportion of patients, this atelectasis cannot be achieved due to interlobar collateral ventilation. This collateral ventilation is generated through incomplete lobar fissures. Therefore, only patients with complete fissures and no collateral ventilation can be selected for endobronchial therapy with one-way valves. Incomplete fissures are very common and exhibit a great variation in anatomy. The reported prevalence is 17%-85% for the right major fissure, 19%-74% for the left major fissure, and 20%-90% for the minor fissure. There are several methods of measuring or predicting the presence of collateral ventilation, with computed tomography (CT)-fissure analysis and the Chartis measurement being the most important. CT-fissure analysis is an indirect method to measure the completeness of fissures as a surrogate for collateral ventilation. The Chartis system is an endobronchial method to directly measure the presence of collateral ventilation. Both methods have unique value, and the combination of both can accurately predict the treatment response to the bronchoscopic placement of endobronchial valves. This review provides an in-depth view of lung fissure and collateral ventilation to help understand its importance in selecting the appropriate patients for new emphysema treatments and thus avoid useless treatment in unsuitable patients.

  12. Enamel fusion using a carbon dioxide laser: A technique for sealing pits and fissures

    SciTech Connect

    Walsh, L.J.; Perham, S.J. )

    1991-05-01

    The well-established enhanced resistance of lased enamel to demineralization is the basis for clinical application of the carbon dioxide laser to caries prevention. This in vitro study examined the effect of focused infrared laser radiation on sound enamel and early pit and fissure caries. Low power levels (2-5 W) induced localized melting and resolidification of enamel with little surface destruction. For sound fissures, fusion of enamel from the lateral walls of the fissure eliminated the fissure space, providing a sealant effect; while in carious fissures, carious enamel was vaporized and adjacent sound enamel fused to partially eliminate the defect. The technique for enamel fusion using CO2 lasers has potential application for sealing pits and fissures and producing physicochemical alterations in enamel which may have preventive benefits.

  13. Joints, fissures, and voids in rhyolite welded ash-flow tuff at Teton damsite, Idaho

    USGS Publications Warehouse

    Prostka, Harold J.

    1977-01-01

    Several kinds of joints, fissures, and voids are present in densely welded rhyolite ash-flow tuff at Teton damsite. Older fissures and voids probably were formed in the ash-flow sheet during secondary flowage, which probably was caused by differential compaction or settling over irregular topography. The younger, more abundant fissures are mostly steep cooling joints that probably have been opened farther by horizontal tectonic extension and gravitational creep, perhaps aided by lateral stress relief.

  14. Surface anatomy of the pulmonary fissures determined by high-resolution computed tomography.

    PubMed

    Heřmanová, Zuzana; Ctvrtlík, Filip; Heřman, Miroslav

    2012-10-01

    The aim of our study was to describe the surface anatomy of the interlobar fissures using volumetric thin-section high-resolution computed tomography (HRCT). Retrospective assessment of HRCT examinations of 250 patients was performed. The localization of the oblique fissures was marked at three sites: posteriorly at its most superior medial limit, laterally in the midaxillary line, and inferiorly at the junction of the middle and lateral thirds of the hemithorax; posteriorly and laterally, this was to the nearest rib whilst inferiorly the position was described in relation to the diaphragm or chest wall. The localization of the horizontal fissure was marked anteriorly in relation to the nearest rib (or costal cartilage) and posteriorly where it intersected with the oblique fissure (superior, middle, or inferior third). Shapes of the fissures and differences between inspiration and expiration were also documented. Descriptive statistics were used to report the most frequent positions. The most frequent localization of the oblique fissure on the left side was posteriorly at the fourth rib (45%), laterally at the sixth rib (52%), and inferiorly in the anterior third of the hemidiaphragm (60%). The right oblique fissure was located posteriorly at the fifth rib (50%), laterally at the sixth rib (50%), and inferiorly in the anterior third of the hemidiaphragm (71%). The horizontal fissure most commonly originated in the middle third of the oblique fissure (61%) and met the anterior thoracic wall at the level of the fourth rib (51%). The most frequent shape of the left oblique fissure was linear (78%), whereas S-shaped and linear configurations (28% each) were most frequent on the right. No difference was found in the surface markings of the fissures between inspiration and expiration in 90% of cases. The considerable individual variation in the position and shape of the interlobar fissures helps to explain the variable descriptions of their surface anatomy in the

  15. Bonding Agents in Pit and Fissure Sealants: A Review

    PubMed Central

    Das, Usha Mohan; G, Suma

    2009-01-01

    Dental adhesive systems used for bonding dental resins to enamel and dentin have evolved through several "generations," with changes in chemistry, mechanism, number of bottles, application technique, and clinical effectiveness. The trend in the latest generation of dental bonding systems is to reduce the number of components and clinical placement steps. The introduction of i bond, a single-bottle dental adhesive system, is the latest of the new generation materials, and combines etchant, adhesive, and desensitizer in one component. This paper describes different dentin bonding agents, its evolution, mechanism of action and different commercially available dentin bonding agents and their role in the retention of pit and fissure sealant. PMID:25206115

  16. A rare case of myeloid sarcoma presenting as anal fissure

    PubMed Central

    VECCHIO, R.; INTAGLIATA, E.; FIUMARA, P.F.; VILLARI, L.; MARCHESE, S.; CACCIOLA, E.

    2015-01-01

    Myeloid sarcoma is a tumor composed of myeloblasts occurring at an extramedullary site. It may develop in patients with acute myeloid leukemia, myeloproliferative or myelodysplastic syndrome, sometimes preceding onset of the systemic disease. Frequent sites of myeloid sarcoma are bones or various soft tissues. Gastrointestinal involvement is very rare. We report a unique case of myeloid sarcoma presenting as a painful anal fissure, in a patient with a history of acute myeloid leukemia. The diagnosis was achieved by a surgical excisional biopsy and immunoistochemical staining. PMID:26712260

  17. Sylvian fissure epidermoid cyst presenting with intention tremor

    PubMed Central

    Shah, Abhidha; Makkiyah, Feda; Goel, Atul

    2016-01-01

    Epidermoid tumors are benign tumors which contain keratin, cellular debris, and cholesterol, and are lined with stratified squamous epithelium. They grow in discreet silence sustained over a multitude of years. The tumors most commonly present with headache and seizures. We report the case of a 24-year-old male with a large sylvian fissure epidermoid tumor who presented with intention tremor. The patient was operated, and a near-total excision of the tumor was performed with a resolution of the tremor. PMID:27057232

  18. Research of features related to land subsidence and ground fissure disasters in the Beijing Plain

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Luo, Y.; Liu, M.; Wang, R.; Wang, H.

    2015-11-01

    This study overviews the development history, current situation, impact, and hazards of land subsidence and ground fissure disasters in the Beijing Plain (BP) and focuses on the disaster distribution and features of disaster-causing mechanisms. Currently, the BP is still in a rapid developmental stage of land subsidence. The development and distribution of land subsidence are affected by various factors including the thickness of Quaternary compressible clay, groundwater overexploitation, and the rapid development of urban construction. The causes of ground fissures in the BP are complex and diverse, with evidence of structure fissures, non-structure fissures, and mixed genesis fissures. Investigations of the Gaoliying ground fissure have shown that this fissure has evidence of fracture activity, with vertical deformation that is more significant than horizontal deformation. Furthermore, this ground fissure has characteristics of inter-annual periodicity and annual jumping. The land subsidence and ground fissures are all under structural control and impact each other, and more severe hazards may be induced under the superimposition of these two types of disasters. Effective measures and suggestions for disaster prevention and control are recommended on the basis of this study.

  19. On homogenization of a variational inequality for an elastic body with periodically distributed fissures

    SciTech Connect

    Pastukhova, S E

    2000-02-28

    We study the problem of small deformations of an elastic body with periodically distributed fissures, where one-sided constraints are imposed on the sides of the fissures; this problem is equivalent to a variational inequality. We prove that if the linear size of the period of the distribution of the fissures tends to zero, then the solutions of this problem converge in the L{sup 2}-norm to the solution of the homogenized problem, which is a non-linear boundary-value problem of elasticity theory for a domain without fissures.

  20. Fissure eruptions at Mount Vesuvius (Italy): Insights on the shallow propagation of dikes at volcanoes

    NASA Astrophysics Data System (ADS)

    Acocella, Valerio; Porreca, Massimiliano; Neri, Marco; Mattei, Massimo; Funiciello, Renato

    2006-08-01

    Fissure eruptions may provide important information on the shallow propagation of dikes at volcanoes. Somma-Vesuvius (Italy) consists of the active Vesuvius cone, bordered to the north by the remnants of the older Somma edifice. Historical chronicles are considered to define the development of the 37 fissure eruptions between A.D. 1631 and 1944. The 1631 fissure, which reopened the magmatic conduit, migrated upward and was the only one triggered by the subvertical propagation of a dike. The other 25 fissure eruptions migrated downward, when the conduit was open, through the lateral propagation of radial dikes. We suggest two scenarios for the development of the fissures. When the summit conduit is closed, the fissures are fed by vertically propagating dikes. When the summit conduit is open, the fissures are fed by laterally propagating dikes along the volcano slopes. Consistent behaviors are found at other composite volcanoes, suggesting a general application to our model, independent of the tectonic setting and composition of magma. At Vesuvius, the historical data set and our scenarios are used to predict the consequences of the emplacement of fissures after the opening of the conduit. The results suggest that, even though the probability of opening of vents within the inhabited south and west slopes is negligible, the possibility that these are reached by a lava flow remains significant.

  1. Preserving rice quality: fine mapping and introgressing a fissure resistance locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice (Oryza sativa L.) kernel fissuring is a major concern of both rice producers and millers. Fissures are small cracks in the rice kernels that increase the percentage of breakage among the kernels when they are transported and milled, which decreases the value of processed rice. This study employ...

  2. Early screening of recombinant inbred lines for fissure resistance in non-semidwarf rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice (Oryza sativa L.) kernel fissuring poses a major problem for both rice farmers and millers. It results in the decreased value of milled rice because of the increase in the percentage of broken kernels associated with fissuring. This study employs the use of fine mapping to increase the genetic ...

  3. Response to early generation selection for resistance to rice kernel fissuring

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The value of milled rice (Oryza sativa L.) depends on the percent whole versus broken kernels after milling. Kernel fissures caused by pre- or post-harvest stresses are the leading cause of breakage upon milling. ‘Cypress’ is known to be more fissure resistant (FR) than most cultivars, but breeding ...

  4. Video monitoring analysis of the dynamics at fissure eruptions

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2016-04-01

    At basaltic eruption often lava fountains occur. The fountains mainly develop at erupting fissures, underlain by a magma-filled dike transporting the magma horizontally and vertically. Understanding of the dynamics of the deep dike and fracture mechanisms are mainly based on geophysical data as well as observations from seismic or geodetic networks. At the surface, however, new methods are needed to allow detailed interpretation on the eruption velocities, interactions between vents and complexities in the magma paths. With video cameras we collected imaging data from different erupting fissures. We find that lava fountaining is often correlated at distinct vents. From the frames of the videos we calculated the height and velocities of fountains as a function of time. Lava fountains often show a pulsating regime, that may change over time. Comparing the fountain height as a function of time of different vents by an time-dependent cross-correlation, we find a time lag between the pulses at adjacent vents. From this we derive an apparent velocity of temporal separation between vents, associated with the fountaining activity based on the calculated time lag and the vent distances. Although the correlation system can change episodically and sporadically, both the frequency of the fountains and eruption and the rest time between single fountains remain remarkably similar for adjacent lava fountains imply a controlling process in the magma feeder system itself. We present and compare our method for the Kamoamoa eruption 2011 (Hawaii) and the Holuhraun eruption 2014/2015 (Iceland). Both sites show a significant time shift between the single pulses of adjacent vents. We compare our velocities determined by this time shift to the assumed magma flow velocity in the dike as determined by independent models. Therefore we conjecture that the time shift of venting activity may allow to estimate the dynamics of magma and fluid migration at depth, as well as to identify the

  5. Pleistocene microvertebrates from fissure-fillings in Thailand

    NASA Astrophysics Data System (ADS)

    Chaimanee, Yaowalak; Jaeger, Jean-Jacques; Suteethorn, Varavudh

    Microvertebrates (and among them specially, rodents) have contributed to the elaboration of precise biochronological time scales and to the reconstitution of Pleistocene paleoenvironments in several parts of the world (North America, Africa, Europe and Japan). They have been demonstrated to be highly sensitive to climatic changes since they are very sensitive to vegetation changes. Up to now, no data is available for Southeast Asia and very few information is available concerning the nature of climatic changes which affected that part of the tropical world during the Pleistocene. In the past few years, we have discovered several fissure fillings in Thailand yielding numerous remains of microvertebrates which have been extracted by dissolution in acetic acid solution. These deposits are the result of the feeding activity of predators, like owls or diurnal raptors, whose pellets are accumulated in caves or fissures. Eleven localities, located in Central (2), Eastern (1), Western (2) and Peninsular Thailand (6) have been investigated so far. Several rodent species, belonging to 9 genera of Murinae (rats and mice) and 9 genera of Sciuridae (squirrels) have been identified in these localities. The most important differences with the extant representatives often concern the size of the teeth of these fossil species. The meaning of these size differences is not yet clearly understood since they can be attributed either to significant time differences between localities (microevolution) or as the result of size variations related to climatic changes (clinical variations). More data will have to be collected to calibrate the temporal frame. Already, important modification of the geographic distribution of some species have been discovered which testify that during the Pleistocene, significative climatic changes have affected Southeast Asia. For example, Exilisciurus, a squirrel which is presently restricted to Borneo has been recognized in Peninsular Thailand. Also, Iomys

  6. Fissure sealant materials: Wear resistance of flowable composite resins

    PubMed Central

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

    2016-01-01

    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm2 and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm2of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics. PMID:27651887

  7. Fissure sealant materials: Wear resistance of flowable composite resins.

    PubMed

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

    2016-01-01

    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  8. Discrete element modeling on the crack evolution behavior of brittle sandstone containing three fissures under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Yang, Sheng-Qi; Huang, Yan-Hua; Ranjith, P. G.; Jiao, Yu-Yong; Ji, Jian

    2015-12-01

    Based on experimental results of brittle, intact sandstone under uniaxial compression, the micro-parameters were firstly confirmed by adopting particle flow code (PFC^{2D}). Then, the validation of the simulated models were cross checked with the experimental results of brittle sandstone containing three parallel fissures under uniaxial compression. The simulated results agreed very well with the experimental results, including the peak strength, peak axial strain, and ultimate failure mode. Using the same micro-parameters, the numerical models containing a new geometry of three fissures are constructed to investigate the fissure angle on the fracture mechanical behavior of brittle sandstone under uniaxial compression. The strength and deformation parameters of brittle sandstone containing new three fissures are dependent to the fissure angle. With the increase of the fissure angle, the elastic modulus, the crack damage threshold, and the peak strength of brittle sandstone containing three fissures firstly increase and secondly decrease. But the peak axial strain is nonlinearly related to the fissure angle. In the entire process of deformation, the crack initiation and propagation behavior of brittle sandstone containing three fissures under uniaxial compression are investigated with respect to the fissure angle. Six different crack coalescence modes are identified for brittle sandstone containing three fissures under uniaxial compression. The influence of the fissure angle on the length of crack propagation and crack coalescence stress is evaluated. These investigated conclusions are very important for ensuring the stability and safety of rock engineering with intermittent structures.

  9. Infrasound from the 2007 fissure eruptions of Kīlauea Volcano, Hawai'i

    USGS Publications Warehouse

    Fee, D.; Garces, M.; Orr, T.; Poland, M.

    2011-01-01

    Varied acoustic signals were recorded at Kīlauea Volcano in mid-2007, coincident with dramatic changes in the volcano's activity. Prior to this time period, Pu'u 'Ō'ō crater produced near-continuous infrasonic tremor and was the primary source of degassing and lava effusion at Kīlauea. Collapse and draining of Pu'u 'Ō'ō crater in mid-June produced impulsive infrasonic signals and fluctuations in infrasonic tremor. Fissure eruptions on 19 June and 21 July were clearly located spatially and temporally using infrasound arrays. The 19 June eruption from a fissure approximately mid-way between Kīlauea's summit and Pu'u 'O'o produced infrasound for ~30 minutes-the only observed geophysical signal associated with the fissure opening. The infrasound signal from the 21 July eruption just east of Pu'u 'Ō'ō shows a clear azimuthal progression over time, indicative of fissure propagation over 12.9 hours. The total fissure propagation rate is relatively slow at 164 m/hr, although the fissure system ruptured discontinuously. Individual fissure rupture times are estimated using the acoustic data combined with visual observations.

  10. Preferential flow in fissured sediments in desert soils related to radioactive waste disposal

    SciTech Connect

    Scanlon, B.R.; Raney, J.A. . Bureau of Economic Geology)

    1992-01-01

    Unsaturated flow in fissured sediments in the Chihuahuan Desert of Texas was examined to determine if these features act as preferred pathways for water and solute transport. Fissures are surface features, or gulleys, that are underlain by fractures filled with sediment derived from surrounding areas. Hydraulic and chemical approaches were used to investigate unsaturated flow processes beneath and adjacent to fissures, and the results were compared with data from surrounding geomorphic systems such as arroyos, ephemeral streams, and interstreams. Typically, high water potentials in surficial sediments result from infiltration of recent precipitation. Below this surficial zone of high water potentials lies a zone of low water potentials that is much thinner beneath the fissure than in adjacent sediments or in sediments beneath ephemeral streams and interstreams. Maximum chloride concentrations in profiles in the near-surface fissured sediments were much lower than those measured in all other geomorphic systems. The corresponding moisture velocities in the fissured sediments ranged from 10 to 70 mm/yr. A tracer experiment demonstrated higher downward water and solute transport in the fracture fill beneath the fissure relative to adjacent sediments. Numerical simulations of the tracer experiment with the computer code TRACR3D reproduced the overall shape of the tracer plume. Sensitivity analyses demonstrated that the tracer plume is most sensitive to spatial variability in soil texture and the corresponding hydraulic parameters. The results from this study suggest that sediments in the fissured area act as preferred pathways in the shallow subsurface because surface runoff is concentrated in the fissures and because underlying fractures and cavities provide avenues for moisture and solute transport.

  11. The Problem of Occlusal Surface Pit and Fissure Dental Caries in Naval Recruits.

    DTIC Science & Technology

    1980-06-01

    been little attention devoted to oclusal surface pit and fissure dental caries. There is so= evidence that tooth morphology is related to susceptibility...AD-A0CM 755 NAVAL DENTAL RESEARCH INST GREAT LAKES IL F/S 6/5 THE PROBLEM OF OCCLUSAL SURFACE PIT AND FISSURE DENTAL CARIES I--ETC(U) JUN 80 M R...THE PROBLEM OF OCCLUSAL SURFACE PIT AND FISSURE DENTAL CARIES IN NAVAL RECRUITS M. R. WIRTHLIN 1. L. SHKLAIR R. G. WALTER J. C. CECIL 0 M. E. COHEN

  12. Moisture and solute flux along preferred pathways characterized by fissured sediments in desert soils

    NASA Astrophysics Data System (ADS)

    Scanlon, Bridget R.

    1992-06-01

    Evaluation of preferred flow pathways is critical for waste disposal. These pathways reduce the effectiveness of thick desert soils in attenuating contaminants by short-circuiting flow through the unsaturated zone. Unsaturated flow in fissured sediments in the Chihuahuan Desert of Texas, U.S.A., was examined to determine if these sediments act as preferred pathways for water and solute transport. Fissures are surface features, or gulleys, that are underlain by fractures filled with loose sediment washed in from surrounding areas. Hydraulic and chemical approaches were used to investigate unsaturated flow processes beneath and adjacent to fissures, and the results were compared with data from surrounding geomorphic systems such as arroyos, ephemeral streams and interstreams. Typically, high water potentials in surficial sediments result from infiltration of recent precipitation. Below this surficial zone of high water potentials lies a zone of low water potentials that is much thinner beneath the fissure than in adjacent sediments or in sediments beneath ephemeral streams and interstreams. Maximum chloride concentrations in profiles in the fissured sediments (80-105 gm -3) were much lower than those measured in all other geomorphic systems (2000-6000 gm -3) because chloride is leached in the vicinity of the fissures. Minimum estimates of the moisture flux from chloride data ranged from 1 to 8 mm yr -1 in the fissured sediments and were up to 350 times greater than those calculated for ephemeral stream and interstream settings. The corresponding moisture velocities in the fissured sediments ranged from 10 to 70 mm yr -1. A tracer experiment demonstrated higher downward water and solute transport in the fracture fill beneath the fissure relative to adjacent sediments. Numerical simulations of the tracer experiment with the computer code TRACR3D reproduced the overall shape of the tracer plume. Sensitivity analyses demonstrated that the tracer plume is most sensitive

  13. [Fissure sealants as primary preventive measures. Four-year evaluation in Stara Pazova].

    PubMed

    Andjelic, P; Pazova, S; Vojinovic, J; Tatic, E; Pintaric, J

    1991-04-01

    Worldwide studies have shown that fissure caries prophylaxis is very difficult using conventional preventive methods. The scientific council of the prophylaxis programme for the protection of mouth and teeth in Vojvodina has begun sealing fissures in Stara Pazova and Novi Sad. The molars of all 6-year-old children were sealed completely. A 77.8% reduction in fissure caries was found at the end of the four-year study. Losses of sealing material came to 16% after four years. Cost-effectiveness analysis: The sealings are three times cheaper than an amalgam filling. Application time: 8-9 minutes.

  14. Cassini VIMS Spectra of the Thermal Emission from Hot Spots Along Enceladus South Pole Fissures

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Buratti, Bonnie J.; Cassini VIMS Team

    2016-10-01

    Most of the south pole fissure region has not been directly illuminated by sunlight since the sub-solar point moved into the northern hemisphere in 2009, thereby eliminating the background of reflected sunlight at VIMS wavelengths and making the fissure thermal emission readily measureable. Since then, VIMS has measured spectra of at least 11 hot spots along the fissures. Most of these measurements were acquired in ride-along mode with CIRS as the prime instrument. During at least 2 encounters, VIMS and CIRS acquired simultaneous or near-simultaneous spectra of the same fissure location. VIMS spectra include multiple hot spots along Damascus, Baghdad, Cairo, and a likely hot spot on Alexandria.All of the VIMS spectra examined to date are consistent with this scenario of a self-regulating fissure maximum T~200 K with brighter VIMS emissions corresponding to fissures up to ~20 m wide. Emission from the warm fissure interior walls dominate the VIMS spectra with <15% contributed by conductive heating of the adjacent terrain at VIMS wavelengths.CIRS spectra report slightly cooler T's due to CIRS increased sensitivity to lower T emission at longer wavelengths and averaging over contributions from both the hottest and cooler areas. Combined analysis of the CIRS and VIMS spectra spanning 3 to 500 micron wavelengths promises to reveal the distribution of [T, area] near the fissures that cannot be spatially resolved. This [T, area] distribution holds the key to understanding how heat is transferred to the surface within a few 100 m of the fissures.The VIMS-detected emission is concentrated in localized hot spots along the fissures and does not seem to be distributed continuously along them. CIRS spectra suggest a more continuous distribution of the emission along the fissure length. Jets locations also are distributed along the fissure length and it appears that the VIMS-detected hot spots in general correlate with jet locations, but not all of the jet locations have been

  15. Mechanical benefits of conservative restoration for dental fissure caries.

    PubMed

    Zhang, Zhongpu; Zheng, Keke; Li, Eric; Li, Wei; Li, Qing; Swain, Michael V

    2016-01-01

    The principle of minimal intervention dentistry (MID) is to limit removal of carious tooth tissue while maximizing its repair and survival potential. The objective of this study is to explore the fracture resistance of a permanent molar tooth with a fissure carious lesion along with three clinical restoration procedures, namely one traditional and two conservative approaches, based upon MID. The traditional restoration employs extensive surgical removal of enamel and dentine about the cavity to eliminate potential risk of further caries development, while conservative method #1 removes significantly less enamel and infected dentine, and conservative method #2 only restores the overhanging enamel above the cavity and leaves the infected and affected dentine as it was. An extended finite element method (XFEM) is adopted here to analyze the fracture behaviors of both two-dimensional (2D) and three-dimensional (3D) modeling of these four different scenarios. It was found that the two conservative methods exhibited better fracture resistance than the traditional restorative method. Although conservative method #2 has less fracture resistance than method #1, it had significantly superior fracture resistance compared to other restorations. More important, after cavity sealing it may potentially enhance the opportunity for remineralization and improved loading bearing capacity and fracture resistance.

  16. Painless Ulcers and Fissures of Toes: Hereditary Sensory Neuropathy, Not Leprosy.

    PubMed

    Rao, Angoori Gnaneshwar

    2016-01-01

    Hereditary sensory neuropathies (HSN) are rare genetically determined neuropathies. They often manifest as painless injuries in children. We present HSN in a 5-year-old boy who presented with recurrent fissuring and ulceration involving both great toes.

  17. Painless Ulcers and Fissures of Toes: Hereditary Sensory Neuropathy, Not Leprosy

    PubMed Central

    Rao, Angoori Gnaneshwar

    2016-01-01

    Hereditary sensory neuropathies (HSN) are rare genetically determined neuropathies. They often manifest as painless injuries in children. We present HSN in a 5-year-old boy who presented with recurrent fissuring and ulceration involving both great toes. PMID:26955138

  18. Putative fissure-resistance QTLs mapped to chromosomes 1 and 8 based on allelic frequency differences observed between fissure-resistant and fissure-susceptible progeny from two segregating populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole rice kernels have two to three times more market value than broken, which means that any reduction in milling yield results in financial losses for both rice producers and millers. One of the primary causes of rice breakage during milling is fissuring of the rice before it even enters the mil...

  19. Orientation of the eruption fissures controlled by a shallow magma chamber in Miyakejima

    NASA Astrophysics Data System (ADS)

    Geshi, Nobuo; Oikawa, Teruki

    2016-11-01

    Orientation of the eruption fissures and composition of the lavas of the Miyakejima volcano indicate tectonic influence of a shallow magma chamber on the distribution of eruption fissures. We examined the distributions and magmatic compositions of 23 fissures that formed within the last 2800 years, based on a field survey and a new dataset of 14C ages. The dominant orientation of the eruption fissures in the central portion of the volcano was found to be NE-SW, which is perpendicular to the direction of regional maximum horizontal compressive stress (σHmax). Magmas that show evidences of magma mixing between basaltic and andesitic magmas erupted mainly from the eruption fissures with a higher offset angle from the regional σHmax direction. The presence of a shallow dike-shaped magma chamber controls the distribution of the eruption fissures. The injection of basaltic magma into the shallow andesitic magma chamber caused the temporal rise of internal magmatic pressure in the shallow magma chamber. Dikes extending from the andesitic magma chamber intrude along the local compressive stress field which is generated by the internal excess pressure of the andesitic magma chamber. As the result, the eruption fissures trend parallel to the elongation direction of the shallow magma chamber. Injection of basaltic magma into the shallow andesitic magma chamber caused the magma mixing. Some basaltic dikes from the deep-seated magma chamber reach the ground surface without intersection with the andesitic magma chamber. The patterns of the eruption fissures can be modified in the future as was observed in the case of the destruction of the shallow magma chamber during the 2000 AD eruption.

  20. A study on using texture analysis methods for identifying lobar fissure regions in isotropic CT images.

    PubMed

    Wei, Q; Hu, Y

    2009-01-01

    The major hurdle for segmenting lung lobes in computed tomographic (CT) images is to identify fissure regions, which encase lobar fissures. Accurate identification of these regions is difficult due to the variable shape and appearance of the fissures, along with the low contrast and high noise associated with CT images. This paper studies the effectiveness of two texture analysis methods - the gray level co-occurrence matrix (GLCM) and the gray level run length matrix (GLRLM) - in identifying fissure regions from isotropic CT image stacks. To classify GLCM and GLRLM texture features, we applied a feed-forward back-propagation neural network and achieved the best classification accuracy utilizing 16 quantized levels for computing the GLCM and GLRLM texture features and 64 neurons in the input/hidden layers of the neural network. Tested on isotropic CT image stacks of 24 patients with the pathologic lungs, we obtained accuracies of 86% and 87% for identifying fissure regions using the GLCM and GLRLM methods, respectively. These accuracies compare favorably with surgeons/radiologists' accuracy of 80% for identifying fissure regions in clinical settings. This shows promising potential for segmenting lung lobes using the GLCM and GLRLM methods.

  1. Monitoring on Xi'an ground fissures deformation with TerraSAR-X data

    USGS Publications Warehouse

    Zhao, C.; Zhang, Q.; Zhu, W.; Lu, Zhiming

    2012-01-01

    Owing to the fine resolution of TerraSAR-X data provided since 2007, this paper applied 6 TerraSAR data (strip mode) during 3rd Dec. 2009 to 23rd Mar. 2010 to detect and monitor the active fissures over Xi'an region. Three themes have been designed for high precision detection and monitoring of Xi'an-Chang'an fissures, as small baseline subsets (SBAS) to test the atmospheric effects of differential interferograms pair stepwise, 2-pass differential interferogram with very short baseline perpendicular to generate the whole deformation map with 44 days interval, and finally, corner reflector (CR) technique was used to closely monitor the relative deformation time series between two CRs settled crossing two ground fissures. Results showed that TerraSAR data are a good choice for small-scale ground fissures detection and monitoring, while special considerations should be taken for their great temporal and baseline decorrelation. Secondly, ground fissures in Xi'an were mostly detected at the joint section of stable and deformable regions. Lastly, CR-InSAR had potential ability to monitor relative deformation crossing fissures with millimeter precision.

  2. Multiscale Strain as a Predictor of Impact-Induced Fissuring in Articular Cartilage.

    PubMed

    Henak, Corinne R; Bartell, Lena R; Cohen, Itai; Bonassar, Lawrence J

    2017-03-01

    Mechanical damage is central to both initiation and progression of osteoarthritis (OA). However, specific causal links between mechanics and cartilage damage are incompletely understood, which results in an inability to predict failure. The lack of understanding is primarily due to the difficulty in simultaneously resolving the high rates and small length scales relevant to the problem and in correlating such measurements to the resulting fissures. This study leveraged microscopy and high-speed imaging to resolve mechanics on the previously unexamined time and length scales of interest in cartilage damage, and used those mechanics to develop predictive models. The specific objectives of this study were to: first, quantify bulk and local mechanics during impact-induced fissuring; second, develop predictive models of fissuring based on bulk mechanics and local strain; and third, evaluate the accuracy of these models in predicting fissures. To achieve these three objectives, bovine tibial cartilage was impacted using a custom spring-loaded device mounted on an inverted microscope. The occurrence of fissures was modulated by varying impact energy. For the first objective, during impact, deformation was captured at 10,000 frames per second and bulk and local mechanics were analyzed. For the second objective, data from samples impacted with a 1.2 mm diameter rod were fit to logistic regression functions, creating models of fissure probability based on bulk and local mechanics. Finally, for the third objective, data from samples impacted with a 0.8 mm diameter rod were used to test the accuracy of model predictions. This study provides a direct comparison between bulk and local mechanical thresholds for the prediction of fissures in cartilage samples, and demonstrates that local mechanics provide more accurate predictions of local failure than bulk mechanics provide. Bulk mechanics were accurate predictors of fissure for the entire sample cohort, but poor predictors

  3. Health-related quality of life in patients with anal fissure: effect of type D personality

    PubMed Central

    Yilmaz, Edip Erdal; Canan, Fatih; Yildirim, Osman; Cetin, Mehmet Mustafa

    2014-01-01

    Introduction Health-related quality of life (HRQL) is a significant factor in describing the burden of illness and the impact of treatment in patients with gastrointestinal disease. Type D (distressed) personality is defined as the co-occurrence of negative affect and social inhibition. Aim To assess the prevalence of type D personality in patients with anal fissure and to investigate whether the presence of a type D personality would affect HRQL in patients with anal fissure. Material and methods One hundred outpatients with anal fissure with no psychiatric comorbidity were consecutively enrolled, along with 100 healthy controls. Type D Scale (DS14) and General Health Survey Short Form-36 (SF-36) were used in the collection of data. Results Patients with anal fissure scored lower on physical roles and bodily pain dimensions of SF-36 than healthy subjects (p < 0.05). Thirty-three patients with anal fissure (33%) and 16 controls (16%) had scored above the cut-off score of the DS14 (p < 0.05). Patients with a type D personality were found to score lower on bodily pain and social roles domains of HRQL than patients without a type D personality. Conclusions Type D personality was associated with increased perceived bodily pain and social roles in patients with anal fissure. Type D personality construct may be an important consideration when assessing HRQL outcomes. A multidimensional approach may be valuable in the assessment of patients presenting with anal fissure, because a subgroup with type-D personality might benefit from psychological therapies. PMID:25061489

  4. Retention of resin-based filled and unfilled pit and fissure sealants: A comparative clinical study

    PubMed Central

    Reddy, V. Rajashekar; Chowdhary, Nagalakshmi; Mukunda, K. S.; Kiran, N. K.; Kavyarani, B. S.; Pradeep, M. C.

    2015-01-01

    Background and Objectives: The most caries-susceptible period of a permanent first molar tooth is the eruption phase, during which the enamel is not fully matured and it is usually difficult for the child to clean the erupting tooth surfaces. Sealing occlusal pits and fissures with resin-based pit and fissure sealants is a proven method to prevent occlusal caries. The difference in the viscosity of the sealants differs in the penetration into pit and fissures and abrasive wear resistance property due to the addition of filler particles. The present study was conducted to evaluate and compare the retention of the resin-based filled (Helioseal F, Ivoclar Vivadent) and unfilled (Clinpro, 3M ESPE) pit and fissure sealants, which is important for their effectiveness. Materials and Methods: Fifty-six children between the age group of 6 and 9 years, with all four newly erupted permanent first molars were selected. Sealants were applied randomly using split mouth design technique on permanent first molars. Evaluation of sealant retention was performed at regular intervals over 12 months, using Simonsen's criteria at 2nd, 4th, 6th, 8th, 10th and 12th month. The results were subjected to statistical analysis. Results: At the end of our study period (12th month), 53.57% showed complete retention, 37.50% showed partial retention, and 8.83% showed complete missing of resin-based filled (Helioseal F) pit and fissure sealant. And, 64.29% showed complete retention, 32.14% showed partial retention, and 3.57% showed complete missing of resin-based unfilled (Clinpro) pit and fissure sealant. This difference in retention rates between filled and unfilled pit and fissure sealants was not statistically significant. Conclusion: The difference in retention rates between Helioseal F and Clinpro was not statistically significant, but Clinpro (unfilled) sealant showed slightly higher retention rates and clinically better performance than Helioseal F (filled). PMID:25821368

  5. Comparison of Various Concentrations of Tricalcium Phosphate Nanoparticles on Mechanical Properties and Remineralization of Fissure Sealants

    PubMed Central

    Tavassoli-Hojjati, Sara; Atai, Mohammad; Haghgoo, Roza; Rahimian-Imam, Sara; Kameli, Somayeh; Ahmaian-Babaki, Fatemeh; Hamzeh, Faezeh; Ahmadyar, Maryam

    2014-01-01

    Objective: The aim of this study was to investigate the mechanical properties (flexural strength, micro-shear bond strength) and remineralizing potential of fissure sealants by adding various concentrations of β-tricalcium phosphate nanoparticles. Materials and Methods: This in-vitro study consisted of five experimental groups containing prepared nano-fisssure sealants (1–5 wt.% β-TCP nanoparticles) and two control groups containing a prepared and a commercial fissure sealant. Flexural/micro-shear bond strength values were measured using Zwick test machine. Cavities on sixty healthy premolar teeth were filled with the fissure sealants containing 0–5 wt.% of nano β-TCP. The samples were assessed for remineralization under scanning electron microscopy (SEM) and EDAX. Kolmogorov-Smirnov test, One-way ANOVA and Tukey’s Post Hoc analysis/HSD were used to analyze the data. Results: There was no significant difference between the flexural strengths/elastic modulus of the 0–5 wt.% nano β-TCP groups (p>0.05). The average flexural strength/elastic modulus of the prepared fissure sealant group (0%) was significantly higher than the commercial fissure sealant group (Clinpro) (p<0.05). There was no significant difference between micro-shear bond strengths of the experimental groups (1–5 wt.%), and between the commercial and the prepared (0%) fissure sealant groups (p>0.05). Examining the samples under SEM showed a significant increase in thickness of the intermediate layer with increasing concentrations of β-TCP nanoparticles (p<0.05). Conclusion: Addition of 1–5 wt.% β-TCP nanoparticles to the fissure sealants significantly increased the remineralization potential without affecting the mechanical properties. PMID:25584048

  6. Geometry of the September 1971 eruptive fissure at Kilauea volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Dvorak, John J.

    1990-09-01

    A three-dimensional model has been used to estimate the location and dimensions of the eruptive fissure for the 24 29 September 1971 eruption along the southwest rift zone of Kilauea volcano, Hawaii. The model is an inclined rectangular sheet embedded in an elastic half-space with constant displacement on the plane of the sheet. The set of “best” model parameters suggests that the sheet is vertical, extends from a depth of about 2 km to the surface, and has a length of about 14 km. Because this sheet intersects the surface where eruptive vents and extensive ground cracking formed during the eruption, this sheet probably represents the conduit for erupted lava. The amount of displacement perpendicular to the sheet is about 1.9 m, in the middle range of values measured for the amount of opening across the September 1971 eruptive fissure. The thickness of the eruptive fissure associated with the January 1983 east rift zone eruption was determined in an earlier paper to be 3.6 m, about twice the thickness determined here for the September 1971 eruption. Because the lengths (12 km for 1983 and 14 km for 1971) and heights (about 2 km) of the sheet models derived for the January 1983 and September 1971 rift zone eruptions are nearly identical, the greater thickness for the January 1983 eruptive fissure implies that the magma pressure was about a factor of two greater to form the January 1983 eruptive fissure. Because the September 1971 and January 1983 eruptive fissures extent to depths of only a few kilometers, the region of greatest compressive stress produced along the volcano's flank by either of these eruptive fissures would also be within a few kilometers of the surface. Previous work has shown that rift eruptions and intrusions contribute to the buildup of compressive stress along Kilauea's south flank and that this buildup is released by increased seismicity along the south flank. Because south flank earthquakes occur at significantly greater depths, i

  7. Geometry of the September 1971 eruptive fissure at Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Dvorak, J.J.

    1990-01-01

    A three-dimensional model has been used to estimate the location and dimensions of the eruptive fissure for the 24-29 September 1971 eruption along the southwest rift zone of Kilauea volcano, Hawaii. The model is an inclined rectangular sheet embedded in an elastic half-space with constant displacement on the plane of the sheet. The set of "best" model parameters suggests that the sheet is vertical, extends from a depth of about 2 km to the surface, and has a length of about 14 km. Because this sheet intersects the surface where eruptive vents and extensive ground cracking formed during the eruption, this sheet probably represents the conduit for erupted lava. The amount of displacement perpendicular to the sheet is about 1.9 m, in the middle range of values measured for the amount of opening across the September 1971 eruptive fissure. The thickness of the eruptive fissure associated with the January 1983 east rift zone eruption was determined in an earlier paper to be 3.6 m, about twice the thickness determined here for the September 1971 eruption. Because the lengths (12 km for 1983 and 14 km for 1971) and heights (about 2 km) of the sheet models derived for the January 1983 and September 1971 rift zone eruptions are nearly identical, the greater thickness for the January 1983 eruptive fissure implies that the magma pressure was about a factor of two greater to form the January 1983 eruptive fissure. Because the September 1971 and January 1983 eruptive fissures extent to depths of only a few kilometers, the region of greatest compressive stress produced along the volcano's flank by either of these eruptive fissures would also be within a few kilometers of the surface. Previous work has shown that rift eruptions and intrusions contribute to the buildup of compressive stress along Kilauea's south flank and that this buildup is released by increased seismicity along the south flank. Because south flank earthquakes occur at significantly greater depths, i.e., from 5

  8. Quality of life in patients with chronic anal fissure after topical treatment with diltiazem

    PubMed Central

    Tsunoda, Akira; Kashiwagura, Yasuharu; Hirose, Ken-ichi; Sasaki, Tadanori; Kano, Nobuyasu

    2012-01-01

    AIM: To assess the physical and mental health of fissure patients before and after topical treatment with diltiazem. METHODS: Consecutive patients were enrolled prospectively into the study. Quality of life was measured with the short-forum 36 health survey (SF-36) before and after 6-wk treatment with diltiazem. Patients scored symptoms of pain, bleeding, and irritation using numeral rating scales at the initial and follow-up visits. Fissure healing was assessed and side effects were noted. RESULTS: Fissures healed in 21 of 30 (70%) patients. There were significant reductions in the scores of pain, bleeding, and irritation after 1 wk of treatment, respectively. Four patients experienced perianal itching and one patient reported headache. When measured at baseline, pain and irritation showed a negative impact on two of the eight subscales on the SF-36, respectively (bodily pain and social functioning for pain; vitality and mental health for irritation). Repeating the SF-36 showed an improvement in bodily pain (P = 0.001). Patients whose fissures healed reported an improvement in bodily pain, health-perception, vitality, and mental health (P < 0.05). CONCLUSION: Successful treatment of chronic anal fissure with topical diltiazem leads to improvement in health-related quality of life. PMID:23494072

  9. In vitro evaluation of shear bond strength and microleakage of different pit and fissure sealants

    PubMed Central

    Babaji, Prashant; Vaid, Shivali; Deep, S.; Mishra, Samvit; Srivastava, Madhulika; Manjooran, Thomas

    2016-01-01

    Aim and Objectives: Fissure caries is most common in children due to deep pit and fissures. Pit and fissure areas on the occlusal surface of the teeth make them susceptible to dental caries, which need to be prevented or restored. Fissures sealant reduces the risk of occlusal caries. The present study was done to evaluate microleakage and shear bond strength of various fissure sealants. Materials and Methods: Thirty-six extracted molars were randomly allocated equally (n = 12) into three groups with three different sealants to evaluate shear bond strength and microleakage at sealant space. The shear bond strengths was evaluated with one-way analysis of variance and microleakage by Kruskal-Wallis nonparametric test using the Statistical Package for the Social Sciences version 18.0 (Chicago: SPSS Inc, 2009). Results: Tetric flow (16.8 MPa) recorded the highest shear bond strength and the difference was statistically significant with enamel loc (12.8 MPa). There was no statistically significant difference in relation to microleakage (P > 0.05) in the tested groups. Conclusions: Tetric flow recorded the highest shear bond strength and the difference was statistically significant with enamel loc. However, there was no statistically significant difference among the groups regarding microleakage. PMID:27652241

  10. Comparison of Topical Nifedipine With Oral Nifedipine for Treatment of Anal Fissure: A Randomized Controlled Trial

    PubMed Central

    Golfam, Farzaneh; Golfam, Parisa; Golfam, Babak; Pahlevani, Puyan

    2014-01-01

    Background: Medical sphincterotomy has gained popularity as a treatment for anal fissure. Calcium channel blockers in topical forms could also be appropriate with low adverse effects. Objectives: This was a prospective randomized controlled trial to compare topical and oral nifedipine in the treatment of chronic anal fissure. Patients and Methods: A prospective randomized controlled trial was conducted at two centers of Shahed University. One hundred and thirty patients with chronic anal fissure aged 18 to 60 years managed in our clinics were included in this study. The patients were randomly divided into two groups. Sixty-five patients received topical nifedipine (TN) and the same number received oral nifedipine (ON). Results: Ulcer healing occurred in 43 (73.33%) of topical nifedipine group compared to 29 (49.5%) patients in oral nifedipine, which was significantly different (P < 0.05). Side effects such as headache and flushing in oral nifedipine group were more prevalent than topical nifedipine, which was statistically different. Recurrence rates were the same after six months of follow-up. Conclusions: Although oral nifedipine can reduce symptom and signs of anal fissure, topical nifedipine has a superior role for anal fissure treatment with higher healing rate and lower side effects. PMID:25389477

  11. Sox4 regulates choroid fissure closure by limiting Hedgehog signaling during ocular morphogenesis

    PubMed Central

    Wen, Wen; Pillai-Kastoori, Lakshmi; Wilson, Stephen G.; Morris, Ann C.

    2015-01-01

    SoxC transcription factors play critical roles in many developmental processes, including neurogenesis, cardiac formation, and skeletal differentiation. In vitro and in vivo loss-of-function studies have suggested that SoxC genes are required for oculogenesis, however the mechanism was poorly understood. Here, we have explored the function of the SoxC factor Sox4 during zebrafish eye development. We show that sox4a and sox4b are expressed in the forebrain and periocular mesenchyme adjacent to the optic stalk during early eye development. Knockdown of sox4 in zebrafish resulted in coloboma, a structural malformation of the eye that is a significant cause of pediatric visual impairment in humans, in which the choroid fissure fails to close. Sox4 morphants displayed altered proximo-distal patterning of the optic vesicle, including expanded pax2 expression in the optic stalk, as well as ectopic cell proliferation in the retina. We show that the abnormal ocular morphogenesis observed in Sox4-deficient zebrafish is caused by elevated Hedgehog (Hh) signaling, and this is due to increased expression of the Hh pathway ligand Indian hedgehog b (ihhb). Consistent with these results, coloboma in sox4 morphants could be rescued by pharmacological treatment with the Hh inhibitor cyclopamine, or by co-knockdown of ihhb. Conversely, overexpression of sox4 reduced Hh signaling and ihhb expression, resulting in cyclopia. Finally, we demonstrate that sox4 and sox11 have overlapping, but not completely redundant, functions in regulating ocular morphogenesis. Taken together, our data demonstrate that Sox4 is required to limit the extent of Hh signaling during eye development, and suggest that mutations in SoxC factors could contribute to the development of coloboma. PMID:25557621

  12. A robotic approach to mapping post-eruptive volcanic fissure conduits

    NASA Astrophysics Data System (ADS)

    Parcheta, Carolyn E.; Pavlov, Catherine A.; Wiltsie, Nicholas; Carpenter, Kalind C.; Nash, Jeremy; Parness, Aaron; Mitchell, Karl L.

    2016-06-01

    VolcanoBot was developed to map volcanic vents and their underlying conduit systems, which are rarely preserved and generally inaccessible to human exploration. It uses a PrimeSense Carmine 1.09 sensor for mapping and carries an IR temperature sensor, analog distance sensor, and an inertial measurement unit (IMU) inside a protective shell. The first field test succeeded in collecting valuable scientific data but revealed several needed improvements, including more rugged cable connections and mechanical couplers, increased ground clearance, and higher-torque motors for uphill mobility. The second field test significantly improved on all of these aspects but it traded electrical ruggedness for reduced data collection speed. Data collected by the VolcanoBots, while intermittent, yield the first insights into the cm-scale geometry of volcanic fissures at depths of up to 25 m. VolcanoBot was deployed at the 1969 Mauna Ulu fissure system on Kīlauea volcano in Hawai'i. It collected first-of-its-kind data from inside the fissure system. We hypothesized that 1) fissure sinuosity should decrease with depth, 2) irregularity should be persistent with depth, 3) any blockages in the conduit should occur at the narrowest points, and 4) the fissure should narrow with depth until it is too narrow for VolcanoBot to pass or is plugged with solidified lava. Our field campaigns did not span enough lateral or vertical area to test sinuosity. The preliminary data indicate that 1) there were many irregularities along fissures at depth, 2) blockages occurred, but not at obviously narrow locations, and 3) the conduit width remained a consistent 0.4-0.5 m for most of the upper 10 m that we analyzed.

  13. Conversion degree, microhardness, microleakage and fluoride release of different fissure sealants.

    PubMed

    Kuşgöz, Adem; Tüzüner, Tamer; Ulker, Mustafa; Kemer, Bariş; Saray, Onur

    2010-11-01

    The purpose of this study was to determine the degree of conversion (DC), microhardness, microleakage and fluoride release of a nano-filled resin based fissure sealant (Grandio Seal, GS) and compare it with an un-filled resin based fissure sealant (Clinpro, CL) and a glass-ionomer based fissure sealant (Fuji Triage, FT). Disk shaped specimens were prepared from tested fissure sealants to determine the DC, Vicker hardness (VHN) and fluoride release (FR). The DC and VHN of each material was evaluated after 24 h. The cumulative fluoride concentrations were evaluated at 1 h, 6 h, 12 h, 1, 7, 15 and 30 days. For microleakage evaluation, fissure sealants were applied to the etched and dried enamel surfaces of sound third molar teeth according to the manufacturer's instructions (n=10). After the thermocycling and mechanical loading procedures, microleakage assessments were carried out. Data were analyzed using one-way ANOVA followed by a post hoc Tukey test, the Kruskal Wallis and Mann-Whitney U test (p<0.05). Results revealed differences regarding DC between all groups: FT (89%) > GS (55.02%) > CL (%51.10) (p<0.05). The VHN values were significantly different among all groups in the following order: GS > FT > CL (p<0.05). FT exhibited significantly higher microleakage scores compared to the CL and GS sealants (p<0.05). The FR of FT was significantly greater than CL and GS (p<0.05). Nano-filled resin based sealant can be used as an alternative to other fissure sealant materials because of its superior hardness results and feasible sealing ability.

  14. Cyp1b1 Regulates Ocular Fissure Closure Through a Retinoic Acid–Independent Pathway

    PubMed Central

    Williams, Antionette L.; Eason, Jessica; Chawla, Bahaar; Bohnsack, Brenda L.

    2017-01-01

    Purpose Mutations in the CYP1B1 gene are the most commonly identified genetic causes of primary infantile-onset glaucoma. Despite this disease association, the role of CYP1B1 in eye development and its in vivo substrate remain unknown. In the present study, we used zebrafish to elucidate the mechanism by which cyp1b1 regulates eye development. Methods Zebrafish eye and neural crest development were analyzed using live imaging of transgenic zebrafish embryos, in situ hybridization, immunostaining, TUNEL assay, and methylacrylate sections. Cyp1b1 and retinoic acid (RA) levels were genetically (morpholino oligonucleotide antisense and mRNA) and pharmacologically manipulated to examine gene function. Results Using zebrafish, we observed that cyp1b1 was expressed in a specific spatiotemporal pattern in the ocular fissures of the developing zebrafish retina and regulated fissure patency. Decreased Cyp1b1 resulted in the premature breakdown of laminin in the ventral fissure and altered subsequent neural crest migration into the anterior segment. In contrast, cyp1b1 overexpression inhibited cell survival in the ventral ocular fissure and prevented fissure closure via an RA-independent pathway. Cyp1b1 overexpression also inhibited the ocular expression of vsx2, pax6a, and pax6b and increased the extraocular expression of shha. Importantly, embryos injected with human wild-type but not mutant CYP1B1 mRNA also showed colobomas, demonstrating the evolutionary and functional conservation of gene function between species. Conclusions Cyp1b1 regulation of ocular fissure closure indirectly affects neural crest migration and development through an RA-independent pathway. These studies provide insight into the role of Cyp1b1 in eye development and further elucidate the pathogenesis of primary infantile-onset glaucoma. PMID:28192799

  15. The effect of CT technical factors on quantification of lung fissure integrity

    NASA Astrophysics Data System (ADS)

    Chong, D.; Brown, M. S.; Ochs, R.; Abtin, F.; Brown, M.; Ordookhani, A.; Shaw, G.; Kim, H. J.; Gjertson, D.; Goldin, J. G.

    2009-02-01

    A new emphysema treatment uses endobronchial valves to perform lobar volume reduction. The degree of fissure completeness may predict treatment efficacy. This study investigated the behavior of a semiautomated algorithm for quantifying lung fissure integrity in CT with respect to reconstruction kernel and dose. Raw CT data was obtained for six asymptomatic patients from a high-risk population for lung cancer. The patients were scanned on either a Siemens Sensation 16 or 64, using a low-dose protocol of 120 kVp, 25 mAs. Images were reconstructed using kernels ranging from smooth to sharp (B10f, B30f, B50f, B70f). Research software was used to simulate an even lower-dose acquisition of 15 mAs, and images were generated at the same kernels resulting in 8 series per patient. The left major fissure was manually contoured axially at regular intervals, yielding 37 contours across all patients. These contours were read into an image analysis and pattern classification system which computed a Fissure Integrity Score (FIS) for each kernel and dose. FIS values were analyzed using a mixed-effects model with kernel and dose as fixed effects and patient as random effect to test for difference due to kernel and dose. Analysis revealed no difference in FIS between the smooth kernels (B10f, B30f) nor between sharp kernels (B50f, B70f), but there was a significant difference between the sharp and smooth groups (p = 0.020). There was no significant difference in FIS between the two low-dose reconstructions (p = 0.882). Using a cutoff of 90%, the number of incomplete fissures increased from 5 to 10 when the imaging protocol changed from B50f to B30f. Reconstruction kernel has a significant effect on quantification of fissure integrity in CT. This has potential implications when selecting patients for endobronchial valve therapy.

  16. Three-armed rifts or masked radial pattern of eruptive fissures? The intriguing case of El Hierro volcano (Canary Islands)

    NASA Astrophysics Data System (ADS)

    Becerril, L.; Galindo, I.; Martí, J.; Gudmundsson, A.

    2015-04-01

    Using new surface structural data as well as subsurface structural data obtained from seventeen water galleries, we provide a comprehensive model of the volcano-tectonic evolution of El Hierro (Canary Islands). We have identified, measured and analysed more than 1700 volcano-structural elements including vents, eruptive fissures, dykes and faults. The new data provide important information on the main structural patterns of the island and on its stress and strain fields, all of which are crucial for reliable hazard assessments. We conducted temporal and spatial analyses of the main structural elements, focusing on their relative age and association with the three main cycles in the construction of the island: the Tiñor Edifice, the El Golfo-Las Playas Edifice, and the Rift Volcanism. A radial strike distribution, which can be related to constructive episodes, is observed in the on-land structures. A similar strike distribution is seen in the submarine eruptive fissures, which are radial with respect to the centre of the island. However, the volcano-structural elements identified onshore and reflecting the entire volcano-tectonic evolution of the island also show a predominant NE-SW strike, which coincides with the main regional trend of the Canary archipelago as a whole. Two other dominant directions of structural elements, N-S and WNW-ESE, are evident from the establishment of the El Golfo-Las Playas edifice, during the second constructive cycle. We suggest that the radial-striking structures reflect comparatively uniform stress fields during the constructive episodes, mainly conditioned by the combination of overburden pressure, gravitational spreading, and magma-induced stresses in each of the volcanic edifices. By contrast, in the shallower parts of the edifice the NE-SW, N-S and WNW-ESE-striking structures reflect local stress fields related to the formation of mega-landslides and masking the general and regional radial patterns.

  17. Breeding for rice fissure resistance made possible through development of a new selection technique and identification of molecular gene tags

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Value: One of the primary causes of rice grain breakage during milling is fissuring, or cracking, of the rice before it enters the mill. Any reduction in kernel fissuring can result in direct increases in profit for both producers and millers. For a producer yielding 7,000 lb/A paddy, even a small (...

  18. Giant desiccation fissures on the Black Rock and Smoke Creek Deserts, Nevada

    USGS Publications Warehouse

    Willden, R.; Mabey, D.R.

    1961-01-01

    Open fissures, from 100 to several hundred feet apart, that have produced polygonal patterns on the Black Rock Desert, Nevada, are believed to be giant desiccation cracks resulting from a secular trend toward aridity in the last few decades. Similar features on the Smoke Creek Desert probably have the same origin.

  19. Impact of extended radiant exposure time on polymerization depth of fluoride-containing fissure sealer materials.

    PubMed

    Borges, Boniek C D; Souza-Junior, Eduardo J; Catelan, Anderson; Ambrosano, Gláucia M B; Paulillo, Luís A M S; Aguiar, Flávio H B

    2011-01-01

    Physical properties such as surface hardness of dental materials are directly linked to their clinical behavior. The aim of this study was to investigate the influence of extended curing time on the polymerization depth offluoride-containing materials used as pit and fissure sealants. Conventional and extended exposure times (20 and 60 seconds) were used to photoactivate a gold-standard pit and fissure sealant (Fluroshield, Dentsply) and a flowable composite (PermaFlo, Ultradent). Twenty square-shaped samples (n=5) were prepared using a LED device (Bluephase 16i, Ivoclar). The Knoop Hardness Number (KHN) was calculated for the top and bottom surface of each sample 24 hours after polymerization. Bottom/top hardness ratio (B/T KHN) was than calculated. Averages were analyzed by two-way ANOVA and Tukey test (alpha=0.05). The flowable composite had higher KHN than conventional pit and fissure sealant for all experimental conditions (p<0.05). The 60-second photoactivation time increased KHN at the bottom surface and B/T KHN only of composite specimens. The flowable composite had better physical properties than the pit and fissure sealant, and they were improved by extended curing time.

  20. Mapping the fissure potential zones based on microtremor measurement in Denpasar City, Bali

    NASA Astrophysics Data System (ADS)

    Prabowo, U. N.; Marjiyono; Sismanto

    2016-01-01

    Denpasar City and its vicinity considered as the areas with excessive ground water exploitation and high earthquake intensity. These conditions will cause these area potential with land subsidence which is triggering ground fissures. This research aims are to mapping the fissures potential areas based on microtremor measurement in Denpasar City and its vicinity. Ground fissures will happen if the land subsidence occurs in the areas which have different bedrock height beneath its sedimentary layer. The height of bedrock is determined by reducing surface elevation with the sedimentary layer thickness. This sedimentary layer thickness obtained from microtremor measurement using HVSR method, and Shear wave velocity (VS) obtained from microtremor array measurement which is analyzed by Spatial Auto Correlation (SPAC) method. The result from HVSR method as well as Peak Ground Acceleration (PGA) value are then analyzed to get ground shear strain value, which is the soil surface strain and its effect when earthquake occurs. Based on the bedrock map, it can be estimated that the bedrock layer forms structure in the southern part of the research areas and the potential fissuring area due to the massive ground water exploitation is in the west Denpasar Subdistrict. In addition, based on the bedrock map and ground shear strain value which combined with Simple Additive Weight (SAW) method, there are two areas having Assuring potential, i.e west and south Denpasar Subdistricts.

  1. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... depressions (faults in the enamel) in the biting surfaces of teeth to prevent cavities. (b)...

  2. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... depressions (faults in the enamel) in the biting surfaces of teeth to prevent cavities. (b)...

  3. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... depressions (faults in the enamel) in the biting surfaces of teeth to prevent cavities. (b)...

  4. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... depressions (faults in the enamel) in the biting surfaces of teeth to prevent cavities. (b)...

  5. 21 CFR 872.3765 - Pit and fissure sealant and conditioner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pit and fissure sealant and conditioner. 872.3765 Section 872.3765 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... depressions (faults in the enamel) in the biting surfaces of teeth to prevent cavities. (b)...

  6. Rice fissure resistance QTLs from ‘Saber’ complement those from ‘Cypress’

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The economic value of broken rice is about half that of whole milled rice, so one goal of producers, millers, and rice breeders is to reduce grain breakage during the dehusking and milling processes. One of the primary causes of rice breakage is fissuring, or cracking, of the rice before it enters ...

  7. Identification of genetic loci underlying the kernel fissure-resistance exhibited by 'cypress' and 'saber'

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The economic value of broken rice is about half that of whole milled rice, so one goal of producers, millers, and rice breeders is to reduce broken grains that result from the dehusking and milling processes One of the primary causes of rice breakage is fissuring, or cracking, of the rice before it ...

  8. Methods for monitoring land subsidence and earth fissures in the Western USA

    NASA Astrophysics Data System (ADS)

    Fergason, K. C.; Rucker, M. L.; Panda, B. B.

    2015-11-01

    Depletion of groundwater resources in many deep alluvial basin aquifers in the Western USA is causing land subsidence, as it does in many regions worldwide. Land subsidence can severely and adversely impact infrastructure by changing the ground elevation, ground slope (grade) and through the development of ground cracks known as earth fissures that can erode into large gullies. Earth fissures have the potential to compromise the foundations of dams, levees, and other infrastructure and cause failure. Subsequent to an evaluation of the overall subsidence experienced in the vicinity of subsidence-impacted infrastructure, a detailed investigation to search for earth fissures, and design and/or mitigation of potentially effected infrastructure, a focused monitoring system should be designed and implemented. Its purpose is to provide data, and ultimately knowledge, to reduce the potential adverse impacts of land subsidence and earth fissure development to the pertinent infrastructure. This risk reduction is realized by quantifying the rate and distribution of ground deformation, and to detect ground rupture if it occurs, in the vicinity of the infrastructure. The authors have successfully designed and implemented monitoring systems capable of quantifying rates and distributions of ground subsidence and detection of ground rupture at multiple locations throughout the Western USA for several types of infrastructure including dams, levees, channels, basins, roadways, and mining facilities. Effective subsidence and earth fissure monitoring requires understanding and quantification of historic subsidence, estimation of potential future subsidence, delineation of the risk for earth fissures that could impact infrastructure, and motivation and resources to continue monitoring through time. A successful monitoring system provides the means to measure ground deformation, grade changes, displacement, and anticipate and assess the potential for earth fissuring. Employing multiple

  9. Soil gas composition from the 2001-2002 fissure in the Lakki Plain (Nisyros Island, Greece): evidences for shallow hydrothermal fluid circulation

    NASA Astrophysics Data System (ADS)

    Venturi, Stefania; Tassi, Franco; Kanellopoulos, Christos; Vaselli, Orlando; Caponi, Chiara; Ricci, Andrea; Raspanti, Alessio; Gallorini, Andrea; Cabassi, Jacopo; Vougioukalakis, Georges

    2016-04-01

    Nisyros volcano (Aegean Sea, Greece) is currently classified in the "Very High Threat" category (Kinvig et al., 2010). Although the last volcanic activity, consisting of phreatic eruptions, occurred in the 19th century, Nisyros experienced an intense seismic activity during 1996-1998 accompanied by ground deformation and changes in the chemistry of fumarolic gases (Chiodini et al., 2002), pointing to a renewed unrest. Between November 2001 and December 2002, a NNE-oriented 600 m long fissure opened in the vegetated central part of the Lakki Plain. The fissure, 1-5 m wide and up to 15-20 m deep, showed neither vertical displacements nor gas release. No changes in the seismic and volcanic activity were observed during or after this event, which was interpreted as related to collapse of the upper caldera floor fine sediment cover (<50 m thick) induced by hydrothermal fluid circulation (Vougioukalakis and Fytikas, 2005). In June 2015, diffuse CO2 flux measurements, in combination with sampling and chemical analysis of the interstitial soil gases, were performed in (i) the fissure bottom, (ii) the adjacent vegetated areas in the Lakki Plain, (iii) the near hydrothermal craters (Stefanos, Kaminakia, Lofos domes), and (iv) sites located outside the caldera (blank values). The fissure showed neither temperature (<30 °C) nor CO2 fluxes (<10 gm-2d-1) anomalies with respect to the blank sites and the Lakki Plain, with values strikingly lower than those measured in the hydrothermal craters (up to 98 °C and 208 gm-2d-1, respectively). Contrarily, the CO2 concentrations in the interstitial soil gases from the fissure (up to 513 mmol/mol) were markedly higher than the background values and comparable with those measured in the craters (up to 841 mmol/mol). Relatively high H2S, H2 and CH4 contents in soil gases from the fissure confirm the hydrothermal origin of these soil gases. However, their CH4/CO2 ratio were lower than those measured in the soil gases from the craters

  10. Enamel Surface with Pit and Fissure Sealant Containing 45S5 Bioactive Glass.

    PubMed

    Yang, S-Y; Kwon, J-S; Kim, K-N; Kim, K-M

    2016-05-01

    Enamel demineralization adjacent to pit and fissure sealants leads to the formation of marginal caries, which can necessitate the replacement of existing sealants. Dental materials with bioactive glass, which releases ions that inhibit dental caries, have been studied. The purpose of this study was to evaluate the enamel surface adjacent to sealants containing 45S5 bioactive glass (BAG) under simulated microleakage between the material and the tooth in a cariogenic environment. Sealants containing 45S5BAG filler were prepared as follows: 0% 45S5BAG + 50.0% glass (BAG0 group), 12.5% 45S5BAG + 37.5% glass (BAG12.5 group), 25.0% 45S5BAG + 25.0% glass (BAG25.0 group), 37.5% 45S5BAG + 12.5% glass (BAG37.5 group), and 50.0% 45S5BAG + 0% glass (BAG50.0 group). A cured sealant disk was placed over a flat bovine enamel disk, separated by a 60-µm gap, and immersed in lactic acid solution (pH 4.0) at 37 °C for 15, 30, and 45 d. After the storage period, each enamel disk was separated from the cured sealant disk, and the enamel surface was examined with optical 3-dimensional surface profilometer, microhardness tester, and scanning electron microscopy. The results showed a significant increase in roughness and a decrease in microhardness of the enamel surface as the proportion of 45S5BAG decreased (P< 0.05). In the scanning electron microscopy images, enamel surfaces with BAG50.0 showed a smooth surface, similar to those in the control group with distilled water, even after prolonged acid storage. Additionally, an etched pattern was observed on the surface of the demineralized enamel with a decreasing proportion of 45S5BAG. Increasing the 45S5BAG filler contents of the sealants had a significant impact in preventing the demineralization of the enamel surface within microgaps between the material and the tooth when exposed to a cariogenic environment. Therefore, despite some marginal leakage, these novel sealants may be effective preventive dental materials for inhibiting

  11. The cycle of instability: stress release and fissure flow as controls on gully head retreat

    NASA Astrophysics Data System (ADS)

    Collison, A. J. C.

    2001-01-01

    Gully head and wall retreat has commonly been attributed to fluvial scour and head collapse as a result of soil saturation, sapping or piping. The empirical evidence to substantiate these conceptual models is sparse, however, and often contradictory. This paper explores the hydrological and mechanical controls on gully head and wall stability by modelling the hydrology, stability and elastic deformation of a marl gully complex in Granada Province, south-east Spain. The hydrological and slope-stability simulations show that saturated conditions can be reached only where preferential fissure flow channels water from tension cracks into the base of the gully head, and that vertical or subvertical heads will be stable unless saturation is achieved. Owing to the high unsaturated strengths of marl measured in this research, failure in unsaturated conditions is possible only where the gully head wall is significantly undercut. Head retreat thus requires the formation of either a tension crack or an undercut hollow. Finite-element stress analysis of eroding slopes reveals a build up of shear stress at the gully head base, and a second stress anomaly just upslope of the head wall. Although tension cracks on gully heads have often been attributed to slope unloading, this research provides strong evidence that the so called sapping hollow commonly found in the gully headwall base is also a function of stress release. Although further research is needed, it seems possible that pop out failures in river channels may be caused by the same process. The hydrological analysis shows that, once a tension crack has developed, throughflow velocity in the gully headwall will increase by an order of magnitude, promoting piping and enlargement of this weakened area. It is, therefore, possible to envisage a cycle of gully expansion in which erosion, channel incision or human action unloads the slope below a gully head, leading to stress patterns that account for the tension crack and a

  12. A symptomatic Sylvian fissure lipoma in a post-traumatic patient

    PubMed Central

    Bokhari, Rakan Farouk; Bangash, Mohammad Hasan; Ahamed, Naushad Ali Basheer; Addas, Jameel

    2014-01-01

    Lipomatous extra-axial lesions in the Sylvian fissure are a rare entity. Their identification, however, is usually simple if a systematic radiological approach is adopted. The best line of management for these lesions is still a matter of controversy and fraught with complications. We present a case of a Sylvian fissure lipoma referred to our neurosurgery services with symptomatic seizures and in a post-traumatic patient. The radiological differentiating features of intracranial lipomas and intracranial dermoids have been discussed. The unusual location of the lesion, in combination with the history of seizures and the nature of presentation (trauma being a red-herring) make this case an interesting find. The lesion was managed conservatively with good outcomes at follow up, on anti-epileptic medications. PMID:24967029

  13. Comparative study of glyceryl trinitrate ointment versus surgical management of chronic anal fissure.

    PubMed

    Tauro, Leo Francis; Shindhe, Vittal V; Aithala, P Sathyamoorthy; Martis, John J S; Shenoy, H Divakar

    2011-08-01

    Chronic Anal Fissure (CAF) is common perineal condition and well-known painful entity. Standard surgical treatment even though available, may require long hospital stay and sometimes have worrying complications like anal incontinence. So non-surgical treatment, Glyceryl Trinitrate has been shown to be an effective for chronic anal fissure. It decreases anal tone and ultimately heals the anal fissure. The present study is the attempt to know the efficacy of 0.2% Glyceryl Trinitrate ointment in the treatment of chronic anal fissure and to compare the effectiveness of 0.2% Glyceryl Trinitrate ointment (GTN) versus fissurectomy with lateral internal sphincterotomy (LIS) and fissurectomy with posterior internal sphincterotomy (PIS) in the management of chronic anal fissure. This is a prospective comparative study of management of chronic anal fissure done in our hospital during the period of one and half year from October 2005 to March 2007. Thirty patients treated with 0.2% Glyceryl Trinitrate ointment and 30 patients treated with fissurectomy and lateral internal sphincterotomy and 30 patients treated with posterior internal sphincterotomy, for chronic anal fissure were selected for study. A single brand of 0.2% Glyceryl Trinitrate ointment (Nitrogesic) used for trial arm. Dose of administration was 1.5 cm to 2 cm in the anal canal with device provided by manufacturers of the proprietary preparation and applied twice a daily for 12 weeks. Patients were followed up for 12 weeks and thereafter evaluated for relief of symptoms in all three groups. Observations were recorded at 2 weeks; 6 weeks and 12 weeks of follow up period, regarding symptoms like pain and bleeding during defecation, healing of CAF and also for side effects like headache in GTN group and flatus, fecal incontinence in surgical groups. Data collected in proforma and analyzed. Study revealed CAF was more in male 59 patients (66%) than the female 31 patients (34%), the ratio being 1: 0.52. The

  14. Fissure basalts and ocean-floor spreading on the East pacific rise.

    PubMed

    Bonatti, E

    1968-08-30

    A basalt pavement outcrops almost continuously in a band along the crestal region of the East Pacific Rise from about 14 degrees S to 6 degrees S, that is, for more than 800 ikilometers; the outcrop may well extend beyond the above limits along the axis of the rise. The basalt band is generally between 40 and 60 kilometers wide and is replaced laterally by sediment. The lavas are fresh, "oceanic tholeiites" which were emplaced less than I million years ago by fissure eruptions. These findings, can be explained by the hypothesis of ocean-floor spreading; the basalts are the expression of material originating from the mantle and rising through fissures along the axis of the ridge. The absence of an axial rift valley on the East Pacific Rise may be explained by the fact that large volumes of lava are being outpoured along its crest.

  15. The influence of geometry on the ascent of magma in open fissures

    NASA Astrophysics Data System (ADS)

    Giberti, G.; Wilson, L.

    1990-09-01

    During steady eruption, the flow conditions (emitted mass flux, exit velocity and exit pressure) depend on the geometry of the conduit in which the eruption occurs. This dependence is examined for the onedimensional, isothermal ascent of a homogeneous basaltic magma with an aqueous volatile phase and newtonian rheology. By fixing the geometry of the feeding fissure, the mass flux flowing in steady conditions can be determined at any depth, as well the magma pressure and vertical velocity. Flow behaviour is analysed for three fissure shapes: constant width, slowly upward narrowing and lenticular. In all the cases examined the magma arrives at the earth's surface with a pressure greater than atmospheric. The results are compared with those obtained when a lithostatic pressure gradient is assumed for the magma column. Some speculations are made, moreover, about the change in eruption style, if conduit geometry varies during a non-steady phase.

  16. Hough transform detection of the longitudinal fissure in tomographic head images.

    PubMed

    Brummer, M E

    1991-01-01

    A technique is presented for automatic detection of the longitudinal fissure in tomographic scans of the brain. The technique utilizes the planar nature of the fissure and is a three-dimensional variant of the Hough transform principle. Algorithmic and computational aspects of the technique are discussed. Results and performance on coronal and transaxial magnetic resonance data show that the algorithm is robust with respect to variations in image contrast in the data and to slight anatomic anomalies. A crucial resolution requirement in the data for accurate parameter estimations is a sufficient number of slices covering the whole brain. The Sobel magnitude edge operator, used for preprocessing, proved adequate for magnetic resonance scans with positive and negative brain/cerebrospinal fluid contrast.

  17. Quality Assessment of Information About Pit and Fissure Sealants in Persian Websites in 2012

    PubMed Central

    Ghasemi, Leila

    2016-01-01

    Objectives: Despite the increasing use of Internet, there is no supervision over the accuracy and quality of the information provided in the web. To deal with this problem, health specialists should take part in planning, publishing and supervision of online health-related information. The aim of this study was to evaluate the quality of information related to pit and fissure sealants in Persian websites. Materials and Methods: In this cross-sectional study, Persian websites providing information about fissure sealants were found using Google search engine. The searched keywords according to the MeSH database were “patient education” and “fissure sealant”. After applying the exclusion criteria, 37 websites out of 500 initial links remained in the study. These websites were evaluated based on a researcher-made checklist. The validity and reliability of the checklist were evaluated and confirmed. Descriptive analysis was applied to report the results of our study using SPSS version 11.5. Results: The average score for the quality of information was 22.46 out of 38. The minimum scores were 16 and 30 and belonged to Pezeshkanemrooz.com and Asa85.blogfa.com , respectively. The results showed that 62.2% of the answers were scored 2–4 and 37.8% were scored 1; therefore, the overall quality of the published content was rated to be moderate for 62.2% and low for 37.8% of the websites. Conclusions: Overall, the quality of information related to fissure sealant provided in Persian websites was good; however, the information given was mostly incomplete and could be improved. The main problems were doubtful credibility and outdated information. PMID:27536329

  18. Comparative Evaluation of the Marginal Sealing Ability of two Commercially Available Pit and Fissure Sealants

    PubMed Central

    Moses, Joyson; Rangeeth, Bollam Nammalwar; Sivakumar, Subramanian

    2016-01-01

    Introduction The occlusal surfaces of the teeth usually have pits and fissures which provide a good environment for demineralization with minimal salivary access and make them caries prone. The success of pit and fissure sealing materials is highly dependent on the marginal sealing ability of the fissures. Aim The present study was carried out to evaluate and compare the marginal sealing ability of two commercially available pit and fissure sealants. Materials and Methods A total of 50 human premolar teeth were used in this invitro study. Group 1 included 25 teeth for application of Clinpro sealant and Group 2 included twenty 25 for application of Helioseal F sealant. Samples were stored in artificial saliva for 72 hours before thermocycling. The samples were immersed in 2% methylene blue solution for 24 hours. The sectioned samples were examined under an Optical Stereomicroscope and compared in terms of the extent of microleakage based on the amount of dye penetration between the sealant and tooth substance interface. The dye penetration scores in both the groups was statistically analysed using Chi square test and Mann Whitney Test. A p-value of less than 0.05 was considered to be statistically significant. Results It was seen that in Group 1, 12 samples (48%) had no dye penetration (Grade 0) while in Group 2, 6 samples (24%) demonstrated Grade 0 penetration. Group 2 had the most extensive dye penetration (Grade 3) in 8 of 25 samples (32%) (p=0.014). Conclusion On comparison of the microleakage scores of the groups, a statistically significant difference was found between the two groups; indicating a much better performance of Clinpro as compared to Helioseal F. PMID:27790568

  19. [Surgical therapy of chronic anal fissure--do additional proctologic operations impair continence?].

    PubMed

    Pfeifer, J; Berger, A; Uranüs, S

    1994-07-01

    78 patients with chronic anal fissures have been mainly operated on by lateral internal sphincterotomy (LATS). Continence have been evaluated by questionnaire at least 9 months postoperatively. Patient without any additional proctological operation had minor disturbances of continence in 17%. Patient with additional operations had disturbances of continence in 30%. Especially the subgroup of patients with LATS and haemorrhoidectomy had bad results. In this group only 45% were fully continent.

  20. Artificial recharge through a well in fissured carbonate rock, west St. Paul, Minnesota

    USGS Publications Warehouse

    Reeder, Harold O.; Wood, Warren W.; Ehrlich, G.G.; Sun, Ren Jen

    1976-01-01

    The injection test demonstrated that it is hydrologically feasible to recharge the Prairie du Chien Group and the Jordan Sandstone artificially through wells completed in the Prairie du Chien Group. The fissures in the Prairie du Chien Group act as conduits through which water spreads. The water passes into the Jordan Sandstone from the Prairie du Chien over a larger area than it would if it were injected directly into the Jordan.

  1. Natural Treatments for Fissure in Ano Used by Traditional Persian Scholars, Razi (Rhazes) and Ibn Sina (Avicenna).

    PubMed

    Derakhshan, Ali Reza

    2016-06-08

    Most cases of chronic fissure do not respond to medical treatment. Razi and Ibn Sina were 2 of the best-known scientists of ancient Persia. The purpose of this study was to find out new scientific evidence in modern medicine about their recommendations, in order to find certain clues to conduct useful researches in the future. First, treatments of anal fissure mentioned by Razi and Ibn Sina were reviewed. Then, literature search was made in electronic databases including PubMed, Scopus, and Google Scholar. Management of anal fissure according to Razi's and Ibn Sina's practices is done based on 3 interventions: lifestyle modifications, drug treatments, and manual procedures. Almost all remedies suggested by Razi and Ibn Sina have shown their effects on fissure in ano via several mechanisms of action in many in vitro and in vivo studies; Still there is lack of human studies on the subject.

  2. The pattern of circumferential and radial eruptive fissures on the volcanoes of Fernandina and Isabela islands, Galapagos

    USGS Publications Warehouse

    Chadwick, W.W.; Howard, K.A.

    1991-01-01

    Maps of the eruptive vents on the active shield volcanoes of Fernandina and Isabela islands, Galapagos, made from aerial photographs, display a distinctive pattern that consists of circumferential eruptive fissures around the summit calderas and radial fissures lower on the flanks. On some volcano flanks either circumferential or radial eruptions have been dominant in recent time. The location of circumferential vents outside the calderas is independent of caldera-related normal faults. The eruptive fissures are the surface expression of dike emplacement, and the dike orientations are interpreted to be controlled by the state of stress in the volcano. Very few subaerial volcanoes display a pattern of fissures similar to that of the Galapagos volcanoes. Some seamounts and shield volcanoes on Mars morphologically resemble the Galapagos volcanoes, but more specific evidence is needed to determine if they also share common structure and eruptive style. ?? 1991 Springer-Verlag.

  3. Squamotympanic fissure in the Ngandong and Sambungmacan hominids: a reply to Delson et al.

    PubMed

    Durband, Arthur C

    2002-03-01

    In the present study the course of the squamotympanic fissure of the mandibular fossa is examined in several fossil hominid specimens. While previous work by several authors had found that the course of this fissure was potentially autapomorphic for the Ngandong and Sambungmacan fossil samples from Indonesia, a more recent study performed by Delson et al. (Anat Rec 2001; 262:380--397) reported that a number of other fossils, including OH 9, Sangiran 4 and 17, and KNM WT 15000 were similar to the Ngandong and Sambungmacan specimens in the expression of this feature. To test these findings, those specimens purported to share similarities with Ngandong and Sambungmacan were examined. The results of this study indicate clearly differing morphologies between the Ngandong and Sambungmacan fossils, on the one hand, and the four African and Indonesian fossils named by Delson et al. (2001). Hence, the course of the squamotympanic fissure remains a potentially autapomorphic feature separating the Ngandong and Sambungmacan samples from the remaining specimens allocated to Homo erectus.

  4. A Nonoperative Approach for Neurosurgical Management of a Sylvian Fissure Dermoid Cyst

    PubMed Central

    Haider, Ali S; Kee, Clarence; DeBacker, Danielle L; Watson, Ian T; Arrey, Eliel N; Osumah, Tijani; Chen, Chen; Alam, Maryam; Toussaint III, L. Gerard

    2016-01-01

    The nonoperative management of sylvian fissure dermoid/epidermoid cysts presents a risk that is difficult to quantify. With rupture, potentially fatal complications such as chemical meningitis, hydrocephalus, fever, seizure, or meningeal irritation may occur. In this paper, we present an asymptomatic case of such a cyst with imaging evidence of prior rupture, and we review the literature for the likelihood of future complications. We use for illustration a case of a 68-year-old woman with imaging features of a sylvian fissure epithelial inclusion cyst who refused surgical intervention and review the literature for further investigation. Conservative management of our patient has not resulted in a complication in over five years, with the continued offer of surgical resection rejected by the patient. This article suggests the possibility of a safe, non-operative management of dermoid/epidermoid cysts of the sylvian fissure; however, the paucity of literature calls for larger studies yielding reliable data regarding the comparative risk of nonoperative management, including the rate of spontaneous rupture, versus the risk and complication incidence of surgical intervention. PMID:27909631

  5. Endoscopic endonasal anatomy of superior orbital fissure and orbital apex regions: critical considerations for clinical applications.

    PubMed

    Dallan, Iacopo; Castelnuovo, Paolo; de Notaris, Matteo; Sellari-Franceschini, Stefano; Lenzi, Riccardo; Turri-Zanoni, Mario; Battaglia, Paolo; Prats-Galino, Alberto

    2013-05-01

    The superior orbital fissure is a critical three-dimensional space connecting the middle cranial fossa and the orbit. From an endoscopic viewpoint, only the medial aspect has a clinical significance. It presents a critical relationship with the lateral sellar compartment, the pterygopalatine fossa and the middle cranial fossa. The connective tissue layers and neural and vascular structures of this region are described. The role of Muller's muscle is confirmed, and the utility of the maxillary and optic strut is outlined. Muller's muscle extends for the whole length of the inferior orbital fissure, passes over the maxillary strut and enters the superior orbital fissure, representing a critical surgical landmark. Dividing the tendon between the medial and inferior rectus muscle allows the identification of the main trunk of the oculomotor nerve, and a little laterally, it is usually possible to visualize the first part of the ophthalmic artery. Based on a better knowledge of anatomy, we trust that this area could be readily addressed in clinical situations requiring an extended approach in proximity of the orbital apex.

  6. Arteries and Veins of the Sylvian Fissure and Insula: Microsurgical Anatomy.

    PubMed

    Delion, Matthieu; Mercier, Philippe; Brassier, Gilles

    2016-01-01

    We present a vascular anatomical study of the arteries and veins of the sylvian fissure and insula.A good knowledge of the sylvian fissure, the insula, and their vascular relationship would seem mandatory before performing surgery in this area, whatever the type of surgery (aneurysms, arteriovenous malformations, insular tumors).We start with the sylvian fissure and insula morphology, followed by the MCA description and its perforators, with special attention paid to the insular perforators. We demonstrate that the long insular perforators penetrating in the superior part of the posterior short gyrus and long gyri vascularize, respectively, the corticonuclear and corticospinal fasciculi. We particularly insist too on three anatomical constants regarding the vascularization of the insula, already described in the literature: The superior periinsular sulcus is the only sulcus on the lateral surface of the brain without an artery along its axis; the superior branch of the MCA supplies the anterior insular pole and both the anterior and middle short gyri in 100 % of cases; in at least 90 % of cases, the artery that supplied the central insular sulcus continued on to become the central artery.We end with the anatomical study of the veins and cisterns.

  7. Prediction of caries development for molar fissures with semiquantitative mutans streptococci test.

    PubMed

    Splieth, C; Bernhardt, O

    1999-06-01

    Risk-specific caries prevention requires validated and simple parameters for a caries risk assessment. The aim of the study was to evaluate the validity of a site-specific chair-side mutans streptococci (MS) test for the prediction of caries incidence in fissures. In 230 6- to 7-yr-old children, occlusal plaque samples of teeth 16 and 36 were cultured with Dentocult SM tests at 37 degrees C for 24 hr. Caries (DMFS), initial caries, sealants, and a plaque index (QHI) were recorded and oral hygiene habits were assessed. Not erupted, carious, filled and sealed teeth were excluded from the analysis (n = 154). After 2 yr, the status of the fissures was re-examined, and a fluoride history was recorded with a questionnaire filled out by the children's parents. Sealed teeth were excluded again (n = 54). With a classification of MS score 0 or 1 as low and MS score 2 or 3 as high caries risk, 92% agreement was reached by two independently working examiners. The MS scores and caries incidence correlated significantly. Seventy-eight % of the caries progression in fissures was prognosed correctly. Sensitivity was 50%, specificity 82%, positive predictive value 29%, and negative predictive value 92%. Children with caries progression tended to have lower fluoride scores. Low MS scores were most likely to be associated with low caries incidence, while high mutans streptococci scores seem to be partially compensated by other parameters.

  8. Distributed Computing for Seismic Data Retrieval using FISSURES DHI Client FMI Implimented from MatSeis 1.9

    NASA Astrophysics Data System (ADS)

    Hart, D. M.; Li, Q.; Creager, K. C.; Ning, R.; Crotwell, H. P.; Zuzlewski, S.; Hellman, S. B.; Schoch, K. S.; Laughbon, C. J.; Stromme, S. R.

    2004-12-01

    Three software development efforts have recently combined to allow a seamless method for obtaining data from the IRIS DMC over the Internet and analyzing it in MATLAB. During the past few years IRIS has constructed the initial framework and definitions for FISSURES servers and Data Handling Interface (DHI) clients. FISSURES uses the distributed computing language Common Object Request Broker Architecture (CORBA), which allows software systems to work across the Internet in a platform independent and computer-language neutral manner. Starting from the FISSURES object model three seismic services have been defined: event, network and seismogram. From these three object types a DHI client is used to access information through FISSURES services. Using the University of Washington developed FISSURES-Matlab-Interface (FMI) DHI client, all three FISSURES objects can be accessed via the Internet and downloaded into local MATLAB objects, allowing access to earthquake event catalogs, seismograms, network and instrument information. The DHI client FMI can be implemented from MatSeis. MatSeis, developed at Sandia National Laboratory, is a MATLAB based, Graphical User Interface (GUI) controlled software package with seismic data visualization, signal processing, and database importing and exporting capabilities, to list just a few. In this poster, we will discuss the seismic data retrieval currently prototyped for the IRIS DMC, as well as the planned connections to the Northern California Earthquake Data Center (NCEDC), Southern California Earthquake Data Center (SCEDC), and South Carolina Earth Physics Project (SCEPP) data center.

  9. Method for laser drilling subterranean earth formations

    DOEpatents

    Shuck, Lowell Z.

    1976-08-31

    Laser drilling of subterranean earth formations is efficiently accomplished by directing a collimated laser beam into a bore hole in registry with the earth formation and transversely directing the laser beam into the earth formation with a suitable reflector. In accordance with the present invention, the bore hole is highly pressurized with a gas so that as the laser beam penetrates the earth formation the high pressure gas forces the fluids resulting from the drilling operation into fissures and pores surrounding the laser-drilled bore so as to inhibit deleterious occlusion of the laser beam. Also, the laser beam may be dynamically programmed with some time dependent wave form, e.g., pulsed, to thermally shock the earth formation for forming or enlarging fluid-receiving fissures in the bore.

  10. Performance of a conventional sealant and a flowable composite on minimally invasive prepared fissures.

    PubMed

    Francescut, Paola; Lussi, Adrian

    2006-01-01

    Three different fissure preparation procedures were tested and compared to the non-invasive approach using a conventional unfilled sealant and a flowable composite. Eighty permanent molars were selected and divided into 4 groups of 20 teeth each. All the teeth were split into 2 halves, and the exposed fissures were photographed under a microscope (35x) before and after being prepared using the following methods: (I) Er:YAG laser (KEY Laser, KaVo) 600 mJ pulse energy, 6 Hz; (II) diamond bur; (III) Er: YAG laser (KEY Laser, KaVo) 200 mJ pulse energy, 4 Hz; (IV) Control group: Powder jet cleaner (Prophyflex, KaVo, Germany). The pre-and postimages were superimposed in order to evaluate the amount of hard tissue removed. Ten teeth in each group were then acid etched and sealed with an unfilled sealant (Delton opaque, Dentsply), while the remaining 10 teeth were acid etched, primed and bonded (Prime & Bond NT, Dentsply) and sealed with a flowable composite (X-flow, DeTrey, Dentsply). Material penetration and microleakage were evaluated after thermocycling (5000 cycles) and staining with methylene blue 5%. ANOVA and Mann-Whitney tests were applied for statistical analysis. The laser 600 mJ and bur eliminated the greatest amount of hard tissue. The control teeth presented the least microleakage when sealed with Delton or X-flow. A correlation between material penetration and microleakage could not be statistically confirmed. Mechanical preparation prior to fissure sealing did not enhance the final performance of the sealant.

  11. Fissure distribution at Mauna Loa (Hawaii) as an example to understand shallow magma transfer at volcanoes

    NASA Astrophysics Data System (ADS)

    La Marra, Daniele; Acocella, Valerio; Trusdell, Frank

    2016-04-01

    Mauna Loa (Hawaii) is the largest active shield volcano on the Island of Hawai'i, covering more than half of it and rising to 4,169 meters above sea level. The volcano hosts the Moku'aweoweo summit caldera, from which two elongated rift zones depart: the Northeast Rift Zone (NERZ) and the Southwest Rift Zone (SWRZ). Most of Mauna Loa's eruptions begin with lava fountains from a series of fissure vents in the summit region and then often migrate to vents down either rift zone. Mauna Loa volcano shows a distinctive feature, being characterized by minor radial eruptive fissures (not related to the two main rifts) on the NW flank only. This study tries to explain such a selective distribution of vents, and thus of shallow magma transfer. To this aim, we run numerical models with different amount of opening of the two rift zones of Mauna Loa, as well as different amount of slip on its SE flank. Our results suggest that the selective occurrence of the radial fissures may be explained by the competition between two processes: a) rift intrusion (especially along the NERZ), promoting the development of radial dikes along the NW flank; b) flank slip, inhibiting the development of the radial dikes on the SE flank. The opening of the two non-parallel main rift zones of Mauna Loa promotes the local extension necessary to develop the radial dikes on the NW flank. A general model for the development of a third branch of radial rift, which may be also applied to Mt. Etna and some volcanoes on the Canary Islands, is proposed.

  12. Anal Fissures

    MedlinePlus

    ... Diet Plans Nutrients and Nutritional Info Sugar and Sugar Substitutes Exercise and Fitness Exercise Basics Sports Safety Injury Rehabilitation ... Diet Plans Nutrients and Nutritional Info Sugar and Sugar Substitutes Exercise and Fitness Exercise Basics Sports Safety Injury Rehabilitation ...

  13. Anal Fissure

    MedlinePlus

    ... and Conditions Find A Surgeon Patients ASCRS Non-Discrimination Statement Privacy Policy Research Foundation of the ASCRS Non-Discrimination Statement About Us ASCRS News Video Disclaimer Social ...

  14. Fissured Tongue

    MedlinePlus

    ... and Vision Leadership Executive Committee Board of Trustees Governance Past Presidents Staff/Contact History Awards Our Partners ... symptoms. No treatment is necessary except to encourage good oral hygiene including brushing the top surface of ...

  15. Continuous monitoring of an earth fissure in Chino, California, USA - a management tool

    NASA Astrophysics Data System (ADS)

    Carpenter, M. C.

    2015-11-01

    Continuous measurements of deformation have been made in Chino, California across an earth fissure and nearby unfissured soil since 2011 in two buried, horizontal, 150 mm pipes, 51 m long, which are connected by sealed boxes enclosing vertical posts at mostly 6 m intervals. Horizontal displacements and normal strain are measured in one line using nine end-to-end quartz tubes that are attached to posts and span fissured or unfissured soil. The free ends of the tubes are supported by slings and move relative to the attachment post of the next quartz tube. Linear variable differential transformer (LVDT) sensors measure the relative movements. Five biaxial tilt sensors were also attached to selected posts in that line. Relative vertical movement was measured at nine locations along the line in the second pipe using low-level differential pressure sensors. The second pipe is half full of water giving a free water surface along its length. Data are recorded on a Campbell CR10 using multiplexers. The quartz-tube horizontal extensometers have exhibited more than 3 mm of predominantly elastic opening and closing in response to about 32 m of seasonal drawdown and recovery, respectively, in an observation well 0.8 km to the south. The nearest production well is 1.6 km to the west. The horizontal strain was 5.9 × 10-5 or 30 % of the lowest estimate of strain-at-failure for alluvium. Maximum relative vertical movement was 4.8 mm. Maximum tilt in the fissure zone was 0.09 arcdeg while tilt at a separate sensor 100 m to the east was 0.86 arcdeg, indicating a wider zone of deformation than is spanned by the instrumentation. High correlation of horizontal displacements during drawdown, and especially recovery, with change in effective stress supports differential compaction as the mechanism for earth-fissure movement. The continuous measurements of horizontal strain coupled with water-level fluctuations and vertical borehole extensometry can provide a real-time adaptive management

  16. Understanding the link between circumferential dikes and eruptive fissures around calderas based on numerical and analog models

    NASA Astrophysics Data System (ADS)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Acocella, Valerio

    2016-06-01

    Active calderas are seldom associated with circumferential eruptive fissures, but eroded magmatic complexes reveal widespread circumferential dikes. This suggests that, while the conditions to emplace circumferential dikes are easily met, mechanisms must prevent them from reaching the surface. We explain this discrepancy with experiments of air injection into gelatin shaped as a volcano with caldera. Analog dikes show variable deflection, depending on the competition between overpressure, Pe, and topographic unloading, Pl; when Pl/Pe = 4.8-5.3, the dikes propagate orthogonal to the least compressive stress. Due to the unloading, they become circumferential and stall below the caldera rim; buoyancy is fundamental for the further rise and circumferential fissure development. Numerical models quantitatively constrain the stress orientation within the gelatin, explaining the observed circumferential dikes. Our results explain how dikes propagate below the rim of felsic and mafic calderas, but only in the latter they are prone to feed circumferential fissures.

  17. The link between circumferential dikes and eruptive fissures around calderas: insights from numerical and analog models

    NASA Astrophysics Data System (ADS)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Acocella, Valerio

    2016-04-01

    Active calderas are seldom associated with circumferential eruptive fissures along their rim, but eroded portions of extinct magmatic complexes reveal widespread evidence of circumferential dikes. This discrepancy suggests that, while the conditions to emplace circumferential dikes below volcanoes are easily met, mechanisms must exist to arrest the dikes before they reach the surface. Here we explain this discrepancy with laboratory experiments of air injection into a gelatin medium shaped to mimic a volcanic edifice with caldera. Our models show that the ascending dikes experience a variable degree of deflection, depending on the competition between dike overpressure, Pe, and the forcing induced by the topographic load, Pl. When Pl/Pe = 4.3 - 4.5 the analog dikes proceed almost insensitive to the stress rotation and erupt within the caldera. When Pl/Pe = 4.8 - 5.3 the analog dikes closely propagate orthogonal to the least compressive stress σ3 and stall below the caldera rim in a circumferential arrangement. Progressive buoyancy increase through repeated supply of fluid is fundamental for the occurrence of circumferential fissures. Complementary numerical models explain the observed circumferential arrangement and validate the experiments. These results contribute defining the shallow magma transfer and related hazard assessment within calderas.

  18. Le Fort I osteotomy to enucleation of grand proportions fissural cyst-presentation of case report.

    PubMed

    Cavalcante, Rafael Correia; Durski, Fernanda; Deliberador, Tatiana Miranda; Giovanini, Allan Fernando; Rebellato, Nelson Luís Barbosa; da Costa, Delson João; Klüppel, Leandro Eduardo; Scariot, Rafaela

    2016-01-01

    Fissural cysts (FC) are caused by entraped epithelium between nasal and maxilar processes. They are commonly treated with surgical enucleation precedded or not by marsupialization depending on the cyst size. Biopsy of lesion is recommended due to confirm radiographic evaluation. It is rare to observe Le Fort I surgical approach to this type of injury. This study reports the case of an uncommon grand proportions fissural cyst in a female patient, 53, that was referred to the Oral and Maxillofacial Surgery Departament of Hospital XV presenting volume increase in maxilla associated with numbness of palate. Radiograph examination showed an intimate relationship between incisors apexes and FC. Expansion of both buccal and palate cortical was then confirmed as well as its unusual size, approximately 25 millimeters. Due to the abnormal size of lesion and possible impairment of upper incisors, LeFort I osteotomy associated with downfracture to cystic enucleation was the chosen treatment. After enucleation, the remaining space was filled with BIOSs and bioguide (lyophilized bone and collagen membrane). Patients' twelve months follow-up demonstrate no relapses and maintenance of teeth involved.

  19. Effects of aging on surface properties and adhesion of Streptococcus mutans on various fissure sealants.

    PubMed

    Bürgers, Ralf; Cariaga, Tashiana; Müller, Rainer; Rosentritt, Martin; Reischl, Udo; Handel, Gerhard; Hahnel, Sebastian

    2009-12-01

    The aim of the present study was the quantification of Streptococcus mutans adhesion on ten widely used pit and fissure sealant materials and the correlation of these findings to surface roughness (R(a)) and surface free energy (SFE). Additionally, changes in streptococcal adhesion and surface parameters after water immersion and artificial aging have been investigated. Circular specimens of ten fissure sealants (seven resin-based composites, two glass ionomers, and one compomer) were made and polished. Surface roughness was determined by perthometer and SFE by goniometer measurements. Sealant materials were incubated with S. mutans suspension (2.5 h, 37 degrees C), and adhering bacteria were quantified by using a biofluorescence assay in combination with an automated plate reader. Surface properties and S. mutans adhesion were measured prior to and after water immersion after 1 and 6 months and after additional thermocycling (5,000 cycles; 5 degrees C/55 degrees C). The tested sealants showed significant differences in S. mutans adhesion prior to and after the applied aging procedures. Aging resulted in slight increases (mostly <0.2 microm) in surface roughness, as well as in significant decreases in SFE and in significantly lower quantities of adhering bacteria. Ketac Bond and UltraSeal XT plus revealed the lowest adhesion potential after artificial aging. In general, the amount of adhering S. mutans was reduced after aging, which may be related to the decline in SFEs.

  20. Deep Orbital Dermoid Cyst Bulging into the Superior Orbital Fissure: Clinical Presentation and Management

    PubMed Central

    Kumar, Ravinder; Vyas, Kapil; Jaiswal, Gagan; Bhargava, Abhishek; Kundu, Jyoti

    2017-01-01

    Purpose: To present a case of deep orbital dermoid cyst with emphasis on clinical presentation, imaging spectrum, differential diagnosis and management. Case Report: A 28-year-old female was referred to our hospital with chief complaint of drooping of right eyelid and progressive headache. Ocular motility, visual acuity and fundus examination were normal. computed tomography (CT) and magnetic resonance imaging (MRI) revealed a well-defined, intraosseous deep orbital dermoid cyst (5.9 mm × 12.5 mm) located near the apex of right orbit, extending from greater wing of sphenoid into the superior orbital fissure. Due to occulomotor nerve (superior and inferior divisions) compression which passes through the superior orbital fissure, ipsilateral headache and ptosis occurred. Complete surgical excision of cyst was performed using noninvasive extracranial lateral orbitotomy approach. After removal of the cyst, curette and cutting drill were used to thoroughly remove any residual cystic content. Histopathological analysis confirmed the diagnosis. The healing was uneventful postoperatively. Conclusion: CT and MRI are easy, reliable, safe and effective imaging methods for establishing the diagnosis of orbital dermoid cyst. Size, location and manifestations are the most important determinants of the disease management. Complete surgical excision without rupture of the cyst is the treatment of choice. PMID:28299014

  1. Experimental and theoretical study of entrainment in volcanic line plumes produced by fissure eruptions

    NASA Astrophysics Data System (ADS)

    Paillat, S.; Kaminski, E. C.

    2013-12-01

    Basaltic fissure eruptions can produce turbulent line plumes injecting gas and particles in the atmosphere. The dynamic of these line plumes is controlled by the efficiency of entrainment as quantified by the so-called entrainment coefficient α. There are only scarce experimental constraints on α in planar jets and plumes. Whereas a constant value of the entrainment coefficient is used in models, data from the literature show a variation of α in pure planar jets. Only a few data are available for plumes. In order to better constrain the entrainment coefficient, we propose a theoretical expression of the entrainment coefficient α, as a function of buoyancy and turbulent structure. The model is validated first, using data from the literature and new experiments in pure jets and plumes. We show that the entrainment coefficient reaches a constant value at large distances from the source and high Reynolds number in pure jets. Positive buoyancy enhances the entrainment in pure plumes where α is about two times larger. The theoretical expression of the entrainment coefficient is then used to study the effect of variable entrainment on the dynamics of volcanic line plumes produced above an eruptive fissure at different scales, ranging from small Hawaiian fountains to basaltic Plinian eruptions (e.g. 1783 Laki eruption) and flood basalts. Both the stability of the eruptive column and the maximum height it reaches in the atmosphere are affected by variable entrainment.

  2. Monitoring an eruption fissure in 3D: video recording, particle image velocimetry and dynamics

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2015-04-01

    The processes during an eruption are very complex. To get a better understanding several parameters are measured. One of the measured parameters is the velocity of particles and patterns, as ash and emitted magma, and of the volcano itself. The resulting velocity field provides insights into the dynamics of a vent. Here we test our algorithm for 3 dimensional velocity fields on videos of the second fissure eruption of Bárdarbunga 2014. There we acquired videos from lava fountains of the main fissure with 2 high speed cameras with small angles between the cameras. Additionally we test the algorithm on videos from the geyser Strokkur, where we had 3 cameras and larger angles between the cameras. The velocity is calculated by a correlation in the Fourier space of contiguous images. Considering that we only have the velocity field of the surface smaller angles result in a better resolution of the existing velocity field in the near field. For general movements also larger angles can be useful, e.g. to get the direction, height and velocity of eruption clouds. In summary, it can be stated that 3D velocimetry can be used for several application and with different setup due to the application.

  3. Maintenance therapy with unprocessed bran in the prevention of acute anal fissure recurrence.

    PubMed Central

    Jensen, S L

    1987-01-01

    The effect of unprocessed bran in a dose of 5 g three times daily and a dose of 2.5 g three times daily for one year on the recurrence rate of anal fissures was studied in a double-blind, placebo-controlled trial in 90 patients with recently healed acute posterior anal fissures. Fifteen patients (16.6%) were withdrawn before the code was broken due to failure to follow the trial protocol for various reasons. Significantly fewer recurrences occurred in patients receiving bran 5 g three times daily (recurrence rate 16%, 95% confidence limits, 4.54 to 36.08) when compared with patients receiving bran 2.5 g three times daily (60%; 38.67 to 78.87) (P less than 0.01) and with patients receiving placebo three times daily (68%; 46.50 to 85.05) (P less than 0.01). No significant difference in recurrences was found between patients on bran 2.5 g and those on placebo. PMID:3039130

  4. Wear of two pit and fissure sealants in contact with primary teeth

    PubMed Central

    Galo, Rodrigo; Contente, Marta Maria Martins Giamatei; Borsatto, Maria Cristina

    2014-01-01

    Objectives: Wear simulations may provide an indication of the clinical performance of pit-and-fissure sealants when associated with primary teeth as counterbody, restricting the involved variables. The aim of this study was to evaluate wear of dental materials used as pit-and-fissure sealants in contact with primary teeth. Materials and Methods: A resinous sealant (Fluroshield®) and a resin-modified glass ionomer cement (Vitremer®) were selected in a post-plate design, using as counterbody primary tooth pins (4 × 4 × 2 mm) at 3 and 10 N vertical load, 1 Hz frequency, 900 wear cycles in artificial saliva (n = 15). Attrition coefficient values were obtained and the material and primary tooth volumes were analyzed. Data were analyzed statistically by ANOVA and Duncan's test (P < 0.05). Results: Fluroshield® presented the highest attrition coefficient values for the 3 N but these values decreased significantly for the 10 N load. The means for volume loss (3 mm) of the different samples after the wear test were not statistically different for the materials. The volume loss values for the primary teeth were statistically different and there was an increase in volume loss with the increase of the load applied in the wear tests. Conclusions: Differences were also observed with regard to the surface deformation characteristics. The wear rates of primary tooth enamel vary according to the type of material and the load applied during mastication. PMID:24966777

  5. Sylvian fissure asymmetries in monozygotic twins: a test of laterality in schizophrenia.

    PubMed

    Bartley, A J; Jones, D W; Torrey, E F; Zigun, J R; Weinberger, D R

    1993-12-15

    To address prior reports that schizophrenia is associated with loss of normal brain asymmetry and that it might be linked to a defect of a gene controlling cerebral lateralization, we measured on three-dimensional cortical renderings from magnetic resonance imaging (MRI) scans the lengths and angles of the sylvian fissures in 10 normal monozygotic (MZ) twin pairs (n = 10 pairs) and in 10 MZ pairs discordant for schizophrenia (n = 10 pairs). We confirmed in both sets of twins the expected normal asymmetries of length and angle of the sylvian fissure. We also confirmed that the length asymmetry occurs solely in the region of the planum temporale. In the discordant twins, affected and unaffected twins did not differ in asymmetry measures, thus failing to support an association between illness per se and diminished asymmetry. Moreover, the discordant twins as a group did not differ from the normal twins as a group, thus failing to confirm the hypothesis of a genetic association with abnormal asymmetry. The implications of variations in methodology and patient samples are discussed.

  6. Monitoring of land subsidence and ground fissures in Xian, China 2005-2006: Mapped by sar Interferometry

    USGS Publications Warehouse

    Zhao, C.Y.; Zhang, Q.; Ding, X.-L.; Lu, Zhiming; Yang, C.S.; Qi, X.M.

    2009-01-01

    The City of Xian, China, has been experiencing significant land subsidence and ground fissure activities since 1960s, which have brought various severe geohazards including damages to buildings, bridges and other facilities. Monitoring of land subsidence and ground fissure activities can provide useful information for assessing the extent of, and mitigating such geohazards. In order to achieve robust Synthetic Aperture Radar Interferometry (InSAR) results, six interferometric pairs of Envisat ASAR data covering 2005–2006 are collected to analyze the InSAR processing errors firstly, such as temporal and spatial decorrelation error, external DEM error, atmospheric error and unwrapping error. Then the annual subsidence rate during 2005–2006 is calculated by weighted averaging two pairs of D-InSAR results with similar time spanning. Lastly, GPS measurements are applied to calibrate the InSAR results and centimeter precision is achieved. As for the ground fissure monitoring, five InSAR cross-sections are designed to demonstrate the relative subsidence difference across ground fissures. In conclusion, the final InSAR subsidence map during 2005–2006 shows four large subsidence zones in Xian hi-tech zones in western, eastern and southern suburbs of Xian City, among which two subsidence cones are newly detected and two ground fissures are deduced to be extended westward in Yuhuazhai subsidence cone. This study shows that the land subsidence and ground fissures are highly correlated spatially and temporally and both are correlated with hi-tech zone construction in Xian during the year of 2005–2006.

  7. Fine mapping and introgressing qFIS1-2, a major QTL for kernel fissure resistance in rice (Oryza sativa L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice (Oryza sativa L.) kernel fissuring increases breakage during milling and decreases the value of processed rice. This study employed molecular gene tagging methods to fine-map a fissure resistance (FR) locus in ‘Cybonnet’, a semidwarf tropical japonica cultivar, as well as transfer this trait to...

  8. Three QTLs conferring resistance to kernel fissuring in rice (Oryza sativa L.) identified by selective genotyping in two tropical japonica populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Kernel fissures caused by pre- or post-harvest stresses are the leading cause of breakage among milled rice, causing economic losses for producers, millers, and processors. Being an environmentally sensitive trait, it is difficult to reliably select for rice fissure resistance among breeding progen...

  9. Rise and Collapse of Volcanic Plumes Produced By Explosive Basaltic Fissure Eruptions

    NASA Astrophysics Data System (ADS)

    Paillat, S.; Kaminski, E. C.

    2014-12-01

    Explosive basaltic fissure eruptions, which release large amounts of sulfur gases in the atmosphere, can have a big impact on climate. The effect on climate depends on the rate of gas injection above the tropopause. The key parameter is the height reached by the eruptive plume as a function of mass flux and entrainment rate. We propose a model of entrainment in 2D volcanic plumes based on lab scale experiments on turbulent jets and plumes. In this model, entrainment varies with the Richardson number and we predict that the height of the column critically depends on the source buoyancy flux determined by the eruptive temperature and the amount of gas in the volcanic mixture at the vent. We obtain that "hot" basaltic planar plumes form stable eruptive columns, even for large eruption rates. Only if fragmentation is not efficient enough, the column collapse will prevent the injection of gas in the stratosphere.

  10. Enamel pretreatment with Er:YAG laser: effects on the microleakage of fissure sealant in fluorosed teeth

    PubMed Central

    Kianimanesh, Nasrin; Shayeghi, Bahareh

    2014-01-01

    Objectives The purpose of this in vitro study was to evaluate the microleakage and penetration of fissure sealant in permanent molar teeth with fluorosis after pretreatment of the occlusal surface. Materials and Methods A total of 120 third molars with mild dental fluorosis were randomly divided into 6 groups (n = 20). The tooth surfaces were sealed with an unfilled resin fissure sealant (FS) material. The experimental groups included: 1) phosphoric acid etching (AE) + FS (control); 2) AE + One-Step Plus (OS, Bisco) + FS; 3) bur + AE + FS; 4) bur + AE + OS + FS; 5) Er:YAG laser + AE + FS; and 6) Er:YAG laser + AE + OS + FS. After thermocycling, the teeth were immersed in 0.5% fuchsin and sectioned. Proportions of mircoleakage (PM) and unfilled area (PUA) were measured by digital microscope. Results Overall, there were significant differences among all groups in the PM (p = 0.00). Group 3 showed the greatest PM, and was significantly different from groups 2 to 6 (p < 0.05). Group 6 showed the lowest PM. Pretreatment with Er:YAG with or without adhesive led to less PM than bur pretreatment. There were no significant differences among groups in PUA. Conclusions Conventional acid etching provided a similar degree of occlusal seal in teeth with fluorosis compared to those pretreated with a bur or Er:YAG laser. Pretreatment of pits and fissures with Er:YAG in teeth with fluorosis may be an alternative method before fissure sealant application. PMID:25110641

  11. Normal values of inner canthal distance, interpupillary distance and palpebral fissure length in normal Chinese children in Taiwan.

    PubMed

    Wu, K H; Tsai, F J; Li, T C; Tsai, C H; Peng, C T; Wang, T R

    2000-01-01

    Ocular measurements, including inner canthal distance, outer canthal distance, interpupillary distance, and palpebral fissure length are important in the evaluation of congenital deformities and posttraumatic telecanthus. In this research, 4446 normal Chinese children in Taiwan were enrolled in our study. The sample of 284 full term neonates, 2742 infants and children aged from 1 month to 3 years, and 1420 preschool children were measured for inner canthal distance, outer canthal distance, interpupillary distance and palpebral fissure length. We calculated the mean value and standard deviation of the ocular measurements in normal Chinese newborns, infants and preschool children in Taiwan under 5 years. No significant sex differences were observed. Compared with previous studies, inner canthal distance, outer canthal distance and interpupillary distance in Chinese children in Taiwan were wider than those in Caucasian children, but the palpebral fissure length was not significantly different. We also found that inner canthal distance was wider than palpebral fissure length at the same age; therefore it was not correct to diagnose hypertelorism in Chinese children in Taiwan; as if an imaginary third eye could fit between the eyes. Thus, we suggest that measurements should be adjusted with normal standards specific for race. Consideration of the position of eyes is relevant for the diagnosis of a large number of syndromes.

  12. Three-Dimensional Numerical Simulation on Triaxial Failure Mechanical Behavior of Rock-Like Specimen Containing Two Unparallel Fissures

    NASA Astrophysics Data System (ADS)

    Huang, Yan-Hua; Yang, Sheng-Qi; Zhao, Jian

    2016-12-01

    A three-dimensional particle flow code (PFC3D) was used for a systematic numerical simulation of the strength failure and cracking behavior of rock-like material specimens containing two unparallel fissures under conventional triaxial compression. The micro-parameters of the parallel bond model were first calibrated using the laboratory results of intact specimens and then validated from the experimental results of pre-fissured specimens under triaxial compression. Numerically simulated stress-strain curves, strength and deformation parameters and macro-failure modes of pre-fissured specimens were all in good agreement with the experimental results. The relationship between stress and the micro-crack numbers was summarized. Crack initiation, propagation and coalescence process of pre-fissured specimens were analyzed in detail. Finally, horizontal and vertical cross sections of numerical specimens were derived from PFC3D. A detailed analysis to reveal the internal damage behavior of rock under triaxial compression was carried out. The experimental and simulated results are expected to improve the understanding of the strength failure and cracking behavior of fractured rock under triaxial compression.

  13. Lateral Anal Sphincterotomy for Chronic Anal Fissures- A Comparison of Outcomes and Complications under Local Anaesthesia Versus Spinal Anaesthesia

    PubMed Central

    Jacob, Tarun; Benjamin, Santosh; Kirishnan, Sumonth

    2017-01-01

    Introduction Fissure-in-Ano is one of the common and most painful anorectal conditions encountered in surgical practice. Inspite of several conservative treatment options, surgical treatment in the form of Lateral Anal Spincterotomy (LAS) remains the gold standard of treatment for Chronic Anal Fissures (CAF). However, LAS is often done under spinal or general anaesthesia incurring huge treatment costs and hospital stay. Aim To study if LAS can be treated with Local Anaesthesia (LA) thereby, reducing the costs and the anaesthetic risk to patients with no significant change in the surgical ease or clinical outcome. Materials and Methods A total of 79 patients with chronic fissure underwent randomized allocation to two treatment arms – The first to undergo LAS under LA and the second under Spinal Anaesthesia (SA). The primary outcome variables studied were complications like post-operative pain, infections, healing rate of fissure and incontinence rates. Secondary outcome variables studied were cost, hospital stay and need for additional anaesthetic. Results A total of 79 patients underwent LAS procedure. A total of 42 patients had LA and 39 patients had SA. There was no statistically significant difference in the healing rate, pain, infection and incontinence rates between the two groups. Moreover, the LA group incurred lower cost, reduced hospital stay and reduced risk of anaesthesia. Conclusions LAS can be satisfactorily performed under local anaesthesia with no increased risk of pain or complications, and is best suited for resource-poor surgical settings.

  14. Exploring rock fissures: does a specialized root morphology explain endemism on granite outcrops?

    PubMed Central

    Poot, Pieter; Hopper, Stephen D.; van Diggelen, Josepha M.H.

    2012-01-01

    Background and Aims Worldwide, many plant species are confined to open, shallow-soil, rocky habitats. Although several hypotheses have been proposed to explain this habitat specificity, none has been convincing. We suggest that the high level of endemism on shallow soils is related to the edaphic specialization needed to survive in these often extremely drought-prone habitats. Previous research has shown that species endemic to ironstone communities in SW Australia have a specialized root morphology that enhances their chance to access fissures in the underlying rock. Here we test the generality of these findings for species that are confined to a shallow-soil habitat that is of much greater global significance: granite outcrops. Methods We compared temporal and spatial root growth and allocation of three endemic woody perennials of SW Australian granite outcrop communities with those of congeners occurring on nearby deeper soils. Seedlings of all species were grown in 1·2 m long custom-made containers with a transparent bottom that allowed monitoring of root growth over time. Key Results The granite outcrop endemics mostly differed in a predictable way from their congeners from deeper soils. They generally invested a larger portion of their biomass in roots, distributed their roots faster and more evenly over the container and had a lower specific root length. In different species pairs the outcrop endemics achieved their apparent advantage by a different combination of the aforementioned traits. Conclusions Our results are consistent with earlier work, indicating that species restricted to different types of drought-prone shallow-soil communities have undergone similar selection pressures. Although adaptive in their own habitat in terms of obtaining access to fissures in the underlying rock, these root system traits are likely to be maladaptive in deeper soil habitats. Therefore, our results may provide an explanation for the narrow endemism of many shallow

  15. Stratigraphy and geochronology of pitfall accumulations in caves and fissures, Bermuda

    NASA Astrophysics Data System (ADS)

    Hearty, Paul J.; Olson, Storrs L.; Kaufman, Darrell S.; Edwards, R. Lawrence; Cheng, Hai

    2004-05-01

    Deep fractures ("fissures") and avens ("skylights") in limestone cave roofs create natural traps for sediments and biota. Fissures fill quickly with surface sediment and organisms soon after opening. Debris cones are formed as materials fall, wash, or drift on air through openings in cave skylights. Such deposits in Admiral's and Grand Canyon Cave, Bermuda contain distinct beds and are composed of mixtures of sediment and charcoal, together with fossils of land snails, crabs, birds, reptiles, and bats. The "pitfall" accumulations were periodically sealed over by calcite flowstone. A stratigraphic record of surface activity and fauna through both glacial and interglacial periods has been preserved. The succession also provides an ideal setting in which to compare several geochronological methods. Calibrated 14C ages on charcoal and shells provide dated horizons at 1600, 12,800, and about 35,000 14C yr BP. Thermal ionization mass spectrometric (TIMS) ages on several flowstone layers constrain the entire sequence in the Admiral's Cave sequence between 126,300±900 yr (Termination II) and historical times. A continuous relative-age record generated by amino acid epimerization (AAE) geochronology ( D-alloisoleucine/ L-isoleucine or aIle/Ile) on the pulmonate land gastropod Poecilozonites verifies the biostratigraphy, reveals a minimal degree of mixing between stratigraphic units, and establishes an independent temporal link between the subterranean and subaerial deposits of Bermuda. This convergence between stratigraphy and geochronology yields a precisely dated succession from the oceanic island of Bermuda, and thus presents a unique opportunity to assess the rates and processes of evolutionary and climate change during that interval.

  16. Shift from magmatic to phreatomagmatic explosion controlled by the evolution of lateral fissure eruption in Suoana Crater, Miyakejima

    NASA Astrophysics Data System (ADS)

    Geshi, Nobuo; Nemeth, Karoly; Noguchi, Rina; Oikawa, Teruki

    2016-04-01

    Combined analysis of the proximal deposit and exposed feeder-diatreme structure of the Suoana Crater of Miyakejima reveals the process of magma-water interaction controlled by the evolution of lateral fissure eruption in a stratovolcanic edifice. The Suoana Crater, an oval maar with 400 x 300 m across is one of the craters of the Suoana-Kazahaya crater chain which is formed during a fissure eruption in the 7th Century. The eruption fissure extends ~3 km from the summit area (~700 m asl) to the lower-flank area (~200m asl). The eruption fissure consists of upper maar-chain (>450 m asl) and lower scora-cone chain. As the wall of the 2000 AD caldera truncated at near the center of the Suoana Crater, the vertical section of the feeder dike - diatreme - maar system of the Suoana Crater is exposed in the caldera wall (Geshi et al., 2011). The ejected materials from the Suoana crater indicate the transition of eruption style from magmatic to phreatomagmatic. The juvenile clasts in the lower half of the deposit exhibit spatter-like shape, indicating the typical deposit from a vigorous fire fountain. Contrary, the juvenile clasts in the upper half are less vesiculated and exhibit cauliflower-shape, indicating the typical phreatomagmatic activity. This transition indicates that the magma-water interaction started at the middle of the eruption. Judging from the ratio of the thickness of the lower and upper parts, the contrast of the content of juvenile clasts, and bulk density of the deposit, the total ejected volume of magma is larger in the lower part compare to the upper part. The transition from magmatic to phreatomagmatic occurred only in the upper half of the eruption fissure, including the Suoana crater, whereas the lower half of the fissure continued dry magmatic eruption throughout their activity. The limited distribution of phreatomagmatic activity can be resulted by the magma extraction from the upper feeder dike system to the lower eruption fissure as it

  17. Analysis of displacements and fissure structures on a slow-moving landslide through very high-resolution orthophoto mosaicing

    NASA Astrophysics Data System (ADS)

    Rothmund, Sabrina; Joswig, Manfred; Niethammer, Uwe; Malet, Jean-Philippe

    2010-05-01

    Very high-resolution multi-temporal images with a ground resolution of a few centimeters allowed to detect and analyze displacements and fissure patterns of the Super-Sauze landslide (Southern French Alps). Images taken by an unmanned aerial vehicle (UAV) during a flight campaign in October 2008 have been used to produce a very high-resolution orthophoto-mosaic of the landslide. In this study, a set of 59 of a total of 1486 images was selected and photogrammetrically processed using different non-parametric rectification approaches (projective transformation, piecewise affine transformation and polynomial transformations of the second and third order). The generated orthophoto-mosaic covers the entire landslide area of 0.09 km² with a ground resolution of 3 to 8 cm. The comparison of this UAV-based orthophoto-mosaic with an orthophotograph from May 2007 (ground resolution of 20 cm) allowed the characterization of the horizontal displacements of the landslide. Displacement vectors were estimated by visually inspecting the images to identify distinct features (rocks, boulders and vegetation patches) in the two orthophotographs. This approach was chosen because of the high dynamics of the landslide and the disadvantageous long period between the repeated image acquisitions. Displacements between 7.1 and 55.4 m in varying directions have been detected and areas of different dynamics could be distinguished for the period between May 2007 and October 2008. Various structures, in particular fissures of different distributions and orientations, could be resolved in the UAV-based orthophoto-mosaic. The similarity of the observed fissures with glacial crevasses is striking and suggests a similar genesis. The identified longitudinal, transverse and cross-shaped fissures are linked to abrupt changes of in-situ crest orientation in the shallow subsurface. The observed shear fissures occur at the lateral boundary of emerging in-situ crests. The fissure genesis could be traced

  18. Subsurface Gas Flow and Ice Grain Acceleration within Enceladus and Europa Fissures: 2D DSMC Models

    NASA Astrophysics Data System (ADS)

    Tucker, O. J.; Combi, M. R.; Tenishev, V.

    2014-12-01

    The ejection of material from geysers is a ubiquitous occurrence on outer solar system bodies. Water vapor plumes have been observed emanating from the southern hemispheres of Enceladus and Europa (Hansen et al. 2011, Roth et al. 2014), and N2plumes carrying ice and ark particles on Triton (Soderblom et al. 2009). The gas and ice grain distributions in the Enceladus plume depend on the subsurface gas properties and the geometry of the fissures e.g., (Schmidt et al. 2008, Ingersoll et al. 2010). Of course the fissures can have complex geometries due to tidal stresses, melting, freezing etc., but directly sampled and inferred gas and grain properties for the plume (source rate, bulk velocity, terminal grain velocity) can be used to provide a basis to constrain characteristic dimensions of vent width and depth. We used a 2-dimensional Direct Simulation Monte Carlo (DSMC) technique to model venting from both axi-symmetric canyons with widths ~2 km and narrow jets with widths ~15-40 m. For all of our vent geometries, considered the water vapor source rates (1027­ - 1028 s-1) and bulk gas velocities (~330 - 670 m/s) obtained at the surface were consistent with inferred values obtained by fits of the data for the plume densities (1026 - 1028 s-1, 250 - 1000 m/s) respectively. However, when using the resulting DSMC gas distribution for the canyon geometries to integrate the trajectories of ice grains we found it insufficient to accelerate submicron ice grains to Enceladus' escape speed. On the other hand, the gas distributions in the jet like vents accelerated grains > 10 μm significantly above Enceladus' escape speed. It has been suggested that micron-sized grains are ejected from the vents with speeds comparable to the Enceladus escape speed. Here we report on these results including comparisons to results obtained from 1D models as well as discuss the implications of our plume model results. We also show preliminary results for similar considerations applied to Europa

  19. Influence of Laser Irradiation on Pits and Fissures: An In Situ Study

    PubMed Central

    Correa–Afonso, Alessandra M; Pécora, Jesus D

    2013-01-01

    Abstract Objective: The aim of this in situ study was to analyze the influence of the Er:YAG, Nd:YAG, and CO2 lasers on the enamel acid resistance of pits and fissures. Background data: The laser tissue interaction has been studied as a method of preventing occlusal caries. Methods: Thirteen volunteers wore palatal acrylic appliances containing human occlusal enamel blocks that were divided into four groups (G1, control; G2, Er:YAG; G3, Nd:YAG; G4, CO2). Each palatal acrylic appliance was used in the four studied groups and was used for 14 consecutive days. A sucrose solution was applied to the specimens six times per day. The specimens were then sectioned in half, and a microhardness test was applied. The other halves were analyzed using polarized light microscopy to measure the caries-like lesion areas, and a morphological analysis was conducted using a scanning electron microscope (SEM). Results: For the statistical analysis of the data obtained from the microhardness test (Knoop hardness number. [KHN]) (α=5%), Fisher's exact test was performed, and the group means were as follows: G1, 247±71; G2, 258±70; G3, 272±73; and G4, 298±56. The results demonstrated that the control group was significantly different from G3 and G4, which presented higher microhardness values. The Wilcoxon signed-rank test was used to analyze the data obtained from the caries-lesion area measurements (mm2) (α=5%) (G1, 0.01±1.08; G2, 0.13±0.18; G3, 0.05±0.17; and G4, 0.09±0.22). The results no showed significant differences among the groups in this analysis. Conclusions: Based on the results from the present study, it may be concluded that the CO2 and Nd:YAG lasers increased the enamel acid resistance in pits and fissures. PMID:23336742

  20. Hemorrhoids, anal fissure, and carcinoma of the colon, rectum, and anus during pregnancy.

    PubMed

    Medich, D S; Fazio, V W

    1995-02-01

    The pregnant patient afflicted with a variety of colorectal conditions merits special consideration for reasons related to the safety and timeliness of operation while preserving fetal viability and fertility. The literature is scanty with respect to hemorrhoids, fissures, and colorectal and anal carcinoma. Therefore, the patient has to have a forthright discussion with her physician(s) about the pros and cons of operative and nonoperative approaches, which can result in either therapeutic abortion and timely surgery versus preserving the fetus and taking on the unknown factor of whether delay in treatment will cause an adverse outcome. This underscores the need for a frank discussion with the patient with regard to anticipated outcomes. In benign conditions, there is more latitude to adopt a conservative approach, as the patient's ability to tolerate the symptoms of her condition would dictate the need for definitive operative therapy. In the patient with malignancy, delaying surgical or radiation therapy carries an unknown risk to the patient. Here, the patient's personal views regarding abortion and future fertility dictate the timing of definitive treatment.

  1. Evaluation of a fissure sealant program as part of community-based teaching and training.

    PubMed

    van Wyk, Philippus J; Kroon, Jeroen; White, John G

    2004-01-01

    Since 1995 the Department of Community Dentistry of the University of Pretoria has been involved in the rendering of mobile primary oral health care services to children in the Hammanskraal area of Gauteng, South Africa, as part of their students' community-based training. Mokonyama Primary School was identified as the first school where a primary oral health care service could be rendered. The objective of this study was to evaluate the impact (outcomes) of a fissure sealant program on the dentition status of the school children. Seven years after the implementation of the program, the dentition status of children at Mokonyama was compared with that of a comparable group of children from the same area who were not exposed to the program. The results showed that the decayed, missing, and filled teeth in the primary dentition (dmft) in the six-year-old group in Mokonyama (1.74) did not differ significantly from the dmft (1.43) of the control group (p = 0.49). The decayed, missing, and filled teeth in the permanent dentition (DMFT) of 0.59 for the fifteen-year-old group in Mokonyama, however, differed significantly (p = 0.0001) from the DMFT of the control group (2.38). Fifteen-year-old children in Mokonyama had 75.2 percent fewer caries than their counterparts in the control group.

  2. Evidence for Bacterial Sulfate Reduction in a Fissured-porous Karst System in Southern Germany

    NASA Astrophysics Data System (ADS)

    Einsiedl, F.; Mayer, B.

    2005-12-01

    Twenty five percent of the world's population uses karst water as drinking water resources. Since karst groundwater systems are highly vulnerable to contamination, groundwater protection and self purification is a major challenge. Up to now research in karst groundwater systems has predominantly concentrated on hydrodynamic processes. Little is known about anoxic processes in oxygen dominated, fracture-matrix diffusion controlled karst aquifers. Isotope measurements comprise a promising tool to identify biogeochemical processes such as bacterial (dissimilatory) sulfate reduction in karstic aquifers. The goal of this study was to determine the sources and the processes affecting sulfate in an oxygen-rich karst aquifer in southern Germany and their dependence on hydrogeological parameters. This was achieved by interpreting tritium data with a simple lumped parameter approach and assessing variations in concentrations and isotopic compositions of sulfate and dissolved inorganic carbon (DIC) with respect to groundwater age. Young groundwater (<30 years) was characterized by comparatively high sulfate concentrations (0.36 mM) and δ34S values similar to those of recent atmospheric deposition (1.5‰). In contrast groundwater with mean residence times >60 years had significantly lower sulfate concentrations (0.08 mM) and markedly higher δ34S values (7.5‰). These results indicate that in karst systems with matrix porosity, bacterial (dissimilatory) sulfate reduction may occur. This process has the potential to contribute to long-term biodegradation of contaminants in the porous rock matrix representing the dominant water reservoir in fissured-porous karst aquifers.

  3. Analysis of anticaries potential of pit and fissures sealants containing amorphous calcium phosphate using synchrotron microtomography.

    PubMed

    Delben, A C B; Cannon, M; Vieira, A E M; Basso, M D; Danelon, M; Santo, M R E; Stock, S R; Xiao, X; De Carlo, F

    2015-01-01

    The aim of this study was to analyze the anticaries potential of pit and fissure sealants containing amorphous calcium phosphate (ACP) by synchrotron microtomography. Bovine enamel blocks (4×4 mm; n=50) were selected through surface hardness (Knoop) analysis. Slabs were obtained through cross-sections taken 1 mm from the border of the enamel. Five indentations, spaced 100 μm apart, were made 300 μm from the border. Ten specimens were prepared for each tested material (Ultraseal XT plus TM, Aegis, Embrace, Vitremer and Experimental Sealant). The materials were randomly attached to the sectioned surfaces of the enamel blocks and fixed with sticky wax. The specimens were submitted to pH cycling. After that, the surface hardness (SH1) was determined, and the blocks were submitted to synchrotron microcomputed tomography analysis to calculate the mineral concentration (ΔgHAp cm(-3)) at different areas of the enamel. The comparison between the SH1 and ΔgHAp cm(-3) showed a correlation for all groups (r=0.840; p<0.001). The fluoride groups presented positive values of ΔgHAp cm(-3), indicating a mineral gain that was observed mainly in the outer part of the enamel. The ACP showed mineral loss in the outer enamel compared with fluoride groups, although it inhibited the demineralization in the deeper areas of enamel. The combination of two remineralizing agents (fluoride and ACP) was highly effective in preventing demineralization.

  4. Assessment of effectiveness of geologic isolation systems. Analytic modeling of flow in a permeable fissured medium

    SciTech Connect

    Strack, O.D.L.

    1982-02-01

    An analytic model has been developed for two dimensional steady flow through infinite fissured porous media, and is implemented in a computer program. The model is the first, and major, step toward the development of a model with finite boundaries, intended for use as a tool for numerical experiments. These experiments may serve to verify some of the simplifying assumptions made in continuum models and to gain insight in the mechanics of the flow. The model is formulated in terms of complex variables and the analytic functions presented are closed-form expressions obtained from singular Cauchy integrals. An exact solution is given for the case of a single crack in an infinite porous medium. The exact solution is compared with the result obtained by the use of an independent method, which assumes Darcian flow in the crack and models the crack as an inhomogeneity in the permeability, in order to verify the simplifying assumptions. The approximate model is compared with solutions obtained from the above independent method for some cases of intersecting cracks. The agreement is good, provided that a sufficient number of elements are used to model the cracks.

  5. Sylvian Fissure and Parietal Anatomy in Children with Autism Spectrum Disorder

    PubMed Central

    Knaus, Tracey A.; Tager-Flusberg, Helen; Foundas, Anne L.

    2012-01-01

    Autism spectrum disorder (ASD) is characterized by deficits in social functioning and language and communication, with restricted interests or stereotyped behaviors. Anatomical differences have been found in the parietal cortex in children with ASD, but parietal subregions and associations between Sylvian fissure (SF) and parietal anatomy have not been explored. In this study, SF length and anterior and posterior parietal volumes were measured on MRI in 30 right-handed boys with ASD and 30 right-handed typically developing boys (7–14 years), matched on age and non-verbal IQ. There was leftward SF and anterior parietal asymmetry, and rightward posterior parietal asymmetry, across groups. There were associations between SF and parietal asymmetries, with slight group differences. Typical SF asymmetry was associated with typical anterior and posterior parietal asymmetry, in both groups. In the atypical SF asymmetry group, controls had atypical parietal asymmetry, whereas in ASD there were more equal numbers of individuals with typical as atypical anterior parietal asymmetry. We did not find significant anatomical-behavioral associations. Our findings of more individuals in the ASD group having a dissociation between cortical asymmetries warrants further investigation of these subgroups and emphasizes the importance of investigating anatomical relationships in addition to group differences in individual regions. PMID:22713374

  6. Shear bond strength and microleakage of a self-etching adhesive for fissure sealing after different types of aging.

    PubMed

    Schuldt, Christoph; Birlbauer, Sebastian; Pitchika, Vinay; Crispin, Alexander; Hickel, Reinhard; Kühnisch, Jan

    2016-01-01

    The aim of this study was to evaluate shear bond strength (SBS) and microleakage of a self-etching adhesive (Adper Prompt L-Pop) in comparison to acid etching prior fissure sealing. Each procedure was tested with 3 aging procedures (1-day water storage, 3-month water storage and 1-day water storage/5,000× thermocycling). SBS was determined according to ISO standard 29022. Additional 30 third molars were utilized for the microleakage analyses. Data were analyzed using Mann-Whitney-U-Test and multiple linear regression models. The SBS of the self-etching adhesive were significantly lower (14.9, 11.9, and 13.0 MPa) than those of conventional fissure sealing (19.1, 18.2, and 15.6 MPa). Multiple linear regression models predicted that material and alteration significantly influenced SBS. The microleakage revealed no difference between both groups (1.3% vs. 1.2%). It can be concluded that the selfetching adhesive might be a pre-treatment alternative for fissure sealing in terms of the easier and shorter clinical workflow.

  7. Cellular resolution optical access to brain regions in fissures: imaging medial prefrontal cortex and grid cells in entorhinal cortex.

    PubMed

    Low, Ryan J; Gu, Yi; Tank, David W

    2014-12-30

    In vivo two-photon microscopy provides the foundation for an array of powerful techniques for optically measuring and perturbing neural circuits. However, challenging tissue properties and geometry have prevented high-resolution optical access to regions situated within deep fissures. These regions include the medial prefrontal and medial entorhinal cortex (mPFC and MEC), which are of broad scientific and clinical interest. Here, we present a method for in vivo, subcellular resolution optical access to the mPFC and MEC using microprisms inserted into the fissures. We chronically imaged the mPFC and MEC in mice running on a spherical treadmill, using two-photon laser-scanning microscopy and genetically encoded calcium indicators to measure network activity. In the MEC, we imaged grid cells, a widely studied cell type essential to memory and spatial information processing. These cells exhibited spatially modulated activity during navigation in a virtual reality environment. This method should be extendable to other brain regions situated within deep fissures, and opens up these regions for study at cellular resolution in behaving animals using a rapidly expanding palette of optical tools for perturbing and measuring network structure and function.

  8. Effect of topical applications of a chlorhexidine/thymol-containing varnish on fissure caries assessed by laser fluorescence.

    PubMed

    Sköld-Larsson, Kerstin; Fornell, Ann-Charlott; Lussi, Adrian; Twetman, Svante

    2004-12-01

    The aim of this study was to monitor the effect of an antibacterial varnish using the readings of a caries-detecting device (DIAGNOdent) in fissures of young permanent molars. The material consisted of 32 healthy patients with a mean age of 14.1 years undergoing orthodontic treatment with fixed appliances. The inclusion criteria were presence of one homologous pair of 2nd upper or lower molars with clinically intact occlusal surfaces. A split-mouth study design was used in which the fissures were treated with either an antibacterial chlorhexidine/thymol-containing varnish or a placebo varnish every 6th week. The follow-up period was 42 weeks and laser fluorescence (LF) readings were carried out every 12th week. The mean LF values increased significantly (P < 0.05) after 24, 36, and 48 weeks compared to baseline following the placebo treatments but not after treatment with the active antibacterial varnish. During the study period, micro-cavities were diagnosed in two test-treated and five placebo-treated teeth. In conclusion, the results reinforce previous findings that frequent applications of a chlorhexidine/thymol-containing dental varnish might have a protective role in fissures of young permanent molars and that this could be monitored with a chair-side caries detecting LF device.

  9. Feasibility and safety of prophylactic tentorium cerebelli hiatus incision in surgery of glioma located in lateral fissure area

    PubMed Central

    Jin’an, Zhao; Yamei, Gao; Huanli, Yang

    2015-01-01

    To discuss the feasibility and safety of prophylactic tentorium cerebelli hiatus incision in surgery of glioma located in lateral fissure area. There were 80 patients with glioma located in lateral fissure area who received treatment from May 2012 to May 2015, divided into two groups, the research group (n=40) and control group (n=40), and then statistical analysis was carried out. Difference in total resection rate and subtotal resection rate of glioma between patients of the research group and those of the control group was not significant (P>0.05); intracranial pressure of patients in the research group was significantly lower than that of control group (P<0.05), their hospital stay was significantly shorter than that of the control group (P<0.05), times of using mannitol were significantly fewer than control group (P<0.05), but the differences of acute renal function damage and second surgery occurrence rate between patients of the two groups were not significant (P>0.05). Prophylactic tentorium cerebelli hiatus incision in surgery of glioma located in lateral fissure area can effectively reduce patients’ intracranial pressure, shorten patients’ hospital stay and reduce patients’ times of using mannitol without increasing the rate of patients’ acute renal function damage and second surgery.

  10. Morphologic Study of Superior Temporal Sulcus-Amygdaloid Body and Lateral Fissure-Amygdaloid Body Surgical Approach by Using Magnetic Resonance Imaging Volume Rendering.

    PubMed

    Qu, Yuan; Ren, Bichen; Chang, Xiaoyu; Zhang, Jinnan; Li, Youqiong; Duan, Haobo; Cheng, Kailiang; Wang, Jincheng

    2016-01-01

    In this research, 83 patients were measured by magnetic resonance imaging volume rendering technique. The authors acquired the curve length of the superior temporal sulcus and the lateral fissure on the cerebral hemisphere, the shortest distance from the superior temporal sulcus and the lateral fissure to the center of amygdaloid body separately, the vertical diameter, the transversal diameter, and the anteroposterior diameter of the amygdaloid body and the 2 approach angles between the median sagittal plane and the shortest segment from the superior temporal sulcus to the center of amygdaloid body and the shortest segment from lateral fissure to the center of the amygdaloid body. At the same time, we preliminarily oriented the 2 points of the superior temporal sulcus and the lateral fissure, which are closest to the center of amygdaloid body, aimed at finding out the best entrance points of surgical approach through the superior temporal sulcus and the lateral fissure to the amygdaloid body and reducing the damage to the nerve fibers or blood vessels during the operation. The results indicate that the point at the front side 1/4 of the superior temporal sulcus may be the ideal surgical approach entrance point and the point at the front side 1/3 of the lateral fissure. There is no difference between 2 cerebral hemispheres (P < 0.05).

  11. Drivers of explosivity and elevated hazard in basaltic fissure eruptions: The 1913 eruption of Ambrym Volcano, Vanuatu (SW-Pacific)

    NASA Astrophysics Data System (ADS)

    Németh, Károly; Cronin, Shane J.

    2011-04-01

    Fissure-eruptions along linear structures can extend for several tens of kilometres with distinct separate manifestations of volcanism along their length. They typically involve low-viscosity mafic magmas forming long lava flows and cinder cones. Eruptions in 1894 and 1913 on Ambrym volcano, Vanuatu, showed how these mildly explosive eruptions can rapidly transform into violent explosive events, producing significant hazard and widespread volcanic ash clouds. During the 1913 episode, a fissure began in the central caldera and basaltic magmas broke out in a series of locations down the island's western flank. In all sites over 100 m in elevation, fissure outbreaks produced vigorous lava fountains and highly fluid lava flows that travelled rapidly to the shoreline. When the outbreaks propagated along the island's axis into coastal plain areas, a climactic series of explosive eruptions occurred, producing a 1.2 km long by 600 m wide maar and tephra ring. A further small tuff ring was formed later, creating a temporary island 400 m offshore. The onshore tephra ring destroyed a hospital and associated buildings. Its last evacuating occupants were close witnesses to the eruption processes. Deposits exposed in the lower portion of the tephra ring show that this part of the eruption began with a mild phreatomagmatic explosive eruption from a narrow vent, followed by a magmatic scoria-producing phase. Subsequently a complex sequence of highly explosive phreatomagmatic eruptions occurred, producing pyroclastic surges, along with repeated distinctive breccia-horizons, rich in coral and lava country rock. These features tally with eye-witness accounts to indicate that the main eruption phase was produced by a periodically shifting locus of phreatomagmatic fragmentation and eruption along a single E-W fissure. The glassy and vesicle-poor pyroclasts produced during this eruption phase were dominantly fragmented in a brittle manner by magma water interaction. Low volatile content

  12. Recrystallized Granite Surface Fissures Of The Wasatch Range, Produced Not Later Than 1/4 Billion Years Ago

    NASA Astrophysics Data System (ADS)

    McDonald, Keith L.

    2000-05-01

    Our studies of numerous recrystallized fissures in 4 granite plutons of Wasatch Range, namely, Mount Tuscarora-Wolverine-Millicent,^1,6,7 Bonanza Peak-Midway,^2 Little Cottonwood Canyon and Ferguson Canyon plutons, all of which formed magma chambers reaching Earth-atmosphere interface, establish that they resulted from high thermal gradients rather than passages of earthquake waves. Magma chambers formed, solidified during Permo-Caroniferous Ice Age(roughly, 1/3...1/4 billion yr ago, a time interval preceding period of extrusion of Rocky Mountains, 10^8 yr ago), and while fluid, belched lava flows^5 extending over its reservoir walls to run hundred of meters. We have shown how the magma melts, dilutes and replaces overlying metamorphic rock^7 to reach Earth's surface so that a pluton containing large amounts of dross(Fe-ores, etc.) had a short fluid lifetime. We also described how offshoots from a long-running main fissure form acute angles with that fissure.^3 Such recrystallized fissures, reaching depths of perhaps 100 m, have initial fractures near time of solidification of their uppermost portion of magma chamber while still hot(<= 1600^oF), a time when max. stresses occur near granite surface due to high thermal gradients, owing to snow coverage, cold water contacts due to rain, stream flow over granite surface, partial coverage by ocean, etc., wherever heat sinks might occur, during P-C ice age--when region of Wasatch Range existed at sea level, Salt Lake Valley being covered entirely by ocean water and region east of Wasatch Bouleuard rising gently above Pacific Ocean to elevations of possibly 500-1000 ft, say, at a distance of 10-15 mi to east. This fact is implied by Chinese Wall of white limestone on Grandeur Peak, unequivocally, and similarly another in Neff's Canyon running e. from n. ridge of 9200 ft. saddle-summit, as well as a dozen other ancient calcified stream beds emptying into ocean to w., in Salt Lake Valley. This existed prior to regional

  13. Identification of possible recent water/lava source fissures in the Cerberus Plains: stratigraphic and crater count age constraints

    NASA Astrophysics Data System (ADS)

    Thomas, Rebecca J.

    2013-04-01

    The Cerberus plains are one of the youngest surfaces on Mars. They are thought to have been formed by lava and/or water flows, but there is considerable debate regarding the source of this material. Much of the material forming the western plains, including the Athabasca Valles outflow channels, appears to have flowed from the region of the Cerberus Fossae graben system [1,2,3] and limited areas forming the eastern plains may have been erupted by low shield volcanoes [4,5]. However, flow of material from west to east is obstructed by a ridge centred on 157°E, 7°N and, prior to this study, vents which might be the source of fluid of a low enough viscosity to form the majority of the flat eastern plains had not been identified. We studied new HiRISE (25cm/px, High Resolution Science Imaging Experiment) images of the ridge between the east and west plains and observed possible source vents for this material: the ridge is cut by a series of pits and fissures which lie at the heads of flows and channels extending towards the surrounding plains. In order to establish the stratigraphic relationships between the vents and plains, this study produced large scale geomorphological maps based on the HiRISE images. The mapping showed that both incised channels and leveed flows extend onto the plain to the south of the ridge and that these were the final phase of plains-forming activity in that region. Conversely, to the north, ridge-sourced deposits only form the plains surface close to the ridge - beyond that, they are overlain by large-scale regional flows that appear to have originated from the direction of Athabasca Valles. In the southeast, a large-scale flow which does not emanate from this ridge forms the plains surface, but there is evidence that the youngest outflow activity from the ridge was contemporaneous with emplacement of this unit. We also performed crater counts to age-date the surfaces and these indicate that plains-forming and ridge-sourced units are of a

  14. Characterisation and microleakage of a new hydrophilic fissure sealant - UltraSeal XT® hydro™

    PubMed Central

    GÜÇLÜ, Zeynep A.; DÖNMEZ, Nazmiye; HURT, Andrew P.; COLEMAN, Nichola J.

    2016-01-01

    ABSTRACT Objectives The aim of this study was to characterise the new hydrophilic fissure sealant, UltraSeal XT® hydro™ (Ultradent Products, USA), and to investigate its in vitro resistance to microleakage after placement on conventionally acid etched and sequentially lased and acid etched molars. Material and Methods The sealant was characterised by Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Vickers indentation test. Occlusal surfaces of extracted human molars were either conventionally acid etched (n=10), or sequentially acid etched and laser irradiated (n=10). UltraSeal XT® hydro™ was applied to both groups of teeth which were then subjected to 2,500 thermocycles between 5 and 55°C prior to microleakage assessment by fuchsin dye penetration. Results UltraSeal XT® hydro™ is an acrylate-based sealant that achieved a degree of conversion of 50.6±2.2% and a Vickers microhardness of 24.2±1.5 under standard light curing (1,000 mWcm-2 for 20 s). Fluoride ion release is negligible within a 14-day period. SEM and EDX analyses indicated that the sealant comprises irregular submicron and nano-sized silicon-, barium-, and aluminium-bearing filler phases embedded in a ductile matrix. Laser preconditioning was found to significantly reduce microleakage (Mann-Whitney U test, p<0.001). The lased teeth presented enhanced surface roughness on a 50 to 100 μm scale that caused the segregation and concentration of the filler particles at the enamel-sealant interface. Conclusion Laser preconditioning significantly decreased microleakage and increased enamel surface roughness, which caused zoning of the filler particles at the enamel-sealant interface. PMID:27556205

  15. Measurements of the gas emission from Holuhraun volcanic fissure eruption on Iceland, using Scanning DOAS instruments

    NASA Astrophysics Data System (ADS)

    Galle, Bo; Pfeffer, Melissa; Arellano, Santiago; Bergsson, Baldur; Conde, Vladimir; Barsotti, Sara; Stefansdottir, Gerdur; Ingvarsson, Thorgils; Bergsson, Bergur; Weber, Konradin

    2016-04-01

    On 31 August 2014 a volcanic fissure eruption started at Holuhraun on Iceland. The eruption lasted for 6 months and was by far the strongest source of sulfur dioxide in Europe over the last 230 years, with sustained emission rates exceeding 100 000 ton/day. This gas emission severely affected people within Iceland. Under the scope of the EU-project FUTUREVOLC, a project with 3.5 years duration, aiming at making Iceland a supersite for volcanological research as a European contribution to GEO, a version of the Scanning DOAS instrument that is adapted to high latitudes with low UV radiation and severe meteorological conditions was developed. Since the first day of the eruption several of these novel instruments were monitoring the SO2 emission from the eruption. A lot of work was needed to sustain this operation during the winter at a very remote site and under severe field conditions. At the same time the very high concentrations in the gas plume, in combination with bad meteorological conditions has required the development of novel methods to derive reliable flux estimates. A simple approach to make a first order correction for atmospheric scattering has been applied, as well as filtering of the dataset to remove the data most affected by scattering. Substantial work has also been made to obtain realistic information on plume height and wind speed. The data from these instruments are the only sustained ground-based measurements of this important gas emission event. In this presentation we will discuss the instrumental issues and evaluation procedures and present the latest version of the emission estimates made from our measurements.

  16. [Epidemiology of anal lesions (fissure and thrombosed external hemorroid) during pregnancy and post-partum].

    PubMed

    Abramowitz, L; Batallan, A

    2003-06-01

    Thrombosed external hemorrhoids (TEH) and anal fissure (AF) are 2 frequent sources of anal pains during childbirth. We are going to define their incidences as available in publications and in our experience in Bichat hospital. Then we will define their risk factors. According to Martin's and Corby's studies, AF was observed in 10% of the delivered women. In Bichat hospital we performed a proctological assessment to 165 pregnant women during the last third of pregnancy and within the 2 months following delivery. We observed 2 AF (1,2%) during the first period and 25 (15,2%) during the second. Rouillon et al. reported an incidence of TEH in 12,2% (20/164), while Pradel and al. reported 34% (18/52) of it. In Bichat hospital, 13 women (7,9%) were presenting with TEH during the last third of pregnancy and 33 (20%) in post-partum period. Two studies looked for a statistical correlation between AF and obstetrical, foetal or maternal factors. Corby et al. only pointed the role of constipation. In our study, terminal constipation was the most important risk factor for AF with 5.7 (2.7-12), odds ratio (95% confidence intervals). Rouillon et al. observed more TEH among women with a prolonged first stage labor and a big baby. In our study, a big baby and mother little lips tears were observed more often among women with TEH (P <0,05). Also, we observed only one TEH among the 25 women with caesarean section (4%). Finally, observation that TEH arise immediately after delivery is another argument to support the role of traumatic delivery. We also demonstrated the role of terminal constipation as risk factor for TEH after delivery. To conclude, 1/3 of pregnant women develop AF or TEH after delivery. These 2 pathologies are strongly correlated to terminal constipation. TEH seems equally furthered by traumatic delivery.

  17. Earth-Fissure Movements Associated with Fluctuations in Ground-Water Levels near the Picacho Mountains, South-Central Arizona, 1980-84

    USGS Publications Warehouse

    Carpenter, M.C.

    1993-01-01

    The Picacho earth fissure transects subsiding alluvial sediments near the east periphery of the Picacho basin in south-central Arizona. The basin has undergone land subsidence of as much as 3.8 meters since the 1930's owing to compaction of the aquifer system in response to ground-water-Ievel declines that have exceeded 100 meters. The fissure, which extends generally north-south for 15 kilometers, exhibits horizontal tensile failure and as much as 0.6 meter of normal dip-slip movement at the land surface. The west side of the fissure is down thrown. The fissure was observed as early as 1927 and is the longest earth fissure in Arizona. Vertical and horizontal displacements were monitored along a line normal to the fissure. The survey line extends from a bedrock outcrop in the Picacho Mountains on the east, past an observation well near the fissure, to a point 1,422 meters to the west. From May 1980 to May 1984, the downthrown west side of the fissure subsided 167+-1.8 millimeters and moved 18+-1.5 millimeters westward into the basin. Concurrently, the relatively upthrown east side subsided 148+-1.8 millimeters and moved 14+-1.5 millimeters westward. Dislocation modeling of deformation along the survey line near the fissure indicates that dip-slip movement has occurred along a vertical fault surface that extends from the land surface to a depth of about 300 meters. Slip was 9 millimeters from May to December 1980 and also 9 millimeters from March to November 1981. Continuous measurements were made of horizontal movement across the fissure using a buried invar-wire horizontal extensometer, while water-level fluctuations were continuously monitored in four piezometers nested in two observation wells. The range of horizontal movement was 4.620 millimeters, and the range of water-level fluctuation in the nearest piezometer in the deep alluvium was 9.05 meters. The maximum annual opening of the fissure during the study period was 3.740 millimeters from March to October

  18. (Micro)morphological, inorganic-organic isotope geochemisty and microbial populations in endostromatolites (cf. fissure calcretes), Haughton impact structure, Devon Island, Canada: The influence of geochemical pathways on the preservation of isotope biomarkers

    NASA Astrophysics Data System (ADS)

    Lacelle, Denis; Pellerin, André; Clark, Ian D.; Lauriol, Bernard; Fortin, Danielle

    2009-05-01

    Endostromatolites (cf. fissure calcretes), which possess microbial evidence for a biogenic origin, are also thought to preserve isotopic biosignatures. In this study, a multi-proxy approach combining (micro)morphological, geochemical and isotopic analyses of middle Holocene age endostromatolites within sub-horizontal fissures in dolomitic limestone outcrops in the Haughton impact crater region (Devon Island, NU) was used to determine their origin (abiotic versus biogenic) and to identify potential isotope biosignatures. The micro-morphologies of the endostromatolites revealed some structures typical of a physico-chemical origin, whereas the presence of rod-shape particles and filamentous structures was more reminiscent of biologically-induced forms. The endostromatolites have δ13C and δ18O compositions reaching maximum values of 7.2‰ and - 11.2‰, respectively. Positive relations between the elemental (Mg, Sr) and isotopic ( δ18O and δ13C) composition of the endostromatolites are indicative of an evaporative enrichment process of the meteoric water infiltrating the fissures prior to calcite precipitation. However, the positive δ13C TOC- δ13C CaCO3 relation in the endostromatolites is strongly indicative that they were microbially-mediated. In support of a microbial origin, mostly aerobic heterotrophic bacteria that have been linked to both carbonate dissolution and mineralization were observed in the microbial diversity of the endostromatolites. However, the results are inconclusive to attribute the formation of the endostromatolites solely to a biologically-induced mineralization, but instead, favor a more complex origin that involved abiotic (evaporation), and to some extent, biological processes prior to and during calcite precipitation. Considering that the endostromatolites result from microbially-influenced mineralization, the effects of physico-chemical processes on the geochemical and isotopic composition of the endostromatolites were much greater

  19. Origins of Feeding Arteries of Hepatocellular Carcinoma Located Near the Umbilical Fissure of the Left Hepatic Lobe: Angiographic Evaluation

    SciTech Connect

    Miyayama, Shiro Yamashiro, Masashi; Shibata, Yoshihiro; Hashimoto, Masahiro; Yoshida, Miki; Tsuji, Kazunobu; Toshima, Fumihito; Matsui, Osamu

    2012-12-15

    Purpose: To analyze the origins of the feeding arteries of hepatocellular carcinomas (HCCs) near the umbilical fissure of the left hepatic lobe. Methods: Twenty-eight HCCs with a mean {+-} SD tumor diameter of 3.4 {+-} 1.0 cm (range 1-4.4 cm) in contact with the right or left side of the umbilical fissure were treated by superselective transcatheter arterial chemoembolization (TACE). The origins of the tumor-feeding arteries were analyzed with arteriograms and computed tomography or cone-beam computed tomography images obtained during and 1 week after TACE.ResultsTwenty-one HCC lesions were located in segment 3 and seven were located in segment 4. Of 21 tumors in segment 3, 13 (61.9%) were supplied by the lateral inferior subsegmental artery (A3), three (14.3%) by the medial subsegmental artery (A4), three (14.3%) by both A4 and A3, one (4.8%) by a branch arising from the left lateral hepatic artery, and one (4.8%) by a branch of the right gastric artery. In particular, all tumor-feeding branches arising from A4 were the first branch of A4. Of seven tumors in segment 4, four (57.1%) were supplied by A4 and three (42.9%) by A3. In particular, all tumor-feeding branches arising from A3 were the first branch of A3. Conclusion: This study demonstrates crossover blood supply to HCC lesions located near the umbilical fissure, in addition to direct feeding from a separate branch. In particular, the first branch of the opposite subsegmental artery may feed tumors when crossover blood supply is present.

  20. Chemical transport in a fissured rock: Verification of a numerical model

    SciTech Connect

    Rasmuson, A.; Narasimhan, T. N.; Neretnieks, I.

    1982-10-01

    Numerical models for simulating chemical transport in fissured rocks constitute powerful tools for evaluating the acceptability of geological nuclear waste repositories. Due to the very long-term, high toxicity of some nuclear waste products, the models are required to predict, in certain cases, the spatial and temporal distribution of chemical concentration less than 0.001% of the concentration released from the repository. Whether numerical models can provide such accuracies is a major question addressed in the present work. To this end, we have verified a numerical model, TRUMP, which solves the advective diffusion equation in general three dimensions with or without decay and source terms. The method is based on an integrated finite-difference approach. The model was verified against known analytic solution of the one-dimensional advection-diffusion problem as well as the problem of advection-diffusion in a system of parallel fractures separated by spherical particles. The studies show that as long as the magnitude of advectance is equal to or less than that of conductance for the closed surface bounding any volume element in the region (that is, numerical Peclet number <2), the numerical method can indeed match the analytic solution within errors of ±10{sup -3} % or less. The realistic input parameters used in the sample calculations suggest that such a range of Peclet numbers is indeed likely to characterize deep groundwater systems in granitic and ancient argillaceous systems. Thus TRUMP in its present form does provide a viable tool for use in nuclear waste evaluation studies. A sensitivity analysis based on the analytic solution suggests that the errors in prediction introduced due to uncertainties in input parameters is likely to be larger than the computational inaccuracies introduced by the numerical model. Currently, a disadvantage in the TRUMP model is that the iterative method of solving the set of simultaneous equations is rather slow when time

  1. Chemical Transport in a Fissured Rock: Verification of a Numerical Model

    NASA Astrophysics Data System (ADS)

    Rasmuson, A.; Narasimhan, T. N.; Neretnieks, I.

    1982-10-01

    Numerical models for simulating chemical transport in fissured rocks constitute powerful tools for evaluating the acceptability of geological nuclear waste repositories. Due to the very long-term, high toxicity of some nuclear waste products, the models are required to predict, in certain cases, the spatial and temporal distribution of chemical concentration less than 0.001% of the concentration released from the repository. Whether numerical models can provide such accuracies is a major question addressed in the present work. To this end we have verified a numerical model, TRUMP, which solves the advective diffusion equation in general three dimensions, with or without decay and source terms. The method is based on an integrated finite difference approach. The model was verified against known analytic solution of the one-dimensional advection-diffusion problem, as well as the problem of advection-diffusion in a system of parallel fractures separated by spherical particles. The studies show that as long as the magnitude of advectance is equal to or less than that of conductance for the closed surface bounding any volume element in the region (that is, numerical Peclet number <2), the numerical method can indeed match the analytic solution within errors of ±10-3% or less. The realistic input parameters used in the sample calculations suggest that such a range of Peclet numbers is indeed likely to characterize deep groundwater systems in granitic and ancient argillaceous systems. Thus TRUMP in its present form does provide a viable tool for use in nuclear waste evaluation studies. A sensitivity analysis based on the analytic solution suggests that the errors in prediction introduced due to uncertainties in input parameters are likely to be larger than the computational inaccuracies introduced by the numerical model. Currently, a disadvantage in the TRUMP model is that the iterative method of solving the set of simultaneous equations is rather slow when time

  2. Geophysical Exploration of Faults, Fissures, and Fractures at Four Sites in Mexicali, Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Lázaro-Mancilla, O.; Gonzalez-Fernandez, A.; Contreras-Corvera, A.; Stock, J. M.; Moreno-Ayala, D.; Ramirez-Hernandez, J.; Carreon-Diazconti, C.; Lopez, D. A. L.; Lopez, J. R.

    2014-12-01

    We conducted field geophysical measurements in areas in the City of Mexicali that are associated with geological faults, fissures, and fractures. The study sites are: 1) Instituto Tecnologico de Mexicali 2) The buried trace of the Michoacan de Ocampo fault in the urban zone 3) Rio Nuevo 4) A site reported by Frez (2013) with ground rupture SW of Cerro Prieto At Site 1, seismic reflection profiling used a cable with 24 geophones at 1 m spacing. The source was a 3.6 kg sledge hammer, with 3 impacts per shot point. 347 shot points at 2 m spacing provided 6 fold coverage along a straight line with minimal elevation changes. Sample rate was 2000/s, and record length 1 s; reflections were seen down to 0.3 s TWTT. Processing included: frequency filter, fk filter, predictive deconvolution, geometry, velocity analysis, NMO and stacking. Lateral changes in the seismic section are due to surface modification and/or the presence of faults.At site 2, we measured 222Radon in 36 locations along 17 profiles across the fault, using inherent alpha spectrometry with a Durridge RAD7 detector. Each site was measured at a depth of 60 cm, with 31 five-minute readings in a 3 hour period, interspersed with 10 minute of background purge and 3 five-minute background measurements. In a profile parallel to the fault, 78% of the readings were > 100 pCi/L, confirming the presence of the fault along the swath surveyed. At Site 3 we compiled observations of post-earthquake cracks, conducted reconnaissance, and measured some profiles using 100 MHz GPR. These observations showed that the cracks are associated with ground failure due to earthquake shaking. At Site 4 our new 222Radon gas measurements complemented a pre-existing profile that had high 222Radon values lacking a structural explanation. Related to this we found that this region has two NW-SE trending features: a magnetic anomaly low of 360 nT (Evans, Summer and Castillo, 1972) and a graben reported by the Mexican Geological Survey in 2003

  3. Reaction of the pterygomaxillary fissure and the condylar cartilage to intermaxillary Class III magnetic mechanics.

    PubMed

    Vardimon, A D; Graber, T M; Stutzmann, J; Voss, L; Petrovic, A G

    1994-04-01

    The skeletal reaction to Class III intermaxillary magnetic mechanics was previously found to affect two target areas, the pterygomaxillary fissure (PMF) and the condylar cartilage. The objectives of this study were to analyze, radiographically and histologically, the response of these tissues to Class III intermaxillary functional orthopedic magnetic appliance (FOMA III), and to postulate possible models of their dichotomous biomechanism. Nine Macaca fascicularis monkeys received periodic administration of vital bone procion dye and were treated for 4 months with FOMA III (6 subjects) and sham appliance (3 subjects). The PMF (the target area of the midfacial complex) demonstrated a decreased skeletal reaction in inferosuperior and lateromedial directions. Cephalometrically, the lowermost PMF point was displaced inferiorly 1.98 +/- 1.74 mm and 0.42 +/- 0.38 mm and anteriorly 1.42 +/- 0.96 mm and 0.58 +/- 0.38 mm in the treated and control groups, respectively. The displacement of the uppermost PMF point, compared with the lowermost point, was three to five times lower. Histologically, two modes of response were found; first, a sutural response (disarticulation and osteogenesis) of the palatomaxillary and pterygopalatine sutures, which was distinctive of the lateral PMF aspect, and second, a dentosutural response, which was characteristic of the medial PMF aspect (bony microfractures between the third molar germ and the maxillary tuberosity in conjunction with mild sutural response). In the mandible, a discrepancy was found between the histologic and the cephalometric findings. Radiographically, mandibular length was unaffected after 4 months of treatment, and the distance condylion-pogonion was equally increased in the treated (0.75 +/- 0.78 mm) and the control animals (0.77 +/- 0.32 mm). Histologically, however, the condylar cartilage demonstrated increased osteoclastic activity at the zone of endochondral ossification and a decreased apposition rate at the

  4. Are eruptions from linear fissures and caldera ring dykes more likely to produce pyroclastic flows?

    NASA Astrophysics Data System (ADS)

    Jessop, D. E.; Gilchrist, J.; Jellinek, A. M.; Roche, O.

    2016-11-01

    Turbulent volcanic jets are produced by highly-energetic explosive eruptions and may form buoyant plumes that rise many tens of kilometres into the atmosphere to form umbrella clouds or collapse to generate ground-hugging pyroclastic flows. Ash injected into the atmosphere can be transported for many hundreds of kilometres with the potential to affect climate, disrupt global air travel and cause respiratory health problems. Pyroclastic flows, by contrast, are potentially catastrophic to populations and infrastructure close to the volcano. Key to which of these two behaviours will occur is the extent to which the mechanical entrainment and mixing of ambient air into the jet by large (entraining) eddies forming the jet edge changes the density of the air-ash mixture: low entrainment rates lead to pyroclastic flows and high entrainment rates give rise to buoyant plumes. Recent experiments on particle-laden (multi-phase) volcanic jets from flared and straight-sided circular openings suggest that the likelihood for buoyant plumes will depend strongly on the shape and internal geometry of the vent region. This newly recognised sensitivity of the fate of volcanic jets to the structure of the vent is a consequence of a complex dynamic coupling between the jet and entrained solid particles, an effect that has generally been overlooked in previous studies. Building on this work, here we use an extensive series of experiments on multi-phase turbulent jets from analogue linear fissures and annular ring fractures to explore whether the restrictive vent geometry during cataclysmic caldera-forming (CCF) eruptions will ultimately lead a relatively greater frequency of pyroclastic flows than eruptions from circular vents on stratovolcanoes. Our results, understood through scaling analyses and a one-dimensional theoretical model, show that entrainment is enhanced where particle motions contribute angular momentum to entraining eddies. However, because the size of the entraining

  5. Fissural volcanism, polygenetic volcanic fields, and crustal thickness in the Payen Volcanic Complex on the central Andes foreland (Mendoza, Argentina)

    NASA Astrophysics Data System (ADS)

    Mazzarini, F.; Fornaciai, A.; Bistacchi, A.; Pasquarè, F. A.

    2008-09-01

    Shield volcanoes, caldera-bearing stratovolcanoes, and monogenetic cones compose the large fissural Payen Volcanic Complex, located in the Andes foreland between latitude 35°S and 38°S. The late Pliocene-Pleistocene and recent volcanic activity along E-W trending eruptive fissures produced basaltic lavas showing a within-plate geochemical signature. The spatial distribution of fractures and monogenetic vents is characterized by self-similar clustering with well defined power law distributions. Vents have average spacing of 1.27 km and fractal exponent D = 1.33 defined in the range 0.7-49.3 km. The fractal exponent of fractures is 1.62 in the range 1.5-48.1 km. The upper cutoffs of fractures and vent fractal distributions (about 48-49 km) scale to the crustal thickness in the area, as derived from geophysical data. This analysis determines fractured media (crust) thickness associated with basaltic retroarc eruptions. We propose that the Payen Volcanic Complex was and is still active under an E-W crustal shortening regime.

  6. Micro-leakage of a Fissure Sealant Cured Using Quartz-tungsten-halogen and Plasma Arc Light Curing Units

    PubMed Central

    Bahrololoomi, Zahra; Soleimani, Ali Asghar; Jafari, Najmeh; Varkesh, Bentolhoda

    2014-01-01

    Background and aims. Newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. Materials and methods. Sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test. Results. There was no significant difference between two groups regarding micro-leakage (P = 0.42). Conclusion. Results showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization. PMID:25587389

  7. Micro-leakage of a Fissure Sealant Cured Using Quartz-tungsten-halogen and Plasma Arc Light Curing Units.

    PubMed

    Bahrololoomi, Zahra; Soleimani, Ali Asghar; Jafari, Najmeh; Varkesh, Bentolhoda

    2014-01-01

    Background and aims. Newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. Materials and methods. Sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test. Results. There was no significant difference between two groups regarding micro-leakage (P = 0.42). Conclusion. Results showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization.

  8. Comparison of Clinical Success of Applying a Kind of Fissure Sealant on the Lower Permanent Molar Teeth in Dry and Wet Conditions

    PubMed Central

    Eskandarian, Tahereh; Baghi, Saeid; Alipoor, Abbas

    2015-01-01

    Statement of the Problem Fissure sealant therapy is among the most effective methods of preventing dental caries. However, it is lengthy and isolation of the teeth is difficult in this procedure especially in young children. Using new hydrophilic fissure sealant may reduce such problems. Purpose This study aimed to evaluate the clinical success of a hydrophilic fissure sealant on the lower permanent molar teeth in dry and wet conditions. Materials and Method This clinical trial assessed 31 patients (mean age 8.13±1.77 years) who needed fissure sealant therapy on their first or second mandibular permanent molar. Having performed dental prophylaxis, the teeth were etched and rinsed. Then one of the two was randomly selected and sealed with smartseal & loc in isolated and dry conditions; while, the other was wetted on the etched enamel by using a saliva-contaminated micro brush, and was then sealed with the same fissure as the first tooth. Six and 12 months later, two independent observers examined the clinical success of sealant through checking the marginal integrity, marginal discoloration, and anatomical form. Data were analyzed by using SPSS software, version 16. The bivariate Chi-square and Exact Fisher tests were used to compare the clinical success of the two treatment methods. Results There was a high interpersonal reliability between the two examiners (K= 0.713). After 12 months, 90.3% clinical success was observed in dry conditions and 83.9% in wet conditions for smartseal & loc; however, the difference was not statistically significant (p= 0.0707). Conclusion According to the results of this study, it seems that using new hydrophilic fissure sealant can reduce technical sensitivities and consequently decreases the apprehensions on saliva contamination of etched enamel during treatment procedures. PMID:26331144

  9. The ‘Excess’ Emission from the Warm Surface Adjacent to Active Fissures on Enceladus from Combined VIMS and CIRS Spectra

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Buratti, Bonnie J.; Howell, Robert R.

    2015-11-01

    The exciting discovery of thermal emission from the tiger stripe fissures at the S. pole of Enceladus is a major highlight of the Cassini mission. Both VIMS (Visible and Infrared Mapping Spectrometer) and CIRS (Composite InfraRed Spectrometer) detect the thermal ‘blackbody’ spectrum emitted from the warm fissure areas. The VIMS instrument is uniquely suited to measuring the hottest active locations because VIMS covers the 3 to 5 micron wavelength range where the rising edge of the Planck function for these T~200 K areas dominates the emission spectrum. At longer wavelengths, the spectrum is more complicated because contributions from small hot areas and larger cooler areas combine to form the broad emission spectrum that is detected by the CIRS instrument at wavelengths >6.7 microns. It is the combination of VIMS and CIRS spectra that paint a more complete portrait of the fissure heat transfer processes. Using spectra that span both the VIMS and CIRS wavelengths places a stronger constraint on the T distribution near the fissures than consideration of the spectra from either instrument alone.We show that when the best (= highest spatial resolution, 800 m/pixel and smaller) VIMS and CIRS spectra of the fissure thermal emission are considered together, there is a large (up to 400%) component of ‘excess’ emission spanning 7 to 17 microns that requires explanation. New analysis of ~2 km spatial resolution VIMS spectra of the Damascus hot spot on 8/13/2010 are similar to the highest resolution 4/14/2012 VIMS Baghdad spectra, confirming that differences in location or time between the best VIMS and CIRS spectra do not explain away the excess. The obvious interpretation is that there are processes that transfer heat from the fissure eruption to the surface within 400 m of the fissure center in addition to heat conduction through the fissure walls. Candidate heat transfer processes include fallback of large warm low velocity ice particles from the edges of the

  10. Mechanisms, Monitoring and Modeling Earth Fissure generation and Fault activation due to subsurface Fluid exploitation (M3EF3): A UNESCO-IGCP project in partnership with the UNESCO-IHP Working Group on Land Subsidence

    NASA Astrophysics Data System (ADS)

    Teatini, P.; Carreon-Freyre, D.; Galloway, D. L.; Ye, S.

    2015-12-01

    Land subsidence due to groundwater extraction was recently mentioned as one of the most urgent threats to sustainable development in the latest UNESCO IHP-VIII (2014-2020) strategic plan. Although advances have been made in understanding, monitoring, and predicting subsidence, the influence of differential vertical compaction, horizontal displacements, and hydrostratigraphic and structural features in groundwater systems on localized near-surface ground ruptures is still poorly understood. The nature of ground failure may range from fissuring, i.e., formation of an open crack, to faulting, i.e., differential offset of the opposite sides of the failure plane. Ground ruptures associated with differential subsidence have been reported from many alluvial basins in semiarid and arid regions, e.g. China, India, Iran, Mexico, Saudi Arabia, Spain, and the United States. These ground ruptures strongly impact urban, industrial, and agricultural infrastructures, and affect socio-economic and cultural development. Leveraging previous collaborations, this year the UNESCO Working Group on Land Subsidence began the scientific cooperative project M3EF3 in collaboration with the UNESCO International Geosciences Programme (IGCP n.641; www.igcp641.org) to improve understanding of the processes involved in ground rupturing associated with the exploitation of subsurface fluids, and to facilitate the transfer of knowledge regarding sustainable groundwater management practices in vulnerable aquifer systems. The project is developing effective tools to help manage geologic risks associated with these types of hazards, and formulating recommendations pertaining to the sustainable use of subsurface fluid resources for urban and agricultural development in susceptible areas. The partnership between the UNESCO IHP and IGCP is ensuring that multiple scientific competencies required to optimally investigate earth fissuring and faulting caused by groundwater withdrawals are being employed.

  11. Efficacy of egg yolk and nitroglycerin ointment as treatments for acute anal fissures: A randomized clinical trial study

    PubMed Central

    Salari, Masoumeh; Salari, Roshanak; Dadgarmoghadam, Maliheh; Khadem-Rezaiyan, Majid; Hosseini, Mousalreza

    2016-01-01

    Background Acute anal fissure as a common disease in society has several etiologies and manifestations such as severe anal pain and bleeding. Nitroglycerin ointment 0.2% is the most common topical treatment used. The most common side effect of nitroglycerin is headache, which is annoying for patients and often leads to discontinuation of the drug. Objective Comparison of egg yolk as a natural substance with analgesic and anti-inflammatory properties and minimal side effects with nitroglycerin ointment in the treatment of acute anal fissure. Methods This randomized clinical trial was carried out during a 10-day period in the Gastroenterology clinic of Ghaem Hospital, Mashhad, Iran (year 2015). 126 patients who filled the inclusion criteria were enrolled. The patients were randomly divided into two groups. Nitroglycerin ointment (0.2%) was applied by patients in the first group, twice daily for 10 days. For the second group, one egg yolk once a day was administered rectally up to 10 days. The pain and bleeding severity were recorded every two days up to 10 days after finishing the treatment course, based on visual scale Results The results showed that egg yolk caused a significant reduction in pain and bleeding compared with nitroglycerin (p<0.05). At the beginning of the study, the difference in pain intensity between the two groups was not statistically significant (p-value = 0.25). However, it became significant in the following days. Changes in the frequency of rectorrhagia were also significant in both groups, showing a major decrease in the number of rectorrhagia cases (p<0.001). Conclusion Egg yolk is more efficient than nitroglycerin in the treatment of acute anal fissure. In addition, lack of any side effects results in the completion of the treatment course by the patients. Trial Registration The trial was registered at the Iranian Registry of Clinical Trials (http://www.irct.ir) with the Irct ID: IRCT2015050718915N3. Funding This work was supported by a

  12. Dike Propagation Mechanisms from Seismicity Accompanying the 2014 Bárðarbunga-Holuhraun Fissure Eruption, Iceland

    NASA Astrophysics Data System (ADS)

    Woods, J.; Ágústsdóttir, T.; Greenfield, T. S.; Green, R. G.; White, R. S.; Brandsdottir, B.

    2015-12-01

    We present data from our dense seismic network which captured in unprecedented detail the micro-seismicity associated with the 2014 dike intrusion from the subglacial Bárðarbunga volcano in central Iceland. Over 30,000 automatically located earthquakes delineate a complex 46 km dike propagation during the days preceding the onset of effusive magmatism at the Holuhraun lava field on 29 August 2014. Approximately 1.5 km3 of lava was erupted, making this the largest eruption in Iceland for over 200 years.Micro-seismicity tracks the lateral migration of the dike, with a concentration of earthquakes in the advancing tip where stresses are greatest, and trailing zones of lesser or no seismicity behind. Onset of an initial 4 hour fissure eruption was accompanied simultaneously by a backward retreat in seismic activity, followed by a gradual re-advance prior to the onset of a second, sustained fissure eruption in the same location on 31 August. Rock fracture mechanisms are determined from fault plane solutions of these seismic events. At the tip of the advancing dike, left-lateral strike-slip faulting parallel to the propagation is dominant, utilising pre-existing lineations and releasing stress accumulated in the brittle layer from rift zone extension. Behind the dike tip, both right-lateral and left-lateral strike-slip earthquakes are found, marking failure of solidifying magma plugs within the dike conduit. Contrary to many models of dike propagation, both normal faulting and failure at high angles to the dike are rare. Furthermore, a distinct lack of seismicity is observed in the 3-4 km region beneath the surface rupture. This suggests that opening is occuring aseismically, with earthquakes focused at the base of the dike near the brittle-ductile boundary.

  13. An in vitro comparison between laser fluorescence and visual examination for detection of demineralization in occlusal pits and fissures.

    PubMed

    Ferreira Zandoná, A G; Analoui, M; Beiswanger, B B; Isaacs, R L; Kafrawy, A H; Eckert, G J; Stookey, G K

    1998-01-01

    It has been demonstrated that when excited by laser light carious enamel appears dark compared to luminescent sound enamel. The aim of this study was to compare the sensitivity and specificity of visual exams (V), laser fluorescence (LF) and dye-enhanced LF (DELF) for detecting demineralization in occlusal pits and fissures. The actual presence of lesions was determined by subsequent confocal laser microscopy (CM), which was compared to histology (H). Independent clinical examiners visually graded three sites on occlusal surfaces of extracted, human premolars as sound or carious and also rated the color of each graded site as: 0 = same as surrounding enamel; 1 = white; 2 = light brown, or 3 = brown/dark brown. An argon laser was used to illuminate the teeth for LF and DELF; the images were captured with a CCD camera and then analyzed. DELF images were captured after the teeth had been exposed to 0.075% sodium fluorescein. Sections were then cut from each specimen and analyzed by CM and H for the presence or absence of caries. Results showed that DELF (0.72) was significantly more sensitive (p<0.05) than LF (0.49) and V (0.03) for detecting caries, but there were no significant differences among the methods in specificity (V 1.00; LF 0.67; DELF 0.60). When color was used as an indication of caries in V (VC, sensitivity 0.47; specificity 0.70), V exams were not different from LF. The area under the ROC curve, using H as the gold standard and CM as the test, was 0.78. Results indicated that DELF was the best diagnostic tool and that VC and LF were equally effective as diagnostic methods, when color of fissures was included as an indication of demineralization in the visual exam.

  14. Potential for aquifer compaction, land subsidence, and earth fissures in Avra Valley, Pima and Pinal counties, Arizona

    USGS Publications Warehouse

    Anderson, S.R.

    1987-01-01

    Avra Valley is a large north-trending alluvial basin about 15 mi west of Tucson in Pima and Pinal Counties, Arizona. The climate of Avra Valley is semiarid, and the average annual precipitation ranges from 8 to 12 in. Two major ephemeral streams, the Santa Cruz River and Brawley Wash, drain the area. These streams and their tributaries provide a source of recharge to an extensive alluvial aquifer that underlies the valley floor. The aquifer consists of interbedded gravel, sand, silt, and clay and contains a vast quantity of groundwater. The physiography, fertile soil, and mild climate of Avra Valley make it an ideal environment for agriculture and urban development. Although the aquifer is replenished by natural recharge and underflow, rates of recharge and underflow have not kept pace with the rate of pumping. Pumping has exceeded recharge for several decades, resulting in a lowering of groundwater levels throughout most of the valley. In places, water level declines have resulted in small amounts of aquifer compaction and land subsidence. Earth fissures, some of which may be the result of localized differential subsidence, also have been observed in the valley. Geohydrologic characteristics of Avra Valley that may contribute to potential aquifer compaction, land subsidence, and earth fissures are described. The quantitative evaluation of potential land subsidence in this report is presented as an interim land- and water-use planning tool pending acquisition and study of additional data. Because of data limitations, the evaluation is made on the assumption that future rates of compaction and subsidence in Avra Valley will be similar to those in the Eloy-Picacho area. The evaluation also assumes that water level declines in the aquifer will continue. Several factors that may reduce groundwater withdrawals, and thus the potential for compaction and subsidence in Avra Valley, were not evaluated. These factors include the enactment of the 1980 Arizona Ground

  15. RECURRENT ECTOPIC CRANIOPHARYNGIOMA IN THE SYLVIAN FISSURE THIRTY YEARS AFTER RESECTION THROUGH A PTERIONAL APPROACH: A CASE REPORT AND REVIEW OF THE LITERATURE

    PubMed Central

    CLARK, SHANNON W.; KENNING, TYLER J.; EVANS, JAMES J.

    2015-01-01

    ABSTRACT Local recurrence of craniopharyngiomas after apparently complete resection occurs frequently. Ectopic recurrence remote from the original site has been reported in 18 adult patients. The interval between the original diagnosis and the time of recurrence varies widely in these reports (1–26 years). We report a case of an ectopic recurrence in the sylvian fissure of an adamantinomatous type craniopharyngioma 34 years after the initial presentation and 30 years after the last surgical resection. In addition to this being the latest reported ectopic recurrence, the location of this new lesion in the sylvian fissure is fairly rare, having been reported in only three other cases. We also reviewed the English literature for reports of ectopic recurrent craniopharyngiomas in order to conduct an analysis of surveillance and treatment strategies. PMID:25797995

  16. Choroidal fissure acts as an overflow device in cerebrospinal fluid drainage: morphological comparison between idiopathic and secondary normal-pressure hydrocephalus

    PubMed Central

    Yamada, Shigeki; Ishikawa, Masatsune; Iwamuro, Yasushi; Yamamoto, Kazuo

    2016-01-01

    To clarify the pathogenesis of two different types of adult-onset normal-pressure hydrocephalus (NPH), we investigated cerebrospinal fluid distribution on the high-field three-dimensional MRI. The subarachnoid spaces in secondary NPH were smaller than those in the controls, whereas those in idiopathic NPH were of similar size to the controls. In idiopathic NPH, however, the basal cistern and Sylvian fissure were enlarged in concurrence with ventricular enlargement towards the z-direction, but the convexity subarachnoid space was severely diminished. In this article, we provide evidence that the key cause of the disproportionate cerebrospinal fluid distribution in idiopathic NPH is the compensatory direct CSF communication between the inferior horn of the lateral ventricles and the ambient cistern at the choroidal fissure. In contrast, all parts of the subarachnoid spaces were equally and severely decreased in secondary NPH. Blockage of CSF drainage from the subarachnoid spaces could cause the omnidirectional ventricular enlargement in secondary NPH. PMID:27941913

  17. Turbulent atmospheric plumes above line sources with an application to volcanic fissure eruptions on the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1989-01-01

    The theory of turbulent plumes maintained above steady line sources of buoyancy is worked out in detail within the limitations of Taylor's entrainment assumption. It is applied to the structure of a pure plume injected into a stably stratified atmosphere. Volcanic basalt eruptions that develop from long, narrow vents create line source plumes, which rise well above the magmatic fire fountains playing near the ground level. The eruption of Laki in 1783 may provide an example of this style of eruption. Flood basalts are more ancient examples. Evidence of enormous fissure eruptions that occurred in the past on Mars and Venus also exists. Owing to the different properties of the atmospheres on these two planets from those on the earth, heights of line source plumes are expected to vary in the ratios 1:6:0.6 (earth:Mars:Venus). It is very unlikely that the observed increase of sulfur dioxide above the Venusian cloud deck in 1978 could have been due to a line source volcanic eruption, even if it had been a flood basalt eruption.

  18. Comparative study of fluoride released and recharged from conventional pit and fissure sealants versus surface prereacted glass ionomer technology

    PubMed Central

    Salmerón-Valdés, Elias Nahum; Scougall-Vilchis, Rogelio J; Alanis-Tavira, Jorge; Morales-Luckie, Raúl Alberto

    2016-01-01

    Context: The fluoride release of sealants in vitro shows a marked decrease. Giomers are distinguishable from manufactured resin-based sealants and contain prereacted glass-ionomer particles (PRG). Aims: To compare the amounts of fluoride released from the main pit and fissure of a resin-based sealant with that from a Giomer and to assess the abilities of the sealant and the Giomer to recharge when exposed to regular use of fluoride rinse. Materials and Methods: The readings for the fluoride concentration were carried out for 60 days using a fluoride ion-specific electrode. After this period, the samples were recharged using a fluoride mouth rinse. The amount of fluoride released after this recharge was determined for 5 days. The data were analyzed using Student's t- and analysis of variance tests. Results: In general, all materials presented higher fluoride release in the first 24 h; G1 and G4 showed a higher fluoride release in this period. On the other hand, G3 and G1 presented the most constant fluoride release until the 8th day, wherein all the sealants considerably decreased in the amount of fluoride released. Conclusion: G1 and G3 released higher concentrations of fluoride, although no significant differences were found. Giomers recharged in the first 24 h after polymerization presented an improved and sustained fluoride release. PMID:26957792

  19. Myoxinol (Hydrolyzed Hibiscus esculentus Extract) in the Cure of Chronic Anal Fissure: Early Clinical and Functional Outcomes

    PubMed Central

    Renzi, Adolfo; Di Sarno, Giandomenico; D'Aniello, Francesco; Ziccardi, Stefania; Paladino, Fiorella

    2015-01-01

    Objective. This study was designed to evaluate the early results of the topical application of Hydrolyzed Hibiscus esculentus Extract 3% ointment (Myoxinol 3%), a novel local product with Botox-like activity, in the conservative treatment of chronic anal fissure (CAF). Methods. Among all patients with CAF observed during the study period, 31 subjects met the inclusion criteria and underwent medical therapy with Myoxinol 3% ointment every 12 hours for 6 weeks. Two patients were lost to follow-up. Clinical and manometric follow-up was carried out eight weeks after treatment. Results. At follow-up the success rate was 72.4% (21/29); median VAS score and mean anal resting pressure were significantly lower if compared with respective baseline data. The only one adverse effect of the topical application of Myoxinol 3% ointment was perianal itch, which was reported by 3,4% (1/29) of the patients available for the analysis. However, in this case this symptom did not cause interruption of the treatment. Conclusions. The topical application of Myoxinol 3% ointment in the cure of CAF shows encouraging early results. Further researches with a larger series and a longer follow-up are needed to confirm these data. PMID:25861259

  20. Dental depth profilometric diagnosis of pit & fissure caries using frequency-domain infrared photothermal radiometry and modulated laser luminescence

    NASA Astrophysics Data System (ADS)

    Jeon, R. J.; Mandelis, A.; Sanchez, V.; Abrams, S. H.

    2005-06-01

    Non-intrusive, non-contacting frequency-domain photothermal radiometry (FD-PTR or PTR) and frequency-domain luminescence (FD-LUM or LUM) have been used with 659- nm and 830-nm laser sources to detect artificial and natural sub-surface defects in human teeth. Fifty-two human teeth were examined with simultaneous measurements of PTR and LUM and compared to conventional diagnostic methods including continuous (dc) luminescence (DIAGNOdent), visual inspection and radiographs by calculating sensitivities and specificities. With the combined criteria of four PTR and LUM signals (two amplitudes and two phases), it was found that the sensitivity of this method was much higher than any of the other methods used in this study, whereas the specificity was comparable to that of dc luminescence diagnostics. Therefore, PTR and LUM, used together as a combined technique, have the potential to be a reliable tool to diagnose early pit and fissure caries and could provide detailed information about deep lesions with its depth profilometric character. Also, from experiments with natural or artificial defects, some depth profilometric characteristics were confirmed.

  1. 640-Slice CT Measurement of Superior Orbital Fissure as Gateway for Light into the Brain: Statistical Evaluation of Area and Distance

    PubMed Central

    La Marra, Alice; Quarchioni, Simone; Ferrari, Fabiana; Gravina, Giovanni Luca; Barile, Antonio; Gregori, Lorenzo Maria; Di Cesare, Ernesto

    2016-01-01

    Objective Our aim was to provide normative data concerning superior orbital fissure area (SOFA), ocular skin and the substantia nigra (D-SS) and orbital fissure and the substantia nigra (D-SOF-S) distances by CT scan in adult Caucasian population Methods The area of the superior orbital fissure (SOF), the distance between the ocular skin and the substantia nigra and the distance between the superior orbital fissure and the substantia nigra using CT and 3D-CT images. Results Normative data stratified for age and gender were obtained. The data here reported show that some degree of variability in SOFA, D-SS and D-SOF-S measurements can be observed healthy Caucasian subjects. Gender stratified prediction intervals (mean +/- 2 Standard Deviations) for SOFA and D-SOF-S were 69.2 (+/-15.8) and 38.4 (+/-7.6) for male and 56.8 (+/-11.9) and 36.5 (+/-6.1) for female, respectively. Age and gender significantly impacted on D-SS values and normative data were constructed generating data stratified for these two variables. D-SS was 89.4 (+/-10.3) and 86.4 (+/-9.7) for male and female, respectively. Conclusions Here we provide adjunctive anatomical information on specific anatomical cerebral zones. Our data may have implications for surgeons actively committed to treat pathological conditions involving these cerebral areas. Additionally, the anatomical variability found with respect to SOF and the potential different exposure of the substanzia nigra to the bright light could play a role in Parkinson’s disease as already speculated in literature. PMID:27661082

  2. Evaluation of retention of pit and fissure sealants placed with and without air abrasion pretreatment in 6-8 year old children – An in vivo study

    PubMed Central

    Goswami, Mridula

    2017-01-01

    Background The success of pit and fissure sealants is directly related to their retention. The purpose of this study was to assess and compare the retention of pit and fissure sealants placed using acid etch alone and a combination of air abrasion and acid etch techniques. Material and Methods 50 subjects aged 6-8 years were included in the study. Primary second molars and permanent first molars were sealed in all four quadrants using split mouth design. The right maxillary and mandibular molars (Group A) were treated by acid etching alone while the left maxillary and mandibular molars (Group B) were pretreated with air abrasion followed by acid etching before application of pit and fissure sealant. Retention of sealants was checked using Simonsen’s criteria of sealant retention after three and six months of sealant application. Results There was no significant difference in retention of sealants in Group A and Group B (p<0.05) after three and six months follow up. The difference in sealant retention in primary and permanent molars was not significant (p>0.05). Maxillary molars showed superior retention compared to mandibular molars, which was statistically significant at both three and six months (p<0.05). Conclusions Combining air abrasion pretreatment with subsequent acid etching did not result in statistically significant difference in sealant retention compared to acid etching alone in both primary and permanent molars after 3 and 6 months follow up. An additional air abrasion pretreatment step can be avoided in pediatric patients when placing sealants and the procedure can be completed faster with better behavior management using acid etching alone. Key words:Pit and fissure sealant, acid etching, air abrasion. PMID:28210438

  3. Hematite (U-Th)/He and Apatite Fission-track Dating Constrain Paleofluid Circulation in Faults: An Example from Gower Peninsula Fissure Fills, Wales

    NASA Astrophysics Data System (ADS)

    Ault, A. K.; Frenzel, M.; Reiners, P. W.; Woodcock, N. H.; Thomson, S. N.

    2015-12-01

    Hematite-calcite fissure fills on the Gower Peninsula, Wales, preserve evidence of faulting, mineralization, and multiple fluid flow events. Fissures are associated with dilational strike-slip faults in early Carboniferous limestone and contain locally brecciated hematite, calcite, and red sediment. Hematite is macroscopically botryoidal, but lobes comprise an intricate aggregate of 0.15-0.5 μm-thick plates with high aspect ratios. Prior work suggests mineralization occurred in either late Carboniferous or late Triassic time. We combine hematite (U-Th)/He dating with apatite (U-Th)/He, apatite fission-track (AFT), and zircon (U-Th)/He thermochronology of fill materials to evaluate the timing and thermal effects of fluid circulation in these structures. Hematite He data from four fissures yield reproducible dates of 141.0 ± 5.1 Ma to 119.9 ± 5.0 Ma. Individual zircon He dates from a sandstone infill sample are ~402-260 Ma, reflecting erosion of source material, and imply a maximum late Permian depositional age. The sandstone AFT date of 131.4 ± 20.1 Ma overlaps with the hematite He results and the apatite He date is ~50 Ma. Reconstruction of the regional burial history from independent geologic constraints reveals modern exposures were not buried and reheated to temperatures hot enough to reset the AFT or hematite He systems in the Triassic-Early Cretaceous. Thus, these data do not simply record ambient cooling from erosion. Hot fluids (~100-150 °C) circulating through fissures in the Early Cretaceous reset the AFT system. Hematite either formed in the Triassic and was also reset by fluids or formed from these fluids. Similar hematite He dates from fault-related mineralization in adjacent south Glamorgan and Cumbria, England, imply concomitant regional hot fluid effects. Our data document hydrothermal fluid circulation, coeval with opening of the North Atlantic Ocean, in these higher permeability fissures and fault veins long after they initially formed

  4. Deep subsurface mine stalactites trap endemic fissure fluid Archaea, Bacteria, and Nematoda possibly originating from ancient seas.

    PubMed

    Borgonie, Gaëtan; Linage-Alvarez, Borja; Ojo, Abidemi; Shivambu, Steven; Kuloyo, Olukayode; Cason, Errol D; Maphanga, Sihle; Vermeulen, Jan-G; Litthauer, Derek; Ralston, Colin D; Onstott, Tullis C; Sherwood-Lollar, Barbara; Van Heerden, Esta

    2015-01-01

    Stalactites (CaCO3 and salt) from water seeps are frequently encountered in ceilings of mine tunnels whenever they intersect water-bearing faults or fractures. To determine whether stalactites could be mineralized traps for indigenous fracture water microorganisms, we analyzed stalactites collected from three different mines ranging in depth from 1.3 to 3.1 km. During sampling in Beatrix gold mine (1.4 km beneath the surface), central South Africa, CaCO3 stalactites growing on the mine tunnel ceiling were collected and observed, in two cases, to contain a living obligate brackish water/marine nematode species, Monhystrella parvella. After sterilization of the outer surface, mineral layers were physically removed from the outside to the interior, and DNA extracted. Based upon 16S and 18S rRNA gene sequencing, Archaea, Bacteria, and Eukarya in different combinations were detected for each layer. Using CT scan and electron microscopy the inner structure of CaCO3 and salt stalactites were analyzed. CaCO3 stalactites show a complex pattern of lamellae carrying bacterially precipitated mineral structures. Nematoda were clearly identified between these layers confirming that bacteria and nematodes live inside the stalactites and not only in the central straw. Salt stalactites exhibit a more uniform internal structure. Surprisingly, several Bacteria showing highest sequence identities to marine species were identified. This, together with the observation that the nematode M. parvella recovered from Beatrix gold mine stalactite can only survive in a salty environment makes the origin of the deep subsurface colonization enigmatic. The possibility of a Permian origin of fracture fluids is discussed. Our results indicate stalactites are suitable for biodiversity recovery and act as natural traps for microorganisms in the fissure water long after the water that formed the stalactite stopped flowing.

  5. Ground based measurements of the gas emission from the Holuhraun volcanic fissure eruption on Iceland 2014/2015

    NASA Astrophysics Data System (ADS)

    Galle, Bo; Arellano, Santiago; Conde, Vladimir; Pfeffer, Melissa; Barsotti, Sara; Stefansdottir, Gerður; Bergsson, Baldur; Bergsson, Bergur; Ingvarsson, Thorgils; Weber, Konradin

    2015-04-01

    The since 31 August 2014 ongoing volcanic eruption at Holuhraun on Iceland is by far the strongest source of sulfur dioxide in Europe over the last 230 years with sustained emission rates exceeding 100 000 ton/day. This gas emission severely affects local population and has become a concern also for air traffic. The eruption has in December continued at constant pace for 3.5 months. Three scenarios are envisaged for the future; (1) the eruption stops, (2) the fissure extends under the Vattnajökul glacier and (3) Bardarbunga volcano erupts. The two later scenarios will cause increased gas emission, severe ash emissions and extended flooding. Under the scope of the EU-project FUTUREVOLC, a project with 3.5 years duration, aiming at making Iceland a supersite for volcanological research as a European contribution to GEO, we are developing a version of the Scanning DOAS instrument that is adapted to high latitudes with low UV radiation and severe meteorological conditions. Since the first day of the eruption several of these novel instruments has been monitoring the SO2 emission from the eruption. Data from our instruments are still after 3.5 months the only sustained ground-based monitoring of this gas emission. A lot of work is however needed to sustain this operation at a very remote site and under severe field conditions. At the same time the very high concentrations in the gas plume, in combination with bad meteorological conditions require the development of novel methods to derive reliable flux estimates. In this presentation we will discuss the instrumental issues and present the latest version of the emission estimates made from our measurements.

  6. Deep subsurface mine stalactites trap endemic fissure fluid Archaea, Bacteria, and Nematoda possibly originating from ancient seas

    PubMed Central

    Borgonie, Gaëtan; Linage-Alvarez, Borja; Ojo, Abidemi; Shivambu, Steven; Kuloyo, Olukayode; Cason, Errol D.; Maphanga, Sihle; Vermeulen, Jan-G; Litthauer, Derek; Ralston, Colin D.; Onstott, Tullis C.; Sherwood-Lollar, Barbara; Van Heerden, Esta

    2015-01-01

    Stalactites (CaCO3 and salt) from water seeps are frequently encountered in ceilings of mine tunnels whenever they intersect water-bearing faults or fractures. To determine whether stalactites could be mineralized traps for indigenous fracture water microorganisms, we analyzed stalactites collected from three different mines ranging in depth from 1.3 to 3.1 km. During sampling in Beatrix gold mine (1.4 km beneath the surface), central South Africa, CaCO3 stalactites growing on the mine tunnel ceiling were collected and observed, in two cases, to contain a living obligate brackish water/marine nematode species, Monhystrella parvella. After sterilization of the outer surface, mineral layers were physically removed from the outside to the interior, and DNA extracted. Based upon 16S and 18S rRNA gene sequencing, Archaea, Bacteria, and Eukarya in different combinations were detected for each layer. Using CT scan and electron microscopy the inner structure of CaCO3 and salt stalactites were analyzed. CaCO3 stalactites show a complex pattern of lamellae carrying bacterially precipitated mineral structures. Nematoda were clearly identified between these layers confirming that bacteria and nematodes live inside the stalactites and not only in the central straw. Salt stalactites exhibit a more uniform internal structure. Surprisingly, several Bacteria showing highest sequence identities to marine species were identified. This, together with the observation that the nematode M. parvella recovered from Beatrix gold mine stalactite can only survive in a salty environment makes the origin of the deep subsurface colonization enigmatic. The possibility of a Permian origin of fracture fluids is discussed. Our results indicate stalactites are suitable for biodiversity recovery and act as natural traps for microorganisms in the fissure water long after the water that formed the stalactite stopped flowing. PMID:26441844

  7. Evolution of dike opening during the March 2011 Kamoamoa fissure eruption, Kīlauea Volcano, Hawai`i

    USGS Publications Warehouse

    Lundgren, Paul; Poland, Michael; Miklius, Asta; Orr, Tim R.; Yun, Sang-Ho; Fielding, Eric; Liu, Zhen; Tanaka, Akiko; Szeliga, Walter; Hensley, Scott; Owen, Susan

    2013-01-01

    The 5–9 March 2011 Kamoamoa fissure eruption along the east rift zone of Kīlauea Volcano, Hawai`i, followed months of pronounced inflation at Kīlauea summit. We examine dike opening during and after the eruption using a comprehensive interferometric synthetic aperture radar (InSAR) data set in combination with continuous GPS data. We solve for distributed dike displacements using a whole Kīlauea model with dilating rift zones and possibly a deep décollement. Modeled surface dike opening increased from nearly 1.5 m to over 2.8 m from the first day to the end of the eruption, in agreement with field observations of surface fracturing. Surface dike opening ceased following the eruption, but subsurface opening in the dike continued into May 2011. Dike volumes increased from 15, to 16, to 21 million cubic meters (MCM) after the first day, eruption end, and 2 months following, respectively. Dike shape is distinctive, with a main limb plunging from the surface to 2–3 km depth in the up-rift direction toward Kīlauea's summit, and a lesser projection extending in the down-rift direction toward Pu`u `Ō`ō at 2 km depth. Volume losses beneath Kīlauea summit (1.7 MCM) and Pu`u `Ō`ō (5.6 MCM) crater, relative to dike plus erupted volume (18.3 MCM), yield a dike to source volume ratio of 2.5 that is in the range expected for compressible magma without requiring additional sources. Inflation of Kīlauea's summit in the months before the March 2011 eruption suggests that the Kamoamoa eruption resulted from overpressure of the volcano's magmatic system.

  8. Caries-Preventive Effect of High-Viscosity Glass Ionomer and Resin-Based Fissure Sealants on Permanent Teeth: A Systematic Review of Clinical Trials

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2016-01-01

    Background Glass-ionomers are traditionally regarded to be inferior to resin as fissure sealants in protecting teeth from dental caries, due to their comparatively lower retention rate. Unlike low-viscosity glass-ionomers, high-viscosity glass-ionomer cements (HVGIC) are placed as sealants by pressing the material into pits and fissures with a petroleum-jelly-coated index finger. Hence, HVGIC sealants are assumed to penetrate pits and fissures deeper, resulting in a higher material retention rate, which may increase its caries-preventive effect. Methods The aim of this review was to answer the question as to whether, in patients with fully erupted permanent molar teeth, HVGIC based fissure sealants are less effective to protect against dental carious lesions in occlusal pits and fissures than resin-based fissure sealants? A systematic literature search in eight databases was conducted. Heterogeneity of accepted trials and imprecision of the established evidence were assessed. Extracted sufficiently homogenous datasets were pooled by use of a random-effects meta-analysis. Internal trial validity was evaluated. The protocol of this systematic review was registered with the International Prospective Register of Systematic Reviews (PROSPERO / Nr.: CRD42015016007). Results Seven clinical trials were provisionally included for further review. Of these, one was excluded. Seven trial reports reporting on six trials were accepted. From these, 11 datasets were extracted and pooled in four meta-analyses. The results suggest no statistically significant differences after up to 48 months and borderline significant differences in favour of HVGIC sealants after 60 months (RR 0.29; 95% CI: 0.09–0.95; p = 0.04 / RD -0.07; 95% CI: -0.14, -0.01). The point estimates and upper confidence levels after 24, 36, 48 and 60 months of RR 1.36; RR 0.90; RR 0.62; RR 0.29 and 2.78; 1.67; 1.21; 0.95, respectively, further suggest a chronological trend in favour of HVGIC above resin

  9. Non-destructive measurement of demineralization and remineralization in the occlusal pits and fissures of extracted 3rd molars with PS-OCT

    NASA Astrophysics Data System (ADS)

    Lee, Chulsung; Hsu, Dennis J.; Le, Michael H.; Darling, Cynthia L.; Fried, Daniel

    2009-02-01

    Previous studies have demonstrated that Polarization Sensitive Optical Coherence Tomography (PS-OCT) can be used to image the remineralization of early artificial caries lesion on smooth enamel surfaces of human and bovine teeth. However, most new dental decay is found in the pits and fissures of the occlusal surfaces of posterior dentition and it is in these high risk areas where the performance of new caries imaging devices need to be investigated. The purpose of this study was to demonstrate that PS-OCT can be used to measure the subsequent remineralization of artificial lesions produced in the pits and fissures of extracted 3rd molars. A PS-OCT system operating at 1310-nm was used to acquire polarization resolved images of occlusal surfaces exposed to a demineralizing solution at pH-4.5 followed by a fluoride containing remineralizing solution at pH-7.0 containing 2-ppm fluoride. The integrated reflectivity was calculated to a depth of 200-µm in the entire lesion area using an automated image processing algorithm. Although a well-defined surface zone was clearly resolved in only a few of the samples that underwent remineralization, the PS-OCT measurements indicated a significant (p<0.05) reduction in the integrated reflectivity between the severity of the lesions that were exposed to the remineralization solution and those that were not. The lesion depth and mineral loss were also measured with polarized light microscopy and transverse microradiography after sectioning the teeth. These results show that PS-OCT can be used to non-destructively monitor the remineralization potential of anti-caries agents in the important pits and fissures of the occlusal surface.

  10. Video monitoring reveals pulsating vents and propagation path of fissure eruption during the March 2011 Pu'u 'Ō'ō eruption, Kilauea volcano

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2017-01-01

    Lava fountains are a common eruptive feature of basaltic volcanoes. Many lava fountains result from fissure eruptions and are associated with the alignment of active vents and rising gas bubbles in the conduit. Visual reports suggest that lava fountain pulses may occur in chorus at adjacent vents. The mechanisms behind such a chorus of lava fountains and the underlying processes are, however, not fully understood. The March 2011 eruption at Pu'u 'Ō'ō (Kilauea volcano) was an exceptional fissure eruption that was well monitored and could be closely approached by field geologists. The fissure eruption occurred along groups of individual vents aligned above the feeding dyke. We investigate video data acquired during the early stages of the eruption to measure the height, width and velocity of the ejecta leaving eight vents. Using a Sobel edge-detection algorithm, the activity level of the lava fountains at the vents was determined, revealing a similarity in the eruption height and frequency. Based on this lava fountain time series, we estimate the direction and degree of correlation between the different vents. We find that the height and velocity of the eruptions display a small but systematic shift in time along the vents, indicating a lateral migration of lava fountaining at a rate of 11 m/s from W to E. This finding is in agreement with a propagation model of a pressure wave originating at the Kilauea volcano and propagating through the dyke at 10 m/s from W to E. Based on this approach from videos only 30 s long, we are able to obtain indirect constraints on the physical dyke parameters, with important implications for lateral magma flow processes at depth. This work shows that the recording and analysis of video data provide important constraints on the mechanisms of lava fountain pulses. Even though the video sequence is short, it allows for the confirmation of the magma propagation direction and a first-order estimation of the dyke dimensions.

  11. The Averno 2 fissure eruption: a recent small-size explosive event at the Campi Flegrei Caldera (Italy)

    NASA Astrophysics Data System (ADS)

    di Vito, Mauro Antonio; Arienzo, Ilenia; Braia, Giuseppe; Civetta, Lucia; D'Antonio, Massimo; di Renzo, Valeria; Orsi, Giovanni

    2011-04-01

    The Averno 2 eruption (3,700 ± 50 a B.P.) was an explosive low-magnitude event characterized by magmatic and phreatomagmatic explosions, generating mainly fall and surge beds, respectively. It occurred in the Western sector of the Campi Flegrei caldera (Campanian Region, South Italy) at the intersection of two active fault systems, oriented NE and NW. The morphologically complex crater area, largely filled by the Averno lake, resulted from vent activation and migration along the NE-trending fault system. The eruption generated a complex sequence of pyroclastic deposits, including pumice fall deposits in the lower portion, and prevailing surge beds in the intermediate-upper portion. The pyroclastic sequence has been studied through stratigraphical, morphostructural and petrological investigations, and subdivided into three members named A through C. Member A was emplaced during the first phase of the eruption mainly by magmatic explosions which generated columns reaching a maximum height of 10 km. During this phase the eruption reached its climax with a mass discharge rate of 3.2 106 kg/s. Intense fracturing and fault activation favored entry of a significant amount of water into the system, which produced explosions driven by variably efficient water-magma interaction. These explosions generated wet to dry surge deposits that emplaced Member B and C, respectively. Isopachs and isopleths maps, as well as areal distribution of ballistic fragments and facies variation of surge deposits allow definition of four vents that opened along a NE oriented, 2 km long fissure. The total volume of magma extruded during the eruption has been estimated at about 0.07 km3 (DRE). The erupted products range in composition from initial, weakly peralkaline alkali-trachyte, to last-emplaced alkali-trachyte. Isotopic data and modeling suggest that mixing occurred during the Averno 2 eruption between a more evolved, less radiogenic stored magma, and a less evolved, more radiogenic magma

  12. Monitoring of the volcanic rock compositions during the 2012-2013 fissure eruption at Tolbachik volcano, Kamchatka

    NASA Astrophysics Data System (ADS)

    Volynets, Anna O.; Edwards, Benjamin R.; Melnikov, Dmitry; Yakushev, Anton; Griboedova, Irina

    2015-12-01

    Here we present the results from monitoring of the composition of rocks produced during the 2012-2013 fissure eruption at Tolbachik volcano (FTE). Major and trace element concentrations in 75 samples are reported. Products of this eruption are represented by high alumina basaltic trachyandesites with higher alkalis and titanium contents than in all previously studied rocks of the Tolbachik monogenetic volcanic field. Rocks erupted during the first three days (27-30 November) from the northern (also called Menyailov) group of vents are the most silica- and alkali-rich (SiO2 concentrations up to 55.35 wt.% and K2O up to 2.67 wt.%). From December onwards, when the eruptive activity switched from the Menyailov vents to the southern (Naboko) group of vents, silica content dropped by 2 wt.%, concentrations of MgO, FeO, TiO2 and Mg# increased, and K2O and Na2O concentrations and K2O/MgO ratio decreased. For the rest of the eruption the compositions of rocks remained constant and homogeneous; no systematic compositional differences between lava, bombs and scoria samples are evident. Trace element distributions in the rocks of the Menyailov and Naboko vent lavas are relatively uniform; Menyailov lavas have slightly higher Th, Nb, Hf, Y, and HREE concentrations than the Naboko vent lavas at more or less constant element ratios. We explain the initial change in geochemistry by tapping of a slightly cooler and fractionated (~ 3% Mt and 8% Cpx) upper part of the magma storage zone before the main storage area began to feed the eruption. Thermodynamic constraints show that apparent liquidus temperatures varied from 1142 °C to 1151 °C, and thermodynamic modeling shows that variations in compositions are consistent with a high degree of low pressure (100-300 MPa), nominally anhydrous fractionation of a parent melt compositionally similar to the 1975 Northern Breakthrough high-Mg basalt. Geochemistry, petrological observations and modeling are in agreement with the newly erupted

  13. Tectono-volcanic control of fissure type vents for the 28 Ma Panalillo ignimbrite in the Villa de Reyes Graben, San Luis Potosí, México.

    NASA Astrophysics Data System (ADS)

    Tristán-González, Margarito; Labarthe-Hernández, Guillermo; Aguirre-Díaz, Gerardo J.; Aguillón-Robles, Alfredo

    2008-10-01

    The volcano-tectonic events at the Villa de Reyes Graben (VRG), in the southern Sierra Madre Occidental, Mexico, include 1) a regional NNE fault system developed before 32 Ma, 2) this pre-32 Ma faulting controlled the emplacement of 31.5 Ma dacitic domes, 3) NE faulting at 28 Ma that displaced the 31.5 Ma dacitic domes and formed the VRG, as well as the oblique grabens of Bledos and Enramadas oriented NW, 4) emplacement of Panalillo ignimbrite at 28 Ma filling the VRG and erupting from fissures related to the oblique grabens, and eruption of Placa basalt apparently also from fault-controlled vents.

  14. Tracking the seismicity preceding and during the March 2010 Fimmvörduháls fissure eruption and April 2010 summit eruption of Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Tarasewicz, J.; Brandsdottir, B.; Hensch, M.; White, R. S.

    2010-12-01

    Using Coalescence Microseismic Mapping (CMM) we have located over 9,000 earthquakes in the period starting two weeks prior to the Fimmvörduháls fissure eruption at the northeastern margin of the Eyjafjallajökull stratovolcano, South Iceland. CMM is an automatic earthquake detection and location program developed at Cambridge University which performs a search in time and space for a best-fit earthquake location. This is done by migrating both P and S wave energy from each seismometer location back into the subsurface and finding an optimum event location where the back-projected energy coalesces within a specified search volume by fitting it to a grid for which P- and S-wave travel times have been calculated from each point in the grid to every seismometer. Following a prolonged period of escalating seismicity we deployed six temporary, three-component, broadband seismometers around the Eyjafjallajökull volcano on 5th March 2010. Data from these seismometers were augmented by data from the eight closest seismometers of the permanent network operated by the Icelandic Meteorological Office (IMO). During March 2010, sustained seismic activity was concentrated primarily between 3-6 km depth under the northeastern flank of the Eyjafjallajökull volcano. To first order, the seismicity migrated eastwards away from the Eyjafjallajökull caldera and towards the first eruption site at Fimmvörduháls during the two weeks prior to eruption. We attribute this to melt movement within the crust. However, clusters in three (or more) discrete locations on the northeastern flank are observed to have been active simultaneously, or with activity alternating between locations, suggesting that magma movement was more complex than a single dyke propagating towards the Fimmvörduháls eruption site. Seismic activity decreased markedly in the two days prior to the onset of the fissure eruption on March 20th. The fissure eruption continued until 12th April and was a pre-cursor to the

  15. Embolization of a Cavernous Sinus Dural Arteriovenous Fistula with Onyx via Direct Puncture of the Cavernous Sinus through the Superior Orbital Fissure

    PubMed Central

    Amiridze, N.; Zoarski, G.; Darwish, R.; Obuchowski, A.; Soloveychic, N.

    2009-01-01

    Summary Treatment of cavernous sinus dural arteriovenous fistula (CSDAVF) may be challenging. We describe a patient who had presented with progressive ocular symptoms due to CSDAVF requiring urgent interventional therapy. Initial attempts to embolize the fistula utilizing a transvenous approach through the inferior petrosal sinus failed because of difficult anatomy. Successful occlusion of the fistula was subsequently achieved with injection of ethylene vinyl alcohol copolymer, Onyx (EV3 Neurovascular, Irvine, CA, USA), via direct percutaneous puncture of the cavernous sinus through the superior orbital fissure. A brief period of asystole during the initial injection of Onyx may be the result of the trigeminocardiac reflex. PMID:20465896

  16. The Alarcón Rise: detail mapping and preliminary results on the geometry, distribution and kinematics of faults and fissures on a ridge-transform system

    NASA Astrophysics Data System (ADS)

    Spelz, R. M.; Fletcher, J. M.; Nieves-Cardoso, C.; Santa Rosa-del Rio, M.; Caress, D. W.; Clague, D. A.; Paduan, J. B.; Martin, J. F.; Guardado-France, R.

    2012-12-01

    The Alarcón Rise, the northernmost segment of the East Pacific Rise before it enters the Gulf of California, is the oldest and perhaps most active spreading ridge-transform system along the oblique-divergent Pacific-North America plate boundary in the southern Gulf of California. Magnetic anomalies along the main ridge axis, which stretches for nearly 50 km long in a NE-SW (034o) direction, suggest that spreading with new oceanic crust was fully established ca. 2.5 Ma, and that its modern configuration as the main plate boundary initiated ca. 2 Ma (Umhoefer, P.J. et al., 2007 Basin Research). High resolution (1m lateral/0.2m vertical) bathymetry data and direct observations of the entire ridge segment, collected and performed by MBARI's autonomous underwater vehicle (AUV) and ROV dives, respectively, during the 2012 Expedition to the Gulf of California, have revealed the presence of an intense array of fault-scarps and fissures displacing numerous neovolcanic landforms such as huge lava domes and smaller cones, pillow mounds and large sheet flows along the entire ridge. The relative age of the surface ruptures is wide-ranging. At some places the fractures appear to be relatively recent, as evident by the apparent young age of the fractured flows, based on having few sessile organisms and/or relatively thin sediment cover. In contrast, fractures and fault-scarps elsewhere are observed to have been partially or totally overrun by lava flows, suggesting their preexistence and relatively older age. The ridge parallel faults and fissures change orientation dramatically as they approach and wrap around the bordering Pescadero and Tamayo fracture zones, which limit the northern and southern flanks of the rise, respectively, giving the ridge a sigmoidal geometry with a Z-shaped symmetry. Moreover, the presence of an en echelon volcanic fissure system near the southern end of the ridge, measuring several kilometers long and oriented somewhat obliquely (~15o clockwise) to

  17. Superior Orbital Fissure Syndrome and Ophthalmoplegia Caused by Varicella Zoster Virus with No Skin Eruption in a Patient Treated with Tumor Necrosis Alpha Inhibitor

    PubMed Central

    Jensen, Helene; Thomsen, Sidsel Thorup; Hansen, Stine Scott; Munksgaard, Signe Bruun; Lindelof, Mette

    2015-01-01

    Varicella zoster virus lies dormant in the dorsal root ganglia after symptomatic chicken pox infection, usually in childhood. If the virus reactivates in the trigeminal ganglia, it can cause varicella zoster ophthalmicus, which can have severe ocular complications. We report a case of a 73-year-old woman in severe immunosuppression due to treatment with mycophenolate mofetil, glucocorticosteroids and a tumor necrosis factor alpha inhibitor. The reactivation caused superior orbital fissure syndrome, which has only rarely been described in relation to varicella zoster virus reactivation. In our case, the syndrome was seen along with severe encephalitis. PMID:26600786

  18. Posterior fossa decompression combined with resection of the cerebellomedullary fissure membrane and expansile duraplasty: a radical and rational surgical treatment for Arnold-Chiari type I malformation.

    PubMed

    Liang, Chen Jian; Dong, Qiu Jian; Xing, You Heng; Shan, Ma; Wen, Lian Xiao; Qiang, Zhong Yuan; Ping, Zhang Qing; Tao, Peng Zhi; Ping, Huang Xiao

    2014-12-01

    This study aims to introduce a new surgical procedure for the treatment of Arnold-Chiari type I malformation (ACM-1) and to compare its effectiveness with the techniques described in previous studies. We performed the following procedures: foramen magnum decompression combined with the removal of both the atlanto-occipital membrane, extended resection of the cerebellomedullary fissure arachnoid membrane, and artificial duraplasty to enlarge the membranic posterior fossa without resecting the cerebellar tonsils and syringosubarachnoid shunting. There were 21 ACM-1 patients: 12 cases had osteo-compression on the cerebellar hemisphere, 18 cases had thickened adhered fabric ring that stretched from arachnoid membrane to cerebellar hemisphere, and 15 cases with syringomyelia. The patients were followed up for 6 months to 3 years after the surgery. All patients showed a remarkable recovery of syringomyelia. There were no morbidity or death related to the surgery. Most of ACM-1 patients, the osteo- and membrane compression on cerebellar hemisphere and tonsil were observed during the operation. Therefore, decompression of foramen magnum and posterior craniocervical combined with the removal of cerebellomedullary fissure arachnoid membrane and placement of an artificial dural graft should be considered as a comprehensive option of minimally invasive surgery and rational and radical treatment of ACM-1. Our experience showed that, by using our procedure, shunting becomes no longer necessary in the treatment of ACM-1-associated syringomyelia.

  19. Can extended photoactivation time of resin-based fissure sealer materials improve ultimate tensile strength and decrease water sorption/solubility?

    PubMed Central

    Borges, Boniek Castillo Dutra; Souza-Júnior, Eduardo José; Catelan, Anderson; Paulillo, Luís Alexandre Maffei Sartini; Aguiar, Flávio Henrique Baggio

    2012-01-01

    Objective: This study aimed to evaluate the impact of extended photoactivation time on ultimate tensile strength (UTS), water sorption (WS) and solubility (WSB) of resin-based materials used as fissure-sealants. Methods: A fissure-sealant (Fluroshield) and a flowable composite (Permaflo) polymerized for 20 and 60 seconds were tested. For UTS, 20 hourglass shaped samples were prepared representing two materials and two photoactivation time (n=5). After 24-h dry-storage, samples were tested in tension using a universal testing machine at a cross-head speed of 0.5 mm/min (UTS was calculated in MPa). For WS and WSB, 20 disks with 5 mm diameter and 1 mm height (n=5) were prepared and volumes were calculated (mm3). They were transferred to desiccators until a constant mass was obtained (m1) and were subsequently immersed in distilled water until no alteration in mass was detected (m2). Samples were reconditioned to constant mass in desiccators (m3). WS and WSB were determined using the equations m2-m3/V and m1-m3/V, respectively. Data were subjected to two-way ANOVA and Tukey’s HSD test (P<.05). Results: There was no significant difference between materials or photoactivation times for the UTS and WS. Permaflo presented lower but negative WSB compared to Fluroshield. Conclusions: Extended photoactivation time did not improve the physical properties tested. Fluroshield presented physical properties that were similar to or better than Permaflo. PMID:23077420

  20. Influence of etching time and bonding strategies on the microshear bond strength of self- and light-cured pit-and-fissure sealants.

    PubMed

    Souza-Junior, Eduardo José; Borges, Boniek Castillo Dutra; Montes, Marcos Antônio Japiassú Resende; Alonso, Roberta Caroline Bruschi; Ambrosano, Glaucia Maria Bovi; Sinhoreti, Mário Alexandre Coelho

    2012-01-01

    This study evaluated the impact of extended etching and bonding strategies on the microshear bond strength of three sealant materials. Two pit-and-fissure sealants [FluroShield, Dentsply (light-cured) and AlphaSeal, DFL (self-cured)] and one light-cured flowable composite resin (Permaflo, Ultradent) were evaluated according to different enamel etching times (15 s or 30 s) and bonding procedures (no adhesive application, application of primer/hydrophobic resin or hydrophobic resin only). Intact enamel blocks were obtained from bovine teeth and sealed via the tested protocols. After 24 h, the microshear bond strength test was performed in a universal testing machine at a crosshead speed of 0.5 mm/min. Failure modes were classified by stereomicroscopy. Data were submitted to a three-way ANOVA and to Tukey's test (α=0.05). There was no statistically significant difference (p>0.05) among the materials. Permaflo showed higher bond strength when etched for 30 s alone. Enamel overetching decreased the bond strength of the light-cured sealant. Primer/bond previous treatment improved bond performance for AlphaSeal. In conclusion, from the tested conditions, all sealant materials presented similar bond strength values in relation to bonding protocol and etching time. The flowable composite can be used as a pit-and-fissure sealant. The use of a three-step adhesive system was essential for the self-cured sealant application.

  1. Remote sensing and petrological observations on the 2012-2013 fissure eruption at Tolbachik volcano, Kamchatka: Implications for reconstruction of the eruption chronology

    NASA Astrophysics Data System (ADS)

    Melnikov, Dmitry; Volynets, Anna O.

    2015-12-01

    We present a reconstruction of the chronological sequence of events that took place during the first days of the 2012-2013 Tolbachik fissure eruption using petrological data and remote sensing methods. We were forced to use this approach because bad weather conditions did not allow direct observations during the first two days of the eruption. We interpreted infrared images from the scanning radiometer VIIRS Suomi NPP and correlated the output with the results of the geochemical study, including comparison of the ash, deposited at the period from 27 to 29 November, with the samples of lava and bombs erupted from the Menyailov and Naboko vents. We argue that the compositional change observed in the eruption products (the decrease of SiO2 concentration and K2O/MgO ratio, increase of MgO concentration and Mg#) started approximately 24 h after the eruption began. At this time the center of activity moved to the southern part of the fissure, where the Naboko group of vents was formed; therefore, this timeframe also characterizes the timing of the Naboko vent opening. The Naboko group of vents remained active until the end of eruption in September 2013.

  2. 3D model of fault and fissures structure of the Kovdor Baddeleyite-Apatite-Magnetite Deposit (NE of the Fennoscandian Shield)

    NASA Astrophysics Data System (ADS)

    Zhirov, Dmitry; Klimov, Sergey

    2015-04-01

    The Kovdor baddeleyite-apatite-magnetite deposit (KBAMD) is represented by a large vertical ore body and is located in the southwestern part of the Kovdor ultramafic-alkaline central-type intrusion. The intrusion represents a concentrically zoned complex of rocks with an oval shape in plan, and straight zoning, which complies with the injection and displacement of each of further magma phases from the center towards the periphery. The operation of the deposit in open pits started in 1962, and nowadays, it has produced over 500,000,000 tons of ore. This is one of the largest open pits in the Kola region, which is ca. 2 km long, 1.8 km wide, and over 400 m deep. Regular structural studies has been carried out since late 1970. A unique massif of spatial data has been accumulated so far to include over 25,000 measurements of fissures and faults from the surface, ca. 20,000 measurements of fissures in the oriented drill core (over 18 km) etc. Using this data base the 3D model of fault and fissures structure was designed. The analysis of one has resulted in the identification of a series of laws and features, which are necessary to be taken into account when designing a deep open pit and mining is carried out. These are mainly aspects concerning the origin, kinematics, mechanics and ratio of spatial extension of various fault systems, variation of their parameters at deep horizons, features of a modern stress field in the country rocks, etc. The 3D model has allowed to divide the whole fracture / fissure systems of the massif rocks into 2 large groups: prototectonic system of joints, including cracks of 'liquid magmatic (carbonatite stage) contraction genesis', and newly formed faults due to the superimposed tectonic stages. With regard to the deposit scale, these are characterized as intraformational and transformational, respectively. Each group shows a set (an assemblage) of fault systems with unique features and signs, as well as regular interconnections. The

  3. Near-Vent, Fissure-Fed Lava Channel Network Morphologies in the Kīlauea December 1974 Flow: Implications for Differentiating Lava Construction From Fluvial Erosion on Planets

    NASA Astrophysics Data System (ADS)

    Bleacher, J. E.

    2015-12-01

    Streamlined islands are often assumed to be the product of erosion by water and are cited as evidence of aqueous flows on Mars. However, lava can build streamlined islands in a manner that is more easily explained by flow thickening followed by partial drainage of preferred lava pathways. Kīlauea's December 1974 (D1974) flow was emplaced as a broad sheet-like flow from a series of en echelon fissures across an older hummocky pāhoehoe tumulus field. The lavas surrounded the tumuli and coalesced to fill a topographic low near the basal scarp of the Koae Fault System. As these obstacles were inundated by the D1974 flow, the lava preferentially cooled around the tumuli to form a higher viscosity zone beneath a smooth crust. Stagnation of these thinner, cooler, and more viscous zones focused the flow into a series of preferred lava pathways located between the stagnant islands. Changes in the local discharge rate disrupted the crust of the flow above the lower viscosity pathways. Older tumuli adjacent to the D1974 flow display the same relief as the flow's islands and uncovered portions of this older flow are exposed at the tops of many islands, supporting an interpretation that islands were anchored by high-standing pre-flow tumuli. As the local lava supply waned, partial drainage of the preferred pathways occurred between the higher-standing surfaces anchored to the older tumuli. The resulting morphology consists of a relatively smooth flow field with thin margins that is dissected by depressed pathways or channels. This morphology resembles an erosional surface incised into a smooth plain, but actually represents an initial constructional process followed by partial drainage within a viscous lava flow. Many other Hawaiian rift zone, fissure-fed flow fields display comparable morphologies in the near vent facies, including islands, terraces, thin flow margins and a lack of well defined topographic levees along channels. Thus, branching channel networks and

  4. Automatic classification of pulmonary peri-fissural nodules in computed tomography using an ensemble of 2D views and a convolutional neural network out-of-the-box.

    PubMed

    Ciompi, Francesco; de Hoop, Bartjan; van Riel, Sarah J; Chung, Kaman; Scholten, Ernst Th; Oudkerk, Matthijs; de Jong, Pim A; Prokop, Mathias; van Ginneken, Bram

    2015-12-01

    In this paper, we tackle the problem of automatic classification of pulmonary peri-fissural nodules (PFNs). The classification problem is formulated as a machine learning approach, where detected nodule candidates are classified as PFNs or non-PFNs. Supervised learning is used, where a classifier is trained to label the detected nodule. The classification of the nodule in 3D is formulated as an ensemble of classifiers trained to recognize PFNs based on 2D views of the nodule. In order to describe nodule morphology in 2D views, we use the output of a pre-trained convolutional neural network known as OverFeat. We compare our approach with a recently presented descriptor of pulmonary nodule morphology, namely Bag of Frequencies, and illustrate the advantages offered by the two strategies, achieving performance of AUC = 0.868, which is close to the one of human experts.

  5. Application of Bistatic TanDEM-X Interferometry to Measure Lava Flow Volume and Lava Extrusion Rates During the 2012-13 Tolbachik, Kamchatka Fissure Eruption

    NASA Astrophysics Data System (ADS)

    Kubanek, J.; Westerhaus, M.; Heck, B.

    2015-12-01

    Aerial imaging methods are a well approved source for mapping lava flows during eruptions and can serve as a base to assess the eruption dynamics and to determine the affected area. However, clouds and smoke often hinder optical systems like the Earth Observation Advanced Land Imager (EO-1-ALI, operated by NASA) to map lava flows properly, which hence affects its reliability. Furthermore, the amount of lava that is extruded during an eruption cannot be determined from optical images - however, it can significantly contribute to assess the accompanying hazard and risk. One way to monitor active lava flows is to quantify the topographic changes over time while using up-to-date high-resolution digital elevation models (DEMs). Whereas photogrammetric methods still fail when clouds and fume obstruct the sight, innovative radar satellite missions have the potential to generate high-resolution DEMs at any time. The innovative bistatic TanDEM-X (TerraSAR-X Add-on for Digital Elevation Measurements) satellite mission enables for the first time generating high-resolution DEMs from synthetic aperture radar satellite data repeatedly with reasonable costs and high resolution. The satellite mission consists of the two nearly identical satellites TerraSAR-X and TanDEM-X that build a large synthetic aperture radar interferometer with adaptable across- and along-track baselines aiming to generate topographic information globally. In the present study, we apply the TanDEM-X data to study the lava flows that were emplaced during the 2012-13 Tolbachik, Kamchatka fissure eruption. The eruption was composed of very fluid lava flows that effused along a northeast-southwest trending fissure. We used about fifteen bistatic data pairs to generate DEMs prior to, during, and after the eruption. The differencing of the DEMs enables mapping the lava flow field at different times. This allows measuring the extruded volume and to derive the changes in lava extrusion over time.

  6. Effect of the application of a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste and adhesive systems on bond durability of a fissure sealant.

    PubMed

    Borges, Boniek Castillo Dutra; Catelan, Anderson; Sasaki, Robson Tetsuo; Ambrosano, Gláucia Maria Bovi; Reis, André Figueiredo; Aguiar, Flávio Henrique Baggio

    2013-01-01

    This study aimed to evaluate the effect of the previous application of a casein phosphopeptide-amorphous calcium phosphate paste (MI Paste, MI) and adhesive systems on the bond durability of a fissure sealant. Ninety-eight enamel blocks were obtained from proximal surfaces of erupted third molars. Specimens were divided into 14 groups (n = 7) according to the previous application of MI (with and without) and the adhesive systems used (no adhesive system; hydrophobic resin of a three-step etch-and-rinse adhesive system; etch-and-rinse single-bottle adhesive system; all-in-one adhesive system; two-step self-etching adhesive system; additional phosphoric acid conditioning and all-in-one adhesive system; additional phosphoric acid conditioning and two-step self-etching adhesive system). A fissure sealant (Fluroshield) was applied and photoactivated for 20 s. Beams (~0.7 mm(2)) were prepared for the microtensile bond strength test, which was executed after 24 h or 6 months of water storage. Fractured specimens were analyzed by scanning electronic microscopy. Data were analyzed by two-way ANOVA with repeated measures/Tukey's test (P < 0.05). Groups that received MI application and adhesive systems presented higher means than those groups where MI was not applied. Higher frequency of cohesive failures was observed for groups with MI. Applying a CPP-ACP containing paste on enamel before adhesive systems was an effective method to increase bond durability of the sealant tested.

  7. Marginal integrity of pit and fissure sealants. Qualitative and quantitative evaluation of the marginal adaptation before and after in vitro thermal and mechanical stressing.

    PubMed

    Stavridakis, Minos M; Favez, Valerie; Campos, Edson A; Krejci, Ivo

    2003-01-01

    This research quantitatively evaluated the marginal adaptation of pit and fissure sealants. The occlusal surfaces of 48 intact, caries-free human molars were cleaned with an air-abrasion unit. The teeth were then randomly divided into eight groups of six teeth each according to the type of enamel conditioning, sealant material applied and curing unit used. After applying either 40% phosphoric acid gel (K-etch, Kuraray Co) or a self-etching primer adhesive system (Clearfil SE Bond, Kuraray Co), sealant materials of two viscosities were applied (Teethmate F-1 and Protect-Liner-F, Kuraray Co) and cured with halogen (Optilux 500, Demetron) or plasma arc (Apollo-95E, Dental & Medical Diagnostic Systems, Ltd) curing units. The marginal adaptation of the pit and fissure sealant restorations was evaluated by using a computer-assisted quantitative margin analysis in a scanning electron microscope (SEM) on epoxy replicas before and after thermal and mechanical stressing of the teeth. The results were statistically analyzed with one-way analysis of variance (ANOVA) at a confidence level of 95% (p=0.05). A post-hoc Tukey HSD-test was used for multiple pairwise comparisons between groups. The null hypothesis was that there was no statistically significant difference between the groups that were tested in this study. The statistically significant differences between groups were more pronounced after loading. In most cases, the self-etching adhesive system (SE Bond) proved as effective as phosphoric acid etching (K-etch). The low viscosity sealant material (Teethmate F-1), in most cases, exhibited better marginal adaptation than the high viscosity material (Protect-Liner F). The high viscosity material performed equally well only when used in combination with the self-etching primer adhesive system as an intermediate layer. The halogen curing unit (Optilux 500) led to better marginal adaptation than the plasma arc curing unit (Apollo 95E), especially after thermal and mechanical

  8. A model study of the pollution effects of the first 3 months of the Holuhraun volcanic fissure: comparison with observations and air pollution effects

    NASA Astrophysics Data System (ADS)

    Steensen, Birthe Marie; Schulz, Michael; Theys, Nicolas; Fagerli, Hilde

    2016-08-01

    The volcanic fissure at Holuhraun, Iceland started at the end of August 2014 and continued for 6 months to the end of February 2015, with an extensive lava flow onto the Holuhraun plain. This event was associated with large SO2 emissions, amounting up to approximately 4.5 times the daily anthropogenic SO2 emitted from the 28 European Union countries, Norway, Switzerland and Iceland. In this paper we present results from EMEP/MSC-W model simulations to which we added 750 kg s-1 SO2 emissions at the Holuhraun plain from September to November (SON), testing three different emission heights. The three simulated SO2 concentrations, weighted with the OMI (Ozone Monitoring Instrument) satellite averaging kernel, are found to be within 30 % of the satellite-observed SO2 column burden. Constraining the SO2 column burden with the satellite data while using the kernel along with the three simulated height distributions of SO2, we estimate that the median of the daily burdens may have been between 13 and 40 kt in the North Atlantic area under investigation. We suggest this to be the uncertainty in the satellite-derived burdens of SO2, mainly due to the unknown vertical distribution of SO2. Surface observations in Europe outside Iceland showed concentration increases up to > 500 µg m-3 SO2 from volcanic plumes passing. Three well identified episodes, where the plume crossed several countries, are compared in detail to surface measurements. For all events, the general timing of the observed concentration peaks compared quite well to the model results. The overall changes to the European SO2 budget due to the volcanic fissure are estimated. Three-monthly wet deposition (SON) of SOx in the 28 European Union countries, Norway and Switzerland is found to be more than 30 % higher in the model simulation with Holuhraun emissions compared to a model simulation with no Holuhraun emissions. The largest increases, apart from extreme values on Iceland, are found on the coast of northern

  9. Retention of a resin-based sealant and a glass ionomer used as a fissure sealant in children with special needs

    PubMed Central

    Nualart-Grollmus, Zacy-Carola

    2014-01-01

    Objectives: The aim of this research is to evaluate the retention of sealants of resin and resin-modified ionomeric glass pits and fissures, on first permanent molars of special patients. Material and Methods: The sample was comprised by 32 children. The ages were between 7 and 18 years. The sealing procedure was made with the relative isolation of the molars to be sealed, through the use of cotton rolls. Two molars were sealed with Clinpro Sealant 3M Dental and the others with Vitremer. Checking of the sealants was made after 3 and 6 months of their placement, evaluating with 3 values: TR: Totally Restrained; PR: Partially Restrained; and CL: Completely Lost. Results: 67.18% of the resinous sealants, and 70.31% of the glass ionomer sealants were successful after three months. After six months, 57.81% of the resin-based sealants and 51.56% of the glass ionomer sealants were successful. When performing the Chi-square statistical analysis (P<0.05) no statistical significance was observed after 6 months. Conclusions: The retention of the resin sealant was similar to that of the glass ionomer cement at the end of six months and the retention of sealants on maxillary teeth was higher than on mandibular teeth. Key words:Sealant, glass ionomer, retention, caries, special needs. PMID:25674325

  10. [Femoropopliteal bypass above the knee-joint fissure by means of a vascular prosthesis made of PTFE: choosing an appropriate diameter of the prosthesis].

    PubMed

    Pokrovskiĭ, A V; Dan, V N; Zotikov, A E; Chupin, A V; Shubin, A A; Bogatov, Iu P; Tedeev, A K

    2007-01-01

    Presented herein are the outcomes of a total of 80 operations of femoropopliteal grafting above the knee-joint fissure, carried out using a vascular prosthesis made of polytetrafluoroethylene (PTFE) in patients diagnosed with atherosclerotic lesions of the arteries of the lower extremities over the period between February 1995 and December 2005 at the Department of Vascular Surgery of the A. V. Vishnevsky Institute of Surgery of the Russian Academy of Medical Sciences. Fifty percent of the patients were operated on for grade II B ischemia, while 13.7% of the patients suffered from grade III ischaemia of the lower limb, and 29 (36.3%) subjects were found to have grade IV ischaemia. The condition of the distal bed was considered in 41.2% of the patients, being defined as in 48.5%, and as "poor" in 10.3%. The operative intervention was carried out according to the conventionally accepted technique. 50% of the reconstructions were performed using the prosthesis 8 mm in diameter, and 50% - using that measuring 6 mm in diameter. A statistically significant impact of the diameter of the prosthesis used on the patency of the graft in the remote postoperative period was revealed: with the prosthesis 8-mm in diameter, the patency after 12, 30 and 60 months amounted to 93%, 64% and 51%, respectively, while with the transplant measuring 6 mm in diameter, these indices at the above-mentioned time intervals did not exceed 62%, 44% and 31%, respectively (P=0.004).

  11. Staged liver resection for perihilar liver tumors using a tourniquet in the umbilical fissure and sequential portal vein embolization on the fourth postoperative day (a modified ALTPS).

    PubMed

    Robles Campos, Ricardo; Brusadin, Roberto; López Conesa, Asunción; Parrilla Paricio, Pascual

    2014-12-01

    Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) achieves the hypertrophy of the future liver remnant in seven days. We achieved the same hypertrophy placing a tourniquet in the parenchimal transection line associating a right portal vein ligation (associating liver tourniquet and right portal vein ligation for staged hepatectomy-ALTPS). In perihiliar tumors a«non touch» technique should be performed. ALPPS y ALTPS do not comply with this technical aspect because a dissection of the hilum is carried out in both procedures during the portal dissection. To avoid this problem we devised a new method called sequential ALTPS. It consists of placing a tourniquet in the umbilical fissure without ligation of the right portal vein during the first stage. Subsequently, on the 4(th) postoperative day we perform a percutaneous right portal vein embolization. We present the first case of this new technique in which we have obtained a hypertrophy of 77% of the future liver remnant seven days after portal vein embolization. In the second stage a right trisectionectomy was performed with inferior vena cava resection with a goretex graft replacement.

  12. Maintenance Therapy with Partially Hydrolyzed Guar Gum in the Conservative Treatment of Chronic Anal Fissure: Results of a Prospective, Randomized Study

    PubMed Central

    Izzo, Giuseppe; Di Martino, Natale; Renzi, Adolfo

    2014-01-01

    Purpose. This study was designed to evaluate the role of maintenance therapy with partially hydrolyzed guar gum (PHGG) after topical application of glyceryl trinitrate (GTN) in the conservative treatment of chronic anal fissure (CAF). Methods. From all the patients with CAF observed during the study period, 165 subjects with healed CAF after standard therapy with topical GTN 0.4% ointment were randomized to receive (group II) or not (group I) maintenance therapy with PHGG for 10 months. Clinical and manometric followup was carried out 6 and 12 months after treatment. Results. At six-month followup, median visual analogue scale score was significantly higher in group I if compared with group II. The success and recurrence rate at 12-month followup were, respectively, 38.3% (28/73) in group I versus 58.5% (41/70) in group II (P = 0.019; Fisher's exact test) and 30.2% (13/43) in group I versus 14.5% (7/48) in group II (P = 0.0047; Fisher's exact test). Conclusion. The maintenance therapy with PHGG in patients with healed CAF after chemical sphincterotomy by topical application of GTN 0.4% ointment seems associated with a significant reduction of recurrence rate and with a significant increase of success rate at 12-month followup. PMID:25089280

  13. Surgical Simulation of Extradural Anterior Clinoidectomy through the Trans-superior Orbital Fissure Approach Using a Dissectable Three-dimensional Skull Base Model with Artificial Cavernous Sinus.

    PubMed

    Mori, Kentaro; Yamamoto, Takuji; Nakao, Yasuaki; Esaki, Takanori

    2010-07-01

    Extradural anterior clinoidectomy via the trans-superior orbital fissure (SOF) approach can provide extensive exposure of the anterior clinoid process and safe drilling under direct view. This technique requires peeling of the dura propria of the temporal lobe from the lateral wall of the SOF. Therefore, cadaveric dissection is mandatory to acquire surgical technique. However, chances for cadaveric dissection are limited. We propose modification of our three-dimensional (3-D) skull base model made from surgically dissectable artificial bone with artificial cavernous sinus including multiple membranous layers and neurovascular structures to simulate extradural anterior clinoidectomy via the trans-SOF approach. The 3-D skull base model precisely reproduced the dura propria of the temporal lobe, periosteal bridge, and inner reticular layer in the cavernous sinus and SOF using silicone and varnish. The cranial nerves and blood vessels were made from rubber fibers and vinyl tube. Simulation of extradural anterior clinoidectomy via the trans-SOF approach could be performed on the model using a high-speed drill under the operating microscope. The steps of reconstruction of the skull base model and dissection promote clear understanding of the 3-D anatomy and techniques of extradural anterior clinoidectomy via the trans-SOF approach.

  14. Assessing Age-Related Ossification of the Petro-Occipital Fissure: Laying the Foundation for Understanding the Clinicopathologies of the Cranial Base

    PubMed Central

    BALBONI, ARMAND L.; ESTENSON, THOMAS L.; REIDENBERG, JOY S.; BERGEMANN, ANDREW D.; LAITMAN, JEFFREY T.

    2005-01-01

    The petro-occitpital fissure (POF) lies within a critical interface of cranial growth and development in the posterior cranial fossa. The relationships between skeletal and soft tissues make this region especially important for examining biomechanical and basic biologic forces that may mold the cranial base and contribute to significant clinicopathologies associated with the structures located near the POF. Therefore, this study investigates the POF in adults in both preserved human cadavers and dried crania in order to determine if developmental changes can be observed and, if so, their value in age assessment as a model system for describing normal morphogenesis of the POF. This study demonstrates that tissue within the POF undergoes characteristic changes in ossification with age, the onset of which is considerably later than that of other synchondroses of the cranial base. Statistically, there is a moderate to strong correlation between age and stage of ossification within the POF. Further, male crania were observed to reach greater degrees of ossification at a younger age than female crania and that individual asymmetry in ossification of the tissue within the POF was not uncommon. An understanding of the basic temporal biological processes of the POF may yield insight into the development of clinicopathologies in this region of the cranial base. PMID:15584035

  15. Possible evidence for on-going volcanism on Mars as suggested by thin, elliptical sheets of low-albedo particulate material around pits and fissures close to Cerberus Fossae

    NASA Astrophysics Data System (ADS)

    Roberts, Gerald Patrick; Crawford, Ian A.; Peacock, David; Vetterlein, Joyce; Parfitt, Elisabeth; Bishop, Louise

    2007-10-01

    We describe 100 200 metre-sized low-albedo haloes from Mars Orbiter Camera (MOC) images, located around sunken pits in the vicinity of Cerberus Fossae, Mars, a fissure-vent system that has been suggested to have been volcanically active within the last few million years. Two types of pit have been identified: (1) lenticular/elongate pits located on the floors of fissures/graben, some of which lead to the summit of a volcano; (2) sub-circular pits, lacking the raised rims expected of impact craters, located either within small lava flows, along fissures, or on flat, cratered plains. The low-albedo haloes encircle the pits, and are in places asymmetric in plan-view, exhibiting almost perfect elliptical outlines with low-aspect ratios, and lightening in appearance towards the margins of the ellipses. Thermal Emission Imaging System (THEMIS) images suggest the haloes are dark particulate deposits. These deposits bury impact craters to a depth of less than a few decimetres. We argue that the elliptical haloes may be mineral precipitates and/or particulate deposits from ballistic volcanic eruptions that have been disrupted by the wind. They are likely be extremely young because <1m thick, low-albedo sedimentary deposits elsewhere on Mars have been observed to disappear in a few tens of years due to deposition of high-albedo dust.

  16. Investigating Alpine fissure rutilated quartz to constrain timing and conditions of post-metamorphic hydrothermal fluid flow

    NASA Astrophysics Data System (ADS)

    Shulaker, D. Z.; Schmitt, A. K.; Zack, T.; Bindeman, I. N.

    2013-12-01

    Rutilated quartz, aka Venus' hair, is finely-acicular rutile intergrown with host quartz generated by fluid-mediated co-crystallization. It is commonly found in hydrothermal veins, including the renown cleft mineral locations of the Swiss Alps. Previous studies of Alpine cleft mineralizations used rare hydrothermal monazite [1] and titanite [2] to constrain vein formation to ~13.5-15.2 Ma, postdating peak metamorphism by ~2-4 Ma. Temperature (T) estimates of 150-450°C are based on fluid inclusions and bulk quartz-mineral oxygen isotope exchange equilibria, and formation pressures (P) are 0.5-2.5 kbar (for a geothermal gradient of 30°C/km) [2]. The potential of rutilated quartz as a thermochronometer, however, has not been harnessed previously. Here, we present the first results of age and P-T determinations for rutilated quartz from six locations in the Swiss Alps (San Gottardo; Feldbach, Binntal; Pi Aul, Vals; Faido, Leventina; Elm, Steinbach; Binntal). Samples were cut and mounted in epoxy discs to expose rutile (0.03 to 1 mm in diameter) and its host quartz which was also imaged in cathodoluminescence (CL). CL images for half of the samples' host quartz exhibited strong sector zoning, while others reveal only weak CL zonation. Isotopic and trace element analyses were carried out by SIMS using a CAMECA ims1270 for U-Pb, O-isotopes, and Ti-in-quartz, and a LA-ICP-MS system (213 nm New Wave laser coupled to an Agilent 7500a) for Zr-in-rutile. U-Pb rutile ages average 15.5×2.0 Ma (2σ). T estimates are 352-575°C (rutile-quartz oxygen isotopes in touching domains), 470-530°C (Zr-in-rutile assuming P = 0.5 and equilibrium with host-rock zircon), and 251-391°C (Ti-in-quartz at assumed P = 0.5 kbar and aTiO2 = 1). CL zones are isotopically unzoned. Rutile-quartz oxygen isotopes are pressure insensitive, whereas Zr-in-rutile and Ti-in-quartz are minimum temperatures. These results demonstrate that rutilated quartz can constrain timing and conditions of post

  17. Computed Tomography- and Magnetic Resonance Image-based Analysis of the Anatomical Variations of the Sylvian Fissure and Characteristics of the Middle Cerebral Artery

    PubMed Central

    Maslehaty, Homajoun; Deuschl, Cornelius; Kleist, Bernadette; Göricke, Sophia; Sure, Ulrich; Müller, Oliver

    2017-01-01

    The aim of this cross sectional anatomical study is to determine the distribution of the defined anatomical variations of the Sylvian fissure (SF) in a normal population and to analyze its bilateral superposable presentation. Furthermore, we examined the course of the middle cerebral artery (MCA) and the division of the MCA branches in relation to the SF types. A total of 300 cranial CT scans - 100 CT angiography datasets and 86 MRIs of patients without intracranial pathologies - were reviewed. The SF was categorized in five types based on Yasargils description and our previous publication. The length, diameter and branches of the MCA were measured and compared to the SF types. SPSS 23.0 for Windows® was used for statistical analysis. We analyzed data of 300 patients (171 male, 129 female; mean age 51.6years). Symmetric and mirror-imaged coherence of the SF was found in 266 patients (88.7%, χ2(8)=3.04, p=0.932). The distribution of the SF types showed significant differences in patients younger than 60 years compared to older patients. A bifurcation was observed in 72.0%. A trifurcation was observed in 12.0% and a false bifurcation in 16.0% of patients. There was no significant difference of the measured diameters or length of the M1 segments according to the SF types. In this CT and MRI based anatomical study we could show that a twisted and narrow SF occurred more frequently in patients younger than 60 years of age. The SF has a high congruence intra-individually. The anatomical condition might influence the size and configuration of the proximal MCA, which in turn might influence the surgeon’s choice of the approach to the SF. Preoperative evaluation on the basis of the presented data, may help to decide for an appropriate approach to the SF. PMID:28243427

  18. Computed Tomography- and Magnetic Resonance Image-based Analysis of the Anatomical Variations of the Sylvian Fissure and Characteristics of the Middle Cerebral Artery.

    PubMed

    Maslehaty, Homajoun; Deuschl, Cornelius; Kleist, Bernadette; Göricke, Sophia; Sure, Ulrich; Müller, Oliver

    2017-01-11

    The aim of this cross sectional anatomical study is to determine the distribution of the defined anatomical variations of the Sylvian fissure (SF) in a normal population and to analyze its bilateral superposable presentation. Furthermore, we examined the course of the middle cerebral artery (MCA) and the division of the MCA branches in relation to the SF types. A total of 300 cranial CT scans - 100 CT angiography datasets and 86 MRIs of patients without intracranial pathologies - were reviewed. The SF was categorized in five types based on Yasargils description and our previous publication. The length, diameter and branches of the MCA were measured and compared to the SF types. SPSS 23.0 for Windows® was used for statistical analysis. We analyzed data of 300 patients (171 male, 129 female; mean age 51.6years). Symmetric and mirror-imaged coherence of the SF was found in 266 patients (88.7%, χ(2)(8)=3.04, p=0.932). The distribution of the SF types showed significant differences in patients younger than 60 years compared to older patients. A bifurcation was observed in 72.0%. A trifurcation was observed in 12.0% and a false bifurcation in 16.0% of patients. There was no significant difference of the measured diameters or length of the M1 segments according to the SF types. In this CT and MRI based anatomical study we could show that a twisted and narrow SF occurred more frequently in patients younger than 60 years of age. The SF has a high congruence intra-individually. The anatomical condition might influence the size and configuration of the proximal MCA, which in turn might influence the surgeon's choice of the approach to the SF. Preoperative evaluation on the basis of the presented data, may help to decide for an appropriate approach to the SF.

  19. Nitroglycerin 0.4% ointment vs placebo in the treatment of pain resulting from chronic anal fissure: a randomized, double-blind, placebo-controlled study

    PubMed Central

    2013-01-01

    Background Complications of chronic anal fissure (CAF) treatments are prompting interest in lower-risk therapies. This study was conducted to compare nitroglycerin (NTG) 0.4% ointment with placebo for pain associated with CAF. Methods In this randomized, double-blind, placebo-controlled trial, patients with one CAF and moderate-to-severe pain (≥50 mm on a 100 mm visual analog scale [VAS]) received 375 mg NTG 0.4% (1.5 mg active ingredient) or 375 mg placebo ointment applied anally every 12 hours for 21 days. The primary end point was change from baseline VAS score in 24-hour pain averaged over days 14–18. Review of data from patients who withdrew early was blinded to treatment. To control for the confounding effects of analgesics, all patients received 650 mg acetaminophen for headache prophylaxis before each application. Results A total of 247 patients were enrolled (NTG, n = 123; placebo, n = 124). The prespecified baseline observation carried forward (BOCF) analysis found no significant difference between groups; however, a last observation carried forward (LOCF) analysis showed a significant advantage for NTG. A post hoc analysis (LOCF/BOCF hybrid) demonstrated a significant adjusted mean difference of −7.0 mm in favor of NTG 0.4% (95% CI −13.6, –0.4; P = .038). Headache was the most common adverse event in the NTG (69.9%) and placebo (47.6%) groups. Conclusions This was the first placebo-controlled study that also controlled for the confounding effects of analgesics used to treat NTG-induced headache. In patients with moderate-to-severe CAF pain, NTG 0.4% ointment effectively reduced CAF pain compared with placebo. Trial registration ClinicalTrials.gov, NCT00522041 PMID:23815124

  20. Microsurgical management of pediatric ependymomas of the fourth ventricle via the trans-cerebellomedullary fissure approach: A review of 26 cases

    PubMed Central

    QIU, BO; WANG, YONG; WANG, WEI; WANG, CHAO; WU, PENGFEI; BAO, YIJUN; OU, SHAOWU; GUO, ZONGZE; WANG, YUNJIE

    2016-01-01

    In the present study, the microsurgical management of 26 ependymomas of the fourth ventricle in children via the trans-cerebellomedullary fissure (CMF) approach was reviewed and evaluated. Clinical data were obtained from 26 ependymomas of the fourth ventricle treated with microsurgery using the trans-CMF approach from March 2006 to September 2010 at the Department of Neurosurgery of The First Affiliated Hospital of China Medical University (Shenyang, China). These data were collected and analyzed. Suboccipital median posterior fossa craniotomy and trans-CMF approach were performed in all cases for the microsurgical removal of the tumors. An additional incision was performed in the inferior medullary velum of 5 patients, in order to obtain adequate exposure of the tumors. As a result, all tumors were well exposed during surgery. Gross total resection (GTR) was achieved in 22 cases, near total resection (NTR) in 3 cases and subtotal resection (STR) in 1 case. All excised tumors were pathologically confirmed. No mortality occurred intraoperatively, and no patient presented with mutism or any other surgery-related complications. One patient suffered from postoperative hydrocephalus and received ventriculoperitoneal shunting, which relieved the symptoms. Over the 3.0–7.5-year follow-up period (mean, 4.8 years), tumor relapse occurred in 1 case with GTR, 2 cases with NTR and 1 case with STR. In total, 3 patients succumbed to tumor relapse and 4 were lost to follow-up. According to the literature and the clinical experience of the present authors, the trans-CMF approach provides safe and sufficient access to the fourth ventricle without the requirement of an incision in the inferior vermis. This approach prevents damage to the normal cerebellum and improves the surgical outcome. Tumor removal, restoration of cerebrospinal fluid circulation and preservation of brainstem function are factors that should be taken into consideration during surgery. For patients with

  1. Galaxy formation

    SciTech Connect

    Silk, J.

    1984-11-01

    Implications of the isotropy of the cosmic microwave background on large and small angular scales for galaxy formation are reviewed. In primeval adiabatic fluctuations, a universe dominated by cold, weakly interacting nonbaryonic matter, e.g., the massive photino is postulated. A possible signature of photino annihilation in our galactic halo involves production of cosmic ray antiprotons. If the density is near its closure value, it is necessary to invoke a biasing mechanism for suppressing galaxy formation throughout most of the universe in order to reconcile the dark matter density with the lower astronomical determinations of the mean cosmological density. A mechanism utilizing the onset of primordial massive star formation to strip gaseous protogalaxies is described. Only the densest, early collapsing systems form luminous galaxies. (ESA)

  2. Comet formation

    NASA Astrophysics Data System (ADS)

    Blum, J.

    2014-07-01

    There has been vast progress in our understanding of planetesimal formation over the past decades, owing to a number of laboratory experiments as well as to refined models of dust and ice agglomeration in protoplanetary disks. Coagulation rapidly forms cm-sized ''pebbles'' by direct sticking in collisions at low velocities (Güttler et al. 2010; Zsom et al. 2010). For the further growth, two model approaches are currently being discussed: (1) Local concentration of pebbles in nebular instabilities until gravitational instability occurs (Johansen et al. 2007). (2) A competition between fragmentation and mass transfer in collisions among the dusty bodies, in which a few ''lucky winners'' make it to planetesimal sizes (Windmark et al. 2012a,b; Garaud et al. 2013). Predictions of the physical properties of the resulting bodies in both models allow a distinction of the two formation scenarios of planetesimals. In particular, the tensile strength (i.e, the inner cohesion) of the planetesimals differ widely between the two models (Skorov & Blum 2012; Blum et al. 2014). While model (1) predicts tensile strengths on the order of ˜ 1 Pa, model (2) results in rather compactified dusty bodies with tensile strengths in the kPa regime. If comets are km-sized survivors of the planetesimal-formation era, they should in principle hold the secret of their formation process. Water ice is the prime volatile responsible for the activity of comets. Thermophysical models of the heat and mass transport close to the comet-nucleus surface predict water-ice sublimation temperatures that relate to maximum sublimation pressures well below the kPa regime predicted for formation scenario (2). Model (1), however, is in agreement with the observed dust and gas activity of comets. Thus, a formation scenario for cometesimals involving gravitational instability is favored (Blum et al. 2014).

  3. Coil therapy for patients with severe emphysema and bilateral incomplete fissures – effectiveness and complications after 1-year follow-up: a single-center experience

    PubMed Central

    Kontogianni, Konstantina; Gerovasili, Vasiliki; Gompelmann, Daniela; Schuhmann, Maren; Hoffmann, Hans; Heussel, Claus Peter; Herth, Felix JF; Eberhardt, Ralf

    2017-01-01

    Background Lung volume reduction coil (LVRC) treatment is established in daily endoscopic lung volume reduction routine. The aim of this study was to evaluate the safety and efficacy of LVRC treatment. Patients and methods This was a retrospective analysis of 86 patients (male/female: 40/46, mean age: 64±7 years) with severe COPD and bilateral incomplete fissures. A total of 10 coils were unilaterally implanted in a single lobe, and 28 out of 86 patients were treated bilaterally. At 90-, 180-, and 365-day follow-up, changes in pulmonary function test (PFT), 6-minute walk test (6MWT) and modified Medical Research Council (mMRC) dyspnea scale, as well as possible complications, were recorded. Results At 90 days, the forced expiratory volume in 1 second did improve (P<0.001), but the improvement was not sustained at the 180- and 365-day follow-up (baseline: 0.71±0.21 vs 0.77±0.23 vs 0.73±0.22 vs 0.70±0.18 L). Both vital capacity and residual volume improved significantly (P<0.001) at the 90- and 180-day follow-up, but the improvement was lost after 365 days. Total lung capacity decreased at the 90-day follow-up but returned to baseline values at the 180- and 365-day follow-up. 6MWT (P=0.01) and mMRC (P=0.007) also improved at 90 and 180 days (Δ6MWT of 31±54 and 20±60 m, respectively), but the improvement was also lost at the 365-day follow-up. No significant further improvement was evident at any point in the follow-up after the second procedure. A total of 4 out of 86 patients passed away due to complications. Significant complications in the first 3 months and then at 12 months included the following: severe hemoptysis in 4 (3.5%) and 4 (3.5%) patients, pneumonia requiring hospitalization in 32 (28.1%) and 9 (7.9%) patients and pneumothorax in 7 (6.1%) and 2 (1.7%) patients, respectively. Milder adverse events included self-limited hemoptysis, pneumonias, or COPD exacerbations treated orally. Conclusion LVRC improved PFT, 6MWT and mMRC initially, but the

  4. Cloud Formation

    NASA Astrophysics Data System (ADS)

    Graham, Mark Talmage

    2004-05-01

    Cloud formation is crucial to the heritage of modern physics, and there is a rich literature on this important topic. In 1927, Charles T.R. Wilson was awarded the Nobel Prize in physics for applications of the cloud chamber.2 Wilson was inspired to study cloud formation after working at a meteorological observatory on top of the highest mountain in Scotland, Ben Nevis, and testified near the end of his life, "The whole of my scientific work undoubtedly developed from the experiments I was led to make by what I saw during my fortnight on Ben Nevis in September 1894."3 To form clouds, Wilson used the sudden expansion of humid air.4 Any structure the cloud may have is spoiled by turbulence in the sudden expansion, but in 1912 Wilson got ion tracks to show up by using strobe photography of the chamber immediately upon expansion.5 In the interim, Millikan's study in 1909 of the formation of cloud droplets around individual ions was the first in which the electron charge was isolated. This study led to his famous oil drop experiment.6 To Millikan, as to Wilson, meteorology and physics were professionally indistinct. With his meteorological physics expertise, in WWI Millikan commanded perhaps the first meteorological observation and forecasting team essential to military operation in history.7 But even during peacetime meteorology is so much of a concern to everyone that a regular news segment is dedicated to it. Weather is the universal conversation topic, and life on land could not exist as we know it without clouds. One wonders then, why cloud formation is never covered in physics texts.

  5. New volcanogenic-eruptive genetic type of diamond occurrence (based on studying the 2012-2013 Fissure Tolbachik Eruption in Kamchatka)

    NASA Astrophysics Data System (ADS)

    Karpov, Gennady; Anikin, Leonid; Filatov, Stanislav; Silaev, Valery; Petrovsky, Vitaly; Zolotarev, Andrey; Dunin-Barkovsky, Romuald; Volynets, Anna

    2014-05-01

    During the 2012-2013 Fissure Tolbachik eruption, diamonds were found both in fresh pyroclastics and in the effusive lava pores. Lavas are aphyric and subaphyric porous aluminous basaltic trachyandesites with rare megacrysts and subphenocrysts of plagioclase, olivine and pyroxene. Groundmass is hyalopilitic, pilotaxitic, occasionally hyaline, with abundant plagioclase microlites. So far, over 750 diamond grains have been found sized mostly 100-500 mkm. Generally, grains are well formed isometric, plane-faced and sharp-edged monocrystals of cubic-octahedral habit and green color, rarer colorless. Faces of rhombic-dodecahedron, tetragonal-trisoctahedron and trigonal-trisoctahedron also occur. Crystal cubic faces host pits of diffusive depletion, and pits with induction surfaces formed after the breakoff of syngenetic inclusions. Octahedral faces often show pyramidal etching pits formed at the dislocation outcrops. Pits contain coatings whose composition includes Fe, Mg, Ca, Si, and Cu-Sn (Zn) alloy films. Diamond X-ray diffraction data (Bruker APEX DUO, STOE IPDS II, MoKα-radiation, 788 reflections) show space group Fd-3m, cubic unit cell parameter a = 3.574(3) A and major reflections (111), (220), (311) etc. at Gandolfi pattern. Raman spectra with red beam reveal only one strong line at 1332 cm-1 typical for diamonds. Spectra excited by the 785 nm beam reveal a wide line with the peak at 1370 cm-1, whose intensity oscillates from 1% to 70% of the diamond line intensity at 1332 cm-1. Infrared absorption spectra reflect two lines with peaks at 1345 and 1130 cm-1, corresponding to structural C-defects (isolated N atoms). Partially, these defects occur in the positive charge state - N+. Structural nitrogen concentration in the form of C-defects varies from 150 to 500 ppm, while that in the form of N+ - from 10 to 30 ppm. Lines of infrared absorption on A and B1 nitrogen defects, as well as those on hydrogen defects typical for most natural diamonds, are not detected for

  6. Amphiplex Formation

    NASA Astrophysics Data System (ADS)

    Petersen, Shannon; Laaser, Jennifer; Lodge, Timothy

    2015-03-01

    Polymer-micelle complexes are currently under heavy investigation due to their potential applications in targeted drug delivery and gene therapy, yet the dynamics of the complex formation is still relatively unstudied. By varying the ratios of poly(styrene sulfonate) chains and cationic poly(dimethylaminoethyl methacrylate)-b-poly(styrene) micelles and the ionic strength of the system, we created a variety of complex configurations of different sizes and charges. The complexes were characterized dynamic light scattering and zeta potential measurements which provided information regarding the hydrodynamic radius, distribution of sizes, and effective charge.

  7. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Fonda, Mark (Technical Monitor)

    2002-01-01

    Modern theories of star and planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. The most detailed models of planetary growth are based upon observations of planets and smaller bodies within our own Solar System and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed, and the methods that are being used and planned for detecting and characterizing extrasolar planets are reviewed.

  8. Macro-permeability distribution and anisotropy in a 3D fissured and fractured clay rock: ‘Excavation Damaged Zone’ around a cylindrical drift in Callovo-Oxfordian Argilite (Bure)

    NASA Astrophysics Data System (ADS)

    Ababou, Rachid; Cañamón Valera, Israel; Poutrel, Adrien

    The Underground Research Laboratory at Bure (CMHM), operated by ANDRA, the French National Radioactive Waste Management Agency, was developed for studying the disposal of radioactive waste in a deep clayey geologic repository. It comprises a network of underground galleries in a 130 m thick layer of Callovo-Oxfordian clay rock (depths 400-600 m). This work focuses on hydraulic homogenization (permeability upscaling) of the Excavation Damaged Zone (EDZ) around a cylindrical drift, taking into account: (1) the permeability of the intact porous rock matrix; (2) the geometric structure of micro-fissures and small fractures synthesized as a statistical set of planar discs; (3) the curved shapes of large ‘chevron’ fractures induced by excavation (periodically distributed). The method used for hydraulic homogenization (upscaling) of the 3D porous and fractured rock is based on a ‘frozen gradient’ superposition of individual fluxes pertaining to each fracture/matrix block, or ‘unit block’. Each unit block comprises a prismatic block of permeable matrix (intact rock) obeying Darcy’s law, crossed by a single piece of planar fracture obeying either Darcy or Poiseuille law. Polygonal as well as disc shaped fractures are accommodated. The result of upscaling is a tensorial Darcy law, with macro-permeability K ij( x) distributed over a grid of upscaling sub-domains, or ‘voxels’. Alternatively, K ij( x) can be calculated point-wise using a moving window, e.g., for obtaining permeability profiles along ‘numerical’ boreholes. Because the permeable matrix is taken into account, the upscaling procedure can be implemented sequentially, as we do here: first, we embed the statistical fissures in the matrix, and secondly, we embed the large curved chevron fractures. The results of hydraulic upscaling are expressed first in terms of ‘equivalent’ macro-permeability tensors, K ij( x, y, z) distributed around the drift. The statistically isotropic fissures are

  9. Habit formation

    PubMed Central

    Smith, Kyle S.; Graybiel, Ann M.

    2016-01-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network. PMID:27069378

  10. Habit formation.

    PubMed

    Smith, Kyle S; Graybiel, Ann M

    2016-03-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network.

  11. Barrier Formation

    PubMed Central

    Lyaruu, D.M.; Medina, J.F.; Sarvide, S.; Bervoets, T.J.M.; Everts, V.; DenBesten, P.; Smith, C.E.; Bronckers, A.L.J.J.

    2014-01-01

    Enamel fluorosis is an irreversible structural enamel defect following exposure to supraoptimal levels of fluoride during amelogenesis. We hypothesized that fluorosis is associated with excess release of protons during formation of hypermineralized lines in the mineralizing enamel matrix. We tested this concept by analyzing fluorotic enamel defects in wild-type mice and mice deficient in anion exchanger-2a,b (Ae2a,b), a transmembrane protein in maturation ameloblasts that exchanges extracellular Cl− for bicarbonate. Defects were more pronounced in fluorotic Ae2a,b−/− mice than in fluorotic heterozygous or wild-type mice. Phenotypes included a hypermineralized surface, extensive subsurface hypomineralization, and multiple hypermineralized lines in deeper enamel. Mineral content decreased in all fluoride-exposed and Ae2a,b−/− mice and was strongly correlated with Cl−. Exposure of enamel surfaces underlying maturation-stage ameloblasts to pH indicator dyes suggested the presence of diffusion barriers in fluorotic enamel. These results support the concept that fluoride stimulates hypermineralization at the mineralization front. This causes increased release of protons, which ameloblasts respond to by secreting more bicarbonates at the expense of Cl− levels in enamel. The fluoride-induced hypermineralized lines may form barriers that impede diffusion of proteins and mineral ions into the subsurface layers, thereby delaying biomineralization and causing retention of enamel matrix proteins. PMID:24170372

  12. Pattern Formation

    NASA Astrophysics Data System (ADS)

    Hoyle, Rebecca

    2006-03-01

    From the stripes of a zebra and the spots on a leopard's back to the ripples on a sandy beach or desert dune, regular patterns arise everywhere in nature. The appearance and evolution of these phenomena has been a focus of recent research activity across several disciplines. This book provides an introduction to the range of mathematical theory and methods used to analyse and explain these often intricate and beautiful patterns. Bringing together several different approaches, from group theoretic methods to envelope equations and theory of patterns in large-aspect ratio-systems, the book also provides insight behind the selection of one pattern over another. Suitable as an upper-undergraduate textbook for mathematics students or as a fascinating, engaging, and fully illustrated resource for readers in physics and biology, Rebecca Hoyle's book, using a non-partisan approach, unifies a range of techniques used by active researchers in this growing field. Accessible description of the mathematical theory behind fascinating pattern formation in areas such as biology, physics and materials science Collects recent research for the first time in an upper level textbook Features a number of exercises - with solutions online - and worked examples

  13. An unusual constellation of congenital malformations in a single patient including partial anomalous pulmonary venous return, persistent left superior vena cava, aberrant pulmonary fissure, anomalous aortic arch, tracheal diverticulum and annular pancreas.

    PubMed

    Lapa, T; Vedelago, J; Kim, H; Patrick, E

    2014-10-31

    We report a case of a male patient with a constellation of rare congenital anomalies consisting of: partial anomalous pulmonary venous return (PAPVR), persistent left superior vena cava, 'bovine arch' aortic branching, tracheal diverticulum, aberrant lung fissure anatomy and an annular pancreas. He had presented with a history of worsening dyspnoea. To the best of our knowledge, this is the first reported case of a single patient with such a vast constellation of anomalies. The radiological evaluations, epidemiology, embryology and clinical features of the anomalies are discussed. It is important for radiologists to be aware of each of these anomalies as distinct entities; detection of a single anomaly should alert to the possibility that further anatomic aberrancies may be present.

  14. The formation of floor-fractured craters in Xanthe Terra

    NASA Astrophysics Data System (ADS)

    Sato, Hiroyuki; Kurita, Kei; Baratoux, David

    2010-05-01

    Floor-fractured craters (FFC) are a peculiar form of degradation of impact craters defined by the presence of crevice networks and mesas affecting crater floors. They are preferentially distributed near chaotic terrains and outflow channels. The scope of this paper is to present a detailed systematic analysis of FFC at Xanthe Terra. FFC morphologies in this region are classified into five types making a picture of different stages of the same degradation process. FFC are geographically intermixed with un-fractured normal craters (non-FFC). Young craters are less prone to show this type of degradation, as suggested by fresh ejecta layer with preserved crater floor. Size distributions of FFC and non-FFC indicate that larger craters are preferentially fractured. Careful examinations of the crater floor elevations reveal that the crevices often extend deeper than the original crater cavity. Furthermore, an onset depth for the formation of FFC is evidenced from the difference of spatial distributions between FFC and non-FFC. Roof-collapsed depressions observed in the same region have been also documented and their characteristics suggest the removal of subsurface material at depth from about 1200 to 4000 m. These observations taken together suggest a subsurface zone of volume deficit at depth from 1 to 2 km down to several kilometers responsible for FFC formation. Then a scenario of FFC formations is presented in the context of groundwater discharge events at the late Hesperian. This scenario involves two key processes, Earth fissuring and piping erosion, known to occur with rapid groundwater migrations on Earth.

  15. A 12-month clinical evaluation of pit-and-fissure sealants placed with and without etch-and-rinse and self-etch adhesive systems in newly-erupted teeth

    PubMed Central

    NOGOURANI, Maryam Karami; JANGHORBANI, Mohsen; KHADEM, Parvin; JADIDI, Zahra; JALALI, Shahriar

    2012-01-01

    Objectives The objective of this one-year clinical study was to investigate the effect of two adhesive systems (Adper Single Bond, a two-step etch-and-rinse and Clearfil SE Bond, a two-step self-etch system) on pit-and-fissure sealant retention in newly-erupted teeth. This study compared the success of the sealants in mesial and distopalatal grooves with and without these two adhesive systems. Material and Methods In a clinical trial, 35 children aged 6-8 years undergoing sealant placement were recruited. This one-year clinical study scored 70 mesial and 70 distopalatal sealants of newly-erupted permanent maxillary first molar, with a split-mouth design. All children received sealant alone in one permanent maxillary molar tooth. Children were randomized into two groups. One group received Self-Etch (SE) bond plus sealant and the other group received Single Bond plus sealant in another permanent maxillary molar tooth. Clinical evaluation at 3, 6 and 12 months was performed and the retention was studied in terms of the success and failure. Results The success rate of sealant in the distopalatal groove, using SEB at 3, 6 and 12 months was 93.3% (95% CI: 68.0, 99.8), 73.3% (95% CI: 44.9, 92.2) and 66.7% (95% CI: 38.4, 88.2), respectively. It was greater than that of the distopalatal groove in SB group with a success rate of 62.5% (95% CI: 35.4, 84.8), 31.3% (95% CI: 11.8, 58.7) and 31.3% (95% CI: 11.8, 58.7), at the three evaluation periods. The success rate of sealant in the mesial groove using SEB was 86.6% (95% CI: 59.5, 98.3), 53.3% (95% CI: 26.6, 78.7) and 53.3% (95% CI: 26.6, 78.7), while this was 100% (95% CI: 79.4, 100.0), 81.3% (95% CI: 54.4, 96.0) and 81.3% (95% CI: 54.4, 96.0) using SB, at 3, 6 and 12-month evaluation periods. Conclusions These results support the use of these two bonding agents in pit-and-fissure sealants under both isolated and contaminated conditions. Further, SE bond seemed to be less sensitive to moisture contamination. PMID:22858703

  16. Common File Formats.

    PubMed

    Mills, Lauren

    2014-03-21

    An overview of the many file formats commonly used in bioinformatics and genome sequence analysis is presented, including various data file formats, alignment file formats, and annotation file formats. Example workflows illustrate how some of the different file types are typically used.

  17. Formate Formation and Formate Conversion in Biological Fuels Production

    PubMed Central

    Crable, Bryan R.; Plugge, Caroline M.; McInerney, Michael J.; Stams, Alfons J. M.

    2011-01-01

    Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is produced by either CoA-dependent cleavage of pyruvate or enzymatic reduction of CO2 in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO2 and H2 or can be further reduced via the Wood-Ljungdahl pathway for carbon fixation or industrially for the production of methanol. Here, we review the enzymes involved in the interconversion of formate and discuss potential applications for biofuels production. PMID:21687599

  18. Hydrophilicity of dentin bonding systems influences in vitro Streptococcus mutans biofilm formation

    PubMed Central

    Brambilla, Eugenio; Ionescu, Andrei; Mazzoni, Annalisa; Cadenaro, Milena; Gagliani, Massimo; Ferraroni, Monica; Tay, Franklin; Pashley, David; Breschi, Lorenzo

    2014-01-01

    Objectives To evaluate in vitro Streptococcus mutans (S. mutans) biofilm formation on the surface of five light-curing experimental dental bonding systems (DBS) with increasing hydrophilicity. The null hypothesis tested was that resin chemical composition and hydrophilicity does not affect S. mutans biofilm formation. Methods Five light-curing versions of experimental resin blends with increasing hydrophilicity were investigated (R1, R2, R3, R4 and R5). R1 and R2 contained ethoxylated BisGMA/TEGDMA or BisGMA/TEGDMA, respectively, and were very hydrophobic, were representative of pit-and-fissure bonding agents. R3 was representative of a typical two-step etch- and-rinse adhesive, while R4 and R5 were very hydrophilic resins analogous to self-etching adhesives. Twenty-eight disks were prepared for each resin blend. After a 24 h-incubation at 37 °C, a multilayer monospecific biofilm of S. mutans was obtained on the surface of each disk. The adherent biomass was determined using the MTT assay and evaluated morphologically with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Results R2 and R3 surfaces showed the highest biofilm formation while R1 and R4 showed a similar intermediate biofilm formation. R5 was more hydrophilic and acidic and was significantly less colonized than all the other resins. A significant quadratic relationship between biofilm formation and hydrophilicity of the resin blends was found. CLSM and SEM evaluation confirmed MTT assay results. Conclusions The null hypothesis was rejected since S. mutans biofilm formation was influenced by hydrophilicity, surface acidity and chemical composition of the experimental resins. Further studies using a bioreactor are needed to confirm the results and clarify the role of the single factors. PMID:24954666

  19. Star Formation in Galaxies

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Topics addressed include: star formation; galactic infrared emission; molecular clouds; OB star luminosity; dust grains; IRAS observations; galactic disks; stellar formation in Magellanic clouds; irregular galaxies; spiral galaxies; starbursts; morphology of galactic centers; and far-infrared observations.

  20. Simple Ontology Format (SOFT)

    SciTech Connect

    Sorokine, Alexandre

    2011-10-01

    Simple Ontology Format (SOFT) library and file format specification provides a set of simple tools for developing and maintaining ontologies. The library, implemented as a perl module, supports parsing and verification of the files in SOFt format, operations with ontologies (adding, removing, or filtering of entities), and converting of ontologies into other formats. SOFT allows users to quickly create ontologies using only a basic text editor, verify it, and portray it in a graph layout system using customized styles.

  1. Deciphering the sedimentological imprint of paleoseismic events: an example from the Aptian Codó Formation, northern Brazil

    NASA Astrophysics Data System (ADS)

    Rossetti, D. F.; Góes, A. M.

    2000-09-01

    A stratigraphic horizon bearing several styles of soft-sediment structures occurs sandwiched within entirely undisturbed deposits in the lacustrine Codó Formation (Aptian) located in the eastern part of the Grajaú Basin, northern Brazil. These deposits show a variety of sedimentary features distinguished according to their deformation style as follows (from bottom to top): (a) Zone 1, consisting of widespread molar-tooth structures (i.e. fine-grained spar-filled cracks) that are interconnected with small-scale faults, fissures and stylolites inclined at a high angle to bedding; (b) Zone 2, represented by complex convolute folds with lateral gradation of smooth synclines and anticlines into isoclinic folds and internal layers that retain the normal bedding features, recumbent folds, "nappe" folds with associated thrust faults, pseudonodules, and mound-and-sag structures; (c) Zone 3, consisting of normal faults and fissures that are vertical to near vertical, show ragged morphology with small delicate peaks, taper both downward and upward after a few centimeters, and are associated with large (up to 2.5 m long) collapsed boulders; and (d) Zone 4, characterized by shales with irregular convolute folds. These deformation zones are interpreted to reflect sediment rheology and alternating periods of sediment accumulation and deformation under the influence of synsedimentary seismic events, as suggested mostly by: (1) occurrence between undeformed deposits; (2) lateral correlation for several kilometers of distance; (3) similarity with other features formed in areas affected by seismic activity; (4) presence of structures attesting to sediment deformation in an unconsolidated to semi-consolidated state; and (5) complex association of brittle and ductile deformation structures. Hence, Zone 1 records small scale cracking and faulting of early-cemented, cohesive deposits. Zone 2 is dominated by ductile deformation structures formed on water-saturated, unconsolidated

  2. Star Formation for Predictive Primordial Galaxy Formation

    NASA Astrophysics Data System (ADS)

    Milosavljević, Miloš; Safranek-Shrader, Chalence

    The elegance of inflationary cosmology and cosmological perturbation theory ends with the formation of the first stars and galaxies, the initial sources of light that launched the phenomenologically rich process of cosmic reionization. Here we review the current understanding of early star formation, emphasizing unsolved problems and technical challenges. We begin with the first generation of stars to form after the Big Bang and trace how they influenced subsequent star formation. The onset of chemical enrichment coincided with a sharp increase in the overall physical complexity of star forming systems. Ab-initio computational treatments are just now entering the domain of the predictive and are establishing contact with local observations of the relics of this ancient epoch.

  3. Tropical cyclone formation

    SciTech Connect

    Montgomery, M.T.; Farrell, B.F. )

    1993-01-15

    The physics of tropical cyclone formation is not well understood, and more is known about the mature hurricane than the formative mechanisms that produce it. It is believed part of the reason for this can be traced to insufficient upper-level atmospheric data. Recent observations suggest that tropical cyclones are initiated by asymmetric interactions associated with migratory upper-level potential vorticity disturbances and low-level disturbances. Favored theories of cyclones formation, however, focus on internal processes associated with cumulus convection and/or air-sea interaction. This work focuses on external mechanisms of cyclone formation and, using both a two- and three-dimensional moist geostrophic momentum model, investigates the role of upper-level potential vorticity disturbances on the formation process. A conceptual model of tropical cyclone formation is proposed, and implications of the theory are discussed. 71 refs., 5 figs., 1 tab.

  4. SIRTF and star formation

    NASA Technical Reports Server (NTRS)

    Shu, Frank H.

    1988-01-01

    Four problems in the field of star formation that can be attacked to advantage with SIRTF are discussed: (1) the patterns of star formation in spiral galaxies, (2) the physical mechanism for bimodal star formation, (3) the nature of bipolar outflows from young stellar objects, and (4) the birth of brown dwarfs. In each case, SIRTF can provide the crucial combination of high angular resolution with great sensitivity over a broad range of wavelengths that is needed to address the relevant issues.

  5. GLOBAL STAR FORMATION REVISITED

    SciTech Connect

    Silk, Joseph; Norman, Colin E-mail: norman@stsci.edu

    2009-07-20

    A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of supernova feedback that leads to a turbulent pressure-regulated generalization of the star formation law and is applicable to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star formation, enhances star formation efficiency. An upper limit is derived for the disk star formation rate in starbursts that depends on the ratio of global ISM to cloud pressures. We extend these considerations to the case where the interstellar gas pressure in the inner galaxy is dominated by outflows from a central active galactic nucleus (AGN). During massive spheroid formation, AGN-driven winds trigger star formation, resulting in enhanced supernova feedback and outflows. The outflows are comparable to the AGN-boosted star formation rate and saturate in the super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence of AGN-driven positive feedback. Bondi accretion feeds the central black hole with a specific accretion rate that is proportional to the black hole mass. AGN-enhanced star formation is mediated by turbulent pressure and relates spheroid star formation rate to black hole accretion rate. The relation between black hole mass and spheroid velocity dispersion has a coefficient (Salpeter time to gas consumption time ratio) that provides an arrow of time. Highly efficient, AGN-boosted star formation can occur at high redshift.

  6. Formative Assessment Probes

    ERIC Educational Resources Information Center

    Eberle, Francis; Keeley, Page

    2008-01-01

    Formative assessment probes can be effective tools to help teachers build a bridge between students' initial ideas and scientific ones. In this article, the authors describe how using two formative assessment probes can help teachers determine the extent to which students make similar connections between developing a concept of matter and a…

  7. Ice Formation on Wings

    NASA Technical Reports Server (NTRS)

    Ritz, L

    1939-01-01

    This report makes use of the results obtained in the Gottingen ice tunnel in which the atmospheric conditions are simulated and the process of ice formation photographed. The effect of ice formation is threefold: 1) added weight to the airplane; 2) a change in the lift and drag forces; 3) a change in the stability characteristics.

  8. School Formative Feedback Systems

    ERIC Educational Resources Information Center

    Halverson, Richard

    2010-01-01

    Data-driven instructional improvement relies on developing coherent systems that allow school staff to generate, interpret, and act upon quality formative information on students and school programs. This article offers a formative feedback system model that captures how school leaders and teachers structure artifacts and practices to create…

  9. Understanding Alliance Formation Patterns

    DTIC Science & Technology

    2015-12-01

    most of the alliance formations throughout history. Using logistic regression models and statistical analysis for different historical periods from... historical periods, especially under conditions of war and peace and based on the polarity of the international system. The approach presented in the...alliance formation, historical periods, geographical proximity, trade exchange, regime type, national material capability, system-level conditions 15

  10. Formative Assessment in Context

    ERIC Educational Resources Information Center

    Oxenford-O'Brian, Julie

    2013-01-01

    This dissertation responds to critical gaps in current research on formative assessment practice which could limit successful implementation of this practice within the K-12 classroom context. The study applies a socio cultural perspective of learning to interpret a cross-case analysis of formative assessment practice occurring during one…

  11. Bcl6a function is required during optic cup formation to prevent p53-dependent apoptosis and colobomata.

    PubMed

    Lee, Jiwoon; Lee, Bum-Kyu; Gross, Jeffrey M

    2013-09-01

    Mutations in BCOR (Bcl6 corepressor) are found in patients with oculo-facio-cardio-dental (OFCD) syndrome, a congenital disorder affecting visual system development, and loss-of-function studies in zebrafish and Xenopus demonstrate a role for Bcor during normal optic cup development in preventing colobomata. The mechanism whereby BCOR functions during eye development to prevent colobomata is not known, but in other contexts it serves as a transcriptional corepressor that potentiates transcriptional repression by B cell leukemia/lymphoma 6 (BCL6). Here, we have explored the function of the zebrafish ortholog of Bcl6, Bcl6a, during eye development, and our results demonstrate that Bcl6a, like Bcor, is required to prevent colobomata during optic cup formation. Our data demonstrate that Bcl6a acts downstream of Vax1 and Vax2, known regulators of ventral optic cup formation and choroid fissure closure, and that bcl6a is a direct target of Vax2. Together, this regulatory network functions to repress p53 expression and thereby suppress apoptosis in the developing optic cup. Furthermore, our data demonstrate that Bcl6a functions cooperatively with Bcor, Rnf2 and Hdac1 in a common gene regulatory network that acts to repress p53 and prevent colobomata. Together, these data support a model in which p53-dependent apoptosis needs to be tightly regulated for normal optic cup formation and that Bcl6a, Bcor, Rnf2 and Hdac1 activities mediate this regulation.

  12. Effects of hydraulic frac fluids and formation waters on groundwater microbial communities

    NASA Astrophysics Data System (ADS)

    Jiménez, Núria; Krüger, Martin

    2015-04-01

    Shale gas is being considered as a complementary energy resource to other fossil fuels. Its exploitation requires using advanced drilling techniques and hydraulic stimulation (fracking). During fracking operations, large amounts of fluids (fresh water, proppants and chemicals) are injected at high pressures into the formations, to create fractures and fissures, and thus to release gas from the source rock into the wellbore. The injected fluid partly remains in the formation, while up to 40% flows back to the surface, together with reservoir waters, sometimes containing dissolved hydrocarbons, high salt concentrations, etc. The aim of our study was to investigate the potential impacts of frac or geogenic chemicals, frac fluid, formation water or flowback on groudnwater microbial communities. Laboratory experiments under in situ conditions (i.e. at in situ temperatures, with high pressure, etc.) were conducted using groundwater samples from three different locations. Series of microcosms (3 of each kind) containing R2 broth medium or groundwater spiked with either single frac chemicals (including biocides), frac fluids, artificial reservoir water, NaCl, or different mixtures of reservoir water and frac fluid (to simulate flowback) were incubated in the dark. Controls included non-amended and non-inoculated microcosms. Classical microbiological methods and molecular analyses were used to assess changes in the microbial abundance, community structure and function in response to the different treatments. Microbial communities were quite halotolerant and their growth benefited from low concentrations of reservoir waters or salt, but they were negatively affected by higher concentrations of formation waters, salt, biocides, frac fluids or flowback. Changes on the microbial community structure could be detected by T-RFLP. Single frac components like guar gum or choline chloride could be used as substrates, while the effects of others like triethanolamine or light oil

  13. Challenges in planet formation

    NASA Astrophysics Data System (ADS)

    Morbidelli, Alessandro; Raymond, Sean N.

    2016-10-01

    Over the past two decades, large strides have been made in the field of planet formation. Yet fundamental questions remain. Here we review our state of understanding of five fundamental bottlenecks in planet formation. These are the following: (1) the structure and evolution of protoplanetary disks; (2) the growth of the first planetesimals; (3) orbital migration driven by interactions between protoplanets and gaseous disk; (4) the origin of the Solar System's orbital architecture; and (5) the relationship between observed super-Earths and our own terrestrial planets. Given our lack of understanding of these issues, even the most successful formation models remain on shaky ground.

  14. Wood formation in Angiosperms.

    PubMed

    Déjardin, Annabelle; Laurans, Françoise; Arnaud, Dominique; Breton, Christian; Pilate, Gilles; Leplé, Jean-Charles

    2010-04-01

    Wood formation is a complex biological process, involving five major developmental steps, including (1) cell division from a secondary meristem called the vascular cambium, (2) cell expansion (cell elongation and radial enlargement), (3) secondary cell wall deposition, (4) programmed cell death, and (5) heartwood formation. Thanks to the development of genomic studies in woody species, as well as genetic engineering, recent progress has been made in the understanding of the molecular mechanisms underlying wood formation. In this review, we will focus on two different aspects, the lignification process and the control of microfibril angle in the cell wall of wood fibres, as they are both key features of wood material properties.

  15. Dust Devil Formation

    NASA Astrophysics Data System (ADS)

    Rafkin, S.; Jemmett-Smith, B.; Fenton, L.; Lorenz, R.; Takemi, T.; Ito, J.; Tyler, D.

    2016-11-01

    The essential dynamical characteristic of convective vortices, including dust devils, is a highly localized vorticity tube that extends into the vertical. This chapter is concerned with both the generation of vorticity and the subsequent focusing of that vorticity into a tight vortex, and with the environmental conditions that are conducive to the formation of convective vortices in general and dust devils in particular. A review of observations, theory, and modeling of dust devil formation is provided.

  16. Plant Formate Dehydrogenase

    SciTech Connect

    John Markwell

    2005-01-10

    The research in this study identified formate dehydrogenase, an enzyme that plays a metabolic role on the periphery of one-carbon metabolism, has an unusual localization in Arabidopsis thaliana and that the enzyme has an unusual kinetic plasticity. These properties make it possible that this enzyme could be engineered to attempt to engineer plants with an improved photosynthetic efficiency. We have produced transgenic Arabidopsis and tobacco plants with increased expression of the formate dehydrogenase enzyme to initiate further studies.

  17. Formation of Giant Planets

    NASA Technical Reports Server (NTRS)

    Lin, Douglas

    1999-01-01

    Under the support of NASA Origins grant, we studied the formation of gaps in protoplanetary disks due the tidal interaction between a fully grown protoplanet and protostellar disk. The result of this study is published in the Astrophysical Journal, (vol 514, 344-367, 1999) and in several conference proceedings. The main focus of this work is to analyze planet-disk interaction during the final stages of protoplanetary formation.

  18. Display formats manual

    NASA Technical Reports Server (NTRS)

    Runnels, R. L.

    1973-01-01

    The standards and procedures for the generation of operational display formats to be used in the Mission Control Center (MCC) display control system are presented. The required effort, forms, and fundamentals for the design, specifications, and production of display formats are identified. The principles of display design and system constraints controlling the creation of optimum operational displays for mission control are explained. The basic two types of MCC display systems for presenting information are described.

  19. Autonomous Formation Flight

    NASA Technical Reports Server (NTRS)

    Schkolnik, Gerard S.; Cobleigh, Brent

    2004-01-01

    NASA's Strategic Plan for the Aerospace Technology Enterprise includes ambitious objectives focused on affordable air travel, reduced emissions, and expanded aviation-system capacity. NASA Dryden Flight Research Center, in cooperation with NASA Ames Research Center, the Boeing Company, and the University of California, Los Angeles, has embarked on an autonomous-formation-flight project that promises to make significant strides towards these goals. For millions of years, birds have taken advantage of the aerodynamic benefit of flying in formation. The traditional "V" formation flown by many species of birds (including gulls, pelicans, and geese) enables each of the trailing birds to fly in the upwash flow field that exists just outboard of the bird immediately ahead in the formation. The result for each trailing bird is a decrease in induced drag and thus a reduction in the energy needed to maintain a given speed. Hence, for migratory birds, formation flight extends the range of the system of birds over the range of birds flying solo. The Autonomous Formation Flight (AFF) Project is seeking to extend this symbiotic relationship to aircraft.

  20. Heritability and reliability of automatically segmented human hippocampal formation subregions

    PubMed Central

    Whelan, Christopher D.; Hibar, Derrek P.; van Velzen, Laura S.; Zannas, Anthony S.; Carrillo-Roa, Tania; McMahon, Katie; Prasad, Gautam; Kelly, Sinéad; Faskowitz, Joshua; deZubiracay, Greig; Iglesias, Juan E.; van Erp, Theo G.M.; Frodl, Thomas; Martin, Nicholas G.; Wright, Margaret J.; Jahanshad, Neda; Schmaal, Lianne; Sämann, Philipp G.; Thompson, Paul M.

    2016-01-01

    The human hippocampal formation can be divided into a set of cytoarchitecturally and functionally distinct subregions, involved in different aspects of memory formation. Neuroanatomical disruptions within these subregions are associated with several debilitating brain disorders including Alzheimer’s disease, major depression, schizophrenia, and bipolar disorder. Multi-center brain imaging consortia, such as the Enhancing Neuro Imaging Genetics through Meta-Analysis (ENIGMA) consortium, are interested in studying disease effects on these subregions, and in the genetic factors that affect them. For large-scale studies, automated extraction and subsequent genomic association studies of these hippocampal subregion measures may provide additional insight. Here, we evaluated the test–retest reliability and transplatform reliability (1.5 T versus 3 T) of the subregion segmentation module in the FreeSurfer software package using three independent cohorts of healthy adults, one young (Queensland Twins Imaging Study, N = 39), another elderly (Alzheimer’s Disease Neuroimaging Initiative, ADNI-2, N = 163) and another mixed cohort of healthy and depressed participants (Max Planck Institute, MPIP, N = 598). We also investigated agreement between the most recent version of this algorithm (v6.0) and an older version (v5.3), again using the ADNI-2 and MPIP cohorts in addition to a sample from the Netherlands Study for Depression and Anxiety (NESDA) (N = 221). Finally, we estimated the heritability (h2) of the segmented subregion volumes using the full sample of young, healthy QTIM twins (N = 728). Test–retest reliability was high for all twelve subregions in the 3 T ADNI-2 sample (intraclass correlation coefficient (ICC) = 0.70–0.97) and moderate-to-high in the 4 T QTIM sample (ICC = 0.5–0.89). Transplatform reliability was strong for eleven of the twelve subregions (ICC = 0.66–0.96); however, the hippocampal fissure was not consistently reconstructed across 1.5 T and

  1. Positronium Formation in Muscle

    PubMed Central

    Gustafson, D. R.

    1970-01-01

    Positronium formation in muscle at +4°C and -4°C was examined by the measurement of the angular correlation of positron annihilation radiation. Since the positronium formation rate in ice is considerably higher than it is in water, there should be a comparable increase in the positronium formation rate in muscle tissue if recent speculation that cellular water is ordered in a semicrystalline icelike state is correct. Comparison of the angular correlation from muscle at +4°C with that from water at +4°C shows no enhancement of the positronium formation rate. Frozen muscle at -4°C shows an enhancement of the positronium formation rate of approximately half that found in ice at -4°C, indicating that most cellular water undergoes a normal water-ice transition when frozen. It is concluded therefore that cell water in muscle is not ordered in a hexagonal icelike structure. While the results are consistent with the hypothesis that cell water is in the liquid state, the hypothesis that cell water is ordered in an undetermined close packed structure which transforms to the hexagonal ice structure at or near 0°C cannot be ruled out. PMID:5436881

  2. Constraints on Exomoon Formation

    NASA Astrophysics Data System (ADS)

    Nakajima, Miki; Genda, Hidenori; Asphaug, Erik; Ida, Shigeru

    2014-11-01

    It has been widely accepted that the Earth’s moon formed by a giant impact during the late stage of the planetary formation process. The giant impact led to the formation of a debris disk around the Earth from which the Moon accreted. This type of satellite formation is considered to be common not only in the solar system (e.g., the Pluto-Charon system) but also in extrasolar systems (e.g. Ogihara & Ida 2009). However, no detailed research has been conducted on impact-induced exomoon formation. Wada et al. (2006) suggest that a vapor-rich disk is dynamically unstable and that it may not be suitable for moon formation. If this is the case, the mass and composition of a planet may affect the satellite formation process. Here, we show results from giant impact simulations of planets with various masses and compositions. We use the model suggested by Nakajima & Stevenson (2014) to estimate the vapor mass fractions of the disks. We find that the more massive and the more ice-rich the planet is, the higher the vapor mass fraction of the disk becomes. This indicates there is an upper limit of the planetary mass to form an impact-induced moon and the limit depends on the planetary composition. This upper limit is a few Earth masses for a rocky planet, and about an Earth mass for an icy planet. These results are consistent with the models that Earth’s and Pluto’s satellites formed by impacts. Although no exomoon has been detected yet, our model may be used to predict whether an observed terrestrial exoplanet could potentially have one or multiple impact-induced exomoons.

  3. Gaussian entanglement of formation

    SciTech Connect

    Wolf, M.M.; Giedke, G.; Krueger, O.; Werner, R. F.; Cirac, J.I.

    2004-05-01

    We introduce a Gaussian version of the entanglement of formation adapted to bipartite Gaussian states by considering decompositions into pure Gaussian states only. We show that this quantity is an entanglement monotone under Gaussian operations and provide a simplified computation for states of arbitrary many modes. For the case of one mode per site the remaining variational problem can be solved analytically. If the considered state is in addition symmetric with respect to interchanging the two modes, we prove additivity of the considered entanglement measure. Moreover, in this case and considering only a single copy, our entanglement measure coincides with the true entanglement of formation.

  4. Sensitivity Data File Formats

    SciTech Connect

    Rearden, Bradley T.

    2016-04-01

    The format of the TSUNAMI-A sensitivity data file produced by SAMS for cases with deterministic transport solutions is given in Table 6.3.A.1. The occurrence of each entry in the data file is followed by an identification of the data contained on each line of the file and the FORTRAN edit descriptor denoting the format of each line. A brief description of each line is also presented. A sample of the TSUNAMI-A data file for the Flattop-25 sample problem is provided in Figure 6.3.A.1. Here, only two profiles out of the 130 computed are shown.

  5. Eruption of magmatic foams on the Moon: Formation in the waning stages of dike emplacement events as an explanation of ;irregular mare patches;

    NASA Astrophysics Data System (ADS)

    Wilson, Lionel; Head, James W.

    2017-04-01

    Volcanic eruptions on the Moon take place in conditions of low gravity and negligible atmospheric pressure, very different from those on Earth. These differences lead to characteristic lunar versions of hawaiian and strombolian explosive activity, and to the production of unusual eruption products neither predicted nor observed on Earth in the terminal stages of eruptions. These include the unusual mounds and rough (hummocky, blocky) floors of some small-shield summit pit crater floors, elongate depressions and mare flows (similar to those named ;irregular mare patches;, IMPs, by Braden et al., 2014). We examine the ascent and eruption of magma in the waning stages of the eruptive process in small-shield summit pit crater floors and show that many IMP characteristics can be plausibly explained by basaltic magma behavior as the rise rate of the ascending magma slows to zero, volatiles exsolve in the dike and lava lake to form a very vesicular foam, and the dike begins to close. Stresses in the very vesicular and porous lava lake crust produce fractures through which the foam extrudes at a rate determined by its non-Newtonian rheology. Waning-stage extrusion of viscous magmatic foams to the surface produces convex mounds whose physical properties inhibit typical impact crater formation and regolith development, creating an artificially young crater retention age. This mechanism for the production and extrusion of very vesicular magmatic foams is also applicable to waning-stage dike closure associated with pit craters atop dikes, and fissure eruptions in the lunar maria, providing an explanation for many irregular mare patches. This mechanism implies that IMPs and associated mare structures (small shields, pit craters and fissure flows) formed synchronously billions of years ago, in contrast to very young ages (less than 100 million years) proposed for IMPs by some workers.

  6. Formation in the Classroom

    ERIC Educational Resources Information Center

    Glennon, Fred; Jacobsen, Douglas; Jacobsen, Rhonda Hustedt; Thatamanil, John J.; Porterfield, Amanda; Moore, Mary Elizabeth

    2011-01-01

    What is the relationship between the academic knowledge of the guild and the formation of students in the classroom? This Forum gathers four essays originally presented at a Special Topics Session at the 2009 conference of the American Academy of Religion (Atlanta, Georgia), with a brief introductory essay by Fred Glennon explaining the genesis of…

  7. Endogenous Cooperation Network Formation

    NASA Astrophysics Data System (ADS)

    Angus, S.

    This paper employs insights from Complex Systems literature to develop a computational model of endogenous strategic network formation. Artificial Adaptive Agents (AAAs), implemented as finite state automata, play a modified two-player Iterated Prisoner's Dilemma game with an option to further develop the interaction space as part of their strategy. Several insights result from this relatively minor modification: first, I find that network formation is a necessary condition for cooperation to be sustainable but that both the frequency of interaction and the degree to which edge formation impacts agent mixing are both necessary conditions for cooperative networks. Second, within the FSA-modified IPD frame-work, a rich ecology of agents and network topologies is observed, with consequent payoff symmetry and network 'purity' seen to be further contributors to robust cooperative networks. Third, the dynamics of the strategic system under network formation show that initially simple dynamics with small interaction length between agents gives way to complex, a-periodic dynamics when interaction lengths are increased by a single step.

  8. Endogenous Cooperation Network Formation

    NASA Astrophysics Data System (ADS)

    Angus, S.

    This paper employs insights from Complex Systems literature to develop a computational model of endogenous strategic network formation. Artificial Adaptive Agents (AAAs), implemented as finite state automata, play a modified two-player Iterated Prisoner's Dilemma game with an option to further develop the interaction space as part of their strategy. Several insights result from this relatively minor modification: first, I find that network formation is a necessary condition for cooperation to be sustainable but that both the frequency of interaction and the degree to which edge formation impacts agent mixing are both necessary conditions for cooperative networks. Second, within the FSA-modified IPD frame-work, a rich ecology of agents and network topologies is observed, with consequent payoff symmetry and network `purity' seen to be further contributors to robust cooperative networks. Third, the dynamics of the strategic system under network formation show that initially simple dynamics with small interaction length between agents gives way to complex, a-periodic dynamics when interaction lengths are increased by a single step.

  9. Formation of planetesimals

    NASA Technical Reports Server (NTRS)

    Weidenschilling, Stuart J.

    1991-01-01

    Formation of planetesimals is discussed. The following subject areas are covered: (1) nebular structure; (2) aerodynamics of the solid bodies in the nebula; (3) problems with gravitational instability; (4) particle growth by coagulation; properties of fractal aggregates; and (5) coagulation and settling of fractal aggregates.

  10. Bacterial formate hydrogenlyase complex

    PubMed Central

    McDowall, Jennifer S.; Murphy, Bonnie J.; Haumann, Michael; Palmer, Tracy; Armstrong, Fraser A.; Sargent, Frank

    2014-01-01

    Under anaerobic conditions, Escherichia coli can carry out a mixed-acid fermentation that ultimately produces molecular hydrogen. The enzyme directly responsible for hydrogen production is the membrane-bound formate hydrogenlyase (FHL) complex, which links formate oxidation to proton reduction and has evolutionary links to Complex I, the NADH:quinone oxidoreductase. Although the genetics, maturation, and some biochemistry of FHL are understood, the protein complex has never been isolated in an intact form to allow biochemical analysis. In this work, genetic tools are reported that allow the facile isolation of FHL in a single chromatographic step. The core complex is shown to comprise HycE (a [NiFe] hydrogenase component termed Hyd-3), FdhF (the molybdenum-dependent formate dehydrogenase-H), and three iron-sulfur proteins: HycB, HycF, and HycG. A proportion of this core complex remains associated with HycC and HycD, which are polytopic integral membrane proteins believed to anchor the core complex to the cytoplasmic side of the membrane. As isolated, the FHL complex retains formate hydrogenlyase activity in vitro. Protein film electrochemistry experiments on Hyd-3 demonstrate that it has a unique ability among [NiFe] hydrogenases to catalyze production of H2 even at high partial pressures of H2. Understanding and harnessing the activity of the FHL complex is critical to advancing future biohydrogen research efforts. PMID:25157147

  11. 500+ Writing Formats.

    ERIC Educational Resources Information Center

    McIntosh, Margaret E.

    1997-01-01

    Suggests a multitude of ideas for students to communicate their ideas in writing using the language of mathematics. Includes a sampling of 500+ writing formats, 67 abbreviated writing assignments, and three complete assignments along with a sample student response to each. Sample assignments include advice column, biographical sketch, commercial,…

  12. The Formation of Trihalomethanes.

    ERIC Educational Resources Information Center

    Trussell, R. Rhodes; Umphres, Mark D.

    1978-01-01

    Reviewed are a number of factors important in the formation of trihalomethanes (THM) including the nature of aquatic humus and the influences of preozonation, bromide, pH, and chlorine. A brief investigation is also conducted into the kinetics of the THM reaction. Several major research needs are represented. (CS)

  13. Kepler Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2015-01-01

    Kepler has vastly increased our knowledge of planets and planetary systems located close to stars. The new data shows surprising results for planetary abundances, planetary spacings and the distribution of planets on a mass-radius diagram. The implications of these results for theories of planet formation will be discussed.

  14. Technobabble: File Formats.

    ERIC Educational Resources Information Center

    Wilson, Bradley

    1999-01-01

    Considers the confusion of over 20 different kinds of graphics programs. Briefly distinguishes between some of the more popular graphics formats (Photoshop, TIFF, JPEG, GIF, PICT, and EPS), and describes the benefits and disadvantages of each in the context of journalism education. (SC)

  15. S-nitrosothiol formation.

    PubMed

    Carver, Jeannean; Doctor, Allan; Zaman, Khalequz; Gaston, Benjamin

    2005-01-01

    Protein and peptide S-nitrosothiols (SNOs) are involved in guanylate cyclase-independent signaling associated with nitric oxide synthase (NOS) activation. As a general rule, SNO formation requires the presence of an electron acceptor such as Cu2+. Various proteins have been identified that catalyze SNO formation, including NOS itself, ceruloplasmin, and hemoglobin. Biochemical evidence suggests the existence of other SNO synthases and NOS-associated proteins involved in SNO formation following NOS activation. Indeed, both hydrophilic and hydrophobic consensus motifs have been identified that favor protein S-nitrosylation. Inorganic SNO formation appears also to occur in biological systems at low pH levels and/or in membranes. Once formed, SNOs localized to specific cellular compartments signal specific effects, ranging from gene regulation to ion channel gating. Indeed, the number of cellular and physiological functions appreciated to be regulated through SNO synthesis, localization, and catabolism is increasing. Although research into SNO biosynthesis is in its infancy, the importance of this field of biochemistry has been confirmed repeatedly by investigators from a broad spectrum of disciplines.

  16. Examination of Jan-Mayen and Elan microcontinents formation conditions based on analogue modeling.

    NASA Astrophysics Data System (ADS)

    Makushkina, Anna; Dubinin, Evgeniy; Grokholsky, Andrey

    2015-04-01

    There are many isolated blocks of continental crust within oceanic crust. In this study we will consider on the Elan Bank and the Jan Mayen ridge. Both these structures formed through complex history of rifts propagation. Elan Bank was formed by ridge jumping during the breakup of India and Antarctica in later Albian (117-118 Ma). Elan Bank was transferred from the Indian to the Antarctic plate via a ridge jump. The role of hot spot is unclear - probably it was the cause of ridge jumping. Thus Elan Bank is isolated block of continental crust, which was consequently accompanied by close eruption of LIP Kerguelen. Jan Mayen Ridge formed via ridge jumping into Greenlandian margin. Aegir Ridge between Europe and Greenland/Jan Mayen margins was active between chron C24 b (~55 Ma) to chron C7 (~24.7 Ma). Next step was the probable weakening of Greenlandian lithosphere by hot-spot and Kolbensei spreading ridge formation which is active since 23.5-22 Ma (chron C6) to nowadays. From others studies we know that Jan Mayen microcontinental block was rotating between anomalies C13 (33.5-33.0 Ma) and 5D (17.6-17.2 Ma). In laboratory of analogue modeling we held series of experiments dedicated to study of rifts propagation. Aim of our modeling was to study main parameters of microcontinents formation during rifting and initial spreading processes. In our model we suggest formation of these two microcontinents due to overlapping of counter rifts. Researching certain model parameters allow us to suggest that microcontinents formation happens when: (1) propagation of counter fissures is symmetrical and simultaneous; (2) initial rifts are shifted from each other on 1,5-3 cm; (3) heterogeneities in model plate (hard block parallel to extension) reduce the probability of microcontinent formation; (4) during the extension and accretion of new "oceanic" crust microcontinent undergoes rotation in horizontal and vertical planes. From our experiments we can preliminary conclude that

  17. Medusae Fossae Formation

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 10 April 2002) The Science This THEMIS visible image was acquired near 7o S, 172o W (188o E) and shows a remarkable martian geologic deposit known as the Medusae Fossae Formation. This Formation, seen here as the raised plateau in the upper two-thirds of the image, is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region the deposit has been heavily eroded by the wind to produce a series of linear ridges called yardangs. These parallel ridges point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to sculpt the dry landscape of Mars. The Medusae Fossae Formation has been completely stripped from the surface in the lower third of the image, revealing a harder layer below that is more resistant to wind erosion. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Several ancient craters that were once completely buried by this deposit are being exposed, or exhumed, as the overlying Medusae Formation is removed. Very few impact craters are visible on this Formation, indicating that the surface seen today is relatively young, and that the processes of erosion are likely to be actively occurring. The Story Medusa of Greek mythology fame, the name-giver to this region, had snaky locks of hair that could turn a person to stone. Wild and unruly, this monster of the underworld could certainly wreak havoc on the world of the human imagination. As scary as she was, Medusa would have no advantage over the fierce, masterful winds blowing across Mars, which once carved the streaky, terrain at the top of this image. Wild and whipping, these winds have slowly eroded away the 'topsoil,' revealing ancient craters and other surface features they once covered. The loosely cemented particles of this 'topsoil' are likely made up of dust

  18. Cosmological structure formation

    NASA Technical Reports Server (NTRS)

    Schramm, David N.

    1991-01-01

    A summary of the current forefront problem of physical cosmology, the formation of structures (galaxies, clusters, great walls, etc.) in the universe is presented. Solutions require two key ingredients: (1) matter; and (2) seeds. Regarding the matter, it now seems clear that both baryonic and non-baryonic matter are required. Whether the non-baryonic matter is hot or cold depends on the choice of seeds. Regarding the seeds, both density fluctuations and topological defects are discussed. The combination of isotropy of the microwave background and the recent observations indicating more power on large scales have severly constrained, if not eliminated, Gaussian fluctuations with equal power on all scales, regardless of the eventual resolution of both the matter and seed questions. It is important to note that all current structure formation ideas require new physics beyond SU(3) x SU(2) x U(1).

  19. Cosmic structure formation

    NASA Technical Reports Server (NTRS)

    Bertschinger, Edumund

    1994-01-01

    This article reviews the prevailing paradigm for how galaxies and larger structures formed in the universe: gravitational instability. Basic observational facts are summarized to motivate the standard cosmological framework underlying most detailed investigations of structure formation. The observed univers approaches spatial uniformity on scales larger than about 10(exp 26) cm. On these scales gravitational dynamics is almost linear and therefore relatively easy to relate to observations of large-scale structure. On smaller scales cosmic structure is complicated not only by nonlinear gravitational clustering but also by nonlinear nongravitational gas dynamical processes. The complexity of these phenomena makes galaxy formation one of the grand challenge problems of the physical sciences. No fully satisfactory theory can presently account in detail for the observed cosmic structure. However, as this article summarizes, significant progress has been made during the last few years.

  20. Formation of bacterial nanocells

    NASA Astrophysics Data System (ADS)

    Vainshtein, Mikhail; Kudryashova, Ekaterina; Suzina, Natalia; Ariskina, Elena; Voronkov, Vadim

    1998-07-01

    Existence of nanobacteria received increasing attention both in environmental microbiology/geomicro-biology and in medical microbiology. In order to study a production of nanoforms by typical bacterial cells. Effects of different physical factors were investigated. Treatment of bacterial cultures with microwave radiation, or culturing in field of electric current resulted in formation a few types of nanocells. The number and type of nanoforms were determined with type and dose of the treatment. The produced nanoforms were: i) globules, ii) clusters of the globules--probably produced by liaison, iii) nanocells coated with membrane. The viability of the globules is an object opened for doubts. The nanocells discovered multiplication and growth on solidified nutrient media. The authors suggest that formation of nanocells is a common response of bacteria to stress-actions produced by different agents.

  1. Prominence Formation Processes

    NASA Astrophysics Data System (ADS)

    Welsch, B. T.; DeVore, C. R.; Antiochos, S. K.

    2005-01-01

    Martens and Zwaan (ApJ v. 558 872) have proposed a prominence/ filament formation model in which differential rotation drives reconnection between two initially unconnected active regions to form helical field lines that support mass and are held down by overlying field. Using an MHD solver with adaptive refinement we simulated this process by imposing a shear flow meant to mimic differential rotation on two bipolar flux distributions meant to mimic distinct active regions. In some runs the flux systems are initially potential while in others they have been twisted by footpoint rotation to inject helicity prior to imposing the shear flow. The resulting structures are studied to understand the role of helicity in the formation of prominence-like structures.

  2. Format-Preserving Encryption

    NASA Astrophysics Data System (ADS)

    Bellare, Mihir; Ristenpart, Thomas; Rogaway, Phillip; Stegers, Till

    Format-preserving encryption (FPE) encrypts a plaintext of some specified format into a ciphertext of identical format—for example, encrypting a valid credit-card number into a valid credit-card number. The problem has been known for some time, but it has lacked a fully general and rigorous treatment. We provide one, starting off by formally defining FPE and security goals for it. We investigate the natural approach for achieving FPE on complex domains, the “rank-then-encipher” approach, and explore what it can and cannot do. We describe two flavors of unbalanced Feistel networks that can be used for achieving FPE, and we prove new security results for each. We revisit the cycle-walking approach for enciphering on a non-sparse subset of an encipherable domain, showing that the timing information that may be divulged by cycle walking is not a damaging thing to leak.

  3. Dust Formation and Destruction

    NASA Astrophysics Data System (ADS)

    Wiebe, Dmitry

    Recent infrared and sub-millimeter observations have opened up a new window in dust evolution studies. High angular resolution of Spitzer and Herschel space telescopes from near to far-infrared wavelengths allows observing dust emission in galactic and extragalactic star-forming complexes, covering a broad range of metallicities, radiation field properties, etc. A wide-scale picture of dust evolution starts to arise from these observations. In my contribution I will try to cover major recent advances in studies of dust formation and destruction, including such topics as a diverse role of supernovae in dust evolution, possibility of dust formation and/or growth in molecular clouds, and VSG and PAH evolution in HII regions and complexes.

  4. Tetrahedron Formation Control

    NASA Technical Reports Server (NTRS)

    Petruzzo, Charles; Guzman, Jose

    2004-01-01

    This paper considers the preliminary development of a general optimization procedure for tetrahedron formation control. The maneuvers are assumed to be impulsive and a multi-stage optimization method is employed. The stages include (1) targeting to a fixed tetrahedron location and orientation, and (2) rotating and translating the tetrahedron. The number of impulsive maneuvers can also be varied. As the impulse locations and times change, new arcs are computed using a differential corrections scheme that varies the impulse magnitudes and directions. The result is a continuous trajectory with velocity discontinuities. The velocity discontinuities are then used to formulate the cost function. Direct optimization techniques are employed. The procedure is applied to the NASA Goddard Magnetospheric Multi-Scale (MMS) mission to compute preliminary formation control fuel requirements.

  5. Formate-assisted pyrolysis

    DOEpatents

    DeSisto, William Joseph; Wheeler, Marshall Clayton; van Heiningen, Adriaan R. P.

    2015-03-17

    The present invention provides, among other thing, methods for creating significantly deoxygenated bio-oils form biomass including the steps of providing a feedstock, associating the feedstock with an alkali formate to form a treated feedstock, dewatering the treated feedstock, heating the dewatered treated feedstock to form a vapor product, and condensing the vapor product to form a pyrolysis oil, wherein the pyrolysis oil contains less than 30% oxygen by weight.

  6. Formation of Transient Lamellipodia

    PubMed Central

    Zimmermann, Juliane; Falcke, Martin

    2014-01-01

    Cell motility driven by actin polymerization is pivotal to the development and survival of organisms and individual cells. Motile cells plated on flat substrates form membrane protrusions called lamellipodia. The protrusions repeatedly appear and retract in all directions. If a lamellipodium is stabilized and lasts for some time, it can take over the lead and determine the direction of cell motion. Protrusions traveling along the cell perimeter have also been observed. Their initiation is in some situations the effect of the dynamics of the pathway linking plasma membrane receptors to actin filament nucleation, e.g. in chemotaxis. However, lamellipodia are also formed in many cells incessantly during motion with a constant state of the signaling pathways upstream from nucleation promoting factors (NPFs), or spontaneously in resting cells. These observations strongly suggest protrusion formation can also be a consequence of the dynamics downstream from NPFs, with signaling setting the dynamic regime but not initiating the formation of individual protrusions. A quantitative mechanism for this kind of lamellipodium dynamics has not been suggested yet. Here, we present a model exhibiting excitable actin network dynamics. Individual lamellipodia form due to random supercritical filament nucleation events amplified by autocatalytic branching. They last for about 30 seconds to many minutes and are terminated by filament bundling, severing and capping. We show the relevance of the model mechanism for experimentally observed protrusion dynamics by reproducing in very good approximation the repetitive protrusion formation measured by Burnette et al. with respect to the velocities of leading edge protrusion and retrograde flow, oscillation amplitudes, periods and shape, as well as the phase relation between protrusion and retrograde flow. Our modeling results agree with the mechanism of actin bundle formation during lamellipodium retraction suggested by Burnette et al. and

  7. Terrestrial planet formation

    PubMed Central

    Righter, K.; O’Brien, D. P.

    2011-01-01

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (∼106 y), followed by planetesimals to embryos (lunar to Mars-sized objects; few × 106 y), and finally embryos to planets (107–108 y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids. PMID:21709256

  8. Tetrahedron Formation Control

    NASA Technical Reports Server (NTRS)

    Guzman, Jose J.

    2003-01-01

    Spacecraft flying in tetrahedron formations are excellent instrument platforms for electromagnetic and plasma studies. A minimum of four spacecraft - to establish a volume - is required to study some of the key regions of a planetary magnetic field. The usefulness of the measurements recorded is strongly affected by the tetrahedron orbital evolution. This paper considers the preliminary development of a general optimization procedure for tetrahedron formation control. The maneuvers are assumed to be impulsive and a multi-stage optimization method is employed. The stages include targeting to a fixed tetrahedron orientation, rotating and translating the tetrahedron and/or varying the initial and final times. The number of impulsive maneuvers citn also be varied. As the impulse locations and times change, new arcs are computed using a differential corrections scheme that varies the impulse magnitudes and directions. The result is a continuous trajectory with velocity discontinuities. The velocity discontinuities are then used to formulate the cost function. Direct optimization techniques are employed. The procedure is applied to the Magnetospheric Multiscale Mission (MMS) to compute preliminary formation control fuel requirements.

  9. Primordial Planet Formation

    NASA Astrophysics Data System (ADS)

    Schild, Rudolph E.; Gibson, Carl H.

    Recent spacecraft observations exploring solar system properties impact standard paradigms of the formation of stars, planets and comets. We stress the unexpected cloud of microscopic dust resulting from the DEEP IMPACT mission, and the existence of molten nodules in STARDUST samples. And the theory of star formation does not explain the common occurrence of binary and multiple star systems in the standard gas fragmentation scenario. No current theory of planet formation can explain the iron core of the earth, under oceans of water. These difficulties are avoided in a scenario where the planet mass objects form primordially and are today the baryonic dark matter. They have been detected in quasar microlensing and anomalous quasar radio brightening bursts. The primordial planets often concentrate together to form a star, with residual matter seen in pre-stellar accretion discs around the youngest stars. These primordial planet mass bodies were formed of hydrogen-helium, aggregated in dense clumps of a trillion at the time of plasma neutralization 380,000 years after the big bang. Most have been frozen and invisible, but are now manifesting themselves in numerous ways as sensitive modern space telescopes become operational. Their key detection signature is their thermal emission spectrum, pegged at the 13.8 degrees Kelvin triple point of hydrogen, the baryonic dark matter (Staplefeldt et al. 1999).

  10. Stabilizing clayey formations

    SciTech Connect

    Lipowski, S. A.; Miskel Jr., J. J.; Schick, M. J.

    1985-03-19

    Process for treating a clayey geological formation to prevent, inhibit or reduce swelling or migrating of clay particles in a formation by treating the formation with an effective amount of a quaternized oligomer which is the reaction product of a polyamine having a primary amino group and a tertiary amino group with a difunctional reactant to form a precondensate monomer which is then chain extended and quaternized by reaction with a dihalogenated hydrocarbon ether. A preferred oligomer is a product of: (I) about 1.0 mole of a precondensate which is the reaction product of (A) from about 2.0 to about 3.0 mole of a polyamine having a primary amino group and a tertiary amino group, the polyamine having a non-cyclic backbone containing between 1 and 6 carbon atoms, with (B) about 1.0 mole of a difunctional reactant which is a diester of a mixture of dicarboxylic acids such as adipic, glutaric and succinic acid, with (II) from about 1.0 to about 1.2 mole of a chain extender such as dichloroethylether. Process is useful in oil producing operations.

  11. Mars brine formation experiment

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey M.; Bullock, Mark A.; Stoker, Carol R.

    1992-01-01

    Evaporites, particularly carbonates, nitrates, and sulfates, may be major sinks of volatiles scavenged from the martian atmosphere. Mars is thought to have once had a denser, warmer atmosphere that permitted the presence of liquid surface water. The conversion of atmospheric CO2 into carbonate is hypothesized to have degraded the martian climate to its present state of a generally subfreezing, desiccated desert. The rate for such a conversion under martian conditions is poorly known, so the time scale of climate degradation by this process cannot be easily evaluated. If some models are correct, carbonate formation may have been fast at geological time scales. The experiments of Booth and Kieffer also imply fast (10(exp 6) - 10(exp 7) yr) removal of the missing CO2 inventory, estimated to be 1 - 5 bar, by means of carbonate formation. The timing of formation of many of the fluvial features observed on Mars is, in large part, dependent on when and how fast the atmosphere changed. A knowledge of the rate at which carbonates and nitrates formed is also essential for assessing the probability that life, or its chemical precursors, could have developed on Mars. No previous experiments have quantitatively evaluated the rate of solution for a suite of mobile anions and cations from unaltered minerals and atmospheric gases into liquid water under Mars-like conditions. Such experiments are the focus of this task.

  12. [The formative causation].

    PubMed

    Bonilla, Ernesto

    2012-12-01

    The hypothesis of formative causation proposed by Rupert Sheldrake in 1981, affirms that morphogenetic fields play a causal role in the development and maintenance of the forms of systems at all levels of complexity and that nature is governed by habits. All animals and plants draw upon and contribute to the collective memory of their species. The author suggested that memory is inherent in nature and it is transmitted by a process called morphic resonance and works through fields called morphic fields. The hypothesis of formative causation accounts for the repetition of forms but does not explain how the first example of any given form originally came into being. Despite the advances in molecular biology, morphogenesis continues to elude a molecular explanation and seems to depend on morphogenetic fields. The hypothesis of formative causation interprets many physical and biological phenomena in a way radically different than those proposed by existing theories. According to this hypothesis the conscious self can be thought of as interacting with morphic fields in order to be connected with the external environment and with the state of the body in consciously controlled activity.

  13. Terrestrial planet formation.

    PubMed

    Righter, K; O'Brien, D P

    2011-11-29

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids.

  14. Model of kimberlite formation

    NASA Astrophysics Data System (ADS)

    Kostrovitsky, Sergey; Fiveyskaya, Lyudmila

    2013-04-01

    The critical goals in recognizing the nature of kimberlites are to find out: (1) the primary composition of melt of these rocks and (2) the principal processes of evolution of primary composition of kimberlites while ascending from mantle depth towards earth surface. Suppose, that the primary composition of kimberlite melt-fluid was in fact the composition of asthenosphere melt geochemically being close to alkaline-basalt (Hi-µ) saturated with high CO2. The genetic relation of kimberlites with basaltoids is indicated by a spatial and temporal affinity of their formation (Carlson et al, 2006; Lehmann et al, 2010; Tappe et al, 2012), similarity of the pattern of incompatible elements distribution, presence of megacryst minerals in alkaline basaltoids, Pyr-Alm garnet included, and finally, model calculation of parent melt composition for low-Cr megacryst minerals; it showed this composition to be typical for the alkaline basaltoid (Jones, 1980). At the asthenosphere level there was differentiation of basaltoid melt-fluid which was responsible for formation of its different parts with varying melt to fluid ratio and possibly varying content of alkalis (K2O). The outbreak of asthenosphere substance through lithosphere mantle proceeded by different scenarios: (a) With a noticeable dominance of fluid component kimberlites were formed by the capture and contamination of high-Mg, high-Cr rocks of lithosphere mantle that caused formation of high-Mg kimberlites. That corresponds to model of Russell (2012). (b) With a considerable proportion of melt phase depending on saturation in fluid there formed magnesium-ferriferous and ferriferous-titaniferous petrochemical types of kimberlites. There is no doubt that in formation of these kimberlite types the contamination of lithosphere material was the case, at the much lower level than in formation of high-Mg kimberlites. This model logically explains steady differences of petrochemistry of kimberlites making up clusters of

  15. Galaxy formation and evolution

    NASA Technical Reports Server (NTRS)

    Cowie, Lennox L.

    1991-01-01

    The presence of high z quasars and radio galaxies tells us that galaxy formation began at z greater than 5, but leaves unanswered the question of when the bulk of galaxies formed. Recent near infrared number counts of galaxies strongly favor a cosmological geometry with q(sub 0) = 0.5 and lambda = 0. Such a model grossly underpredicts blue galaxy counts. Spectroscopy shows that the excess blue galaxies at B = 24 are dwarfs at z approximately equals 0.4 which are no longer seen at the present time. These dwarfs must contain a large amount of baryonic matter which is not included in current estimates of baryonic omega .

  16. What initiated planetesimal formation?

    NASA Technical Reports Server (NTRS)

    Cuzzi, J. N.; Dobrovolskis, A. R.; Hogan, R. C.

    1994-01-01

    The physical structure of primitive (chondritic) meteorites, even after some geological processing and modification, is thought by most to contain clues as to the first stage of accretion of solid matter into objects that might be called planetesimals. However, theoretical understanding of the processes responsible for this important stage is shaky. We note what we believe are fundamental obstacles for the Goldreich-Ward version of rapid and direct planetesimal formation via gravitational instability in a settled particle layer, and describe an alternative scenario which might lead from grainy nebula gas to primitive planetesimals in a way that has intriguing connections to the meteorite evidence.

  17. Galaxy formation and evolution

    NASA Technical Reports Server (NTRS)

    Cowie, Lennox L.

    1991-01-01

    The presence of high-z quasars and radio galaxies indicates that galaxy formation began at z greater than 5, but leaves unanswered the question of when the bulk of galaxies formed. Recent near-infrared number counts of galaxies strongly favor a cosmological geometry with q0 = 0.5 and Lambda = 0. Such a model grossly underpredicts blue galaxy counts. Spectroscopy shows that the excess blue galaxies at B = 24 are dwarfs at z = 0.4, which are no longer seen at the present time. These dwarfs must contain a large amount of baryonic matter which is not included in current estimates of baryonic Omega.

  18. Flexible formation configuration for terrain following flight: Formation keeping constraints

    NASA Astrophysics Data System (ADS)

    Latyshev, Simon

    This work suggests a control method for the terrain-following formation motion of a group of communicating autonomous agents. The presented approach centers on defining a suitable set of constraints for formation keeping task that shall be fulfilled while agents are negotiating an unknown terrain toward the predefined goal location. It allows agents to maintain a general geometric formation shape, while allowing each individual formation member freedom of maneuver, required for terrain collision free motion. Formation structure is defined with the use of virtual leader. Formation keeping constraints are defined with plane surfaces, specified relative to position and navigation vector of the virtual leader. Formation navigation and guidance constraints are defined using navigation vectors of formation members and the virtual leader. Alternative designs for the constraints derived with parabolic, cone, and cylindrical surfaces are considered. Formation control is derived using the Udwadia-Kalaba equation, following corresponding approach to the development of control methods for constraint based dynamical systems, including leader-follower systems defined using geometric constraints. Approach to terrain following motion requiring agents to stay within bounds of cylindrical corridor volumes built around their respective navigation vectors is assumed. Individual formation primitives and multi-level, hierarchical, formation structures are considered. Simulations, based on three degrees of freedom nonlinear model of an agent, performed using Mathematica and specifically developed combined Maya-Mathematica modeling and simulation system, demonstrate that a flexible terrain following formation motion is achieved with the presented sets of constraints.

  19. Star Formation in Irregular Galaxies.

    ERIC Educational Resources Information Center

    Hunter, Deidre; Wolff, Sidney

    1985-01-01

    Examines mechanisms of how stars are formed in irregular galaxies. Formation in giant irregular galaxies, formation in dwarf irregular galaxies, and comparisons with larger star-forming regions found in spiral galaxies are considered separately. (JN)

  20. FRS Geospatial Return File Format

    EPA Pesticide Factsheets

    The Geospatial Return File Format describes format that needs to be used to submit latitude and longitude coordinates for use in Envirofacts mapping applications. These coordinates are stored in the Geospatail Reference Tables.

  1. Formation of water bells

    NASA Astrophysics Data System (ADS)

    Ybert, Christophe; Clanet, Christophe; Bocquet, Lyderic; Duez, Cyril

    2007-11-01

    We study experimentally the situation that consist in a liquid jet impacting normally onto a fixed solid disk. Depending on the experimental conditions, the thin liquid film that spreads onto the solid surface can either pour along the surface, or detach form the disk and form a so-called water bell. The dynamics and the stability of such bells as a function of the hydrodynamic parameters such as the jet and disk diameters or the jet velocity, have already been the object of detailed characterization [1]. This experiment of bell formation appears as the symmetric situation compared to that of a solid body impacting a quiescent liquid. In the latter case, it was recently shown [2] that despite large Re and We numbers, the solid surface characteristics were dramatically influencing the impact scenario. In the present study, we consequently revisit this problem of water bell formation by systematically varying the solid surface characteristics (roughness, surface properties, etc.). It is shown here again that surface parameters strongly influence the domain of bell existence. Our measurements are rationalized by a subtle balance between inertia versus capillary forces and wetting contributions on the liquid film in the ejection region. [1] C. Clanet, J. Fluid Mech., 430, 111-147 (2001) [2] C. Duez et al., Nature Physics, 3, 180-183 (2007)

  2. Microbeam formation system

    NASA Astrophysics Data System (ADS)

    Kazarinov, N. Yu.; Kazacha, V. I.; Kalagin, I. V.

    2017-01-01

    Equations for calculating the microbeam formation channel are derived. The channel consists of two coaxial diaphragms with radii r 1,2 and a target with a radius r T . With the given ion beam parameters, distance between the diaphragms L, beam radius on the target r T , and desired efficiency of beam passage through the diaphragms η0, the system of equations allows calculating the distance from the second diaphragm to the target L 1 and the radii of both diaphragms. Dependences of the diaphragm radii and the distance L 1on the efficiency η0 at a fixed target radius r T and of the efficiency η0 and the diaphragm radii r 1,2 on the distance L at a fixed distance L 1 are found. The effect of the deviations of the main channel and beam parameters from the optimum values on the microbeam formation efficiency is estimated. Tolerable values are determined for the diaphragm displacement and background magnetic field.

  3. Granular Crater Formation

    NASA Astrophysics Data System (ADS)

    Clark, Abe; Behringer, Robert; Brandenburg, John

    2009-11-01

    This project characterizes crater formation in a granular material by a jet of gas impinging on a granular material, such as a retro-rocket landing on the moon. We have constructed a 2D model of a planetary surface, which consists of a thin, clear box partially filled with granular materials (sand, lunar and Mars simulants...). A metal pipe connected to a tank of nitrogen gas via a solenoid valve is inserted into the top of the box to model the rocket. The results are recorded using high-speed video. We process these images and videos in order to test existing models and develop new ones for describing crater formation. A similar set-up has been used by Metzger et al.footnotetextP. T. Metzger et al. Journal of Aerospace Engineering (2009) We find that the long-time shape of the crater is consistent with a predicted catenary shape (Brandenburg). The depth and width of the crater both evolve logarithmically in time, suggesting an analogy to a description in terms of an activated process: dD/dt = A (-aD) (D is the crater depth, a and A constants). This model provides a useful context to understand the role of the jet speed, as characterized by the pressure used to drive the flow. The box width also plays an important role in setting the width of the crater.

  4. Sedimentology of Spearfish Formation

    SciTech Connect

    Sabel, J.M.

    1983-03-01

    The Permo-Triassic Spearfish Formation of the southeastern Black Hills, South Dakota, consists of evaporite, clastic, and carbonate sediments which formed as the result of the complex depositional history. The lithologies that occur as the result of primary deposition are (in decreasing order of abundance) gypsum, siltstone, shale, sandstone, conglomerate, limestone, dolomite, and a highly organic-rich marlstone (oil shale). The gypsum and limestone were precipitated in a low energy, hyper-saline-subaqueous environment, while the shale and organic-rich marlstone were deposited in a relatively fresh, low energy, subaqueous environment. The siltstone and dolomite were deposited in intertidal to supratidal conditions. Sandstone and conglomerate were deposited in a high flow regime fluvial environment. Although salt casts are common, no halite was observed in the area. Breccias occur as the result of post-depositional processes. During the late Middle Permian, the depocenter of the Minnekahta sea shifted westward causing the beginning of Spearfish deposition in the area. Subsequent local fluctuations of the shoreline altered environments from shallow marine to terrestrial. Throughout accumulation of the formation, deposition continued in this fashion, similar to conditions currently observed in the Persian Gulf region.

  5. Deep Water Formation

    NASA Technical Reports Server (NTRS)

    Killworth, P. D.

    1984-01-01

    Some simple arguments on plumes of dense water and filling boxes were given. What determines the time for a large-scale environment to be modified by the injection of dense water at its edge is the mass flux, not the buoyancy flux. However, it is the denser buoyancy flux, when there are several competing plumes (e.g., the Mediterranean outflow versus the Denmark Strait outflow) that determines which plume will provide the bottom water for that ocean basin. It was noted that the obvious laboratory experiment (rotate a pie-shaped annulus, and heat/cool it on the surface) had never been performed. Thus, to some extent our belief that deep convection is somehow automatic at high latitudes to close off some ill-defined meridional circulation has never been tested. A summary of deep convection was given. The two fundamental formation mechanisms were shown. Of the two, it is open-ocean convection which forms the water which supplies the Denmark Strait overflow -- in all likelihood, as formation in the Greenland Sea remains stubbornly unobserved. But it is the slope convection which finally creates North Atlantic deep water, following the Denmark Strait overspill.

  6. Bubble formation in microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.

    1994-01-01

    Two KC-135 flight campaigns have been conducted to date which are specifically dedicated to study bubble formation in microgravity. The first flight was conducted during March 14-18, 1994, and the other during June 20-24, 1994. The results from the June 1994 flight have not been analyzed yet, while the results from the March flight have been partially analyzed. In the first flight three different experiments were performed, one with the specific aim at determining whether or not cavitation can take place during any of the fluid handling procedures adopted in the shuttle bioprocessing experiments. The other experiments were concerned with duplicating some of the procedures that resulted in bubble formation, namely the NCS filling procedure and the needle scratch of a solid surface. The results from this set of experiments suggest that cavitation did not take place during any of the fluid handling procedures. The results clearly indicate that almost all were generated as a result of the breakup of the gas/liquid interface. This was convincingly demonstrated in the scratch tests as well as in the liquid fill tests.

  7. Planet Formation - Overview

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2005-01-01

    Modern theories of star and planet formation are based upon observations of planets and smaller bodies within our own Solar System, exoplanets &round normal stars and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path.

  8. Method for measuring pollutant formation

    NASA Technical Reports Server (NTRS)

    Annen, Kurt (Inventor); Stickler, David B. (Inventor)

    2001-01-01

    Diagnostic methods for determining an instantaneous rate of pollutant formation in a combustion system are based on measurement of chemiluminescence intensity generated simultaneously with the formation of the pollutant. The chemiluminescent signal is generated by an analog reaction which occurs in parallel with a key step in the formation of a specific pollutant of interest. The connection between the analog reaction and the pollution reaction is such that the chemiluminescent signal indicates the local, instantaneous formation rate of the pollutant of interest.

  9. Formative Assessment: Simply, No Additives

    ERIC Educational Resources Information Center

    Roskos, Kathleen; Neuman, Susan B.

    2012-01-01

    Among the types of assessment the closest to daily reading instruction is formative assessment. In contrast to summative assessment, which occurs after instruction, formative assessment involves forming judgments frequently in the flow of instruction. Key features of formative assessment include identifying gaps between where students are and…

  10. Fracture system influence on the reservoirs rock formation of Ordovician-Devonian carbonates in West Siberia tectonic depression

    NASA Astrophysics Data System (ADS)

    Koveshnikov, A. E.; Nesterova, A. C.; Dolgaya, T. F.

    2016-09-01

    During the Paleozoic period from the beginning of the Cambrian to the end of the Carboniferous in the boundaries of the West Siberia tectonic depression there occurred the sea, where the carbonate platforms were formed by the limestones accumulation. All the area at the end of the Carboniferous period was turned to land. Resulting from Gertsynskaya folding in the times of Permian - Triassic the formed deposits were folded and denudated to a considerable extent. Besides, the reservoir rocks of the crust of weathering including redeposited one, were formed as a result of hypergenesis, during the continental stand of the area in the near-surface zone. A new geological prospecting unit has been suggested which underlies these crusts of weathering and formed during fracture tectonic processes with hydrothermal-metasomatic limestones reworking and the processes of hydrothermal leaching and dolomitization. So, in the carbonate platforms the system of fissure zones related to tectonic disturbance was formed. This has a dendrite profile where the series of tangential, more thinned fractures deviate from the stem and finish in pores and caverns. The carbonate platforms formation in the West Siberia tectonic depression has been analyzed, their dynamics and gradual increasing from the minimal in Ordovician and Silurian to maximal at the end of the Late Devonian has been shown.

  11. Dyke-path formation in relation to the eruptions of Eyjafjallajökull 2010 and Bardarbunga-Holuhraun 2014

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust

    2015-04-01

    Dykes are extension fractures and form when the magmatic overpressure is high enough to rupture (break) the host rock. Their formation is entirely analogous to that of many joints and human-made hydraulic fractures, such as are used to increase permeability in reservoirs. When generating their paths, dykes use existing weaknesses (e.g., cooling joints) in the host rock. The maximum depth of large tension fractures below the surface of a rift zone, however, is mostly less than a few hundred metres. If the fractures extend to greater depths, they must change into closed normal faults which are generally not used as magma paths. There are thus no large tension fractures or wide-open faults at great depths ready to be filled with magma to form a dyke. While magma flow in dykes, as in other fluid-driven fractures, is at any point in various directions dyke segmentation may indicate the overall large-scale flow direction. Thus, dykes composed of large-spaced disconnected segments in lateral sections are primarily formed in vertical magma flow at segmentation depth whereas those composed of large-spaced disconnected segments in vertical sections are primarily formed in lateral magma flow. The far-field displacement and stress fields of segmented dykes are similar to those generated by single, continuous dykes of similar dimensions, particularly when the distances between the nearby tips of the segments become small in comparison with segment lengths. Most dykes become arrested and never supply magma to eruptions. Feeder-dykes normally reach the surface only along parts of their lengths (strike-dimensions). The volumetric flow or effusion rate of magma through a feeder-dyke or volcanic fissure depends on the aperture (opening) of the dyke or fissure in the 3rd power. All these theoretical and observational results are here applied to the dyke emplacements associated with the eruptions of Eyjafjallajökull 2010 and Bardarbunga-Holuhraun 2014. The results make it possible to

  12. Myxobacteria Fruiting Body Formation

    NASA Astrophysics Data System (ADS)

    Jiang, Yi

    2006-03-01

    Myxobacteria are social bacteria that swarm and glide on surfaces, and feed cooperatively. When starved, tens of thousands of cells change their movement pattern from outward spreading to inward concentration; they form aggregates that become fruiting bodies, inside which cells differentiate into nonmotile, environmentally resistant spores. Traditionally, cell aggregation has been considered to imply chemotaxis, a long-range cell interaction mediated by diffusing chemicals. However, myxobacteria aggregation is the consequence of direct cell-contact interactions. I will review our recent efforts in modeling the fruiting body formation of Myxobacteria, using lattice gas cellular automata models that are based on local cell-cell contact signaling. These models have reproduced the individual phases in Myxobacteria development such as the rippling, streaming, early aggregation and the final sporulation; the models can be unified to simulate the whole developmental process of Myxobacteria.

  13. Mechanism of GEMS formation

    SciTech Connect

    Bradley, J P; Dai, Z R

    2004-03-10

    GEMS (glass with embedded metal and sulfides) in interplanetary dust particles (IDPs) were examined using 200 keV analytical transmission electron microscopy. The morphologies and crystallography of embedded relict grains reveal that GEMS are pseudomorphs formed by irradiation processing of crystals free-floating in space. Some GEMS retain a compositional and morphological ''memory'' of the crystal from which they formed. Pseudomorphism rules out condensation, annealing, flash heating, or shock melting as alternative mechanisms of GEMS formation. A significant and often dominant fraction of the atoms in GEMS were sputtered deposited from other grains. Therefore, a normal (solar) isotopic composition is not a reliable indicator of whether GEMS formed in the solar system or in presolar interstellar or circumstellar environments.

  14. Factors stimulating bone formation.

    PubMed

    Lind, M; Bünger, C

    2001-10-01

    The aim of this review is to describe major approaches for stimulating bone healing and to review other factors affecting bone healing. Spinal bone fusion after surgery is a demanding process requiring optimal conditions for clinical success. Bone formation and healing can be enhanced through various methods. Experimental studies have revealed an array of stimulative measures. These include biochemical stimulation by use of hormones and growth factors, physical stimulation through mechanical and electromagnetic measures, and bone grafting by use of bone tissue or bone substitutes. Newer biological techniques such as stem cell transplantation and gene therapy can also be used to stimulate bone healing. Apart from bone transplantation, clinical experience with the many stimulation modalities is limited. Possible areas for clinical use of these novel methods are discussed.

  15. DUST FORMATION IN MACRONOVAE

    SciTech Connect

    Takami, Hajime; Ioka, Kunihito; Nozawa, Takaya E-mail: kunihito.ioka@kek.jp

    2014-07-01

    We examine dust formation in macronovae (as known as kilonovae), which are the bright ejecta of neutron star binary mergers and one of the leading sites of r-process nucleosynthesis. In light of information about the first macronova candidate associated with GRB 130603B, we find that dust grains of r-process elements have difficulty forming because of the low number density of the r-process atoms, while carbon or elements lighter than iron can condense into dust if they are abundant. Dust grains absorb emission from ejecta with an opacity even greater than that of the r-process elements, and re-emit photons at infrared wavelengths. Such dust emission can potentially account for macronovae without r-process nucleosynthesis as an alternative model. This dust scenario predicts a spectrum with fewer features than the r-process model and day-scale optical-to-ultraviolet emission.

  16. Physics of amniote formation

    NASA Astrophysics Data System (ADS)

    Fleury, Vincent; Murukutla, Ameya Vaishnavi; Chevalier, Nicolas R.; Gallois, Benjamin; Capellazzi-Resta, Marina; Picquet, Pierre; Peaucelle, Alexis

    2016-08-01

    We present a detailed study of the formation of the amniotic sac in the avian embryo, and a comparison with the crocodile amniotic sac. We show that the amniotic sac forms at a circular line of stiffness contrast, separating rings of cell domains. Cells align at this boundary, and this in turn orients and concentrates the tension forces. The tissue fold which forms the amniotic sac is locked exactly along this line due to the colocalization of the stiffness contrast and of the tensile force. In addition, the tensile force plays a regenerative role when the amniotic sac is cut. The fold forming the ventral side of the embryo displays the same characteristics. This work shows that amniote embryogenesis consists of a cascade of buckling events taking place at the boundaries between regions of differing mechanical properties. Hence, amniote embryogenesis relies on a simple and robust biomechanical scheme used repeatedly, and selected ancestrally.

  17. Glass formation in microgravity

    NASA Technical Reports Server (NTRS)

    Ray, C. S.; Day, D. E.

    1987-01-01

    An account is given of containerless glass-forming experiments conducted aboard the Space Shuttle in 1985, using a single-axis acoustic levitator furnace apparatus. An attempt was made to obtain quantitative evidence for the suppression of heterogeneous nucleation/crystallization in containerless melts under microgravity conditions, as well as to study melt homogenization in the absence of gravity-driven convection and assess the feasibility of laser fusion target glass microsphere preparation with a microgravity apparatus of the present type. A ternary calcia-gallia-silica glass thus obtained indicated a 2-3-fold increase in glass-formation tendency for this material composition in microgravity, by comparison with 1g.

  18. Recipes for planet formation

    NASA Astrophysics Data System (ADS)

    Meyer, Michael R.

    2009-11-01

    Anyone who has ever used baking soda instead of baking powder when trying to make a cake knows a simple truth: ingredients matter. The same is true for planet formation. Planets are made from the materials that coalesce in a rotating disk around young stars - essentially the "leftovers" from when the stars themselves formed through the gravitational collapse of rotating clouds of gas and dust. The planet-making disk should therefore initially have the same gas-to-dust ratio as the interstellar medium: about 100 to 1, by mass. Similarly, it seems logical that the elemental composition of the disk should match that of the star, reflecting the initial conditions at that particular spot in the galaxy.

  19. Kinetics of ring formation

    NASA Astrophysics Data System (ADS)

    Ben-Naim, E.; Krapivsky, P. L.

    2011-06-01

    We study reversible polymerization of rings. In this stochastic process, two monomers bond and, as a consequence, two disjoint rings may merge into a compound ring or a single ring may split into two fragment rings. This aggregation-fragmentation process exhibits a percolation transition with a finite-ring phase in which all rings have microscopic length and a giant-ring phase where macroscopic rings account for a finite fraction of the entire mass. Interestingly, while the total mass of the giant rings is a deterministic quantity, their total number and their sizes are stochastic quantities. The size distribution of the macroscopic rings is universal, although the span of this distribution increases with time. Moreover, the average number of giant rings scales logarithmically with system size. We introduce a card-shuffling algorithm for efficient simulation of the ring formation process and we present numerical verification of the theoretical predictions.

  20. Galaxy formation by dust

    NASA Technical Reports Server (NTRS)

    Wang, Boqi; Field, Goerge B.

    1989-01-01

    It has been known since the early 1940's that radiation can cause an instability in the interstellar medium. Absorbing dust particles in an isotropic radiation field shadow each other by a solid angle which is inversely proportional to the square of the distance between the two particles, leading to an inverse-square attractive force - mock gravity. The effect is largest in an optically thin medium. Recently Hogan and White (HW, hereafter) proposed that if the pre-galactic universe contained suitable sources of radiation and dust, instability in the dust distribution caused by mock gravity may have led to the formation of galaxies and galaxy clusters. In their picture of a well-coupled dust-gas medium, HW show that mock gravity begins to dominate gravitational instability when the perturbation becomes optically thin, provided that the radiation field at the time is strong enough. The recent rocket observation of the microwave background at submillimeter wavelengths by Matsumoto et al. might be from pre-galactic stars, the consequence of the absorption of ultraviolet radiation by dust, and infrared reemission which is subsequently redshifted. HW's analysis omits radiative drag, incomplete collisional coupling of gas and dust, finite dust albedo, and finite matter pressure. These effects could be important. In a preliminary calculation including them, the authors have confirmed that mock gravitational instability is effective if there is a strong ultraviolet radiation at the time, but any galaxies that form would be substantially enriched in heavy elements because the contraction of the dust is more rapid than that of the gas. Moreover, since the dust moves with supersonic velocity through the gas soon after the perturbation becomes optically thin, the sputtering of dust particles by gas is significant, so the dust could disappear before the instability develops significantly. They conclude that the mock gravity by dust is not important in galaxy formations.

  1. Dityrosine formation in calmodulin

    SciTech Connect

    Malencik, D.A.; Anderson, S.R.

    1987-02-10

    Ultraviolet (280-nm) irradiation of bovine brain calmodulin results in calcium-dependent changes in its fluorescence emission spectrum. These consist of a decline in the intrinsic tyrosine fluorescence of the protein and the appearance of a new emission maximum at 400 nm. Chromatography of irradiated calmodulin, using Ultrogel AcA 54 and phenyl-agarose columns, yields several distinctive fractions. One of these, representing 2.8% of the total recovered protein and 53% of the total fluorescence emission at 400 nm, was selected for detailed characterization. Analyses performed on acid hydrolysates reveal the presence of dityrosine, a derivative of tyrosine known for its fluorescence near 400 nm, at the level of 0.59-0.89 mol per 16,700 g of protein. Sodium dodecyl sulfate gel electrophoresis experiments demonstrate two components of apparent molecular weights 14,000 (80%) and 16,000 (20%). Observations on the effects of UV irradiation on the thrombic fragments of calmodulin and on related calcium binding proteins (rabbit skeletal muscle troponin C, bovine cardiac troponin C, and parvalbumin) support the interpretation that dityrosine formation in calmodulin results from the intramolecular cross-linking of Tyr-99 and Tyr-138. The dityrosine-containing photoproduct of calmodulin is unable to stimulate the p-nitrophenyl phosphatase activity of calcineurin under standard assay conditions. Smooth muscle myosin light chain kinase binds the derivative about 280-fold less effectively than it binds native calmodulin. Of several metal ions tested, only Cd/sup 2 +/ approaches Ca/sup 2 +/ in its ability to promote the appearance of the 400-nm emission band during UV irradiation of calmodulin. Mn/sup 2 +/ and Cu/sup 2 +/ appear to inhibit dityrosine formation.

  2. Streamer formation in sprites

    NASA Astrophysics Data System (ADS)

    McHarg, M. G.; Kammae, T.; Nielsen, H. C.

    2005-12-01

    Models of sprite formation for positive cloud-to-ground lightning strokes predict both downward (positive), and upward (negative) propagating streamers. Previous high speed camera observations of sprites are generally consistent with these predictions, but have been unable to resolve the temporal formation of the streamers due to frame rates limited to a few thousand frames per second. We report observations made during the evening of 9 July 2005 at 10,000 frames per second, with the image intensifier gated to 50 microseconds per frame. These observations often show the streamer head to be a bead-like structure propagating downward at approximately 7x106 m/s for 1,500 microseconds. The bead is followed by a dark region, and the main emissions from the sprite column are delayed ~800 microseconds after the passage of the streamer head. There are also "beads" which clearly propagate upward. Some events appear to be very similar to laboratory images of time resolved streamer zones. We interpret these observations in terms of positive/negative streamers. We see evidence for branching of the streamer tips in several cases, as well as evidence of upward propagating streamers transitioning into a more diffuse emission. Previous work (Pasko and Stenbaek-Nielsen, GRL 29(10), 2002) indicates this transition region has a lower border at an altitude when the dielectric relaxation time scale equals the time scale for an individual electron to develop into a streamer, and an upper border when the dielectric relaxation time scale roughly equals the dissociative attachment time scale. The present observations appear to be broadly consistent with this interpretation.

  3. Medusae Fossae Formation

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 16 April 2002) The Science This THEMIS visible image was acquired near 11o N, 159o W (201o E) and shows examples of the remarkable variations that can be seen in the erosion of the Medusae Fossae Formation. This Formation is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region, like many others throughout the Medusae Fossae Formation, the surface has been eroded by the wind into a series of linear ridges called yardangs. These ridges generally point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to erode the landscape of Mars. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Within this single image it is possible to see differing amounts of erosion and stripping of layers in the Medusae Fossae Formation. Near the bottom (southern) edge of the image a rock layer with a relatively smooth upper surface covers much of the image. Moving upwards (north) in the image this layer becomes more and more eroded. At first there are isolated regions where the smooth unit has been eroded to produce sets of parallel ridges and knobs. Further north these linear knobs increase in number, and only small, isolated patches of the smooth upper surface remain. Finally, at the top of the image, even the ridges have been removed, exposing the remarkably smooth top of hard, resistant layer below. This sequence of layers with differing hardness and resistance to erosion is common on Earth and on Mars, and suggests significant variations in the physical properties, composition, particle size, and/or cementation of these martian layers. As is common throughout the Medusae Fossae Formation, very few impact craters are visible, indicating that the surface exposed is relatively young, and that the process of erosion may be active today

  4. Medusae Fossae Formation

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 16 April 2002) The Science This THEMIS visible image was acquired near 11o N, 159o W (201o E) and shows examples of the remarkable variations that can be seen in the erosion of the Medusae Fossae Formation. This Formation is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region, like many others throughout the Medusae Fossae Formation, the surface has been eroded by the wind into a series of linear ridges called yardangs. These ridges generally point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to erode the landscape of Mars. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Within this single image it is possible to see differing amounts of erosion and stripping of layers in the Medusae Fossae Formation. Near the bottom (southern) edge of the image a rock layer with a relatively smooth upper surface covers much of the image. Moving upwards (north) in the image this layer becomes more and more eroded. At first there are isolated regions where the smooth unit has been eroded to produce sets of parallel ridges and knobs. Further north these linear knobs increase in number, and only small, isolated patches of the smooth upper surface remain. Finally, at the top of the image, even the ridges have been removed, exposing the remarkably smooth top of hard, resistant layer below. This sequence of layers with differing hardness and resistance to erosion is common on Earth and on Mars, and suggests significant variations in the physical properties, composition, particle size, and/or cementation of these martian layers. As is common throughout the Medusae Fossae Formation, very few impact craters are visible, indicating that the surface exposed is relatively young, and that the process of erosion may be active today

  5. Gas formation. Formation temperatures of thermogenic and biogenic methane.

    PubMed

    Stolper, D A; Lawson, M; Davis, C L; Ferreira, A A; Santos Neto, E V; Ellis, G S; Lewan, M D; Martini, A M; Tang, Y; Schoell, M; Sessions, A L; Eiler, J M

    2014-06-27

    Methane is an important greenhouse gas and energy resource generated dominantly by methanogens at low temperatures and through the breakdown of organic molecules at high temperatures. However, methane-formation temperatures in nature are often poorly constrained. We measured formation temperatures of thermogenic and biogenic methane using a "clumped isotope" technique. Thermogenic gases yield formation temperatures between 157° and 221°C, within the nominal gas window, and biogenic gases yield formation temperatures consistent with their comparatively lower-temperature formational environments (<50°C). In systems where gases have migrated and other proxies for gas-generation temperature yield ambiguous results, methane clumped-isotope temperatures distinguish among and allow for independent tests of possible gas-formation models.

  6. Acid-fog deposition at Kilauea volcano: A possible mechanism for the formation of siliceous-sulfate rock coatings on Mars

    NASA Astrophysics Data System (ADS)

    Schiffman, Peter; Zierenberg, Robert; Marks, Naomi; Bishop, Janice L.; Darby Dyar, M.

    2006-11-01

    On the summit of Kilauea volcano, sulfur dioxide, which is continuously emitted from Halemaumau crater and rapidly sequestered into sulfuric-acid rich aerosol entrained in the prevailing trade winds, is subsequently precipitated as acid fog immediately downwind from Kilauea caldera in the Kau Desert. The characteristic pH of surface tephra deposits is <4.0 in Sand Wash, a region of nearly continuous, acidic aerosol fallout immediately southwest of the caldera. Vertical exposures of unconsolidated tephras of the Keanakakoi Ash found within fissures and small, dry gullies are coated with thin rock coatings of amorphous silica and jarosite. These rock coatings are formed via an evaporative mechanism whereby acidic pore fluids, circulating in the upper few meters within the highly porous tephra, are wicked toward the walls of the gullies. Geochemical modeling of the rock coating formation process implies that the sulfate formation via evaporation occurs subsequent to minimal interaction of acidic pore fluids with the basaltic tephra. This also suggests that the cycle from acid-fog fallout to precipitation of the siliceous-sulfate rock coatings must occur quite rapidly. Acid-fog deposition of sulfate and silica at Kilauea may provide one mechanism for the origin of jarosite-bearing outcrops on Mars.

  7. Beach-cusp formation

    USGS Publications Warehouse

    Sallenger, A.H.

    1979-01-01

    Field experiments on beach-cusp formation were undertaken to document how the cuspate form develops and to test the edge-wave hypothesis on the uniform spacing of cusps. These involved observations of cusps forming from an initially plane foreshore. The cuspate form was observed to be a product of swash modification of an intertidal beach ridge as follows. A ridge, cut by a series of channels quasi-equally spaced along its length, was deposited onto the lower foreshore. The ridge migrated shoreward with flood tide, while the longshore positions of the channels remained fixed. On ebb tide, changes in swash circulation over the ridge allowed the upwash to flow shoreward through the channels and the channel mouths were eroded progressively wider until adjacent mouths met, effecting a cuspate shape. Measured spacings of cusps, ranging in size from less than 1 m to more than 12 m, agree well with computed spacings due to either zero-mode subharmonic or zero-mode synchronous edge waves. Edge-wave-induced longshore variations in run up will cause water ponded behind a ridge to converge at points of low swash and flow seaward as relatively narrow currents eroding channels spaced at one edge-wave wavelength for synchronous edge waves or one half wavelength for subharmonic edge waves. The channels are subsequently modified into cusp troughs as described above.

  8. Bubble formation in microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.

    1996-01-01

    An extensive experimental program was initiated for the purpose of understanding the mechanisms leading to bubble generation during fluid handling procedures in a microgravity environment. Several key fluid handling procedures typical for PCG experiments were identified for analysis in that program. Experiments were designed to specifically understand how such procedures can lead to bubble formation. The experiments were then conducted aboard the NASA KC-135 aircraft which is capable of simulating a low gravity environment by executing a parabolic flight attitude. However, such a flight attitude can only provide a low gravity environment of approximately 10-2go for a maximum period of 30 seconds. Thus all of the tests conducted for these experiments were designed to last no longer than 20 seconds. Several experiments were designed to simulate some of the more relevant fluid handling procedures during protein crystal growth experiments. These include submerged liquid jet cavitation, filling of a cubical vessel, submerged surface scratch, attached drop growth, liquid jet impingement, and geysering experiments. To date, four separate KC-135 flight campaigns were undertaken specifically for performing these experiments. However, different experiments were performed on different flights.

  9. Acromioclavicular joint cyst formation.

    PubMed

    Hiller, Andrew D; Miller, Joshua D; Zeller, John L

    2010-03-01

    Acromioclavicular joint (ACJ) cysts are an uncommon and unusual sequela associated with shoulder pathophysiology. The majority of literature on ACJ cysts consists of individual case reports with no definitive literature review currently available. In addition to a comprehensive literature review, four clinical cases are presented in this report. First described by Craig (1984), a total of 41 cases have been previously reported in the literature. Of these cases, five occurred with the rotator cuff musculature intact. The remaining 36 cases of ACJ cysts occurred in patients with a complete tear/avulsion of the rotator cuff. Previous attempts at compiling a complete record of all reported cases have combined several distinct conditions into a single category. This article presents two distinct etiologies for the pathogenesis of ACJ cyst formation. In the presence of an intact rotator cuff, a Type 1 cyst can form superficially and be limited to the ACJ. Following a massive or traumatic tear of the rotator cuff, mechanical instability of the humeral head can cause a deterioration of the inferior acromioclavicular capsule (cuff tear arthropathy) and an overproduction of synovial fluid. Overtime, a "geyser" of fluid can form between the glenohumeral and the ACJ, forming a Type 2 cyst. This differentiation and categorization is essential for appropriate classification and treatment.

  10. Gaining Insight into Star Formation: Resolved Star Formation Laws

    NASA Astrophysics Data System (ADS)

    Liebst, Kelley; Scowen, Paul A.

    2014-06-01

    Until recently astronomers have used star formation laws to measure the star formation rate and star formation efficiency of galaxies only on global scales because of the poor resolution of available data. What I am now capable of producing is a spatially resolved star formation law that can provide direct insight into the physical processes that govern star formation and assess the short-term nature of bursts of star formation and the longer-term nature of larger-scale events that can dictate the global distribution of stars and the ultimate fate of a galaxy as a whole. I am using exquisite narrowband optical data from a variety of sources, including the Hubble Space Telescope, and Kitt Peak National Observatory, etc., in conjunction with infrared data from the Spitzer Infrared Nearby Galaxy Survey and the Spitzer Local Volume Legacy survey, neutral gas data from The HI Nearby Galaxy Survey, and molecular gas data from the Berkeley-Illinois-Maryland Association Survey of Nearby Galaxies, to provide star formation rates and star formation efficiencies on previously inaccessible small spatial scales across a suite of galaxies that represent a range of star formation environments and scales. My sample includes 18 spiral galaxies ranging from 2.1 to 15.1 Mpc in distance and offers a large range of morphological types (i.e. a large range of star formation environments). I am using these data to test different models of star formation modes under a variety of physical conditions and relate the variations I observe to the known local physical conditions and the associated star formation histories for each locale within each galaxy.This is the heart of the matter - that the nature and evolution of the local physical environment intimately influences how stars can form, how quickly and how massive those stars are allowed to form, and as a result how they shape the local conditions for subsequent star formation. It is this tracking of the stellar ecology that is vital for

  11. Formation and ecology of plaque at different locations in the mouth.

    PubMed

    Theilade, E; Theilade, J

    1985-04-01

    Some recent findings concerning microbial colonization of smooth surfaces of teeth, gingival crevices, occlusal fissures and removable dentures are reviewed considering the many ecologic factors of importance for the oral microbial communities. The oral microbiota is extremely complex comprising at least 200 taxa. In spite of interindividual and site-to-site variations, each oral habitat has a characteristic microbiota ranging from Gram-positive, facultatively anaerobic cocci and rods in occlusal fissures to predominance of Gram-negative, strictly anaerobic rods and spirochetes in deep periodontal pockets.

  12. Binary stars - Formation by fragmentation

    NASA Technical Reports Server (NTRS)

    Boss, Alan P.

    1988-01-01

    Theories of binary star formation by capture, separate nuclei, fission and fragmentation are compared, assessing the success of theoretical attempts to explain the observed properties of main-sequence binary stars. The theory of formation by fragmentation is examined, discussing the prospects for checking the theory against observations of binary premain-sequence stars. It is concluded that formation by fragmentation is successful at explaining many of the key properties of main-sequence binary stars.

  13. Formation of Bidisperse Particle Clouds

    NASA Astrophysics Data System (ADS)

    Er, Jenn Wei; Zhao, Bing; Law, Adrian W. K.; Adams, E. Eric

    2014-11-01

    When a group of dense particles is released instantaneously into water, their motion has been conceptualized as a circulating particle thermal (Ruggerber 2000). However, Wen and Nacamuli (1996) observed the formation of particle clumps characterized by a narrow, fast moving core shedding particles into wakes. They observed the clump formation even for particles in the non-cohesive range as long as the source Rayleigh number was large (Ra > 1E3) or equivalently the source cloud number (Nc) was small (Nc < 3.2E2). This physical phenomenon has been investigated by Zhao et al. (2014) through physical experiments. They proposed the theoretical support for Nc dependence and categorized the formation processes into cloud formation, transitional regime and clump formation. Previous works focused mainly on the behavior of monodisperse particles. The present study further extends the experimental investigation to the formation process of bidisperse particles. Experiments are conducted in a glass tank with a water depth of 90 cm. Finite amounts of sediments with various weight proportions between coarser and finer particles are released from a cylindrical tube. The Nc being tested ranges from 6E-3 to 9.9E-2, which covers all the three formation regimes. The experimental results showed that the introduction of coarse particles promotes cloud formation and reduce the losses of finer particles into the wake. More quantitative descriptions of the effects of source conditions on the formation processes will be presented during the conference.

  14. Glass formation - A contemporary view

    NASA Technical Reports Server (NTRS)

    Uhlmann, D. R.

    1983-01-01

    The process of glass formation is discussed from several perspectives. Particular attention is directed to kinetic treatments of glass formation and to the question of how fast a given liquid must be cooled in order to form a glass. Specific consideration is paid to the calculation of critical cooling rates for glass formation, to the effects of nucleating heterogeneities and transients in nucleation on the critical cooling rates, to crystallization on reheating a glass, to the experimental determination of nucleation rates and barriers to crystal nucleation, and to the characteristics of materials which are most conducive to glass formation.

  15. Medusae Fossae Formation

    NASA Technical Reports Server (NTRS)

    1998-01-01

    An exotic terrain of wind-eroded ridges and residual smooth surfaces are seen in one of the highest resolution images ever taken of Mars from orbit. The Medusae Fossae formation is believed to be formed of the fragmental ejecta of huge explosive volcanic eruptions. When subjected to intense wind-blasting over hundreds of millions of years, this material erodes easily once the uppermost tougher crust is breached. In the Mars Orbiter Camera (MOC) image shown on the right, the crust, or cap rock, can be seen in the upper right part of the picture. The finely-spaced ridges are similar to features on Earth called yardangs, which are formed by intense winds plucking individual grains from, and by wind-driven sand blasting particles off, sedimentary deposits.

    The MOC image was taken on October 30, 1997 at 11:05 AM PST, shortly after the Mars Global Surveyor spacecraft's 31st closest approach to Mars. The image covers an area 3.6 X 21.5 km (2.2 X 13.4 miles) at 3.6 m (12 feet) per picture element--craters only 11 m (36 feet, about the size of a swimming pool) across can be seen. The context image (left; the best Viking view of the area; VO 1 387S34) has a resolution of 240 m/pixel, or 67 times lower resolution than the MOC frame.

    Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  16. Formative Assessment Probes: Is It a Rock? Continuous Formative Assessment

    ERIC Educational Resources Information Center

    Keeley, Page

    2013-01-01

    A lesson plan is provided for a formative assessment probe entitled "Is It a Rock?" This probe is designed for teaching elementary school students about rocks through the use of a formative assessment classroom technique (FACT) known as the group Frayer Model. FACT activates students' thinking about a concept and can be used to…

  17. Dwarf Galaxy Formation with H2-regulated Star Formation

    NASA Astrophysics Data System (ADS)

    Kuhlen, Michael; Krumholz, Mark R.; Madau, Piero; Smith, Britton D.; Wise, John

    2012-04-01

    We describe cosmological galaxy formation simulations with the adaptive mesh refinement code Enzo that incorporate a star formation prescription regulated by the local abundance of molecular hydrogen. We show that this H2-regulated prescription leads to a suppression of star formation in low-mass halos (Mh <~ 1010 M ⊙) at z > 4, alleviating some of the dwarf galaxy problems faced by theoretical galaxy formation models. H2 regulation modifies the efficiency of star formation of cold gas directly, rather than indirectly reducing the cold gas content with "supernova feedback." We determine the local H2 abundance in our most refined grid cells (76 proper parsec in size at z = 4) by applying the model of Krumholz, McKee, & Tumlinson, which is based on idealized one-dimensional radiative transfer calculations of H2 formation-dissociation balance in ~100 pc atomic-molecular complexes. Our H2-regulated simulations are able to reproduce the empirical (albeit lower z) Kennicutt-Schmidt relation, including the low Σgas cutoff due to the transition from atomic to molecular phase and the metallicity dependence thereof, without the use of an explicit density threshold in our star formation prescription. We compare the evolution of the luminosity function, stellar mass density, and star formation rate density from our simulations to recent observational determinations of the same at z = 4-8 and find reasonable agreement between the two.

  18. Lichen-rock interaction in volcanic environments: evidences of soil-precursor formation

    NASA Astrophysics Data System (ADS)

    Vingiani, S.; Adamo, P.; Terribile, F.

    2012-04-01

    The weathering action of the lichens Lecidea fuscoatra (L.) Ach. and Stereocaulon vesuvianum Pers. on basaltic rock collected on the slopes of Mt. Etna (Sicily) at 1550 m a.s.l. has been studied using optical (OM) and electron (SEM) microscopy equipped with microanalytical device (EDS). Biological factors associated with lichen growth play a major role in the weathering of minerals on bare rocks and contribute to the preliminary phases of soil formation. The present work investigates the biogeophysical and biogeochemical weathering associated to the growth of epilithic lichens on lava flows from Mt. Etna (Sicily) and Mt. Vesuvius (Campania). The chosen lichen species were the crustose Lecidea fuscoatra (L.) Ach., the foliose Xanthoparmelia conspersa and the fructicose Stereocaulon vesuvianum Pers. An integrated approach based on the study of both disturbed and undisturbed samples of lichenized rock was applied in order to appreciate the complexity of the rock-lichen interface environment in terms of micromorphological, mineralogical and chemical properties. XRD and XRF analyses coupled to microscopical (OM), submicroscopical (SEM) and microanalitical (EDS) observations were the used techniques. In both study environments, the chemical, mineralogical and micromorphological properties of the uncoherent materials found at the lichen-rock interface suggest they consist of rock fragments eroded from the surroundings and accumulated in cavities and fissures of the rough lava flows. According to the thallus morphology, the lichens colonizing the lava preserve the interface materials from further aeolic and water erosion, provide these materials of organic matter and moisture, entrap allochtonous quartz and clay minerals. The calcium oxalate production by L. fuscoatra and X. conspersa, the Al enrichment around S. vesuvianum hyphae and the occurrence of Fe-oxide phases at the rock-lichen interface are evidences of lichens interaction with the underlying sediments. Indeed

  19. The formation of Pangea

    NASA Astrophysics Data System (ADS)

    Stampfli, G. M.; Hochard, C.; Vérard, C.; Wilhem, C.; vonRaumer, J.

    2013-05-01

    The making of Pangea is the result of large-scale amalgamation of continents and micro-continents, which started at the end of the Neoproterozoic with the formation of Gondwana. As pieces were added to Gondwana on its South-American, Antarctica and Australia side, ribbon-like micro-continents were detached from its African and South-Chinese side: Cadomia in the late Neoproterozoic, Avalonia and Hunia in the Ordovician, Galatia in the Devonian and Cimmeria in the Permian. Cadomia was re-accreted to Gondwana, but the other ribbon-continents were accreted to Baltica, North-China, Laurussia or Laurasia. Finding the origin of these numerous terranes is a major geological challenge. Recently, a global plate tectonic model was developed together with a large geological/geodynamic database, at the Lausanne University, covering the last 600 Ma of the Earth's history. Special attention was given to the placing of Gondwana derived terranes in their original position, using all possible constraints. We propose here a solution for the Variscan terranes, another paper deals with the Altaids. The Galatian super-terrane was detached from Gondwana in the Devonian, during the opening of Paleotethys, and was quickly separated into four sub-terranes that started to by-pass each other. The leading terranes collided at the end of the Devonian with the Hanseatic terrane detached from Laurussia. In the Carboniferous, Gondwana started to impinge onto the amalgamated terranes, creating the Variscan chain and the Pangean super-continent. East of Spain Paleotethys remained opened until the Triassic, subducting northward under Laurasia. Roll-back of the Paleotethyan slab triggered the collapse of most of the European Variscan orogen, which was replaced by series of Permian rifts, some of them becoming oceanized back-arc basins during the Triassic. Major force changes at the Pangean plate limits at the end of the Triassic provoked its break-up, through the opening of the proto

  20. Star formation in the multiverse

    SciTech Connect

    Bousso, Raphael; Leichenauer, Stefan

    2009-03-15

    We develop a simple semianalytic model of the star formation rate as a function of time. We estimate the star formation rate for a wide range of values of the cosmological constant, spatial curvature, and primordial density contrast. Our model can predict such parameters in the multiverse, if the underlying theory landscape and the cosmological measure are known.

  1. Formative Automated Computer Testing (FACT).

    ERIC Educational Resources Information Center

    Hunt, Nicoll; Hughes, Janet; Rowe, Glenn

    2002-01-01

    Describes the development of a tool, FACT (Formative Automated Computer Testing), to formatively assess information technology skills of college students in the United Kingdom. Topics include word processing competency; tests designed by tutors and delivered via a network; and results of an evaluation that showed students preferred automated…

  2. The Apennine Bench Formation revisited

    NASA Technical Reports Server (NTRS)

    Spudis, P. D.; Hawke, B. R.

    1985-01-01

    The Apennine Bench Formation consists of pre-mare light plains materials that crop out south of the crater Archimedes, inside the Imbrium basin. This material was ascribed to either impact or volcanic origins. The characteristics of Apollo 15 KREEP basalts and the Apennine Bench Formation are reviewed to determine whether their characteristics are compatible with a volcanic origin.

  3. Formation Algorithms and Simulation Testbed

    NASA Technical Reports Server (NTRS)

    Wette, Matthew; Sohl, Garett; Scharf, Daniel; Benowitz, Edward

    2004-01-01

    Formation flying for spacecraft is a rapidly developing field that will enable a new era of space science. For one of its missions, the Terrestrial Planet Finder (TPF) project has selected a formation flying interferometer design to detect earth-like planets orbiting distant stars. In order to advance technology needed for the TPF formation flying interferometer, the TPF project has been developing a distributed real-time testbed to demonstrate end-to-end operation of formation flying with TPF-like functionality and precision. This is the Formation Algorithms and Simulation Testbed (FAST) . This FAST was conceived to bring out issues in timing, data fusion, inter-spacecraft communication, inter-spacecraft sensing and system-wide formation robustness. In this paper we describe the FAST and show results from a two-spacecraft formation scenario. The two-spacecraft simulation is the first time that precision end-to-end formation flying operation has been demonstrated in a distributed real-time simulation environment.

  4. Tariffs Formation on oil transportation

    NASA Astrophysics Data System (ADS)

    Glyzina, T. S.; Kolbysheva, Yu. V.; Grivtsova, I. S.; Dmitrieva, N. V.

    2016-09-01

    Oil transportation via trunk pipelines is an important part of the oil industry's activity. The main instrument of tariff regulation is the method of tariffs formation. Three methods of tariffs formation such as the method of economically justified costs (the Cost plus method), the method of economically justified return on investment capital (the RAB method), and the method of tariffs indexation were considered.

  5. IRIG Serial Time Code Formats

    DTIC Science & Technology

    2016-08-01

    TELECOMMUNICATIONS AND TIMING GROUP IRIG STANDARD 200-16 IRIG SERIAL TIME CODE FORMATS DISTRIBUTION A: APPROVED FOR...ARNOLD ENGINEERING DEVELOPMENT COMPLEX NATIONAL AERONAUTICS AND SPACE ADMINISTRATION This page intentionally left blank. IRIG SERIAL TIME CODE ...Serial Time Code Formats, RCC 200-16, August 2016 v Table of Contents Preface

  6. The Principal as Formative Coach

    ERIC Educational Resources Information Center

    Nidus, Gabrielle; Sadder, Maya

    2011-01-01

    Formative coaching, an approach that uses student work as the foundation for mentoring and professional development, can help principals become more effective instructional leaders. In formative coaching, teaches and coaches analyze student work to determine next steps for instruction. This article shows how a principal can use the steps of the…

  7. SAS FORMATS: USES AND ABUSES

    EPA Science Inventory

    SAS formats are a very powerful tool. They allow you to display the data in a more readable manner without modifying it. Formats can also be used to group data into categories for use in various procedures like PROC FREQ, PROC TTEST, and PROC MEANS (as a class variable). As ...

  8. Motivating Students through Formative Feedback

    ERIC Educational Resources Information Center

    Mauch, Lois

    2007-01-01

    Technology tools that are used to help apply standards and benchmarks motivate physical educators to use new methods of teaching, and create new ways to provide students with direct formative feedback, the number one motivator for students. Direct formative feedback refers to verbal communication between the teacher and/or parent and student. The…

  9. SAS FORMATS: USES AND ABUSES

    EPA Science Inventory

    SAS formats are a very powerful tool. They allow you to display the data in a more readable manner without modifying it. Formats can also be used to group data into categories for use in various procedures like PROC FREQ, PROC TTEST, and PROC MEANS (as a class variable). As w...

  10. Portable File Format (PFF) specifications

    SciTech Connect

    Dolan, Daniel H.

    2015-02-01

    Created at Sandia National Laboratories, the Portable File Format (PFF) allows binary data transfer across computer platforms. Although this capability is supported by many other formats, PFF files are still in use at Sandia, particularly in pulsed power research. This report provides detailed PFF specifications for accessing data without relying on legacy code.

  11. Physics of primordial star formation

    NASA Astrophysics Data System (ADS)

    Yoshida, Naoki

    2012-09-01

    The study of primordial star formation has a history of nearly sixty years. It is generally thought that primordial stars are one of the key elements in a broad range of topics in astronomy and cosmology, from Galactic chemical evolution to the formation of super-massive blackholes. We review recent progress in the theory of primordial star formation. The standard theory of cosmic structure formation posits that the present-day rich structure of the Universe developed through gravitational amplification of tiny matter density fluctuations left over from the Big Bang. It has become possible to study primordial star formation rigorously within the framework of the standard cosmological model. We first lay out the key physical processes in a primordial gas. Then, we introduce recent developments in computer simulations. Finally, we discuss prospects for future observations of the first generation of stars.

  12. Cyanide Formation by Chromobacterium violaceum

    PubMed Central

    Michaels, Ruth; Corpe, W. A.

    1965-01-01

    Michaels, Ruth (Columbia University, New York, N.Y.), and W. A. Corpe. Cyanide formation by Chromobacterium violaceum. J. Bacteriol. 89:106–112. 1965.—The formation of cyanide by a Chromobacterium violaceum strain was studied with growing cultures and with nonproliferating cells grown in complex and chemically defined media. Most of the cyanide was produced during the log-phase growth of the organism, and accumulated in the culture supernatant fluid. A synergistic effect of glycine and methionine on cyanide formation in a chemically defined medium was observed, and the amount of cyanide formed was found to be dependent on the concentrations of the two substances. Cyanide formation by nonproliferating cells was stimulated by preincubation with glycine and methionine. Cyanide formation by adapted cells in the presence of glycine and methionine was stimulated by succinate, malate, or fumarate, and depressed by azide and 2,4-dinitrophenol. Methionine could be replaced by betaine, dimethylglycine, and choline. PMID:14255648

  13. Pattern formation at liquid interfaces

    NASA Astrophysics Data System (ADS)

    Heidel, Barbara; Knobler, Charles M.

    1990-01-01

    Quantitative experimental investigations of pattern formation at a liquid interface are described. The reaction studied is the photoreduction of Fe 3+ in aqueous solution and the subsequent formation of Turnbull's Blue. Both the wavelength of the pattern and the time at which the break in homogeneity occurs have been studied as functions of the concentrations of the reactants and the viscosity of the solvent. Many of the features of the process are consistent with a mechanism in which autocatalysis is enhanced by double diffusion. Preliminary studies of pattern formation in the KI/starch/chloralhydrate system are also presented.

  14. The physics of planetesimal formation

    NASA Technical Reports Server (NTRS)

    Weidenschilling, Stuart J.; Donn, Bertram D.; Meakin, Paul

    1989-01-01

    Physical processes involved in the planetesimal formation are discussed with special attention given to the nature of aerodynamic interactions between solid bodies and gas in the solar nebula. It is emphasized that the model of planetesimal formation by gravitational instability of a dust layer yields predictions that are simple but almost certainly wrong. It is suggested instead that the formation of planetesimals began with the process of coagulation of grains into larger aggregates, and that gravitational forces became more important than gas drag only after objects as large as many meters in diameter had formed.

  15. Dynamics of rock varnish formation

    SciTech Connect

    Raymond, R. Jr.; Reneau, S.L.; Guthrie, G.D. Jr.; Bish, D.L.; Harrington, C.D.

    1991-01-01

    Our studies of rock varnish from the southwestern United States suggest that the Mn-phase in rock varnish has neither the chemistry nor the crystal structure of birnessite. Rather, the Mn-rich phase is non-crystalline and contains Ba, Ca, Fe, Al, and P. Unknowns concerning the formation of this non-crystalline Mn phase must be resolved before researchers are able to define chemical parameters of rock varnish formation based upon conditions of formation of the Mn phase. 6 refs., 9 figs.

  16. Results of Aluminosilicate Formation Testing

    SciTech Connect

    Wilmarth, W.R.

    2001-09-11

    The purpose of this work was to examine several experimental parameters of the formation of aluminosilicates under several tank chemistries, examine the conversion of crystalline phases, and determine inherent solubilities of certain crystal phases.

  17. Ultraviolet Mars Reveals Cloud Formation

    NASA Video Gallery

    Images from MAVEN's Imaging UltraViolet Spectrograph were used to make this movie of rapid cloud formation on Mars on July 9-10, 2016. The ultraviolet colors of the planet have been rendered in fal...

  18. Motion Predicts Clinical Callus Formation

    PubMed Central

    Elkins, Jacob; Marsh, J. Lawrence; Lujan, Trevor; Peindl, Richard; Kellam, James; Anderson, Donald D.; Lack, William

    2016-01-01

    Background: Mechanotransduction is theorized to influence fracture-healing, but optimal fracture-site motion is poorly defined. We hypothesized that three-dimensional (3-D) fracture-site motion as estimated by finite element (FE) analysis would influence callus formation for a clinical series of supracondylar femoral fractures treated with locking-plate fixation. Methods: Construct-specific FE modeling simulated 3-D fracture-site motion for sixty-six supracondylar femoral fractures (OTA/AO classification of 33A or 33C) treated at a single institution. Construct stiffness and directional motion through the fracture were investigated to assess the validity of construct stiffness as a surrogate measure of 3-D motion at the fracture site. Callus formation was assessed radiographically for all patients at six, twelve, and twenty-four weeks postoperatively. Univariate and multivariate linear regression analyses examined the effects of longitudinal motion, shear (transverse motion), open fracture, smoking, and diabetes on callus formation. Construct types were compared to determine whether their 3-D motion profile was associated with callus formation. Results: Shear disproportionately increased relative to longitudinal motion with increasing bridge span, which was not predicted by our assessment of construct stiffness alone. Callus formation was not associated with open fracture, smoking, or diabetes at six, twelve, or twenty-four weeks. However, callus formation was associated with 3-D fracture-site motion at twelve and twenty-four weeks. Longitudinal motion promoted callus formation at twelve and twenty-four weeks (p = 0.017 for both). Shear inhibited callus formation at twelve and twenty-four weeks (p = 0.017 and p = 0.022, respectively). Titanium constructs with a short bridge span demonstrated greater longitudinal motion with less shear than did the other constructs, and this was associated with greater callus formation (p < 0.001). Conclusions: In this study of

  19. Cosmic strings and galaxy formation

    NASA Technical Reports Server (NTRS)

    Bertschinger, Edmund

    1989-01-01

    The cosmogonical model proposed by Zel'dovich and Vilenkin (1981), in which superconducting cosmic strings act as seeds for the origin of structure in the universe, is discussed, summarizing the results of recent theoretical investigations. Consideration is given to the formation of cosmic strings, the microscopic structure of strings, gravitational effects, cosmic string evolution, and the formation of galaxies and large-scale structure. Simulation results are presented in graphs, and several outstanding issues are listed and briefly characterized.

  20. Dense cloud formation and star formation in a barred galaxy

    NASA Astrophysics Data System (ADS)

    Nimori, M.; Habe, A.; Sorai, K.; Watanabe, Y.; Hirota, A.; Namekata, D.

    2013-03-01

    We investigate the properties of massive, dense clouds formed in a barred galaxy and their possible relation to star formation, performing a two-dimensional hydrodynamical simulation with the gravitational potential obtained from the 2MASS data from the barred spiral galaxy, M83. Since the environment for cloud formation and evolution in the bar region is expected to be different from that in the spiral arm region, barred galaxies are a good target to study the environmental effects on cloud formation and the subsequent star formation. Our simulation uses for an initial 80 Myr isothermal flow of non-self gravitating gas in the barred potential, then including radiative cooling, heating and self-gravitation of the gas for the next 40 Myr, during which dense clumps are formed. We identify many cold, dense gas clumps for which the mass is more than 104 M⊙ (a value corresponding to the molecular clouds) and study the physical properties of these clumps. The relation of the velocity dispersion of the identified clump's internal motion with the clump size is similar to that observed in the molecular clouds of our Galaxy. We find that the virial parameters for clumps in the bar region are larger than that in the spiral arm region. From our numerical results, we estimate star formation in the bar and spiral arm regions by applying the simple model of Krumholz & McKee (2005). The mean relation between star formation rate and gas surface density agrees well with the observed Kennicutt-Schmidt relation. The star formation efficiency in the bar region is ˜60 per cent of the spiral arm region. This trend is consistent with observations of barred galaxies.

  1. Formation of high-grade ignimbrites Part II. A pyroclastic suspension current model with implications also for low-grade ignimbrites

    NASA Astrophysics Data System (ADS)

    Freundt, Armin

    Analogue experiments in part I led to the conclusion that pyroclastic flows depositing very high-grade ignimbrite move as dilute suspension currents. In the thermo-fluid-dynamical model developed, the degree of cooling of expanded turbulent pyroclastic flows dynamically evolves in response to entrainment of air and mass loss to sedimentation. Initial conditions of the currents are derived from column-collapse modeling for magmas with an initial H2O content of 1-3wt.% erupting through circular vents and caldera ring-fissures. The flows spread either longitudinally or radially from source up to a runout distance that increases with higher mass flux but decreases with higher gas content, temperature, bottom slope and coarser initial grain size. Progressive dilution by entrainment and sedimentation causes pyroclastic currents to transform into buoyant ash plumes at the runout distance. The ash plumes reach stratospheric heights and distribute 30-80% of the erupted material as widespread co-ignimbrite ash. Pyroclastic suspension currents with initial mass fluxes of 107-1012kg/s can spread for tens of kilometers with only limited cooling, although they move as supercritical, strongly entraining currents for the eruption conditions considered here. With increasing eruption mass flux, cooling during passage through the fountain diminishes while cooling during flow transport increases. The net effect is that eruption temperature exerts the prime control on emplacement temperature. Pyroclastic suspension currents can form welded ignimbrite across their entire extent if eruption temperature is To>1.3.Tmw, the minimum welding temperature. High eruption rates, a large fraction of fine ash, and a ring-fissure vent favor the formation of extensive high-grade ignimbrite. For very hot eruptions producing sticky, partially molten pyroclasts, analysis of particle aggregation systematics shows that factors favoring longer runout also favor more efficient aggregation, which reduces

  2. Geochemical study of products associated with spontaneous oxidation of coal in the Cerro Pelado Formation, Venezuela

    NASA Astrophysics Data System (ADS)

    Martínez, M.; Márquez, G.; Alejandre, F. J.; Del Río, J. J.; Hurtado, A.

    2009-02-01

    The aim of this research work is a geochemical, mineralogical, and textural characterization of spontaneously smouldered coal-derived products in northwestern Venezuela (Cerro Pelado Formation, some 10 km from Pedregal city). Several solid samples were collected from this formation, six of unweathering coal, an other six of resulting unmelted rocks forming on a surface coal bed, and the last four of mineralizations found accumulating around gas vents. The fresh coal and the unmelted material were analysed by scanning electron microscopy, X-ray diffraction, and proximate techniques. Products such as magnetite and chabazite-K were identified in the alteration rocks. Likewise, both materials were also studied in order to determine the mobilization of 17 elements into the environment; such elements were analysed through inductively coupled plasma atomic emission spectroscopy on extracts obtained by a sequential extraction method: each sample was firstly extracted with MilliQ water and then the resultant residue was washed. This and the subsequently resulting residues are extracted according to the mentioned procedure by using, respectively, ammonium acetate, chlorhydric acid, peroxide and chlorhydric acid, nitric acid and fluorhydric acid, and nitric acid. The studied elements are classified as highly mobile (Na, Ni, ...), nearly immobile (Ti, P) and partially mobile (Mg, Fe, K, ...). In regards to mineralizations around fumaroles associated with smoldering coal seams, Fourier-transform infrared spectroscopy and X-ray diffraction analyses have revealed the presence of salammoniac, mascagnite and other solid combustion compounds formed by reaction of gas emitted from coal oxidation, in addition to previously non-reported sulfur-rich by-products associated with gas fissures, particularly ammonium thiosulfate, a phase first obtained only synthetically in the laboratory. Another objective of the research was to collect and analyse gases escaping from surficial vents

  3. Rapid de novo aneurysm formation after clipping of a ruptured middle cerebral artery aneurysm in an infant with an MYH11 mutation.

    PubMed

    Ravindra, Vijay M; Karsy, Michael; Schmidt, Richard H; Taussky, Philipp; Park, Min S; Bollo, Robert J

    2016-10-01

    The authors report the case of a previously healthy 6-month-old girl who presented with right arm and leg stiffening consistent with seizure activity. An initial CT scan of the head demonstrated acute subarachnoid hemorrhage in the basal cisterns extending into the left sylvian fissure. Computed tomography angiography demonstrated a 7 × 6 × 5-mm saccular aneurysm of the inferior M2 division of the left middle cerebral artery. The patient underwent left craniotomy and microsurgical clip ligation with wrapping of the aneurysm neck because the vessel appeared circumferentially dysplastic in the region of the aneurysm. Postoperative angiography demonstrated a small remnant, sluggish distal flow, but no significant cerebral vasospasm. Fifty-five days after the initial aneurysm rupture, the patient presented again with an acute intraparenchymal hemorrhage of the left anterior temporal lobe. Angiogram revealed a circumferentially dysplastic superior division of the M2 branch, with a new 5 × 4-mm saccular aneurysm distinct from the first, with 2 smaller aneurysms distal to the new ruptured aneurysm. Endovascular parent vessel occlusion with Onyx was performed. Genetic testing revealed a mutation of the MYH11. To the authors' knowledge, this is the first report of rapid de novo aneurysm formation in an infant with an MYH11 mutation. The authors review the patient's clinical presentation and management and comprehensively review the literature on this topic.

  4. Graben formation and dike arrest during the 2009 Harrat Lunayyir dike intrusion in Saudi Arabia: Insights from InSAR, stress calculations and analog experiments

    NASA Astrophysics Data System (ADS)

    Xu, Wenbin; Jónsson, Sigurjón; Corbi, Fabio; Rivalta, Eleonora

    2016-04-01

    Detailed spatial and temporal accounts of propagating dikes from crustal deformation data, including their interplay with faulting, are rare, leaving many questions about how this interplay affects graben formation and the arrest of dikes unanswered. Here we use interferometric synthetic aperture radar (InSAR) observations, stress calculations, and analog experiments to investigate the interaction between an intruding dike and normal faulting during the 2009 Harrat Lunayyir dike intrusion in western Saudi Arabia. We generated five displacement maps from InSAR data to unravel the temporal evolution of deformation covering the majority of the intrusion. We find that the observed surface displacements can be modeled by a ~2 m thick dike with an upper tip ~2 km below the surface on 16 May 2009, 4 weeks after the onset of seismic unrest. In the following three days, the dike propagated to within ~1 km of the surface with graben-bounding normal faulting dominating the near-field deformation. The volume of the dike doubled between mid-May and mid-June. We carried out analog experiments that indicate that the wedge-shaped graben grew outward with the faulting style changing progressively from normal faulting to oblique. Coulomb failure stress change calculations show that the intruding dike caused two zones of shallow horizontal tension on both sides of the dike, producing two zones of fissuring and normal faulting at the surface. In return, the faulting provoked compression around the upper tip of the dike, holding back its vertical propagation.

  5. Treating tar sands formations with karsted zones

    DOEpatents

    Vinegar, Harold J.; Karanikas, John Michael

    2010-03-09

    Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.

  6. An Adaptable Seismic Data Format

    NASA Astrophysics Data System (ADS)

    Krischer, Lion; Smith, James; Lei, Wenjie; Lefebvre, Matthieu; Ruan, Youyi; de Andrade, Elliott Sales; Podhorszki, Norbert; Bozdağ, Ebru; Tromp, Jeroen

    2016-11-01

    We present ASDF, the Adaptable Seismic Data Format, a modern and practical data format for all branches of seismology and beyond. The growing volume of freely available data coupled with ever expanding computational power opens avenues to tackle larger and more complex problems. Current bottlenecks include inefficient resource usage and insufficient data organization. Properly scaling a problem requires the resolution of both these challenges, and existing data formats are no longer up to the task. ASDF stores any number of synthetic, processed or unaltered waveforms in a single file. A key improvement compared to existing formats is the inclusion of comprehensive meta information, such as event or station information, in the same file. Additionally, it is also usable for any non-waveform data, for example, cross-correlations, adjoint sources or receiver functions. Last but not least, full provenance information can be stored alongside each item of data, thereby enhancing reproducibility and accountability. Any data set in our proposed format is self-describing and can be readily exchanged with others, facilitating collaboration. The utilization of the HDF5 container format grants efficient and parallel I/O operations, integrated compression algorithms and check sums to guard against data corruption. To not reinvent the wheel and to build upon past developments, we use existing standards like QuakeML, StationXML, W3C PROV and HDF5 wherever feasible. Usability and tool support are crucial for any new format to gain acceptance. We developed mature C/Fortran and Python based APIs coupling ASDF to the widely used SPECFEM3D_GLOBE and ObsPy toolkits.

  7. The Dynamics of Latifundia Formation

    PubMed Central

    Chaves, Luis Fernando

    2013-01-01

    Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia. PMID:24376597

  8. Metallurgical coke: formation, structure and properties

    SciTech Connect

    Marsh, H.

    1982-01-01

    Metallurgical coke has an optical texture or microstructure composed of anisotropic carbon in the form of mosaics and flow-type anisotropy as well as isotropic carbon or inerts. The anisotropic carbon is formed via the intermediates of nematic liquid crystals and mesophase. The physical and chemical properties of the coal ultimately control the fluidity of the carbonization system and this, in turn, is important in controlling the size and shape of resultant anisotropy in the coke. Each component of the optical texture makes a contribution to coke performance. The interlocked, randomly orientated units of the mosaics, 1 to 10 ..mu..m diameter, are more resistant to crack propagation and fracture than is the isotropic carbon or the flow-type anisotropic carbon (length > 10 ..mu..m). Anisotropic carbon is more resistant to gasification than is isotropic carbon and this factor is relevant in discussion of solution-loss in the blast furnace. The mosaic units of anisotropic carbon, on gasification, do not develop the fissures which ooccur in the flow-type anisotropy and hence coke strength can be maintained relatively. The mosaics, which constitute a major part of the optical texture of metallurgical cokes, are more resistant to attack by alkali than the flow-type anisotropy. The isotropic carbon is probably more resistant. Co-carbonizations are described which produce cokes with these suitable optical textures. The concepts of hydrogen shuttling is introduced to explain the successful use of pitch additives in coal blends.

  9. The Physics of Planetesimal Formation

    NASA Astrophysics Data System (ADS)

    Simon, Jacob; Armitage, Philip; Youdin, Andrew; Li, Rixin

    2015-12-01

    Planetesimals are the precursors to planets, and understanding their formation is an essential step towards developing a complete theory of planet formation. For small solid particles (e.g., dust grains) to coagulate into planetesimals, however, requires that these particles grow beyond centimeter sizes; with traditional coagulation physics, this is very difficult. The streaming instability, which is a clumping process akin to the pile-up of cars in a traffic jam, generates sufficiently high solid densities that the mutual gravity between the clumped particles eventually causes their collapse towards planetesimal mass and size scales. Exploring this transition from dust grains to planetesimals is still in its infancy but is extremely important if we want to understand the basics of planet formation. Here, I present a series of high resolution, first principles numerical simulations of potoplanetary disk gas and dust to study the clumping of particles via the streaming instability and the subsequent collapse towards planetesimals. These simulations have been employed to characterize the planetesimal population as a function of radius in protoplanetary disks. The results of these simulations will be crucial for planet formation models to correctly explain the formation and configuration of solar systems.

  10. VLBI Data Interchange Format (VDIF)

    NASA Technical Reports Server (NTRS)

    Whitney, Alan; Kettenis, Mark; Phillips, Chris; Sekido, Mamoru

    2010-01-01

    One important outcome of the 7th International e-VLBI Workshop in Shanghai in June 2008 was the creation of a task force to study and recommend a universal VLBI data format that is suitable for both on-the-wire e-VLBI data transfer, as well as direct disk storage. This task force, called the VLBI Data Interchange Format (VDIF) Task Force, is the first part of a two-part effort, the second of which will address standardization of e-VLBI data-transmission-protocols. The formation of the VDIF Task Force was prompted particularly by increased e-VLBI activity and the difficulties encountered when data arrive at a correlator in different formats from various instruments in various parts of the world. The task force created a streaming packetized data format that may be used for real-time and non-realtime e-VLBI, as well as direct disk storage. The data may contain multiple channels of time-sampled data with an arbitrary number of channels, arbitrary #bits/sample up to 32, and real or complex data; data rates in excess of 100 Gbps are supported. Each data packet is completely self-identifying via a short header, and data may be decoded without reference to any external information. The VDIF task force has completed its work, and the VDIF standard was ratified at the 2009 e-VLBI workshop in Madrid.

  11. SW New Mexico Oil Well Formation Tops

    SciTech Connect

    Shari Kelley

    2015-10-21

    Rock formation top picks from oil wells from southwestern New Mexico from scout cards and other sources. There are differing formation tops interpretations for some wells, so for those wells duplicate formation top data are presented in this file.

  12. Formative Evaluation in the Performance Context.

    ERIC Educational Resources Information Center

    Dick, Walter; King, Debby

    1994-01-01

    Reviews the traditional formative evaluation model used by instructional designers; summarizes Kirkpatrick's model of evaluation; proposes the integration of part of Kirkpatrick's model with traditional formative evaluation; and discusses performance-context formative evaluation. (three references) (LRW)

  13. Morphological study of penumbral formation

    NASA Astrophysics Data System (ADS)

    Kitai, Reizaburo; Watanabe, Hiroko; Otsuji, Ken'ichi

    2014-12-01

    Penumbrae are known to be areas of mainly horizontal magnetic field surrounding umbrae of relatively large and mature sunspots. In this paper, we observationally studied the formation of penumbrae in NOAA 10978, where several penumbral formations were observed in G-band images of the Solar Optical Telescope on board Hinode. Thanks to the continuous observation by Hinode, we could morphologically follow the evolution of sunspots and found that there are several paths to the penumbral formation: (1) active accumulation of magnetic flux, (2) rapid emergence of magnetic field, and (3) appearance of twisted or rotating magnetic tubes. In all of these cases, magnetic fields are expected to sustain high inclination at the edges of flux tube concentration longer than the characteristic growth time of downward magnetic pumping.

  14. Jet-Induced Star Formation

    SciTech Connect

    van Breugel, W; Fragile, C; Anninos, P; Murray, S

    2003-12-16

    Jets from radio galaxies can have dramatic effects on the medium through which they propagate. We review observational evidence for jet-induced star formation in low ('FR-I') and high ('FR-II') luminosity radio galaxies, at low and high redshifts respectively. We then discuss numerical simulations which are aimed to explain a jet-induced starburst ('Minkowski's Object') in the nearby FR-I type radio galaxy NGC 541. We conclude that jets can induce star formation in moderately dense (10 cm{sup -3}), warm (10{sup 4} K) gas; that this may be more common in the dense environments of forming, active galaxies; and that this may provide a mechanism for 'positive' feedback from AGN in the galaxy formation process.

  15. Pathophysiology of glioma cyst formation.

    PubMed

    Adn, Mahmoudreza; Saikali, Stephan; Guegan, Yvon; Hamlat, Abderrahmane

    2006-01-01

    Fluid filled cystic cavities are accompaniments of some cerebral gliomas. These tumoural cysts together with peritumoural vasogenic brain oedema add to the morbid effects of the gliomas in terms of mass effect and increased intracranial pressure. Although different mechanisms have been suggested as to the pathogenesis of glioma-associated cysts, it is still unclear why these cysts appear in only a limited number of cerebral gliomas while brain oedema, a probable precursor of glioma cysts, is a usual accompaniment of most gliomas. Here, the authors present a two-hit hypothesis of brain glioma cyst formation. We suggest that after the formation of vasogenic tumoural brain oedema, microvascular phenomena may lead to the formation of microcysts, which might later become confluent and grow to form macroscopic cysts. Progress in the understanding of pathogenesis of cerebral glioma cysts might set targets for treatment of brain edema and glioma cysts.

  16. Theories of Giant Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1998-01-01

    An overview of current theories of planetary formation, with emphasis on giant planets, is presented. The most detailed models are based upon observations of our own Solar System and of young stars and their environments. While these models predict that rocky planets should form around most single stars, the frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Most models for extrasolar giant planets suggest that they formed as did Jupiter and Saturn (in nearly circular orbits, far enough from the star that ice could), and subsequently migrated to their current positions, although some models suggest in situ formation.

  17. Formation of Planets around Pulsars

    NASA Astrophysics Data System (ADS)

    Banit, M.; Ruderman, M. A.; Shaham, J.; Applegate, J. H.

    1993-10-01

    Pulse arrival-time delays PSR 1257+ 12 suggest the existence of at least two planets in nearly circular orbits around it. In this paper we discuss different scenarios for the formation of planets in circular orbits around pulsars. Among other topics, we look in some detail at wind emission mechanisms that are particularly relevant to the process of evaporation of planets around pulsars and discuss their possible role in orbit circularization. We conclude that the formation of such planets may occur in a very late phase of low-mass X-ray binary (LMXB) or binary millisecond pulsar (BMP) evolution. Evaporation of the companion star in these phases supplies matter to a circumbinary "excretion" disk in which the physical conditions, similar to those appropriate for the BMP 1957+20 system, may allow the formation of planets like those observed in PSR 1257+12.

  18. Bundle Formation in Biomimetic Hydrogels.

    PubMed

    Jaspers, Maarten; Pape, A C H; Voets, Ilja K; Rowan, Alan E; Portale, Giuseppe; Kouwer, Paul H J

    2016-08-08

    Bundling of single polymer chains is a crucial process in the formation of biopolymer network gels that make up the extracellular matrix and the cytoskeleton. This bundled architecture leads to gels with distinctive properties, including a large-pore-size gel formation at very low concentrations and mechanical responsiveness through nonlinear mechanics, properties that are rarely observed in synthetic hydrogels. Using small-angle X-ray scattering (SAXS), we study the bundle formation and hydrogelation process of polyisocyanide gels, a synthetic material that uniquely mimics the structure and mechanics of biogels. We show how the structure of the material changes at the (thermally induced) gelation point and how factors such as concentration and polymer length determine the architecture, and with that, the mechanical properties. The correlation of the gel mechanics and the structural parameters obtained from SAXS experiments is essential in the design of future (synthetic) mimics of biopolymer networks.

  19. Physicochemical regulation of biofilm formation

    PubMed Central

    Renner, Lars D.; Weibel, Douglas B.

    2011-01-01

    This article reviews the physical and chemical constraints of environments on biofilm formation. We provide a perspective on how materials science and engineering can address fundamental questions and unmet technological challenges in this area of microbiology, such as biofilm prevention. Specifically, we discuss three factors that impact the development and organization of bacterial communities. (1) Physical properties of surfaces regulate cell attachment and physiology and affect early stages of biofilm formation. (2) Chemical properties influence the adhesion of cells to surfaces and their development into biofilms and communities. (3) Chemical communication between cells attenuates growth and influences the organization of communities. Mechanisms of spatial and temporal confinement control the dimensions of communities and the diffusion path length for chemical communication between biofilms, which, in turn, influences biofilm phenotypes. Armed with a detailed understanding of biofilm formation, researchers are applying the tools and techniques of materials science and engineering to revolutionize the study and control of bacterial communities growing at interfaces. PMID:22125358

  20. Formation Flying In Highly Elliptical Orbits Initializing the Formation

    NASA Technical Reports Server (NTRS)

    Mailhe, Laurie; Schiff, Conrad; Hughes, Steven

    2000-01-01

    In this paper several methods are examined for initializing formations in which all spacecraft start in a common elliptical orbit subsequent to separation from the launch vehicle. The tetrahedron formation used on missions such as the Magnetospheric Multiscale (MMS), Auroral Multiscale Midex (AMM), and Cluster is used as a test bed Such a formation provides full three degrees-of-freedom in the relative motion about the reference orbit and is germane to several missions. The type of maneuver strategy that can be employed depends on the specific initial conditions of each member of the formation. Single-impulse maneuvers based on a Gaussian variation-of-parameters (VOP) approach, while operationally simple and intuitively-based, work only in a limited sense for a special class of initial conditions. These 'tailored' initial conditions are characterized as having only a few of the Keplerian elements different from the reference orbit. Attempts to achieve more generic initial conditions exceed the capabilities of the single impulse VOP. For these cases, multiple-impulse implementations are always possible but are generally less intuitive than the single-impulse case. The four-impulse VOP formalism discussed by Schaub is examined but smaller delta-V costs are achieved in our test problem by optimizing a Lambert solution.

  1. Formation of the first stars.

    PubMed

    Bromm, Volker

    2013-11-01

    Understanding the formation of the first stars is one of the frontier topics in modern astrophysics and cosmology. Their emergence signalled the end of the cosmic dark ages, a few hundred million years after the Big Bang, leading to a fundamental transformation of the early Universe through the production of ionizing photons and the initial enrichment with heavy chemical elements. We here review the state of our knowledge, separating the well understood elements of our emerging picture from those where more work is required. Primordial star formation is unique in that its initial conditions can be directly inferred from the Λ cold dark matter (ΛCDM) model of cosmological structure formation. Combined with gas cooling that is mediated via molecular hydrogen, one can robustly identify the regions of primordial star formation, the so-called minihalos, having total masses of ~10(6) M⊙ and collapsing at redshifts z ≈ 20-30. Within this framework, a number of studies have defined a preliminary standard model, with the main result that the first stars were predominantly massive. This model has recently been modified to include a ubiquitous mode of fragmentation in the protostellar disks, such that the typical outcome of primordial star formation may be the formation of a binary or small multiple stellar system. We will also discuss extensions to this standard picture due to the presence of dynamically significant magnetic fields, of heating from self-annihalating WIMP dark matter, or cosmic rays. We conclude by discussing possible strategies to empirically test our theoretical models. Foremost among them are predictions for the upcoming James Webb space telescope (JWST), to be launched ~2018, and for 'stellar archaeology', which probes the abundance pattern in the oldest, most-metal poor stars in our cosmic neighborhood, thereby constraining the nucleosynthesis inside the first supernovae.

  2. Magnetohydrodynamic mechanism for pedestal formation.

    PubMed

    Guazzotto, L; Betti, R

    2011-09-16

    Time-dependent two-dimensional magnetohydrodynamic simulations are carried out for tokamak plasmas with edge poloidal flow. Differently from conventional equilibrium theory, a density pedestal all around the edge is obtained when the poloidal velocity exceeds the poloidal sound speed. The outboard pedestal is induced by the transonic discontinuity, the inboard one by mass redistribution. The density pedestal follows the formation of a highly sheared flow at the transonic surface. These results may be relevant to the L-H transition and pedestal formation in high performance tokamak plasmas.

  3. Pattern formation in the geosciences

    PubMed Central

    Goehring, Lucas

    2013-01-01

    Pattern formation is a natural property of nonlinear and non-equilibrium dynamical systems. Geophysical examples of such systems span practically all observable length scales, from rhythmic banding of chemical species within a single mineral crystal, to the morphology of cusps and spits along hundreds of kilometres of coastlines. This article briefly introduces the general principles of pattern formation and argues how they can be applied to open problems in the Earth sciences. Particular examples are then discussed, which summarize the contents of the rest of this Theme Issue. PMID:24191107

  4. Star formation and extinct radioactivities

    NASA Technical Reports Server (NTRS)

    Cameron, A. G. W.

    1984-01-01

    An assessment is made of the evidence for the existence of now-extinct radioactivities in primitive solar system material, giving attention to implications for the early stages of sun and solar system formation. The characteristics of possible disturbances in dense molecular clouds which can initiate the formation of cloud cores is discussed, with emphasis on these disturbances able to generate fresh radioactivities. A one-solar mass red giant star on the asymptotic giant branch appears to have been the best candidate to account for the short-lived extinct radioactivities in the early solar system.

  5. Formation Criterion for Synthetic Jets

    DTIC Science & Technology

    2005-10-01

    formation data for the axisymmetric case were published over 50 years ago by Ingard and Labate.10 More recent studies33,34 suggest that L0/d > 1 for...with the axisymmetric data from Ingard and Labate10 and Smith et al.33 are compared in Fig. 7. It is found that the available data are consis- tent with...the jet formation criterion with an empirically determined constant K equal to approximately 0.16. The deviation of Ingard and Labate’s data at their

  6. Optimal Reconfiguration of Tetrahedral Formations

    NASA Technical Reports Server (NTRS)

    Huntington, Geoffrey; Rao, Anil V.; Hughes, Steven P.

    2004-01-01

    The problem of minimum-fuel formation reconfiguration for the Magnetospheric Multi-Scale (MMS) mission is studied. This reconfiguration trajectory optimization problem can be posed as a nonlinear optimal control problem. In this research, this optimal control problem is solved using a spectral collocation method called the Gauss pseudospectral method. The objective of this research is to provide highly accurate minimum-fuel solutions to the MMS formation reconfiguration problem and to gain insight into the underlying structure of fuel-optimal trajectories.

  7. Star formation and gas supply

    NASA Astrophysics Data System (ADS)

    Catinella, B.

    2016-06-01

    A detailed knowledge of how gas cycles in and around galaxies, and how it depends on galaxy properties such as stellar mass and star formation rate, is crucial to understand galaxy formation and evolution. We take advantage of the most sensitive surveys of cold gas in massive galaxies, GASS and COLD GASS, as well as of the state-of-the-art HI blind survey ALFALFA to investigate how molecular and atomic hydrogen reservoirs vary along and across the main sequence of star-forming galaxies.

  8. Terrestrial Planet Formation: Constraining the Formation of Mercury

    NASA Astrophysics Data System (ADS)

    Lykawka, Patryk Sofia; Ito, Takashi

    2017-04-01

    How the four terrestrial planets of the solar system formed is one of the most fundamental questions in the planetary sciences. Particularly, the formation of Mercury remains poorly understood. We investigated terrestrial planet formation by performing 110 high-resolution N-body simulation runs using more than 100 embryos and 6000 disk planetesimals representing a primordial protoplanetary disk. To investigate the formation of Mercury, these simulations considered an inner region of the disk at 0.2–0.5 au (the Mercury region) and disks with and without mass enhancements beyond the ice line location, a IL, in the disk, where a IL = 1.5, 2.25, and 3.0 au were tested. Although Venus and Earth analogs (considering both orbits and masses) successfully formed in the majority of the runs, Mercury analogs were obtained in only nine runs. Mars analogs were also similarly scarce. Our Mercury analogs concentrated at orbits with a ∼ 0.27–0.34 au, relatively small eccentricities/inclinations, and median mass m ∼ 0.2 {M}\\oplus . In addition, we found that our Mercury analogs acquired most of their final masses from embryos/planetesimals initially located between 0.2 and ∼1–1.5 au within 10 Myr, while the remaining mass came from a wider region up to ∼3 au at later times. Although the ice line was negligible in the formation of planets located in the Mercury region, it enriched all terrestrial planets with water. Indeed, Mercury analogs showed a wide range of water mass fractions at the end of terrestrial planet formation.

  9. Star formation across galactic environments

    NASA Astrophysics Data System (ADS)

    Young, Jason

    I present here parallel investigations of star formation in typical and extreme galaxies. The typical galaxies are selected to be free of active galactic nuclei (AGN), while the extreme galaxies host quasars (the most luminous class of AGN). These two environments are each insightful in their own way; quasars are among the most violent objects in the universe, literally reshaping their host galaxies, while my sample of AGN-free star-forming galaxies ranges from systems larger than the Milky Way to small galaxies which are forming stars at unsustainably high rates. The current paradigm of galaxy formation and evolution suggests that extreme circumstances are key stepping stones in the assembly of galaxies like our Milky Way. To test this paradigm and fully explore its ramifications, this dual approach is needed. My sample of AGN-free galaxies is drawn from the KPNO International Spectroscopic Survey. This Halpha-selected, volume-limited survey was designed to detect star-forming galaxies without a bias toward continuum luminosity. This type of selection ensures that this sample is not biased toward galaxies that are large or nearby. My work studies the KISS galaxies in the mid- and far-infrared using photometry from the IRAC and MIPS instruments aboard the Spitzer Space Telescope. These infrared bands are particularly interesting for star formation studies because the ultraviolet light from young stars is reprocessed into thermal emission in the far-infrared (24mum MIPS) by dust and into vibrational transitions features in the mid-infrared (8.0mum IRAC) by polycyclic aromatic hydrocarbons (PAHs). The work I present here examines the efficiencies of PAH and thermal dust emission as tracers of star-formation rates over a wide range of galactic stellar masses. I find that the efficiency of PAH as a star-formation tracer varies with galactic stellar mass, while thermal dust has a highly variable efficiency that does not systematically depend on galactic stellar mass

  10. Stereotype Formation: Biased by Association

    ERIC Educational Resources Information Center

    Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

    2010-01-01

    We propose that biases in attitude and stereotype formation might arise as a result of learned differences in the extent to which social groups have previously been predictive of behavioral or physical properties. Experiments 1 and 2 demonstrate that differences in the experienced predictiveness of groups with respect to evaluatively neutral…

  11. Army Transformation to Expeditionary Formations

    DTIC Science & Technology

    2008-01-01

    potatoes " of the United States Army. This is what our nation depends on and expects a land based anned force to be. No formation currently on this...is something to be said about form and functionality. Briefly this, kudos to Army leadership by reducing the level of maintenance ( starching , sewing

  12. Circumstellar disks and planetary formation

    NASA Astrophysics Data System (ADS)

    Huélamo, N.

    2017-03-01

    Circumstellar disks are very common around young intermediate-, low-mass stars, and brown dwarfs. They are the cradle of planetary systems, although the mechanism to form planets is still unknown. In this text I review some advances in the field of circumstellar disks and planetary formation coming from observations.

  13. Formative Assessment in Dance Education

    ERIC Educational Resources Information Center

    Andrade, Heidi; Lui, Angela; Palma, Maria; Hefferen, Joanna

    2015-01-01

    Feedback is crucial to students' growth as dancers. When used within the framework of formative assessment, or assessment for learning, feedback results in actionable next steps that dancers can use to improve their performances. This article showcases the work of two dance specialists, one elementary and one middle school teacher, who have…

  14. Formative Assessment: A Cybernetic Viewpoint

    ERIC Educational Resources Information Center

    Roos, Bertil; Hamilton, David

    2005-01-01

    This paper considers alternative assessment, feedback and cybernetics. For more than 30 years, debates about the bi-polarity of formative and summative assessment have served as surrogates for discussions about the workings of the mind, the social implications of assessment and, as important, the role of instruction in the advancement of learning.…

  15. Amyloid Beta Mediates Memory Formation

    ERIC Educational Resources Information Center

    Garcia-Osta, Ana; Alberini, Cristina M.

    2009-01-01

    The amyloid precursor protein (APP) undergoes sequential cleavages to generate various polypeptides, including the amyloid [beta] (1-42) peptide (A[beta][1-42]), which is believed to play a major role in amyloid plaque formation in Alzheimer's disease (AD). Here we provide evidence that, in contrast with its pathological role when accumulated,…

  16. Chevrons formation in laminar erosion

    NASA Astrophysics Data System (ADS)

    Devauchelle, Olivier; Josserand, Christophe; Lagree, Pierre-Yves; Zaleski, Stephane; Nguyen, Khanh-Dang; Malverti, Luce; Lajeunesse, Eric

    2007-11-01

    When eroded by laminar free-surface flows, granular substrates may generate a rich variety of natural patterns. Among them are dunes, similar to the ones observed by Charru and Hinch in a Couette cell (Charru F, Hinch EJ ; Ripple formation on a particle bed sheared by a viscous liquid. Part 1. Steady flow ; JOURNAL OF FLUID MECHANICS 550: 111-121 MAR 10 2006). Chevron-shaped instabilities as those found on the sea-shore, can also be observed, sometimes in competition against dunes formation. These were first pointed out by Daerr et al. when pulling a plate covered with granular material out of a bath of water (Daerr A, Lee P, Lanuza J, et al. ; Erosion patterns in a sediment layer ; PHYSICAL REVIEW E 67 (6): Art. No. 065201 Part 2 JUN 2003). Both instabilities can grow in laminar open-channel flows, an experimental set-up which is more easily controlled. The mechanisms leading to the formation of these patterns are investigated and compared. Whereas dunes formation requires vertical inertia effects, we show that chevrons may result from the non-linear evolution of bars instability, which may grow even in purely viscous flows.

  17. Formative Assessment in Primary Science

    ERIC Educational Resources Information Center

    Loughland, Tony; Kilpatrick, Laetitia

    2015-01-01

    This action learning study in a year three classroom explored the implementation of five formative assessment principles to assist students' understandings of the scientific topic of liquids and solids. These principles were employed to give students a greater opportunity to express their understanding of the concepts. The study found that the…

  18. Formative Considerations Using Integrative CALL.

    ERIC Educational Resources Information Center

    Callahan, Philip; Shaver, Peter

    2001-01-01

    Addresses technical and learning issues relating to a formative implementation of a computer assisted language learning (CALL) browser-based intermediate Russian program. Instruction took place through a distance education implementation and in a grouped classroom using a local-area network. Learners indicated the software was clear, motivating,…

  19. The EPRDATA Format: A Dialogue

    SciTech Connect

    Hughes, III, Henry Grady

    2015-08-18

    Recently the Los Alamos Nuclear Data Team has communicated certain issues of concern in relation to the new electron/photon/relaxation ACE data format as released in the eprdata12 library. In this document those issues are parsed, analyzed, and answered.

  20. Audiences for Contemporary Radio Formats.

    ERIC Educational Resources Information Center

    Lull, James T.; And Others

    A radio audience survey of 110 sample geographic clusters in the Santa Barbara, California, area served a twofold purpose: the construction of a demographic profile of audience types according to radio format choices, and the identification and analysis of various audience subgroups. A skip interval technique of these geographic clusters resulted…

  1. Formative Evaluation as Management Information.

    ERIC Educational Resources Information Center

    Petrosko, Joseph M.; And Others

    This paper deals with systems concepts, particularly those related to management information systems (MIS) as exemplified by the Center for the Study of Evaluation (CSE) Formative Evaluation Kit. The concept of MIS is in numerous ways more flexible than might be imagined from a cursory reading of the business-management literature. An MIS does not…

  2. Cloud formation in substellar atmospheres

    NASA Astrophysics Data System (ADS)

    Helling, Christiane

    2009-02-01

    Clouds seem like an every-day experience. But-do we know how clouds form on brown dwarfs and extra-solar planets? How do they look like? Can we see them? What are they composed of? Cloud formation is an old-fashioned but still outstanding problem for the Earth atmosphere, and it has turned into a challenge for the modelling of brown dwarf and exo-planetary atmospheres. Cloud formation imposes strong feedbacks on the atmospheric structure, not only due to the clouds own opacity, but also due to the depletion of the gas phase, possibly leaving behind a dynamic and still supersaturated atmosphere. I summarise the different approaches taken to model cloud formation in substellar atmospheres and workout their differences. Focusing on the phase-non-equilibrium approach to cloud formation, I demonstrate the inside we gain from detailed microphysical modelling on for instance the material composition and grain size distribution inside the cloud layer on a Brown Dwarf atmosphere. A comparison study on four different cloud approaches in Brown Dwarf atmosphere simulations demonstrates possible uncertainties in interpretation of observational data.

  3. SAS FORMATS: USES AND ABUSES

    EPA Science Inventory

    SAS formats are a very powerful tool. They allow you to display the data in a more readable manner without modifying the data. They can also be used to group data into categories for use in various procedures like PROC FREQ, PROC TTEST, and PROC MEANS (as a class variable). ...

  4. A standard audit trail format

    SciTech Connect

    Bishop, M.

    1995-02-01

    The central role of audit trails, or (more properly) logs, in security monitoring needs little description, for it is too well known for any to doubt it. Auditing, or the analysis of logs, is a central part of security not only in computer system security but also in analyzing financial and other non-technical systems. As part of this process, it is often necessary to reconcile logs from different sources. This speaks of a need for a standard logging format. A standard log format robust enough to meet the needs of heterogeneity, transportability across various network protocols, and flexibility sufficient to meet a variety of needs in very different environments must satisfy two basic properties: extensibility and portability. This report presents the author`s proposed format for a standard log record. In section 3, he shows how and where the translation should be done, and in section 4 he demonstrates how log records from several disparate systems would be put into this format. Section 5 concludes with some observations and suggestions for future work.

  5. Mantle dynamics following supercontinent formation

    NASA Astrophysics Data System (ADS)

    Heron, Philip J.

    This thesis presents mantle convection numerical simulations of supercontinent formation. Approximately 300 million years ago, through the large-scale subduction of oceanic sea floor, continental material amalgamated to form the supercontinent Pangea. For 100 million years after its formation, Pangea remained relatively stationary, and subduction of oceanic material featured on its margins. The present-day location of the continents is due to the rifting apart of Pangea, with supercontinent dispersal being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The work presented here investigates the thermal evolution of mantle dynamics (e.g., mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Specifically, continental insulation and continental margin subduction are analyzed. Continental material, as compared to oceanic material, inhibits heat flow from the mantle. Previous numerical simulations have shown that the formation of a stationary supercontinent would elevate sub-continental mantle temperatures due to the effect of continental insulation, leading to the break-up of the continent. By modelling a vigorously convecting mantle that features thermally and mechanically distinct continental and oceanic plates, this study shows the effect of continental insulation on the mantle to be minimal. However, the formation of a supercontinent results in sub-continental plume formation due to the re-positioning of subduction zones to the margins of the continent. Accordingly, it is demonstrated that continental insulation is not a significant factor in producing sub-supercontinent plumes but that subduction patterns control the location and timing of upwelling formation. A theme throughout the thesis is an inquiry into why geodynamic studies would produce different results. Mantle viscosity, Rayleigh number, continental size, continental insulation, and oceanic plate boundary evolution are

  6. Wintertime Haze Formation in Beijing

    NASA Astrophysics Data System (ADS)

    Levy Zamora, M. E.

    2015-12-01

    Recent severe haze events in China have attracted significant public attention due to the severely reduced visibility and unprecedentedly high pollutant concentrations. Particular attention has been given to the high concentrations of particulate matter with a diameter less than 2.5 microns (PM2.5), which can exceed several hundred micrograms per cubic meter over several days. During January and February of 2015, a suite of aerosol instruments was deployed in Beijing to directly measure a comprehensive set of aerosol properties, including the particle size distribution, effective density, and chemical composition. In this presentation, we will discuss the particulate matter formation mechanisms, the evolution of aerosol properties throughout the event, and how the winter formation mechanisms compare with the warmer seasons. We show that the periodic cycles of severe haze episodes in Beijing are largely driven by meteorological conditions. During haze events, stagnation typically develops as a result of a low planetary boundary layer and weak southerly wind from polluted industrial source regions. Stronger northerly winds were frequently observed during the clean period, which carry unpolluted air masses from the less populated northern mountainous areas. Nucleation consistently occurs on clean days, producing a high number concentration of nano particles. The particle mass concentration exceeding several hundred micrograms per cubic meter is attributed to the continuous size growth from the nucleation-mode particles (diameter less than 10 nm) over multiple days to produce a high concentration of larger particles (diameter greater than 100 nm). The particle chemical composition in Beijing is similar to those commonly measured in other urban centers, which is indicative of chemical constituents dominated by secondary aerosol formation. Our results reveal that the severe haze formation in Beijing during the wintertime is similar to the mechanism of haze formation

  7. Inside-out planet formation

    SciTech Connect

    Chatterjee, Sourav; Tan, Jonathan C. E-mail: jt@astro.ufl.edu

    2014-01-01

    The compact multi-transiting planet systems discovered by Kepler challenge planet formation theories. Formation in situ from disks with radial mass surface density, Σ, profiles similar to the minimum mass solar nebula but boosted in normalization by factors ≳ 10 has been suggested. We propose that a more natural way to create these planets in the inner disk is formation sequentially from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (∼cm-m size) 'pebbles', drifting inward via gas drag. Pebbles collect at the pressure maximum associated with the transition from a magnetorotational instability (MRI)-inactive ('dead zone') region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an ∼1 M {sub ⊕} planet directly or induces gradual planet formation via core accretion. The planet may undergo Type I migration into the active region, allowing a new pebble ring and planet to form behind it. Alternatively, if migration is inefficient, the planet may continue to accrete from the disk until it becomes massive enough to isolate itself from the accretion flow. A variety of densities may result depending on the relative importance of residual gas accretion as the planet approaches its isolation mass. The process can repeat with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. Our simple analytical model for this scenario of inside-out planet formation yields planetary masses, relative mass scalings with orbital radius, and minimum orbital separations consistent with those seen by Kepler. It provides an explanation of how massive planets can form with tightly packed and well-aligned system architectures, starting from typical protoplanetary disk properties.

  8. The Multifaceted Planetesimal Formation Process

    NASA Astrophysics Data System (ADS)

    Johansen, A.; Blum, J.; Tanaka, H.; Ormel, C.; Bizzarro, M.; Rickman, H.

    Accumulation of dust and ice particles into planetesimals is an important step in the planet formation process. Planetesimals are the seeds of both terrestrial planets and the solid cores of gas and ice giants forming by core accretion. Leftover planetesimals in the form of asteroids, transneptunian objects, and comets provide a unique record of the physical conditions in the solar nebula. Debris from planetesimal collisions around other stars signposts that the planetesimal formation process, and hence planet formation, is ubiquitous in the Galaxy. The planetesimal formation stage extends from micrometer-sized dust and ice to bodies that can undergo runaway accretion. The latter ranges in size from 1 km to 1000 km, dependent on the planetesimal eccentricity excited by turbulent gas density fluctuations. Particles face many barriers during this growth, arising mainly from inefficient sticking, fragmentation, and radial drift. Two promising growth pathways are mass transfer, where small aggregates transfer up to 50% of their mass in high-speed collisions with much larger targets, and fluffy growth, where aggregate cross sections and sticking probabilities are enhanced by a low internal density. A wide range of particle sizes, from 1 mm to 10 m, concentrate in the turbulent gas flow. Overdense filaments fragment gravitationally into bound particle clumps, with most mass entering planetesimals of contracted radii from 100 km to 500 km, depending on local disk properties. We propose a hybrid model for planetesimal formation where particle growth starts unaided by self-gravity but later proceeds inside gravitationally collapsing pebble clumps to form planetesimals with a wide range of sizes.

  9. The Black Hole Formation Probability

    NASA Astrophysics Data System (ADS)

    Clausen, Drew R.; Piro, Anthony; Ott, Christian D.

    2015-01-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. Using the observed BH mass distribution from Galactic X-ray binaries, we investigate the probability that a star will make a BH as a function of its ZAMS mass. Although the shape of the black hole formation probability function is poorly constrained by current measurements, we believe that this framework is an important new step toward better understanding BH formation. We also consider some of the implications of this probability distribution, from its impact on the chemical enrichment from massive stars, to its connection with the structure of the core at the time of collapse, to the birth kicks that black holes receive. A probabilistic description of BH formation will be a useful input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  10. Dioxin formation from waste incineration.

    PubMed

    Shibamoto, Takayuki; Yasuhara, Akio; Katami, Takeo

    2007-01-01

    There has been great concern about dioxins-polychlorinated dibenzo dioxins (PCDDs), polychlorinated dibenzo furans (PCDFs), and polychlorinated biphenyls (PCBs)-causing contamination in the environment because the adverse effects of these chemicals on human health have been known for many years. Possible dioxin-contamination has received much attention recently not only by environmental scientists but also by the public, because dioxins are known to be formed during the combustion of industrial and domestic wastes and to escape into the environment via exhaust gases from incinerators. Consequently, there is a pressing need to investigate the formation mechanisms or reaction pathways of these chlorinated chemicals to be able to devise ways to reduce their environmental contamination. A well-controlled small-scale incinerator was used for the experiments in the core references of this review. These articles report the investigation of dioxin formation from the combustion of various waste-simulated samples, including different kinds of paper, various kinds of wood, fallen leaves, food samples, polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride, polyethylene tetraphthalate (PET), and various kinds of plastic products. These samples were also incinerated with inorganic chlorides (NaCl, KCl, CuCI2, MgCl2, MnCl2, FeCl2, CoCl2, fly ash, and seawater) or organic chlorides (PVC, chlordane, and pentachlorophenol) to investigate the role of chlorine content and/or the presence of different metals in dioxin formation. Some samples, such as newspapers, were burned after they were impregnated with NaCl or PVC, as well as being cocombusted with chlorides. The roles of incineration conditions, including chamber temperatures, O2 concentrations, and CO concentrations, in dioxin formation were also investigated. Dioxins (PCDDs, PCDFs, and coplanar-PCBs) formed in the exhaust gases from a controlled small-scale incinerator, where experimental waste

  11. What Is Formation? A Conceptual Discussion

    ERIC Educational Resources Information Center

    Sutphen, Molly; de Lange, Thomas

    2015-01-01

    This paper addresses the principles and connotations of the term "formation." In our discussion of formation, we draw on different disciplines in order to widen and deepen our understanding of the concept of formation. We also mirror the formation concept against comparable terms and draw on studies in which it has been applied in…

  12. Formation of Molecular Clouds and Initial Conditions of Star Formation

    NASA Astrophysics Data System (ADS)

    Inoue, Tsuyoshi

    2013-07-01

    Using three-dimensional magnetohydrodynamic simulations, including the effects of radiative cool- ing/heating, chemical reactions, self-gravity and thermal conduction, we investigate the formation of molecular clouds in the multi-phase interstellar medium. We consider the formation of molecular clouds due to accretion of HI clouds as suggested by recent observations. Our simulations show that the initial HI medium is piled up behind the shock waves induced by accretion flows. Since the accreting medium is highly inhomogeneous as a consequence of thermal instability, a newly formed molecular cloud becomes very turbulent owing to the development of the Richtmyer-Meshkov instability. The kinetic energy of the turbulence dominates the thermal, magnetic, and gravitational energies. However, the kinetic energy measured using CO-fraction-weighted density is comparable to the other energies, once the CO molecules are sufficiently formed as a result of UV shielding. This suggests that the true kinetic energy of turbulence in molecular clouds as a whole can be much larger than the kinetic energy of turbulence estimated by using line widths of molecular emission. We find that dense clumps in the molecular cloud show the following evolution: the typical plasma beta of the clumps is roughly constant; the size-ělocity dispersion relation follows Larson's law, irrespective of the density; and the clumps evolve into magnetically supercritical cores by clump-clump collisions. These statistical properties would represent the initial conditions of star formation.

  13. Method of fracturing a geological formation

    DOEpatents

    Johnson, James O.

    1990-01-01

    An improved method of fracturing a geological formation surrounding a well bore is disclosed. A relatively small explosive charge is emplaced in a well bore and the bore is subsequently hydraulically pressurized to a pressure less than the formation breakdown pressure and preferably greater than the fracture propagation pressure of the formation. The charge is denoted while the bore is so pressurized, resulting in the formation of multiple fractures in the surrounding formation with little or no accompanying formation damage. Subsequent hydraulic pressurization can be used to propagate and extend the fractures in a conventional manner. The method is useful for stimulating production of oil, gas and possibly water from suitable geologic formations.

  14. ASDF: A new data format for astronomy

    NASA Astrophysics Data System (ADS)

    Greenfield, P.; Droettboom, M.; Bray, E.

    2015-09-01

    We present the case for developing a successor format for the immensely successful FITS format. We first review existing alternative formats and discuss why we do not believe they provide an adequate solution. The proposed format is called the Advanced Scientific Data Format (ASDF) and is based on an existing text format, YAML, that we believe removes most of the current problems with the FITS format. An overview of the capabilities of the new format is given along with specific examples. This format has the advantage that it does not limit the size of attribute names (akin to FITS keyword names) nor place restrictions on the size or type of values attributes have. Hierarchical relationships are explicit in the syntax and require no special conventions. Finally, it is capable of storing binary data within the file in its binary form. At its basic level, the format proposed has much greater applicability than for just astronomical data.

  15. Treating tar sands formations with dolomite

    DOEpatents

    Vinegar, Harold J.; Karanikas, John Michael

    2010-06-08

    Methods for treating a tar sands formation are described herein. The tar sands formation may include dolomite and hydrocarbons. Methods may include providing heat at less than the decomposition temperature of dolomite from one or more heaters to at least a portion of the formation. At least some of the hydrocarbon fluids are mobilized in the formation. At least some of the hydrocarbon fluids may be produced from the formation.

  16. Field technique of permeability tests in highly fissured limestone strata

    NASA Astrophysics Data System (ADS)

    Al-Salihi, Adnan; Asaad, Abdulah

    2002-05-01

    Résumé.L'étude de dispositifs de dénoyage est nécessaire pour l'amélioration de sites avant la construction de certaines structures. L'étude de dispositifs de dénoyage efficaces exige d'estimer la valeur du coefficient de perméabilité in situ. Les relations disponibles pour estimer le coefficient de perméabilité ont été développées sur la base de mesures et de conditions de terrain limitées, et les prédictions varient de plusieurs ordres de grandeur. C'est pourquoi il est nécessaire de réaliser des mesures de perméabilité sur le terrain et de déterminer la relation qui permet le meilleur ajustement de ces mesures avant l'étude du dispositif de dénoyage pour des conditions locales et géologiques spécifiques. Ce papier présente des mesures de perméabilité sur le terrain dans des niveaux calcaires complexes chaotiques et diagénétisés. Il propose également une analyse comparative de plusieurs relations disponibles dans la littérature destinées à prédire le coefficient de perméabilité in situ. L'analyse est faite en conditions permanentes et non permanentes. Les résultats montrent que la valeur du coefficient de perméabilité dépend du niveau de la nappe, qui est affecté par le régime de marées. On montre que l'équation de l'US Navy donne la meilleure corrélation avec les mesures de terrain. Resumen.El diseño de sistemas de desecado es necesario para mejorar las condiciones de un emplazamiento antes de la construcción de determinadas estructuras. El diseño de un sistema eficiente de desecado requiere de la estimación del valor de la permeabilidad in-situ. Las relaciones disponibles para tal fin han sido desarrolladas bajo condiciones y medidas de campo limitadas; sus predicciones varían en algunos órdenes de magnitud. Por tanto, es necesario tomar medidas de permeabilidad en campo y determinar la relación que reproduce mejor dichas medidas como paso previo al diseño de un sistema de desecado en condiciones geológicas y de emplazamiento específicas. Este artículo presenta medidas de permeabilidad en campo para estratos de calcita caóticos y diagenéticos. También ofrece un análisis comparativo de diversas relaciones disponibles en la bibliografía con el fin de predecir el valor de la permeabilidad in-situ. El análisis se ha hecho tanto en régimen permanente como en estacionario. Los resultados demuestran que la permeabilidad depende del nivel freático, el cual está afectado por las mareas. La ecuación de la Marina estadounidense es la que proporciona una mejor correlación con las medidas de campo.

  17. Slopes in Stiff-fissured Clays and Shales

    DTIC Science & Technology

    1968-06-01

    shown that the Cucaracha and Culebra clay shales from the Panama Canal Zone, C and the Pierre shale from the Oahe damsite in South Dakota all exhibit...rapidly conducted tests, and in tests of 30 days duration the strength was about 22% less. The strength loss for Cucaracha clay shale was even more

  18. Suivi de fissuration de matériaux par thermographie

    NASA Astrophysics Data System (ADS)

    Ait Aouit, Djedjiga; Ouahabi, Abdeldjalil

    2008-08-01

    The purpose of this work is to present a novel strategy for real-time monitoring crack growth of materials. The process is based on the use of thermal data extracted along the horizontal axis of symmetry of single edge notch tension (SENT) specimens, during fatigue tests. These data are exploited using an implemented program to detect in situ the growth of fatigue crack, with the critical size and propagation speed of the crack. This technique has the advantage to be applicable to a wide range of materials regardless of their electrical conductivity and their surface texture. To cite this article: D. Ait Aouit, A. Ouahabi, C. R. Mecanique 336 (2008).

  19. An advanced algorithm for highway pavement fissure detection

    NASA Astrophysics Data System (ADS)

    Chen, Bei; Cao, Wenlun; He, Yuyao

    2012-04-01

    This paper presents image detection method of pavement crack based on fractal dimension feature and designs self-adapting algorithm of fractal dimension interval of pavement region. Through image pretreatment, calculation of fractal dimension, self-adapting calculation of dimension interval, we obtain the location image of damage pavement. The experimental results of transverse crack, longitudinal crack, net-shaped crack, pit slot are contrast with that of Sobel operator. The results show that they have the similar capability on the representation of crack, but the proposed method is more flexible on the aspect of representation of crack size and calculation of damage ratio.

  20. Laser beam pulse formatting method

    DOEpatents

    Daly, Thomas P.; Moses, Edward I.; Patterson, Ralph W.; Sawicki, Richard H.

    1994-01-01

    A method for formatting a laser beam pulse (20) using one or more delay loops (10). The delay loops (10) have a partially reflective beam splitter (12) and a plurality of highly reflective mirrors (14) arranged such that the laser beam pulse (20) enters into the delay loop (10) through the beam splitter (12) and circulates therein along a delay loop length (24) defined by the mirrors (14). As the laser beam pulse (20) circulates within the delay loop (10) a portion thereof is emitted upon each completed circuit when the laser beam pulse (20) strikes the beam splitter (12). The laser beam pulse (20) is thereby formatted into a plurality of sub-pulses (50, 52, 54 and 56). The delay loops (10) are used in combination to produce complex waveforms by combining the sub-pulses (50, 52, 54 and 56) using additive waveform synthesis.

  1. Complexity of formation in holography

    NASA Astrophysics Data System (ADS)

    Chapman, Shira; Marrochio, Hugo; Myers, Robert C.

    2017-01-01

    It was recently conjectured that the quantum complexity of a holographic boundary state can be computed by evaluating the gravitational action on a bulk region known as the Wheeler-DeWitt patch. We apply this complexity=action duality to evaluate the `complexity of formation' [1, 2], i.e. the additional complexity arising in preparing the entangled thermofield double state with two copies of the boundary CFT compared to preparing the individual vacuum states of the two copies. We find that for boundary dimensions d > 2, the difference in the complexities grows linearly with the thermal entropy at high temperatures. For the special case d = 2, the complexity of formation is a fixed constant, independent of the temperature. We compare these results to those found using the complexity=volume duality.

  2. Galaxy formation through hierarchical clustering

    NASA Technical Reports Server (NTRS)

    White, Simon D. M.; Frenk, Carlos S.

    1991-01-01

    Analytic methods for studying the formation of galaxies by gas condensation within massive dark halos are presented. The present scheme applies to cosmogonies where structure grows through hierarchical clustering of a mixture of gas and dissipationless dark matter. The simplest models consistent with the current understanding of N-body work on dissipationless clustering, and that of numerical and analytic work on gas evolution and cooling are adopted. Standard models for the evolution of the stellar population are also employed, and new models for the way star formation heats and enriches the surrounding gas are constructed. Detailed results are presented for a cold dark matter universe with Omega = 1 and H(0) = 50 km/s/Mpc, but the present methods are applicable to other models. The present luminosity functions contain significantly more faint galaxies than are observed.

  3. Geologic 'Face on Mars' Formation

    NASA Technical Reports Server (NTRS)

    1976-01-01

    NASA's Viking 1 Orbiter spacecraft photographed this region in the northern latitudes of Mars on July 25, 1976 while searching for a landing site for the Viking 2 Lander. The speckled appearance of the image is due to missing data, called bit errors, caused by problems in transmission of the photographic data from Mars to Earth. Bit errors comprise part of one of the 'eyes' and 'nostrils' on the eroded rock that resembles a human face near the center of the image. Shadows in the rock formation give the illusion of a nose and mouth. Planetary geologists attribute the origin of the formation to purely natural processes. The feature is 1.5 kilometers (one mile) across, with the sun angle at approximately 20 degrees. The picture was taken from a range of 1,873 kilometers (1,162 miles).

  4. The dynamics of city formation*

    PubMed Central

    Henderson, J. Vernon; Venables, Anthony J.

    2013-01-01

    This paper examines city formation in a country whose urban population is growing steadily over time, with new cities required to accommodate this growth. In contrast to most of the literature there is immobility of housing and urban infrastructure, and investment in these assets is taken on the basis of forward-looking behavior. In the presence of these fixed assets cities form sequentially, without the population swings in existing cities that arise in current models, but with swings in house rents. Equilibrium city size, absent government, may be larger or smaller than is efficient, depending on how urban externalities vary with population. Efficient formation of cities with internalization of externalities involves local government intervention and borrowing to finance development. The paper explores the institutions required for successful local government intervention. PMID:25089087

  5. Rapid gas hydrate formation process

    DOEpatents

    Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.

    2013-01-15

    The disclosure provides a method and apparatus for forming gas hydrates from a two-phase mixture of water and a hydrate forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas hydrate. The reaction zone pressure is less than the mixing zone pressure so that expansion of the hydrate-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the hydrate-forming gas. The result of the process is the formation of gas hydrates continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.

  6. Cosmological models of galaxy formation

    NASA Astrophysics Data System (ADS)

    Menci, N.

    I review the present status of galaxy formation models within a cosmological framework. I focus on semi-analytic models based on the Cold Dark Matter scenario, discussing the role of the different physical process involving dark matter and baryons in determining the observed statistical properties of galaxies and their dependence on cosmic time and on environment evolution. I will highlight some present problems and briefly present the main effects of assuming a Warm Dark Matter scenario.

  7. Formation of the Light Infantry.

    DTIC Science & Technology

    1986-03-21

    This essay examines the formation of the light infantry. Initially, the requirements for strategic deployment and deterrence are examined. The...background that led to the decision to form this type of division is discussed. The author reviews the historical precedence for light infantry force. Using...issues addressed consider the relationship of the light force to the Army’s New Manning System, COHORT. Other personnel matters examined include the

  8. Hydrogen Sulfide Inhibits Amyloid Formation

    PubMed Central

    2015-01-01

    Amyloid fibrils are large aggregates of misfolded proteins, which are often associated with various neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and vascular dementia. The amount of hydrogen sulfide (H2S) is known to be significantly reduced in the brain tissue of people diagnosed with Alzheimer’s disease relative to that of healthy individuals. These findings prompted us to investigate the effects of H2S on the formation of amyloids in vitro using a model fibrillogenic protein hen egg white lysozyme (HEWL). HEWL forms typical β-sheet rich fibrils during the course of 70 min at low pH and high temperatures. The addition of H2S completely inhibits the formation of β-sheet and amyloid fibrils, as revealed by deep UV resonance Raman (DUVRR) spectroscopy and ThT fluorescence. Nonresonance Raman spectroscopy shows that disulfide bonds undergo significant rearrangements in the presence of H2S. Raman bands corresponding to disulfide (RSSR) vibrational modes in the 550–500 cm–1 spectral range decrease in intensity and are accompanied by the appearance of a new 490 cm–1 band assigned to the trisulfide group (RSSSR) based on the comparison with model compounds. The formation of RSSSR was proven further using a reaction with TCEP reduction agent and LC-MS analysis of the products. Intrinsic tryptophan fluorescence study shows a strong denaturation of HEWL containing trisulfide bonds. The presented evidence indicates that H2S causes the formation of trisulfide bridges, which destabilizes HEWL structure, preventing protein fibrillation. As a result, small spherical aggregates of unordered protein form, which exhibit no cytotoxicity by contrast with HEWL fibrils. PMID:25545790

  9. The Chemistry of Planet Formation

    NASA Astrophysics Data System (ADS)

    Oberg, Karin I.

    2017-01-01

    Exo-planets are common, and they span a large range of compositions. The origins of the observed diversity of planetary compositions is largely unconstrained, but must be linked to the planet formation physics and chemistry. Among planets that are Earth-like, a second question is how often such planets form hospitable to life. A fraction of exo-planets are observed to be ‘physically habitable’, i.e. of the right temperature and bulk composition to sustain a water-based prebiotic chemistry, but this does not automatically imply that they are rich in the building blocks of life, in organic molecules of different sizes and kinds, i.e. that they are chemically habitable. In this talk I will argue that characterizing the chemistry of protoplanetary disks, the formation sites of planets, is key to address both the origins of planetary bulk compositions and the likelihood of finding organic matter on planets. The most direct path to constrain the chemistry in disks is to directly observe it. In the age of ALMA it is for the first time possible to image the chemistry of planet formation, to determine locations of disk snowlines, and to map the distributions of different organic molecules. Recent ALMA highlights include constraints on CO snowline locations, the discovery of spectacular chemical ring systems, and first detections of more complex organic molecules. Observations can only provide chemical snapshots, however, and even ALMA is blind to the majority of the chemistry that shapes planet formation. To interpret observations and address the full chemical complexity in disks requires models, both toy models and astrochemical simulations. These models in turn must be informed by laboratory experiments, some of which will be shown in this talk. It is thus only when we combine observational, theoretical and experimental constraints that we can hope to characterize the chemistry of disks, and further, the chemical compositions of nascent planets.

  10. Star Formation in MUSCEL Galaxies

    NASA Astrophysics Data System (ADS)

    Young, Jason; Kuzio de Naray, Rachel; Wang, Sharon Xuesong

    2017-01-01

    We present preliminary star-formation histories for a subset of the low surface brightness (LSB) galaxies in the MUSCEL (MUltiwavelength observations of the Structure, Chemistry, and Evolution of LSB galaxies) program. These histories are fitted against ground-based IFU spectra in tandem with space-based UV and IR photometry. MUSCEL aims to use these histories along with kinematic analyses to determine the physical processes that have caused the evolution of LSB galaxies to diverge from their high surface brightness counterparts.

  11. THE BLACK HOLE FORMATION PROBABILITY

    SciTech Connect

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P {sub BH}(M {sub ZAMS}). Although we find that it is difficult to derive a unique P {sub BH}(M {sub ZAMS}) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P {sub BH}(M {sub ZAMS}) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P {sub BH}(M {sub ZAMS}) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  12. Spray formation with complex fluids

    NASA Astrophysics Data System (ADS)

    Lustig, S.; Rosen, M.

    2011-05-01

    Droplet formation through Faraday excitation has been tested in the low driving frequency limit. Kerosene was used to model liquid fuel with the addition of PIB in different proportions. All fluids were characterized in detail. The mechanisms of ejection were investigated to identify the relative influence of viscosity and surface tension. It was also possible to characterize the type of instability leading to the emission drop process.

  13. Theoretical Studies of Nanocluster Formation

    DTIC Science & Technology

    2016-05-26

    Briefing Charts 3. DATES COVERED (From - To) 22 April 2016 - 25 May 2016 4. TITLE AND SUBTITLE Theoretical Studies of nanocluster formation 5a. CONTRACT...Date: 5/5/2016 14. ABSTRACT Viewgraph/Briefing Charts 15. SUBJECT TERMS N/A 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18...SAR 17 19b. TELEPHONE NO (include area code) N/A Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 Theoretical studies of

  14. Mechanistic Models of Soot Formation

    DTIC Science & Technology

    1993-07-14

    incorporating a soot formation model into a flame code, the effects of changes in the thermodynamics of the average PAH moiety as PAH’s increase in size is...thermodynamics can have a substantial effect on the equilibrium situation between a fuel, molecular hydrogen and the polyaromatic product. For example, consider a...one atm-cm or more, it was shown that optical thickness effects can become important and an expression was derived for self-absorption 5 . Radiative

  15. The Black Hole Formation Probability

    NASA Astrophysics Data System (ADS)

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH(M ZAMS). Although we find that it is difficult to derive a unique P BH(M ZAMS) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH(M ZAMS) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH(M ZAMS) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  16. Vortex Formation in Shallow Flows

    NASA Astrophysics Data System (ADS)

    Rockwell, Donald

    2006-11-01

    Vortical structures having a scale much larger than the depth of the flow, which arise in bluff body wakes, jets, and mixing layers generated in shallow layers, show distinctive features due to the influence of bed friction. Cinema techniques of high-image-density particle image velocimetry are employed to characterize quasi-two-dimensional and three-dimensional aspects of the vortex development in terms of: patterns of vorticity; flow topology involving definition of critical points; and global spectral and cross-spectral analyses, based on simultaneous time records at thousands of grid points of the cinema imaging. Taken together, these representations lead to an understanding of the relationship between coherent vortex development and unsteadiness along the bed and, furthermore, provide a basis for exploration of concepts generic to separated shear layers in shallow flows. These concepts include: suppression of a primary mode of vortex formation due to bed friction and emergence of another mode; resonant coupling between a gravity wave of the shallow layer and vortex formation, leading to large-scale vortices; and passive and active (open loop) control, which can either retard or enhance the onset of vortex formation. These studies suggest opportunities for further investigation on both experimental and numerical fronts. Collaboration with Haojun Fu, Alis Ekmekci, Jung-Chang Lin, and Muammer Ozgoren is gratefully acknowledged.

  17. Theory of Planetary System Formation

    NASA Technical Reports Server (NTRS)

    Cassen, Patrick

    1996-01-01

    Observations and theoretical considerations support the idea that the Solar System formed by the collapse of tenuous interstellar matter to a disk of gas and dust (the primitive solar nebula), from which the Sun and other components separated under the action of dissipative forces and by the coagulation of solid material. Thus, planets are understood to be contemporaneous byproducts of star formation. Because the circumstellar disks of new stars are easier to observe than mature planetary systems, the possibility arises that the nature and variety of planets might be studied from observations of the conditions of their birth. A useful theory of planetary system formation would therefore relate the properties of circumstellar disks both to the initial conditions of star formation and to the consequent properties of planets to those of the disk. Although the broad outlines of such a theory are in place, many aspects are either untested, controversial, or otherwise unresolved; even the degree to which such a comprehensive theory is possible remains unknown.

  18. Positronium formation in various polyimides

    NASA Astrophysics Data System (ADS)

    Okamoto, Ken-ichi; Tanaka, Kazuhiro; Katsube, Mikio; Sueoka, Osamu; Ito, Yasuo

    1993-03-01

    Positronium (Ps) formation in various polyimides has been studied. It has been found that Ps yield is zero or small in the polyimides having pyromellitic dianhydride (PMDA) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) as acid anhydride moiety, while those having 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 2,2- bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) form Ps with intensities up to about 20%. This difference is well correlated with the electron affinity of these moieties: PMDA > BTDA > BPDA ˜ 6FDA. In another experiment o-Ps yields and its lifetimes were measured in benzene solutions of monomeric model compounds (imide compounds prepared from n-butylamine and the acid anhydrides). It has been found that the model compounds from PMDA and BTDA both inhibit Ps formation and quench o-Ps lifetimes but that those from BPDA and 6FDA have neither the inhibition nor the quenching effects. The results show that the spur model is applicable for Ps formation in the polyimides.

  19. Formation of Outer Planets: Overview

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack

    2003-01-01

    An overview of current theories of planetary formation, with emphasis on giant planets is presented. The most detailed models are based upon observation of our own Solar System and of young stars and their environments. Terrestrial planets are believe to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. According to the prevailing core instability model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk disspates. The primary questions regarding the core instability model is whether planets with small cores can accrete gaseous enveloples within the lifetimes of gaseous protoplanetary disks. The main alternative giant planet formation model is the disk instability model, in which gaseous planets form directly via gravitational instabilities within protoplanetary disks. Formation of giant planets via gas instability has never been demonstrated for realistic disk conditions. Moreover, this model has difficulty explaining the supersolar abundances of heavy elements in Jupiter and Saturn, and it does not explain the orgin of planets like Uranus and Neptune.

  20. EXPERIMENTAL INVESTIGATION OF PIC FORMATION ...

    EPA Pesticide Factsheets

    The report gives results of experiments to assess: (1) the effect of residual copper retained in an incineration facility on polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF) formation during incineration of non-copper-containing chlorofluorocarbons (CFCs); and (2) the formation of chlorinated and aromatic products of incomplete combustion (PICs), including PCDD/PCDFs, during incineration of CFC recycling residue and hydrochlorofluorocarbons (HCFCs). High concentrations of PCDD/PCDFs (23,800 ng/dscm at 7% O2) measured in FY91 during incineration of CFC-12 in a turbulent flame reactor (TFR) could not be repeated in the present study. Repetition tests conducted in the same facility under similar operating conditions resulted in PCDD/PCDF concentrations of 118ng/dscm at 7% O2. However, results of the present study suggest that residual copper retained in an incineration facility possibly promotes the formation of PCDD/PCDFs during incineration of CFC-12 which does not contain copper. Tests conducted in the TFR resulted in measured PCDD/PCDF concentrations of 386-454 ng/dscm at 7% O2 during incineration of CFC-12 which followed incineration of copper-containing compounds. These results suggest that CFCs may best be incinerated in incinerators which do not treat any copper-containing waste prior to CFC incineration. Report available at NTIS as PB96152186. To share information

  1. NSDF: Neuroscience Simulation Data Format.

    PubMed

    Ray, Subhasis; Chintaluri, Chaitanya; Bhalla, Upinder S; Wójcik, Daniel K

    2016-04-01

    Data interchange is emerging as an essential aspect of modern neuroscience. In the areas of computational neuroscience and systems biology there are multiple model definition formats, which have contributed strongly to the development of an ecosystem of simulation and analysis tools. Here we report the development of the Neuroscience Simulation Data Format (NSDF) which extends this ecosystem to the data generated in simulations. NSDF is designed to store simulator output across scales: from multiscale chemical and electrical signaling models, to detailed single-neuron and network models, to abstract neural nets. It is self-documenting, efficient, modular, and scalable, both in terms of novel data types and in terms of data volume. NSDF is simulator-independent, and can be used by a range of standalone analysis and visualization tools. It may also be used to store variety of experimental data. NSDF is based on the widely used HDF5 (Hierarchical Data Format 5) specification and is open, platform-independent, and portable.

  2. Ionization and Triggered Star Formation

    NASA Astrophysics Data System (ADS)

    Gritschneder, M.; Lin, D. N. C.; Murray, S. D.; Burkert, A.

    2011-12-01

    We perform a set of high resolution simulations on the impact of the UV-radiation of massive stars on the turbulent interstellar medium with the tree-SPH code iVINE. This parameter study includes different levels and driving scales of the turbulence, different ionizing flux as well as different temperatures and densities of the cold gas. We find a clear correlation between the initial state of the turbulent cloud and the final morphology and physical properties of the structures adjacent to the HII region. From the simulations we are able to derive a criterion for the formation of pillar-like structures and thus the formation of cores and stars. Gravitational collapse occurs regularly on the tips of the structures. We also derive column densities and velocity profiles of our simulations and find these to be in very good agreement with the observations of trunks and cores. In addition, we investigate the further evolution of the pillars once the massive star explodes. This leads to a supernova triggered scenario for the formation of our Solar System.

  3. Supernova Feedback in Galaxy Formation

    NASA Astrophysics Data System (ADS)

    Dubois, Y.; Teyssier, R.

    2008-06-01

    The hierarchical model of galaxy formation is known to suffer from the ``over-cooling'' problem: the high efficiency of radiative cooling results in too much baryonic matter in a condensed phase (namely, cold gas or stars) when compared to observations. A solution proposed by many authors (see Springel & Hernquist 2003; Fujita et al. 2004; Rasera & Teyssier 2005) is feedback due to supernova (SN) driven winds or active galactic nuclei. Modeling SN feedback by direct injection of thermal energy usually turns out to be inefficient in galaxy-scale simulations, due to the quasi-instantaneous radiation of the SN energy. To avoid this effect, we have developed a new method to incorporate SN feedback in cosmological simulations: using temporary test particles, we reproduce explicitly a local Sedov blast wave solution in the gas distribution. We have performed several self-consistent runs of isolated Navarro, Frenk, & White (1996, hereafter NFW) halos with radiative cooling, star formation, SN feedback and metal enrichment using the adaptive mesh refinement code RAMSES (Teyssier 2002). We have explored the influence of SN feedback on the formation and the evolution of galaxies with different masses. We have studied the efficiency of the resulting galactic winds, as a function of the mass of the parent halo.

  4. Outlook: Testing Planet Formation Theories

    NASA Astrophysics Data System (ADS)

    Boss, A. P.

    The discovery of the first planetary companion to a solar-type star by Mayor and Queloz (1995) launched the extrasolar planetary systems era. Observational and theoretical progress in this area has been made at a breathtaking pace since 1995, as evidenced by this workshop. We now have a large and growing sample of extrasolar gas giant planets with which to test our theories of their formation and evolution. The two competing theories for the formation of gas giant planets, core accretion and disk instability, appear to have testable predictions: (i) Core accretion seems to require exceptionally long-lived disks, implying that gas giants should be somewhat rare, while disk instability can occur in even the shortest-lived disk, implying that gas giants should be abundant. The ongoing census of gas giants by the spectroscopic search programs will determine the frequency of gas giants on Jupiter-like orbits within the next decade. (ii) Core accretion takes millions of years to form gas giants, while disk instability forms gaseous protoplanets in thousands of years. Determining the epoch of gas giant planet formation by searching for astrometric wobbles indicative of gas giant companions around young stars with a range of ages (˜ 0.1 Myr to ˜ 10 Myr) should be possible with the Space Interferometry Mission (SIM). (iii) Core accretion would seem to be bolstered by a higher ratio of dust to gas, whereas disk instability occurs equally well for a range of dust opacities. Determining whether a high primordial metallicity is necessary for gas giant planet formation can be accomplished by spectroscopic and astrometric searches for gas giants around metal-poor stars. Eventually, ice giant planets will be detectable as well. If ice giants are found to be much more frequent that gas giants, this may imply that core accretion occurs, but usually fails to form a gas giant. Terrestrial planets will be detected through photometry by Kepler and Eddington, astrometry by SIM, and

  5. Formation mechanisms of metal colloids

    NASA Astrophysics Data System (ADS)

    Halaciuga, Ionel

    Highly dispersed uniform metallic particles are widely used in various areas of technology and medicine and are likely to be incorporated into many other applications in the future. It is commonly accepted that size, shape and composition of the particles represent critical factors in most applications. Thus, understanding the mechanisms of formation of metal particles and the ways to control the physical (e.g. shape, size) and chemical (e.g. composition) properties is of great importance. In the current research, the formation of uniform silver spheres is investigated experimentally. The parameters that influence the formation of silver particles when concentrated iso-ascorbic acid and silver-polyamine complex solutions are rapidly mixed were studied in the absence of dispersants. We found that by varying the nature of the amine, temperature, concentration of reactants, silver/amine molar ratio, and the nature of the silver salt, the size of the resulting silver particles can be varied in a wide range (0.08--1.5 microm). The silver particles were formed by aggregation of nanosize subunits as substantiated by both electron microscopy and X-ray diffraction techniques and by the vivid rapid color changes during the chemical precipitation process. From the practical standpoint, the goal of this research was to prepare well dispersed spherical silver particles having a relatively smooth surface and a diameter of about 1 microm to satisfy the demands of the current electronic materials market. A two stage particle growth model previously developed to explain the narrow size distribution occurring in synthesis of gold spheres was applied to the present experimental system, and the parameters that control the size distribution characteristics were identified. The kinetic parameter required to match the final particle size was found to be in agreement with the one used previously in modeling formation of gold spheres, suggesting that similar kinetics governs the

  6. Formation of the hurricane eye

    NASA Astrophysics Data System (ADS)

    Vigh, Jonathan L.

    This dissertation consists of three distinct studies which investigate aspects of eye formation. The first study reviews eye phenomenon in a variety of vortices ranging from simple vortices to the menagerie of geophysical vortices, emphasizing similarities and differences to the eyes formed in hurricanes. The hurricane eye is found to be a paradoxical structure imposed by conservation of angular momentum and the boundaries of the vortex. A comprehensive definition for hurricane eye formation is proposed and various eye formation mechanisms are summarized. The next study presents a simple theoretical argument to isolate the conditions under which a tropical cyclone can rapidly develop a warm-core thermal structure and subsequently approach a steady state. The theoretical argument is based on the balanced vortex model and, in particular, on the associated transverse circulation equation and the geopotential tendency equation. The transverse circulation and the temperature tendency in a tropical vortex depend not only on the diabatic forcing, but also on the spatial distributions of the static stability, the baroclinity, and the inertial stability. The vortex response to diabatic heating depends critically on whether the heating occurs in the low inertial stability region outside the radius of maximum wind or in the high inertial stability region inside the radius of maximum wind. This result suggests that rapid intensification is favored for storms which have at least some of the eyewall convection inside the radius of maximum wind. The development of an eye partially removes diabatic heating from the high inertial stability region of the storm center, yet rapid intensification may continue if the eyewall heating continues to become more efficient. As the warm core matures and static stability increases over the inner core, conditions there become less favorable for deep upright convection and the storm tends to approach a steady state. The final study characterizes

  7. Hormone interactions during lateral root formation.

    PubMed

    Fukaki, Hidehiro; Tasaka, Masao

    2009-03-01

    Lateral root (LR) formation, the production of new roots from parent roots, is a hormone- and environmentally-regulated developmental process in higher plants. Physiological and genetic studies using Arabidopsis thaliana and other plant species have revealed the roles of several plant hormones in LR formation, particularly the role of auxin in LR initiation and primordium development, resulting in much progress toward understanding the mechanisms of auxin-mediated LR formation. However, hormone interactions during LR formation have been relatively underexamined. Recent studies have shown that the plant hormones, cytokinin and abscisic acid negatively regulate LR formation whereas brassinosteroids positively regulate LR formation. On the other hand, ethylene has positive and negative roles during LR formation. This review summarizes recent findings on hormone-regulated LR formation in higher plants, focusing on auxin as a trigger and on the other hormones in LR formation, and discusses the possible interactions among plant hormones in this developmental process.

  8. Early generation selection for rice fissure resistance proves effective and indicates a fissure resistance gene on chromsome 1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole rice kernels have two to three times more market value than brokens, which means that any reduction in milling yield results in financial losses for both rice producers and millers. One of the leading causes of reduced milling yield is exposure of the rice kernels to severe moisture changes b...

  9. On-Going Galaxy Formation

    NASA Astrophysics Data System (ADS)

    Braine, Jonathan; Duc, P.-A.; Lisenfeld, U.; Charmandaris, V.; Vallejo, O.; Leon, S.; Brinks, E.

    2002-07-01

    We investigate the process of galaxy formation as can be observed in the only currently forming galaxies - the so-called Tidal Dwarf Galaxies, hereafter TDGs - through observations of the molecular gas detected via its CO (Carbon Monoxide) emission. These objects are formed of material torn off of the outer parts of a spiral disk due to tidal forces in a collision between two massive galaxies. Molecular gas is a key element in the galaxy formation process, providing the link between a cloud of gas and a bona fide galaxy. We have detected CO in 8 TDGs (Braine, Lisenfeld, Duc and Leon, 2000: Nature 403, 867; Braine, Duc, Lisenfeld, Charmandaris, Vallejo, Leon and Brinks: 2001, A&A 378, 51), with an overall detection rate of 80%, showing that molecular gas is abundant in TDGs, up to a few 108 M ⊙. The CO emission coincides both spatially and kinematically with the HI emission, indicating that the molecular gas forms from the atomic hydrogen where the HI column density is high. A possible trend of more evolved TDGs having greater molecular gas masses is observed, in accord with the transformation of HI into H2. Although TDGs share many of the properties of small irregulars, their CO luminosity is much greater (factor ˜ 100) than that of standard dwarf galaxies of comparable luminosity. This is most likely a consequence of the higher metallicity (≳sim 1/3 solar) of TDGs which makes CO a good tracer of molecular gas. This allows us to study star formation in environments ordinarily inaccessible due to the extreme difficulty of measuring the molecular gas mass. The star formation efficiency, measured by the CO luminosity per Hα flux, is the same in TDGs and full-sized spirals. CO is likely the best tracer of the dynamics of these objects because some fraction of the HI near the TDGs may be part of the tidal tail and not bound to the TDG. Although uncertainties are large for individual objects, as the geometry is unknown, our sample is now of eight detected objects

  10. A Fossil Group in Formation

    NASA Astrophysics Data System (ADS)

    Miller, Eric D.; Rappaport, Saul A.; McDonald, Michael; Bautz, Mark W.; Grant, Catherine E.; Veilleux, Sylvain

    2016-04-01

    In the current picture of hierarchical structure formation, galaxy groups play a vital role as the seeds from which large assemblies of matter form. Compact groups are also important environments in which to watch the fueling of star formation and AGN activity, as the conditions are ideal for galaxy-galaxy interactions. We have identified a galaxy system that may represent an intermediate or transition stage in group evolution. Shakhbazyan 1 (or SHK 1) is a remarkably compact collection of about ten massive, red-sequence galaxies within a region 100 kpc across. Several of these galaxies show signs of AGN activity, and new, deep optical observations with the Discovery Channel Telescope reveal an extended stellar envelope surrounding the galaxies. This envelope is much more extended than what would be expected from a superposition of normal galaxy envelopes, and it indicates a large amount of intra-group starlight, evidence that the galaxies in SHK 1 are dynamically interacting.We here present new Chandra spectral imaging observations of this unusual system that confirm the presence of an X-ray-emitting diffuse intra-group medium (IGM), with a temperature of 1.5 keV and X-ray luminosity of 1043 erg/s. Assuming hydrostatic equilibrium, the system is about 1/3 as massive as expected from the optical richness. In addition, three of the ten central galaxies exhibit signatures of X-ray AGN. The under-luminous IGM, high density of bright galaxies, and evidence for galaxy-galaxy interaction indicate that this system may be in a transition stage of galaxy merging, similar to that expected in the formation of a fossil group. Alternatively, SHK 1 may consist of multiple poor groups in the final stages of merging along our line of sight. We explore these scenarios and outline paths of future study for this enigmatic system.

  11. Microbial Formation of Manganese Oxides

    PubMed Central

    Greene, Anthony C.; Madgwick, John C.

    1991-01-01

    Microbial manganese oxidation was demonstrated at high Mn2+ concentrations (5 g/liter) in bacterial cultures in the presence of a microalga. The structure of the oxide produced varied depending on the bacterial strain and mode of culture. A nonaxenic, acid-tolerant microalga, a Chlamydomonas sp., was found to mediate formation of manganite (γ-MnOOH). Bacteria isolated from associations with crude cultures of this alga grown in aerated bioreactors formed disordered γ-MnO2 from Mn2+ at concentrations of 5 g/liter over 1 month, yielding 3.3 g of a semipure oxide per liter. All algal-bacterial cultures removed Mn2+ from solution, but only those with the highest removal rates formed an insoluble oxide. While the alga was an essential component of the reaction, a Pseudomonas sp. was found to be primarily responsible for the formation of a manganese precipitate. Medium components—algal biomass and urea—showed optima at 5.7 and 10 g/liters, respectively. The scaled-up culture (50 times) gave a yield of 22.3 g (53 mg/liter/day from a 15-liter culture) of semipure disordered γ-MnO2, identified by X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy, and had a manganese oxide O/Mn ratio of 1.92. The Mn(IV) content in the oxide was low (30.5%) compared with that of mined or chemically formed γ-MnO2 (ca. 50%). The shortfall in the bacterial oxide manganese content was due to biological and inorganic contaminants. FTIR spectroscopy, transmission electron microscopy, and electron diffraction studies have identified manganite as a likely intermediate product in the formation of disordered γ-MnO2. PMID:16348459

  12. Probabilistic Modeling of Rosette Formation

    PubMed Central

    Long, Mian; Chen, Juan; Jiang, Ning; Selvaraj, Periasamy; McEver, Rodger P.; Zhu, Cheng

    2006-01-01

    Rosetting, or forming a cell aggregate between a single target nucleated cell and a number of red blood cells (RBCs), is a simple assay for cell adhesion mediated by specific receptor-ligand interaction. For example, rosette formation between sheep RBC and human lymphocytes has been used to differentiate T cells from B cells. Rosetting assay is commonly used to determine the interaction of Fc γ-receptors (FcγR) expressed on inflammatory cells and IgG coated on RBCs. Despite its wide use in measuring cell adhesion, the biophysical parameters of rosette formation have not been well characterized. Here we developed a probabilistic model to describe the distribution of rosette sizes, which is Poissonian. The average rosette size is predicted to be proportional to the apparent two-dimensional binding affinity of the interacting receptor-ligand pair and their site densities. The model has been supported by experiments of rosettes mediated by four molecular interactions: FcγRIII interacting with IgG, T cell receptor and coreceptor CD8 interacting with antigen peptide presented by major histocompatibility molecule, P-selectin interacting with P-selectin glycoprotein ligand 1 (PSGL-1), and L-selectin interacting with PSGL-1. The latter two are structurally similar and are different from the former two. Fitting the model to data enabled us to evaluate the apparent effective two-dimensional binding affinity of the interacting molecular pairs: 7.19 × 10−5 μm4 for FcγRIII-IgG interaction, 4.66 × 10−3 μm4 for P-selectin-PSGL-1 interaction, and 0.94 × 10−3 μm4 for L-selectin-PSGL-1 interaction. These results elucidate the biophysical mechanism of rosette formation and enable it to become a semiquantitative assay that relates the rosette size to the effective affinity for receptor-ligand binding. PMID:16603493

  13. Structure and formation of microplasmin.

    PubMed Central

    Wu, H L; Shi, G Y; Wohl, R C; Bender, M L

    1987-01-01

    The structure of human microplasmin, prepared from plasmin in alkaline solution, has been studied. Microplasmin consists of two polypeptide chains connected by disulfide bonds. One polypeptide is the B chain of plasmin consisting of 230 amino acids, and the other peptide is the COOH-terminal portion of the A chain of plasmin consisting of 31 amino acid residues. Microplasmin has a molecular weight of 28,635, calculated from its primary sequence. It is slightly more positively charged than plasminogen and is a more hydrophobic molecule. The proposed scheme for the formation of microplasmin involves autolysis at specific peptide bonds and scrambling of especially sensitive disulfide bonds in alkaline solution. PMID:2962191

  14. The formation of interstellar jets

    NASA Technical Reports Server (NTRS)

    Tenorio-Tagle, G.; Canto, J.; Rozyczka, M.

    1988-01-01

    The formation of interstellar jets by convergence of supersonic conical flows and the further dynamical evolution of these jets are investigated theoretically by means of numerical simulations. The results are presented in extensive graphs and characterized in detail. Strong radiative cooling is shown to result in jets with Mach numbers 2.5-29 propagating to lengths 50-100 times their original widths, with condensation of swept-up interstellar matter at Mach 5 or greater. The characteristics of so-called molecular outflows are well reproduced by the simulations of low-Mach-number and quasi-adiabatic jets.

  15. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, Anthony F.

    1999-01-01

    Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area.

  16. Advances in multicellular spheroids formation

    PubMed Central

    Cui, X.; Hartanto, Y.

    2017-01-01

    Three-dimensional multicellular spheroids (MCSs) have a complex architectural structure, dynamic cell–cell/cell–matrix interactions and bio-mimicking in vivo microenvironment. As a fundamental building block for tissue reconstruction, MCSs have emerged as a powerful tool to narrow down the gap between the in vitro and in vivo model. In this review paper, we discussed the structure and biology of MCSs and detailed fabricating methods. Among these methods, the approach in microfluidics with hydrogel support for MCS formation is promising because it allows essential cell–cell/cell–matrix interactions in a confined space. PMID:28202590

  17. Formation Flying and Deformable Instruments

    NASA Astrophysics Data System (ADS)

    Rio, Yvon

    2009-05-01

    Astronomers have always attempted to build very stable instruments. They fight all that can cause mechanical deformation or image motion. This has led to well established technologies (autoguide, active optics, thermal control, tip/tilt correction), as well as observing methods based on the use of controlled motion (scanning, micro scanning, shift and add, chopping and nodding). Formation flying disturbs this practice. It is neither possible to reduce the relative motion to very small amplitudes, nor to control it at will. Some impacts on Simbol-X instrument design, and operation are presented.

  18. Formation Flying and Deformable Instruments

    SciTech Connect

    Rio, Yvon

    2009-05-11

    Astronomers have always attempted to build very stable instruments. They fight all that can cause mechanical deformation or image motion. This has led to well established technologies (autoguide, active optics, thermal control, tip/tilt correction), as well as observing methods based on the use of controlled motion (scanning, micro scanning, shift and add, chopping and nodding). Formation flying disturbs this practice. It is neither possible to reduce the relative motion to very small amplitudes, nor to control it at will. Some impacts on Simbol-X instrument design, and operation are presented.

  19. The formation of sunlike stars.

    PubMed

    Lada, C J; Shu, F H

    1990-05-04

    Understanding how stars like the sun formed constitutes one of the principal challenges confronting modern astrophysics. In recent years, advances in observational technology, particularly at infrared and millimeter wavelengths, have produced an avalanche of critical data and unexpected discoveries about the process of star formation, which is blocked from external view at optical and shorter wavelengths by an obscuring blanket of interstellar dust. Fueled by this new knowledge, a comprehensive empirical picture of stellar genesis is beginning to emerge, laying the foundations for a coherent theory of the birth of sunlike stars.

  20. Inside-Out Planet Formation

    NASA Astrophysics Data System (ADS)

    Tan, Jonathan

    The objective of this proposal is to investigate several aspects of the Inside-Out Planet Formation model, recently proposed by Chatterjee & Tan (2014). This model involves sequential formation of planets from pebble (i.e., ~centimeter to ~meter-sized particle)-rich rings in the inner regions of protoplanetary disks. Pebbles, formed from dust coagulation, migrate to the inner disk because of gas drag and collect at a local pressure maximum associated with the inner boundary of the dead zone with a magneto-rotational instability (MRI)-active region. Once the first planet forms from the pebble ring, it may either grow to open a gap leading to dead zone retreat or migrate inwards into the MRI-active region. In either case, a new pebble ring starts to form exterior to the planet, and the process repeats. This model may help explain the systems of tightly packed inner planets (STIPs) recently discovered by Kepler. We propose to: (1) Calculate the radial structure of the inner accretion disk to estimate locations of the dead zone inner boundary (DZIB), most likely set by thermal ionization of alkali metals; (2) Construct a model of pebble formation and radial drift to estimate pebble supply rates to the inner disk, including analysis of MHD simulations of the MRI to assess the effect of pressure fluctuations due to turbulence; (3) Simulate the interactions of protoplanets that are expected to form via gravitational instability from the pebble ring to examine if a single dominant planet can form by collisions and/or continued pebble accretion, and the timescale for this process; (4) Simulate planet-disk interactions near the DZIB using the FARGO code to study gap-opening and migration of planets; (5) Study planetary system synthesis via Inside-Out Planet Formation via a series of connected FARGO simulations; (6) Compare model results, such as planet masses and orbital properties, with observed exoplanet systems. This work has the potential to help provide a theoretical

  1. Petrophysical evaluation of subterranean formations

    SciTech Connect

    Klein, James D; Schoderbek, David A; Mailloux, Jason M

    2013-05-28

    Methods and systems are provided for evaluating petrophysical properties of subterranean formations and comprehensively evaluating hydrate presence through a combination of computer-implemented log modeling and analysis. Certain embodiments include the steps of running a number of logging tools in a wellbore to obtain a variety of wellbore data and logs, and evaluating and modeling the log data to ascertain various petrophysical properties. Examples of suitable logging techniques that may be used in combination with the present invention include, but are not limited to, sonic logs, electrical resistivity logs, gamma ray logs, neutron porosity logs, density logs, NRM logs, or any combination or subset thereof.

  2. Comet Formation in Collapsing Pebble Clouds: Pebble Formation

    NASA Astrophysics Data System (ADS)

    Lorek, Sebastian; Lacerda, Pedro; Blum, Jürgen

    2016-10-01

    The formation of comets by gradual growth from (sub-)micron sized ice and dust monomers to km-sized bodies suffers from growth barriers (bouncing, fragmentation, drift). Growth stalls at sizes between mm and m, rendering it considerably difficult to form km-sized objects. However, the streaming instability and subsequent gravitational collapse of clouds of pebbles (particle agglomerates) provide an alternative. The pebbles require Stokes numbers between 0.01 and 3, which corresponds to sizes between mm and dm, unless the pebbles are very porous. Furthermore, the local solid/gas density ratio must be near unity and the local total mass in solids must be >2-3x higher than the minimum mass solar nebula value (1% of gas mass). The gravitational collapse of the pebble clouds then bypasses the growth barriers, forming km-sized bodies directly. The observed bulk properties of comets, e.g. porosity near 80%, are consistent with this scenario. Okuzumi et al. (2012) showed that including porosity comets can form directly via coagulation from sub-micron monomers. However, this relies on using 0.1 micron monomers and pure sticking collisions. Krijt et al. (2015) included erosion and found that highly porous pebbles around 109 g in mass can form and might trigger the streaming instability. Drazkowska & Dullemond (2014) showed that compact coagulation can lead to triggering the streaming instability. All those studies include only ice and a simplified collision model. However, a large fraction of a comet's mass is dust. Here, we develop a pebble formation model that includes sticking, bouncing, mass transfer/erosion, and fragmentation, as well as porosity. To take dust and ice into account, we extended the collision model for the treatment of mixed pebbles by linearly interpolating the threshold velocities and compression curves between the cases of pure dust and pure ice based on the fractional abundance of dust monomers. Our simulations show that pebble formation with the full

  3. Choosing to write the paper format thesis.

    PubMed

    Morris, H M; Tipples, G

    1998-04-01

    Graduate students today may be faced with the option of writing either a traditional format thesis or a paper format thesis. In contrast to the traditional format in which the text body consists of four or five chapters, the body of the paper format thesis can be comprised of an introductory chapter, two or more papers written as publishable manuscripts, and a conclusion. In this article, an overview of the paper format thesis is presented and contrasted with the traditional format thesis. The description of the paper format thesis is followed by its advantages and disadvantages for writers and readers. It is by weighing all possible pros and cons, as well as considering one's individual situation, that the graduate student will be able to decide which format of thesis to write.

  4. 40 CFR 1502.10 - Recommended format.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... § 1502.10 Recommended format. Agencies shall use a format for environmental impact statements which will encourage good analysis and clear presentation of the alternatives including the proposed action....

  5. SAR polar format implementation with MATLAB.

    SciTech Connect

    Martin, Grant D.; Doerry, Armin Walter

    2005-11-01

    Traditional polar format image formation for Synthetic Aperture Radar (SAR) requires a large amount of processing power and memory in order to accomplish in real-time. These requirements can thus eliminate the possible usage of interpreted language environments such as MATLAB. However, with trapezoidal aperture phase history collection and changes to the traditional polar format algorithm, certain optimizations make MATLAB a possible tool for image formation. Thus, this document's purpose is two-fold. The first outlines a change to the existing Polar Format MATLAB implementation utilizing the Chirp Z-Transform that improves performance and memory usage achieving near realtime results for smaller apertures. The second is the addition of two new possible image formation options that perform a more traditional interpolation style image formation. These options allow the continued exploration of possible interpolation methods for image formation and some preliminary results comparing image quality are given.

  6. 40 CFR 761.45 - Marking formats.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... POLYCHLORINATED BIPHENYLS (PCBs) MANUFACTURING, PROCESSING, DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Marking of PCBs and PCB Items § 761.45 Marking formats. The following formats shall be used for marking:...

  7. XML Format for SESAME and LEOS

    SciTech Connect

    Durrenberger, J K; Neely, J R; Sterne, P A

    2009-04-29

    The objective of this document is to describe the XML format used by LLNL and LANL to represent the equation-of-state and related material information in the LEOS and SESAME data libraries. The primary purpose of this document is to describe a specific XML format for representing EOS data that is tailored to the nature of the underlying data and is amenable to conversion to both legacy SESAME and LEOS binary formats. The secondary purpose is to describe an XML format that lends itself to a 'natural' representation in a binary file format of the SESAME, pdb or hdf5 form so that this format and related tools can be used for the rapid and efficient development and implementation of prototype data structures. This document describes the XML format only. A working knowledge of LEOS and SESAME formats is assumed.

  8. Formation of the terrestrial planets from planetesimals

    NASA Technical Reports Server (NTRS)

    Wetherill, George W.

    1991-01-01

    Formation of the terrestrial planets from planetesimals is discussed. The following subject areas are covered: (1) formation of the original planetesimals; (2) growth of planetesimals into planetary embryos; and (3) growth of runaway planetary embryos into terrestrial planets.

  9. Formation number for vortex dipoles

    NASA Astrophysics Data System (ADS)

    Sadri, Vahid; Krueger, Paul S.

    2016-11-01

    This investigation considers the axisymmetric formation of two opposite sign concentric vortex rings from jet ejection between concentric cylinders. This arrangement is similar to planar flow in that the vortex rings will travel together when the gap between the cylinders is small, similar to a vortex dipole, but it has the advantage that the vortex motion is less constrained than the planar case (vortex stretching and vortex line curvature is allowed). The flow was simulated numerically at a jet Reynolds number of 1,000 (based on ΔR and the jet velocity), jet pulse length-to-gap ratio (L / ΔR) in the range 10-20, and gap-to-outer radius ratio (ΔR /Ro) in the range 0.01-0.1. Small gap ratios were chosen for comparison with 2D results. In contrast with 2D results, the closely paired vortices in this study exhibited pinch-off from the generating flow and finite formation numbers. The more complex flow evolution afforded by the axisymmetric model and its influence on the pinch-off process will be discussed. This material is based on work supported by the National Science Foundation under Grant No. 1133876 and SMU. This supports are gratefully acknowledged.

  10. Formation mechanism of calcium hexaluminate

    NASA Astrophysics Data System (ADS)

    Chen, Jun-hong; Chen, Hai-yang; Yan, Ming-wei; Cao, Zheng; Mi, Wen-jun

    2016-10-01

    To investigate the formation mechanism of calcium hexaluminate (CaAl12O19, CA6), the analytically pure alumina and calcia used as raw materials were mixed in CaO/Al2O3 ratio of 12.57:137.43 by mass. The raw materials were ball-milled and shaped into green specimens, and fired at 1300-1600°C. Then, the phase composition and microstructure evolution of the fired specimen were studied, and a first principle calculation was performed. The results show that in the reaction system of CaO and Al2O3, a small amount of CA6 forms at 1300°C, and greater amounts are formed at 1400°C and higher temperatures. The reaction is as follows: CaO·2Al2O3 (CA2) + 4Al2O3 → CA6. The diffusions of Ca2+ in CA2 towards Al2O3 and Al3+ in Al2O3 towards CA2 change the structures in different degrees of difficulty. Compared with the difficulty of structural change and the corresponding lattice energy change, it is deduced that the main formation mechanism is the diffusion of Ca2+ in CA2 towards Al2O3.

  11. Pattern formations and optimal packing.

    PubMed

    Mityushev, Vladimir

    2016-04-01

    Patterns of different symmetries may arise after solution to reaction-diffusion equations. Hexagonal arrays, layers and their perturbations are observed in different models after numerical solution to the corresponding initial-boundary value problems. We demonstrate an intimate connection between pattern formations and optimal random packing on the plane. The main study is based on the following two points. First, the diffusive flux in reaction-diffusion systems is approximated by piecewise linear functions in the framework of structural approximations. This leads to a discrete network approximation of the considered continuous problem. Second, the discrete energy minimization yields optimal random packing of the domains (disks) in the representative cell. Therefore, the general problem of pattern formations based on the reaction-diffusion equations is reduced to the geometric problem of random packing. It is demonstrated that all random packings can be divided onto classes associated with classes of isomorphic graphs obtained from the Delaunay triangulation. The unique optimal solution is constructed in each class of the random packings. If the number of disks per representative cell is finite, the number of classes of isomorphic graphs, hence, the number of optimal packings is also finite.

  12. Possible mechanisms of macrolayer formation

    SciTech Connect

    Sadasivan, P.; Chappidi, P.R.; Unal, C.; Nelson, R.A.

    1992-05-01

    The high heat flux nucleate boiling region, also called the vapor mushroom region, has been shown to have a thin liquid layer on the heater surface under the large mushroom-shaped vapor bubbles that grow from the heater surface. The name given to this liquid layer is the macrolayer to differentiate it from the microlayer that exists under the discrete bubbles found at lower heat fluxes in the nucleate boiling region. Typical thicknesses of this macrolayer range from 50 to 500 {mu}m for water on a flat horizontal boiling surface and depend upon the heat flux. Thus, the macrolayer is thicker than the wedge-shaped microlayers, found under discrete bubbles, which range in thickness from 1 to 10 {mu}m. Although the mechanism of microlayer formation and its evaporation is conceptually simple that of the macrolayer is still not understood. This paper critically compares the potential mechanisms proposed for macrolayer formation. These mechanisms include the Helmholtz instability applied to the vapor stem above active nucleation sites, liquid trapped by lateral coalescence of discrete bubbles that initially form during the mushroom bubble`s waiting period, and the limitation of liquid resupply at mushroom departure as a result of vapor flow from the active nucleation sites.

  13. Possible mechanisms of macrolayer formation

    SciTech Connect

    Sadasivan, P.; Chappidi, P.R.; Unal, C.; Nelson, R.A.

    1992-01-01

    The high heat flux nucleate boiling region, also called the vapor mushroom region, has been shown to have a thin liquid layer on the heater surface under the large mushroom-shaped vapor bubbles that grow from the heater surface. The name given to this liquid layer is the macrolayer to differentiate it from the microlayer that exists under the discrete bubbles found at lower heat fluxes in the nucleate boiling region. Typical thicknesses of this macrolayer range from 50 to 500 {mu}m for water on a flat horizontal boiling surface and depend upon the heat flux. Thus, the macrolayer is thicker than the wedge-shaped microlayers, found under discrete bubbles, which range in thickness from 1 to 10 {mu}m. Although the mechanism of microlayer formation and its evaporation is conceptually simple that of the macrolayer is still not understood. This paper critically compares the potential mechanisms proposed for macrolayer formation. These mechanisms include the Helmholtz instability applied to the vapor stem above active nucleation sites, liquid trapped by lateral coalescence of discrete bubbles that initially form during the mushroom bubble's waiting period, and the limitation of liquid resupply at mushroom departure as a result of vapor flow from the active nucleation sites.

  14. Coring in deep hardrock formations

    SciTech Connect

    Drumheller, D.S.

    1988-08-01

    The United States Department of Energy is involved in a variety of scientific and engineering feasibility studies requiring extensive drilling in hard crystalline rock. In many cases well depths extend from 6000 to 20,000 feet in high-temperature, granitic formations. Examples of such projects are the Hot Dry Rock well system at Fenton Hill, New Mexico and the planned exploratory magma well near Mammoth Lakes, California. In addition to these programs, there is also continuing interest in supporting programs to reduce drilling costs associated with the production of geothermal energy from underground sources such as the Geysers area near San Francisco, California. The overall progression in these efforts is to drill deeper holes in higher temperature, harder formations. In conjunction with this trend is a desire to improve the capability to recover geological information. Spot coring and continuous coring are important elements in this effort. It is the purpose of this report to examine the current methods used to obtain core from deep wells and to suggest projects which will improve existing capabilities. 28 refs., 8 figs., 2 tabs.

  15. Autophagosome formation in mammalian cells.

    PubMed

    Burman, Chloe; Ktistakis, Nicholas T

    2010-12-01

    Autophagy is a fundamental intracellular trafficking pathway conserved from yeast to mammals. It is generally thought to play a pro-survival role, and it can be up regulated in response to both external and intracellular factors, including amino acid starvation, growth factor withdrawal, low cellular energy levels, endoplasmic reticulum (ER) stress, hypoxia, oxidative stress, pathogen infection, and organelle damage. During autophagy initiation a portion of the cytosol is surrounded by a flat membrane sheet known as the isolation membrane or phagophore. The isolation membrane then elongates and seals itself to form an autophagosome. The autophagosome fuses with normal endocytic traffic to mature into a late autophagosome, before fusing with lysosomes. The molecular machinery that enables formation of an autophagosome in response to the various autophagy stimuli is almost completely identified in yeast and-thanks to the observed conservation-is also being rapidly elucidated in higher eukaryotes including mammals. What are less clear and currently under intense investigation are the mechanism by which these various autophagy components co-ordinate in order to generate autophagosomes. In this review, we will discuss briefly the fundamental importance of autophagy in various pathophysiological states and we will then review in detail the various players in early autophagy. Our main thesis will be that a conserved group of heteromeric protein complexes and a relatively simple signalling lipid are responsible for the formation of autophagosomes in mammalian cells.

  16. Beaver assisted river valley formation

    USGS Publications Warehouse

    Westbrook, C.J.; Cooper, D.J.; Baker, B.W.

    2011-01-01

    We examined how beaver dams affect key ecosystem processes, including pattern and process of sediment deposition, the composition and spatial pattern of vegetation, and nutrient loading and processing. We provide new evidence for the formation of heterogeneous beaver meadows on riverine system floodplains and terraces where dynamic flows are capable of breaching in-channel beaver dams. Our data show a 1.7-m high beaver dam triggered overbank flooding that drowned vegetation in areas deeply flooded, deposited nutrient-rich sediment in a spatially heterogeneous pattern on the floodplain and terrace, and scoured soils in other areas. The site quickly de-watered following the dam breach by high stream flows, protecting the deposited sediment from future re-mobilization by overbank floods. Bare sediment either exposed by scouring or deposited by the beaver flood was quickly colonized by a spatially heterogeneous plant community, forming a beaver meadow. Many willow and some aspen seedlings established in the more heavily disturbed areas, suggesting the site may succeed to a willow carr plant community suitable for future beaver re-occupation. We expand existing theory beyond the beaver pond to include terraces within valleys. This more fully explains how beavers can help drive the formation of alluvial valleys and their complex vegetation patterns as was first postulated by Ruedemann and Schoonmaker in 1938. ?? 2010 John Wiley & Sons, Ltd.

  17. Computer simulation of bubble formation.

    SciTech Connect

    Insepov, Z.; Bazhirov, T.; Norman, G.; Stegailov, V.; Mathematics and Computer Science; Institute for High Energy Densities of Joint Institute for High Temperatures of RAS

    2007-01-01

    Properties of liquid metals (Li, Pb, Na) containing nanoscale cavities were studied by atomistic Molecular Dynamics (MD). Two atomistic models of cavity simulation were developed that cover a wide area in the phase diagram with negative pressure. In the first model, the thermodynamics of cavity formation, stability and the dynamics of cavity evolution in bulk liquid metals have been studied. Radial densities, pressures, surface tensions, and work functions of nano-scale cavities of various radii were calculated for liquid Li, Na, and Pb at various temperatures and densities, and at small negative pressures near the liquid-gas spinodal, and the work functions for cavity formation in liquid Li were calculated and compared with the available experimental data. The cavitation rate can further be obtained by using the classical nucleation theory (CNT). The second model is based on the stability study and on the kinetics of cavitation of the stretched liquid metals. A MD method was used to simulate cavitation in a metastable Pb and Li melts and determine the stability limits. States at temperatures below critical (T < 0.5Tc) and large negative pressures were considered. The kinetic boundary of liquid phase stability was shown to be different from the spinodal. The kinetics and dynamics of cavitation were studied. The pressure dependences of cavitation frequencies were obtained for several temperatures. The results of MD calculations were compared with estimates based on classical nucleation theory.

  18. Enamel formation and amelogenesis imperfecta.

    PubMed

    Hu, Jan C-C; Chun, Yong-Hee P; Al Hazzazzi, Turki; Simmer, James P

    2007-01-01

    Dental enamel is the epithelial-derived hard tissue covering the crowns of teeth. It is the most highly mineralized and hardest tissue in the body. Dental enamel is acellular and has no physiological means of repair outside of the protective and remineralization potential provided by saliva. Enamel is comprised of highly organized hydroxyapatite crystals that form in a defined extracellular space, the contents of which are supplied and regulated by ameloblasts. The entire process is under genetic instruction. The genetic control of amelogenesis is poorly understood, but requires the activities of multiple components that are uniquely important for dental enamel formation. Amelogenesis imperfecta (AI) is a collective designation for the variety of inherited conditions displaying isolated enamel malformations, but the designation is also used to indicate the presence of an enamel phenotype in syndromes. Recently, genetic studies have demonstrated the importance of genes encoding enamel matrix proteins in the etiology of isolated AI. Here we review the essential elements of dental enamel formation and the results of genetic analyses that have identified disease-causing mutations in genes encoding enamel matrix proteins. In addition, we provide a fresh perspective on the roles matrix proteins play in catalyzing the biomineralization of dental enamel.

  19. Consensus formation on adaptive networks

    NASA Astrophysics Data System (ADS)

    Kozma, Balazs; Barrat, Alain

    2008-01-01

    The structure of a network can significantly influence the properties of the dynamical processes that take place on them. While many studies have been paid to this influence, much less attention has been devoted to the interplay and feedback mechanisms between dynamical processes and network topology on adaptive networks. Adaptive rewiring of links can happen in real life systems such as acquaintance networks, where people are more likely to maintain a social connection if their views and values are similar. In our study, we consider different variants of a model for consensus formation. Our investigations reveal that the adaptation of the network topology fosters cluster formation by enhancing communication between agents of similar opinion, although it also promotes the division of these clusters. The temporal behavior is also strongly affected by adaptivity: while, on static networks, it is influenced by percolation properties, on adaptive networks, both the early and late time evolutions of the system are determined by the rewiring process. The investigation of a variant of the model reveals that the scenarios of transitions between consensus and polarized states are more robust on adaptive networks.

  20. Vascular pattern formation in plants.

    PubMed

    Scarpella, Enrico; Helariutta, Ykä

    2010-01-01

    Reticulate tissue systems exist in most multicellular organisms, and the principles underlying the formation of cellular networks have fascinated philosophers, mathematicians, and biologists for centuries. In particular, the beautiful and varied arrangements of vascular tissues in plants have intrigued mankind since antiquity, yet the organizing signals have remained elusive. Plant vascular tissues form systems of interconnected cell files throughout the plant body. Vascular cells are aligned with one another along continuous lines, and vascular tissues differentiate at reproducible positions within organ environments. However, neither the precise path of vascular differentiation nor the exact geometry of vascular networks is fixed or immutable. Several recent advances converge to reconcile the seemingly conflicting predictability and plasticity of vascular tissue patterns. A control mechanism in which an apical-basal flow of signal establishes a basic coordinate system for body axis formation and vascular strand differentiation, and in which a superimposed level of radial organizing cues elaborates cell patterns, would generate a reproducible tissue configuration in the context of an underlying robust, self-organizing structure, and account for the simultaneous regularity and flexibility of vascular tissue patterns.