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Sample records for fragments stabs final

  1. Ultraselective Sorbents. Task 2: Molecularly Imprinted Polymers (MIPs)/Stabilized Antibody Fragments (STABs). Final Report FY 2004

    SciTech Connect

    Harvey, Scott D.

    2004-09-01

    This report describes the preparation and application of molecularly imprinted polymers (MIPs) for the highly selective analysis of target signature compounds. The overall goal of this project task is to exploit the high selectivity of MIPs to generate a pure and enriched fraction of target analyte from environmental samples, either during the sampling stage or immediately thereafter. Due to the high purity of analyte fraction obtained, simplified field portable instrumentation that is capable of high performance trace analysis can be constructed. Major sections contained in this FY 2004 Final Report describe: (1) the synthesis and evaluation of MIPs specific toward explosives, (2) the design, construction, and performance of a novel instrument for the trace aqueous analysis of G-series nerve agent hydrolysis compounds, and (3) interfacing MIP separations with ion mobility spectrometric detection.

  2. Environmentally Benign Stab Detonators

    DTIC Science & Technology

    2006-07-11

    a mixture of lead azide, lead styphnate , barium nitrate, antimony sulfides, and tetracene) mJ millijoule (10–3 J) FINAL REPORT PP...initiating mix (NOL-130) and transfer charge of current stab detonators contain hazardous materials such as lead azide, lead styphnate , and barium nitrate...tetracene) and heavy metal constituents (e.g., lead styphnate , lead azide, barium nitrate, and antimony sulfides) present in the NOL-130 initiating

  3. Back stab

    PubMed Central

    Banerjee, Susitna; Baerlocher, Mark Otto; Asch, Murray R.

    2007-01-01

    OBJECTIVE To review the evidence supporting use of percutaneous vertebroplasty for relief of pain and mechanical stability in patients with vertebral compression fractures unrelieved by conventional measures. QUALITY OF EVIDENCE Ovid MEDLINE was searched from January 1966 to December2006 for all English-language papers on vertebroplasty. The quality of evidence in these papers was graded according to the 4-point classification system of evidence-based medicine. Level II evidence currently supports use of vertebroplasty. MAIN MESSAGE Vertebroplasty alleviates pain from vertebral compression fractures that result from osteoporosis, hemangiomas, malignancies, and vertebral osteonecrosis. Vertebroplasty has provided substantial pain relief in 60% to 100% of patients; has decreasedanalgesic use in 34% to 91% of patients; and has improved physical mobility in 29% to 100% of patients. Contraindications to vertebroplasty include asymptomatic compression fractures of the vertebral body, vertebra plana, retropulsed bone fragments or tumours, active infection, uncorrectable coagulopathy, allergy to the bone cement or opacification agent, severe cardiopulmonary disease, pregnancy, and pre-existing radiculopathy. The short-term complication rate was found to be 0.5% to 54%. Rare but serious complications include compression of the spinal cord or nerve root, infection, cement embolization causing pulmonary infarct and clinical symptoms, paradoxical embolization of the cerebral artery, and severe hematomas. CONCLUSION Vertebroplasty is a safe and effective treatment for vertebral fractures that cannot be treated using conservative measures. PMID:17872813

  4. Stab water supply system

    SciTech Connect

    Hammett, D.S.

    1983-02-08

    Apparatus and method for fire suppression on offshore oil platforms including a stab receptacle on an outer surface of a platform connected to a fluid distribution system within the platform for distributing fire suppressing fluid to selected locations, a stab carrying a fluid conduit from a self-propelled service vessel, with the stab being in turn supported on a boom extending from the service vessel, a pumping system on the service vessel for supplying fire suppressing fluid through the conduit to the stab and thereby to the preselected locations. The service vessel is preferably a semi-submersible and includes a system for dynamic positioning of the vessel such as side thrusters in addition to a main propulsion unit.

  5. Primary stabbing headache.

    PubMed

    Pareja, Juan A; Sjaastad, Ottar

    2010-01-01

    Primary stabbing headache is characterized by transient, cephalic ultrashort stabs of pain. It is a frequent complaint with a prevalence of 35.2%, a female preponderance, and a mean age of onset of 28 years (Vågå study). Attacks are generally characterized by moderate to severe, jabbing or stabbing pain, lasting from a fraction of a second to 3s. Attack frequency is generally low, with one or a few attacks per day. The paroxysms generally occur spontaneously, during daytime. Most patients exhibit a sporadic pattern, with an erratic, unpredictable alternation between symptomatic and non-symptomatic periods. Paroxysms are almost invariably unilateral. Temporal and fronto-ocular areas are most frequently affected. Attacks tend to move from one area to another, in either the same or the opposite hemicranium. Jabs may be accompanied by a shock-like feeling and even by head movement - "jolts" -or vocalization. On rare occasions, conjunctival hemorrhage and monocular vision loss have been described as associated features. Primary stabbing headache may concur, synchronously or independently, with other primary headaches. In contrast to what is the case in adults, in childhood it is not usually associated with other headaches. Treatment is rarely necessary. Indomethacin, 75-150 mg daily, may seem to be of some avail. Celecoxib, nifedipine, melatonin, and gabapentin have been reported to be effective in isolated cases and small series of patients. The drug studies need corroboration.

  6. Environmentally Benign Stab Detonators

    SciTech Connect

    Gash, A

    2005-12-21

    Many energetic systems can be activated via mechanical means. Percussion primers in small caliber ammunition and stab detonators used in medium caliber ammunition are just two examples. Current medium caliber (20-60mm) munitions are detonated through the use of impact sensitive stab detonators. Stab detonators are very sensitive and must be small, as to meet weight and size limitations. A mix of energetic powders, sensitive to mechanical stimulus, is typically used to ignite such devices. Stab detonators are mechanically activated by forcing a firing pin through the closure disc of the device and into the stab initiating mix. Rapid heating caused by mechanically driven compression and friction of the mixture results in its ignition. The rapid decomposition of these materials generates a pressure/temperature pulse that is sufficient to initiate a transfer charge, which has enough output energy to detonate the main charge. This general type of ignition mix is used in a large variety of primers, igniters, and detonators.[1] Common primer mixes, such as NOL-130, are made up of lead styphnate (basic) 40%, lead azide (dextrinated) 20%, barium nitrate 20%, antimony sulfide 15%, and tetrazene 5%.[1] These materials pose acute and chronic toxicity hazards during mixing of the composition and later in the item life cycle after the item has been field functioned. There is an established need to replace these mixes on toxicity, health, and environmental hazard grounds. This effort attempts to demonstrate that environmentally acceptable energetic solgel coated flash metal multilayer nanocomposites can be used to replace current impact initiated devices (IIDs), which have hazardous and toxic components. Successful completion of this project will result in IIDs that include innocuous compounds, have sufficient output energy for initiation, meet current military specifications, are small, cost competitive, and perform as well as or better than current devices. We expect flash

  7. Primary and secondary stabbing headache.

    PubMed

    Robbins, Matthew S; Evans, Randolph W

    2015-04-01

    Eight out of the 33 cases of primary stabbing headache seen in a general neurology clinic (40% have headache as their chief complaint) in the last 3.5 years are presented. The epidemiology, association with other primary headache disorders, secondary associations, testing, and treatment of primary stabbing headache are reviewed.

  8. Biomechanics of knife stab attacks.

    PubMed

    Chadwick, E K; Nicol, A C; Lane, J V; Gray, T G

    1999-10-25

    Equipment, materials and methods for the measurement of the biomechanical parameters governing knife stab attacks have been developed and data have been presented that are relevant to the improvement of standards for the testing of stab-resistant materials. A six-camera Vicon motion analysis system was used to measure velocity, and derive energy and momentum during the approach phase of the attack and a specially developed force-measuring knife was used to measure three-dimensional forces and torque during the impact phase. The body segments associated with the knife were modelled as a series of rigid segments: trunk, upper arm, forearm and hand. The velocities of these segments, together with knowledge of the mass distribution from biomechanical tables, allowed the calculation of the individual segment energy and momentum values. The instrumented knife measured four components of load: axial force (along the length of the blade), cutting force (parallel to the breadth of the blade), lateral force (across the blade) and torque (twisting action) using foil strain gauges. Twenty volunteers were asked to stab a target with near maximal effort. Three styles of stab were used: a short thrust forward, a horizontal style sweep around the body and an overhand stab. These styles were chosen based on reported incidents, providing more realistic data than had previously existed. The 95th percentile values for axial force and energy were 1885 N and 69 J, respectively. The ability of current test methods to reproduce the mechanical parameters measured in human stab attacks has been assessed. It was found that current test methods could reproduce the range of energy and force values measured in the human stab attacks, although the simulation was not accurate in some respects. Non-axial force and torque values were also found to be significant in the human tests, but these are not reproduced in the standard mechanical tests.

  9. [Stab wounds in emergency department].

    PubMed

    Bège, T; Berdah, S V; Brunet, C

    2013-12-01

    Stab wounds represent the most common cause of penetrating wounds, occurring mainly in case of aggression or suicide attempt. Clinical severity depends on the superficial or penetrating aspect of the wound, its location and damaged organs. Medical management must be known because the vital risk is involved in penetrating wounds. Hemodynamically unstable patients should be operated without delay after performing a chest X-ray and ultrasound Focus assisted sonography for trauma (FAST) to guide the surgery. In the stable patients, the general clinical examination, exploration of the wound and medical imaging detect injuries requiring surgical management. Stab penetrating wounds require close and rapid collaboration between medical teams, tailored to the institution's resources.

  10. Environmentally Benign Stab Detonators

    SciTech Connect

    Gash, A E

    2006-07-07

    The coupling of energetic metallic multilayers (a.k.a. flash metal) with energetic sol-gel synthesis and processing is an entirely new approach to forming energetic devices for several DoD and DOE needs. They are also practical and commercially viable manufacturing techniques. Improved occupational safety and health, performance, reliability, reproducibility, and environmentally acceptable processing can be achieved using these methodologies and materials. The development and fielding of this technology will enhance mission readiness and reduce the costs, environmental risks and the necessity of resolving environmental concerns related to maintaining military readiness while simultaneously enhancing safety and health. Without sacrificing current performance, we will formulate new impact initiated device (IID) compositions to replace materials from the current composition that pose significant environmental, health, and safety problems associated with functions such as synthesis, material receipt, storage, handling, processing into the composition, reaction products from testing, and safe disposal. To do this, we will advance the use of nanocomposite preparation via the use of multilayer flash metal and sol-gel technologies and apply it to new small IIDs. This work will also serve to demonstrate that these technologies and resultant materials are relevant and practical to a variety of energetic needs of DoD and DOE. The goal will be to produce an IID whose composition is acceptable by OSHA, EPA, the Clean Air Act, Clean Water Act, Resource Recovery Act, etc. standards, without sacrificing current performance. The development of environmentally benign stab detonators and igniters will result in the removal of hazardous and toxic components associated with their manufacturing, handling, and use. This will lead to improved worker safety during manufacturing as well as reduced exposure of Service personnel during their storage and or use in operations. The

  11. Analytical assessment of woven fabrics under vertical stabbing - The role of protective clothing.

    PubMed

    Hejazi, Sayyed Mahdi; Kadivar, Nastaran; Sajjadi, Ali

    2016-02-01

    Knives are being used more commonly in street fights and muggings. Therefore, this work presents an analytical model for woven fabrics under vertical stabbing loads. The model is based on energy method and the fabric is assumed to be unidirectional comprised of N layers. Thus, the ultimate stab resistance of fabric was determined based on structural parameters of fabric and geometrical characteristics of blade. Moreover, protective clothing is nowadays considered as a strategic branch in technical textile industry. The main idea of the present work is improving the stab resistance of woven textiles by using metal coating method. In the final, a series of vertical stabbing tests were conducted on cotton, polyester and polyamide fabrics. Consequently, it was found that the model predicts with a good accuracy the ultimate stab resistance of the sample fabrics.

  12. Stab Sensitivity of Energetic Nanolaminates

    SciTech Connect

    Gash, A; Barbee, T; Cervantes, O

    2006-05-22

    This work details the stab ignition, small-scale safety, and energy release characteristics of bimetallic Al/Ni(V) and Al/Monel energetic nanolaminate freestanding thin films. The influence of the engineered nanostructural features of the energetic multilayers is correlated with both stab initiation and small-scale energetic materials testing results. Structural parameters of the energetic thin films found to be important include the bi-layer period, total thickness of the film, and presence or absence of aluminum coating layers. In general the most sensitive nanolaminates were those that were relatively thick, possessed fine bi-layer periods, and were not coated. Energetic nanolaminates were tested for their stab sensitivity as freestanding continuous parts and as coarse powders. The stab sensitivity of mock M55 detonators loaded with energetic nanolaminate was found to depend strongly upon both the particle size of the material and the configuration of nanolaminate material, in the detonator cup. In these instances stab ignition was observed with input energies as low as 5 mJ for a coarse powder with an average particle dimension of 400 {micro}m. Selected experiments indicate that the reacting nanolaminate can be used to ignite other energetic materials such as sol-gel nanostructured thermite, and conventional thermite that was either coated onto the multilayer substrate or pressed on it. These results demonstrate that energetic nanolaminates can be tuned to have precise and controlled ignition thresholds and can initiate other energetic materials and therefore are viable candidates as lead-free impact initiated igniters or detonators.

  13. Improved Barriers to Turbine Engine Fragments: Final Annual Report

    DTIC Science & Technology

    2002-06-01

    failure behavior in the vicinity of a pegged hole. A series of these fabric corner failure tests in both Zylon and Kevlar fabrics determined that...barrier) upon the ballistic efficiency of the barrier. In some cases, Keviar could be as effective as (or more effective than) Zylon , due to the larger...fraction of impact energy consumed in producing comer tearing. A considerable database of large-scale fragment impact tests into Zylon and Kevlar fabric

  14. FY04&05 LDRD Final Report Fission Fragment Sputtering

    SciTech Connect

    Ebbinghaus, B; Trelenberg, T; Meier, T; Felter, T; Sturgeon, J; Kuboda, A; Wolfer, B

    2006-02-22

    Fission fragments born within the first 7 {micro}m of the surface of U metal can eject a thousand or more atoms per fission event. Existing data in the literature show that the sputtering yield ranges from 10 to 10,000 atoms per fission event near the surface, but nothing definitive is known about the energy of the sputtered clusters. Experimental packages were constructed allowing the neutron irradiation of natural uranium foils to investigate the amount of material removed per fission event and the kinetic energy distribution of the sputtered atoms. Samples were irradiated but were never analyzed after irradiation. Similar experiments were attempted in a non-radioactive environment using accelerator driven ions in place of fission induced fragments. These experiments showed that tracks produced parallel to the surface (and not perpendicular to the surface) are the primary source of the resulting particulate ejecta. Modeling studies were conducted in parallel with the experimental work. Because the reactor irradiation experiments were not analyzed, data on the energy of the resulting particulate ejecta was not obtained. However, some data was found in the literature on self sputtering of {sup 252}Cf that was used to estimate the velocity and hence the energy of the ejected particulates. Modeling of the data in the literature showed that the energy of the ejecta was much lower than had been anticipated. A mechanism to understand the nature of the ejecta was pursued. Initially it was proposed that the fission fragment imparts its momenta on the electrons which then impart their momenta on the nuclei. Once the nuclei are in motion, the particulate ejecta would result. This initial model was wrong. The error was in the assumption that the secondary electrons impart their momenta directly on the nuclei. Modeling and theoretical considerations showed that the secondary electrons scatter many times before imparting all their momenta. As a result, their energy transfer is

  15. Forensic evidence in apparel fabrics due to stab events.

    PubMed

    Kemp, S E; Carr, D J; Kieser, J; Niven, B E; Taylor, M C

    2009-10-30

    Stab injuries and fatalities have been reported to be the most common crimes of violence in several countries, particularly in those where access to firearms is restricted [J.M. Taupin, F.-P. Adolf, J. Robertson, Examination of damage to textiles, in: J. Robertson, M. Grieve (Eds.), Forensic Examination of Fibres, CRC Press, United States of America, 1999, pp. 65-87; A.C. Hunt, R.J. Cowling, Murder by stabbing, Forensic Sci. Int. 52 (1991) 107-112; D.A. Rouse, Patterns of stab wounds: a six year study, Med. Sci. Law 34 (1994) 67-71]. Analysis of damaged apparel may provide important information about the cause of death and the events leading up to and after the victim's final moments [M.T. Pailthorpe, N.A.G. Johnson, The private forensic scientist and the criminal justice system, in: D. Biles, J. Vernon (Eds.), Private Sector and Community Involvement in the Criminal Justice System: Conference Proceedings, vol. 23, Australian Institute of Criminology, Wellington, 1994, 231-240]. A high proportion of stab wounds occur in the chest and as this area is generally clothed many sharp force cases involve damage to fabrics [J.M. Taupin, F.-P. Adolf, J. Robertson, Examination of damage to textiles, in: J. Robertson, M. Grieve (Eds.), Forensic Examination of Fibres, CRC Press, United States of America, 1999, pp. 65-87; A.C. Hunt, R.J. Cowling, Murder by stabbing, Forensic Sci. Int. 52 (1991) 107-112; D.A. Rouse, Patterns of stab wounds: a six year study, Med. Sci. Law 34 (1994) 67-71]. The structural stabilisation and degradation of fabric due to laundering significantly alters fabric properties [S.E. Gore, R.M. Laing, C.A. Wilson, D.J. Carr, B.E. Niven, Standardizing a pre-treatment cleaning procedure and effects of application on apparel fabrics, Text. Res. J. 76 (2006) 455-464], yet the effect of such on severance morphology does not appear to have been investigated. In this work the effect of blade type (hunting knife, kitchen knife, screwdriver) on new and laundered

  16. Primary stabbing "ice-pick" headache.

    PubMed

    Mukharesh, Loulwah O; Jan, Mohammed M S

    2011-10-01

    Primary stabbing "ice-pick" headache is rarely reported in children. It is characterized by transient, sharp stabbing pain that occurs within a localized area of the scalp for seconds. Five children were diagnosed according to the International Classification of Headache Disorders Diagnostic Criteria, Second Edition. Ages at diagnosis ranged from 6-16 years (mean age, 9.8 years), with signs lasting for 3-12 months (mean, 6.5 months) before assessment. All children presented with recurrent daily to monthly headaches that were very brief, lasting for seconds. The headache was orbital in one child, temporal in one child, and occipital in three children. Three children manifested other associated migraine headache types, and two had a positive family history of migraine. Amitriptyline was prescribed to two patients because of headache frequency and severity. The signs gradually subsided in all patients during follow-up of 3 months to 5 years (mean, 27 months). Primary stabbing headache may occasionally occur in children with features different from those encountered in adults. The headache is less frequent and often occipital in location. Its signs respond well to amitriptyline. However, larger prospective pediatric studies are needed to describe this syndrome further.

  17. Transient stabbing headache from an acute thalamic hemorrhage.

    PubMed

    Robbins, Matthew S

    2011-06-01

    Stabbing headache can be encountered in both primary and secondary forms, but has been infrequently reported among patients with stroke, and is not known to be associated with a small well-circumscribed brain lesion. A 95-year-old woman taking warfarin presented with the sudden onset of stabbing headache strictly in the right frontal and supraorbital regions, along with gait imbalance and dysarthria. Neuroimaging revealed a small left thalamic hematoma. This association of an acute thalamic lesion with stabbing headache in the contralateral trigeminal distribution is discussed, along with a brief review of stabbing headache occurring in cerebrovascular disease.

  18. Herpes simplex virus following stab phlebectomy.

    PubMed

    Hicks, Caitlin W; Lum, Ying Wei; Heller, Jennifer A

    2017-03-01

    Herpes simplex virus infection following surgery is an unusual postoperative phenomenon. Many mechanisms have been suggested, with the most likely explanation related to latent virus reactivation due to a proinflammatory response in the setting of local trauma. Here, we present a case of herpes simplex virus reactivation in an immunocompetent female following a conventional right lower extremity stab phlebectomy. Salient clinical and physical examination findings are described, and management strategies for herpes simplex virus reactivation are outlined. This is the first known case report of herpes simplex virus reactivation following lower extremity phlebectomy.

  19. A Comparison of Self-Inflicted Stab Wounds Versus Assault-Induced Stab Wounds

    PubMed Central

    Ahn, Sanghyun; Kim, Dong Jin; Paik, Kwang Yeol; Chung, Jae Hee; Park, Woo-Chan; Kim, Wook; Lee, In Kyu

    2016-01-01

    Background Although self-inflicted and assault-induced knife injuries might have different mortality and morbidity rates, no studies have actually evaluated the importance of the cause of knife injuries in terms of patient outcomes and treatment strategies. Objectives The aims of this study were to assess the difference between the outcomes of patients presenting with self-inflicted stab wounds (SISW) versus assault-induced stab wounds (AISW). Patients and Methods A retrospective review of the relevant electronic medical records was performed for the period between January 2000 and December 2012 for patients who were referred to the department of surgery for stab wounds by the trauma team. The patients were divided into either SISW (n = 10) or AISW groups (n = 11), depending on the cause of the injury. Results A total of 19 patients had undergone exploratory laparotomy. Of the nine patients with SISW undergoing this procedure, no injury was found in seven of the patients. In the AISW group, eight of the ten laparotomies were therapeutic. Three patients in the AISW group died during hospital admission. The average number of stab wounds was 1.2 for the SISW group and 3.5 for the AISW group. Organ injuries were more frequent in the AISW group, affecting the lung (2), diaphragm (3), liver (5), small bowel (2), colon (2), and kidney (1). Conclusions Although evaluations of the initial vital signs and physical examinations are still important, the history regarding the source of the stab wounds (AISW vs. SISW) may be helpful in determining the appropriate treatment methods and predicting patient outcomes. PMID:28184363

  20. Neutron emission effects on final fragments mass and kinetic energy distribution from low energy fission of 34U

    NASA Astrophysics Data System (ADS)

    Montoya, M.; Rojas, J.; Lobato, I.

    2008-12-01

    The kinetic energy distribution as a function of mass of final fragments (m) from low energy fission of $^{234}U$, measured with the Lohengrin spectrometer by Belhafaf et al. presents a peak around m=108 and another around m = 122. The authors attribute the first peak to the evaporation of a large number of neutrons around the corresponding mass number; and the second peak to the distribution of the primary fragment kinetic energy. Nevertheless, the theoretical calculations related to primary distribution made by Faust et al. do not result in a peak around m = 122. In order to clarify this apparent controversy, we have made a numerical experiment in which the masses and the kinetic energy of final fragments are calculated, assuming an initial distribution of the kinetic energy without peaks on the standard deviation as function of fragment mass. As a result we obtain a pronounced peak on the standard deviation of the kinetic energy distribution around m = 109, a depletion from m = 121 to m = 129, and an small peak around m = 122, which is not as big as the measured by Belhafaf et al. Our simulation also reproduces the experimental results on the yield of the final mass, the average number of emitted neutrons as a function of the provisional mass (calculated from the values of the final kinetic energy of the complementary fragments) and the average value of fragment kinetic energy as a function of the final mass.

  1. Ultrasonic Weld Sealing of M55 Stab Detonators

    DTIC Science & Technology

    1981-01-01

    Single-base Fluorocarbon HIGH EXPLOSIVES PRIMERS Cannon Electric Pistol Shot Stab Lithium aluminum hydride Magnesium hydride Bromine...trifluoride Nitronium perchlorate Fluoboric acid Inhibited red fuming nitric acid (IRFNA) Phosphorus sesquisulfide, red phosphorus and potassium

  2. Characteristics and rehabilitation for patients with spinal cord stab injury.

    PubMed

    Wang, Fangyong; Zhang, Junwei; Tang, Hehu; Li, Xiang; Jiang, Shudong; Lv, Zhen; Liu, Shujia; Chen, Shizheng; Liu, Jiesheng; Hong, Yi

    2015-12-01

    [Purpose] The objective of the study was to compare the incidence, diagnosis, treatment, and prognosis of patients with spinal cord stab injury to those with the more common spinal cord contusion injury. [Subjects] Of patients hospitalized in China Rehabilitation Research Center from 1994 to 2014, 40 of those having a spinal cord stab injury and 50 with spinal cord contusion were selected. [Methods] The data of all patients were analyzed retrospectively. The cases were evaluated by collecting admission and discharge ASIA (American Spinal Injury Association) and ADL (activity of daily living) scores. [Results] After a comprehensive rehabilitation program, ASIA and ADL scores of patients having both spinal cord stab injury and spinal cord contusion significantly increase. However, the increases were noted to be higher in patients having a spinal cord stab injury than those having spinal cord contusion. [Conclusion] Comprehensive rehabilitation is effective both for patients having spinal cord stab injury and those with spinal cord contusion injury. However, the prognosis of patients having spinal cord stab injury is better than that of patients with spinal cord contusion.

  3. Mesenteric calcification following abdominal stab wound

    PubMed Central

    Hicks, Caitlin W.; Velopulos, Catherine G.; Sacks, Justin M.

    2014-01-01

    INTRODUCTION Heterotopic ossification (HO) refers to the formation of bone in non-ossifying tissue. Heterotopic mesenteric ossification is a rare form of HO that is characterized by the formation of an ossifying pseudotumour at the base of the mesentery, usually following abdominal surgery. PRESENTATION OF CASE We describe a case of mesenteric HO in a young male who presented for elective ventral incisional hernia repair following a stab wound to the abdomen requiring exploratory laparotomy 21 months earlier. Preoperative workup was unremarkable, but a hard, bone-like lesion was noted to encircle the base of the mesentery upon entering the abdomen, consistent with HO. The lesion was excised with close margins, and his hernia was repaired without incident. DISCUSSION Traumatic HO describes the ossification of extra-skeletal tissue that specifically follows a traumatic event. It usually occurs adjacent to skeletal tissue, but has been occasionally described in the abdomen as well, usually in patients who suffer abdominal trauma. Overall the prognosis of HO is good, as it is considered a benign lesion with no malignant potential. However, the major morbidity associated with mesenteric HO is bowel obstruction. CONCLUSION The size, location, and symptoms related to our patient's mesenteric HO put him risk for obstruction in the future. As a result, the mass was surgically excised during his ventral hernia repair with good outcomes. PMID:24981165

  4. Selective Nonoperative Management of Abdominal Stab Wounds.

    PubMed

    Murry, Jason S; Hoang, David M; Ashragian, Sogol; Liou, Doug Z; Barmparas, Galinos; Chung, Rex; Alban, Rodrigo F; Margulies, Daniel R; Ley, Eric J

    2015-10-01

    Stab wounds (SW) to the abdomen traditionally require urgent exploration when associated with shock, evisceration, or peritonitis. Hemodynamically stable patients without evisceration may benefit from serial exams even with peritonitis. We compared patients taken directly to the operating room with abdominal SWs (ED-OR) to those admitted for serial exams (ADMIT). We retrospectively reviewed hemodynamically stable patients presenting with any abdominal SW between January 2000 and December 2012. Exclusions included evidence of evisceration, systolic blood pressure ≤110 mm Hg, or blood transfusion. NON-THER was defined as abdominal exploration without identification of intra-abdominal injury requiring repair. Of 142 patients included, 104 were ED-OR and 38 were ADMIT. When ED-OR was compared with ADMIT, abdominal Abbreviated Injury Score was higher (2.4 vs 2.1; P = 0.01) and hospital length of stay was longer (4.8 vs 3.3 days; P = 0.04). Incidence of NON-THER was higher in ED-OR cohort (71% vs 13%; P ≤ 0.001). In a regression model, ED-OR was a predictor of NON-THER (adjusted odds ratio 16.6; P < 0.001). One patient from ED-OR expired after complications from NON-THER. There were no deaths in the ADMIT group. For those patients with abdominal SWs who present with systolic blood pressure ≥110 mm Hg, no blood product transfusion in the emergency department and lacking evisceration, admission for serial abdominal exams may be preferred regardless of abdominal exam.

  5. Assessment of Reporting, Attitudes and Knowledge About the Stab Incidents and Professional Risk of Viral Infection among Health Care Professionals in Primary Health Care

    PubMed Central

    Becirovic, Sabina; Pranjic, Nurka; Sarajlic-Spahic, Selvedina; Ahmetagic, Sead; Huseinagic, Senad

    2013-01-01

    Conflict of interest: none declared. Goal The goal of the research is to determine the relationship between frequency and reporting of stab incidents, attitudes and knowledge about stab incidents and occupational risk for transmission of viral infection with HBV, HCV or HIV among health care professionals employed in primary health care. Material and methods Conducted is prospective, cross-section study by questionnaires in 2012. The survey included health professionals in Primary Health Care Center in Tuzla. The final sample has 131 respondents (85% women). Statistical analysis was performed using the statistical package SPSS version 20.0. Results The prevalence rate of stab incidents throughout their career in our study was 66%; while the rate of reported incidents was 4.83 ˜ 5 times lower than the actual prevalence. In 49 out of 87 cases this was a case of hollow needle prick. The most common causes of stab incidents are the time pressure, unforeseen reactions of patients and lack of concentration. Conclusion Stab incidents are often not reported in in developing countries. Training in order to raise awareness and knowledge about the problem, proper procedures, good organization of work and anti-stress program, safer disposal, conducting prophylaxis before and after exposure monitored by the relevant institutions of occupational medicine should contribute to solving this problem. PMID:24082835

  6. Impact of prompt-neutron corrections on final fission-fragment distributions

    NASA Astrophysics Data System (ADS)

    Al-Adili, A.; Hambsch, F.-J.; Pomp, S.; Oberstedt, S.

    2012-11-01

    Background: One important quantity in nuclear fission is the average number of prompt neutrons emitted from the fission fragments, the prompt neutron multiplicity, ν¯. The total number of prompt fission neutrons, ν¯tot, increases with increasing incident neutron energy. The prompt-neutron multiplicity is also a function of the fragment mass and the total kinetic energy of the fragmentation. Those data are only known in sufficient detail for a few thermal-neutron-induced fission reactions on, for example, 233,235U and 239Pu. The enthralling question has always been asked how the additional excitation energy is shared between the fission fragments. The answer to this question is important in the analysis of fission-fragment data taken with the double-energy technique. Although in the traditional approach the excess neutrons are distributed equally across the mass distribution, a few experiments showed that those neutrons are predominantly emitted by the heavy fragments.Purpose: We investigated the consequences of the ν(A,TKE,En) distribution on the fission fragment observables.Methods: Experimental data obtained for the 234U(n,f) reaction with a Twin Frisch Grid Ionization Chamber, were analyzed assuming two different methods for the neutron evaporation correction. The effect of the two different methods on the resulting fragment mass and energy distributions is studied.Results: We found that the preneutron mass distributions obtained via the double-energy technique become slightly more symmetric, and that the impact is larger for postneutron fission-fragment distributions. In the most severe cases, a relative yield change up to 20-30% was observed.Conclusions: We conclude that the choice of the prompt-neutron correction method has strong implications on the understanding and modeling of the fission process and encourages new experiments to measure fission fragments in coincidence with prompt fission neutrons. Even more, the correct determination of postneutron

  7. Char particle fragmentation and its effect on unburned carbon during pulverized coal combustion. Final report, March 20, 1997

    SciTech Connect

    Mitchell, R.E.

    1997-12-31

    This document is the final report of work on a project concerned with the fragmentation of char particles during pulverized coal combustion that was conducted at the High Temperature Gasdynamics Laboratory at Stanford University, Stanford, California. The project is intended to satisfy, in part, PETC`s research efforts to understand the chemical and physical processes that govern coal combustion. The overall objectives of the project were: (1) to characterize the fragmentation events as a function of combustion environment, (2) to characterize fragmentation with respect to particle porosity and mineral loadings, (3) to assess overall mass loss rates with respect to particle fragmentation, and (4) to quantify the impact of fragmentation on unburned carbon in ash. The knowledge obtained during the course of this project can be used to predict accurately the overall mass loss rates of coals based on both the physical and chemical characteristics of their chars. The work provides a means of assessing reasons for unburned carbon in the ash of coal fired boilers and furnaces.

  8. Striation patterns in serrated blade stabs to cartilage.

    PubMed

    Pounder, Derrick J; Reeder, Francesca D

    2011-05-20

    Stab wounds were made in porcine cartilage with 13 serrated knives, amongst which 4 were drop-point and 9 straight-spine; 9 coarsely serrated, 3 finely serrated and 1 with mixed pattern serrations. The walls of the stab tracks were cast with dental impression material, and the casts photographed together with the knife blades for comparison. All 13 serrated blades produced an "irregularly regular" pattern of striations on cartilage in all stabbings. Unusual and distinctive blade serration patterns produced equally distinctive wound striation patterns. A reference collection of striation patterns and corresponding blades might prove useful for striation pattern analysis. Drop-point blades produced similar striations to straight-spine blades except that the striations were not parallel but rather fan-shaped, converging towards the wound exit. The fan-shaped striation pattern characteristic of drop-point blades is explained by the initial lateral movement of the blade through the cartilage imposed by the presence of the drop point shape. It appears that the greater the overall angle of the drop point, the shorter the blade length over which the drop point occurs, and the closer the first serration is to the knife tip, the more obvious is the fan-shaped pattern. We anticipate that micro-irregularities producing individualising characteristics in non-serrated drop point blades, provided they were located at the tip opposite the drop point, should also show a fan-shaped pattern indicative of a drop point blade. The examination of the walls of stab wounds to cartilage represents an under-utilised source of forensic information to assist in knife identification.

  9. The stab resistant properties of Kevlar/STF composites

    NASA Astrophysics Data System (ADS)

    Zhao, Jinhua; Cao, Hailin; Li, Xia; Wan, Junxi; Wang, Kun; Zhang, Jinfeng

    2012-04-01

    A colloidal shear thickening fluid (STF) was prepared by dispersing submicron silica particles in Polyethylene glycol 200(PEG200) with ball-milling technique. Kevlar/STF composites were fabricated by soaking Kevlar in the solution of STF diluted by ethanol. The rheological behavior of the fluid with various concentrations and the effect of dilution ratio on stab resistant properties of Kevlar/STF composites were studied. The result shows that the initial viscosity and the highest viscosity of the fluid increase as the weight fraction of SiO2 increasing with the weight fraction ranging from 50% to 60%, while the critical shear rate decrease as the weight fraction increasing. The fluid has notable shear thickening behavior at SiO2 weight fraction of 59%. Two solutions with 1:0.5 and 1:1weight ratio of STF:ethanol were used to fabricate Kevlar/STF composites. It is found that the composites fabricated by solution with dilution ratio 1:1 show better stab resistant properties. The Kevlar/STF composites exhibit better stab resistant properties than the neat Kevlar with the same areal density.

  10. The development of a stabbing machine for forensic textile damage analysis.

    PubMed

    Benson, Natasha; Dos Santos, Robson Oliveria; Griffiths, Kate; Cole, Nerida; Doble, Philip; Roux, Claude; Blanes, Lucas

    2017-04-01

    This article describes the development of a horizontal stabbing machine with an interchangeable knife holder to simulate stab events. The machine consists of a motorised arm with a pneumatic system designed to deliver 60 unique stabbing positions. The mechanics were robust and the positioning system highly reproducible with standard deviations of less than 1.0mm in the x-axis and 2.3mm in the y-axis for a given stab position. The force of the instrument may be varied by the operator to a maximum of approximately 221N. The suitability of the instrument for simulating stab events was evaluated by measuring the severance length and textile damage from stab delivered from four different knives and nine penetrating angles.

  11. Atypical stab injury suggesting ritual suicide.

    PubMed

    Kučerová, Štěpánka; Vojtíšek, Tomáš; Hejna, Petr

    Sharp weapons have been one of the most common deadly tools in cases of homicide and suicide for a long time. Tentative incisions accompany the majority of suicides by sharp force and the absence of hesitation marks provokes questions about the manner of death. We present the bizarre fatality of a 41-year-old male with an isolated circumscribed incision on the right neck, where the body was found lying in a pool of blood in the shower of his apartment. The internal examination revealed a 4-cm-long channel-like defect running inwardly and downwardly along the right sternocleidomastoid region. The cause of death was external bleeding from an injured right carotid artery and internal jugular vein. The wound had clean non-contused margins without any conspicuous hesitation injuries. A fragment of a razor blade, found in blood splatters, was identified as the only potential injuring tool. The case was classified as a suicide.

  12. An Analytical Model for Predicting Stab Resistance of Flexible Woven Composites

    NASA Astrophysics Data System (ADS)

    Hou, Limin; Sun, Baozhong; Gu, Bohong

    2013-08-01

    Flexible woven composites have been widely used in geotextiles and light weight building structures. The stab resistance behavior of the flexible woven composite is an important factor for the application design. This paper reports an analytical model for predicting stab resistance of flexible woven composites under perpendicular stab with a blunt steel penetrator. The analytical model was established based on the microstructure and the deformation shape of the flexible woven composite under normal penetration. During the quasi-static stab penetration, the strain energies of warp and weft yarns and resins have been calculated. The stab resistance was calculated from the strain energies of the flexible woven composite. Furthermore, the contributions of the warp and weft yarns, resins to the stab resistance have been analyzed. It was found the three constituents have near the same contribution to the stab resistance. The higher value of weaving density, strength of yarns and especially the higher strength coating resins will lead the higher stab resistance. With the analytical model, the stab resistance would be expected to be designed in an efficient way with an acceptable precision.

  13. A concealed atriopleural fistula resulting from a cardiac stab wound.

    PubMed

    Arnáiz-García, María Elena; Arnáiz, Javier; Pontón, Alejandro; Pulitani, Ivana; González-Santos, Jose María; Arévalo-Abascal, Adolfo; Bueno-Codoñer, María E; Arnáiz-García, Ana María

    2014-09-01

    A young male presented with a right parasternal stab wound. The chest radiography was normal and transthoracic echocardiography ruled out pericardial tamponade. He remained hemodynamically stable until three hours later when signs of progressive anemia were observed. Chest computed tomography showed massive right-sided hemothorax. The patient underwent surgery, which revealed an active bleeding atriopleural fistula connecting the right atrium and draining into the right pleura resulting from the negative pressure generated during respiration. This mechanism prevented cardiac tamponade and maintained initial hemodynamically stability.

  14. 76 FR 22920 - Stab Resistance of Personal Body Armor (2000) Standard Special Technical Committee Request for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-25

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Office of Justice Programs Stab Resistance of Personal Body Armor (2000) Standard Special Technical... Institute of Justice (NIJ) is in the process of revising its Stab Resistance of Personal Body Armor...

  15. Variability of simulants used in recreating stab events.

    PubMed

    Carr, D J; Wainwright, A

    2011-07-15

    Forensic investigators commonly use simulants/backing materials to mount fabrics and/or garments on when recreating damage due to stab events. Such work may be conducted in support of an investigation to connect a particular knife to a stabbing event by comparing the severance morphology obtained in the laboratory to that observed in the incident. There does not appear to have been a comparison of the effect of simulant type on the morphology of severances in fabrics and simulants, nor on the variability of simulants. This work investigates three simulants (pork, gelatine, expanded polystyrene), two knife blades (carving, bread), and how severances in the simulants and an apparel fabric typically used to manufacture T-shirts (single jersey) were affected by (i) simulant type and (ii) blade type. Severances were formed using a laboratory impact apparatus to ensure a consistent impact velocity and hence impact energy independently of the other variables. The impact velocity was chosen so that the force measured was similar to that measured in human performance trials. Force-time and energy-time curves were analysed and severance morphology (y, z directions) investigated. Simulant type and knife type significantly affected the critical forensic measurements of severance length (y direction) in the fabric and 'skin' (Tuftane). The use of EPS resulted in the lowest variability in data, further the severances recorded in both the fabric and Tuftane more accurately reflected the dimensions of the impacting knives.

  16. The spectrum of injuries in buttock stab wounds.

    PubMed

    Campion, T; Cross, S

    2017-03-10

    Buttock stab wounds are a surprisingly common and increasing source of presentations to emergency departments. These injuries can have a significant impact on quality of life, and there are a number of often subtle, but significant, injuries that the radiologist must be alert to when interpreting computed tomography examinations in these patients. In this review, we will examine briefly the sociological reasons for the increase in these injuries, discuss appropriate imaging techniques, and provide imaging examples of the clinically important injuries that may be encountered in this region. These injuries include rectal or colonic perforation; genito-urinary trauma, for example urethral injury; injury to the sciatic nerve; and a spectrum of vascular trauma including transection and pseudoaneurysm or arteriovenous fistula formation.

  17. Suicide by more than 90 stab wounds including perforation of the skull.

    PubMed

    Karger, B; Vennemann, B

    2001-12-01

    A man committed suicide in his bathroom using a small pocket knife. At the autopsy a total of 92 stab wounds on the forehead, in both temples, the anterior aspect of the neck, the back of the neck, the chest and the sides of the trunk were found. In addition, repeated stabbing had caused a large soft tissue defect on the forehead. The frontal bone showed 3 perforations but no brain injury was present and two ribs were severed in the bony part, one of which carried a star-like pattern from repeated stabbing. No major vessels were injured and the cause of death was exsanguination after a considerable survival time. The large number of stab wounds, the perforation of bone and some injury sites, especially the head and back of the neck, are extraordinary findings in suicides which were probably favoured by insufficient anatomical knowledge and the use of a short-bladed knife. A psychiatric history could not be verified.

  18. Candida albicans spondylodiscitis following an abdominal stab wound: forensic considerations.

    PubMed

    Savall, Frederic; Dedouit, Fabrice; Telmon, Norbert; Rougé, Daniel

    2014-03-01

    Candida albicans spondylodiscitis is a fungal infection of the spine which is still unusual in spite of the increasing frequency of predisposing factors. A 22-year-old man received an abdominal stab wound during a physical assault. Initial medical care included surgery, prolonged use of indwelling vascular catheters with administration of broad-spectrum antibiotics, and hospitalization in intensive care. Two months after the event, the victim experienced back pain in the right lumbar region and septic spondylodiscitis secondary to C. albicans was diagnosed three weeks later. This case is noteworthy because of its clinical forensic context. In France, the public prosecutor orders a medico-legal assessment after an assault for all living victims in order to establish a causal relationship between the assault and its complications. In our case, the patient presented numerous risk factors for candidemia and the forensic specialist reasonably accepted that the causal relationship was certain but indirect. We have only found one published case of spondylodiscitis after an abdominal penetrating injury and the pathogenic agent was not mentioned. We have found no case reported in a forensic context. This unusual observation shows that it may be genuinely difficult to prove the causal relationship between an abdominal penetrating injury and an unusual infectious complication such as fungal spondylodiscitis.

  19. Occult diaphragmatic injury from stab wounds to the lower chest and abdomen.

    PubMed

    Madden, M R; Paull, D E; Finkelstein, J L; Goodwin, C W; Marzulli, V; Yurt, R W; Shires, G T

    1989-03-01

    Ninety-five patients with stab wounds to the lower chest and abdomen underwent routine abdominal exploration. Eighteen of these patients had diaphragmatic injury and in five patients it was the only injury found. Isolated diaphragmatic injury in asymptomatic patients cannot be reliably delineated by either serial physical examination or peritoneal lavage. Delayed recognition of incarcerated diaphragmatic hernia after stab wounds to the lower left chest and upper abdomen has an associated mortality rate of 36%. The anatomic area of concern can be defined as stab wounds that penetrate the left side of the chest below the fourth intercostal space anteriorly, the sixth intercostal space laterally, and the tip of the scapula posteriorly. Exploratory laparotomy is necessary in these patients until a reliable nonoperative method is established that can exclude injuries to the diaphragm.

  20. Stab Incision Glaucoma Surgery: A Modified Guarded Filtration Procedure for Primary Open Angle Glaucoma

    PubMed Central

    Jacob, Soosan; Figus, Michele; Ashok Kumar, Dhivya; Areeckal Incy, Saijimol

    2016-01-01

    Purpose. To describe a modified guarded filtration surgery, stab incision glaucoma surgery (SIGS), for primary open angle glaucoma (POAG). Methods. This prospective, interventional case series included patients with POAG (IOP ≥21 mmHg with glaucomatous visual field defects). After sliding superior conjunctiva down over limbus, 2.8 mm bevel-up keratome was used to create conjunctival entry and superficial corneoscleral tunnel in a single step starting 1.5 mm behind limbus. Lamellar corneoscleral tunnel was carefully dissected 0.5–1 mm into cornea and anterior chamber (AC) was entered. Kelly Descemet's punch (1 mm) was slid along the tunnel into AC to punch internal lip of the tunnel, thereby compromising it. Patency of ostium was assessed by injecting fluid in AC and visualizing leakage from tunnel. Conjunctival incision alone was sutured. Results. Mean preoperative IOP was 27.41 ± 5.54 mmHg and mean postoperative IOP was 16.47 ± 4.81 mmHg (n = 17). Mean reduction in IOP was 38.81 ± 16.55%. There was significant reduction of IOP (p < 0.000). 64.7% had IOP at final follow-up of <18 mmHg without medication and 82.35% had IOP <18 mmHg with ≤2 medications. No sight threatening complications were encountered. Conclusion. Satisfactory IOP control was noted after SIGS in interim follow-up (14.18 ± 1.88 months). PMID:27144015

  1. Stab Incision Glaucoma Surgery: A Modified Guarded Filtration Procedure for Primary Open Angle Glaucoma.

    PubMed

    Jacob, Soosan; Figus, Michele; Ashok Kumar, Dhivya; Agarwal, Ashvin; Agarwal, Amar; Areeckal Incy, Saijimol

    2016-01-01

    Purpose. To describe a modified guarded filtration surgery, stab incision glaucoma surgery (SIGS), for primary open angle glaucoma (POAG). Methods. This prospective, interventional case series included patients with POAG (IOP ≥21 mmHg with glaucomatous visual field defects). After sliding superior conjunctiva down over limbus, 2.8 mm bevel-up keratome was used to create conjunctival entry and superficial corneoscleral tunnel in a single step starting 1.5 mm behind limbus. Lamellar corneoscleral tunnel was carefully dissected 0.5-1 mm into cornea and anterior chamber (AC) was entered. Kelly Descemet's punch (1 mm) was slid along the tunnel into AC to punch internal lip of the tunnel, thereby compromising it. Patency of ostium was assessed by injecting fluid in AC and visualizing leakage from tunnel. Conjunctival incision alone was sutured. Results. Mean preoperative IOP was 27.41 ± 5.54 mmHg and mean postoperative IOP was 16.47 ± 4.81 mmHg (n = 17). Mean reduction in IOP was 38.81 ± 16.55%. There was significant reduction of IOP (p < 0.000). 64.7% had IOP at final follow-up of <18 mmHg without medication and 82.35% had IOP <18 mmHg with ≤2 medications. No sight threatening complications were encountered. Conclusion. Satisfactory IOP control was noted after SIGS in interim follow-up (14.18 ± 1.88 months).

  2. Stabbing headache in an 8-year-old girl: primary or drug induced headache?

    PubMed

    Biedroł, Agnieszka; Kaciłski, Marek; Skowronek-Bała, Barbara

    2014-04-01

    The occurrence of stabbing headaches in children requires a thorough diagnostic approach that excludes secondary headaches. The organic background should be taken into consideration when alarming symptoms occur, such as a purely 1-sided location, a change in the character of the headache, or possibly a link to physical activity. The current study describes the case of an 8-year-old girl who suffered short-lasting stabbing headache attacks. The headaches with increasing intensity and frequency started 1 month before her hospitalization and were usually preceded by physical activity (dancing, running). The pain, which was located in the right supraorbital region, lasted 1 second and occurred several times during the day. No associated symptoms were observed. In addition, the girl suffered from allergic rhinitis and was on antiallergic treatment (levocetirizine, fluticasone nasal spray). On admission she was in good general condition, and a pediatric and neurologic examination revealed no abnormalities. Her brain MRI was normal. The initial diagnosis was that the patient was suffering from primary stabbing headaches. However, during a follow-up visit 4 months later, a relationship was observed between the cessation of the headache attacks and the discontinuation of an antihistaminic drug. Six months later, the girl remained headache free. In cases involving differential diagnoses of stabbing headaches, it is important to consider the adverse reactions of the drugs used.

  3. Reversible cortical blindness following successful surgical repair of two stab wounds in the heart.

    PubMed

    El Gatit, A; Abdul Razeq, M; El Snaini, F; Saad, K; Zaiton, A

    2008-03-01

    This report describes a case of cortical blindness that followed successful surgical repair of two stab wounds in the heart in a 29-year old Libyan man. The patient presented in a state of pre cardiac arrest (shock and low cardiac output status), following multiple chest stab wounds. Chest tube was immediately inserted. Surgery was urgently performed suturing the two wounds; in the root of the aorta and in the left ventricle, and haemostasis was secured. Cardiac arrest was successfully prevented. The patient recovered smoothly, but 24 hours later he declared total blindness. Ophtalmic and neurological examinations and investigations that included fundoscopy, Electroencephalograms (EEGs) and Computed Tomography Scans revealed no abnormalities, apart from absence of alpha waves in the EEGs. We diagnosed the case as cortical blindness and continued caring for the patient conservatively. Three days later, the patient regained his vision gradually and was discharged on the 7(th) postoperative day without any remarks.

  4. Reversible Cortical Blindness Following Successful Surgical Repair Of Two Stab Wounds In The Heart

    PubMed Central

    El Gatit, A; Abdul Razeq, M; El Snaini, F; Saad, K; Zaiton, A

    2008-01-01

    This report describes a case of cortical blindness that followed successful surgical repair of two stab wounds in the heart in a 29-year old Libyan man. The patient presented in a state of pre cardiac arrest (shock and low cardiac output status), following multiple chest stab wounds. Chest tube was immediately inserted. Surgery was urgently performed suturing the two wounds; in the root of the aorta and in the left ventricle, and haemostasis was secured. Cardiac arrest was successfully prevented. The patient recovered smoothly, but 24 hours later he declared total blindness. Ophtalmic and neurological examinations and investigations that included fundoscopy, Electroencephalograms (EEGs) and Computed Tomography Scans revealed no abnormalities, apart from absence of alpha waves in the EEGs. We diagnosed the case as cortical blindness and continued caring for the patient conservatively. Three days later, the patient regained his vision gradually and was discharged on the 7th postoperative day without any remarks. PMID:21516165

  5. Suicide by skull stab wounds: a case of drug-induced psychosis.

    PubMed

    Jousset, Nathalie; Rougé-Maillart, Clotilde; Turcant, Alain; Guilleux, Michel; Le Bouil, Anne; Tracqui, Antoine

    2010-12-01

    Suicide by stabbing to the head and/or driving sharp objects into the skull is of extreme rarity. This article reports the case of a 27-year-old man, who committed suicide by multiple knife stabs and cuts to the head, the torso, one shoulder and the forearms. Autopsy showed a perforating wound of the skull and the 10-cm long broken blade of the knife being still embedded in the right temporal lobe of the brain. The deceased had no history of psychiatric illness but was currently treated by mefloquine, a quinine derivative associated with a high rate of psychiatric adverse effects. Toxicological examination confirmed a recent intake of mefloquine together with chloroquine, another antimalarial drug. To our knowledge, this is the first report of a completed suicide with very strong evidence of mefloquine implication. Discussion focuses upon mefloquine-induced psychiatric disorders and highlights the importance of performing toxicological investigations in cases of unusual suicides.

  6. Brown-Sequard syndrome associated with unusual spinal cord injury by a screwdriver stab wound

    PubMed Central

    Beer-Furlan, André Luiz; Paiva, Wellingson Silva; Tavares, Wagner Malagó; de Andrade, Almir Ferreira; Teixeira, Manoel Jacobsen

    2014-01-01

    Introduction: Stab wounds resulting in spinal cord injuries are very rare. In direct central back stabbings, the layers of muscles and the spinal column tends to deflect blades, rarely causing injuries to the spinal cord. We report an unusual case of traumatic spinal cord injury by a screwdriver stab, presented as Brown-Séquard syndrome and discuss possible pitfalls on the surgical treatment. Case report: A 34 year-old man was brought to the emergency department after a group assault with a single screwdriver stab wound on the back. Neurological examination revealed an incomplete Brown-Sequard syndrome, with grade IV motor deficit on the left leg and contralateral hemihypoalgesia below T9 level. Radiological evaluation showed a retained 9 cm screwdriver that entered and trespassed the spinal canal at T6 level, reaching the posterior mediastinum with close relation to the thoracic aorta. Vascular injury could not be excluded. The joint decision between the neurosurgery and the vascular surgery teams was the surgical removal of the screwdriver under direct visualization. A left mini-thoracotomy was performed. Simultaneously, a careful dissection was done and screwdriver was firmly pulled back on the opposite path of entry under direct visualization of the aorta. The neurological deficit was maintained immediately after the surgical procedure. Follow-up visit after 1 year showed minor motor deficit and good healing. Conclusions: It is important to consider all aspects of secondary injury on the surgical planning of penetrating spinal cord injury. The secondary injury can be minimized with multidisciplinary planning of the surgical procedure. PMID:24482724

  7. Occupational deaths due to penetrating chest injuries from sledgehammer fragments: two case reports and review of the literature.

    PubMed

    Smith, Michael E; Zumwalt, Ross

    2004-03-01

    Occupational deaths due to projectiles from hand tools are rare. We report 2 unusual cases of individuals killed by metallic projectiles produced by the fragmentation of the head of a sledgehammer. At initial examination, these wounds appear similar to atypical gunshot or stab wounds. Proper evaluation requires radiographic examination, scene correlation, and, when possible, comparison of metallic fragments retrieved at autopsy and tools from the scene.

  8. Stab injury and device implantation within the brain results in inversely multiphasic neuroinflammatory and neurodegenerative responses

    NASA Astrophysics Data System (ADS)

    Potter, Kelsey A.; Buck, Amy C.; Self, Wade K.; Capadona, Jeffrey R.

    2012-08-01

    An estimated 25 million people in the US alone rely on implanted medical devices, ˜2.5 million implanted within the nervous system. Even though many devices perform adequately for years, the host response to medical devices often severely limits tissue integration and long-term performance. This host response is believed to be particularly limiting in the case of intracortical microelectrodes, where it has been shown that glial cell encapsulation and localized neuronal cell loss accompany intracortical microelectrode implantation. Since neuronal ensembles must be within ˜50 µm of the electrode to obtain neuronal spikes and local field potentials, developing a better understanding of the molecular and cellular environment at the device-tissue interface has been the subject of significant research. Unfortunately, immunohistochemical studies of scar maturation in correlation to device function have been inconclusive. Therefore, here we present a detailed quantitative study of the cellular events and the stability of the blood-brain barrier (BBB) following intracortical microelectrode implantation and cortical stab injury in a chronic survival model. We found two distinctly inverse multiphasic profiles for neuronal survival in device-implanted tissue compared to stab-injured animals. For chronically implanted animals, we observed a biphasic paradigm between blood-derived/trauma-induced and CNS-derived inflammatory markers driving neurodegeneration at the interface. In contrast, stab injured animals demonstrated a CNS-mediated neurodegenerative environment. Collectively these data provide valuable insight to the possibility of multiple roles of chronic neuroinflammatory events on BBB disruption and localized neurodegeneration, while also suggesting the importance to consider multiphasic neuroinflammatory kinetics in the design of therapeutic strategies for stabilizing neural interfaces.

  9. Delayed myelopathy secondary to stab wound with a retained blade tip within the laminae: case report

    PubMed Central

    Wang, Hui; Ma, Lei; Ding, Wen-Yuan

    2015-01-01

    Delayed neurologic deficit after a stab wound with a retained foreign body near the spinal canal is unusual, adequate radiological examination is fundamental in detecting retained foreign bodies, especially the CT scan, surgical extraction of the foreign body is the primary task and the surgical outcome is satisfactory. Here, we report a rare case of delayed myelopathy caused by spinal stenosis secondary to broken blade tip within thoracic laminae in an old man, who was injured in a knife attack 39 years ago. The incidence, clinical presentation, diagnosis and prognosis are discussed. PMID:26629221

  10. FVIIIra, CD15, and tryptase performance in the diagnosis of skin stab wound vitality in forensic pathology.

    PubMed

    Gauchotte, Guillaume; Wissler, Marie-Pierre; Casse, Jean-Matthieu; Pujo, Julien; Minetti, Christophe; Gisquet, Héloïse; Vigouroux, Charlène; Plénat, François; Vignaud, Jean-Michel; Martrille, Laurent

    2013-09-01

    The timing of skin wounds is one of the most challenging problems in forensic pathology. In the first minutes or hours after infliction, histological examination fails to determine whether a wound was sustained before or after death. The aim of this study was to evaluate the use of three immunohistochemical markers (FVIIIra, CD15, and tryptase) for the interpretation of the timing of cutaneous stab wounds. We evaluated these markers in intravital wounds from autopsy cases (n = 12) and surgical specimens (n = 58). As controls, we used normal skin samples from autopsies (n = 8) and an original ex vivo surgical human model of recent postmortem wounds (n = 24). We found overexpression of FVIIIra in 100 % of vital wounds, but also in 53 % of the controls. The number of CD15-positive cells was higher in wound margins than in internal controls (p < 0.0001) and was significantly correlated with the time interval between incision and devascularization (p = 0.0005; minimal time for positivity, 9 min). Using the anti-tryptase antibody, we found that the mast cell degranulation rate was higher in wound margins (p < 0.0001) and correlated with the time interval (minimal time, 1 min). The sensitivity and specificity for the diagnosis of vitality were respectively 100 and 47 % for FVIIIra, 47 and 100 % for CD15, and 60 and 100 % for tryptase. The inter-observer agreement coefficients were 0.68 for FVIIIra, 0.90 for CD15, and 0.46 for tryptase. Finally, we demonstrated that these markers were not reliable in putrefied or desiccated specimens. In conclusion, CD15 and tryptase, but not FVIIIra, may be useful markers for differentiating recent antemortem from postmortem injuries.

  11. Differences between postmortem computed tomography and conventional autopsy in a stabbing murder case

    PubMed Central

    Zerbini, Talita; da Silva, Luiz Fernando Ferraz; Ferro, Antonio Carlos Gonçalves; Kay, Fernando Uliana; Junior, Edson Amaro; Pasqualucci, Carlos Augusto Gonçalves; do Nascimento Saldiva, Paulo Hilario

    2014-01-01

    OBJECTIVE: The aim of the present work is to analyze the differences and similarities between the elements of a conventional autopsy and images obtained from postmortem computed tomography in a case of a homicide stab wound. METHOD: Comparison between the findings of different methods: autopsy and postmortem computed tomography. RESULTS: In some aspects, autopsy is still superior to imaging, especially in relation to external examination and the description of lesion vitality. However, the findings of gas embolism, pneumothorax and pulmonary emphysema and the relationship between the internal path of the instrument of aggression and the entry wound are better demonstrated by postmortem computed tomography. CONCLUSIONS: Although multislice computed tomography has greater accuracy than autopsy, we believe that the conventional autopsy method is fundamental for providing evidence in criminal investigations. PMID:25518020

  12. An unusual case of orbito-frontal rod fence stab injury with a good outcome

    PubMed Central

    2013-01-01

    Background High-energy non-missile penetrating injuries (stab injuries) account for a small percentage of penetrating head injuries and they present a series of special features. Case presentation A 35-year-old man suffered orbito-frontal? and trans-cranial injuries after falling five meters from a terrace onto a rod iron fence. The removal of the metal rod was performed outside the operating room. The orbital roof was exposed and repaired through a bifrontal craniotomy and the frontal sinuses were cranialised. The orbital floor and zygoma were plated with micro-screws. Conclusion The patient recovered without significant complications, apart from a slight paresis of the right superior rectus; the ocular globe remained intact. The positive outcome obtained in this very challenging case is attributable to the competency of the Neurotrauma Unit and to the use of a synergistic approach which involved the contribution of neurosurgeons, maxillo-facial surgeons, radiologists and anaesthesiologists. PMID:23941677

  13. Fragmentation Pathways in the Uracil Radical Cation

    SciTech Connect

    Zhou, Congyi; Matsika, Spiridoula; Kotur, Marija; Weinacht, Thomas C.

    2012-08-24

    We investigate pathways for fragmentation in the uracil radical cation using ab initio electronic structure calculations. We focus on the main fragments produced in pump–probe dissociative ionization experiments. These are fragments with mass to charge ratios (m/z) of 69, 28, 41, and 42. Barriers to dissociation along the ground ionic surface are reported, which provide an estimate of the energetic requirements for the production of the main fragments. Finally, direct and sequential fragmentation mechanisms have been analyzed, and it is concluded that sequential fragmentation after production of fragment with m/z 69 is the dominant mechanism for the production of the smaller fragments.

  14. Postmortem ventilation in cases of penetrating gunshot and stab wounds to the chest.

    PubMed

    Germerott, Tanja; Preiss, Ulrich S; Ross, Steffen G; Thali, Michael J; Flach, Patricia M

    2013-11-01

    We sought to determine the effect of postmortem ventilation in combination with a suction pump in cases showing penetrating trauma to the chest with haemo- and/or pneumothorax, for better evaluation of the lungs in postmortem computed tomography (PMCT). The study included 6 subjects (1 female, 5 male; age 32-67years) with a penetrating gunshot or stab wound to the chest and consecutive pneumo- and/or haemothorax. The pneumo- and haemothorax were evacuated by a suction pump, and postmortem ventilation was applied using a home care ventilator. PMCT images with and without postmortem ventilation were compared, as well as the autopsy results. In three cases haemo- and pneumothorax was clearly reduced. Postmortem ventilation led to distinct re-expansion of the lungs in two cases, and to re-expansion of single lung lobes in two cases with shotgun injuries. No visible effect was seen in the remaining two cases, because of extensive destruction of lung tissue and blood aspiration. In two cases the injuries sustained in the individual lung lobes were successfully located during postmortem ventilation. The bullet channel was apparent in one case; in another case, injury of the pericardium became visible by generating pneumopericardium. The present method is capable of improving evaluation of the postmortem lung in the presence of single stab or gunshot wounds and if there is no severe destruction of the respiratory system and aspiration. Forensic autopsy should still be considered as the gold standard, although in some cases the present method might be helpful, especially where no autopsy is required.

  15. Chameleon fragmentation

    SciTech Connect

    Brax, Philippe

    2014-02-01

    A scalar field dark energy candidate could couple to ordinary matter and photons, enabling its detection in laboratory experiments. Here we study the quantum properties of the chameleon field, one such dark energy candidate, in an ''afterglow'' experiment designed to produce, trap, and detect chameleon particles. In particular, we investigate the possible fragmentation of a beam of chameleon particles into multiple particle states due to the highly non-linear interaction terms in the chameleon Lagrangian. Fragmentation could weaken the constraints of an afterglow experiment by reducing the energy of the regenerated photons, but this energy reduction also provides a unique signature which could be detected by a properly-designed experiment. We show that constraints from the CHASE experiment are essentially unaffected by fragmentation for φ{sup 4} and 1/φ potentials, but are weakened for steeper potentials, and we discuss possible future afterglow experiments.

  16. Fatal delayed cardiac tamponade due to rupture of micropseudoaneurysm of left anterior descending coronary artery following stab to the chest.

    PubMed

    Xing, Jingjun; Li, Shangxun; Zhang, Lin; Yang, Yi; Duan, Yijie; Li, Wenhe; Zhou, Yiwu

    2015-01-01

    Traumatic coronary pseudoaneurysm has been described to be mainly associated to iatrogenic lesion of the coronary arteries. However, chest-stab-wound-related coronary pseudoaneurysm caused by isolated partial incision of a coronary artery giving rise to fatal delayed cardiac tamponade is very rare. We describe an autopsy case in which this potentially fatal complication developed 8 days later after a thoracic stab wound. Unfortunately, the imaging examination failed to detect this defect during hospitalization. Postmortem examination revealed that the posterior wall of the left anterior descending coronary artery was intact but that the anterior wall was incised, forming a micropseudoaneurysm which had ruptured. This case highlights that isolated coronary artery injuries must be considered in any patient with a penetrating wound to the thorax, and coronary pseudoaneurysms should not be missed in these patients.

  17. Double stent technique for the treatment of an internal carotid artery pseudoaneurysm caused by zone III stab injury.

    PubMed

    Hori, Yuzo; Kiyosue, Hiro; Kashiwagi, Junichi; Asano, Tomoshige; Shuto, Rieko; Matsumoto, Yushi; Nagatomi, Hirofumi; Mori, Hiromu

    2007-10-01

    A 77-year-old man was transferred to the hospital with swelling of his neck and oropharynx after a stab injury to his oral cavity with pruning shears. Findings at complete neurologic examination were normal. Contrast-enhanced computed tomography (CT) and angiography revealed a pseudoaneurysm at the pharyngeal portion of the right internal carotid artery. Endovascular treatment was undertaken by using the double bare stent technique. The pseudoaneurysm was completely occluded immediately after the procedure. There were no complications. There were no further symptoms or evidence of recurrence of the aneurysm during the 18-month follow-up period. The double bare stent technique is safe and effective for the treatment of zone III carotid artery stab injuries.

  18. A case of cerebellar infarction caused by vertebral artery injury from a stab wound to the neck.

    PubMed

    Park, Jung Je; Shim, Hyun Seok; Jeong, Jae Ho; Whang, Soo Hyun; Kim, Jin Pyeong; Jeon, Sea Young; Kwon, Oh Jin

    2007-09-01

    Vertebral artery injuries are the least common arterial injuries because of the deep location of the vessel in a bony canal. Injury of this vessel has not been associated with neurological deficits, and it is thought that many of these injuries are not recognized. The incidence of vertebral artery injury occurring after a penetration wound to the neck varies from 1.0% in gunshot wounds to 7.4% in stab wounds. However, even with vertebral artery injury in penetration wounds of the neck the association with cerebellar infarction is a rare occurrence. We describe a case of cerebellar infarction caused by vertebral artery injury from a stab wound that severed the vessel between the transverse processes of C3 and C4 with a hypoplastic contralateral vertebral artery. The patient ultimately suffered infarction of the cerebellum due to the lack of preservation of the posterior inferior cerebellar artery blood flow. Management is discussed and the medical literature is reviewed.

  19. Unusual intracranial stab wounds inflicted with metal tent stakes for a case involving a family murder suicide.

    PubMed

    Oki, Takahito; Asamura, Hideki; Hayashi, Tokutaro; Ota, Masao

    2010-10-10

    This article presents a highly unusual homicide involving intracranial stab wounds. Of three members of a family killed by intracranial stab wounds apparently inflicted with metal tent stakes, two also showed signs of wounds inflicted during an apparent struggle with the assailant. A wooden mallet appears to be the implement use to drive the metal stakes into the cranial cavity. In all victims, toxicological analysis indicated the presence of brotizolam at concentrations ranging from 30 to 50ngml(-1). The one victim who showed no signs of wounds incurred during a defensive struggle was found to have blood alcohol levels of 2.87mgml(-1). The assailant, another family member with a history of major psychiatric disorders, apparently committed suicide by drowning following the attacks.

  20. A Penetrating Stab Wound of the Perianal Area Causing a Combined Rectal and Bladder Injury: One Case Report

    PubMed Central

    Tazi, Mohammed Fadl; Khallouk, Abdelhak; Ahallal, Youness; Riyach, Omar; El Ammari, Jalal Eddine; El Fassi, Mohammed Jamal; Farih, Moulay Hassan

    2012-01-01

    Although the management of either isolated rectal or bladder injury is no more controversial, their combined effect and their optimal management has been seldom reported in the English literature. From a case report of a 45-year-old male who was found to have a combined bladder and rectal injury secondary to a stab wound of the perianal area, the authors develop a diagnostic and therapeutic algorithm for the management of this uncommon trauma. PMID:22844630

  1. Surgical judgment in the management of abdominal stab wounds. Utilizing clinical criteria from a 10-year experience.

    PubMed Central

    Lee, W C; Uddo, J F; Nance, F C

    1984-01-01

    A 10-year retrospective study of patients with stab wounds to the abdomen managed under a protocol of selective management has been performed. Patients were assessed on the basis of clinical presentation and physical examination, with minimal diagnostic studies. Peritoneal lavage was not utilized in the evaluation of the patients. Two hundred and nineteen such patients were identified. One hundred and eleven of these patients were treated nonoperatively. Ninety patients were treated by immediate laparotomy. Eighteen patients, initially observed, underwent delayed laparotomy. One patient, not explored despite clear-cut indications for laparotomy, died of sepsis, emphasizing the need for strict adherence to the stated protocol. The negative or unnecessary laparotomy rate was 7.8%. The false-negative examination rate was 5.5%. Overall mortality rate was 2.3%. The accuracy of careful clinical evaluation and observation is comparable to, or better than, any other method currently available to identify intra-abdominal injuries in patients with abdominal stab wounds. The study suggests that selective management of stab wounds of the abdomen may be safely practiced in a smaller community hospital. PMID:6721604

  2. The 2-repeat allele of the MAOA gene confers an increased risk for shooting and stabbing behaviors.

    PubMed

    Beaver, Kevin M; Barnes, J C; Boutwell, Brian B

    2014-09-01

    There has been a great deal of research examining the link between a polymorphism in the promoter region of the MAOA gene and antisocial phenotypes. The results of these studies have consistently revealed that low activity MAOA alleles are related to antisocial behaviors for males who were maltreated as children. Recently, though, some evidence has emerged indicating that a rare allele of the MAOA gene-that is, the 2-repeat allele-may have effects on violence that are independent of the environment. The current study builds on this research and examines the association between the 2-repeat allele and shooting and stabbing behaviors in a sample of males drawn from the National Longitudinal Study of Adolescent Health. Analyses revealed that African-American males who carry the 2-repeat allele are significantly more likely than all other genotypes to engage in shooting and stabbing behaviors and to report having multiple shooting and stabbing victims. The limitations of the study are discussed and suggestions for future research are offered.

  3. Endovascular Repair of an Actively Hemorrhaging Stab Wound Injury to the Abdominal Aorta

    SciTech Connect

    Hussain, Qasim; Maleux, Geert Heye, Sam; Fourneau, Inge

    2008-09-15

    Traumatic injury of the abdominal aorta is rare and potentially lethal (Yeh et al., J Vasc Surg 42(5):1007-1009, 2005; Chicos et al., Chirurgia (Bucur) 102(2):237-240, 2007) as it can result in major retroperitoneal hemorrhage, requiring an urgent open surgery. In case of concomitant bowel injury or other conditions of hostile abdomen, endovascular repair can be an alternative treatment. This case report deals with a 50-year-old man presenting at the emergency ward with three stab wounds: two in the abdomen and one in the chest. During explorative laparotomy, liver laceration and bowel perforation were repaired. One day later, abdominal CT-scan revealed an additional retroperitoneal hematoma associated with an aortic pseudoaneurysm, located anteriorly 3 cm above the aortic bifurcation. Because of the risk of graft infection, an endovascular repair of the aortic injury using a Gore excluder stent-graft was performed. Radiological and clinical follow-up revealed a gradual shrinkage of the pseudo-aneurysm and no sign of graft infection at two years' follow-up.

  4. [Forensic medical expertise of the stab wounds: the current state-of-the art].

    PubMed

    Sarkisian, B A; Karpov, D A

    2014-01-01

    This review of special literature encompasses the publications on the injuries inflicted by piercing objects. The results of analysis of these materials indicate that both the mechanisms of formation and the morphological features of stab wounds and damages to the clothes are studied perfectly well. Their shape and morphological patterns are shown to be dependent on the size, shape, and cross-section area of the great variety of the piercing objects. However, investigations carried out thus far did not take into consideration the formation of the signs of skin plastic deformation, such as edge portions of borderline thickening, stretching of epidermis over the walls, transformation of the epidermal network pattern into longitudinal folding, etc. It is concluded that further studies are necessary to better characterize injuries inflicted by piercing objects differing in the sharpness and the shape of cross section and thereby to obtain a deeper insight in the morphological features. It can be expected that such studies will provide a basis for the development of criteria for the individual and intra-group expert identification of the traumatic agents.

  5. Does cone beam CT actually ameliorate stab wound analysis in bone?

    PubMed

    Gaudio, D; Di Giancamillo, M; Gibelli, D; Galassi, A; Cerutti, E; Cattaneo, C

    2014-01-01

    This study aims at verifying the potential of a recent radiological technology, cone beam CT (CBCT), for the reproduction of digital 3D models which may allow the user to verify the inner morphology of sharp force wounds within the bone tissue. Several sharp force wounds were produced by both single and double cutting edge weapons on cancellous and cortical bone, and then acquired by cone beam CT scan. The lesions were analysed by different software (a DICOM file viewer and reverse engineering software). Results verified the limited performances of such technology for lesions made on cortical bone, whereas on cancellous bone reliable models were obtained, and the precise morphology within the bone tissues was visible. On the basis of such results, a method for differential diagnosis between cutmarks by sharp tools with a single and two cutting edges can be proposed. On the other hand, the metrical computerised analysis of lesions highlights a clear increase of error range for measurements under 3 mm. Metric data taken by different operators shows a strong dispersion (% relative standard deviation). This pilot study shows that the use of CBCT technology can improve the investigation of morphological stab wounds on cancellous bone. Conversely metric analysis of the lesions as well as morphological analysis of wound dimension under 3 mm do not seem to be reliable.

  6. Stiletto stabbing: penetrating injury to the hypothalamus with hyperacute diabetes insipidus.

    PubMed

    Itshayek, Eyal; Gomori, John Moshe; Spektor, Sergey; Cohen, José E

    2010-12-01

    Diabetes insipidus (DI) is a well documented complication observed after traumatic head injuries. We report a case of hyperacute onset DI in a 19-year-old male who sustained a hypothalamic-pituitary injury when he was stabbed in the head with a 30-cm long thin-bladed knife. At CT, our patient showed significant hemorrhagic contusions of the lower hypothalamus. He developed polydipsia, polyuria, and mild hypernatremia in the Emergency Department. Diagnostic digital subtraction angiography showed a hypervascular congestive pituitary gland with prominent draining veins. On the third day his hypernatremia became severe (183mEq/L). He was managed with parenteral fluids and a regimen of intranasal DDAVP (1-desamino 8-d-arginine vasopressin), leading to improved plasmatic sodium levels, urine output, and urinary specific gravity. In patients presenting with hyperacute posttraumatic DI, emergency room physicians and neurosurgeons should rule out direct injury to the hypothalamus and/or the posterior lobe of the pituitary, and initiate early pharmacological treatment.

  7. A new method of ergonomic testing of gloves protecting against cuts and stabs during knife use.

    PubMed

    Irzmańska, Emilia; Tokarski, Tomasz

    2017-05-01

    The paper presents a new method of ergonomic evaluation of gloves protecting against cuts and stabs during knife use, consisting of five manual dexterity tests. Two of them were selected based on the available literature and relevant safety standards, and three were developed by the authors. All of the tests were designed to simulate occupational tasks associated with meat processing as performed by the gloved hand in actual workplaces. The tests involved the three most common types of protective gloves (knitted gloves made of a coverspun yarn, metal mesh gloves, and metal mesh gloves with an ergonomic polyurethane tightener) and were conducted on a group of 20 males. The loading on the muscles of the upper limb (adductor pollicis, flexor carpi ulnaris, flexor carpi radialis, and biceps brachii) was measured using surface electromyography. For the obtained muscle activity values, correlations were found between the glove type and loading of the upper limb. ANOVA showed that the activity of all muscles differed significantly between the five tests. A relationship between glove types and electromyographic results was confirmed at a significance level of α = 0.05.

  8. Fragmentation Processes

    NASA Astrophysics Data System (ADS)

    Whelan, Colm T.

    2012-12-01

    Preface; 1. Direct and resonant double-photoionization: from atoms to solids L. Avaldi and G. Stefani; 2. The application of propagation exterior complex scaling to atomic collisions P. L. Bartlett and A. T. Stelbovics; 3. Fragmentation of molecular-ion beams in intense ultra-short laser pulses I. Ben-Itzhak; 4. Atoms with one and two active electrons in strong laser fields I. A. Ivanov and A. S. Kheifets; 5. Experimental aspects of ionization studies by positron and positronium impact G. Laricchia, D. A. Cooke, Á. Kövér and S. J. Brawley; 6. (e,2e) spectroscopy using fragmentation processes J. Lower, M. Yamazaki and M. Takahashi; 7. A coupled pseudostate approach to the calculation of ion-atom fragmentation processes M. McGovern, H. R. J. Walters and C. T. Whelan; 8. Electron Impact Ionization using (e,2e) coincidence techniques from threshold to intermediate energies A. J. Murray; 9. (e,2e) processes on atomic inner shells C. T. Whelan; 10. Spin resolved atomic (e,2e) processes J. Lower and C. T. Whelan; Index.

  9. Computational and Experimental Determination of Fragmentation for Naturally Fragmenting Warheads

    DTIC Science & Technology

    1981-05-01

    Table Page I Chemical analysis of Armco iron and HF-I steel ....................... 3 2 Summary of tensile-pull measurements for transverse-direction...ntered) REPORT DOCUMENTATION PAGE - E-EFORE COMTLETING FORM I REPORT NUMBER 2 GOVT ACCESSION NO. 3 RECIPIENT’S CATALOG NUMBERNSWC TR 80-238 4 TITLE (and...Sulbtitle) S TYPE OF REPORT & PERIOD COVERED COMPUTATIONAL AND EXPERIMENTAL 1 Final DETERMINATION OF FRAGMENTATION FOR NATURALLY FRAGMENTING WARHEADS

  10. IMPACT fragmentation model developments

    NASA Astrophysics Data System (ADS)

    Sorge, Marlon E.; Mains, Deanna L.

    2016-09-01

    The IMPACT fragmentation model has been used by The Aerospace Corporation for more than 25 years to analyze orbital altitude explosions and hypervelocity collisions. The model is semi-empirical, combining mass, energy and momentum conservation laws with empirically derived relationships for fragment characteristics such as number, mass, area-to-mass ratio, and spreading velocity as well as event energy distribution. Model results are used for several types of analysis including assessment of short-term risks to satellites from orbital altitude fragmentations, prediction of the long-term evolution of the orbital debris environment and forensic assessments of breakup events. A new version of IMPACT, version 6, has been completed and incorporates a number of advancements enabled by a multi-year long effort to characterize more than 11,000 debris fragments from more than three dozen historical on-orbit breakup events. These events involved a wide range of causes, energies, and fragmenting objects. Special focus was placed on the explosion model, as the majority of events examined were explosions. Revisions were made to the mass distribution used for explosion events, increasing the number of smaller fragments generated. The algorithm for modeling upper stage large fragment generation was updated. A momentum conserving asymmetric spreading velocity distribution algorithm was implemented to better represent sub-catastrophic events. An approach was developed for modeling sub-catastrophic explosions, those where the majority of the parent object remains intact, based on estimated event energy. Finally, significant modifications were made to the area-to-mass ratio distribution to incorporate the tendencies of different materials to fragment into different shapes. This ability enabled better matches between the observed area-to-mass ratios and those generated by the model. It also opened up additional possibilities for post-event analysis of breakups. The paper will discuss

  11. Stab wounds of the anterior abdomen. Analysis of a management plan using local wound exploration and quantitative peritoneal lavage.

    PubMed Central

    Oreskovich, M R; Carrico, C J

    1983-01-01

    A management plan for stab wounds to the anterior abdomen incorporating local wound exploration and quantitative peritoneal lavage was applied to 572 patients. One hundred eighty-five of these patients presented with shock, peritonitis, or evisceration and underwent immediate exploratory laparotomy with the finding of an intraperitoneal organ injury in 183 (99%). The remaining 387 patients with a negative physical examination underwent exploration of the stab wound to determine fascial penetration. Wound exploration was negative in 151 of these patients and they were discharged from the emergency room. Two hundred thirty-six additional patients had penetration of the fascia and underwent peritoneal lavage. Ninety-two per cent of patients with lavage counts greater than 50,000 had an intraperitoneal organ injury. No patients with lavage counts less than 1,000 red cells had an organ injury. Forty-three per cent of patients in the intermediate group (1,000-50,000 RBCs/mm3) had an organ injury and 59% included penetration of a hollow viscus. An approach incorporating local wound exploration and quantitative peritoneal lavage followed by exploratory laparotomy for red blood cell counts greater than 1,000 should result in less than 10% negative laparotomies and no missed injuries. PMID:6625712

  12. Comparison of single incision and multi incision diagnostic laparoscopy on evaluation of diaphragmatic status after left thoracoabdominal penetrating stab wounds

    PubMed Central

    İlhan, Mehmet; Gök, Ali Fuat Kaan; Bademler, Süleyman; Cücük, Ömer Cenk; Soytaş, Yiğit; Yanar, Hakan Teoman

    2017-01-01

    AIM: Single incision diagnostic laparoscopy (SIDL) may be an alternative procedure to multi-incision diagnostic laparoscopy (MDL) for penetrating thoracoabdominal stab wounds. The purpose of this study is sharing our experience and comparing two techniques for diaphragmatic status. MATERIALS AND METHODS: Medical records of 102 patients with left thoracoabdominal penetrating stab injuries who admitted to Istanbul School of Medicine, Trauma and Emergency Surgery Clinic between February 2012 and April 2016 were examined. The patients were grouped according to operation technique. Patient records were retrospectively reviewed for data including, age, sex, length of hospital stay, diaphragm injury rate, surgical procedure, operation time and operation time with wound repair, post-operative complications and accompanying injuries. RESULTS: The most common injury location was the left anterior thoracoabdomen. SIDL was performed on 26 patients. Nine (34.6%) of the 26 patients had a diaphragm injury. Seventy-six patients underwent MDL. Diaphragmatic injury was detected in 20 (26.3%) of 76 patients. The average operation time and post-operative complications were similar; there was no statistically significant difference between MDL and SIDL groups. CONCLUSION: SIDL can be used as a safe and feasible procedure in the repair of a diaphragm wounds. SIDL may be an alternative method in the diagnosis and treatment of these patients. PMID:27934791

  13. Fatal tiger attack: a case report with emphasis on typical tiger injuries characterized by partially resembling stab-like wounds.

    PubMed

    Pathak, Hrishikesh; Borkar, Jaydeo; Dixit, Pradeep; Dhawane, Shailendra; Shrigiriwar, Manish; Dingre, Niraj

    2013-10-10

    Fatalities due to attacks by tigers on humans are uncommon and are rarely described in the medico-legal literature. We herein present a forensic investigation in a unique case of a fatal tiger attack in the wild on a 35 year old female in India by an Indian Bengal tiger (Panthera tigris tigris). The attack resulted in two pairs of puncture wounds over the nape area with occult cervical spine injuries resulting from transfixing of spine due to the tiger canines; multiple puncture wounds, numerous scratches and abrasions consistent with the tiger claw injuries and injury to the right jugulocarotid vessels. This case outlines the characteristic injury pattern from such an attack along with the multiple sources of the tiger injuries. The analysis of these injuries might reveal the motivation behind the attack and the big cat species involved in the attack. A tiger injury is sometimes compared with a stab injury, as the patterned injuries due to a tiger bite are characterized by multiple penetrating, stab-like wounds. So, a special attention is paid toward establishment of the cause of death from bites by the animal teeth under unknown circumstances of trauma and to exclude the possibility of a homicide beyond reasonable doubt in such cases.

  14. Robust Object Tracking Using Valid Fragments Selection

    PubMed Central

    Li, Bo; Tian, Peng; Luo, Gang

    2016-01-01

    Local features are widely used in visual tracking to improve robustness in cases of partial occlusion, deformation and rotation. This paper proposes a local fragment-based object tracking algorithm. Unlike many existing fragment-based algorithms that allocate the weights to each fragment, this method firstly defines discrimination and uniqueness for local fragment, and builds an automatic pre-selection of useful fragments for tracking. Then, a Harris-SIFT filter is used to choose the current valid fragments, excluding occluded or highly deformed fragments. Based on those valid fragments, fragment-based color histogram provides a structured and effective description for the object. Finally, the object is tracked using a valid fragment template combining the displacement constraint and similarity of each valid fragment. The object template is updated by fusing feature similarity and valid fragments, which is scale-adaptive and robust to partial occlusion. The experimental results show that the proposed algorithm is accurate and robust in challenging scenarios. PMID:27430036

  15. Reframing landscape fragmentation's effects on ecosystem services.

    PubMed

    Mitchell, Matthew G E; Suarez-Castro, Andrés F; Martinez-Harms, Maria; Maron, Martine; McAlpine, Clive; Gaston, Kevin J; Johansen, Kasper; Rhodes, Jonathan R

    2015-04-01

    Landscape structure and fragmentation have important effects on ecosystem services, with a common assumption being that fragmentation reduces service provision. This is based on fragmentation's expected effects on ecosystem service supply, but ignores how fragmentation influences the flow of services to people. Here we develop a new conceptual framework that explicitly considers the links between landscape fragmentation, the supply of services, and the flow of services to people. We argue that fragmentation's effects on ecosystem service flow can be positive or negative, and use our framework to construct testable hypotheses about the effects of fragmentation on final ecosystem service provision. Empirical efforts to apply and test this framework are critical to improving landscape management for multiple ecosystem services.

  16. The Role of Shear-Thickening Fluids (STFs) in Ballistic and Stab-Resistance Improvement of Flexible Armor

    NASA Astrophysics Data System (ADS)

    Hasanzadeh, M.; Mottaghitalab, V.

    2014-04-01

    This paper provides a detailed review on relevant literature related to rheological properties of STFs with particular emphasis on efforts to improve their impact resistance. The review has concisely demonstrated that there are many factors affecting shear-thickening behavior of colloidal suspensions. Nanoparticle characteristics such as shape, size, distribution, solid volume fraction, and interaction with other particles as well as properties related to suspending phase and also flow field could affect the rheological properties of STFs. Recent studies on application of STFs to textile fabrics, preparation techniques, and the factors determining the performance of STF/fabric composites are summarized. Particular emphasis is laid on researches that explore the ballistic, stab, and puncture protective properties of STF-based materials and body armors.

  17. Diagnostic Accuracy of Abdominal wall Ultrasonography and Local Wound Exploration in Predicting the Need for Laparotomy following Stab Wound

    PubMed Central

    Vafaei, Ali; Heidari, Kamran; Saboorizadeh, Afshin; shams akhtari, Amin

    2017-01-01

    Introduction: Screening of patients with anterior abdominal penetrating trauma in need for laparotomy is an important issue in management of these cases. This study aimed to compare the accuracy of abdominal wall ultrasonography (AWU) and local wound exploration (LWE) in this regard. Methods: This diagnostic accuracy study was conducted on ≥ 18 year-old patients presenting to emergency department with anterior abdominal stab wound and stable hemodynamics, to compare the characteristics of AWU and LWE in screening of patients in need of laparotomy. Results: 50 cases with the mean age of 28.44 ± 7.14 years were included (80% male). Sensitivity, specificity and area under the receiver operating characteristic (ROC) curve of AWU were 70.58 (95% CI: 44.04 – 88.62), 93.33 (95% CI: 76.49 – 98.83), and 81.96 (95% CI: 69.91 – 94.01), respectively. These measures were 88.23 (62.25 – 97.93), 93.33 (76.49 – 98.83), and 90.78 (95% CI: 81.67 – 99.89) for LWE, respectively. The difference in overall accuracy of the two methods was not statistically significant (p = 0.0641). Conclusion: Based on the findings of the present study, AWU and LWE had the same specificity but different sensitivities in screening of anterior abdominal stab wound patients in need of laparotomy. The overall accuracy of LWE was slightly higher (91.48% versus 85.1%). PMID:28286841

  18. Coal char fragmentation during pulverized coal combustion

    SciTech Connect

    Baxter, L.L.

    1995-07-01

    A series of investigations of coal and char fragmentation during pulverized coal combustion is reported for a suite of coals ranging in rank from lignite to low-volatile (lv) bituminous coal under combustion conditions similar to those found in commercial-scale boilers. Experimental measurements are described that utilize identical particle sizing characteristics to determine initial and final size distributions. Mechanistic interpretation of the data suggest that coal fragmentation is an insignificant event and that char fragmentation is controlled by char structure. Chars forming cenospheres fragment more extensively than solid chars. Among the chars that fragment, large particles produce more fine material than small particles. In all cases, coal and char fragmentation are seen to be sufficiently minor as to be relatively insignificant factors influencing fly ash size distribution, particle loading, and char burnout.

  19. Comparison Of Flat-Knitted Structures Made Of Poly(P-Phenylene-2,6-Benzobisoxazole) And Para-Aramid Referring To Their Stab Resistance

    NASA Astrophysics Data System (ADS)

    Obermann, M.; Aumann, S.; Heimlich, F.; Weber, M. O.; Schwarz-Pfeiffer, A.

    2016-07-01

    In the field of protective gear, developers always aim for lighter and more flexible material in order to increase the wearing comfort. Suppliers now work on knitted garments in the sports-sector as well as in workwear and protective gear for policemen or security-agents. In a recent project different knitted structures made of a poly(p-phenylene-2,6-benzobisoxazole) (PBO)-multifilament were compared to their counterparts made of para-aramid. In focus of the comparison stood the stab-resistance linked to either the mass per unit area or the stitch density. The tested fabrics were produced on hand flat knitting machines as well as on electronical flat knitting machines of the type Stoll CMS 330TC4, in order to analyse fabrics with different tightness factor and machine gauges. The stab resistance of the different knitted fabrics was examined according to the standard of the Association of Test Laboratories for Bullet, Stab or Pike Resistant Materials and Construction Standards. The presentation includes the depiction of the results of the test series and their interpretation. Furthermore it will give an outlook on most suitable combinations of materials and structures to be used in protective gear.

  20. Parton fragmentation functions

    NASA Astrophysics Data System (ADS)

    Metz, A.; Vossen, A.

    2016-11-01

    The field of fragmentation functions of light quarks and gluons is reviewed. In addition to integrated fragmentation functions, attention is paid to the dependence of fragmentation functions on transverse momenta and on polarization degrees of freedom. Higher-twist and di-hadron fragmentation functions are considered as well. Moreover, the review covers both theoretical and experimental developments in hadron production in electron-positron annihilation, deep-inelastic lepton-nucleon scattering, and proton-proton collisions.

  1. Fragmentation Analysis - Fundamental Processes

    DTIC Science & Technology

    Wausau quartzite and anorthosite of 3.0 to 3.5 inch size were fragmented in this device. An analysis of the fragment distribution results of the drop...disc-shaped specimens of Wausau quartzite, anorthosite , and Felch marble were then fragmented with the impact pendulum device. Computer programs were

  2. Selectable fragmentation warhead

    DOEpatents

    Bryan, Courtney S.; Paisley, Dennis L.; Montoya, Nelson I.; Stahl, David B.

    1993-01-01

    A selectable fragmentation warhead capable of producing a predetermined number of fragments from a metal plate, and accelerating the fragments toward a target. A first explosive located adjacent to the plate is detonated at selected number of points by laser-driven slapper detonators. In one embodiment, a smoother-disk and a second explosive, located adjacent to the first explosive, serve to increase acceleration of the fragments toward a target. The ability to produce a selected number of fragments allows for effective destruction of a chosen target.

  3. The direct cost of traumatic secretion transfer in hermaphroditic land snails: individuals stabbed with a love dart decrease lifetime fecundity.

    PubMed

    Kimura, Kazuki; Chiba, Satoshi

    2015-04-07

    Several taxa of simultaneously hermaphroditic land snails exhibit a conspicuous mating behaviour, the so-called shooting of love darts. During mating, such land snail species transfer a specific secretion by stabbing a mating partner's body with the love dart. It has been shown that sperm donors benefit from this traumatic secretion transfer, because the secretions manipulate the physiology of a sperm recipient and increase the donors' fertilization success. However, it is unclear whether reception of dart shooting is costly to the recipients. Therefore, the effect of sexual conflict and antagonistic arms races on the evolution of traumatic secretion transfer in land snails is still controversial. To examine this effect, we compared lifetime fecundity and longevity between the individuals that received and did not receive dart shooting from mating partners in Bradybaena pellucida. Our experiments showed that the dart-receiving snails suffered reduction in lifetime fecundity and longevity. These results suggest that the costly mating behaviour, dart shooting, generates conflict between sperm donors and recipients and that sexually antagonistic arms races have contributed to the diversification of the morphological and behavioural traits relevant to dart shooting. Our findings also support theories suggesting a violent escalation of sexual conflict in hermaphroditic animals.

  4. The direct cost of traumatic secretion transfer in hermaphroditic land snails: individuals stabbed with a love dart decrease lifetime fecundity

    PubMed Central

    Kimura, Kazuki; Chiba, Satoshi

    2015-01-01

    Several taxa of simultaneously hermaphroditic land snails exhibit a conspicuous mating behaviour, the so-called shooting of love darts. During mating, such land snail species transfer a specific secretion by stabbing a mating partner's body with the love dart. It has been shown that sperm donors benefit from this traumatic secretion transfer, because the secretions manipulate the physiology of a sperm recipient and increase the donors' fertilization success. However, it is unclear whether reception of dart shooting is costly to the recipients. Therefore, the effect of sexual conflict and antagonistic arms races on the evolution of traumatic secretion transfer in land snails is still controversial. To examine this effect, we compared lifetime fecundity and longevity between the individuals that received and did not receive dart shooting from mating partners in Bradybaena pellucida. Our experiments showed that the dart-receiving snails suffered reduction in lifetime fecundity and longevity. These results suggest that the costly mating behaviour, dart shooting, generates conflict between sperm donors and recipients and that sexually antagonistic arms races have contributed to the diversification of the morphological and behavioural traits relevant to dart shooting. Our findings also support theories suggesting a violent escalation of sexual conflict in hermaphroditic animals. PMID:25761713

  5. The combined fragmentation and systematic molecular fragmentation methods.

    PubMed

    Collins, Michael A; Cvitkovic, Milan W; Bettens, Ryan P A

    2014-09-16

    fragmentation methods to accurately estimate derivatives of the molecular and crystal energies. Finally, to provide some common applications of CFM and SMF, we present some specific examples of energy calculations for moderately large molecules. For computational chemists, this fragmentation approach represents an important practical advance. It reduces the computer time required to estimate the energies of molecules so dramatically, that accurate calculations of the energies and reactivity of very large organic and biological molecules become feasible.

  6. Universality of fragment shapes

    PubMed Central

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-01-01

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism. PMID:25772300

  7. Universality of fragment shapes

    NASA Astrophysics Data System (ADS)

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-03-01

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism.

  8. Assessment of missile hazards: identification of reference fragmentation patterns.

    PubMed

    Gubinelli, Gianfilippo; Cozzani, Valerio

    2009-04-30

    Industrial accidents involving fragment projection were investigated. The analysis of fracture mechanics fundamentals allowed the exploration of the relations between the fracture characteristics and the final event leading to equipment collapse. Reference fragmentation patterns were defined on the basis of the geometrical characteristics of the categories of process vessels that are more frequently involved in fragmentation accidents. Primary scenarios leading to fragment projection were correlated to specific fragmentation patterns. A database reporting a detailed analysis of more than 140 vessel fragmentation events provided the data needed to support and validate the approach. The available data also allowed the calculation of the expected probability of fragment projection following vessel fragmentation, and the probability of the alternative fragmentation patterns with respect to the different accidental scenarios, based on the observed frequencies over the available data set.

  9. Fragmentation properties of metals

    SciTech Connect

    Grady, D.E.; Kipp, M.E.

    1996-06-01

    In the present study we are developing an experimental fracture material property test method specific to dynamic fragmentation. Spherical test samples of the metals of interest are subjected to controlled impulsive stress loads by acceleration to high velocities with a light-gas launcher facility and subsequent normal impact on thin plates. Motion, deformation and fragmentation of the test samples are diagnosed with multiple flash radiography methods. The impact plate materials are selected to be transparent to the x-ray method so that only test metal material is imaged. Through a systematic series of such tests, both strain-to-failure and fragmentation resistance properties are determined through this experimental method. Fragmentation property data for several steels, copper, aluminum, tantalum and titanium have been obtained to date. Aspects of the dynamic data have been analyzed with computational methods to achieve a better understanding of the processes leading to failure and fragmentation, and to test an existing computational fragmentation model.

  10. Fragments and Coherence

    ERIC Educational Resources Information Center

    Watson, Anne

    2008-01-01

    Can teachers contact the inner coherence of mathematics while working in a context fragmented by always-new objectives, criteria, and initiatives? How, more importantly, can learners experience the inner coherence of mathematics while working in a context fragmented by testing, modular curricular, short-term learning objectives, and lessons that…

  11. Fragment Hazard Investigation Program

    DTIC Science & Technology

    1978-10-01

    53 Ballistic Density (k) ............................................. 53 Ejection A ngle (a...54 Ejection Velocity (V) ................................................. 54 DEVELOPMENT OF EMPIRICAL RELATION...5S 54 Fragment Weight Versus Gamma for Test QD-155-08 ......................... 56 55 Fragment Range Versus Ejection Angle as a Function of

  12. Fragmentation of fullerenes

    NASA Astrophysics Data System (ADS)

    Chancey, Ryan T.; Oddershede, Lene; Harris, Frank E.; Sabin, John R.

    2003-04-01

    We have performed classical molecular-dynamics simulations of the fragmentation collisions of neutral fullerenes (C24, C60, C100, and C240) with a hard wall. The interactions between the carbon atoms are modeled by a Tersoff potential and the position of each carbon atom at each time step is calculated using a sixth-order predictor-corrector method. The statistical distribution of the fragments depends on impact energy. At low energies, the fragment distribution appears symmetric, with both the large and small fragment distributions well fitted by an exponential function of the same exponent, the value of which decreases with impact energy. At intermediate energies, the distribution of the smallest fragments can be fitted equally well by a power law or an exponential function. At high impact energies, the entire fragmentation pattern is well described by a single exponential function, the exponent increasing with energy. The observed tendencies in fragment distributions as well as the obtained exponents are in agreement with experimental observations. The fragmentation behavior of the four investigated fullerenes is very similar, and it is noted that C60 appears to be the most stable.

  13. Fragmentation in massive star formation.

    PubMed

    Beuther, Henrik; Schilke, Peter

    2004-02-20

    Studies of evolved massive stars indicate that they form in a clustered mode. During the earliest evolutionary stages, these regions are embedded within their natal cores. Here we present high-spatial-resolution interferometric dust continuum observations disentangling the cluster-like structure of a young massive star-forming region. The derived protocluster mass distribution is consistent with the stellar initial mass function. Thus, fragmentation of the initial massive cores may determine the initial mass function and the masses of the final stars. This implies that stars of all masses can form via accretion processes, and coalescence of intermediate-mass protostars appears not to be necessary.

  14. Opaque rock fragments

    SciTech Connect

    Abhijit, B.; Molinaroli, E.; Olsen, J.

    1987-05-01

    The authors describe a new, rare, but petrogenetically significant variety of rock fragments from Holocene detrital sediments. Approximately 50% of the opaque heavy mineral concentrates from Holocene siliciclastic sands are polymineralic-Fe-Ti oxide particles, i.e., they are opaque rock fragments. About 40% to 70% of these rock fragments show intergrowth of hm + il, mt + il, and mt + hm +/- il. Modal analysis of 23,282 opaque particles in 117 polished thin sections of granitic and metamorphic parent rocks and their daughter sands from semi-arid and humid climates show the following relative abundances. The data show that opaque rock fragments are more common in sands from igneous source rocks and that hm + il fragments are more durable. They assume that equilibrium conditions existed in parent rocks during the growth of these paired minerals, and that the Ti/Fe ratio did not change during oxidation of mt to hm. Geothermometric determinations using electron probe microanalysis of opaque rock fragments in sand samples from Lake Erie and the Adriatic Sea suggest that these rock fragments may have equilibrated at approximately 900/sup 0/ and 525/sup 0/C, respectively.

  15. Fragmentation of monoclonal antibodies

    PubMed Central

    Vlasak, Josef

    2011-01-01

    Fragmentation is a degradation pathway ubiquitously observed in proteins despite the remarkable stability of peptide bond; proteins differ only by how much and where cleavage occurs. The goal of this review is to summarize reports regarding the non-enzymatic fragmentation of the peptide backbone of monoclonal antibodies (mAbs). The sites in the polypeptide chain susceptible to fragmentation are determined by a multitude of factors. Insights are provided on the intimate chemical mechanisms that can make some bonds prone to cleavage due to the presence of specific side-chains. In addition to primary structure, the secondary, tertiary and quaternary structures have a significant impact in modulating the distribution of cleavage sites by altering local flexibility, accessibility to solvent or bringing in close proximity side chains that are remote in sequence. This review focuses on cleavage sites observed in the constant regions of mAbs, with special emphasis on hinge fragmentation. The mechanisms responsible for backbone cleavage are strongly dependent on pH and can be catalyzed by metals or radicals. The distribution of cleavage sites are different under acidic compared to basic conditions, with fragmentation rates exhibiting a minimum in the pH range 5–6; therefore, the overall fragmentation pattern observed for a mAb is a complex result of structural and solvent conditions. A critical review of the techniques used to monitor fragmentation is also presented; usually a compromise has to be made between a highly sensitive method with good fragment separation and the capability to identify the cleavage site. The effect of fragmentation on the function of a mAb must be evaluated on a case-by-case basis depending on whether cleavage sites are observed in the variable or constant regions, and on the mechanism of action of the molecule. PMID:21487244

  16. Universality in Fragmentation

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Holian, B. L.; Timonen, J.

    2000-04-01

    Fragmentation of a two-dimensional brittle solid by impact and ``explosion,'' and a fluid by ``explosion'' are all shown to become critical. The critical points appear at a nonzero impact velocity, and at infinite explosion duration, respectively. Within the critical regimes, the fragment-size distributions satisfy a scaling form qualitatively similar to that of the cluster-size distribution of percolation, but they belong to another universality class. Energy balance arguments give a correlation length exponent that is exactly one-half of its percolation value. A single crack dominates fragmentation in the slow-fracture limit, as expected.

  17. Fragmentation of the Chelyabinsk Fireball

    NASA Astrophysics Data System (ADS)

    Melosh, J.

    2013-12-01

    The most intense bolide since the 1908 Tunguska event occurred in the early morning hours of 15 February 2013 near the Russian town of Chelyabinsk. The impacting asteroid ranged between 17 and 20 m diameter with a mass of about 10,000 tons. Its estimated pre-atmospheric velocity was about 18.6 km/sec at a low angle of 20° from the horizontal. The resulting airburst occurred at an altitude of about 23 km and released an estimated total energy of about 440 kT (1.7 x 1015 J). The blast wave shattered windows on the ground over a wide area and collapsed the roof of a zinc factory. In spite of the size of the initital asteroid, only small fragments (a few kg, so far) have been recovered. The entry of an asteroid into Earth's atmosphere and its aerodynamic fragmentation and deceleration has been modeled by a number of authors over the past few decades. Full-featured numerical simulations are presently limited in their ability to simultaneously incorporate fragmentation, energy coupling between solid fragments and the atmosphere, and thermal radiation, but an approximate treatment of the fragmentation and dispersion of a large entering meteoroid called the 'pancake model' has achieved good fits to other observed events, including the Tunguska explosion, the 1947 Shikote-Alin fall and strewn fields from larger iron meteorite falls, such as the Henbury craters. Simulations using the pancake model can fit the overall observations of the Chelyabinsk event using an 18 m diameter asteroid of density 3000 kg/m3 following the observed trajectory and possessing an initial strength of about 7 MPa, which is relatively high for a stony meteoroid. This suggests that the asteroid was not a strengthless rubble pile, but in fact possessed considerable strength, compared to other stony meteorites of similar type. Aerodynamic breakup begins at an altitude of 31 km and the final airburst occurs at 22 km, releasing about 250 kT at this time. Subsequent to this airburst, large fragments

  18. On Disciplinary Fragmentation and Scientific Progress

    PubMed Central

    Balietti, Stefano; Mäs, Michael; Helbing, Dirk

    2015-01-01

    Why are some scientific disciplines, such as sociology and psychology, more fragmented into conflicting schools of thought than other fields, such as physics and biology? Furthermore, why does high fragmentation tend to coincide with limited scientific progress? We analyzed a formal model where scientists seek to identify the correct answer to a research question. Each scientist is influenced by three forces: (i) signals received from the correct answer to the question; (ii) peer influence; and (iii) noise. We observed the emergence of different macroscopic patterns of collective exploration, and studied how the three forces affect the degree to which disciplines fall apart into divergent fragments, or so-called “schools of thought”. We conducted two simulation experiments where we tested (A) whether the three forces foster or hamper progress, and (B) whether disciplinary fragmentation causally affects scientific progress and vice versa. We found that fragmentation critically limits scientific progress. Strikingly, there is no effect in the opposite causal direction. What is more, our results shows that at the heart of the mechanisms driving scientific progress we find (i) social interactions, and (ii) peer disagreement. In fact, fragmentation is increased and progress limited if the simulated scientists are open to influence only by peers with very similar views, or when within-school diversity is lost. Finally, disciplines where the scientists received strong signals from the correct answer were less fragmented and experienced faster progress. We discuss model’s implications for the design of social institutions fostering interdisciplinarity and participation in science. PMID:25790025

  19. On disciplinary fragmentation and scientific progress.

    PubMed

    Balietti, Stefano; Mäs, Michael; Helbing, Dirk

    2015-01-01

    Why are some scientific disciplines, such as sociology and psychology, more fragmented into conflicting schools of thought than other fields, such as physics and biology? Furthermore, why does high fragmentation tend to coincide with limited scientific progress? We analyzed a formal model where scientists seek to identify the correct answer to a research question. Each scientist is influenced by three forces: (i) signals received from the correct answer to the question; (ii) peer influence; and (iii) noise. We observed the emergence of different macroscopic patterns of collective exploration, and studied how the three forces affect the degree to which disciplines fall apart into divergent fragments, or so-called "schools of thought". We conducted two simulation experiments where we tested (A) whether the three forces foster or hamper progress, and (B) whether disciplinary fragmentation causally affects scientific progress and vice versa. We found that fragmentation critically limits scientific progress. Strikingly, there is no effect in the opposite causal direction. What is more, our results shows that at the heart of the mechanisms driving scientific progress we find (i) social interactions, and (ii) peer disagreement. In fact, fragmentation is increased and progress limited if the simulated scientists are open to influence only by peers with very similar views, or when within-school diversity is lost. Finally, disciplines where the scientists received strong signals from the correct answer were less fragmented and experienced faster progress. We discuss model's implications for the design of social institutions fostering interdisciplinarity and participation in science.

  20. A comparative audit of gunshot wounds and stab wounds to the neck in a South African metropolitan trauma service.

    PubMed

    Madsen, A S; Laing, G L; Bruce, J L; Clarke, D L

    2016-09-01

    Introduction The aim of this comparative study of gunshot wounds (GSWs) and stab wounds (SWs) to the neck was to quantify the impact of the mechanism of injury on the outcome and management of penetrating neck injury (PNI). Methods A prospective trauma registry was interrogated retrospectively. Data were analysed pertaining to demographics and injury severity score (ISS), physiology on presentation, anatomical site of wounds and injuries sustained, investigations, management, outcome and complications. Results There were 452 SW and 58 GSW cases over the 46 months of the study. Patients with GSWs were more likely to have extracervical injuries than those with SWs (69% vs 63%). The incidence of a 'significant cervical injury' was almost twice as high in the GSW cohort (55% vs 31%). For patients with transcervical GSWs, this increased to 80%. The mean ISS was 17 for GSW and 11 for SW patients. Those in the GSW cohort presented with threatened airways and a requirement for an emergency airway three times as often as patients with SWs (24% vs 7% and 14% vs 5% respectively). The incidence among GSW and SW patients respectively was 5% and 6% for airway injuries, 12% and 8% for injuries to the digestive tract, 21% and 16% for vascular injuries, 59% and 10% for associated cervical injuries, 36% and 14% for maxillofacial injuries, 16% and 9% for injuries to the head, and 35% and 45% for injuries to the chest. In the GSW group, 91% underwent computed tomography angiography (CTA), with 23% of these being positive for a vascular injury. For SWs, 74% of patients underwent CTA, with 17% positive for a vascular injury. Slightly more patients with GSWs required operative intervention than those with SWs (29% vs 26%). Conclusions Patients with GSWs to the neck have a worse outcome than those with injuries secondary to SWs. However, the proportion of neck injuries actually requiring direct surgical intervention is not increased and most cases with PNI secondary to GSWs can be managed

  1. A comparative audit of gunshot wounds and stab wounds to the neck in a South African metropolitan trauma service

    PubMed Central

    Madsen, AS; Laing, GL; Bruce, JL

    2016-01-01

    Introduction The aim of this comparative study of gunshot wounds (GSWs) and stab wounds (SWs) to the neck was to quantify the impact of the mechanism of injury on the outcome and management of penetrating neck injury (PNI). Methods A prospective trauma registry was interrogated retrospectively. Data were analysed pertaining to demographics and injury severity score (ISS), physiology on presentation, anatomical site of wounds and injuries sustained, investigations, management, outcome and complications. Results There were 452 SW and 58 GSW cases over the 46 months of the study. Patients with GSWs were more likely to have extracervical injuries than those with SWs (69% vs 63%). The incidence of a ‘significant cervical injury’ was almost twice as high in the GSW cohort (55% vs 31%). For patients with transcervical GSWs, this increased to 80%. The mean ISS was 17 for GSW and 11 for SW patients. Those in the GSW cohort presented with threatened airways and a requirement for an emergency airway three times as often as patients with SWs (24% vs 7% and 14% vs 5% respectively). The incidence among GSW and SW patients respectively was 5% and 6% for airway injuries, 12% and 8% for injuries to the digestive tract, 21% and 16% for vascular injuries, 59% and 10% for associated cervical injuries, 36% and 14% for maxillofacial injuries, 16% and 9% for injuries to the head, and 35% and 45% for injuries to the chest. In the GSW group, 91% underwent computed tomography angiography (CTA), with 23% of these being positive for a vascular injury. For SWs, 74% of patients underwent CTA, with 17% positive for a vascular injury. Slightly more patients with GSWs required operative intervention than those with SWs (29% vs 26%). Conclusions Patients with GSWs to the neck have a worse outcome than those with injuries secondary to SWs. However, the proportion of neck injuries actually requiring direct surgical intervention is not increased and most cases with PNI secondary to GSWs can be

  2. Fragmentation in Biaxial Tension

    SciTech Connect

    Campbell, G H; Archbold, G C; Hurricane, O A; Miller, P L

    2006-06-13

    We have carried out an experiment that places a ductile stainless steel in a state of biaxial tension at a high rate of strain. The loading of the ductile metal spherical cap is performed by the detonation of a high explosive layer with a conforming geometry to expand the metal radially outwards. Simulations of the loading and expansion of the metal predict strain rates that compare well with experimental observations. A high percentage of the HE loaded material was recovered through a soft capture process and characterization of the recovered fragments provided high quality data, including uniform strain prior to failure and fragment size. These data were used with a modified fragmentation model to determine a fragmentation energy.

  3. Environmentally Benign Stab Detonators

    SciTech Connect

    Gash, A; Barbee, T; Simpson, R; Satcher, J; Walton, C

    2003-12-15

    This effort attempts to demonstrate that environmentally acceptable energetic sol-gel coated flash metal multilayer nanocomposites can be used to replace current impact initiated devices (IIDs) which have hazardous and toxic components. Successful completion of this project will result in IIDs that include innocuous compounds, have sufficient output energy for initiation, meet current military specifications, are small, cost competitive, and perform as well as or better than current devices. We expect flash metal multilayer and sol-gel to be generic technologies applicable to a wide range of devices, especially in small caliber ammunition and sub-munitions. We will replace the NOL-130 mixture with a nanocomposite that consists of a mechanically robust energetic multilayer foil that has been coated with a sol-gel energetic material. The exothermic reactions are activated in this nanocomposite are the transformation of the multilayer material to its respective intermetallic alloy and the thermite reaction, which is characterized by very high temperatures, a small pressure pulse, and hot particle ejection. The proposed materials and their reaction products consist of, but are not limited to aluminum, nickel, iron, aluminum oxide, titanium, iron oxide and boron. These materials have much more desirable environmental and health characteristics than the NOL-130 composition.

  4. Target fragmentation in radiobiology

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Cucinotta, Francis A.; Shinn, Judy L.; Townsend, Lawrence W.

    1993-01-01

    Nuclear reactions in biological systems produce low-energy fragments of the target nuclei seen as local high events of linear energy transfer (LET). A nuclear-reaction formalism is used to evaluate the nuclear-induced fields within biosystems and their effects within several biological models. On the basis of direct ionization interaction, one anticipates high-energy protons to have a quality factor and relative biological effectiveness (RBE) of unity. Target fragmentation contributions raise the effective quality factor of 10 GeV protons to 3.3 in reasonable agreement with RBE values for induced micronuclei in bean sprouts. Application of the Katz model indicates that the relative increase in RBE with decreasing exposure observed in cell survival experiments with 160 MeV protons is related solely to target fragmentation events. Target fragment contributions to lens opacity given an RBE of 1.4 for 2 GeV protons in agreement with the work of Lett and Cox. Predictions are made for the effective RBE for Harderian gland tumors induced by high-energy protons. An exposure model for lifetime cancer risk is derived from NCRP 98 risk tables, and protraction effects are examined for proton and helium ion exposures. The implications of dose rate enhancement effects on space radiation protection are considered.

  5. The Fragmentation of Learning.

    ERIC Educational Resources Information Center

    Downes, Stephen

    2001-01-01

    Information and communication technologies, especially the Internet, have vastly increased access to information and educational opportunities. Steadily increasing consumer demand is driving the development of online educational materials. The end result may be a "fragmentation" of learning involving multiple learning providers and delivery modes,…

  6. Fluctuations and symmetry energy in nuclear fragmentation dynamics.

    PubMed

    Colonna, M

    2013-01-25

    Within a dynamical description of nuclear fragmentation, based on the liquid-gas phase transition scenario, we explore the relation between neutron-proton density fluctuations and nuclear symmetry energy. We show that, along the fragmentation path, isovector fluctuations follow the evolution of the local density and approach an equilibrium value connected to the local symmetry energy. Higher-density regions are characterized by smaller average asymmetry and narrower isotopic distributions. This dynamical analysis points out that fragment final state isospin fluctuations can probe the symmetry energy of the density domains from which fragments originate.

  7. Statistical models of brittle fragmentation

    NASA Astrophysics Data System (ADS)

    Åström, J. A.

    2006-06-01

    Recent developments in statistical models for fragmentation of brittle material are reviewed. The generic objective of these models is understanding the origin of the fragment size distributions (FSDs) that result from fracturing brittle material. Brittle fragmentation can be divided into two categories: (1) Instantaneous fragmentation for which breakup generations are not distinguishable and (2) continuous fragmentation for which generations of chronological fragment breakups can be identified. This categorization becomes obvious in mining industry applications where instantaneous fragmentation refers to blasting of rock and continuous fragmentation to the consequent crushing and grinding of the blasted rock fragments. A model of unstable cracks and crack-branch merging contains both of the FSDs usually related to instantaneous fragmentation: the scale invariant FSD with the power exponent (2-1/D) and the double exponential FSD which relates to Poisson process fragmentation. The FSDs commonly related to continuous fragmentation are: the lognormal FSD originating from uncorrelated breakup and the power-law FSD which can be modeled as a cascade of breakups. Various solutions to the generic rate equation of continuous fragmentation are briefly listed. Simulations of crushing experiments reveal that both cascade and uncorrelated fragmentations are possible, but that also a mechanism of maximizing packing density related to Apollonian packing may be relevant for slow compressive crushing.

  8. Heterogeneous fragmentation of metallic liquid microsheet with high velocity gradient

    NASA Astrophysics Data System (ADS)

    An-Min, He; Pei, Wang; Jian-Li, Shao

    2016-01-01

    Large-scale molecular dynamics simulations are performed to study the fragmentation of metallic liquid sheets with high velocity gradient. Dynamic fragmentation of the system involves the formation of a network of fragments due to the growth and coalescence of holes, decomposition of the network into filaments, and further breakup of the filaments into spherical clusters. The final size distribution of the fragmented clusters in the large volume limit is found to obey a bilinear exponential form, which is resulted from the heterogeneous breakup of quasi-cylindrical filaments. The main factors contributing to fragmentation heterogeneity are introduced, including strain rate inhomogeneity and matter distribution nonuniformity of fragments produced during decomposition of the network structure. Project supported by the Science and Technology Development Foundation of China Academy of Engineering Physics (Grant Nos. 2013A0201010 and 2015B0201039) and the National Natural Science Foundation of China (Grant No. 11402032).

  9. Fragmentation of Fractal Random Structures

    NASA Astrophysics Data System (ADS)

    Elçi, Eren Metin; Weigel, Martin; Fytas, Nikolaos G.

    2015-03-01

    We analyze the fragmentation behavior of random clusters on the lattice under a process where bonds between neighboring sites are successively broken. Modeling such structures by configurations of a generalized Potts or random-cluster model allows us to discuss a wide range of systems with fractal properties including trees as well as dense clusters. We present exact results for the densities of fragmenting edges and the distribution of fragment sizes for critical clusters in two dimensions. Dynamical fragmentation with a size cutoff leads to broad distributions of fragment sizes. The resulting power laws are shown to encode characteristic fingerprints of the fragmented objects.

  10. Rho kinase regulates fragmentation and phagocytosis of apoptotic cells

    SciTech Connect

    Orlando, Kelly A.; Stone, Nicole L.; Pittman, Randall N. . E-mail: pittman@pharm.med.upenn.edu

    2006-01-01

    During the execution phase of apoptosis, a cell undergoes cytoplasmic and nuclear changes that prepare it for death and phagocytosis. The end-point of the execution phase is condensation into a single apoptotic body or fragmentation into multiple apoptotic bodies. Fragmentation is thought to facilitate phagocytosis; however, mechanisms regulating fragmentation are unknown. An isoform of Rho kinase, ROCK-I, drives membrane blebbing through its activation of actin-myosin contraction; this raises the possibility that ROCK-I may regulate other execution phase events, such as cellular fragmentation. Here, we show that COS-7 cells fragment into a number of small apoptotic bodies during apoptosis; treating with ROCK inhibitors (Y-27632 or H-1152) prevents fragmentation. Latrunculin B and blebbistatin, drugs that interfere with actin-myosin contraction, also inhibit fragmentation. During apoptosis, ROCK-I is cleaved and activated by caspases, while ROCK-II is not activated, but rather translocates to a cytoskeletal fraction. siRNA knock-down of ROCK-I but not ROCK-II inhibits fragmentation of dying cells, consistent with ROCK-I being required for apoptotic fragmentation. Finally, cells dying in the presence of the ROCK inhibitor Y-27632 are not efficiently phagocytized. These data show that ROCK plays an essential role in fragmentation and phagocytosis of apoptotic cells.

  11. Fragment formula calculator (FFC): determination of chemical formulas for fragment ions in mass spectrometric data.

    PubMed

    Wegner, André; Weindl, Daniel; Jäger, Christian; Sapcariu, Sean C; Dong, Xiangyi; Stephanopoulos, Gregory; Hiller, Karsten

    2014-02-18

    a fragment ion repository that contains the chemical formulas and retained carbon atoms of a wide range of trimethylsilyl and tert-butyldimethylsilyl derivatized compounds. In total, we report the chemical formulas and backbone carbon compositions for 160 fragment ions of 43 alkylsilyl-derivatives of primary metabolites. Finally, we implemented the FFC algorithm in an easy-to-use graphical user interface and made it publicly available at http://www.ffc.lu .

  12. Investigation on laser induced salivary stone fragmentation

    NASA Astrophysics Data System (ADS)

    Sroka, Ronald; Pongratz, Thomas; Eder, Matthias; Domes, Mona; Vogeser, Michael; Johnson, Thorsten; Siedeck, Vanessa; Schroetzlmair, Florian; Zengel, Pamela

    2014-03-01

    Objective: It was the objective of this in-vitro study to investigate photon-based techniques for identifying the composition and fragmentation of salivary stones using a Ho:YAG laser. Materials and Method: Salivary stones (n=47) extracted from patients with clinical symptoms of sialolithiasis were examined in-vitro. After extraction, the stones were kept in Ringers solution until size and volume measurements could be performed. Thereafter, dual-energy CT scans (DECT) were performed to classify the composition of the stones. Subsequently, fluorescence measurements were performed by taking images under blue light excitation as well as by fluorescence spectroscopy, measuring excitation-emission-matrixes (EEM). Further investigation to identify the exact composition of the stone was performed by Raman spectroscopy and FTIR spectroscopy of stone fragments and debris. Fragmentation was performed in an aquarium set-up equipped with a mesh (hole: 1.5mm) using a Ho:YAG-laser to deliver laser pulses of 0.5, 1.0 and 1.5J/pulse at a frequency of 3Hz through a 200μm-fibre to the stone surface. The collected data were analyzed and fragmentation rates were calculated. Finally, correlation between stone composition and fragmentation was performed. Results: Blue light fluorescence excitation resulted in either fluorescence in the green spectral region or in a combination of green and red fluorescence emission. EEM-measurement showed the corresponding spectra. Raman spectroscopy showed a mixture of carbonate apatite and keratin. DECT results in evidence of calcium containing components. FTIR-spectroscopy results showed that carbonate apatite is the main component. Fragmentation experiment showed a dependency on the energy per pulse applied if the evaluation implies the ratio of fragmented weight to pulse, while the ratio fragmented weight to energy remains about constant for the three laser parameter used. Conclusion: The composition of salivary stones could be determined using

  13. New Scalings in Nuclear Fragmentation

    SciTech Connect

    Bonnet, E.; Bougault, R.; Galichet, E.; Gagnon-Moisan, F.; Guinet, D.; Lautesse, P.; Marini, P.; Parlog, M.

    2010-10-01

    Fragment partitions of fragmenting hot nuclei produced in central and semiperipheral collisions have been compared in the excitation energy region 4-10 MeV per nucleon where radial collective expansion takes place. It is shown that, for a given total excitation energy per nucleon, the amount of radial collective energy fixes the mean fragment multiplicity. It is also shown that, at a given total excitation energy per nucleon, the different properties of fragment partitions are completely determined by the reduced fragment multiplicity (i.e., normalized to the source size). Freeze-out volumes seem to play a role in the scalings observed.

  14. Fragmentation of massive dense cores down to ≲ 1000 AU: Relation between fragmentation and density structure

    SciTech Connect

    Palau, Aina; Girart, Josep M.; Estalella, Robert; Fuente, Asunción; Fontani, Francesco; Sánchez-Monge, Álvaro; Commerçon, Benoit; Hennebelle, Patrick; Busquet, Gemma; Bontemps, Sylvain; Zapata, Luis A.; Zhang, Qizhou; Di Francesco, James

    2014-04-10

    In order to shed light on the main physical processes controlling fragmentation of massive dense cores, we present a uniform study of the density structure of 19 massive dense cores, selected to be at similar evolutionary stages, for which their relative fragmentation level was assessed in a previous work. We inferred the density structure of the 19 cores through a simultaneous fit of the radial intensity profiles at 450 and 850 μm (or 1.2 mm in two cases) and the spectral energy distribution, assuming spherical symmetry and that the density and temperature of the cores decrease with radius following power-laws. Even though the estimated fragmentation level is strictly speaking a lower limit, its relative value is significant and several trends could be explored with our data. We find a weak (inverse) trend of fragmentation level and density power-law index, with steeper density profiles tending to show lower fragmentation, and vice versa. In addition, we find a trend of fragmentation increasing with density within a given radius, which arises from a combination of flat density profile and high central density and is consistent with Jeans fragmentation. We considered the effects of rotational-to-gravitational energy ratio, non-thermal velocity dispersion, and turbulence mode on the density structure of the cores, and found that compressive turbulence seems to yield higher central densities. Finally, a possible explanation for the origin of cores with concentrated density profiles, which are the cores showing no fragmentation, could be related with a strong magnetic field, consistent with the outcome of radiation magnetohydrodynamic simulations.

  15. Fragmentation of random trees

    NASA Astrophysics Data System (ADS)

    Kalay, Z.; Ben-Naim, E.

    2015-01-01

    We study fragmentation of a random recursive tree into a forest by repeated removal of nodes. The initial tree consists of N nodes and it is generated by sequential addition of nodes with each new node attaching to a randomly-selected existing node. As nodes are removed from the tree, one at a time, the tree dissolves into an ensemble of separate trees, namely, a forest. We study statistical properties of trees and nodes in this heterogeneous forest, and find that the fraction of remaining nodes m characterizes the system in the limit N\\to ∞ . We obtain analytically the size density {{φ }s} of trees of size s. The size density has power-law tail {{φ }s}˜ {{s}-α } with exponent α =1+\\frac{1}{m}. Therefore, the tail becomes steeper as further nodes are removed, and the fragmentation process is unusual in that exponent α increases continuously with time. We also extend our analysis to the case where nodes are added as well as removed, and obtain the asymptotic size density for growing trees.

  16. Fragmentation of random trees

    NASA Astrophysics Data System (ADS)

    Kalay, Ziya; Ben-Naim, Eli

    2015-03-01

    We investigate the fragmentation of a random recursive tree by repeated removal of nodes, resulting in a forest of disjoint trees. The initial tree is generated by sequentially attaching new nodes to randomly chosen existing nodes until the tree contains N nodes. As nodes are removed, one at a time, the tree dissolves into an ensemble of separate trees, namely a forest. We study the statistical properties of trees and nodes in this heterogeneous forest. In the limit N --> ∞ , we find that the system is characterized by a single parameter: the fraction of remaining nodes m. We obtain analytically the size density ϕs of trees of size s, which has a power-law tail ϕs ~s-α , with exponent α = 1 + 1 / m . Therefore, the tail becomes steeper as further nodes are removed, producing an unusual scaling exponent that increases continuously with time. Furthermore, we investigate the fragment size distribution in a growing tree, where nodes are added as well as removed, and find that the distribution for this case is much narrower.

  17. SPR-based fragment screening: advantages and applications.

    PubMed

    Neumann, T; Junker, H-D; Schmidt, K; Sekul, R

    2007-01-01

    Fragment-based screening has recently evolved into a promising strategy in drug discovery, and a range of biophysical methods can be employed for fragment library screening. Relevant approaches, such as X-ray, NMR and tethering are briefly introduced focussing on their suitability for fragment-based drug discovery. In particular the application of surface plasmon resonance (SPR) techniques to the primary screening of large libraries comprising small molecules is discussed in detail. SPR is known to be a powerful tool for studying biomolecular interactions in a sensitive and label-free detection format. Advantages of SPR methods over more traditional assay formats are discussed and the application of available channel and array based SPR systems to biosensing are reviewed. Today, SPR protocols have been applied to secondary screening of compound libraries and hit conformation, but primary screening of large fragment libraries for drug discovery is often hampered by the throughput of available systems. Chemical microarrays, in combination with SPR imaging, can simultaneously generate affinity data for protein targets with up to 9,216 immobilized fragments per array. This approach has proven to be suitable for screening fragment libraries of up to 110,000 compounds in a high throughput fashion. The design of fragment libraries and appropriate immobilization chemistries are discussed, as well as suitable follow-up strategies for fragment hit optimization. Finally, described case studies demonstrate the successful identification of selective low molecular weight inhibitors for pharmacologically relevant drug targets through the SPR screening of fragment libraries.

  18. Effect of Fibrin Packing on Managing Hepatic Hemorrhage and Liver Wound Healing in a Model of Liver Stab Wound in Rat

    PubMed Central

    Banihashemi, Mehrzad; Safari, Azam; Nezafat, Navid; Tahamtan, Mahmoodreza; Negahdaripour, Manica; Azarpira, Negar; Ghasemi, Younes

    2017-01-01

    Objective: To evaluate the effect of fibrin perihepatic packing on controlling liver hemorrhage and liver wound healing.   Methods: In this animal experimental study, 20 adult male Sprague Dawley rats, weighing 200-220 g, were included. Stab wound injury was created by number 15 scalpel, so that bilateral liver capsules and liver tissue were cut, and acute bleeding was accrued. The animals were divided into 2 study groups: control (with a primary gauze packing treatment) and test group (with fibrin packing treatment). Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total serum bilirubin (TSB) levels were measured as a liver function test during the treatment period. Blood loss was calculated for estimation of hepatic hemorrhage during surgery. After four weeks, the liver wound repair was evaluated by sampling and Hematoxylin and Eosin staining (H&E). Results: In the test group, all of animals were alive (mortality rate= 0%). Significantly, ALT and AST levels were raised after surgery, followed by a decrease ALT (p=0.783) and AST (p=0.947) to the normal level during 4 days. Estimated blood loss was 2.89 ± 0.73 mL (about 19.65% of estimated blood volume). Hematocrit levels returned to the normal level (p=0.109) after 48 hours. In the control group, the mortality rate was 50% during 12h after surgery. ALT (p=0.773) and AST (p=0.853) were decreased to normal level during 6 days, and estimated blood loss was 4.98 ± 0.77 mL (about 32.98% of estimated blood volume) in the remaining animals. Moreover, hematocrit levels returned to the normal level (p=0.432) after 72 hours. Estimated blood loss in the test group was significantly less than control group (p<0.001). Total serum bilirubin levels were not significantly different from the normal level, before and after surgery in both groups. Histopathology sections from the post-hepatectomy specimens showed that the site of the previous incision was completely repaired, and a dense fibrous septum

  19. Fragmentation of a jet with small radius

    NASA Astrophysics Data System (ADS)

    Dai, Lin; Kim, Chul; Leibovich, Adam K.

    2016-12-01

    In this paper, we consider the fragmentation of a parton into a jet with small jet radius R . Perturbatively, logarithms of R can appear, which for narrow jets can lead to large corrections. Using soft-collinear effective theory, we introduce the fragmentation function to a jet (FFJ), which describes the fragmentation of a parton into a jet. We discuss how these objects are related to the standard jet functions. Calculating the FFJ to next-to-leading order, we show that these objects satisfy the standard Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations, with a natural scale that depends upon R . By using the standard renormalization group evolution, we can therefore resum logarithms of R . We further use the soft-collinear effective theory to prove a factorization theorem where the FFJs naturally appear, for the fragmentation of a hadron within a jet with small R . Finally, we also show how this formalism can be used to resum the ratio of jet radii for a subjet to be emitted from within a fat jet.

  20. Recovery of Depleted Uranium Fragments from Soil

    SciTech Connect

    Farr, C.P.; Alecksen, T.J.; Heronimus, R.S.; Simonds, M.H.; Farrar, D.R.; Baker, K.R.; Miller, M.L.

    2008-07-01

    A cost-effective method was demonstrated for recovering depleted uranium (DU) fragments from soil. A compacted clean soil pad was prepared adjacent to a pile of soil containing DU fragments. Soil from the contaminated pile was placed on the pad in three-inch lifts using conventional construction equipment. Each lift was scanned with an automatic scanning system consisting of an array of radiation detectors coupled to a detector positioning system. The data were downloaded into ArcGIS for data presentation. Areas of the pad exhibiting scaler counts above the decision level were identified as likely locations of DU fragments. The coordinates of these locations were downloaded into a PDA that was wirelessly connected to the positioning system. The PDA guided technicians to the locations where hand-held trowels and shovels were used to remove the fragments. After DU removal, the affected areas were re-scanned and the new data patched into the data base to replace the original data. This new data set along with soil sample results served as final status survey data. (authors)

  1. Universality in fragment inclusive yields from Au+Au collisions

    NASA Astrophysics Data System (ADS)

    Insolia, A.; Tuvè, C.; Albergo, S.; Bieser, F.; Brady, F. P.; Caccia, Z.; Cebra, D.; Chacon, A. D.; Chance, J. L.; Choi, Y.; Costa, S.; Elliott, J. B.; Gilkes, M.; Hauger, J. A.; Hirsch, A. S.; Hjort, E. L.; Justice, M.; Keane, D.; Kintner, J.; Lisa, M.; Matis, H. S.; McMahan, M.; McParland, C.; Olson, D. L.; Partlan, M. D.; Porile, N. T.; Potenza, R.; Rai, G.; Rasmussen, J.; Ritter, H. G.; Romero, J. L.; Russo, G. V.; Scharenberg, R.; Scott, A.; Shao, Y.; Srivastava, B. K.; Symons, T. J. M.; Tincknell, M. L.; Wang, S.; Warren, P. G.; Wieman, H. H.; Wolf, K. L.

    2001-11-01

    The inclusive light fragment (Z⩽7) yield data in Au+Au reactions, measured by the EOS Collaboration at the LBNL Bevalac, are presented and discussed. For peripheral collisions the measured charge distributions develop progressively according to a power law which can be fitted by a single τ exponent independently of the bombarding energy in the range 250-1200 A MeV. In addition to this universal feature, we observe that the location of the maximum in the individual yields of different charged fragments shift towards lower multiplicity as the fragment charge increases from Z=3 to Z=7. This trend is common to all six measured beam energies. Moments of charge distributions and correlations among different moments are reported. Finally, the THe,DT thermometer has been constructed for central and peripheral collisions using the double yield ratios of He and D, T projectile fragments. The measured nuclear temperatures are in agreement with experimental findings in other fragmentation reactions.

  2. The Largest Fragment of a Homogeneous Fragmentation Process

    NASA Astrophysics Data System (ADS)

    Kyprianou, Andreas; Lane, Francis; Mörters, Peter

    2017-03-01

    We show that in homogeneous fragmentation processes the largest fragment at time t has size e^{-t Φ '(overline{p})}t^{-3/2 (log Φ )'(overline{p})+o(1)}, where Φ is the Lévy exponent of the fragmentation process, and overline{p} is the unique solution of the equation (log Φ )'(bar{p})=1/1+bar{p}. We argue that this result is in line with predictions arising from the classification of homogeneous fragmentation processes as logarithmically correlated random fields.

  3. Longitudinal Changes in the Structure and Inflammatory Response of the Intervertebral Disc Due to Stab Injury in a Murine Organ Culture Model

    PubMed Central

    Abraham, Adam C.; Liu, Jennifer W.; Tang, Simon Y.

    2017-01-01

    Despite the significant public health impact of intervertebral disc (IVD) degeneration and low back pain, it remains challenging to investigate the multifactorial molecular mechanisms that drive the degenerative cascade. Organ culture model systems offer the advantage of allowing cells to live and interact with their native extracellular matrix, while simultaneously reducing the amount of biological variation and complexity present at the organismal level. Murine organ cultures in particular also allow the use of widely available genetically modified animals with molecular level reporters that would reveal insights on the degenerative cascade. Here, we utilize an organ culture system of murine lumbar functional spinal units where we are able to maintain the cellular, metabolic, and structural, and mechanical stability of the whole organ over a 21-day period. Furthermore, we describe a novel approach in organ culture by using tissues from animals with an NF-κB-luc reporter in combination with a mechanical injury model, and are able to show that proinflammatory factors and cytokines such as NF-κB and IL-6 produced by IVD cells can be monitored longitudinally during culture in a stab injury model. Taken together, we utilize a murine organ culture system that maintains the cellular and tissue level behavior of the intervertebral disc and apply it to transgenic animals that allow the monitoring of the inflammatory profile of IVDs. This approach could provide important insights on the molecular and metabolic mediators that regulate the homeostasis of the IVD. PMID:27273204

  4. 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.

  5. Quantitative experimental modelling of fragmentation during explosive volcanism

    NASA Astrophysics Data System (ADS)

    Thordén Haug, Ø.; Galland, O.; Gisler, G.

    2012-04-01

    Phreatomagmatic eruptions results from the violent interaction between magma and an external source of water, such as ground water or a lake. This interaction causes fragmentation of the magma and/or the host rock, resulting in coarse-grained (lapilli) to very fine-grained (ash) material. The products of phreatomagmatic explosions are classically described by their fragment size distribution, which commonly follows power laws of exponent D. Such descriptive approach, however, considers the final products only and do not provide information on the dynamics of fragmentation. The aim of this contribution is thus to address the following fundamental questions. What are the physics that govern fragmentation processes? How fragmentation occurs through time? What are the mechanisms that produce power law fragment size distributions? And what are the scaling laws that control the exponent D? To address these questions, we performed a quantitative experimental study. The setup consists of a Hele-Shaw cell filled with a layer of cohesive silica flour, at the base of which a pulse of pressurized air is injected, leading to fragmentation of the layer of flour. The fragmentation process is monitored through time using a high-speed camera. By varying systematically the air pressure (P) and the thickness of the flour layer (h) we observed two morphologies of fragmentation: "lift off" where the silica flour above the injection inlet is ejected upwards, and "channeling" where the air pierces through the layer along sub-vertical conduit. By building a phase diagram, we show that the morphology is controlled by P/dgh, where d is the density of the flour and g is the gravitational acceleration. To quantify the fragmentation process, we developed a Matlab image analysis program, which calculates the number and sizes of the fragments, and so the fragment size distribution, during the experiments. The fragment size distributions are in general described by power law distributions of

  6. Species–fragmented area relationship

    PubMed Central

    Hanski, Ilkka; Zurita, Gustavo A.; Bellocq, M. Isabel; Rybicki, Joel

    2013-01-01

    The species–area relationship (SAR) gives a quantitative description of the increasing number of species in a community with increasing area of habitat. In conservation, SARs have been used to predict the number of extinctions when the area of habitat is reduced. Such predictions are most needed for landscapes rather than for individual habitat fragments, but SAR-based predictions of extinctions for landscapes with highly fragmented habitat are likely to be biased because SAR assumes contiguous habitat. In reality, habitat loss is typically accompanied by habitat fragmentation. To quantify the effect of fragmentation in addition to the effect of habitat loss on the number of species, we extend the power-law SAR to the species–fragmented area relationship. This model unites the single-species metapopulation theory with the multispecies SAR for communities. We demonstrate with a realistic simulation model and with empirical data for forest-inhabiting subtropical birds that the species–fragmented area relationship gives a far superior prediction than SAR of the number of species in fragmented landscapes. The results demonstrate that for communities of species that are not well adapted to live in fragmented landscapes, the conventional SAR underestimates the number of extinctions for landscapes in which little habitat remains and it is highly fragmented. PMID:23858440

  7. Thermodynamical string fragmentation

    NASA Astrophysics Data System (ADS)

    Fischer, Nadine; Sjöstrand, Torbjörn

    2017-01-01

    The observation of heavy-ion-like behaviour in pp collisions at the LHC suggests that more physics mechanisms are at play than traditionally assumed. The introduction e.g. of quark-gluon plasma or colour rope formation can describe several of the observations, but as of yet there is no established paradigm. In this article we study a few possible modifications to the Pythia event generator, which describes a wealth of data but fails for a number of recent observations. Firstly, we present a new model for generating the transverse momentum of hadrons during the string fragmentation process, inspired by thermodynamics, where heavier hadrons naturally are suppressed in rate but obtain a higher average transverse momentum. Secondly, close-packing of strings is taken into account by making the temperature or string tension environment-dependent. Thirdly, a simple model for hadron rescattering is added. The effect of these modifications is studied, individually and taken together, and compared with data mainly from the LHC. While some improvements can be noted, it turns out to be nontrivial to obtain effects as big as required, and further work is called for.

  8. Fragment screening and HIV therapeutics.

    PubMed

    Bauman, Joseph D; Patel, Disha; Arnold, Eddy

    2012-01-01

    Fragment screening has proven to be a powerful alternative to traditional methods for drug discovery. Biophysical methods, such as X-ray crystallography, NMR spectroscopy, and surface plasmon resonance, are used to screen a diverse library of small molecule compounds. Although compounds identified via this approach have relatively weak affinity, they provide a good platform for lead development and are highly efficient binders with respect to their size. Fragment screening has been utilized for a wide range of targets, including HIV-1 proteins. Here, we review the fragment screening studies targeting HIV-1 proteins using X-ray crystallography or surface plasmon resonance. These studies have successfully detected binding of novel fragments to either previously established or new sites on HIV-1 protease and reverse transcriptase. In addition, fragment screening against HIV-1 reverse transcriptase has been used as a tool to better understand the complex nature of ligand binding to a flexible target.

  9. Fragmentation functions in nuclear media

    NASA Astrophysics Data System (ADS)

    Sassot, Rodolfo; Stratmann, Marco; Zurita, Pia

    2010-03-01

    We perform a detailed phenomenological analysis of how well hadronization in nuclear environments can be described in terms of effective fragmentation functions. The medium modified fragmentation functions are assumed to factorize from the partonic scattering cross sections and evolve in the hard scale in the same way as the standard or vacuum fragmentation functions. Based on precise data on semi-inclusive deep-inelastic scattering off nuclei and hadron production in deuteron-gold collisions, we extract sets of effective fragmentation functions for pions and kaons at next-to-leading order accuracy. The obtained sets provide a rather accurate description of the kinematical dependence of the analyzed cross sections and are found to differ significantly from standard fragmentation functions both in shape and magnitude. Our results support the notion of factorization and universality in the studied nuclear environments, at least in an effective way and within the precision of the available data.

  10. An Enumerative Combinatorics Model for Fragmentation Patterns in RNA Sequencing Provides Insights into Nonuniformity of the Expected Fragment Starting-Point and Coverage Profile.

    PubMed

    Prakash, Celine; Haeseler, Arndt Von

    2017-03-01

    RNA sequencing (RNA-seq) has emerged as the method of choice for measuring the expression of RNAs in a given cell population. In most RNA-seq technologies, sequencing the full length of RNA molecules requires fragmentation into smaller pieces. Unfortunately, the issue of nonuniform sequencing coverage across a genomic feature has been a concern in RNA-seq and is attributed to biases for certain fragments in RNA-seq library preparation and sequencing. To investigate the expected coverage obtained from fragmentation, we develop a simple fragmentation model that is independent of bias from the experimental method and is not specific to the transcript sequence. Essentially, we enumerate all configurations for maximal placement of a given fragment length, F, on transcript length, T, to represent every possible fragmentation pattern, from which we compute the expected coverage profile across a transcript. We extend this model to incorporate general empirical attributes such as read length, fragment length distribution, and number of molecules of the transcript. We further introduce the fragment starting-point, fragment coverage, and read coverage profiles. We find that the expected profiles are not uniform and that factors such as fragment length to transcript length ratio, read length to fragment length ratio, fragment length distribution, and number of molecules influence the variability of coverage across a transcript. Finally, we explore a potential application of the model where, with simulations, we show that it is possible to correctly estimate the transcript copy number for any transcript in the RNA-seq experiment.

  11. Rock fragment movement in shallow rill flow - A laboratory study

    NASA Astrophysics Data System (ADS)

    Becker, Kerstin; Wirtz, Stefan; Seeger, Manuel; Gronz, Oliver; Remke, Alexander; Iserloh, Thomas; Brings, Christine; Casper, Markus; Ries, Johannes B.

    2014-05-01

    Studies concerning rill erosion mainly deal with the erosion and transport of fine material. The transport of rock fragments is examined mostly for mountain rivers. But there are important differences between the conditions and processes in rivers and in rills: (1) In most cases, the river cuts into a coarse substrate, where fine material is sparse, whereas rill erosion occurs on arable land. So the main part of the substrate is fine material and only single rock fragments influence the processes. (2) In rivers, the water depth is relatively high. There are a lot of studies about hydraulic parameters in such flows, but there is almost nothing known about hydraulic conditions in surface runoff events of a few centimeters. Additionally, little information exists about the rock fragment movement as a part of rill erosion processes on arable land. This knowledge should be increased because rock fragments cause non-stationary water turbulences in rills, which enhance the erosive force of flowing water. Field experiments can only show the fact that a certain rock fragment has moved: The starting point and the final position can be estimated. But the moving path and especially the initiation of the movement is not detectable under field conditions. Hence, we developed a laboratory setup to analyze the movement of rock fragments depending on rock fragment properties (size, form), slope gradient, flow velocity and surface roughness. By observing the rock fragments with cameras from two different angles we are able (1) to measure the rotation angles of a rock fragment during the experiment and (2) to deduce different rock fragment movement patterns. On this poster we want to present the experimental setup, developed within the scope of a master thesis, and the results of these experiments.

  12. Electroproduction in the Target Fragmentation Region

    NASA Astrophysics Data System (ADS)

    Avagyan, Harut

    2014-09-01

    The Semi-Inclusive DIS process in the Target Fragmentation Region (TFR), when the hadron is produced in the fragmentation process of the target remnants, can be described through the so-called Fracture Functions (FFs). They represent the joint probability of producing the final hadron from the target remnants, when a parton of the target nucleon is struck by the virtual photon in a hard scattering process. Like the ordinary parton distribution functions, the FFs are universal objects, thus they can be measured in one experiment at a given hard scale and then used to make predictions for other experiments, at another hard scale. Measurements of the Lambda multiplicities and polarization asymmetries in TFR, in particular, will provide information on corresponding Fracture Functions. The study of its Q2 dependence at JLab and EIC also will test the perturbative framework implied by Fracture Functions, simultaneously encoding the information on the interacting parton and on the fragmentation of the spectator system. We will present ongoing studies of electroproduction in TFR at Jefferson Lab, and proposed future measurement at upgraded JLab and Electron Ion Collider.

  13. Driven fragmentation of granular gases.

    PubMed

    Cruz Hidalgo, Raúl; Pagonabarraga, Ignacio

    2008-06-01

    The dynamics of homogeneously heated granular gases which fragment due to particle collisions is analyzed. We introduce a kinetic model which accounts for correlations induced at the grain collisions and analyze both the kinetics and relevant distribution functions these systems develop. The work combines analytical and numerical studies based on direct simulation Monte Carlo calculations. A broad family of fragmentation probabilities is considered, and its implications for the system kinetics are discussed. We show that generically these driven materials evolve asymptotically into a dynamical scaling regime. If the fragmentation probability tends to a constant, the grain number diverges at a finite time, leading to a shattering singularity. If the fragmentation probability vanishes, then the number of grains grows monotonously as a power law. We consider different homogeneous thermostats and show that the kinetics of these systems depends weakly on both the grain inelasticity and driving. We observe that fragmentation plays a relevant role in the shape of the velocity distribution of the particles. When the fragmentation is driven by local stochastic events, the long velocity tail is essentially exponential independently of the heating frequency and the breaking rule. However, for a Lowe-Andersen thermostat, numerical evidence strongly supports the conjecture that the scaled velocity distribution follows a generalized exponential behavior f(c) approximately exp(-cn) , with n approximately 1.2 , regarding less the fragmentation mechanisms.

  14. HIERARCHICAL FRAGMENTATION OF THE ORION MOLECULAR FILAMENTS

    SciTech Connect

    Takahashi, Satoko; Ho, Paul T. P.; Su, Yu-Nung; Teixeira, Paula S.; Zapata, Luis A.

    2013-01-20

    We present a high angular resolution map of the 850 {mu}m continuum emission of the Orion Molecular Cloud-3 (OMC 3) obtained with the Submillimeter Array (SMA); the map is a mosaic of 85 pointings covering an approximate area of 6.'5 Multiplication-Sign 2.'0 (0.88 Multiplication-Sign 0.27 pc). We detect 12 spatially resolved continuum sources, each with an H{sub 2} mass between 0.3-5.7 M {sub Sun} and a projected source size between 1400-8200 AU. All the detected sources are on the filamentary main ridge (n{sub H{sub 2}}{>=}10{sup 6} cm{sup -3}), and analysis based on the Jeans theorem suggests that they are most likely gravitationally unstable. Comparison of multi-wavelength data sets indicates that of the continuum sources, 6/12 (50%) are associated with molecular outflows, 8/12 (67%) are associated with infrared sources, and 3/12 (25%) are associated with ionized jets. The evolutionary status of these sources ranges from prestellar cores to protostar phase, confirming that OMC-3 is an active region with ongoing embedded star formation. We detect quasi-periodical separations between the OMC-3 sources of Almost-Equal-To 17''/0.035 pc. This spatial distribution is part of a large hierarchical structure that also includes fragmentation scales of giant molecular cloud ( Almost-Equal-To 35 pc), large-scale clumps ( Almost-Equal-To 1.3 pc), and small-scale clumps ( Almost-Equal-To 0.3 pc), suggesting that hierarchical fragmentation operates within the Orion A molecular cloud. The fragmentation spacings are roughly consistent with the thermal fragmentation length in large-scale clumps, while for small-scale cores it is smaller than the local fragmentation length. These smaller spacings observed with the SMA can be explained by either a helical magnetic field, cloud rotation, or/and global filament collapse. Finally, possible evidence for sequential fragmentation is suggested in the northern part of the OMC-3 filament.

  15. The effect of radiative feedback on disc fragmentation

    NASA Astrophysics Data System (ADS)

    Mercer, Anthony; Stamatellos, Dimitris

    2017-02-01

    Protostellar discs may become massive enough to fragment producing secondary low-mass objects: planets, brown dwarfs and low-mass stars. We study the effect of radiative feedback from such newly formed secondary objects using radiative hydrodynamic simulations. We compare the results of simulations without any radiative feedback from secondary objects with those where two types of radiative feedback are considered: (i) continuous and (ii) episodic. We find that (i) continuous radiative feedback stabilizes the disc and suppresses further fragmentation, reducing the number of secondary objects formed; (ii) episodic feedback from secondary objects heats and stabilizes the disc when the outburst occurs, but shortly after the outburst stops, the disc becomes unstable and fragments again. However, fewer secondary objects are formed compared to the case without radiative feedback. We also find that the mass growth of secondary objects is mildly suppressed due to the effect of their radiative feedback. However, their mass growth also depends on where they form in the disc and on their subsequent interactions, such that their final masses are not drastically different from the case without radiative feedback. We find that the masses of secondary objects formed by disc fragmentation are from a few MJ to a few 0.1 M⊙. Planets formed by fragmentation tend to be ejected from the disc. We conclude that planetary-mass objects on wide orbits (wide-orbit planets) are unlikely to form by disc fragmentation. Nevertheless, disc fragmentation may be a significant source of free-floating planets and brown dwarfs.

  16. Considerations in producing preferentially reduced half-antibody fragments.

    PubMed

    Makaraviciute, Asta; Jackson, Carolyn D; Millner, Paul A; Ramanaviciene, Almira

    2016-02-01

    Half-antibody fragments are a promising reagent for biosensing, drug-delivery and labeling applications, since exposure of the free thiol group in the Fc hinge region allows oriented reaction. Despite the structural variations among the molecules of different IgG subclasses and those obtained from different hosts, only generalized preferential antibody reduction protocols are currently available. Preferential reduction of polyclonal sheep anti-digoxin, rabbit anti-Escherichia coli and anti-myoglobin class IgG antibodies to half-antibody fragments has been investigated. A mild reductant 2-mercaptoethylamine (2-MEA) and a slightly stronger reductant tris(2-carboxyethyl)phosphine (TCEP) were used and the fragments obtained were quantitatively determined by SDS-PAGE analysis. It has been shown that the yields of half-antibody fragments could be increased by lowering the pH of the reduction mixtures. However, antibody susceptibility to the reductants varied. At pH4.5 the highest yield of sheep anti-digoxin IgG half-antibody fragments was obtained with 1M 2-MEA. Conversely, rabbit IgG half-antibody fragments could only be obtained with the stronger reductant TCEP. Preferential reduction of rabbit anti-myoglobin IgG antibodies was optimized and the highest half-antibody yield was obtained with 35 mM TCEP. Finally, it has been demonstrated that produced anti-myoglobin half-IgG fragments retained their binding activity.

  17. Depleted Uranium Test Range Fragment Reclamation

    DTIC Science & Technology

    1982-07-01

    fragment drying was necessary in order to obtain adequate vacuum levels in the VIR furnaces . e. Vacuujm Induction Remelting Fragments and Casting...Acid Pickle and Water Rinse .... ........ 2 d. Drying the Fragments .... ............... 2 e. Vacuum Induction Remelting Fragments and Casting...feasibility of reclaiming test range fragments by vacuum induction remelting (VIR). The technical direction of Phase 11 was highly dependent upon the

  18. Recovery of depleted uranium fragments from soil.

    PubMed

    Farr, C P; Alecksen, T J; Heronimus, R S; Simonds, M H; Farrar, D R; Miller, M L; Baker, K R

    2010-02-01

    A "proof of concept" was conducted to determine the effectiveness of a survey method for cost-effective recovery of depleted uranium (DU) fragments from contaminated soil piles at Sandia National Laboratories. First, DU fragments ranging from less than a gram up to 48 g were covered by various thicknesses of soil and used for detector efficiency measurements. The efficiencies were measured for three different sodium iodide detectors: a 5.1-cm by 5.1-cm (2-inch by 2-inch) detector, a 7.6-cm by 7.6-cm (3-inch by 3-inch) detector, and a Field Instrument for the Detection of Low Energy Radiation (FIDLER) detector. The FIDLER detector was found to be superior to the other detectors in each measurement. Next, multiple 7.6-cm (3-inch) layers of soil, taken from the contaminated piles, were applied to a clean pad of soil. Each layer was scanned by an array of eight FIDLER detectors pulled by a tractor. The array, moving 10.2 to 12.7 cm s(-1) (4 to 5 inches per second), automatically recorded radiation count data along with associated detector coordinates at 3-s intervals. The DU fragments were located and identified with a handheld system consisting of a FIDLER detector and a positioning system and then removed. After DU removal, the affected areas were re-scanned and a new lift of contaminated soil was applied. The detection capability of the system as a function of DU fragment mass and burial depth was modeled and determined to be sufficient to ensure that the dose-based site concentration goals would be met. Finally, confirmation soil samples were taken from random locations and from decontaminated soil areas. All samples had concentrations of U that met the goal of 400-500 pCi g(-1).

  19. Fragmentation of drying paint layers

    NASA Astrophysics Data System (ADS)

    Bakos, Katinka; Dombi, András; Járai-Szabó, Ferenc; Néda, Zoltán

    2013-11-01

    Fragmentation of thin layers of drying granular materials on a frictional surface are studied both by experiments and computer simulations. Besides a qualitative description of the fragmentation phenomenon, the dependence of the average fragment size as a function of the layer thickness is thoroughly investigated. Experiments are done using a special nail polish, which forms characteristic crack structures during drying. In order to control the layer thickness, we diluted the nail polish in acetone and evaporated in a controlled manner different volumes of this solution on glass surfaces. During the evaporation process we managed to get an instable paint layer, which formed cracks as it dried out. In order to understand the obtained structures a previously developed spring-block model was implemented in a three-dimensional version. The experimental and simulation results proved to be in excellent qualitative and quantitative agreement. An earlier suggested scaling relation between the average fragment size and the layer thickness is reconfirmed.

  20. A semiempirical nuclear fragmentation model

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Townsend, Lawrence W.; Badavi, F. F.

    1987-01-01

    An abrasion/ablation model of heavy ion fragmentation is derived which includes a second order correction for the surface energy term and provides a reasonable representation of the present elemental fragmentation cross sections. The full development of the model must await the resolution of disagreement among different experiments and an expansion of the experimental data base to a broader set of projectile-target combinations.

  1. High Fragmentation Steel Production Process

    DTIC Science & Technology

    1984-01-01

    phase of the project entailed the purchase and metallurgical characterization of two heats of HF-1 steel from different vendors. Performed by...At>-A 13^ nzt AD AD-E401 117 CONTRACTOR REPORT ARLCD-CR-83049 HIGH FRAGMENTATION STEEL PRODUCTION PROCESS ^"fP-PTTMirj A 1 James F. Kane...Report 6. PERFORMING ORG. REPORT NUMBER High Fragmentation Steel Production Process 7. AUTHORfs; James F. Kane, Ronald L. Kivak, Colin C. MacCrindle

  2. QGP and Modified Jet Fragmentation

    SciTech Connect

    Wang, Xin-Nian

    2005-04-18

    Recent progresses in the study of jet modification in hotmedium and their consequences in high-energy heavy-ion collisions are reviewed. In particular, I will discuss energy loss for propagating heavy quarks and the resulting modified fragmentation function. Medium modification of the parton fragmentation function due to quark recombination are formulated within finite temperature field theory and their implication on the search for deconfined quark-gluon plasma is also discussed.

  3. Jet mass dependence of fragmentation in positron-proton collisions

    NASA Astrophysics Data System (ADS)

    Urmossy, K.

    2017-02-01

    We propose the characterization of fragmentation functions by the energy fraction tilde{x} a hadron takes away from the energy of the jet measured in the frame co-moving with the jet. Besides, we propose the usage of the jet mass as the fragmentation scale tilde{Q}. We show that these two Lorentz-invariant variables emerge naturally in a microcanonical ensemble with conserved four-momentum. Then, we construct a statistical hadronisation model, in which, two features of the hadronic final states in various high-energy reactions (power law spectra and negative-binomial multiplicity distributions) can be connected simply. Finally, we analyse the scale dependence of the parameters of the model (power of the spectrum and mean energy per hadron) in the φ3 theory. Fitting fragmentation functions in diffractive positron-proton collisions, we obtain a prediction for the jet mass dependence of the hadron multiplicity distribution inside jets.

  4. Particle size statistics in dynamic fragmentation

    SciTech Connect

    Grady, D.E. )

    1990-12-15

    Condensed matter, when subjected to intense disrupting forces through impact or radiation deposition, will break up into a randomly distributed array of fragments. An earlier analysis of random fragmentation is extended to account for fragmentation in bodies which are finite in extent and for bodies within which the minimum fragment size is bounded. The statistical fragment size relations are compared with molecular dynamic simulations of dynamic fragmentation, with fragmentation caused by the high-energy collision of nuclear particles, and with the distribution of galaxies in the universe which are assumed to be fragment debris from the primordial Big Bang.

  5. Fragmentation and ablation during entry

    SciTech Connect

    Canavan, G.H.

    1997-09-01

    This note discusses objects that both fragment and ablate during entry, using the results of previous reports to describe the velocity, pressure, and fragmentation of entering objects. It shows that the mechanisms used there to describe the breakup of non-ablating objects during deceleration remain valid for most ablating objects. It treats coupled fragmentation and ablation during entry, building on earlier models that separately discuss the entry of objects that are hard, whose high heat of ablation permits little erosion, and those who are strong whose strength prevents fragmentation, which are discussed in ``Radiation from Hard Objects,`` ``Deceleration and Radiation of Strong, Hard, Asteroids During Atmospheric Impact,`` and ``Meteor Signature Interpretation.`` This note provides a more detailed treatment of the further breakup and separation of fragments during descent. It replaces the constraint on mass per unit area used earlier to determine the altitude and magnitude of peak power radiation with a detailed analytic solution of deceleration. Model predictions are shown to be in agreement with the key features of numerical calculations of deceleration. The model equations are solved for the altitudes of maximum radiation, which agree with numerical integrations. The model is inverted analytically to infer object size and speed from measurements of peak power and altitude to provide a complete model for the approximate inversion of meteor data.

  6. Fragmentation of DNA by sonication.

    PubMed

    Sambrook, Joseph; Russell, David W

    2006-09-01

    INTRODUCTIONDNA fragmentation is often necessary prior to library construction or subcloning for DNA sequencing. This protocol describes a method for DNA fragmentation by sonication. During sonication, DNA samples are subjected to hydrodynamic shearing by exposure to brief periods of sonication. DNA that has been sonicated for excessive periods of time is extremely difficult to clone. Most sonicators will not shear DNA to a size of less than 300-500 bp, and it is tempting to continue sonication until the entire DNA population has been reduced in size. However, the yield of subclones is usually greater if sonication is stopped when the fragments of the target DNA first reach a size of ~700 bp.

  7. Considerations of Protein Subpockets in Fragment-Based Drug Design.

    PubMed

    Bartolowits, Matthew; Davisson, V Jo

    2016-01-01

    While the fragment-based drug design approach continues to gain importance, gaps in the tools and methods available in the identification and accurate utilization of protein subpockets have limited the scope. The importance of these features of small molecule-protein recognition is highlighted with several examples. A generalized solution for the identification of subpockets and corresponding chemical fragments remains elusive, but there are numerous advancements in methods that can be used in combination to address subpockets. Finally, additional examples of approaches that consider the relative importance of small-molecule co-dependence of protein conformations are highlighted to emphasize an increased significance of subpockets, especially at protein interfaces.

  8. A thermodynamic theory of dynamic fragmentation

    SciTech Connect

    Yew, Ching H.; Taylor, P.A.

    1993-08-01

    We present a theory of dynamic fragmentation of brittle materials based on thermodynamic arguments. We recover the expressions for average fragment size and number as originally derived by Grady. We extend the previous work by obtaining descriptions of fragment size distribution and compressibility change due to the fragmentation process. The size distribution is assumed to be proportional to the spectral power of the strain history and a sample distribution is presented for a fragmentation process corresponding to a constant rate strain history. The description of compressibility change should be useful in computational studies of fragmentation. These results should provide insight into the process of fragmentation of brittle materials from hypervelocity impact.

  9. The Fragmentation of Literary Theory

    ERIC Educational Resources Information Center

    Howard, Jennifer

    2005-01-01

    Syllabi from some 20 colleges and universities were reviewed with prominent English and literature departments and a discussion was held with a number of professors who teach literary theory. It is suggested that devolution and fragmentation of theory might be a survival strategy, an adaptation to the new realties of academic institutions.

  10. Percolative fragmentation and spontaneous agglomeration

    SciTech Connect

    Hurt, R.; Davis, K.

    1999-03-01

    Captive particle imaging experiments were performed on over 200 coal and char particles in the pulverized size range from four coals of various rank at oxygen concentration from 3--19 mol% and at gas temperatures of about 1250 K. Despite wide variations in single-particle behavior, the data set reveals two clear trends that provide new information on the nature of char combustion. First, the low-rank coal chars are observed to maintain their high reactivity through the late stages of combustion, thus avoiding the near-extinction events and long burnout tails observed for bituminous coal chars. Secondly, percolative fragmentation in the late stages of combustion is a rare event under these conditions. Some particles reach a percolation threshold rate in combustion, but typically undergo spontaneous agglomeration rather than liberation of the incipient fragments. It is concluded that percolative fragmentation behavior in the pulverized size range is determined not only by solid-phase connectivity, but also by a real competition between disruptive and cohesive forces present at the time of formation of the colloidal-sized incipient fragments.

  11. Controlled Dynamic Fragmentation of Ceramics

    DTIC Science & Technology

    2009-12-14

    mechanism determining ballistic impact performance of ceramic armors as well as reliability of gun barrels. This program, which was sponsored by the...Research Office Fragmentation is a key damage mechanism determining ballistic impact performance of ceramic armors as well as reliability of gun ...the defect distributions that were considered (Weibull, Gauss and Uniform) fall on a single universal curve. Sdf

  12. Nuclear energy release from fragmentation

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Souza, S. R.; Tsang, M. B.; Zhang, Feng-Shou

    2016-08-01

    It is well known that binary fission occurs with positive energy gain. In this article we examine the energetics of splitting uranium and thorium isotopes into various numbers of fragments (from two to eight) with nearly equal size. We find that the energy released by splitting 230,232Th and 235,238U into three equal size fragments is largest. The statistical multifragmentation model (SMM) is applied to calculate the probability of different breakup channels for excited nuclei. By weighing the probability distributions of fragment multiplicity at different excitation energies, we find the peaks of energy release for 230,232Th and 235,238U are around 0.7-0.75 MeV/u at excitation energy between 1.2 and 2 MeV/u in the primary breakup process. Taking into account the secondary de-excitation processes of primary fragments with the GEMINI code, these energy peaks fall to about 0.45 MeV/u.

  13. Fission fragment driven neutron source

    DOEpatents

    Miller, Lowell G.; Young, Robert C.; Brugger, Robert M.

    1976-01-01

    Fissionable uranium formed into a foil is bombarded with thermal neutrons in the presence of deuterium-tritium gas. The resulting fission fragments impart energy to accelerate deuterium and tritium particles which in turn provide approximately 14 MeV neutrons by the reactions t(d,n).sup.4 He and d(t,n).sup.4 He.

  14. A Stab in the Dark?

    PubMed Central

    Tompson, Lisa

    2013-01-01

    Objectives: Test the influence of darkness in the street robbery crime event alongside temperature. Methods: Negative binomial regression models tested darkness and temperature as predictors of street robbery. Units of analysis were four 6-hr time intervals in two U.K. study areas that have different levels of darkness and variations of temperature throughout the year. Results: Darkness is a key factor related to robbery events in both study areas. Traversing from full daylight to full darkness increased the predicted volume of robbery by a multiple of 2.6 in London and 1.2 in Glasgow. Temperature was significant only in the London study area. Interaction terms did not enhance the predictive power of the models. Conclusion: Darkness is an important driving factor in seasonal variation of street robbery. A further implication of the research is that time of the day patterns are crucial to understanding seasonal trends in crime data. PMID:25076797

  15. Stabbing simulations and DNA transfer.

    PubMed

    Samie, Lydie; Hicks, Tacha; Castella, Vincent; Taroni, Franco

    2016-05-01

    Technical developments have made it possible to analyze very low amounts of DNA. This has many advantages, but the drawback of this technological progress is that interpretation of the results becomes increasingly complex: the number of mixed DNA profiles increased relatively to single source DNA profiles and stochastic effects in the DNA profile, such as drop-in and drop-out, are more frequently observed. Moreover, the relevance of low template DNA material regarding the activities alleged is not as straightforward as it was a few years ago, when for example large quantities of blood were recovered. The possibility of secondary and tertiary transfer is now becoming an issue. The purpose of this research is twofold: first, to study the transfer of DNA from the handler and secondly, to observe if handlers would transfer DNA from persons closely connected to them. We chose to mimic cases where the offender would attack a person with a knife. As a first approach, we envisaged that the defense would not give an alternative explanation for the origin of the DNA. In our transfer experiments (4 donors, 16 experiments each, 64 traces), 3% of the traces were single DNA profiles. Most of the time, the DNA profile of the person handling the knife was present as the major profile: in 83% of the traces the major contributor profile corresponded to the stabber's DNA profile (in single stains and mixtures). Mixture with no clear major/minor fraction (12%) were observed. 5% of the traces were considered of insufficient quality (more than 3 contributors, presence of a few minor peaks). In that case, we considered that the stabber's DNA was absent. In our experiments, no traces allowed excluding the stabber, however it must be noted that precautions were taken to minimize background DNA as knives were cleaned before the experiments. DNA profiles of the stabber's colleagues were not observed. We hope that this study will allow for a better understanding of the transfer mechanism and of how to assess and describe results given activity level propositions. In this preliminary research, we have focused on the transfer of DNA on the hand of the person. Besides, more research is needed to assign the probability of the results given an alternative activity proposed by the defense, for instance when the source of the DNA is not contested, but that the activities are.

  16. Experimental Volcanology: Fragmentation and Permeability

    NASA Astrophysics Data System (ADS)

    Spieler, O.

    2005-12-01

    An increasing number of scientists design new experiments to analyse processes that control the dynamics of explosive eruptions. There research is mostly coupled to numerical models and aims toward its controlling parameters. The fragmentation process, its threshold and the speed of the fragmentation wave as well as the energy consumed by the fragmentation are some hot spots of the experimental volcanology. Analysing the fragmentation behaviour of volcaniclastics as close to the natural system as possible, we found a number of physical constrains. Identifying the porosity as determining factor of the threshold, we realised that neither threshold nor the speed of the fragmentation process are solely controlled by the rock density. The later results of the shock tube type apparatus lead to the analysis of the specific surface area and permeability as direct links to textural features. Permeability analysis performed in a modified shock tube type apparatus, show two clear, distinct trends for dome rock and pyroclastic samples. The specific surface determined by Argon sorbtion (BET) as well as textural features of pumices from Campi Flegrei, Montserrat and Krakatoa (1883) give in contrary evidence of a more complex story. Large spherical, or ellipsoidal bubbles around fractured crystals prove that the high permeability of the pumice has partially developed after the fixing of the bubble size distribution. This puts up the question, if permeability measurements on pyroclastic samples reveal relevant numbers! The surface tension controlled 'self sealing' behaviour of surfaces from foaming obsidian hinders in situ measurements. Close textural investigations will have to clarify how the 'post process' samples deviate from the syneruptive conduit filling.

  17. Fragments

    ERIC Educational Resources Information Center

    Moreira, Claudio

    2008-01-01

    This performance autoethnography shows the author's struggle in finding his place, scholarship, voice, and body, into the academic setting. Mixing together memories of his lived experience with sugar cane workers, notes, and leftovers of different fieldworks, plus 6 years of life as grad student at the University of Illinois, the author looks for…

  18. DNA fragment editing of genomes by CRISPR/Cas9.

    PubMed

    Jinhuan, Li; Jia, Shou; Qiang, Wu

    2015-10-01

    The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease 9 (Cas9) system from bacteria and archaea emerged recently as a new powerful technology of genome editing in virtually any organism. Due to its simplicity and cost effectiveness, a revolutionary change of genetics has occurred. Here, we summarize the recent development of DNA fragment editing methods by CRISPR/Cas9 and describe targeted DNA fragment deletions, inversions, duplications, insertions, and translocations. The efficient method of DNA fragment editing provides a powerful tool for studying gene function, regulatory elements, tissue development, and disease progression. Finally, we discuss the prospects of CRISPR/Cas9 system and the potential applications of other types of CRISPR system.

  19. Contribution of rock fragments to soil fertility

    NASA Astrophysics Data System (ADS)

    Korboulewsky, Nathalie; Besnault, Adeline; Tétégan, Marion; Cousin, Isabelle

    2010-05-01

    other types. Indeed limestones, compared to chert and flint, contained 20 times higher exchangeable Ca (2.3 g Ca/kg for limestones compared to 0.08 and 0.03 g Ca/kg for chert and flint) and 7 to 10 times higher Mg (19.3g Mg/kg for limestones compared to 2.7 and 1.7 g Mg/kg for chert and flint). Potassium showed a completely different trend with the highest exchangeable K found for chert and marly limestone, intermediate levels for lithographic limestone and flint, and lowest levels for oolitic limestone. In addition, whatever the pebble origin, calcium was the element the most released. Limestones released more Mg than K, and chert and flint more K than Mg. Further, released exchangeable Ca and Mg were closely related to the dry mass of pebbles, but exchangeable K was not. As mentioned above, much more cations were extracted from limestones compared to chert and flint. Besides, chert released twice as much as flint for the three cations. Finally, the fertilisation potential of these pebbles and especially limestones is far to be negligible. For instance, the exchangeable Ca, Mg and K released from lithographic pebbles represent respectively about 50%, 20% and 10% of those released from the surrounding fine earth. These results confirm the potential contribution of rock fragments to soil fertility. Furthermore, important differences in exchangeable cations in relation to their origin were measured. Further analyses are being carried out on pebbles from other origins and on available phosphorus. We believe that this work is a first step towards a better understanding of the role of rock fragments in plant-soil relationships.

  20. Evolution of Particle Size Distributions in Fragmentation Over Time

    NASA Astrophysics Data System (ADS)

    Charalambous, C. A.; Pike, W. T.

    2013-12-01

    We present a new model of fragmentation based on a probabilistic calculation of the repeated fracture of a particle population. The resulting continuous solution, which is in closed form, gives the evolution of fragmentation products from an initial block, through a scale-invariant power-law relationship to a final comminuted powder. Models for the fragmentation of particles have been developed separately in mainly two different disciplines: the continuous integro-differential equations of batch mineral grinding (Reid, 1965) and the fractal analysis of geophysics (Turcotte, 1986) based on a discrete model with a single probability of fracture. The first gives a time-dependent development of the particle-size distribution, but has resisted a closed-form solution, while the latter leads to the scale-invariant power laws, but with no time dependence. Bird (2009) recently introduced a bridge between these two approaches with a step-wise iterative calculation of the fragmentation products. The development of the particle-size distribution occurs with discrete steps: during each fragmentation event, the particles will repeatedly fracture probabilistically, cascading down the length scales to a final size distribution reached after all particles have failed to further fragment. We have identified this process as the equivalent to a sequence of trials for each particle with a fixed probability of fragmentation. Although the resulting distribution is discrete, it can be reformulated as a continuous distribution in maturity over time and particle size. In our model, Turcotte's power-law distribution emerges at a unique maturation index that defines a regime boundary. Up to this index, the fragmentation is in an erosional regime with the initial particle size setting the scaling. Fragmentation beyond this index is in a regime of comminution with rebreakage of the particles down to the size limit of fracture. The maturation index can increment continuously, for example under

  1. Analytical and experimental evaluation of a proposed self-forging fragment munition

    SciTech Connect

    Tuft, D.B.; Folsom, E.N.

    1982-12-27

    Analytical and experimental tools have been used to study the formation of a proposed self-forging fragment projectile. The primary objective of this study is the determination of the interior and exterior shape of the fully formed fragment, and to determine if the fragment tumbles in flight. In addition, it is of interest to compare computer predictions to experimental results. An experiment was performed using high speed photography and high-energy flash x-ray radiography to study liner and case motion and projectile formation. Fabrication and assembly tolerances were closely controlled in an effort to eliminate tolerances as a possible source of fragment instability. X-ray film-density contours were analyzed to determine the fully formed fragment interior and exterior shape. Down-range yaw screens showed fragment tumbling in flight. The computed fragment shape was compared to experimental results and it was found that a retaining ring in the computational model near the liner periphery had a significant effect on the final computed fragment shape. With the retaining ring in the computational model and full two-way sliding between all material interfaces, the final computed fragment showed very good agreement with the experiment on both exterior and interior shapes.

  2. Relativistic heavy ion fragmentation at HISS (Heavy Ion Spectrometer System)

    SciTech Connect

    Tull, C.E.

    1990-10-01

    An experiment was conducted at the Lawrence Berkeley Laboratory to measure projectile fragmentation of relativistic heavy ions. Charge identification was obtained by the use of a Cerenkov Hodoscope operating above the threshold for total internal reflection, while velocity measurement was performed by use of a second set of Cerenkov radiators operating at the threshold for total internal reflection. Charge and mass resolution for the system was {sigma}{sub Z} = 0.2 e and {sigma}{sub A} = 0.2 u. Measurements of the elemental and isotopic production cross sections for the fragmentation of {sup 40}Ar at 1.65{center dot}A GeV have been compared with an Abrasion-Ablation Model based on the evaporation computer code GEMINI. The model proves to be an accurate predictor of the cross sections for fragments between Chlorine and Boron. The measured cross section were reproduced using simple geometry with charge dispersions induced by zero-point vibrations of the giant dipole resonance for the prompt abrasion stage, and injecting an excitation energy spectrum based on a final state interaction with scaling factor E{sub fsi} = 38.8 MeV/c. Measurement of the longitudinal momentum distribution widths for projectile fragments are consistent with previous experiment and can be interpreted as reflecting the Fermi momentum distribution in the initial projectile nucleus. Measurement of the transverse momentum indicate an additional, unexplained dependence of the reduced momentum widths on fragment mass. This dependence has the same sign and similar slope to previously measured fragments of {sup 139}La, and to predictions based on phase-space constraints on the final state of the system.

  3. Detecting Fragmentation Extinction Thresholds for Forest Understory Plant Species in Peninsular Spain

    PubMed Central

    Rueda, Marta; Moreno Saiz, Juan Carlos; Morales-Castilla, Ignacio; Albuquerque, Fabio S.; Ferrero, Mila; Rodríguez, Miguel Á.

    2015-01-01

    Ecological theory predicts that fragmentation aggravates the effects of habitat loss, yet empirical results show mixed evidences, which fail to support the theory instead reinforcing the primary importance of habitat loss. Fragmentation hypotheses have received much attention due to their potential implications for biodiversity conservation, however, animal studies have traditionally been their main focus. Here we assess variation in species sensitivity to forest amount and fragmentation and evaluate if fragmentation is related to extinction thresholds in forest understory herbs and ferns. Our expectation was that forest herbs would be more sensitive to fragmentation than ferns due to their lower dispersal capabilities. Using forest cover percentage and the proportion of this percentage occurring in the largest patch within UTM cells of 10-km resolution covering Peninsular Spain, we partitioned the effects of forest amount versus fragmentation and applied logistic regression to model occurrences of 16 species. For nine models showing robustness according to a set of quality criteria we subsequently defined two empirical fragmentation scenarios, minimum and maximum, and quantified species’ sensitivity to forest contraction with no fragmentation, and to fragmentation under constant forest cover. We finally assessed how the extinction threshold of each species (the habitat amount below which it cannot persist) varies under no and maximum fragmentation. Consistent with their preference for forest habitats probability occurrences of all species decreased as forest cover contracted. On average, herbs did not show significant sensitivity to fragmentation whereas ferns were favored. In line with theory, fragmentation yielded higher extinction thresholds for two species. For the remaining species, fragmentation had either positive or non-significant effects. We interpret these differences as reflecting species-specific traits and conclude that although forest amount is of

  4. Detecting fragmentation extinction thresholds for forest understory plant species in peninsular Spain.

    PubMed

    Rueda, Marta; Moreno Saiz, Juan Carlos; Morales-Castilla, Ignacio; Albuquerque, Fabio S; Ferrero, Mila; Rodríguez, Miguel Á

    2015-01-01

    Ecological theory predicts that fragmentation aggravates the effects of habitat loss, yet empirical results show mixed evidences, which fail to support the theory instead reinforcing the primary importance of habitat loss. Fragmentation hypotheses have received much attention due to their potential implications for biodiversity conservation, however, animal studies have traditionally been their main focus. Here we assess variation in species sensitivity to forest amount and fragmentation and evaluate if fragmentation is related to extinction thresholds in forest understory herbs and ferns. Our expectation was that forest herbs would be more sensitive to fragmentation than ferns due to their lower dispersal capabilities. Using forest cover percentage and the proportion of this percentage occurring in the largest patch within UTM cells of 10-km resolution covering Peninsular Spain, we partitioned the effects of forest amount versus fragmentation and applied logistic regression to model occurrences of 16 species. For nine models showing robustness according to a set of quality criteria we subsequently defined two empirical fragmentation scenarios, minimum and maximum, and quantified species' sensitivity to forest contraction with no fragmentation, and to fragmentation under constant forest cover. We finally assessed how the extinction threshold of each species (the habitat amount below which it cannot persist) varies under no and maximum fragmentation. Consistent with their preference for forest habitats probability occurrences of all species decreased as forest cover contracted. On average, herbs did not show significant sensitivity to fragmentation whereas ferns were favored. In line with theory, fragmentation yielded higher extinction thresholds for two species. For the remaining species, fragmentation had either positive or non-significant effects. We interpret these differences as reflecting species-specific traits and conclude that although forest amount is of

  5. An Enumerative Combinatorics Model for Fragmentation Patterns in RNA Sequencing Provides Insights into Nonuniformity of the Expected Fragment Starting-Point and Coverage Profile

    PubMed Central

    Haeseler, Arndt Von

    2017-01-01

    Abstract RNA sequencing (RNA-seq) has emerged as the method of choice for measuring the expression of RNAs in a given cell population. In most RNA-seq technologies, sequencing the full length of RNA molecules requires fragmentation into smaller pieces. Unfortunately, the issue of nonuniform sequencing coverage across a genomic feature has been a concern in RNA-seq and is attributed to biases for certain fragments in RNA-seq library preparation and sequencing. To investigate the expected coverage obtained from fragmentation, we develop a simple fragmentation model that is independent of bias from the experimental method and is not specific to the transcript sequence. Essentially, we enumerate all configurations for maximal placement of a given fragment length, F, on transcript length, T, to represent every possible fragmentation pattern, from which we compute the expected coverage profile across a transcript. We extend this model to incorporate general empirical attributes such as read length, fragment length distribution, and number of molecules of the transcript. We further introduce the fragment starting-point, fragment coverage, and read coverage profiles. We find that the expected profiles are not uniform and that factors such as fragment length to transcript length ratio, read length to fragment length ratio, fragment length distribution, and number of molecules influence the variability of coverage across a transcript. Finally, we explore a potential application of the model where, with simulations, we show that it is possible to correctly estimate the transcript copy number for any transcript in the RNA-seq experiment. PMID:27661099

  6. Energy production using fission fragment rockets

    SciTech Connect

    Chapline, G.; Matsuda, Y.

    1991-08-01

    Fission fragment rockets are nuclear reactors with a core consisting of thin fibers in a vacuum, and which use magnetic fields to extract the fission fragments from the reactor core. As an alternative to ordinary nuclear reactors, fission fragment rockets would have the following advantages: Approximately twice as efficient if one can directly convert the fission fragment energy into electricity; by reducing the buildup of a fission fragment inventory in the reactor one could avoid a Chernobyl type disaster; and collecting the fission fragments outside the reactor could simplify the waste disposal problem. 6 refs., 4 figs., 2 tabs.

  7. Fragmentation of suddenly heated liquids

    SciTech Connect

    Blink, J.A.

    1985-03-01

    Fragmentation of free liquids in Inertial Confinement Fusion reactors could determine the upper bound on reactor pulse rate. The x-ray ablated materials must cool and recondense to allow driver beam propagation. The increased surface area caused by fragmentation will enhance the cooling and condensation rates. Relaxation from the suddenly heated state will move a liquid into the negative pressure region under the liquid-vapor P-V dome. The lithium equation of state was used to demonstrate that neutron-induced vaporization uses only a minor fraction of the added heat, much less than would be required to drive the expansion. A 77% expansion of the lithium is required before the rapid vaporization process of spinodal decomposition could begin, and nucleation and growth are too slow to contribute to the expansion.

  8. Asymmetry effects in fragment production

    NASA Astrophysics Data System (ADS)

    Kaur, Manpreet; Kaur, Varinderjit

    2016-05-01

    The production of different fragments has been studied by taking into account the mass asymmetry of the reaction and employing the momentum dependent interactions. Two different set of asymmetric reactions have been analyzed while keeping Atotal fixed using soft momentum dependent equation of state. Our results indicate that the impact of momentum dependent interactions is different in lighter projectile systems as compared to heavier ones. The comparative analysis of IQMD simulations with the experimental data in case of heavier projectile and lighter target system for the reaction of 197Au+27Al (η = 0.7) at E = 600 MeV/nucleon shows that with the inclusion of MDI we are able, upto some extent, to reproduce the experimental universality of rise and fall of intermediate mass fragments (IMFs).

  9. Golgi fragmentation in Alzheimer's disease

    PubMed Central

    Joshi, Gunjan; Bekier, Michael E.; Wang, Yanzhuang

    2015-01-01

    The Golgi apparatus is an essential cellular organelle for post-translational modifications, sorting, and trafficking of membrane and secretory proteins. Proper functionality of the Golgi requires the formation of its unique cisternal-stacking morphology. The Golgi structure is disrupted in a variety of neurodegenerative diseases, suggesting a common mechanism and contribution of Golgi defects in neurodegenerative disorders. A recent study on Alzheimer's disease (AD) revealed that phosphorylation of the Golgi stacking protein GRASP65 disrupts its function in Golgi structure formation, resulting in Golgi fragmentation. Inhibiting GRASP65 phosphorylation restores the Golgi morphology from Aβ-induced fragmentation and reduces Aβ production. Perturbing Golgi structure and function in neurons may directly impact trafficking, processing, and sorting of a variety of proteins essential for synaptic and dendritic integrity. Therefore, Golgi defects may ultimately promote the development of AD. In the current review, we focus on the cellular impact of impaired Golgi morphology and its potential relationship to AD disease development. PMID:26441511

  10. Petrology of some lithic fragments from Luna 20

    USGS Publications Warehouse

    Roedder, E.; Weiblen, P.W.

    1973-01-01

    Microscopic and electron microprobe studies were made of polished thin sections of part of a 30-mg sample of 250-500 ??m lunar soil returned by Luna 20 from a point between Mare Fecunditatis and Mare Crisium. Very fine-grained lithic (crystalline) rock fragments, composing about one fifth of the total sample, have mineralogical compositions equivalent to various types of gabbro, anorthositic gabbro, gabbroic anorthosite and troctolite, with minor basalt. The textures now observed in these fragments are in large part metamorphic. Twentyseven electron microprobe analyses of minerals from these fragments are presented, including olivine, plagioclase, pyroxene, spinel, nickel-iron and a Zr-Ti-REE mineral possibly similar to 'phase B' of Lovering and Wark (1971). Analyses of seven melt inclusions and twenty-eight defocused beam analyses of lithic fragments are also given. Some of the fragments contain 'gas' inclusions which, along with the fine grain size, are believed to indicate final crystallization under low pressure near surface conditions. The almost complete absence of granophyric material in this sample raises the question of whether or not there are at least two distinct magmas for the plagioclase-rich terrae rocks from which this soil sample was derived in part. ?? 1973.

  11. Modeling of Fragmentation of Asteroids

    NASA Technical Reports Server (NTRS)

    Agrawal, Parul; Prabhu, Dinesh K.; Carlozzi, Alexander; Hart, Kenneth; Bryson, Katie; Sears, Derek

    2015-01-01

    The objective of this study is to understand fragmentation and fracture of a given asteroid and mechanisms of break-up. The focus of the present work is to develop modeling techniques for stony asteroids in 10m-100m range to answer two questions: 1) What is the role of material makeup of an asteroid in the stress distribution? 2)How is stress distribution altered in the presence of pre-existing defects?

  12. Fragment Penetration Tests of Armor

    DTIC Science & Technology

    1983-03-15

    Identify by block numbhr) Provides techniques for evaluating armor resistance to attack by HE projectile fragments. Includes static detonations of shell...DISTRIBUTION D. REFERENCES * . . . ........ . ........... D-1 1. SCOPE. This TOP describes the available techniques for testing armor for resistance to attack by...Projectiles Against Armor Plates ("Yankee Stadium" Test-). 4.1.1 hCjective. The objective is to determine the resistance to penetration of various armor

  13. Fragmentation: Is the message clear?

    USGS Publications Warehouse

    Bissonette, J.A.; Storch, Ilse

    2002-01-01

    In this paper, we briefly discuss some of the fundamental problems arising from the inherent complexity of larger-scale ecological systems. We examine the tenuous assumption of a direct correspondence between ecological data and theory, we comment on a recent report that evaluated the efficacy of fragmentation experiments, and we briefly assess its implications for ecological research and conservation practice on the landscape scale. Copyright ?? 2002 by the author(s). Published here under licence by The Resilience Alliance.

  14. The fragmentation of Kosmos 2163

    NASA Technical Reports Server (NTRS)

    1992-01-01

    On 6 Dec. 1991 Kosmos 2163, a maneuverable Soviet spacecraft which had been in orbit for 58 days, experienced a major breakup at an altitude of approximately 210 km. Although numerous pieces of debris were created, the fragments decayed rapidly leaving no long-term impact on the near-Earth environment. The assessed cause of the event is the deliberate detonation of an explosive device. Details of this event are presented.

  15. Local Morphological Response of the Distal Femoral Articular–Epiphyseal Cartilage Complex of Young Foals to Surgical Stab Incision and Potential Relevance to Cartilage Injury and Repair in Children

    PubMed Central

    Hendrickson, Eli H.S.; Ekman, Stina; Carlson, Cathy S.; Dolvik, Nils I.

    2013-01-01

    Objective: Describe the local morphological response of the articular–epiphyseal cartilage complex to surgical stab incision in the distal femur of foals, with emphasis on the relationship between growth cartilage injury, enchondral ossification, and repair. Design: Nine foals were induced into general anesthesia at the age of 13 to 15 days. Four full-thickness stab incision defects were created in the cartilage on the lateral aspect of the lateral trochlear ridge of the left distal femur. Follow-up examination was carried out from 1 to 49 days postoperatively, including examination of intact bones, sawed slabs, and histological sections. Results: Incision defects filled with cells displaying fibroblast-, chondrocyte-, and osteoblast-like characteristics, potentially validating the rationale behind the drilling of stable juvenile osteochondritis dissecans lesions in children. Incisions induced necrosis within the cartilage on the margins at all depths of the defects. Sharp dissection may therefore be contraindicated in cartilage repair in young individuals. Incisions caused a focal delay in enchondral ossification in 2 foals, apparently related to the orientation of the incision defect relative to the direction of ossification. Defects became progressively surrounded by subchondral bone, in which granulation tissue containing clasts and foci of osteoblast-like cells was observed. Continued enchondral ossification was therefore likely to result in healing of uncomplicated defects to morphologically normal bone. Conclusions: Epiphyseal growth cartilage injury had the potential to exert a negative effect on enchondral ossification. Enchondral ossification exerted a beneficial effect on repair. This relationship warrants consideration in future studies of cartilage injury and repair within the articular–epiphyseal cartilage complex of all species. PMID:26069670

  16. Fragmentation in Science and in Society

    ERIC Educational Resources Information Center

    Bohm, David

    1971-01-01

    Fragmentation" is a general social condition. The author presents a case for wholeness and its dynamic, cyclic character. Science and society need not be fragmented. They should be considered part of a holocyclation." (LS)

  17. Evaluating Fragment Construction Policies for SDT Systems

    DTIC Science & Technology

    2006-01-01

    allocates a fragment and begins translation. Once a termination condition is met, Strata emits any trampolines that are necessary. Trampolines are pieces... trampolines (unless its target previously exists in the fragment cache). Once a CTI’s target instruction becomes available in the fragment cache, the CTI is...linked directly to the destination, avoiding future uses of the trampoline . This mechanism is called Fragment Linking and avoids significant overhead

  18. Comparison of calculations of fragment production

    SciTech Connect

    Canavan, G.H.

    1998-01-01

    This note compares estimates of fragment production rates in debris collisions through calculations performed with consistent debris distribution functions implicit in integrated collision frequencies provided by Attachment A. Differences between estimates of fragment production rates in space debris collisions are shown to be due primarily to different choices of the exponent in the fragment production function and the distinction between catastrophic and all collisions. Sensitivity to the fragment production parameter over the range of values consistent with experimental data is discussed.

  19. Fragmentation of cosmic-string loops

    NASA Technical Reports Server (NTRS)

    York, Thomas

    1989-01-01

    The fragmentation of cosmic string loops is discussed, and the results of a simulation of this process are presented. The simulation can evolve any of a large class of loops essentially exactly, including allowing fragments that collide to join together. Such reconnection enhances the production of small fragments, but not drastically. With or without reconnections, the fragmentation process produces a collection of nonself-intersecting loops whose typical length is on the order of the persistence length of the initial loop.

  20. Plumes, orogenesis, and supercontinental fragmentation

    NASA Astrophysics Data System (ADS)

    Dalziel, I. W. D.; Lawver, L. A.; Murphy, J. B.

    2000-05-01

    A time-space relationship between large igneous provinces (LIPS), present day hot spots, and the fragmentation of Pangea has been documented over several decades, but the cause of fragmentation has remained elusive. LIPS are regarded either as the result of impingement of a mantle plume on the base of the lithosphere, or as the initial products of adiabatic decompression melting of anomalously hot mantle. Do LIPS therefore constitute evidence of an active role for plumes from the deep mantle in supercontinental fragmentation, or are they merely the first indications of a large-scale but near-surface tectonic process? Two long recognized and enigmatic orogenic events may offer a solution to this geologically important 'chicken or egg' conundrum. The reconstructed early Mesozoic Gondwanide fold belt of South America, southern Africa, and Antarctica, could have resulted from 'plume-modified orogeny', flattening of a downgoing lithospheric slab due to the buoyancy of a plume rising beneath a continental margin subduction zone. If so, the ˜180 Ma Karroo and Ferrar LIPS associated with the opening of the ocean basin between East and West Gondwanaland at ˜165 Ma resulted from impingement of this plume and are unrelated to the thermal insulation of the shallow mantle beneath Gondwanaland. It would then follow that the plume itself played an active, possibly critical, role in the initial breakup of the supercontinent. The Late Paleozoic 'Ancestral Rockies' deformation in the southwestern United States could be yet another example of orogeny driven by a plume that initiated the break-up of Pangea approximately 15 Myr earlier in the Central Atlantic region.

  1. Fission fragment excited laser system

    DOEpatents

    McArthur, David A.; Tollefsrud, Philip B.

    1976-01-01

    A laser system and method for exciting lasing action in a molecular gas lasing medium which includes cooling the lasing medium to a temperature below about 150 K and injecting fission fragments through the lasing medium so as to preferentially excite low lying vibrational levels of the medium and to cause population inversions therein. The cooled gas lasing medium should have a mass areal density of about 5 .times. 10.sup.-.sup.3 grams/square centimeter, relaxation times of greater than 50 microseconds, and a broad range of excitable vibrational levels which are excitable by molecular collisions.

  2. Burried broken extraction instrument fragment

    PubMed Central

    Balaji, S. M.

    2013-01-01

    Despite adequate effort to perform tooth removal carefully, some accidents may happen when defective instruments are unknowingly used. This article reports of a non-symptomatic case of a retained fractured dental elevator tip during an uneventful extraction a decade earlier. Patient was not aware till routine radiographic examination revealed its presence. Use of three dimensional imaging techniques in this case is highlighted. Rarely, instruments breakage may occur during surgical procedures. It is duty of the dentists to check the surgical instrument for signs of breakage and be prepared to solve a possible emergency. Retained fragments should be carefully studied prior to attempt of removal. PMID:23662269

  3. Final Report

    SciTech Connect

    Gurney, Kevin R.

    2015-01-12

    This document constitutes the final report under DOE grant DE-FG-08ER64649. The organization of this document is as follows: first, I will review the original scope of the proposed research. Second, I will present the current draft of a paper nearing submission to Nature Climate Change on the initial results of this funded effort. Finally, I will present the last phase of the research under this grant which has supported a Ph.D. student. To that end, I will present the graduate student’s proposed research, a portion of which is completed and reflected in the paper nearing submission. This final work phase will be completed in the next 12 months. This final workphase will likely result in 1-2 additional publications and we consider the results (as exemplified by the current paper) high quality. The continuing results will acknowledge the funding provided by DOE grant DE-FG-08ER64649.

  4. Final Report

    SciTech Connect

    DeTar, Carleton

    2012-12-10

    This document constitutes the Final Report for award DE-FC02-06ER41446 as required by the Office of Science. It summarizes accomplishments and provides copies of scientific publications with significant contribution from this award.

  5. Ternary fission of nuclei into comparable fragments

    SciTech Connect

    Karpeshin, F. F.

    2015-07-15

    The problem of nuclear fission into three comparable fragments is considered. A mechanism of true ternary fission is proposed. In contrast to sequential fission, where the three fragments arise upon two sequential events of binary fission, the mechanism in question relies on a scenario that originally involves fission into three fragments. This mechanism is driven by a hexadecapole deformation of the fissioning nucleus, in contrast to binary fission associated with quadrupole vibrations of the nuclear surface. The fragment-mass ratios are estimated. The dynamics of formation of collinear fragments and their subsequent motion in opposite directions is traced. The calculated probability of true ternary fission complies with observed values.

  6. Ternary fission of nuclei into comparable fragments

    NASA Astrophysics Data System (ADS)

    Karpeshin, F. F.

    2015-07-01

    The problem of nuclear fission into three comparable fragments is considered. A mechanism of true ternary fission is proposed. In contrast to sequential fission, where the three fragments arise upon two sequential events of binary fission, the mechanism in question relies on a scenario that originally involves fission into three fragments. This mechanism is driven by a hexadecapole deformation of the fissioning nucleus, in contrast to binary fission associated with quadrupole vibrations of the nuclear surface. The fragment-mass ratios are estimated. The dynamics of formation of collinear fragments and their subsequent motion in opposite directions is traced. The calculated probability of true ternary fission complies with observed values.

  7. Impact of numerical models on fragmentation processes

    NASA Astrophysics Data System (ADS)

    Renouf, Mathieu; Gezahengn, Belien; Abbas, Micheline; Bourgeois, Florent

    2013-06-01

    Simulated fragmentation process in granular assemblies is a challenging problem which date back the beginning of the 90'. If first approaches have focus on the fragmentation on a single particle, with the development of robust, fast numerical method is is possible today to simulated such process in a large collection of particles. But the question of the fragmentation problem is still open: should the fragmentation be done dynamically (one particle becoming two fragments) and according which criterion or should the fragment paths be defined initially and which is the impact of the discretization and the model of fragments? The present contribution proposes to investigate the second aspect i.e. the impact of fragment modeling on the fragmentation processes. First to perform such an analysis, the geometry of fragments (disks/sphere or polygon/polyhedra), their behavior (rigid/deformable) and the law governing their interactions are investigated. Then such model will be used in a grinding application where the evolution of fragments and impact on the behavior of the whole packing are investigate.

  8. Fragmentation in filamentary molecular clouds

    NASA Astrophysics Data System (ADS)

    Contreras, Yanett; Garay, Guido; Rathborne, Jill M.; Sanhueza, Patricio

    2016-02-01

    Recent surveys of dust continuum emission at sub-mm wavelengths have shown that filamentary molecular clouds are ubiquitous along the Galactic plane. These structures are inhomogeneous, with overdensities that are sometimes associated with infrared emission and active of star formation. To investigate the connection between filaments and star formation, requires an understanding of the processes that lead to the fragmentation of filaments and a determination of the physical properties of the overdensities (clumps). In this paper, we present a multiwavelength study of five filamentary molecular clouds, containing several clumps in different evolutionary stages of star formation. We analyse the fragmentation of the filaments and derive the physical properties of their clumps. We find that the clumps in all filaments have a characteristic spacing consistent with the prediction of the `sausage' instability theory, regardless of the complex morphology of the filaments or their evolutionary stage. We also find that most clumps have sufficient mass and density to form high-mass stars, supporting the idea that high-mass stars and clusters form within filaments.

  9. Heavy Ion Fragmentation Experiments at the Bevatron

    NASA Technical Reports Server (NTRS)

    Heckman, H. H.

    1975-01-01

    Fragmentation processes of heavy nuclei in matter using the heavy-ion capability of the Bevatron were studied. The purpose was to obtain the single particle inclusive spectra of secondary nuclei produced at 0 deg by the fragmentation of heavy ion beam projectiles. The process being examined is B+T yields F + anything, where B is the beam nucleus, T is the target nucleus, and F is the detected fragment. The fragments F are isotopically identified by experimental procedures involving magnetic analysis, energy loss and time-of-flight measurements. Attempts were also made to: (1) measure the total and partial production cross section for all isotopes, (2) test the applicability of high-energy multi-particle interaction theory to nuclear fragmentation, (3) apply the cross-section data and fragmentation probabilities to cosmic ray transport theory, and (4) search for systematic behavior of fragment production as a means to improve existing semi-empirical theories of cross sections.

  10. Binding thermodynamics discriminates fragments from druglike compounds: a thermodynamic description of fragment-based drug discovery.

    PubMed

    Williams, Glyn; Ferenczy, György G; Ulander, Johan; Keserű, György M

    2016-12-01

    Small is beautiful - reducing the size and complexity of chemical starting points for drug design allows better sampling of chemical space, reveals the most energetically important interactions within protein-binding sites and can lead to improvements in the physicochemical properties of the final drug. The impact of fragment-based drug discovery (FBDD) on recent drug discovery projects and our improved knowledge of the structural and thermodynamic details of ligand binding has prompted us to explore the relationships between ligand-binding thermodynamics and FBDD. Information on binding thermodynamics can give insights into the contributions to protein-ligand interactions and could therefore be used to prioritise compounds with a high degree of specificity in forming key interactions.

  11. DNA Fragments Assembly Based on Nicking Enzyme System

    PubMed Central

    Wang, Rui-Yan; Shi, Zhen-Yu; Guo, Ying-Ying; Chen, Jin-Chun; Chen, Guo-Qiang

    2013-01-01

    A couple of DNA ligation-independent cloning (LIC) methods have been reported to meet various requirements in metabolic engineering and synthetic biology. The principle of LIC is the assembly of multiple overlapping DNA fragments by single-stranded (ss) DNA overlaps annealing. Here we present a method to generate single-stranded DNA overlaps based on Nicking Endonucleases (NEases) for LIC, the method was termed NE-LIC. Factors related to cloning efficiency were optimized in this study. This NE-LIC allows generating 3′-end or 5′-end ss DNA overlaps of various lengths for fragments assembly. We demonstrated that the 10 bp/15 bp overlaps had the highest DNA fragments assembling efficiency, while 5 bp/10 bp overlaps showed the highest efficiency when T4 DNA ligase was added. Its advantage over Sequence and Ligation Independent Cloning (SLIC) and Uracil-Specific Excision Reagent (USER) was obvious. The mechanism can be applied to many other LIC strategies. Finally, the NEases based LIC (NE-LIC) was successfully applied to assemble a pathway of six gene fragments responsible for synthesizing microbial poly-3-hydroxybutyrate (PHB). PMID:23483947

  12. Quantitative structure-hydrophobicity relationships of molecular fragments and beyond.

    PubMed

    Zou, Jian-Wei; Huang, Meilan; Huang, Jian-Xiang; Hu, Gui-Xiang; Jiang, Yong-Jun

    2016-03-01

    Quantitative structure-property relationship (QSPR) models were firstly established for the hydrophobic substituent constant (πX) using the theoretical descriptors derived solely from electrostatic potentials (EPSs) at the substituent atoms. The descriptors introduced are found to be related to hydrogen-bond basicity, hydrogen-bond acidity, cavity, or dipolarity/polarizability terms in linear solvation energy relationship, which endows the models good interpretability. The predictive capabilities of the models constructed were also verified by rigorous Monte Carlo cross-validation. Then, eight groups of meta- or para-disubstituted benzenes and one group of substituted pyridines were investigated. QSPR models for individual systems were achieved with the ESP-derived descriptors. Additionally, two QSPR models were also established for Rekker's fragment constants (foct), which is a secondary-treatment quantity and reflects average contribution of the fragment to logP. It has been demonstrated that the descriptors derived from ESPs at the fragments, can be well used to quantitatively express the relationship between fragment structures and their hydrophobic properties, regardless of the attached parent structure or the valence state. Finally, the relations of Hammett σ constant and ESP quantities were explored. It implies that σ and π, which are essential in classic QSAR and represent different type of contributions to biological activities, are also complementary in interaction site.

  13. Exploring fragment spaces under multiple physicochemical constraints

    NASA Astrophysics Data System (ADS)

    Pärn, Juri; Degen, Jörg; Rarey, Matthias

    2007-06-01

    We present a new algorithm for the enumeration of chemical fragment spaces under constraints. Fragment spaces consist of a set of molecular fragments and a set of rules that specifies how fragments can be combined. Although fragment spaces typically cover an infinite number of molecules, they can be enumerated in case that a physicochemical profile of the requested compounds is given. By using min-max ranges for a number of corresponding properties, our algorithm is able to enumerate all molecules which obey these properties. To speed up the calculation, the given ranges are used directly during the build-up process to guide the selection of fragments. Furthermore, a topology based fragment filter is used to skip most of the redundant fragment combinations. We applied the algorithm to 40 different target classes. For each of these, we generated tailored fragment spaces from sets of known inhibitors and additionally derived ranges for several physicochemical properties. We characterized the target-specific fragment spaces and were able to enumerate the complete chemical subspaces for most of the targets.

  14. Permeable Gas Flow Influences Magma Fragmentation Speed.

    NASA Astrophysics Data System (ADS)

    Richard, D.; Scheu, B.; Spieler, O.; Dingwell, D.

    2008-12-01

    Highly viscous magmas undergo fragmentation in order to produce the pyroclastic deposits that we observe, but the mechanisms involved remain unclear. The overpressure required to initiate fragmentation depends on a number of physical parameters, such as the magma's vesicularity, permeability, tensile strength and textural properties. It is clear that these same parameters control also the speed at which a fragmentation front travels through magma when fragmentation occurs. Recent mathematical models of fragmentation processes consider most of these factors, but permeable gas flow has not yet been included in these models. However, it has been shown that permeable gas flow through a porous rock during a sudden decompression event increases the fragmentation threshold. Fragmentation experiments on natural samples from Bezymianny (Russia), Colima (Mexico), Krakatau (Indonesia) and Augustine (USA) volcanoes confirm these results and suggest in addition that high permeable flow rates may increase the speed of fragmentation. Permeability from the investigated samples ranges from as low as 5 x 10-14 to higher than 9 x 10- 12 m2 and open porosity ranges from 16 % to 48 %. Experiments were performed for each sample series at applied pressures up to 35 MPa. Our results indicate that the rate of increase of fragmentation speed is higher when the permeability is above 10-12 m2. We confirm that it is necessary to include the influence of permeable flow on fragmentation dynamics.

  15. Single chain Fab (scFab) fragment

    PubMed Central

    Hust, Michael; Jostock, Thomas; Menzel, Christian; Voedisch, Bernd; Mohr, Anja; Brenneis, Mariam; Kirsch, Martina I; Meier, Doris; Dübel, Stefan

    2007-01-01

    Background The connection of the variable part of the heavy chain (VH) and and the variable part of the light chain (VL) by a peptide linker to form a consecutive polypeptide chain (single chain antibody, scFv) was a breakthrough for the functional production of antibody fragments in Escherichia coli. Being double the size of fragment variable (Fv) fragments and requiring assembly of two independent polypeptide chains, functional Fab fragments are usually produced with significantly lower yields in E. coli. An antibody design combining stability and assay compatibility of the fragment antigen binding (Fab) with high level bacterial expression of single chain Fv fragments would be desirable. The desired antibody fragment should be both suitable for expression as soluble antibody in E. coli and antibody phage display. Results Here, we demonstrate that the introduction of a polypeptide linker between the fragment difficult (Fd) and the light chain (LC), resulting in the formation of a single chain Fab fragment (scFab), can lead to improved production of functional molecules. We tested the impact of various linker designs and modifications of the constant regions on both phage display efficiency and the yield of soluble antibody fragments. A scFab variant without cysteins (scFabΔC) connecting the constant part 1 of the heavy chain (CH1) and the constant part of the light chain (CL) were best suited for phage display and production of soluble antibody fragments. Beside the expression system E. coli, the new antibody format was also expressed in Pichia pastoris. Monovalent and divalent fragments (DiFabodies) as well as multimers were characterised. Conclusion A new antibody design offers the generation of bivalent Fab derivates for antibody phage display and production of soluble antibody fragments. This antibody format is of particular value for high throughput proteome binder generation projects, due to the avidity effect and the possible use of common standard sera

  16. Fragmentation of interstellar clouds and star formation

    NASA Technical Reports Server (NTRS)

    Silk, J.

    1982-01-01

    The principal issues are addressed: the fragmentation of molecular clouds into units of stellar mass and the impact of star formation on molecular clouds. The observational evidence for fragmentation is summarized, and the gravitational instability described of a uniform spherical cloud collapsing from rest. The implications are considered of a finite pressure for the minimum fragment mass that is attainable in opacity-limited fragmentation. The role of magnetic fields is discussed in resolving the angular momentum problem and in making the collapse anisotropic, with notable consequences for fragmentation theory. Interactions between fragments are described, with emphasis on the effect of protostellar winds on the ambient cloud matter and on inhibiting further star formation. Such interactions are likely to have profound consequences for regulating the rate of star formation and on the energetics and dynamics of molecular clouds.

  17. Fragmentation processes in two-phase materials

    NASA Astrophysics Data System (ADS)

    Carmona, H. A.; Guimarães, A. V.; Andrade, J. S.; Nikolakopoulos, I.; Wittel, F. K.; Herrmann, H. J.

    2015-01-01

    We investigate the fragmentation process of solid materials with crystalline and amorphous phases using the the discrete element method. Damage initiates inside spherical samples above the contact zone in a region where the circumferential stress field is tensile. Cracks initiated in this region grow to form meridional planes. If the collision energy exceeds a critical value which depends on the material's internal structure, cracks reach the sample surface resulting in fragmentation. We show that this primary fragmentation mechanism is very robust with respect to the internal structure of the material. For all configurations, a sharp transition from the damage to the fragmentation regime is observed, with smaller critical collision energies for crystalline samples. The mass distribution of the fragments follows a power law for small fragments with an exponent that is characteristic for the branching merging process of unstable cracks. Moreover this exponent depends only on the dimensionally of the system and not on the microstructure.

  18. Impact failure and fragmentation properties of metals

    SciTech Connect

    Grady, D.E.; Kipp, M.E.

    1998-03-01

    In the present study we describe the development of an experimental fracture material property test method specific to dynamic fragmentation. Spherical test samples of the metals of interest are subjected to controlled impulsive stress loads by acceleration to high velocities with a light-gas launcher facility and subsequent normal impact on thin plates. Motion, deformation and fragmentation of the test samples are diagnosed with multiple flash radiography methods. The impact plate materials are selected to be transparent to the x-ray method so that only test metal material is imaged. Through a systematic series of such tests both strain-to-failure and fragmentation resistance properties are determined through this experimental method. Fragmentation property data for several steels, copper, aluminum, tantalum and titanium have been obtained to date. Aspects of the dynamic data have been analyzed with computational methods to achieve a better understanding of the processes leading to failure and fragmentation, and to test an existing computational fragmentation model.

  19. Tooth fragment reattachment: An esthetic, biological restoration

    PubMed Central

    Choudhary, Ajay; Garg, Rakesh; Bhalla, Anindya; Khatri, Rohit Kumar

    2015-01-01

    Coronal fractures of the anterior teeth are a common form of dental trauma. If the original tooth fragment is retained following fracture, reattachment of the fractured fragment to the remaining tooth can provide better and long lasting esthetics, improved function, a positive psychological response, and is a faster and less complicated procedure. This paper reports on coronal tooth fracture case that was successfully treated using adhesive reattachment of fractured fragment and post placement. PMID:25810662

  20. Complex fragment emission from hot compound nuclei

    SciTech Connect

    Moretto, L.G.

    1986-03-01

    The experimental evidence for compound nucleus emission of complex fragments at low energies is used to interpret the emission of the same fragments at higher energies. The resulting experimental picture is that of highly excited compound nuclei formed in incomplete fusion processes which decay statistically. In particular, complex fragments appear to be produced mostly through compound nucleus decay. In the appendix a geometric-kinematic theory for incomplete fusion and the associated momentum transfer is outlined. 10 refs., 19 figs.

  1. Filter for interpretation of fragmentation during entry

    SciTech Connect

    Canavan, G.H.

    1997-10-01

    Objects that fragment cascade and decelerate abruptly, producing short, bright, signatures which can be used to estimate object diameter and speed. Other objects can be incorporated into a generalized fragmentation filter. This note summarizes the results of previous reports on the prediction and inversion of signatures from objects that radiate, ablate, and fragment during entry and uses them to produce models for the parameters of entering objects.

  2. Interaction of three fission fragments and yields of various ternary fragments

    NASA Astrophysics Data System (ADS)

    Denisov, V. Yu.; Pilipenko, N. A.; Sedykh, I. Yu.

    2017-01-01

    The interaction potential energy of the three deformed fragments formed in fission of 252Cf is studied for various combinations of three-fragment fission. The lowest height of the potential energy ridge between three touching and separated deformed fragments is sought. The excitation energies of various three-deformed-fragment configurations, at the lowest barrier heights related to the yield of the corresponding configuration, are considered in detail. The most probable three-fragment fission configurations are discussed. The yields of various ternary fragments in fission of 250Cf agree well with available experimental data.

  3. The dihadron fragmentation function and its evolution

    SciTech Connect

    Majumder, Abhijit; Wang, Xin-Nian

    2004-02-24

    Dihadron fragmentation functions and their evolution arestudied in the process of e+e- annihilation. Under the collinearfactorization approximation and facilitated by the cut-vertex technique,the two hadron inclusive cross section at leading order (LO) is shown tofactorize into a short distance parton cross section and a long distancedihadron fragmentation function. We provide the definition of such adihadron fragmentation function in terms of parton matrix elements andderive its DGLAP evolution equation at leading log. The evolutionequation for the non-singlet quark fragmentation function is solvednumerically with a simple ansatz for the initial condition and resultsare presented for cases of physical interest.

  4. Optical model calculations of heavy-ion target fragmentation

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.; Cucinotta, F. A.; Norbury, J. W.

    1986-01-01

    The fragmentation of target nuclei by relativistic protons and heavy ions is described within the context of a simple abrasion-ablation-final-state interaction model. Abrasion is described by a quantum mechanical formalism utilizing an optical model potential approximation. Nuclear charge distributions of the excited prefragments are calculated by both a hypergeometric distribution and a method based upon the zero-point oscillations of the giant dipole resonance. Excitation energies are estimated from the excess surface energy resulting from the abrasion process and the additional energy deposited by frictional spectator interactions of the abraded nucleons. The ablation probabilities are obtained from the EVA-3 computer program. Isotope production cross sections for the spallation of copper targets by relativistic protons and for the fragmenting of carbon targets by relativistic carbon, neon, and iron projectiles are calculated and compared with available experimental data.

  5. Gene prediction in metagenomic fragments based on the SVM algorithm

    PubMed Central

    2013-01-01

    Background Metagenomic sequencing is becoming a powerful technology for exploring micro-ogranisms from various environments, such as human body, without isolation and cultivation. Accurately identifying genes from metagenomic fragments is one of the most fundamental issues. Results In this article, we present a novel gene prediction method named MetaGUN for metagenomic fragments based on a machine learning approach of SVM. It implements in a three-stage strategy to predict genes. Firstly, it classifies input fragments into phylogenetic groups by a k-mer based sequence binning method. Then, protein-coding sequences are identified for each group independently with SVM classifiers that integrate entropy density profiles (EDP) of codon usage, translation initiation site (TIS) scores and open reading frame (ORF) length as input patterns. Finally, the TISs are adjusted by employing a modified version of MetaTISA. To identify protein-coding sequences, MetaGun builds the universal module and the novel module. The former is based on a set of representative species, while the latter is designed to find potential functionary DNA sequences with conserved domains. Conclusions Comparisons on artificial shotgun fragments with multiple current metagenomic gene finders show that MetaGUN predicts better results on both 3' and 5' ends of genes with fragments of various lengths. Especially, it makes the most reliable predictions among these methods. As an application, MetaGUN was used to predict genes for two samples of human gut microbiome. It identifies thousands of additional genes with significant evidences. Further analysis indicates that MetaGUN tends to predict more potential novel genes than other current metagenomic gene finders. PMID:23735199

  6. A highly bent fragment of Crithidia fasciculata kinetoplast DNA.

    PubMed

    Kitchin, P A; Klein, V A; Ryan, K A; Gann, K L; Rauch, C A; Kang, D S; Wells, R D; Englund, P T

    1986-08-25

    Kinetoplast DNA minicircles from Crithidia fasciculata contain a single major region of bent helix. Restriction fragments containing this bent helix have electrophoretic behavior on polyacrylamide gels which is much more anomalous than that of previously studied bent fragments. Therefore, the C. fasciculata fragments probably have a more extreme curvature. Sequencing part of a cloned minicircle revealed an unusual structure for the bent region. In a sequence of 200 bases, the bent region contains 18 runs of 4-6 As with 16 of these runs in the same strand. In some parts of this sequence the A runs are regularly spaced with a periodicity of about 10 base pairs. This spacing is nearly in phase with the twist of the DNA helix. This same sequence arrangement has been observed in other bent fragments, but the number of A runs is much greater in this C. fasciculata sequence. It is likely that there are small bends associated with each A run which, because of their periodic spacing, add up to produce substantial curvature in this molecule. In addition to having highly anomalous electrophoretic behavior, the fragment has unusual circular dichroism spectra. Its spectrum in the absence of ethanol is that of B DNA, but ethanol in the concentration range of 51-71% (w/w) induces changes to forms which are different from those of any well characterized DNA structure. The C. fasciculata bent helix is neither cleaved by S1 nuclease nor modified by bromoacetaldehyde under conditions in which other unusual DNA structures (such as cruciforms or B-Z junctions) are susceptible to attack by these reagents. Finally, a two-dimensional agarose gel analysis of a family of topoisomers of a plasmid containing the bent helix revealed no supercoil-induced relaxation.

  7. Final Report

    SciTech Connect

    Marchant, Gary E.

    2013-04-23

    This is the final report of a two year project entitled "Governing Nanotechnology Risks and Benefits in the Transition to Regulation: Innovative Public and Private Approaches." This project examined the role of new governance or "soft law" mechanisms such as codes of conduct, voluntary programs and partnership agreements to manage the risks of emerging technologies such as nanotechnology. A series of published or in publication papers and book chapters are attached.

  8. Final Report

    SciTech Connect

    R. Paul Drake

    2001-11-30

    This final report describes work involving 22 investigators from 11 institutions to explore the dynamics present in supernova explosions by means of experiments on the Omega laser. The specific experiments emphasized involved the unstable expansion of a spherical capsule and the coupling of perturbations at a first interface to a second interface by means of a strong shock. Both effects are present in supernovae. The experiments were performed at Omega and the computer simulations were undertaken at several institutions. B139

  9. Final Report

    SciTech Connect

    Stinis, Panos

    2016-08-07

    This is the final report for the work conducted at the University of Minnesota (during the period 12/01/12-09/18/14) by PI Panos Stinis as part of the "Collaboratory on Mathematics for Mesoscopic Modeling of Materials" (CM4). CM4 is a multi-institution DOE-funded project whose aim is to conduct basic and applied research in the emerging field of mesoscopic modeling of materials.

  10. Dynamic fragmentation in a quenched two-mode Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Wu, Shu-Yuan; Zhong, Hong-Hua; Huang, Jia-Hao; Qin, Xi-Zhou; Lee, Chao-Hong

    2016-06-01

    We investigate the fragmentation in a two-mode Bose-Einstein condensate with Josephson coupling. We explore how the fragmentation and entropy of the ground state depend on the intermode asymmetry and interparticle interactions. Owing to the interplay between the asymmetry and the interactions, a sequence of notches and plateaus in the fragmentation appears with the single-atom tunneling and interaction blockade, respectively. We then analyze the dynamical properties of the fragmentation in three typical quenches of the asymmetry: linear, sudden, and periodic quenches. In a linear quench, the final state is a fragmented state due to the sequential Landau-Zener tunneling, which can be analytically explained by applying the two-level Landau-Zener formula for each avoided level crossing. In a sudden quench, the fragmentation exhibits persistent fluctuations that sensitively depend on the interparticle interactions and intermode coupling. In a periodic quench, the fragmentation is modulated by the periodic driving, and a suitable modulation may allow one to control the fragmentation.

  11. The role of thermodynamics in disc fragmentation

    NASA Astrophysics Data System (ADS)

    Stamatellos, Dimitris; Whitworth, Anthony P.

    2009-12-01

    Thermodynamics play an important role in determining the way a protostellar disc fragments to form planets, brown dwarfs and low-mass stars. We explore the effect that different treatments of radiative transfer have in simulations of fragmenting discs. Three prescriptions for the radiative transfer are used: (i) the diffusion approximation of Stamatellos et al.; (ii) the barotropic equation of state (EOS) of Goodwin et al. and (iii) the barotropic EOS of Bate et al. The barotropic approximations capture the general evolution of the density and temperature at the centre of each proto-fragment but (i) they do not make any adjustments for particular circumstances of a proto-fragment forming in the disc and (ii) they do not take into account thermal inertia effects that are important for fast-forming proto-fragments in the outer disc region. As a result, the number of fragments formed in the disc and their properties are different, when a barotropic EOS is used. This is important not only for disc studies but also for simulations of collapsing turbulent clouds, as in many cases in such simulations stars form with discs that subsequently fragment. We also examine the difference in the way proto-fragments condense out in the disc at different distances from the central star using the diffusion approximation and following the collapse of each proto-fragment until the formation of the second core (ρ ~= 10-3gcm-3). We find that proto-fragments forming closer to the central star tend to form earlier and evolve faster from the first to the second core than proto-fragments forming in the outer disc region. The former have a large pool of material in the inner disc region that they can accrete from and grow in mass. The latter accrete more slowly and they are hotter because they generally form in a quick abrupt event.

  12. The Argonne fragment mass analyzer

    SciTech Connect

    Davids, C.N.; Larson, J.D.

    1988-01-01

    The Fragment Mass Analyzer (FMA) is currently under construction at the ATLAS facility. The FMA is an eight-meter long recoil mass spectrometer which will be used to separate nuclear reaction products from the primary heavy-ion beam and disperse them by A/q (mass/charge) at the focal plane. The FMA will be used in many different types of experiments. Gamma rays originating from very weak fusion-evaporation channels can be observed in coincidence with the recoil nucleus identified at the FMA focal plane. Production and decay of nuclei far from stability will be studied at the focal plane by implanting exotic recoils directly into detectors or by using a fast tape transport system. The FMA will also be used for reaction mechanism studies. A radioactive beam facility behind the focal plane is planned, which will allow beta-NMR and nuclear moment measurements to be made. The FMA will utilize the wide range of beam and intensities to be provided by the new ECR-positive ion injector also under construction at ATLAS. 8 refs., 4 figs., 1 tab.

  13. Methodology for Dynamic Characterization of Fragmenting Warheads

    DTIC Science & Technology

    2009-05-01

    the originator. Army Research Laboratory Aberdeen Proving Ground, MD 21005-5069 ARL-SR-179 May 2009 Methodology for Dynamic... Methodology for Dynamic Characterization of Fragmenting Warheads by Jason Angel ARL-SR-179 May 2009...Characterization of Fragmenting Warheads Jason Angel Weapons and Materials Research Directorate, ARL

  14. Baculovirus display of functional antibody Fab fragments.

    PubMed

    Takada, Shinya; Ogawa, Takafumi; Matsui, Kazusa; Suzuki, Tasuku; Katsuda, Tomohisa; Yamaji, Hideki

    2015-08-01

    The generation of a recombinant baculovirus that displays antibody Fab fragments on the surface was investigated. A recombinant baculovirus was engineered so that the heavy chain (Hc; Fd fragment) of a mouse Fab fragment was expressed as a fusion to the N-terminus of baculovirus gp64, while the light chain of the Fab fragment was simultaneously expressed as a secretory protein. Following infection of Sf9 insect cells with the recombinant baculovirus, the culture supernatant was analyzed by enzyme-linked immunosorbent assay using antigen-coated microplates and either an anti-mouse IgG or an anti-gp64 antibody. A relatively strong signal was obtained in each case, showing antigen-binding activity in the culture supernatant. In western blot analysis of the culture supernatant using the anti-gp64 antibody, specific protein bands were detected at an electrophoretic mobility that coincided with the molecular weight of the Hc-gp64 fusion protein as well as that of gp64. Flow cytometry using a fluorescein isothiocyanate-conjugated antibody specific to mouse IgG successfully detected the Fab fragments on the surface of the Sf9 cells. These results suggest that immunologically functional antibody Fab fragments can be displayed on the surface of baculovirus particles, and that a fluorescence-activated cell sorter with a fluorescence-labeled antigen can isolate baculoviruses displaying specific Fab fragments. This successful baculovirus display of antibody Fab fragments may offer a novel approach for the efficient selection of specific antibodies.

  15. The Stellar IMF from turbulent fragmentation

    NASA Technical Reports Server (NTRS)

    Padoan, P.; Nordlund, A.

    2001-01-01

    In this paper they conclude that turbulent fragmentation is unavoidable in super-sonically turbulent molecular clouds, and given the success of the present model to predict the observed shape of the Stellar IMF, they conclude that turbulent fragmentation is essential to the origin of the stellar IMF.

  16. The Family Circle: A Study in Fragmentation

    ERIC Educational Resources Information Center

    Bronfenbrenner, Urie

    1976-01-01

    Presents data describing the fragmentation of the family, suggests causes for the fragmentation, and offers suggestions for reversing the trend. The suggestions focus on day care, part-time employment practices, enhancing the position of women, and work and responsibility. (IRT)

  17. Sizing of DNA fragments by flow cytometry

    SciTech Connect

    Johnson, M.E.; Goodwin, P.M.; Ambrose, W.P.; Martin, J.C.; Marrone, B.L.; Jett, J.H.; Keller, R.A.

    1993-02-01

    Individual, stained DNA fragments were sized using a modified flow cytometer with high sensitivity fluorescence detection. The fluorescent intercalating dye ethidium homodimer was used to stain stoichiometrically lambda phage DNA and a Kpn I digest of lambda DNA. Stained, individual fragments of DNA were passed through a low average power, focused, mode-locked laser beam, and the fluorescence from each fragment was collected and quantified. Time-gated detection was used to discriminate against Raman scattering from the water solvent. The fluorescence burst from each fragment was related directly to its length, thus providing a means to size small quantities of kilobase lengths of DNA quickly. Improvements of several orders of magnitude in analysis time and sample size over current gel electrophoresis techniques were realized. Fragments of 17.1,29.9, and 48.5 thousand base pairs were well resolved, and were sized in 164 seconds. Less than one pg of DNA was required for analysis. We have demonstrated sizing of individual, stained DNA fragments with resolution approaching that of gel electrophoresis for moderately large fragments, but with significant reductions in the analysis time and the amount of sample required. Furthermore, system response is linear with DNA fragment length, in contrast to the logarithmic response in gel electrophoresis. There exists the potential to perform this sizing using relatively simple instrumentation, i.e. a continuous wave laser of low power and current mode detection.

  18. Sizing of DNA fragments by flow cytometry

    SciTech Connect

    Johnson, M.E.; Goodwin, P.M.; Ambrose, W.P.; Martin, J.C.; Marrone, B.L.; Jett, J.H.; Keller, R.A.

    1993-01-01

    Individual, stained DNA fragments were sized using a modified flow cytometer with high sensitivity fluorescence detection. The fluorescent intercalating dye ethidium homodimer was used to stain stoichiometrically lambda phage DNA and a Kpn I digest of lambda DNA. Stained, individual fragments of DNA were passed through a low average power, focused, mode-locked laser beam, and the fluorescence from each fragment was collected and quantified. Time-gated detection was used to discriminate against Raman scattering from the water solvent. The fluorescence burst from each fragment was related directly to its length, thus providing a means to size small quantities of kilobase lengths of DNA quickly. Improvements of several orders of magnitude in analysis time and sample size over current gel electrophoresis techniques were realized. Fragments of 17.1,29.9, and 48.5 thousand base pairs were well resolved, and were sized in 164 seconds. Less than one pg of DNA was required for analysis. We have demonstrated sizing of individual, stained DNA fragments with resolution approaching that of gel electrophoresis for moderately large fragments, but with significant reductions in the analysis time and the amount of sample required. Furthermore, system response is linear with DNA fragment length, in contrast to the logarithmic response in gel electrophoresis. There exists the potential to perform this sizing using relatively simple instrumentation, i.e. a continuous wave laser of low power and current mode detection.

  19. Final Report

    SciTech Connect

    R Paul Drake

    2004-01-12

    OAK-B135 This is the final report from the project Hydrodynamics by High-Energy-Density Plasma Flow and Hydrodynamics and Radiation Hydrodynamics with Astrophysical Applications. This project supported a group at the University of Michigan in the invention, design, performance, and analysis of experiments using high-energy-density research facilities. The experiments explored compressible nonlinear hydrodynamics, in particular at decelerating interfaces, and the radiation hydrodynamics of strong shock waves. It has application to supernovae, astrophysical jets, shock-cloud interactions, and radiative shock waves.

  20. First principles approach to ionicity of fragments

    NASA Astrophysics Data System (ADS)

    Pilania, Ghanshyam; Liu, Xiang-Yang; Valone, Steven M.

    2015-02-01

    We develop a first principles approach towards the ionicity of fragments. In contrast to the bond ionicity, the fragment ionicity refers to an electronic property of the constituents of a larger system, which may vary from a single atom to a functional group or a unit cell to a crystal. The fragment ionicity is quantitatively defined in terms of the coefficients of contributing charge states in a superposition of valence configurations of the system. Utilizing the constrained density functional theory-based computations, a practical method to compute the fragment ionicity from valence electron charge densities, suitably decomposed according to the Fragment Hamiltonian (FH) model prescription for those electron densities, is presented for the first time. The adopted approach is illustrated using BeO, MgO and CaO diatomic molecules as simple examples. The results are compared and discussed with respect to the bond ionicity scales of Phillips and Pauling.

  1. Sheared DNA fragment sizing: comparison of techniques.

    PubMed Central

    Ordahl, C P; Johnson, T R; Caplan, A I

    1976-01-01

    DNA fragmented by conventional French press shearing procedures (30,000 lbs/in2) has a number-average fragment size of 230 base pairs. This is considerably smaller than the 450 base pairs typically reported for DNA sheared by this method. Comparison of 5 sizing techniques indicates that sheared DNA fragment size is overestimated by either measurement of velocity sedimentation or Kleinschmidt Electron Microscopic visualization. Both adsorption grid electron microscopic visualization and gel electrophoresis yield the most reliable estimates of the mean size of small DNA fragment populations. In addition, the assessment of fragment size distribution (not possible from sedimentation analysis) potentially allows more critical evaluation of DNA hybridization and reassociation kinetic and measurement parameters. Images PMID:1034292

  2. FINAL REPORT

    SciTech Connect

    PETER, GARY F.

    2014-07-16

    Excellent progress was made in standardizing three complementary methods: Magnetic resonance imaging, x-ray micro CT, and MALDI imaging linear ion trap mass spectroscopy to image biomass and chemical, anatomical and functional changes that occur during pretreatment and hydrolysis. Magnetic resonance microscopy provides excellent images with as low as 5 uM resolution with hydrated biomass samples. We visualized dramatic changes in signal associated with the hydrolysis of the carbohydrates by strong acids. Quantitative diffusion approaches were used to probe more subtle structural changes in biomass. Diffusion tensor calculations reflect diffusion anisotropy and fractional anisotropy maps clearly show the longer range diffusion within the vessels compared to within the fiber cells. The diffusion is increased along the cell walls of the vessels. Suggesting that further research with NMR imaging should be pursued. X-ray CT provides excellent images at as low as 3.5 uM resolution from dried biomass. Small increases in surface area, and decreases in local density have been quantified in with wood after mild pretreatments; these changes are expected to be underestimates of the hydrated wood, due to the ~12% shrinkage that occurs upon drying untreated wood. MALDI-MS spectra show high ion intensities at most mass to charge ratios in untreated and pretreated woody material. MALDI-MSn is required to improve specificity and reduce background for imaging. MALDI-TOF is not specific enough for carbohydrate identification. Using MALDI-LIT/MSn we can readily identify oligomeric glucans and xylans and their fragmentation patterns as well as those of the glucuronic acid side chains of birch 4-O-methyl glucuronxylan. Imaging of glucan and xylan oligomers show that many contain isobaric ions with different distributions, indicating again that MSn is needed for accurate imaging of lignocellulosic materials. We are now starting to integrate the three imaging methods by using the same set

  3. In Situ X-Ray Observations of Dendritic Fragmentation During Directional Solidification of a Sn-Bi Alloy

    SciTech Connect

    Gibbs, John W.; Tourret, Damien; Gibbs, Paul J.; Imhoff, Seth D.; Gibbs, Meghan Jane; Walker, Brandon A.; Fezzaa, Kamel; Clarke, Amy Jean

    2015-09-25

    Dendrite fragmentation is an important phenomenon in microstructural development during solidification. For instance, it plays a key role in initiating the columnar-to-equiaxed transition (CET). In this paper, we use x-ray radiography to study dendrite fragmentation rate in a Sn-39.5 wt.% Bi alloy during directional solidification. Experiments were performed in which solidification was parallel and anti-parallel to gravity, leading to significantly different fragmentation rates. We quantify the distribution of fragmentation rate as a function of distance from the solidification front, time in the mushy zone, and volume fraction of solid. Finally, while the observed fragmentation rate can be high, there is no evidence of a CET, illustrating that it requires more than just fragmentation to occur.

  4. In Situ X-Ray Observations of Dendritic Fragmentation During Directional Solidification of a Sn-Bi Alloy

    DOE PAGES

    Gibbs, John W.; Tourret, Damien; Gibbs, Paul J.; ...

    2015-09-25

    Dendrite fragmentation is an important phenomenon in microstructural development during solidification. For instance, it plays a key role in initiating the columnar-to-equiaxed transition (CET). In this paper, we use x-ray radiography to study dendrite fragmentation rate in a Sn-39.5 wt.% Bi alloy during directional solidification. Experiments were performed in which solidification was parallel and anti-parallel to gravity, leading to significantly different fragmentation rates. We quantify the distribution of fragmentation rate as a function of distance from the solidification front, time in the mushy zone, and volume fraction of solid. Finally, while the observed fragmentation rate can be high, there ismore » no evidence of a CET, illustrating that it requires more than just fragmentation to occur.« less

  5. Mass yields and kinetic energy of fragments from fission of highly-excited nuclei with A≲220

    NASA Astrophysics Data System (ADS)

    Denisov, V. Yu.; Margitych, T. O.; Sedykh, I. Yu.

    2017-02-01

    It is shown that the potential energy surface of the two separated fragments has the saddle point, which takes place at small distance between the surfaces of well-deformed fragments. The height of this two-body saddle point is larger than the height of one-body fission barrier for nuclei with A ≲ 220. The mass yields of the fission fragments, which are appearing at the fission of nuclei with A ≲ 220, are related to the number of states of the two-fragment systems at the two-body saddle points. The characteristics of kinetic energy of fragments are described by using the trajectory motion equations with the dissipation terms. The Gaussian distribution of the final kinetic energy around the classical value of this energy induced by the stochastic fluctuations is taken into account at an evaluation of the total kinetic energy distributions of the fission fragments.

  6. Aggregation-fragmentation model of robust concentration gradient formation

    NASA Astrophysics Data System (ADS)

    Saunders, Timothy E.

    2015-02-01

    Concentration gradients of signaling molecules are essential for patterning during development and they have been observed in both unicellular and multicellular systems. In subcellular systems, clustering of the signaling molecule has been observed. We develop a theoretical model of cluster-mediated concentration gradient formation based on the Becker-Döring equations of aggregation-fragmentation processes. We show that such a mechanism produces robust concentration gradients on realistic time and spatial scales so long as the process of clustering does not significantly stabilize the signaling molecule. Finally, we demonstrate that such a model is applicable to the pom1p subcellular gradient in fission yeast.

  7. Frozen Impacted Drop: from Fragmentation to Hierarchical Crack Patterns

    NASA Astrophysics Data System (ADS)

    Séon, Thomas; Ghabache, Elisabeth; Josserand, Christophe

    2016-11-01

    We investigate experimentally the quenching of a liquid pancake, obtained through the impact of a water drop on a cold solid substrate (0°C to -60°C). We show that, below a certain substrate temperature, fractures appear on the frozen pancake and the crack patterns change from a 2D fragmentation regime to a hierarchical fracture regime as the thermal shock increases. The different regimes are discussed and the transition temperatures are estimated through classical fracture scaling arguments. Finally, a phase diagram presents how these regimes can be controlled by the drop impact parameters.

  8. Frozen Impacted Drop: From Fragmentation to Hierarchical Crack Patterns

    NASA Astrophysics Data System (ADS)

    Ghabache, Elisabeth; Josserand, Christophe; Séon, Thomas

    2016-08-01

    We investigate experimentally the quenching of a liquid pancake, obtained through the impact of a water drop on a cold solid substrate (0 °C to -60 ° C ). We show that, below a certain substrate temperature, fractures appear on the frozen pancake and the crack patterns change from a 2D fragmentation regime to a hierarchical fracture regime as the thermal shock increases. The different regimes are discussed and the transition temperatures are estimated through classical fracture scaling arguments. Finally, a phase diagram presents how these regimes can be controlled by the drop impact parameters.

  9. Ion sources for fission fragment accelerators

    NASA Astrophysics Data System (ADS)

    Köster, U.; Kester, O.; Habs, D.

    1998-03-01

    At the Grenoble and Munich high-flux reactors fission fragment accelerators are under design which will deliver beams of very neutron-rich fission products with a final energy between 3 and 6 MeV/u. In order to obtain an efficient acceleration in a compact accelerator, charge conversion of the 1+ ion beams from the in-pile ion source to a q/A⩾0.16 has to take place. In the chain from production to acceleration, ion sources are the key elements to reach high beam intensities of over 1010s-1. For the in-pile part the target-ion source assembly has not only to be very efficient, but should also be highly selective for the desired elements (which go from nickel to europium) on one hand and robust against the hostile environment (high neutron and gamma flux) on the other hand. Foreseen types are a surface ionization source, which could also be run as laser ion source for resonant photo ionization, and, for rare gases, a plasma ion source coupled via a transfer line to the target. For the charge state breeding several different schemes are considered: the combination of a Penning trap for bunching, cooling, and mass separation and an electron beam ion source (EBIS) as charge breeder, similar to REX-ISOLDE, an EBIS with direct injection of a dc beam of 1+ ions ("accu-EBIS") or an electron cyclotron resonance ion source (ECRIS) with either continuous or bunched extraction. The EBIS may provide higher charge states, whereas the ECRIS is able to work with much higher beam intensities and allows cw-operation. The advantage of each scheme is explained and some design requirements of the different sources are presented.

  10. Ion sources for fission fragment accelerators

    NASA Astrophysics Data System (ADS)

    Köster, U.; Kester, O.; Habs, D.

    1998-02-01

    At the Grenoble and Munich high-flux reactors fission fragment accelerators are under design which will deliver beams of very neutron-rich fission products with a final energy between 3 and 6 MeV/u. In order to obtain an efficient acceleration in a compact accelerator, charge conversion of the 1+ ion beams from the in-pile ion source to a q/A⩾0.16 has to take place. In the chain from production to acceleration, ion sources are the key elements to reach high beam intensities of over 1010s-1. For the in-pile part the target-ion source assembly has not only to be very efficient, but should also be highly selective for the desired elements (which go from nickel to europium) on one hand and robust against the hostile environment (high neutron and gamma flux) on the other hand. Foreseen types are a surface ionization source, which could also be run as laser ion source for resonant photo ionization, and, for rare gases, a plasma ion source coupled via a transfer line to the target. For the charge state breeding several different schemes are considered: the combination of a Penning trap for bunching, cooling, and mass separation and an electron beam ion source (EBIS) as charge breeder, similar to REX-ISOLDE, an EBIS with direct injection of a dc beam of 1+ ions ("accu-EBIS") or an electron cyclotron resonance ion source (ECRIS) with either continuous or bunched extraction. The EBIS may provide higher charge states, whereas the ECRIS is able to work with much higher beam intensities and allows cw-operation. The advantage of each scheme is explained and some design requirements of the different sources are presented.

  11. Virtual fragment screening: an exploration of various docking and scoring protocols for fragments using Glide

    NASA Astrophysics Data System (ADS)

    Kawatkar, Sameer; Wang, Hongming; Czerminski, Ryszard; Joseph-McCarthy, Diane

    2009-08-01

    Fragment-based drug discovery approaches allow for a greater coverage of chemical space and generally produce high efficiency ligands. As such, virtual and experimental fragment screening are increasingly being coupled in an effort to identify new leads for specific therapeutic targets. Fragment docking is employed to create target-focussed subset of compounds for testing along side generic fragment libraries. The utility of the program Glide with various scoring schemes for fragment docking is discussed. Fragment docking results for two test cases, prostaglandin D2 synthase and DNA ligase, are presented and compared to experimental screening data. Self-docking, cross-docking, and enrichment studies are performed. For the enrichment runs, experimental data exists indicating that the docking decoys in fact do not inhibit the corresponding enzyme being examined. Results indicate that even for difficult test cases fragment docking can yield enrichments significantly better than random.

  12. Intravitreal Phacoemulsification Using Torsional Handpiece for Retained Lens Fragments

    PubMed Central

    Kumar, Vinod; Takkar, Brijesh

    2016-01-01

    Purpose: To evaluate the results of intravitreal phacoemulsification with torsional hand piece in eyes with posteriorly dislocated lens fragments. Methods: In this prospective, interventional case series, 15 eyes with retained lens fragments following phacoemulsification were included. All patients underwent standard three-port pars plana vitrectomy and intravitreal phacoemulsification using sleeveless, torsional hand piece (OZiL™, Alcon's Infiniti Vision System). Patients were followed up for a minimum of six months to evaluate the visual outcomes and complications. Results: The preoperative best-corrected visual acuity (BCVA) ranged from light perception to 0.3. No complications such as thermal burns of the scleral wound, retinal damage due to flying lens fragments, or difficult lens aspiration occurred during intravitreal phacoemulsification. Mean post-operative BCVA at the final follow-up was 0.5. Two eyes developed cystoid macular edema, which was managed medically. No retinal detachment was noted. Conclusion: Intravitreal phacoemulsification using torsional hand piece is a safe and effective alternative to conventional longitudinal phacofragmentation. PMID:27621783

  13. An algorithm for a semiempirical nuclear fragmentation model

    NASA Technical Reports Server (NTRS)

    Badavi, F. F.; Townsend, L. W.; Wilson, J. W.; Norbury, J. W.

    1987-01-01

    In the present paper, an algorithm for HZE (High Charge and Energy) fragmentation based upon a combination of a two step abrasion/ablation model and electromagnetic dissociation is presented. Development of the model and detailed comparison with available experimental data are given elsewhere. The abrasion process accounts for the removal of nuclear matter in the overlap region of the colliding ions. An average transmission factor is used for the projectile and target nuclei at a given impact parameter to account for the finite mean free path in nuclear matter. The ions are treated otherwise on a geometric basis assuming uniform spheres. The ablation process is treated as a single nucleon-evaporation for every 10 MeV of excitation energy as used by Bowman in the original form of the model. The charge distribution of final fragments are calculated according to the Rudstam formula, except for some correction in mass 5, 8 and 9 fragments which show strong structure effects and correspondingly significant deviation from Rudstam's values. The nuclear electromagnetic dissociation is based on the Weizsacker-Williams (WW) method of virtual quanta where due to its simplicity, the virtual photon spectrum for individual multipoles, and finite extent of the charge distribution are not included. Comparisons of the model are made with the available experimental data here and more extensively elsewhere.

  14. Coordination of dibensothiophenes and corannulenes to organometallic ruthenium (II) fragments

    SciTech Connect

    Vecchi, Paul Anthony

    2005-01-01

    This dissertation contains five papers in the format required for journal publication which describe (in part) my research accomplishments as a graduate student at Iowa State University. This work can be broadly categorized as the binding of weakly-coordinating ligands to cationic organometallic ruthenium fragments, and consists of two main areas of study. Chapters 2-4 are investigations into factors that influence the binding of dibenzothiophenes to [Cp'Ru(CO)2(+ fragments, where Cp' = η5-C5H5 (Cp) and η5-C5Me5 (Cp*). Chapters 5 and 6 present the synthesis and structural characterization of complexes containing corannulene buckybowls that are η6-coordinated to [Cp*Ru(+ fragments. The first chapter contains a brief description of the difficulty in lowering sulfur levels in diesel fuel along with a review of corannulene derivatives and their metal complexes. After the final paper is a short summary of the work herein (Chapter 7). Each chapter is independent, and all equations, schemes, figures, tables, references, and appendices in this dissertation pertain only to the chapter in which they appear.

  15. Fragmentation of ice by low velocity impact

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1982-01-01

    Low-velocity impact experiments (0.14 to 1 km/s) carried out in polycrystalline water ice targets at 257 and 81 K reveal interactions which are assigned to four fragmentation classes: cratering, erosion, disruption, and total fragmentation. The specific kinetic energies for the transitions between these classes are found to be about one to two orders of magnitude below those for silicate rocks. The mass vs. cumulative number distribution of fragments in the experiments is described by a simple power law, similar to that observed in fragmented rocks both in the laboratory and in nature. The logarithmic slopes of cumulative number vs. fragment weight range from -0.9 to -1.8; they decrease with increasing projectile energy and are approximately independent of target temperature. The shapes of fragments resulting from erosion and disruption of ice targets are found to be significantly less spherical for 257 K targets than for 81 K targets. Fragment sphericity increases with increasing projectile energy at 257 K; however, no similar trend is observed for 81 K ice.

  16. Use of antibody fragments (Fv) in immunocytochemistry.

    PubMed

    Kleymann, G; Ostermeier, C; Heitmann, K; Haase, W; Michel, H

    1995-06-01

    We developed a novel antibody fragment (Fv) technique for localization and determination of the surface topology of membrane protein complexes by immunogold electron microscopy. Several hybridoma cell lines producing murine monoclonal antibodies (MAbs) raised against bacterial membrane proteins were established. The cDNAs coding for the variable domains of the MAbs were cloned and expressed in Escherichia coli. The engineered Fv fragments served as trifunctional adapter molecules. The Fv fragment binds to the epitope of the membrane protein. The Strep tag fused to the VH chain was used for one-step affinity purification of the Fv fragments. Immunological detection of the membrane protein-bound Fv fragments in electron microscopy was accomplished either via the Strep tag with colloidal gold-labeled streptavidin or via the c-myc tag, which was fused to the VL chain, in combination with the c-myc tag-specific antibody 9E10 and a colloidal gold-labeled secondary antibody. We examined four Fv fragments directed against the cytochrome c oxidase or the ubiquinol-cytochrome c oxidoreductase of Paracoccus denitrificans and bacteriorhodopsin of Halobacterium halobium to show that this method is generally applicable. In all cases the Fv fragments showed the same results as their corresponding parent antibodies in electron microscopic immunostaining and other applications.

  17. Heavy ion fragmentation experiments at the bevatron

    NASA Technical Reports Server (NTRS)

    Heckman, H. H.

    1976-01-01

    Collaborative research efforts to study the fragmentation processes of heavy nuclei in matter using heavy ion beams of the Bevatron/Bevalac are described. The goal of the program is to obtain the single particle inclusive spectra of secondary nuclei produced at 0 deg by the fragmentation of heavy ion beam projectiles. The process being examined is B+T yields F + anything, where B is the beam nucleus, T is the target nucleus, and F is the detected fragment. The fragments F are isotopically identified by experimental procedures involving magnetic analysis, energy loss and time-of-flight measurements. Effects were also made to: (a) study processes of heavy nuclei in matter, (b) measure the total and partial production cross section for all isotopes, (c) test the applicability of high energy multiparticle interaction theory to nuclear fragmentation, (d) apply the cross section data and fragmentation probabilities to cosmic ray transport theory, and (e) search for systematic behavior of fragment production as a means to improve existing semi-empirical theories of cross-sections.

  18. Simulation of collisional fragmentation with explosives

    NASA Technical Reports Server (NTRS)

    Housen, Kevin

    1993-01-01

    For practical reasons, experimental studies of collisional fragmentation must at times rely on explosives to fragment a target body. For example, Housen et al., described experiments in which spheres were fragmented in a pressurized atmosphere. Explosives were used because impacts could not be performed in the pressure chamber. Explosives can also be used to study targets much larger than those which can be disrupted by conventional light-gas guns, thereby allowing size- and rate-effects to be investigated. The purpose of this study is to determine the charge burial depth required to simulate various aspects of collisions.

  19. Prediction of fragment velocities and trajectories

    NASA Technical Reports Server (NTRS)

    Kulesz, J. J.; Vargas, L. M.; Moseley, P. K.

    1979-01-01

    Analytical techniques are described which predict: (1) the velocities of two unequal fragments from bursting cylindrical pressure vessels; (2) the velocity and range of portions of vessels containing a fluid which, when the vessel ruptures, causes the fragment to accelerate as the fluid changes from the liquid to the gaseous phase; and (3) the ranges of fragments subjected to drag and lift forces during flight. Numerous computer runs were made with various initial conditions in an effort to generalize the results for maximum range in plots of dimensionless range versus dimensionless velocity.

  20. Bone fragments a body can make

    SciTech Connect

    Stout, S.D.; Ross, L.M. Jr. )

    1991-05-01

    Data obtained from various analytical techniques applied to a number of small bone fragments recovered from a crime scene were used to provide evidence for the occurrence of a fatality. Microscopic and histomorphometric analyses confirmed that the fragments were from a human skull. X-ray microanalysis of darkened areas on the bone fragments revealed a chemical signature that matched the chemical signature of a shotgun pellet recovered at the scene of the crime. The above findings supported the deoxyribonucleic acid (DNA) fingerprint evidence which, along with other evidence, was used to convict a man for the murder of his wife, even though her body was never recovered.

  1. The late effect of grenade fragments.

    PubMed

    Symonds, R P; Mackay, C; Morley, P

    1985-06-01

    Following the explosion of a grenade or shell, the victim may be peppered with literally hundreds of pieces of metal. Troublesome fragments which perforate a major viscus may be removed but others are often left behind, as it is felt (usually correctly) that these fragments will cause no harm. We describe a case in which a grenade fragment received 16 years previously pierced the large bowel. A psoas abscess developed which was located by ultrasound. Pus was aspirated under ultrasound control and the lesion was successfully treated by antibiotics.

  2. DNA sequence from Cretaceous period bone fragments.

    PubMed

    Woodward, S R; Weyand, N J; Bunnell, M

    1994-11-18

    DNA was extracted from 80-million-year-old bone fragments found in strata of the Upper Cretaceous Blackhawk Formation in the roof of an underground coal mine in eastern Utah. This DNA was used as the template in a polymerase chain reaction that amplified and sequenced a portion of the gene encoding mitochondrial cytochrome b. These sequences differ from all other cytochrome b sequences investigated, including those in the GenBank and European Molecular Biology Laboratory databases. DNA isolated from these bone fragments and the resulting gene sequences demonstrate that small fragments of DNA may survive in bone for millions of years.

  3. Fission Fragment Properties from a Microscopic Approach

    SciTech Connect

    Dubray, N.; Goutte, H.; Delaroche, J.-P.

    2008-04-17

    We calculate potential energy surfaces in the elongation-asymmetry plane, up to very large deformations, with the Hartree-Fock-Bogoliubov method and the Gogny nucleon-nucleon effective interaction DIS, for the {sup 226}Th and {sup 256,258,260}Fm fissioning systems. We then define a criterion based on the nuclear density, in order to discriminate between pre- and post-scission configurations. Using this criterion, many scission configurations are identified, and are used for the calculation of several fragment properties, like fragment deformations, deformation energies, energy partitioning, neutron binding energies at scission, charge polarization, total fragment kinetic energies and neutron multiplicities.

  4. Protein-templated fragment ligations - from molecular recognition to drug discovery.

    PubMed

    Jaegle, Mike; Wong, Ee Lin; Tauber, Carolin; Nawrotzky, Eric; Arkona, Christoph; Rademann, Jörg

    2017-01-24

    The understanding and manipulation of molecular recognition events is the key to modern approaches in drug discovery. Protein-templated fragment ligation is a novel concept to support drug discovery and can help to improve the efficacy of already existing protein ligands. Protein-templated fragment ligations are chemical reactions between small molecules ("fragments") that utilize a protein´s surface as a template to combine and to form a protein ligand with increased binding affinity. The approach exploits the molecular recognition of reactive small molecule fragments by proteins both for ligand assembly and for the identification of bioactive fragment combinations. Chemical synthesis and bioassay are thus integrated in one single step. In this article we portrait the biophysical basis of reversible and irreversible fragment ligations and the available methods to detect protein-templated ligation products. The scope of known chemical reactions providing templated ligation products is reviewed and the possibilities to extend the reaction portfolio are discussed. Selected recent applications of the method in protein ligand discovery are reported. Finally, the strengths and limitations of the concept are discussed and an outlook on the future impact of templated fragment ligations on the drug discovery process is given.

  5. The multiple roles of computational chemistry in fragment-based drug design

    NASA Astrophysics Data System (ADS)

    Law, Richard; Barker, Oliver; Barker, John J.; Hesterkamp, Thomas; Godemann, Robert; Andersen, Ole; Fryatt, Tara; Courtney, Steve; Hallett, Dave; Whittaker, Mark

    2009-08-01

    Fragment-based drug discovery (FBDD) represents a change in strategy from the screening of molecules with higher molecular weights and physical properties more akin to fully drug-like compounds, to the screening of smaller, less complex molecules. This is because it has been recognised that fragment hit molecules can be efficiently grown and optimised into leads, particularly after the binding mode to the target protein has been first determined by 3D structural elucidation, e.g. by NMR or X-ray crystallography. Several studies have shown that medicinal chemistry optimisation of an already drug-like hit or lead compound can result in a final compound with too high molecular weight and lipophilicity. The evolution of a lower molecular weight fragment hit therefore represents an attractive alternative approach to optimisation as it allows better control of compound properties. Computational chemistry can play an important role both prior to a fragment screen, in producing a target focussed fragment library, and post-screening in the evolution of a drug-like molecule from a fragment hit, both with and without the available fragment-target co-complex structure. We will review many of the current developments in the area and illustrate with some recent examples from successful FBDD discovery projects that we have conducted.

  6. The multiple roles of computational chemistry in fragment-based drug design.

    PubMed

    Law, Richard; Barker, Oliver; Barker, John J; Hesterkamp, Thomas; Godemann, Robert; Andersen, Ole; Fryatt, Tara; Courtney, Steve; Hallett, Dave; Whittaker, Mark

    2009-08-01

    Fragment-based drug discovery (FBDD) represents a change in strategy from the screening of molecules with higher molecular weights and physical properties more akin to fully drug-like compounds, to the screening of smaller, less complex molecules. This is because it has been recognised that fragment hit molecules can be efficiently grown and optimised into leads, particularly after the binding mode to the target protein has been first determined by 3D structural elucidation, e.g. by NMR or X-ray crystallography. Several studies have shown that medicinal chemistry optimisation of an already drug-like hit or lead compound can result in a final compound with too high molecular weight and lipophilicity. The evolution of a lower molecular weight fragment hit therefore represents an attractive alternative approach to optimisation as it allows better control of compound properties. Computational chemistry can play an important role both prior to a fragment screen, in producing a target focussed fragment library, and post-screening in the evolution of a drug-like molecule from a fragment hit, both with and without the available fragment-target co-complex structure. We will review many of the current developments in the area and illustrate with some recent examples from successful FBDD discovery projects that we have conducted.

  7. Simulated effects of habitat loss and fragmentation on a solitary, mustellid predator

    SciTech Connect

    Jager, Yetta; Carr, Eric A; Efroymson, Rebecca Ann

    2005-01-01

    Brine spills associated with petroleum extraction can reduce the amount of suitable habitat and increase habitat fragmentation for many terrestrial animals. We conducted a simulation study to quantify the effects of habitat loss and fragmentation on a solitary mammal predator. To provide focus, we adopted biological attributes of the American badger (Taxidea taxus) and environmental attributes of the Tallgrass Prairie Preserve in Oklahoma. We simulated badger activities on landscapes with different degrees of habitat loss and fragmentation using a spatially explicit and individual-based population model. Both habitat loss and fragmentation increased the incidence of habitat-related mortality and decreased the proportion of eligible females that mated, which decreased final population sizes and the likelihood of persistence. Parameter exploration suggested that steep, threshold-like, responses to habitat loss occurred when animals included high-risk habitat in their territories. Badger populations showed a steeper decline with increasing habitat loss on landscapes fragmented by spills than on less fragmented landscapes. Habitat fragmentation made it difficult for badgers to form high-quality territories, and exposed individuals to higher risk while seeking to establish a territory. Our simulations also suggest that an inability to find mates (an Allee effect) becomes increasingly important for landscapes that support a sparse distribution of territories. Thus, the presence of unmated females with territories may foreshadow population decline in solitary species that do not normally tolerate marginal adults.

  8. Enhanced multiparametric hyaluronan degradation for production of molar-mass-defined fragments.

    PubMed

    Holubova, Lucie; Korecka, Lucie; Podzimek, Stepan; Moravcova, Veronika; Rotkova, Jana; Ehlova, Tereza; Velebny, Vladimir; Bilkova, Zuzana

    2014-11-04

    Hyaluronic acid (HA) is known to serve as a dynamic mediator intervening in many physiological functions. Its specific effect has been repeatedly confirmed to be strongly influenced by the molecular size of hyaluronan fragments. However common technological approaches of HA fragments production have their limitations. In many cases, the final products do not meet the strict pharmaceutical requirements, specifically due to size polydispersity and reaction contaminants. We present novel methodology based on combination of unique incidental ability of the plant-derived protease papain to split the glycosidic bonds and an indispensable advantages of biocompatible macroporous material with incorporated ferrous ions serving as carrier for covalent papain fixation. This atypical and yet unpublished highly efficient multiparametric approach allows enhanced HA fragmentation for easily and safely producing molar-mass-defined HA fragments with narrow size distribution. Native polyacrylamide gel electrophoresis (PAGE) and size exclusion chromatography/multi-angle light scattering (SEC-MALS) confirmed the effectiveness of our multiparametric approach.

  9. Quantification of DNA fragmentation in processed foods using real-time PCR.

    PubMed

    Mano, Junichi; Nishitsuji, Yasuyuki; Kikuchi, Yosuke; Fukudome, Shin-Ichi; Hayashida, Takuya; Kawakami, Hiroyuki; Kurimoto, Youichi; Noguchi, Akio; Kondo, Kazunari; Teshima, Reiko; Takabatake, Reona; Kitta, Kazumi

    2017-07-01

    DNA analysis of processed foods is performed widely to detect various targets, such as genetically modified organisms (GMOs). Food processing often causes DNA fragmentation, which consequently affects the results of PCR analysis. In order to assess the effects of DNA fragmentation on the reliability of PCR analysis, we investigated a novel methodology to quantify the degree of DNA fragmentation. We designed four real-time PCR assays that amplified 18S ribosomal RNA gene sequences common to various plants at lengths of approximately 100, 200, 400, and 800 base pairs (bp). Then, we created an indicator value, "DNA fragmentation index (DFI)", which is calculated from the Cq values derived from the real-time PCR assays. Finally, we demonstrated the efficacy of this method for the quality control of GMO detection in processed foods by evaluating the relationship between the DFI and the limit of detection.

  10. Final Report

    SciTech Connect

    Webb, Robert C.; Kamon, Teruki; Toback, David; Safonov, Alexei; Dutta, Bhaskar; Dimitri, Nanopoulos; Pope, Christopher; White, James

    2013-11-18

    Overview The High Energy Physics Group at Texas A&M University is submitting this final report for our grant number DE-FG02-95ER40917. This grant has supported our wide range of research activities for over a decade. The reports contained here summarize the latest work done by our research team. Task A (Collider Physics Program): CMS & CDF Profs. T. Kamon, A. Safonov, and D. Toback co-lead the Texas A&M (TAMU) collider program focusing on CDF and CMS experiments. Task D: Particle Physics Theory Our particle physics theory task is the combined effort of Profs. B. Dutta, D. Nanopoulos, and C. Pope. Task E (Underground Physics): LUX & NEXT Profs. R. Webb and J. White(deceased) lead the Xenon-based underground research program consisting of two main thrusts: the first, participation in the LUX two-phase xenon dark matter search experiment and the second, detector R&D primarily aimed at developing future detectors for underground physics (e.g. NEXT and LZ).

  11. History of on-orbit satellite fragmentations

    NASA Technical Reports Server (NTRS)

    Johnson, N. L.; Gabbard, J. R.; Devere, G. T.; Johnson, E. E.

    1984-01-01

    The causes of on-orbit fragmentations are varied and may be intentional or accidental. The cause of many fragmentations remains unknown. While a few cases are currently under investigation as on-orbit collision candidates, man is directly responsible for the vast majority of artificial debris polluting the near-Earth space environment. It should be emphasized that the number of fragments listed with each event in this document represent only those debris officially cataloged by NORAD. Each known on-orbit satellite fragementation is described within this document in module format. Also listed are pertinent characteristics of each fragmentation event. Comments regarding the nature of the satellite and additional details of the events are given.

  12. Gravitational fragmentation of the Carina Flare supershell

    NASA Astrophysics Data System (ADS)

    Wünsch, Richard

    2015-03-01

    We study the gravitational fragmentation of a thick shell comparing the analytical theory to 3D hydrodynamic simulations and to observations of the Carina Flare supershell. We use both grid-based (AMR) and particle-based (SPH) codes to follow the idealised model of the fragmenting shell and found an excellent agreement between the two codes. Growth rates of fragments at different wavelength are well described by the pressure assisted gravitational instability (PAGI) - a new theory of the thick shell fragmentation. Using the APEX telescope we observe a part of the surface of the Carina Flare supershell (GSH287+04-17) in the 13CO(2-1) line. We apply a new clump-finding algorithm DENDROFIND to identify 50 clumps. We determine the clump mass function and we construct the minimum spanning tree connecting clumps positions to estimate the typical distance among clumps. We conclude that the observed masses and distances correspond well to the prediction of PAGI.

  13. Universal Dynamic Fragmentation in D Dimensions

    NASA Astrophysics Data System (ADS)

    Âström, J. A.; Ouchterlony, F.; Linna, R. P.; Timonen, J.

    2004-06-01

    A generic model is introduced for brittle fragmentation in D dimensions, and this model is shown to lead to a fragment-size distribution with two distinct components. In the small fragment-size limit a scale-invariant size distribution results from a crack branching-merging process. At larger sizes the distribution becomes exponential as a result of a Poisson process, which introduces a large-scale cutoff. Numerical simulations are used to demonstrate the validity of the distribution for D=2. Data from laboratory-scale experiments and large-scale quarry blastings of granitic gneiss confirm its validity for D=3. In the experiments the nonzero grain size of rock causes deviation from the ideal model distribution in the small-size limit. The size of the cutoff seems to diverge at the minimum energy sufficient for fragmentation to occur, but the scaling exponent is not universal.

  14. Fragment Length of Circulating Tumor DNA.

    PubMed

    Underhill, Hunter R; Kitzman, Jacob O; Hellwig, Sabine; Welker, Noah C; Daza, Riza; Baker, Daniel N; Gligorich, Keith M; Rostomily, Robert C; Bronner, Mary P; Shendure, Jay

    2016-07-01

    Malignant tumors shed DNA into the circulation. The transient half-life of circulating tumor DNA (ctDNA) may afford the opportunity to diagnose, monitor recurrence, and evaluate response to therapy solely through a non-invasive blood draw. However, detecting ctDNA against the normally occurring background of cell-free DNA derived from healthy cells has proven challenging, particularly in non-metastatic solid tumors. In this study, distinct differences in fragment length size between ctDNAs and normal cell-free DNA are defined. Human ctDNA in rat plasma derived from human glioblastoma multiforme stem-like cells in the rat brain and human hepatocellular carcinoma in the rat flank were found to have a shorter principal fragment length than the background rat cell-free DNA (134-144 bp vs. 167 bp, respectively). Subsequently, a similar shift in the fragment length of ctDNA in humans with melanoma and lung cancer was identified compared to healthy controls. Comparison of fragment lengths from cell-free DNA between a melanoma patient and healthy controls found that the BRAF V600E mutant allele occurred more commonly at a shorter fragment length than the fragment length of the wild-type allele (132-145 bp vs. 165 bp, respectively). Moreover, size-selecting for shorter cell-free DNA fragment lengths substantially increased the EGFR T790M mutant allele frequency in human lung cancer. These findings provide compelling evidence that experimental or bioinformatic isolation of a specific subset of fragment lengths from cell-free DNA may improve detection of ctDNA.

  15. Observations of Titan IIIC Transtage Fragmentation Debris

    NASA Astrophysics Data System (ADS)

    Cowardin, H.; Buckalew, B.; Barker, E.; Abercromby, K.; Seitzer, P.; Cardona, T.; Krisko, P.; Lederer, S.

    2013-09-01

    The fragmentation of a Titan IIIC Transtage (1968-081) on 21 February 1992 is one of only two known break-ups in or near geosynchronous orbit. The original rocket body and 24 pieces of debris are currently being tracked by the U. S. Space Surveillance Network (SSN). The rocket body (SSN# 3432) and several of the original fragments (SSN# 25000, 25001, 30000, and 33511) were observed in survey mode during 2004-2010 using the 0.6 m Michigan Orbital DEbris Survey Telescope (MODEST) in Chile using a broad R filter. This paper presents a size distribution for all calibrated magnitude data acquired on MODEST. Size distribution plots are also shown using historical models for small fragmentation debris (down to 10 cm) thought to be associated with the Titan Transtage break-up. In November 2010, visible broadband photometry (Johnson/Kron-Cousins BVRI) was acquired with the 0.9 m Small and Moderate Aperture Research Telescope System (SMARTS) at the Cerro Tololo Inter-American Observatory (CTIO) in Chile on several Titan fragments (SSN 25001, 33509, and 33510) and the parent rocket body (SSN 3432). Color index data are used to determine the fragment brightness distribution and how the data compares to spacecraft materials measured in the laboratory using similar photometric measurement techniques. In order to better characterize the break-up fragments, spectral measurements were acquired on three Titan fragments (one fragment observed over two different time periods) using the 6.5-m Magellan telescopes at Las Campanas Observatory in Chile. The telescopic spectra of SSN 25000 (May 2012 and January 2013), SSN 38690, and SSN 38699 are compared with laboratory acquired spectra of materials (e.g., aluminum and various paints) to determine the surface material.

  16. Measuring the photon fragmentation function at LEP

    NASA Astrophysics Data System (ADS)

    Glover, E. W. N.; Morgan, A. G.

    1994-06-01

    Using an algorithm that treats photons and hadrons democratically, we discuss how the quark to photon fragmentation function, D q →γ, might be measured in ‘photon’ + jet events at LEP. Simple analytic results are given at lowest order. The possibility of determining the gluon to photon fragmentation function, D g →γ, in ‘photon’ + 2 jet events is also discussed, however, the prospects for doing so seem bleak.

  17. Observations of Titan IIIC Transtage Fragmentation Debris

    NASA Technical Reports Server (NTRS)

    Cowardin, Heather; Seitzer, P.; Abercromby, K.; Barker, E.; Buckalew, B.; Cardona, T.; Krisko, P.; Lederer, S.

    2013-01-01

    The fragmentation of a Titan IIIC Transtage (1968-081) on 21 February 1992 is one of only two known break-ups in or near geosynchronous orbit. The original rocket body and 24 pieces of debris are currently being tracked by the U. S. Space Surveillance Network (SSN). The rocket body (SSN# 3432) and several of the original fragments (SSN# 25000, 25001, 30000, and 33511) were observed in survey mode during 2004-2010 using the 0.6-m Michigan Orbital DEbris Survey Telescope (MODEST) in Chile using a broad R filter. This paper presents a size distribution for all calibrated magnitude data acquired on MODEST. Size distribution plots are also shown using historical models for small fragmentation debris (down to 10 cm) thought to be associated with the Titan Transtage break-up. In November 2010, visible broadband photometry (Johnson/Kron-Cousins BVRI) was acquired with the 0.9-m Small and Moderate Aperture Research Telescope System (SMARTS) at the Cerro Tololo Inter-American Observatory (CTIO) in Chile on several Titan fragments (SSN 25001, 33509, and 33510) and the parent rocket body (SSN 3432). Color index data are used to determine the fragment brightness distribution and how the data compares to spacecraft materials measured in the laboratory using similar photometric measurement techniques. In order to better characterize the break-up fragments, spectral measurements were acquired on three Titan fragments (one fragment observed over two different time periods) using the 6.5-m Magellan telescopes at Las Campanas Observatory in Chile. The telescopic spectra of SSN 25000 (May 2012 and January 2013), SSN 38690, and SSN 38699 are compared with laboratory acquired spectra of materials (e.g., aluminum and various paints) to determine the surface material.

  18. Fragment Length of Circulating Tumor DNA

    PubMed Central

    Underhill, Hunter R.; Kitzman, Jacob O.; Hellwig, Sabine; Welker, Noah C.; Daza, Riza; Gligorich, Keith M.; Rostomily, Robert C.; Shendure, Jay

    2016-01-01

    Malignant tumors shed DNA into the circulation. The transient half-life of circulating tumor DNA (ctDNA) may afford the opportunity to diagnose, monitor recurrence, and evaluate response to therapy solely through a non-invasive blood draw. However, detecting ctDNA against the normally occurring background of cell-free DNA derived from healthy cells has proven challenging, particularly in non-metastatic solid tumors. In this study, distinct differences in fragment length size between ctDNAs and normal cell-free DNA are defined. Human ctDNA in rat plasma derived from human glioblastoma multiforme stem-like cells in the rat brain and human hepatocellular carcinoma in the rat flank were found to have a shorter principal fragment length than the background rat cell-free DNA (134–144 bp vs. 167 bp, respectively). Subsequently, a similar shift in the fragment length of ctDNA in humans with melanoma and lung cancer was identified compared to healthy controls. Comparison of fragment lengths from cell-free DNA between a melanoma patient and healthy controls found that the BRAF V600E mutant allele occurred more commonly at a shorter fragment length than the fragment length of the wild-type allele (132–145 bp vs. 165 bp, respectively). Moreover, size-selecting for shorter cell-free DNA fragment lengths substantially increased the EGFR T790M mutant allele frequency in human lung cancer. These findings provide compelling evidence that experimental or bioinformatic isolation of a specific subset of fragment lengths from cell-free DNA may improve detection of ctDNA. PMID:27428049

  19. Factors Controlling the Fragmentation Behavior of Magma

    NASA Astrophysics Data System (ADS)

    Richard, D.; Scheu, B.; Mueller, S.; Spieler, O.; Dingwell, D. B.

    2006-12-01

    Five volcanoes of explosive eruptive behavior from the Ring of Fire were selected to investigate the processes responsible for their degree of explosivity and eruptive style. These volcanoes are Colima, (Mexico), St. Augustine (USA), Bezymianny (Russia), Krakatau and Kelut (Indonesia). In an attempt to better understand the processes controlling fragmentation at these volcanoes, we performed shock-tube experiments with natural samples from these volcanoes at overpressures between 4 and 35 MPa at room temperature. Both fragmentation threshold and speed of fragmentation were determined. Previous studies have already shown that porosity is a first order parameter in eruption models and our recent results support this statement. However, it is clear that other factors such as permeability need to be considered to explain variations observed in fragmentation behavior. Colima sample series of 24 % porosity require overpressures of over 11 MPa to fragment, whereas other Colima sample series of 15 % porosity require overpressures of only 8 MPa to fragment. Permeability measurements confirmed a permeability of about one order of magnitude higher for the samples of 24 % porosity. However, this information alone does not necessarily provide an explanation for the large scatter seen in the fragmentation speed data within one sample series. Experimental data will be supported by textural microscopic analyses in order to provide more constraints on the dominant factors responsible for the scatter in fragmentation behavior. Explaining this scatter will help to shed light on the respective eruptive behavior of the investigated volcanoes and thus help to understand why, at the first glance, very "similar" volcanic systems may react in very different ways. This work is part of the BMBF project SUNDAARC, which aims to quantify the potential risk of selected highly-explosive volcanoes by combining field and laboratory investigations.

  20. Ebstein Anomaly With QRS Fragmentation on Electrocardiogram

    PubMed Central

    Acharya, Prakash; Ang, Jonathan Ross; Gitler, Bernard

    2017-01-01

    Ebstein anomaly is a rare congenital disorder that involves the tricuspid valve and the right ventricle. It is associated with interatrial communication, which allows for paradoxical embolization causing unilateral blindness. Abnormal conduction through the atrialized right ventricle leads to QRS fragmentation on electrocardiogram. Its presence suggests a more severe abnormality and a higher risk of arrhythmia. The QRS fragmentation disappears after corrective surgery with resection of the atrialized right ventricle. PMID:28203575

  1. Ebstein Anomaly With QRS Fragmentation on Electrocardiogram.

    PubMed

    Acharya, Prakash; Ang, Jonathan Ross; Gitler, Bernard

    2017-01-01

    Ebstein anomaly is a rare congenital disorder that involves the tricuspid valve and the right ventricle. It is associated with interatrial communication, which allows for paradoxical embolization causing unilateral blindness. Abnormal conduction through the atrialized right ventricle leads to QRS fragmentation on electrocardiogram. Its presence suggests a more severe abnormality and a higher risk of arrhythmia. The QRS fragmentation disappears after corrective surgery with resection of the atrialized right ventricle.

  2. Relationships between Liquid Atomization and Solid Fragmentation

    DTIC Science & Technology

    2016-03-01

    Relationships between Liquid Atomization and Solid Fragmentation Approved for public release; distribution is unlimited. March 2016...4.535 924 × 10 –1 kilogram (kg) unified atomic mass unit (amu) 1.660 539 × 10 –27 kilogram (kg) pound-mass per cubic foot (lb ft –3 ) 1.601 846 × 10...penetrate and pinch off fragments. For example, for jet atomization , Marmottant & Villermaux (2004b) say: “Liquid destabilization proceeds from a two

  3. Electroweak fragmentation functions for dark matter annihilation

    SciTech Connect

    Cavasonza, Leila Ali; Krämer, Michael; Pellen, Mathieu

    2015-02-18

    Electroweak corrections can play a crucial role in dark matter annihilation. The emission of gauge bosons, in particular, leads to a secondary flux consisting of all Standard Model particles, and may be described by electroweak fragmentation functions. To assess the quality of the fragmentation function approximation to electroweak radiation in dark matter annihilation, we have calculated the flux of secondary particles from gauge-boson emission in models with Majorana fermion and vector dark matter, respectively. For both models, we have compared cross sections and energy spectra of positrons and antiprotons after propagation through the galactic halo in the fragmentation function approximation and in the full calculation. Fragmentation functions fail to describe the particle fluxes in the case of Majorana fermion annihilation into light fermions: the helicity suppression of the lowest-order cross section in such models cannot be lifted by the leading logarithmic contributions included in the fragmentation function approach. However, for other classes of models like vector dark matter, where the lowest-order cross section is not suppressed, electroweak fragmentation functions provide a simple, model-independent and accurate description of secondary particle fluxes.

  4. Microstructural characterization of pipe bomb fragments

    SciTech Connect

    Gregory, Otto; Oxley, Jimmie; Smith, James; Platek, Michael; Ghonem, Hamouda; Bernier, Evan; Downey, Markus; Cumminskey, Christopher

    2010-03-15

    Recovered pipe bomb fragments, exploded under controlled conditions, have been characterized using scanning electron microscopy, optical microscopy and microhardness. Specifically, this paper examines the microstructural changes in plain carbon-steel fragments collected after the controlled explosion of galvanized, schedule 40, continuously welded, steel pipes filled with various smokeless powders. A number of microstructural changes were observed in the recovered pipe fragments: deformation of the soft alpha-ferrite grains, deformation of pearlite colonies, twin formation, bands of distorted pearlite colonies, slip bands, and cross-slip bands. These microstructural changes were correlated with the relative energy of the smokeless powder fillers. The energy of the smokeless powder was reflected in a reduction in thickness of the pipe fragments (due to plastic strain prior to fracture) and an increase in microhardness. Moreover, within fragments from a single pipe, there was a radial variation in microhardness, with the microhardness at the outer wall being greater than that at the inner wall. These findings were consistent with the premise that, with the high energy fillers, extensive plastic deformation and wall thinning occurred prior to pipe fracture. Ultimately, the information collected from this investigation will be used to develop a database, where the fragment microstructure and microhardness will be correlated with type of explosive filler and bomb design. Some analyses, specifically wall thinning and microhardness, may aid in field characterization of explosive devices.

  5. Fragmentation of metal particles during heterogeneous explosion

    NASA Astrophysics Data System (ADS)

    Ripley, R. C.; Donahue, L.; Zhang, F.

    2015-03-01

    Heterogeneous explosives contain a mixture of standard explosive material and reactive metal particles. The inclusion of metal particles alters the energy density and energy release timescales involved in the blast event. Available experimental evidence indicates that metal particles may be damaged or fragmented during heterogeneous blast, altering the distribution of particle sizes from their initial state. This paper discusses adaptation and application of fragmentation theory and physical models for particle damage during condensed matter detonation, aerodynamic breakup of molten particles, and particle impact fragmentation with nearby structures. The shock compression and impact fragmentation models are based on the energy methods for dynamic fragmentation by Grady and Kipp, while aerodynamic breakup is treated according to Weber number stability criteria for droplets. These particle fragmentation models are validated against fundamental test cases from the literature. The models are then applied to heterogeneous blast scenarios including free field and wall reflection in a semi-confined urban street. Comparison with experimental records of pressure shows good agreement despite challenges inherent in the complexity of heterogeneous blast measurement and multiphase simulation.

  6. Implications of promiscuous Pim-1 kinase fragment inhibitor hydrophobic interactions for fragment-based drug design.

    PubMed

    Good, Andrew C; Liu, Jinyu; Hirth, Bradford; Asmussen, Gary; Xiang, Yibin; Biemann, Hans-Peter; Bishop, Kimberly A; Fremgen, Trisha; Fitzgerald, Maria; Gladysheva, Tatiana; Jain, Annuradha; Jancsics, Katherine; Metz, Markus; Papoulis, Andrew; Skerlj, Renato; Stepp, J David; Wei, Ronnie R

    2012-03-22

    We have studied the subtleties of fragment docking and binding using data generated in a Pim-1 kinase inhibitor program. Crystallographic and docking data analyses have been undertaken using inhibitor complexes derived from an in-house surface plasmon resonance (SPR) fragment screen, a virtual needle screen, and a de novo designed fragment inhibitor hybrid. These investigations highlight that fragments that do not fill their binding pocket can exhibit promiscuous hydrophobic interactions due to the lack of steric constraints imposed on them by the boundaries of said pocket. As a result, docking modes that disagree with an observed crystal structure but maintain key crystallographically observed hydrogen bonds still have potential value in ligand design and optimization. This observation runs counter to the lore in fragment-based drug design that all fragment elaboration must be based on the parent crystal structure alone.

  7. Shuttle data book: SRM fragment velocity model. Presented to the SRB Fragment Model Review Panel

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This study was undertaken to determine the velocity of fragments generated by the range safety destruction (RSD) or random failure of a Space Transportation System (STS) Solid Rocket Motor (SRM). The specific requirement was to provide a fragment model for use in those Galileo and Ulysses RTG safety analyses concerned with possible fragment impact on the spacecraft radioisotope thermoelectric generators (RTGS). Good agreement was obtained between predictions and observations for fragment velocity, velocity distributions, azimuths, and rotation rates. Based on this agreement with the entire data base, the model was used to predict the probable fragment environments which would occur in the event of an STS-SRM RSD or randon failure at 10, 74, 84 and 110 seconds. The results of these predictions are the basis of the fragment environments presented in the Shuttle Data Book (NSTS-08116). The information presented here is in viewgraph form.

  8. Fragment library design: using cheminformatics and expert chemists to fill gaps in existing fragment libraries.

    PubMed

    Kutchukian, Peter S; So, Sung-Sau; Fischer, Christian; Waller, Chris L

    2015-01-01

    Fragment based screening (FBS) has emerged as a mainstream lead discovery strategy in academia, biotechnology start-ups, and large pharma. As a prerequisite of FBS, a structurally diverse library of fragments is desirable in order to identify chemical matter that will interact with the range of diverse target classes that are prosecuted in contemporary screening campaigns. In addition, it is also desirable to offer synthetically amenable starting points to increase the probability of a successful fragment evolution through medicinal chemistry. Herein we describe a method to identify biologically relevant chemical substructures that are missing from an existing fragment library (chemical gaps), and organize these chemical gaps hierarchically so that medicinal chemists can efficiently navigate the prioritized chemical space and subsequently select purchasable fragments for inclusion in an enhanced fragment library.

  9. Development and Evaluation of an Automatic Fragment-Weighing Apparatus,

    DTIC Science & Technology

    1980-12-01

    mainly attributable to the large variation in size and geometry of the fragments and the need to separate and feed each of the fragments singly onto the...for separating and feeding the fragments to the balance pan Fragments introduced into the vibrating sorter are forced to travel slowly upwards along...Fragment feed rate from the spiral can be further controlled by the amplitude of vibration of the spiral (speed of fragment ascent) as well as the

  10. The Conversion of Smaller Borane Fragments to Larger Structures. Systematics of Boron Hydride Reactions.

    DTIC Science & Technology

    1984-12-31

    Robert W. Parry and Goji Kodama Contract DAAG-29-8rl-K-Ol0l S. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK S Department of...Entered; THE CONVERSION OF SMALLER BORANE FRAGMENTS TO LARGER STRUCTURES - SYSTEMATICS OF BORON HYDRIDE REACTIONS FINAL REPORT ROBERT W. PARRY AND GOJI

  11. Hypervelocity Impact Test Fragment Modeling: Modifications to the Fragment Rotation Analysis and Lightcurve Code

    NASA Technical Reports Server (NTRS)

    Gouge, Michael F.

    2011-01-01

    Hypervelocity impact tests on test satellites are performed by members of the orbital debris scientific community in order to understand and typify the on-orbit collision breakup process. By analysis of these test satellite fragments, the fragment size and mass distributions are derived and incorporated into various orbital debris models. These same fragments are currently being put to new use using emerging technologies. Digital models of these fragments are created using a laser scanner. A group of computer programs referred to as the Fragment Rotation Analysis and Lightcurve code uses these digital representations in a multitude of ways that describe, measure, and model on-orbit fragments and fragment behavior. The Dynamic Rotation subroutine generates all of the possible reflected intensities from a scanned fragment as if it were observed to rotate dynamically while in orbit about the Earth. This calls an additional subroutine that graphically displays the intensities and the resulting frequency of those intensities as a range of solar phase angles in a Probability Density Function plot. This document reports the additions and modifications to the subset of the Fragment Rotation Analysis and Lightcurve concerned with the Dynamic Rotation and Probability Density Function plotting subroutines.

  12. On the fragmentation of biomolecules: Fragmentation of alanine dipeptide along the polypeptide chain

    SciTech Connect

    Solov'yov, I. A. Yakubovich, A. V.; Solov'yov, A. V.; Greiner, W.

    2006-09-15

    The interaction potential between amino acids in alanine dipeptide has been studied for the first time taking into account exact molecular geometry. Ab initio calculation has been performed in the framework of density functional theory taking into account all electrons in the system. The fragmentation of dipeptide along the polypeptide chain, as well as the interaction between alanines, has been considered. The energy of the system has been analyzed as a function of the distance between fragments for all possible dipeptide fragmentation channels. Analysis of the energy barriers makes it possible to estimate the characteristic fragmentation times and to determine the degree of applicability of classical electrodynamics for describing the system energy.

  13. Final report

    SciTech Connect

    Dobbs, Fred C.

    2003-01-15

    species of flagellates, Spumella sp. and Bodo sp. (identifications are tentative) were isolated from South Oyster sediments by repetitive serial dilution/extinction method. Protistan cells were cultured with Cereal leaf Prescott medium and pelleted by centrifugation. Protistan DNAs were extracted with a DNA extraction kit (Sigma Co.) and the sequencing of their SSrDNA is underway. Finally, to follow up on our collaboration of Dr. Bill Johnson (Univ. of Utah), one of the co-PIs under the same NABIR umbrella, we are pleased to report we have successfully tested antibody-ferrographic capture of protists (See previous year's report for more background). Polyclonal FITC-conjugated antibody specific for a flagellate, Spumella sp., was produced by Rockland Inc., and we now are able to enumerate that species using ferrographic capture. There are, however, some issues of non-specific staining that remain to be resolved.

  14. History of on-orbit satellite fragmentations

    NASA Technical Reports Server (NTRS)

    Nauer, David J.

    1992-01-01

    Since the first serious satellite fragmentation occurred in Jun. 1961, and instantaneously increased the total Earth satellite population by more than 400 percent, the issue of space operations within the finite region of space around the Earth has been the subject of increasing interest and concern. The prolific satellite fragmentations of the 1970's and the marked increase in the number of fragmentations in the 1980's served to widen international research into the characteristics and consequences of such events. Plans for large, manned space stations in the next decade and beyond demand a better understanding of the hazards of the dynamic Earth satellite population. The contribution of satellite fragmentations to the growth of the Earth satellite population is complex and varied. The majority of detectable fragmentation debris have already fallen out of orbit, and the effects of 40 percent of all fragmentations have completely disappeared. In this volume, satellite fragmentations are categorized by their assessed nature and to a lesser degree by their effect on the near-Earth space environment. A satellite breakup is the usually destructive disassociation of an orbital payload, rocket body, or structure, often with a wide range of ejecta velocities. A satellite breakup may be accidental or the result of intentional actions, e.g., due to a propulsion system malfunction or a space weapons test, respectively. An anomalous event is the unplanned separation, usually at low velocity, of one or more detectable objects from a satellite which remains essentially intact. Anomalous events can be caused by material deterioration of items such as thermal blankets, protective shields, or solar panels. As a general rule, a satellite breakup will produce considerably more debris, both trackable and non-trackable, than an anomalous event. From one perspective, satellite breakups may be viewed as a measure of the effects of man's activity on the environment, while anomalous

  15. Demonstration of protein-fragment complementation assay using purified firefly luciferase fragments

    PubMed Central

    2013-01-01

    Background Human interactome is predicted to contain 150,000 to 300,000 protein-protein interactions, (PPIs). Protein-fragment complementation assay (PCA) is one of the most widely used methods to detect PPI, as well as Förster resonance energy transfer (FRET). To date, successful applications of firefly luciferase (Fluc)-based PCA have been reported in vivo, in cultured cells and in cell-free lysate, owing to its high sensitivity, high signal-to-background (S/B) ratio, and reversible response. Here we show the assay also works with purified proteins with unexpectedly rapid kinetics. Results Split Fluc fragments both fused with a rapamycin-dependently interacting protein pair were made and expressed in E. coli system, and purified to homogeneity. When the proteins were used for PCA to detect rapamycin-dependent PPI, they enabled a rapid detection (~1 s) of PPI with high S/B ratio. When Fn7-8 domains (7 nm in length) that was shown to abrogate GFP mutant-based FRET was inserted between split Fluc and FKBP12 as a rigid linker, it still showed some response, suggesting less limitation in interacting partner’s size. Finally, the stability of the probe was investigated. Preincubation of the probes at 37 degreeC up to 1 h showed marked decrease of the luminescent signal to 1.5%, showing the limited stability of this system. Conclusion Fluc PCA using purified components will enable a rapid and handy detection of PPIs with high S/B ratio, avoiding the effects of concomitant components. Although the system might not be suitable for large-scale screening due to its limited stability, it can detect an interaction over larger distance than by FRET. This would be the first demonstration of Fluc PCA in vitro, which has a distinct advantage over other PPI assays. Our system enables detection of direct PPIs without risk of perturbation by PPI mediators in the complex cellular milieu. PMID:23536995

  16. Global-scale patterns of forest fragmentation

    USGS Publications Warehouse

    Riitters, K.; Wickham, J.; O'Neill, R.; Jones, B.; Smith, E.

    2000-01-01

    We report an analysis of forest fragmentation based on 1-km resolution land-cover maps for the globe. Measurements in analysis windows from 81 km 2 (9 ?? 9 pixels, "small" scale) to 59,049 km 2 (243 ?? 243 pixels, "large" scale) were used to characterize the fragmentation around each forested pixel. We identified six categories of fragmentation (interior, perforated, edge, transitional, patch, and undetermined) from the amount of forest and its occurrence as adjacent forest pixels. Interior forest exists only at relatively small scales; at larger scales, forests are dominated by edge and patch conditions. At the smallest scale, there were significant differences in fragmentation among continents; within continents, there were significant differences among individual forest types. Tropical rain forest fragmentation was most severe in North America and least severe in Europe - Asia. Forest types with a high percentage of perforated conditions were mainly in North America (five types) and Europe - Asia (four types), in both temperate and subtropical regions. Transitional and patch conditions were most common in 11 forest types, of which only a few would be considered as "naturally patchy" (e.g., dry woodland). The five forest types with the highest percentage of interior conditions were in North America; in decreasing order, they were cool rain forest, coniferous, conifer boreal, cool mixed, and cool broadleaf. Copyright ?? 2000 by The Resilience Alliance.

  17. Modelling of the Pele Fragmentation Dynamics

    NASA Astrophysics Data System (ADS)

    Verreault, Jimmy

    2013-06-01

    The Penetrator with Enhanced Lateral Effect (PELE) is a type of explosive-free projectile that undergoes radial fragmentation upon an impact with a target plate. This type of projectile is composed of a brittle cylindrical shell (the jacket) filled in its core with a material characterized with a large Poisson's ratio. Upon an impact with a target, the axial compression causes the filling to expand in the radial direction. However, due to the brittleness of the jacket material, very little radial deformation can occur which creates a radial stress between the two materials and a hoop stress in the jacket. Fragmentation of the jacket occurs if the hoop stress exceeds the material's ultimate stress. The PELE fragmentation dynamics is explored via Finite-Element Method (FEM) simulations using the AUTODYN explicit dynamics hydrocode. The numerical results are compared with an analytical model based on wave interactions, as well as with the experimental investigation of Paulus and Schirm (1996). The comparison is based on the mechanical stress in the filling, the resulting radial velocity of the fragments, the number of fragments generated and their mass distribution.

  18. a Study of Proton Induced Nuclear Fragmentation in the Threshold Region: 1 TO 20 GEV

    NASA Astrophysics Data System (ADS)

    Sangster, Thomas Craig

    This thesis contains the details of the experimental set-up and final results of BNL E-778. The experimental objective was to study proton induced nuclear fragmentation using an internal gas jet target facility that was specifically designed for this experiment and installed in the AGS main ring. The fragment telescopes were designed to measure a broad range of fragment charge (2 to 14) and kinetic energy (5 to 100 MeV). Using a mixed gas target (1% or 3% Xe with H(,2)), normalized fragment production cross sections were obtained by separately measuring p-p elastic production from the H(,2) component. Fragment production cross sections are observed to rise dramatically ((TURN) x 10) for incident proton energies between 1 and 10 GeV, while above 10 GeV, fragment production appears to be independent of the incident proton energy. The measured differential cross sections (above 10 GeV) are found to agree (within 20%) with the differential cross sections measured during a previous internal target experiment (E-591) conducted at FNAL, where the lowest available proton energies were 50 GeV. The measured fragment kinetic energy spectra (above 10 GeV) are fit with a functional form motivated by the observation that fragment production in an excited nuclear system is consistent with a critical phenomenon (a liquid -gas phase transition). The failure of this functional form at the lowest available incident energies (below 10 GeV) is interpreted as the observation of an additional fragment production mechanism. Recent theoretical and experimental evidence for an asymmetric fission process (binary decay), is used to modify the original functional form for the two-component spectra. It is concluded that, in the threshold region, two fragment production mechanisms are observed. Although insufficient information is available to uniquely separate the two components, certain features of the asymmetric fission mechanism are identified. The observed p-nucleus systematics are also

  19. Performance of phased rotation, conformation and translation function: accurate protein model building with tripeptidic and tetrapeptidic fragments.

    PubMed

    Pavelcík, Frantisek; Václavík, Jirí

    2010-09-01

    The automatic building of protein structures with tripeptidic and tetrapeptidic fragments was investigated. The oligopeptidic conformers were positioned in the electron-density map by a phased rotation, conformation and translation function and refined by a real-space refinement. The number of successfully located fragments lay within the interval 75-95% depending on the resolution and phase quality. The overlaps of partially located fragments were analyzed. The correctly positioned fragments were connected into chains. Chains formed in this way were extended directly into the electron density and a sequence was assigned. In the initial stage of the model building the number of located fragments was between 60% and 95%, but this number could be increased by several cycles of reciprocal-space refinement and automatic model rebuilding. A nearly complete structure can be obtained on the condition that the resolution is reasonable. Computer graphics will only be needed for a final check and small corrections.

  20. On the effect of grain burnback on STS-SRM fragment velocity

    SciTech Connect

    Eck, M.B.; Mukunda, M. )

    1991-01-01

    Concerns raised during the Ulysses Final Safety Analysis Review (FSAR) process called the solid rocket motor (SRM) fragment velocity prediction model into question. The specific area of concern was that there was a section of the SRM casing which was exposed to SRM chamber pressure as the grain (fuel) was consumed. These questions centered on the velocity of fragments which originated from the field joint region given that failure occurred between 37 and 72 seconds mission elapsed time (MET). Two dimensional coupled Eulerian-Lagrangian calculations were performed to assess the hot gas flow field which resulted from SRM casing fragmentation. The fragment to gas interface-pressure time-history obtained from these analyses was reduced to a boundary condition algorithm which was applied to an explicit-time-integration, finite element, three dimensional shell model of the SRM casing and unburned fuel. The results of these calculations showed that the velocity of fragments originating in the field joint was adequately described by the range of velocities given in the Shuttle Data Book (1988). Based on these results, no further analyses were required, and approval was obtained from the Launch Abort Subpanel of the Interagency Nuclear Safety Review Panel to use the SRM fragment velocity environments presented in the Ulysses FSAR (1990).

  1. Yeast vacuoles fragment in an asymmetrical two-phase process with distinct protein requirements.

    PubMed

    Zieger, Martin; Mayer, Andreas

    2012-09-01

    Yeast vacuoles fragment and fuse in response to environmental conditions, such as changes in osmotic conditions or nutrient availability. Here we analyze osmotically induced vacuole fragmentation by time-lapse microscopy. Small fragmentation products originate directly from the large central vacuole. This happens by asymmetrical scission rather than by consecutive equal divisions. Fragmentation occurs in two distinct phases. Initially, vacuoles shrink and generate deep invaginations that leave behind tubular structures in their vicinity. Already this invagination requires the dynamin-like GTPase Vps1p and the vacuolar proton gradient. Invaginations are stabilized by phosphatidylinositol 3-phosphate (PI(3)P) produced by the phosphoinositide 3-kinase complex II. Subsequently, vesicles pinch off from the tips of the tubular structures in a polarized manner, directly generating fragmentation products of the final size. This phase depends on the production of phosphatidylinositol-3,5-bisphosphate and the Fab1 complex. It is accelerated by the PI(3)P- and phosphatidylinositol 3,5-bisphosphate-binding protein Atg18p. Thus vacuoles fragment in two steps with distinct protein and lipid requirements.

  2. Anti-fouling properties of Fab' fragments immobilized on silane-based adlayers

    NASA Astrophysics Data System (ADS)

    Crivianu-Gaita, Victor; Romaschin, Alexander; Thompson, Michael

    2015-12-01

    Biosensors require surfaces that are highly specific towards the target analyte and that are minimally fouling. However, surface tuning to minimize fouling is a difficult task. The last decade has seen an increase in the use of immobilized antigen-binding antibody fragments (Fab') in biosensors. One Fab' linker compound S-(11-trichlorosilyl-undecanyl)-benzothiosulfonate (TUBTS) and three spacers were used to create the silane-based adlayers. The ultra-high frequency electromagnetic piezoelectric acoustic sensor (EMPAS) was used to gauge the fouling properties of the various surfaces using bovine serum albumin (BSA), goat IgG, and mouse serum. X-ray photoelectron spectroscopy (XPS), contact angle, and atomic force microscopy (AFM) were employed to characterize the surfaces. It was discovered that immobilized oriented Fab' fragments reduced the fouling levels of surfaces up to 80% compared to the surfaces without fragments. An explanation for this phenomenon is that the antibody fragments increase the hydration of the surfaces and aid in the formation of an anti-fouling water barrier. The anti-fouling effect of the Fab' fragments is at its maximum when there is an even distribution of fragments across the surfaces. Finally, using Fab'-covered surfaces, a cancer biomarker was detected from serum, showing the applicability of this work to the field of biodetection.

  3. Micromachined fragment capturer for biomedical applications.

    PubMed

    Choi, Young-Soo; Lee, Dong-Weon

    2011-11-01

    Due to changes in modern diet, a form of heart disease called chronic total occlusion has become a serious disease to be treated as an emergency. In this study, we propose a micromachined capturer that is designed and fabricated to collect plaque fragments generated during surgery to remove the thrombus. The fragment capturer consists of a plastic body made by rapid prototyping, SU-8 mesh structures using MEMS techniques, and ionic polymer metal composite (IPMC) actuators. An array of IPMC actuators combined with the SU-8 net structure was optimized to effectively collect plaque fragments. The evaporation of solvent through the actuator's surface was prevented using a coating of SU-8 and polydimethylsiloxane thin film on the actuator. This approach improved the available operating time of the IPMC, which primarily depends on solvent loss. Our preliminary results demonstrate the possibility of using the capturer for biomedical applications.

  4. Micromachined fragment capturer for biomedical applications

    NASA Astrophysics Data System (ADS)

    Choi, Young-Soo; Lee, Dong-Weon

    2011-11-01

    Due to changes in modern diet, a form of heart disease called chronic total occlusion has become a serious disease to be treated as an emergency. In this study, we propose a micromachined capturer that is designed and fabricated to collect plaque fragments generated during surgery to remove the thrombus. The fragment capturer consists of a plastic body made by rapid prototyping, SU-8 mesh structures using MEMS techniques, and ionic polymer metal composite (IPMC) actuators. An array of IPMC actuators combined with the SU-8 net structure was optimized to effectively collect plaque fragments. The evaporation of solvent through the actuator's surface was prevented using a coating of SU-8 and polydimethylsiloxane thin film on the actuator. This approach improved the available operating time of the IPMC, which primarily depends on solvent loss. Our preliminary results demonstrate the possibility of using the capturer for biomedical applications.

  5. Fragmentation of Kozai–Lidov Disks

    NASA Astrophysics Data System (ADS)

    Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G.

    2017-02-01

    We analyze the gravitational instability (GI) of a locally isothermal inclined disk around one component of a binary system. Such a disk can undergo global Kozai–Lidov (KL) cycles if the initial disk tilt is above the critical KL angle (of about 40◦). During these cycles, an initially circular disk exchanges its inclination for eccentricity, and vice versa. Self-gravity may suppress the cycles under some circumstances. However, with hydrodynamic simulations that include self-gravity, we show that for a sufficiently high initial disk tilts and for certain disk masses, disks can undergo KL oscillations and fragment due to GI, even when the Toomre Q value for an equivalent undisturbed disk is well within the stable regime (Q> 2). We suggest that KL triggered disk fragmentation provides a mechanism for the efficient formation of giant planets in binary systems and may enhance the fragmentation of disks in massive black hole binaries.

  6. Transversity from two pion interference fragmentation

    SciTech Connect

    She Jun; Huang Yang; Barone, Vincenzo; Ma Boqiang

    2008-01-01

    We present calculation on the azimuthal spin asymmetries for pion pair production in semi-inclusive deep inelastic scattering (SIDIS) process at both HERMES and COMPASS kinematics, with transversely polarized proton, deuteron, and neutron targets. We calculate the asymmetry by adopting a set of parametrization of the interference fragmentation functions and two different models for the transversity. We find that the result for the proton target is insensitive to the approaches of the transversity but more helpful to understand the interference fragmentation functions. However, for the neutron target, which can be obtained through using deuteron and {sup 3}He targets, we find different predictions for different approaches to the transversity. Thus probing the two pion interference fragmentation from the neutron can provide us more interesting information on the transversity.

  7. Fragmentation of methane molecules by antiproton impact

    NASA Astrophysics Data System (ADS)

    Salehzadeh, Arash; Kirchner, Tom

    2016-09-01

    Extending previous work for proton impact, we have investigated the fragmentation of methane molecules due to collisions with antiprotons in the 25 keV to 5 MeV impact energy range. The multi-center nature of the problem is addressed by using a spectral representation of the molecular Hartree-Fock-level Hamiltonian and a single-center expansion of the initially populated molecular orbitals. The two-center basis generator method (TC-BGM) is used for orbital propagation. Electron-removal cross sections obtained from the TC-BGM solutions are complemented with a dynamical decay-route fragmentation model to calculate cross sections for the production of fragment ions. Good agreement with the available experimental data is observed for CH4+,CH3+,CH2+and CH+. Work supported by NSERC, Canada.

  8. Crystallographic fragment-based drug discovery: use of a brominated fragment library targeting HIV protease.

    PubMed

    Tiefenbrunn, Theresa; Forli, Stefano; Happer, Meaghan; Gonzalez, Ana; Tsai, Yingssu; Soltis, Michael; Elder, John H; Olson, Arthur J; Stout, Charles D

    2014-02-01

    A library of 68 brominated fragments was screened against a new crystal form of inhibited HIV-1 protease in order to probe surface sites in soaking experiments. Often, fragments are weak binders with partial occupancy, resulting in weak, difficult-to-fit electron density. The use of a brominated fragment library addresses this challenge, as bromine can be located unequivocally via anomalous scattering. Data collection was carried out in an automated fashion using AutoDrug at SSRL. Novel hits were identified in the known surface sites: 3-bromo-2,6-dimethoxybenzoic acid (Br6) in the flap site and 1-bromo-2-naphthoic acid (Br27) in the exosite, expanding the chemistry of known fragments for development of higher affinity potential allosteric inhibitors. At the same time, mapping the binding sites of a number of weaker binding Br-fragments provides further insight into the nature of these surface pockets.

  9. Analysis of fission-fragment mass distribution within the quantum-mechanical fragmentation theory

    NASA Astrophysics Data System (ADS)

    Singh, Pardeep; Kaur, Harjeet

    2016-11-01

    The fission-fragment mass distribution is analysed for the 208Pb(18O, f) reaction within the quantum-mechanical fragmentation theory (QMFT). The reaction potential has been calculated by taking the binding energies, Coulomb potential and proximity potential of all possible decay channels and a stationary Schrödinger equation has been solved numerically to calculate the fission-fragment yield. The overall results for mass distribution are compared with those obtained in experiment. Fine structure dips in yield, corresponding to fragment shell closures at Z = 50 and N=82, which are observed by Bogachev et al., are reproduced successfully in the present calculations. These calculations will help to estimate the formation probabilities of fission fragments and to understand many related phenomena occurring in the fission process.

  10. Crystallographic Fragment Based Drug Discovery: Use of a Brominated Fragment Library Targeting HIV Protease

    PubMed Central

    Tiefenbrunn, Theresa; Forli, Stefano; Happer, Meaghan; Gonzalez, Ana; Tsai, Yingssu; Soltis, Michael; Elder, John H.; Olson, Arthur J.; Stout, C. David

    2013-01-01

    A library of 68 brominated fragments was screened against a new crystal form of inhibited HIV-1 protease in order to probe surface sites in soaking experiments. Often fragments are weak binders with partial occupancy, resulting in weak, difficult-to-fit electron density. The use of a brominated fragment library addresses this challenge, as bromine can be located unequivocally via anomalous scattering. Data collection was carried out in an automated fashion using AutoDrug at SSRL. Novel hits were identified in the known surface sites: 3-bromo-2,6-dimethoxybenzoic acid (Br6) in the flap site, and 1-bromo-2-naphthoic acid (Br27) in the exosite, expanding the chemistry of known fragments for development of higher affinity potential allosteric inhibitors. At the same time, mapping the binding sites of a number of weaker binding Br-fragments provides further insight into the nature of these surface pockets. PMID:23998903

  11. Parton Propagation and Fragmentation in QCD Matter

    SciTech Connect

    Alberto Accardi, Francois Arleo, William Brooks, David D'Enterria, Valeria Muccifora

    2009-12-01

    We review recent progress in the study of parton propagation, interaction and fragmentation in both cold and hot strongly interacting matter. Experimental highlights on high-energy hadron production in deep inelastic lepton-nucleus scattering, proton-nucleus and heavy-ion collisions, as well as Drell-Yan processes in hadron-nucleus collisions are presented. The existing theoretical frameworks for describing the in-medium interaction of energetic partons and the space-time evolution of their fragmentation into hadrons are discussed and confronted to experimental data. We conclude with a list of theoretical and experimental open issues, and a brief description of future relevant experiments and facilities.

  12. Explosive fragmentation of orbiting propellant tanks

    NASA Technical Reports Server (NTRS)

    Benz, F. J.; Kays, R. L.; Bishop, C. V.; Eck, M. B.

    1989-01-01

    An examination is made of the in-orbit explosive characteristics of the Delta second stage and Ariane third stage, with a view to the vehicle breakups of the Ariane SPOT third-stage fuel tank in November, 1986, and of two Delta second stage tanks. Attention is given to the possible role of residual propellants in these breakups. After reviewing orbital data and comparing predicted fragment velocities with observed fragment velocities in debris patterns, a comparison has been made of total debris energy with total calculated explosion energy. Both physical and chemical explosions are deemed possible.

  13. Radio Frequency Fragment Separator at NSCL

    NASA Astrophysics Data System (ADS)

    Bazin, D.; Andreev, V.; Becerril, A.; Doléans, M.; Mantica, P. F.; Ottarson, J.; Schatz, H.; Stoker, J. B.; Vincent, J.

    2009-07-01

    A new device has been designed and built at NSCL which provides additional filtering of radioactive beams produced via projectile fragmentation. The Radio Frequency Fragment Separator (RFFS) uses the time micro structure of the beams accelerated by the cyclotrons to deflect particles according to their time-of-flight, in effect producing a phase filtering. The transverse RF (Radio Frequency) electric field of the RFFS has superior filtering performance compared to other electrostatic devices, such as Wien filters. Such filtering is critical for radioactive beams produced on the neutron-deficient side of the valley of stability, where strong contamination occurs at intermediate energies from 50 to 200 MeV/u.

  14. Statistical fragmentation of small neutral carbon clusters

    SciTech Connect

    Diaz-Tendero, S.; Alcami, M.; Martin, F.; Hervieux, P.-A.

    2005-03-01

    We present a statistical fragmentation study of the C{sub 5}, C{sub 7}, and C{sub 9} carbon clusters using the Metropolis Monte Carlo and Weisskopf methods. We show that inclusion of several isomeric forms as well as rotational effects is essential to reproduce the experimental observations. We have found that, for cluster excitation energies around 10 eV, several fragmentation channels are efficiently populated, but the dominant one always corresponds to C{sub n-3}/C{sub 3}. For high enough excitation energies, we observe first-order phase transitions corresponding to a complete breakup of the cluster.

  15. Treatment imprudence leading to missed tooth fragment

    PubMed Central

    Barua, Pranamee; Chaudhary, Seema; Kaur, Harsimran; Mallikarjuna, Rachappa

    2013-01-01

    Traumatic dental injuries (TDI) represent one of the most common oral health problems in children and adolescents. Dental trauma requires a special consideration when it accompanies soft tissue lacerations. Tooth fragments occasionally penetrate into soft tissues and may cause severe complications. This article describes the case of a 12-year-old girl with a fractured tooth fragment embedded in the lower lip for 4 months, which went unnoticed at her primary health centre. This report highlights the importance of proper radiographic diagnosis along with clinical examination after trauma in order to prevent any future complications. PMID:23606390

  16. Analytical pyrolysis of cells and cell fragments

    SciTech Connect

    Faix, O.; Bertelt, E.

    1995-12-01

    Wood of spruce, beech and birch was disintegrated without chemical pretreatment after 10 minutes of steaming at 110{degrees}C in a laboratory defibrator. Fibers, vessels, and fragments of secondary wall were separated by wet screening. A hydrocylon was used for separation of middle lamellae. By using analytical pyrolysis-GC/MS, parenchymatic cells were found to be richer in lignin than the other cells. The lignin content of middle lamellae was 35% (beech, spruce) and 39% (birch). In agreement with the literature, the S/G ratios of the vessels and middle lamellae was lower than those of the other cells and cell fragments.

  17. Evolution of parton fragmentation functions at finitetemperature

    SciTech Connect

    Osborne, Jonathan; Wang, Enke; Wang, Xin-Nian

    2002-06-12

    The first order correction to the parton fragmentation functions in a thermal medium is derived in the leading logarithmic approximation in the framework of thermal field theory. The medium-modified evolution equations of the parton fragmentation functions are also derived. It is shown that all infrared divergences, both linear and logarithmic, in the real processes are canceled among themselves and by corresponding virtual corrections. The evolution of the quark number and the energy loss (or gain) induced by the thermal medium are investigated.

  18. Effect of forest fragmentation on bird populations

    USGS Publications Warehouse

    Robbins, C.S.

    1979-01-01

    Many of the insectivorous songbird species that winter in the tropics are dependent on large unbroken tracts of forest during the breeding season. These species are disappearing from localities where forests are becoming fragmented. By long-range planning, managers can prevent local extinctions of these area-sensitive birds through use of such techniques as management in large units, retention of connecting corridors, and prevention of excessive isolation of forest fragments. Edge conditions can be provided, where appropriate to meet the needs of upland game species.

  19. Computer Model Of Fragmentation Of Atomic Nuclei

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

    1995-01-01

    High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.

  20. Angular Momentum Population in Projectile Fragmentation

    NASA Astrophysics Data System (ADS)

    Podolyák, Zs.; Gladnishki, K. A.; Gerl, J.; Hellström, M.; Kopatch, Y.; Mandal, S.; Górska, M.; Regan, P. H.; Wollersheim, H. J.; Schmidt, K.-H.; Gsi-Isomer Collaboration

    2004-02-01

    Isomeric states in neutron-deficient nuclei around A ≈190 have been identified following the projectile fragmentation of a relativistic energy 238U beam. The deduced isomeric ratios are compared with a model based on the abrasion-ablation description. The experimental isomeric ratios are lower by a factor of ≈2 than the calculated ones assuming the `sharp cutoff' approximation. The observation of the previously reported isomeric Iπ=43/2- state in 215Ra represents the current record for the highest discrete spin state observed following a projectile fragmentation reaction.

  1. Flexible fragmentation rules for next-generation OPC: tag prior to fragmentation

    NASA Astrophysics Data System (ADS)

    Chen, Shih-Ying; Lynn, Eric C.

    2002-07-01

    Fragmentation, cutting polygon edge into piecewise of small segments that are later allowed to move individually, has been widely accepted as the work-around methodology in modern model-based optical proximity correction (OPC) tools. As tuning a model-based OPC recipe, most engineers spend much time on the model fitting to make simulated curves a better fit to empirical data (CD measurements). Most failure cases, however, do not result from a model with bad fitting. Instead it has been frequently found that undesired OPC outcomes were derived from fragmentation process. Tuning fragmentation parameters may not be sufficient to resolve some failure cases since it could be intrinsic issues of the current fragmentation mechanism. An illustrative example is the poor correction of a hammerhead line end, in which current fragmentation mechanisms fail to identify it as a line end and later improper compensation (correction) is installed. Other examples include asymmetric OPC results are frequently found. In the present study, several examples were used to assist the analysis of current fragmentation mechanisms in the aspects of effectiveness and limitations. For the coming 0.1 micron or even more advanced generations of technologies, the role of fragmentation mechanism renders its importance more profoundly. Therefore, more powerful fragmentation mechanism will be one of major factors for the success of OPC process. It is the main goal of this study to propose a new fragmentation mechanism. Edges are tagged specifically according to their environment prior to the process of cutting edge into smaller segments. The pseudo code of the new fragmentation mechanism will be given with detailed descriptions.

  2. Combined Effects of UV Exposure Duration and Mechanical Abrasion on Microplastic Fragmentation by Polymer Type.

    PubMed

    Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Han, Gi Myung; Jung, Seung Won; Shim, Won Joon

    2017-03-28

    It is important to understand the fragmentation processes and mechanisms of plastic litter to predict microplastic production in the marine environment. In this study, accelerated weathering experiments were performed in the laboratory, with ultraviolet (UV) exposure for up to 12 months followed by mechanical abrasion (MA) with sand for 2 months. Fragmentation of low-density polyethylene (PE), polypropylene (PP), and expanded polystyrene (EPS) was evaluated under conditions that simulated a beach environment. PE and PP were minimally fragmented by MA without photooxidation by UV (8.7 ± 2.5 and 10.7 ± 0.7 particles/pellet, respectively). The rate of fragmentation by UV exposure duration increased more for PP than PE. A 12-month UV exposure and 2-month MA of PP and PE produced 6084 ± 1061 and 20 ± 8.3 particles/pellet, respectively. EPS pellets were susceptible to MA alone (4220 ± 33 particles/pellet), while the combination of 6 months of UV exposure followed by 2 months of MA produced 12,152 ± 3276 particles/pellet. The number of fragmented polymer particles produced by UV exposure and mechanical abrasion increased with decreasing size in all polymer types. The size-normalized abundance of the fragmented PE, PP, and EPS particles according to particle size after UV exposure and MA was predictable. Up to 76.5% of the initial EPS volume was unaccounted for in the final volume of pellet produced particle fragments, indicating that a large proportion of the particles had fragmented into undetectable submicron particles.

  3. Dynamical effects in the Coulomb expansion following nuclear fragmentation

    SciTech Connect

    Chung, K.C.; Donangelo, R.; Schechter, H.

    1987-09-01

    The effects of the Coulomb expansion on the fragment kinetic energy spectrum for a fragmentating hot nuclear system is investigated. In particular, /sup 12/C-fragment spectra are calculated and compared with those predicted by the uniform expansion approximation. The results indicate that the energy spectra of fragments are quite sensitive to the details of the Coulomb expansion treatment.

  4. Nuclear DNA fragmentation during cell death of short-lived ray tracheids in the conifer Pinus densiflora.

    PubMed

    Nakaba, Satoshi; Kubo, Takafumi; Funada, Ryo

    2011-05-01

    One key event in the programmed cell death is nuclear DNA fragmentation. We investigated the timing of nuclear DNA fragmentation during the cell death of short-lived ray tracheids in Pinus densiflora using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay. Fluorescence due to TUNEL was detected only in deformed nuclei that lacked obvious chromatin in ray tracheids that were adjacent to ray tracheids that no longer contained nuclei. Our observations revealed that nuclear DNA fragmentation occurred only at the final stage of cell death in ray tracheids in situ.

  5. DNA fragment sizing and sorting by laser-induced fluorescence

    DOEpatents

    Hammond, Mark L.; Jett, James H.; Keller, Richard A.; Marrone, Babetta L.; Martin, John C.

    1996-01-01

    A method is provided for sizing DNA fragments using high speed detection systems, such as flow cytometry to determine unique characteristics of DNA pieces from a sample. In one characterization the DNA piece is fragmented at preselected sites to produce a plurality of DNA fragments. The DNA piece or the resulting DNA fragments are treated with a dye effective to stain stoichiometrically the DNA piece or the DNA fragments. The fluorescence from the dye in the stained fragments is then examined to generate an output functionally related to the number of nucleotides in each one of the DNA fragments. In one embodiment, the intensity of the fluorescence emissions from each fragment is linearly related to the fragment length. The distribution of DNA fragment sizes forms a characterization of the DNA piece for use in forensic and research applications.

  6. Internal energy and fragmentation of ions produced in electrospray sources.

    PubMed

    Gabelica, Valérie; De Pauw, Edwin

    2005-01-01

    This review addresses the determination of the internal energy of ions produced by electrospray ionization (ESI) sources, and the influence of the internal energy on analyte fragmentation. A control of the analyte internal energy is crucial for several applications of electrospray mass spectrometry, like structural studies, construction of reproducible and exportable spectral libraries, analysis of non-covalent complexes. Sections II and III summarize the Electrospray mechanisms and source design considerations which are relevant to the problem of internal energy, and Section IV gives an overview of the inter-relationships between ion internal energy, reaction time scale, and analyte fragmentation. In these three sections we tried to make the most important theoretical elements understandable by all ESI users, and their understanding requires a minimal background in physical chemistry. We then present the different approaches used to experimentally determine the ion internal energy, as well as various attempts in modeling the internal energy uptake in electrospray sources. Finally, a tentative comparison between electrospray and other ionization sources is made. As the reader will see, although many reports appeared on the subject, the knowledge in the field of internal energy of ions produced by soft ionization sources is still scarce, because of the complexity of the system, and this is what makes this area of research so interesting. The last section presents some perspectives for future research.

  7. RNA-level unscrambling of fragmented genes in Diplonema mitochondria

    PubMed Central

    Kiethega, Georgette N.; Yan, Yifei; Turcotte, Marcel; Burger, Gertraud

    2013-01-01

    We previously reported a unique genome with systematically fragmented genes and gene pieces dispersed across numerous circular chromosomes, occurring in mitochondria of diplonemids. Genes are split into up to 12 short fragments (modules), which are separately transcribed and joined in a way that differs from known trans-splicing. Further, cox1 mRNA includes six non-encoded uridines indicating RNA editing. In the absence of recognizable cis-elements, we postulated that trans-splicing and RNA editing are directed by trans-acting molecules. Here, we provide insight into the post-transcriptional processes by investigating transcription, RNA processing, trans-splicing and RNA editing in cox1 and at a newly discovered site in cob. We show that module precursor transcripts are up to several thousand nt long and processed accurately at their 5′ and 3′ termini to yield the short coding-only regions. Processing at 5′ and 3′ ends occurs independently, and a processed terminus engages in trans-splicing even if the module’s other terminus is yet unprocessed. Moreover, only cognate module transcripts join, though without directionality. In contrast, module transcripts requiring RNA editing only trans-splice when editing is completed. Finally, experimental and computational analyses suggest the existence of RNA trans-factors with the potential for guiding both trans-splicing and RNA editing. PMID:23324603

  8. First assembly times and equilibration in stochastic coagulation-fragmentation

    SciTech Connect

    D’Orsogna, Maria R.; Lei, Qi; Chou, Tom

    2015-07-07

    We develop a fully stochastic theory for coagulation and fragmentation (CF) in a finite system with a maximum cluster size constraint. The process is modeled using a high-dimensional master equation for the probabilities of cluster configurations. For certain realizations of total mass and maximum cluster sizes, we find exact analytical results for the expected equilibrium cluster distributions. If coagulation is fast relative to fragmentation and if the total system mass is indivisible by the mass of the largest allowed cluster, we find a mean cluster-size distribution that is strikingly broader than that predicted by the corresponding mass-action equations. Combinations of total mass and maximum cluster size under which equilibration is accelerated, eluding late-stage coarsening, are also delineated. Finally, we compute the mean time it takes particles to first assemble into a maximum-sized cluster. Through careful state-space enumeration, the scaling of mean assembly times is derived for all combinations of total mass and maximum cluster size. We find that CF accelerates assembly relative to monomer kinetic only in special cases. All of our results hold in the infinite system limit and can be only derived from a high-dimensional discrete stochastic model, highlighting how classical mass-action models of self-assembly can fail.

  9. Enriching screening libraries with bioactive fragment space.

    PubMed

    Zhang, Na; Zhao, Hongtao

    2016-08-01

    By deconvoluting 238,073 bioactive molecules in the ChEMBL library into extended Murcko ring systems, we identified a set of 2245 ring systems present in at least 10 molecules. These ring systems belong to 2221 clusters by ECFP4 fingerprints with a minimum intracluster similarity of 0.8. Their overlap with ring systems in commercial libraries was further quantified. Our findings suggest that success of a small fragment library is driven by the convergence of effective coverage of bioactive ring systems (e.g., 10% coverage by 1000 fragments vs. 40% by 2million HTS compounds), high enrichment of bioactive ring systems, and low molecular complexity enhancing the probability of a match with the protein targets. Reconciling with the previous studies, bioactive ring systems are underrepresented in screening libraries. As such, we propose a library of virtual fragments with key functionalities via fragmentation of bioactive molecules. Its utility is exemplified by a prospective application on protein kinase CK2, resulting in the discovery of a series of novel inhibitors with the most potent compound having an IC50 of 0.5μM and a ligand efficiency of 0.41kcal/mol per heavy atom.

  10. Fragmentation of parton jets at small x

    SciTech Connect

    Kirschner, R.

    1985-08-01

    The parton fragmentation function is calculated in the region of small x in the doubly logarithmic approximation of QCD. For this, the method of separating the softest particle, which has hitherto been applied only in the Regge kinematic region, is developed. Simple arguments based on unitarity and gauge invariance are used to derive the well known condition of ordering of the emission angles.

  11. Dynamic rock fragmentation: oil shale applications

    SciTech Connect

    Boade, R. R.; Grady, D. E.; Kipp, M. E.

    1980-01-01

    Explosive rock fragmentation techniques used in many resource recovery operations have in the past relied heavily upon traditions of field experience for their design. As these resources, notably energy resources, become less accessible, it becomes increasingly important that fragmentation techniques be optimized and that methods be developed to effectively evaluate new or modified explosive deployment schemes. Computational procedures have significant potential in these areas, but practical applications must be preceded by a thorough understanding of the rock fracture phenomenon and the development of physically sound computational models. This paper presents some of the important features of a rock fragmentation model that was developed as part of a program directed at the preparation of subterranean beds for in situ processing of oil shale. The model, which has been implemented in a two-dimensional Lagrangian wavecode, employs a continuum damage concept to quantify the degree of fracturing and takes into account experimental observations that fracture strength and fragment dimensions depend on tensile strain rates. The basic premises of the model are considered in the paper as well as some comparisons between calculated results and observations from blasting experiments.

  12. The injection of asteroid fragments into resonances

    NASA Astrophysics Data System (ADS)

    Farinella, P.; Gonczi, R.; Froeschle, Ch.; Froeschle, C.

    1993-02-01

    A model is presented for the ejection of fragments from impact cratering or breakup of existing asteroids and the chance insertion of the escaping fragments into the 'dangerous' regions of the phase spaces close to the 3:1 and g = g6 resonances, where chaotic behavior may arise. It is found that both resonances are effective channels for fragment collection and delivery and their efficiencies are of the same order of magnitude, but they sample in a different way the orbital elements and the physical properties of the parent objects. Although this depends on the poorly known size distribution of small asteroids, it seems possible that a large fraction of near-earth asteroids and meteorites are generated by a small sample of the asteroid population, mostly located in the vicinity of resonances, whose average properties do not necessarily coincide with those of the general population. The g = g6 resonance is probably an effective fragment delivery channel in the moderate-inclination regions near 2.4 and 2.7 AU and near the inner edge of the belt.

  13. Vocabularies Clashing: "The Fragmented Generation" Describes Itself

    ERIC Educational Resources Information Center

    Collins, Daniel

    2011-01-01

    After reading Scott Seider and Howard Gardner's essay "The Fragmented Generation" (2009) in a college freshman writing class, students responded by providing their own labels for their generation. This article includes excerpts from their essays. Following these excerpts is the instructor's theoretical justification for this kind of classroom…

  14. Conformational studies of cellulosic fragments by DFT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study of cellulosic fragments by DFTr is a continuation of our efforts to produce quality structural data that will be valuable to those working in the field of cellulose structure and enzymatic degradation. Using a reduced basis set and density functional DFTr (B3LYP), optimization of cellulosi...

  15. DFT STUDIES OF DP-3 AMYLOSE FRAGMENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study extends our work on mono- and disaccharides to structures with three glucose residues by two alpha-[1-4] bridges, denoted herein as DP-3's. DFT optimization studies of DP-3 fragments have been carried out at the B3LYP/6-311++G** level of theory. Different hydroxymethyl conformations (gg...

  16. Fragman: an R package for fragment analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determination of microsatellite lengths or other DNA fragment types is an important initial component of many genetic studies such as mutation detection, linkage and QTL mapping, genetic diversity, pedigree analysis, and detection of heterozygosity. A handful of commercial and freely available softw...

  17. RESPONSE TO "THE OPTIMAL FRAGMENTATION PRINCIPLE".

    EPA Science Inventory

    Response to "The Optimal Fragmentation Principle"

    To follow up on my comment to Dale Johnson and to respond to his entertaining and provocative letter, I confess to some frustration in seeing a show-and-tell of a sophisticated tool for data mining and exploration, without ...

  18. Ligament Mediated Fragmentation of Viscoelastic Liquids

    NASA Astrophysics Data System (ADS)

    Keshavarz, Bavand; Houze, Eric C.; Moore, John R.; Koerner, Michael R.; McKinley, Gareth H.

    2016-10-01

    The breakup and atomization of complex fluids can be markedly different than the analogous processes in a simple Newtonian fluid. Atomization of paint, combustion of fuels containing antimisting agents, as well as physiological processes such as sneezing are common examples in which the atomized liquid contains synthetic or biological macromolecules that result in viscoelastic fluid characteristics. Here, we investigate the ligament-mediated fragmentation dynamics of viscoelastic fluids in three different canonical flows. The size distributions measured in each viscoelastic fragmentation process show a systematic broadening from the Newtonian solvent. In each case, the droplet sizes are well described by Gamma distributions which correspond to a fragmentation-coalescence scenario. We use a prototypical axial step strain experiment together with high-speed video imaging to show that this broadening results from the pronounced change in the corrugated shape of viscoelastic ligaments as they separate from the liquid core. These corrugations saturate in amplitude and the measured distributions for viscoelastic liquids in each process are given by a universal probability density function, corresponding to a Gamma distribution with nmin=4 . The breadth of this size distribution for viscoelastic filaments is shown to be constrained by a geometrical limit which can not be exceeded in ligament-mediated fragmentation phenomena.

  19. Modelling of the PELE fragmentation dynamics

    NASA Astrophysics Data System (ADS)

    Verreault, J.

    2014-05-01

    The Penetrator with Enhanced Lateral Effect (PELE) is a type of explosive-free projectile that undergoes radial fragmentation upon an impact with a target plate. This type of projectile is composed of a brittle cylindrical shell (the jacket) filled in its core with a material characterized with a large Poisson's ratio. Upon an impact with a target, the axial compression causes the filling to expand in the radial direction. However, due to the brittleness of the jacket material, very little radial deformation can occur which creates a radial stress between the two materials and a hoop stress in the jacket. Fragmentation of the jacket occurs if the hoop stress exceeds the material's ultimate stress. The PELE fragmentation dynamics is explored via Finite-Element Method (FEM) simulations using the Autodyn explicit dynamics hydrocode. The numerical results are compared with an analytical model based on wave interactions, as well as with the experimental investigation of Paulus and Schirm (1996). The comparison is based on the mechanical stress in the filling and the qualitative fragmentation of the jacket.

  20. DNA fragmentation by charged particle tracks

    NASA Astrophysics Data System (ADS)

    Stenerlöw, B.; Höglund, E.; Carlsson, J.

    High-LET (linear energy transfer) charged particles induce DNA double-strand breaks (DSB) in a non-random fashion in mammalian cells. The clustering of DSB, probably determined by track structure as well as chromatin conformation, results in an excess of small- and intermediate-sized DNA fragments. DNA fragmentation in normal human fibroblasts (GM5758) was analyzed by pulsed-field gel electrophoresis after irradiation with photons ( 60Co) or 125 keV/μm nitrogen ions. Compared to conventional DSB analysis, i.e. assays only measuring the fraction of DNA smaller than a single threshold, the relative biological effectiveness (RBE) for DSB induction increased with 100%. Further, the size distribution of DNA fragments showed a significant dependence on radiation quality, with an excess of fragments up to 1 Mbp. Irradiation of naked genomic DNA without histone proteins increased the DSB yields 25 and 13 times for photons and nitrogen ions, respectively. The results suggest possible roles of both track structure and chromatin organization in the distribution of DNA double-strand breaks along the chromosome.

  1. Fragmentation of Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Mueller, Erich J.; Ho, Tin-Lun; Ueda, Masahito; Baym, Gordon

    2006-09-01

    We present the theory of bosonic systems with multiple condensates, providing a unified description of various model systems that are found in the literature. We discuss how degeneracies, interactions, and symmetries conspire to give rise to this unusual behavior. We show that as degeneracies multiply, so do the varieties of fragmentation, eventually leading to strongly correlated states with no trace of condensation.

  2. Fragmentation and hydration of tektites and microtektites

    USGS Publications Warehouse

    Glass, B.P.; Muenow, D.W.; Bohor, B.F.; Meeker, G.P.

    1997-01-01

    An examination of data collected over the last 30 years indicates that the percent of glass fragments vs. whole splash forms in the Cenozoic microtektite strewn fields increases towards the source crater (or source region). We propose that this is due to thermal stress produced when tektites and larger microtektites fall into water near the source crater while still relatively hot (>1150 ??C). We also find evidence (low major oxide totals, frothing when melted) for hydration of most of the North American tektite fragments and microtektites found in marine sediments. High-temperature mass spectrometry indicates that these tektite fragments and microtektites contain up to 3.8 wt% H2O. The H2O-release behavior during the high-temperature mass-spectrometric analysis, plus high Cl abundances (???0.05 wt%), indicate that the North. American tektite fragments and microtektites were hydrated in the marine environment (i.e., the H2O was not trapped solely on quenching from a melt). The younger Ivory Coast and Australasian microtektites do not exhibit much evidence of hydration (at least not in excess of 0.5 wt% H2O); this suggests that the degree of hydration increases with age. In addition, we find that some glass spherules (with 65 wt% SiO2 can undergo simple hydration in the marine environment, while impact glasses (with <65 wt% SiO2) can also undergo palagonitization.

  3. Achieving climate connectivity in a fragmented landscape

    PubMed Central

    Lawler, Joshua J.; McRae, Brad H.; Nuñez, Tristan A.; Theobald, David M.

    2016-01-01

    The contiguous United States contains a disconnected patchwork of natural lands. This fragmentation by human activities limits species’ ability to track suitable climates as they rapidly shift. However, most models that project species movement needs have not examined where fragmentation will limit those movements. Here, we quantify climate connectivity, the capacity of landscape configuration to allow species movement in the face of dynamically shifting climate. Using this metric, we assess to what extent habitat fragmentation will limit species movements in response to climate change. We then evaluate how creating corridors to promote climate connectivity could potentially mitigate these restrictions, and we assess where strategies to increase connectivity will be most beneficial. By analyzing fragmentation patterns across the contiguous United States, we demonstrate that only 41% of natural land area retains enough connectivity to allow plants and animals to maintain climatic parity as the climate warms. In the eastern United States, less than 2% of natural area is sufficiently connected. Introducing corridors to facilitate movement through human-dominated regions increases the percentage of climatically connected natural area to 65%, with the most impactful gains in low-elevation regions, particularly in the southeastern United States. These climate connectivity analyses allow ecologists and conservation practitioners to determine the most effective regions for increasing connectivity. More importantly, our findings demonstrate that increasing climate connectivity is critical for allowing species to track rapidly changing climates, reconfiguring habitats to promote access to suitable climates. PMID:27298349

  4. Bullet on bullet fragmentation profile in soils.

    PubMed

    Martin, W Andy; Nestler, Catherine C; Wynter, Michelle; Larson, Steven L

    2014-12-15

    Lead-antimony alloy slugs encased in a brass jackets are common small arms caliber ammunition used for training and target practice. When small caliber ammunition is fired at testing and training ranges, these metals--some of which are toxic--are introduced into the environment. Research was conducted on the effects of bullet on bullet impacts and the resulting bullet fragmentation. The extent of bullet fragmentation, among other factors, affects the formation of mobile metal species from small arms firing ranges. Bullet on bullet impact can increase the surface area to mass ratio of the bullet metal alloys in the soil. The solubility of a metal is typically associated with the specific corrosion rate in the berm environment which is dependent on the surface area of the fragments. The purpose of the study was to analyze the bullet on bullet impact effects in six soil types. Changes in the metal distribution as a result of bullet impact was evaluated through sieve analysis and changes in the particle size distribution. The bullet on bullet impact observed in this study demonstrated a significant and observable shift in the fragmentation profiles for the lead, antimony, and copper in soils after shooting an average of 1050 tungsten-nylon bullets into the legacy lead soils. This study provides new information to assist with determining the potential environmental fate, transport, and environmental availability associated with constant bullet on bullet impact at testing and training ranges.

  5. Oscillating Filaments. I. Oscillation and Geometrical Fragmentation

    NASA Astrophysics Data System (ADS)

    Gritschneder, Matthias; Heigl, Stefan; Burkert, Andreas

    2017-01-01

    We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid-based AMR code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, such as with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation, and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process “geometrical fragmentation.” In our realization, the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristic scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. We show that the overall oscillation pattern can hide the infall signature of cores.

  6. Identification of B. anthracis N(5)-carboxyaminoimidazole ribonucleotide mutase (PurE) active site binding compounds via fragment library screening.

    PubMed

    Lei, Hao; Jones, Christopher; Zhu, Tian; Patel, Kavankumar; Wolf, Nina M; Fung, Leslie W-M; Lee, Hyun; Johnson, Michael E

    2016-02-15

    The de novo purine biosynthesis pathway is an attractive target for antibacterial drug design, and PurE from this pathway has been identified to be crucial for Bacillus anthracis survival in serum. In this study we adopted a fragment-based hit discovery approach, using three screening methods-saturation transfer difference nucleus magnetic resonance (STD-NMR), water-ligand observed via gradient spectroscopy (WaterLOGSY) NMR, and surface plasmon resonance (SPR), against B. anthracis PurE (BaPurE) to identify active site binding fragments by initially testing 352 compounds in a Zenobia fragment library. Competition STD NMR with the BaPurE product effectively eliminated non-active site binding hits from the primary hits, selecting active site binders only. Binding affinities (dissociation constant, KD) of these compounds varied between 234 and 301μM. Based on test results from the Zenobia compounds, we subsequently developed and applied a streamlined fragment screening strategy to screen a much larger library consisting of 3000 computationally pre-selected fragments. Thirteen final fragment hits were confirmed to exhibit binding affinities varying from 14μM to 700μM, which were categorized into five different basic scaffolds. All thirteen fragment hits have ligand efficiencies higher than 0.30. We demonstrated that at least two fragments from two different scaffolds exhibit inhibitory activity against the BaPurE enzyme.

  7. Fragment informatics and computational fragment-based drug design: an overview and update.

    PubMed

    Sheng, Chunquan; Zhang, Wannian

    2013-05-01

    Fragment-based drug design (FBDD) is a promising approach for the discovery and optimization of lead compounds. Despite its successes, FBDD also faces some internal limitations and challenges. FBDD requires a high quality of target protein and good solubility of fragments. Biophysical techniques for fragment screening necessitate expensive detection equipment and the strategies for evolving fragment hits to leads remain to be improved. Regardless, FBDD is necessary for investigating larger chemical space and can be applied to challenging biological targets. In this scenario, cheminformatics and computational chemistry can be used as alternative approaches that can significantly improve the efficiency and success rate of lead discovery and optimization. Cheminformatics and computational tools assist FBDD in a very flexible manner. Computational FBDD can be used independently or in parallel with experimental FBDD for efficiently generating and optimizing leads. Computational FBDD can also be integrated into each step of experimental FBDD and help to play a synergistic role by maximizing its performance. This review will provide critical analysis of the complementarity between computational and experimental FBDD and highlight recent advances in new algorithms and successful examples of their applications. In particular, fragment-based cheminformatics tools, high-throughput fragment docking, and fragment-based de novo drug design will provide the focus of this review. We will also discuss the advantages and limitations of different methods and the trends in new developments that should inspire future research.

  8. The Spectrum of Satellite Breakup and Fragmentation

    NASA Astrophysics Data System (ADS)

    Finkleman, D.

    The objective of this paper is to expose the spectrum of satellite breakup physics and is implications for debris production and observables. Satellite response to the debris environment generally emphasizes small scale hypervelocity impact or the interaction of intense, coherent radiation with satellite surfaces or internals. There are empirical correlations of fragment size distributions based on arena tests and extremely rare observations of breakups in space. Klinkrad describes well research on material response to hypervelocity impact such as the ballistic limit for various materials and shielding walls. Smirnov, et. al., report well the phenomenology of breakups under the influence of nonuniform internal loading of monolithic bodies, such as pressurized tanks. They set forth the transformation of elastic energy into fragment kinetic energy. They establish a sound physical framework for bounding the number of fragments. We took advantage of these works in our previous papers. There is not much research into the response of nonuniform structures to hypervelocity collisions with similarly massive and complex objects. This work generally employs complex hydrodynamic and finite element computation that is not well suited to real time, operational assessment of the consequences of such encounters. We hope to diminish the void between the extremes of microscopic impact and complex hydrocodes. Our previous reports employed the framework established by Chobotov and Spencer, fundamentally equilibrium, Newtonian approach. We now explore the spectrum of interactions and debris evolutions possible with realistic combinations of these theories. The spectrum encompasses Newtonian, semi-elastic energy and momentum transfer through little or no momentum exchange and from virtually all of the mass of the colliders being involved through fractional mass involvement. We observe that the more Newtonian outcomes do not agree well with sparse observations of the few collisions that

  9. Inflaton fragmentation and oscillon formation in three dimensions

    NASA Astrophysics Data System (ADS)

    Amin, Mustafa A.; Easther, Richard; Finkel, Hal

    2010-12-01

    Analytical arguments suggest that a large class of scalar field potentials permit the existence of oscillons — pseudo-stable, non-topological solitons — in three spatial dimensions. In this paper we numerically explore oscillon solutions in three dimensions. We confirm the existence of these field configurations as solutions to the Klein-Gorden equation in an expanding background, and verify the predictions of Amin and Shirokoff [1] for the characteristics of individual oscillons for their model. Further, we demonstrate that significant numbers of oscillons can be generated via fragmentation of the inflaton condensate, consistent with the analysis of Amin [2]. These emergent oscillons can easily dominate the post-inflationary universe. Finally, both analytic and numerical results suggest that oscillons are stable on timescales longer than the post-inflationary Hubble time. Consequently, the post-inflationary universe can contain an effective matter-dominated phase, during which it is dominated by localized concentrations of scalar field matter.

  10. High-level iodination of monoclonal antibody fragments for radiotherapy

    SciTech Connect

    Ferens, J.M.; Krohn, K.A.; Beaumier, P.L.; Brown, J.P.; Hellstroem, I.; Hellstroem, K.E.; Carrasquillo, J.A.; Larson, S.M.

    1984-03-01

    Two different murine monoclonal antibody Fab fragments specific for p97, a melanoma-associated antigen, were labeled with I-131 at high activity levels without excessive chemical damage. Up to 20 mg of Fab were labeled with up to 300 mCi of I-131 using the chloramine-T method and large working volumes at room temperature. As much as 90% of the initial activity was recovered as labeled product. The labeled Fabs varied in their sensitivity to radioiodination damage, as measured by an in vitro cell-binding assay. Radioiodination was performed safely using a remote iodination apparatus. The final product was of radiopharmaceutical quality suitable for clinical diagnosis and experimental radiotherapy in humans.

  11. The fragmentation of 510 MeV/nucleon iron-56 in polyethylene. I. Fragment fluence spectra

    NASA Technical Reports Server (NTRS)

    Zeitlin, C.; Miller, J.; Heilbronn, L.; Frankel, K.; Gong, W.; Schimmerling, W.

    1996-01-01

    The fragmentation of 510 MeV/nucleon iron ions in several thicknesses of polyethylene has been measured. Non-interacting primary beam particles and fragments have been identified and their LETs calculated by measuring ionization energy loss in a stack of silicon detectors. Fluences, normalized to the incident beam intensity and corrected for detector effects, are presented for each fragment charge and target. Histograms of fluence as a function of LET are also presented. Some implications of these data for measurements of the biological effects of heavy ions are discussed.

  12. A T-matrix theory of galactic heavy-ion fragmentation

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W.; Deutchman, P. A.

    1985-01-01

    The theory of galactic heavy ion fragmentation is furthered by incorporating a T matrix approach into the description of the three step process of abrasion, ablation, and final state interations. The connection between this T matrix and the interaction potential is derived. For resonant states, the substitution of complex energies for real energies in the transition rate is formerly justified for up to third order processes. The previously developed abrasion-ablation fragmentation theory is rederived from first principles and is shown to result from time ordering, classical probability, and zero width resonance approximations. Improvements in the accuracy of the total fragmentation cross sections require an alternative to the latter two approximations. A Lorentz invariant differential abrasion-ablation cross section is derived which explicitly includes the previously derived abrasion total cross sections. It is demonstrated that spectral and angular distributions can be obtained from the general Lorentz invariant form.

  13. One loop corrections on fragmentation function of 1S wave charmed mesons

    NASA Astrophysics Data System (ADS)

    Sepahvand, Reza; Dadfar, Sareh

    2017-04-01

    We present the contribution of the next to leading order (NLO) corrections in fragmentation a c-quark to 1S wave charmed mesons. These corrections are calculated by using the dimensional regularization method. We use two slicing methods that allow the phase space integrals to be evaluated in 4 dimensions. Technical details are discussed about virtual and real corrections in this scheme. Our numerical calculations show the NLO corrections to D mesons fragmentation function (FF) enhance the fragmentation probability (FP). The production ratio of vector mesons D* and D+* to all states is estimated. At NLO, it is obtained a bit smaller than the one at LO. Finally our analytic results are compared with available experimental data for D0 and D+* mesons.

  14. Late-stage planetary accretion including hit-and-run collisions and fragmentation

    NASA Astrophysics Data System (ADS)

    Chambers, J. E.

    2013-05-01

    To date, most simulations of the final accretion of the terrestrial planets have assumed that all collisions lead to mergers. Recent hydrodynamic simulations of impacts between planetary mass bodies (Leinhardt, Z.M., Stewart, S.T. [2012]. Astrophys. J. 745, 79; Genda, H., Kokubo, E., Ida, S. [2012]. Astrophys J. 744, 137) have parameterized the outcome of planetary collisions in terms of the masses and velocities of the colliding bodies. Using these results, it is now possible to simulate late-stage planetary growth using a more realistic model for collisions. Here, we describe results of eight N-body simulations of terrestrial planet formation that incorporate collisional fragmentation and hit-and-run collisions. The results are compared to simulations using identical initial collisions in which all collisions were assumed to result in mergers (Chambers, J.E. [2001]. Icarus 152, 205-224). The new simulations form 3 to 5 terrestrial planets moving on widely spaced orbits with growth complete by 400 My. The mean time for Earth-like planets to reach half their final mass is 17 My, comparable to the time in simulations without fragmentation. However, the prolonged sweep up of collision fragments lengthens the mean time required for Earth analogues to become fully formed to 159 My. The final planets have somewhat smaller masses m and eccentricities e when fragmentation is included. Masses are particularly reduced in the region now occupied by Mars. The final distributions of m, e and semi-major axis are similar to the terrestrial planets of the Solar System, but the strong concentration of mass in the narrow zone occupied by Earth and Venus is not reproduced. Collisional fragmentation is likely to preferentially eject silicate-rich mantle material leaving a target enriched in iron-rich core material. However, large bodies often reaccrete silicate-rich mantle fragments at a later time, leaving their final composition largely unchanged. The final core mass fractions of

  15. Solution for the fragment-size distribution in a crack-branching model of fragmentation

    NASA Astrophysics Data System (ADS)

    Kekäläinen, P.; Åström, J. A.; Timonen, J.

    2007-08-01

    It is well established that rapidly propagating cracks in brittle material are unstable such that they generate side branches. It is also known that cracks are attracted by free surfaces, which means that they attract each other. This information is used here to formulate a generic model of fragmentation in which the small-size part of the fragment-size distribution results from merged crack branches in the damage zones along the paths of the propagating cracks. This model is solved under rather general assumptions for the fragment-size distribution. The model leads to a generic distribution S-γexp(-S/S0) for fragment sizes S , where γ=(2d-1)/(d) with d the Euclidean dimension, and S0 is a material dependent parameter.

  16. Assessment of Fragmentation Performance of Blast-enhanced Explosive Fragmentation Munitions

    DTIC Science & Technology

    2010-10-01

    aluminized blast-enhanced PAX-Al composition. The experimental assessment of the fragmentation performance of tested charges was accomplished using...charges, rapid expansion of high pressure detonation products results in high-strain high-strain-rate dilation of the hardened steel shell, which...eventually ruptures generating a “spray” of high-velocity steel fragments. Defining the longitudinal axis of the munition as the polar axis z, the

  17. Mercaptan-induced fragmentation of a subunit-like proteolytic fragment of immunoglobulin M

    PubMed Central

    Butchko, G. M.; Inman, F. P.

    1972-01-01

    Limited papain hydrolysis of immunoglobulin M (IgM) produces a subunit-like proteolytic fragment designated IgMp (Inman & Hazen, 1968). In the presence of mercaptans, IgMp partially dissociated into Fcμ-like and Fabμ fragments. Treatment of residual IgM (that remaining after a papain digestion) with 2mm-mercaptoethylamine resulted in fragmentation of the same type that occurs in a routine limited digestion of IgM with papain, although exogenous enzyme was not added to the mixture. When IgM was hydrolysed with 14C-labelled papain, a small quantity of the enzyme was found to be associated with the residual IgM and IgMp fractions. IgM and IgM 7S subunit (IgMs) that had been exposed to papain in the absence of activating mercaptan and separated from the enzyme by gel filtration also fragmented when subsequently treated with 2mm-mercaptoethylamine. The fragments resembled those produced during a typical limited papain digestion of IgM. It was concluded that mercaptoethylamine induced fragmentation of IgMp by activating adsorbed papain. ImagesFig. 1.PLATE 1 PMID:5076228

  18. Unveiling a mechanism for species decline in fragmented habitats: fragmentation induced reduction in encounter rates

    PubMed Central

    Wosniack, M. E.; Santos, M. C.; Pie, M. R.; Marques, M. C. M.; Raposo, E. P.; Viswanathan, G. M.; da Luz, M. G. E.

    2014-01-01

    Several studies have reported that fragmentation (e.g. of anthropogenic origin) of habitats often leads to a decrease in the number of species in the region. An important mechanism causing this adverse ecological impact is the change in the encounter rates (i.e. the rates at which individuals meet other organisms of the same or different species). Yet, how fragmentation can change encounter rates is poorly understood. To gain insight into the problem, here we ask how landscape fragmentation affects encounter rates when all other relevant variables remain fixed. We present strong numerical evidence that fragmentation decreases search efficiencies thus encounter rates. What is surprising is that it falls even when the global average densities of interacting organisms are held constant. In other words, fragmentation per se can reduce encounter rates. As encounter rates are fundamental for biological interactions, it can explain part of the observed diminishing in animal biodiversity. Neglecting this effect may underestimate the negative outcomes of fragmentation. Partial deforestation and roads that cut through forests, for instance, might be responsible for far greater damage than thought. Preservation policies should take into account this previously overlooked scientific fact. PMID:24258156

  19. Peptide Fragmentation Induced by Radicals at Atmospheric Pressure

    PubMed Central

    Vilkov, Andrey N.; Laiko, Victor V.; Doroshenko, Vladimir M.

    2009-01-01

    A novel ion dissociation technique, which is capable of providing an efficient fragmentation of peptides at essentially atmospheric pressure conditions, is developed. The fragmentation patterns observed often contain c-type fragments that are specific to ECD/ETD, along with the y-/b- fragments that are specific to CAD. In the presented experimental setup, ion fragmentation takes place within a flow reactor located in the atmospheric pressure region between the ion source and the mass spectrometer. According to a proposed mechanism, the fragmentation results from the interaction of ESI-generated analyte ions with the gas-phase radical species produced by a corona discharge source. PMID:19034885

  20. Dimensional effects in dynamic fragmentation of brittle materials

    NASA Astrophysics Data System (ADS)

    Linna, R. P.; Åström, J. A.; Timonen, J.

    2005-07-01

    It has been shown previously that dynamic fragmentation of brittle D -dimensional objects in a D -dimensional space gives rise to a power-law contribution to the fragment-size distribution with a universal scaling exponent 2-1/D . We demonstrate that in fragmentation of two-dimensional brittle objects in three-dimensional space, an additional fragmentation mechanism appears, which causes scale-invariant secondary breaking of existing fragments. Due to this mechanism, the power law in the fragment-size distribution has now a scaling exponent of ˜1.17 .

  1. Gastric Perforation by Ingested Rabbit Bone Fragment.

    PubMed

    Gambaracci, Giulio; Mecarini, Eleonora; Franceschini, Maria Silvia; Scialpi, Michele

    2016-01-01

    The majority of accidentally ingested foreign bodies is excreted from the gastrointestinal (GI) tract without any complications. Sometimes sharp foreign bodies - like chicken and fish bones - can lead to intestinal perforation and may present insidiously with a wide range of symptoms and, consequently, different diagnoses. We report the case of a 59-year-old woman presenting with fever and a 1-month history of vague abdominal pain. Computed tomography (CT) showed the presence of a hyperdense linear image close to the gastric antrum surrounded by a fluid collection and free peritoneal air. At laparotomy, a 4-cm rabbit bone fragment covered in inflamed tissue was detected next to a gastric wall perforation. Rabbit bone fragment ingestion, even if rarely reported, should not be underestimated as a possible cause of GI tract perforation.

  2. HZEFRG1 - SEMIEMPIRICAL NUCLEAR FRAGMENTATION MODEL

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.

    1994-01-01

    The high charge and energy (HZE), Semiempirical Nuclear Fragmentation Model, HZEFRG1, was developed to provide a computationally efficient, user-friendly, physics-based program package for generating nuclear fragmentation databases. These databases can then be used in radiation transport applications such as space radiation shielding and dosimetry, cancer therapy with laboratory heavy ion beams, and simulation studies of detector design in nuclear physics experiments. The program provides individual element and isotope production cross sections for the breakup of high energy heavy ions by the combined nuclear and Coulomb fields of the interacting nuclei. The nuclear breakup contributions are estimated using an energy-dependent abrasion-ablation model of heavy ion fragmentation. The abrasion step involves removal of nucleons by direct knockout in the overlap region of the colliding nuclei. The abrasions are treated on a geometric basis and uniform spherical nuclear density distributions are assumed. Actual experimental nuclear radii obtained from tabulations of electron scattering data are incorporated. Nuclear transparency effects are included by using an energy-dependent, impact-parameter-dependent average transmission factor for the projectile and target nuclei, which accounts for the finite mean free path of nucleons in nuclear matter. The ablation step, as implemented by Bowman, Swiatecki, and Tsang (LBL report no. LBL-2908, July 1973), was treated as a single-nucleon emission for every 10 MeV of excitation energy. Fragmentation contributions from electromagnetic dissociation (EMD) processes, arising from the interacting Coulomb fields, are estimated by using the Weiszacker-Williams theory, extended to include electric dipole and electric quadrupole contributions to one-nucleon removal cross sections. HZEFRG1 consists of a main program, seven function subprograms, and thirteen subroutines. Each is fully commented and begins with a brief description of its

  3. Porous fission fragment tracks in fluorapatite

    SciTech Connect

    Li Weixing; Ewing, Rodney C.; Wang Lumin; Sun Kai; Lang, Maik; Trautmann, Christina

    2010-10-01

    Fission tracks caused by the spontaneous fission of {sup 238}U in minerals, as revealed by chemical etching, are extensively used to determine the age and thermal history of Earth's crust. Details of the structure and annealing of tracks at the atomic scale have remained elusive, as the original track is destroyed during chemical etching. By combining transmission electron microscopy with in situ heating, we demonstrate that fission tracks in fluorapatite are actually porous tubes, instead of having an amorphous core, as generally assumed. Direct observation shows thermally induced track fragmentation in fluoapatite, in clear contrast to the amorphous tracks in zircon, which gradually ''fade'' without fragmentation. Rayleigh instability and the thermal emission of vacancies control the annealing of porous fission tracks in fluorapatite.

  4. BARNARD 59: NO EVIDENCE FOR FURTHER FRAGMENTATION

    SciTech Connect

    Roman-Zuniga, C. G.; Frau, P.; Girart, J. M.; Alves, Joao F.

    2012-03-10

    The dense molecular clump at the center of the Barnard 59 (B59) complex is the only region in the Pipe Nebula that has formed a small, stellar cluster. The previous analysis of a high-resolution near-IR dust extinction map revealed that the nuclear region in B59 is a massive, mostly quiescent clump of 18.9 M{sub Sun }. The clump shows a monolithic profile, possibly indicating that the clump is on the way to collapse, with no evident fragmentation that could lead to another group of star systems. In this paper, we present new analysis that compares the dust extinction map with a new dust emission radio-continuum map of higher spatial resolution. We confirm that the clump does not show any significant evidence for prestellar fragmentation at scales smaller than those probed previously.

  5. Near Earth asteroid orbit perturbation and fragmentation

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.; Harris, Alan W.

    1992-01-01

    Collisions by near earth asteroids or the nuclei of comets pose varying levels of threat to man. A relatively small object, approximately 100 meter diameter, which might be found on an impact trajectory with a populated region of the Earth, could potentially be diverted from an Earth impacting trajectory by mass driver rocket systems. For larger bodies, such systems would appear to be beyond current technology. For any size object, nuclear explosions appear to be more efficient, using either the prompt blow-off from neutron radiation, the impulse from ejecta of near-surface explosion for deflection, or as a fragmenting charge. Practical deflections of bodies with diameters of 0.1, 1, and 10 km require interception, years to decades prior to earth encounter, with explosions a few kilotons, megatons, or gigatons, respectively, of equivalent TNT energy to achieve orbital velocity changes or destruction to a level where fragments are dispersed to harmless spatial densities.

  6. Strange quark matter fragmentation in astrophysical events

    NASA Astrophysics Data System (ADS)

    Paulucci, L.; Horvath, J. E.

    2014-06-01

    The conjecture of Bodmer-Witten-Terazawa suggesting a form of quark matter (Strange Quark Matter) as the ground state of hadronic interactions has been studied in laboratory and astrophysical contexts by a large number of authors. If strange stars exist, some violent events involving these compact objects, such as mergers and even their formation process, might eject some strange matter into the interstellar medium that could be detected as a trace signal in the cosmic ray flux. To evaluate this possibility, it is necessary to understand how this matter in bulk would fragment in the form of strangelets (small lumps of strange quark matter in which finite effects become important). We calculate the mass distribution outcome using the statistical multifragmentation model and point out several caveats affecting it. In particular, the possibility that strangelets fragmentation will render a tiny fraction of contamination in the cosmic ray flux is discussed.

  7. Fragment screening using X-ray crystallography.

    PubMed

    Davies, Thomas G; Tickle, Ian J

    2012-01-01

    The fragment-based approach is now well established as an important component of modern drug discovery. A key part in establishing its position as a viable technique has been the development of a range of biophysical methodologies with sufficient sensitivity to detect the binding of very weakly binding molecules. X-ray crystallography was one of the first techniques demonstrated to be capable of detecting such weak binding, but historically its potential for screening was under-appreciated and impractical due to its relatively low throughput. In this chapter we discuss the various benefits associated with fragment-screening by X-ray crystallography, and describe the technical developments we have implemented to allow its routine use in drug discovery. We emphasize how this approach has allowed a much greater exploitation of crystallography than has traditionally been the case within the pharmaceutical industry, with the rapid and timely provision of structural information having maximum impact on project direction.

  8. Application of microtomography and image analysis to the quantification of fragmentation in ceramics after impact loading

    NASA Astrophysics Data System (ADS)

    Forquin, Pascal; Ando, Edward

    2017-01-01

    Silicon carbide ceramics are widely used in personal body armour and protective solutions. However, during impact, an intense fragmentation develops in the ceramic tile due to high-strain-rate tensile loadings. In this work, microtomography equipment was used to analyse the fragmentation patterns of two silicon carbide grades subjected to edge-on impact (EOI) tests. The EOI experiments were conducted in two configurations. The so-called open configuration relies on the use of an ultra-high-speed camera to visualize the fragmentation process with an interframe time set to 1 µs. The so-called sarcophagus configuration consists in confining the target in a metallic casing to avoid any dispersion of fragments. The target is infiltrated after impact so the final damage pattern is entirely scanned using X-ray tomography and a microfocus source. Thereafter, a three-dimensional (3D) segmentation algorithm was tested and applied in order to separate fragments in 3D allowing a particle size distribution to be obtained. Significant differences between the two specimens of different SiC grades were noted. To explain such experimental results, numerical simulations were conducted considering the Denoual-Forquin-Hild anisotropic damage model. According to the calculations, the difference of crack pattern in EOI tests is related to the population of defects within the two ceramics. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  9. Recurrent Sleep Fragmentation Induces Insulin and Neuroprotective Mechanisms in Middle-Aged Flies

    PubMed Central

    Williams, Michael J.; Perland, Emelie; Eriksson, Mikaela M.; Carlsson, Josef; Erlandsson, Daniel; Laan, Loora; Mahebali, Tabusi; Potter, Ella; Frediksson, Robert; Benedict, Christian; Schiöth, Helgi B.

    2016-01-01

    Lack of quality sleep increases central nervous system oxidative stress and impairs removal of neurotoxic soluble metabolites from brain parenchyma. During aging poor sleep quality, caused by sleep fragmentation, increases central nervous system cellular stress. Currently, it is not known how organisms offset age-related cytotoxic metabolite increases in order to safeguard neuronal survival. Furthermore, it is not understood how age and sleep fragmentation interact to affect oxidative stress protection pathways. We demonstrate sleep fragmentation increases systems that protect against oxidative damage and neuroprotective endoplasmic reticulum molecular chaperones, as well as neuronal insulin and dopaminergic expression in middle-aged Drosophila males. Interestingly, even after sleep recovery the expression of these genes was still upregulated in middle-aged flies. Finally, sleep fragmentation generates higher levels of reactive oxygen species (ROS) in middle-aged flies and after sleep recovery these levels remain significantly higher than in young flies. The fact that neuroprotective pathways remain upregulated in middle-aged flies beyond sleep fragmentation suggests it might represent a strong stressor for the brain during later life. PMID:27531979

  10. Application of microtomography and image analysis to the quantification of fragmentation in ceramics after impact loading.

    PubMed

    Forquin, Pascal; Ando, Edward

    2017-01-28

    Silicon carbide ceramics are widely used in personal body armour and protective solutions. However, during impact, an intense fragmentation develops in the ceramic tile due to high-strain-rate tensile loadings. In this work, microtomography equipment was used to analyse the fragmentation patterns of two silicon carbide grades subjected to edge-on impact (EOI) tests. The EOI experiments were conducted in two configurations. The so-called open configuration relies on the use of an ultra-high-speed camera to visualize the fragmentation process with an interframe time set to 1 µs. The so-called sarcophagus configuration consists in confining the target in a metallic casing to avoid any dispersion of fragments. The target is infiltrated after impact so the final damage pattern is entirely scanned using X-ray tomography and a microfocus source. Thereafter, a three-dimensional (3D) segmentation algorithm was tested and applied in order to separate fragments in 3D allowing a particle size distribution to be obtained. Significant differences between the two specimens of different SiC grades were noted. To explain such experimental results, numerical simulations were conducted considering the Denoual-Forquin-Hild anisotropic damage model. According to the calculations, the difference of crack pattern in EOI tests is related to the population of defects within the two ceramics.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  11. A nuclear fragmentation energy deposition model

    NASA Technical Reports Server (NTRS)

    Ngo, D. M.; Wilson, J. W.; Fogarty, T. N.; Buck, W. W.; Townsend, L. W. (Principal Investigator)

    1991-01-01

    A formalism for target fragment transport is presented with application to energy loss spectra in thin silicon devices. A nuclear data base is recommended that agrees well with the measurements of McNulty et al. using surface barrier detectors. High-energy events observed by McNulty et al., which are not predicted by intranuclear cascade models, are well represented by the present work.

  12. Large ejecta fragments from asteroids. [Abstract only

    NASA Technical Reports Server (NTRS)

    Asphaug, E.

    1994-01-01

    The asteroid 4 Vesta, with its unique basaltic crust, remains a key mystery of planetary evolution. A localized olivine feature suggests excavation of subcrustal material in a crater or impact basin comparable in size to the planetary radius (R(sub vesta) is approximately = 280 km). Furthermore, a 'clan' of small asteroids associated with Vesta (by spectral and orbital similarities) may be ejecta from this impact 151 and direct parents of the basaltic achondrites. To escape, these smaller (about 4-7 km) asteroids had to be ejected at speeds greater than the escape velocity, v(sub esc) is approximately = 350 m/s. This evidence that large fragments were ejected at high speed from Vesta has not been reconciled with the present understanding of impact physics. Analytical spallation models predict that an impactor capable of ejecting these 'chips off Vesta' would be almost the size of Vesta! Such an impact would lead to the catastrophic disruption of both bodies. A simpler analysis is outlined, based on comparison with cratering on Mars, and it is shown that Vesta could survive an impact capable of ejecting kilometer-scale fragments at sufficient speed. To what extent does Vesta survive the formation of such a large crater? This is best addressed using a hydrocode such as SALE 2D with centroidal gravity to predict velocities subsequent to impact. The fragmentation outcome and velocity subsequent to the impact described to demonstrate that Vesta survives without large-scale disassembly or overturning of the crust. Vesta and its clan represent a valuable dataset for testing fragmentation hydrocodes such as SALE 2D and SPH 3D at planetary scales. Resolution required to directly model spallation 'chips' on a body 100 times as large is now marginally possible on modern workstations. These boundaries are important in near-surface ejection processes and in large-scale disruption leading to asteroid families and stripped cores.

  13. Mechanisms of fragmentation of cationic peptide ions

    NASA Astrophysics Data System (ADS)

    Zhao, Hong; Adams, Jeanette

    1993-06-01

    Fragmentation mechanisms for formation of several commonly occurring product ions in high-energy collision-induced induced decomposition spectra of either (M + Cat2+ - H)+ ions of peptides cationized with alkaline earth metal ions, (M + Ca+)+ ions cationized with alkali metal ions, or (M + H)+ ions are evaluated by using deuterium-labelled peptides. The different sources of hydrogen transferred in the reactions are identified. Our study supports some previously proposed mechanisms but also provides evidence for others.

  14. String Fragmentation Model in Space Radiation Problems

    NASA Technical Reports Server (NTRS)

    Tang, Alfred; Johnson, Eloise (Editor); Norbury, John W.; Tripathi, R. K.

    2002-01-01

    String fragmentation models such as the Lund Model fit experimental particle production cross sections very well in the high-energy limit. This paper gives an introduction of the massless relativistic string in the Lund Model and shows how it can be modified with a simple assumption to produce formulas for meson production cross sections for space radiation research. The results of the string model are compared with inclusive pion production data from proton-proton collision experiments.

  15. Antibody Fragments as Probe in Biosensor Development

    PubMed Central

    Saerens, Dirk; Huang, Lieven; Bonroy, Kristien; Muyldermans, Serge

    2008-01-01

    Today's proteomic analyses are generating increasing numbers of biomarkers, making it essential to possess highly specific probes able to recognize those targets. Antibodies are considered to be the first choice as molecular recognition units due to their target specificity and affinity, which make them excellent probes in biosensor development. However several problems such as difficult directional immobilization, unstable behavior, loss of specificity and steric hindrance, may arise from using these large molecules. Luckily, protein engineering techniques offer designed antibody formats suitable for biomarker analysis. Minimization strategies of antibodies into Fab fragments, scFv or even single-domain antibody fragments like VH, VL or VHHs are reviewed. Not only the size of the probe but also other issues like choice of immobilization tag, type of solid support and probe stability are of critical importance in assay development for biosensing. In this respect, multiple approaches to specifically orient and couple antibody fragments in a generic one-step procedure directly on a biosensor substrate are discussed. PMID:27873779

  16. Cationized Carbohydrate Gas-Phase Fragmentation Chemistry.

    PubMed

    Bythell, Benjamin J; Abutokaikah, Maha T; Wagoner, Ashley R; Guan, Shanshan; Rabus, Jordan M

    2016-11-28

    We investigate the fragmentation chemistry of cationized carbohydrates using a combination of tandem mass spectrometry, regioselective labeling, and computational methods. Our model system is D-lactose. Barriers to the fundamental glyosidic bond cleavage reactions, neutral loss pathways, and structurally informative cross-ring cleavages are investigated. The most energetically favorable conformations of cationized D-lactose were found to be similar. In agreement with the literature, larger group I cations result in structures with increased cation coordination number which require greater collision energy to dissociate. In contrast with earlier proposals, the B n -Y m fragmentation pathways of both protonated and sodium-cationized analytes proceed via protonation of the glycosidic oxygen with concerted glycosidic bond cleavage. Additionally, for the sodiated congeners our calculations support sodiated 1,6-anhydrogalactose B n ion structures, unlike the preceding literature. This affects the subsequent propensity of formation and prediction of B n /Y m branching ratio. The nature of the anomeric center (α/β) affects the relative energies of these processes, but not the overall ranking. Low-energy cross-ring cleavages are observed for the metal-cationized analytes with a retro-aldol mechanism producing the (0,2) A 2 ion from the sodiated forms. Theory and experiment support the importance of consecutive fragmentation processes, particularly for the protonated congeners at higher collision energies. Graphical Abstract ᅟ.

  17. Fibril Fragmentation Enhances Amyloid Cytotoxicity*♦

    PubMed Central

    Xue, Wei-Feng; Hellewell, Andrew L.; Gosal, Walraj S.; Homans, Steve W.; Hewitt, Eric W.; Radford, Sheena E.

    2009-01-01

    Fibrils associated with amyloid disease are molecular assemblies of key biological importance, yet how cells respond to the presence of amyloid remains unclear. Cellular responses may not only depend on the chemical composition or molecular properties of the amyloid fibrils, but their physical attributes such as length, width, or surface area may also play important roles. Here, we report a systematic investigation of the effect of fragmentation on the structural and biological properties of amyloid fibrils. In addition to the expected relationship between fragmentation and the ability to seed, we show a striking finding that fibril length correlates with the ability to disrupt membranes and to reduce cell viability. Thus, despite otherwise unchanged molecular architecture, shorter fibrillar samples show enhanced cytotoxic potential than their longer counterparts. The results highlight the importance of fibril length in amyloid disease, with fragmentation not only providing a mechanism by which fibril load can be rapidly increased but also creating fibrillar species of different dimensions that can endow new or enhanced biological properties such as amyloid cytotoxicity. PMID:19808677

  18. Mitochondrial fragmentation in excitotoxicity requires ROCK activation.

    PubMed

    Martorell-Riera, Alejandro; Segarra-Mondejar, Marc; Reina, Manuel; Martínez-Estrada, Ofelia M; Soriano, Francesc X

    2015-01-01

    Mitochondria morphology constantly changes through fission and fusion processes that regulate mitochondrial function, and it therefore plays a prominent role in cellular homeostasis. Cell death progression is associated with mitochondrial fission. Fission is mediated by the mainly cytoplasmic Drp1, which is activated by different post-translational modifications and recruited to mitochondria to perform its function. Our research and other studies have shown that in the early moments of excitotoxic insult Drp1 must be nitrosylated to mediate mitochondrial fragmentation in neurons. Nonetheless, mitochondrial fission is a multistep process in which filamentous actin assembly/disassembly and myosin-mediated mitochondrial constriction play prominent roles. Here we establish that in addition to nitric oxide production, excitotoxicity-induced mitochondrial fragmentation also requires activation of the actomyosin regulator ROCK. Although ROCK1 has been shown to phosphorylate and activate Drp1, experiments using phosphor-mutant forms of Drp1 in primary cortical neurons indicate that in excitotoxic conditions, ROCK does not act directly on Drp1 to mediate fission, but may act on the actomyosin complex. Thus, these data indicate that a wider range of signaling pathways than those that target Drp1 are amenable to be inhibited to prevent mitochondrial fragmentation as therapeutic option.

  19. Cationized Carbohydrate Gas-Phase Fragmentation Chemistry

    NASA Astrophysics Data System (ADS)

    Bythell, Benjamin J.; Abutokaikah, Maha T.; Wagoner, Ashley R.; Guan, Shanshan; Rabus, Jordan M.

    2016-11-01

    We investigate the fragmentation chemistry of cationized carbohydrates using a combination of tandem mass spectrometry, regioselective labeling, and computational methods. Our model system is D-lactose. Barriers to the fundamental glyosidic bond cleavage reactions, neutral loss pathways, and structurally informative cross-ring cleavages are investigated. The most energetically favorable conformations of cationized D-lactose were found to be similar. In agreement with the literature, larger group I cations result in structures with increased cation coordination number which require greater collision energy to dissociate. In contrast with earlier proposals, the B n -Y m fragmentation pathways of both protonated and sodium-cationized analytes proceed via protonation of the glycosidic oxygen with concerted glycosidic bond cleavage. Additionally, for the sodiated congeners our calculations support sodiated 1,6-anhydrogalactose B n ion structures, unlike the preceding literature. This affects the subsequent propensity of formation and prediction of B n /Y m branching ratio. The nature of the anomeric center (α/β) affects the relative energies of these processes, but not the overall ranking. Low-energy cross-ring cleavages are observed for the metal-cationized analytes with a retro-aldol mechanism producing the 0,2 A 2 ion from the sodiated forms. Theory and experiment support the importance of consecutive fragmentation processes, particularly for the protonated congeners at higher collision energies.

  20. Fragmentation of hypervelocity aluminum projectiles on fabrics

    NASA Astrophysics Data System (ADS)

    Rudolph, Martin; Schäfer, Frank; Destefanis, Roberto; Faraud, Moreno; Lambert, Michel

    2012-07-01

    This paper presents work performed for a study investigating the ability of different flexible materials to induce fragmentation of a hypervelocity projectile. Samples were chosen to represent a wide range of industrially available types of flexible materials like ceramic, aramid and carbon fabrics as well as a thin metallic mesh. Impact conditions and areal density were kept constant for all targets. Betacloth and multi-layer insulation (B-MLI) are mounted onto the targets to account for thermal system engineering requirements. All tests were performed using the Space light-gas gun facility (SLGG) of the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI. Projectiles were aluminum spheres with 5 mm diameter impacting at approximately 6.3 km/s. Fragmentation was evaluated using a witness plate behind the target. An aramid and a ceramic fabric lead the ranking of fabrics with the best projectile fragmentation and debris cloud dispersion performance. A comparison with an equal-density rigid aluminum plate is presented. The work presented can be applied to optimize the micrometeoroid and space debris (MM/SD) shielding structure of inflatable modules.

  1. The Evolution of Grain Size Distribution in Explosive Rock Fragmentation - Sequential Fragmentation Theory Revisited

    NASA Astrophysics Data System (ADS)

    Scheu, B.; Fowler, A. C.

    2015-12-01

    Fragmentation is a ubiquitous phenomenon in many natural and engineering systems. It is the process by which an initially competent medium, solid or liquid, is broken up into a population of constituents. Examples occur in collisions and impacts of asteroids/meteorites, explosion driven fragmentation of munitions on a battlefield, as well as of magma in a volcanic conduit causing explosive volcanic eruptions and break-up of liquid drops. Besides the mechanism of fragmentation the resulting frequency-size distribution of the generated constituents is of central interest. Initially their distributions were fitted empirically using lognormal, Rosin-Rammler and Weibull distributions (e.g. Brown & Wohletz 1995). The sequential fragmentation theory (Brown 1989, Wohletz at al. 1989, Wohletz & Brown 1995) and the application of fractal theory to fragmentation products (Turcotte 1986, Perfect 1997, Perugini & Kueppers 2012) attempt to overcome this shortcoming by providing a more physical basis for the applied distribution. Both rely on an at least partially scale-invariant and thus self-similar random fragmentation process. Here we provide a stochastic model for the evolution of grain size distribution during the explosion process. Our model is based on laboratory experiments in which volcanic rock samples explode naturally when rapidly depressurized from initial pressures of several MPa to ambient conditions. The physics governing this fragmentation process has been successfully modelled and the observed fragmentation pattern could be numerically reproduced (Fowler et al. 2010). The fragmentation of these natural rocks leads to grain size distributions which vary depending on the experimental starting conditions. Our model provides a theoretical description of these different grain size distributions. Our model combines a sequential model of the type outlined by Turcotte (1986), but generalized to cater for the explosive process appropriate here, in particular by

  2. Time reversal odd fragmentation functions in semi-inclusive deep inelastic lepton-hadron scattering

    SciTech Connect

    Mulders, P.J.; Levelt, J.

    1994-04-01

    In semi-inclusive scattering of polarized leptons from unpolarized hadrons, one can measure a time reversal odd structure function. It shows up as a sin({phi}) asymmetry of the produced hadrons. This asymmetry can be expressed as the product of a twist-three {open_quotes}hadron {r_arrow} quark{close_quotes} profile function and a time reversal odd twist-two {open_quotes}quark {r_arrow} hadron{close_quotes} fragmentation function. This fragmentation function can only be measured for nonzero transverse momenta of the produced hadron. Its appearance is a consequence of final state interactions between the produced hadron and the rest of the final state.

  3. Apollo 14 Lunar glass fragment known as Genesis bean

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A tiny green glass fragment taken from an Apollo 14 core tube sampling. Because of its scientific significance and shape, the fragment has been nicknamed the 'Genesis bean'. The main constituents are iron and magnesium.

  4. LOCALIZING NATIONAL FRAGMENTATION STATISTICS WITH FOREST TYPE MAPS

    EPA Science Inventory

    Fragmmentation of forest types is an indicator of biodiversity in the Montreal Process, but the available national data permit assessment of only overall forestland fragmentation, not forest type fragmentation. Here we illustrate how to localize national statistics from the 2003...

  5. FRAGMENTATION AND SPREADING OF A METEOR-LIKE OBJECT

    SciTech Connect

    Park, Chul; Brown, Jeffrey D.

    2012-12-01

    The phenomenon of fragmentation and spreading of a high-speed flying object resembling a meteorite is studied experimentally and theoretically. Experimentally, a model made of graphite is launched in a ballistic range and is made to fragment and spread. The flow field produced by the cloud of the fragments is observed optically. The observed deceleration and spreading behavior is numerically reconstructed using computational-fluid-dynamic calculations, applying an improved meteoroid fragmentation theory. The existing meteoroid fragmentation theory is improved by introducing the hypothesis that the incubation process of the pressurized fluid permeating through the fragment precedes the splitting process. The incubation time is determined by the ratio of permeability of the fragment to the fluid's viscosity and is much longer than the time for splitting given by the existing theory. Agreement is obtained between the observed and calculated behavior of the fragment cloud by appropriately choosing this ratio.

  6. An All-Fragments Grammar for Simple and Accurate Parsing

    DTIC Science & Technology

    2012-03-21

    present a simple but accurate parser which exploits both large tree fragments and symbol refinement. We parse with all fragments of the training set...in contrast to much recent work on tree selection in data-oriented parsing and tree -substitution grammar learning. We require only simple...which exploits both large tree fragments and sym- bol refinement. We parse with all fragments of the training set, in contrast to much recent work on

  7. Fast fragments: the development of a parallel effective fragment potential method.

    PubMed

    Netzloff, Heather M; Gordon, Mark S

    2004-11-30

    The Effective Fragment Potential (EFP) method for solvation decreases the cost of a fully quantum mechanical calculation by dividing a chemical system into an ab initio region that contains the solute plus some number of solvent molecules, if desired, and an "effective fragment" region that contains the remaining solvent molecules. Interactions introduced with this fragment region (for example, Coulomb and polarization interactions) are added as one-electron terms to the total system Hamiltonian. As larger systems and dynamics are just starting to be studied with the EFP method, more needs to be done to decrease the calculation time of the method. This article considers parallelization of both the EFP fragment-fragment and mixed quantum mechanics (QM)-EFP interaction energy and gradient computation within the GAMESS suite of programs. The iteratively self-consistent polarization term is treated with a new algorithm that makes use of nonblocking communication to obtain better scalability. Results show that reasonable speedup is achieved with a variety of sizes of water clusters and number of processors.

  8. Electron impact fragmentation of adenine: partial ionization cross sections for positive fragments

    NASA Astrophysics Data System (ADS)

    van der Burgt, Peter J. M.; Finnegan, Sinead; Eden, Samuel

    2015-07-01

    Using computer-controlled data acquisition we have measured mass spectra of positive ions for electron impact on adenine, with electron energies up to 100 eV. Ion yield curves for 50 ions have been obtained and normalized by comparing their sum to the average of calculated total ionization cross sections. Appearance energies have been determined for 37 ions; for 20 ions for the first time. All appearance energies are consistent with the fragmentation pathways identified in the literature. Second onset energies have been determined for 12 fragment ions (for 11 ions for the first time), indicating the occurrence of more than one fragmentation process e.g. for 39 u (C2HN+) and 70 u (C2H4N3+). Matching ion yield shapes (118-120 u, 107-108 u, 91-92 u, and 54-56 u) provide new evidence supporting closely related fragmentation pathways and are attributed to hydrogen rearrangement immediately preceding the fragmentation. We present the first measurement of the ion yield curve of the doubly charged parent ion (67.5 u), with an appearance energy of 23.5 ± 1.0 eV. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene Surdutovich.

  9. Filament fragmentation in high-mass star formation

    NASA Astrophysics Data System (ADS)

    Beuther, H.; Ragan, S. E.; Johnston, K.; Henning, Th.; Hacar, A.; Kainulainen, J. T.

    2015-12-01

    be due to no significant gas flows along the filamentary axis, but it may also be partly caused by a low inclination angle of the filament with respect to the plane of the sky minimizing such a signature. Conclusions: The IRDC 18223 3.2 mm continuum data are consistent with thermal fragmentation of a gravitationally bound and compressible gas cylinder. However, the high mass-to-length ratio requires additional support - most likely turbulence and/or magnetic fields - against collapse. The N2H+ spectral line data indicate a kinematic origin of the filament, but we cannot conclusively differentiate whether it has formed out of (pre-existing) velocity-coherent subfilaments, whether magnetized converging gas flows, a larger-scale collapsing cloud, or even whether rotation played a significant role during filament formation. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).Final reduced data cubes (FITS) are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/584/A67

  10. Separation and structure elucidation of coal molecule fragments. Final report, February 1, 1976-August 31, 1979

    SciTech Connect

    Schultz, R V; Jorgenson, J W; Maskarinec, M P; Kump, R L; Marli, F; Novotny, M; Todd, L J

    1980-01-01

    Separation and identification of the polynuclear aromatic and aliphatic fractions of solvent-refined coal and its recycle oil were performed using a combination of solvent partition and chromatographic fractionation procedures with glass-capillary gas chromatography/mass spectrometry. Chromatographic profiles were generated for each fraction and some semiquantitative data were also obtained. In total, 146 polynuclear aromatic components of SRC were tentatively identified by their molecular weights, as indicated by the mass spectra of the gas chromatography peaks. In addition, wherever possible, specific isomers have been indicated, based on comparison of spectral characteristics and retention data. Separation and identification of nitrogen-containing aromatics of the recycle oil of SRC was accomplished with a combination solvent partition and capillary gas chromatography with deactivated glass columns. High-precision retention measurements of known pyridine and quinoline derivatives are reported, utilizing parent aza-arenes as retention standards. Both precisely measured retention data and mass spectral information combined lead to positive identification of some compounds in SRC samples. A total of 48 two-membered or three-membered aza-arenes have been tentatively identified in the recycle oil.

  11. Final report: Accelerated beta decay for disposal of fission fragment wastes

    SciTech Connect

    Reiss, Howard R.

    2000-03-06

    The fundamental theory of the interaction of intense, low-frequency electromagnetic fields with certain radioactive nuclei has been fully formulated. The nuclei are of the type that exists in high-level radioactive wastes that are end products of the production of energy from nuclear fission. The basic physical mechanisms that underlie the coupling of the applied field to the nucleus have been identified. Both the basic theory and numerical predictions that stem from it support the conclusion that high-level radioactive wastes can be disposed of by substantially accelerating the rate of radioactive decay. Some old experiments on the acceleration of this type of radioactivity, with results that were not understood at the time, have been re-examined. Their interpretation is now clear, and the experiments are found to be in agreement with the theory.

  12. Pyrite thermochemistry, ash agglomeration, and char fragmentation during pulverized coal combustion. Final technical report

    SciTech Connect

    Akan-Etuk, A.; Diaz, R.; Niksa, S.

    1991-10-01

    The objective of the present work is to introduce an experimental program that will eventually lead to time-resolved iron ash composition over the technological operating domain. The preceding literature survey suggests two important stipulations on any such experimental program. The first stipulation is that good control must be established over the operating conditions, to accurately quantify their effects. The other is that data must be obtained rapidly, to thoroughly cover the important operating domain. This work presents a series of studies that has characterized the desulfurization of pyrite during the early stages of combustion. An experimental system was established and used to monitor the effects of oxygen, temperature, and residence time on the evolution of condensed phase products of the combustion of pure pyrite. (VC)

  13. Unusual Fragmentation Pathways in Collagen Glycopeptides

    NASA Astrophysics Data System (ADS)

    Perdivara, Irina; Perera, Lalith; Sricholpech, Marnisa; Terajima, Masahiko; Pleshko, Nancy; Yamauchi, Mitsuo; Tomer, Kenneth B.

    2013-07-01

    Collagens are the most abundant glycoproteins in the body. One characteristic of this protein family is that the amino acid sequence consists of repeats of three amino acids -(X—Y—Gly)n. Within this motif, the Y residue is often 4-hydroxyproline (HyP) or 5-hydroxylysine (HyK). Glycosylation in collagen occurs at the 5-OH group in HyK in the form of two glycosides, galactosylhydroxylysine (Gal-HyK) and glucosyl galactosylhydroxylysine (GlcGal-HyK). In collision induced dissociation (CID), collagen tryptic glycopeptides exhibit unexpected gas-phase dissociation behavior compared to typical N- and O-linked glycopeptides (i.e., in addition to glycosidic bond cleavages, extensive cleavages of the amide bonds are observed). The Gal- or GlcGal- glycan modifications are largely retained on the fragment ions. These features enable unambiguous determination of the amino acid sequence of collagen glycopeptides and the location of the glycosylation site. This dissociation pattern was consistent for all analyzed collagen glycopeptides, regardless of their length or amino acid composition, collagen type or tissue. The two fragmentation pathways—amide bond and glycosidic bond cleavage—are highly competitive in collagen tryptic glycopeptides. The number of ionizing protons relative to the number of basic sites (i.e., Arg, Lys, HyK, and N-terminus) is a major driving force of the fragmentation. We present here our experimental results and employ quantum mechanics calculations to understand the factors enhancing the labile character of the amide bonds and the stability of hydroxylysine glycosides in gas phase dissociation of collagen glycopeptides.

  14. Unusual fragmentation pathways in collagen glycopeptides

    PubMed Central

    Perdivara, Irina; Perera, Lalith; Sricholpech, Marnisa; Terajima, Masahiko; Pleshko, Nancy; Yamauchi, Mitsuo; Tomer, Kenneth B.

    2013-01-01

    Collagens are the most abundant glycoproteins in the body. One characteristic of this protein family is that the amino acid sequence consists of repeats of three amino acids –(X—Y—Gly)n. Within this motif, the Y residue is often 4-hydroxyproline (HyP) or 5-hydroxylysine (HyK). Glycosylation in collagen occurs at the 5-OH group in HyK in the form of two glycosides, galactosylhydroxylysine (Gal-HyK) and glucosyl galactosylhydroxylysine (GlcGal-HyK). In collision induced dissociation (CID), collagen tryptic glycopeptides exhibit unexpected gas-phase dissociation behavior compared to typical N- and O-linked glycopeptides, i.e. in addition to glycosidic bond cleavages, extensive cleavages of the amide bonds are observed. The Gal- or GlcGal- glycan modifications are largely retained on the fragment ions. These features enable unambiguous determination of the amino acid sequence of collagen glycopeptides and the location of the glycosylation site. This dissociation pattern was consistent for all analyzed collagen glycopeptides, regardless of their length or amino acid composition, collagen type or tissue. The two fragmentation pathways – amide bond and glycosidic bond cleavage – are highly competitive in collagen tryptic glycopeptides. The number of ionizing protons relative to the number of basic sites (i.e. Arg, Lys, HyK and N-terminus) is a major driving force of the fragmentation. We present here our experimental results and employ quantum mechanics calculations, to understand the factors enhancing the labile character of the amide bonds and the stability of hydroxylysine glycosides in gas phase dissociation of collagen glycopeptides. PMID:23633013

  15. Single-Chain Fragment Variable Antibody Piezoimmunosensors

    PubMed Central

    Shen, Zhihong; Stryker, Gabrielle A.; Mernaugh, Ray L.; Yu, Lei; Yan, Heping; Zeng, Xiangqun

    2008-01-01

    In this paper, we describe a novel nonlabeled biosensor with high diagnostic potential for rapid and sensitive detection of antigens in complex biological samples. The biosensor comprises a piezoimmunosensor (PZ) displaying a specially constructed recombinant antibody on its surface. The recombinant single-chain fragment variable (scFv) antibody contained a cysteine within the linker amino acid sequence used to join the scFv variable heavy and light chains. The presence of cysteine induced the scFv construct to self-assemble as a densely packed rigid monolayer on the gold surface of a quartz crystal microbalance. scFv molecules in this self-assembled mono-layer (SAM) exhibited a defined orientation and high areal densities, with scFv-modified microbalance surfaces displaying 35 times as many variable antigen-binding sites per square centimeter as surfaces modified with whole antibody. Experimental data show that the scFv SAM PZ is superior to Fab fragment, Fab fragment containing a free sulfhydryl group (i.e., Fab-SH), and whole antibody PZs regarding sensitivity and specificity. Because of their small uniform size (MW ≈ 27000) and the ease with which they can be modified using genetic engineering, scFv’s have significant advantages over whole antibodies in microbalance biosensor systems. We demonstrate here that the use of scFv containing a cysteine within the scFv linker sequence (i.e., scFv-cys) for preparation of biosensor surfaces markedly increases the density of available antigen-binding sites, yielding a system that is highly selective, rapid, and capable of detecting low concentrations of antigens in complex samples. PMID:15679346

  16. Negative Ion CID Fragmentation of O-linked Oligosaccharide Aldoses—Charge Induced and Charge Remote Fragmentation

    NASA Astrophysics Data System (ADS)

    Doohan, Roisin A.; Hayes, Catherine A.; Harhen, Brendan; Karlsson, Niclas Göran

    2011-06-01

    Collision induced dissociation (CID) fragmentation was compared between reducing and reduced sulfated, sialylated, and neutral O-linked oligosaccharides. It was found that fragmentation of the [M - H]- ions of aldoses with acidic residues gave unique Z-fragmentation of the reducing end GalNAc containing the acidic C-6 branch, where the entire C-3 branch was lost. This fragmentation pathway, which is not seen in the alditols, showed that the process involved charge remote fragmentation catalyzed by a reducing end acidic anomeric proton. With structures containing sialic acid on both the C-3 and C-6 branch, the [M - H]- ions were dominated by the loss of sialic acid. This fragmentation pathway was also pronounced in the [M - 2H]2- ions revealing both the C-6 Z-fragment plus its complementary C-3 C-fragment in addition to glycosidic and cross ring fragmentation. This generation of the Z/C-fragment pairs from GalNAc showed that the charges were not participating in their generation. Fragmentation of neutral aldoses showed pronounced Z-fragmentation believed to be generated by proton migration from the C-6 branch to the negatively charged GalNAc residue followed by charge remote fragmentation similar to the acidic oligosaccharides. In addition, A-type fragments generated by charge induced fragmentation of neutral oligosaccharides were observed when the charge migrated from C-1 of the GalNAc to the GlcNAc residue followed by rearrangement to accommodate the 0,2A-fragmentation. LC-MS also showed that O-linked aldoses existed as interchangeable α/β pyranose anomers, in addition to a third isomer (25% of the total free aldose) believed to be the furanose form.

  17. Projectile fragmentation wall for CHICSi detector

    NASA Astrophysics Data System (ADS)

    Budzanowski, A.; Czech, B.; Siwek, A.; Skwirczyńska, I.; Staszel, P.; CHIC Collaboration

    2002-04-01

    The Forward Wall Detector (FWD) is designed to identify projectile-like fragments from heavy-ion reactions at the CELSIUS storage ring in Uppsala, Sweden. FWD covers the polar angle from 3.9° to 11.7° with geometrical efficiency of 81%. The single-detection module can be either of phoswich type (10 mm fast plastic+80 mm CsI(Tl)) or Δ E- E telescope (750 μm Si+80 mm CsI(Tl)). It is expected to have charge identification up to Z=18 and mass resolution for H and He isotopes.

  18. Melt inclusions in Luna 24 soil fragments

    NASA Technical Reports Server (NTRS)

    Roedder, W.; Weiblen, P. W.

    1978-01-01

    Optical examinations of 28 slides of Luna 24 soil fragments revealed melt inclusions in grains of olivine, plagioclase, spinel, and ilmenite as well as interstitial inclusions. In contrast with Apollo samples, the Luna 24 samples contain sulfide melt inclusions, which indicates that saturation with respect to an iron sulfide melt took place throughout much of the crystallization history, even while olivine was crystallizing. The Luna 24 silicate-melt inclusions have recorded a more extensive differentiation toward higher iron magmas than have the Apollo inclusions, but they have also recorded some inexplicably low aluminum values.

  19. Magnetic Support and Fragmentation of Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Carlberg, R. G.; Pudritz, R. E.

    1990-12-01

    Molecular clouds contain magnetic fields with energies comparable to their gravitational binding energies. In the dynamic environment of the interstellar medium, strong hydromagnetic waves are excited in this field on wavelengths longer than the ion-neutral mean free path. In a typical molecular cloud this length-scale, λmin, is of the order of 10-1 of the cloud size. On shorter length-scales the gas is without wave pressure support, and can flow down field lines. The joint effects of excess gravity and flux leakage causes a local dynamic collapse. We test our ideas with a detailed -body calculation in which we impose MHD waves on an initially uniform isothermal gas cloud. The effect of magnetic fields is included in our calculation by the frictional drag on the dominant, neutral population. In the absence of MHD waves the cloud fragments slightly while collapsing, then merges together at the centre into a single, pressure-supported, flattened object. We impose a spectrum of large amplitude Alfvén waves whose velocity amplitude varies as k-3/2, where k is the wavenumber. The initial background magnetic field is chosen to have an energy density slightly larger than the gravitational energy density. The damping is assumed to be balanced by a continuous external supply of wave energy. The simulation shows that the magnetic field and hydromagnetic waves provide sufficient support against gravity so that the cloud undergoes a global, isotropic contraction at a quarter the free-fall rate. The shortest wave present, λ≍λmin, sets the minimum fragment mass, for small Jeans masses. We follow the evolution of fragments having a minimum overdensity of 30 (corresponding to a mass m ≥ 0.4 × 10-3 Mcloud). The fragments appear quickly, and then agglomerate together, yielding an evolving mass spectrum that remains approximately a power law, dN/dm ∝ m-α, where a is 2.5 ± 0.5. Several specific tests of this theory are proposed: (i) that a short wavelength cut

  20. Habitat fragmentation threatens wild populations of Carica papaya (Caricaceae) in a lowland rainforest.

    PubMed

    Chávez-Pesqueira, Mariana; Suárez-Montes, Pilar; Castillo, Guillermo; Núñez-Farfán, Juan

    2014-07-01

    • Premise of the study: Wild populations of domesticated species constitute a genetic reservoir and are fundamental to the evolutionary potential of species. Wild papaya (Carica papaya) is a rare, short-lived, gap-colonizing, dioecious tree that persists in the forest by continuous dispersal. Theoretically, these life-history characteristics render wild papaya highly susceptible to habitat fragmentation, with anticipated negative effects on its gene pool. Further, species dioecy may cause founder effects to generate local biases in sex ratio, decreasing effective population size.• Methods: We contrasted the genetic diversity and structure of C. papaya between wild populations from rainforest fragments and continuous forest at Los Tuxtlas, Mexico. We evaluated recent migration rates among populations as well as landscape resistance to gene flow. Finally, we calculated the sex ratio of the populations in both habitats.• Key results: Populations of wild papaya in rainforest fragments showed lower genetic diversity and higher population differentiation than populations in continuous rainforest. Estimates of recent migration rates showed a higher percentage of migrants moving from the continuous forest to the forest fragments than in the opposite direction. Agricultural land and cattle pasture were found to be the most resistant matrices to gene flow. Finally, biased sex ratios were seen to affect the effective population size in both habitats.• Conclusions: The mating system, rarity, and short life cycle of C. papaya are exacerbating the effects of rainforest fragmentation on its genetic diversity, threatening the persistence of its natural populations in the proposed place of origin as well as its genetic reservoir.

  1. High Explosive Deonation Threshold Sensitivity Due to Multiple Fragment Impacts

    SciTech Connect

    Georgevich, V; Pincosy, P; Chase, J

    2004-01-07

    Fragments, bullets or projectiles can initiate a detonation in a high explosive (HE). For this to happen certain critical conditions need to be exceeded. For a given explosive, these critical conditions are the projectile velocity, the projectile size and shape, and the projectile material properties. A lot of work has been done in the area of metal shaped charge jets and individual fragments impacting the HE. One major gap in understanding initiation phenomena is the effect of multiple fragment impact. This study shows that multiple fragments can lower the fragment size and the kinetic energy thresholds.

  2. Efficient exploration of chemical space by fragment-based screening.

    PubMed

    Hall, Richard J; Mortenson, Paul N; Murray, Christopher W

    2014-01-01

    Screening methods seek to sample a vast chemical space in order to identify starting points for further chemical optimisation. Fragment based drug discovery exploits the superior sampling of chemical space that can be achieved when the molecular weight is restricted. Here we show that commercially available fragment space is still relatively poorly sampled and argue for highly sensitive screening methods to allow the detection of smaller fragments. We analyse the properties of our fragment library versus the properties of X-ray hits derived from the library. We particularly consider properties related to the degree of planarity of the fragments.

  3. Native and exotic plants of fragments of sagebrush steppe produced by geomorphic processes versus land use

    USGS Publications Warehouse

    Huntly, N.; Bangert, R.; Hanser, S.E.

    2011-01-01

    Habitat fragmentation and invasion by exotic species are regarded as major threats to the biodiversity of many ecosystems. We surveyed the plant communities of two types of remnant sagebrush-steppe fragments from nearby areas on the Snake River Plain of southeastern Idaho, USA. One type resulted from land use (conversion to dryland agriculture; hereafter AG Islands) and the other from geomorphic processes (Holocene volcanism; hereafter kipukas). We assessed two predictions for the variation in native plant species richness of these fragments, using structural equation models (SEM). First, we predicted that the species richness of native plants would follow the MacArthur-Wilson (M-W) hypothesis of island biogeography, as often is expected for the communities of habitat fragments. Second, we predicted a negative relationship between native and exotic plants, as would be expected if exotic plants are decreasing the diversity of native plants. Finally, we assessed whether exotic species were more strongly associated with the fragments embedded in the agricultural landscape, as would be expected if agriculture had facilitated the introduction and naturalization of non-native species, and whether the communities of the two types of fragments were distinct. Species richness of native plants was not strongly correlated with M-W characteristics for either the AG Islands or the **kipukas. The AG Islands had more species and higher cover of exotics than the kipukas, and exotic plants were good predictors of native plant species richness. Our results support the hypothesis that proximity to agriculture can increase the diversity and abundance of exotic plants in native habitat. In combination with other information, the results also suggest that agriculture and exotic species have caused loss of native diversity and reorganization of the sagebrush-steppe plant community. ?? 2011 Springer Science+Business Media B.V.

  4. SCEDS: protein fragments for molecular replacement in Phaser

    SciTech Connect

    McCoy, Airlie J.; Nicholls, Robert A.; Schneider, Thomas R.

    2013-11-01

    Protein fragments suitable for use in molecular replacement can be generated by normal-mode perturbation, analysis of the difference distance matrix of the original versus normal-mode perturbed structures, and SCEDS, a score that measures the sphericity, continuity, equality and density of the resulting fragments. A method is described for generating protein fragments suitable for use as molecular-replacement (MR) template models. The template model for a protein suspected to undergo a conformational change is perturbed along combinations of low-frequency normal modes of the elastic network model. The unperturbed structure is then compared with each perturbed structure in turn and the structurally invariant regions are identified by analysing the difference distance matrix. These fragments are scored with SCEDS, which is a combined measure of the sphericity of the fragments, the continuity of the fragments with respect to the polypeptide chain, the equality in number of atoms in the fragments and the density of C{sup α} atoms in the triaxial ellipsoid of the fragment extents. The fragment divisions with the highest SCEDS are then used as separate template models for MR. Test cases show that where the protein contains fragments that undergo a change in juxtaposition between template model and target, SCEDS can identify fragments that lead to a lower R factor after ten cycles of all-atom refinement with REFMAC5 than the original template structure. The method has been implemented in the software Phaser.

  5. Research on the photoelectric measuring method of warhead fragment velocity

    NASA Astrophysics Data System (ADS)

    Liu, Ji; Yu, Lixia; Zhang, Bin; Liu, Xiaoyan

    2016-09-01

    The velocity of warhead fragment is the key criteria to determine its mutilation efficiency. But owing to the small size, larger quantity, irregular shape, high speed, arbitrary direction, large dispersion of warhead fragment and adverse environment, the test of fragment velocity parameter is very difficult. The paper designed an optoelectronic system to measure the average velocity of warhead fragments accurately. The apparatus included two parallel laser screens spaced apart at a known fixed distance for providing time measurement between start and stop signals. The large effective screen area was composed of laser source, retro-reflector and large area photo-diode. Whenever a moving fragment interrupted two optical screens, the system would generate a target signal. Due to partial obscuration of the incident energy and the poor test condition of the explosion, fragment target signal is easily disturbed. Therefore, fragments signal processing technology has become a key technology of the system. The noise of signal was reduced by employing wavelet decomposition and reconstruction. The time of fragment passing though the target was obtained by adopting peak detection algorithm. Based on the method of search peak in different width scale and waveform trend by using optima wavelet, the problem of rolling waveform was solved. Lots of fragments experiments of the different types of the warheads were conducted. Experimental results show that: warhead fragments capture rate of system is better than 98%, which can give velocity of each fragment in the density of less than 20 pieces per m2.

  6. DNA fragment sizing and sorting by laser-induced fluorescence

    SciTech Connect

    Jett, J.H.; Hammond, M.L.; Keller, R.A.; Marrone, B.L.; Martin, J.C.

    1992-12-31

    A method is provided for obtaining DNA fingerprints using high speed detection systems, such as flow cytometry to determine unique characteristics of DNA pieces from a selected sample. In one characterization the DNA piece is fragmented at preselected sites to produce a plurality of DNA fragments. The DNA piece or the resulting DNA fragments are treated with a dye effective to stain stoichiometrically the DNA fragments. The fluorescence from the dye in the stained fragments is then examined to generate an output functionally related to the number of nucleotides in each one of the DNA fragments. In one embodiment, the intensity of the fluorescence emissions from each fragment is directly proportional to the fragment length. Additional dyes can be bound to the DNA piece and DNA fragments to provide information additional to length information. Oligonucleotide specific dyes and/or hybridization probes can be bound to the DNA fragments to provide information on oligonucleotide distribution or probe hybridization to DNA fragments of different sizes.

  7. Target of rapamycin signaling mediates vacuolar fragmentation.

    PubMed

    Stauffer, Bobbiejane; Powers, Ted

    2017-02-01

    In eukaryotic cells, cellular homeostasis requires that different organelles respond to intracellular as well as environmental signals and modulate their behavior as conditions demand. Understanding the molecular mechanisms required for these changes remains an outstanding goal. One such organelle is the lysosome/vacuole, which undergoes alterations in size and number in response to environmental and physiological stimuli. Changes in the morphology of this organelle are mediated in part by the equilibrium between fusion and fission processes. While the fusion of the yeast vacuole has been studied intensively, the regulation of vacuolar fission remains poorly characterized by comparison. In recent years, a number of studies have incorporated genome-wide visual screens and high-throughput microscopy to identify factors required for vacuolar fission in response to diverse cellular insults, including hyperosmotic and endoplasmic reticulum stress. Available evidence now demonstrates that the rapamycin-sensitive TOR network, a master regulator of cell growth, is required for vacuolar fragmentation in response to stress. Importantly, many of the genes identified in these studies provide new insights into potential links between the vacuolar fission machinery and TOR signaling. Together these advances both extend our understanding of the regulation of vacuolar fragmentation in yeast as well as underscore the role of analogous events in mammalian cells.

  8. Assessing subglacial processes from diatom fragmentation patterns

    USGS Publications Warehouse

    Scherer, R.P.; Sjunneskog, C.M.; Iverson, N.R.; Hooyer, T.S.

    2004-01-01

    Reconstructing the size and glacial style of past ice-sheet advances requires interpreting complex glacial sedimentary facies. We use diatoms, a major component of Antarctic continental shelf deposits, to infer the physical conditions under which these deposits were emplaced. The degree of diatom fragmentation and the presence of diatoms of varying stratigraphic age in glacial sediments provide means to qualitatively gauge glacial mixing and transport. Here we report an experimentally calibrated index of diatom fragmentation that provides a simple but objective method of assessing the degree of subshearing imparted on marine glacial sedimentary deposits. By using a ring-shear device to subject diatomaceous sediment to stresses comparable to those beneath the Ross ice streams, we quantitatively assess patterns of diatom comminution resulting from compaction and from progressive shear stress. Elongate pennate diatoms are found to break disproportionately to discoid centric diatoms when subjected to shear stress; thus, a simple ratio of unbroken centric to pennate diatoms provides a reliable gauge of past shearing. Comparison of ring-shear results with a suite of previously analyzed sediments that represent a variety of glacial, glacial-marine, and hemipelagic settings of the Ross Sea and subglacial Ross Embayment demonstrates that this index can be employed for estimating relative subglacial stresses in this setting. ?? 2004 Geological Society of America.

  9. Fragment Screening of Human Aquaporin 1

    PubMed Central

    To, Janet; Torres, Jaume

    2016-01-01

    Aquaporins (AQPs) are membrane proteins that enable water transport across cellular plasma membranes in response to osmotic gradients. Phenotypic analyses have revealed important physiological roles for AQPs, and the potential for AQP water channel modulators in various disease states has been proposed. For example, AQP1 is overexpressed in tumor microvessels, and this correlates with higher metastatic potential and aggressiveness of the malignancy. Chemical modulators would help in identifying the precise contribution of water channel activity in these disease states. These inhibitors would also be important therapeutically, e.g., in anti-cancer treatment. This perceived importance contrasts with the lack of success of high-throughput screens (HTS) to identify effective and specific inhibitors of aquaporins. In this paper, we have screened a library of 1500 “fragments”, i.e., smaller than molecules used in HTS, against human aquaporin (hAQP1) using a thermal shift assay and surface plasmon resonance. Although these fragments may not inhibit their protein target, they bound to and stabilized hAQP1 (sub mM binding affinities (KD), with an temperature of aggregation shift ΔTagg of +4 to +50 °C) in a concentration-dependent fashion. Chemically expanded versions of these fragments should follow the determination of their binding site on the aquaporin surface. PMID:27023529

  10. Fragmentation functions beyond fixed order accuracy

    NASA Astrophysics Data System (ADS)

    Anderle, Daniele P.; Kaufmann, Tom; Stratmann, Marco; Ringer, Felix

    2017-03-01

    We give a detailed account of the phenomenology of all-order resummations of logarithmically enhanced contributions at small momentum fraction of the observed hadron in semi-inclusive electron-positron annihilation and the timelike scale evolution of parton-to-hadron fragmentation functions. The formalism to perform resummations in Mellin moment space is briefly reviewed, and all relevant expressions up to next-to-next-to-leading logarithmic order are derived, including their explicit dependence on the factorization and renormalization scales. We discuss the details pertinent to a proper numerical implementation of the resummed results comprising an iterative solution to the timelike evolution equations, the matching to known fixed-order expressions, and the choice of the contour in the Mellin inverse transformation. First extractions of parton-to-pion fragmentation functions from semi-inclusive annihilation data are performed at different logarithmic orders of the resummations in order to estimate their phenomenological relevance. To this end, we compare our results to corresponding fits up to fixed, next-to-next-to-leading order accuracy and study the residual dependence on the factorization scale in each case.

  11. Oxygen-containing fragments in natural products.

    PubMed

    Titarenko, Zoya; Vasilevich, Natalya; Zernov, Vladimir; Kirpichenok, Michael; Genis, Dmitry

    2013-02-01

    An analysis of the chemical environment of the oxygen atoms in the DNP database compared to the CMC and SCD databases was performed. Some structural clusters were identified which are predominant among the natural products and can be considered as distinctive features of NPs. Fifty-three oxygen-containing structural fragments that are distinctive for the DNP (distinctive set of fragments DSF) in comparison with the SCD have been identified. A new descriptor Mc was introduced for describing the ratio of atoms involved in the DSF to the total number of heavy atoms. A significant difference in the Mc values among the reference databases allowed the use of a specific cluster of the DSF as a tool for performing similarity searches for oxygen-containing NP molecules, or for evaluation or comparison of databases according to their NP-likeness. An example illustrating that the suggested approach could allow not only estimating the NP-likeness, but also serve as a tool for designing new NP-like compounds is provided. The suggested approach for NP-likeness evaluation moves away from the traditional ideas of scaffolds, cycles, linkers and substituents.

  12. Protein fragment reconstruction using various modeling techniques

    NASA Astrophysics Data System (ADS)

    Boniecki, Michal; Rotkiewicz, Piotr; Skolnick, Jeffrey; Kolinski, Andrzej

    2003-11-01

    Recently developed reduced models of proteins with knowledge-based force fields have been applied to a specific case of comparative modeling. From twenty high resolution protein structures of various structural classes, significant fragments of their chains have been removed and treated as unknown. The remaining portions of the structures were treated as fixed - i.e., as templates with an exact alignment. Then, the missed fragments were reconstructed using several modeling tools. These included three reduced types of protein models: the lattice SICHO (Side Chain Only) model, the lattice CABS (Cα + Cβ + Side group) model and an off-lattice model similar to the CABS model and called REFINER. The obtained reduced models were compared with more standard comparative modeling tools such as MODELLER and the SWISS-MODEL server. The reduced model results are qualitatively better for the higher resolution lattice models, clearly suggesting that these are now mature, competitive and complementary (in the range of sparse alignments) to the classical tools of comparative modeling. Comparison between the various reduced models strongly suggests that the essential ingredient for the sucessful and accurate modeling of protein structures is not the representation of conformational space (lattice, off-lattice, all-atom) but, rather, the specificity of the force fields used and, perhaps, the sampling techniques employed. These conclusions are encouraging for the future application of the fast reduced models in comparative modeling on a genomic scale.

  13. Ion Optics Simulation for Fragment Separator

    NASA Astrophysics Data System (ADS)

    Kawada, Yosuke; Nakamura, Takashi; Kubo, Toshiyuki; Takeda, Hiroyuki; Sumikama, Toshiyuki

    2009-10-01

    We have developed a Monte-Carlo simulation code for unstable-nuclear beam experiments using a fragment-separator. This code primarily aims at calculating beam traces in the fragment separator BigRIPS and ZeroDegree Spectrometer (ZDS) at RIBF(RIKEN RI-Beam Factory). This code uses externally given transfer-matrices of ion optics such as an output of COSY Infinity[1]. We have applied this code to recent campaign of experiments using ^48Ca at 345MeV/u as primary beam. In the experiments, two modes of ion optical settings , namely ``Standard'' and ``High Brho'' modes were used. The former is an ordinary used starndard setteing, which has a limit in the maximum rigidity (Bρ<9.2Tm). On the other hand, the ``High Brho'' setting has been developed for a secondary beam with higher rigidity, such as for very neutron rich nuclei ^22C (A/Z=3.67). In this talk, we compare properties of these two optics settings and evaluate beam traces, emittances, and transmissions.[4pt] [1] K. Makino, M. Berz Nucl. Instr. Meth. A 558 (2005)

  14. Optoelectronic System for Measuring Warhead Fragments Velocity

    NASA Astrophysics Data System (ADS)

    Liu, Ji; Zhao, Donge; Li, Yangjun; Zhou, Hanchang

    2011-02-01

    High-speed warhead fragments velocity measurement is one of the key technologies in investigating damage efficiency of warhead. We have designed and constructed a system to accurately determine the velocity of warhead fragments by measuring the time of flight between two parallel laser screens is presented. Each screen is formed by a laser source, a large photodetector and a retro-reflector. Optical output of the laser source is a collimated beam. The beam passes through cylindrical lens and the slit of photodetector reach to retro-reflector .The energy, reflected by retro-reflector; focus on the active area of photodetector. The system utilizes reflected ray by scotchlite retro-reflector as the start and end signal. And utilizes wideband circuit and data acquiring system to condition and sample signals. Experimental results show the system can measurement velocity are within the range from 20m/s to 2000m/s on target area of 1m2 and can perform satisfactorily with a wide range from 2000 lx to100,000lx. The measurement system also can be used to test velocity of projectile.

  15. Collapse and fragmentation of rotating, prolate clouds

    NASA Astrophysics Data System (ADS)

    Nelson, Richard P.

    1998-08-01

    We present the results of collapse calculations for uniformly rotating, prolate clouds performed using the numerical method: smoothed particle hydrodynamics (SPH). The clouds considered are isothermal, prolate spheroids with different axial ratios (a/b), and with different values of β, the ratio of the rotational to gravitational energy. Small density perturbations are added to the clouds, and different initial perturbation spectra are studied. All of the clouds considered are strongly unstable to gravitational contraction, and so collapse to form a spindle configuration. Such a linear structure is unstable to fragmentation, so that the clouds break up into a number of subcondensations. The long-term evolution of the system is then determined by the angular momentum possessed by these fragments. It is found that a number of the calculations performed result in the formation of orbitally stable binary systems, composed of two rotationally supported discs in orbit about their common centre of mass. Tidal interactions during closest approach, close three-body interactions and the continued accretion of material with high specific angular momentum are all found to increase the orbital separation during these calculations, ensuring that the systems do not merge at later times. The calculations are therefore relevant to the problem of binary star formation, though the systems produced tend to have large orbital separations and periods. One of the strong points of the models presented, however, is their ability to produce systems with a range of mass ratios and orbital eccentricities, without the explicit inclusion of biases in the initial conditions.

  16. Improvements to a model of projectile fragmentation

    NASA Astrophysics Data System (ADS)

    Mallik, S.; Chaudhuri, G.; Das Gupta, S.

    2011-11-01

    In a recent paper [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.83.044612 83, 044612 (2011)] we proposed a model for calculating cross sections of various reaction products which arise from disintegration of projectile-like fragments resulting from heavy-ion collisions at intermediate or higher energy. The model has three parts: (1) abrasion, (2) disintegration of the hot abraded projectile-like fragment (PLF) into nucleons and primary composites using a model of equilibrium statistical mechanics, and (3) possible evaporation of hot primary composites. It was assumed that the PLF resulting from abrasion has one temperature T. Data suggested that, while just one value of T seemed adequate for most cross-section calculations, a single value failed when dealing with very peripheral collisions. We have now introduced a variable T=T(b) where b is the impact parameter of the collision. We argue that there are data which not only show that T must be a function of b but, in addition, also point to an approximate value of T for a given b. We propose a very simple formula: T(b)=D0+D1[As(b)/A0] where As(b) is the mass of the abraded PLF and A0 is the mass of the projectile; D0 and D1 are constants. Using this model we compute cross sections for several collisions and compare with data.

  17. Fragmentation and constitutive response of tailored mesostructured aluminum compacts

    NASA Astrophysics Data System (ADS)

    Marquez, Andrew M.; Braithwaite, Christopher H.; Weihs, Timothy P.; Krywopusk, Nicholas M.; Gibbins, David J.; Vecchio, Kenneth S.; Meyers, Marc A.

    2016-04-01

    The fragmentation and constitutive response of aluminum-based compacts were examined under dynamic conditions using mesostructured powder compacts in which the interfaces between the powders (sizes of 40, 100, and 400 μm) were tailored during the swaging fabrication process. Fragmentation was induced in ring samples of this material through explosive loading and was examined through high speed photography, laser interferometry, and soft capture of fragments. Fragment velocities of around 100 m/s were recorded. The fragment mass distributions obtained correlated in general with the interfacial strength of the compacts as well as with the powder size. Experimental results are compared with fragmentation theories to characterize the behavior of reactive powders based on the material's mesostructure by introducing the fracture toughness of the compacts. The mean fragment size is calculated using a modified form of Mott's theory and successfully compared with experimental results.

  18. Predicting 'hot' and 'warm' spots for fragment binding.

    PubMed

    Rathi, Prakash Chandra; Ludlow, R Frederick; Hall, Richard John; Murray, Christopher W; Mortenson, Paul Neil; Verdonk, Marcel L

    2017-04-04

    Computational fragment mapping methods aim to predict hotspots on protein surfaces where small fragments will bind. Such methods are popular for druggability assessment as well as structure-based design. However, to date researchers developing or using such tools have had no clear way of assessing the performance of these methods. Here, we introduce the first diverse, high quality validation set for computational fragment mapping. The set contains 52 diverse examples of fragment binding 'hot' and 'warm' spots from the Protein Data Bank (PDB). Additionally, we describe PLImap, a novel protocol for fragment mapping based on the Protein-Ligand Interaction force field (PLIff). We evaluate PLImap against the new fragment mapping test set, and compare its performance to that of simple shape-based algorithms and fragment docking using GOLD. PLImap is made publicly available from https://bitbucket.org/AstexUK/pli.

  19. Participant and spectator scaling of spectator fragments in Au + Au and Cu + Cu collisions at sNN=19.6 and 22.4 GeV

    DOE PAGES

    Alver, B.; Back, B. B.; Baker, M. D.; ...

    2016-08-02

    Specmore » tator fragments resulting from relativistic heavy ion collisions, consisting of single protons and neutrons along with groups of stable nuclear fragments up to nitrogen (Z = 7), are measured in PHOBOS. These fragments are observed in Au+Au ( sNN=19.6 GeV) and Cu+Cu (22.4 GeV) collisions at high pseudorapidity (η). The dominant multiply-charged fragment is the tightly bound helium (α), with lithium, beryllium, and boron all clearly seen as a function of collision centrality and pseudorapidity. In this paper, we observe that in Cu+Cu collisions, it becomes much more favorable for the α fragments to be released than lithium. The yields of fragments approximately scale with the number of spectator nucleons, independent of the colliding ion. The shapes of the pseudorapidity distributions of fragments indicate that the average deflection of the fragments away from the beam direction increases for more central collisions. Finally, a detailed comparison of the shapes for α and lithium fragments indicates that the centrality dependence of the deflections favors a scaling with the number of participants in the collision.« less

  20. Construction of a 3D-shaped, natural product like fragment library by fragmentation and diversification of natural products.

    PubMed

    Prescher, Horst; Koch, Guido; Schuhmann, Tim; Ertl, Peter; Bussenault, Alex; Glick, Meir; Dix, Ina; Petersen, Frank; Lizos, Dimitrios E

    2017-02-01

    A fragment library consisting of 3D-shaped, natural product-like fragments was assembled. Library construction was mainly performed by natural product degradation and natural product diversification reactions and was complemented by the identification of 3D-shaped, natural product like fragments available from commercial sources. In addition, during the course of these studies, novel rearrangements were discovered for Massarigenin C and Cytochalasin E. The obtained fragment library has an excellent 3D-shape and natural product likeness, covering a novel, unexplored and underrepresented chemical space in fragment based drug discovery (FBDD).

  1. MaRaCluster: A Fragment Rarity Metric for Clustering Fragment Spectra in Shotgun Proteomics.

    PubMed

    The, Matthew; Käll, Lukas

    2016-03-04

    Shotgun proteomics experiments generate large amounts of fragment spectra as primary data, normally with high redundancy between and within experiments. Here, we have devised a clustering technique to identify fragment spectra stemming from the same species of peptide. This is a powerful alternative method to traditional search engines for analyzing spectra, specifically useful for larger scale mass spectrometry studies. As an aid in this process, we propose a distance calculation relying on the rarity of experimental fragment peaks, following the intuition that peaks shared by only a few spectra offer more evidence than peaks shared by a large number of spectra. We used this distance calculation and a complete-linkage scheme to cluster data from a recent large-scale mass spectrometry-based study. The clusterings produced by our method have up to 40% more identified peptides for their consensus spectra compared to those produced by the previous state-of-the-art method. We see that our method would advance the construction of spectral libraries as well as serve as a tool for mining large sets of fragment spectra. The source code and Ubuntu binary packages are available at https://github.com/statisticalbiotechnology/maracluster (under an Apache 2.0 license).

  2. Natural-product-derived fragments for fragment-based ligand discovery

    NASA Astrophysics Data System (ADS)

    Over, Björn; Wetzel, Stefan; Grütter, Christian; Nakai, Yasushi; Renner, Steffen; Rauh, Daniel; Waldmann, Herbert

    2013-01-01

    Fragment-based ligand and drug discovery predominantly employs sp2-rich compounds covering well-explored regions of chemical space. Despite the ease with which such fragments can be coupled, this focus on flat compounds is widely cited as contributing to the attrition rate of the drug discovery process. In contrast, biologically validated natural products are rich in stereogenic centres and populate areas of chemical space not occupied by average synthetic molecules. Here, we have analysed more than 180,000 natural product structures to arrive at 2,000 clusters of natural-product-derived fragments with high structural diversity, which resemble natural scaffolds and are rich in sp3-configured centres. The structures of the cluster centres differ from previously explored fragment libraries, but for nearly half of the clusters representative members are commercially available. We validate their usefulness for the discovery of novel ligand and inhibitor types by means of protein X-ray crystallography and the identification of novel stabilizers of inactive conformations of p38α MAP kinase and of inhibitors of several phosphatases.

  3. Determining fragmentation dynamics through a study of neutron multiplicity at the NSCL

    NASA Astrophysics Data System (ADS)

    Stephenson, Sharon; Christ, Peter; Mazza, Maria; MoNA Collaboration

    2017-01-01

    In nuclear fragmentation reactions the number of neutrons and the excitation energy of the final fragment are related to the excitation energies of prefragments, which are produced in the reaction target but not directly observed. The MoNA Collaboration designed and performed an experiment to measure the number of neutrons in coincidence with charged projectile fragments to determine the excitation mechanisms of specific prefragments. All prior MoNA experimental campaigns concentrated on neutrons emitted from discrete levels in near dripline nuclei and treated any evaporation neutrons as an underlying background. This experiment capitalizes on those evaporation neutrons, focusing on sodium, neon and fluorine reaction products. For the experiment a 32Mg secondary beam with energy 86 MeV/u was incident on a Be reaction target. This target is upstream from the Sweeper, a superconducting dipole steering magnet with a bending angle of 43° and a vertical gap that permits forward-focused neutrons to get to the MoNA, the Modular Neutron Array. The rigidity of the Sweeper was varied during this experiment to increase the detection range. Analysis of the neutron-neutron hit distribution in coincidence with each sodium, neon, or fluorine charged fragment will be presented. This work was supported in part by the National Science Foundation Award 1613429 and the Howard Hughes Medical Institute Award 52007540.

  4. Gastric Bezoar Treatment by Endoscopic Fragmentation in Combination with Pepsi-Cola® Administration

    PubMed Central

    Iwamuro, Masaya; Yunoki, Naoko; Tomoda, Jun; Nakamura, Kazuhiro; Okada, Hiroyuki; Yamamoto, Kazuhide

    2015-01-01

    Patient: Male, 86 Final Diagnosis: Gastric bezoar Symptoms: — Medication: Cola Clinical Procedure: Endoscopic fragmentation after gastric lavage with Pepsi-Cola Specialty: Gastroenterology and Hepatology Objective: Unusual setting of medical care Background: Although bezoar dissolution by Coca-Cola® has been described in case reports and case series, to the best of our knowledge, the usefulness of other cola products such as Pepsi-Cola® has never been reported in the English literature. Case Report: An 86-year-old Taiwanese man was diagnosed with a gastric bezoar. Endoscopic fragmentation with a polypectomy snare was attempted twice but failed to remove the bezoar. Subsequently, 500 mL of Pepsi NEX Zero® was administered daily for 4 days via nasogastric tube. The bezoar was softened and successfully fragmented by the polypectomy snare and needle-knife devices on the third attempt. Conclusions: This report presents the first case of a gastric bezoar successfully treated by endoscopic fragmentation in combination with Pepsi-Cola® administration, suggesting the possible utility of cola beverages in bezoar treatment, regardless of product brands. PMID:26164451

  5. Fractal Fragmentation triggered by meteor impact: The Ries Crater (Germany)

    NASA Astrophysics Data System (ADS)

    Paredes Marino, Joali; Perugini, Diego; Rossi, Stefano; Kueppers, Ulrich

    2015-04-01

    FRACTAL FRAGMENTATION TRIGGERED BY METEOR IMPACT: THE RIES CRATER (GERMANY) Joali Paredes (1), Stefano Rossi (1), Diego Perugini (1), Ulrich Kueppers (2) 1. Department of Physics and Geology, University of Perugia, Italy 2. Department of Earth and Environmental Sciences, University of Munich, Germany The Nördlinger Ries is a large circular depression in western Bavaria, Germany. The depression was caused by a meteor impact, which occurred about 14.3 million-14.5 million years ago. The original crater rim had an estimated diameter of 24 kilometers. Computer modeling of the impact event indicates that the impact or probably had diameters of about 1.5 kilometers and impacted the target area at an angle around 30 to 50 degrees from the surface in a west- southwest to east-northeast direction. The impact velocity is thought to have been about 20 km/s. The meteor impact generated extensive fragmentation of preexisting rocks. In addition, melting of these rocks also occurred. The impact melt was ejected at high speed provoking its extensive fragmentation. Quenched melt fragments are ubiquitous in the outcrops. Here we study melt fragment size distributions with the aim of understanding the style of melt fragmentation during ejection and to constrain the rheological properties of such melts. Digital images of suevite (i.e. the rock generated after deposition and diagenesis of ash and fragments produced by the meteor impact) were obtained using a high-resolution optical scanner. Successively, melt fragments were traced by image analysis and the images segmented in order to obtain binary images on which impact melt fragments are in black color, embedded on a white background. Hence, the size of fragments was determined by image analysis. Fractal fragmentation theory has been applied to fragment size distributions of melt fragments in the Ries crater. Results indicate that melt fragments follow fractal distributions indicating that fragmentation of melt generated by the

  6. CATABOLIC ORIGIN OF A BENCE JONES PROTEIN FRAGMENT

    PubMed Central

    Cioli, D.; Baglioni, C.

    1968-01-01

    Gel filtration analysis of the urinary proteins of some patients with myeloma has shown the presence of "fragments" of Bence Jones proteins which correspond to the variable half of these proteins. Experiments have been carried out to establish the origin of a "fragment" observed in a patient who excreted a large amount of this protein. Labeled homologous Bence Jones protein has been injected into this and other control patients. Excretion of labeled "fragment" has been observed in all. Analysis by peptide mapping and radio-autography of this labeled "fragment" isolated from the urine showed that the invariable half of the Bence Jones protein was not excreted; it seemed thus likely that the invariable half was metabolized to small peptides and free amino acids. A labeled Bence Jones protein which was excreted without any accompanying "fragment" was injected into the patient who excreted large amounts of "fragment." No excretion of labeled "fragment" was observed. It was thus concluded that the property of being degraded to "fragment" is characteristic of some "fragile" Bence Jones proteins and is not determined by the patient. Incubation with serum or urine of the "fragile" Bence Jones protein failed to produce any "fragment." "Fragments" of Bence Jones proteins are thus most likely formed during excretion of these proteins through the kidney and are products of the catabolism of Bence Jones proteins. PMID:5666962

  7. Spontaneous Motility of Actin Lamellar Fragments

    NASA Astrophysics Data System (ADS)

    Blanch-Mercader, C.; Casademunt, J.

    2013-02-01

    We show that actin lamellar fragments driven solely by polymerization forces at the bounding membrane are generically motile when the circular symmetry is spontaneously broken, with no need of molecular motors or global polarization. We base our study on a nonlinear analysis of a recently introduced minimal model [Callan-Jones et al., Phys. Rev. Lett. 100, 258106 (2008)PRLTAO0031-900710.1103/PhysRevLett.100.258106]. We prove the nonlinear instability of the center of mass and find an exact and simple relation between shape and center-of-mass velocity. A complex subcritical bifurcation scenario into traveling solutions is unfolded, where finite velocities appear through a nonadiabatic mechanism. Examples of traveling solutions and their stability are studied numerically.

  8. Isolator fragmentation and explosive initiation tests

    SciTech Connect

    Dickson, Peter; Rae, Philip John; Foley, Timothy J.; Novak, Alan M.; Armstrong, Christopher Lee; Baca, Eva V.; Gunderson, Jake Alfred

    2015-09-30

    Three tests were conducted to evaluate the effects of firing an isolator in proximity to a barrier or explosive charge. The tests with explosive were conducted without barrier, on the basis that since any barrier will reduce the shock transmitted to the explosive, bare explosive represents the worst-case from an inadvertent initiation perspective. No reaction was observed. The shock caused by the impact of a representative plastic material on both bare and cased PBX9501 is calculated in the worst-case, 1-D limit, and the known shock response of the HE is used to estimate minimum run-to-detonation lengths. The estimates demonstrate that even 1-D impacts would not be of concern and that, accordingly, the divergent shocks due to isolator fragment impact are of no concern as initiating stimuli.

  9. Communication: Embedded fragment stochastic density functional theory

    SciTech Connect

    Neuhauser, Daniel; Baer, Roi; Rabani, Eran

    2014-07-28

    We develop a method in which the electronic densities of small fragments determined by Kohn-Sham density functional theory (DFT) are embedded using stochastic DFT to form the exact density of the full system. The new method preserves the scaling and the simplicity of the stochastic DFT but cures the slow convergence that occurs when weakly coupled subsystems are treated. It overcomes the spurious charge fluctuations that impair the applications of the original stochastic DFT approach. We demonstrate the new approach on a fullerene dimer and on clusters of water molecules and show that the density of states and the total energy can be accurately described with a relatively small number of stochastic orbitals.

  10. Isolator fragmentation and explosive initiation tests

    SciTech Connect

    Dickson, Peter; Rae, Philip John; Foley, Timothy J.; Novak, Alan M.; Armstrong, Christopher Lee; Baca, Eva V.; Gunderson, Jake Alfred

    2016-09-19

    Three tests were conducted to evaluate the effects of firing an isolator in proximity to a barrier or explosive charge. The tests with explosive were conducted without a barrier, on the basis that since any barrier will reduce the shock transmitted to the explosive, bare explosive represents the worst-case from an inadvertent initiation perspective. No reaction was observed. The shock caused by the impact of a representative plastic material on both bare and cased PBX 9501 is calculated in the worst-case, 1-D limit, and the known shock response of the HE is used to estimate minimum run-to-detonation lengths. The estimates demonstrate that even 1-D impacts would not be of concern and that, accordingly, the divergent shocks due to isolator fragment impact are of no concern as initiating stimuli.

  11. Forest fragmentation and its effects on birds

    USGS Publications Warehouse

    Robbins, C.S.; Johnson, James E.

    1988-01-01

    Fragmentation of forest land, whether by suburban development, highways, transmission lines, or poorly planned cutting regimes, seriously affects reproduction by the large numbers of obligate forest interior birds. Many of our warblers, vireos, thrushes, tanagers, and flycatchers are highly migratory insectivorous birds that spend more than half the year in the neotropics, but migrate north to the United States and Canada to rear their young. These tropical visitors are especially vulnerable to predation and cowbird parasitism and are unable to maintain their populations within 100-200 m of forest edge. Habitats for these declining species can be provided by managing forest lands in large blocks so as to maintain at all times extensive contiguous areas of successional stages as well as of mature forest. Avoiding scattered small cuts will also help by reducing edge, road construction, and other disturbance.

  12. Thermally activated fragmentation of a homopolymer chain

    NASA Astrophysics Data System (ADS)

    Fugmann, Simon; Sokolov, Igor M.

    2011-03-01

    We consider the thermally activated fragmentation of a homopolymer chain, which can exhibit strongly non-Markovian behavior on the timescale of interest. In our model the dynamics of the intact chain is a Rouse one until a bond breaks and bond breakdown is considered as a first passage problem over a barrier to an absorbing boundary. Using the framework of the Wilemski-Fixman approximation we calculate activation times of individual bonds for free and grafted polymer chains. We show that these times crucially depend on the length of the chain and the location of the bond yielding a minimum at the free chain ends. Going beyond the Wilemski-Fixman approximation we show that a generalized form of the renewal equation for barrier crossings serves to improve the quantitative agreement between numerical simulations and analytical predictions. The authors thankfully acknowledge financial support by DFG within the SFB 555 research collaboration program.

  13. Spatio-temporal Genetic Structure of a Tropical Bee Species Suggests High Dispersal Over a Fragmented Landscape.

    PubMed

    Suni, Sevan S; Bronstein, Judith L; Brosi, Berry J

    2014-03-01

    Habitat destruction threatens biodiversity by reducing the amount of available resources and connectivity among geographic areas. For organisms living in fragmented habitats, population persistence may depend on dispersal, which maintains gene flow among fragments and can prevent inbreeding within them. It is centrally important to understand patterns of dispersal for bees living in fragmented areas given the importance of pollination systems and recently documented declines in bee populations. We used population and landscape genetic techniques to characterize patterns of dispersal over a large fragmented area in southern Costa Rica for the orchid bee species Euglossa championi. First, we estimated levels of genetic differentiation among forest fragments as φpt, an analog to the traditional summary statistic Fst, as well as two statistics that may more adequately represent levels of differentiation, G'st and Dest . Second, we used a Bayesian approach to determine the number and composition of genetic groups in our sample. Third we investigated how genetic differentiation changes with distance. Fourth, we determined the extent to which deforested areas restrict dispersal. Finally, we estimated the extent to which there were temporal differences in allele frequencies within the same forest fragments. Within years we found low levels of differentiation even over 80 km, and no effect of land use type on level of genetic differentiation. However, we found significant genetic differentiation between years. Taken together our results suggest that there are high levels of gene flow over this geographic area, and that individuals show low site fidelity over time.

  14. Spatio-temporal Genetic Structure of a Tropical Bee Species Suggests High Dispersal Over a Fragmented Landscape

    PubMed Central

    Suni, Sevan S.; Bronstein, Judith L.; Brosi, Berry J.

    2014-01-01

    Habitat destruction threatens biodiversity by reducing the amount of available resources and connectivity among geographic areas. For organisms living in fragmented habitats, population persistence may depend on dispersal, which maintains gene flow among fragments and can prevent inbreeding within them. It is centrally important to understand patterns of dispersal for bees living in fragmented areas given the importance of pollination systems and recently documented declines in bee populations. We used population and landscape genetic techniques to characterize patterns of dispersal over a large fragmented area in southern Costa Rica for the orchid bee species Euglossa championi. First, we estimated levels of genetic differentiation among forest fragments as φpt, an analog to the traditional summary statistic Fst, as well as two statistics that may more adequately represent levels of differentiation, G’st and Dest. Second, we used a Bayesian approach to determine the number and composition of genetic groups in our sample. Third we investigated how genetic differentiation changes with distance. Fourth, we determined the extent to which deforested areas restrict dispersal. Finally, we estimated the extent to which there were temporal differences in allele frequencies within the same forest fragments. Within years we found low levels of differentiation even over 80 km, and no effect of land use type on level of genetic differentiation. However, we found significant genetic differentiation between years. Taken together our results suggest that there are high levels of gene flow over this geographic area, and that individuals show low site fidelity over time. PMID:24659825

  15. Effects of Neutron Emission on Fragment Mass and Kinetic Energy Distribution from Thermal Neutron-Induced Fission of {sup 235}U

    SciTech Connect

    Montoya, M.; Rojas, J.; Saetone, E.

    2007-10-26

    The mass and kinetic energy distribution of nuclear fragments from thermal neutron-induced fission of {sup 235}U(n{sub th},f) have been studied using a Monte-Carlo simulation. Besides reproducing the pronounced broadening in the standard deviation of the kinetic energy at the final fragment mass number around m = 109, our simulation also produces a second broadening around m = 125. These results are in good agreement with the experimental data obtained by Belhafaf et al. and other results on yield of mass. We conclude that the obtained results are a consequence of the characteristics of the neutron emission, the sharp variation in the primary fragment kinetic energy and mass yield curves. We show that because neutron emission is hazardous to make any conclusion on primary quantities distribution of fragments from experimental results on final quantities distributions.

  16. Final Technical Report

    SciTech Connect

    Schuur, Edward; Luo, Yiqi

    2016-12-01

    This final grant report is a continuation of the final grant report submitted for DE-SC0006982 as the Principle Investigator (Schuur) relocated from the University of Florida to Northern Arizona University. This report summarizes the original project goals, as well as includes new project activities that were completed in the final period of the project.

  17. Fragmented local governance and water resource management outcomes.

    PubMed

    Kim, Jae Hong; Keane, Timothy D; Bernard, Eric A

    2015-03-01

    Fragmented jurisdictions and decision making structures can result in destructive competition and/or a lack of systematic cooperation that can hamper effective resource management and environmental planning, although the value of local autonomy and stakeholder participations should not be underestimated. This study empirically examines if political fragmentation in local governance is a significant barrier to successful resource management. To test this hypothesis, the authors quantify the degree of political fragmentation at two different geographical scales - 1) site-level: 12-digit watersheds and 2) regional: metropolitan statistical areas or equivalent regions - and analyze how water resource management outcomes vary with the level of political fragmentation using nationwide land cover and stream gauge information in the U.S. Regression analysis shows water quality declines (or slower quality improvements), measured in terms of total suspended solids, are associated with both site-level and regional political fragmentation indicators, suggesting that political fragmentation can make resource management more challenging.

  18. Sizing of single fluorescently stained DNA fragments by scanning microscopy

    PubMed Central

    Laib, Stephan; Rankl, Michael; Ruckstuhl, Thomas; Seeger, Stefan

    2003-01-01

    We describe an approach to determine DNA fragment sizes based on the fluorescence detection of single adsorbed fragments on specifically coated glass cover slips. The brightness of single fragments stained with the DNA bisintercalation dye TOTO-1 is determined by scanning the surface with a confocal microscope. The brightness of adsorbed fragments is found to be proportional to the fragment length. The method needs only minute amount of DNA, beyond inexpensive and easily available surface coatings, like poly-l-lysine, 3-aminoproyltriethoxysilane and polyornithine, are utilizable. We performed DNA-sizing of fragment lengths between 2 and 14 kb. Further, we resolved the size distribution before and after an enzymatic restriction digest. At this a separation of buffers or enzymes was unnecessary. DNA sizes were determined within an uncertainty of 7–14%. The proposed method is straightforward and can be applied to standardized microtiter plates. PMID:14602931

  19. Soft x-ray ionization induced fragmentation of glycine

    NASA Astrophysics Data System (ADS)

    Itälä, E.; Kooser, K.; Rachlew, E.; Huels, M. A.; Kukk, E.

    2014-06-01

    X-ray absorption commonly involves dissociative core ionization producing not only momentum correlated charged fragments but also low- and high-energy electrons capable of inducing damage in living tissue. This gives a natural motivation for studying the core ionization induced fragmentation processes in biologically important molecules such as amino acids. Here the fragmentation of amino acid glycine following carbon 1s core ionization has been studied. Using photoelectron-photoion-photoion coincidence technique, a detailed analysis on fragmentation of the sample molecule into pairs of momentum correlated cations has been carried out. The main characteristics of core ionization induced fragmentation of glycine were found to be the rupture of the C-Cα bond and the presence of the CNH_2^+ fragment.

  20. Soft x-ray ionization induced fragmentation of glycine.

    PubMed

    Itälä, E; Kooser, K; Rachlew, E; Huels, M A; Kukk, E

    2014-06-21

    X-ray absorption commonly involves dissociative core ionization producing not only momentum correlated charged fragments but also low- and high-energy electrons capable of inducing damage in living tissue. This gives a natural motivation for studying the core ionization induced fragmentation processes in biologically important molecules such as amino acids. Here the fragmentation of amino acid glycine following carbon 1s core ionization has been studied. Using photoelectron-photoion-photoion coincidence technique, a detailed analysis on fragmentation of the sample molecule into pairs of momentum correlated cations has been carried out. The main characteristics of core ionization induced fragmentation of glycine were found to be the rupture of the C-Cα bond and the presence of the CNH(2)(+) fragment.

  1. Popping Balloons: A Case Study of Dynamical Fragmentation

    NASA Astrophysics Data System (ADS)

    Moulinet, Sébastien; Adda-Bedia, Mokhtar

    2015-10-01

    Understanding the physics of fragmentation is important in a wide range of industrial and geophysical applications. Fragmentation processes involve large strain rates and short time scales that take place during crack nucleation and propagation. Using rubber membranes, we develop an experimental analysis that enables us to track the fragmentation process in situ in both time and space. We find that bursting a highly stretched membrane yields a treelike fragmentation network that originates at a single seed crack, followed by successive crack tip-splitting events. We show that a dynamic instability drives this branching mechanism. Fragmentation occurs when the crack tip speed attains a critical velocity for which tip splitting becomes the sole available mechanism of releasing the stored elastic energy. Given the general character of the fragmentation processes, this framework should be applicable to other crack networks in brittle materials.

  2. Protein hydrogen exchange studied by the fragment separation method.

    PubMed

    Englander, J J; Rogero, J R; Englander, S W

    1985-05-15

    The potential of hydrogen-exchange studies for providing detailed information on protein structure and structural dynamics has not yet been realized, largely because of the continuing inability to correlate measured exchange behavior with the parts of a protein that generate that behavior. J. Rosa and F. M. Richards (1979, J. Mol. Biol. 133, 399-416) pioneered a promising approach to this problem in which tritium label at exchangeable proton sites can be located by fragmenting the protein, separating the fragments, and measuring the label carried by each fragment. However, severe losses of tritium label during the fragment separation steps have so far rendered the results ambiguous. This paper describes methods that minimize losses of tritium label during the fragment separation steps and correct for losses that do occur so that the label can be unambiguously located and even quantified. Steps that promote adequate fragment isolation are also described.

  3. Soft x-ray ionization induced fragmentation of glycine

    SciTech Connect

    Itälä, E.; Kooser, K.; Rachlew, E.; Huels, M. A.; Kukk, E.

    2014-06-21

    X-ray absorption commonly involves dissociative core ionization producing not only momentum correlated charged fragments but also low- and high-energy electrons capable of inducing damage in living tissue. This gives a natural motivation for studying the core ionization induced fragmentation processes in biologically important molecules such as amino acids. Here the fragmentation of amino acid glycine following carbon 1s core ionization has been studied. Using photoelectron-photoion-photoion coincidence technique, a detailed analysis on fragmentation of the sample molecule into pairs of momentum correlated cations has been carried out. The main characteristics of core ionization induced fragmentation of glycine were found to be the rupture of the C–C{sub α} bond and the presence of the CNH{sub 2}{sup +} fragment.

  4. Fragment size does not matter when you are well connected: effects of fragmentation on fitness of coexisting gypsophiles.

    PubMed

    Matesanz, S; Gómez-Fernández, A; Alcocer, I; Escudero, A

    2015-09-01

    Most habitat fragmentation studies have focused on the effects of population size on reproductive success of single species, but studies assessing the effects of both fragment size and connectivity, and their interaction, on several coexisting species are rare. In this study, we selected 20 fragments along two continuous gradients of size and degree of isolation in a gypsum landscape in central Spain. In each fragment, we selected 15 individuals of each of three dominant gypsophiles (Centaurea hyssopifolia, Lepidium subulatum and Helianthemum squamatum, 300 plants per species, 900 plants in total) and measured several reproductive traits: inflorescence number, fruit set, seed set and seed mass. We hypothesised that plant fitness would be lower on small and isolated fragments due to an interaction between fragment size and connectivity, and that response patterns would be species-specific. Overall, fragment size had very little effect on reproductive traits compared to that of connectivity. We observed a positive effect of fragment connectivity on C. hyssopifolia fitness, mediated by the increased seed predation in plants from isolated fragments, resulting in fewer viable seeds per capitulum and lower seed set. Furthermore, seed mass was lower in plants from isolated fragments for both C. hyssopifolia and L. subulatum. In contrast, few reproductive traits of H. squamatum were affected by habitat fragmentation. We discuss the implications of species-specific responses to habitat fragmentation for the dynamics and conservation of gypsum plant communities. Our results highlight the complex interplay among plants and their mutualistic and antagonistic visitors, and reinforce the often-neglected role of habitat connectivity as a key component of the fragmentation process.

  5. Critical Features of Fragment Libraries for Protein Structure Prediction.

    PubMed

    Trevizani, Raphael; Custódio, Fábio Lima; Dos Santos, Karina Baptista; Dardenne, Laurent Emmanuel

    2017-01-01

    The use of fragment libraries is a popular approach among protein structure prediction methods and has proven to substantially improve the quality of predicted structures. However, some vital aspects of a fragment library that influence the accuracy of modeling a native structure remain to be determined. This study investigates some of these features. Particularly, we analyze the effect of using secondary structure prediction guiding fragments selection, different fragments sizes and the effect of structural clustering of fragments within libraries. To have a clearer view of how these factors affect protein structure prediction, we isolated the process of model building by fragment assembly from some common limitations associated with prediction methods, e.g., imprecise energy functions and optimization algorithms, by employing an exact structure-based objective function under a greedy algorithm. Our results indicate that shorter fragments reproduce the native structure more accurately than the longer. Libraries composed of multiple fragment lengths generate even better structures, where longer fragments show to be more useful at the beginning of the simulations. The use of many different fragment sizes shows little improvement when compared to predictions carried out with libraries that comprise only three different fragment sizes. Models obtained from libraries built using only sequence similarity are, on average, better than those built with a secondary structure prediction bias. However, we found that the use of secondary structure prediction allows greater reduction of the search space, which is invaluable for prediction methods. The results of this study can be critical guidelines for the use of fragment libraries in protein structure prediction.

  6. Critical Features of Fragment Libraries for Protein Structure Prediction

    PubMed Central

    dos Santos, Karina Baptista

    2017-01-01

    The use of fragment libraries is a popular approach among protein structure prediction methods and has proven to substantially improve the quality of predicted structures. However, some vital aspects of a fragment library that influence the accuracy of modeling a native structure remain to be determined. This study investigates some of these features. Particularly, we analyze the effect of using secondary structure prediction guiding fragments selection, different fragments sizes and the effect of structural clustering of fragments within libraries. To have a clearer view of how these factors affect protein structure prediction, we isolated the process of model building by fragment assembly from some common limitations associated with prediction methods, e.g., imprecise energy functions and optimization algorithms, by employing an exact structure-based objective function under a greedy algorithm. Our results indicate that shorter fragments reproduce the native structure more accurately than the longer. Libraries composed of multiple fragment lengths generate even better structures, where longer fragments show to be more useful at the beginning of the simulations. The use of many different fragment sizes shows little improvement when compared to predictions carried out with libraries that comprise only three different fragment sizes. Models obtained from libraries built using only sequence similarity are, on average, better than those built with a secondary structure prediction bias. However, we found that the use of secondary structure prediction allows greater reduction of the search space, which is invaluable for prediction methods. The results of this study can be critical guidelines for the use of fragment libraries in protein structure prediction. PMID:28085928

  7. Exponential and power-law mass distributions in brittle fragmentation

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Linna, R. P.; Timonen, J.; Møller, Peder Friis; Oddershede, Lene

    2004-08-01

    Generic arguments, a minimal numerical model, and fragmentation experiments with gypsum disk are used to investigate the fragment-size distribution that results from dynamic brittle fragmentation. Fragmentation is initiated by random nucleation of cracks due to material inhomogeneities, and its dynamics are pictured as a process of propagating cracks that are unstable against side-branch formation. The initial cracks and side branches both merge mutually to form fragments. The side branches have a finite penetration depth as a result of inherent damping. Generic arguments imply that close to the minimum strain (or impact energy) required for fragmentation, the number of fragments of size s scales as s-(2D-1)/Df1(-(2/λ)Ds)+f2(-s0-1(λ+s1/D)D) , where D is the Euclidean dimension of the space, λ is the penetration depth, and f1 and f2 can be approximated by exponential functions. Simulation results and experiments can both be described by this theoretical fragment-size distribution. The typical largest fragment size s0 was found to diverge at the minimum strain required for fragmentation as it is inversely related to the density of initially formed cracks. Our results also indicate that scaling of s0 close to this divergence depends on, e.g., loading conditions, and thus is not universal. At the same time, the density of fragment surface vanishes as L-1 , L being the linear dimension of the brittle solid. The results obtained provide an explanation as to why the fragment-size distributions found in nature can have two components, an exponential as well as a power-law component, with varying relative weights.

  8. Quark fragmentation in e/sup +/e/sup -/ collisions

    SciTech Connect

    Oddone, P.

    1984-12-01

    This brief review of new results in quark and gluon fragmentation observed in e/sup +/e/sup -/ collisions concentrates mostly on PEP results and, within PEP, mostly on TPC results. The new PETRA results have been reported at this conference by M. Davier. It is restricted to results on light quark fragmentation since the results on heavy quark fragmentation have been reported by J. Chapman.

  9. Fragment-based screening of the bromodomain of ATAD2

    SciTech Connect

    Harner, Mary J.; Chauder, Brian A.; Phan, Jason; Fesik, Stephen W.

    2014-10-14

    Cellular and genetic evidence suggest that inhibition of ATAD2 could be a useful strategy to treat several types of cancer. To discover small-molecule inhibitors of the bromodomain of ATAD2, we used a fragment-based approach. As a result, fragment hits were identified using NMR spectroscopy, and ATAD2 was crystallized with three of the hits identified in the fragment screen.

  10. Charge Prediction of Lipid Fragments in Mass Spectrometry

    SciTech Connect

    Schrom, Brian T.; Kangas, Lars J.; Ginovska, Bojana; Metz, Thomas O.; Miller, John H.

    2011-12-18

    An artificial neural network is developed for predicting which fragment is charged and which fragment is neutral for lipid fragment pairs produced from a liquid chromatography tandem mass spectrometry simulation process. This charge predictor is integrated into software developed at PNNL for in silico spectra generation and identification of metabolites known as Met ISIS. To test the effect of including charge prediction in Met ISIS, 46 lipids are used which show a reduction in false positive identifications when the charge predictor is utilized.

  11. Fragmentation of mercury compounds under ultraviolet light irradiation

    NASA Astrophysics Data System (ADS)

    Kokkonen, E.; Löytynoja, T.; Hautala, L.; Jänkälä, K.; Huttula, M.

    2015-08-01

    Ultraviolet light induced photofragmentation of mercury compounds is studied experimentally with electron energy resolved photoelectron-photoion coincidence techniques and theoretically with computational quantum chemical methods. A high resolution photoelectron spectrum using synchrotron radiation is presented. Fragmentation of the molecule is studied subsequent to ionization to the atomic-mercury-like d orbitals. State dependent fragmentation behaviour is presented and specific reactions for dissociation pathways are given. The fragmentation is found to differ distinctly in similar orbitals of different mercury compounds.

  12. Fragmentation of weak non-ablating objects during entry

    SciTech Connect

    Canavan, G.H.

    1997-04-01

    Fragmentation of objects during entry can be treated with developed models of breakup, fragment cascade, separation, and deceleration. The results reduce to those derived earlier for strong objects. Model predictions are in agreement with the key features of numerical simulations. Model equations can be inverted analytically to infer object size, entry speed, and strength from measurements of peak power and altitude and fragmentation altitude or time.

  13. Gravitational fragmentation - A comparison with W49A

    NASA Technical Reports Server (NTRS)

    Keto, Eric R.; Lattanzio, John C.; Monaghan, Joe J.

    1991-01-01

    The process of gravitational fragmentation of molecular clouds is investigated through a comparison of numerical and observational results. The expected millimeter wave molecular line emission from a model fragmenting cloud generated by a numerical hydrodynamic simulation is calculated and compared with observations of HCO(+) from the star-forming region W49A. This investigation suggests that the rotating ring of H II regions, the necklace in W49A, may have formed in the gravitational fragmentation of a flattened rotating molecular cloud.

  14. Fragment-based lead discovery: challenges and opportunities

    NASA Astrophysics Data System (ADS)

    Sun, Chaohong; Petros, Andrew M.; Hajduk, Philip J.

    2011-07-01

    Fragment-based lead discovery has undergone remarkable changes over the last 15 years. During this time, the pharmaceutical industry has changed dramatically as well, and continued evolution of the industry is assured. These changes present many challenges but also several opportunities for executing fragment-based drug design. This article will explore some of the more significant changes in the industry and how they may affect future discovery efforts related to fragment-based initiatives.

  15. Fragmentation of mercury compounds under ultraviolet light irradiation

    SciTech Connect

    Kokkonen, E.; Hautala, L.; Jänkälä, K.; Huttula, M.; Löytynoja, T.

    2015-08-21

    Ultraviolet light induced photofragmentation of mercury compounds is studied experimentally with electron energy resolved photoelectron-photoion coincidence techniques and theoretically with computational quantum chemical methods. A high resolution photoelectron spectrum using synchrotron radiation is presented. Fragmentation of the molecule is studied subsequent to ionization to the atomic-mercury-like d orbitals. State dependent fragmentation behaviour is presented and specific reactions for dissociation pathways are given. The fragmentation is found to differ distinctly in similar orbitals of different mercury compounds.

  16. The Effective Fragment Molecular Orbital Method for Fragments Connected by Covalent Bonds

    PubMed Central

    Steinmann, Casper; Fedorov, Dmitri G.; Jensen, Jan H.

    2012-01-01

    We extend the effective fragment molecular orbital method (EFMO) into treating fragments connected by covalent bonds. The accuracy of EFMO is compared to FMO and conventional ab initio electronic structure methods for polypeptides including proteins. Errors in energy for RHF and MP2 are within 2 kcal/mol for neutral polypeptides and 6 kcal/mol for charged polypeptides similar to FMO but obtained two to five times faster. For proteins, the errors are also within a few kcal/mol of the FMO results. We developed both the RHF and MP2 gradient for EFMO. Compared to ab initio, the EFMO optimized structures had an RMSD of 0.40 and 0.44 Å for RHF and MP2, respectively. PMID:22844433

  17. Fragmentation of ions in a low pressure linear ion trap.

    PubMed

    Collings, Bruce A

    2007-08-01

    The efficiency of in-trap fragmentation in a low-pressure linear ion trap (LIT), using dipolar excitation, is dependent upon the choice of both the excitation q and the drive frequency of the quadrupole. In the work presented here, fragmentation efficiencies have been measured as a function of excitation q for drive frequencies of 816 kHz and 1.228 MHz. The experiments were carried out by fragmenting reserpine (609.23-->448.20 Th and 397.21-->365.19 Th transitions) and caffeine (195-->138 Th and 138-->110 Th transitions). The data showed that the onset of efficient fragmentation occurred at a lower Mathieu q for the LIT operated at 1.228 MHz when compared with the LIT operated at 816 kHz. A comparison of the fragmentation efficiency curves as a function of pseudo-potential well depth showed that the onset of fragmentation is independent of the drive frequency. In addition, a comparison of the fragmentation efficiency curves showed that all four of the precursor ions fragmented within a range of four V of pseudo-potential well depth. The choice of an appropriate excitation q can then be determined based upon a minimum pseudo-potential well depth, quadrupole field radius, drive frequency, and the mass of interest. Fragmentation efficiencies were also found to be significantly greater when using the higher drive frequency.

  18. [Understanding mitochondrial genome fragmentation in parasitic lice (Insecta: Phthiraptera)].

    PubMed

    Dong, Wen-Ge; Guo, Xian-Guo; Jin, Dao-Chao; Xue, Shi-Peng; Qin, Feng; Simon, Song; Stephen, C Barker; Renfu, Shao

    2013-07-01

    Lice are obligate ectoparasites of mammals and birds. Extensive fragmentation of mitochondrial genomes has been found in some louse species in the families Pediculidae, Pthiridae, Philopteridae and Trichodectidae. For example, the mt genomes of human body louse (Pediculus humanus), head louse (Pediculus capitis), and public louse (Pthirus pubis) have 20, 20 and 14 mini-chromosomes, respectively. These mini-chromosomes might be the results of deletion and recombination of mt genes. The factors and mechanisms of mitochondrial genome fragmentation are currently unknown. The fragmentation might be the results of evolutionary selection or random genetic drift or it is probably related to the lack of mtSSB (mitochondrial single-strand DNA binding protein). Understanding the fragmentation of mitochondrial genomes is of significance for understanding the origin and evolution of mitochondria. This paper reviews the recent advances in the studies of mito-chondrial genome fragmentation in lice, including the phenomena of mitochondrial genome fragmentation, characteristics of fragmented mitochondrial genomes, and some factors and mechanisms possibly leading to the mitochondrial genome fragmentation of lice. Perspectives for future studies on fragmented mt genomes are also discussed.

  19. Life history strategy influences parasite responses to habitat fragmentation.

    PubMed

    Froeschke, Götz; van der Mescht, Luther; McGeoch, Melodie; Matthee, Sonja

    2013-12-01

    Anthropogenic habitat use is a major threat to biodiversity and is known to increase the abundance of generalist host species such as rodents, which are regarded as potential disease carriers. Parasites have an intimate relationship with their host and the surrounding environment and it is expected that habitat fragmentation will affect parasite infestation levels. We investigated the effect of habitat fragmentation on the ecto- and endoparasitic burdens of a broad niche small mammal, Rhabdomys pumilio, in the Western Cape Province, South Africa. Our aim was to look at the effects of fragmentation on different parasite species with diverse life history characteristics and to determine whether general patterns can be found. Sampling took place within pristine lowland (Fynbos/Renosterveld) areas and at fragmented sites surrounded and isolated by agricultural activities. All arthropod ectoparasites and available gastrointestinal endoparasites were identified. We used conditional autoregressive models to investigate the effects of habitat fragmentation on parasite species richness and abundance of all recovered parasites. Host density and body size were larger in the fragments. Combined ecto- as well as combined endoparasite taxa showed higher parasite species richness in fragmented sites. Parasite abundance was generally higher in the case of R. pumilio individuals in fragmented habitats but it appears that parasites that are more permanently associated with the host's body and those that are host-specific show the opposite trend. Parasite life history is an important factor that needs to be considered when predicting the effects of habitat fragmentation on parasite and pathogen transmission.

  20. Gluon Fragmentation Functions in the Nambu-Jona-Lasinio Model

    NASA Astrophysics Data System (ADS)

    Yang, Dong-Jing; Li, Hsiang-nan

    We derive gluon fragmentation functions in the Nambu-Jona-Lasinio (NJL) model by approximating a gluon as a fictitious color-octet quark-anti-quark (qbar{q}) pair. Gluon elementary fragmentation functions are derived from the quark and anti-quark elementary fragmentation functions for emitting specific mesons in the NJL model under the requirement that the qbar{q} pair maintains in the flavor-singlet state after meson emission. An iteration method and an inverse matrix method based on the gluon elementary fragmentation functions then yield the gluon fragmentation functions at the model scale. It is found that the resultant gluon fragmentation functions are stable with respect to variation of relevant model parameters, especially after QCD evolution to a higher scale is implemented. We show that the inclusion of the gluon fragmentation functions into the theoretical predictions from only the quark fragmentation functions greatly improve the agreement with the SLD data for the pion and kaon productions in e+e- annihilation. Our proposal provides a plausible construct for the gluon fragmentation functions, which are supposed to be null in the NJL model.

  1. {J}/{ψ} production via fragmentation at HERA

    NASA Astrophysics Data System (ADS)

    Godbole, R. M.; Roy, D. P.; Sridhar, K.

    1996-02-01

    We compute the contributions to large- p T{J}/{ψ} production at DHEA coming from fragmentation of gluons and charm quarks. We find that the charm quark fragmentation contribution dominates over the direct production of {J}/{ψ} via photongluon fusion at large- p T, while the gluon fragmentation is negligibly small over the whole range of pT. An experimental study of pT distributions of {J}/{ψ} at HERA will providea direct probe of the charm quark fragmentation functions.

  2. Experimental fragmentation of crystal- and vesicle-bearing silicic melts

    NASA Astrophysics Data System (ADS)

    Martel, Caroline; Dingwell, Donald; Spieler, Oliver; Pichavant, Michel; Wilke, Max

    2001-07-01

    We experimentally investigate the effect of crystals on the fragmentation behavior of a three-phase (melt+gas+crystals) system under rapid decompression. Starting materials are cylinders of hydrated haplogranite melts containing alumina crystals that are placed at 6-30 MPa and 600-800°C in a fragmentation bomb for foaming. Subsequently, these bubble- and crystal-bearing melts are rapidly decompressed (within <1 s) to room pressure and temperature and the fragmented particles are recovered for analysis. We investigated the influence of the crystal size ( 70-350 µm in diameter), the crystal content (20-95 vol.%), and the magnitude of the decompression (6-30 MPa) on the fragment sizes. Crystals down to 70 µm in diameter have a strong influence on the fragment size distribution by defining fragments made of single crystals. Increasing the crystal content in the starting material leads to an increase of the average size of the fragments. Increasing the magnitude of the decompression generates finer fragments. Fragmentation threshold or dynamic tensile strength ranges from 10 MPa for crystal-poor samples up to >30 MPa for phenocryst- and microlite-bearing samples.

  3. Single spin asymmetry in forward p A collisions. II. Fragmentation contribution

    NASA Astrophysics Data System (ADS)

    Hatta, Yoshitaka; Xiao, Bo-Wen; Yoshida, Shinsuke; Yuan, Feng

    2017-01-01

    We compute the twist-three fragmentation contribution to the transverse single spin asymmetry (SSA) in light hadron production p↑p →h X and p↑A →h X including the gluon saturation effect in the unpolarized nucleon/nucleus. Together with the results in our previous paper, this completes the full evaluation of the SSA in this process in the "hybrid" formalism. We argue that the dependence of SSAs on the atomic mass number in the forward region can elucidate the relative importance of the soft gluon pole contribution from the twist-three quark-gluon-quark correlation in the polarized nucleon and the twist-three fragmentation contribution from the final state hadron.

  4. The effects of axial length on the fracture and fragmentation of expanding rings

    NASA Astrophysics Data System (ADS)

    Jones, D. R.; Eakins, D. E.; Savinykh, A. S.; Razorenov, S. V.

    2012-08-01

    Rings of Ti-6Al-4V with aspect ratios (wall thickness:axial length) of 1 : 1, 1 : 2 and 1 : 4 have been expanded to failure at radial strain rates ɛr ˜ 1 × 104 s-1 using 4340 (EN24T) steel and Cu-ETP cylindrical drivers containing a column of RDX. Expansion velocity was measured using VISAR enabling calculation of the stress-strain history of the ring alongside fragment recovery with up to 98% original ring mass recovered. Using the recovered samples average fragment length and mass and final strain have been measured along with analysis of the fracture sites to determine the active failure mechanisms. Perfect rings (aspect ratio 1 : 1) were found to undergo necking before failure, whereas the longer rings failed though ductile tensile cracking at 45∘ to the radius. This data is then compared with finite element analysis results.

  5. Identification of μs-isomers produced in the fragmentation of a 112Sn beam

    NASA Astrophysics Data System (ADS)

    Grzywacz, R.; Anne, R.; Auger, G.; Bazin, D.; Borcea, C.; Borrel, V.; Corre, J. M.; Dörfler, T.; Fomichov, A.; Gaelens, M.; Guillemaud-Mueller, D.; Hue, R.; Huyse, M.; Janas, Z.; Keller, H.; Lewitowicz, M.; Lukyanov, S.; Mueller, A. C.; Penionzhkevich, Yu.; Pfützner, M.; Pougheon, F.; Rykaczewski, K.; Saint-Laurent, M. G.; Schmidt, K.; Schmidt-Ott, W.-D.; Sorlin, O.; Szerypo, J.; Tarasov, O.; Wauters, J.; Żylicz, J.

    1995-02-01

    Decays of over forty short-lived ( T {1}/{2} from ≈ 50 ns to 70 μs) isomeric states including a new isomer 66mAs produced in the fragmentation of a 112Sn beam (58 A·MeV, 63 A·MeV) on a natNi target were observed at the final focus of the LISE3 spectrometer at GANIL. Their detection, based on the slow (≈ 10 μs) time correlation of identified ions with the characteristic γ-radiation, represents a novel method to search for new isomers and can be used for unambiguous isotope identification for projectile fragment separator experiments. Isomeric yields and isomer-to-total production ratios were determined.

  6. Reorganization of microtubules in endosperm cells and cell fragments of the higher plant Haemanthus in vivo

    PubMed Central

    1986-01-01

    The reorganization of the microtubular meshwork was studied in intact Haemanthus endosperm cells and cell fragments (cytoplasts). This higher plant tissue is devoid of a known microtubule organizating organelle. Observations on living cells were correlated with microtubule arrangements visualized with the immunogold method. In small fragments, reorganization did not proceed. In medium and large sized fragments, microtubular converging centers formed first. Then these converging centers reorganized into either closed bushy microtubular spiral or chromosome-free cytoplasmic spindles/phragmoplasts. Therefore, the final shape of organized microtubular structures, including spindle shaped, was determined by the initial size of the cell fragments and could be achieved without chromosomes or centrioles. Converging centers elongate due to the formation of additional structures resembling microtubular fir trees. These structures were observed at the pole of the microtubular converging center in anucleate fragments, accessory phragmoplasts in nucleated cells, and in the polar region of the mitotic spindle during anaphase. Therefore, during anaphase pronounced assembly of new microtubules occurs at the polar region of acentriolar spindles. Moreover, statistical analysis demonstrated that during the first two-thirds of anaphase, when chromosomes move with an approximately constant speed, kinetochore fibers shorten, while the length of the kinetochore fiber complex remains constant due to the simultaneous elongation of their integral parts (microtubular fir trees). The half-spindle shortens only during the last one-third of anaphase. These data contradict the presently prevailing view that chromosome-to-pole movements in acentriolar spindles of higher plants are concurrent with the shortening of the half-spindle, the self- reorganizing property of higher plant microtubules (tubulin) in vivo. It may be specific for cells without centrosomes and may be superimposed also on other

  7. Devising for a distal radius fracture fixation focus on the intra-articular volar dislocated fragment

    PubMed Central

    Sugiyama, Yoichi; Naito, Kiyohito; Obata, Hiroyuki; Kinoshita, Mayuko; Aritomi, Kentaro; Kaneko, Kazuo; Obayashi, Osamu

    2016-01-01

    Introduction Distal radius fracture (DRF) accompanied by intra-articular volar displaced fragment is difficult to reduce. This volar fragment remains when treated with a simple buttress effect alone, and V-shaped deformity may remain on the articular surface. We attempted to improve dorsal rotational deviation of volar fragment by osteosynthesis applying the condylar stabilizing technique. We report the surgical procedure and results. Materials and methods The subjects were 10 cases of DRF accompanied by intra-articular volar displaced fragments surgically treated (mean age: 69 years old). The fracture type based on the AO classification was B3 in 1 case, C1 in 4, C2 in 2, and C3 in 3 cases. All cases were treated with a volar locking plate. Reduction was applied utilizing the angle stability of the volar locking plate, similarly to the condylar stabilizing technique. On the final follow-up, we evaluated clinical and radiologic evaluation. To evaluate V-shaped valley deformity of the articular surface, the depth of the lunate fossa of the radius was measured using computed tomography (CT). Results The duration of postoperative follow-up was 11 (6–24) months. Mayo wrist score was 93 (Excellent in 10 cases). No general complication associated with a volar locking plate was noted in any case. Volar tilt on radiography were 11° (4–14). The depth of the lunate fossa on CT was 3.9 ± 0.7 mm in the patients. Conclusion This procedure may be useful for osteosynthesis of distal radius fracture accompanied by intra-articular volar displaced fragments. PMID:27144008

  8. The Power to Detect Recent Fragmentation Events Using Genetic Differentiation Methods

    PubMed Central

    Lloyd, Michael W.; Campbell, Lesley; Neel, Maile C.

    2013-01-01

    Habitat loss and fragmentation are imminent threats to biological diversity worldwide and thus are fundamental issues in conservation biology. Increased isolation alone has been implicated as a driver of negative impacts in populations associated with fragmented landscapes. Genetic monitoring and the use of measures of genetic divergence have been proposed as means to detect changes in landscape connectivity. Our goal was to evaluate the sensitivity of Wright’s Fst, Hedrick’ G’st, Sherwin’s MI, and Jost’s D to recent fragmentation events across a range of population sizes and sampling regimes. We constructed an individual-based model, which used a factorial design to compare effects of varying population size, presence or absence of overlapping generations, and presence or absence of population sub-structuring. Increases in population size, overlapping generations, and population sub-structuring each reduced Fst, G’st, MI, and D. The signal of fragmentation was detected within two generations for all metrics. However, the magnitude of the change in each was small in all cases, and when Ne was >100 individuals it was extremely small. Multi-generational sampling and population estimates are required to differentiate the signal of background divergence from changes in Fst, G’st, MI, and D associated with fragmentation. Finally, the window during which rapid change in Fst, G’st, MI, and D between generations occurs can be small, and if missed would lead to inconclusive results. For these reasons, use of Fst, G’st, MI, or D for detecting and monitoring changes in connectivity is likely to prove difficult in real-world scenarios. We advocate use of genetic monitoring only in conjunction with estimates of actual movement among patches such that one could compare current movement with the genetic signature of past movement to determine there has been a change. PMID:23704965

  9. Classical imaging and digital imaging spectrophotometric techniques in cullets (glass fragments) sorting

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe

    2004-10-01

    Cullets optical sorting represents one of the oldest selection procedure applied to the field of solid waste recycling. From the original sorting strategies, mainly addressed to separate non-transparent elements (ceramics, stones, metal particles, etc.) from transparent ones (glass fragments), the attention was addressed to define procedures and actions able to separate the cullets according to their color characteristics and, more recently, to recognize transparent ceramic glass from glass. Cullets sorting is currently realized adopting, as detecting architecture, laser beam technology based devices. The sorting logic is mainly analogical. An "on-off" logic is applied. Detection is, in fact, based on the evaluation of the "characteristics" of the energy (transparent or non-transparent fragment) and the spectra (fragment color attributes) received by a detector after that cullets were crossed by a suitable laser beam light. Such an approach presents some limits related with the technology utilized and the material characteristics. The technological limits are linked to the physical dimension and the mechanical arrangement of the optics carrying out and in the signals, and with the pneumatic architectures enabling the modification of cullets trajectory to realize sorting, according to their characteristics (color and transmittance). Furthermore such devices are practically "blind" in the recognition of ceramic glasses, whose presence in the final selected material to melt, damage the full recycled glass fusion compromising the quality of the final product. In the following it will be described the work developed, and the results achieved, in order to design a full integrated classical digital imaging and spectrophotometric based approach addressed to develop suitable sorting strategies able to perform, at industrial recycling scale, the distinction of cullets both in terms of color and material typologies, that is "real glass" from "ceramic glass" fragments.

  10. Does the fracture fragment at the anterior column in thoracolumbar burst fractures get enough attention?

    PubMed Central

    Deqing, Luo; Kejian, Lian; Teng, Li; Weitao, Zou; Dasheng, Lin

    2017-01-01

    Abstract Prospective cohort study. To evaluate whether failure of the fracture fragment at the anterior column reduction in thoracolumbar fracture has an influence on the final radiologic and clinical outcomes. Cervical teardrop fracture has caused wide concern in spinal surgery field. Although similar fracture fragment at the anterior column was also observed in thoracolumbar burst fractures, the conception of teardrop fracture in thoracolumbar fractures was rarely mentioned in the literature, let alone a study. Fifty patients who suffered from thoracolumbar burst fractures with a fracture fragment at the anterior column were prospectively analyzed. Twenty-seven patients in whom the fragments were reduced by posterior surgery, verified by postoperative X-ray or CT, were included in the reduced group, and 23 patients were included in the nonreduced group. Radiologic and clinical outcomes of both groups were compared after over 2 years follow-up. There was no significant difference regarding to Cobb angle, Oswestry Disability Index (ODI) score, and disc grade between the 2 groups preoperatively. At final follow-up, the mean angle of kyphosis was 13.91° ± 3.47° in the nonreduced group and 8.42° ± 2.07° in the reduced groups (P < 0.01). All fractures consolidated in the reduced group, but the nonreduced group revealed 3 cases with nonunion. Besides, the average Pfirrmann grade of degenerative disc adjacent to the fractured vertebral was 2.87 ± 1.18 in the nonreduced group, higher than 1.81 ± 0.62 in the reduced group (P < 0.01). The ODI score in the nonreduced group was 0.54 ± 0.13 and 0.36 ± 0.12 in the reduced group (P < 0.01). In the present study, failure reduction of the fracture fragment at the anterior column could result in poor radiologic and clinical outcomes of the thoracolumbar burst fractures treated with posterior surgery. Therefore, we recommend the surgeon should pay more attention to reducing the fracture

  11. Aerodynamic characteristics and respiratory deposition of fungal fragments

    NASA Astrophysics Data System (ADS)

    Cho, Seung-Hyun; Seo, Sung-Chul; Schmechel, Detlef; Grinshpun, Sergey A.; Reponen, Tiina

    The purpose of this study was to investigate the aerodynamic characteristics of fungal fragments and to estimate their respiratory deposition. Fragments and spores of three different fungal species ( Aspergillus versicolor, Penicillium melinii, and Stachybotrys chartarum) were aerosolized by the fungal spore source strength tester (FSSST). An electrical low-pressure impactor (ELPI) measured the size distribution in real-time and collected the aerosolized fungal particles simultaneously onto 12 impactor stages in the size range of 0.3-10 μm utilizing water-soluble ZEF-X10 coating of the impaction stages to prevent spore bounce. For S. chartarum, the average concentration of released fungal fragments was 380 particles cm -3, which was about 514 times higher than that of spores. A. versicolor was found to release comparable amount of spores and fragments. Microscopic analysis confirmed that S. chartarum and A. versicolor did not show any significant spore bounce, whereas the size distribution of P. melinii fragments was masked by spore bounce. Respiratory deposition was calculated using a computer-based model, LUDEP 2.07, for an adult male and a 3-month-old infant utilizing the database on the concentration and size distribution of S. chartarum and A. versicolor aerosols measured by the ELPI. Total deposition fractions for fragments and spores were 27-46% and 84-95%, respectively, showing slightly higher values in an infant than in an adult. For S. chartarum, fragments demonstrated 230-250 fold higher respiratory deposition than spores, while the number of deposited fragments and spores of A. versicolor were comparable. It was revealed that the deposition ratio (the number of deposited fragments divided by that of deposited spores) in the lower airways for an infant was 4-5 times higher than that for an adult. As fungal fragments have been shown to contain mycotoxins and antigens, further exposure assessment should include the measurement of fungal fragments for

  12. Ecological study of social fragmentation, poverty, and suicide

    PubMed Central

    Whitley, Elise; Gunnell, David; Dorling, Daniel; Smith, George Davey

    1999-01-01

    Objectives To investigate the association between suicide and area based measures of deprivation and social fragmentation. Design Ecological study. Setting 633 parliamentary constituencies of Great Britain as defined in 1991. Main outcome measures Age and sex specific mortality rates for suicide and all other causes for 1981-92. Results Mortality from suicide and all other causes increased with increasing Townsend deprivation score, social fragmentation score, and abstention from voting in all age and sex groups. Suicide mortality was most strongly related to social fragmentation, whereas deaths from other causes were more closely associated with Townsend score. Constituencies with absolute increases in social fragmentation and Townsend scores between 1981 and 1991 tended to have greater increases in suicide rates over the same period. The relation between change in social fragmentation and suicide was largely independent of Townsend score, whereas the association with Townsend score was generally reduced after adjustment for social fragmentation. Conclusions Suicide rates are more strongly associated with measures of social fragmentation than with poverty at a constituency level. Key messagesPlace of residence may affect health, and mortality from most common diseases tends to be higher in areas characterised by low socioeconomic positionResearch dating back over 100 years suggests that social fragmentation may influencesuicideIn the 1980s and 1990s, parliamentary constituencies with high levels of social fragmentation had high rates of suicide, independent of deprivationConstituencies with the greatest increases in social fragmentation between 1981 and 1991 also had the greatest increases in suicide rates over the same periodAny targeting of suicide prevention may be more effective if aimed at socially fragmented rather than deprived areas PMID:10521194

  13. Protein minimization by random fragmentation and selection.

    PubMed

    Rudgers, G W; Palzkill, T

    2001-07-01

    Protein-protein interactions are involved in most biological processes and are important targets for drug design. Over the past decade, there has been increased interest in the design of small molecules that mimic functional epitopes of protein inhibitors. BLIP is a 165 amino acid protein that is a potent inhibitor of TEM-1 beta-lactamase (K(i) = 0.1 nM). To aid in the development of new inhibitors of beta-lactamase, the gene encoding BLIP was randomly fragmented and DNA segments encoding peptides that retain the ability to bind TEM-1 beta-lactamase were isolated using phage display. The selected peptides revealed a common, overlapping region that includes BLIP residues C30-D49. Synthesis and binding analysis of the C30-D49 peptide indicate that this peptide inhibits TEM-1 beta-lactamase. Therefore, a peptide derivative of BLIP that has been reduced in size by 88% compared with wild-type BLIP retains the ability to bind and inhibit beta-lactamase.

  14. Haplotype assembly from aligned weighted SNP fragments.

    PubMed

    Zhao, Yu-Ying; Wu, Ling-Yun; Zhang, Ji-Hong; Wang, Rui-Sheng; Zhang, Xiang-Sun

    2005-08-01

    Given an assembled genome of a diploid organism the haplotype assembly problem can be formulated as retrieval of a pair of haplotypes from a set of aligned weighted SNP fragments. Known computational formulations (models) of this problem are minimum letter flips (MLF) and the weighted minimum letter flips (WMLF; Greenberg et al. (INFORMS J. Comput. 2004, 14, 211-213)). In this paper we show that the general WMLF model is NP-hard even for the gapless case. However the algorithmic solutions for selected variants of WMFL can exist and we propose a heuristic algorithm based on a dynamic clustering technique. We also introduce a new formulation of the haplotype assembly problem that we call COMPLETE WMLF (CWMLF). This model and algorithms for its implementation take into account a simultaneous presence of multiple kinds of data errors. Extensive computational experiments indicate that the algorithmic implementations of the CWMLF model achieve higher accuracy of haplotype reconstruction than the WMLF-based algorithms, which in turn appear to be more accurate than those based on MLF.

  15. Electron Impact Fragmentation of CH4 Molecules

    NASA Astrophysics Data System (ADS)

    Suzuki, Ryoji; Oguri, Kazuhiro; Makochekanwa, Casten; Kitajima, Masashi; Tanaka, Hiroshi

    2004-09-01

    Absolute electron-molecule impact dissociation cross sections are of interest in many fields of physics and chemistry, plasma etching of microelectronic devices and other industrial applications. However, experimental data on these cross sections is scarce mainly because of the difficulties involved in measuring neutral fragments [1]. Electron impact dissociation of CH4 molecules into the CH3 radicals have been investigated over the energy range 15.0 to 37.0 eV. The experimental procedure involves a dual-electron-beam in a two-stage collision system in conjunction with a quadrupole mass spectrometer (QMS). This is similar to the threshold-ionization mass spectrometry method [2]. Significant differences, in magnitude up to four times at 100 eV, exist between the only available absolute measurements by Sugai et al. [2] and Moore et al. [3]. Our data shows very close agreement with the Moore et al. data, which which show reasonable consistency with the available CH4 total dissociation data by Winters [3]. [1] L. S. Polak and D. I. Slovetsky, Int. J. Rad. Phys. Chem. 8, 257 (1976). [2] H. Sugai, H. Toyoda and T. Nakano, Jpn. J. Appl. Phys. 30, 2912 (1991). [3] H. F. Winters, J. Chem. Phys. 63, 3462 (1975).

  16. Optical selection and collection of DNA fragments

    DOEpatents

    Roslaniec, Mary C.; Martin, John C.; Jett, James H.; Cram, L. Scott

    1998-01-01

    Optical selection and collection of DNA fragments. The present invention includes the optical selection and collection of large (>.mu.g) quantities of clonable, chromosome-specific DNA from a sample of chromosomes. Chromosome selection is based on selective, irreversible photoinactivation of unwanted chromosomal DNA. Although more general procedures may be envisioned, the invention is demonstrated by processing chromosomes in a conventional flow cytometry apparatus, but where no droplets are generated. All chromosomes in the sample are first stained with at least one fluorescent analytic dye and bonded to a photochemically active species which can render chromosomal DNA unclonable if activated. After passing through analyzing light beam(s), unwanted chromosomes are irradiated using light which is absorbed by the photochemically active species, thereby causing photoinactivation. As desired chromosomes pass this photoinactivation point, the inactivating light source is deflected by an optical modulator; hence, desired chromosomes are not photoinactivated and remain clonable. The selection and photoinactivation processes take place on a microsecond timescale. By eliminating droplet formation, chromosome selection rates 50 times greater than those possible with conventional chromosome sorters may be obtained. Thus, usable quantities of clonable DNA from any source thereof may be collected.

  17. Recent results on jet fragmentation from CDF

    SciTech Connect

    A. Safonov

    2002-06-04

    In this paper, the most recent results on jet fragmentation obtained at the Collider Detector at Fermilab Tevatron are presented. The multiplicity and momentum distribution of charged particles inside jets in dijet events are compared to the predictions of the Modified Leading Log Approximation complemented with the hypothesis of Local Parton-Hadron Duality. Values for the two parameters of the model are extracted, the cut-off scale Q{sub eff} = 230 {+-} 40 MeV and the rate of parton-to-hadron conversions K{sub LPHD}{sup charged} = 0.56 {+-} 0.10. A fit of the data for the ratio of multiplicities in gluon and quark jets r, where r is treated as a free parameter, results in r = 1.9 {+-} 0.5. Also, we compare the charged particle multiplicities in dijet and {gamma}-jet events. The comparison allows for an extraction of a model-independent ratio of multiplicities in gluon and quark jets. We report r = N{sub g}/N{sub q} = 1.61 {+-} 0.11(stat) {+-} 0.28(syst) for E{sub jet} = 40 GeV.

  18. Proline Conformation in a Functional Tau Fragment.

    PubMed

    Ahuja, Puneet; Cantrelle, François-Xavier; Huvent, Isabelle; Hanoulle, Xavier; Lopez, Juan; Smet, Caroline; Wieruszeski, Jean-Michel; Landrieu, Isabelle; Lippens, G

    2016-01-16

    The conformational state of distinct prolines can determine the folding of a protein but equally other biological processes when coupled to a conformation-sensitive secondary reaction. For the neuronal tau protein, the importance of proline conformation is underscored by its interaction with different prolyl cis/trans isomerases. The proline conformation would gain even further importance after phosphorylation of the preceding residue by various proline-directed kinases. A number of molecular diseases including Alzheimer's disease and traumatic brain injury were thereby recently qualified as "cistauosis", as they would imply a cis conformation for the pThr231-Pro232 prolyl bond. We here investigate by NMR spectroscopy the conformation of all prolines in a functional Tau fragment, Tau[208-324]. Although we can detect and identify some minor conformers in the cis form, we show that all prolines are for over 90% in the trans conformation. Phosphorylation by CDK2/CycA3, which notably leads to complete modification of the Thr231 residue, does not change this conclusion. Our data hence disagree with the notion that specific prolyl bonds in tau would adopt preferentially the cis conformation.

  19. Fragment Prioritization on a Large Mutagenicity Dataset.

    PubMed

    Floris, Matteo; Raitano, Giuseppa; Medda, Ricardo; Benfenati, Emilio

    2016-12-29

    The identification of structural alerts is one of the simplest tools used for the identification of potentially toxic chemical compounds. Structural alerts have served as an aid to quickly identify chemicals that should be either prioritized for testing or for elimination from further consideration and use. In the recent years, the availability of larger datasets, often growing in the context of collaborative efforts and competitions, created the raw material needed to identify new and more accurate structural alerts. This work applied a method to efficiently mine large toxicological dataset for structural alert showing a strong statistical association with mutagenicity. In details, we processed a large Ames mutagenicity dataset comprising 14,015 unique molecules obtained by joining different data sources. After correction for multiple testing, we were able to assign a probability value to each fragment. A total of 51 rules were identified, with p-value < 0.05. Using the same method, we also confirmed the statistical significance of several mutagenicity rules already present and largely recognized in the literature. In addition, we have extended the application of our method by predicting the mutagenicity of an external data set.

  20. Vet Centers. Final rule.

    PubMed

    2016-03-02

    The Department of Veterans Affairs (VA) adopts as final an interim final rule that amends its medical regulation that governs Vet Center services. The National Defense Authorization Act for Fiscal Year 2013 (the 2013 Act) requires Vet Centers to provide readjustment counseling services to broader groups of veterans, members of the Armed Forces, including a member of a reserve component of the Armed Forces, and family members of such veterans and members. This final rule adopts as final the regulatory criteria to conform to the 2013 Act, to include new and revised definitions.

  1. Relative stereochemical determination and synthesis of the C17-C25 δ-lactone fragment of hemicalide.

    PubMed

    Fleury, Etienne; Sorin, Geoffroy; Prost, Elise; Pancrazi, Ange; Sautel, François; Massiot, Georges; Lannou, Marie-Isabelle; Ardisson, Janick

    2013-02-01

    Hemicalide is a novel marine metabolite polyketide distinguished by a unique mechanism of action. Because of insufficient quantities of purified material, this natural product has evaded complete stereochemical assignments. Recently, we have determined the relative stereochemistry of the C8-C13 hexad by synthesizing the C1-C13 fragment. Presently, we report the assignment of the C17-C25 δ-lactone fragment. NMR analysis of authentic hemicalide along with a computational conformation study allowed us to reduce the number of putative relative isomers from 16 to 4. Concise syntheses of the four candidate diastereomers were achieved using a common strategy based on a Dias aldehyde allylation reaction, an intramolecular Horner-Wadsworth-Emmons olefination, and a dihydroxylation reaction. Finally, thorough NMR comparisons enabled us to deduce the relative stereochemistry of the C1-C17 fragment with high certainty.

  2. Comparison of calculated and experimental results of fragmenting cylinder experiments

    SciTech Connect

    WILSON,L.T.; REEDAL,D.R.; KIPP,MARLIN E.; MARTINEZ,REINA R.; GRADY,D.E.

    2000-06-02

    The Grady-Kipp fragmentation model provides a physically based method for determining the fracture and breakup of materials under high loading rates. Recently, this model has been implemented into the CTH Shock Physics Code and has been used to simulate several published experiments. Materials studied in this paper are AerMet 100 steel and a 90% tungsten alloy. The experimental geometry consists of a right circular cylinder filled with an explosive main charge that is initiated at its center. The sudden expansion of the resulting detonation products causes fracture of the cylinder. Strain rates seen in the cylinder are on the order of 10{sup 4} s{sup {minus}1}. The average fragment sizes calculated with the Grady-Kipp fragmentation model successfully replicate the mean fragment size obtained from the experimental fragment distribution. When Poisson statistics are applied to the calculated local average fragment sizes, good correlation is also observed with the shape of the experimental cumulative fragment distribution. The experimental fragmentation results, CTH numerical simulations, and correlation of these numerical results with the experimental data are described.

  3. Generation of competitor DNA fragments for quantitative PCR.

    PubMed

    Uberla, K; Platzer, C; Diamantstein, T; Blankenstein, T

    1991-11-01

    A convenient and generally applicable method for the generation of competitor DNA fragments for quantitative PCR is described. Using mouse-specific primers, fragments are amplified from DNA of an evolutionarily distantly related species under low-stringency annealing conditions. Because these artificially created fragments contain the mouse primer specific ends, they can be used for the quantification of the mouse DNA amplified by these primers. Competitor DNA fragments that differ in size from the corresponding mouse DNA are selected to distinguish both fragments visually by gel electrophoresis. Competitor DNA fragments were generated for mouse beta-actin, interleukin-1, and tumor necrosis factor (TNF). Co-amplification of beta-actin cDNA for adjustment of equal amounts of input cDNA and subsequently TNF cDNA from lipopolysaccharide (LPS)-activated and nonactivated spleen cells with serial dilutions of the respective competitor DNA fragments allowed a semiquantitative comparison of the ratio of TNF mRNA present in both cDNA samples. Under certain conditions, the competitor DNA fragments can be used to determine the approximate molar concentration of a mRNA.

  4. Chromosomal fragments transmitted through three generations in Oncopeltus (Hemiptera).

    PubMed

    LaChance, L E; Degrugillier, M

    1969-10-10

    Chromosomal fragments and translocations induced by x-rays in the sperm of adult milkweed bugs, Oncopeltus fasciatus (Dallas), were detected in the meiotic cells of F(1), F(2), and F(3), males and caused high levels of sterility in lintreated progeny. The persistence of these fragments through numerous generations of cells confirmed the holokinetic nature of the milkweed bug chromosomes.

  5. Impact and explosion crater ejecta, fragment size, and velocity

    NASA Technical Reports Server (NTRS)

    Okeefe, J. D.; Ahrens, T. J.

    1983-01-01

    A model was developed for the mass distribution of fragments that are ejected at a given velocity for impact and explosion craters. The model is semi-empirical in nature and is derived from (1) numerical calculations of cratering and the resultant mass versus ejection velocity, (2) observed ejecta blanket particle size distributions, (3) an empirical relationship between maximum ejecta fragment size and crater diameter and an assumption on the functional form for the distribution of fragements ejected at a given velocity. This model implies that for planetary impacts into competent rock, the distribution of fragments ejected at a given velocity are nearly monodisperse, e.g., 20% of the mass of the ejecta at a given velocity contain fragments having a mass less than 0.1 times a mass of the largest fragment moving at that velocity. Using this model, the largest fragment that can be ejected from asteroids, the moon, Mars, and Earth is calculated as a function of crater diameter. In addition, the internal energy of ejecta versus ejecta velocity is found. The internal energy of fragments having velocities exceeding the escape velocity of the moon will exceed the energy required for incipient melting for solid silicates and thus, constrains the maximum ejected solid fragment size.

  6. Building a chemical space based on fragment descriptors.

    PubMed

    Baskin, Igor; Varnek, Alexandre

    2008-09-01

    This article reviews the application of fragment descriptors at different stages of virtual screening: filtering, similarity search, and direct activity assessment using QSAR/QSPR models. Several case studies are considered. It is demonstrated that the power of fragment descriptors stems from their universality, very high computational efficiency, simplicity of interpretation and versatility.

  7. Gas-Phase Fragmentation Analysis of Nitro-Fatty Acids

    PubMed Central

    Bonacci, Gustavo; Asciutto, Eliana K.; Woodcock, Steven R.; Salvatore, Sonia R.; Freeman, Bruce A.; Schopfer, Francisco J.

    2012-01-01

    Nitro-fatty acids are electrophilic signaling mediators formed in increased amounts during inflammation by nitric oxide and nitrite-dependent redox reactions. A more rigorous characterization of endogenously-generated species requires additional understanding of their gas-phase induced fragmentation. Thus, collision induced dissociation (CID) of nitroalkane and nitroalkene groups in fatty acids were studied in the negative ion mode to provide mass spectrometric tools for their structural characterization. Fragmentation of nitroalkanes occurred mainly through loss of the NO2− anion or neutral loss of HNO2. The CID of nitroalkenes proceeds via a more complex cyclization, followed by fragmentation to nitrile and aldehyde products. Gas-phase fragmentation of nitroalkene functional groups with additional γ or δ unsaturation occurred through a multiple step cyclization reaction process, leading to 5 and 6 member ring heterocyclic products and carbon chain fragmentation. Cyclization products were not obtained during nitroalkane fragmentation, highlighting the role of double bond π electrons during NO2− rearrangements, stabilization and heterocycle formation. The proposed structures, mechanisms and products of fragmentation are supported by analysis of 13C and 15N labeled parent molecules, 6 different nitroalkene positional isomers, 6 nitroalkane positional isomers, accurate mass determinations at high resolution and quantum mechanics calculations. Multiple key diagnostic ion fragments were obtained through this analysis, allowing for the precise placement of double bonds and sites of fatty acid nitration, thus supporting an ability to predict nitro positions in biological samples. PMID:21953257

  8. Gluon fragmentation functions in the Nambu-Jona-Lasinio model

    NASA Astrophysics Data System (ADS)

    Yang, Dong-Jing; Li, Hsiang-nan

    2016-09-01

    We derive gluon fragmentation functions in the Nambu-Jona-Lasinio (NJL) model by treating a gluon as a pair of color lines formed by a fictitious quark and antiquark (q q ¯). Gluon elementary fragmentation functions are obtained from the quark and antiquark elementary fragmentation functions for emitting specific mesons in the NJL model under the requirement that the q q ¯ pair maintains in the flavor-singlet state after meson emissions. An integral equation, which iterates the gluon elementary fragmentation functions to all orders, is then solved to yield the gluon fragmentation functions at a model scale. It is observed that these solutions are stable with respect to variation of relevant model parameters, especially after QCD evolution to a higher scale is implemented. We show that the inclusion of the gluon fragmentation functions into the theoretical predictions from only the quark fragmentation functions greatly improves the agreement with the SLD data for the pion and kaon productions in e+e- annihilation. Our proposal provides a plausible construct for the gluon fragmentation functions, which are supposed to be null in the NJL model.

  9. Complex fragment emission at low and high excitation energy

    SciTech Connect

    Moretto, L.G.

    1986-08-01

    Complex fragment emission has been certified as a compound nucleus process at low energies. An extension of the measurements to heavy ion reactions up to 50 MeV/u shows that most complex fragments are emitted by highly excited compound nuclei formed in incomplete fusion reactions. 12 refs., 26 figs.

  10. Term Fragment Analysis for Inversion of Large Files.

    ERIC Educational Resources Information Center

    Schipma, Peter B.

    Words and word fragments from the computer-readable data bases "Chemical Abstracts Condensates" and "Biological Abstracts Previews" were analyzed in terms of length, number, and frequency of appearance to determine some parameters upon which inversion of these data bases could be predicated. Types (unique words or fragments)…

  11. The Progressive Fragmentation of 332P/Ikeya-Murakami

    NASA Astrophysics Data System (ADS)

    Kleyna, J. T.; Ye, Q.-Z.; Hui, M.-T.; Meech, K. J.; Wainscoat, R.; Micheli, M.; Keane, J. V.; Weaver, H. A.; Weryk, R.

    2016-08-01

    We describe 2016 January-April observations of the fragments of 332P/Ikeya-Murakami, a comet earlier observed in a 2010 October outburst. We present photometry of the fragments and perform simulations to infer the time of breakup. We argue that the eastern-most rapidly brightening fragment (F4) best corresponds to the original nucleus, rather than the initial bright fragment F1. We compute radial and tangential nongravitational parameters, A 1 = (1.5 ± 0.4) × 10-8 au day-2 and (7.2 ± 1.9) × 10-9 au day-2 both are consistent with zero at the 4σ level. Monte Carlo simulations indicate that the fragments were emitted on the outbound journey well after the 2010 outburst, with bright fragment F1 splitting in early 2014 and the fainter fragments within months of the 2016 January recovery. Western fragment F7 is the oldest, dating from 2011. We suggest that the delayed onset of the splitting is consistent with a self-propagating crystallization of water ice.

  12. Identifying Interactions that Determine Fragment Binding at Protein Hotspots.

    PubMed

    Radoux, Chris J; Olsson, Tjelvar S G; Pitt, Will R; Groom, Colin R; Blundell, Tom L

    2016-05-12

    Locating a ligand-binding site is an important first step in structure-guided drug discovery, but current methods do little to suggest which interactions within a pocket are the most important for binding. Here we illustrate a method that samples atomic hotspots with simple molecular probes to produce fragment hotspot maps. These maps specifically highlight fragment-binding sites and their corresponding pharmacophores. For ligand-bound structures, they provide an intuitive visual guide within the binding site, directing medicinal chemists where to grow the molecule and alerting them to suboptimal interactions within the original hit. The fragment hotspot map calculation is validated using experimental binding positions of 21 fragments and subsequent lead molecules. The ligands are found in high scoring areas of the fragment hotspot maps, with fragment atoms having a median percentage rank of 97%. Protein kinase B and pantothenate synthetase are examined in detail. In each case, the fragment hotspot maps are able to rationalize a Free-Wilson analysis of SAR data from a fragment-based drug design project.

  13. Microscopic investigations on the fragmentation of heavy nuclei

    NASA Astrophysics Data System (ADS)

    Jung, Chr.; Cassing, W.; Mosel, U.; Cusson, R. Y.

    1988-02-01

    Model calculations of fragmentation reactions in the TDH F approximation provide quantitative information about the stability of heavy nuclei in a mean-field description. A comparison of these results to proton-induced fragmentation reactions shows that mean-field nuclei are much too stable against local fluctuations caused, e.g., by residual nucleon-nucleon collisions.

  14. High-throughput fragment screening by affinity LC-MS.

    PubMed

    Duong-Thi, Minh-Dao; Bergström, Maria; Fex, Tomas; Isaksson, Roland; Ohlson, Sten

    2013-02-01

    Fragment screening, an emerging approach for hit finding in drug discovery, has recently been proven effective by its first approved drug, vemurafenib, for cancer treatment. Techniques such as nuclear magnetic resonance, surface plasmon resonance, and isothemal titration calorimetry, with their own pros and cons, have been employed for screening fragment libraries. As an alternative approach, screening based on high-performance liquid chromatography separation has been developed. In this work, we present weak affinity LC/MS as a method to screen fragments under high-throughput conditions. Affinity-based capillary columns with immobilized thrombin were used to screen a collection of 590 compounds from a fragment library. The collection was divided into 11 mixtures (each containing 35 to 65 fragments) and screened by MS detection. The primary screening was performed in <4 h (corresponding to >3500 fragments per day). Thirty hits were defined, which subsequently entered a secondary screening using an active site-blocked thrombin column for confirmation of specificity. One hit showed selective binding to thrombin with an estimated dissociation constant (K (D)) in the 0.1 mM range. This study shows that affinity LC/MS is characterized by high throughput, ease of operation, and low consumption of target and fragments, and therefore it promises to be a valuable method for fragment screening.

  15. Analysis of the fragmentation debris environment between 2005 and 2008

    NASA Astrophysics Data System (ADS)

    Flegel, Sven Kevin; Stabroth, Sebastian; Wiedemann, Carsten; Klinkrad, Heiner; Krag, Holger; Vörsmann, Peter

    Several fragmentation events have occurred in the years since the release of the ESA space debris model MASTER-2005 (Meteoroid and Space Debris Terrestrial Environment Reference). During this period some notable events took place which resulted in an unusually large increase in the spatial debris density. A compilation of the fragmentation events between 2005 and 2008 is presented based on data gathered from the literature. Event parameters such as object type and location are discussed. The spatial object density is then simulated using the MASTER- 2005 population generation tool POEM (Program for Orbital Debris Environment Modelling). The NASA Breakup Model implemented in POEM is used to determine the properties of the initial cloud of fragments for each event. Propagating the orbital elements of all fragments yields the time dependent evolution of the object clouds. Spatial densities are then calculated from the distribution of the fragments. The results are discussed for all events in the detailed time frame. The changes in the orbital fragment environment since 2005 as a consequence of the presented events are of further interest. To this end, the overall density which is obtained from the simulations with POEM is compared to the predicted growth of the total spatial density. The prediction for the fragmentation debris is generated with MASTER-2005 on the basis of a business-as-usual scenario for the year 2005. Deviations between the resulting spatial density distributions are discussed in terms of fragmentation rates, breakup locations and breakup cause.

  16. Study of Shape Isomeric States in Fission Fragments

    NASA Astrophysics Data System (ADS)

    Pyatkov, Yu. V.; Kamanin, D. V.; Alexandrov, A. A.; Alexandrova, I. A.; Kondtatyev, N. A.; Kuznetsova, , E. A.; Strekalovsky, A. O.; Strekalovsky, O. V.; Zhuchko, V. E.; Mkaza, N.

    2015-06-01

    For the first time the brake-up of the fission fragments crossing metal foil was observed. The effect takes place predominantly in front impacts. To treat the data we suppose the bulk of the fragments from the conventional binary fission to be borne in shape-isomer states which look like di-nuclear systems with magic cores.

  17. Detection of single lambda DNA fragments by flow cytometry

    SciTech Connect

    Johnson, M.E.; Goodwin, P.M.; Ambrose, W.P.; Martin, J.C.; Marrone, B.L.; Keller, R.A. )

    1993-01-01

    The authors have demonstrated flow cytometric detection and sizing of single pieces of fluorescently stained lambda DNA (48.5 kb) and individual Kpn I restriction fragments of lambda DNA at 17.05 kb and 29.95 kb. DNA fragments were stained stoichiometrically with an intercalating dye such that the fluorescence from each fragment was directly proportional to fragment length. Laser powers range from 10 to 100 mW and transit times through the focused laser beam were several milliseconds. Measurements were made using time-resolved single photon counting of the detected fluorescence emission from individual stained DNA fragments. Samples were analyzed at rates of about 50 fragments per second. The measured fluorescence intensities are linearly correlated with DNA fragment length over the range measured. Detection sensitivity and resolution needed for analysis of small pieces of DNA are discussed and a comparison of single photon counting measurements of DNA fragments to measurements using more conventional flow cytometers is made. Applications of this methodology to DNA sizing and DNA fingerprinting are discussed.

  18. Internal structure and fragmentation kinetics of silica granules

    NASA Astrophysics Data System (ADS)

    Grosseau, P.; Dumas, T.; Bonnefoy, O.; Barriquand, L.; Guy, L.; Thomas, G.

    2013-06-01

    To improve the mechanical properties of tires, silica granules can be incorporated into the elastomer as well as carbon black. Ideally, the fragmentation of the granules in the elastomer must be obtained with low mechanical stresses and lead to very small fragments distributed homogeneously in the material. On the other hand, granules must present a sufficient cohesion, in order to avoid the generation of fine particles during handling operations. Thus it appears necessary to control the mechanical strength of granules and the mechanism of their fragmentation. In this experimental study, we investigated the fragmentation of silica granules of 250 microns produced by spray drying. For this, we characterized by granulometry the evolution of the Particle Size Distribution of silica powder in water. The granules were suspended in water and submitted to ultrasounds. This treatment is used to create the fragmentation that occurs by viscous shearing in industrial rubber processing. A core-shell structure, characteristic of granules obtained by atomization process, was observed by SEM. Furthermore, by varying the intensity of mechanical stress, the multi-scale structure of granules was evidenced as well as the existence of different regimes of fragmentation. The kinetics of fragmentation was experimentally followed on two grades of silica that showed significant differences in their behavior during the fragmentation process.

  19. Visualization of sneeze ejecta: steps of fluid fragmentation leading to respiratory droplets

    NASA Astrophysics Data System (ADS)

    Scharfman, B. E.; Techet, A. H.; Bush, J. W. M.; Bourouiba, L.

    2016-02-01

    Coughs and sneezes feature turbulent, multiphase flows that may contain pathogen-bearing droplets of mucosalivary fluid. As such, they can contribute to the spread of numerous infectious diseases, including influenza and SARS. The range of contamination of the droplets is largely determined by their size. However, major uncertainties on the drop size distributions persist. Here, we report direct observation of the physical mechanisms of droplet formation at the exit of the mouth during sneezing. Specifically, we use high-speed imaging to directly examine the fluid fragmentation at the exit of the mouths of healthy subjects. We reveal for the first time that the breakup of the fluid into droplets continues to occur outside of the respiratory tract during violent exhalations. We show that such breakup involves a complex cascade of events from sheets, to bag bursts, to ligaments, which finally break into droplets. Finally, we reveal that the viscoelasticity of the mucosalivary fluid plays an important role in delaying fragmentation by causing the merger of the droplet precursors that form along stretched filaments; thereby affecting the final drop size distribution farther downstream.

  20. Phenocryst fragments in rhyolitic lavas and lava domes

    NASA Astrophysics Data System (ADS)

    Allen, S. R.; McPhie, J.

    2003-08-01

    Although rhyolitic lavas and lava domes are characterised by evenly porphyritic textures, not all the phenocrysts are whole euhedra. We undertook image analysis of 46 rhyolitic lava and lava dome samples to determine the abundance and shape of quartz and feldspar phenocryst fragments. Phenocryst fragments were identified in nearly all samples. On average, fragments amount to ˜5% of the total phenocryst population, or ˜0.5 modal%. The abundance of fragments in lavas and lava domes is not related to the groundmass texture (whether vesicular, flow banded, massive, glassy or crystalline), nor to distance from source. Fragments are, however, more abundant in samples with higher phenocryst contents. The phenocryst fragments in rhyolitic lavas and lava domes are mainly medium to large (0.5-3.5 mm), almost euhedral crystals with only a small portion removed, or chunky, equant, subhedral fragments, and occur in near-jigsaw-fit or clast-rotated pairs or groups. The fragments probably formed in response to decompression of large melt inclusions. Shear during laminar flow then dismembered the phenocrysts; continued laminar shear separated and rotated the fragments. Fractures probably formed preferentially along weaknesses in the phenocrysts, such as zones of melt inclusions, cleavage planes and twin composition planes. Rare splintery fragments are also present, especially within devitrified domains. Splinters are attributed to comminution of solid lava adjacent to fractures that were later healed. For comparison, we measured crystal abundance in a further 12 rhyolite samples that include block and ash flow deposits and ignimbrite. Phenocryst fragments within clasts in the block and ash flow samples showed similar shapes and abundances to those fragments within the lava and lava domes. Crystal fragments are much more abundant in ignimbrite (exceeding 67% of the crystal population) however, and dominated by small, equant, anhedral chunks or splinters. The larger crystals in

  1. Relativistic correction to gluon fragmentation function into pseudoscalar quarkonium

    NASA Astrophysics Data System (ADS)

    Gao, Xiangrui; Jia, Yu; Li, Liuji; Xiong, Xiaonu

    2017-02-01

    Inspired by the recent measurements of the ηc meson production at LHC experiments, we investigate the relativistic correction effect for the fragmentation functions of gluon/charm quark fragmenting into ηc, which constitute the crucial nonperturbative element for the ηc production at high p T. Employing three distinct methods, we calculate the next-to-leading-order (NLO) relativistic correction to g → ηc fragmentation function in the NRQCD factorization framework, as well as verifying the existing NLO result for the c → ηc fragmentation function. We also study the evolution behavior of these fragmentation functions with the aid of the DGLAP equation. Supported by National Natural Science Foundation of China (11475188, 11261130311, 11575202, 11222549), IHEP Innovation (Y4545170Y2), State Key Lab for Electronics and Particle Detectors

  2. Fragmentation of a Viscoelastic Food by Human Mastication

    NASA Astrophysics Data System (ADS)

    Kobayashi, Naoki; Kohyama, Kaoru; Shiozawa, Kouichi

    2010-04-01

    Fragment-size distributions have been studied experimentally in masticated viscoelastic food (fish sausage). The mastication experiment in seven subjects was examined. We classified the obtained results into two groups, namely, a single lognormal distribution and a lognormal distribution with exponential tail group. The facts suggest that the individual variability might affect the fragmentation pattern when the food sample has a much more complicated physical property. In particular, the latter result (lognormal distribution with exponential tail) indicates that the fragmentation pattern by human mastication for fish sausage is different from the fragmentation pattern for raw carrot shown in our previous study. \\cite{KKSM06} The excellent data fitting by the lognormal distribution with exponential tail implies that the fragmentation process has a size-segregation-structure between large and small parts. In order to explain this structure, we propose a mastication model for fish sausage based on stochastic processes.

  3. Habitat fragmentation may not matter to species diversity

    PubMed Central

    Yaacobi, Gal; Ziv, Yaron; Rosenzweig, Michael L

    2007-01-01

    Conservation biologists worry that fragmenting a bloc of natural habitat might reduce its species diversity. However, they also recognize the difficulty and importance of isolating the effect of fragmentation from that of simple loss of area. Using two different methods (species–area curve and Fisher's α index of diversity) to analyse the species diversities of plants, tenebrionid beetles and carabid beetles in a highly fragmented Mediterranean scrub landscape, we decoupled the effect of degree of fragmentation from that of area loss. In this system, fragmentation by itself seems not to have influenced the number of species. Our results, obtained at the scale of hectares, agree with similar results at island and continent scales. PMID:17666380

  4. Nuclear fragmentation measurements for hadrontherapy and space radiation protection

    NASA Astrophysics Data System (ADS)

    De Napoli, M.; Agodi, C.; Battistoni, G.; Blancato, A. A.; Bondı, M.; Cappuzzello, F.; Carbone, D.; Cavallaro, M.; Cirrone, G. A. P.; Cuttone, G.; Giacoppo, F.; Morone, M. C.; Nicolosi, D.; Pandola, L.; Raciti, G.; Rapisarda, E.; Romano, F.; Sardina, D.; Scuderi, V.; Sfienti, C.; Tropea, S.

    2013-04-01

    Nuclear fragmentation measurements are necessary in hadrontherapy and space radiation protection, to predict the effects of the ion nuclear interactions within the human body. Nowadays, a very limited set of carbon fragmentation cross sections has been measured and in particular, to our knowledge, no double differential fragmentation cross sections at intermediate energies are available in literature. We have measured the double differential cross sections and the angular distributions of the secondary fragments produced in the 12C fragmentation at 62 AMeV on a thin carbon target. The experimental data have been also used to benchmark the prediction capability of the Geant4 Monte Carlo code at intermediate energies, where it was never tested before.

  5. Habitat fragmentation, climate change, and inbreeding in plants.

    PubMed

    Leimu, Roosa; Vergeer, Philippine; Angeloni, Francesco; Ouborg, N Joop

    2010-05-01

    Habitat fragmentation and climate change are recognized as major threats to biodiversity. The major challenge for present day plant populations is how to adapt and cope with altered abiotic and biotic environments caused by climate change, when at the same time adaptive and evolutionary potential is decreased as habitat fragmentation reduces genetic variation and increases inbreeding. Although the ecological and evolutionary effects of fragmentation and climate change have been investigated separately, their combined effects remained largely unexplored. In this review, we will discuss the individual and joint effects of habitat fragmentation and climate change on plants and how the abilities and ways in which plants can respond and cope with climate change may be compromised due to habitat fragmentation.

  6. Metal and phosphide phases in Luna 24 soil fragments

    NASA Astrophysics Data System (ADS)

    Axon, H. J.; Nasir, M. J.; Knowles, F.

    1980-06-01

    Soil fragments in the 106-150 and 150-250 micron size ranges were selected for metallographic and microprobe examination on the basis of their magnetic properties. Serial sections of the mounted fragments were examined. One fragment proved to be a compositionally zoned crystal of phosphide with no metal phase but partly embedded in glass. Another was a coarse-grained association of silica with ilmenite and fayalite with a 5-micron particle of metallic iron in troilite. One splinter of oxide contained a central spine of metallic iron. The remaining six fragments contained 10-micron particles of iron-nickel-cobalt alloy with compositions in either the 'meteoritic' or the low Ni-low Co sub-meteoritic composition ranges of Ni, Co content. In some fragments separate particles of alloy had different Ni, Co contents. No particles of high Co metal were encountered.

  7. Primary and secondary fragmentation of crystal-bearing intermediate magma

    NASA Astrophysics Data System (ADS)

    Jones, Thomas J.; McNamara, Keri; Eychenne, Julia; Rust, Alison C.; Cashman, Katharine V.; Scheu, Bettina; Edwards, Robyn

    2016-11-01

    Crystal-rich intermediate magmas are subjected to both primary and secondary fragmentation processes, each of which may produce texturally distinct tephra. Of particular interest for volcanic hazards is the extent to which each process contributes ash to volcanic plumes. One way to address this question is by fragmenting pyroclasts under controlled conditions. We fragmented pumice samples from Soufriere Hills Volcano (SHV), Montserrat, by three methods: rapid decompression in a shock tube-like apparatus, impact by a falling piston, and milling in a ball mill. Grain size distributions of the products reveal that all three mechanisms produce fractal breakage patterns, and that the fractal dimension increases from a minimum of 2.1 for decompression fragmentation (primary fragmentation) to a maximum of 2.7 by repeated impact (secondary fragmentation). To assess the details of the fragmentation process, we quantified the shape, texture and components of constituent ash particles. Ash shape analysis shows that the axial ratio increases during milling and that particle convexity increases with repeated impacts. We also quantify the extent to which the matrix is separated from the crystals, which shows that secondary processes efficiently remove adhering matrix from crystals, particularly during milling (abrasion). Furthermore, measurements of crystal size distributions before (using x-ray computed tomography) and after (by componentry of individual grain size classes) decompression-driven fragmentation show not only that crystals influence particular size fractions across the total grain size distribution, but also that free crystals are smaller in the fragmented material than in the original pumice clast. Taken together, our results confirm previous work showing both the control of initial texture on the primary fragmentation process and the contributions of secondary processes to ash formation. Critically, however, our extension of previous analyses to characterisation

  8. Transcriptome analysis reveals signature of adaptation to landscape fragmentation.

    PubMed

    Somervuo, Panu; Kvist, Jouni; Ikonen, Suvi; Auvinen, Petri; Paulin, Lars; Koskinen, Patrik; Holm, Liisa; Taipale, Minna; Duplouy, Anne; Ruokolainen, Annukka; Saarnio, Suvi; Sirén, Jukka; Kohonen, Jukka; Corander, Jukka; Frilander, Mikko J; Ahola, Virpi; Hanski, Ilkka

    2014-01-01

    We characterize allelic and gene expression variation between populations of the Glanville fritillary butterfly (Melitaea cinxia) from two fragmented and two continuous landscapes in northern Europe. The populations exhibit significant differences in their life history traits, e.g. butterflies from fragmented landscapes have higher flight metabolic rate and dispersal rate in the field, and higher larval growth rate, than butterflies from continuous landscapes. In fragmented landscapes, local populations are small and have a high risk of local extinction, and hence the long-term persistence at the landscape level is based on frequent re-colonization of vacant habitat patches, which is predicted to select for increased dispersal rate. Using RNA-seq data and a common garden experiment, we found that a large number of genes (1,841) were differentially expressed between the landscape types. Hexamerin genes, the expression of which has previously been shown to have high heritability and which correlate strongly with larval development time in the Glanville fritillary, had higher expression in fragmented than continuous landscapes. Genes that were more highly expressed in butterflies from newly-established than old local populations within a fragmented landscape were also more highly expressed, at the landscape level, in fragmented than continuous landscapes. This result suggests that recurrent extinctions and re-colonizations in fragmented landscapes select a for specific expression profile. Genes that were significantly up-regulated following an experimental flight treatment had higher basal expression in fragmented landscapes, indicating that these butterflies are genetically primed for frequent flight. Active flight causes oxidative stress, but butterflies from fragmented landscapes were more tolerant of hypoxia. We conclude that differences in gene expression between the landscape types reflect genomic adaptations to landscape fragmentation.

  9. Cassini's Grand Finale: The Final Orbits

    NASA Astrophysics Data System (ADS)

    Spilker, Linda; Edgington, Scott

    2016-04-01

    The Cassini-Huygens mission, a joint collaboration between NASA, ESA and the Italian Space Agency, is approaching its last year of operations after nearly 12 years in orbit around Saturn. Cassini will send back its final bits of unique data on September 15th, 2017 as it plunges into Saturn's atmosphere, vaporizing and satisfying planetary protection requirements. Before that time Cassini will continue its legacy of exploration and discovery with 12 close flybys of Titan in 2016 and 2017 that will return new science data as well as sculpt the inclinations and periods of the final orbits. Even though all of our close icy satellite flybys, including those of Enceladus, are now completed, numerous Voyager-class flybys (<100,000 km) of Mimas and Enceladus remain as well as some of our best flybys of the tiny ring moons. Cassini will also continue to study seasonal and temporal changes in the system as northern summer solstice approaches. In November 2016 Cassini will transition to a series of orbits with peripases just outside Saturn's F ring. These 20 orbits will include close flybys of some tiny ring moons and excellent views of the F ring and outer A ring. The 126th and final close flyby of Titan will propel Cassini across Saturn's main rings and into its final orbits. Cassini's Grand Finale, starting in April 2017, is comprised of 22 orbits at an inclination of 63 degrees. Cassini will repeatedly dive between the innermost rings and the upper atmosphere of the planet providing insights into fundamental questions unattainable during the rest of the mission. Cassini will be the first spacecraft to explore this region. These close orbits provide the highest resolution observations of both the rings and Saturn, and direct in situ sampling of the ring particles, composition, plasma, Saturn's exosphere and the innermost radiation belts. Saturn's gravitational field will be measured to unprecedented accuracy, providing information on the interior structure of the planet

  10. Beyond the fragmentation threshold hypothesis: regime shifts in biodiversity across fragmented landscapes.

    PubMed

    Pardini, Renata; Bueno, Adriana de Arruda; Gardner, Toby A; Prado, Paulo Inácio; Metzger, Jean Paul

    2010-10-27

    Ecological systems are vulnerable to irreversible change when key system properties are pushed over thresholds, resulting in the loss of resilience and the precipitation of a regime shift. Perhaps the most important of such properties in human-modified landscapes is the total amount of remnant native vegetation. In a seminal study Andrén proposed the existence of a fragmentation threshold in the total amount of remnant vegetation, below which landscape-scale connectivity is eroded and local species richness and abundance become dependent on patch size. Despite the fact that species patch-area effects have been a mainstay of conservation science there has yet to be a robust empirical evaluation of this hypothesis. Here we present and test a new conceptual model describing the mechanisms and consequences of biodiversity change in fragmented landscapes, identifying the fragmentation threshold as a first step in a positive feedback mechanism that has the capacity to impair ecological resilience, and drive a regime shift in biodiversity. The model considers that local extinction risk is defined by patch size, and immigration rates by landscape vegetation cover, and that the recovery from local species losses depends upon the landscape species pool. Using a unique dataset on the distribution of non-volant small mammals across replicate landscapes in the Atlantic forest of Brazil, we found strong evidence for our model predictions--that patch-area effects are evident only at intermediate levels of total forest cover, where landscape diversity is still high and opportunities for enhancing biodiversity through local management are greatest. Furthermore, high levels of forest loss can push native biota through an extinction filter, and result in the abrupt, landscape-wide loss of forest-specialist taxa, ecological resilience and management effectiveness. The proposed model links hitherto distinct theoretical approaches within a single framework, providing a powerful tool

  11. Fragmentation and Coverage Variation in Viral Metagenome Assemblies, and Their Effect in Diversity Calculations.

    PubMed

    García-López, Rodrigo; Vázquez-Castellanos, Jorge Francisco; Moya, Andrés

    2015-01-01

    , calculations using contigs as different OTUs ultimately overestimate diversity when compared to diversity calculated from species coverage. In order to compare the effect of coverage and fragmentation, we generated three sets of simulated Illumina paired-end reads with different sequencing depths. We compared different assemblies performed with RayMeta, CLC Assembly Cell, MEGAHIT, SPAdes, Meta-IDBA, SOAPdenovo, Velvet, Metavelvet, and MIRA with the best attainable assemblies for each dataset (formed by arranging data using known genome coordinates) by calculating different assembly statistics. A new fragmentation score was included to estimate the degree of genome fragmentation of each taxon and adjust the coverage accordingly. The abundance in the metagenome was compared by bootstrapping the assembly data and hierarchically clustering them with the best possible assembly. Additionally, richness and diversity indexes were calculated for all the resulting assemblies and were assessed under two distributions: contigs as independent OTUs and sequences classified by species. Finally, we search for the strongest correlations between the diversity indexes and the different assembly statistics. Although fragmentation was dependent of genome coverage, it was not as heavily influenced by the assembler. The sequencing depth was the predominant attractor that influenced the success of the assemblies. The coverage increased notoriously in larger datasets, whereas fragmentation values remained lower and unsaturated. While still far from obtaining the ideal assemblies, the RayMeta, SPAdes, and the CLC assemblers managed to build the most accurate contigs with larger datasets while Meta-IDBA showed a good performance with the medium-sized dataset, even after the adjusted coverage was calculated. Their resulting assemblies showed the highest coverage scores and the lowest fragmentation values. Alpha diversity calculated from contigs as OTUs resulted in significantly higher values for all

  12. Generalized-ensemble simulations of the human parathyroid hormone fragment PTH(1-34)

    NASA Astrophysics Data System (ADS)

    Hansmann, Ulrich H. E.

    2004-01-01

    A generalized-ensemble technique, multicanonical sampling, is used to study the folding of a 34-residue human parathyroid hormone fragment. An all-atom model of the peptide is employed and the protein-solvent interactions are approximated by an implicit solvent. Our results demonstrate that generalized-ensemble simulations are well suited to sample low-energy structures of such large polypeptides. Configurations with a root-mean-square deviation to the crystal structure of less than 1 Å are found. Finally, we discuss limitations of our implicit solvent model.

  13. Nuclear fragmentation energy and momentum transfer distributions in relativistic heavy-ion collisions

    NASA Technical Reports Server (NTRS)

    Khandelwal, Govind S.; Khan, Ferdous

    1989-01-01

    An optical model description of energy and momentum transfer in relativistic heavy-ion collisions, based upon composite particle multiple scattering theory, is presented. Transverse and longitudinal momentum transfers to the projectile are shown to arise from the real and absorptive part of the optical potential, respectively. Comparisons of fragment momentum distribution observables with experiments are made and trends outlined based on our knowledge of the underlying nucleon-nucleon interaction. Corrections to the above calculations are discussed. Finally, use of the model as a tool for estimating collision impact parameters is indicated.

  14. High-resolution (e, 2e + ion) study of electron-impact ionization and fragmentation of methane

    SciTech Connect

    Ren, Xueguang Pflüger, Thomas; Weyland, Marvin; Baek, Woon Yong; Rabus, Hans; Ullrich, Joachim; Dorn, Alexander

    2015-05-07

    The ionization and fragmentation of methane induced by low-energy (E{sub 0} = 66 eV) electron-impact is investigated using a reaction microscope. The momentum vectors of all three charged final state particles, two outgoing electrons, and one fragment ion, are detected in coincidence. Compared to the earlier study [Xu et al., J. Chem. Phys. 138, 134307 (2013)], considerable improvements to the instrumental mass and energy resolutions have been achieved. The fragment products CH{sub 4}{sup +}, CH{sub 3}{sup +}, CH{sub 2}{sup +}, CH{sup +}, and C{sup +} are clearly resolved. The binding energy resolution of ΔE = 2.0 eV is a factor of three better than in the earlier measurements. The fragmentation channels are investigated by measuring the ion kinetic energy distributions and the binding energy spectra. While being mostly in consistence with existing photoionization studies the results show differences including missing fragmentation channels and previously unseen channels.

  15. Fragmentation dynamics of argon clusters (Arn, n =2 to 11) following electron-impact ionization: Modeling and comparison with experiment

    NASA Astrophysics Data System (ADS)

    Bonhommeau, David; Halberstadt, Nadine; Viel, Alexandra

    2006-05-01

    The fragmentation dynamics of argon clusters ionized by electron impact is investigated for initial cluster sizes up to n =11 atoms. The dynamics of the argon atoms is modeled using a mixed quantum-classical method in which the nuclei are treated classically and the transitions between electronic states quantum mechanically. The potential-energy surfaces are derived from a diatomics-in-molecules model with the addition of the induced dipole-induced dipole and spin-orbit interactions. The results show extensive and fast fragmentation. The dimer is the most abundant ionic fragment, with a proportion increasing from 66% for n =2 to a maximum of 95% for n =6 and then decreasing down to 67% for n =11. The next abundant fragment is the monomer for n <7 and the trimer otherwise. The parent ion dissociation lifetimes are all in the range of 1ps. Long-lived trajectories appear for initial cluster sizes of seven and higher, and favor the formation of the larger fragments (trimers and tetramers). Our results show quantitative agreement with available experimental results concerning the extensive character of the fragmentation: Ar+ and Ar2+ are the only ionic fragments for sizes up to five atoms; their overall proportion is in quantitative agreement for all the studied sizes; Ar2+ is the main fragment for all sizes; stable Ar3+ fragments only appear for n ⩾5, and their proportion increases smoothly with cluster size from there. However, the individual ionic monomer and dimer fragment proportions differ. The experimental ones exhibit oscillations with initial cluster size, with a slight tendency to decrease on average for the monomer. In contrast our results show a monotonic, systematic evolution, similar to what was found in our earlier studies on neon and krypton clusters. Several hypotheses are discussed in order to find the origin of this discrepancy. Finally, the metastable II(1/2)u and II(1/2)g states of Ar2+ are found to decay with a lifetime of 3.5 and 0.1ps

  16. Tropical forest fragmentation limits pollination of a keystone understory herb.

    PubMed

    Hadley, Adam S; Frey, Sarah J K; Robinson, W Douglas; Kress, W John; Betts, Matthew G

    2014-08-01

    Loss of native vegetation cover is thought to be a major driver of declines in pollination success worldwide. However, it is not well known whether reducing the fragmentation of remaining vegetation can ameliorate these negative effects. We tested the independent effects of composition vs. configuration on the reproductive success of a keystone tropical forest herb (Heliconia tortuosa). To do this we designed a large-scale mensurative experiment that independently varied connected forest-patch size (configuration) and surrounding amount of forest (composition). In each patch, we tested whether pollen tubes, fruit, and seed set were associated with these landscape variables. We also captured hummingbirds as an indication of pollinator availability in a subset of patches according to the same design. We found evidence for an effect of configuration on seed set of H. tortuosa, but not on other aspects of plant reproduction; proportion of seeds produced increased 40% across the gradient in patch size we observed (0.64 to > 1300 ha), independent of the amount of forest in the surrounding landscape at both local and landscape scales. We also found that the availability of pollinators was dependent upon forest configuration; hummingbird capture rates increased three and one-half times across the patch size gradient, independent of forest amount. Finally, pollinator availability was strongly positively correlated with seed set. We hypothesize that the effects of configuration on plant fitness that we observed are due to reduced pollen quality resulting from altered hummingbird availability and/or movement behavior. Our results suggest that prioritizing larger patches of tropical forest may be particularly important for conservation of this species.

  17. PLANETARY CORE FORMATION WITH COLLISIONAL FRAGMENTATION AND ATMOSPHERE TO FORM GAS GIANT PLANETS

    SciTech Connect

    Kobayashi, Hiroshi; Krivov, Alexander V.; Tanaka, Hidekazu

    2011-09-01

    Massive planetary cores ({approx}10 Earth masses) trigger rapid gas accretion to form gas giant planets such as Jupiter and Saturn. We investigate the core growth and the possibilities for cores to reach such a critical core mass. At the late stage, planetary cores grow through collisions with small planetesimals. Collisional fragmentation of planetesimals, which is induced by gravitational interaction with planetary cores, reduces the amount of planetesimals surrounding them, and thus the final core masses. Starting from small planetesimals that the fragmentation rapidly removes, less massive cores are formed. However, planetary cores acquire atmospheres that enlarge their collisional cross section before rapid gas accretion. Once planetary cores exceed about Mars mass, atmospheres significantly accelerate the growth of cores. We show that, taking into account the effects of fragmentation and atmosphere, initially large planetesimals enable formation of sufficiently massive cores. On the other hand, because the growth of cores is slow for large planetesimals, a massive disk is necessary for cores to grow enough within a disk lifetime. If the disk with 100 km sized initial planetesimals is 10 times as massive as the minimum mass solar nebula, planetary cores can exceed 10 Earth masses in the Jovian planet region (>5 AU).

  18. Extraction of quark transversity distribution and Collins fragmentation functions with QCD evolution

    SciTech Connect

    Kang, Zhong-Bo; Prokudin, Alexei; Sun, Peng; Yuan, Feng

    2016-01-13

    In this paper, we study the transverse momentum dependent (TMD) evolution of the Collins azimuthal asymmetries in e+e- annihilations and semi-inclusive hadron production in deep inelastic scattering (SIDIS) processes. All the relevant coefficients are calculated up to the next-to-leading logarithmic (NLL) order accuracy. By applying the TMD evolution at the approximate NLL order in the Collins- Soper-Sterman (CSS) formalism, we extract transversity distributions for u and d quarks and Collins fragmentation functions from current experimental data by a global analysis of the Collins asymmetries in back-to-back di-hadron productions in e+e- annihilations measured by BELLE and BABAR Collaborations and SIDIS data from HERMES, COMPASS, and JLab HALL A experiments. The impact of the evolution effects and the relevant theoretical uncertainties are discussed. We further discuss the TMD interpretation for our results, and illustrate the unpolarized quark distribution, transversity distribution, unpolarized quark fragmentation and Collins fragmentation functions depending on the transverse momentum and the hard momentum scale. Finally, we give predictions and discuss impact of future experiments.

  19. Extraction of quark transversity distribution and Collins fragmentation functions with QCD evolution

    DOE PAGES

    Kang, Zhong-Bo; Prokudin, Alexei; Sun, Peng; ...

    2016-01-13

    In this paper, we study the transverse momentum dependent (TMD) evolution of the Collins azimuthal asymmetries in e+e- annihilations and semi-inclusive hadron production in deep inelastic scattering (SIDIS) processes. All the relevant coefficients are calculated up to the next-to-leading logarithmic (NLL) order accuracy. By applying the TMD evolution at the approximate NLL order in the Collins- Soper-Sterman (CSS) formalism, we extract transversity distributions for u and d quarks and Collins fragmentation functions from current experimental data by a global analysis of the Collins asymmetries in back-to-back di-hadron productions in e+e- annihilations measured by BELLE and BABAR Collaborations and SIDIS datamore » from HERMES, COMPASS, and JLab HALL A experiments. The impact of the evolution effects and the relevant theoretical uncertainties are discussed. We further discuss the TMD interpretation for our results, and illustrate the unpolarized quark distribution, transversity distribution, unpolarized quark fragmentation and Collins fragmentation functions depending on the transverse momentum and the hard momentum scale. Finally, we give predictions and discuss impact of future experiments.« less

  20. The potential effects of climate change on amphibian distribution, range fragmentation and turnover in China

    PubMed Central

    Huang, Min-Yi; Varela, Sara

    2016-01-01

    Many studies predict that climate change will cause species movement and turnover, but few have considered the effect of climate change on range fragmentation for current species and/or populations. We used MaxEnt to predict suitable habitat, fragmentation and turnover for 134 amphibian species in China under 40 future climate change scenarios spanning four pathways (RCP2.6, RCP4.5, RCP6 and RCP8.5) and two time periods (the 2050s and 2070s). Our results show that climate change may cause a major shift in spatial patterns of amphibian diversity. Amphibians in China would lose 20% of their original ranges on average; the distribution outside current ranges would increase by 15%. Suitable habitats for over 90% of species will be located in the north of their current range, for over 95% of species in higher altitudes (from currently 137–4,124 m to 286–4,396 m in the 2050s or 314–4,448 m in the 2070s), and for over 75% of species in the west of their current range. Also, our results predict two different general responses to the climate change: some species contract their ranges while moving westwards, southwards and to higher altitudes, while others expand their ranges. Finally, our analyses indicate that range dynamics and fragmentation are related, which means that the effects of climate change on Chinese amphibians might be two-folded. PMID:27547522