Science.gov

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

    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

  3. 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

  4. 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.

  5. 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. PMID:26774251

  6. [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. PMID:24176734

  7. Multiple stabbing in sex-related homicides.

    PubMed

    Radojević, Nemanja; Radnić, Bojana; Petković, Stojan; Miljen, Maletin; Curović, Ivana; Cukić, Dragana; Soć, Miodrag; Savić, Slobodan

    2013-07-01

    It is possible that sexually driven homicides are the consequence of sexual deviation, but more often than not the main cause of such homicides stems from a non-paraphilic person's emotional component. It is known that homicides which involve multiple stabbing are very often the result of the assailant's highly expressed affect. This study tries to establish whether such homicides are essentially related to the sexual motives of the murderer. This paper is conducted through a retrospective autopsy study that includes 766 cases of homicides. These were reviewed and analysed according to the motive of the homicide, as well as by method, age, and gender of the victim, and the relationship between the victim and the assailant. The motives of homicides are classified as non-sexual and sexual, including homicides related to rape, jealousy, amorous affairs outside of an established relationship, deviant sexual behaviour of psychiatric patients, paraphilia, and disturbed emotional relationships between the victim and the assailant. Cases include both hetero- and homosexual relationships. Multiple stabbing occurs significantly more frequently in sex-related homicides (≥ 3 stab wounds) than in other homicide types. When the criteria for multiple stabbing are changed (≥ 4, 5, or 25 stab wounds), the percentage of sex-related homicides rises in every group in relation to the increased number of wounds. Sensitivity and specificity are represented by ROC curves for 3, 5 and 7 stab wounds. The correlation coefficients between multiple stabbing and sex-related homicides regarding gender are all near 0.9. For female victims, all homicides committed by 25 and more stab wounds were found to be sex-related. Statistically, jealousy was the most frequent motive for sex-related multiple stabbing homicides. Regardless of age, homicides involving multiple stabbings should be considered sex-related, especially when the victim is female. PMID:23756522

  8. Intracranial complications of transorbital stab wounds.

    PubMed Central

    De Villiers, J C; Sevel, D

    1975-01-01

    Oscular and orbital injuries due to stab wounds may mask underlying serious intracranial damage. The correct clinical assessment and treatment of such cases require the attention of a team comprising a neurosurgeon, ophthalmologist, otolaryngologist, and plastic surgeon. Images PMID:1125159

  9. 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

  10. 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

  11. Retained garden fork following cranial stab injury

    PubMed Central

    Gonya, Sonwabile; Mbatha, Andile; Moyeni, Nondabula; Enicker, Basil

    2016-01-01

    Retained garden fork is a rare complication of penetrating cranial trauma. Retained knife blade is the most commonly reported presentation. We report an unusual case of a 30-year-old male patient treated at our institution, who presented with a retained garden fork following a stab to the head, with no associated neurological deficits. Computerized tomographic scan of the brain was performed preoperatively to assess the trajectory of the weapon and parenchymal injury. A craniectomy was performed to facilitate removal of the weapon in the operating theatre under general anaesthesia. Intravenous prophylactic antibiotics were administered pre- and postoperatively to prevent septic complications. The patient recovered well and was discharged home. PMID:26747398

  12. Toward a Predictive Assessment of Stab-Penetration Forces.

    PubMed

    Ní Annaidh, Aisling; Cassidy, Marie; Curtis, Michael; Destrade, Michel; Gilchrist, Michael D

    2015-09-01

    Collaborative research between the disciplines of forensic pathology and biomechanics was undertaken to investigate the hyperelastic properties of human skin, to determine the force required for sharp instrument penetration of skin, and to develop a finite element model, which reflects the mechanisms of sharp instrument penetration. These studies have led to the development of a "stab metric," based on simulations, to describe the force magnitudes in stabbing incidents. Such a metric should, in time, replace the crudely quantitative descriptors of stabbing forces currently used by forensic pathologists. PMID:24781391

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

    PubMed Central

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

    2015-01-01

    [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. PMID:26834329

  14. Socioeconomic aspects of stab and gunshot wounds.

    PubMed

    Wase, R E; Hamit, H F

    1979-09-01

    Records of 294 patients with gunshot, stab, or shotgun wounds admitted to Charlotte Memorial Hospital and Medical Center between July 1, 1976 and June 30, 1977 were reviewed. Data were gathered on 24 clinical, social, and economic aspects to discover any patterns in these areas. Eighty-three percent of the patients were male; 71%, black; 70%, unmarried; and 56%, between 16 and 30 years of age. Fifty-five percent came to the hospital between 10 pm and 3 am; 57% on Friday, Saturday, or Sunday; 31% came in June, July, or August. Sixty-four percent were gunshot wounds, 80% of which were by small caliber weapons. Ninety-four percent of all patients survived. The patients "consumed" 3,260 hosptial days, 526 intensive care unit days, 533 units of blood, and 261 operations, totaling 595 hours of operating room time. Hospital charges totaled $668,000, of which 1.1% was paid from private funds and nearly 65% from the taxpayers and other private paying patients. PMID:470276

  15. [Survived stab to the heart in a schizophrenic man].

    PubMed

    Fieseler, Sybille; Zinka, Bettina; Kunz, Sebastian N

    2011-01-01

    Schizophrenia is associated with a significant risk of suicide. According to recent research, 10-15 % of all schizophrenic patients die by suicide. It is not uncommon that the victims show sharp force injuries, so that the forensic pathologist first has to differentiate between self-infliction and involvement of another person. The authors' case report presents a 68-year-old schizophrenic patient who committed suicide by jumping out of a window of his apartment located on the second floor after inflicting multiple stab wounds to his thoracic region. At autopsy, an older stab wound to the apex of the heart was detected. In the criminal investigation, a suicide attempt made 13 days before could be ascertained. As the patient did not want to be taken to a hospital at that time, the injury had never been examined or documented. Since there was no evidence suggesting homicide, the older stab to the heart was interpreted as a tentative injury. PMID:22039699

  16. 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

  17. 76 FR 69764 - Stab-Resistant Body Armor Standard Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-09

    ...The National Institute of Justice (NIJ) and the National Institute of Standards and Technology (NIST) are jointly hosting a workshop focused on the NIJ Stab-resistant Body Armor Standard, and the discussion is directed toward manufacturers, certification bodies, and test laboratories. This workshop is being held specifically to discuss with interested parties recent progress made toward the......

  18. Class characteristics of serrated knife stabs to cartilage.

    PubMed

    Pounder, Derrick J; Cormack, Lesley; Broadbent, Elizabeth; Millar, John

    2011-06-01

    A total of 136 stab wounds were made in cartilage with 8 serrated knives and 72 stabs with 4 nonserrated knives. The walls of the stab track were documented by photography, cast with dental impression material, and the casts photographed. Staining the translucent cartilage surface with blue or green food dye improved photography. Serrated blades produced striations on cartilage in all stabbings. Patterns of blade serration beyond the broad categories of coarse and fine were recognizable. The overall pattern of striations was "irregularly regular." The distance between the blade-spine wound end and the first serration striation is a class characteristic of the knife which produced the defect, as are distances to the subsequent serration striations, which become ever close together and eventually merge near the blade-edge wound end. Serrated knives may be ground (scalloped) on either the left side or the right side of the blade and this class characteristic is identifiable from the walls of the wound track, on which the scalloped blade surface produces broad ridges and narrow striation valleys, with a reverse image on the opposing wound wall. A drop point serrated blade consistently produced an additional oblique mark angled from the blade-spine wound end, accurately reflecting the shape of the blade tip, and representing a chatter mark. PMID:20407362

  19. 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

    ... 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 (2000... bodies and (2) test laboratories with experience in programs for similar types of personal...

  20. [Forensic medical evaluation of stab-incised wounds caused by knives with point defects].

    PubMed

    Krupin, K N; Leonov, S V

    2011-01-01

    The present experimental study allowed to characterize specific signs of stab-incised wounds caused by knives with operational point defects. Diagnostic coefficients calculated for these macro- and microscopic features facilitate differential diagnostics of the injuries and make it possible to identify a concrete stabbing/cutting weapon with which the wound was inflicted.. PMID:21866847

  1. 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. PMID:21371835

  2. 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

  3. [Current management of stab wounds to the colon].

    PubMed

    Peycru, T; Avaro, J P; Biance, N; Tardat, E; Balandraud, P

    2006-06-01

    Stab wounds to the colon are a frequent surgical emergency. Local wound exploration under local anaesthesia is not required systematically. We recommend surveillance based on clinical observation and laboratory testing to detect peritoneal signs. If progression of symptoms is suspected, diagnostic peritoneal lavage (DPL) should be performed. Immediate surgical exploration is indicated in two cases, i.e., generalized peritonitis and haemodynamic instability due to internal bleeding. The preferred repair technique is direct suture or resection followed by a handsewn or mechanical anastomosis. The morbidity, cost and social consequences of colostomy must be taken into account. It should be considered as a salvage procedure for patients in critical condition or extensive colonic injury. PMID:16924827

  4. Do Patients with Penetrating Abdominal Stab Wounds Require Laparotomy?

    PubMed Central

    Sanei, Behnam; Mahmoudieh, Mohsen; Talebzadeh, Hamid; Shahabi Shahmiri, Shahab; Aghaei, Zahra

    2013-01-01

    Background The optimal management of hemodynamically stable asymptomatic patients with anterior abdominal stab wounds (AASWs) remains controversial. The goal is to identify and treat injuries in a safe cost-effective manner. Common evaluation strategies are local wound exploration (LWE), diagnostic peritoneal lavage (DPL), serial clinical assessment (SCAs) and computed tomography (CT) imaging. Making a decision about the right time to operate on a patient with a penetrating abdominal stab wound, especially those who have visceral evisceration, is a continuing challenge. Objectives Until the year 2010, our strategy was emergency laparotomy in patients with penetrating anterior fascia and those with visceral evisceration. This survey was conducted towards evaluating the results of emergency laparotomy. So, better management can be done in patients with penetrating abdominal stab wounds. Patients and Methods This retrospective cross-sectional study was performed on patients with abdominal penetrating trauma who referred to Al- Zahra hospital in Isfahan, Iran from October 2000 to October 2010. It should be noted that patients with abdominal blunt trauma, patients under 14 years old, those with lateral abdomen penetrating trauma and patients who had unstable hemodynamic status were excluded from the study. Medical records of patients were reviewed and demographic and clinical data were collected for all patients including: age, sex, mechanism of trauma and the results of LWE and laparotomy. Data were analyzed with PASW v.20 software. All data were expressed as mean ± SD. The distribution of nominal variables was compared using the Chi-squared test. Also, diagnostic index for LWE were calculated. A two-sided P value less than 0.05 was considered to be statistically significant. Results During the 10 year period of the study, 1100 consecutive patients with stab wounds were admitted to Al-Zahra hospital Isfahan, Iran. In total, about 150 cases had penetrating traumas in

  5. Changing trends in the pattern and outcome of stab injuries at a North London hospital

    PubMed Central

    Nair, Manojkumar S; Uzzaman, Mohammed M; Al-Zuhir, Naail; Jadeja, Ashok; Navaratnam, Romi

    2011-01-01

    Objective: To study the incidence, pattern and outcome of stab injuries attending a North London Teaching Hospital over a 3-year (2006-2008) period. Materials and Methods: A retrospective review of collected data from the Hospital database was conducted. The database contains comprehensive medical records for all patients attended by the trauma team for deliberate stab injuries. It is updated by the surgical team after each admission. All patients with deliberate penetrating injury who were attended by the service between 1 January 2006 and 31 December 2008 were identified. Patients who died in the prehospital phase, those managed exclusively by the emergency department and limb injuries without vascular compromise were excluded from the study. Results: Six hundred and nineteen patients with stab injuries (following knife crime) from North London attended the Hospital in the above period. One hundred and thirty-seven paients required surgical admission. Two were cases of self-inflicted knife injuries. Over the 3-year period the percentage of victims below 20 years of age is increasing. Ninety-three percent of knife crime occured between 6 pm and 6 am; recently moving toward week days from weekend period. Conclusions: The overall rate of penetrating injuries (stab injuries) is slowly declining. Timely cardiothoracic support facility is vital in saving lives with major cardiac stab injuries. Although alcohol drinking restriction has been lifted, most cases of stabbings are still occurring out-of-hours when surgical personnel are limited. PMID:22090737

  6. Spinning-turbine-fragment impacts on casing models. Final report. [PWR; BWR

    SciTech Connect

    Wilbeck, J.S.

    1983-07-01

    Ten 1/11-scale model turbine-missile-impact tests were conducted at the Naval Air Propulsion Center under the supervision of Southwest Research Institute. These tests were conducted in support of the EPRI program to assess turbine-missile effects in nuclear plant design. The objective of the tests was to determine the effects of missile spin, blade crush, and target edge conditions on the impact of turbine disk fragments on the steel casing. The burst of a modified gas-turbine rotor in a high-speed spin chamber provided three missiles with the proper rotational and translational velocities of actual steam-turbine fragments. Tests of unbladed, spinning missiles were compared with previous tests of unbladed, nonspinning missiles. The total residual energy of the spinning missiles was the same as that of the nonspinning missiles launched in a piercing orientation. Tests with bladed missiles showed that for equal burst speeds, the residual energy of bladed missiles is less than that of unbladed missiles.

  7. Abdominal stab wounds: self-inflicted wounds versus assault wounds.

    PubMed

    Venara, Aurélien; Jousset, Nathalie; Airagnes, Guillaume; Arnaud, Jean-Pierre; Rougé-Maillart, Clotilde

    2013-05-01

    Intentional penetrating wounds, self inflicted or inflicted by others, are increasingly common. As a result, it can be difficult for the forensic examiner to determine whether the cause is self-inflicted or not. This type of trauma has been studied from a psychological perspective and from a surgical perspective but the literature concerning the forensic perspective is poorer. The objective of this study was to compare the epidemiology of abdominal stab wounds so as to distinguish specific features of each type. This could help the forensic scientist to determine the manner of infliction of the wound. We proposed a retrospective monocentric study that included all patients with an abdominal wound who were managed by the visceral surgery department at Angers University Hospital. Demographic criteria, patient history, circumstances and location of the wound were noted and compared. A comparison was drawn between group 1 (self inflicted wound) and group 2 (assault). This study showed that the only significant differences are represented by the patient's prior history and the circumstances surrounding the wound, i.e. the scene and time of day. In our study, neither the site, nor the injuries sustained reveal significant clues as to the origin of the wound. According to our findings, in order to determine the cause, the forensic examiner should thus carefully study the circumstances and any associated injuries. PMID:23622473

  8. Costs of gunshot and cut/stab wounds in the United States, with some Canadian comparisons.

    PubMed

    Miller, T R; Cohen, M A

    1997-05-01

    This article estimates the costs of U.S. gunshot and cut/stab wound by intent. It also compares U.S. to Canadian gunshot experience. Incidence data are from published sources, the National Hospital Ambulatory Medical Care Survey (NHAMCS), and cause-coded emergency department discharge and hospital discharge data systems. Medical care payments and lost earnings per case come from National Crime Survey data, a literature review, and weighting of costs by diagnosis from Databook on Nonfatal Injury-Incidence. Costs, and Consequences by Miller et al. (The Urban Institute Press, Washington, DC. 1995) with the diagnosis distribution of penetrating injuries from the discharge data systems. Quality of life losses are estimated primarily from jury awards to penetrating injury victims. In 1992, gunshots killed 37,776 Americans; cut/stab wounds killed 4095. Another 134,000 gunshot survivors and 3,100,000 cut/stab wound survivors received medical treatment. Annually, gunshot wounds cost an estimated U.S. $126 billion. Cut/stab wounds cost another U.S. $51 billion. The gunshot and cut/stab totals include U.S. $40 billion and U.S. $13 billion respectively in medical, public services, and work-loss costs. Across medically treated cases, costs average U.S. $154,000 per gunshot survivor and U.S. $12,000 per cut/stab survivor. Gunshot wounds are more than three times as common in the U.S. than in Canada, which has strict handgun control. With the same quality of life loss per victim, gunshot costs per capita are an estimated U.S. $495 in the U.S. vs U.S. $180 in Canada. Per gun, however, the costs are higher in Canada, Gunshot wound rates rise linearly with gun ownership. PMID:9183471

  9. 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

  10. 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. PMID:24664098

  11. A stab in the back with a screwdriver: a case report

    PubMed Central

    Bhutta, Mohammed A; Dunkow, Paul D; Lang, Derick M

    2008-01-01

    Background Stabbings infrequently produce spinal injury. However, the use weapons other than blades can overcome this natural defence barrier. Case Presentation We present a spinal injury produced by a screwdriver, its management and a review of the literature. Conclusion This case highlights the need for clinical vigilance, including in those who appear stable and a senior multidisciplinary approach to each individual case. PMID:19014454

  12. 76 FR 35024 - National Institute of Justice Stab-Resistant Body Armor Standard Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-15

    ...The National Institute of Justice (NIJ) and the National Institute of Standards and Technology (NIST) are jointly hosting workshop focused on the NIJ Stab-Resistant Body Armor Standard. It is anticipated that the discussion at the workshop will be directed primarily toward manufacturers, certification bodies, and test laboratories. NIJ and NIST are hosting this workshop specifically to discuss......

  13. A Method for Cell Culture and Maintenance of Ammonia-Oxidizing Archaea in Agar Stab.

    PubMed

    Chu, Yeon-Jin; Lee, Jin-Young; Shin, So-Ra; Kim, Geun-Joong

    2015-12-01

    Ammonia oxidizing archaea (AOA) are predominantly found and closely linked with geochemical cycling of nitrogen in non-extreme habitats. However, these strains have mainly been investigated using liquid cultures of enriched cells. Here, we provide an agar stab as a simple and reliable means of cultivating and maintaining AOA. PMID:26543273

  14. A rare suicidal case of a ten-year-old child stabbing himself in the throat.

    PubMed

    Hasekura, H; Fukushima, H; Yonemura, I; Ota, M

    1985-10-01

    A rare case is reported of a ten-year-old boy who committed suicide by stabbing himself in the throat with a pointed knife. Possibility of an accidental injury was excluded by the autopsy findings; suspicion of a homicide by his father was cleared through the deposition of his sister. The reason of suicide was attributed directly to his father's severe scolding and indirectly to his mother's death two years before. PMID:4067552

  15. [Recurrent ventricular tachycardia as a late complication of a cardiac stab wound].

    PubMed

    Niedziela, Justyna; Wozakowska-Kapłon, Beata; Dziubek, Katarzyna; Jaskulska-Niedziela, Elzbieta; Włosowicz, Monika

    2010-01-01

    We present a case of a 55-year-old male who suffered from a cardiac stab wound in his youth and 38 years later developed unstable sustained ventricular tachycardia. Imaging showed presence of a scarf of myocardium which probably caused the arrhythmia. Arrhythmia was successfully controlled using combined treatment with pharmacotherapy and cardioverter-defibrillator implantation. Relapses of ventricular tachycardia treated by appropriate interventions of cardioverter-defibrillator occurred when the patient stopped pharmacotherapy and experienced great psychic stress. PMID:20131201

  16. Stabbing and safeguarding in children and young people: a Pan-London service evaluation and audit

    PubMed Central

    Apps, John R; Williams, Carrie; McGuinness, Anne; Gabbie, Susie; Sutcliffe, Alastair G

    2013-01-01

    Objectives To characterize paediatric presentations of stabbing to emergency departments across London and to audit existing referral rates to the police and social services against the new standard set by the General Medical Council. Design Retrospective multi-centre service evaluation/audit. Setting All emergency departments within London. Participants Patients under 18 years of age presenting to emergency departments with non-accidental stabbing between 1 April 2007 and 30 April 2009. Main outcome measures Patient age, nature of assault, assailant, injuries and management. Rates of documented referral to police and social services, as mandated by GMC guidance. Results A total of 381 presentations were identified from 20 out of the 32 hospitals in London, 160 of whom were less than 16 years old. The majority were seen only by emergency department staff and only a minority (28%) were admitted. Three died in the departments. A knife was the commonest weapon and the limbs the most common site of injury. Referrals to police were documented in only 30% of patients (43% if <16 years old) and to social services in 16% (31% if <16 years old) of those discharged. In the majority, there was no documentation (police 64%, social services 79%). Conclusions A significant number of paediatric stabbings present to emergency departments across London. The majority of these are discharged directly from departments. Of those discharged, documentation regarding referral rates to Police and Social Services was poor, and documented referral rates low. This study covered a period prior to the introduction of new General Medical Council guidance and a repeat audit to assess subsequent documented referrals is required. PMID:23885300

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

    PubMed

    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. PMID:22832283

  18. 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.

  19. Prehospital ultrasound detects pericardial tamponade in a pregnant victim of stabbing assault.

    PubMed

    Byhahn, Christian; Bingold, Tobias M; Zwissler, Bernhard; Maier, Marcus; Walcher, Felix

    2008-01-01

    The development of handheld, portable ultrasound devices has enabled the use of this diagnostic tool also in the out-of-hospital environment. We report on a pregnant teenager who was found haemodynamically unstable after a stab assault. When she suffered cardiac arrest shortly thereafter, diagnosis of cardiac tamponade was made by portable ultrasound, and immediate pericardiocentesis was performed by the emergency physician. While her baby died after emergency Caesarean section, the teenager survived after thoracotomy and prolonged resuscitation without neurological sequelae. PMID:17716805

  20. 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

  1. Quantification of forces required for stabbing with screwdrivers and other blunter instruments.

    PubMed

    Parmar, Kiran; Hainsworth, Sarah Victoria; Rutty, Guy Nathan

    2012-01-01

    In the UK, stabbing is the most common cause of homicide. The weapons used include knives, swords, screwdrivers and glass shards. Quantifying the exact force used in a stabbing incident is considered to be a difficult area due to the large number of variables present, such as sharpness of weapon, angle of attack and relative movements of the people involved. Having quantifiable data would allow a forensic pathologist to make a more informed decision when it comes to answering the commonly posed question in court "what was the degree of force involved in the stabbing incident?" The answer to this question is considered significant in determining an alleged assailant's intent to cause harm. This paper presents results of the first detailed study relating geometry of screwdrivers to the forces required for penetration. Additionally, a range of other blunt weapons such as pens and chisels have also been studied. A silicone rubber-foam analogue has been used as the main skin simulant owing to it having similar mechanical properties to that of human skin and giving highly repeatable results. Different screwdrivers of varying shape and size have been tested (i.e. slotted, Phillips, posidriv and Torx), along with other implements including chisels and pens. The weapon geometry was characterised and related to the peak force required for penetration. Our results show that there is a direct correlation between the cross-sectional area of a screwdriver head and the amount of force required for penetration. Screwdrivers with larger cross-sectional areas require a significantly greater force to penetrate (forces in the region of 100-120 N) but "sharper" slotted screwdrivers penetrate with much lower forces (~30 N). The forces required for penetrating the rubber-foam analogue with screwdrivers are higher than for "sharp" knives, but in some cases similar to the forces required for stabbing with "blunt" knives. For the other weapons such as chisels and biros, the force required

  2. A review of stab wound injuries at a tertiary trauma centre in Singapore: are self-inflicted ones less severe?

    PubMed Central

    Leow, Jeffrey J; Lingam, Pravin; Lim, Vanessa W; Go, Karen TS; Chiu, Ming Terk; Teo, Li Tserng

    2016-01-01

    INTRODUCTION In Singapore, as strict laws are a strong deterrent against armed violence, little is known about the epidemiology of penetrating stab wound injuries. Our study aimed to investigate the epidemiology of stab wound injuries at a major trauma centre in Singapore and determine if there was a difference in severity between self-inflicted stab wound (SI) injuries and those inflicted by others (IO). METHODS We retrospectively reviewed all penetrating injuries at Tan Tock Seng Hospital, and identified and categorised all stab wound injuries as SI or IO. Basic demographic information, injury severity characteristics and outcome data were compared between these two groups. A review of all mortalities was performed, including recording the causes of death. RESULTS Between 2005 and 2010, there were a total of 149 stab wound injuries, of which 24 (16.1%) were SI and 125 (83.9%) were IO injuries. Patients tended to be young (mean age 34.1 ± 14.2 years). The mean Injury Severity Score was significantly different between the SI and IO groups (8.8 ± 6.5 vs. 12.3 ± 8.1; p = 0.03). In both groups, the majority underwent an operative procedure (83.3% vs. 85.6%) and had an average hospital stay of four days. CONCLUSION The study confirms our hypothesis that SI injuries tend to be less severe than IO injuries and are more likely to occur at home rather than at a public area. This finding may be useful in the triage of patients with stab wound injuries. PMID:26831311

  3. Carotid artery dissection due to elongated styloid process: a self-stabbing phenomenon.

    PubMed

    Razak, Anmar; Short, Jody L; Hussain, Syed I

    2014-01-01

    Elongated styloid process (ESP) is an anatomical variant that has been described as the cause of Eagle syndrome. Until recently, the styloid process has not been appreciated as a significant contributor to carotid artery dissection (CAD), which is not part of Eagle syndrome. We present a case of a 41-year-old male who presented with acute right middle cerebral artery occlusion and was found to have ESP projecting to and abutting the lateral wall of a dissected right internal carotid artery (ICA). Forced sustained head turning with maximal muscle contraction was the initiating event driving the styloid process into the wall of the ICA in a manner that can be likened to being stabbed with a pointed object. Knowing the association between ESP, Eagle syndrome, and CAD shall lead to increased awareness and appropriate diagnosis and treatment. PMID:23163559

  4. Lethal penetrating stab injury to the vertebral artery: A case report with review of literature

    PubMed Central

    Sarkari, Avijit; Singh, Pankaj K.; Mahapatra, Ashok K.

    2016-01-01

    The vertebral arteries are rarely injured in penetrating neck trauma due to their deep location in the foramen transversarium. These injuries in isolation are not associated with neurological deficits or ischemic changes on radiology as the collaterals are usually sufficient. We report a case of fatal unilateral vertebral artery stab injury leading to bilateral cerebellar and brainstem infarction. The carotid Doppler ruled out the presence of any carotid artery injury. Life-threatening injuries are possible in the presence of hypoplastic contralateral vertebral artery or inadequate flow from the anterior circulation not making up for the deficit. This emphasizes that thorough evaluation and timely management of suspected injuries to even a single vertebral artery should be undertaken. PMID:27366277

  5. Complex suicide by self-stabbing with subsequent drowning in the sea.

    PubMed

    Kaliszan, Michał; Karnecki, Karol; Tomczak, Ewa; Gos, Tomasz; Jankowski, Zbigniew

    2013-09-01

    The paper presents a unique case of a complex suicide committed by a young man, mostly probably triggered by a disappointment in love. The uniqueness of the suicide lies in the fact that the victim inflicted several deep stab wounds on himself, in the chest and abdomen, while standing partly submerged in the sea and, having done so, he dropped and disappeared in the water. The postmortem examination showed, apart from deep wounds in the trunk, characteristics of drowning that manifested itself in the form of aqueous emphysema of the lungs. Suicide was clearly determined on the basis of the circumstances preceding death, the location, and arrangement of the trunk wounds and the testimony given by a witness of the incident. The circumstances preceding the suicidal act clearly suggest an underlying undiagnosed mental disorder. PMID:23866029

  6. 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

  7. Lethal penetrating stab injury to the vertebral artery: A case report with review of literature.

    PubMed

    Sarkari, Avijit; Singh, Pankaj K; Mahapatra, Ashok K

    2016-01-01

    The vertebral arteries are rarely injured in penetrating neck trauma due to their deep location in the foramen transversarium. These injuries in isolation are not associated with neurological deficits or ischemic changes on radiology as the collaterals are usually sufficient. We report a case of fatal unilateral vertebral artery stab injury leading to bilateral cerebellar and brainstem infarction. The carotid Doppler ruled out the presence of any carotid artery injury. Life-threatening injuries are possible in the presence of hypoplastic contralateral vertebral artery or inadequate flow from the anterior circulation not making up for the deficit. This emphasizes that thorough evaluation and timely management of suspected injuries to even a single vertebral artery should be undertaken. PMID:27366277

  8. Spinal Cord Injury Caused by Stab Wounds: Incidence, Natural History, and Relevance for Future Research.

    PubMed

    McCaughey, Euan J; Purcell, Mariel; Barnett, Susan C; Allan, David B

    2016-08-01

    Spinal cord injury caused by stab wounds (SCISW) results from a partial or complete transection of the cord, and presents opportunities for interventional research. It is recognized that there is low incidence, but little is known about the natural history or the patient's suitability for long-term clinical outcome studies. This study aims to provide population-based evidence of the demographics of SCISW, and highlight the issues regarding the potential for future research. The database of the Queen Elizabeth National Spinal Injuries Unit (QENSIU), the sole center for treating SCI in Scotland, was reviewed between 1994 and 2013 to ascertain the incidence, demographics, functional recovery, and mortality rates for new SCISW. During this 20 year period, 35 patients with SCISW were admitted (97.1% male, mean age 30.0 years); 31.4% had a cervical injury, 60.0% had a thoracic injury, and 8.6% had a lumbar injury. All had a neurological examination, with 42.9% diagnosed as motor complete on admission and 77.1% discharged as motor incomplete. A total of 70.4% of patients with an American Spinal Injury Association Impairment Scale (AIS) level of A to C on admission had an improved AIS level on discharge. Nine (25.7%) patients have died since discharge, with mean life expectancy for these patients being 9.1 years after injury (20-65 years of age). Patients had higher levels of comorbidities, substance abuse, secondary events, and poor compliance compared with the general SCI population, which may have contributed to the high mortality rate observed post-discharge. The low incidence, heterogeneous nature, spontaneous recovery rate, and problematic follow-up makes those with penetrating stab injuries of the spinal cord a challenging patient group for SCI research. PMID:26825180

  9. Fluctuations in nuclear fragmentation

    SciTech Connect

    Aranda, A.; Dorso, C.O.; Furci, V.; Lopez, J.A.

    1995-12-01

    Heavy ion collisions can be used to study the thermodynamics of hot and dense nuclear matter only if the initial mass and energy fluctuations that lead to fragmentation are of thermal origin and survive the disassembly process. If this is the case, the observed fragment multiplicity should be directly related to those initial fluctuations and to the conditions of temperature and density causing them. The feasibility of this scenario is demonstrated with a molecular dynamics study of the evolution of mass and energy fluctuations, and fluctuations of the phase-space density. First, it is verified that the fluctuations leading to fragmentation are indeed early ones. Second, it is determined that different initial conditions of density and temperature can indeed produce varying final fragment multiplicities. The {rho}-{ital T} plane is mapped to the fragment multiplicity with good precision. This mapping should be easily reproducible with existing experimental data.

  10. [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. PMID:25269165

  11. 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.

  12. Multiple severe stab wounds to chest with cuts to the ribs. Suicide or homicide?

    PubMed

    Kaliszan, Michał

    2011-01-01

    This paper presents the case of a 36-year-old man found dead in a forest near his home with multiple stab wounds on the chest and abdomen, while the chest wounds penetrated deep into the left pleural cavity and the lung parenchyma, completely cutting through the bone sections of four ribs along the channels of the wounds. In addition, a kitchen knife dug into the ground was found in the immediate vicinity of the corpse. The deceased was wearing a T-shirt with numerous clearly visible holes in places corresponding to the wounds and quite a large tear at the bottom. The post-mortem revealed 19 distinct wounds of the chest as well as a dozen or so superficial marks of cuts or pricks with a pointed tool on the torso. The findings of the police investigation suggested that shortly before death the man was in a bad mood and he had been telling his friends to prepare for his funeral, which was supposed to point to suicidal tendencies. Could, however, such numerous and heavy bodily injuries have been self-inflicted and would such a wounded person still be able to dig a knife into hard forest bed? If yes, in this case we are most probably dealing with aggressive self-destruction, a type of behavior sometimes observed in people suffering from serious mental disorders. PMID:21216377

  13. Stabbing Yourself in the Heart: A Case of Autoimmunity Gone Awry

    PubMed Central

    Vigneswaran, Hari; Parikh, Leslie; Poppas, Athena

    2015-01-01

    Within internal medicine, cardiac and neurologic pathology comprises a vast majority of patient complaints. Physicians and advanced-care practitioners must be highly educated and comfortable in the evaluation, diagnosis, and management of these entities. Chest pain accounts for millions of annual visits to the emergency room with pericarditis diagnosed in approximately four percent of patients with nonischemic chest pain. Guillain-Barre Syndrome is autoimmune polyneuropathy that often results in transient paralysis. Simultaneous diagnosis of both entities is a rare but described phenomenon. Here, we present a clinical case of GBS associated pericarditis. A fifty-five-year-old man with history of renal transplant presented with lower extremity weakness and urinary incontinence. Physical exam and diagnostic studies confirmed Guillain-Barre Syndrome. Patient subsequently developed stabbing chest pain with clinical presentation and electrocardiogram consistent with pericarditis. The patient was successfully treated for both diseases. This case highlights that although infrequent, internal medicine care providers must be cognizant of this correlation to ensure timely diagnosis and treatment. PMID:26664359

  14. Penetration of a piece of World War II rifle grenade initially suspected as a stab wound.

    PubMed

    Raul, Jean-Sébastien; Berthelon, Laurent; Tracqui, Antoine; Ludes, Bertrand

    2002-09-01

    The authors report the case of a 58-year-old man found dead by his son in the forest where he had gone to cut wood for winter. Initial examination showed an upper left laterocervical wound compatible with a stab wound. Radiography and autopsy performed the next day showed a piece of metal located in the left part of the occipital bone, associated with a half-ring fracture of the occipital bone and consequent diffuse subarachnoid hemorrhage. Death was attributed to a spinal shock after impact at the cervicocephalic junction. Investigators returned to the scene and found a few more metal elements and also a 20-cm deep and 40-cm wide crater underneath a fire the deceased had set. Army experts concluded that the metal pieces belonged to an ATM 9 antitank rifle grenade used by the U.S. Army during World War II. Death was considered accidental, the deceased having unfortunately set a fire over the grenade. PMID:12198357

  15. The spectrum of injuries resulting from posterior abdominal stab wounds: a South African experience

    PubMed Central

    Oosthuizen, GV; Clarke, DL

    2015-01-01

    Introduction The spectrum of injury associated with anterior abdominal stab wounds (SWs) is well established. The literature on the spectrum of organ injury associated with SWs to the posterior abdomen, however, is limited. Methods We reviewed our experience of 105 consecutive patients who had established indications for laparotomy managed over a 4-year period in a high volume trauma service in South Africa. Results Of the 105 patients, 97 (92%) were male and the overall mean age was 24 years. Fifty-seven patients (54%) had immediate indications for laparotomy. The remaining 48 patients (46%) initially underwent active clinical observation and the indications for laparotomy became apparent during the observation period. Of the 105 laparotomies performed, 94 (90%) were positive and 11 (10%) were negative. Of the 94 positive laparotomies, 92 were therapeutic and 2 were non-therapeutic. A total of 176 organ injuries were identified: 50 (53%) of the 94 patients sustained a single organ injury while the remaining 44 (47%) sustained multiple organ injuries. The most commonly injured organs were the colon (n=63), spleen (n=21) and kidney (n=19). Conclusions The pattern of intra-abdominal injuries secondary to SWs to the posterior abdomen is different to that seen with the anterior abdomen. Colonic injury is most commonly encountered, followed by injuries to the spleen and kidney. Clinicians must remain vigilant because of the potential for occult injuries. PMID:26263933

  16. 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. PMID:23392761

  17. 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.

  18. Magma Fragmentation

    NASA Astrophysics Data System (ADS)

    Gonnermann, Helge M.

    2015-05-01

    Magma fragmentation is the breakup of a continuous volume of molten rock into discrete pieces, called pyroclasts. Because magma contains bubbles of compressible magmatic volatiles, decompression of low-viscosity magma leads to rapid expansion. The magma is torn into fragments, as it is stretched into hydrodynamically unstable sheets and filaments. If the magma is highly viscous, resistance to bubble growth will instead lead to excess gas pressure and the magma will deform viscoelastically by fracturing like a glassy solid, resulting in the formation of a violently expanding gas-pyroclast mixture. In either case, fragmentation represents the conversion of potential energy into the surface energy of the newly created fragments and the kinetic energy of the expanding gas-pyroclast mixture. If magma comes into contact with external water, the conversion of thermal energy will vaporize water and quench magma at the melt-water interface, thus creating dynamic stresses that cause fragmentation and the release of kinetic energy. Lastly, shear deformation of highly viscous magma may cause brittle fractures and release seismic energy.

  19. Forest Fragmentation

    EPA Science Inventory

    This indicator describes forest fragmentation in the contiguous United States circa 2001. This information provides a broad, recent picture of the spatial pattern of the nation’s forests and the extent to which they are being broken into smaller patches and pierced or interspe...

  20. [Stab wounds of the hand and forearm due to Kuluna in Kinshasa (Democratic Republic of Congo): types of injuries and treatment].

    PubMed

    Kibadi, K; Portaels, F; Pichot, Y; Kapinga, M; Moutet, F

    2015-01-01

    Democratic Republic of Congo (DRC), a particular form of juvenile delinquency and insecurity intensifies in the city of Kinshasa. This is the phenomenon Kuluna. It is organized gangs equipped with machetes and other weapons. The main objective of this study is to know the phenomenon Kuluna and describe the upper limb injuries caused by machetes, while insisting on the specifics of the management of these lesions in our communities. This retrospective descriptive study examines 14 cases of wounds of the hand and forearm due to stab phenomenon Kuluna, in Kinshasa. It covers the period from 1 November 2010 to 1 November 2013. Among the 14 patients with lesions in the hand and forearm admitted and treated at the Unit of Plastic Reconstructive and Aesthetic Surgery, Hand Surgery and Burns, University Clinics of Kinshasa to attacks due to the phenomenon Kuluna. We have 11 men and 3 women. The average age was 33, 5 years (extremes of 21 and 56 years). The right upper limb is reached that the left upper limb, respectively 12 patients and 2 patients. The lesions are localized to the wrist in the majority of cases (10 patients) in the palm of hand and in 3 patients in the fingers in 1 patient. The palmar surface is reached (10 cases) and the dorsal (4 cases). Zone 5 of the International Classification of flexor and Zone 8 topographic classification extensors at hand are the predilection sites of lesions respectively the palmar surface (6 out of 10) and the dorsal (2 case 4). The median nerve at the wrist is cut in half the cases. On bone lesions localized to the forearm, we observed a high incidence of fracture of the ulna (62.5%). The treatment begins with the stabilization of bone pieces, gestures revascularization and nerve sutures and suture tendon and finally skin coverage. Rehabilitation was mandatory, she supervises the actions of repair and it continues until the recovery of function. PMID:26837110

  1. [The morphological features of stab-and-slash skin wounds inflicted by the blades with differently shaped tips through the multilayer barrier].

    PubMed

    Sarkisian, B A; Fedorov, S Iu

    2014-01-01

    The objective of the present work was to study the shape, size, and morphological features of stab-and-slash skin wounds inflicted by the blades with differently shaped tips taking into consideration the direction of stab through multiple garments (1, 2, and 3 layers). The injuries were inflicted by kitchen knives having the blades of practically identical length and width but differently shaped tips. A total of 480 skin wounds and 720 damaged cloth specimens were available for the examination. The analysis of the data obtained revealed differences between morphological features of the skin wounds. Injuries to the skin unprotected by the cloths had different shape and length of the edge and end portions depending on the shape of the blade tip and the direction of the stab. The length of all wound inflicted through the barrier decreased as the number of layers increased. The wounds had the linear shape, their contusion collar and flattened area became narrower; the shape of the back edges of the wounds inflicted through a three-layer barrier altered. It is concluded that the result of the present study may be useful for the improvement of diagnostics of stab-and-slash skin wounds. PMID:25269167

  2. Perturbative fragmentation

    SciTech Connect

    Kopeliovich, B. Z.; Pirner, H.-J.; Potashnikova, I. K.; Schmidt, Ivan; Tarasov, A. V.

    2008-03-01

    The Berger model of perturbative fragmentation of quarks to pions is improved by providing an absolute normalization and keeping all terms in a (1-z) expansion, which makes the calculation valid at all values of fractional pion momentum z. We also replace the nonrelativistic wave function of a loosely bound pion by the more realistic procedure of projecting to the light-cone pion wave function, which in turn is taken from well known models. The full calculation does not confirm the (1-z){sup 2} behavior of the fragmentation function (FF) predicted in [E. L. Berger, Z. Phys. C 4, 289 (1980); Phys. Lett. 89B, 241 (1980] for z>0.5, and only works at very large z>0.95, where it is in reasonable agreement with phenomenological FFs. Otherwise, we observe quite a different z-dependence which grossly underestimates data at smaller z. The disagreement is reduced after the addition of pions from decays of light vector mesons, but still remains considerable. The process dependent higher twist terms are also calculated exactly and found to be important at large z and/or p{sub T}.

  3. 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

  4. Invasive hyphal growth in Wangiella dermatitidis is induced by stab inoculation and shows dependence upon melanin biosynthesis.

    PubMed

    Brush, L; Money, N P

    1999-12-01

    Stab inoculation of agar medium with yeasts of the human pathogen Wangiella dermatitidis resulted in induction of invasive hyphae. Mechanical penetration of agar was indicated by the observation that an increase in medium gel strength slowed the rate of substrate invasion. A melanized wild-type strain (8656) exhibited much faster invasive growth through 2-8% agar than three melanin-deficient mutants. Inhibition of melanin synthesis in strain 8656 using tricyclazole resulted in a decrease in its rate of invasive growth, while scytalone restored melanin synthesis in the albino mel3 strain and boosted its rate of invasive growth. Earlier research established that cellular melanization is also associated with invasive hyphal growth in the mouse brain, and infections with strain 8656 are invariably lethal. Together, these in vitro and in vivo data indicate that biomechanical characteristics of fungi may be important determinants of virulence and disease progression in human and animal mycoses. PMID:10669584

  5. Undetected Aorto-RV Fistula With Aortic Valve Injury and Delayed Cardiac Tamponade following a Chest Stab Wound: A Case Report

    PubMed Central

    Esfahanizadeh, Jamil; Abbasi Tashnizi, Mohammad; Moeinipour, Ali Asghar; Sepehri Shamloo, Alireza

    2013-01-01

    Introduction Although a few patients will survive after penetrating cardiac injuries, some of them may have unnoticeable intracardiac injuries. The combination of aorto-right ventricular fistula with aortic valve injury is rare. Case Presentation A 19 year-old man referred with an aorto-right ventricular fistula accompanied with aortic regurgitation and delayed tamponade following a stab in the chest. The patient was scheduled for fistula repair, aortic valve replacement and pericardectomy two months after trauma. Conclusions To prevent missing intracardiac injury and also late cardiac injury complications, in all pericordial stab wounds, serial clinical examinations and serial echocardiography should be performed. In addition, cardiac injuries should be repaired during the same hospital stay. PMID:24350161

  6. Optimization of Cry3A Yields in Bacillus thuringiensis by Use of Sporulation-Dependent Promoters in Combination with the STAB-SD mRNA Sequence

    PubMed Central

    Park, Hyun-Woo; Ge, Baoxue; Bauer, Leah S.; Federici, Brian A.

    1998-01-01

    The insecticidal activity of Bacillus thuringiensis strains toxic to coleopterous insects is due to Cry3 proteins assembled into small rectangular crystals. Toxin synthesis in these strains is dependent primarily upon a promoter that is active in the stationary phase and a STAB-SD sequence that stabilizes the cry3 transcript-ribosome complex. Here we show that significantly higher yields of Cry3A can be obtained by using dual sporulation-dependent cyt1Aa promoters to drive the expression of cry3Aa when the STAB-SD sequence is included in the construct. The Cry3A yield per unit of culture medium obtained with this expression system was 12.7-fold greater than that produced by DSM 2803, the wild-type strain of B. thuringiensis from which Cry3Aa was originally described, and 1.4-fold greater than that produced by NB176, a mutant of the same strain containing two or three copies of cry3Aa, which is the active ingredient of the commercial product Novodor, used for control of beetle pests. The toxicities of Cry3A produced with this construct or the wild-type strain were similar when assayed against larvae of the cottonwood leaf beetle, Chrysomela scripta. The volume of Cry3A crystals produced with cyt1Aa promoters and the STAB-SD sequence was 1.3-fold that of typical bipyramidal Cry1 crystals toxic to lepidopterous insects. The dual-promoter/STAB-SD system offers an additional method for potentially improving the efficacy of insecticides based on B. thuringiensis. PMID:9758822

  7. 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.

  8. Explosive fragmentation

    NASA Astrophysics Data System (ADS)

    Vledouts, Alexandre; Graña-Otero, José; Quinard, Joel; Vandenberghe, Nicolas; Villermaux, Emmanuel

    2013-11-01

    We report on an experiment consisting in forcing the fast radial expansion of a spherical liquid shell. The shell is formed by the capillary pinch off of a water thin annular jet surrounding a jet of reactive gaseous mixture at ambient pressure. The encapsulated gas in the resulting water bubble is a mixture of Hydrogen and Oxygen in controlled relative proportions, which is ignited by a laser plasma aimed at the center of the bubble. The strongly exothermic combustion of the mixture induces the expansion of the hot burnt gas, pushing the shell radially outwards in a violently accelerated motion. That motion triggers the instability of the shell, developing thickness modulations ultimately piercing it in a number of holes. The capillary retraction of the holes concentrates the liquid constitutive of the shell into a web of ligaments, whose breakup leads to stable drops. We document the overall process, from the kinematics of the shell initial expansion, to the final drops size distribution as a function of the composition of the gas mixture and bubble shell thickness.

  9. 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

  10. 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

    2015-04-01

    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

  11. 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.

  12. 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.

  13. Selectable fragmentation warhead

    SciTech Connect

    Bryan, C.S.; Paisley, D.L.; Montoya, N.I.; Stahl, D.B.

    1992-12-31

    This report discusses a selectable fragmentation warhead which is 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.

  14. Molecular energies from an incremental fragmentation method

    NASA Astrophysics Data System (ADS)

    Meitei, Oinam Romesh; Heßelmann, Andreas

    2016-02-01

    The systematic molecular fragmentation method by Collins and Deev [J. Chem. Phys. 125, 104104 (2006)] has been used to calculate total energies and relative conformational energies for a number of small and extended molecular systems. In contrast to the original approach by Collins, we have tested the accuracy of the fragmentation method by utilising an incremental scheme in which the energies at the lowest level of the fragmentation are calculated on an accurate quantum chemistry level while lower-cost methods are used to correct the low-level energies through a high-level fragmentation. In this work, the fragment energies at the lowest level of fragmentation were calculated using the random-phase approximation (RPA) and two recently developed extensions to the RPA while the incremental corrections at higher levels of the fragmentation were calculated using standard density functional theory (DFT) methods. The complete incremental fragmentation method has been shown to reproduce the supermolecule results with a very good accuracy, almost independent on the molecular type, size, or type of decomposition. The fragmentation method has also been used in conjunction with the DFT-SAPT (symmetry-adapted perturbation theory) method which enables a breakdown of the total nonbonding energy contributions into individual interaction energy terms. Finally, the potential problems of the method connected with the use of capping hydrogen atoms are analysed and two possible solutions are supplied.

  15. 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. PMID:18752892

  16. 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.

  17. Universality of fragment shapes.

    PubMed

    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

  18. 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

  19. 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.

  20. 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.

  1. Fragmentation in the First Galaxies

    NASA Astrophysics Data System (ADS)

    Safranek-Shrader, Chalence; Bromm, Volker; Milosavljević, Miloš

    2010-11-01

    Motivated by recent simulations of galaxy formation in which protogalaxies acquire their baryonic content through cold accretion, we study the gravitational fragmentation of cold streams flowing into a typical first galaxy. We use a one-zone hydrodynamical model to examine the thermal evolution of the gas flowing into a 108 M sun dark matter halo at redshift z = 10. The goal is to gain an understanding of the expected fragmentation mass scale and thus the characteristic mass of the first population of stars to form by shock fragmentation. Our model accurately describes the chemical and thermal evolution of the gas as we are specifically concerned with how the chemical abundances and initial conditions of the low-density, metal-enriched, cold accretion streams that pass an accretion shock alter the cooling properties and tendency to fragment in the post-shock gas. Cold accretion flows are not shock heated at the virial radius but instead flow along high-baryonic-density filaments of the cosmic web and penetrate deep into the host halo of the protogalaxy. In this physical regime, if molecular cooling is absent because of a strong Lyman-Werner background, we find there to be a sharp drop in the fragmentation mass at a metallicity of Z ~ 10-4 Z sun. If, however, H2 and HD molecules are present, they dominate the cooling at T < 104 K, and metallicity then has no effect on the fragmentation properties of the cold stream. For a solar abundance pattern of metallicity, O is the most effective metal coolant throughout the evolution, while for a pair instability supernova (PISN) metallicity yield, Si+ is the most effective coolant. PISN abundance patterns also exhibit a slightly smaller critical metallicity. Dust grains are not included in our chemical model, but we argue that their inclusion would not significantly alter the results. We also find that this physical scenario allows for the formation of stellar clusters and large, 104 M sun bound fragments, possibly the

  2. FRAGMENTATION IN THE FIRST GALAXIES

    SciTech Connect

    Safranek-Shrader, Chalence; Bromm, Volker; Milosavljevic, Milos

    2010-11-10

    , 10{sup 4} M{sub sun} bound fragments, possibly the precursors to globular clusters and supermassive black holes. Finally, we conclude that the usual assumption of isobaricity for galactic shocks breaks down in gas of a sufficiently high metallicity, suggesting that metal cooling leads to thermal instabilities.

  3. 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…

  4. 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.

  5. Selectable fragmentation warhead

    SciTech Connect

    Bryan, C.S.; Paisley, D.L.; Montoya, N.I.; Stahl, D.B.

    1993-07-20

    A selectable fragmentation warhead is described comprising: a case having proximal and distal ends; a fragmenting plate mounted in said distal end of said casing; first explosive means cast adjacent to said fragmenting plate for creating a predetermined number of fragments from said fragmenting plate; three or more first laser-driven slapper detonators located adjacent to said first explosive means for detonating said first explosive means in a predetermined pattern; smoother-disk means located adjacent to said first means for accelerating said fragments; second explosive means cast adjacent to said smoother-disk means for further accelerating said fragments; at least one laser-driven slapper detonators located in said second explosive means; a laser located in said proximal end of said casing; optical fibers connecting said laser to said first and second laser-driven slapper detonators; and optical switch means located in series with said optical fibers connected to said plurality of first laser-driven slapper detonators for blocking or passing light from said laser to said plurality of first laser-driven slapper detonators.

  6. 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

  7. 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. PMID:25790025

  8. Stratification of gallstone fragments: the key to more effective fragmentation.

    PubMed

    Alderfer, J T; Laufer, I; Wisniewski, F; Malet, P F

    1992-04-01

    During previous experiments with in vitro fragmentation in a simulated gallbladder, we noticed that stone fragments tended to stratify with the dust and smaller fragments settled to the dependent portion, while the larger fragments settled on top. We reviewed the oral cholecystogram (OCG) of 10 patients examined 6 months following gallstone lithotripsy. In all cases with adequate visualization of stone fragments, the stratification phenomenon was observed. We hypothesized that adjusting the shock wave focus to target on these large fragments would improve the efficiency of fragmentation. To test this hypothesis, we fragmented three matched pairs of gallstones in vitro. For each pair, the stones were removed from the same gallbladder and the stone weights of the two stones were within 10%. The smaller member of each pair was fragmented using the "old method" with the focus on the fragment line. The larger stone was fragmented with the "new method" with the focus in the acoustic shadow deep to the echogenic line caused by the dust and small fragments in the dependent portion. The distribution of fragments was analyzed by passing the fragments through a series of filters. With the new method of targeting, the proportion of fragments less than 1.5 mm was doubled while the fragments greater than 5 mm were eliminated. The new method of targeting, taking into account the stratification of stone fragments, produces more effective fragmentation and should lead to more rapid clearance of fragments from the gallbladder. PMID:10149180

  9. 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

  10. Literalism, perspectivism, chaotic fragmentalism and psychotherapy techniques.

    PubMed

    Leitner, L M

    1982-12-01

    Literalism and chaotic fragmentalism have been advanced as two concepts to explain psychopathology while perspectivism has been used to explain psychological health (Landfield, 1980 a). It is hypothesized that, to the extent that they are therapeutic, all therapies move clients toward perspectivism and away from literalism and chaotic fragmentalism. Eight major schools of psychotherapy are discussed in terms of the principles of technique which enable them to change literalism and chaotic fragmentalism. The advantages of a unifying theory permitting diversity of techniques are discussed in relation to the ability of the clinician to be flexible yet not confused. Further, the unifying concepts of literalism, perspectivism, and chaotic fragmentalism are used to understand systematically the strengths and weaknesses of many therapeutic techniques. Finally, the implications of the differences in therapeutic techniques for changing different types of literalisms are discussed. PMID:7150515

  11. Jet fragmentation via recombination of parton showers

    NASA Astrophysics Data System (ADS)

    Han, Kyong Chol; Fries, Rainer J.; Ko, Che Ming

    2016-04-01

    We propose to model hadronization of parton showers in QCD jets through a hybrid approach involving quark recombination and string fragmentation. This is achieved by allowing gluons at the end of the perturbative shower evolution to undergo a nonperturbative splitting into quark and antiquark pairs, then applying a Monte Carlo version of instantaneous quark recombination, and finally subjecting remnant quarks (those which have not found a recombination partner) to Lund string fragmentation. When applied to parton showers from the pythia Monte Carlo event generator, the final hadron spectra from our calculation compare quite well to pythia jets that have been hadronized with the default Lund string fragmentation. Our new approach opens up the possibility to generalize hadronization to jets embedded in a quark gluon plasma.

  12. Fragment capture device

    DOEpatents

    Payne, Lloyd R.; Cole, David L.

    2010-03-30

    A fragment capture device for use in explosive containment. The device comprises an assembly of at least two rows of bars positioned to eliminate line-of-sight trajectories between the generation point of fragments and a surrounding containment vessel or asset. The device comprises an array of at least two rows of bars, wherein each row is staggered with respect to the adjacent row, and wherein a lateral dimension of each bar and a relative position of each bar in combination provides blockage of a straight-line passage of a solid fragment through the adjacent rows of bars, wherein a generation point of the solid fragment is located within a cavity at least partially enclosed by the array of bars.

  13. Fracture tooth fragment reattachment

    PubMed Central

    Maitin, Nitin; Maitin, Shipra Nangalia; Rastogi, Khushboo; Bhushan, Rajarshi

    2013-01-01

    Coronal fractures of the anterior teeth are a common form of dental trauma and its sequelae may impair the establishment and accomplishment of an adequate treatment plan. Among the various treatment options, reattachment of a crown fragment is a conservative treatment that should be considered for crown fractures of anterior teeth. This clinical case reports the management of two coronal tooth fracture cases that were successfully treated using tooth fragment reattachment using glass-fibre-reinforced composite post. PMID:23853012

  14. Large scale meta-analysis of fragment-based screening campaigns: privileged fragments and complementary technologies.

    PubMed

    Kutchukian, Peter S; Wassermann, Anne Mai; Lindvall, Mika K; Wright, S Kirk; Ottl, Johannes; Jacob, Jaison; Scheufler, Clemens; Marzinzik, Andreas; Brooijmans, Natasja; Glick, Meir

    2015-06-01

    A first step in fragment-based drug discovery (FBDD) often entails a fragment-based screen (FBS) to identify fragment "hits." However, the integration of conflicting results from orthogonal screens remains a challenge. Here we present a meta-analysis of 35 fragment-based campaigns at Novartis, which employed a generic 1400-fragment library against diverse target families using various biophysical and biochemical techniques. By statistically interrogating the multidimensional FBS data, we sought to investigate three questions: (1) What makes a fragment amenable for FBS? (2) How do hits from different fragment screening technologies and target classes compare with each other? (3) What is the best way to pair FBS assay technologies? In doing so, we identified substructures that were privileged for specific target classes, as well as fragments that were privileged for authentic activity against many targets. We also revealed some of the discrepancies between technologies. Finally, we uncovered a simple rule of thumb in screening strategy: when choosing two technologies for a campaign, pairing a biochemical and biophysical screen tends to yield the greatest coverage of authentic hits. PMID:25550355

  15. A general theory of turbulent fragmentation

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.

    2013-04-01

    the fragmentation process. We demonstrate that this is because fragmentation cascades on small scales are generically `frozen in' when large-scale fluctuations push the `parent' region above the collapse threshold; though they collapse, their statistics are only weakly modified by the collapse process. Finally, with thermal or turbulent support, structure develops `top-down' in time via a fragmentation cascade, but we show that significant rotational/angular momentum support reverses the sense of structure formation to `bottom-up' growth via mergers of bound clumps, and introduces a characteristic `maximal instability scale' distinct from the Toomre scale.

  16. Heavy fragment radioactivities

    SciTech Connect

    Price, P.B.

    1987-12-10

    This recently discovered mode of radioactive decay, like alpha decay and spontaneous fission, is believed to involve tunneling through the deformation-energy barrier between a very heavy nucleus and two separated fragments the sum of whose masses is less than the mass of the parent nucleus. In all known cases the heavier of the two fragments is close to doubly magic /sup 208/Pb, and the lighter fragment has even Z. Four isotopes of Ra are known to emit /sup 14/C nuclei; several isotopes of U as well as /sup 230/Th and /sup 231/Pa emit Ne nuclei; and /sup 234/U exhibits four hadronic decay modes: alpha decay, spontaneous fission, Ne decay and Mg decay.

  17. Fragment screening: an introduction.

    PubMed

    Leach, Andrew R; Hann, Michael M; Burrows, Jeremy N; Griffen, Ed J

    2006-09-01

    There are clearly many different philosophies associated with adapting fragment screening into mainstream Drug Discovery Lead Generation strategies. Scientists at Astex, for instance, focus entirely on strategies involving use of X-ray crystallography and NMR. However, AstraZeneca uses a number of different fragment screening strategies. One approach is to screen a 2000 compound fragment set (with close to "lead-like" complexity) at 100 microM in parallel with every HTS such that the data are obtained on the entire screening collection at 10 microM plus the extra samples at 100 microM; this provides valuable compound potency data in a concentration range that is usually unexplored. The fragments are then screen-specific "privileged structures" that can be searched for in the rest of the HTS output and other databases as well as having synthesis follow-up. A typical workflow for a fragment screen within AstraZeneca is shown below (Figure 24) and highlights the desirability (particularly when screening >100 microM) for NMR and X-ray information to validate weak hits and give information on how to optimise them. In this chapter, we have provided an introduction to the theoretical and practical issues associated with the use of fragment methods and lead-likeness. Fragment-based approaches are still in an early stage of development and are just one of many interrelated techniques that are now used to identify novel lead compounds for drug development. Fragment based screening has some advantages, but like every other drug hunting strategy will not be universally applicable. There are in particular some practical challenges associated with fragment screening that relate to the generally lower level of potency that such compounds initially possess. Considerable synthetic effort has to be applied for post-fragment screening to build the sort of potency that would be expected to be found from a traditional HTS. However, if there are no low-hanging fruit in a screening

  18. Fragmentation methods in laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Jiang, Zhi X.; Whitehurst, Colin; King, Terence A.

    1991-07-01

    Following a series of opto-acoustic-mechanical and spectroscopic studies into the basic mechanisms of laser lithotripsy, a plasma-mediated opto-mechanical energy transfer model is presented. Laser energy, first absorbed by the calculi material at the surface and couples into the initiated plasma following ionization of vaporized material, is finally transformed into destructive mechanical energy via a shock wave induced by the impulsive expansion of the resulting plasma. This leads to the fragmentation of the calculi. The laser-plasma energy coupling gives a new definition for the fluence threshold to laser induced breakdown, which agrees with shock wave detection and analysis. A laser pulse shape with initial low intensity and sufficient fluence to vaporize a required amount of target material (lasting a few microsecond(s) ) and terminating in a short, intense pulse of about 1microsecond(s) or less, to couple most of the laser energy into the dense young plasma and so create high pressures, is required to produce optimum effect for laser lithotripsy. An opto-mechanical coupler has been designed which transfers the maximum laser energy into mechanically destructive energy, and successfully fragments various types of urinary and biliary calculi even including those calculi with poor surface absorptance, like pure white cystine. A solid state laser, Ho:YAG (2.1 micrometers wavelength and 150 microsecond(s) pulse width), has also been tested as an alternative to the flashlamp-excited dye laser. The underwater shock wave induced by this laser has been measured and has successfully fragmented calculi with poor absorptance in the visible region.

  19. 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. PMID:25166159

  20. 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.

  1. Searching for lost fragments in GEO

    NASA Astrophysics Data System (ADS)

    Ikeda, Hitoshi; Hanada, Toshiya; Yasaka, Tetsuo

    2008-12-01

    This paper attempts to search the lost fragments from the near-synchronous US TitanIIIC transtage explosion of February 21, 1992, known as the second major fragmentation of a TitanIIIC transtage. This breakup was accidentally observed by the Maui GEODSS sensor, and then a total of 23 objects were reported from the breakup, no orbital data on any fragments has been generated by the SSN. In order to evaluate the debris cloud orbital evolution, we demonstrate the actual US TitanIIIC transtage explosion by using breakup model and orbit propagator. The perturbing accelerations, considered in this analysis are the non-spherical part of the Earth's gravitational attraction, the gravitational attraction due to the Sun and Moon, and the solar radiation pressure effects. Finally, we will present a search strategy based on distribution of the right ascension of the ascending node about the catalogued objects and the debris particles from the US TitanIIIC transtage explosion.

  2. 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).

  3. Shielding and fragmentation studies.

    PubMed

    Zeitlin, C; Guetersloh, S; Heilbronn, L; Miller, J

    2005-01-01

    Radiation dosimetry for manned spaced missions depends on the ability to adequately describe the process of high-energy ion transport through many materials. Since the types of possible nuclear interactions are many and complex, transport models are used which depend upon a reliable source of experimental data. To expand the heavy ion database used in the models we have been measuring charge-changing cross sections and fragment production cross sections from heavy-ion interactions in various elementa targets. These include materials flown on space missions such as carbon and aluminium, as well as those important in radiation dosimetry such as hydrogen, nitrogen and water. Measuring heavy-ion fragmentation through these targets also gives us the ability to determine the effectiveness of new materials proposed for shielding such as graphite composites and polyethylene hybrids. Measurement without a target present gives an indication of the level of contamination of the primary beam, which is also important in radiobiology experiments. PMID:16604611

  4. Fragmentation of cancer cells

    NASA Astrophysics Data System (ADS)

    Vanapalli, Siva; Kamyabi, Nabiollah

    Tumor cells have to travel through blood capillaries to be able to metastasize and colonize in distant organs. Among the numerous cells that are shed by the primary tumor, very few survive in circulation. In vivo studies have shown that tumor cells can undergo breakup at microcapillary junctions affecting their survival. It is currently unclear what hydrodynamic and biomechanical factors contribute to fragmentation and moreover how different are the breakup dynamics of highly and weakly metastatic cells. In this study, we use microfluidics to investigate flow-induced breakup of prostate and breast cancer cells. We observe several different modes of breakup of cancer cells, which have striking similarities with breakup of viscous drops. We quantify the breakup time and find that highly metastatic cancer cells take longer to breakup than lowly metastatic cells suggesting that tumor cells may dynamically modify their deformability to avoid fragmentation. We also identify the role that cytoskeleton and membrane plays in the breakup process. Our study highlights the important role that tumor cell fragmentation plays in cancer metastasis. Cancer Prevention and Research Institute of Texas.

  5. Electroeluting DNA fragments.

    PubMed

    Zarzosa-Alvarez, Ana L; Sandoval-Cabrera, Antonio; Torres-Huerta, Ana L; Bermudez-Cruz, Rosa M

    2010-01-01

    Purified DNA fragments are used for different purposes in Molecular Biology and they can be prepared by several procedures. Most of them require a previous electrophoresis of the DNA fragments in order to separate the band of interest. Then, this band is excised out from an agarose or acrylamide gel and purified by using either: binding and elution from glass or silica particles, DEAE-cellulose membranes, "crush and soak method", electroelution or very often expensive commercial purification kits. Thus, selecting a method will depend mostly of what is available in the laboratory. The electroelution procedure allows one to purify very clean DNA to be used in a large number of applications (sequencing, radiolabeling, enzymatic restriction, enzymatic modification, cloning etc). This procedure consists in placing DNA band-containing agarose or acrylamide slices into sample wells of the electroeluter, then applying current will make the DNA fragment to leave the agarose and thus be trapped in a cushion salt to be recovered later by ethanol precipitation. PMID:20834225

  6. Fracture, failure, and fragmentation

    SciTech Connect

    Dienes, J.K.

    1984-01-01

    Though continuum descriptions of material behavior are useful for many kinds of problems, particularly those involving plastic flow, a more general approach is required when the failure is likely to involve growth and coalescence of a large number of fractures, as in fragmentation. Failures of this kind appear frequently in rapid dynamic processes such as those resulting from impacts and explosions, particularly in the formation of spall fragments. In the first part of this paper an approach to formulating constitutive relations that accounts for the opening, shear and growth of an ensemble of cracks is discussed. The approach also accounts for plastic flow accompanying fragmentation. The resulting constitutive relations have been incorporated into a Lagrangean computer program. In the second part of this paper a theoretical approach to coalescence is described. The simplest formulation makes use of a linear Liouville equation, with crack growth limited by the mean free path of cracks, assumed constant. This approach allows for an anisotropic distribution of cracks. An alternative approach is also described in which the decrease of the mean free path with increasing crack size is accounted for, but the crack distribution is assumed isotropic. A reduction of the governing Liouville equation to an ordinary differential equation of third order is possible, and the result can be used to determine how mean-free-path decreases with increasing crack size.

  7. Fragment-based lead design

    NASA Astrophysics Data System (ADS)

    Filz, O. A.; Poroikov, Vladimir V.

    2012-02-01

    State-of-the-art approaches to the fragment-based design of organic compounds with desired properties are considered. The review covers methods, which are used in different steps of the design, such as computational methods for fragment library design, experimental and computational methods for fragment discovery and methods for the generation of structures of organic compounds. Examples are given of drug candidates, which were constructed using the fragment-based approach. The bibliography includes 156 references.

  8. 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

  9. Virtual fragment preparation for computational fragment-based drug design.

    PubMed

    Ludington, Jennifer L

    2015-01-01

    Fragment-based drug design (FBDD) has become an important component of the drug discovery process. The use of fragments can accelerate both the search for a hit molecule and the development of that hit into a lead molecule for clinical testing. In addition to experimental methodologies for FBDD such as NMR and X-ray Crystallography screens, computational techniques are playing an increasingly important role. The success of the computational simulations is due in large part to how the database of virtual fragments is prepared. In order to prepare the fragments appropriately it is necessary to understand how FBDD differs from other approaches and the issues inherent in building up molecules from smaller fragment pieces. The ultimate goal of these calculations is to link two or more simulated fragments into a molecule that has an experimental binding affinity consistent with the additive predicted binding affinities of the virtual fragments. Computationally predicting binding affinities is a complex process, with many opportunities for introducing error. Therefore, care should be taken with the fragment preparation procedure to avoid introducing additional inaccuracies.This chapter is focused on the preparation process used to create a virtual fragment database. Several key issues of fragment preparation which affect the accuracy of binding affinity predictions are discussed. The first issue is the selection of the two-dimensional atomic structure of the virtual fragment. Although the particular usage of the fragment can affect this choice (i.e., whether the fragment will be used for calibration, binding site characterization, hit identification, or lead optimization), general factors such as synthetic accessibility, size, and flexibility are major considerations in selecting the 2D structure. Other aspects of preparing the virtual fragments for simulation are the generation of three-dimensional conformations and the assignment of the associated atomic point charges

  10. Fragmentation of Massive Dense Cores Down to <~ 1000 AU: Relation between Fragmentation and Density Structure

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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. The James Clerk Maxwell Telescope is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the United Kingdom, the Netherlands Organisation for Scientific Research, and the National Research Council of Canada.

  11. Tube Fragmentation of Multiple Materials

    SciTech Connect

    Thornhill, T. F.; Chhabildas, L. C.; Vogler, T. J.

    2006-07-28

    In the current study we are developing an experimental fracture material property test method specific to dynamic fragmentation. This test method allows the study of fracture fragmentation in a reproducible laboratory environment under well-controlled loading conditions. Motion and fragmentation of the specimen are diagnosed using framing camera, VISAR and soft recovery methods. Fragmentation properties of several steels, nitinol, tungsten alloy, copper, aluminum, and titanium have been obtained to date. The values for fragmentation toughness, and failure threshold will be reported, as well as effects in these values as the material strain-rate is varied through changes in wall thickness and impact conditions.

  12. Tube fragmentation of multiple materials.

    SciTech Connect

    Thornhill, Tom Finley, III; Vogler, Tracy John; Chhabildas, Lalit Chandra

    2003-07-01

    In the current study we are developing an experimental fracture material property test method specific to dynamic fragmentation. This test method allows the study of fracture fragmentation in a reproducible laboratory environment under well-controlled loading conditions. Motion and fragmentation of the specimen are diagnosed using framing camera, VISAR and soft recovery methods. Fragmentation properties of several steels, nitinol, tungsten alloy, copper, aluminum, and titanium have been obtained to date. The values for fragmentation toughness, and failure threshold will be reported, as well as effects in these values as the material strain-rate is varied through changes in wall thickness and impact conditions.

  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. A New Secondary Structure Assignment Algorithm Using Cα Backbone Fragments.

    PubMed

    Cao, Chen; Wang, Guishen; Liu, An; Xu, Shutan; Wang, Lincong; Zou, Shuxue

    2016-01-01

    The assignment of secondary structure elements in proteins is a key step in the analysis of their structures and functions. We have developed an algorithm, SACF (secondary structure assignment based on Cα fragments), for secondary structure element (SSE) assignment based on the alignment of Cα backbone fragments with central poses derived by clustering known SSE fragments. The assignment algorithm consists of three steps: First, the outlier fragments on known SSEs are detected. Next, the remaining fragments are clustered to obtain the central fragments for each cluster. Finally, the central fragments are used as a template to make assignments. Following a large-scale comparison of 11 secondary structure assignment methods, SACF, KAKSI and PROSS are found to have similar agreement with DSSP, while PCASSO agrees with DSSP best. SACF and PCASSO show preference to reducing residues in N and C cap regions, whereas KAKSI, P-SEA and SEGNO tend to add residues to the terminals when DSSP assignment is taken as standard. Moreover, our algorithm is able to assign subtle helices (310-helix, π-helix and left-handed helix) and make uniform assignments, as well as to detect rare SSEs in β-sheets or long helices as outlier fragments from other programs. The structural uniformity should be useful for protein structure classification and prediction, while outlier fragments underlie the structure-function relationship. PMID:26978354

  15. A New Secondary Structure Assignment Algorithm Using Cα Backbone Fragments

    PubMed Central

    Cao, Chen; Wang, Guishen; Liu, An; Xu, Shutan; Wang, Lincong; Zou, Shuxue

    2016-01-01

    The assignment of secondary structure elements in proteins is a key step in the analysis of their structures and functions. We have developed an algorithm, SACF (secondary structure assignment based on Cα fragments), for secondary structure element (SSE) assignment based on the alignment of Cα backbone fragments with central poses derived by clustering known SSE fragments. The assignment algorithm consists of three steps: First, the outlier fragments on known SSEs are detected. Next, the remaining fragments are clustered to obtain the central fragments for each cluster. Finally, the central fragments are used as a template to make assignments. Following a large-scale comparison of 11 secondary structure assignment methods, SACF, KAKSI and PROSS are found to have similar agreement with DSSP, while PCASSO agrees with DSSP best. SACF and PCASSO show preference to reducing residues in N and C cap regions, whereas KAKSI, P-SEA and SEGNO tend to add residues to the terminals when DSSP assignment is taken as standard. Moreover, our algorithm is able to assign subtle helices (310-helix, π-helix and left-handed helix) and make uniform assignments, as well as to detect rare SSEs in β-sheets or long helices as outlier fragments from other programs. The structural uniformity should be useful for protein structure classification and prediction, while outlier fragments underlie the structure–function relationship. PMID:26978354

  16. Habitat specialization predicts genetic response to fragmentation in tropical birds.

    PubMed

    Khimoun, Aurélie; Eraud, Cyril; Ollivier, Anthony; Arnoux, Emilie; Rocheteau, Vincent; Bely, Marine; Lefol, Emilie; Delpuech, Martin; Carpentier, Marie-Laure; Leblond, Gilles; Levesque, Anthony; Charbonnel, Anaïs; Faivre, Bruno; Garnier, Stéphane

    2016-08-01

    Habitat fragmentation is one of the most severe threats to biodiversity as it may lead to changes in population genetic structure, with ultimate modifications of species evolutionary potential and local extinctions. Nonetheless, fragmentation does not equally affect all species and identifying which ecological traits are related to species sensitivity to habitat fragmentation could help prioritization of conservation efforts. Despite the theoretical link between species ecology and extinction proneness, comparative studies explicitly testing the hypothesis that particular ecological traits underlies species-specific population structure are rare. Here, we used a comparative approach on eight bird species, co-occurring across the same fragmented landscape. For each species, we quantified relative levels of forest specialization and genetic differentiation among populations. To test the link between forest specialization and susceptibility to forest fragmentation, we assessed species responses to fragmentation by comparing levels of genetic differentiation between continuous and fragmented forest landscapes. Our results revealed a significant and substantial population structure at a very small spatial scale for mobile organisms such as birds. More importantly, we found that specialist species are more affected by forest fragmentation than generalist ones. Finally, our results suggest that even a simple habitat specialization index can be a satisfying predictor of genetic and demographic consequences of habitat fragmentation, providing a reliable practical and quantitative tool for conservation biology. PMID:27314987

  17. Scaling behavior of fragment shapes.

    PubMed

    Kun, F; Wittel, F K; Herrmann, H J; Kröplin, B H; Måløy, K J

    2006-01-20

    We present an experimental and theoretical study of the shape of fragments generated by explosive and impact loading of closed shells. Based on high speed imaging, we have determined the fragmentation mechanism of shells. Experiments have shown that the fragments vary from completely isotropic to highly anisotropic elongated shapes, depending on the microscopic cracking mechanism of the shell. Anisotropic fragments proved to have a self-affine character described by a scaling exponent. The distribution of fragment shapes exhibits a power-law decay. The robustness of the scaling laws is illustrated by a stochastic hierarchical model of fragmentation. Our results provide a possible improvement of the representation of fragment shapes in models of space debris. PMID:16486594

  18. Fragment oriented molecular shapes.

    PubMed

    Hain, Ethan; Camacho, Carlos J; Koes, David Ryan

    2016-05-01

    Molecular shape is an important concept in drug design and virtual screening. Shape similarity typically uses either alignment methods, which dynamically optimize molecular poses with respect to the query molecular shape, or feature vector methods, which are computationally less demanding but less accurate. The computational cost of alignment can be reduced by pre-aligning shapes, as is done with the Volumetric-Aligned Molecular Shapes (VAMS) method. Here, we introduce and evaluate fragment oriented molecular shapes (FOMS), where shapes are aligned based on molecular fragments. FOMS enables the use of shape constraints, a novel method for precisely specifying molecular shape queries that provides the ability to perform partial shape matching and supports search algorithms that function on an interactive time scale. When evaluated using the challenging Maximum Unbiased Validation dataset, shape constraints were able to extract significantly enriched subsets of compounds for the majority of targets, and FOMS matched or exceeded the performance of both VAMS and an optimizing alignment method of shape similarity search. PMID:27085751

  19. 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)

  20. 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.

  1. Calibrations for studies of neutron-rich precursor fragments

    NASA Astrophysics Data System (ADS)

    Mazza, Maria; Parkhurst, Rachel; Wilensky, Samuel; Mosby, Michelle; Stephenson, Sharon; Rogers, Warren; MoNA Collaboration Collaboration

    2015-10-01

    Heavy ion collisions at relativistic energies produce the radioactive beams used at nuclear structure facilities worldwide. However, there are still unanswered questions about the reaction mechanism of projectile fragmentation and the specific roles that ablation, evaporation, and abrasion play. Using the projectile fragmentation of a 32Mg beam at 86 MeV/u on a natural Beryllium target at the National Superconducting Cyclotron Laboratory (NSCL), our experimental goal is to better understand the excitation energy and the momentum distribution of the precursors of the observed final fragments (neon, sodium, and fluorine). A suite of charged particle detectors in conjunction with the Modular Neutron Array (MoNA) allows us to analyze both the charged final fragments as well as the coincident neutrons. Detector calibration results and preliminary results will be presented. This material is based upon work supported by the National Science Foundation under Grants PHY-1205537.

  2. 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

  3. Chapter 4 embedded metal fragments.

    PubMed

    Kalinich, John F; Vane, Elizabeth A; Centeno, Jose A; Gaitens, Joanna M; Squibb, Katherine S; McDiarmid, Melissa A; Kasper, Christine E

    2014-01-01

    The continued evolution of military munitions and armor on the battlefield, as well as the insurgent use of improvised explosive devices, has led to embedded fragment wounds containing metal and metal mixtures whose long-term toxicologic and carcinogenic properties are not as yet known. Advances in medical care have greatly increased the survival from these types of injuries. Standard surgical guidelines suggest leaving embedded fragments in place, thus individuals may carry these retained metal fragments for the rest of their lives. Nursing professionals will be at the forefront in caring for these wounded individuals, both immediately after the trauma and during the healing and rehabilitation process. Therefore, an understanding of the potential health effects of embedded metal fragment wounds is essential. This review will explore the history of embedded fragment wounds, current research in the field, and Department of Defense and Department of Veterans Affairs guidelines for the identification and long-term monitoring of individuals with embedded fragments. PMID:25222538

  4. Fragmentation pathways of polymer ions.

    PubMed

    Wesdemiotis, Chrys; Solak, Nilüfer; Polce, Michael J; Dabney, David E; Chaicharoen, Kittisak; Katzenmeyer, Bryan C

    2011-01-01

    Tandem mass spectrometry (MS/MS) is increasingly applied to synthetic polymers to characterize chain-end or in-chain substituents, distinguish isobaric and isomeric species, and determine macromolecular connectivities and architectures. For confident structural assignments, the fragmentation mechanisms of polymer ions must be understood, as they provide guidelines on how to deduce the desired information from the fragments observed in MS/MS spectra. This article reviews the fragmentation pathways of synthetic polymer ions that have been energized to decompose via collisionally activated dissociation (CAD), the most widely used activation method in polymer analysis. The compounds discussed encompass polystyrenes, poly(2-vinyl pyridine), polyacrylates, poly(vinyl acetate), aliphatic polyester copolymers, polyethers, and poly(dimethylsiloxane). For a number of these polymers, several substitution patterns and architectures are considered, and questions regarding the ionization agent and internal energy of the dissociating precursor ions are also addressed. Competing and consecutive dissociations are evaluated in terms of the structural insight they provide about the macromolecular structure. The fragmentation pathways of the diverse array of polymer ions examined fall into three categories, viz. (1) charge-directed fragmentations, (2) charge-remote rearrangements, and (3) charge-remote fragmentations via radical intermediates. Charge-remote processes predominate. Depending on the ionizing agent and the functional groups in the polymer, the incipient fragments arising by pathways (1)-(3) may form ion-molecule complexes that survive long enough to permit inter-fragment hydrogen atom, proton, or hydride transfers. PMID:20623599

  5. Fragment-based drug design.

    PubMed

    Feyfant, Eric; Cross, Jason B; Paris, Kevin; Tsao, Désirée H H

    2011-01-01

    Fragment-based drug design (FBDD), which is comprised of both fragment screening and the use of fragment hits to design leads, began more than 15 years ago and has been steadily gaining in popularity and utility. Its origin lies on the fact that the coverage of chemical space and the binding efficiency of hits are directly related to the size of the compounds screened. Nevertheless, FBDD still faces challenges, among them developing fragment screening libraries that ensure optimal coverage of chemical space, physical properties and chemical tractability. Fragment screening also requires sensitive assays, often biophysical in nature, to detect weak binders. In this chapter we will introduce the technologies used to address these challenges and outline the experimental advantages that make FBDD one of the most popular new hit-to-lead process. PMID:20981527

  6. 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

  7. 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. PMID:26875110

  8. Dynamic fragmentation of ferroelectric ceramics using the torsional Kolsky bar

    SciTech Connect

    Costin, L S; Grady, D E

    1983-10-01

    This paper studied the dynamic loading and subsequent fragmentation of four different load zirconate titanate (95/5 PZT) ferroelectric ceramics using a torsional Kolsky bar apparatus. Solid cylinders of the four materials were loaded in torsion at shear strain rates in the range 10/sup 2/ to 10/sup 3/s/sup -1/. Using the strain gage recordings of the incident, reflected and transmitted pulses, the energy required to fragment the specimen was determined for each test. In addition, the fragments resulting from each test were collected and analyzed by various technciques to determine their mass and size distributions. Results show some differences in particle distributions between the different batches of material. However, there is a more significant and consistent difference between the dynamic strength (as measured by the maximum shear stress) and the fragment mass distributions of the virgin material and the pressure depoled material, despite the fact that no differences were detected in the energy of fragmentation. Using earlier analytical results which relate the local kinetic energy of a potential fragment to the surface energy required to create that fragment, a relationship between the distribution of fragments from a test and material properties was derived. Results of tests on PZT as well as other materials such as oil shale, graphite, uranium dioxide and glass indicate a good correlation between the fragment distribution parameter, n, and material properties as predicted by the theory. Finally, the results are analyzed to determine the potential effects of internal stresses on the dynamic strength of the material and its fragmentation characteristics.

  9. Measuring the photon fragmentation function at HERA

    NASA Astrophysics Data System (ADS)

    Gehrmann-de Ridder, A.; Gehrmann, T.; Poulsen, E.

    2006-08-01

    The production of final state photons in deep inelastic scattering originates from photon radiation off leptons or quarks involved in the scattering process. Photon radiation off quarks involves a contribution from the quark-to-photon fragmentation function, corresponding to the non-perturbative transition of a hadronic jet into a single, highly energetic photon accompanied by some limited hadronic activity. Up to now, this fragmentation function was measured only in electron positron annihilation at LEP. We demonstrate by a dedicated parton-level calculation that a competitive measurement of the quark-to-photon fragmentation function can be obtained in deep inelastic scattering at HERA. Such a measurement can be obtained by studying the photon energy spectra in γ+(0+1)-jet events, where γ denotes a hadronic jet containing a highly energetic photon (the photon jet). Isolated photons are then defined from the photon jet by imposing a minimal photon energy fraction. For this so-called democratic clustering approach, we study the cross sections for isolated γ+(0+1)-jet and γ+(1+1)-jet production as well as for the inclusive isolated photon production in deep inelastic scattering.

  10. 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.

  11. 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. PMID:26779832

  12. 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.

  13. Fragmentation Function in Thermofield Dynamics

    NASA Astrophysics Data System (ADS)

    Ladrem, M.; Chekerker, M.; Khanna, F. C.; Santana, A. E.

    2013-04-01

    The fragmentation function at high energy experiments is introduced by using thermofield dynamics (TFD), a real-time finite-temperature quantum field formalism. Due to the structure of TFD, the results at T = 0 and T ≠ 0 are split in a direct way. As an application, we consider the temperature effect on the fragmentation function of a hadron leading to quark-antiquark pairs. Using a definition of Wilson-loop in real-time, we find that the fragmentation function decreases in magnitude with an increase in the temperature.

  14. Velocity fluctuations of fission fragments

    NASA Astrophysics Data System (ADS)

    Llanes-Estrada, Felipe J.; Carmona, Belén Martínez; Martínez, Jose L. Muñoz

    2016-02-01

    We propose event by event velocity fluctuations of nuclear fission fragments as an additional interesting observable that gives access to the nuclear temperature in an independent way from spectral measurements and relates the diffusion and friction coefficients for the relative fragment coordinate in Kramers-like models (in which some aspects of fission can be understood as the diffusion of a collective variable through a potential barrier). We point out that neutron emission by the heavy fragments can be treated in effective theory if corrections to the velocity distribution are needed.

  15. Fragment merger: an online tool to merge overlapping long sequence fragments.

    PubMed

    Bell, Trevor G; Kramvis, Anna

    2013-03-01

    While PCR amplicons extend to a few thousand bases, the length of sequences from direct Sanger sequencing is limited to 500-800 nucleotides. Therefore, several fragments may be required to cover an amplicon, a gene or an entire genome. These fragments are typically sequenced in an overlapping fashion and assembled by manually sliding and aligning the sequences visually. This is time-consuming, repetitive and error-prone, and further complicated by circular genomes. An online tool merging two to twelve long overlapping sequence fragments was developed. Either chromatograms or FASTA files are submitted to the tool, which trims poor quality ends of chromatograms according to user-specified parameters. Fragments are assembled into a single sequence by repeatedly calling the EMBOSS merger tool in a consecutive manner. Output includes the number of trimmed nucleotides, details of each merge, and an optional alignment to a reference sequence. The final merge sequence is displayed and can be downloaded in FASTA format. All output files can be downloaded as a ZIP archive. This tool allows for easy and automated assembly of overlapping sequences and is aimed at researchers without specialist computer skills. The tool is genome- and organism-agnostic and has been developed using hepatitis B virus sequence data. PMID:23482300

  16. 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.

  17. (Natural fragmentation of exploding cylinders)

    SciTech Connect

    Grady, D.E.; Hightower, M.M.

    1990-01-01

    The natural fragmentation of a 4140 steel cylinder fully loaded with RX-35-AN insensitive high explosive is investigated through experiment and analysis. Methods of Taylor and Gurney are used to determine the fracture strain and kinematic state of the expanding cylinder. Energy methods based on mechanisms of both tension fracture and adiabatic shear fracture are used to calculate the circumferential fragmentation intensity. 9 refs., 5 figs.

  18. Fragmentation of hot classical drops

    SciTech Connect

    Vicentini, A.; Jacucci, G.; Pandharipande, V.R.

    1985-05-01

    Time evolution of hot drops of matter containing approx.230 or approx.130 particles is studied by classical molecular dynamics. Initially, the drops have uniform density and a sharp surface. The chosen initial conditions include three values of density and a range of temperatures wide enough to study the phenomena of evaporation, fragmentation, and total vaporization in a unified fashion. The average density and temperature of central matter is measured periodically to obtain trajectories of the evolution in the rho,T plane. These trajectories indicate that the matter expands almost adiabatically until it reaches the region of adiabatic instabilities. Density inhomogeneities develop in this region, but the matter fragments only if the expansion continues to average densities of less than one-fourth the liquid density, otherwise it recondenses into a single blob. The recondensed matter and fragments have very crooked surfaces. If the temperature is high enough, the expanding matter does not enter the region of adiabatic instabilities and totally vaporizes. For initial densities of the order of equilibrium density, matter does not fragment or develop large inhomogeneities in the region enclosed by the isothermal and adiabatic spinodals. Thus it appears unlikely that fragmentation of small drops (nuclei) can be used to study the isothermal critical region of gas-liquid phase transition. A detailed tabulation of the energies and number of monomers, dimers, light, and heavy fragments emitted in each event is presented.

  19. 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

  20. 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.

  1. Biological restorations using tooth fragments.

    PubMed

    Busato, A L; Loguercio, A D; Barbosa, A N; Sanseverino, M do C; Macedo, R P; Baldissera, R A

    1998-02-01

    A "biological" restoration technique using dental fragments and adhesive materials is described. These fragments were obtained from extracted human teeth which had been previously sterilized and stored in a tooth bank. The advantages are: the use of extracted teeth as restorative material, esthetics, and treatment cost. The positive sensation of having back the missing tooth was the most mentioned comment among patients. The disadvantages are: the difficulty of obtaining teeth with the needed characteristics, problems of making an indirect restoration, matching the original color, and the non-acceptance by some patients who consider it strange to have other people's teeth placed in their mouths. PMID:9823086

  2. WITHDRAWN: Fragmentation of charged aqueous nanodroplets

    NASA Astrophysics Data System (ADS)

    Ichiki, Kengo

    2005-11-01

    The whole evaporating process of charged aqueous nanodroplets is studied by systematic molecular dynamics simulations until most of the solvent molecules are evaporated. % The solvent evaporation makes the droplet smaller and smaller, and at a certain point the repulsive force among ions causes an instability, where typically single ion and 10 to 20 water molecules are disintegrated from the main droplet. % This ion fragmentation occurs around 70 to 80% of the charge predicted by the Rayleigh theory [Lord Rayleigh, Phil. Mag. 14, 184 (1882)]. % The numerical results are summarized in the function R(z) which is the fragmentation radius at the charge z. From the fitting by the power law Rz^β, we find that at lower temperature T=350 and 370 K the result is close to the Rayleigh theory β= 2/3, while at higher temperature T=400 and 450 K it is like β= 1/2. % Another fitting on R(z) by the extended ion evaporation mechanism [M. Gamero-Castaño and J. Fern'andez de la Mora, Anal. Chim. Acta 406, 67 (2000)] works well for both cases. % The final state of the evaporation process is typically a single ion with several water molecules. If we put an alanine dipeptide in zwitterionic form at the beginning, two charges remain in some cases.

  3. Metapopulation Persistence in Random Fragmented Landscapes

    PubMed Central

    Grilli, Jacopo; Barabás, György; Allesina, Stefano

    2015-01-01

    Habitat destruction and land use change are making the world in which natural populations live increasingly fragmented, often leading to local extinctions. Although local populations might undergo extinction, a metapopulation may still be viable as long as patches of suitable habitat are connected by dispersal, so that empty patches can be recolonized. Thus far, metapopulations models have either taken a mean-field approach, or have modeled empirically-based, realistic landscapes. Here we show that an intermediate level of complexity between these two extremes is to consider random landscapes, in which the patches of suitable habitat are randomly arranged in an area (or volume). Using methods borrowed from the mathematics of Random Geometric Graphs and Euclidean Random Matrices, we derive a simple, analytic criterion for the persistence of the metapopulation in random fragmented landscapes. Our results show how the density of patches, the variability in their value, the shape of the dispersal kernel, and the dimensionality of the landscape all contribute to determining the fate of the metapopulation. Using this framework, we derive sufficient conditions for the population to be spatially localized, such that spatially confined clusters of patches act as a source of dispersal for the whole landscape. Finally, we show that a regular arrangement of the patches is always detrimental for persistence, compared to the random arrangement of the patches. Given the strong parallel between metapopulation models and contact processes, our results are also applicable to models of disease spread on spatial networks. PMID:25993004

  4. The Munich Accelerator for Fission Fragments MAFF

    SciTech Connect

    Habs, D.; Gross, M.; Assmann, W.; Beck, L.; Grossmann, R.; Maier, H.-J.; Schumann, M.; Sewtz, M.; Szerypo, J.; Thirolf, P.G.; Kruecken, R.; Faestermann, T.; Maier-Komor, P.; Nebel, F.; Zech, E.; Hartung, P.; Stoepler, R.; Juettner, Ph.; Tralmer, F.L.

    2005-11-21

    The layout and status of MAFF at the Munich high flux reactor FRM-II is described. At MAFF 1014 fissions/s will be induced by thermal neutrons in a target with approx. 1 g of 235U. The situation is compared to the SPIRAL2 facility where 1014 fissions/s are expected by fast neutron fission in a target containing 5100 g of 238U. A comparison of the yields of SPIRAL2 and MAFF is performed to show the complementarity of the two ISOL-facilities for fission fragments. MAFF has approximately five times the beam intensities of SPIRAL2 for short-lived fission isotopes with lifetimes shorter than 5 s and thus will focus on the most neutron-rich nuclei, while SPIRAL2 has better perspectives for the more intense, less neutron-rich post-accelerated beams.A problem that also deserves attention is the production of {alpha} emitters, in particular plutonium. Here MAFF has the advantage to contain the Pu-producing 238U only as impurity not as the main fissile system. If SPIRAL2 would use 235U instead of 238U this problematic issue could be avoided at the cost of a further reduction in intensity of very neutron-rich fission fragments by a factor of 10. Finally new physics close to the classically doubly-magic nuclei 78Ni and 132Sn is described.

  5. Isospin dependence of fragment spectra in heavy/super-heavy colliding nuclei at intermediate energies

    NASA Astrophysics Data System (ADS)

    Chugh, Rajiv; Kumar, Rohit; Vinayak, Karan Singh

    2016-05-01

    Using isospin-dependent quantum molecular dynamics (IQMD) approach, we performed a theoretical investigation of the evolution of various kinds of fragments in heavy and superheavy-ion reactions in the intermediate/medium energy domain. We demonstrated direct impact of symmetry energy and Coulomb interactions on the evolution of fragments. Final fragment spectra (yields) obtained from the analysis of various heavy/super-heavy ion reactions at different reaction conditions show high sensitivity towards Coulomb interactions and less significant sensitivity to symmetry energy forms. No inconsistent pattern of fragment structure is obtained in case of super-heavy ion involved reactions for all the parameterizations of density dependence of symmetry energy.

  6. Fragmentation functions of the pion, kaon, and proton in the NLO approximation: Laplace transform approach

    NASA Astrophysics Data System (ADS)

    Zarei, M.; Taghavi-Shahri, F.; Tehrani, S. Atashbar; Sarbishei, M.

    2015-10-01

    Using the repeated Laplace transform, we find an analytical solution for Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations for extracting the pion, kaon, and proton fragmentation functions at next-to-leading-order approximation. We also study the symmetry breaking of the sea quarks fragmentation functions Dq¯ h(z ,Q2) and simply separate them according to their mass ratio. Finally, we calculate the total fragmentation functions of these hadrons and compare them with experimental data and those from global fits. Our results show a good agreement with the fragmentation functions obtained from global parametrizations as well as with the experimental data.

  7. 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.

  8. 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.

  9. 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.

  10. Economical technique for fragmentation testing

    NASA Technical Reports Server (NTRS)

    Smith, T. H., III; Snoke, B. A.

    1974-01-01

    Automatic rifle was modified for remote, single-shot use. To simulate statistically--determined fragment size from rocket-motor casing blunt-nosed bullet was made of same alloy. Cartridge was loaded with enough powder to make bullet reach target at same estimated velocity as shrapnel from rocket casing.

  11. 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. PMID:26496751

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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…

  19. Petrology of some lithic fragments from Luna 20.

    NASA Technical Reports Server (NTRS)

    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- to 500-micron 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. Twenty-seven 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 28 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.

  20. Energy production using fission fragment rockets

    NASA Astrophysics Data System (ADS)

    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 the efficiency if the fission fragment energy can be directly converted into electricity; reduction of the buildup of a fission fragment inventory in the reactor could avoid a Chernobyl type disaster; and collection of the fission fragments outside the reactor could simplify the waste disposal problem.

  1. Workflow Design Using Fragment Composition

    NASA Astrophysics Data System (ADS)

    Mosser, Sébastien; Blay-Fornarino, Mireille; France, Robert

    The Service-Oriented Architecture (Soa) paradigm supports the assembly of atomic services to create applications that implement complex business processes. Assembly can be accomplished by service orchestrations defined by Soa architects. The Adore method allows Soa architects to model complex orchestrations of services by composing models of smaller orchestrations called orchestration fragments. The Adore method can also be used to weave fragments that address new concerns into existing application models. In this paper we illustrate how the Adore method can be used to separate and compose process aspects in a Soa design of the Car Crash Crisis Management System. The paper also includes a discussion of the benefits and limitations of the Adore method.

  2. 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).

  3. 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

  4. 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.

  5. 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.

  6. Telomere Restriction Fragment (TRF) Analysis

    PubMed Central

    Mender, Ilgen; Shay, Jerry W.

    2016-01-01

    While telomerase is expressed in ~90% of primary human tumors, most somatic tissue cells except transiently proliferating stem-like cells do not have detectable telomerase activity (Shay and Wright, 1996; Shay and Wright, 2001). Telomeres progressively shorten with each cell division in normal cells, including proliferating stem-like cells, due to the end replication (lagging strand synthesis) problem and other causes such as oxidative damage, therefore all somatic cells have limited cell proliferation capacity (Hayflick limit) (Hayflick and Moorhead, 1961; Olovnikov, 1973). The progressive telomere shortening eventually leads to growth arrest in normal cells, which is known as replicative senescence (Shay et al., 1991). Once telomerase is activated in cancer cells, telomere length is stabilized by the addition of TTAGGG repeats to the end of chromosomes, thus enabling the limitless continuation of cell division (Shay and Wright, 1996; Shay and Wright, 2001). Therefore, the link between aging and cancer can be partially explained by telomere biology. There are many rapid and convenient methods to study telomere biology such as Telomere Restriction Fragment (TRF), Telomere Repeat Amplification Protocol (TRAP) (Mender and Shay, 2015b) and Telomere dysfunction Induced Foci (TIF) analysis (Mender and Shay, 2015a). In this protocol paper we describe Telomere Restriction Fragment (TRF) analysis to determine average telomeric length of cells. Telomeric length can be indirectly measured by a technique called Telomere Restriction Fragment analysis (TRF). This technique is a modified Southern blot, which measures the heterogeneous range of telomere lengths in a cell population using the length distribution of the terminal restriction fragments (Harley et al., 1990; Ouellette et al., 2000). This method can be used in eukaryotic cells. The description below focuses on the measurement of human cancer cells telomere length. The principle of this method relies on the lack of

  7. 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?

  8. HCD Fragmentation of Glycated Peptides.

    PubMed

    Keilhauer, Eva C; Geyer, Philipp E; Mann, Matthias

    2016-08-01

    Protein glycation is a concentration-dependent nonenzymatic reaction of reducing sugars with amine groups of proteins to form early as well as advanced glycation (end-) products (AGEs). Glycation is a highly disease-relevant modification but is typically only studied on a few blood proteins. To complement our blood proteomics studies in diabetics, we here investigate protein glycation by higher energy collisional dissociation (HCD) fragmentation on Orbitrap mass spectrometers. We established parameters to most efficiently fragment and identify early glycation products on in vitro glycated model proteins. Retaining standard collision energies does not degrade performance if the most dominant neutral loss of H6O3 is included into the database search strategy. Glycation analysis of the entire HeLa proteome revealed an unexpected intracellular preponderance for arginine over lysine modification in early and advanced glycation (end-) products. Single-run analysis from 1 μL of undepleted and unenriched blood plasma identified 101 early glycation sites as well as numerous AGE sites on diverse plasma proteins. We conclude that HCD fragmentation is well-suited for analyzing glycated peptides and that the diabetic status of patients can be directly diagnosed from single-run plasma proteomics measurements. PMID:27425404

  9. 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.

  10. 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.

  11. Bimodal Behavior of the Heaviest Fragment Distribution in Projectile Fragmentation

    SciTech Connect

    Bonnet, E.; Borderie, B.; Rivet, M. F.; Dayras, R.; Gagnon-Moisan, F.; Guinet, D.; Lautesse, P.; Parlog, M.; Rosato, E.; Vigilante, M.

    2009-08-14

    The charge distribution of the heaviest fragment detected in the decay of quasiprojectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in nonextensive systems. In this Letter, we present new analyses of experimental data from Au on Au collisions at 60, 80, and 100 MeV/nucleon showing that bimodality is largely independent of the data selection procedure and of entrance channel effects. An estimate of the latent heat of the transition is extracted.

  12. 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.

  13. The fragmentation process at HERMES

    SciTech Connect

    Maiheu, B.

    2005-10-06

    In semi-inclusive deep-inelastic scattering one can study the fragmentation process of partons by extracting multiplicity distributions for the resulting hadrons. At the HERMES experiment a unique possibility exists to study this hadronization at a {radical}(s) of 7.2 GeV. Making full use of the hadron identification capabilities of a Ring Imaging Cerenkov (RICH) detector, we were able to extract charge-separated pion and kaon multiplicities. Significant effort was put reducing the model dependence of the result by tuning the used MC generator and using an unfolding method to correct for experimental inefficiencies and migration of events due to both radiative and detector smearing.

  14. Fragmentation alters stream fish community structure in dendritic ecological networks.

    PubMed

    Perkin, Joshuah S; Gido, Keith B

    2012-12-01

    Effects of fragmentation on the ecology of organisms occupying dendritic ecological networks (DENs) have recently been described through both conceptual and mathematical models, but few hypotheses have been tested in complex, real-world ecosystems. Stream fishes provide a model system for assessing effects of fragmentation on the structure of communities occurring within DENs, including how fragmentation alters metacommunity dynamics and biodiversity. A recently developed habitat-availability measure, the "dendritic connectivity index" (DCI), allows for assigning quantitative measures of connectivity in DENs regardless of network extent or complexity, and might be used to predict fish community response to fragmentation. We characterized stream fish community structure in 12 DENs in the Great Plains, USA, during periods of dynamic (summer) and muted (fall) discharge regimes to test the DCI as a predictive model of fish community response to fragmentation imposed by road crossings. Results indicated that fish communities in stream segments isolated by road crossings had reduced species richness (alpha diversity) relative to communities that maintained connectivity with the surrounding DEN during summer and fall. Furthermore, isolated communities had greater dissimilarity (beta diversity) to downstream sites notisolated by road crossings during summer and fall. Finally, dissimilarity among communities within DENs decreased as a function of increased habitat connectivity (measured using the DCI) for summer and fall, suggesting that communities within highly connected DENs tend to be more homogeneous. Our results indicate that the DCI is sensitive to community effects of fragmentation in riverscapes and might be used by managers to predict ecological responses to changes in habitat connectivity. Moreover, our findings illustrate that relating structural connectivity of riverscapes to functional connectivity among communities might aid in maintaining metacommunity

  15. 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.

  16. Velocity distribution of fragments of catastrophic impacts

    NASA Technical Reports Server (NTRS)

    Takagi, Yasuhiko; Kato, Manabu; Mizutani, Hitoshi

    1992-01-01

    Three dimensional velocities of fragments produced by laboratory impact experiments were measured for basalts and pyrophyllites. The velocity distribution of fragments obtained shows that the velocity range of the major fragments is rather narrow, at most within a factor of 3 and that no clear dependence of velocity on the fragment mass is observed. The NonDimensional Impact Stress (NDIS) defined by Mizutani et al. (1990) is found to be an appropriate scaling parameter to describe the overall fragment velocity as well as the antipodal velocity.

  17. Coagulation and fragmentation with discrete mass loss

    NASA Astrophysics Data System (ADS)

    Blair, Pamela N.; Lamb, Wilson; Stewart, Iain W.

    2007-05-01

    A nonlinear integro-differential equation that models a coagulation and multiple fragmentation process in which discrete fragmentation mass loss can occur is examined using the theory of strongly continuous semigroups of operators. Under the assumptions that the coagulation kernel is bounded and the fragmentation rate function a satisfies a linear growth condition, global existence and uniqueness of solutions that lose mass in accordance with the model are established. In the case when no coagulation is present and the fragmentation process is governed by power-law kernels, an explicit formula is given for the substochastic semigroup associated with the resulting mass-loss fragmentation equation.

  18. Kinetic energies of cluster fragments in ternary fission of 252 Cf

    NASA Astrophysics Data System (ADS)

    Vijayaraghavan, K. R.; von Oertzen, W.; Balasubramaniam, M.

    2012-03-01

    The kinetic energy distribution and potential energies of fragments from the collinear cluster tripartition (CCT), the "true" ternary fission of 252Cf, have been calculated. It is assumed that the breakup of the nucleus into three fragments happens sequentially in two steps from a hyper-deformed shape. In the first step a first neck rupture occurs of the parent radioactive nucleus, forming two fragments (one of them is usually 132Sn) and, in the second step, one of the two fragments breaks into two other fragments, resulting finally in three fragments (the experiment is based on a binary coincidence where a missing mass is determined). We show the result for the principal combination of the three spherical fragments (semi-magic isotopes of Sn, Ca, Ni) observed recently experimentally. These isotopes are clusters with high Q -values, which produce the highest yields in the ternary fission bump. It is shown that the kinetic energies of the middle fragments have very low values, making their experimental detection quite difficult. This fact explains why the direct detection of true ternary fission with three fragments heavier than A > 40 has escaped experimental observation.

  19. 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.

  20. Nonlinear inflaton fragmentation after preheating

    SciTech Connect

    Felder, Gary N.; Kofman, Lev

    2007-02-15

    We consider the nonlinear dynamics of inflaton fragmentation during and after preheating in the simplest model of chaotic inflation. While the earlier regime of parametric resonant particle production and the later turbulent regime of interacting fields evolving towards equilibrium are well identified and understood, the short intermediate stage of violent nonlinear dynamics remains less explored. Lattice simulations of fully nonlinear preheating dynamics show specific features of this intermediate stage: occupation numbers of the scalar particles are peaked, scalar fields become significantly nongaussian and the field dynamics become chaotic and irreversible. Visualization of the field dynamics in position space reveals that nonlinear interactions generate nongaussian inflaton inhomogeneities with very fast growing amplitudes. The peaks of the inflaton inhomogeneities coincide with the peaks of the scalar field(s) produced by parametric resonance. When the inflaton peaks reach their maxima, they stop growing and begin to expand. The subsequent dynamics is determined by expansion and superposition of the scalar waves originating from the peaks. Multiple wave superposition results in phase mixing and turbulent wave dynamics. Thus, the short intermediate stage is defined by the formation, expansion and collision of bubblelike field inhomogeneities associated with the peaks of the original gaussian field. This process is qualitatively similar to the bubblelike inflaton fragmentation that occurs during tachyonic preheating after hybrid or new inflation.

  1. 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.

  2. Structures of endothiapepsin-fragment complexes from crystallographic fragment screening using a novel, diverse and affordable 96-compound fragment library.

    PubMed

    Huschmann, Franziska U; Linnik, Janina; Sparta, Karine; Ühlein, Monika; Wang, Xiaojie; Metz, Alexander; Schiebel, Johannes; Heine, Andreas; Klebe, Gerhard; Weiss, Manfred S; Mueller, Uwe

    2016-05-01

    Crystallographic screening of the binding of small organic compounds (termed fragments) to proteins is increasingly important for medicinal chemistry-oriented drug discovery. To enable such experiments in a widespread manner, an affordable 96-compound library has been assembled for fragment screening in both academia and industry. The library is selected from already existing protein-ligand structures and is characterized by a broad ligand diversity, including buffer ingredients, carbohydrates, nucleotides, amino acids, peptide-like fragments and various drug-like organic compounds. When applied to the model protease endothiapepsin in a crystallographic screening experiment, a hit rate of nearly 10% was obtained. In comparison to other fragment libraries and considering that no pre-screening was performed, this hit rate is remarkably high. This demonstrates the general suitability of the selected compounds for an initial fragment-screening campaign. The library composition, experimental considerations and time requirements for a complete crystallographic fragment-screening campaign are discussed as well as the nine fully refined obtained endothiapepsin-fragment structures. While most of the fragments bind close to the catalytic centre of endothiapepsin in poses that have been observed previously, two fragments address new sites on the protein surface. ITC measurements show that the fragments bind to endothiapepsin with millimolar affinity. PMID:27139825

  3. The fragmentation of expanding shells - III. Oligarchic accretion and the mass spectrum of fragments

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    We use smoothed particle hydrodynamics (SPH) simulations to investigate the gravitational fragmentation of expanding shells through the linear and non-linear regimes. The results are analysed using spherical-harmonic decomposition to capture the initiation of structure during the linear regime, the potential-based method of Smith et al. to follow the development of clumps in the mildly non-linear regime and sink particles to capture the properties of the final bound objects during the highly non-linear regime. In the early, mildly non-linear phase of fragmentation, we find that the clump mass function still agrees quite well with the mass function predicted by the analytic model. However, the sink mass function is quite different, in the sense of being skewed towards high-mass objects. This is because, once the growth of a condensation becomes non-linear, it tends to be growing non-competitively from its own essentially separate reservoir; we call this oligarchic accretion.

  4. 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. PMID:26826800

  5. Fragmentation and Coagulation in Supramolecular (Co)polymerization Kinetics

    PubMed Central

    2016-01-01

    The self-assembly of molecular building blocks into one-dimensional supramolecular architectures has opened up new frontiers in materials science. Due to the noncovalent interactions between the monomeric units, these architectures are intrinsically dynamic, and understanding their kinetic driving forces is key to rationally programming their morphology and function. To understand the self-assembly dynamics of supramolecular polymerizations (SP), kinetic models based on aggregate growth by sequential monomer association and dissociation have been analyzed. However, fragmentation and coagulation events can also play a role, as evident from studies on peptide self-assembly and the fact that aggregations can be sensitive to mechanical agitations. Here, we analyze how fragmentation and coagulation events influence SP kinetics by theoretical analysis of self-assembling systems of increasing complexity. Our analysis starts with single-component systems in which aggregates are able to grow via an isodesmic or cooperative nucleation–elongation mechanism. Subsequently, equilibration dynamics in cooperative two-component supramolecular copolymerizations are investigated. In the final part, we reveal how aggregate growth in the presence of competing, kinetically controlled pathways is influenced by fragmentation and coagulation reactions and reveal how seed-induced growth can give rise to block copolymers. Our analysis shows how fragmentation and coagulation reactions are able to modulate SP kinetics in ways that are highly system dependent. PMID:27163054

  6. Robustness of optimal random searches in fragmented environments

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    The random search problem is a challenging and interdisciplinary topic of research in statistical physics. Realistic searches usually take place in nonuniform heterogeneous distributions of targets, e.g., patchy environments and fragmented habitats in ecological systems. Here we present a comprehensive numerical study of search efficiency in arbitrarily fragmented landscapes with unlimited visits to targets that can only be found within patches. We assume a random walker selecting uniformly distributed turning angles and step lengths from an inverse power-law tailed distribution with exponent μ . Our main finding is that for a large class of fragmented environments the optimal strategy corresponds approximately to the same value μopt≈2 . Moreover, this exponent is indistinguishable from the well-known exact optimal value μopt=2 for the low-density limit of homogeneously distributed revisitable targets. Surprisingly, the best search strategies do not depend (or depend only weakly) on the specific details of the fragmentation. Finally, we discuss the mechanisms behind this observed robustness and comment on the relevance of our results to both the random search theory in general, as well as specifically to the foraging problem in the biological context.

  7. A modified technique on the reattachment of permanent tooth fragments following dental trauma. Case report.

    PubMed

    Arapostathis, Konstantinos; Arhakis, Aristidis; Kalfas, Sotiris

    2005-01-01

    Fractured anterior teeth can be restored by adhesive bonding of the fractured fragment to the remaining tooth structure. One of the major challenges for the practitioner treating traumatized anterior teeth with immediate fragment reattachment is disguising the fracture line, through the correct use of masking and restorative resins to make the restorations imperceptible to the eye as well as improve the retention of the restoration. This paper discusses a modified technique for reattaching a permanent tooth fragment following dental trauma. The initial procedure involved simple reattachment using light cured composite resin between the fragment and the remnant part of the tooth, without additional preparation. The surplus resin was spread across it in an attempt to optimize marginal seal and improve the aesthetics of the restoration. Finally, after taking into account the occlusion, the lingual surfaces of the teeth were veneered with microfilled composite to improve the retention of the reattached fragments. PMID:16302596

  8. Novel strategy for three-dimensional fragment-based lead discovery.

    PubMed

    Yuan, Haoliang; Lu, Tao; Ran, Ting; Liu, Haichun; Lu, Shuai; Tai, Wenting; Leng, Ying; Zhang, Weiwei; Wang, Jian; Chen, Yadong

    2011-04-25

    Fragment-based drug design (FBDD) is considered a promising approach in lead discovery. However, for a practical application of this approach, problems remain to be solved. Hence, a novel practical strategy for three-dimensional lead discovery is presented in this work. Diverse fragments with spatial positions and orientations retained in separately adjacent regions were generated by deconstructing well-aligned known inhibitors in the same target active site. These three-dimensional fragments retained their original binding modes in the process of new molecule construction by fragment linking and merging. Root-mean-square deviation (rmsd) values were used to evaluate the conformational changes of the component fragments in the final compounds and to identify the potential leads as the main criteria. Furthermore, the successful validation of our strategy is presented on the basis of two relevant tumor targets (CDK2 and c-Met), demonstrating the potential of our strategy to facilitate lead discovery against some drug targets. PMID:21438547

  9. SPY: A new scission point model based on microscopic ingredients to predict fission fragments properties

    NASA Astrophysics Data System (ADS)

    Lemaître, J.-F.; Dubray, N.; Hilaire, S.; Panebianco, S.; Sida, J.-L.

    2013-12-01

    Our purpose is to determine fission fragments characteristics in a framework of a scission point model named SPY for Scission Point Yields. This approach can be considered as a theoretical laboratory to study fission mechanism since it gives access to the correlation between the fragments properties and their nuclear structure, such as shell correction, pairing, collective degrees of freedom, odd-even effects. Which ones are dominant in final state? What is the impact of compound nucleus structure? The SPY model consists in a statistical description of the fission process at the scission point where fragments are completely formed and well separated with fixed properties. The most important property of the model relies on the nuclear structure of the fragments which is derived from full quantum microscopic calculations. This approach allows computing the fission final state of extremely exotic nuclei which are inaccessible by most of the fission model available on the market.

  10. 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.

  11. Knowledge-based fragment binding prediction.

    PubMed

    Tang, Grace W; Altman, Russ B

    2014-04-01

    Target-based drug discovery must assess many drug-like compounds for potential activity. Focusing on low-molecular-weight compounds (fragments) can dramatically reduce the chemical search space. However, approaches for determining protein-fragment interactions have limitations. Experimental assays are time-consuming, expensive, and not always applicable. At the same time, computational approaches using physics-based methods have limited accuracy. With increasing high-resolution structural data for protein-ligand complexes, there is now an opportunity for data-driven approaches to fragment binding prediction. We present FragFEATURE, a machine learning approach to predict small molecule fragments preferred by a target protein structure. We first create a knowledge base of protein structural environments annotated with the small molecule substructures they bind. These substructures have low-molecular weight and serve as a proxy for fragments. FragFEATURE then compares the structural environments within a target protein to those in the knowledge base to retrieve statistically preferred fragments. It merges information across diverse ligands with shared substructures to generate predictions. Our results demonstrate FragFEATURE's ability to rediscover fragments corresponding to the ligand bound with 74% precision and 82% recall on average. For many protein targets, it identifies high scoring fragments that are substructures of known inhibitors. FragFEATURE thus predicts fragments that can serve as inputs to fragment-based drug design or serve as refinement criteria for creating target-specific compound libraries for experimental or computational screening. PMID:24762971

  12. Magma fragmentation speed: an experimental determination

    NASA Astrophysics Data System (ADS)

    Spieler, O.; Dingwell, D. B.; Alidibirov, M.

    2004-01-01

    The propagation speed of a fragmentation front, combined with the ascent velocity of magma is, in all likelihood, a controlling factor in the dynamics of explosive volcanic eruptions. Direct measurement of the 'fragmentation speed' in natural systems appears to be impossible at present. Fortunately, laboratory experiments can provide information on the propagation speed of the fragmentation front. Here we present the results of fragmentation speed determinations using a so-called 'fragmentation bomb'. These are, to the best of our knowledge, the first in situ fragmentation speed determinations performed on magma. Natural magma samples (Merapi basaltic andesite, Mount St. Helens dacite and Unzen dacite) have been investigated in the temperature range of 20-950°C and at pressures up to 25 MPa. Two techniques have been employed. Firstly, in experiments at 20°C, dynamic pressure transducers were placed above and below the magma samples and the fragmentation speed of the magma sample was derived from an analysis of the decompression curves. Secondly, at elevated temperatures, an alternative technique was introduced and successfully employed. This involved the severing via fragmentation of conducting wires placed within the samples at various heights. Fragmentation speeds are very low, falling in the range of 2-70 m/s and increasing with an increase in the magnitude of the decompression step responsible for the fragmentation. The first high-temperature determination seems consistent with low-temperature results. Implications for explosive volcanism are discussed briefly.

  13. Influence of different liquid-drop-based bindings on lighter mass fragments and entropy production

    NASA Astrophysics Data System (ADS)

    Kumar, Rohit; Shivani; Gautam, Sakshi

    2016-04-01

    We study the production of lighter fragments and associated phenomena within the Quantum Molecular Dynamics (QMD) model. The Minimum Spanning Tree (MST) method is used to identify the pre-clusters. The final stable fragments were identified by imposing binding energy criteria on the fragments formed using the MST method. The effect of different binding energy criteria was investigated by employing various liquid-drop-based binding energy formulae. Though light clusters show significant effect of different binding energies, their associated phenomenon, i.e. entropy production is insensitive towards different binding energy criteria.

  14. Velocities of fragments from bursting gas reservoirs.

    NASA Technical Reports Server (NTRS)

    Taylor, D. E.; Price, C. F.

    1971-01-01

    A solution is obtained from a simplified approach for the problem of the motion of two fragments driven into a vacuum after rupture of a container filled with gas. Following rupture, the two container fragments are driven in opposite directions. From the separation developed between the moving fragments, the originally contained gas escapes to the vacuum, perpendicular to the direction of motion of the fragments, and with locally sonic velocity. The present solution removes two restrictions of an earlier similar approach: (1) the speed of the gas within the original volume (and consequently, by inference, that of the fragments) is small relative to the sonic escape velocity, and (2) the volume between the separating fragments while they are accelerating undergoes negligible change from the original volume.

  15. 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.

  16. Fragmentation of an axially impacted slender rod

    NASA Astrophysics Data System (ADS)

    Ji, W.; Waas, A. M.

    2010-02-01

    Motivated by experimental results on the dynamic buckling and fragmentation of a vertical column impacted by a falling mass, results from an analytical model for dynamic buckling which considers the dynamic interaction between the axial column deformation and the out-of-plane buckling displacements are used to interpret the fragmentation process and the resulting fragment lengths. It is shown that a critical time exists for the rod to undergo fragmentation. At this critical time, the rod deforms in a modulated pattern of waves, setting up the stage for the ensuing fragmentation as a result of induced large curvatures that exceed the critical bending strain of the rod material. The resulting fragment length distributions, which show two characteristics peaks at \\frac{\\lambda}{2} and \\frac{\\lambda}{4} , where λ is a characteristic half-wavelength, are found to compare favorably with the experimental results.

  17. 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.

  18. Fragmentation statistics from Eulerian hydrocode calculations

    SciTech Connect

    Trucano, T.G.; Grady, D.E.; McGlaun, J.M.

    1989-01-01

    In this paper, we discuss a procedure for computing discrete fragmentation information for terminal ballistics events from the continuum data that emerges from two-dimensional Eulerian hydrocode simulations of these events. The present examples deal with the normal impact of lead cylinders on lead plates at velocities below 1600 m/s. In this regime, the resulting debris is almost exclusively solid lead fragments. We have experimental data of sufficient accuracy to evaluate the extraction of such fragmentation information from code simulations. The problem is interesting because the observed distribution of fragment size would require extreme subgrid resolution in the hydrocode if the statistics were computed directly. Our approach is different. We ask whether or not the general continuum description predicted by the code contains enough information to allow coupling of an analytic fragmentation theory that successfully predicts fragmentation statistics. We believe that this approach is valid, and discuss our current success in matching experimental data. 10 refs., 7 figs., 5 tabs.

  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. Aggregation of β-amyloid fragments

    NASA Astrophysics Data System (ADS)

    Meinke, Jan H.; Hansmann, Ulrich H. E.

    2007-01-01

    The authors study the folding and aggregation of six chains of the β-amyloid fragment 16-22 using Monte Carlo simulations. While the isolated fragment prefers a helical form at room temperature, in the system of six interacting fragments one observes both parallel and antiparallel β sheets below a crossover temperature Tx≈420K. The antiparallel sheets have lower energy and are therefore more stable. Above the nucleation temperature the aggregate quickly dissolves into widely separated, weakly interacting chains.

  1. 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.

  2. Cylinder Fragmentation Using Gas Gun Techniques

    NASA Astrophysics Data System (ADS)

    Thornhill, T. F.; Reinhart, W. D.; Chhabildas, L. C.; Grady, D. E.; Wilson, L. T.

    2002-07-01

    In this study an experimental technique for study of cylinder fracture fragmentation characteristics has been developed on a two-stage light gas gun. This test method allows the study of cylinder fracture fragmentation in a laboratory environment under well-controlled loading conditions. Application of this technique allows measure of failure strain, strain rates, expansion velocity, and fragmentation toughness. Results of several experiments on Aermet steel are presented.

  3. Separation of DNA restriction fragments using capillary electrophoresis

    SciTech Connect

    Chan, K.C.; Whang, Chenwen; Yeung, E.S. )

    1993-01-01

    Gel-filled and non-gel' capillary electrophoresis (CE) have been applied to the separation of various DNA restriction fragments. 30% HydroLink gel, polymerized inside a 75[mu]m i.d. fused-silica capillary, was used in the gel-filled CE. Primary results show that the HL capillary gel was simple to cast, and its stability was reasonably good under the running conditions. In the non-gel CE experiment, a buffer containing the sieving additive hydroxypropylmethyl cellulose was used to affect the size-dependent separation. The use of GC capillaries eliminates the inconvenience of separately coating the capillary walls for efficient non-gel separation. Finally, the authors demonstrate that it is feasible to detect native DNA fragments using indirect fluorometry in non-gel capillary electrophoresis.

  4. Emission of intermediate mass fragments using γ-spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Gómez del Campo, J.; Baktash, C.; Jin, H.-Q.; Rudolph, D.; D'onofrio, A.; Terrasi, F.; de Angelis, G.; de Poli, M.; Fahlander, C.; Gadea, A.; Napoli, D. R.; Pan, Q.; Spolaore, P.; de Acuna, L.; Bazzacco, D.; Lunardi, S.; Pavan, P.; Rossi-Alvarez, C.; Buscemi, A.; Zanon, R.; de Rosa, A.; Campajola, L.; La Commara, M.; Inglima, G.; Roca, V.; Romano, M.; Sandoli, M.; Romoli, M.; Ordine, A.; Pierroutsakou, D.

    1998-02-01

    Intermediate mass fragments (IMF) and light particles emitted from the 58Ni+58Ni reaction at a beam energy of 375 MeV have been studied. The fragments and light particles were measured in coincidence with 4π γ-ray spectrometer. The Z=6 (C) kinetic energy spectra and the distribution of the final nuclei in coincidence with the emitted C are well described by Hauser-Feshbach calculations extended to many channels. A detailed study of C-γ and 3α-γ correlations indicate a strong selectivity of the IMF decay. Our results indicate that the IMF can populate nuclei that are not accessible via multiple light particle (Z<3) emission and, thus, are useful for nuclear structure studies.

  5. 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.

  6. Jet production and fragmentation properties in deep inelastic muon scattering

    NASA Astrophysics Data System (ADS)

    Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Conrad, J.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Drobnitzki, M.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Ftàčnik, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffre, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, A.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Pietrzyk, U.; Pönsgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlabböhmer, A.; Schiemann, H.; Schmitz, N.; Schneegans, M.; Scholz, M.; Schröder, T.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thénard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.; Wolf, G.; Ziemons, K.

    1987-12-01

    Results are presented from a study of deep inelastic 280 GeV muon-nucleon interactions on the transverse momenta and jet properties of the final state hadrons. The results are analysed in a way which attempts to separate the contributions of hard and soft QCD effects from those that arise from the fragmentation process. The fragmentation models with which the data are compared are the Lund string model, the independent jet model, the QCD parton shower model including soft gluon interference effects, and the firestring model. The discrimination between these models is discussed. Various methods of analysis of the data in terms of hard QCD processes are presented. From a study of the properties of the jet profiles a value of α s , to leading order, is determined using the Lund string model, namely α s =0.29±0.01 (stat.) ±0.02 (syst.), for Q 2˜20 GeV2.

  7. Quantification of airway deposition of intact and fragmented pollens.

    PubMed

    Horváth, Alpár; Balásházy, Imre; Farkas, Arpád; Sárkány, Zoltán; Hofmann, Werner; Czitrovszky, Aladár; Dobos, Erik

    2011-12-01

    Although pollen is one of the most widespread agents that can cause allergy, its airway transport and deposition is far from being fully explored. The objective of this study was to characterize the airway deposition of pollens and to contribute to the debate related to the increasing number of asthma attacks registered after thunderstorms. For the quantification of the deposition of inhaled pollens in the airways computer simulations were performed. Our results demonstrated that smaller and fragmented pollens may penetrate into the thoracic airways and deposit there, supporting the theory that fragmented pollen particles are responsible for the increasing incidence of asthma attacks following thunderstorms. Pollen deposition results also suggest that children are the most exposed to the allergic effects of pollens. Finally, pollens between 0.5 and 20 μm deposit more efficiently in the lung of asthmatics than in the healthy lung, especially in the bronchial region. PMID:21563012

  8. 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.

  9. 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.

  10. Isotope Labeling Study of Retinal Chromophore Fragmentation.

    PubMed

    Musbat, Lihi; Nihamkin, Maria; Ytzhak, Shany; Hirshfeld, Amiram; Friedman, Noga; Dilger, Jonathan M; Sheves, Mordechai; Toker, Yoni

    2016-04-28

    Previous studies have shown that the gas-phase fragmentation of the retinal chromophore after S0-S1 photoexcitation results in a prominent fragment of mass 248 which cannot be explained by the cleavage of any single bond along the polyene chain. It was therefore theorized that the fragmentation mechanism involves a series of isomerizations and cyclization processes, and two mechanisms for these processes were suggested. Here we used isotope labeling MS-MS to provide conclusive support for the fragmentation mechanism suggested by Coughlan et al. (J. Phys. Chem. Lett. 2014, 5, 3195). PMID:27046667

  11. Electron-impact-induced tryptophan molecule fragmentation

    NASA Astrophysics Data System (ADS)

    Tamuliene, Jelena; Romanova, Liudmila G.; Vukstich, Vasyl S.; Papp, Alexander V.; Snegursky, Alexander V.

    2015-01-01

    The fragmentation of a gas-phase tryptophan molecule by a low-energy (<70 eV) electron impact was studied both experimentally and theoretically. Various positively charged fragments were observed and analyzed. A special attention was paid to the energy characteristics of the ionic fragment yield. The geometrical parameters of the initial molecule rearrangement were also analyzed. The fragmentation observed was due to either a simple bond cleavage or more complex reactions involving molecular rearrangements. Contribution to the Topical Issue "Elementary Processes with Atoms and Molecules in Isolated and Aggregated States", edited by Friedrich Aumayr, Bratislav Marinkovic, Stefan Matejcik, John Tanis and Kurt H. Becker.

  12. 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

  13. Thermodynamic stability and flexibility characteristics of antibody fragment complexes

    PubMed Central

    Li, Tong; Verma, Deeptak; Tracka, Malgorzata B.; Casas-Finet, Jose; Livesay, Dennis R.; Jacobs, Donald J.

    2015-01-01

    Free energy landscapes, backbone flexibility and residue-residue couplings for being co-rigid or co-flexible are calculated from the minimal Distance Constraint Model (mDCM) on an exploratory dataset consisting of VL, scFv and Fab antibody fragments. Experimental heat capacity curves are reproduced markedly well, and an analysis of quantitative stability/flexibility relationships (QSFR) is applied to a representative VL domain and several complexes in the scFv and Fab forms. Global flexibility in the denatured ensemble typically decreases in the larger complexes due to domain-domain interfaces. Slight decreases in global flexibility also occur in the native state of the larger fragments, but with a concurrent large increase in correlated flexibility. Typically, a VL fragment has more co-rigid residue pairs when isolated compared to the scFv and Fab forms, where correlated flexibility appears upon complex formation. This context dependence on residue-residue couplings in the VL domain across length scales of a complex is consistent with the evolutionary hypothesis of antibody maturation. In comparing two scFv mutants with similar thermodynamic stability, local and long-ranged changes in backbone flexibility are observed. In the case of anti-p24 HIV-1 Fab, a variety of QSFR metrics were found to be atypical, which includes comparatively greater co-flexibility in the VH domain and less co-flexibility in the VL domain. Interestingly, this fragment is the only example of a polyspecific antibody in our dataset. Finally, the mDCM method is extended to cases where thermodynamic data is incomplete, enabling high throughput QSFR studies on large numbers of antibody fragments and their complexes. PMID:23855672

  14. A new Parameter to Determine Degree of Fragmentation of Rockslides

    NASA Astrophysics Data System (ADS)

    Thordén Haug, Øystein; Rosenau, Matthias; Leever, Karen; Oncken, Onno

    2015-04-01

    When a rock slope fails, the consequent transport of materials depends on the bulk state of the rock mass. For example, if the rock mass collapses and disintegrates into a granular material, appropriate transport models need to consider the physics of granular material to determine the rock mass transport and final travel length. In contrast, should the failure occur on a well-defined failure zone and the block have sufficient cohesion, the rock mass can be considered as an elastic block. However, were the block to experience high stresses during its travel, for example from impacting the ground after free falling, it may still fragment and turn into a granular material. Determination of which systems immediately collapses, which remain intact and which is likely to fragments during transport is of key importance to choose appropriate transport models. To do this requires a quantitative description of which systems will undergo fragmentation and which will not. To simplify matters somewhat, we only consider the question whether or not the material experiences enough stresses during its travel for fragmentation to occur. Fragmentation of a rock mass is determined by numerous variables such as its intact rock strength, pre-existing fracture density, size and geometry, as well as the topography of the slope. However, as it is not yet understood how these variables interact, such a description is still lacking. Here we suggest such a description for a special case of a cuboid sample traveling over a slope break. We perform a series of tests using a newly developed analogue rock material of which the bulk material cohesion can be controlled. In the tests, a cuboid shaped sample of the analogue material is released down a slope of 45° at a height of 0.7 m and impacts on a horizontal plate. The tests show that the degree of fragmentation depends on aspect ratio, kinetic energy and material strength of the samples. To collapse of the data from all three variables, we

  15. Statistical theory of fragmentation processes

    SciTech Connect

    Dienes, J.K.

    1984-01-01

    The goal of the work reviewed here is a theory of material behavior accounting for the average deformation that results from the opening, shear, growth and coalescence of an ensemble of microcracks. A concomitant is the calculation of permeability from crack structure. The first part of this paper summarizes previous developments. In particular, the initial work on this problem made use of a linear Liouville equation to characterize the change in crack distribution resulting from crack growth and coalescence. Straightforward analytic solutions to this equation were possible because the mean free path of cracks was assumed constant. Though this assumption is useful for the early stages of crack growth, increasing crack size reduces the mean free path in the later stages of fragmentation. This problem is addressed in the second part of this paper. The governing (nonlinear) Liouville equation is derived therein, and it is shown that it can be reduced to an ordinary differential equation of third order involving only a single parameter, ..beta... This equation has now been solved numerically to determine the limiting value of the mean free path as a function of ..beta.., and the results are presented in graphical form. In the third part of this paper prospects for further developments are briefly discussed.

  16. 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.

  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.

    1993-01-01

    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.

  18. Waves in fragmented geomaterials with impact attenuation

    NASA Astrophysics Data System (ADS)

    Dyskin, Arcady; Pasternak, Elena

    2016-04-01

    Attenuation of waves in geomaterials, such as seismic waves is usually attributed to energy dissipation due to the presence of viscous fluid and/or viscous cement between the constituents. In fragmented geomaterials such as blocky rock mass there is another possible source of energy dissipation - impacting between the fragments. This can be characterised by the coefficient of restitution, which is the ratio between the rotational velocities after and before the impact. In particular, this manifests itself in the process of mutual rotations of the fragments/blocks, whereby in the process of oscillation different ends of the contacting faces of the fragments are impacting. During the rotational oscillations the energy dissipation is concentrated in the neutral position that is the one in which the relative rotation between two fragments is zero. We show that in a simple system of two fragments this dissipation is equivalent, in a long run, to the presence of viscous damper between the fragments (the Voigt model of visco-elasticity). Generalisation of this concept to the material consisting of many fragments leads to a Voigt model of wave propagation where the attenuation coefficient is proportional to the logarithm of restitution coefficient. The waves in such a medium show slight dispersion caused by damping and strong dependence of the attenuation on the wave frequency.

  19. Sizing of DNA fragments by flow cytometry

    NASA Astrophysics Data System (ADS)

    Johnson, Mitchell E.; Goodwin, Peter M.; Ambrose, W. Patrick; Martin, John C.; Marrone, Babetta L.; Jett, James H.; Keller, Richard A.

    1993-06-01

    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.

  20. 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.

  1. 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.

  2. Missing Fragments: Detecting Cooperative Binding in Fragment-Based Drug Design

    PubMed Central

    2012-01-01

    The aim of fragment-based drug design (FBDD) is to identify molecular fragments that bind to alternate subsites within a given binding pocket leading to cooperative binding when linked. In this study, the binding of fragments to human phenylethanolamine N-methyltransferase is used to illustrate how (a) current protocols may fail to detect fragments that bind cooperatively, (b) theoretical approaches can be used to validate potential hits, and (c) apparent false positives obtained when screening against cocktails of fragments may in fact indicate promising leads. PMID:24900472

  3. Missing fragments: detecting cooperative binding in fragment-based drug design.

    PubMed

    Nair, Pramod C; Malde, Alpeshkumar K; Drinkwater, Nyssa; Mark, Alan E

    2012-04-12

    The aim of fragment-based drug design (FBDD) is to identify molecular fragments that bind to alternate subsites within a given binding pocket leading to cooperative binding when linked. In this study, the binding of fragments to human phenylethanolamine N-methyltransferase is used to illustrate how (a) current protocols may fail to detect fragments that bind cooperatively, (b) theoretical approaches can be used to validate potential hits, and (c) apparent false positives obtained when screening against cocktails of fragments may in fact indicate promising leads. PMID:24900472

  4. Differential localization of processed fragments of Plasmodium falciparum serine repeat antigen and further processing of its N-terminal 47 kDa fragment.

    PubMed

    Li, Jie; Mitamura, Toshihide; Fox, Barbara A; Bzik, David J; Horii, Toshihiro

    2002-12-01

    The serine repeat antigen (SERA) of Plasmodium falciparum is a blood stage malaria vaccine candidate. It has been shown that 120 kDa SERA was proteolytically processed into N-terminal 47 kDa fragment (P47), central 56 kDa fragment (P56) that was further converted to 50 kDa (P50), and C-terminal 18 kDa fragment (P18). Here, we have examined the processing of SERA and the localization of its processed fragments by using mouse antibodies directed against recombinant proteins corresponding to different domains of SERA. Western blot analysis showed that all the processing events occurred inside parasitized erythrocytes at the stage just prior to the schizont rupture, that P47 was further processed into two 25 kDa fragments and that the two fragments, which were linked to P18 through disulfide bonds, were associated with the merozoite. In contrast, P50 was completely shed into culture medium and absent from the merozoite. This observation was further supported by the results of indirect immunofluorescence assay. These results could account for the findings that antibodies against P47 were inhibitory to the parasite growth in vitro but those against P50 were not. Finally, we demonstrated that the further processing of P47 is allelic type-dependent. The results of the present study would help in vaccine designing based on SERA. PMID:12421632

  5. DRAGON: Monte Carlo Generator of Particle Production from a Fragmented Fireball in Ultrarelativistic Nuclear Collisions

    NASA Astrophysics Data System (ADS)

    Tomasik, Boris

    2010-11-01

    A Monte Carlo generator of the final state of hadrons emitted from an ultrarelativistic nuclear collision is introduced. An important feature of the generator is a possible fragmentation of the fireball and emission of the hadrons from fragments. Phase space distribution of the fragments is based on the blast wave model extended to azimuthally non-symmetric fireballs. Parameters of the model can be tuned and this allows to generate final states from various kinds of fireballs. A facultative output in the OSCAR1999A format allows for a comprehensive analysis of phase-space distributions and/or use as an input for an afterburner. DRAGON's purpose is to produce artificial data sets which resemble those coming from real nuclear collisions provided fragmentation occurs at hadronisation and hadrons are emitted from fragments without any further scattering. Its name, DRAGON, stands for DRoplet and hAdron GeneratOr for Nuclear collisions. In a way, the model is similar to THERMINATOR, with the crucial difference that emission from fragments is included.

  6. Recent results from the PEP4-TPC on quark fragmentation

    SciTech Connect

    Hofmann, W.

    1983-11-12

    The physics goals for the PEP-4/PEP-9 experiment concentrate on two areas: the fragmentation properties of quarks and gluons produced in e+e- annihilation, and the investigation of hadron production in 2-photon collisions. Only the first of these topics is addressed. Despite the many successes of QCD in the description of deep inelastic reactions, the basic fragmentation process of quarks and gluons is not very well understood. This lack of knowledge has been shown to jeopardize precise test of QCD, such as the accurate determination of the strong coupling constant. With its ability to disentangle complex hadronic events and to identify most of the final state particles, the TPC allows new and more sensitive tests of fragmentation models. A brief description of the detector is given and particle identification by ionization energy loss is described. Next, the inclusive production of stable hadrons and of resonances is discussed, and limits on the inclusive production of fractional charged particles are given. A new analysis of long-range correlations in e+e- annihilation is given.

  7. 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.

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

    SciTech Connect

    Vecchi, Paul Anthony

    2005-05-01

    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 {l_brace}Cp'Ru(CO){sub 2}{r_brace}{sup +} fragments, where Cp' = {eta}{sup 5}-C{sub 5}H{sub 5} (Cp) and {eta}{sup 5}-C{sub 5}Me{sub 5} (Cp*). Chapters 5 and 6 present the synthesis and structural characterization of complexes containing corannulene buckybowls that are {eta}{sup 6}-coordinated to {l_brace}Cp*Ru{r_brace}{sup +} 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.

  9. GUIDOS: tools for the assessment of pattern, connectivity, and fragmentation

    NASA Astrophysics Data System (ADS)

    Vogt, Peter

    2013-04-01

    Pattern, connectivity, and fragmentation can be considered as pillars for a quantitative analysis of digital landscape images. The free software toolbox GUIDOS (http://forest.jrc.ec.europa.eu/download/software/guidos) includes a variety of dedicated methodologies for the quantitative assessment of these features. Amongst others, Morphological Spatial Pattern Analysis (MSPA) is used for an intuitive description of image pattern structures and the automatic detection of connectivity pathways. GUIDOS includes tools for the detection and quantitative assessment of key nodes and links as well as to define connectedness in raster images and to setup appropriate input files for an enhanced network analysis using Conefor Sensinode. Finally, fragmentation is usually defined from a species point of view but a generic and quantifiable indicator is needed to measure fragmentation and its changes. Some preliminary results for different conceptual approaches will be shown for a sample dataset. Complemented by pre- and post-processing routines and a complete GIS environment the portable GUIDOS Toolbox may facilitate a holistic assessment in risk assessment studies, landscape planning, and conservation/restoration policies. Alternatively, individual analysis components may contribute to or enhance studies conducted with other software packages in landscape ecology.

  10. Impact fragmentation of aluminum reactive materials

    NASA Astrophysics Data System (ADS)

    Hooper, Joseph P.

    2012-08-01

    We report the fragmentation of brittle, granular aluminum spheres following high velocity impact (0.5-2.0 km/s) on thin steel plates. These spheres, machined from isostatically pressed aluminum powder, represent a prototypical metallic reactive material. The fragments generated by the impacts are collected in a soft-catch apparatus and analyzed down to a length scale of 44μm. With increasing velocity, there is a transition from an exponential Poisson-process fragment distribution with a characteristic length scale to a power-law behavior indicative of scale-invariance. A normalized power-law distribution with a finite size cutoff is introduced and used to analyze the number and mass distributions of the recovered fragments. At high impact velocities, the power-law behavior dominates the distribution and the power-law exponent is identical to the universal value for brittle fragmentation discussed in recent works. The length scale at which the power-law behavior decays is consistent with the idea that the length of side microbranches or damage zones from primary cracks is governing this cutoff. The transition in fragment distribution at high strain-rates also implies a significant increase in small fragments that can rapidly combust in an ambient atmosphere.

  11. 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.

  12. Anionic derivatives of uracil: fragmentation and reactivity.

    PubMed

    Cole, Callie A; Wang, Zhe-Chen; Snow, Theodore P; Bierbaum, Veronica M

    2014-09-01

    Uracil is an essential biomolecule for terrestrial life, yet its prebiotic formation mechanisms have proven elusive for decades. Meteorites have been shown to contain uracil and the interstellar abundance of aromatic species and nitrogen-containing molecules is well established, providing support for uracil's presence in the interstellar medium (ISM). The ion chemistry of uracil may provide clues to its prebiotic synthesis and role in the origin of life. The fragmentation of biomolecules provides valuable insights into their formation. Previous research focused primarily on the fragmentation and reactivity of cations derived from uracil. In this study, we explore deprotonated uracil-5-carboxylic acid and its anionic fragments to elucidate novel reagents of uracil formation and to characterize the reactivity of uracil's anionic derivatives. The structures of these fragments are identified through theoretical calculations, further fragmentation, experimental acidity bracketing, and reactivity with several detected and potential interstellar species (SO2, OCS, CS2, NO, N2O, CO, NH3, O2, and C2H4). Fragmentation is achieved through collision induced dissociation (CID) in a commercial ion trap mass spectrometer, and all reaction rate constants are measured using a modification of this instrument. Experimental data are supported by theoretical calculations at the B3LYP/6-311++G(d,p) level of theory. Lastly, the astrochemical implications of the observed fragmentation and reaction processes are discussed. PMID:25036757

  13. A Stochastic Model of DNA Fragments Rejoining

    PubMed Central

    Li, Yongfeng; Qian, Hong; Wang, Ya; Cucinotta, Francis A.

    2012-01-01

    When cells are exposed to ionizing radiation, DNA damages in the form of single strand breaks (SSBs), double strand breaks (DSBs), base damage or their combinations are frequent events. It is known that the complexity and severity of DNA damage depends on the quality of radiation, and the microscopic dose deposited in small segments of DNA, which is often related to the linear transfer energy (LET) of the radiation. Experimental studies have suggested that under the same dose, high LET radiation induces more small DNA fragments than low-LET radiation, which affects Ku efficiently binding with DNA end and might be a main reason for high-LET radiation induced RBE [1] since DNA DSB is a major cause for radiation-induced cell death. In this work, we proposed a mathematical model of DNA fragments rejoining according to non-homologous end joining (NHEJ) mechanism. By conducting Gillespie's stochastic simulation, we found several factors that impact the efficiency of DNA fragments rejoining. Our results demonstrated that aberrant DNA damage repair can result predominantly from the occurrence of a spatial distribution of DSBs leading to short DNA fragments. Because of the low efficiency that short DNA fragments recruit repair protein and release the protein residue after fragments rejoining, Ku-dependent NHEJ is significantly interfered with short fragments. Overall, our work suggests that inhibiting the Ku-dependent NHEJ may significantly contribute to the increased efficiency for cell death and mutation observed for high LET radiation. PMID:23028515

  14. Introduction to fragment-based drug discovery.

    PubMed

    Erlanson, Daniel A

    2012-01-01

    Fragment-based drug discovery (FBDD) has emerged in the past decade as a powerful tool for discovering drug leads. The approach first identifies starting points: very small molecules (fragments) that are about half the size of typical drugs. These fragments are then expanded or linked together to generate drug leads. Although the origins of the technique date back some 30 years, it was only in the mid-1990s that experimental techniques became sufficiently sensitive and rapid for the concept to be become practical. Since that time, the field has exploded: FBDD has played a role in discovery of at least 18 drugs that have entered the clinic, and practitioners of FBDD can be found throughout the world in both academia and industry. Literally dozens of reviews have been published on various aspects of FBDD or on the field as a whole, as have three books (Jahnke and Erlanson, Fragment-based approaches in drug discovery, 2006; Zartler and Shapiro, Fragment-based drug discovery: a practical approach, 2008; Kuo, Fragment based drug design: tools, practical approaches, and examples, 2011). However, this chapter will assume that the reader is approaching the field with little prior knowledge. It will introduce some of the key concepts, set the stage for the chapters to follow, and demonstrate how X-ray crystallography plays a central role in fragment identification and advancement. PMID:21695633

  15. In situ end labeling of fragmented DNA in induced ovarian atresia.

    PubMed

    D'Herde, K; De Pestel, G; Roels, F

    1994-01-01

    Apoptosis is studied in a model of induced follicular atresia in the ovary of Japanese quail (Coturnix coturnix japonica) by in situ end labeling of DNA fragments in granulosa cells using two different techniques (incorporation of labeled nucleotides by DNA polymerase I or terminal deoxynucleotidyl transferase). The most remarkable observation related to apoptosis in this model is the predominant cytoplasmic localization of labeled DNA fragments, while DNA fragmentation appears to be absent from compacted chromatin masses of apoptotic nuclei and apoptotic nuclear fragments. Unstained apoptotic bodies are present adjacent to stained ones, so that their detection rate on hematoxylin + eosin stained sections is better than on the in situ end-labeled sections. This suggests that DNA fragmentation is a late even or not obligatory in apoptotic granulosa cell death. In contrast to similar studies on atretic granulosa in mammalian models, the process of apoptosis is asynchronous in the granulosal epithelium, with a majority of nuclei with normal chromatin configuration remaining negative for DNA fragmentation. Finally it is shown that the techniques used are not specific for apoptosis, as DNA fragmentation in necrotic granulosa cells is detected as well. PMID:7654330

  16. Using the speeded word fragment completion task to examine semantic priming.

    PubMed

    Heyman, Tom; De Deyne, Simon; Hutchison, Keith A; Storms, Gert

    2015-06-01

    The present research investigates semantic priming with an adapted version of the word fragment completion task. In this task, which we refer to as the speeded word fragment completion task, participants need to complete words such as lett_ce (lettuce), from which one letter was omitted, as quickly as possible. This paradigm has some interesting qualities in comparison with the traditionally used lexical decision task. That is, it requires no pseudowords, it is more engaging for participants, and most importantly, it allows for a more fine-grained investigation of semantic activation. In two studies, we found that words were completed faster when the preceding trial comprised a semantically related fragment such as tom_to (tomato) than when it comprised an unrelated fragment such as guit_r (guitar). A third experiment involved a lexical decision task, to compare both paradigms. The results showed that the magnitude of the priming effect was similar, but item-level priming effects were inconsistent over tasks. Crucially, the speeded word fragment completion task obtained strong priming effects for highly frequent, central words, such as work, money, and warm, whereas the lexical decision task did not. In a final experiment featuring only short, highly frequent words, the lexical decision task failed to find a priming effect, whereas the fragment completion task did obtain a robust effect. Taken together, these results suggest that the speeded word fragment completion task may prove a viable alternative for examining semantic priming. PMID:24942248

  17. 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.

  18. Spreading and Fragmenting Characteristics of Impacting Droplet on Micro/ Nanostructured Water-Repellent Surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Hyungmo; Lee, Chan; Kim, Moo Hwan; Kim, Joonwon

    2012-11-01

    After impact on a solid surface a droplet spreads, but in different ways such as deposition, rebound, and fragmentation. Because fragmentation occurs when the kinetic energy beat the surface energy during impact, Weber number is the most important dimensionless number in the rebound/fragmentation criteria. This also can be dramatically changed by the micro/nano-scale surface structures. Different micro/nanostructured surfaces were fabricated using silicon wet etching, black silicon formation, or the combination of these methods. Then, spreading and fragmenting events were analyzed with supporting experimental results. On the surfaces, the microstructures form obstacles to drop spreading and retracting, the nanostructures give extreme water-repellency, and the hybrid micro/nanostructures facilitate droplet fragmentation. Especially, the Cassie-Baxter's fraction factor of the microstructures can change rebound/fragmentation criteria. From this work, we finally investigate how the micro/nanostructures can change spreading and fragmenting dynamics during droplet impact. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government (MEST) (No. 2011-0030075).

  19. "Diabodies": small bivalent and bispecific antibody fragments.

    PubMed Central

    Holliger, P; Prospero, T; Winter, G

    1993-01-01

    Bivalent and bispecific antibodies and their fragments have immense potential for practical application. Here we describe the design of small antibody fragments with two antigen-binding sites. The fragments comprise a heavy-chain variable domain (VH) connected to a light-chain variable domain (VL) on the same polypeptide chain (VH-VL). By using a linker that is too short to allow pairing between the two domains on the same chain, the domains are forced to pair with the complementary domains of another chain and create two antigen-binding sites. As indicated by a computer graphic model of the dimers, the two pairs of domains can pack together with the antigen-binding sites pointing in opposite directions. The dimeric antibody fragments, or "diabodies," can be designed for bivalent or bispecific interactions. Starting from the monoclonal antibodies NQ11.7.22 (NQ11) and D1.3 directed against the hapten phenyloxazolone and hen egg lysozyme, respectively, we built bivalent fragments (VHNQ11-VLNQ11)2 and (VHD1.3-VLD1.3)2 and bispecific fragments VHNQ11-VLD1.3 and VHD1.3-VLNQ11. The fragments were expressed by secretion from bacteria and shown to bind specifically to the hapten and/or antigen. Those with 5- and 15-residue linkers had similar binding affinities to the parent antibodies, but a fragment with the VH domain joined directly to the VL domain was found to have slower dissociation kinetics and an improved affinity for hapten. Diabodies offer a ready means of constructing small bivalent and bispecific antibody fragments in bacteria. Images Fig. 1 Fig. 3 PMID:8341653

  20. Factors affecting bird communities in fragments ofsecondary pine forests in the north-western Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Brotons, Lluís; Herrando, Sergi

    2001-02-01

    We assessed the influence of size, extent of isolation and vegetation structure of secondary forest fragments on the richness and species composition of breeding bird communities in a sample of pine forest fragments surrounded by an agricultural matrix in the north-western Mediterranean basin. Fragment size was the main predictor of bird's occurrence, since it accounted for 70 % of the model variation. Isolation was also a valuable predictor of species occurrence, especially for forest specialists. Finally, subarboreal vegetation such as holm oak and a well-developed tree layer of large pines favoured forest species occurrence. Therefore, in spite of the long history of human impact, forest birds in Mediterranean mosaics are sensitive to both habitat loss and isolation of remnant patches in a similar manner to the patterns found in other temperate fragmented landscapes where human impact is more recent.

  1. Aggregation of beta-amyloid fragments.

    PubMed

    Meinke, Jan H; Hansmann, Ulrich H E

    2007-01-01

    The authors study the folding and aggregation of six chains of the beta-amyloid fragment 16-22 using Monte Carlo simulations. While the isolated fragment prefers a helical form at room temperature, in the system of six interacting fragments one observes both parallel and antiparallel beta sheets below a crossover temperature T(x) approximately equal to 420 K. The antiparallel sheets have lower energy and are therefore more stable. Above the nucleation temperature the aggregate quickly dissolves into widely separated, weakly interacting chains. PMID:17212510

  2. 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.

  3. 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.

  4. The singular coagulation equation with multiple fragmentation

    NASA Astrophysics Data System (ADS)

    Saha, Jitraj; Kumar, Jitendra

    2015-06-01

    In this paper, we prove the global existence and uniqueness of the solutions to the initial-value problem for the coagulation-fragmentation equation with singular coagulation kernel and multiple fragmentation kernel. The solution obtained in this case also satisfies the mass conservation law. The proof is based on strong convergence methods applied to suitably chosen unbounded coagulation kernels having singularities in both the coordinate axes and satisfying certain growth conditions, which can possibly reach up to a quadratic growth at infinity, and the fragmentation kernel covers a very large class of unbounded functions.

  5. EJECTA KNOT FLICKERING, MASS ABLATION, AND FRAGMENTATION IN CASSIOPEIA A

    SciTech Connect

    Fesen, Robert A.; Zastrow, Jordan A.; Hammell, Molly C.; Shull, J. Michael; Silvia, Devin W.

    2011-08-01

    Ejecta knot flickering, ablation tails, and fragmentation are expected signatures associated with the gradual dissolution of high-velocity supernova (SN) ejecta caused by their passage through an inhomogeneous circumstellar medium or interstellar medium (ISM). Such phenomena mark the initial stages of the gradual merger of SN ejecta with and the enrichment of the surrounding ISM. Here we report on an investigation of this process through changes in the optical flux and morphology of several high-velocity ejecta knots located in the outskirts of the young core-collapse SN remnant Cassiopeia A using Hubble Space Telescope images. Examination of WFPC2 F675W and combined ACS F625W + F775W images taken between 1999 June and 2004 December of several dozen debris fragments in the remnant's northeast ejecta stream and along the remnant's eastern limb reveal substantial emission variations ('flickering') over timescales as short as nine months. Such widespread and rapid variability indicates knot scale lengths {approx_equal} 10{sup 15} cm and a highly inhomogeneous surrounding medium. We also identify a small percentage of ejecta knots located all around the remnant's outer periphery which show trailing emissions typically 0.''2-0.''7 in length aligned along the knot's direction of motion suggestive of knot ablation tails. We discuss the nature of these trailing emissions as they pertain to ablation cooling, knot disruption, and fragmentation, and draw comparisons to the emission 'strings' seen in {eta} Car. Finally, we identify several tight clusters of small ejecta knots which resemble models of shock-induced fragmentation of larger SN ejecta knots caused by a high-velocity interaction with a lower density ambient medium.

  6. 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.

  7. FOREST FRAGMENTATION AS AN ECONOMIC INDICATOR

    EPA Science Inventory

    Despite concern over the ecological consequences of conversion of land from natural cover to anthropogenic uses, there are few studies that show a quantitative relationship between fragmentation and economic factors. For the southside economic region of Virginia, we generated a ...

  8. Dispersal and extinction in fragmented landscapes.

    PubMed Central

    Thomas, C D

    2000-01-01

    Evolutionary and population dynamics models suggest that the migration rate will affect the probability of survival in fragmented landscapes. Using data for butterfly species in the fragmented British landscape and in immediately adjoining areas of the European continent, this paper shows that species of intermediate mobility have declined most, followed by those of low mobility, whereas high-mobility species are generally surviving well. Compared to the more sedentary species, species of intermediate mobility require relatively large areas where they breed at slightly lower local densities. Intermediate mobility species have probably fared badly through a combination of metapopulation (extinction and colonization) dynamics and the mortality of migrating individuals which fail to find new habitats in fragmented landscapes. Habitat fragmentation is likely to result in the non-random extinction of populations and species characterized by different levels of dispersal, although the details are likely to depend on the taxa, habitats and regions considered. PMID:10687818

  9. The NJL Model for Quark Fragmentation Functions

    SciTech Connect

    T. Ito, W. Bentz, I. Cloet, A W Thomas, K. Yazaki

    2009-10-01

    A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an effective quark theory. Concentrating on the pion fragmentation function, we first explain the reason why the elementary (lowest order) fragmentation process q → qπ is completely inadequate to describe the empirical data, although the “crossed” process π → qq describes the quark distribution functions in the pion reasonably well. Then, taking into account cascade-like processes in a modified jet-model approach, we show that the momentum and isospin sum rules can be satisfied naturally without introducing any ad-hoc parameters. We present numerical results for the Nambu-Jona-Lasinio model in the invariant mass regularization scheme, and compare the results with the empirical parametrizations. We argue that this NJL-jet model provides a very useful framework to calculate the fragmentation functions in an effective chiral quark theory.

  10. Fragmentation of Care in Ectopic Pregnancy.

    PubMed

    Stulberg, Debra B; Dahlquist, Irma; Jarosch, Christina; Lindau, Stacy T

    2016-05-01

    Objectives Ectopic pregnancy is an important cause of maternal morbidity and mortality. Women who experience fragmented care may undergo unnecessary delays to diagnosis and treatment. Based on ectopic pregnancy cases observed in clinical practice that raised our concern about fragmentation of care, we designed an exploratory study to describe the number, characteristics, and outcomes of fragmented care among patients with ectopic pregnancy at one urban academic hospital. Methods Chart review with descriptive statistics. Fragmented care was defined as a patient being evaluated at an outside facility for possible ectopic pregnancy and transferred, referred, or discharged before receiving care at the study institution. Results Of 191 women seen for possible or definite ectopic pregnancy during the study period, 42 (22 %) met the study definition of fragmented care. The study was under-powered to observe statistically significant differences across groups, but we found concerning, non-significant trends: patients with fragmented care were more likely to be Medicaid recipients (65.9 vs. 58.8 %) and to experience a complication (23.8 vs. 18.1 %) compared to those with non-fragmented care. Most patients (n = 37) received no identifiable treatment prior to transfer and arrived to the study hospital with no communication to the receiving hospital from the outside provider (n = 34). Nine patients (21 %) presented with ruptured ectopic pregnancies. The fragmentation we observed in our study may contribute to previously identified socio-economic disparities in ectopic pregnancy outcomes. Conclusion If future research confirms these findings, health information exchanges and regional coordination of care may be important strategies for reducing maternal mortality. PMID:26987855

  11. 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.

  12. Preferred Modes of Decay in Nuclear Fragmentation

    NASA Astrophysics Data System (ADS)

    Aranda, Alfredo; López, Jorge A.; Wu, Zehua

    1997-04-01

    Recent experiments show a characteristic energy dependence of the different fragmentation modes in heavy ion reactions at intermediate energies. In this work we study this effect and find that, in nuclear fragmentation, like in binary fission, some modes of decay are more probable than the rest. We argue that these high probability mass partitions are ultimately responsible for the observed energy dependence. This work was supported by the National Science Foundation grant PHY-9600038 and Artemio de la Vega Foundation.

  13. 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.

  14. 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.

  15. Periodically spaced fragmentation in Orion A

    NASA Technical Reports Server (NTRS)

    Dutrey, A.; Duvert, G.; Castets, A.; Langer, W. D.; Bally, J.; Wilson, R. W.

    1991-01-01

    Evidence is found for periodic density structure in the highly fragmented interior of the Orion A molecular cloud from analysis of a large scale map of C(O-18) J = 1 - 0 emission. The spatial wavelength is about 1 parsec, and extends at least over 2 degrees along the main filament of Orion A and is also observed in other filamentary structures in Orion. This periodicity in the clumps is a result of externally triggered and magnetically mediated cloud collapse and fragmentation.

  16. 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

  17. Molecular cloning of Renibacterium salmoninarum DNA fragments.

    PubMed

    Etchegaray, J P; Martínez, M A; Krauskopf, M; León, G

    1991-03-15

    A Renibacterium salmoninarum enriched recombinant DNA library was constructed to isolate DNA fragments which could be used as probes to detect gene sequences specific for the causative agent of bacterial kidney disease in salmonid fish. One fragment of 149 base pairs was isolated and its specificity and sequence determined. This probe may prove useful in the design of diagnostic tests for the disease in asymptomatic fish and ova. PMID:2044941

  18. 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.

  19. 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.

  20. 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.

  1. Cylinder Fragmentation Using Gas Gun Methods

    NASA Astrophysics Data System (ADS)

    Thornhill, Tom; Reinhart, William; Chhabildas, Lalit; Grady, Dennis; Wilson, Leonard

    2001-06-01

    An experimental technique for investigating fracture and fragmentation characteristics of materials has been developed for use on the gas guns. In this method the candidate material is in the cylindrical form. This technique involves the precision alignment of the candidate cylinder, and symmetric impact of a stationary cylinder plug with the moving projectile from the gun. This test method allows the study of cylinder fragmentation in a laboratory environment under well-controlled loading conditions. In this presentation, results of several experiments on Aermet steel will be presented. The fragmentation toughness of the material can be estimated through knowledge of the material strain-rate and mean fragment size derived from the statistical distribution of the fragments. The values for fragmentation toughness will be compared with those obtained from other experimental methods such as explosives loading or ball on plate impact methods. Future developments and directions in test geometry, test methods and diagnostics will also be reported. This work was supported by the U. S. Department of Energy under contract DE-AC04-94AL85000.

  2. 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. PMID:25709032

  3. 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.

  4. 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.

  5. Invariant object recognition based on extended fragments.

    PubMed

    Bart, Evgeniy; Hegdé, Jay

    2012-01-01

    Visual appearance of natural objects is profoundly affected by viewing conditions such as viewpoint and illumination. Human subjects can nevertheless compensate well for variations in these viewing conditions. The strategies that the visual system uses to accomplish this are largely unclear. Previous computational studies have suggested that in principle, certain types of object fragments (rather than whole objects) can be used for invariant recognition. However, whether the human visual system is actually capable of using this strategy remains unknown. Here, we show that human observers can achieve illumination invariance by using object fragments that carry the relevant information. To determine this, we have used novel, but naturalistic, 3-D visual objects called "digital embryos." Using novel instances of whole embryos, not fragments, we trained subjects to recognize individual embryos across illuminations. We then tested the illumination-invariant object recognition performance of subjects using fragments. We found that the performance was strongly correlated with the mutual information (MI) of the fragments, provided that MI value took variations in illumination into consideration. This correlation was not attributable to any systematic differences in task difficulty between different fragments. These results reveal two important principles of invariant object recognition. First, the subjects can achieve invariance at least in part by compensating for the changes in the appearance of small local features, rather than of whole objects. Second, the subjects do not always rely on generic or pre-existing invariance of features (i.e., features whose appearance remains largely unchanged by variations in illumination), and are capable of using learning to compensate for appearance changes when necessary. These psychophysical results closely fit the predictions of earlier computational studies of fragment-based invariant object recognition. PMID:22936910

  6. 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

  7. Measurement Techniques for Hypervelocity Impact Test Fragments

    NASA Technical Reports Server (NTRS)

    Hill, Nicole E.

    2008-01-01

    The ability to classify the size and shape of individual orbital debris fragments provides a better understanding of the orbital debris environment as a whole. The characterization of breakup fragmentation debris has gradually evolved from a simplistic, spherical assumption towards that of describing debris in terms of size, material, and shape parameters. One of the goals of the NASA Orbital Debris Program Office is to develop high-accuracy techniques to measure these parameters and apply them to orbital debris observations. Measurement of the physical characteristics of debris resulting from groundbased, hypervelocity impact testing provides insight into the shapes and sizes of debris produced from potential impacts in orbit. Current techniques for measuring these ground-test fragments require determination of dimensions based upon visual judgment. This leads to reduced accuracy and provides little or no repeatability for the measurements. With the common goal of mitigating these error sources, allaying any misunderstandings, and moving forward in fragment shape determination, the NASA Orbital Debris Program Office recently began using a computerized measurement system. The goal of using these new techniques is to improve knowledge of the relation between commonly used dimensions and overall shape. The immediate objective is to scan a single fragment, measure its size and shape properties, and import the fragment into a program that renders a 3D model that adequately demonstrates how the object could appear in orbit. This information would then be used to aid optical methods in orbital debris shape determination. This paper provides a description of the measurement techniques used in this initiative and shows results of this work. The tradeoffs of the computerized methods are discussed, as well as the means of repeatability in the measurements of these fragments. This paper serves as a general description of methods for the measurement and shape analysis of

  8. E2F1-dependent miR-421 regulates mitochondrial fragmentation and myocardial infarction by targeting Pink1.

    PubMed

    Wang, Kun; Zhou, Lu-Yu; Wang, Jian-Xun; Wang, Yin; Sun, Teng; Zhao, Bing; Yang, Yong-Jie; An, Tao; Long, Bo; Li, Na; Liu, Cui-Yun; Gong, Ying; Gao, Jin-Ning; Dong, Yan-Han; Zhang, Jian; Li, Pei-Feng

    2015-01-01

    Mitochondrial fragmentation plays an important role in the progression of cardiac diseases, such as myocardial infarction and heart failure. Mitochondrial network is controlled by many factors in different cell types. Here we show that the interplay between E2F1, miR-421 and Pink1 regulates mitochondrial morphology and cardiomyocyte cell death. Pink1 reduces mitochondrial fragmentation and protects cardiomyocyte from apoptosis. On the other hand, miR-421 promotes cardiomyocyte mitochondrial fragmentation, apoptosis and myocardial infarction by suppressing Pink1 translation. Finally, we show that transcription factor E2F1 activates miR-421 expression. Knocking down E2F1 suppresses mitochondrial fragmentation, apoptosis and myocardial infarction by affecting miR-421 levels. Collectively, these data identify the E2F1/miR-421/Pink axis as a regulator of mitochondrial fragmentation and cardiomyocyte apoptosis, and suggest potential therapeutic targets in treatment of cardiac diseases. PMID:26184432

  9. 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.

  10. 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.

  11. Comparison of mitotic cell death by chromosome fragmentation to premature chromosome condensation

    PubMed Central

    2010-01-01

    Mitotic cell death is an important form of cell death, particularly in cancer. Chromosome fragmentation is a major form of mitotic cell death which is identifiable during common cytogenetic analysis by its unique phenotype of progressively degraded chromosomes. This morphology however, can appear similar to the morphology of premature chromosome condensation (PCC) and thus, PCC has been at times confused with chromosome fragmentation. In this analysis the phenomena of chromosome fragmentation and PCC are reviewed and their similarities and differences are discussed in order to facilitate differentiation of the similar morphologies. Furthermore, chromosome pulverization, which has been used almost synonymously with PCC, is re-examined. Interestingly, many past reports of chromosome pulverization are identified here as chromosome fragmentation and not PCC. These reports describe broad ranging mechanisms of pulverization induction and agree with recent evidence showing chromosome fragmentation is a cellular response to stress. Finally, biological aspects of chromosome fragmentation are discussed, including its application as one form of non-clonal chromosome aberration (NCCA), the driving force of cancer evolution. PMID:20959006

  12. 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.

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

    NASA Technical Reports Server (NTRS)

    Eck, Marshall B.; Mukunda, Meera

    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).

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

    NASA Astrophysics Data System (ADS)

    Eck, Marshall B.; Mukunda, Meera

    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).

  15. Simvastatin inhibits CD44 fragmentation in chondrocytes.

    PubMed

    Terabe, Kenya; Takahashi, Nobunori; Takemoto, Toki; Knudson, Warren; Ishiguro, Naoki; Kojima, Toshihisa

    2016-08-15

    In human osteoarthritic chondrocytes, the hyaluronan receptor CD44 undergoes proteolytic cleavage at the cell surface. CD44 cleavage is thought to require transit of CD44 into cholesterol-rich lipid rafts. The purpose of this study was to investigate whether statins exert a protective effect on articular chondrocytes due to diminution of cholesterol. Three model systems of chondrocytes were examined including human HCS-2/8 chondrosarcoma cells, human osteoarthritic chondrocytes and normal bovine articular chondrocytes. Treatment with IL-1β + Oncostatin M resulted in a substantial increase in CD44 fragmentation in each of the three chondrocyte models. Pre-incubation with simvastatin prior to treatment with IL-1β + Oncostatin M decreased the level of CD44 fragmentation, decreased the proportion of CD44 that transits into the lipid raft fractions, decreased ADAM10 activity and diminished the interaction between CD44 and ADAM10. In HCS-2/8 cells and bovine articular chondrocytes, fragmentation of CD44 was blocked by the knockdown of ADAM10. Inhibition of CD44 fragmentation by simvastatin also resulted in improved retention of pericellular matrix. Addition of cholesterol and farnesyl-pyrophosphate reversed the protective effects of simvastatin. Thus, the addition of simvastatin exerts positive effects on chondrocytes including reduced CD44 fragmentation and enhanced the retention of pericellular matrix. PMID:27242325

  16. Ultrafast ionization and fragmentation of molecular silane

    SciTech Connect

    Sayres, Scott G.; Ross, Matt W.; Castleman, A. W. Jr.

    2010-09-15

    The ionization and fragmentation of molecular silane is examined here with laser intensities ranging between 7x10{sup 12} and 1x10{sup 15} W/cm{sup 2} at 624 nm. The ionization potential of silane determined using both multiphoton ionization (MPI) and tunneling ionization (TI) models agrees with the vertical ionization potential of the molecule. In addition, the application of the tunneling ionization model is extended here to the fragments of silane to determine their appearance potentials. MPI values for SiH{sub 3}{sup +}, SiH{sub 2}{sup +}, SiH{sup +}, Si{sup +}, as well as H{sub 2}{sup +} and H{sup +} are consistent with vertical potentials, whereas the TI measurements are found to be in accord with adiabatic potentials. The tunneling appearance potentials observed for the fragments H{sub 2}{sup +} and H{sup +} are lower than reported for other techniques. In fact, the appearance potential measurements for these species resulting from silane are lower than their ionization potentials. The fragmentation rate of silane is determined to be nearly 20 times larger than the ionization rate. The main precursor for producing amorphous silicon (a-Si:H) thin films, SiH{sub 3}{sup +} is the dominant fragmentation product making up roughly a third of the total ion yield, a substantial increase from other techniques.

  17. 3D puzzle reconstruction for archeological fragments

    NASA Astrophysics Data System (ADS)

    Jampy, F.; Hostein, A.; Fauvet, E.; Laligant, O.; Truchetet, F.

    2015-03-01

    The reconstruction of broken artifacts is a common task in archeology domain; it can be supported now by 3D data acquisition device and computer processing. Many works have been dedicated in the past to reconstructing 2D puzzles but very few propose a true 3D approach. We present here a complete solution including a dedicated transportable 3D acquisition set-up and a virtual tool with a graphic interface allowing the archeologists to manipulate the fragments and to, interactively, reconstruct the puzzle. The whole lateral part is acquired by rotating the fragment around an axis chosen within a light sheet thanks to a step-motor synchronized with the camera frame clock. Another camera provides a top view of the fragment under scanning. A scanning accuracy of 100μm is attained. The iterative automatic processing algorithm is based on segmentation into facets of the lateral part of the fragments followed by a 3D matching providing the user with a ranked short list of possible assemblies. The device has been applied to the reconstruction of a set of 1200 fragments from broken tablets supporting a Latin inscription dating from the first century AD.

  18. Observation of magnetic fragmentation in spin ice

    NASA Astrophysics Data System (ADS)

    Petit, S.; Lhotel, E.; Canals, B.; Ciomaga Hatnean, M.; Ollivier, J.; Mutka, H.; Ressouche, E.; Wildes, A. R.; Lees, M. R.; Balakrishnan, G.

    2016-08-01

    Fractionalized excitations that emerge from a many-body system have revealed rich physics and concepts, from composite fermions in two-dimensional electron systems, revealed through the fractional quantum Hall effect, to spinons in antiferromagnetic chains and, more recently, fractionalization of Dirac electrons in graphene and magnetic monopoles in spin ice. Even more surprising is the fragmentation of the degrees of freedom themselves, leading to coexisting and a priori independent ground states. This puzzling phenomenon was recently put forward in the context of spin ice, in which the magnetic moment field can fragment, resulting in a dual ground state consisting of a fluctuating spin liquid, a so-called Coulomb phase, on top of a magnetic monopole crystal. Here we show, by means of neutron scattering measurements, that such fragmentation occurs in the spin ice candidate Nd2Zr2O7. We observe the spectacular coexistence of an antiferromagnetic order induced by the monopole crystallization and a fluctuating state with ferromagnetic correlations. Experimentally, this fragmentation manifests itself through the superposition of magnetic Bragg peaks, characteristic of the ordered phase, and a pinch point pattern, characteristic of the Coulomb phase. These results highlight the relevance of the fragmentation concept to describe the physics of systems that are simultaneously ordered and fluctuating.

  19. Molten aluminum alloy fuel fragmentation experiments

    SciTech Connect

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-09-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles ({approximately}30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller ({approximately} mm), and the 20 mm jet which underwent sinuous wave breakup produced {approximately}100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was {ge}343 K, the melt fragments did not freeze during their transit through 1.2 m of water.

  20. Molten aluminum alloy fuel fragmentation experiments

    SciTech Connect

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-01-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles ({approximately}30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller ({approximately} mm), and the 20 mm jet which underwent sinuous wave breakup produced {approximately}100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was {ge}343 K, the melt fragments did not freeze during their transit through 1.2 m of water.

  1. Short read DNA fragment anchoring algorithm

    PubMed Central

    Wang, Wendi; Zhang, Peiheng; Liu, Xinchun

    2009-01-01

    Background The emerging next-generation sequencing method based on PCR technology boosts genome sequencing speed considerably, the expense is also get decreased. It has been utilized to address a broad range of bioinformatics problems. Limited by reliable output sequence length of next-generation sequencing technologies, we are confined to study gene fragments with 30~50 bps in general and it is relatively shorter than traditional gene fragment length. Anchoring gene fragments in long reference sequence is an essential and prerequisite step for further assembly and analysis works. Due to the sheer number of fragments produced by next-generation sequencing technologies and the huge size of reference sequences, anchoring would rapidly becoming a computational bottleneck. Results and discussion We compared algorithm efficiency on BLAT, SOAP and EMBF. The efficiency is defined as the count of total output results divided by time consumed to retrieve them. The data show that our algorithm EMBF have 3~4 times efficiency advantage over SOAP, and at least 150 times over BLAT. Moreover, when the reference sequence size is increased, the efficiency of SOAP will get degraded as far as 30%, while EMBF have preferable increasing tendency. Conclusion In conclusion, we deem that EMBF is more suitable for short fragment anchoring problem where result completeness and accuracy is predominant and the reference sequences are relatively large. PMID:19208116

  2. Stream Hydrological Fragmentation Drives Bacterioplankton Community Composition

    PubMed Central

    Fazi, Stefano; Vázquez, Eusebi; Casamayor, Emilio O.; Amalfitano, Stefano; Butturini, Andrea

    2013-01-01

    In Mediterranean intermittent streams, the hydrological fragmentation in summer and the successive water flow re-convergence in autumn allow exploring how local processes shape the microbial community within the same habitat. The objectives of this study were to determine how bacterial community composition responded to hydrological fragmentation in summer, and to evaluate whether the seasonal shifts in community composition predominate over the effects of episodic habitat fragmentation. The bacterial community was assessed along the intermittent stream Fuirosos (Spain), at different levels of phylogenetic resolution by in situ hybridization, fingerprinting, and 16S rRNA gene sequencing. The hydrological fragmentation of the stream network strongly altered the biogeochemical conditions with the depletion of oxidized solutes and caused changes in dissolved organic carbon characteristics. In the isolated ponds, beta-Proteobacteria and Actinobacteria increased their abundance with a gradual reduction of the alpha-diversity as pond isolation time increased. Moreover, fingerprinting analysis clearly showed a shift in community composition between summer and autumn. In the context of a seasonal shift, the temporary stream fragmentation simultaneously reduced the microbial dispersion and affected local environmental conditions (shift in redox regime and quality of the dissolved organic matter) tightly shaping the bacterioplankton community composition. PMID:23741302

  3. Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

    NASA Astrophysics Data System (ADS)

    Thies, R.; Heinz, A.; Adachi, T.; Aksyutina, Y.; Alcantara-Núñes, J.; Altstadt, S.; Alvarez-Pol, H.; Ashwood, N.; Aumann, T.; Avdeichikov, V.; Barr, M.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boretzky, K.; Borge, M. J. G.; Burgunder, G.; Camaño, M.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkäll, J.; Chakraborty, S.; Chartier, M.; Chulkov, L. V.; Cortina-Gil, D.; Crespo, R.; Datta, U.; Díaz Fernández, P.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estradé, A.; Farinon, F.; Fraile, L. M.; Freer, M.; Freudenberger, M.; Fynbo, H. O. U.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Göbel, K.; Golubev, P.; Gonzalez Diaz, D.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Henriques, A.; Holl, M.; Ickert, G.; Ignatov, A.; Jakobsson, B.; Johansson, H. T.; Jonson, B.; Kalantar-Nayestanaki, N.; Kanungo, R.; Knöbel, R.; Kröll, T.; Krücken, R.; Kurcewicz, J.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lepyoshkina, O.; Lindberg, S.; Machado, J.; Marganiec, J.; Maroussov, V.; Mostazo, M.; Movsesyan, A.; Najafi, A.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Perea, A.; Petri, M.; Pietri, S.; Plag, R.; Prochazka, A.; Rahaman, A.; Rastrepina, G.; Reifarth, R.; Ribeiro, G.; Ricciardi, M. V.; Rigollet, C.; Riisager, K.; Röder, M.; Rossi, D.; Sanchez del Rio, J.; Savran, D.; Scheit, H.; Simon, H.; Sorlin, O.; Stoica, V.; Streicher, B.; Taylor, J. T.; Tengblad, O.; Terashima, S.; Togano, Y.; Uberseder, E.; Van de Walle, J.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Weigand, M.; Wheldon, C.; Wilson, G.; Wimmer, C.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M. V.; Zilges, A.; Zuber, K.; R3B Collaboration

    2016-05-01

    Background: Models describing nuclear fragmentation and fragmentation fission deliver important input for planning nuclear physics experiments and future radioactive ion beam facilities. These models are usually benchmarked against data from stable beam experiments. In the future, two-step fragmentation reactions with exotic nuclei as stepping stones are a promising tool for reaching the most neutron-rich nuclei, creating a need for models to describe also these reactions. Purpose: We want to extend the presently available data on fragmentation reactions towards the light exotic region on the nuclear chart. Furthermore, we want to improve the understanding of projectile fragmentation especially for unstable isotopes. Method: We have measured projectile fragments from 10,12 -18C and B-1510 isotopes colliding with a carbon target. These measurements were all performed within one experiment, which gives rise to a very consistent data set. We compare our data to model calculations. Results: One-proton removal cross sections with different final neutron numbers (1 p x n ) for relativistic 10,12 -18C and B-1510 isotopes impinging on a carbon target. Comparing model calculations to the data, we find that the epax code is not able to describe the data satisfactorily. Using abrabla07 on the other hand, we find that the average excitation energy per abraded nucleon needs to be decreased from 27 MeV to 8.1 MeV. With that decrease abrabla07 describes the data surprisingly well. Conclusions: Extending the available data towards light unstable nuclei with a consistent set of new data has allowed a systematic investigation of the role of the excitation energy induced in projectile fragmentation. Most striking is the apparent mass dependence of the average excitation energy per abraded nucleon. Nevertheless, this parameter, which has been related to final-state interactions, requires further study.

  4. An Investigation of Fragments Produced in the 58,64Ni + 9Be Fragmentation Reactions

    NASA Astrophysics Data System (ADS)

    Zhang, Y. L.; Ma, C. W.; Wang, S. S.; Qiao, C. Y.

    The cross sections of the fragments produced in the 140A MeV 58,64Ni + 9Be reactions have been studied using the empirical parametrization formula EPAX2 and EPAX3, the modified statistical abrasion-ablation (SAA) model, and the antisymmetrized molecular dynamics (AMD) model. The calculated cross sections of fragments are compared and discussed.

  5. Fragment Impact Toolkit: A Toolkit for Modeling Fragment Generation and Impacts on Targets

    NASA Astrophysics Data System (ADS)

    Shevitz, Daniel

    2005-07-01

    In this talk we will detail the status of the Fragment Impact Toolkit. The toolkit is used to model nearby explosion problems and assess probabilities of user-specified outcomes. The toolkit offers a framework, without locking the user into any particular set of states, assumptions, or constraints. The toolkit breaks a fragment impact problem into five components, all of which are extendable: (1) source description that includes the geometry of the source; (2) fragment generation that comprises the fragmentation process, including fragment size distributions (if required) and assignment of initial conditions, such a velocity; (3) fragment flight that includes what occurs to fragments while airborne; (4) target intersection that includes specification of target geometry, position, and orientation; and (5) target consequence that includes what occurs when fragments hit a target. Two notable contributions of the toolkit are the ability to have sources that break up with position-dependent and user-specifiable size probability distributions and then impact targets of arbitrary complexity. In this paper we will show examples of how to use the toolkit and simulate targets, including airplanes and stacks of munitions.

  6. Fragmentation of Macromolecules Resulting from Ion Impact

    NASA Astrophysics Data System (ADS)

    Storey, D. M.; Dubois, R. D.

    1997-04-01

    Ion induced fragmentation of macromolecules is being investigated by bombarding various amino acids, which have been deposited on solid substrates, with few-keV singly-charged ions. Ionized particles, ejected from the target, are extracted with an electric field and time-of-flight mass spectroscopy is used to determine the degree of ionization and fragmentation which has occured. The goal of this study is to investigate how macromolecules respond to different energy deposition mechanisms. For example, the patterns we observe indicates that slow, low-charged ions primarily remove electrons from the molecule, thus producing varying degrees of ionization for the entire molecule. In contrast, for slow, highly-charged ions, where the potential energy of the incoming ion is extremely large, considerable fragmentation and ejection of intact molecules is observed(C. Ruehliche, D. Schneider, R. DuBois and R. Balhorn, Nucl. Inst. and Meth. (in press) 1997.). Data for various macromolecules will be presented and discussed.

  7. 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.

  8. Experiences in fragment-based drug discovery.

    PubMed

    Murray, Christopher W; Verdonk, Marcel L; Rees, David C

    2012-05-01

    Fragment-based drug discovery (FBDD) has become established in both industry and academia as an alternative approach to high-throughput screening for the generation of chemical leads for drug targets. In FBDD, specialised detection methods are used to identify small chemical compounds (fragments) that bind to the drug target, and structural biology is usually employed to establish their binding mode and to facilitate their optimisation. In this article, we present three recent and successful case histories in FBDD. We then re-examine the key concepts and challenges of FBDD with particular emphasis on recent literature and our own experience from a substantial number of FBDD applications. Our opinion is that careful application of FBDD is living up to its promise of delivering high quality leads with good physical properties and that in future many drug molecules will be derived from fragment-based approaches. PMID:22459076

  9. Identifying fragment vuv excitations with dissociation channels from the strong-field ionization of N{sub 2}

    SciTech Connect

    Coffee, Ryan N.; Gibson, George N.

    2005-07-15

    Along with attosecond pulses comes a growing need for broadband amplification in the extreme ultraviolet spectral regime. Ultrafast laser pulses interacting with high symmetry molecules produce electronic excitations that are approaching this energy regime. Although there is some theoretical work regarding such excitation, experimental progress had been hampered in a fundamental way. Ion time-of-flight spectroscopy measures dissociation pathways but provides no specific information regarding the final state of the fragments. Vacuum-ultraviolet spectroscopy provides complete information about excited fragments but says nothing of the dissociation channel. In this paper we measure the internal states of nitrogen ion fragments and we associate them with specific dissociation pathways.

  10. Weak solutions to the continuous coagulation equation with multiple fragmentation

    PubMed Central

    Giri, Ankik Kumar; Laurençot, Philippe; Warnecke, Gerald

    2012-01-01

    The existence of weak solutions to the continuous coagulation equation with multiple fragmentation is shown for a class of unbounded coagulation and fragmentation kernels, the fragmentation kernel having possibly a singularity at the origin. This result extends previous ones where either boundedness of the coagulation kernel or no singularity at the origin for the fragmentation kernel was assumed. PMID:22389550

  11. 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.

  12. Supersymmetric QCD and high energy cosmic rays: Fragmentation functions of supersymmetric QCD

    NASA Astrophysics Data System (ADS)

    Corianò, Claudio; Faraggi, Alon E.

    2002-04-01

    The supersymmetric evolution of the fragmentation functions (or timelike evolution) within N=1 QCD is discussed and predictions for the fragmentation functions of the theory (into final protons) are given. We use a backward running of the supersymmetric DGLAP equations, using a method developed in previous works. We start from the usual QCD parametrizations at low energy and run the DGLAP back, up to an intermediate scale-assumed to be supersymmetric-where we switch-on supersymmetry. From there on we assume the applicability of an N=1 supersymmetric evolution (ESAP). We elaborate on the possible application of these results to high energy cosmic rays near the GZK cutoff.

  13. DRAGON: Monte Carlo generator of particle production from a fragmented fireball in ultrarelativistic nuclear collisions

    NASA Astrophysics Data System (ADS)

    Tomášik, Boris

    2009-09-01

    A Monte Carlo generator of the final state of hadrons emitted from an ultrarelativistic nuclear collision is introduced. An important feature of the generator is a possible fragmentation of the fireball and emission of the hadrons from fragments. Phase space distribution of the fragments is based on the blast wave model extended to azimuthally non-symmetric fireballs. Parameters of the model can be tuned and this allows to generate final states from various kinds of fireballs. A facultative output in the OSCAR1999A format allows for a comprehensive analysis of phase-space distributions and/or use as an input for an afterburner. Program summaryProgram title: DRAGON Catalogue identifier: AEDK_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDK_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 6383 No. of bytes in distributed program, including test data, etc.: 32 756 Distribution format: tar.gz Programming language: C++ Computer: PC Pentium 4, though no particular tuning for this machine was performed Operating system: Linux; the program has been successfully run on Gentoo Linux 2.6, RedHat Linux 9, Debian Linux 4.0, all with g++ compiler. It also ran successfully on MS Windows under Microsoft Visual C++ 2008 Express Edition as well as under cygwin/g++ RAM: 100 Mbytes Supplementary material: Sample output files from the test run, provided in the distribution, are available. Classification: 11.2 Nature of problem: Deconfined matter produced in ultrarelativistic nuclear collisions expands and cools down and eventually returns into the confined phase. If the expansion is fast, the fireball could fragment either due to spinodal decomposition or due to suddenly arising bulk viscous force. Particle abundances are reasonably well described with just a few parameters

  14. 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.

  15. 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.

  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. Production of antibody fragments in Escherichia coli.

    PubMed

    Katsuda, Tomohisa; Sonoda, Hiroyuki; Kumada, Yoichi; Yamaji, Hideki

    2012-01-01

    Escherichia coli is a host widely used in the industrial production of recombinant proteins. However, the expression of heterologous proteins in E. coli often encounters the formation of inclusion bodies, which are insoluble and nonfunctional protein aggregates. For the successful production of antibody fragments, which includes single-chain variable fragments (scFvs), we describe here the modification of linker, signal, and Shine-Dalgarno (SD) sequences, the coexpression of cytoplasmic and periplasmic chaperones, and a method for fed-batch cultivation with exponential feed. PMID:22907360

  18. 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.

  19. 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.

  20. Angular momentum dependence of complex fragment emission

    SciTech Connect

    Sobotka, L.G.; Sarantites, D.G.; Li, Z.; Dines, E.L.; Halbert, M.L.; Hensley, D.C.; Lisle, J.C.; Schmitt, R.P.; Majka, Z.; Nebbia, G.

    1987-12-01

    The angular momentum dependence of large fragment production in long-lived reactions is studied by measurements of fragment cross sections from reactions with substantially different angular momentum distributions and the coincident ..gamma..-ray multiplicity distributions. The results indicate that the primary l-wave distributions move to larger mean values and decrease in width and skewness with increasing mass symmetry in the decay channel. The results also confirm that the partition of angular momentum kinetic energy relaxed heavy-ion reactions is that expected for a rigidly rotating intermediate.

  1. 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.

  2. Retained intravitreal lens fragments after phacoemulsification: a clinicopathological correlation

    PubMed Central

    Yeo, L; Charteris, D; Bunce, C; Luthert, P; Gregor, Z

    1999-01-01

    AIMS—To explore the relation between clinical course and timing of vitrectomy with the nature and intensity of intraocular inflammatory response in eyes with retained intravitreal lens fragments following complicated phacoemulsification.
METHODS—Prospective evaluation of 22 eyes with retained lens fragments with emphasis on corneal clarity, uveitis, intraocular pressure (IOP), timing of vitrectomy, and visual outcome. Numbers of different types of inflammatory cells in vitreous washings were counted, masked to clinical details, in three non-overlapping adjacent high power fields. Relations between clinical and pathological findings were assessed.
RESULTS—The IOP was raised in 19 eyes before vitrectomy and remained high in nine postoperatively. The latter had higher median total cell count (104 cells/mm2) than those with normal postoperative IOP (37 cells/mm2) but this difference was not statistically significantly different (p=0.17). Nine of 22 eyes underwent vitrectomy within 1 week of cataract surgery. Median total cell count in these eyes was 20 cells/mm2 compared with 140 cells/mm2 in eyes vitrectomised later—this difference was statistically significant (p <0.001). Final visual acuity was 6/12 or better in 13 eyes, these had fewer intravitreal inflammatory cells than the remaining six with poor visual outcome and no pre-existing cause for this (three patients excluded) (p=0.02). Macrophages were the predominant inflammatory cell type.
CONCLUSION—There was significantly less inflammatory cell activity in eyes which had retained lens fragments removed early (within 1 week). Later removal was associated with persistently elevated IOP and poorer visual outcome.

 PMID:10502573

  3. Fragmentation of structural energetic materials: implications for performance

    NASA Astrophysics Data System (ADS)

    Aydelotte, B.; Braithwaite, C. H.; Thadhani, N. N.

    2014-05-01

    Fragmentation results for structural energetic materials based on intermetallic forming mixtures are reviewed and the implications of the fragment populations are discussed. Cold sprayed Ni+Al and explosively compacted mixtures of Ni+Al+W and Ni+Al+W+Zr powders were fabricated into ring shaped samples and explosively fragmented. Ring velocity was monitored and fragments were soft captured in order to study the fragmentation process. It was determined that the fragments produced by these structural energetic materials are much smaller than those typically produced by ductile metals such as steel or aluminum. This has implications for combustion processes that may occur subsequent to the fragmentation process.

  4. 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.

  5. Condensate fragmentation as a sensitive measure of the quantum many-body behavior of bosons with long-range interactions

    NASA Astrophysics Data System (ADS)

    Fischer, Uwe R.; Lode, Axel U. Â. J.; Chatterjee, Budhaditya

    2015-06-01

    The occupation of more than one single-particle state, and hence the emergence of fragmentation, is a many-body phenomenon occurring for systems of spatially confined strongly interacting bosons. In the present study, we investigate the effect of the range of the interparticle interactions on the fragmentation degree of one- and two-dimensional systems in single wells. We solve the full many-body Schrödinger equation of the system using the recursive implementation of the multiconfigurational time-dependent Hartree for bosons method (R-MCTDHB). The dependence of the degree of fragmentation on dimensionality, particle number, areal or line density, and interaction strength is assessed. For contact interactions, it is found that the fragmentation is essentially density independent in two dimensions. However, fragmentation increasingly depends on density the more long ranged the interactions become. At fixed particle number N , the degree of fragmentation is increasing when the density is decreasing, as expected in one spatial dimension. We demonstrate that this, nontrivially, remains true also for long-range interactions in two spatial dimensions. We, finally, find that fragmentation in a single well is a mesoscopic phenomenon: Within our fully self-consistent approach, the degree of fragmentation, to a good approximation, decreases universally as N-1 /2 when only N is varied.

  6. Three-dimensional bonded-cell model for grain fragmentation

    NASA Astrophysics Data System (ADS)

    Cantor, D.; Azéma, E.; Sornay, P.; Radjai, F.

    2016-07-01

    We present a three-dimensional numerical method for the simulation of particle crushing in 3D. This model is capable of producing irregular angular fragments upon particle fragmentation while conserving the total volume. The particle is modeled as a cluster of rigid polyhedral cells generated by a Voronoi tessellation. The cells are bonded along their faces by a cohesive Tresca law with independent tensile and shear strengths and simulated by the contact dynamics method. Using this model, we analyze the mechanical response of a single particle subjected to diametral compression for varying number of cells, their degree of disorder, and intercell tensile and shear strength. In particular, we identify the functional dependence of particle strength on the intercell strengths. We find that two different regimes can be distinguished depending on whether intercell shear strength is below or above its tensile strength. In both regimes, we observe a power-law dependence of particle strength on both intercell strengths but with different exponents. The strong effect of intercell shear strength on the particle strength reflects an interlocking effect between cells. In fact, even at low tensile strength, the particle global strength can still considerably increase with intercell shear strength. We finally show that the Weibull statistics describes well the particle strength variability.

  7. 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.

  8. Observation campaign dedicated to 1968-081E fragments identification

    NASA Astrophysics Data System (ADS)

    Uetsuhara, Masahiko; Yanagisawa, Toshifumi; Kinoshita, Daisuke; Hanada, Toshiya; Kitazawa, Yukihito

    2013-06-01

    This paper proposes a comprehensive approach to associate origins of space objects newly discovered during optical surveys in the geostationary region with spacecraft breakup events. A recent study has shown that twelve breakup events would be occurred in the geostationary region. The proposed approach utilizes orbital debris modeling techniques to effectively conduct prediction, detection, and classification of breakup fragments. Two techniques are applied to get probable results for origin identifications. First, we select an observation point where a high detection rate for one breakup event among others can be expected. Second, we associate detected tracklets, which denotes the signals associated with a physical object, with the prediction results according to their angular velocities. The second technique investigates which breakup event a tracklet would belong to, and its probability by using the k-nearest neighbor (k-NN) algorithm.In this paper we conduct optical observations of breakup fragments to verify the proposed approach. We selected a well-known breakup event of the rocket body US Titan 3C Transtage (1968-081E) as the primary observation target, and then we conduct optical observations by campaign between two sensors in Taiwan and one sensor in Japan. While three nights observations, we detect 96 tracklets that are uncorrelated with the Space Surveillance Network catalogue at the observation epochs, and finally 50 tracklets among them are associated with the breakup event of 1968-081E.

  9. 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. PMID:22430881

  10. Final Words

    ERIC Educational Resources Information Center

    Bers, Trudy

    2012-01-01

    This final chapter provides observations about institutional research in community colleges derived from the preceding chapters and the issue editors' own experiences. Taken as a whole, the chapters in this issue, as well as the editors' experiences, suggest several observations about institutional research in community colleges. These include the…

  11. 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. PMID:27311891

  12. 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.

  13. 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...

  14. 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...

  15. Comparison of calculations of fragment production rates

    SciTech Connect

    Canavan, G.H.

    1997-08-01

    Differences between NASA and DoD estimates of fragment production rates in space debris collisions are shown to be due primarily to different choices of the exponent in the debris distribution. The sensitivity to this parameter over the range of values consistent with experimental data is discussed.

  16. Spatial representation: maps of fragmented space.

    PubMed

    Giocomo, Lisa M

    2015-05-01

    Grid cells in medial entorhinal cortex are thought to act as a neural metric for spatial navigation. A new study has examined the ability of grid cells to use self-motion cues to form a global map across fragmented spaces. PMID:25942547

  17. Tracking Seed Coat Fragments in Cotton Ginning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High seed coat fragment (SCF) content in cotton bales causes processing problems in textile plants. This experiment was designed to determine the origin of SCF by tracking their occurrence through a conventional sequence of gin machinery. After the lint cleaner, lint contained an average of 12.25 ...

  18. 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.

  19. 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.

  20. 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.

  1. Achieving climate connectivity in a fragmented landscape.

    PubMed

    McGuire, Jenny L; Lawler, Joshua J; McRae, Brad H; Nuñez, Tristan A; Theobald, David M

    2016-06-28

    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

  2. Modified Fragmentation Function from Quark Recombination

    SciTech Connect

    Majumder, A.; Wang, Enke; Wang, Xin-Nian

    2005-07-26

    Within the framework of the constituent quark model, it isshown that the single hadron fragmentation function of a parton can beexpressed as a convolution of shower diquark or triquark distributionfunction and quark recombination probability, if the interference betweenamplitudes of quark recombination with different momenta is neglected.Therecombination probability is determined by the hadron's wavefunction inthe constituent quark model. The shower diquark or triquark distributionfunctions of a fragmenting jet are defined in terms of overlappingmatrices of constituent quarks and parton field operators. They aresimilar in form to dihadron or trihadron fragmentation functions in termsof parton operator and hadron states. Extending the formalism to thefield theory at finite temperature, we automatically derive contributionsto the effective single hadron fragmentation function from therecombination of shower and thermal constituent quarks. Suchcontributions involve single or diquark distribution functions which inturn can be related to diquark or triquark distribution functions via sumrules. We also derive QCD evolution equations for quark distributionfunctions that in turn determine the evolution of the effective jetfragmentation functions in a thermal medium.

  3. 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.

  4. 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…

  5. Chemical fragment arrays for rapid druggability assessment.

    PubMed

    Aretz, J; Kondoh, Y; Honda, K; Anumala, U R; Nazaré, M; Watanabe, N; Osada, H; Rademacher, C

    2016-07-12

    Incorporation of early druggability assessment in the drug discovery process provides a means to prioritize target proteins for high-throughput screening. We present chemical fragment arrays as a method that is capable of determining the druggability of a given target with low protein and compound consumption, enabling rapid decision making during early phases of drug discovery. PMID:26890187

  6. Overview of nuclear fragmentation models and needs

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Cucinotta, F. A.; Wilson, J. W. (Principal Investigator)

    1996-01-01

    It has been known for some time that adequate assessment of spacecraft shield requirements and concomitant estimates of astronauts radiation exposures from galactic cosmic radiation requires accurate, quantitative methods for characterizing these radiation fields as they pass through thick absorbers. The main nuclear interaction processes involved are (1) nuclear elastic and inelastic collisions, and (2) nuclear breakup (fragmentation) and electromagnetic dissociation (EMD). Nuclear fragmentation and EMD are important because they alter the elemental and isotopic composition of the transported radiation fields. At present, there is no suitably accurate theory for predicting nuclear fragmentation cross sections for all collision pairs and energies of interest in space radiation protection. Typical cross-section differences between theory and experiment range from about 25 percent to a factor of two. The resulting errors in transported flux, for high linear energy transfer (LET) particles, are comparble to these cross-section errors. In this overview, theoretical models of heavy ion fragmentation currently used to generate input data bases for cosmic-ray transport and shielding codes are reviewed. Their shortcomings are discussed. Further actions needed to improve their accuracy and generality are presented.

  7. Quantum properties of QCD string fragmentation

    NASA Astrophysics Data System (ADS)

    Todorova-Nová, Šárka

    2016-07-01

    A simple quantization concept for a 3-dim QCD string is used to derive properties of QCD flux tube from the mass spectrum of light mesons and to predict observable quantum effects in correlations between adjacent hadrons. The quantized fragmentation model is presented and compared with experimental observations.

  8. 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. PMID:25201767

  9. Molecular fragmentation induced by a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Kosmidis, Constantine E.; Ledingham, Kenneth W. D.; Kilic, H. S.; McCanny, T.; Singhal, Raghunandan P.; Smith, D.; Langley, Andrew J.

    1998-07-01

    The 90 femtosecond laser induced fragmentation at 375 nm for a number of different nitro-molecules is compared to that induced by a nanosecond laser at the same wavelength by means of time-of-flight mass spectrometry. The potential of femtosecond laser mass spectrometry for analytical purposes is discussed.

  10. 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...

  11. 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 ...

  12. 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.

  13. Analysis of Fragmentation and Resulting Shrapnel Penetration of Naturally Fragmenting Cylindrical Bombs

    SciTech Connect

    Gardner, S.E.

    2000-08-01

    Fragmentation of exploding cylinders and penetration mechanics of surrounding vessel walls were examined and a qualitative understanding was achieved. This understanding provided a basis for making simplifying approximations and assumptions that aided in creating a shrapnel penetration model. Several mathematical models were discussed, and results from 6 cylinder tests were analyzed in order to select a model that best represented the data. It was determined that the overall best mathematical model to predict shrapnel penetration uses the modified Gurney equation to calculate fragment velocity, the Mott equation to calculate largest fragment weight, and the Christman/Gehring equation to calculate penetration depth.

  14. 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.

  15. Localization of molecular orbitals: from fragments to molecule.

    PubMed

    Li, Zhendong; Li, Hongyang; Suo, Bingbing; Liu, Wenjian

    2014-09-16

    Conspectus Localized molecular orbitals (LMO) not only serve as an important bridge between chemical intuition and molecular wave functions but also can be employed to reduce the computational cost of many-body methods for electron correlation and excitation. Therefore, how to localize the usually completely delocalized canonical molecular orbitals (CMO) into confined physical spaces has long been an important topic: It has a long history but still remains active to date. While the known LMOs can be classified into (exact) orthonormal and nonorthogonal, as well as (approximate) absolutely localized MOs, the ways for achieving these can be classified into two categories, a posteriori top-down and a priori bottom-up, depending on whether they invoke the global CMOs (or equivalently the molecular density matrix). While the top-down approaches have to face heavy tasks of minimizing or maximizing a given localization functional typically of many adjacent local extrema, the bottom-up ones have to invoke some tedious procedures for first generating a local basis composed of well-defined occupied and unoccupied subsets and then maintaining or resuming the locality when solving the Hartree-Fock/Kohn-Sham (HF/KS) optimization condition. It is shown here that the good of these kinds of approaches can be combined together to form a very efficient hybrid approach that can generate the desired LMOs for any kind of gapped molecules. Specifically, a top-down localization functional, applied to individual small subsystems only, is minimized to generate an orthonormal local basis composed of functions centered on the preset chemical fragments. The familiar notion for atomic cores, lone pairs, and chemical bonds emerges here automatically. Such a local basis is then employed in the global HF/KS calculation, after which a least action is taken toward the final orthonormal localized molecular orbitals (LMO), both occupied and virtual. This last step is very cheap, implying that, after

  16. 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

  17. 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.

  18. Insights into 2-Chloropyrimidine fragmentation through a thermochemical analysis of the ionic fragments

    NASA Astrophysics Data System (ADS)

    Castrovilli, Mattea Carmen; Bolognesi, Paola; Casavola, Annarita; Cartoni, Antonella; Catone, Daniele; O'Keeffe, Patrick; Avaldi, Lorenzo

    2014-09-01

    In the present work we have studied the photoinduced ion chemistry of the 2Cl-pyrimidine molecule in the energy region 9-14 eV. The theoretical gas phase enthalpies of formation of the main fragments calculated using the G3B3 and G2 ab initio methods are compared to the experimental values, derived by the measured appearance energy of the fragments. This approach provides new insights into both the geometric structure of the ionic fragments and the basic mechanisms governing the molecular fragmentation. Contribution to the Topical Issue "Nano-scale Insights into Ion-beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Paulo Limão-Vieira and Malgorzata Smialek-Telega.

  19. [Fragmentation process of wetland landscape in watersheds of Sanjiang Plain, China].

    PubMed

    Liu, Hongyu; Lü, Xianguo; Zhang, Shikui; Yang, Qing

    2005-02-01

    The Sanjiang Plain is the largest fresh water wetland distribution area in China and the center of waterfowls breeding and habitat area in Asia, but over the past 50 years, more than 73% of its wetland had lost because of agricultural development, and as a result, the wetland biodiversity declines dramatically, and the remnant wetlands are in a very fragment state. Based on historical maps, remote sensing data and GIS techniques, this paper selected two watersheds to analyze their wetland landscape fragmentation process during 1950-2000. It was indicated that land reclamation resulted in a decrease of 98% wetland corridors in Qixing River, 90% in Naoli River, 87% in the middle reach of Bielahong River, and 94% in the lower reach of Bielahong River; The amount of isolated wetlands in watershed increased dramatically; The maximum patch areas of wetland decreased by 92.6% in Naoli River watershed and 74.6% in Bielahong River watershed, and the mean wetland patch area in the two watersheds decreased by 99%. Before 1983, the wetland landscape was in an extensive area distribution state (the index of patch density was < 0.1), but after 1983, it fragmented dramatically, with the index of patch density larger than 1.5. The shape fragmentation indices of wetland decreased from 1950 to 2000, indicating a very big change in wetland patch shapes in the watersheds. The area fragmentation indices of wetland also increased from 1950 to 2000, especially after 1983, showing that the wetlands were in a serious fragmentation state. The wetland landscape fragmentation changed from a landmass and island model to a satellite model, and finally to a completely isolated model, which indicated the great changes in spatial structure of wetland in the Sanjiang Plain. PMID:15852925

  20. Fragmentation and systematics of the pygmy dipole resonance in the stable N=82 isotones

    SciTech Connect

    Savran, D.; Loeher, B.; Elvers, M.; Endres, J.; Zilges, A.; Fritzsche, M.; Pietralla, N.; Ponomarev, V. Yu.; Romig, C.; Schnorrenberger, L.; Sonnabend, K.

    2011-08-15

    The low-lying electric dipole (E1) strength in the semimagic nucleus {sup 136}Xe has been measured, which finalizes the systematic survey to investigate the so-called pygmy dipole resonance (PDR) in all stable even N=82 isotones with the method of nuclear resonance fluorescence using real photons in the entrance channel. In all cases, a fragmented resonance-like structure of E1 strength is observed in the energy region 5-8 MeV. An analysis of the fragmentation of the strength reveals that the degree of fragmentation decreases toward the proton-deficient isotones, while the total integrated strength increases, indicating a dependence of the total strength on the neutron-to-proton ratio. The experimental results are compared to microscopic calculations within the quasiparticle phonon model. The calculation includes complex configurations of up to three phonons and is able to reproduce also the fragmentation of the E1 strength, which allows us to draw conclusions on the damping of the PDR. Calculations and experimental data are in good agreement on the degree of fragmentation and also on the integrated strength if the sensitivity limit of the experiments is taken into account.

  1. Generation of stable colloidal gold nanoparticles by ultrashort laser-induced melting and fragmentation

    NASA Astrophysics Data System (ADS)

    Vasa, Parinda; Sharma, Rahul; Singh, Mamraj; Dharmadhikari, Aditya K.; Dharmadhikari, Jayashree A.; Mathur, Deepak

    2014-09-01

    We report on generation of stable colloidal gold nanoparticles by ultrashort laser-induced melting and fragmentation. Irradiation of colloidal gold nanoparticles (of initial size larger than 25 nm) by 56 fs long, near-IR pulses of moderate fluence (1.3-5.3 J cm-2) generates very small (2.5 nm) nanoparticles with a narrow size distribution (±0.5 nm). Systematic measurements show the final size of fragmented nanoparticles to be (i) very weakly dependent on the original size and particle shape as well as of pump laser wavelength (800 nm, 1200 nm and 1350 nm), but (ii) strongly dependent on laser parameters; moreover, fragmentation is effectively controllable by pulse fluence and irradiation time. The fragmented particles appear to be contaminant free and have high crystalline quality. We find that the fragmented particles are stable over a time period of more than three months. Stable, contaminant-free, crystalline colloidal gold nanoparticles of sizes around 3 nm, with very narrow size distribution, have potential utility in diverse nanotechnological applications, ranging from biologically relevant imaging to nanoscopic generators of high-frequency mechanical vibrations in the GHz range.

  2. 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

  3. Gastric Perforation by Ingested Rabbit Bone Fragment

    PubMed Central

    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. PMID:27403113

  4. Fission Fragment characterization with FALSTAFF at NFS

    NASA Astrophysics Data System (ADS)

    Doré, D.; Farget, F.; Lecolley, F.-R.; Ledoux, X.; Lehaut, G.; Materna, T.; Pancin, J.; Panebianco, S.

    2013-03-01

    The Neutrons for Science (NFS) facility will be one of the first installations of the SPIRAL2 facility. NFS will be composed of a time-of-flight baseline and irradiation stations and will allow studying neutron-induced reactions for energies going from some hundreds of keV up to 40 MeV. Continuous and quasi-monoenergetic energy neutron beams will be available. Taking advantage of this new installation, the development of an experimental setup for a full characterization of actinide fission fragments in this energy domain has been undertaken. To achieve this goal a new detection system called FALSTAFF (Four Arm cLover for the STudy of Actinide Fission Fragments) in under development. In this paper, the characteristics of the NFS facility will be exposed and the motivations for the FALSTAFF experiment will be presented. The experimental setup will be described and the expected resolutions based on realistic GEANT4 simulations will be discussed.

  5. 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.

  6. Modeling fibril fragmentation in real-time

    NASA Astrophysics Data System (ADS)

    Tan, Pengzhen; Hong, Liu

    2013-08-01

    During the application of the mass-action-equation models to the study of amyloid fiber formation, time-consuming numerical calculations constitute a major bottleneck. To conquer this difficulty, here an alternative efficient method is introduced for the fragmentation-only model. It includes two basic steps: (1) simulate close-formed time-evolutionary equations for the number concentration P(t) derived from the moment-closure method; (2) reconstruct the detailed fiber length distribution based on the knowledge of moments obtained in the first step. Compared to direct calculation, our method speeds up the performance by at least 10 000 times (from days to seconds). The accuracy is also satisfactory if suitable functions for the approximate fibril length distribution are taken. Further application to the sonication studies on PI264-b-PFS48 micelles performed by Guerin et al. confirms our method is very promising for the real-time analysis of the experiments on fibril fragmentation.

  7. 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.

  8. 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.

  9. 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

  10. Anisotropic Neutron Evaporation from Spinning Fission Fragments

    NASA Astrophysics Data System (ADS)

    Stuttgé, L.; Dorvaux, O.; Gönnenwein, F.; Mutterer, M.; Kopatch, Yu.; Chernysheva, E.; Hanappe, F.; Hambsch, F.-J.

    2011-10-01

    Neutron evaporation anisotropy in the centre of mass of the rotating fission fragments in the spontaneous fission of 252Cf has been investigated within the CORA experiments. If it is well accepted that the bulk of emitted neutrons originate from an isotropic evaporation in the centre of mass of the moving fragments, discrepancies in experimental as well as in theoretical energy and angular distributions appear throughout many attempts performed by various authors. Scission neutrons most probably contribute but don't allow to explain totally the observed anisotropy. Due to its weak contribution to the total anisotropy, the centre of mass anisotropy is very difficult to be highlighted. A novel experimental approach has been developed to extract this effect and will be presented as well as some first results.

  11. Fragmentation pathways of ethylene after core ionization

    NASA Astrophysics Data System (ADS)

    Gaire, B.; Bocharova, I.; Sturm, F. P.; Gehrken, N.; Haxton, D. J.; Belkacem, A.; Weber, Th.; Zohrabi, M.; Ben-Itzhak, I.; Gatton, A.; Williams, J.; Reedy, D.; Nook, C.; Landers, A.; Gassert, H.; Zeller, S.; Voigtsberger, J.; Jahnke, T.; Doerner, R.

    2014-05-01

    We have measured the Auger electrons in coincidence with the recoil ions, resulting from the core ionization of ethylene molecules, by employing the COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS) method. The Auger-electron and recoil-ion energy maps are used to identify the fragmentation pathways and they are compared to the valence photo-double-ionization of ethylene. The dicationic electronic states favored by the propensity rules are identified and their role on the fragmentation pathways is discussed. The molecular-frame Auger electron angular distribution provides further insight into the breakup of this molecule after core ionization. Supported by the Director, Office of Science, Office of Basic Energy Sciences, and by the Division of Chemical Sciences, Geosciences, and Biosciences of the U.S. Department of Energy at LBNL under Contract No. DE-AC02-05CH11231.

  12. 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.

  13. Near Earth asteroid orbit perturbation and fragmentation

    NASA Astrophysics Data System (ADS)

    Ahrens, Thomas J.; Harris, Alan W.

    1992-03-01

    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.

  14. The clearance of human fibrinogen fragments D1, D2, D3 and fibrin fragment D1 dimer in mice.

    PubMed

    Pizzo, S V; Pasqua, J J

    1982-10-01

    The clearance of human fibrinogen fragments D1, D2, D3 and fibrin fragment D1 dimer were studied in the mouse model. Clearance of these fragments is a complex process involving clearance from blood into three other compartments. The overall clearance of fragment D1 and its dimer were essentially identical. Fragments D2 and D3 cleared at a progressively slower rate. Competition studies were performed between 125I-labeled fragment D1 and large molar excesses of unlabeled human fragments D1, D2, D3, D1 dimer, fragment E, fibrinogen, macroalbumin, mannan and asialoorosomucoid. Of these ligands only the fragment D variants competed for the clearance of 125I-labeled fragment D1. Cross-competition was observed when 125I-labeled fragment D1 dimer was cleared in the presence of a large molar excesses of fragment D1. Autopsies demonstrated that injected fragments D1, D2, D3 and D1 dimer cleared primarily in liver and kidneys. In some clearance studies, livers were perfused with tissue culture fluid, subjected to light microscopic autoradiography, and silver grain counts performed to localize cleared fragment D1. These experiments indicated that 80% of the liver uptake was in hepatocytes. However, when silver grain counts were normalized for the number of parenchymal and nonparenchymal cells, the distribution of silver grains was essentially identical (1.8 and 1.6 grains per cells, respectively). It is concluded that fragments D1, D2, D3 and D1 dimer are recognized by a similar clearance pathway. Since neither fibrinogen nor fragment E competed for the clearance of fragment D1, it is suggested that determinants present in the fragment D domain become exposed after plasmin attack on fibrinogen and are responsible for clearance. PMID:7138910

  15. 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.

  16. 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.

  17. Space fragment in studies of the Earth

    NASA Technical Reports Server (NTRS)

    Avanesov, G. A.; Ziman, Y. L.

    1982-01-01

    The fragment apparatus, mounted on board the artificial earth satellite Meteor, was created for the operational study of the natural resources of the Earth in the optical range of electromagnetic waves. The orbit of the satellite at an altitude of about 650 km makes it possible to observe the same sectors of the Earth's surface at the same time of day with a periodicity of 15 days.

  18. New results on jet fragmentation at CDF

    SciTech Connect

    Jindariani, Sergo; /Florida U.

    2006-12-01

    Presented are the latest results of jet fragmentation studies at the Tevatron using the CDF Run II detector. Studies include the distribution of transverse momenta (Kt) of particles jets, two-particle momentum correlations, and indirectly global event shapes in p{bar p} collisions. Results are discussed within the context of recent Next-to-Leading Log calculations as well as earlier experimental results from the Tevatron and e{sup +}e{sup -} colliders.

  19. Molecular electrostatic potentials by systematic molecular fragmentation

    SciTech Connect

    Reid, David M.; Collins, Michael A.

    2013-11-14

    A simple method is presented for estimating the molecular electrostatic potential in and around molecules using systematic molecular fragmentation. This approach estimates the potential directly from the electron density. The accuracy of the method is established for a set of organic molecules and ions. The utility of the approach is demonstrated by estimating the binding energy of a water molecule in an internal cavity in the protein ubiquitin.

  20. 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.

  1. Preferred modes of decay in nuclear fragmentation

    SciTech Connect

    Aranda, A.; Lopez, J.A.; Wu, Z.

    1997-02-01

    Recent experimental studies show a characteristic energy dependence of the different fragmentation modes in heavy-ion reactions at intermediate energies. In this work we study this dependence and find that, in multifragmentation, just like in low-energy fission, some modes of decay are more probable than the rest. We argue that these high-probability mass partitions are ultimately responsible for the observed energy dependence. {copyright} {ital 1997} {ital The American Physical Society}

  2. Shear fragmentation of unstable flux flow

    NASA Astrophysics Data System (ADS)

    Kunchur, Milind N.; Ivlev, Boris I.; Knight, James M.

    2002-08-01

    When free flux flow is pushed beyond its instability, the homogeneous flow becomes spatially distorted leading to a new class of dynamic phases with steps in resistivity. At high-flux densities B, the relatively incompressible vortex matter fragments into domains of constant shear curvature, leading to a horizontal-sawtooth-shaped current-voltage characteristic. Measurements on Y1Ba2Cu3O7-δ films confirm this behavior and are quantitatively consistent with the model, which has no adjustable parameters.

  3. Nuclear fragmentation studies for microelectronic application

    NASA Technical Reports Server (NTRS)

    Ngo, Duc M.; Wilson, John W.; Buck, Warren W.; Fogarty, Thomas N.

    1989-01-01

    A formalism for target fragment transport is presented with application to energy loss spectra in thin silicon devices. Predicted results are compared to experiments with the surface barrier detectors of McNulty et al. The intranuclear cascade nuclear reaction model does not predict the McNulty experimental data for the highest energy events. A semiempirical nuclear cross section gives an adequate explanation of McNulty's experiments. Application of the formalism to specific electronic devices is discussed.

  4. 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.

  5. Fragment Screening of Human Aquaporin 1.

    PubMed

    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

  6. 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. PMID:25789413

  7. Catastrophic fragmentation of asteroids: Evidence from meteorites

    NASA Technical Reports Server (NTRS)

    Keil, K.; Haack, H.; Scott, E. R. D.

    1994-01-01

    Meteorites are impact-derived fragments from approximately 85 parent bodies. For seven of these bodies, the meteorites record evidence suggesting that they may have been catastrophically fragmented. We identify three types of catastrophic events: (1) impact and reassemble events greater than 4.4 Gy ago, involving molten or very hot parent bodies (greater than 1200 C); this affected the parent bodies of the ureilites, Shallowater, and the mesosiderites. In each case, the fragments cooled rapidly (approximately 1-1000 C/day) and then reassembled. (2) Later impacts involving cold bodies which, in some cases, reassembled; this occurred on the H and L ordinary chondrite parent bodies. The L parent body probably suffered another catastrophic event about 500 My ago. (3) Recent impacts of cold, multi-kilometer-sized bodies that generated meter-sized meteoroids; this occurred on the parent bodies of the IIIAB irons (650 My ago), the IVA irons (400 My ago), and the H ordinary chondrite (7 My ago).

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. Alzheimer's disease: identification and development of β-secretase (BACE-1) binding fragments and inhibitors by dynamic ligation screening (DLS).

    PubMed

    Fernández-Bachiller, María Isabel; Horatscheck, André; Lisurek, Michael; Rademann, Jörg

    2013-07-01

    The application of dynamic ligation screening (DLS), a methodology for fragment-based drug discovery (FBDD), to the aspartic protease β-secretase (BACE-1) is reported. For this purpose, three new fluorescence resonance energy transfer (FRET) substrates were designed and synthesized. Their kinetic parameters (Vmax , KM , and kcat ) were determined and compared with a commercial substrate. Secondly, a peptide aldehyde was designed as a chemically reactive inhibitor (CRI) based on the Swedish mutation substrate sequence. Incubation of this CRI with the protease, a FRET substrate, and one amine per well taken from an amine library, which was assembled by a maximum common substructure (MCS) approach, revealed the fragment 3-(3-aminophenyl)-2H-chromen-2-one (1) to be a competitive BACE-1 inhibitor that enhanced the activity of the CRI. Irreversibly formed fragment combination products of 1 with the initial peptide sequence were active and confirmed the targeting of the active site through the ethane-1,2-diamine isostere. Finally, structure-assisted combination of fragment 1 with secondary fragments that target the S1 site in hit optimization yielded novel, entirely fragment-based BACE-1 inhibitors with up to 30-fold improved binding affinity. Interactions with the protein were explained by molecular modeling studies, which indicate that the new fragment combinations interact with the catalytic aspartic acid dyad, as well as with the adjacent binding sites required for potency. PMID:23757181

  13. 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

  14. Fragmentation Point Detection of JPEG Images at DHT Using Validator

    NASA Astrophysics Data System (ADS)

    Mohamad, Kamaruddin Malik; Deris, Mustafa Mat

    File carving is an important, practical technique for data recovery in digital forensics investigation and is particularly useful when filesystem metadata is unavailable or damaged. The research on reassembly of JPEG files with RST markers, fragmented within the scan area have been done before. However, fragmentation within Define Huffman Table (DHT) segment is yet to be resolved. This paper analyzes the fragmentation within the DHT area and list out all the fragmentation possibilities. Two main contributions are made in this paper. Firstly, three fragmentation points within DHT area are listed. Secondly, few novel validators are proposed to detect these fragmentations. The result obtained from tests done on manually fragmented JPEG files, showed that all three fragmentation points within DHT are successfully detected using validators.

  15. 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.

  16. 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.

  17. 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...

  18. Graphical Methods for Separating Beam and Target Fragmentation Regions

    NASA Astrophysics Data System (ADS)

    Londergan, J. T.; Mathieu, V.; Szczepaniak, A. P.; Joint Physics Analysis Center Collaboration

    2015-10-01

    For reactions involving three or more final-state particles, graphical methods can help to elucidate the dominant reaction mechanism. Van Hove introduced a longitudinal phase space plot, which categorizes reaction products in terms of their longitudinal moments. We review the construction of such plots, and show how they are useful in separating beam and target fragmentation regimes. We summarize the information that can be obtained from Van Hove plots, and use these plots to analyze reactions with three or four strongly-interacting particles in the final state. As an example, we apply these methods to simulated data for the reaction π- + p -->π- + η (η ') + p . We show how cuts in the Van Hove plot can be utilized to isolate various two-body processes that contribute to this reaction. We also show how the dominant reaction processes change with the beam energy. VM and APS supported by US DOE, Grants DE-AC05-06OR23177 and DE-FG0287-ER40365; JTL by NSF-PHY-1205019.

  19. Alternative downstream processes for production of antibodies and antibody fragments.

    PubMed

    Arakawa, Tsutomu; Tsumoto, Kouhei; Ejima, Daisuke

    2014-11-01

    Protein-A or Protein-L affinity chromatography and virus inactivation are key processes for the manufacturing of therapeutic antibodies and antibody fragments. These two processes often involve exposure of therapeutic proteins to denaturing low pH conditions. Antibodies have been shown to undergo conformational changes at low pH, which can lead to irreversible damages on the final product. Here, we review alternative downstream approaches that can reduce the degree of low pH exposure and consequently damaged product. We and others have been developing technologies that minimize or eliminate such low pH processes. We here cover facilitated elution of antibodies using arginine in Protein-A and Protein-G affinity chromatography, a more positively charged amidated Protein-A, two Protein-A mimetics (MEP and Mabsorbent), mixed-mode and steric exclusion chromatography, and finally enhanced virus inactivation by solvents containing arginine. This article is part of a Special Issue entitled: Recent advances in molecular engineering of antibody. PMID:24859179

  20. An (e, 2e + ion) investigation of fragmentation of methane induced by low energy electrons

    NASA Astrophysics Data System (ADS)

    Xu, S.; Ma, X.; Ren, X.; Senftleben, A.; Pflüger, T.; Ullrich, J.; Yan, S.; Zhang, P.; Yang, J.; Dorn, A.

    2014-04-01

    An (e, 2e+ion) investigation of the ionization and dissociation of methane by 54 eV electron impact is performed using the advanced reaction microscope. By measuring two electrons and the ion in the final state in triple coincidence, the species of the ions are identified, and the energies deposited into the target are determined. The species and the kinetic energies of the fragmented ion show strong dependence on the intermediate states of the parent ion.

  1. [The fragmentation of representational space in schizophrenia].

    PubMed

    Plagnol, A; Oïta, M; Montreuil, M; Granger, B; Lubart, T

    2003-01-01

    Existent neurocognitive models of schizophrenia converge towards a core of impairments involving working memory, context processing, action planning, controlled and intentional processing. However, the emergence of this core remains itself difficult to explain and more specific hypotheses do not explain the heterogeneity of schizophrenia. To overcome these limits, we propose a new paradigm based on representational theory from cognitive science. Some recent developments of this theory enable us to describe a subjective universe as a representational space which is displayed from memory. We outline a conceptual framework to construct such a representational space from analogical -representations that can be activated in working memory and are connected to a network of symbolic structures. These connections are notably made through an analytic process of the analogical fragments, which involves the attentional focus. This framework allows us to define rigorously some defense processes in response to traumatic tensions that are expressed on the representational space. The fragmentation of representational space is a consequence of a defensive denial based on an impairment of the analytic process. The fragmentation forms some parasitic areas in memory which are excluded from the main part of the representational space and disturb information processing. The key clinical concepts of paranoid syndromes can be defined in this conceptual framework: mental automatism, delusional intuition, acute destructuration, psychotic dissociation, and autistic withdrawal. We show that these syndromes imply each other, which in return increases the fragmentation of the representational space. Some new concepts emerge naturally in this framework, such as the concept of "suture" which is defined as a link between a parasitic area and the main representational space. Schizophrenia appears as a borderline case of fragmentation of the representational space. This conceptual framework is

  2. 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

  3. [The emotional assessment by test subjects of short musical fragments].

    PubMed

    Al'tman, Ia A; Guzikov, B M; Zakharova, L E; Poltorak, S V

    1999-01-01

    Emotional estimation of 96 short (2-5 s) musical fragments was studied in 6 healthy subjects. Fragments were scored on a 5-point scale. Statistically significant difference in estimations of specific musical fragments (positive, negative, or indifferent) was found. PMID:10693273

  4. 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.

  5. 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.

  6. 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.

  7. Guided reconstitution of membrane protein fragments.

    PubMed

    Cohen, Leah S; Arshava, Boris; Kauffman, Sarah; Mathew, Elizabeth; Fracchiolla, Katrina E; Ding, Fa-Xiang; Dumont, Mark E; Becker, Jeffrey M; Naider, Fred

    2014-01-01

    Structural analysis by NMR of G protein-coupled receptors (GPCRs) has proven to be extremely challenging. To reduce the number of peaks in the NMR spectra by segmentally labeling a GPCR, we have developed a Guided Reconstitution method that includes the use of charged residues and Cys activation to drive heterodimeric disulfide bond formation. Three different cysteine-activating reagents: 5-5'-dithiobis(2-nitrobenzoic acid) [DTNB], 2,2'-dithiobis(5-nitropyridine) [DTNP], and 4,4'-dipyridyl disulfide [4-PDS] were analyzed to determine their efficiency in heterodimer formation at different pHs. Short peptides representing the N-terminal (NT) and C-terminal (CT) regions of the first extracellular loop (EL1) of Ste2p, the Saccharomyces cerevisiae alpha-factor mating receptor, were activated using these reagents and the efficiencies of activation and rates of heterodimerization were analyzed. Activation of NT peptides with DTNP and 4-PDS resulted in about 60% yield, but heterodimerization was rapid and nearly quantitative. Double transmembrane domain protein fragments were biosynthesized and used in Guided Reconstitution reactions. A 102-residue fragment, 2TM-tail [Ste2p(G31-I120C)], was heterodimerized with CT-EL1-tail(DTNP) at pH 4.6 with a yield of ∼75%. A 132-residue fragment, 2TMlong-tail [Ste2p(M1-I120C)], was expressed in both unlabeled and (15)N-labeled forms and used with a peptide comprising the third transmembrane domain, to generate a 180-residue segmentally labeled 3TM protein that was found to be segmentally labeled using [(15)N,(1)H]-HSQC analysis. Our data indicate that the Guided Reconstitution method would be applicable to the segmental labeling of a membrane protein with 3 transmembrane domains and may prove useful in the preparation of an intact reconstituted GPCR for use in biophysical analysis and structure determination. PMID:23897574

  8. 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.

  9. TRANSVERSE POLARIZATION DISTRIBUTION AND FRAGMENTATION FUNCTIONS

    SciTech Connect

    BOER,D.

    2000-04-11

    The authors discuss transverse polarization distribution and fragmentation functions, in particular, T-odd functions with transverse momentum dependence, which might be relevant for the description of single transverse spin asymmetries. The role of intrinsic transverse momentum in the expansion in inverse powers of the hard scale is elaborated upon. The sin {phi} single spin asymmetry in the process e {rvec p} {r_arrow} e{prime} {pi}{sup +} X as recently reported by the HERMES Collaboration is investigated, in particular, by using the bag model.

  10. 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.

  11. Stochastic Equation of Fragmentation and Branching Processes Related to Avalanches

    NASA Astrophysics Data System (ADS)

    Beznea, Lucian; Deaconu, Madalina; Lupaşcu, Oana

    2016-02-01

    We give a stochastic model for the fragmentation phase of an avalanche. We construct a fragmentation-branching process related to the avalanches, on the set of all fragmentation sizes introduced by Bertoin. A fractal property of this process is emphasized. We also establish a specific stochastic differential equation of fragmentation. It turns out that specific branching Markov processes on finite configurations of particles with sizes bigger than a strictly positive threshold are convenient for describing the continuous time evolution of the number of the resulting fragments. The results are obtained by combining analytic and probabilistic potential theoretical tools.

  12. Collective flow properties of intermediate mass fragments and isospin effects in fragmentation at Fermi energies

    SciTech Connect

    Baran, V.; Zus, R.; Colonna, M.; Di Toro, M.

    2013-11-13

    Within a microscopic transport model (Stochastic Mean Field) we analyze the collective flow properties associated to the intermediate mass fragments produced in nuclear fragmentation. We study the transverse and elliptic flow parameters for each rank in mass hierarchy. The results are plotted for {sup 124}Sn + {sup 124}Sn systems at an energy of 50AMeV and for an impact parameter b=4fm. The correlation with the dynamics of the isospin degree of freedom is also discussed and the results are presented for the same systems.

  13. 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).

  14. 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.

  15. 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.

  16. 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.

  17. Kaon fragmentation function from NJL-jet model

    SciTech Connect

    Matevosyan, Hrayr H.; Thomas, Anthony W.; Bentz, Wolfgang

    2010-07-27

    The NJL-jet model provides a sound framework for calculating the fragmentation functions in an effective chiral quark theory, where the momentum and isospin sum rules are satisfied without the introduction of ad hoc parameters [1]. Earlier studies of the pion fragmentation functions using the Nambu-Jona-Lasinio (NJL) model within this framework showed good qualitative agreement with the empirical parameterizations. Here we extend the NJL-jet model by including the strange quark. The corrections to the pion fragmentation function and corresponding kaon fragmentation functions are calculated using the elementary quark to quark-meson fragmentation functions from NJL. The results for the kaon fragmentation function exhibit a qualitative agreement with the empirical parameterizations, while the unfavored strange quark fragmentation to pions is shown to be of the same order of magnitude as the unfavored light quark's. The results of these studies are expected to provide important guidance for the analysis of a large variety of semi-inclusive data.

  18. Fragmentation of Structural Energetic Materials: Implications for Performance

    NASA Astrophysics Data System (ADS)

    Aydelotte, Brady; Braithwaite, Christopher; Thadhani, Naresh

    2013-06-01

    Fragmentation results for structural energetic materials based on intermetallic forming mixtures are reviewed and the implications of the fragment populations are discussed. Cold Sprayed Ni+Al and explosively compacted mixtures of Ni+Al+W and Ni+Al+W+Zr powders were fabricated into ring shaped samples and subjected to fragmentation tests. Ring velocity was monitored and fragments were soft captured in order to study the fragmentation process. It was determined that the fragments produced by these structural energetic materials are much smaller than those typically produced by ductile metals such as steel or aluminum. This has implications for combustion processes that may occur subsequent to the fragmentation process. ONR/MURI grant No. N00014-07-1-0740 Dr. Cliff Bedford PM.

  19. A framework for integrating thermal biology into fragmentation research.

    PubMed

    Tuff, K T; Tuff, T; Davies, K F

    2016-04-01

    Habitat fragmentation changes thermal conditions in remnant patches, and thermal conditions strongly influence organism morphology, distribution, and activity patterns. However, few studies explore temperature as a mechanism driving ecological responses to fragmentation. Here we offer a conceptual framework that integrates thermal biology into fragmentation research to better understand individual, species, community, and ecosystem-level responses to fragmentation. Specifically, the framework addresses how fragmentation changes temperature and how the effects of those temperature changes spread through the ecosystem, from organism response via thermal sensitivity, to changes in species distribution and activity patterns, to shifts in community structure following species' responses, and ultimately to changes in ecosystem functions. We place a strong emphasis on future research directions by outlining "Critical gaps" for each step of the framework. Empirical efforts to apply and test this framework promise new understanding of fragmentation's ecological consequences and new strategies for conservation in an increasingly fragmented and warmer world. PMID:26892491

  20. Fission fragment rockets: A potential breakthrough

    SciTech Connect

    Chapline, G.F.; Dickson, P.W.; Schnitzler, B.G.

    1988-01-01

    A new reactor concept which has the potential of enabling extremely energetic and ambitious space propulsion missions is described. Fission fragments are directly utilized as the propellant by guiding them out of a very low density core using magnetic fields. The very high fission fragment exhaust velocities yield specific impulses of approximately a million seconds while maintaining respectable thrust levels. Specific impulses of this magnitude allow acceleration of significant payload masses to several percent of the velocity of light and enable a variety of interesting missions, e.g., payloads to the nearest star, Alpha Centauri, in about a hundred years for very rapid solar system transport. The parameters reported in this paper are based on a very preliminary analysis. Considerable trade-off studies will be required to find the optimum system. We hope the optimum system proves to be as attractive as our preliminary analysis indicates, although we must admit that our limited effort is insufficient to guarantee any specific level of performance.

  1. 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

  2. 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.

  3. Low temperature chemical fragmentation of coal

    SciTech Connect

    Deno, N. C.; Curry, K.; Jones, A. D.; Minard, R.; Potter, T.; Rakitsky, W.; Wagner, K.; Yevak, R. J.

    1980-01-01

    Trifluoroperoxyacetic acid chemically fragments coals at 25 to 80/sup 0/. The reagent is so selective for oxidizing aromatic rings and is so inert towards benzylic hydrogen that isopropylbenzene, tetralin, indan, and dihydrophenanthrene have their benzene ring(s) totally destroyed without any evidence of oxidation at the benzylic hydrogen. The fragments contain more and different structural information relative to conventional oxidations with Mn VII, Cr VI, HNO/sub 3/, and O/sub 2/. These latter selectively oxidize benzylic hydrogen. Products from 37 selected coals show that 9,10-dihydroanthracene and 9,10-dihydrophenanthrene units are prominent features in most bituminous coals in accord with Given's structure of coal. Their frequency accounts for the fact that no continuous fused ring structure or graphite structure exists. The only simple alkyl substituent is methyl. Liquefaction (solvent refining) sharply increases the amount of arylmethyl and aromatic structure and causes the appearance of unsubstituted phenyl groups. Nitric acid degradations have been reinvestigated and are developed into a premier method for analyzing the amounts and lengths of linear alkane chains in coals. Generally the amounts of such chains represents 0 to 2% of the carbon in coal, but in one Utah coal they account for about 42% of the carbons.

  4. 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.

  5. On fragmentation of meteoroids in interplanetary space

    NASA Astrophysics Data System (ADS)

    Porubčan, V.; Tóth, J.; Yano, H.

    2002-10-01

    A possible fragmentation of meteoroids in interplanetary space inferred from grouping of particles in meteor streams is discussed. There is a conviction maintained by many observers that meteors within the streams are observed to be clustered in pairs or larger groups more frequently than one could expect from random distribution. The rate of dispersive effects indicates that the lifetime of any such a group of meteoroids is very limited. Therefore, if real, the pairs or groups must be due to recent fragmentation of larger meteoroids. Analyses based on visual observations of meteor streams lead to contradictory results. More conclusive are analyses based on radio measurements, which present a negative result concerning the permanent meteor showers with the stream structures at their middle and late evolutionary stages, and an indication of a positive result for younger dense stream structures of recent origin. Analysis of the 1969 Leonid display obtained by the Springhill high-power radar shows that about 10% of the population around the shower maximum is associated in close groups, within a distance up to of about 10 km and confined to an effective stream width comparable to the diameter of the Earth. The recent Leonid returns with the storm in 1999 provided a possibility to verify a non-random grouping of particles within this young filament of the stream. The analysis and results based on TV observations of the storm are presented and discussed.

  6. Fragment-size prediction during dynamic fragmentation of melted tin. Experimental investigation and modelling issues

    NASA Astrophysics Data System (ADS)

    Roy, Gilles; Signor, Loic; de Resseguier, Thibaut; Dragon, Andre; Llorca, Fabrice

    2007-06-01

    A triangular shock-wave of sufficient intensity propagating in a metal sample may induce melting. When it reaches the free surface, tensile stresses are generated in the liquid state and lead to the creation of an expanding continuum of liquid debris. This phenomenon called micro-spalling consists of a dynamic fragmentation process in the melted material. Relevant data are still few but important for developing robust and physics-based models. Recently, we have reported a qualitative investigation of micro-spall in tin samples submitted to laser shocks [J. Appl. Phys. 101, 013506, 2007]. The present paper contains new experimental results including fragment recovery using a low density PVC-foam and post-test evaluation of the fragment-size distribution using X-ray microtomography. These results are compared to theoretical predictions from hydrocode simulations coupled with a modified formulation of the well-known energy fragmentation model of D.E. Grady [J. Mech. Phys. Sol., 36(3), pp.353-384, 1988].

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

    PubMed

    The, Matthew; Käll, Lukas

    2016-03-01

    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). PMID:26653874

  8. Fission Fragment Charge and Mass Distributions from Intermediate-Energy Reactions of 238-U Projectiles

    NASA Astrophysics Data System (ADS)

    Souliotis, G. A.; Loveland, W.; Zyromski, K. E.; Wozniak, G. J.; Morrissey, D. J.; Aleklett, Kjell

    1999-10-01

    The charge, mass and velocity distributions of fission fragments from the interaction of 20 MeV/nucleon 238-U projectiles with 27-Al and 208-Pb have been measured using the MSU A1200 fragment separator. The observed distributions from the U+Al reaction are consistent with fission following fusion-like events giving rise to products that are very n-deficient relative to the line of beta-stability. However, the distributions from the U+Pb reaction are consistent with fission following quasielastic or deep-inelastic collisions, resulting in fragments that are neutron rich. Substantial yields of very n-rich nuclei are observed. Estimates of rates of important n-rich nuclides from a typical second generation projectile-fragmentation (PF) facility are given. Finally, the importance of the present cross section data for the planning of next generation intermediate-energy PF facilities able to produce short-lived neutron-rich radioactive beams by fission of heavy projectiles is discussed.

  9. Microsatellite analysis of demographic genetic structure in fragmented populations of the tropical tree Symphonia globulifera.

    PubMed

    Aldrich, P R; Hamrick, J L; Chavarriaga, P; Kochert, G

    1998-08-01

    We developed genetic markers for three microsatellite loci in the tropical tree Symphonia globulifera and used them to examine the demographic genetic consequences of forest fragmentation. High levels of genetic variation were revealed in samples of adults, saplings, and seedlings. The more-variable loci exhibited less stability in allelic composition across sites and stages. The number of alleles per hectare (ha) of forest was similar when continuous forest plots were compared to plots from fragmented forest for all three stages. This pattern also held for the number of unique multilocus adult and sapling genotypes, but the number of unique seedling genotypes per ha of fragmented forest greatly exceeded expectations based on continuous forest data, probably due to the concentration of seeds into remnant forest patches by foraging bats. Significant inbreeding and genetic differentiation were most often associated with the fragmented forest and the seedlings. Finally, principal component analysis reaffirmed that a bottleneck, acting in concert with pre-existing genetic structure in the adults, had led to enhanced and rapid divergence in the seedlings following deforestation, a result that is of central interest for landscape management. PMID:9711860

  10. 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

  11. Ionizations and fragmentations of benzene, methylbenzene, and chlorobenzene in strong IR and UV laser fields

    NASA Astrophysics Data System (ADS)

    Zhang, Jun-Feng; Lü, Hang; Zuo, Wan-Long; Xu, Hai-Feng; Jin, Ming-Xing; Ding, Da-Jun

    2015-11-01

    Ionizations and fragmentations of benzene, methylbenzene, and chlorobenzene are studied in linearly polarized 50-fs, 800-nm and 400-nm strong laser fields using a time-of-flight mass spectrometer. It is shown that at low laser intensity, the parent ions are dominant for any one of the molecules in an 800-nm strong laser field, while extensive fragmentation is observed in a 400-nm laser field, which can be understood by the resonant photon absorption of molecular cations. The ratio of the yield of the parent ion to the yield of the total ion for each molecule is measured as a function of laser intensity in a range from 1.0 × 1013 W/cm2 to 4.0 × 1014 W/cm2, in either the 800-nm or 400-nm laser field. The results show that the fragmentation of the aromatic molecules increases significantly as the laser intensity is increased. Possible mechanisms for fragmentation in strong laser fields are discussed. Finally, the saturation intensity of ionization of the titled molecules is also determined. Project supported by the National Basic Research Program of China (Grant No. 2013CB922200) and the National Natural Science Foundation of China (Grant No. 11274140).

  12. Final Report

    SciTech Connect

    Wessels, B. W.

    2002-08-02

    Final report for program on the study of structure and properties of epitaxial oxide films. The defect structure of epitaxial oxide thin films was investigated. Both binary and complex oxides were studied. Epitaxial oxides were synthesized by organometallic chemical vapor deposition (OMCVD). This technique has been found to be highly versatile for the synthesis of a wide range of epitaxial oxide including dielectrics, ferroelectrics and high T{sub c} superconductors. Systems investigated include the binary oxides ZnO and TiO{sub 2} and ferroelectric oxides BaTiO{sub 3}, BaSrTiO{sub 3} and KNbO{sub 3}. Techniques used to evaluate the defect structure included deep level transient spectroscopy (DLTS), photocapacitance spectroscopy, and photoluminescence (PL) spectroscopy. High purity, stoichiometric oxide films were deposited and their defect structure evaluated. Epitaxial ZnO was deposited at temperatures as low as 250 C. PL indicated only near band edge ultraviolet emission showing that both extrinsic and intrinsic point defects could be significantly lowered in OMCVD derived thin films compared to that of the bulk. This presumably was a result of low deposition temperatures and high purity starting materials. Ferroelectric oxides epitaxial thin films of BaTiO{sub 3} and the solid solution BaSrTiO{sub 3} were synthesized and the defect structure determined. Photocapacitance spectroscopy was developed to quantify electrically active defects in the oxides. Defects with concentrations as low as 10{sup 14} cm{sup -3} were observed and their properties determined. A new model was developed for the electronic transport properties of intrinsic and extrinsic BaTiO{sub 3}. A transport model was proposed whereby conduction in La doped films occurs via hopping in localized states within a pseudogap formed between a lower Hubbard band and the conduction band edge. The influence of the size effect on the ferroelectric phase transition in the thin films was investigated. The

  13. 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

  14. An Arp2/3 nucleated F-actin shell fragments nuclear membranes at nuclear envelope breakdown in starfish oocytes.

    PubMed

    Mori, Masashi; Somogyi, Kálmán; Kondo, Hiroshi; Monnier, Nilah; Falk, Henning J; Machado, Pedro; Bathe, Mark; Nédélec, François; Lénárt, Péter

    2014-06-16

    Animal cells disassemble and reassemble their nuclear envelopes (NEs) upon each division. Nuclear envelope breakdown (NEBD) serves as a major regulatory mechanism by which mixing of cytoplasmic and nuclear compartments drives the complete reorganization of cellular architecture, committing the cell for division. Breakdown is initiated by phosphorylation-driven partial disassembly of the nuclear pore complexes (NPCs), increasing their permeability but leaving the overall NE structure intact. Subsequently, the NE is rapidly broken into membrane fragments, defining the transition from prophase to prometaphase and resulting in complete mixing of cyto- and nucleoplasm. However, the mechanism underlying this rapid NE fragmentation remains largely unknown. Here, we show that NE fragmentation during NEBD in starfish oocytes is driven by an Arp2/3 complex-nucleated F-actin "shell" that transiently polymerizes on the inner surface of the NE. Blocking the formation of this F-actin shell prevents membrane fragmentation and delays entry of large cytoplasmic molecules into the nucleus. We observe spike-like protrusions extending from the F-actin shell that appear to "pierce" the NE during the fragmentation process. Finally, we show that NE fragmentation is essential for successful reproduction, because blocking this process in meiosis leads to formation of aneuploid eggs. PMID:24909322

  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. Disappearance of insectivorous birds from tropical forest fragments

    PubMed Central

    Şekercioḡlu, Çaḡan H.; Ehrlich, Paul R.; Daily, Gretchen C.; Aygen, Deniz; Goehring, David; Sandí, Randi F.

    2002-01-01

    Determining the impact of forest disturbance and fragmentation on tropical biotas is a central goal of conservation biology. Among tropical forest birds, understory insectivores are particularly sensitive to habitat disturbance and fragmentation, despite their relatively small sizes and freedom from hunting pressure. Why these birds are especially vulnerable to fragmentation is not known. Our data indicate that the best determinant of the persistence of understory insectivorous birds in small fragments is the ability to disperse through deforested countryside habitats. This finding contradicts our initial hypothesis that the decline of insectivorous birds in forest fragments is caused by impoverished invertebrate prey base in fragments. Although we observed significantly fewer insectivorous birds in smaller fragments, extensive sampling of invertebrate communities (106,082 individuals) and avian diets (of 735 birds) revealed no important differences between large and small fragments. Neither habitat specificity nor drier fragment microclimates seemed critical. Bird species that were less affected by forest fragmentation were, in general, those that used the deforested countryside more, and we suggest that the key to their conservation will be found there. PMID:11782549

  17. 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.

  18. 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.

  19. Experimental studies of collision and fragmentation phenomena

    NASA Technical Reports Server (NTRS)

    Hartmann, William K.; Davis, D. R.; Weidenschilling, S. J.

    1987-01-01

    The reduction and publication of an extensive data set collected in experiments over several years at Ames and PSI is briefly examined. Hartmann has been assembling data sets from his experiments on catastrophic fragmentation of various materials, including basalt, other igneous rock, ice, and weak dirt clods. Weidenschilling and Davis have continued to gather and reduce data on oblique impacts. The data indicate a power law distribution of ejecta mass vs. velocity, with a slope that is independent of azimuth, and does not vary with impact angle from normal impacts to at least 75 deg from vertical. In order to improve models of coagulation of dust aggregates in the solar nebula, SJW developed an apparatus for drop tests of fragile projectiles. Davis and Weidenschilling continued to collect and analyze experimental data on collisional catastrophic disruption at the Ames Vertical Gun Range.

  20. Spin Effects in High Energy Fragmentation Processes

    NASA Astrophysics Data System (ADS)

    Liang, Zuo-Tang

    Recent measurements, in particular those on Λ polarization and spin alignment of vector mesons in e+e- annihilation at LEP, and those on the azimuthal asymmetry at HERA, have attracted much attention on the spin effects in high energy fragmentation processes. In this talk, we make a brief introduction to the different topics studied in this connection and a short summary of the available data. After that, we present a short summary of the main theoretical results that we obtained in studying these different topics. The talk was mainly based on the publications [5-9] which have been finished in collaboration with C.Boros, Liu Chun-xiu and Xu Qing-hua.

  1. [Comparative characteristics of chromatin endonuclease fragments].

    PubMed

    Miul'berg, A A; Tishchenko, L I; Domkina, L K

    1977-05-01

    Soluble fragments of chromatin obtained by Ca, Mg-dependent endonuclease digest of rat liver nuclei, have been separated by gel chromatography on Sepharose 4B into three zones, containing oligomers, tetramers--dimers and monomers, respectively. The content of nonhistone proteins and particularly lysine-rich histones is decreased with a transition from theoligomers to monomers. The average protein/DNA ratio of the monomers is equal to 1.36 and that of histone/DNA ratio--to 0.82. The dependence of the degree of chromatin digest by endonuclease on its protein content and conditions of isolation and incubation of nuclei is discussed. The chromatin monomer formed appears to be made up of a nucleosome and short portions of spacer DNA bound to some part of histone HI and nonhistone proteins. PMID:889964

  2. [The fragmentation of national health systems].

    PubMed

    Barillas, E

    1997-03-01

    The nationalistic tendencies observed in the world today, rooted in ethnic and ancestral cultural values that do not necessarily coincide with the physical boundaries of countries, have an enormous influence on societal organization, the distribution of wealth, and the processes of decentralization being carried out by governments. At the same time, the economic liberalization policies which are in fashion accentuate social divisions and favor models of health care that are fragmented according to the economic means of the user. This document explores the consequences of these trends for equity in the health and medical insurance systems of Latin America, as well as the role of the State and the private sector in the provision of services. PMID:9162594

  3. 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.

  4. Assortative mating and fragmentation within dog breeds

    PubMed Central

    2008-01-01

    Background There are around 400 internationally recognized dog breeds in the world today, with a remarkable diversity in size, shape, color and behavior. Breeds are considered to be uniform groups with similar physical characteristics, shaped by selection rooted in human preferences. This has led to a large genetic difference between breeds and a large extent of linkage disequilibrium within breeds. These characteristics are important for association mapping of candidate genes for diseases and therefore make dogs ideal models for gene mapping of human disorders. However, genetic uniformity within breeds may not always be the case. We studied patterns of genetic diversity within 164 poodles and compared it to 133 dogs from eight other breeds. Results Our analyses revealed strong population structure within poodles, with differences among some poodle groups as pronounced as those among other well-recognized breeds. Pedigree analysis going three generations back in time confirmed that subgroups within poodles result from assortative mating imposed by breed standards as well as breeder preferences. Matings have not taken place at random or within traditionally identified size classes in poodles. Instead, a novel set of five poodle groups was identified, defined by combinations of size and color, which is not officially recognized by the kennel clubs. Patterns of genetic diversity in other breeds suggest that assortative mating leading to fragmentation may be a common feature within many dog breeds. Conclusion The genetic structure observed in poodles is the result of local mating patterns, implying that breed fragmentation may be different in different countries. Such pronounced structuring within dog breeds can increase the power of association mapping studies, but also represents a serious problem if ignored. In dog breeding, individuals are selected on the basis of morphology, behaviour, working or show purposes, as well as geographic population structure. The same

  5. 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.

  6. 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

  7. Popping Balloons: A Case Study of Dynamical Fragmentation.

    PubMed

    Moulinet, Sébastien; Adda-Bedia, Mokhtar

    2015-10-30

    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. PMID:26565468

  8. 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.

  9. 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.

  10. 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. PMID:25567736

  11. HRMS studies on the fragmentation pathways of metallapentalyne

    NASA Astrophysics Data System (ADS)

    Lin, Zhiwei; Zhu, Congqing; Xia, Haiping

    2015-02-01

    The electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) using collision-induced dissociation (CID) method was applied to investigate the characteristic fragment ions of metalla-aromatic complexes for the first time. The fragmentation process of osmapentalyne, which contained metal-carbon triple bond in a five-membered ring, was discussed in detail. The ESI FT-ICR MS CID experimental results at high resolution mass spectra (HRMS) demonstrated the elemental composition of fragment ions unambiguously, thus a reasonable fragmentation pathway of osmapentalyne was proposed. In addition, the characteristic fragment ions have been investigated, which were specific and useful for the identification of some osmapentalynes complexes. These characteristic fragmentation pathways were helpful to analyze and interpret the stability and property of the parent ion. Also, this method could be used for the characterization of other organometallic complexes, especially containing characteristic isotopic peaks.

  12. Calculating shared fragments for the single digest problem

    SciTech Connect

    Soderlund, C. New Mexico State Univ., Las Cruces, NM . Dept. of Computer Science); Torney, D.; Burks, C. )

    1992-01-01

    A partial restriction map can be computed by using single digest fragments from a set of clones that are known to be in a contig. If there is no error or uncertainty in the data so that the set of unique restriction fragments can be calculated exactly, then the restriction map can be assembled using a polynomial-time algorithm based on the consecutive 1's property. However, there is typically both error and uncertainty in the data, which we WW describe in this paper. The data we are using is from the chromosome 16 mapping project at Los Alamos National Laboratory. We have developed an algorithm that consists of two steps: (1) calculate the set of unique restriction fragments and (2) assemble the fragments so that the set of fragments for each clone is contiguous. We present our algorithm for calculating the most probable set of unique fragments.

  13. Calculating shared fragments for the single digest problem

    SciTech Connect

    Soderlund, C. |; Torney, D.; Burks, C.

    1992-08-01

    A partial restriction map can be computed by using single digest fragments from a set of clones that are known to be in a contig. If there is no error or uncertainty in the data so that the set of unique restriction fragments can be calculated exactly, then the restriction map can be assembled using a polynomial-time algorithm based on the consecutive 1`s property. However, there is typically both error and uncertainty in the data, which we WW describe in this paper. The data we are using is from the chromosome 16 mapping project at Los Alamos National Laboratory. We have developed an algorithm that consists of two steps: (1) calculate the set of unique restriction fragments and (2) assemble the fragments so that the set of fragments for each clone is contiguous. We present our algorithm for calculating the most probable set of unique fragments.

  14. Combined analysis of charm-quark fragmentation-fraction measurements

    NASA Astrophysics Data System (ADS)

    Lisovyi, Mykhailo; Verbytskyi, Andrii; Zenaiev, Oleksandr

    2016-07-01

    A summary of measurements of the fragmentation of charm quarks into a specific hadron is given. Measurements performed in photoproduction and deep inelastic scattering in e± p, pp and e+e‒ collisions are compared, using up-to-date branching ratios. Within uncertainties, all measurements agree, supporting the hypothesis that fragmentation is independent of the specific production process. Averages of the fragmentation fractions over all measurements are presented. The average has significantly reduced uncertainties compared to individual measurements.

  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. 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.

  17. Release and characteristics of fungal fragments in various conditions.

    PubMed

    Mensah-Attipoe, Jacob; Saari, Sampo; Veijalainen, Anna-Maria; Pasanen, Pertti; Keskinen, Jorma; Leskinen, Jari T T; Reponen, Tiina

    2016-03-15

    Intact spores and submicrometer size fragments are released from moldy building materials during growth and sporulation. It is unclear whether all fragments originate from fungal growth or if small pieces of building materials are also aerosolized as a result of microbial decomposition. In addition, particles may be formed through nucleation from secondary metabolites of fungi, such as microbial volatile organic compounds (MVOCs). In this study, we used the elemental composition of particles to characterize the origin of submicrometer fragments released from materials contaminated by fungi. Particles from three fungal species (Aspergillus versicolor, Cladosporium cladosporioides and Penicillium brevicompactum), grown on agar, wood and gypsum board were aerosolized using the Fungal Spore Source Strength Tester (FSSST) at three air velocities (5, 16 and 27 m/s). Released spores (optical size, dp ≥ 0.8 μm) and fragments (dp ≤ 0.8 μm) were counted using direct-reading optical aerosol instruments. Particles were also collected on filters, and their morphology and elemental composition analyzed using scanning electron microscopes (SEMs) coupled with an Energy-Dispersive X-ray spectroscopy (EDX). Among the studied factors, air velocity resulted in the most consistent trends in the release of fungal particles. Total concentrations of both fragments and spores increased with an increase in air velocity for all species whereas fragment-spore (F/S) ratios decreased. EDX analysis showed common elements, such as C, O, Mg and Ca, for blank material samples and fungal growth. However, N and P were exclusive to the fungal growth, and therefore were used to differentiate biological fragments from non-biological ones. Our results indicated that majority of fragments contained N and P. Because we observed increased release of fragments with increased air velocities, nucleation of MVOCs was likely not a relevant process in the formation of fungal fragments. Based on elemental

  18. 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.

  19. Structural mechanisms of photoeffect in polyimide structures containing heterocyclic fragments

    SciTech Connect

    Aleksandrova, E. L.

    2006-11-15

    Trends in the variation in the quantum yields of charge-carrier photogeneration in polyimide structures containing heterocyclic fragments are studied. It is shown that the efficiency of sensitization of polyimides depends on the donor and acceptor properties of the fragments of monomeric units of the polyimide. It is established that the range of spectral sensitivity for heterocyclic fragments representing intramolecular complexes with charge transport is wider than that for heterocycles that do not represent such complexes.

  20. [Perception of short musical fragments by hypomaniac patients].

    PubMed

    Al'tman, Ia A; Gromyko, D I; Golubev, A A; Varfolomeev, A L

    2006-01-01

    Emotional assessment of short fragments from pieces of chamber music was studied in patients in steady elated mood (hypomaniac). Six fragments, assessed by healthy subjects as emotionally positive, neutral or negative were used. The examined subjects were shown to be capable for an emotional assessment of the musical fragments. The most pronounced difference of the examined patients from healthy subjects and depressive patients examined earlier was the predominance of neutral assessments in hypomaniacs. PMID:16869266

  1. Optical model methods of predicting nuclide production cross sections from heavy ion fragmentation

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Ramsey, C. R.; Tripathi, R. K.; Cucinotta, F. A.; Norbury, J. W.; Wilson, J. W. (Principal Investigator)

    1999-01-01

    Quantum mechanical optical potential methods for calculating inclusive isotope and element production cross sections from the fragmenting of heavy nuclei by intermediate- and high-energy protons and heavy ions are presented based upon a modified abrasion-ablation-FSI (frictional spectator interaction) collision model. The abrasion stage is treated as a quantum mechanical knockout process that leaves the residual prefragment in an excited state. Prefragment excitation energies are estimated using a combined liquid drop and FSI method. In ablation the prefragment deexcites by particle and photon emission to produce the final fragment. Contributions from electromagnetic dissociation to single nucleon removal cross sections are incorporated using a Weiszacker-Williams theory that includes electric dipole and electric quadrupole interactions. Estimates of elemental and isotopic production cross sections are in good agreement with published cross section measurements for a variety of projectile-target-beam energy combinations.

  2. SCEDS: protein fragments for molecular replacement in Phaser

    PubMed Central

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

    2013-01-01

    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 Cα 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. PMID:24189233

  3. [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. PMID:23853355

  4. Habitat fragmentation and its lasting impact on Earth's ecosystems.

    PubMed

    Haddad, Nick M; Brudvig, Lars A; Clobert, Jean; Davies, Kendi F; Gonzalez, Andrew; Holt, Robert D; Lovejoy, Thomas E; Sexton, Joseph O; Austin, Mike P; Collins, Cathy D; Cook, William M; Damschen, Ellen I; Ewers, Robert M; Foster, Bryan L; Jenkins, Clinton N; King, Andrew J; Laurance, William F; Levey, Douglas J; Margules, Chris R; Melbourne, Brett A; Nicholls, A O; Orrock, John L; Song, Dan-Xia; Townshend, John R

    2015-03-01

    We conducted an analysis of global forest cover to reveal that 70% of remaining forest is within 1 km of the forest's edge, subject to the degrading effects of fragmentation. A synthesis of fragmentation experiments spanning multiple biomes and scales, five continents, and 35 years demonstrates that habitat fragmentation reduces biodiversity by 13 to 75% and impairs key ecosystem functions by decreasing biomass and altering nutrient cycles. Effects are greatest in the smallest and most isolated fragments, and they magnify with the passage of time. These findings indicate an urgent need for conservation and restoration measures to improve landscape connectivity, which will reduce extinction rates and help maintain ecosystem services. PMID:26601154

  5. {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.

  6. 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. PMID:23954434

  7. Mass Spectrometric and Computational Investigation of the Protonated Carnosine-Carboplatin Complex Fragmentation.

    PubMed

    Ritacco, Ida; Sicilia, Emilia; Shoeib, Tamer; Korany, Mohamed; Russo, Nino

    2015-08-17

    Platinum(II)-based anticancer drugs are square-planar d(8) complexes that, activated by hydrolysis, cause cancer cell death by binding to nuclear DNA and distorting its structure. For that reason, interactions of platinum anticancer drugs with DNA have been extensively investigated, aiming at disentangling the mechanism of action and toxicity. Less attention, however, has been devoted to the formation of adducts between platinum drugs with biological ligands other than DNA. These adducts can cause the loss and deactivation of the drug before it arrives at the ultimate target and are also thought to contribute to the drug's toxicity. Here are reported the outcomes of electrospray ionization mass spectrometry experiments and density functional theory (DFT) computations carried out to investigate the fragmentation pathways of the protonated carnosine-carboplatin complex, [Carnosine + CarbPt + H](+). DFT calculations at the B3LYP/LANL2DZ level employed to probe fragmentation mechanisms account for all experimental data. Because of the relative rigidity of the structure of the most stable 1A conformer, stabilized by three strong hydrogen bonds, the first step of all of the examined fragmentation pathways is the interconversion of the 1A conformer into the less stable structure 1B. Formation of the [Carnosine + H](+) fragment from the precursor ion, [Carnosine + CarbPt + H](+), is calculated to be the lowest-energy process. At slightly higher energies, the loss of two amino groups is observed to produce the [Carnosine + (CarbPt - NH3) + H](+) and [Carnosine + (CarbPt - 2NH3) + H](+) ions. At significantly higher energies, the loss of CO2 occurs, yielding the final [Carnosine + (CarbPt - NH3) - CO2 + H](+) and [Carnosine + (CarbPt - 2NH3) - CO2 + H](+) products. Formation of the [CarbPt + H](+) fragment from [Carnosine + CarbPt + H](+), even if not hampered by a high activation barrier, is calculated to be very unfavorable from a thermodynamic point of view. PMID:26238420

  8. 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

  9. 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.

  10. 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)

  11. The Case for the Median Fragment Size as a Better Fragment Size Descriptor than the Mean

    NASA Astrophysics Data System (ADS)

    Ouchterlony, Finn

    2016-01-01

    Cunningham's use of x 50, the median fragment size, instead of the mean < x > in the main prediction equation of the Kuz-Ram model has several times been pointed out as a mistake. This paper analyses if this mistake is important using dimensional analysis and by reanalyzing the historical Soviet data behind Kuznetsov's original equation for the mean. The main findings in this paper are that: (1) Cunningham's mistake has no proven effect in practice and would only be relevant as long as he used Kuznetsov's equation for the rock factor A, i.e. till 1987. (2) Kuznetsov's equation has its roots in the characteristic size of the Rosin-Rammler (RR) functions fit to the sieving data as a way to determine the mean, not only in the mean itself. (3) The key data set behind Kuznetsov's equation just as easily provides a prediction equation for x 50 with the same goodness of fit as the equation for the mean. (4) Use of x 50 instead of the mean < x > in a dimensional analysis of fragmentation leads to considerable mathematical simplifications because the normalized mass passing at x 50 is a constant number. Non-dimensional ratios like x 50/ x max based on two percentile sizes also lead to such simplifications. The median x 50 as a fragment size descriptor thus has a sounder theoretical background than the mean < x >. It is normally less prone to measurement errors and it is not rejected by the original Soviet data. Thus, Cunningham's mistake has led the rock fragmentation community in the right direction.

  12. 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.

  13. Quantum mechanical fragment methods based on partitioning atoms or partitioning coordinates.

    PubMed

    Wang, Bo; Yang, Ke R; Xu, Xuefei; Isegawa, Miho; Leverentz, Hannah R; Truhlar, Donald G

    2014-09-16

    atoms for capping dangling bonds, and we have shown that they can greatly improve the accuracy. Finally we present a new approach that goes beyond QM/MM by combining the convenience of molecular mechanics with the accuracy of fitting a potential function to electronic structure calculations on a specific system. To make the latter practical for systems with a large number of degrees of freedom, we developed a method to interpolate between local internal-coordinate fits to the potential energy. A key issue for the application to large systems is that rather than assigning the atoms or monomers to fragments, we assign the internal coordinates to reaction, secondary, and tertiary sets. Thus, we make a partition in coordinate space rather than atom space. Fits to the local dependence of the potential energy on tertiary coordinates are arrayed along a preselected reaction coordinate at a sequence of geometries called anchor points; the potential energy function is called an anchor points reactive potential. Electrostatically embedded fragment methods and the anchor points reactive potential, because they are based on treating an entire system by quantum mechanical electronic structure methods but are affordable for large and complex systems, have the potential to open new areas for accurate simulations where combined QM/MM methods are inadequate. PMID:24841937

  14. Hollow fission fragment tracks in fluorapatite

    NASA Astrophysics Data System (ADS)

    Li, Weixing

    Spontaneous fission of uranium in minerals creates a damaged "track" along the trajectory of the fission fragments. Fission tracks in fluorapatite, enlarged by chemical etching, are widely used in geologic age-dating and the reconstruction of the thermal history of Earth's crust. However, despite this wide spread application, there have been no systematic studies of the internal structure of unetched fission tracks or the atomic-scale process of track annealing. In this research, fission tracks in fluorapatite are demonstrated to be nano-channels instead of amorphous cores as had been assumed. The formation of hollow tracks is ascribed to the highly ionizing energy deposition of fission fragments inducing radiolytic decomposition of fluorapatite accompanied by the loss of volatile elements. The mechanism for thermal annealing of hollow tracks in fluorapatite is shown to be entirely different from that of amorphous tracks in zircon. The discontinuity of fission tracks, in addition to the shrinkage, prevents chemicals from entering into the hollow tracks for further etching, and then significantly reduces the etched length. The shrinkage of hollow fission tracks results from thermo-emission of vacancies or gaseous species from the cavities to surrounding solids instead of atomic-scale recovery of the amorphous core. The high diffusivity of atoms on the surface of hollow tracks causes the discontinuity of tracks either by Rayleigh instability, by Brownian motion, or by preferential motion of track segments. The preferential motion of atoms along c-axis causes more rapid annealing of fission tracks perpendicular to the c-axis. Under the electron beam, the hollow tracks segment into droplets and the track segments randomly move at room temperature or preferentially move along c-axis at high temperatures. The radiolytic annealing results from beam-enhanced diffusion, which is similar to thermally enhanced diffusion. The similarity in the morphology of fission tracks and

  15. FRAGMENTATION OF URINARY CALCULI IN VITRO BY BURST WAVE LITHOTRIPSY

    PubMed Central

    Maxwell, Adam D.; Cunitz, Bryan W.; Kreider, Wayne; Sapozhnikov, Oleg A.; Hsi, Ryan S.; Harper, Jonathan D.; Bailey, Michael R.; Sorensen, Mathew D.

    2015-01-01

    Purpose We have developed a new method of lithotripsy that uses short, broadly focused bursts of ultrasound rather than shock waves to fragment stones. This study investigated the characteristics of stone comminution by burst wave lithotripsy in vitro. Materials and Methods Artificial and natural stones (mean 8.2±3.0 mm, range 5–15 mm) were treated with ultrasound bursts using a focused transducer in a water bath. Stones were exposed to bursts with focal pressure amplitude ≤6.5 MPa at 200 Hz burst repetition rate until completely fragmented. Ultrasound frequencies of 170 kHz, 285 kHz, and 800 kHz were applied using 3 different transducers. The time to achieve fragmentation for each stone type was recorded, and fragment size distribution was measured by sieving. Results Stones exposed to ultrasound bursts were fragmented at focal pressure amplitudes ≥2.8 MPa at 170 kHz. Fractures appeared along the stone surface, resulting in fragments separating at the surface nearest to the transducer until the stone was disintegrated. All natural and artificial stones were fragmented at the highest focal pressure of 6.5 MPa with treatment durations between a mean of 36 seconds for uric acid to 14.7 minutes for cystine stones. At a frequency of 170 kHz, the largest artificial stone fragments were <4 mm. Exposures at 285 kHz produced only fragments <2 mm, and 800 kHz produced only fragments <1 mm. Conclusions Stone comminution with burst wave lithotripsy is feasible as a potential noninvasive treatment method for nephrolithiasis. Adjusting the fundamental ultrasound frequency allows control of stone fragment size. PMID:25111910

  16. Fragmentation of Lewis-type trisaccharides in the gas phase

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroaki; Yamagaki, Tohru; Tachibana, Kazuo; Fukui, Kazuhiko

    2008-11-01

    The mechanisms of fragmentation of the chlorinated Lewis-type trisaccharides Lewis a and Lewis X were studied by using experimental and theoretical methods. In the fragment ion spectra obtained by ESI-CID-MS, C- and Z-type fragmentations corresponding to 4- and 3-linked glycosyl bond cleavages of the N-acetylglucosamine moiety were observed. The relationships of the relative ion intensities of C- and Z-type fragmentations were Z > C in Lewis a and C > Z in Lewis X, suggesting that the relationships of the activation energies were C > Z in Lewis a and Z > C in Lewis X. Anomeric and acetoamide groups were assumed to be included in the mechanisms of C- and Z-type fragmentation; we therefore analyzed 3-fucosyllactose and methylated Lewis-type trisaccharides, which are the derivatives of Lewis-type trisaccharides. These analyses revealed that C-type fragmentation was little influenced by anomeric group and that Z-type fragmentation was influenced by both the anomeric and the acetoamide groups. Fragmentation mechanisms were proposed on the basis of the experimental results and were calculated at the HF/3-21G(d), HF/6-31G(d) levels. From the calculations, C-type fragmentation of the 4-linkage was considered to take place by electron transfer from the acetoamide group, and Z-type fragmentation at the 3-linkage was considered to take place in two steps: (i) elimination of the 3-linked saccharide moiety, and (ii) deprotonation of an anomeric proton by a chloride anion. The activation energies for C- and Z-type fragmentations, as determined by HF calculations, were consistent with the experimentally assumed trends.

  17. 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

  18. FragViz: visualization of fragmented networks

    PubMed Central

    2010-01-01

    Background Researchers in systems biology use network visualization to summarize the results of their analysis. Such networks often include unconnected components, which popular network alignment algorithms place arbitrarily with respect to the rest of the network. This can lead to misinterpretations due to the proximity of otherwise unrelated elements. Results We propose a new network layout optimization technique called FragViz which can incorporate additional information on relations between unconnected network components. It uses a two-step approach by first arranging the nodes within each of the components and then placing the components so that their proximity in the network corresponds to their relatedness. In the experimental study with the leukemia gene networks we demonstrate that FragViz can obtain network layouts which are more interpretable and hold additional information that could not be exposed using classical network layout optimization algorithms. Conclusions Network visualization relies on computational techniques for proper placement of objects under consideration. These algorithms need to be fast so that they can be incorporated in responsive interfaces required by the explorative data analysis environments. Our layout optimization technique FragViz meets these requirements and specifically addresses the visualization of fragmented networks, for which standard algorithms do not consider similarities between unconnected components. The experiments confirmed the claims on speed and accuracy of the proposed solution. PMID:20860802

  19. 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.

  20. 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.

  1. 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) and tokens (all…

  2. Gas-Phase Fragmentation Analysis of Nitro-Fatty Acids

    NASA Astrophysics Data System (ADS)

    Bonacci, Gustavo; Asciutto, Eliana K.; Woodcock, Steven R.; Salvatore, Sonia R.; Freeman, Bruce A.; Schopfer, Francisco J.

    2011-09-01

    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 NO{2/-} 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 NO{2/-} 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.

  3. 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.

  4. Experimental modelling of fragmentation applied to volcanic explosions

    NASA Astrophysics Data System (ADS)

    Haug, Øystein Thordén; Galland, Olivier; Gisler, Galen R.

    2013-12-01

    Explosions during volcanic eruptions cause fragmentation of magma and host rock, resulting in fragments with sizes ranging from boulders to fine ash. The products can be described by fragment size distributions (FSD), which commonly follow power laws with exponent D. The processes that lead to power-law distributions and the physical parameters that control D remain unknown. We developed a quantitative experimental procedure to study the physics of the fragmentation process through time. The apparatus consists of a Hele-Shaw cell containing a layer of cohesive silica flour that is fragmented by a rapid injection of pressurized air. The evolving fragmentation of the flour is monitored with a high-speed camera, and the images are analysed to obtain the evolution of the number of fragments (N), their average size (A), and the FSD. Using the results from our image-analysis procedure, we find transient empirical laws for N, A and the exponent D of the power-law FSD as functions of the initial air pressure. We show that our experimental procedure is a promising tool for unravelling the complex physics of fragmentation during phreatomagmatic and phreatic eruptions.

  5. 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. PMID:27043011

  6. Stenocybe fragmenta, a new species of Mycocaliciaceae with fragmenting spores

    USGS Publications Warehouse

    Peterson, E.B.; Rikkinen, Jouko

    1998-01-01

    The new species Stenocybe fragmenta (Ascomycota, Mycocaliciaceae) is described from western North America. The species was collected from twigs of Cercocarpus montanus and Rhamnus purshiana. Stenocybe fragmenta is characterized by 5-7 septate, 18-30 I?m long ascospores that fragment at maturity. This is the first report of spore fragmentation among the Mycocaliciaceae.

  7. 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.

  8. 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.

  9. Ground and satellite observations of auroral fragmentation into patches

    NASA Astrophysics Data System (ADS)

    Shiokawa, Kazuo; Nishi, Katsuki

    2016-07-01

    We review characteristic auroral fragmentation which is the process by which uniform aurora is broken into several fragments to form auroral patches, based on the all-sky camera observations at Tromsoe, Norway and THEMIS chain in Canada. The auroral fragmentation occurs as finger-like structures developing predominantly in meridional direction with speeds of several tens m/s and scale sizes of several tens kilometers without any shearing motion. These features suggest that pressure-driven instability in the balance between the earthward magnetic-tension force and the tailward pressure gradient force in the magnetosphere is the main driving force of the auroral fragmentation. Thus, these observations indicate that auroral fragmentation associated with pressure-driven instability is a process that creates auroral patches. Auroral fragmentation is seen from midnight to dawn local time and usually appears at the beginning of the substorm recovery phase, near the low latitude boundary of the auroral region. One example of plasma and magnetic field observations by the THEMIS satellite in the conjugate magnetosphere shows diamagnetic anti-phase variations of magnetic and plasma pressures with time scales of several to tens minutes associated with the auroral fragmentation. This observation also supports the idea of pressure-driven instability to cause the auroral fragmentation into patches.

  10. 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.

  11. 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.

  12. Gelation and mass conservation in coagulation-fragmentation models

    NASA Astrophysics Data System (ADS)

    Escobedo, M.; Laurençot, Ph.; Mischler, S.; Perthame, B.

    The occurrence of gelation and the existence of mass-conserving solutions to the continuous coagulation-fragmentation equation are investigated under various assumptions on the coagulation and fragmentation rates, thereby completing the already known results. A non-uniqueness result is also established and a connection to the modified coagulation model of Flory is made.

  13. TEMPORAL CHANGE IN FRAGMENTATION OF CONTINENTAL US FORESTS

    EPA Science Inventory

    Changes in forest ecosystem function and condition arise from changes in forest fragmentation. Previous studies estimated forest fragmentation for the continental United States (US). In this study, new temporal land-cover data from the National Land Cover Database (NLCD) were us...

  14. ACFIS: a web server for fragment-based drug discovery

    PubMed Central

    Hao, Ge-Fei; Jiang, Wen; Ye, Yuan-Nong; Wu, Feng-Xu; Zhu, Xiao-Lei; Guo, Feng-Biao; Yang, Guang-Fu

    2016-01-01

    In order to foster innovation and improve the effectiveness of drug discovery, there is a considerable interest in exploring unknown ‘chemical space’ to identify new bioactive compounds with novel and diverse scaffolds. Hence, fragment-based drug discovery (FBDD) was developed rapidly due to its advanced expansive search for ‘chemical space’, which can lead to a higher hit rate and ligand efficiency (LE). However, computational screening of fragments is always hampered by the promiscuous binding model. In this study, we developed a new web server Auto Core Fragment in silico Screening (ACFIS). It includes three computational modules, PARA_GEN, CORE_GEN and CAND_GEN. ACFIS can generate core fragment structure from the active molecule using fragment deconstruction analysis and perform in silico screening by growing fragments to the junction of core fragment structure. An integrated energy calculation rapidly identifies which fragments fit the binding site of a protein. We constructed a simple interface to enable users to view top-ranking molecules in 2D and the binding mode in 3D for further experimental exploration. This makes the ACFIS a highly valuable tool for drug discovery. The ACFIS web server is free and open to all users at http://chemyang.ccnu.edu.cn/ccb/server/ACFIS/. PMID:27150808

  15. ACFIS: a web server for fragment-based drug discovery.

    PubMed

    Hao, Ge-Fei; Jiang, Wen; Ye, Yuan-Nong; Wu, Feng-Xu; Zhu, Xiao-Lei; Guo, Feng-Biao; Yang, Guang-Fu

    2016-07-01

    In order to foster innovation and improve the effectiveness of drug discovery, there is a considerable interest in exploring unknown 'chemical space' to identify new bioactive compounds with novel and diverse scaffolds. Hence, fragment-based drug discovery (FBDD) was developed rapidly due to its advanced expansive search for 'chemical space', which can lead to a higher hit rate and ligand efficiency (LE). However, computational screening of fragments is always hampered by the promiscuous binding model. In this study, we developed a new web server Auto Core Fragment in silico Screening (ACFIS). It includes three computational modules, PARA_GEN, CORE_GEN and CAND_GEN. ACFIS can generate core fragment structure from the active molecule using fragment deconstruction analysis and perform in silico screening by growing fragments to the junction of core fragment structure. An integrated energy calculation rapidly identifies which fragments fit the binding site of a protein. We constructed a simple interface to enable users to view top-ranking molecules in 2D and the binding mode in 3D for further experimental exploration. This makes the ACFIS a highly valuable tool for drug discovery. The ACFIS web server is free and open to all users at http://chemyang.ccnu.edu.cn/ccb/server/ACFIS/. PMID:27150808

  16. 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.

  17. Characterizing forest fragments in boreal, temperate, and tropical ecosystems.

    PubMed

    Meddens, Arjan J H; Hudak, Andrew T; Evans, Jeffrey S; Gould, William A; González, Grizelle

    2008-12-01

    An increased ability to analyze landscapes in a spatial manner through the use of remote sensing leads to improved capabilities for quantifying human-induced forest fragmentation. Developments of spatially explicit methods in landscape analyses are emerging. In this paper, the image delineation software program eCognition and the spatial pattern analysis program FRAGSTATS were used to quantify patterns of forest fragments on six landscapes across three different climatic regions characterized by different moisture regimes and different influences of human pressure. Our results support the idea that landscapes with higher road and population density are more fragmented; however, there are other, equally influential factors contributing to fragmentation, such as moisture regime, historic land use, and fire dynamics. Our method provided an objective means to characterize landscapes and assess patterns of forest fragments across different forested ecosystems by addressing the limitations of pixel-based classification and incorporating image objects. PMID:19205180

  18. Fragment-based design of kinase inhibitors: a practical guide.

    PubMed

    Erickson, Jon A

    2015-01-01

    Fragment-based drug design has become an important strategy for drug design and development over the last decade. It has been used with particular success in the development of kinase inhibitors, which are one of the most widely explored classes of drug targets today. The application of fragment-based methods to discovering and optimizing kinase inhibitors can be a complicated and daunting task; however, a general process has emerged that has been highly fruitful. Here a practical outline of the fragment process used in kinase inhibitor design and development is laid out with specific examples. A guide to the overall process from initial discovery through fragment screening, including the difficulties in detection, to the computational methods available for use in optimization of the discovered fragments is reported. PMID:25709040

  19. A sampling approach for protein backbone fragment conformations.

    PubMed

    Yu, J Y; Zhang, W

    2013-01-01

    In protein structure prediction, backbone fragment bias information can narrow down the conformational space of the whole polypeptide chain significantly. Unlike existing methods that use fragments as building blocks, the paper presents a probabilistic sampling approach for protein backbone torsion angles by modelling angular correlation of (phi, psi) with a directional statistics distribution. Given a protein sequence and secondary structure information, this method samples backbone fragments conformations by using a backtrack sampling algorithm for the hidden Markov model with multiple inputs and a single output. The proposed approach is applied to a fragment library, and some well-known structural motifs are sampled very well on the optimal path. Computational results show that the method can help to obtain native-like backbone fragments conformations. PMID:23777175

  20. Characterization of the scission point from fission-fragment velocities

    NASA Astrophysics Data System (ADS)

    Caamaño, M.; Farget, F.; Delaune, O.; Schmidt, K.-H.; Schmitt, C.; Audouin, L.; Bacri, C.-O.; Benlliure, J.; Casarejos, E.; Derkx, X.; Fernández-Domínguez, B.; Gaudefroy, L.; Golabek, C.; Jurado, B.; Lemasson, A.; Ramos, D.; Rodríguez-Tajes, C.; Roger, T.; Shrivastava, A.

    2015-09-01

    The isotopic yield distributions and kinematic properties of fragments produced in the transfer-induced fission of 240Pu and fusion-induced fission of 250Cf, with 9 MeV and 45 MeV excitation energy, respectively, were measured in inverse kinematics with the spectrometer VAMOS. The kinematics of identified fission fragments allow to derive properties of the scission configuration such as the distance between fragments, the total kinetic energy, the neutron multiplicity, the total excitation energy, and, for the first time, the proton- and neutron-number sharing during the emergence of the fragments. These properties of the scission point are studied as functions of the fragment atomic number. The correlation between these observables, gathered in one single experiment and for two different fissioning systems at different excitation energies, give valuable information for the understanding and modeling of the fission process.

  1. 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.

  2. Nuclear fragmentation measurements for hadrontherapy and space radiation protection

    SciTech Connect

    De Napoli, M.; Agodi, C.; Blancato, A. A.; Cavallaro, M.; Cirrone, G. A. P.; Cuttone, G.; Sardina, D.; Scuderi, V.; Battistoni, G.; Bondi, M.; Cappuzzello, F.; Carbone, D.; Nicolosi, D.; Raciti, G.; Tropea, S.; Giacoppo, F.; Morone, M. C.; Pandola, L.; Rapisarda, E.; Romano, F.; and others

    2013-04-19

    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 {sup 12}C 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.

  3. Novel Definition and Algorithm for Chaining Fragments with Proportional Overlaps

    NASA Astrophysics Data System (ADS)

    Uricaru, Raluca; Mancheron, Alban; Rivals, Eric

    Chaining fragments is a crucial step in genome alignment. Existing chaining algorithms compute a maximum weighted chain with no overlaps allowed between adjacent fragments. In practice, using local alignments as fragments, instead of MEMs, generates frequent overlaps between fragments, due to combinatorial reasons and biological factors, i.e. variable tandem repeat structures that differ in number of copies between genomic sequences. In this paper, in order to raise this limitation, we formulate a novel definition of a chain, allowing overlaps proportional to the fragments lengths, and exhibit an efficient algorithm for computing such a maximum weighted chain. We tested our algorithm on a dataset composed of 694 genome couples and accounted for significant improvements in terms of coverage, while keeping the running times below reasonable limits.

  4. Recombinant Kinase Production and Fragment Screening by NMR Spectroscopy.

    PubMed

    Han, Byeonggu; Ahn, Hee-Chul

    2016-01-01

    During the past decade fragment-based drug discovery (FBDD) has rapidly evolved and several drugs or drug candidates developed by FBDD approach are clinically in use or in clinical trials. For example, vemurafenib, a V600E mutated BRAF inhibitor, was developed by utilizing FBDD approach and approved by FDA in 2011. In FBDD, screening of fragments is the starting step for identification of hits and lead generation. Fragment screening usually relies on biophysical techniques by which the protein-bound small molecules can be detected. NMR spectroscopy has been extensively used to study the molecular interaction between the protein and the ligand, and has many advantages in fragment screening over other biophysical techniques. This chapter describes the practical aspects of fragment screening by saturation transfer difference NMR. PMID:26501900

  5. Transcriptome Analysis Reveals Signature of Adaptation to Landscape Fragmentation

    PubMed Central

    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. PMID:24988207

  6. 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. PMID:24988207

  7. Observations of Titan 3C-4 Transtage Fragmentation Debris

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    The fragmentation of a Titan 3C-4 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 US 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 will present a size distribution for all calibrated magnitude data acquired on MODEST. Size distribution plots will also be shown using historical models for small fragmentation debris (down to 10 cm) believed to be associated with the Titan 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, 33510) and the parent rocket body. Color index data will be 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 2012, the SSN added 16 additional fragments to the catalogue. MODEST acquired magnitude data on ten Titan fragments in late 2012 and early 2013. The magnitude distribution of all the observed fragments are analyzed as a function of time. In order to better characterize the breakup fragments spectral measurements were acquired on the original rocket body and five Titan fragments using the 6.5-m Magellan telescopes at Las Campanas Observatory in Chile. The telescopic spectra are compared with laboratory acquired spectra of materials (e.g., Aluminum and various paints) and categorized based on known absorption features for spacecraft materials.

  8. 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.

  9. Effects of target fragmentation on evaluation of LET spectra from space radiations: implications for space radiation protection studies

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Wilson, J. W.; Shinn, J. L.; Badavi, F. F.; Badhwar, G. D.

    1996-01-01

    We present calculations of linear energy transfer (LET) spectra in low earth orbit from galactic cosmic rays and trapped protons using the HZETRN/BRYNTRN computer code. The emphasis of our calculations is on the analysis of the effects of secondary nuclei produced through target fragmentation in the spacecraft shield or detectors. Recent improvements in the HZETRN/BRYNTRN radiation transport computer code are described. Calculations show that at large values of LET (> 100 keV/micrometer) the LET spectra seen in free space and low earth orbit (LEO) are dominated by target fragments and not the primary nuclei. Although the evaluation of microdosimetric spectra is not considered here, calculations of LET spectra support that the large lineal energy (y) events are dominated by the target fragments. Finally, we discuss the situation for interplanetary exposures to galactic cosmic rays and show that current radiation transport codes predict that in the region of high LET values the LET spectra at significant shield depths (> 10 g/cm2 of Al) is greatly modified by target fragments. These results suggest that studies of track structure and biological response of space radiation should place emphasis on short tracks of medium charge fragments produced in the human body by high energy protons and neutrons.

  10. 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.

  11. Colon centerline extraction in fragmented segmentations.

    PubMed

    Krishnan, Karthik; Madrosiya, Akshay; Desai, Nasir

    2015-08-01

    In virtual colonoscopy, the clinical need is a smooth centered path from the rectum to the cecum, for interactive navigation along the colonic lumen. The primary challenge is breakages in the colon, due to fecal residue, abnormalities, poor insufflation and inadequate electronic cleansing. Here we propose a method, that is a modification of the classic energy minimized geodesic, that extracts centered paths through fragmented colons. To begin, we perform electronic cleansing, automatically localize 4 points: rectum, cecum, sphlenic and hepatic flexures; followed by region growing and heuristic approaches to generate the initial segmentation. This is followed by a daisy chaining procedure to link possibly large colon blobs that may have been missed as weaker candidate segmentations. We then perform a front propagation to extract a minimal energy path through the ordered set of points. This propagation is guided by multiple forces: (a) A strong force given by the distance to the colon segmentation surface (b) A weak force derived from the CT intensity (c) A weak force from the distance to the surface of weaker candidate colon segmentations (d) A geodesic repulsive force, where the other points exhibit an repelling force in their voronoi partition, the force proportional to the geodesic distance to the point. Our contribution is a path extraction method for the colon that is the energy minimized geodesic (a) favouring centeredness (b) punching through gaps, traversing in so far as possible through lower intensity regions and possibly centered within these gaps (c) ordered through the feature points. Results show improvements of the method over the standard minimal energy path approach. PMID:26736927

  12. Comparing Binding Modes of Analogous Fragments Using NMR in Fragment-Based Drug Design: Application to PRDX5

    PubMed Central

    Guichou, Jean-François; Cala, Olivier; Krimm, Isabelle

    2014-01-01

    Fragment-based drug design is one of the most promising approaches for discovering novel and potent inhibitors against therapeutic targets. The first step of the process consists of identifying fragments that bind the protein target. The determination of the fragment binding mode plays a major role in the selection of the fragment hits that will be processed into drug-like compounds. Comparing the binding modes of analogous fragments is a critical task, not only to identify specific interactions between the protein target and the fragment, but also to verify whether the binding mode is conserved or differs according to the fragment modification. While X-ray crystallography is the technique of choice, NMR methods are helpful when this fails. We show here how the ligand-observed saturation transfer difference (STD) experiment and the protein-observed 15N-HSQC experiment, two popular NMR screening experiments, can be used to compare the binding modes of analogous fragments. We discuss the application and limitations of these approaches based on STD-epitope mapping, chemical shift perturbation (CSP) calculation and comparative CSP sign analysis, using the human peroxiredoxin 5 as a protein model. PMID:25025339

  13. 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. PMID:25230471

  14. Liquid droplet coalescence and fragmentation at the aqueous-air surface.

    PubMed

    Paneru, Govind; Law, Bruce M; Ibi, Koki; Ushijima, Baku; Flanders, Bret N; Aratono, Makoto; Matsubara, Hiroki

    2015-01-13

    For hexadecane oil droplets at an aqueous-air surface, the surface film in coexistence with the droplets exhibits two-dimensional gaseous (G), liquid (L), or solid (S) behavior depending upon the temperature and concentration of the cationic surfactant dodecyltrimethylammonium bromide. In the G (L) phase, oil droplets are observed to coalesce (fragment) as a function of time. In the coalescence region, droplets coalesce on all length scales, and the final state is a single oil droplet at the aqueous-air surface. The fragmentation regime is complex. Large oil droplets spread as oil films; hole nucleation breaks up this film into much smaller fluctuating and fragmenting or metastable droplets. Metastable droplets are small contact angle spherical caps and do not fluctuate in time; however, they are unstable over long time periods and eventually sink into the bulk water phase. Buoyancy forces provide a counterbalancing force where the net result is that small oil droplets (radius r < 80 μm) are mostly submerged in the bulk aqueous medium with only a small fraction protruding above the liquid surface. In the G phase, a mechanical stability theory for droplets at liquid surfaces indicates that droplet coalesce is primarily driven by surface tension effects. This theory, which only considers spherical cap shaped surface droplets, qualitatively suggests that in the L phase the sinking of metastable surface droplets into the bulk aqueous medium is driven by a negative line tension and a very small spreading coefficient. PMID:25477297

  15. Extraction of quark transversity distribution and Collins fragmentation functions with QCD evolution

    DOE PAGESBeta

    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 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

  16. On the relationship between microbubble fragmentation, deflation, and broadband superharmonic signal production

    PubMed Central

    Lindsey, Brooks D.; Rojas, Juan D.; Dayton, Paul A.

    2016-01-01

    Acoustic angiography imaging of microbubble contrast agents utilizes the superharmonic energy produced from excited microbubbles, and enables high-contrast, high-resolution imaging. However, the exact mechanism by which broadband harmonic energy is produced is not fully understood. In order to elucidate the role of microbubble shell fragmentation in superharmonic signal production, simultaneous optical and acoustic measurements were performed on individual microbubbles at transmit frequencies from 1.75 to 3.75 MHz and pressures near the shell fragmentation threshold for microbubbles of varying diameter. High-amplitude, broadband superharmonic signals were produced with shell fragmentation, while weaker signals (approximately 25% of peak amplitude) were observed in the presence of shrinking bubbles. Furthermore, when imaging populations of stationary microbubbles with a dual-frequency ultrasound imaging system, a sharper decline in image intensity with respect to frame number was observed for 1 μm bubbles than for 4 μm bubbles. Finally, in a study of two rodents, increasing frame rate from 4 to 7 Hz resulted in a decrease in mean steady-state image intensity of 27% at 1000 kPa and 29% at 1300 kPa. While the existence of superharmonic signals when bubbles shrink has the potential to prolong the imaging efficacy of microbubbles, parameters such as frame rate and peak pressure must be balanced with expected re-perfusion rate in order to maintain adequate contrast during in vivo imaging. PMID:25766572

  17. Reconstruction of protein backbones from the BriX collection of canonical protein fragments.

    PubMed

    Baeten, Lies; Reumers, Joke; Tur, Vicente; Stricher, François; Lenaerts, Tom; Serrano, Luis; Rousseau, Frederic; Schymkowitz, Joost

    2008-05-01

    As modeling of changes in backbone conformation still lacks a computationally efficient solution, we developed a discretisation of the conformational states accessible to the protein backbone similar to the successful rotamer approach in side chains. The BriX fragment database, consisting of fragments from 4 to 14 residues long, was realized through identification of recurrent backbone fragments from a non-redundant set of high-resolution protein structures. BriX contains an alphabet of more than 1,000 frequently observed conformations per peptide length for 6 different variation levels. Analysis of the performance of BriX revealed an average structural coverage of protein structures of more than 99% within a root mean square distance (RMSD) of 1 Angstrom. Globally, we are able to reconstruct protein structures with an average accuracy of 0.48 Angstrom RMSD. As expected, regular structures are well covered, but, interestingly, many loop regions that appear irregular at first glance are also found to form a recurrent structural motif, albeit with lower frequency of occurrence than regular secondary structures. Larger loop regions could be completely reconstructed from smaller recurrent elements, between 4 and 8 residues long. Finally, we observed that a significant amount of short sequences tend to display strong structural ambiguity between alpha helix and extended conformations. When the sequence length increases, this so-called sequence plasticity is no longer observed, illustrating the context dependency of polypeptide structures. PMID:18483555

  18. Fragmentation transition in a coevolving network with link-state dynamics.

    PubMed

    Carro, A; Vazquez, F; Toral, R; San Miguel, M

    2014-06-01

    We study a network model that couples the dynamics of link states with the evolution of the network topology. The state of each link, either A or B, is updated according to the majority rule or zero-temperature Glauber dynamics, in which links adopt the state of the majority of their neighboring links in the network. Additionally, a link that is in a local minority is rewired to a randomly chosen node. While large systems evolving under the majority rule alone always fall into disordered topological traps composed by frustrated links, any amount of rewiring is able to drive the network to complete order, by relinking frustrated links and so releasing the system from traps. However, depending on the relative rate of the majority rule and the rewiring processes, the system evolves towards different ordered absorbing configurations: either a one-component network with all links in the same state or a network fragmented in two components with opposite states. For low rewiring rates and finite-size networks there is a domain of bistability between fragmented and nonfragmented final states. Finite-size scaling indicates that fragmentation is the only possible scenario for large systems and any nonzero rate of rewiring. PMID:25019828

  19. Consistency check of charged hadron multiplicities and fragmentation functions in SIDIS

    NASA Astrophysics Data System (ADS)

    Yang, Dong-Jing; Jiang, Fu-Jiun; Chang, Wen-Chen; Kao, Chung-Wen; Nam, Seung-il

    2016-04-01

    We derived the conditions on certain combinations of integrals of the fragmentation functions of pion using HERMES data for the sum of the charged pion multiplicities from semi-inclusive deep-inelastic scattering (SIDIS) off the deuteron target. In our derivation the nucleon parton distribution functions (PDFs) are assumed to be isospin SU(2) symmetric. Similar conditions have also been obtained for the fragmentation functions (FFs) of kaon by the sum of charged kaon multiplicities as well. We have chosen several FFs to study the impact of those conditions we have derived. Among those FFs, we find that the fragmentation functions produced by the nonlocal chiral-quark model (NLχQM) constantly satisfy the conditions. Furthermore, the ratios of the strange PDFs S (x ,Q2) and the non-strange PDFs Q (x ,Q2) extracted from the charged pion and kaon multiplicities differ from each other significantly. Finally, we demonstrate that the HERMES pion multiplicity data are unlikely to be compatible with two widely-used PDFs, namely CTEQ6L and leading order NNPDF3.0.

  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