379 research outputs found
Rheology of granular flows across the transition from soft to rigid particles
International audienc
Ion Microscopy: A New Approach for Subcellular Localization of Labelled Molecules
Secondary ion mass spectroscopy (SIMS) was used to obtain images representing the intracellular distribution of molecules labelled with carbon 14.
Deoxyadenosine labelled with carbon 14 was added to a cultured human fibroblast cell medium, and the intracellular distribution of this molecule was studied using three different SIMS instruments: the CAMECA IMS 3F and SMI 300 ion microscopes and the UC-HRL scanning ion microprobe.
Carbon 14 distribution images obtained by this method show that deoxyadenosine U-C14 is present in the cytoplasm as well as the nucleus, with a higher concentration in\u27 the nucleoli. Our study clearly demonstrates that ion microscopy is well suited for carbon 14 detection and localization at the subcellular level, permitting a wide variety of microanalytical tracer experiments
Introduction to Configuration Path Integral Monte Carlo
In low-temperature high-density plasmas quantum effects of the electrons are
becoming increasingly important. This requires the development of new
theoretical and computational tools. Quantum Monte Carlo methods are among the
most successful approaches to first-principle simulations of many-body quantum
systems. In this chapter we present a recently developed method---the
configuration path integral Monte Carlo (CPIMC) method for moderately coupled,
highly degenerate fermions at finite temperatures. It is based on the second
quantization representation of the -particle density operator in a basis of
(anti-)symmetrized -particle states (configurations of occupation numbers)
and allows to tread arbitrary pair interactions in a continuous space.
We give a detailed description of the method and discuss the application to
electrons or, more generally, Coulomb-interacting fermions. As a test case we
consider a few quantum particles in a one-dimensional harmonic trap. Depending
on the coupling parameter (ratio of the interaction energy to kinetic energy),
the method strongly reduces the sign problem as compared to direct path
integral Monte Carlo (DPIMC) simulations in the regime of strong degeneracy
which is of particular importance for dense matter in laser plasmas or compact
stars. In order to provide a self-contained introduction, the chapter includes
a short introduction to Metropolis Monte Carlo methods and the second
quantization of quantum mechanics.Comment: chapter in book "Introduction to Complex Plasmas: Scientific
Challenges and Technological Opportunities", Michael Bonitz, K. Becker, J.
Lopez and H. Thomsen (Eds.) Springer Series "Atomic, Optical and Plasma
Physics", vol. 82, Springer 2014, pp. 153-194 ISBN: 978-3-319-05436-0 (Print)
978-3-319-05437-7 (Online
Finite-time fluctuations in the degree statistics of growing networks
This paper presents a comprehensive analysis of the degree statistics in
models for growing networks where new nodes enter one at a time and attach to
one earlier node according to a stochastic rule. The models with uniform
attachment, linear attachment (the Barab\'asi-Albert model), and generalized
preferential attachment with initial attractiveness are successively
considered. The main emphasis is on finite-size (i.e., finite-time) effects,
which are shown to exhibit different behaviors in three regimes of the
size-degree plane: stationary, finite-size scaling, large deviations.Comment: 33 pages, 7 figures, 1 tabl
Dissipation of vibration in rough contact
The relationship which links the normal vibration occurring during the sliding of rough surfaces and the nominal contact area is investigated. Two regimes are found. In the first one, the vibrational level does not depend on the contact area, while in the second one, it is propor- tional to the contact area. A theoretical model is proposed. It is based on the assumption that the vibrational level results from a competition between two processes of vibration damping, the internal damping of the material and the contact damping occurring at the interface
Static Friction Phenomena in Granular Materials: Coulomb Law vs. Particle Geometry
The static as well as the dynamic behaviour of granular material are
determined by dynamic {\it and} static friction. There are well known methods
to include static friction in molecular dynamics simulations using scarcely
understood forces. We propose an Ansatz based on the geometrical shape of
nonspherical particles which does not involve an explicit expression for static
friction. It is shown that the simulations based on this model are close to
experimental results.Comment: 11 pages, Revtex, HLRZ-33/9
On passion and moral behavior in achievement settings: The mediating role of pride
The Dualistic Model of Passion (Vallerand et al., 2003) distinguishes two types of passion: harmonious passion (HP) and obsessive passion (OP) that predict adaptive and less adaptive outcomes, respectively. In the present research, we were interested in understanding the role of passion in the adoption of moral behavior in achievement settings. It was predicted that the two facets of pride (authentic and hubristic; Tracy & Robins, 2007) would mediate the passion-moral behavior relationship. Specifically, because people who are passionate about a given activity are highly involved in it, it was postulated that they should typically do well and thus experience high levels of pride when engaged in the activity. However, it was also hypothesized that while both types of passion should be conducive to authentic pride, only OP should lead to hubristic pride. Finally, in line with past research on pride (Carver, Sinclair, & Johnson, 2010; Tracy et al., 2009), only hubristic pride was expected to negatively predict moral behavior, while authentic pride was expected to positively predict moral behavior. Results of two studies conducted with paintball players (N=163, Study 1) and athletes (N=296, Study 2) supported the proposed model. Future research directions are discussed in light of the Dualistic Model of Passion
Is radiotherapy required in first-line treatment of stage I diffuse anaplastic Wilms tumor? A report of SIOP-RTSG, AIEOP, JWiTS, and UKCCSG
BACKGROUND: As a significant proportion of relapses occurred in the tumor bed or abdomen on patients with the fifth National Wilms Tumor Study stage I anaplastic Wilms tumor (WT), flank radiotherapy was added for stage I anaplastic WT in the subsequent study of the Children's Oncology Group (AREN0321). Preliminary results revealed reduction of relapse rate and improved survival. In cases treated with preoperative chemotherapy, such as in International Society of Pediatric Oncology (SIOP), the value of radiotherapy has never been studied. The aim of this observational study is to describe the pattern of recurrence and survival of patients with stage I diffuse anaplastic WT (DAWT) after induction chemotherapy. METHODS: Retrospective data analysis of the pattern of relapse and survival of all patients with stage I DAWT were included in recent SIOP, L'Associazone Italiana Ematologica Oncologia Pediatrica (AIEOP), Japan Wilms Tumor Study Group (JWiTS), United Kingdom Children's Cancer Study Group (UKCCSG) renal tumor registries. Postoperative treatment consisted of actinomycin D, vincristine, and doxorubicin for 28 weeks without local irradiation. RESULTS: One hundred nine cases with stage I DAWT were identified, of which 95 cases received preoperative chemotherapy. Of these, seven patients underwent preoperative trueâcut biopsy. Sixteen of the 95 patients relapsed (17%), six locally, four at distant site, and six combined, and all treated according to SIOP 2001 relapse protocol, which resulted in a 5âyear overall survival of 93%. CONCLUSION: Despite 13% locoregional relapse rate, an excellent rescue rate was achieved after salvage treatment, in patients with stage I DAWT whose firstâline treatment comprised threeâdrug chemotherapy (including doxorubicin), without flank irradiation. Therefore, we continue not to advocate the use of radiotherapy in firstâline treatment after preoperative chemotherapy in stage I DAWT in the next SIOP protocol
Characteristics and outcome of pediatric renal cell carcinoma patients registered in the International Society of Pediatric Oncology (SIOP) 93â01, 2001 and UKâIMPORT database: A report of the SIOPâRenal Tumor Study Group
In children, renal cell carcinoma (RCC) is rare. This study is the first report of pediatric patients with RCC registered by the International Society of Pediatric OncologyâRenal Tumor Study Group (SIOPâRTSG). Pediatric patients with histologically confirmed RCC, registered in SIOP 93â01, 2001 and UKâIMPORT databases, were included. Eventâfree survival (EFS) and overall survival (OS) were analyzed using the KaplanâMeier method. Between 1993 and 2019, 122 pediatric patients with RCC were registered. Available detailed data (n = 111) revealed 56 localized, 30 regionally advanced, 25 metastatic and no bilateral cases. Histological classification according to World Health Organization 2004, including immunohistochemical and molecular testing for transcription factor E3 (TFE3) and/or EB (TFEB) translocation, was available for 65/122 patients. In this group, the most common histological subtypes were translocation type RCC (MiTâRCC) (36/64, 56.3%), papillary type (19/64, 29.7%) and clear cell type (4/64, 6.3%). One histological subtype was not reported. In the remaining 57 patients, translocation testing could not be performed, or TFEâcytogenetics and/or immunohistochemistry results were missing. In this group, the most common RCC histological subtypes were papillary type (21/47, 44.7%) and clear cell type (11/47, 23.4%). Ten histological subtypes were not reported. Estimated 5âyear (5y) EFS and 5yâOS of the total group was 70.5% (95% CI = 61.7%â80.6%) and 84.5% (95% CI = 77.5%â92.2%), respectively. Estimated 5yâOS for localized, regionally advanced, and metastatic disease was 96.8%, 92.3%, and 45.6%, respectively. In conclusion, the registered pediatric patients with RCC showed a reasonable outcome. Survival was substantially lower for patients with metastatic disease. This descriptive study stresses the importance of full, prospective registration including TFEâtesting
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