556 research outputs found
Mechanically-driven Stem Cell Separation in Tissues caused by Proliferating Daughter Cells
The homeostasis of epithelial tissue relies on a balance between the
self-renewal of stem cell populations, cellular differentiation, and loss.
Although this balance needs to be tightly regulated to avoid pathologies, such
as tumor growth, the regulatory mechanisms, both cell-intrinsic and collective,
which ensure tissue steady-state are still poorly understood. Here, we develop
a computational model that incorporates basic assumptions of stem cell renewal
into distinct populations and mechanical interactions between cells. We find
that the model generates unexpected dynamic features: stem cells repel each
other in the bulk tissue and are thus found rather isolated, as in a number of
in vivo contexts. By mapping the system onto a gas of passive Brownian
particles with effective repulsive interactions, that arise from the generated
flows of differentiated cells, we show that we can quantitatively describe such
stem cell distribution in tissues. The interaction potential between a pair of
stem cells decays exponentially with a characteristic length that spans several
cell sizes, corresponding to the volume of cells generated per stem cell
division. Our findings may help understanding the dynamics of normal and
cancerous epithelial tissues
Kompatibilität und Relevanz von Social Media in der mittelständischen Unternehmenspraxis: Ergebnisbericht einer empirischen Untersuchung
Die Nutzung von Social Media zu Unternehmenszwecken ist mittlerweile gängige Praxis. Sowohl Großunternehmen als auch zunehmend der Mittelstand setzen soziale Medien ein, um einerseits die Kollaboration mit internen und externen Stakeholdern zu fördern und um andererseits insbesondere ihre Kommunikationsprozesse sowohl innerhalb als auch außerhalb des Unternehmens zu optimieren.
Weitgehend unberücksichtigt bleiben dabei insbesondere im Mittelstand bislang die Besonderheiten dieser Unternehmen, die einen Einsatz von Social Media sowohl begünstigen als auch diesem eher entgegenstehen können.
Der vorliegende Forschungsbericht ist das Ergebnis einer Studie zu den unternehmenstypabhängigen Nutzungspotenzialen von Social Media im Mittelstand. Er soll einen Einblick in die Kompatibilität von Social Media mit den Charakteristika mittelständischer Unternehmenstypen sowie in die Nutzungspotenziale von Social Media in unterschiedlichen Anwendungsbereichen mittelständischer Unternehmen geben
Kompatibilität und Relevanz von Social Media in der mittelständischen Unternehmenspraxis: Materialien zur empirischen Untersuchung
Die Nutzung von Social Media zu Unternehmenszwecken ist mittlerweile gängige Praxis. Sowohl Großunternehmen als auch zunehmend der Mittelstand setzen soziale Medien ein, um einerseits die Kollaboration mit internen und externen Stakeholdern zu fördern und um andererseits insbesondere ihre Kommunikationsprozesse sowohl innerhalb als auch außerhalb des Unternehmens zu optimieren.
Weitgehend unberücksichtigt bleiben dabei insbesondere im Mittelstand bislang die Besonderheiten dieser Unternehmen, die einen Einsatz von Social Media sowohl begünstigen als auch diesem eher entgegenstehen können.
Die vorliegende Sammlung von Materialien ist das Ergebnis einer Studie zu den unternehmenstypabhängigen Nutzungspotenzialen von Social Media im Mittelstand. Sie stellt die wesentlichen Erkenntnisse in grafisch kondensierter Form dar und bildet die Grundlage für den vorab als Band 181 in der Reihe Bamberger Betriebswirtschaftliche Beiträge (BBB) veröffentlichten Ergebnisbericht
A Practical Second-Order Fault Attack against a Real-World Pairing Implementation
Several fault attacks against pairing-based
cryptography have been described theoretically in recent
years. Interestingly, none of these have been practically
evaluated. We accomplished this task and prove that fault
attacks against pairing-based cryptography are indeed
possible and are even practical — thus posing a serious
threat. Moreover, we successfully conducted a second-order fault attack against an open source implementation
of the eta pairing on an AVR XMEGA A1. We injected
the first fault into the computation of the Miller Algorithm
and applied the second fault to skip the final exponentiation completely. We introduce a low-cost setup that
allowed us to generate multiple independent faults in one
computation. The setup implements these faults by clock
glitches which induce instruction skips. With this setup we
conducted the first practical fault attack against a complete
pairing computation
Associations between BMI and the FTO Gene Are Age Dependent: Results from the GINI and LISA Birth Cohort Studies up to Age 6 Years
Objective: The association between polymorphisms in intron 1 of the fat mass and obesity associated gene (FTO) and obesity-related traits is one of the most robust associations reported for complex traits and is established both in adults and children. However, little is known about the longitudinal dynamics of these polymorphisms on body mass index (BMI), overweight, and obesity. Methods: This study is based on the 2,732 full-term neonates of the German GINI-plus and LISA-plus birth cohorts, for whom genotyping data on the FTO variants rs1558902 (T>A) or rs9935401 (G>A) were available. Children were followed from birth up to age 6 years. Up to 9 anthropometric measurements of BMI were obtained. Fractional-Polynomial-Generalized-Estimation-Equation modeling was used to assess developmental trends and their potential dependence on genotype status. Results: We observed no evidence for BMI differences between genotypes of both variants for the first 3 years of life. However, from age 3 years onwards, we noted a higher BMI for the homozygous minor alleles carriers in comparison to the other two genotype groups. However, evidence for statistical significance was reached from the age of 4 years onwards. Conclusions: This is one of the first studies investigating in detail the development of BMI depending on FTO genotype between birth and the age of 6 years in a birth cohort not selected for the phenotype studied. We observed that the association between BMI and FTO genotype evolves gradually and becomes descriptively detectable from the age of 3 years onwards
An expert consensus on the recommendations for the use of biomarkers in Fabry disease
Fabry disease is an X-linked lysosomal storage disorder caused by the accumulation of glycosphingolipids in various tissues and body fluids, leading to progressive organ damage and life-threatening complications. Phenotypic classification is based on disease progression and severity and can be used to predict outcomes. Patients with a classic Fabry phenotype have little to no residual α-Gal A activity and have widespread organ involvement, whereas patients with a later-onset phenotype have residual α-Gal A activity and disease progression can be limited to a single organ, often the heart. Diagnosis and monitoring of patients with Fabry disease should therefore be individualized, and biomarkers are available to support with this. Disease-specific biomarkers are useful in the diagnosis of Fabry disease; non-disease-specific biomarkers may be useful to assess organ damage. For most biomarkers it can be challenging to prove they translate to differences in the risk of clinical events associated with Fabry disease. Therefore, careful monitoring of treatment outcomes and collection of prospective data in patients are needed. As we deepen our understanding of Fabry disease, it is important to regularly re-evaluate and appraise published evidence relating to biomarkers. In this article, we present the results of a literature review of evidence published between February 2017 and July 2020 on the impact of disease-specific treatment on biomarkers and provide an expert consensus on clinical recommendations for the use of those biomarkers.publishedVersio
A Framework to Select Parameters for Lattice-Based Cryptography
Selecting parameters in lattice-based cryptography is a challenging task, which is essentially accomplished using one of two approaches. The first (very common) approach is to derive parameters assuming that the desired security level is equivalent to the bit hardness of the underlying lattice problem, ignoring the gap implied by available security reductions. The second (barely used) approach takes the gap and thus the security reduction into account. In this work, we investigate how efficient lattice-based schemes are if they respect existing security reductions. Thus, we present a framework to systematically select parameters for any lattice-based scheme using either approaches. We apply our methodology to the schemes by Lindner and Peikert (LP), by
El Bansarkhani (LARA), and by Ducas et al. (BLISS). We analyze their security reductions and derive a gap of 2, 3, and 63 bits, respectively. We show how parameters impact the schemes\u27 efficiency when involving these gaps
Risk factors and outcomes of unrecognised endobronchial intubation in major trauma patients
Background Emergency tracheal intubation during
major trauma resuscitation may be associated with
unrecognised endobronchial intubation. The risk factors
and outcomes associated with this issue have not
previously been fully defined.
Methods We retrospectively analysed adult patients
admitted directly from the scene to the ED of a single
level 1 trauma centre, who received either prehospital
or ED tracheal intubation prior to initial whole-body
CT
from January 2008 to December 2019. Our objectives
were to describe tube-to-
carina
distances (TCDs) via CT
and to assess the risk factors and outcomes (mortality,
length of intensive care unit stay and mechanical
ventilation) of patients with endobronchial intubation
(TCD <0 cm) using a multivariable model.
Results We included 616 patients and discovered 26
(4.2%) cases of endobronchial intubation identified
on CT. Factors associated with an increased risk of
endobronchial intubations were short body height
(OR per 1 cm increase 0.89; 95% CI 0.84 to 0.94;
p≤0.001), a high body mass index (OR 1.14; 95% CI
1.04 to 1.25; p=0.005) and ED intubation (OR 3.62;
95% CI 1.39 to 8.90; p=0.006). Eight of 26 cases
underwent tube thoracostomy, four of whom had no
evidence of underlying chest injury on CT. There was no
statistically significant difference in mortality or length
of stay although the absolute number of endobronchial
intubations was small.
Conclusions Short body height and high body mass
index were associated with endobronchial intubation.
Before considering tube thoracostomy in intubated
major trauma patients suspected of pneumothorax, the
possibility of unrecognised endobronchial intubation
should be considered
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