2,005 research outputs found
Biogenic polymer-based patches for congenital cardiac surgery: a feasibility study.
OBJECTIVE
Currently used patch materials in congenital cardiac surgery do not grow, renew, or remodel. Patch calcification occurs more rapidly in pediatric patients eventually leading to reoperations. Bacterial cellulose (BC) as a biogenic polymer offers high tensile strength, biocompatibility, and hemocompatibility. Thus, we further investigated the biomechanical properties of BC for use as patch material.
METHODS
The BC-producing bacteria Acetobacter xylinum were cultured in different environments to investigate optimal culturing conditions. For mechanical characterization, an established method of inflation for biaxial testing was used. The applied static pressure and deflection height of the BC patch were measured. Furthermore, a displacement and strain distribution analysis was performed and compared to a standard xenograft pericardial patch.
RESULTS
The examination of the culturing conditions revealed that the BC became homogenous and stable when cultivated at 29°C, 60% oxygen concentration, and culturing medium exchange every third day for a total culturing period of 12 days. The estimated elastic modulus of the BC patches ranged from 200 to 530â
MPa compared to 230â
MPa for the pericardial patch. The strain distributions, calculated from preloaded (2â
mmHg) to 80â
mmHg inflation, show BC patch strains ranging between 0.6% and 4%, which was comparable to the pericardial patch. However, the pressure at rupture and peak deflection height varied greatly, ranging from 67 to around 200â
mmHg and 0.96 to 5.28â
mm, respectively. The same patch thickness does not automatically result in the same material properties indicating that the manufacturing conditions have a significant impact on durability.
CONCLUSIONS
BC patches can achieve comparable results to pericardial patches in terms of strain behavior as well as in the maximum applied pressure that can be withstood without rupture. Bacterial cellulose patches could be a promising material worth further research
Slow dynamics and aging in a non-randomly frustrated spin system
A simple, non-disordered spin model has been studied in an effort to
understand the origin of the precipitous slowing down of dynamics observed in
supercooled liquids approaching the glass transition. A combination of Monte
Carlo simulations and exact calculations indicates that this model exhibits an
entropy vanishing transition accompanied by a rapid divergence of time scales.
Measurements of various correlation functions show that the system displays a
hierarchy of time scales associated with different degrees of freedom. Extended
structures, arising from the frustration in the system, are identified as the
source of the slow dynamics. In the simulations, the system falls out of
equilibrium at a temperature higher than the entropy-vanishing
transition temperature and the dynamics below exhibits aging as
distinct from coarsening. The cooling rate dependence of the energy is also
consistent with the usual glass formation scenario.Comment: 41 pages, 16 figures. Bibliography file is correcte
Episodic memory and theory of mind : a connection reconsidered
In the literature on episodic memory, one claim that has been made by a number of psychologists (e.g., Perner & Ruffman, 1995; Suddendorf & Corballis, 1997; Wheeler, Stuss, & Tulving, 1997), and that is also at least implicit in some of the accounts given by philosophers (e.g., Dokic, 2001; FernĂĄndez, 2008; Owens, 1996), is that being able to recollect particular past events in the distinctive way afforded by episodic memory requires the possession of aspects of a theory of mind, such as a grasp of the relationship between oneâs present recollective experience and oneâs own past perceptual experience of the remembered event. In this paper, I re-examine what connection, if any, there is between episodic memory and theory of mind. I first criticize the dominant way in which this connection has been construed theoretically, which â perhaps influenced by other aspects of theory of mind research â has sought to link the possession of episodic memory primarily with a grasp of the idea of representation, or the idea of informational access. I then argue for a novel, alternative, way of connecting episodic memory and theory of mind, which focuses on the category of an experience, and on the role a grasp of that category might be seen to play in episodic recollection. In doing so, I also draw attention to a dimension of our understanding of the mental which remains as yet underexplored in the literature on theory of mind
Oral High-Dose Atorvastatin Treatment in Relapsing-Remitting Multiple Sclerosis
BACKGROUND:Recent data from animal models of multiple sclerosis (MS) and from a pilot study indicated a possible beneficial impact of statins on MS. METHODOLOGY/PRINCIPAL FINDINGS:Safety, tolerability and effects on disease activity of atorvastatin given alone or in combination with interferon-beta (IFN-beta) were assessed in a phase II open-label baseline-to-treatment trial in relapsing-remitting MS (RRMS). Patients with at least one gadolinium-enhancing lesion (CEL) at screening by magnetic resonance imaging (MRI) were eligible for the study. After a baseline period of 3 monthly MRI scans (months -2 to 0), patients followed a 9-month treatment period on 80 mg atorvastatin daily. The number of CEL in treatment months 6 to 9 compared to baseline served as the primary endpoint. Other MRI-based parameters as well as changes in clinical scores and immune responses served as secondary endpoints. Of 80 RRMS patients screened, 41 were included, among them 16 with IFN-beta comedication. The high dose of 80 mg atorvastatin was well tolerated in the majority of patients, regardless of IFN-beta comedication. Atorvastatin treatment led to a substantial reduction in the number and volume of CEL in two-sided multivariate analysis (p = 0.003 and p = 0.008). A trend towards a significant decrease in number and volume of CEL was also detected in patients with IFN-beta comedication (p = 0.060 and p = 0.062), in contrast to patients without IFN-beta comedication (p = 0.170 and p = 0.140). Immunological investigations showed no suppression in T cell response but a significant increase in IL-10 production. CONCLUSIONS/SIGNIFICANCE:Our data suggest that high-dose atorvastatin treatment in RRMS is safe and well tolerated. Moreover, MRI analysis indicates a possible beneficial effect of atorvastatin, alone or in combination with IFN-beta, on the development of new CEL. Thus, our findings provide a rationale for phase II/III trials, including combination of atorvastatin with already approved immunomodulatory therapy regimens. TRIAL REGISTRATION:ClinicalTrials.gov NCT00616187
Multi-particle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider
Measurements of multi-particle azimuthal correlations (cumulants) for charged
particles in p-Pb and Pb-Pb collisions are presented. They help address the
question of whether there is evidence for global, flow-like, azimuthal
correlations in the p-Pb system. Comparisons are made to measurements from the
larger Pb-Pb system, where such evidence is established. In particular, the
second harmonic two-particle cumulants are found to decrease with multiplicity,
characteristic of a dominance of few-particle correlations in p-Pb collisions.
However, when a gap is placed to suppress such correlations,
the two-particle cumulants begin to rise at high-multiplicity, indicating the
presence of global azimuthal correlations. The Pb-Pb values are higher than the
p-Pb values at similar multiplicities. In both systems, the second harmonic
four-particle cumulants exhibit a transition from positive to negative values
when the multiplicity increases. The negative values allow for a measurement of
to be made, which is found to be higher in Pb-Pb collisions at
similar multiplicities. The second harmonic six-particle cumulants are also
found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find
which is indicative of a Bessel-Gaussian
function for the distribution. For very high-multiplicity Pb-Pb
collisions, we observe that the four- and six-particle cumulants become
consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and
Pb-Pb are measured. These are found to be similar for overlapping
multiplicities, when a gap is placed.Comment: 25 pages, 11 captioned figures, 3 tables, authors from page 20,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/87
Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at = 5.02 TeV
Two-particle angular correlations between unidentified charged trigger and
associated particles are measured by the ALICE detector in p-Pb collisions at a
nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum
range 0.7 5.0 GeV/ is examined,
to include correlations induced by jets originating from low
momen\-tum-transfer scatterings (minijets). The correlations expressed as
associated yield per trigger particle are obtained in the pseudorapidity range
. The near-side long-range pseudorapidity correlations observed in
high-multiplicity p-Pb collisions are subtracted from both near-side
short-range and away-side correlations in order to remove the non-jet-like
components. The yields in the jet-like peaks are found to be invariant with
event multiplicity with the exception of events with low multiplicity. This
invariance is consistent with the particles being produced via the incoherent
fragmentation of multiple parton--parton scatterings, while the yield related
to the previously observed ridge structures is not jet-related. The number of
uncorrelated sources of particle production is found to increase linearly with
multiplicity, suggesting no saturation of the number of multi-parton
interactions even in the highest multiplicity p-Pb collisions. Further, the
number scales in the intermediate multiplicity region with the number of binary
nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/161
Jesus, Barabbas and the People: The Climax of Lukeâs Trial Narrative and Lukan Christology (Luke 23.13-25)
This article argues that the nuance and function given to the Barabbas pericope in Lukeâs trial narrative differs significantly from that expressed by the other evangelists. It submits that Luke depicts Jesusâ death to be the result of a substitution between the acquitted Jesus and the insurrectionist and murderer Barabbas. Furthermore, the third evangelist has crafted his trial narrative so as to highlight the representative nature of this death, thereby developing Jesusâ narrative identity as the Messiah. It is concluded that Lukeâs crafting of his trial narrative raises questions for the prevalent view that the third evangelist has not integrated the idea of substitution into his understanding of Jesusâ death
The Replication Database:Documenting the Replicability of Psychological Science
In psychological science, replicabilityârepeating a study with a new sample achieving consistent results (Parsons et al., 2022)âis critical for affirming the validity of scientific findings. Despite its importance, replication efforts are few and far between in psychological science with many attempts failing to corroborate past findings. This scarcity, compounded by the difficulty in accessing replication data, jeopardizes the efficient allocation of research resources and impedes scientific advancement. Addressing this crucial gap, we present the Replication Database (https://forrt-replications.shinyapps.io/fred_explorer), a novel platform hosting 1,239 original findings paired with replication findings. The infrastructure of this database allows researchers to submit, access, and engage with replication findings. The database makes replications visible, easily findable via a graphical user interface, and tracks replication rates across various factors, such as publication year or journal. This will facilitate future efforts to evaluate the robustness of psychological research
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