2,095 research outputs found
Searching for Extra Dimensions in the Early Universe
We investigate extra spatial dimensions () in the early
universe using very high resolution molecular rotational spectroscopic data
derived from a large molecular cloud containing moderately cold carbon monoxide
gas at Z . It turns out that the -dependent quantum
mechanical wavelength transitions are solvable for a linear molecule and we
present the solution here. The CO microwave data allows a very precise
determination of . The probability
that is one in 7794, only 850 million years (using the
standard cosmology) after the Big Bang.Comment: 17 pages, 2 figure
The Parallel Persistent Memory Model
We consider a parallel computational model that consists of processors,
each with a fast local ephemeral memory of limited size, and sharing a large
persistent memory. The model allows for each processor to fault with bounded
probability, and possibly restart. On faulting all processor state and local
ephemeral memory are lost, but the persistent memory remains. This model is
motivated by upcoming non-volatile memories that are as fast as existing random
access memory, are accessible at the granularity of cache lines, and have the
capability of surviving power outages. It is further motivated by the
observation that in large parallel systems, failure of processors and their
caches is not unusual.
Within the model we develop a framework for developing locality efficient
parallel algorithms that are resilient to failures. There are several
challenges, including the need to recover from failures, the desire to do this
in an asynchronous setting (i.e., not blocking other processors when one
fails), and the need for synchronization primitives that are robust to
failures. We describe approaches to solve these challenges based on breaking
computations into what we call capsules, which have certain properties, and
developing a work-stealing scheduler that functions properly within the context
of failures. The scheduler guarantees a time bound of in expectation, where and are the work and
depth of the computation (in the absence of failures), is the average
number of processors available during the computation, and is the
probability that a capsule fails. Within the model and using the proposed
methods, we develop efficient algorithms for parallel sorting and other
primitives.Comment: This paper is the full version of a paper at SPAA 2018 with the same
nam
Physical and Antibacterial Properties of Peppermint Essential Oil Loaded Poly (Δ-caprolactone) (PCL) Electrospun Fiber Mats for Wound Healing
The aim of this study was to fabricate and characterize various concentrations of peppermint essential oil (PEP) loaded on poly(Δ-caprolactone) (PCL) electrospun fiber mats for healing applications, where PEP was intended to impart antibacterial activity to the fibers. SEM images illustrated that the morphology of all electrospun fiber mats was smooth, uniform, and bead-free. The average fiber diameter was reduced by the addition of PEP from 1.6 ± 0.1 to 1.0 ± 0.2 Όm. Functional groups of the fibers were determined by Raman spectroscopy. Gas chromatography-mass spectroscopy (GC-MS) analysis demonstrated the actual PEP content in the samples. In vitro degradation was determined by measuring weight loss and their morphology change, showing that the electrospun fibers slightly degraded by the addition of PEP. The wettability of PCL and PEP loaded electrospun fiber mats was measured by determining contact angle and it was shown that wettability increased with the incorporation of PEP. The antimicrobial activity results revealed that PEP loaded PCL electrospun fiber mats exhibited inhibition against Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria. In addition, an in-vitro cell viability assay using normal human dermal fibroblast (NHDF) cells revealed improved cell viability on PCL, PCLPEP1.5, PCLPEP3, and PCLGEL6 electrospun fiber mats compared to the control (CNT) after 48 h cell culture. Our findings showed for the first time PEP loaded PCL electrospun fiber mats with antibiotic-free antibacterial activity as promising candidates for wound healing applications
Evaluation of Electrospun Poly(Δ-Caprolactone)/Gelatin Nanofiber Mats Containing Clove Essential Oil for Antibacterial Wound Dressing
The objective of this study was to produce antibacterial poly(Δ-caprolactone) (PCL)-gelatin (GEL) electrospun nanofiber mats containing clove essential oil (CLV) using glacial acetic acid (GAA) as a âbenignâ (non-toxic) solvent. The addition of CLV increased the fiber diameter from 241 ± 96 to 305 ± 82 nm. Aside from this, the wettability of PCL-GEL nanofiber mats was increased by the addition of CLV. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the presence of CLV, and the actual content of CLV was determined by gas chromatographyâmass spectrometry (GC-MS). Our investigations showed that CLV-loaded PCL-GEL nanofiber mats did not have cytotoxic effects on normal human dermal fibroblast (NHDF) cells. On the other hand, the fibers exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli. Consequently, PCL-GEL/CLV nanofiber mats are potential candidates for antibiotic-free wound healing applications
Exponential Distribution of Locomotion Activity in Cell Cultures
In vitro velocities of several cell types have been measured using computer
controlled video microscopy, which allowed to record the cells' trajectories
over several days. On the basis of our large data sets we show that the
locomotion activity displays a universal exponential distribution. Thus, motion
resulting from complex cellular processes can be well described by an
unexpected, but very simple distribution function. A simple phenomenological
model based on the interaction of various cellular processes and finite ATP
production rate is proposed to explain these experimental results.Comment: 4 pages, 3 figure
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