323 research outputs found
Enhancement of drag and mixing in a dilute solution of rodlike polymers at low Reynolds numbers
We study the dynamics of a dilute solution of rigid rodlike polymers in a
viscous fluid at low Reynolds number by means of numerical simulations of a
simple rheological model. We show that the rotational dynamics of polymers
destabilizes the laminar flow and causes the emergence of a turbulent-like
chaotic flow with a wide range of active scales. This regime displays an
increased flow resistance, corresponding to a reduced mean flow at fixed
external forcing, as well as an increased mixing efficiency. The latter effect
is quantified by measuring the decay of the variance of a scalar field
transported by the flow. By comparing the results of numerical simulations of
the model in two- and three-dimensions, we show that the phenomena observed are
qualitatively independent on the dimensionality of the space.Comment: 18 pages, 13 figure
Conformal invariance of weakly compressible two-dimensional turbulence
We study conformal invariance of vorticity clusters in weakly compressible
two-dimensional turbulence at low Mach numbers. On the basis of very high
resolution direct numerical simulation we demonstrate the scaling invariance of
the inverse cascade with scaling close to Kolmogorov prediction. In this range
of scales, the statistics of zero-vorticity isolines are found to be compatible
with those of critical percolation, thus generalizing the results obtained in
incompressible Navier-Stokes turbulence.Comment: 7 pages, 8 figure
Ammonium recovery from agro-industrial digestate using bioelectrochemical systems
Abstract
Growing food and biomass production at the global scale has determined a corresponding increase in the demand for and use of nutrients. In this study, the possibility of recovering nitrogen from agro-industrial digestate using bioelectrochemical systems was investigated: two microbial electrolysis cells (MECs) were fed with synthetic and real digestate (2.5 gNH4+-N L−1). Carbon felt and granular graphite were used as anodes in MEC-1 and MEC-2, respectively. As to synthetic wastewater, the optimal nitrogen load (NL) for MEC-1 and -2 was 1.25 and 0.75 gNH4+-N d−1, respectively. MEC-1 showed better performance in terms of NH4+-N removal efficiency (39 ± 2.5%) and recovery rate (up to 70 gNH4+-N m−2d−1), compared to MEC-2 (33 ± 4.7% and up to 30 gN m−2d−1, respectively). At the optimal hydraulic retention time, lower NH4+-N removal efficiencies and recovery rates were observed when real digestate was fed to MEC-1 (29 ± 6.6% and 60 ± 13 gNH4+-N m−2d−1, respectively) and MEC-2 (21 ± 7.9% and 10 ± 3.6 gNH4+-N m−2d−1, respectively), likely due to the higher complexity of the influent. The average energy requirements were 3.6–3.7 kWh kgNremoved−1, comparable with values previously reported in the literature and lower than conventional ammonia recovery processes. Results are promising and may reduce the need for costly and polluting processes for nitrogen synthesis
Structuring targeted surveillance for monitoring disease emergence by mapping observational data onto ecological process
An efficient surveillance system is a crucial factor in identifying, monitoring and tackling outbreaks of infectious diseases. Scarcity of data and limited amounts of economic resources require a targeted effort from public health authorities. In this paper, we propose a mathematical method to identify areas where surveillance is critical and low reporting rates might leave epidemics undetected. Our approach combines the use of reference-based susceptible-exposed-infectious models and observed reporting data;We propose two different specifications, for constant and time-varying surveillance, respectively. Our case study is centred around the spread of the raccoon rabies epidemic in the state of New York, using data collected between 1990 and 2007. Both methods offer a feasible solution to analyse and identify areas of intervention
Milk cathelicidin and somatic cell counts in dairy goats along the course of lactation
This research communication reports the evaluation of cathelicidin in dairy goat milk for its relationship with the somatic cell count (SCC) and microbial culture results. Considering the limited performances of SCC for mastitis monitoring in goats, there is interest in evaluating alternative diagnostic tools. Cathelicidin is an antimicrobial protein involved in innate immunity of the mammary gland. In this work, half-udder milk was sampled bimonthly from a herd of 37 Alpine goats along an entire lactation and tested with the cathelicidin ELISA together with SCC and bacterial culture. Cathelicidin and SCC showed a strong correlation (r = 0.72; n = 360 milk samples). This was highest in mid-lactation (r = 0.83) and lowest in late lactation (r = 0.61), and was higher in primiparous (0.80, n = 130) than in multiparous goats (0.71, n = 230). Both markers increased with stage of lactation, but cathelicidin increased significantly less than SCC. Inaddition, peak level in late lactation was lower for cathelicidin (5.05-fold increase) than for SCC (7.64-fold increase). Twenty-one (5.8%) samples were positive to bacteriological culture, 20 for coagulase-negative staphylococci and one for Streptococcus spp.; 18 of them were positive to the cathelicidin ELISA (85.71% sensitivity). Sensitivity of SCC >500 000 and of SCC >1 000 000 cells/ml was lower (71.43 and 23.81%, respectively). Therefore, the high correlation of cathelicidin with SCC during the entire lactation, along with its lower increase in late lactation and good sensitivity indetecting intramammary infection (IMI), indicate a potential for monitoring subclinical mastitis in dairy goats. However, based on this preliminary assessment, specificity should be improved (40.41% for cathelicidin vs. 54.57 and 67.85% for SCC >500 000 and >1 000 000 cells/ml, respectively). Therefore, the application of cathelicidin for detecting goat IMI will require further investigation and optimization, especially concerning the definition of diagnostic thresholds
Whole-exome analysis in osteosarcoma to identify a personalized therapy
Osteosarcoma is the most common pediatric primary non-hematopoietic bone
tumor. Survival of these young patients is related to the response to chemotherapy and
development of metastases. Despite many advances in cancer research, chemotherapy
regimens for osteosarcoma are still based on non-selective cytotoxic drugs. It is essential
to investigate new specific molecular therapies for osteosarcoma to increase the survival
rate of these patients. We performed exomic sequence analyses of 8 diagnostic biopsies
of patients with conventional high grade osteosarcoma to advance our understanding
of their genetic underpinnings and to correlate the genetic alteration with the clinical
and pathological features of each patient to identify a personalized therapy.
We identified 18,275 somatic variations in 8,247 genes and we found three
mutated genes in 7/8 (87%) samples (KIF1B, NEB and KMT2C). KMT2C showed the
highest number of variations; it is an important component of a histone H3 lysine 4
methyltransferase complex and it is one of the histone modifiers previously implicated
in carcinogenesis, never studied in osteosarcoma. Moreover, we found a group of 15
genes that showed variations only in patients that did not respond to therapy and
developed metastasis and some of these genes are involved in carcinogenesis and
tumor progression in other tumors.
These data could offer the opportunity to get a key molecular target to identify
possible new strategies for early diagnosis and new therapeutic approaches for
osteosarcoma and to provide a tailored treatment for each patient based on their
genetic profile
A variational pseudo-self-interaction correction approach: ab-initio description of correlated oxides and molecules
We present a fully variational generalization of the pseudo self-interaction
correction (VPSIC) approach previously presented in two implementations based
on plane-waves and atomic orbital basis set, known as PSIC and ASIC,
respectively. The new method is essentially equivalent to the previous version
for what concern the electronic properties, but it can be exploited to
calculate total-energy derived properties as well, such as forces and
structural optimization. We apply the method to a variety of test cases
including both non-magnetic and magnetic correlated oxides and molecules,
showing a generally good accuracy in the description of both structural and
electronic properties.Comment: 23 pages, 9 tables, 16 figure
DESIGNING OF A RT REAL TIME PCR ASSAY BASED ON NS1 GENE FOR RAPID DETECTION OF USUTU VIRUS (USUV)
Introduction: Usutu virus belongs to the Japanese encephalitis virus group (the isolates exhibited 97% identity) within the family Flaviviridae closely related to West Nile virus (WNV). Both share in nature an enzootic infectious cycle between avian hosts and mosquito vectors (i.e. Culex spp.). The distribution areal is expanding in several European countries, including Italy; the simultaneous spatial and temporal co-circulation of new flaviviruses require a new approaches in the laboratory diagnosis for Flaviviridae infection in humans
Characteristics of patients admitted to emergency department for asthma attack: A real-LIFE study
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