351 research outputs found
Is trivial the antiferromagnetic RP(2) model in four dimensions?
We study the antiferromagnetic RP(2) model in four dimensions. We find a
second order transition with two order parameters, one ferromagnetic and the
other antiferromagnetic. The antiferromagnetic sector has mean-field critical
exponents and a renormalized coupling which goes to zero in the continuum
limit. The exponents of the ferromagnetic channel are not the mean-field ones,
but the difference can be interpreted as logarithmic corrections. We perform a
detailed analysis of these corrections and conclude the triviality of the
continuum limit of this model.Comment: 21 pages, 5 figures, LaTeX2
Effect of different digestates derived from anaerobic co-digestion of Olive Mill Solid Waste (OMSW) and various microalgae as fertilizers for the cultivation of ryegrass
Aims
The aim of this work was to evaluate the fertilizing effect of three anaerobic co-digestates on the growth of the herbaceous plant Lolium rigidum.
Methods
Nine treatments, combining different nutritional solutions (organic and inorganic) and number of fertilizations (one or two) were evaluated. Organic nutritive solution: plants grown with different olive mill solid waste (OMSW) -microalgae co-digestates: 75% OMSW-25% Raphidocelis subcapitata, volatile solids (VS) basis (OMSW-Rs); 50% OMSW- 50% Chlamydomonas Reinhardtii, VS basis (OMSW-Chl); and 75% OMSW-25% Secenedesmus quadricauda, VS basis (OMSW-Sq). Inorganic nutritive solution (INS): plants grown with inorganic Hoagland nutrient solution at 50%. After 60 days of experimentation, biometric and nutritional characteristics and photosynthetic activity were measured.
Results
The results showed a favourable growth, development and nutritional quality of L. rigidum plants when digestates obtained from the anaerobic co-digestion of OMSW-microalgae are used as organic nutritional solutions as opposed to INS ones. The highest total biomass of L. rigidum was obtained with the treatments that involved two fertilizations. No inhibition due to excess nutrients was observed. A higher root/shoot ratio was achieved with the digestates of OMSW-Rs and OMSW-Ch as compared to that obtained with OMSW-Sq (F = 17.23 p ≤ 0.001). The nitrogen shoot biomass obtained after the organic treatments with the above-mentioned co-digestates was higher than that obtained after the inorganic treatment. Net photosynthesis rates did not present differences in the co-digestates treatments, being equal or superior to the INS treatments.
Conclusions
The use of the anaerobic co-digestates from OMSW-microalgae can be considered a viable and promising alternative to inorganic fertilization
NGC1600 - Cluster or Field Elliptical?
A study of the galaxy distribution in the field of the elliptical galaxy
NGC1600 has been undertaken. Although this galaxy is often classified as a
member of a loose group, all the neighbouring galaxies are much fainter and
could be taken as satellites of NGC1600. The number density profile of galaxies
in the field of this galaxy shows a decline with radius, with evidence of a
background at approximately 1.3 Mpc. The density and number density profile are
consistent with that found for other isolated early-type galaxies. NGC1600
appears as an extended source in X-rays, and the center of the X-ray emission
seems not to coincide with the center of the galaxy. The velocity distribution
of neighbouring galaxies has been measured from optical spectroscopic
observations and shows that the mean radial velocity is approximately 85 km/s
less than that of NGC1600, indicating that the centre of mass could lie outside
the galaxy. The velocity dispersion of the `group' is estimated at 429 km/s.
The inferred mass of the system is therefore of the order of 10^14 solar
masses, a value that corresponds to a large group. NGC1600 therefore shares
some similarities, but is not identical to, the `fossil clusters' detected in
X-ray surveys. Implications of this result for studies of isolated early-type
galaxies are briefly discussed.Comment: 8 pages, 5 figures and 2 table, accepted for publication in the Ap
Critical Behavior of the Three-Dimensional Ising Spin Glass
We have simulated, using parallel tempering, the three dimensional Ising spin
glass model with binary couplings in a helicoidal geometry. The largest lattice
(L=20) has been studied using a dedicated computer (the SUE machine). We have
obtained, measuring the correlation length in the critical region, a strong
evidence for a second-order finite temperature phase transition ruling out
other possible scenarios like a Kosterlitz-Thouless phase transition. Precise
values for the and critical exponents are also presented.Comment: RevTex; 12 pages plus 5 ps figures. Final version to be published in
PR
Transferosomes as nanocarriers for drugs across the skin : quality by design from lab to industrial scale
Transferosomes, also known as transfersomes, are ultradeformable vesicles for transdermal applications consisting of a lipid bilayer with phospholipids and an edge activator and an ethanol/aqueous core. Depending on the lipophilicity of the active substance, it can be encapsulated within the core or amongst the lipid bilayer. Compared to liposomes, transferosomes are able to reach intact deeper regions of the skin after topical administration delivering higher concentrations of active substances making them a successful drug delivery carrier for transdermal applications. Most transferosomes contain phosphatidylcholine (C18) as it is the most abundant lipid component of the cell membrane, and hence, it is highly tolerated for the skin, decreasing the risk of undesirable effects, such as hypersensitive reactions. The most common edge activators are surfactants such as sodium deoxycholate, Tween® 80 and Span® 80. Their chain length is optimal for intercalation within the C18 phospholipid bilayer. A wide variety of drugs has been successfully encapsulated within transferosomes such as phytocompounds like sinomenine or apigenin for rheumatoid arthritis and leukaemia respectively, small hydrophobic drugs but also macromolecules like insulin. The main factors to develop optimal transferosomal formulations (with high drug loading and nanometric size) are the optimal ratio between the main components as well as the critical process parameters for their manufacture. Application of quality by design (QbD), specifically design of experiments (DoE), is crucial to understand the interplay among all these factors not only during the preparation at lab scale but also in the scale-up process. Clinical trials of a licensed topical ketoprofen transferosomal gel have shown promising results in the alleviation of symptons in orthreothritis with non-severe skin and subcutaneous tissue disorders. However, the product was withdrawn from the market which probably was related to the higher cost of the medicine linked to the expensive manufacturing process required in the production of transferosomes compared to other conventional gel formulations. This example brings out the need for a careful formulation design to exploit the best properties of this drug delivery system as well as the development of manufacturing processes easily scalable at industrial level
Antiferromagnetic 4-d O(4) Model
We study the phase diagram of the four dimensional O(4) model with first
(beta1) and second (beta2) neighbor couplings, specially in the beta2 < 0
region, where we find a line of transitions which seems to be second order. We
also compute the critical exponents on this line at the point beta1 =0 (F4
lattice) by Finite Size Scaling techniques up to a lattice size of 24, being
these exponents different from the Mean Field ones.Comment: 26 pages LaTeX2e, 7 figures. The possibility of logarithmic
corrections has been considered, new figures and tables added. Accepted for
publication in Physical Review
Seasonal and Long-Term Variability of the Mixed Layer Depth and its Influence on Ocean Productivity in the Spanish Gulf of Cádiz and Mediterranean Sea
The warming of the surface ocean is expected to increase the stratification of the upper water column. This would decrease the efficiency of the wind-induced mixing, reducing the nutrient supply to the euphotic layer and the productivity of the oceans. Climatic projections show that the Mediterranean Sea will experience a strong warming and salting along the twenty first century. Nevertheless, very few works have found and quantified changes in the water column stratification of the Western Mediterranean. In this work, we obtain time series of Mixed Layer Depth (MLD) along the Spanish Mediterranean waters and the Gulf of Cádiz, using periodic CTD profiles collected under the umbrella of the Ocean Observing system of the Instituto Español de Oceanografía (IEO-CSIC). The length of the time series analyzed is variable, depending on the geographical area, but in some cases these time series extend from the beginning of the 1990s decade. Our results show that at present, no statistically significant changes can be detected. These results are confirmed by the analysis of MLD time series obtained from Argo profilers. Some of the meteorological factors that could affect the water column stratification (wind intensity and precipitation rates) did not experience significant changes for the 1990-2021 period, neither were observed long-term changes in the chlorophyll concentration. The hypothesis proposed to explain this lack of trends, is that the salinity increase of the surface waters has compensated for the warming, and consequently, the density of the upper layer of the Western Mediterranean (WMED) has remained constant. As the wind intensity has not experienced significant trends, the stratification of the Spanish Mediterranean waters and those of the Gulf of Cádiz would have not been affected. Nevertheless, we do not discard that our results are a consequence of the short length of the available time series and the large variance of the variables analyzed, evidencing the importance of the maintenance of the ocean monitoring programs.En prens
Simulating spin systems on IANUS, an FPGA-based computer
We describe the hardwired implementation of algorithms for Monte Carlo
simulations of a large class of spin models. We have implemented these
algorithms as VHDL codes and we have mapped them onto a dedicated processor
based on a large FPGA device. The measured performance on one such processor is
comparable to O(100) carefully programmed high-end PCs: it turns out to be even
better for some selected spin models. We describe here codes that we are
currently executing on the IANUS massively parallel FPGA-based system.Comment: 19 pages, 8 figures; submitted to Computer Physics Communication
Impact of SARS-CoV-2 infection on liver disease
Introduction: Abnormal liver biochemistry is not a rare finding in the context of SARS-CoV-2 infection, regardless of patients having pre-existing chronic disease or not Content: This review examines the current body of knowledge on the relationship between COVID-19 and liver injury, which is frequently found in this setting Summary: Although the pathogenesis of liver injury is not fully understood, it has been suggested to be the result of a combination of multiple factors. These include direct injury caused by the virus, immune system hyperactivation, ischemic and drug-induced injury. The prognostic valor of these alterations is also the subject of intense research. Due to their potential impact, these alterations require proper management and treatment, especially in patients with chronic liver disease or liver transplant recipients. Outlook: Some aspects associated with liver injury during COVID-19, especially in severe presentations, are not well understood. Studies assessing the clinical impact of COVID-19 on the healthy or diseased liver may help adjust treatment and immunization guidelines to the profile of the patient. © 2022 Sergio Salgüero Fernández et al., published by De Gruyter, Berlin/Boston
Long-Term Changes in the Water Mass Properties in the Balearic Channels Over the Period 1996–2019
The analysis of a 24-year time series of Conductivity-Temperature-Depth (CTD) casts collected in the Balearic Channels (1996–2019) has allowed detecting and quantifying long-term changes in water mass properties in the Western Mediterranean. For the complete period, the intermediate waters have experienced warming and salting at rates of 1.4°C/100yr and 0.3–0.6/100yr for the Western Intermediate Water, and 1°C/100yr and 0.3–0.4/100yr for the Levantine Intermediate Water. The density of these two water masses has not changed. The deep waters, defined as those denser than 29.1 kg/m3, showed positive trends in temperature, salinity, and density (0.8°C/100yr, 0.2/100yr, and 0.02 kg.m–3/100yr, respectively). The high temporal variability of the upper layer makes the detection of long-term changes more difficult. Nevertheless, combining CTD data with temperature data from the oceanographic station at L’Estartit and simulated data from the NCEP/NCAR reanalysis, it can be established that the Atlantic Water increased its temperature at a rate of 2.1–2.8°C/100yr and likely its salinity at a rate of 0.6/100yr. The water column absorbed heat at a rate equivalent to 1–1.2 W/m2. All these trends are much higher than those reported in previous works (more than double in some cases). The warming of the water column produced an increase in the thermosteric component of sea level. However, this increase was compensated by the decrease in the halosteric component. Besides these changes, other alterations related to the Western Mediterranean Transition have been observed over shorter periods. The temperature and salinity of the intermediate waters increased before the winter of 2004/2005 and then the temperature and salinity of the deep waters increased dramatically in 2005. The density of the deep water reached values unprecedented before 2005. Deep and intermediate waters were uplifted by the presence of such dense deep waters. The arrival of warmer and saltier intermediate waters from the Eastern Mediterranean is also observed, mainly after 2010.Postprin
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