1,013 research outputs found
Solving the Optimal Trading Trajectory Problem Using a Quantum Annealer
We solve a multi-period portfolio optimization problem using D-Wave Systems'
quantum annealer. We derive a formulation of the problem, discuss several
possible integer encoding schemes, and present numerical examples that show
high success rates. The formulation incorporates transaction costs (including
permanent and temporary market impact), and, significantly, the solution does
not require the inversion of a covariance matrix. The discrete multi-period
portfolio optimization problem we solve is significantly harder than the
continuous variable problem. We present insight into how results may be
improved using suitable software enhancements, and why current quantum
annealing technology limits the size of problem that can be successfully solved
today. The formulation presented is specifically designed to be scalable, with
the expectation that as quantum annealing technology improves, larger problems
will be solvable using the same techniques.Comment: 7 pages; expanded and update
Linkages among Population, Food Production, and the Environment at Multiple Scales
Human population, its number and distribution on our planet, has a seemingly direct linkage to how much food we consume and how we practice agriculture. How this population-foodenvironment interface manifests across the globe is complex, non-linear, and both local- and scale-dependent. This essay is an overview of the population-food-environment nexus, providing recent history and statistics on these processes at several crude scales. We include a discussion of theory, review different drivers of the population-food-environment processes, provide a global overview of population and agricultural statistics from 1970 to 2010, and discuss trends and implications for Latin America, as well as some specific multi-scale case studies. We conclude with a review of potential future trends and proposed solutions
Self-similar and charged spheres in the diffusion approximation
We study spherical, charged and self--similar distributions of matter in the
diffusion approximation. We propose a simple, dynamic but physically meaningful
solution. For such a solution we obtain a model in which the distribution
becomes static and changes to dust. The collapse is halted with damped mass
oscillations about the absolute value of the total charge.Comment: 15 pages, 7 figure
A search for late-type supergiants in the inner regions of the Milky Way
We present the results of a narrow-band infrared imaging survey of a narrow
strip (12' wide) around the galactic equator between 6 deg and 21 deg of
galactic longitude aimed at detecting field stars with strong CO absorption,
mainly late-type giants and supergiants. Our observations include follow-up low
resolution spectroscopy (R = 980) of 191 selected candidates in the H and K
bands. Most of these objects have photometric and spectroscopic characteristics
consistent with them being red giants, and some display broad, strong
absorption wings due to water vapor absorption between the H and K bands. We
also identify in our sample 18 good supergiant candidates characterized by
their lack of noticeable water absorption, strong CO bands in the H and K
windows, and HK_S photometry suggestive of high intrinsic luminosity and
extinctions reaching up to A_V ~40 mag. Another 9 additional candidates share
the same features except for weak H2O absorption, which is also observed among
some M supergiants in the solar neighbourhood. Interesting differences are
noticed when comparing our stars to a local sample of late-type giants and
supergiants, as well as to a sample of red giants in globular clusters of
moderately subsolar metallicity and to a sample of bulge stars. (...) We
propose that the systematic spectroscopic differences of our inner Galaxy stars
are due to their higher metallicities that cause deeper mixing in their
mantles, resulting in lower surface abundances of C and O and higher abundances
of CN, which contribute to the strength of the CaI and NaI features at low
resolution. Our results stress the limitations of using local stars as
templates for the study of composite cool stellar populations such as central
starbursts in galaxies (Abridged).Comment: 21 pages (including figures), A&A accepte
Orbital free ab initio molecular dynamics study of liquid Al near melting
Producción CientíficaThe orbital free ab initio molecular dynamics method is applied to study the static and dynamic
structure of liquid Al near the triple point. The method uses a new kinetic energy functional, along
with a local pseudopotential constructed within the same kinetic energy functional. The results
obtained for the dynamic structure factor are compared with recent experimental data
Fibrin association at hybrid biointerfaces made of clot-binding peptides and polythiophene
The properties as biointerfaces of electroactive conducting polymer-peptide biocomposites formed by poly(3,4-ethylenedioxythiophene) (PEDOT) and CREKA or CR(NMe)EKA peptide sequences (where Glu has been replaced by N-methyl-Glu in the latter) have been compared. CREKA is a linear pentapeptide that recognizes clotted plasma proteins and selectively homes to tumors, while CR(NMe)EKA is an engineer to improve such properties by altering peptide-fibrin interactions. Differences between PEDOT-CREKA and PEDOT-CR(NMe)EKA reflect dissemblance in the organization of the peptides into the polymeric matrix. Both peptides affect fibrinogen thrombin-catalyzed polymerization causing the immediate formation of fibrin, whereas in the absence of thrombin this phenomenon is only observed for CR(NMe)EKA. Consistently, the fibrin-adsorption capacity is higher for PEDOT-CR(NMe)EKA than for PEDOT-CREKA, even though in both cases adsorbed fibrin exhibits round-like morphologies rather than the characteristic fibrous structure. PEDOT-peptide films coated with fibrin are selective in terms of cell adhesion, promoting the attachment of metastatic cells with respect to normal cells.Peer ReviewedPostprint (author's final draft
Anti-Obesity Effects of Isorhamnetin and Isorhamnetin Conjugates
Isorhamnetin is a plant-derived secondary metabolite which belongs to the family of flavonoids. This review summarises the main outcomes described in the literature to date, regarding the effects of isorhamnetin on obesity from in vitro and in vivo studies. The studies carried out in pre-adipocytes show that isorhamnetin is able to reduce adipogenesis at 10 μM or higher doses and that these effects are mediated by Pparγ and by Wnt signalling pathway. Very few studies addressed in rodents are available so far. It seems that treatment periods longer than two weeks are needed by isorhamnetin and its glycosides to be effective as anti-obesity agents. Nevertheless, improvements in glycaemic control can be observed even in short treatments. Regarding the underlying mechanisms of action, although some contradictory results have been found, reductions in de novo lipogenesis and fatty acid uptake could be proposed. Further research is needed to increase the scientific evidence referring to this topic; studies in animal models are essential, as well as randomised clinical trials to determine whether the positive results observed in animals could also be found in humans, in order to determine if isorhamnetin and its glycosides can represent a real tool against obesity.This study was supported by the Instituto de Salud Carlos III (CIBERobn) under Grant CB12/03/30007 and the Ministerio de Ciencia e Innovación (PID2020-118300RB-C21 and PID2020-118300RB-C22 co-funded by FEDER)
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Enrichment of native plastic associated biofilm communities to enhance polyester degrading activity
Data Availability Statement: All data is available upon reasonable request to the corresponding author. Sequence data has been deposited in the NCBI SRA database and GenBank and is available under the code PRJNA962804.Supporting Information is available online at https://ami-journals.onlinelibrary.wiley.com/doi/full/10.1111/1462-2920.16466#support-information-section .Copyright © 2023 The Authors. Plastic pollution is an increasing worldwide problem urgently requiring a solution. While recycling rates are increasing globally, only 9% of all plastic waste has been recycled, and with the cost and limited downstream uses of recycled plastic, an alternative is needed. Here, we found that expanded polystyrene (EPS) promoted high levels of bacterial biofilm formation and sought out environmental EPS waste to characterize these native communities. We demonstrated that the EPS attached communities had limited plastic degrading activity. We then performed a long-term enrichment experiment where we placed a robust selection pressure on these communities by limiting carbon availability such that the waste plastic was the only carbon source. Seven of the resulting enriched bacterial communities had increased plastic degrading activity compared to the starting bacterial communities. Pseudomonas stutzeri was predominantly identified in six of the seven enriched communities as the strongest polyester degrader. Sequencing of one isolate of P. stutzeri revealed two putative polyesterases and one putative MHETase. This indicates that waste plastic-associated biofilms are a source for bacteria that have plastic-degrading potential, and that this potential can be unlocked through selective pressure and further in vitro enrichment experiments, resulting in biodegradative communities that are better than nature.Academy of Medical Sciences/the Wellcome Trust/the Government Department of Business, Energy and Industrial Strategy/the British Heart Foundation/Diabetes UK Springboard Award. Grant Number: SBF006/1040;
Biotechnology and Biological Sciences Research Council New Investigator Award. Grant Number: BB/V007823/1;
European Commission. Grant Number: 887648;
Natural Environment Research Council. Grant Number: NE/X010902/1
Wireless Sensor Networks for Oceanographic Monitoring: A Systematic Review
Monitoring of the marine environment has come to be a field of scientific interest in the last ten years. The instruments used in this work have ranged from small-scale sensor networks to complex observation systems. Among small-scale networks, Wireless Sensor Networks (WSNs) are a highly attractive solution in that they are easy to deploy, operate and dismantle and are relatively inexpensive. The aim of this paper is to identify, appraise, select and synthesize all high quality research evidence relevant to the use of WSNs in oceanographic monitoring. The literature is systematically reviewed to offer an overview of the present state of this field of study and identify the principal resources that have been used to implement networks of this kind. Finally, this article details the challenges and difficulties that have to be overcome if these networks are to be successfully deployed
The H2 velocity structure of inner knots in HH 212: asymmetries and rotation
High-resolution R~50 000 long-slit spectroscopy of the inner knots of the
highly symmetrical protostellar outflow HH 212 was obtained in the 1-0 S(1)
line of H2 at 2.12 micron with a spatial resolution of ~0.45 arcsec. At the
resulting velocity resolution of ~6 km s-1, multiple slit oriented observations
of the northern first knot NK1 clearly show double-peaked line profiles
consistent with either a radiative bow shock or dual (forward and reverse)
shocks. In contrast, the velocity distribution of the southern first knot SK1
remains single-peaked, suggesting a significantly lower jet velocity and
possibly a different density variation in the jet pulses in the southern flow
compared to the northern flow. Comparison with a semi-empirical analytical
model of bow shock emission allows us to constrain parameters such as the bow
inclination to the line of sight, the bow shock and jet velocities for each
flow. Although a few features are not reproduced by this model, it confirms the
presence of several dynamical and kinematical asymmetries between opposite
sides of the HH 212 bipolar jet. The position-velocity diagrams of both knots
exhibit complex dynamics that are broadly consistent with emission from a bow
shock and/or jet shock, which does not exclude jet rotation, although a clear
signature of jet rotation in HH 212 is missing. Alternative interpretations of
the variation of radial velocity across these knots, such as a variation in the
jet orientation, as well as for the velocity asymmetries between the flows, are
also considered. The presence of a correlation between flow velocity and
collimation in each flow is suggested.Comment: Accepted for publication in Astronomy and Astrophysics, 16 page
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