Probing the Ultimate Limits of Plasmonic Enhancement Ciracì, C.; Hill, R. T.; Mock, J. J. ...
Science (American Association for the Advancement of Science),
08/2012, Letnik:
337, Številka:
6098
Journal Article
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Metals support surface plasmons at optical wavelengths and have the ability to localize light to subwavelength regions. The field enhancements that occur in these regions set the ultimate limitations ...on a wide range of nonlinear and quantum optical phenomena. We found that the dominant limiting factor is not the resistive loss of the metal, but rather the intrinsic nonlocality of its dielectric response. A semiclassical model of the electronic response of a metal places strict bounds on the ultimate field enhancement. To demonstrate the accuracy of this model, we studied optical scattering from gold nanoparticles spaced a few angstroms from a gold film. The bounds derived from the models and experiments impose limitations on all nanophotonic systems.
Epithelial glucose transport is accomplished by Na+‐glucose co‐transporters, SGLT1 and SGLT2. In the intestine, uptake of dietary glucose is for its majority mediated by SGLT1, and humans with ...mutations in the SGLT1 gene show glucose/galactose malabsorption. In the kidney, both transporters, SGLT1 and SGLT2, are expressed and recent studies identified that SGLT2 mediates up to 97% of glucose reabsorption. Humans with mutations in the SGLT2 gene show familial renal glucosuria. In the last three decades, significant progress was made in understanding the physiology of these transporters and their potential as therapeutic targets. Based on the structure of phlorizin, a natural compound acting as a SGLT1/2 inhibitor, initially several SGLT2, and later SGLT1 and dual SGLT1/2 inhibitors have been developed. Interestingly, SGLT2 knockout or treatment with SGLT2 selective inhibitors only causes a fractional glucose excretion in the magnitude of ∼60%, an effect mediated by up‐regulation of renal SGLT1. Based on these findings the hypothesis was brought forward that dual SGLT1/2 inhibition might further improve glycaemic control via targeting two distinct organs that express SGLT1: the intestine and the kidney. Of note, SGLT1/2 double knockout mice completely lack renal glucose reabsorption. This review will address the rationale for the development of SGLT1 and dual SGLT1/2 inhibitors and potential benefits compared to sole SGLT2 inhibition.
The Solar Orbiter magnetometer Horbury, T. S.; O’Brien, H.; Carrasco Blazquez, I. ...
Astronomy and astrophysics (Berlin),
10/2020, Letnik:
642
Journal Article
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The magnetometer instrument on the Solar Orbiter mission is designed to measure the magnetic field local to the spacecraft continuously for the entire mission duration. The need to characterise not ...only the background magnetic field but also its variations on scales from far above to well below the proton gyroscale result in challenging requirements on stability, precision, and noise, as well as magnetic and operational limitations on both the spacecraft and other instruments. The challenging vibration and thermal environment has led to significant development of the mechanical sensor design. The overall instrument design, performance, data products, and operational strategy are described.
A set of four finite energy QCD sum rules are used to determine the magnetic field dependence of the sum of the up- and down-quark masses of QCD, (mu+md), the pion decay constant fπ, the pion mass ...mπ, the gluon condensate, ⟨αsG2⟩, and the squared energy threshold for the onset of perturbative QCD, s0, related to the Polyakov loop of lattice QCD. As a first input we take the magnetic evolution of the chiral quark condensate from lattice QCD and/or Nambu–Jona-Lasinio results. As a second input we take three different possible conditions concerning the quark and pion masses.
Primary ventral hernia (PVH) and incisional hernia (IH) repair using a mesh appears to reduce hernia recurrence. However, are the benefits of mesh offset in part by mesh-related complications? The ...aim of this study was to compare placement of a mesh versus simple suture for recurrence and postoperative complications in the repair of PVH or IH.
Five databases were searched for randomized controlled trials (RCTs). The study population was patients with a PVH or IH undergoing hernia repair. Intervention was placement of a nonabsorbable synthetic mesh, regardless of mesh location, surgical technique, hernia characteristics or surgical setting compared to primary suture. Primary outcome was the incidence of hernia recurrence. Secondary outcomes were wound infection, hematoma, seroma, postsurgical pain, duration of operation, and quality of life. A random-effects meta-analysis with trial sequential analysis (TSA) was used.
10 RCTs with a total of 1270 patients were included. A significant reduction of the incidence of PVH or IH recurrence using a mesh for repair (risk ratio RR 0.39, 95% CI 0.27-0.55; P < 0.00001; I2 = 20%) was observed. TSA for recurrence, the accrued information size (1270) was 312% of the estimated required information size (RIS). Subgroup analysis for PVH and IH confirms reduction of recurrence after using a mesh in both groups. Overall postoperative complications did not show statistically significant differences between the mesh and surgical suture groups (RR 1.31, 95% CI 0.94-1.84; P = 0.12; I2 = 27%) but the accrued information size was only 22.4% of RIS and by subgroups complications were only related with IH repair.
Evidence for the efficacy of repair of PVH or IH using a nonabsorbable synthetic mesh in terms of recurrence was found to be robust. Evidence for complications remains inconclusive.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The sodium/proton exchanger isoform 3 (NHE3) is expressed in the intestine and the kidney, where it contributes to hydrogen secretion and sodium (re)absorption. The roles of this transporter have ...been studied by the use of the respective knockout mice and by using pharmacological inhibitors. Whole-body NHE3 knockout mice suffer from a high mortality rate (with only ∼30% of mice surviving into adulthood), and based on the expression of NHE3 in both intestine and kidney, some conclusions that were originally derived were based on this rather complex phenotype. In the last decade, more refined models have been developed that added temporal and spatial control of NHE3 expression. For example, novel mouse models have been developed with a knockout of NHE3 in intestinal epithelial cells, tubule/collecting duct of the kidney, proximal tubule of the kidney, and thick ascending limb of the kidney. These refined models have significantly contributed to our understanding of the role of NHE3 in a tissue/cell type-specific manner. In addition, tenapanor was developed, which is a non-absorbable, intestine-specific NHE3 inhibitor. In rat and human studies, tenapanor lowered intestinal P
i
uptake and was effective in lowering plasma P
i
levels in patients on hemodialysis. Of note, diarrhea is seen as a side effect of tenapanor (with its indication for the treatment of constipation) and in intestine-specific NHE3 knockout mice; however, effects on plasma P
i
were not supported by this mouse model which showed enhanced and not reduced intestinal P
i
uptake. Further studies indicated that the gut microbiome in mice lacking intestinal NHE3 resembles an intestinal environment favoring the competitive advantage of inflammophilic over anti-inflammatory species, something similar seen in patients with inflammatory bowel disease. This review will highlight recent developments and summarize newly gained insight from these refined models.
Standard practice in reclamation of mine tailings is the emplacement of a 15 to 90cm soil/gravel/rock cap which is then hydro-seeded. In this study we investigate compost-assisted direct planting ...phytostabilization technology as an alternative to standard cap and plant practices. In phytostabilization the goal is to establish a vegetative cap using native plants that stabilize metals in the root zone with little to no shoot accumulation. The study site is a barren 62-hectare tailings pile characterized by extremely acidic pH as well as lead, arsenic, and zinc each exceeding 2000mgkg−1. The study objective is to evaluate whether successful greenhouse phytostabilization results are scalable to the field. In May 2010, a 0.27ha study area was established on the Iron King Mine and Humboldt Smelter Superfund (IKMHSS) site with six irrigated treatments; tailings amended with 10, 15, or 20% (w/w) compost seeded with a mix of native plants (buffalo grass, arizona fescue, quailbush, mountain mahogany, mesquite, and catclaw acacia) and controls including composted (15 and 20%) unseeded treatments and an uncomposted unseeded treatment. Canopy cover ranging from 21 to 61% developed after 41 months in the compost-amended planted treatments, a canopy cover similar to that found in the surrounding region. No plants grew on unamended tailings. Neutrophilic heterotrophic bacterial counts were 1.5 to 4 orders of magnitude higher after 41months in planted versus unamended control plots. Shoot tissue accumulation of various metal(loids) was at or below Domestic Animal Toxicity Limits, with some plant specific exceptions in treatments receiving less compost. Parameters including % canopy cover, neutrophilic heterotrophic bacteria counts, and shoot uptake of metal(loids) are promising criteria to use in evaluating reclamation success. In summary, compost amendment and seeding, guided by preliminary greenhouse studies, allowed plant establishment and sustained growth over 4years demonstrating feasibility for this phytostabilization technology.
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•Cap and plant is the current costly standard for mine tailings reclamation•We assessed direct planting for remediation of acidic metalliferous mine tailings•60-day greenhouse pot studies translated successfully to this 41-month field trial•A single compost application supported plant establishment and soil development•Direct planting with compost is a viable alternative for treatment of mine tailings
The extragalactic background light (EBL) is of fundamental importance both for understanding the entire process of galaxy evolution and for γ-ray astronomy, but the overall spectrum of the EBL ...between 0.1 and 1000 μm has never been determined directly from galaxy spectral energy distribution (SED) observations over a wide redshift range. The evolving, overall spectrum of the EBL is derived here utilizing a novel method based on observations only. This is achieved from the observed evolution of the rest-frame K-band galaxy luminosity function up to redshift 4, combined with a determination of galaxy-SED-type fractions. These are based on fitting Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) templates to a multiwavelength sample of about 6000 galaxies in the redshift range from 0.2 to 1 from the All-wavelength Extended Groth Strip International Survey (AEGIS). The changing fractions of quiescent galaxies, star-forming galaxies, starburst galaxies and active galactic nucleus (AGN) galaxies in that redshift range are estimated, and two alternative extrapolations of SED types to higher redshifts are considered. This allows calculation of the evolution of the luminosity densities from the ultraviolet (UV) to the infrared (IR), the evolving star formation rate density of the Universe, the evolving contribution to the bolometric EBL from the different galaxy populations including AGN galaxies and the buildup of the EBL. Our EBL calculations are compared with those from a semi-analytic model, another observationally based model and observational data. The EBL uncertainties in our modelling based directly on the data are quantified, and their consequences for attenuation of very-high-energy γ-rays due to pair production on the EBL are discussed. It is concluded that the EBL is well constrained from the UV to the mid-IR, but independent efforts from IR and γ-ray astronomy are needed in order to reduce the uncertainties in the far-IR.
Metamaterials are artificial materials with subwavelength structure that enable the translation of magnetic and electric responses into spectral regions not accessible through naturally occurring ...materials. Here, we report direct measurements of the propagation and confinement of terahertz electromagnetic surface modes tightly bound to flat plasmonic metamaterials that consist of metal surfaces decorated with two-dimensional arrays of subwavelength-periodicity pits. These modes are surface plasmon polaritons with an effective plasma frequency controlled entirely by the surface geometry. The mode spectrum and penetration depth into air demonstrate strong wavelength-scale energy confinement to the surface below the electromagnetic band edge; this is in stark contrast to the very weak confinement found at flat metal surfaces in this spectral regime. The results are in good agreement with analytical and numerical models of surface plasmon polaritons propagating on structured perfect-conductor surfaces, and imply that plasmonic metamaterials could help miniaturize optical components or lead to improved chemical or biochemical sensors.
We study the one-loop gluon polarization tensor at zero and finite temperature in the presence of a magnetic field, to extract the thermomagnetic evolution of the strong coupling αs. We analyze four ...distinct regimes, to wit, the small and large field cases, both at zero and at high temperature. From a renormalization group analysis, we show that at zero temperature, either for small or large magnetic fields, and for a fixed transferred momentum Q2, αs grows with the field strength with respect to its vacuum value. However, at high temperature and also for a fixed value of Q2, we find two different cases. When the magnetic field is even larger than the squared temperature, αs also grows with the field strength. On the contrary, when the squared temperature is larger than the magnetic field, a turnover behavior occurs, and αs decreases with the field strength. This thermomagnetic behavior of αs can help explain the inverse magnetic catalysis phenomenon found by lattice QCD calculations.
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