Resonance,phase front,and polarization-independence constraints of inhomogeneous fabry-perot interferometers

The major objective of this paper is to demonstrate the feasibility of imposing local resonance conditions while simultaneously controlling phase front properties upon transmission through slowly-varying Fabry-Perot type interferometers. The interaction of arbitrarily distorted incident phase fronts with double and triple-screened resonators is formulated, and appropriate design procedures are outlined. Special attention is paid to the significant effects of dielectric loading on the effective frequency band and to the cross polarization problem which arises, unavoidably, in conjunction with two-dimensional phase front distortions. The suggested design procedures are demonstrated via concrete numerical examples which are subsequently analyzed throughout a finite (20%) bandwidth.     

Optimal Interpolating Spaces Preserving Shape

In this paper we study the existence and characterization of spaces which are images of minimal-norm projections that are required to interpolate at given functionals and satisfy additional shape-preserving requirements. We will call such spaces optimal interpolating spaces preserving shape. This investigation leads to concrete solutions in classical settings and, as examples, Π_n will be determined to be such spaces with regard to certain interpolation and shape-preserving requirements on the projections. Restated, the theory of this paper gives rist to an n-dimensional Hahn–Banach extension theorem, where the minimal-norm extension is required to keep invariant a fixed cone.     

Rotations of Periodic Strings and Short Superstrings

This paper presents two simple approximation algorithms for the shortest superstring problem with approximation ratios 2 ( ≈ 2.67) and( ≈ 2.596). The framework of our improved algorithms is similar to that of previous algorithms in the sense that they construct a superstring by computing some optimal cycle covers on the distance graph of the given strings and then break and merge the cycles to finally obtain a Hamiltonian path, but we make use of new bounds on the overlap between two strings. We prove that for each periodic semiinfinite string α = a₁a₂··· of periodq, there exists an integerk, such that forany(finite) stringsof periodpwhich isinequivalentto α, the overlap betweensand therotationα[k] = a_ka_{k + 1}··· is at mostp + q. Moreover, ifp ≤ q, then the overlap betweensand α[k] is not larger than (p + q). The bounds are tight. In the previous shortest superstring algorithmsp + qwas used as the standard (tight) bound on overlap between two strings with periodspandq.     

Structural study of the Li(0.5)Na(0.5)MnFe2(PO4)3 and Li(0.75)Na(0.25)MnFe2(PO4)3 alluaudite phases and their electrochemical properties as positive electrodes in lithium batteries

The alluaudite lithiated phases Li(0.5)Na(0.5)MnFe(2)(PO(4))(3) and Li(0.75)Na(0.25)MnFe(2)(PO(4))(3) were prepared via a sol-gel synthesis, leading to powders with spongy characteristics. The Rietveld refinement of the X-ray and neutron diffraction data coupled with ab initio calculations allowed us for the first time to accurately localize the lithium ions in the alluaudite structure. Actually, the lithium ions are localized in the A(1) and A(1)' sites of the tunnel. M?ssbauer measurements showed the presence of some Fe(2+) that decreased with increasing Li content. Neutron diffraction revealed the presence of a partial Mn/Fe exchange between the two transition metal sites that shows clearly that the oxidation state of the element is fixed by the type of occupied site. The electrochemical properties of the two phases were studied as positive electrodes in lithium batteries in the 4.5-1.5 V potential window, but they exhibit smaller electrochemical reversible capacity compared with the non-lithiated NaMnFe(2)(PO(4))(3). The possibility of Na(+)/Li(+) ion deintercalation from (Na,Li)MnFe(2)(PO(4))(3) was also investigated by DFT+U calculations.     

Discovery of rare sulfated N-unsubstituted glucosamine based heparan sulfate analogs selectively activating chemokines

Achieving selective inhibition of chemokines with structurally well-defined heparan sulfate (HS) oligosaccharides can provide important insights into cancer cell migration and metastasis. However, HS is highly heterogeneous in chemical composition, which limits its therapeutic use. Here, we report the rational design and synthesis of N-unsubstituted (NU) and N-acetylated (NA) heparan sulfate tetrasaccharides that selectively inhibit structurally homologous chemokines. HS analogs were produced by divergent synthesis, where fully protected HS tetrasaccharide precursor was subjected to selective deprotection and regioselectively O-sulfated, and O-phosphorylated to obtain 13 novel HS tetrasaccharides. HS microarray and SPR analysis with a wide range of chemokines revealed the structural significance of sulfation patterns and NU domain in chemokine activities for the first time. Particularly, HT-3,6S-NH revealed selective recognition by CCL2 chemokine. Further systematic interrogation of the role of HT-3,6S-NH in cancer demonstrated an effective blockade of CCL2 and its receptor CCR2 interactions, thereby impairing cancer cell proliferation, migration and invasion, a step towards designing novel drug molecules.     

On Measuring the Efficiency of Kernel Operators in L p (R d )

It is well known that it is possible to enhance the approximation properties of a kernel operator by increasing its support size. There is an obvious tradeoff between higher approximation order of a kernel and the complexity of algorithms that employ it. A question is then asked: how do we compare the efficiency of kernels with comparable support size? We follow Blu and Unser and choose as a measure of the efficiency of the kernels the first leading constant in a certain error expansion. We use time domain methods to treat the case of globally supported kernels in L _p (R ^d), 1≤p≤∞.

     

Liquid chromatography-tandem mass spectrometry determination for multiclass pesticides from insect samples by microwave-assisted solvent extraction followed by a salt-out effect and micro-dispersion purification

The effects of phyto-pharmaceutic compounds (PPCs), such as neonicotinoids, on wildlife reproduction and survival are a rising concern. Yet, understanding the biological consequences of PPC use is particularly complex given the large diversity of PPCs and their derivatives to which wildlife can be exposed. Here, we present a simple and sensitive method for the simultaneous detection and quantification of multiclass PPCs (54 molecules) in single insect boluses (<0.05 g dry mass) by ultra-high pressure liquid chromatography coupled to a tandem mass spectrometer (LC-MS/MS). A key part of this new method is the use of a two-step extraction method combining (i) the high efficiency of a microwave-assisted solvent extraction (MAE) for extracting analytes that might be tightly bound to environmental matrices and (ii) the versatility of a salt-out effect adapted from the QuEChERS methodology allowing the extraction and purification of a wide array of analytes. This microwave-assisted salt-out extraction (MASOE) approach was compared to classical extraction methods including matrix solid phase dispersion (MSPD), microwave-assisted extraction (MAE), and the QuEChERS method. Average recoveries for 54 analytes ranged from 49% to 106%, (relative standard deviations <22%). The limits of detection (LODs) and quantification (LOQs) were in the ranges of 0.10–3.00 ng g⁻¹ and 0.40–7.00 ng g⁻¹, respectively. We applied this method to analyse 881 insect boluses collected from Tree Swallow (Tachycineta bicolour) nestlings along an agricultural intensification gradient in southern Québec (Canada). We detected 25 PPCs out of the 54 considered. We detected at least one PPC in 30% of samples and were able to quantify at least one of them in 17% of samples. Our study shows that the MASOE method should prove to be a powerful tool for studying the fate and impacts of PPCs on wildlife.