Unusual Spectrum Research Articles

Carcinoma of the Tongue in Renal Transplant Recipients: An Unusual Spectrum of De novo Malignancy at a Tertiary Care Center in India Over a Period of 26 Years.

Renal transplant recipients are at a higher risk of malignancy. We report our experience and the critical differences in the presentation of malignancy in kidney transplant patients performed at our tertiary care center and followed up over the period of 1990–2015. A total of 338 live donor transplants performed in 332 patients were analyzed. Induction immunosuppression was used in 22 cases with interleukin-2 (IL-2) receptor antibody. Overall 299 patients were continued on calcineurin inhibitor (CNI)-based triple drug immunosuppression, 33 were off CNI with 13 of them receiving sirolimus additionally. A total of 16 malignancies including post transplant lymphoproliferative disease (5), oral cancer (5), lung cancer (2), hepatobiliary cancer (2), colon cancer (1), and skin cancer (1) were diagnosed in 15 patients. Over the 26-year follow up, 138 patients died of whom 12 died due to cancer. Cancer occurred in 4.7% of patients but accounted for 9.4% of deaths. Oral cancer occurred after a significantly longer latency of over 10 years (212 vs. 94 months, P = 0.00652). Despite the longer latency, oral cancer patients were younger at diagnosis (44.0 vs. 52 years, P = 0.01016) and had better outcome (Fisher's exact test, P = 0.0275). This was despite a longer overall follow-up for the oral cancer patients, reflecting the better outcome for these patients (24 vs. 4 months, P = 0.0278). This might be the result of relatively early diagnosis of oral cancers.

Drosophila melanogaster rhodopsin Rh7 is a UV-to-visible light sensor with an extraordinarily broad absorption spectrum

The genome of Drosophila melanogaster contains seven rhodopsin genes. Rh1-6 proteins are known to have respective absorption spectra and function as visual pigments in ocelli and compound eyes. In contrast, Rh7 protein was recently revealed to function as a circadian photoreceptor in the brain. However, its molecular properties have not been characterized yet. Here we successfully prepared a recombinant protein of Drosophila Rh7 in mammalian cultured cells. Drosophila Rh7 bound both 11-cis-retinal and 11-cis-3-hydroxyretinal to form photo-pigments which can absorb UV light. Irradiation with UV light caused formation of a visible-light absorbing metarhodopsin that activated Gq-type of G protein. This state could be photoconverted back to the original state and, thus Rh7 is a Gq-coupled bistable pigment. Interestingly, Rh7 (lambda max = 350 nm) exhibited an unusual broad spectrum with a longer wavelength tail reaching 500 nm, whose shape is like a composite of spectra of two pigments. In contrast, replacement of lysine at position 90 with glutamic acid caused the formation of a normal-shaped absorption spectrum with maximum at 450 nm. Therefore, Rh7 is a unique photo-sensor that can cover a wide wavelength region by a single pigment to contribute to non-visual photoreception.

A Parameter Study for Modeling Mg ii h and k Emission during Solar Flares

Abstract Solar flares show highly unusual spectra in which the thermodynamic conditions of the solar atmosphere are encoded. Current models are unable to fully reproduce the spectroscopic flare observations, especially the single-peaked spectral profiles of the Mg ii h and k lines. We aim to understand the formation of the chromospheric and optically thick Mg ii h and k lines in flares through radiative transfer calculations. We take a flare atmosphere obtained from a simulation with the radiative hydrodynamic code RADYN as input for a radiative transfer modeling with the RH code. By iteratively changing this model atmosphere and varying thermodynamic parameters such as temperature, electron density, and velocity, we study their effects on the emergent intensity spectra. We reproduce the typical single-peaked Mg ii h and k flare spectral shape and approximate the intensity ratios to the subordinate Mg ii lines by increasing either densities, temperatures, or velocities at the line core formation height range. Additionally, by combining unresolved upflows and downflows up to ∼250 km s−1 within one resolution element, we reproduce the widely broadened line wings. While we cannot unambiguously determine which mechanism dominates in flares, future modeling efforts should investigate unresolved components, additional heat dissipation, larger velocities, and higher densities and combine the analysis of multiple spectral lines.

Communication: Nonadditive dielectric susceptibility spectra of associating liquids.

Highly unusual linear-response spectra involving contributions from hydrogen-bonded supramolecular processes and from structural relaxations are found in 4-methyl-3-heptanol mixed with 2-ethyl-1-hexylbromide. Although the mean time scales of the underlying relaxations are separated by more than 3 decades, the overall spectra cannot be decomposed into a sum of these processes. This finding challenges the ubiquitous practice of disentangling susceptibility spectra of Debye liquids by adding suitable subspectra. The spectral shape of the studied viscous mixtures is excellently described using the Williams ansatz, here a necessary approach and not as previously considered merely an alternative to additive analyses.

Near-unity absorption in a graphene-embedded defective photonic crystals array

Near-unity absorption is achieved theoretically at the terahertz frequencies by the graphene-based absorber under the condition of approaching critical coupling. The designed structure is composed of a defective photonic crystal array equal to the multilayer subwavelength grating, which possesses simultaneously the properties of photonic crystal and subwavelength grating so that both FP resonance and Fano resonance are excited. To simulate the structure accurately, rigorous coupled-wave analysis is employed. It is found that the dip can be introduced into the high absorption spectrum by the coupling of two resonances, which is realized by tuning the chemical potential of graphene, the geometry and equivalent thickness of grating as well as the angle of incident wave. The unusual absorption spectra are believed to be useful in the detection and modulation of terahertz waves.

Spatial detection of outlier loci with Moran eigenvector maps

The spatial signature of microevolutionary processes structuring genetic variation may play an important role in the detection of loci under selection. However, the spatial location of samples has not yet been used to quantify this. Here, we present a new two-step method of spatial outlier detection at the individual and deme levels using the power spectrum of Moran eigenvector maps (MEM). The MEM power spectrum quantifies how the variation in a variable, such as the frequency of an allele at a SNP locus, is distributed across a range of spatial scales defined by MEM spatial eigenvectors. The first step (Moran spectral outlier detection: MSOD) uses genetic and spatial information to identify outlier loci by their unusual power spectrum. The second step uses Moran spectral randomization (MSR) to test the association between outlier loci and environmental predictors, accounting for spatial autocorrelation. Using simulated data from two published papers, we tested this two-step method in different scenarios of landscape configuration, selection strength, dispersal capacity and sampling design. Under scenarios that included spatial structure, MSOD alone was sufficient to detect outlier loci at the individual and deme levels without the need for incorporating environmental predictors. Follow-up with MSR generally reduced (already low) false-positive rates, though in some cases led to a reduction in power. The results were surprisingly robust to differences in sample size and sampling design. Our method represents a new tool for detecting potential loci under selection with individual-based and population-based sampling by leveraging spatial information that has hitherto been neglected.

Eumelanin broadband absorption develops from aggregation-modulated chromophore interactions under structural and redox control

Eumelanins, the chief photoprotective pigments in man and mammals, owe their black color to an unusual broadband absorption spectrum whose origin is still a conundrum. Excitonic effects from the interplay of geometric order and disorder in 5,6-dihydroxyindole (DHI)-based oligomeric/polymeric structures play a central role, however the contributions of structural (scaffold-controlled) and redox (π-electron-controlled) disorder have remained uncharted. Herein, we report an integrated experimental-theoretical entry to eumelanin chromophore dynamics based on poly(vinyl alcohol)-controlled polymerization of a large set of 5,6-dihydroxyindoles and related dimers. The results a) uncover the impact of the structural scaffold on eumelanin optical properties, disproving the widespread assumption of a universal monotonic chromophore; b) delineate eumelanin chromophore buildup as a three-step dynamic process involving the rapid generation of oxidized oligomers, termed melanochromes (phase I), followed by a slow oxidant-independent band broadening (phase II) leading eventually to scattering (phase III); c) point to a slow reorganization-stabilization of melanochromes via intermolecular redox interactions as the main determinant of visible broadband absorption.

Unprecedented tetranuclear complexes with "weighing balance shaped" topology: single crystal structures, unusual EPR spectra, magnetic properties and antioxidant activity.

Using the 2-hydroxy-N'-[(E)-phenyl(pyridin-2-yl)methylidene]benzohydrazide ligand and dicarboxylate anions (succinate and malonate), two new copper(ii) complexes of formula [Cu4(μ-L)4(μ-CH2(COO)2)(H2O)3](NO3)2·4H2O (1) and [Cu4(μ-L)4(μ-CH2-CH2(COO)2)(H2O)](NO3)2] (2) have been synthesized and characterized by single crystal X-ray diffraction. Complexes 1 and 2 contain a dicarboxylate bridged tetranuclear Cu(ii) cationic unit with "weighing balance shaped" topology. These compounds have also been studied by variable temperature magnetic susceptibility measurements, X-band EPR spectroscopy and electrochemistry. The unprecedented tetranuclear copper complexes 1 and 2 exhibit antiferromagnetic interactions between adjacent copper(ii) centers with magnetic exchange coupling constants (J) of J1 = -6.8 cm-1, J2 = -20.6 cm-1 and g = 2.03 for 1 and J1 = -3.1 cm-1, J2 = -13.9 cm-1 and g = 2.02 for 2. The goal for our research work is to understand the factors that govern the stability of the Cu-O(-O-C-O-) bond towards reactive oxygen species (ROS) in Cu-containing mimics utilizing a systematic approach. The antioxidant superoxide dismutase measurements indicate that these complexes behave as superoxide dismutase mimics.

ABUNDANCE DERIVATIONS FOR THE SECONDARY STARS IN CATACLYSMIC VARIABLES FROM NEAR-INFRARED SPECTROSCOPY

ABSTRACT We derive metallicities for 41 cataclysmic variables (CVs) from near-infrared spectroscopy. We use synthetic spectra that cover the 0.8 μm ≤ λ ≤ 2.5 μm bandpass to ascertain the value of [Fe/H] for CVs with K-type donors, while also deriving abundances for other elements. Using calibrations for determining [Fe/H] from the K-band spectra of M-dwarfs, we derive more precise values for for the secondaries in the shortest period CVs, and examine whether they have carbon deficits. In general, the donor stars in CVs have subsolar metallicities. We confirm carbon deficits for a large number of systems. CVs with orbital periods >5 hr are most likely to have unusual abundances. We identify four CVs with CO emission. We use phase-resolved spectra to ascertain the mass and radius of the donor in U Gem. The secondary star in U Gem appears to have a lower apparent gravity than a main sequence star of its spectral type. Applying this result to other CVs, we find that the later-than-expected spectral types observed for many CV donors are mostly an effect of inclination. All of the magnetic CVs, except the low accretion rate polar MQ Dra, have donors with subsolar metallicities. We find that two systems with unusual spectra, EI Psc and QZ Ser, have large excesses of sodium and extreme deficits of carbon. Synthetic spectra that have a reduced abundance of hydrogen are best able to explain the spectra of these two objects.

Optical spectra of ultracool dwarfs with the Southern African Large Telescope

New spectra of 81 ultracool dwarfs (spectral types M7 and later) are discussed. Spectral classifications of 49 objects are available in the literature, while 32 objects are newly classified. The known spectral types were used to test an automated classification scheme, which relies primarily on template fitting, supplemented by matching of spectral indices calibrated against the template spectra. An attempt was made to quantify the uncertainty in the spectral types, which is generally better than two subclasses. Objects for which spectral types differ by more than one subclass from the literature classifications are discussed individually. Discrepancies between automated classifications based on respectively template fitting and spectral index matching, may be useful for flagging objects with unusual spectra. Aside from the 32 first-time classifications, alternative classifications are presented for 32 previously classified dwarfs. Very large (equivalent width greater than 130 \AA) H$\alpha$ flares are reported for the known ultracool dwarf binary 2MASS J15200224$-$4422419; curiously, the object does not appear to have quiescent emission lines. Non-zero equivalent width measurements are listed for a further 29 objects.

On the unusual IR spectra of the pentachlorophenol – Trimethylamine complex in low temperature matrices

Usually the stretching vibration of the A-H group in hydrogen-bonded complexes gives an intense, broad absorption in the IR spectrum. However in a few complexes it has proved difficult to detect this absorption in low temperature matrices. In this work the Ratajczak-Yaremko vibrational model of the hydrogen bond has been applied to simulate the IR spectrum obtained for one such complex: the pentachlorophenol-trimethylamine, PCP-TMA, hydrogen bonded complex isolated in an argon matrix. Quantum chemical calculations have also been carried out to gain further insight into this complex.

Studies of the spectroscopic properties of lead–gallium oxyfluoride (LGOF) glasses and glass–ceramics activated by Pr3+ ions

Lead–gallium glasses, due to the absence of typical glass-forming components, are characterized by an increased tendency to crystallization. Despite this, they are interesting materials due to a shift of IR absorption edge up to 6 and 7μm. The paper studies thermal stability, the UV–vis and IR transmission and luminescence spectroscopy of the lead–gallium glass. The base lead–gallium glass 0.65PbO·0.20Ga2O3·0.15SiO2 was modified by the addition of 2mol% BaF2 and 1mol% Pr6O11. DTA/DSC data showed that the glasses are characterized by the multi-stage crystallization. Unusual luminescence excitation spectra confronted with emission spectra, measured for glass (as made) and glass ceramic (annealed) phase, have been tentatively interpreted by means of single configuration coordinate diagrams. It seems that in both phases the praseodymium ions occur in two sites: lower- and higher-field environment. We propose the fluorine-affected sites as the lower field sites and purely oxide sites as the higher field sites. It seems likely that O–Pr–O sites can be treated as the higher filed sites whereas the fluorine affected sites, i.e. F–Pr–F and/or O–Pr–F sites, as the lower field sites.

Primary Cardiac Tumors in Infants and Children: Surgical Strategy and Long-Term Outcome

Primary cardiac tumors in infants and children are extremely rare; hence, there is very little literature available, and most knowledge is based on collections of case reports. This report is a comprehensive review of our 26-year experience with primary cardiac tumors in children with emphasis on surgical indications, strategies, and long-term outcome. Between 1986 and 2012, 47 children (mean age 5.9 ± 2.4 months; range, 1 day to 17 years) underwent either subtotal or total resection of cardiac tumors (rhabdomyoma, 13; fibroma, 12; teratoma, 9; myxoma, 8; hemangioma, 2; rhabdomyosarcoma, 1; non-Hodgkin's lymphoma, 1; lymphangioma, 1). The majority were diagnosed by echocardiography (n= 33). Clinical patterns were varied: 40 had an atypical heart murmur and 6 were asymptomatic. Outflow tract obstruction of more than 30 mm Hg was present in 11 children. Three patients had abnormal coronary arteries secondary to pressure from tumor bulk. Indications of resection were hemodynamic/respiratory compromise, severe arrhythmia, and asignificant embolization risk. Strategy of resection varied according to location and hemodynamic status without damage to adjacent structures. Morbidity included bleeding in a patient and a transient low output state in another. A 5-month-old infant with left ventricular fibroma underwent left ventricular assist device implantation secondary to failure from weaning off cardiopulmonary bypass, and she eventually underwent heart transplantation 17 days later. Early mortality (n= 2, 4.2%) included a 5-month-old infant who underwent complete resection of rhabdomyoma located in the left ventricle, with concomitant pulmonary valve replacement; unfortunately, he underwent left ventricular assist device implantation for postoperative heart failure and died on the 13th postoperative day. An8-month-old child with 3 cm× 4 cm fibroma obstructing the right ventricular outflow tract compressing the right coronary artery died of severe right-side heart failure on the 13th postoperative day. One late death (2.1%) occurred; a 16-year-old with non-Hodgkin's lymphoma died 7 months after the surgery. Mean duration of follow-up is 11.6 ± 3.5 years. All survivors (93.4%) are well, free of tumor-related symptoms and tumor recurrence/progression, even when resection was incomplete. This study illustrates that although primary cardiac tumors in infants and children have a wide and unusual spectrum of clinical presentation, an individualized approach to tumor resection allows restoration of an adequate hemodynamic function and satisfactory long-term, tumor-free outcome.

Regular cuboid diamonds from placers on the northeastern Siberian platform

Alluvial placers of the northeastern Siberian Platform are characterized by a specific diamond population: regular cuboids, forming a continuous color series from yellowish-green to yellow and dark orange. This is the first comprehensive study of a large number of cuboid diamonds focusing on their morphology, N content and aggregation state, photoluminescence, C isotopic composition and inclusions.The cuboids are cubic (i.e. nearly flat faced) to subrounded crystals; most of them are resorbed. The cathodolominescence images and the birefringence patterns show that many cuboid diamonds record deformation. The cuboid diamonds are characterized by unusual FTIR spectra with the presence of C- (single nitrogen atom) and A- (pair of neighbour nitrogen atoms) centers, and two centers of unknown origin, termed X and Y. The presence of single substitutional nitrogen defects (C centers) in all cuboid diamonds testifies either storage in the mantle at relatively cool conditions or formation just prior to eruption of their host kimberlites. The studied diamonds are also characterized by the presence of specific set of luminescence centers: N3, H3, S1, NVo and NV−, some of which are suggested to have formed during deformation subsequent to diamond growth. The cuboid diamonds show a wide range of carbon isotope compositions from mantle-like values towards strongly 13C depleted compositions (−6.1 to −20.2‰ δ13C). Combined with the finding of an eclogitic sulfide inclusion, the light carbon isotope compositions link the formation of the studied cuboids to deeply subducted basic protoliths, i.e. former oceanic crust.

Unusual non-fluorescent broad spectrum siderophore activity (SID EGYII) by Pseudomonas aeruginosa strain EGYII DSM 101801 and a new insight towards simple siderophore bioassay.

Present study highlights an unusual non-fluorescent hydroxamate broad spectrum siderophore (SID EGYII) activity from Pseudomonas aeruginosa strain EGYII DSM 101801, a soil bacterial isolate, along with simple low cost effective siderophore bioassay. Detection of SID EGYII activity qualitatively was proved by masking this activity against Erwinia amylovora strain EGY1 DSM 101800, an indicator strain, in well-cut diffusion assay containing 100 µM FeCl3. SID EGYII activity was expressed quantitatively as arbitrary units [Siderophore arbitrary units (SAU)] 380 SAU/mL against E. amylovora strain EGY1 DSM 101800. Maximal SID EGYII activity was achieved upon growing P. aeruginosa strain EGYII DSM 101801 in PYB broth at 180 rpm for 24 h. SID EGYII displayed a broad spectrum antimicrobial activity against some human pathogens (i.e., Gram-positive bacteria, Gram-negative bacteria and yeasts) and a fireblight plant pathogen. Interestingly, transformants of Escherichia coli JM109 (DE3)pSID/EGYII harboring P. aeruginosa strain EGYII DSM 101801 plasmid demonstrated a perceivable antimicrobial activity against E. amylovora strain EGY1 DSM 101800. The broad spectrum antimicrobial activity of the unusual non-fluorescent SID EGYII would underpin its high potential in targeting bacterial pathogens posing probable threats to human health and agricultural economy. The present simple low cost effective bioassay is a new insight towards an alternative to the expensive cumbersome siderophore Chrome Azurol S assay.

THE FIRST BROWN DWARF/PLANETARY-MASS OBJECT IN THE 32 ORIONIS GROUP*

ABSTRACT The 32 Orionis group is a co-moving group of roughly 20 young (24 Myr) M3-B5 stars 100 pc from the Sun. Here we report the discovery of its first substellar member, WISE J052857.69+090104.2. This source was previously reported to be an M giant star based on its unusual near-infrared spectrum and lack of measureable proper motion. We re-analyze previous data and new moderate-resolution spectroscopy from Magellan/Folded-port InfraRed Echellette to demonstrate that this source is a young near-infrared L1 brown dwarf with very low surface gravity features. Spectral model fits indicate T eff = 1880 − 70 + 150 ?> K and log g ?> = 3.8 − 0.2 + 0.2 ?> , consistent with a 15–22 Myr object with a mass near the deuterium-burning limit. Its sky position, estimated distance, kinematics (both proper motion and radial velocity), and spectral characteristics are all consistent with membership in 32 Orionis, and its temperature and age imply a mass (M = 14 − 3 + 4 ?> M J ) that straddles the brown dwarf/planetary-mass object boundary. The source has a somewhat red J − W 2 ?> color compared to other L1 dwarfs, but this is likely a low-gravity-related temperature offset; we find no evidence of significant excess reddening from a disk or cool companion in the 3–5 μm waveband.

Vacancies in Kitaev quantum spin liquids on the three-dimensional hyperhoneycomb lattice

We study the effect of adding disorder to the exactly solvable Kitaev model on the hyper-honeycomb lattice, which hosts both gapped and gapless spin liquid phases with an emergent $\mathbb{Z}_2$ gauge field. The latter has an unusual gapless spectrum of Majorana fermion excitations, with a co-dimension-two Fermi ring. We thus address the question of the interplay of topological physics and disorder by considering the properties of isolated single and pair of vacancies. We show that near the vacancies, the local magnetic response to a field $h_z$ is parametrically enhanced in comparison to the pristine bulk. Unlike the previously studied case of the 2D honeycomb Kitaev model, the vacancies do not bind a flux of the $\mathbb{Z}_2$ gauge field. In the gapped phase, an isolated vacancy gives rise to effectively free spin-half moments with a non-universal coupling to an external field. In the gapless phase, the low-field magnetization is suppressed parametrically, to $(-\ln h_z)^{-1/2}$ because of interactions with the surrounding spin-liquid. We also show that a pair of vacancies is subject to a sublattice-dependent interaction on account of coupling through the bulk spin liquid, which is spatially anisotropic even when all Kitaev couplings have equal strength. This coupling is thus exponentially suppressed with distance in the gapped phase. In the gapless phase, two vacancies on the same (opposite) sublattice exhibit an enhanced (suppressed) low-field response, amounting to an effectively (anti-)ferromagnetic interaction.

Doping dependence of unusual electron spectrum in hole-doped cuprate superconductors

Based on the renormalized Hubbard model, the doping dependence of electron spectrum in cuprate superconductors is discussed within the self-consistent mean field theory. It is shown that the renormalization factor [Formula: see text] (then the quasiparticle coherent weight) increases almost linearly with the doping and plays an important role in the unconventional superconductivity for cuprate superconductors. It suppresses the magnitude of the quasiparticle peak in the electron spectrum, especially in underdoped region. By calculation of the energy and doping dependence of the electron spectral function, the main features of the electron spectrum in cuprate superconductors can be described qualitatively. In particular, with the increasing doping concentration, the position of the quasiparticle peak moves to the Fermi energy and the magnitude of the quasiparticle peak increases monotonically. Our results also show that the superconducting order parameter is determined by product of the renormalization factor and the pseudogap.

Long-lived binary tunneling spectrum in the quantum Hall Tomonaga-Luttinger liquid

The existence of long-lived non-equilibrium states without showing thermalization, which has previously been demonstrated in time evolution of ultracold atoms, suggests the possibility of their spatial analogue in transport behavior of interacting electrons in solid-state systems. Here we report long-lived non-equilibrium states in one-dimensional edge channels in the integer quantum Hall regime. An indirect heating scheme in a counterpropagating configuration is employed to generate a non-trivial binary spectrum consisting of high- and low-temperature components. This unusual spectrum is sustained even after travelling 5 - 10 {\mu}m, much longer than the length for electronic relaxation (about 0.1 {\mu}m), without showing significant thermalization. This observation is consistent with the integrable model of Tomonaga-Luttinger liquid. The long-lived spectrum implies that the system is well described by non-interacting plasmons, which are attractive for carrying information for a long distance.

Universality of vibrational spectra of globular proteins

It is shown that the density of modes of the vibrational spectrum of globular proteins is universal, i.e. regardless of the protein in question, it closely follows one universal curve. The present study, including 135 proteins analyzed with a full atomic empirical potential (CHARMM22) and using the full complement of all atoms Cartesian degrees of freedom, goes far beyond previous claims of universality, confirming that universality holds even in the frequency range that is well above 100 cm−1 (300–4000 cm−1), where peaks and turns in the density of states are faithfully reproduced from one protein to the next. We also characterize fluctuations of the spectral density from the average, paving the way to a meaningful discussion of rare, unusual spectra and the structural reasons for the deviations in such ‘outlier’ proteins. Since the method used for the derivation of the vibrational modes (potential energy formulation, set of degrees of freedom employed, etc) has a dramatic effect on the spectral density, another significant implication of our findings is that the universality can provide an exquisite tool for assessing and improving the quality of potential functions and the quality of various models used for NMA computations. Finally, we show that the input configuration also affects the density of modes, thus emphasizing the importance of simplified potential energy formulations that are minimized at the outset. In summary, our findings call for a serious two-way dialogue between theory and experiment: experimental spectra of proteins could now guide the fine tuning of theoretical empirical potentials, and the various features and peaks observed in theoretical studies—being universal, and hence now rising in importance—would hopefully spur experimental confirmation.