Hyperspectral imaging with a TWINS birefringent interferometer.

We introduce a high-performance hyperspectral camera based on the Fourier-transform approach, where the two delayed images are generated by the Translating-Wedge-Based Identical Pulses eNcoding System (TWINS) [Opt. Lett. 37, 3027 (2012)], a common-path birefringent interferometer that combines compactness, intrinsic interferometric delay precision, long-term stability and insensitivity to vibrations. In our imaging system, TWINS is employed as a time-scanning interferometer and generates high-contrast interferograms at the single-pixel level. The camera exhibits high throughput and provides hyperspectral images with spectral background level of -30dB and resolution of 3 THz in the visible spectral range. We show high-quality spectral measurements of absolute reflectance, fluorescence and transmission of artistic objects with various lateral sizes.

Versatile Control of

We demonstrate quantum control of ^{9}Be^{+} ions directly implemented by an optical frequency comb. Based on numerical simulations of the relevant processes in ^{9}Be^{+} for different magnetic field regimes, we demonstrate a wide applicability when controlling the comb's spectral properties. We introduce a novel technique for the selective and efficient generation of a spectrally tailored narrow-bandwidth optical frequency comb near 313 nm. We experimentally demonstrate internal state control and internal-motional state coupling of ^{9}Be^{+} ions implemented by stimulated-Raman manipulation using a spectrally optimized optical frequency comb. Our pulsed laser approach is a key enabling step for the implementation of quantum logic and quantum information experiments in Penning traps.

Fourier transform spectroscopy in the vibrational fingerprint region with a birefringent interferometer.

We introduce a birefringent interferometer for Fourier transform (FT) spectroscopy in the mid-infrared, covering the vibrational fingerprint region (5-10 µm, 1000-2000 cm-1), which is crucial for molecular identification. Our interferometer employs the crystal calomel (Hg2Cl2), which combines high birefringence (ne-no≈0.55) with a broad transparency range (0.38-20 µm). We adopt a design based on birefringent wedges, which is simple and compact and guarantees excellent delay accuracy and long-term stability. We demonstrate FTIR spectroscopy, with a frequency resolution of 3 cm-1, as well as two-dimensional IR (2DIR) spectroscopy. Our setup can be extended to other spectroscopic modalities such as vibrational circular dichroism and step-scan FT spectroscopy.

Narrowband carrier-envelope phase stable mid-infrared pulses at wavelengths beyond 10 µm by chirped-pulse difference frequency generation.

We report on the generation of narrowband carrier-envelope phase stable mid-infrared (MIR) pulses between 10 and 15 µm. High pulse energies and narrow bandwidths are required for the selective nonlinear excitation of collective modes of matter that is not possible with current sources. We demonstrate bandwidths of <2% at 12.5 µm wavelength through difference frequency generation between two near-infrared (NIR) pulses, which are linearly chirped. We obtain a reduction in bandwidth by one order of magnitude, compared to schemes that make use of transform-limited NIR pulses. The wavelength of the narrowband MIR pulse can be tuned by changing the optical delay between the two chirped NIR pulses.

Optical stark effects in j-aggregate-metal hybrid nanostructures exhibiting a strong exciton-surface-plasmon-polariton interaction.

We report on the observation of optical Stark effects in J-aggregate-metal hybrid nanostructures exhibiting strong exciton-surface-plasmon-polariton coupling. For redshifted nonresonant excitation, pump-probe spectra show short-lived dispersive line shapes of the exciton-surface-plasmon-polariton coupled modes caused by a pump-induced Stark shift of the polariton resonances. For larger coupling strengths, the sign of the Stark shift is reversed by a transient reduction in normal mode splitting. Our studies demonstrate an approach to coherently control and largely enhance optical Stark effects in strongly coupled hybrid systems. This may be useful for applications in ultrafast all-optical switching.

THz-Frequency Modulation of the Hubbard U in an Organic Mott Insulator.

We use midinfrared pulses with stable carrier-envelope phase offset to drive molecular vibrations in the charge transfer salt ET-F_{2}TCNQ, a prototypical one-dimensional Mott insulator. We find that the Mott gap, which is probed resonantly with 10 fs laser pulses, oscillates with the pump field. This observation reveals that molecular excitations can coherently perturb the electronic on-site interactions (Hubbard U) by changing the local orbital wave function. The gap oscillates at twice the frequency of the vibrational mode, indicating that the molecular distortions couple quadratically to the local charge density.

Complete analog control of the carrier-envelope-phase of a high-power laser amplifier.

In this work we demonstrate the development of a complete analog feedback loop for the control of the carrier-envelope phase (CEP) of a high-average power (20 W) laser operating at 10 kHz repetition rate. The proposed method combines a detection scheme working on a single-shot basis at the full-repetition-rate of the laser system with a fast actuator based either on an acousto-optic or on an electro-optic crystal. The feedback loop is used to correct the CEP fluctuations introduced by the amplification process demonstrating a CEP residual noise of 320 mrad measured on a single-shot basis. The comparison with a feedback loop operating at a lower sampling rate indicates an improvement up to 45% in the residual noise. The measurement of the CEP drift for different integration times clearly evidences the importance of the single-shot characterization of the residual CEP drift. The demonstrated scheme could be efficiently applied for systems approaching the 100 kHz repetition rate regime.

Ultrafast spectroscopy of linear carbon chains: the case of dinaphthylpolyynes.

The dynamics of excited states in α,ω-dinaphthylpolyyne, a class of linear sp-carbon chains, has been investigated by ultrafast transient absorption spectroscopy and DFT//TDDFT calculations. We show that the role of molecular conformers, in which end-capped naphthalene rings are planar or perpendicular to the polyyne plane, is fundamental for understanding both the steady state properties, such as UV-Vis absorption spectra and vibronic transitions, and the ultrafast transient absorption features. In particular, we observed in one of the conformers the ultrafast formation of a narrow photo-induced absorption band rising within 30 ps. This band can be assigned to an inter-system crossing event leading to the formation of triplet excited states.

Coherent synthesis of ultra-broadband optical parametric amplifiers.

We report on coherent synthesis of two ultra-broadband optical parametric amplifiers, each compressed by chirped mirror pairs, resulting in almost-octave-spanning (520-1000 nm) spectra supporting nearly single-cycle sub-4 fs pulse duration. Synthesized pulse timing is locked to less than 30 as by a balanced optical cross-correlator. The synthesized pulse is characterized by two-dimensional spectral interferometry and has a 3.8 fs duration.

Electron-phonon coupling in high-temperature cuprate superconductors determined from electron relaxation rates.

We determined electronic relaxation times via pump-probe optical spectroscopy using sub-15 fs pulses for the normal state of two different cuprate superconductors. We show that the primary relaxation process is the electron-phonon interaction and extract a measure of its strength, the second moment of the Eliashberg function λ[ω2] = 800 ± 200 meV2 for La(1.85)Sr(0.15)CuO4 and λ[ω2] = 400 ± 100 meV2 for YBa(2)Cu(3)O(6.5). These values suggest a possible fundamental role of the electron-phonon interaction in the superconducting pairing mechanism.

Hemodialysis: yesterday, today and tomorrow.

Hemodialysis was born in 1945 to treat acute renal failure, and it has progressively become a rescue therapy for patients with chronic kidney disease (CKD) stage 5, otherwise doomed to death. During the years, technological innovations have led to improved dialytic tolerance, making possible to extend the treatment to a greater number of subjects. Low- and high-flux bicarbonate dialysis are nowadays the most frequent hemodialysis techniques; hemodiafiltration with different modalities, short daily and overnight hemo-dialysis are also widespread, each of them with peculiar characteristics. A recent randomized controlled clinical trial has identified high-flux hemodialysis as the best treatment for patients with low serum levels of albumin and for diabetics in comparison to low flux dialysis. Apart from the treatment of end-stage renal disease (ESRD), hemodialysis has new and important applications, including heart failure treatment and multiple myeloma. The need to provide hemodialysis patients a better quality of life has increased the interest in developing new techniques, such as the wearable artificial kidney, although still in initial clinical development. During the last 60 years, we have seen an exciting evolution in the field of hemodialysis, which has led to important changes in the outcome of ESRD patients. The preclinical and clinical hard work ongoing in earlier stages of CKD should be able to obtain further relevant improvements and maybe avoid the need of hemodialysis itself.

Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu.

Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can explain the relatively old crater-retention ages of the equatorial features of Ryugu and Bennu. Two separate parent-body disruptions are not necessarily required to explain their different hydration levels.

The in vitro effects of cigarette smoke on fatty acid metabolism are partially counteracted by simvastatin.

BACKGROUND: Statins enhance the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs) from their precursors both in vitro and in vivo. In particular, an increased conversion of linoleic acid (LA) and of alpha-linolenic acid to their derivatives is observed in cultured cells. On the contrary, cigarette smoke (CS) negatively and dose-dependently affects the LC-PUFA production. AIM: To evaluate the effects of CS alone or with simvastatin, on [1-(14)C] LA metabolism in THP-1 cells. RESULTS: CS inhibits LA conversion; after co-incubation, simvastatin nullifies the effects of CS, maintaining LA conversion comparable to controls. However, at the highest CS concentration, simvastatin is unable to counteract the effects of CS. Changes of LA conversion reflect the modulation of desaturase activities by simvastatin and CS. CONCLUSION: CS decreases PUFA conversion and its effects are modulated by the opposite effect of statins. It can be speculated that statin treatments in smoking patients may provide some beneficial effects on PUFA metabolism in addition to lowering cholesterol levels.

An unusual cause of traumatic reticulitis/reticuloperitonitis in a herd of Swiss dairy cows nearby an airport.

This report describes the findings in five cows from one dairy herd, in which all 31 cows were slaughtered or euthanised because of traumatic reticuloperitonitis. All the cows had numerous thin sharp pieces of metal attached to a magnet in the reticulum, giving the magnet a hedgehog-like appearance. Investigation revealed that the cattle had eaten forage harvested from a field immediately adjacent to an airport. The snow was cleared from the airport runways with a machine that had a wire-bristle brush attachment. Mechanical wear resulted in numerous wire bristles breaking and these were blown with the snow onto the field in question. The wire then became accidentally incorporated into the hay and grass silage at harvest the next summer and was ingested by the cattle in the fall and winter. To prevent further cases, approximately 200 tonnes of hay and grass silage contaminated with wire were discarded and 30 hectares of the 50-hectare field were cultivated and re-sown. The wire-bristles of the snow plow were replaced with plastic bristles. The cost of this and the livestock loss was several hundred thousand Swiss Francs.

[Do convective treatments significantly reduce morbidity and mortality?]. / I trattamenti convettivi riducono significativamente morbilita' e mortalita'?

Standard hemodialysis is a far from ideal treatment for uremia since the morbidity and mortality of patients on hemodialysis are still significantly higher than those of non-hemodialyzed subjects with similar demographic characteristics. Because it has been suggested that the cause could lie in the inadequate removal of ''middle molecules'' by standard hemodialyis, two alternative treatments have been proposed: high-efficiency hemodialyis and high-flux hemodialyis. The 2002 results of the HEMO study showed that both these treatments are associated with a non-significant reduction in the relative risk of death (4% and 8%, respectively). The MPO study, which - unlike the HEMO study - enrolled only incident cases and not did not allow reuse of dialyzers, evaluated the mortality rate with high-flux and low-flux hemodialysis in a sicker population, i.e., patients with hypoalbuminemia, and showed a significant reduction in the relative risk of death especially in patients with diabetes. In an attempt to define the clinical impact of hemodiafiltration, some of the efficacy data from clinical studies are reviewed in light of a number of factors that may be related to the high mortality among hemodialysis patients. The current state of affairs suggests it is reasonable to prefer high-flux hemodialysis in sicker patients, especially diabetics. Moreover, the use of ultrapure dialysis fluid is recommended to reduce chronic inflammation and its consequences.

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu.

Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.

Soybean protein diet increases low density lipoprotein receptor activity in mononuclear cells from hypercholesterolemic patients.

The effect of two diets containing different protein sources (animal vs. soybean) on the low density lipoprotein (LDL) receptor activity was tested in freshly isolated mononuclear cells from 12 individuals with severe type II hyperlipoproteinemia. The two diets, both taken for 4 wk in a crossover design were of otherwise identical composition. During the soybean protein diet period, total cholesterol was reduced by 15.9% and LDL-cholesterol by 16.4%. The diet containing animal proteins exerted no significant change in plasma lipid levels vs. the baseline findings. The soybean diet regimen dramatically affected the degradation of LDL by mononuclear cells. Degradation was increased 16-fold vs. the basal activity and 8-fold compared with the standard low lipid diet with animal proteins. There was, however, no clear relationship between the reduction of total and LDL-cholesterolemia and the increased LDL degradation. These findings confirm similar data previously obtained in cholesterol-fed rats and suggest that some factor/s, most likely of a protein nature, may regulate the expression of lipoprotein receptors in peripheral cells, particularly when receptor activity is suppressed by experimental diets and/or spontaneous hypercholesterolemia.

Generation of broadband mid-infrared pulses from an optical parametric amplifier.

We report on the direct generation of broadband mid-IR pulses from an optical parametric amplifier. Several crystals with extended IR transparency, when pumped at 800 nm, display a broad phase-matching bandwidth around 1 mum, allowing for the generation of idler pulses spanning the 3-5 mum wavelength range. Using LiIO(3), we produce 2muJ pulses tunable in the 3-4 mum range with bandwidth supporting 30-fs transform-limited duration.

Narrow-bandwidth picosecond pulses by spectral compression of femtosecond pulses in second-order nonlinear crystals.

We introduce a simple approach for the efficient generation of tunable narrow-bandwidth picosecond pulses synchronized to broadband femtosecond ones. Second harmonic generation in the presence of large group velocity mismatch between the interacting pulses transfers a large fraction of the energy of a broadband fundamental frequency pulse into a narrowband second harmonic one. Using a periodically poled stoichiometric lithium tantalate crystal coupled to an infrared optical parametric amplifier, we generated 200-nJ pulses with spectral width lower than 8.5 cm(-1) and tunability from 720 to 890 nm. Energy scaling and extension of the tuning range are straightforward.

Towards VO2 monitoring: Validation of a heart rate based algorithm.

This article presents and validates a novel algorithm for the continuous monitoring of the VO2 during exercise. The algorithm relies on instantaneous HR measurements to provide a continuous estimation, and can be integrated in a wearable device (e.g., smartwatch, sensor patch). It can be customized by user's main anthropomorphic parameters and automatically learns from newly incoming data recalibrating itself if needed. The system is evaluated against a database of 14 healthy subjects performing various maximal endurance tests. The proposed method provides a VO2 estimation with average RMSE of 4.63 ml/kg/min.