Genetic relationships between weight loss in early lactation and daily milk production throughout lactation in Holstein cows.

After calving, high-yielding dairy cows mobilize body reserves for energy, sometimes to the detriment of health and fertility. This study aimed to estimate the genetic correlation between body weight loss until nadir and daily milk production (MY24) in first- (L1) and second-lactation (L2) Holstein cows. The data set included 859,020 MY24 records and 570,651 daily raw body weight (BWr) phenotypes from 3,989 L1 cows, and 665,361 MY24 records and 449,449 BWr phenotypes from 3,060 L2 cows, recorded on 36 French commercial farms equipped with milking robots that included an automatic weighing platform. To avoid any bias due to change in digestive content, BWr was adjusted for variations in feed intake, estimated from milk production and BWr. Adjusted body weight was denoted BW. The genetic parameters of BW and MY24 in L1 and L2 cows were estimated using a 4-trait random regression model. In this model, the random effects were fitted by second-order Legendre polynomials on a weekly basis from wk 1 to 44. Nadir of BW was found to be earlier than reported in the literature, at 29 d in milk, and BW loss from calving to nadir was also lower than generally assumed, close to 29 kg. To estimate genetic correlations between body weight loss and production, we defined BWL5 as the loss of weight between wk 1 and 5 after calving. Genetic correlations between BWL5 and MY24 ranged from -0.26 to 0.05 in L1 and from -0.11 to 0.10 in L2, according to days in milk. These moderate to low values suggest that it may be possible to select for milk production without increasing early body mobilization.

The importance of monitoring wet age-related macular degeneration patients during Coronavirus disease 19 pandemic: A retrospective study of assessment of functional and structural outcomes.

OBJECTIVES: Intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections are the gold standard treatment for wet age-related macular degeneration (wet AMD). Coronavirus disease 2019 (COVID-19) has led to the cancellation of many scheduled intravitreal anti-VEGF injection visits. We compared the functional and structural visual outcomes of wet AMD patients who did not adhere to their planned intervals (group 1) with those who did (group 2). METHODS: Wet AMD patients of Swiss Visio Montchoisi and RétinElysée were included. Best-corrected visual acuity (BCVA) and optical coherence tomography (OCT) changes between their first visit after the end of the first national lockdown in Switzerland (27 April 2020, first post-lockdown visit) and their last visit before the beginning of the first national lockdown in Switzerland (13 March 2020, last pre-lockdown visit) were assessed. The BCVA outcome was defined as unfavorable when there was a loss of≥5 ETDRS letters in the first post-lockdown visit compared to the BCVA at last pre-lockdown visit. The OCT outcome was defined as unfavorable when there was an increase in at least one of the parameters, intraretinal fluid (IRF), subretinal fluid (SRF), or pigment epithelial detachment (PED), at the first post-lockdown visit compared to the last pre-lockdown visit. MAIN RESULTS: Group 1 (89 patients, 109 eyes) had a 13.41% greater rate of unfavorable BCVA outcomes and a 38.27% greater rate of unfavorable OCT outcomes than group 2 (96 patients, 122 eyes) (P=0.04, P<0.0001, respectively). Multivariate analysis showed that the more the patients deviated from their programmed injections and the higher the BCVA pre-lockdown, the higher the rate of unfavorable BCVA outcomes (P=0.03 and P=0.02, respectively). OCT outcomes were not a predictive factor for an unfavorable BCVA outcome. CONCLUSIONS: The cancellation of many intravitreal anti-VEGF injection appointments resulted in worse functional and structural outcomes in wet AMD patients. The COVID-19 pandemic led many patients to refrain from their routine intravitreal anti-VEGF injection appointments, allowing us to analyze the role of designated intervals in the treatment of wet AMD. During any future lockdown due to COVID-19 or similar circumstances, continuity of care for wet AMD patients should be maintained.

Tailoring the refractive index of Ge-S based glass for 3D embedded waveguides operating in the mid-IR region.

The photosensitivity of GeS(x) binary glasses in response to irradiation to femtosecond pulses at 800 nm is investigated. Samples with three different molecular compositions were irradiated under different exposure conditions. The material response to laser exposure was characterized by both refractometry and micro-Raman spectroscopy. It is shown that the relative content of sulfur in the glass matrix influences the photo-induced refractive index modification. At low sulfur content, both positive and negative index changes can be obtained while at high sulfur content, only a positive index change can be reached. These changes were correlated with variations in the Raman response of exposed glass which were interpreted in terms of structural modifications of the glass network. Under optimized exposure conditions, waveguides with positive index changes of up to 7.8 x 10(-3)and a controllable diameter from 14 to 25 µm can be obtained. Direct inscription of low insertion losses (IL = 3.1 - 3.9 dB) waveguides is demonstrated in a sample characterized by a S/Ge ratio of 4. The current results open a pathway towards the use of Ge-S binary glasses for the fabrication of integrated mid-infrared photonic components.

High mechanical strength fiber Bragg gratings made with infrared femtosecond pulses and a phase mask.

We report that by using 800 nm femtosecond pulses and the phase-mask technique, first-order fiber Bragg gratings with refractive index modulation in excess of 1×10(-3) can be written through both the acrylate and polyimide coatings of unloaded standard silica fibers without noticeable degradation of mechanical strength. We also demonstrate that the same experimental conditions can be applied for efficient FBG writing through the polyimide coating of pure silica core fibers, opening significant opportunities in the field of fiber sensors.

Photon transport in cylindrically-shaped disordered meso-macroporous materials.

We theoretically and experimentally investigate light diffusion in disordered meso-macroporous materials with a cylindrical shape. High Internal Phase Emulsion (HIPE)-based silica foam samples, exhibiting a polydisperse pore-size distribution centered around 19 µm to resemble certain biological tissues, are realized. To quantify the effect of a finite lateral size on measurable quantities, an analytical model for diffusion in finite cylinders is developed and validated by Monte Carlo random walk simulations. Steady-state and time-resolved transmission experiments are performed and the transport parameters (transport mean free path and material absorption length) are successfully retrieved from fits of the experimental curves with the proposed model. This study reveals that scattering losses on the lateral sides of the samples are responsible for a lowering of the transmission signal and a shortening of the photon lifetime, similar in experimental observables to the effect of material absorption. The recognition of this geometrical effect is essential since its wrong attribution to material absorption could be detrimental in various applications, such as biological tissue diagnosis or conversion efficiency in dye-sensitized solar cells.

Mid-infrared chalcogenide glass Raman fiber laser.

We report the first demonstration of a Raman fiber laser (RFL) emitting in the mid-infrared, above 3 µm. The operation of a single-mode As2S3 chalcogenide glass based RFL at 3.34 µm is demonstrated by using a low-loss Fabry-Pérot cavity formed by a pair of fiber Bragg gratings. A specially designed quasi-cw erbium-doped fluoride fiber laser emitting at 3.005 µm is used to pump the RFL. A laser output peak power of 0.6 W is obtained with a lasing efficiency of 39% with respect to the launched pump power.

Writing of Bragg gratings through the polymer jacket of low-loss As2S3 fibers using femtosecond pulses at 800 nm.

Fiber Bragg gratings (FBG) were written through the polymer jacket of low-loss single mode As(2)S(3) chalcogenide fibers by using femtosecond laser pulses at 800 nm and a phase-mask. Peak reflectivity in excess of 99% was obtained at 3440 nm after 5 min of exposure. The resulting FBG maintained a peak reflectivity of 90% after 64 min of thermal annealing at 100 °C. This demonstration paves the way to the development of all-fiber mid-infrared laser sources.

Mutations in the tail domain of DYNC1H1 cause dominant spinal muscular atrophy.

OBJECTIVE: To identify the gene responsible for 14q32-linked dominant spinal muscular atrophy with lower extremity predominance (SMA-LED, OMIM 158600). METHODS: Target exon capture and next generation sequencing was used to analyze the 73 genes in the 14q32 linkage interval in 3 SMA-LED family members. Candidate gene sequencing in additional dominant SMA families used PCR and pooled target capture methods. Patient fibroblasts were biochemically analyzed. RESULTS: Regional exome sequencing of all candidate genes in the 14q32 interval in the original SMA-LED family identified only one missense mutation that segregated with disease state-a mutation in the tail domain of DYNC1H1 (I584L). Sequencing of DYNC1H1 in 32 additional probands with lower extremity predominant SMA found 2 additional heterozygous tail domain mutations (K671E and Y970C), confirming that multiple different mutations in the same domain can cause a similar phenotype. Biochemical analysis of dynein purified from patient-derived fibroblasts demonstrated that the I584L mutation dominantly disrupted dynein complex stability and function. CONCLUSIONS: We demonstrate that mutations in the tail domain of the heavy chain of cytoplasmic dynein (DYNC1H1) cause spinal muscular atrophy and provide experimental evidence that a human DYNC1H1 mutation disrupts dynein complex assembly and function. DYNC1H1 mutations were recently found in a family with Charcot-Marie-Tooth disease (type 2O) and in a child with mental retardation. Both of these phenotypes show partial overlap with the spinal muscular atrophy patients described here, indicating that dynein dysfunction is associated with a range of phenotypes in humans involving neuronal development and maintenance.

Study of the photosensitivity of GeS binary glasses to 800 nm femtosecond pulses.

We present the first study of the photosensitivity of GeS binary glasses in response to irradiation to femtosecond pulses at 800 nm. A maximum positive refractive index change of 3.5x10(-3) is demonstrated with the possibility to control the waveguide diameter from ~8 to ~50 µm by adjusting the input pulse energy. It is also demonstrated that under different exposure conditions, a maximum negative index change of -7.5x10(-3) can be reached. The present results clearly illustrate the potential of this family of glasses for the fabrication of mid-infrared waveguides.

Self-organized periodic structures on Ge-S based chalcogenide glass induced by femtosecond laser irradiation.

Self-organized periodic structures have been observed on the surface of the ablation craters of Ge-S based chalcogenide glass produced after irradiation by a focused beam of a femtosecond Ti:sapphire laser (1 kHz, 34 fs, 806 nm). Scanning electron microscopy and atomic force microscopy images of irradiated spots show a periodic structure of ripples with a spatial period of 720 nm (close to the wavelength of fs laser pulses) and an alignment parallel to the electric field of light. With an increasing number of pulses, from 5 to 50 pulses, a characteristic evolution of ripples was observed from a random structure to a series of generally aligned peaks-and-valleys self-organized periodic structures. Additionally, at the center of the ablated spot, micro-domains appear where the ripples are still regular but are assembled in a more complex fashion. The experimental observations are interpreted in terms of strong temperature gradients combined with interference of the incident laser irradiation and a scattered surface electromagnetic wave.

In vivo evaluation of demyelination and remyelination in a nerve crush injury model.

Nerves of the peripheral nervous system have, to some extent, the ability to regenerate after injury, particularly in instances of crush or contusion injuries. After a controlled crush injury of the rat sciatic nerve, demyelination and remyelination are followed with functional assessments and imaged both ex vivo and in vivo over the course of 4 weeks with video-rate coherent anti-Stokes Raman scattering (CARS) microscopy. A new procedure compatible with live animal imaging is developed for performing histomorphometry of myelinated axons. This allows quantification of demyelination proximal and remyelination distal to the crush site ex vivo and in vivo respectively.

Single molecule probing of dynamics in supercooled polymers.

Fluorescence experiments with single BODIPY molecules embedded in a poly(methyl acrylate) matrix have been performed at various temperatures in the supercooled regime. By using pulsed excitation, fluorescence lifetime and linear dichroism time trajectories were accessible at the same time. Both observables have been analyzed without data binning. While the linear dichroism solely reflects single particle dynamics, the fluorescence lifetime observable depends on the molecular environment, so that the dynamics from the polymer host surrounding a chromophore contributes to this quantity. We observe that the lifetime correlation decays slightly faster than polarization correlation, indicating the occurrence of large angular reorientations. Additionally, dichroism time trajectories have been adducted to reveal directly the geometry of rotational dynamics. We identify small but also significantly larger rotational jumps being responsible for the overall molecular reorientation.

Probe molecules in polymer melts near the glass transition: A molecular dynamics study of chain length effects.

Molecular dynamics simulations of a dense melt of short bead-spring polymer chains containing N=5, 10, or 25 effective monomers are presented and analyzed. Parts of our simulations include also a single dumbbell (N=2) of the same type, which is interpreted to represent a coarse-grained model for a fluorescent probe molecule as used in corresponding experiments. We obtain the mean-square displacements of monomers and chains center of mass, and intermediate incoherent scattering functions of both monomers in the chains and particles in the dumbbells as function of time for a broad regime of temperatures above the critical temperature T(c) of mode-coupling theory. For both the chains and the dumbbell, also orientational autocorrelation functions are calculated and for the dumbbell time series for the time evolution of linear dichroism and its autocorrelation function are studied. From both sets of data we find that both the mode-coupling critical temperature T(c) (representing the "cage effect") and the Vogel-Fulcher temperature T(0) (representing the caloric glass transition temperature) systematically increase with chain length. Furthermore, the dumbbell dynamics yields detailed information on the differences in the matrix dynamics that are caused by the chain length variation. Deviations from the Stokes-Einstein relation are discussed, and an outlook to related experiments is given.

Controlling the photoluminescence of CdSe/ZnS quantum dots with a magnetic field.

We present an investigation of the photoluminescence of CdSe/ZnS quantum dots at high light intensity and in low magnetic fields. Upon increasing the magnetic field up to 90 G, the photoluminescence intensity drops. When decreasing the magnetic field back to zero the photoluminescence drop remains present. A plausible explanation is the Zeeman splitting of defect-associated energy levels under the influence of a magnetic field. The defect-trapped electrons may then be positioned at a metastable level, thereby reducing the number of recombinations. This effect may be used to control the luminescence of quantum dots.

Quantitative myelin imaging with coherent anti-Stokes Raman scattering microscopy: alleviating the excitation polarization dependence with circularly polarized laser beams.

The use of coherent anti-Stokes Raman scattering microscopy tuned to the lipid vibration for quantitative myelin imaging suffers from the excitation polarization dependence of this third-order nonlinear optical effect. The contrast obtained depends on the orientation of the myelin membrane, which in turn affects the morphometric parameters that can be extracted with image analysis. We show how circularly polarized laser beams can be used to avoid this complication, leading to images free of excitation polarization dependence. The technique promises to be optimal for in vivo imaging and the resulting images can be used for coherent anti-Stokes Raman scattering optical histology on native state tissue.

Ytterbium fiber laser based on first-order fiber Bragg gratings written with 400 nm femtosecond pulses and a phase-mask.

A Fiber Bragg grating of 369 nm pitch was inscribed in a germanium-free double-clad ytterbium doped silica fiber using a femto-second pulse train at 400 nm wavelength and a phase mask. The photo-induced refractive index modulation of higher than 4 x 10(-3) was obtained and the accompanying photo-induced losses were subsequently removed by thermal annealing, resulting in a low loss (<0.1 dB), stable and high reflectivity (>40 dB) FBG. Based on this FBG, a monolithic Ytterbium fiber laser operating at 1073 nm with slope efficiency of 71% and output power of 13 W was demonstrated.

2.3 W single transverse mode thulium-doped ZBLAN fiber laser at 1480 nm.

A 2.3 W single transverse mode thulium-doped fluoride fiber laser based on fiber Bragg gratings is presented. The laser has a conversion efficiency of 65% to be compared to the quantum limit of 72%. The performances of the laser are compared for two pump wavelengths of 1040 and 1064 nm and are analyzed based on a rate equation analysis.

Analysis of the exponential character of single molecule rotational correlation functions for large and small fluorescence collection angles.

Coarse-grained molecular dynamics simulations and single molecule fluorescence microscopy experiments have been performed in order to investigate the influence of the numerical aperture (NA) of the microscope objective on the exponential character of the rotational correlation functions of probes embedded in complex matrices. The results obtained by using either a dry lens (NA=0.95) or an oil objective (NA=1.4) show that, in the moderately (simulations) and deeply (experiment) supercooled melts, the rotational (linear dichroism) correlation functions of the single molecules (SMs) exhibit a nonexponential character. Furthermore, by fitting Kohlrausch-Williams-Watt functions to the correlation curves, the stretching parameters turn out to be very similar for both types of objectives. Our results demonstrate that the nonexponentiality is intrinsic to the complex rotational dynamics of the SM in the supercooled solid and point to the validity of the use of a high NA dry lens to perform such experiments.

Purely axial compression of fiber Bragg gratings embedded in a highly deformable polymer.

We demonstrate a tuning device for fiber Bragg gratings with a wavelength tuning range in excess of 65 nm. A purely axial tuning technique using a highly deformable polymer molded in a cylinder shape is used to embed a fiber Bragg grating and to achieve a wavelength tuning range from 1551.7 to 1485.5 nm. The tuning curve is highly linear with a tuning rate of 9.6 nm for every percent of applied strain. The insertion losses of the device, the variations of the full width at half maximum, and the stability of the Bragg wavelength over a working day have been studied and shown to be less than 0.02 dB, 0.14, and 0.2 nm, respectively.

Single molecule probing of the glass transition phenomenon: simulations of several types of probes.

Molecular dynamics simulations of a system of short bead-spring chains containing an additional dumbbell are presented and analyzed. This system represents a coarse-grained model for a melt of short, flexible polymers containing fluorescent probe molecules at very dilute concentration. It is shown that such a system is very well suited to study aspects of the glass transition of the undercooled polymer melt via single molecule spectroscopy, which are not easily accessed by other methods. Such aspects include data which can be extracted from a study of fluctuations along a trajectory of the single molecule, probing the rugged energy landscape of the glass-forming liquid and transitions from one metabasin of this energy landscape to the next one. Such an information can be inferred from "distance maps" constructed from trajectories characterizing the translational and orientational motion of the probe. At the same time, determining autocorrelation functions along such trajectories, it is shown for several types of probes (differing in their size and/or mass within reasonable limits) that this time-averaged information of the probe is fully compatible with ensemble averaged information on the relaxation of the glass-forming matrix, accessible from bulk measurements. The analyzed quantities include the fluorescence lifetime, linear dichroism, and also various orientational correlation functions of the probe, in order to provide guidance to experimental work. Similar to earlier findings from simulations of bulk molecular fluids, deviations from the Stokes-Einstein and Stokes-Einstein-Debye relations are observed.