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https://www.readbyqxmd.com/read/28526480/human-seasonal-and-circadian-studies-in-antarctica-halley-75-0-s
#1
Josephine Arendt, Benita Middleton
Living for extended periods in Antarctica exposes base personnel to extremes of daylength (photoperiod) and temperature. At the British Antarctic Survey base of Halley, 75(0)S, the sun does not rise for 110 d in the winter and does not set for 100 d in summer. Photoperiod is the major time cue governing the timing of seasonal events such as reproduction in many species. The neuroendocrine signal providing photoperiodic information to body physiology is the duration of melatonin secretion which reflects the length of the night: longer in the short days of winter and shorter in summer...
May 16, 2017: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/28504766/direct-stabilization-of-optomechanical-oscillators
#2
Ke Huang, Mani Hossein-Zadeh
We demonstrate a simple and effective technique for stabilizing the oscillation amplitude of a radiation pressure driven RF optomechanical oscillator (OMO). By controlling the optomechanical gain through a feedback loop that uses the oscillation amplitude itself as the feedback parameter, we have been able to suppress the amplitude fluctuations and drift. In contrast to more complex techniques that only lock the relative wavelength detuning, the proposed technique isolates the oscillation amplitude not only from laser wavelength variations, but also from laser power variations, ambient temperature variations, and coupling gap variations...
May 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28499924/hypercholesterolemia-causes-circadian-dysfunction-a-potential-risk-factor-for-cardiovascular-disease
#3
Makoto Akashi, Ritsuko Matsumura, Takahiro Matsuo, Yuki Kubo, Hiroshi Komoda, Koichi Node
Hypercholesterolemia is a well-known risk factor for a wide range of diseases in developed countries. Here, we report that mice lacking functional LDLR (low density lipoprotein receptor), an animal model of human familial hypercholesterolemia, show circadian abnormalities. In free running behavioral experiments in constant darkness, these mice showed a prolonged active phase and distinctly bimodal rhythms. Even when the circadian rhythms were entrained by light and dark cycles, these mice showed a significant attenuation of behavioral onset intensity at the start of the dark period...
April 27, 2017: EBioMedicine
https://www.readbyqxmd.com/read/28495879/dual-comb-spectroscopy-of-water-vapor-with-a-free-running-semiconductor-disk-laser
#4
S M Link, D J H C Maas, D Waldburger, U Keller
Dual-comb spectroscopy offers the potential for high accuracy combined with fast data acquisition. Applications are often limited, however, by the complexity of optical comb systems. Here we present dual-comb spectroscopy of water vapor using a substantially simplified single-laser system. Very good spectroscopy measurements with fast sampling rates are achieved with a free-running dual-comb mode-locked semiconductor disk laser. The absolute stability of the optical comb modes is characterized both for free-running operation and with simple microwave stabilization...
May 11, 2017: Science
https://www.readbyqxmd.com/read/28490102/effect-of-grape-juice-press-fractioning-on-polysaccharide-and-oligosaccharide-compositions-of-pinot-meunier-and-chardonnay-champagne-base-wines
#5
Sandrine Jégou, Duc An Hoang, Thomas Salmon, Pascale Williams, Solomen Oluwa, Céline Vrigneau, Thierry Doco, Richard Marchal
Press fractioning is an important step in the production of sparkling base wines to segregate the grape juices with different qualities. Grape juice fractions were collected during the pressing cycle at industrial and laboratory scales. The Pinot meunier and Chardonnay Champagne base wines obtained from the free-run juice and the squeezed juices exhibited strong differences from the beginning to the last step of pressing cycle for numerous enological parameters. Significant changes in polysaccharide (PS) and oligosaccharide (OS) base wine composition and concentration were found as the pressing cycle progressed...
October 1, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28461004/disruption-of-normal-circadian-clock-function-in-a-mouse-model-of-tauopathy
#6
Korey Stevanovic, Amara Yunus, Aurelie Joly-Amado, Marcia Gordon, David Morgan, Danielle Gulick, Joshua Gamsby
Disruption of normal circadian rhythm physiology is associated with neurodegenerative disease, which can lead to symptoms such as altered sleep cycles. In Alzheimer's disease (AD), circadian dysfunction has been attributed to β-amyloidosis. However, it is unclear whether tauopathy, another AD-associated neuropathology, can disrupt the circadian clock. We have evaluated the status of the circadian clock in a mouse model of tauopathy (Tg4510). Tg4510 mice display a long free-running period at an age when tauopathy is present, and show evidence of tauopathy in the suprachiasmatic nucleus (SCN) of the hypothalamus - the site of the master circadian clock...
April 28, 2017: Experimental Neurology
https://www.readbyqxmd.com/read/28452285/daily-light-exposure-patterns-reveal-phase-and-period-of-the-human-circadian-clock
#7
Tom Woelders, Domien G M Beersma, Marijke C M Gordijn, Roelof A Hut, Emma J Wams
Light is the most potent time cue that synchronizes (entrains) the circadian pacemaker to the 24-h solar cycle. This entrainment process is an interplay between an individual's daily light perception and intrinsic pacemaker period under free-running conditions. Establishing individual estimates of circadian phase and period can be time-consuming. We show that circadian phase can be accurately predicted (SD = 1.1 h for dim light melatonin onset, DLMO) using 9 days of ambulatory light and activity data as an input to Kronauer's limit-cycle model for the human circadian system...
April 1, 2017: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28448626/genetic-background-dependent-effects-of-murine-micro-rnas-on-circadian-clock-function
#8
Silke Kiessling, Ahmet Ucar, Kamal Chowdhury, Henrik Oster, Gregor Eichele
MicroRNAs (miRs) are important regulators of a wide range of biological processes. Antagomir studies suggest an implication of miR-132 in the functionality of the mammalian circadian clock. miR-212 and miR-132 are tandemly processed from the same transcript and share the same seed region. We found the clock modulator miR-132 and miR-212 to be expressed rhythmically in the central circadian clock. Consequently, mRNAs implicated in circadian functions may likely be targeted by both miRs. To further characterize the circadian role we generated mice with stable deletion of the miR-132/212 locus and compared the circadian behavior of mutant and wild-type control animals on two genetic backgrounds frequently used in chronobiological research, C57BL/6N and 129/Sv...
2017: PloS One
https://www.readbyqxmd.com/read/28437981/efficient-laser-noise-reduction-method-via-actively-stabilized-optical-delay-line
#9
Dawei Li, Cheng Qian, Ye Li, Jianye Zhao
We report a fiber laser noise reduction method by locking it to an actively stabilized optical delay line, specifically a fiber-based Mach-Zehnder interferometer with a 10 km optical fiber spool. The fiber spool is used to achieve large arm imbalance. The heterodyne signal of the two arms converts the laser noise from the optical domain to several megahertz, and it is used in laser noise reduction by a phase-locked loop. An additional phase-locked loop is induced in the system to compensate the phase noise due to environmentally induced length fluctuations of the optical fiber spool...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28418264/emission-characteristics-of-laser-induced-plasma-using-collinear-long-and-short-dual-pulse-laser-induced-breakdown-spectroscopy-libs
#10
Zhenzhen Wang, Yoshihiro Deguchi, Renwei Liu, Akihiro Ikutomo, Zhenzhen Zhang, Daotong Chong, Junjie Yan, Jiping Liu, Fang-Jung Shiou
Collinear long and short dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) was employed to clarify the emission characteristics from laser-induced plasma. The plasma was sustained and became stable by the long pulse-width laser with the pulse width of 60 μs under free running (FR) conditions as an external energy source. Comparing the measurement results of stainless steel in air using single-pulse LIBS (SP-LIBS) and DP-LIBS, the emission intensity was markedly enhanced using DP-LIBS. The temperature of plasma induced by DP-LIBS was maintained at a higher temperature under different gate delay time and short pulse-width laser power conditions compared with those measured using short SP-LIBS...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28416676/dissociation-of-per1-and-bmal1-circadian-rhythms-in-the-suprachiasmatic-nucleus-in-parallel-with-behavioral-outputs
#11
Daisuke Ono, Sato Honma, Yoshihiro Nakajima, Shigeru Kuroda, Ryosuke Enoki, Ken-Ichi Honma
The temporal order of physiology and behavior in mammals is primarily regulated by the circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). Taking advantage of bioluminescence reporters, we monitored the circadian rhythms of the expression of clock genes Per1 and Bmal1 in the SCN of freely moving mice and found that the rate of phase shifts induced by a single light pulse was different in the two rhythms. The Per1-luc rhythm was phase-delayed instantaneously by the light presented at the subjective evening in parallel with the activity onset of behavioral rhythm, whereas the Bmal1-ELuc rhythm was phase-delayed gradually, similar to the activity offset...
May 2, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28415286/dissociation-between-two-subgroups-of-the-suprachiasmatic-nucleus-affected-by-the-number-of-damped-oscillated-neurons
#12
Changgui Gu, Huijie Yang, Jos Ht Rohling
In mammals, the main clock located in the suprachiasmatic nucleus (SCN) of the brain synchronizes the body rhythms to the environmental light-dark cycle. The SCN is composed of about 2×10^{4} neurons which can be classified into three oscillatory phenotypes: self-sustained oscillators, damped oscillators, and arrhythmic neurons. Exposed to an artificial external light-dark cycle with a period of 22h instead of 24h, two subgroups of the SCN can become desynchronized (dissociated). The ventrolateral (VL) subgroup receives photic input and is entrained to the external cycle and a dorsomedial (DM) subgroup oscillates with its endogenous (i...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28382017/disrupted-ultradian-activity-rhythms-and-differential-expression-of-several-clock-genes-in-interleukin-6-deficient-mice
#13
Francisco J Monje, Ana Cicvaric, Juan Pablo Acevedo Aguilar, Immanuel Elbau, Orsolya Horvath, Weifei Diao, Micaela Glat, Daniela D Pollak
The characteristics of the cycles of activity and rest stand out among the most intensively investigated aspects of circadian rhythmicity in humans and experimental animals. Alterations in the circadian patterns of activity and rest are strongly linked to cognitive and emotional dysfunctions in severe mental illnesses such as Alzheimer's disease (AD) and major depression (MDD). The proinflammatory cytokine interleukin 6 (IL-6) has been prominently associated with the pathogenesis of AD and MDD. However, the potential involvement of IL-6 in the modulation of the diurnal rhythms of activity and rest has not been investigated...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28380932/self-corrected-chip-based-dual-comb-spectrometer
#14
Nicolas Bourbeau Hébert, Jérôme Genest, Jean-Daniel Deschênes, Hugo Bergeron, George Y Chen, Champak Khurmi, David G Lancaster
We present a dual-comb spectrometer based on two passively mode-locked waveguide lasers integrated in a single Er-doped ZBLAN chip. This original design yields two free-running frequency combs having a high level of mutual stability. We developed in parallel a self-correction algorithm that compensates residual relative fluctuations and yields mode-resolved spectra without the help of any reference laser or control system. Fluctuations are extracted directly from the interferograms using the concept of ambiguity function, which leads to a significant simplification of the instrument that will greatly ease its widespread adoption and commercial deployment...
April 3, 2017: Optics Express
https://www.readbyqxmd.com/read/28380828/performance-and-wavelength-tuning-of-green-emitting-terbium-lasers
#15
Philip Werner Metz, Daniel-Timo Marzahl, Günter Huber, Christian Kränkel
Wavelength tuning experiments in the green spectral range applying Tb<sup>3+</sup>-doped LiLuF<sub>4</sub> and Tb<sup>3+</sup>/Na<sup>+</sup>-codoped CaF<sub>2</sub> single crystals are presented. While in the former case almost 100 mW could be obtained throughout a total range of 7 nm, the inhomogeneously broadened emission features of Tb<sup>3+</sup> in the CaF<sub>2</sub>-matrix allowed for a continuous tuning range exceeding 10 nm...
March 6, 2017: Optics Express
https://www.readbyqxmd.com/read/28332253/sex-and-ancestry-determine-the-free-running-circadian-period
#16
Charmane I Eastman, Victoria A Tomaka, Stephanie J Crowley
The endogenous, free-running circadian period (τ) determines the phase relationship that an organism assumes when entrained to the 24-h day. We found a shorter circadian period in African Americans compared to non-Hispanic European Americans (24.07 versus 24.33 h). We speculate that a short circadian period, closer to 24 h, was advantageous to humans living around the equator, but when humans migrated North out of Africa, where the photoperiod changes with seasons, natural selection favoured people with longer circadian periods...
March 23, 2017: Journal of Sleep Research
https://www.readbyqxmd.com/read/28331201/synchrony-of-plant-cellular-circadian-clocks-with-heterogeneous-properties-under-light-dark-cycles
#17
Masaaki Okada, Tomoaki Muranaka, Shogo Ito, Tokitaka Oyama
Individual cells in a plant can work independently as circadian clocks, and their properties are the basis of various circadian phenomena. The behaviour of individual cellular clocks in Lemna gibba was orderly under 24-h light/dark cycles despite their heterogeneous free-running periods (FRPs). Here, we reveal the entrainment habits of heterogeneous cellular clocks using non-24-h light/dark cycles (T-cycles). The cellular rhythms of AtCCA1::LUC under T = 16 h cycles showed heterogeneous entrainment that was associated with their heterogeneous FRPs...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28297889/time-varying-coupling-functions-dynamical-inference-and-cause-of-synchronization-transitions
#18
Tomislav Stankovski
Interactions in nature can be described by their coupling strength, direction of coupling, and coupling function. The coupling strength and directionality are relatively well understood and studied, at least for two interacting systems; however, there can be a complexity in the interactions uniquely dependent on the coupling functions. Such a special case is studied here: synchronization transition occurs only due to the time variability of the coupling functions, while the net coupling strength is constant throughout the observation time...
February 2017: Physical Review. E
https://www.readbyqxmd.com/read/28295094/excess-carrier-envelope-phase-noise-generation-in-saturable-absorbers
#19
Nils Raabe, Tianli Feng, Mark Mero, Haochen Tian, Youjian Song, Wolfgang Hänsel, Ronald Holzwarth, Alexander Sell, Armin Zach, Günter Steinmeyer
Attosecond spectroscopy and precision frequency metrology depend on the stabilization of the carrier-envelope phase (CEP) of mode-locked lasers. Unfortunately, the phase of only a few types of lasers can be stabilized to jitters in the few-hundred millirad range. In a comparative experimental study, we analyze a femtosecond Ti:sapphire laser and three mode-locked fiber lasers. We numerically demodulate recorded time series of the free-running carrier-envelope beat note. Our analysis indicates a correlation between amplitude and frequency fluctuations at low Fourier frequencies for essentially all lasers investigated...
March 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28271169/-intraoperative-monitoring-of-the-facial-nerve-vestibular-schwannoma-surgery
#20
J Prell, C Strauss, S K Plontke, S Rampp
BACKGROUND: In vestibular schwannoma surgery, facial nerve injury with consecutive functional impairment is one of the most important complications. Intraoperative monitoring of facial nerve function has been developed in order to avoid this complication. OBJECTIVE: Which methods for intraoperative monitoring have been developed? Which methods are in use today and what can they achieve in modern vestibular schwannoma surgery? MATERIAL AND METHODS: This article provides an evaluation and summary of the literature, as well as a discussion of the methods and their ability to achieve the goals of intraoperative monitoring...
March 7, 2017: HNO
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