Multiperiodicity in the Light Variations of the Beta Cephei Star Beta Crucis

NASA Technical Reports Server (NTRS)

Cuypers, J.; Aerts, C.; Buzasi, D.; Catanzarite, J.; Conrow, T.; Laher, R.

2002-01-01

High-resolution spectroscopic observations have led recently to the discovery that the P Cephei star Beta Crucis (Mimosa) is multiperiodic with at least three non-radial pulsation modes. Data obtained by the star tracker of the WIRE satellite have now allowed us to confirm this multiperiodicity in the light variations. A total of five million observations covering 17 days was analyzed and the three main periods we find in this work are in perfect agreement with the results derived from the line profile variations. The photometric amplitudes are small (3, 2.7 and 0.6 millimag for the dominant modes), but this is not surprising in view of the mode identifications derived earlier from the line profiles. Additional periods of low-amplitude modes (between 0.2-0.3 mmag) are also derived, including one suggested earlier by the radial velocity data.

Period Variations of the Eclipsing Binary Systems T LMi and VX Lac

NASA Astrophysics Data System (ADS)

Yılmaz, M.; İzci, D. D.; Gümüş, D.; Özavci, İ.; Selam, S. O.

2015-07-01

We present a period analysis of the two Algol-type eclipsing binary systems T LMi and VX Lac using all available times of minimum in the literature, as well as new minima obtained at the Ankara University Kreiken Observatory. The period analysis of T LMi suggests mass transfer between the components and also a third body that is dynamically bound to the binary system. The analysis of VX Lac also suggests mass transfer between the components, and the presence of a third and a fourth body under the assumption of a Light-Time Effect. In addition, the periodic variation of VX Lac was examined under the hypothesis of magnetic activity, and the corresponding parameters were derived. We report here the orbital parameters for both systems, along with the ones related to mass transfer, and those for the third and fourth bodies.

Light period regulation of carbohydrate partitioning

NASA Technical Reports Server (NTRS)

Janes, Harry W.

1994-01-01

We have shown that the photosynthetic period is important in regulating carbon partitioning. Even when the same amount of carbon is fixed over a 24h period considerably more is translocated out of the leaf under the longer photosynthetic period. This is extremely important when parts of the plant other than the leaves are to be sold. It is also important to notice the amount of carbon respired in the short photosynthetic period. The light period effect on carbohydrate fixation, dark respiration, and translocation is shown in this report.

THREE FUNDAMENTAL PERIODS IN AN 87 YEAR LIGHT CURVE OF THE SYMBIOTIC STAR MWC 560

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leibowitz, Elia M.; Formiggini, Liliana, E-mail: elia@astro.tau.ac.il

2015-08-15

We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers ofmore » the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.« less

Mid-Term Quasi-Periodicities and Solar Cycle Variation of the White-Light Corona from 18.5 Years (1996.0 - 2014.5) of LASCO Observations

NASA Astrophysics Data System (ADS)

Barlyaeva, T.; Lamy, P.; Llebaria, A.

2015-07-01

We report on the analysis of the temporal evolution of the solar corona based on 18.5 years (1996.0 - 2014.5) of white-light observations with the SOHO/LASCO-C2 coronagraph. This evolution is quantified by generating spatially integrated values of the K-corona radiance, first globally, then in latitudinal sectors. The analysis considers time series of monthly values and 13-month running means of the radiance as well as several indices and proxies of solar activity. We study correlation, wavelet time-frequency spectra, and cross-coherence and phase spectra between these quantities. Our results give a detailed insight on how the corona responds to solar activity over timescales ranging from mid-term quasi-periodicities (also known as quasi-biennial oscillations or QBOs) to the long-term 11 year solar cycle. The amplitude of the variation between successive solar maxima and minima (modulation factor) very much depends upon the strength of the cycle and upon the heliographic latitude. An asymmetry is observed during the ascending phase of Solar Cycle 24, prominently in the royal and polar sectors, with north leading. Most prominent QBOs are a quasi-annual period during the maximum phase of Solar Cycle 23 and a shorter period, seven to eight months, in the ascending and maximum phases of Solar Cycle 24. They share the same properties as the solar QBOs: variable periodicity, intermittency, asymmetric development in the northern and southern solar hemispheres, and largest amplitudes during the maximum phase of solar cycles. The strongest correlation of the temporal variations of the coronal radiance - and consequently the coronal electron density - is found with the total magnetic flux. Considering that the morphology of the solar corona is also directly controlled by the topology of the magnetic field, this correlation reinforces the view that they are intimately connected, including their variability at all timescales.

No Evidence of Periodic Variability in the Light Curve of Active Galaxy J0045+41

NASA Astrophysics Data System (ADS)

Barth, Aaron J.; Stern, Daniel

2018-05-01

Dorn-Wallenstein, Levesque, & Ruan recently presented the identification of a z = 0.215 active galaxy located behind M31 and claimed the detection of multiple periodic variations in the object’s light curve with as many as nine different periods. They interpreted these results as evidence of the presence of a binary supermassive black hole with an orbital separation of just a few hundred au, and estimated the gravitational-wave signal implied by such a system. We demonstrate that the claimed periodicities are based on a misinterpretation of the null hypothesis test simulations and an error in the method used to calculate the false alarm probabilities. There is no evidence of periodicity in the data.

Double cyclic variations in orbital period of the eclipsing cataclysmic variable EX Dra

NASA Astrophysics Data System (ADS)

Han, Zhong-tao; Qian, Sheng-bang; Voloshina, Irina; Zhu, Li-Ying

2017-06-01

EX Dra is a long-period eclipsing dwarf nova with ˜2-3 mag amplitude outbursts. This star has been monitored photometrically from November, 2009 to March, 2016 and 29 new mid-eclipse times were obtained. By using new data together with the published data, the best fit to the O-C curve indicate that the orbital period of EX Dra have an upward parabolic change while undergoing double-cyclic variations with the periods of 21.4 and 3.99 years, respectively. The upward parabolic change reveals a long-term increase at a rate of \\dot{P}= {+7.46}×10^{-11} s s^{-1}. The evolutionary theory of cataclysmic variables (CVs) predicts that, as a CV evolves, the orbital period should be decreasing rather than increasing. Secular increase can be explained as the mass transfer between the secondary and primary or may be just an observed part of a longer cyclic change. Most plausible explanation for the double-cyclic variations is a pair of light travel-time effect via the presence of two companions. Their masses are determined to be MAsin i'A=29.3(±0.6) M_{Jup} and MBsin i'B=50.8(±0.2) M_{Jup}. When the two companions are coplanar to the orbital plane of the central eclipsing pair, their masses would match to brown dwarfs.

Magnetic Activity and Period Variation Studies of the Short-period Eclipsing Binaries. II. V1101 Her, AD Phe, and NSV 455 (J011636.15-394955.7)

NASA Astrophysics Data System (ADS)

Pi, Qing-feng; Zhang, Li-yun; Bi, Shao-lan; Han, Xianming L.; Wang, Dai-mei; Lu, Hong-peng

2017-12-01

In this paper, we present new BVRI light curves of short-period contact eclipsing binaries V1101 Her and AD Phe from our observations carried out from 2014 to 2015 using the SARA KP and SARA CT telescopes. There is an eclipsing binary located at α(2000) = 01h16m36.ˢ15 and δ(2000) = -39°49‧55.″7 in the field of view of AD Phe. We derived an updated ephemeris and found there a cyclic variation overlaying a continuous period increase (V1101 Her) and decrease (AD Phe). This kind of cyclic variation may be attributed to the light time effect via the presence of the third body or magnetic activity cycle. The orbital period increase suggests that V1101 Her is undergoing a mass-transfer from the primary to the secondary component (dM 1/dt = 2.64(±0.11) × 10-6 M ⊙ yr-1) with the third body (P 3 = 13.9(±1.9) years), or 2.81(±0.07) × 10-6 M ⊙ yr-1 for an increase andmagnetic cycle (12.4(±0.5) years). The long-term period decrease suggests that AD Phe is undergoing a mass-transfer from the secondary component to the primary component at a rate of -8.04(±0.09) × 10-8 M ⊙ yr-1 for a period decrease and the third body (P 3 = 56.2(±0.8) years), or -7.11(±0.04) × 10-8 M ⊙ yr-1 for a decrease and magnetic cycle (50.3(±0.5) years). We determined their orbital and geometrical parameters. For AD Phe, we simultaneously analyzed our BVRI light curves and the spectroscopic observations obtained by Duerbeck & Rucinski. The spectral type of V1101 Her was classified as G0 ± 2V by LAMOST stellar spectra survey. The asymmetry of the R-band light curve of AD Phe obtained by McFarlane & Hilditch in 1987 is explained by a cool spot on the primary component.

Variation in the Level of Grain Defect Light Flecks and Spots on Cattle Hides

PubMed Central

Nafstad, O; Grønstøl, H

2001-01-01

The occurrence of hide damage light flecks and spots was determined on tanned hides from 28 herds during a period of 8 to 12 months. Light flecks and spots are described as small areas of grain loss up to 3 mm in diameter that are seen on dyed crust cattle leather. Damage was found on 75.8% of all hides. The neck and shoulders were the anatomical region with the highest prevalence of damage. Sixty-eight per cent of all hides had light flecks and spots in this region. The forelimbs and dewlap were the anatomical region with the second highest occurrence with a prevalence of 39.1%. This distribution corresponded to the known distribution of lice in cattle. No significant differences were observed in age, sex, prevalence of lice in the herd assessed in March or infestations with different lice species. The frequency of light flecks and spots varied significantly during the year. The frequency was highest in the late winter and early spring, decreased significantly during the summer and was lowest in the autumn. This variation supported the importance of lice in the development of light flecks and spots and suggested a relatively long healing period for the damages induced by lice. PMID:11455905

Photometric Investigation and Possible Light-Time Effect in the Orbital Period of a Marginal Contact System, CW Cassiopeiae

NASA Astrophysics Data System (ADS)

Jiang, Tian-Yu; Li, Li-Fang; Han, Zhan-Wen; Jiang, Deng-Kai

2010-04-01

The first complete charge-coupled device (CCD) light curves in B and V passbands of a neglected contact binary system, CW Cassiopeiae (CW Cas), are presented. They were analyzed simultaneously by using the Wilson and Devinney (WD) code (1971, ApJ, 166, 605). The photometric solution indicates that CW Cas is a W-type W UMa system with a mass ratio of m2/m1 2.234, and that it is in a marginal contact state with a contact degree of ˜6.5% and a relatively large temperature difference of ˜327K between its two components. Based on the minimum times collected from the literature, together with the new ones obtained in this study, the orbital period changes of CW Cas were investigated in detail. It was found that a periodical variation overlaps with a secular period decrease in its orbital period. The long-term period decrease with a rate of dP/dt = -3.44 × 10-8d yr-1 can be interpreted either by mass transfer from the more-massive component to the less-massive with a rate of dm2/dt = -3.6 × 10-8M⊙ yr-1, or by mass and angular-momentum losses through magnetic braking due to a magnetic stellar wind. A low-amplitude cyclic variation with a period of T = 63.7 yr might be caused by the light-time effect due to the presence of a third body.

Incident light adjustable solar cell by periodic nanolens architecture

PubMed Central

Yun, Ju-Hyung; Lee, Eunsongyi; Park, Hyeong-Ho; Kim, Dong-Wook; Anderson, Wayne A.; Kim, Joondong; Litchinitser, Natalia M.; Zeng, Jinwei; Yi, Junsin; Kumar, M. Melvin David; Sun, Jingbo

2014-01-01

Could nanostructures act as lenses to focus incident light for efficient utilization of photovoltaics? Is it possible, in order to avoid serious recombination loss, to realize periodic nanostructures in solar cells without direct etching in a light absorbing semiconductor? Here we propose and demonstrate a promising architecture to shape nanolenses on a planar semiconductor. Optically transparent and electrically conductive nanolenses simultaneously provide the optical benefit of modulating the incident light and the electrical advantage of supporting carrier transportation. A transparent indium-tin-oxide (ITO) nanolens was designed to focus the incident light-spectrum in focal lengths overlapping to a strong electric field region for high carrier collection efficiency. The ITO nanolens effectively broadens near-zero reflection and provides high tolerance to the incident light angles. We present a record high light-conversion efficiency of 16.0% for a periodic nanostructured Si solar cell. PMID:25371099

Period Variation in BW Vulpeculae (Abstract)

NASA Astrophysics Data System (ADS)

Cowall, D. E.; Odell, A. P.

2018-06-01

(Abstract only) BW Vulpeculae (BW Vul) has the largest amplitude of the beta Cephei stars. An observing campaign on this star using the AAVSOnetís Bright Star Monitor (BSM) telescopes was begun in December of 2015 and has yielded 66 nights of observations to date. A period analysis will be presented using the BSM data set in combination with unpublished data from the Lowell Observatory. Over almost 80 years of observations, BW Vul has closely followed a parabolic ephemeris (period increasing by 2.4 seconds/century) plus a light-travel-time effect. This parabola with excursions on either side also could be viewed as a sequence of straight lines (constant period) with abrupt period increases. The first paradigm predicted a necessary change in slope around 2004, which did not occur. Instead, the period decreased abruptly in 2009. That maximum occurred 250 minutes early compared to the first paradigm, and about 25 minutes early compared to the straight-line paradigm from 1982ñ2009.

The 3.5 micron light curves of long period variable stars. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Strecker, D. W.

1973-01-01

Infrared observations at an effective wavelength of 3.5 microns of a selected group of long period variable (LPV) stars are presented. Mira type and semiregular stars of M, S, and C spectral classifications were monitored throughout the full cycle of variability. Although the variable infrared radiation does not exactly repeat in intensity or time, the regularity is sufficient to produce mean 3.5 micron light curves. The 3.5 micron maximum radiation lags the visual maximum by about one-seventh of a cycle, while the minimum 3.5 micron intensity occurs nearly one-half cycle after infrared maximum. In some stars, there are inflections or humps on the ascending portion of the 3.5 micron light curve which may also be seen in the visual variations.

The first photometric investigation and orbital period variation analysis of the W UMa type binary IK Bootis

NASA Astrophysics Data System (ADS)

Kriwattanawong, Wichean; Sanguansak, Nuanwan; Maungkorn, Sakdawoot

2017-08-01

With new CCD observations of the W UMa type binary IK Boo, we present the first investigation of photometric parameters and orbital period change. The BVRc light curve fit shows that IK Boo is a W-type contact system with a mass ratio of q = 1.146 and a shallow contact with a fill-out factor of f = 2.22%. The orbital period decrease was found to be a rate of -3.28 × 10-7 d yr-1, corresponding to a mass transfer from the more massive to the less massive component with a rate of -2.83 × 10-6 M⊙ yr-1. The inner and outer critical Roche lobes will contract and cause the contact degree to increase. Therefore, IK Boo may evolve into a deeper contact system. Furthermore, a possible cyclic variation was found with a period of 9.74 yr, which could be explained by the light-travel time effect due to the existence of a third companion in the system.

Eclipsing Binaries in the OGLE Variable Star Catalogs. V. Long-Period EB-Type Light Curve Systems in the Small Magellanic Cloud and the PLC-β Relation

NASA Astrophysics Data System (ADS)

Rucinski, Slavek M.; Maceroni, Carla

2001-01-01

Thirty-eight long-period (P>10 days) apparently contact binary stars discovered by the OGLE-II project in the SMC show EB-type light curves and an ``inverted'' period-color relation with longer orbital periods for redder systems. The strong light variations between eclipses can be explained within a semidetached model in which ellipsoidal variations of a large, evolved, Roche lobe-filling component dominates over eclipse effects in the systemic light changes. The model requires further spectroscopic and color-curve support before it can be fully accepted. It is noted that the dominant role of the Roche lobe-filling component in the total systemic luminosity can explain the new period-luminosity-color (PLC) relation, which has been established for the long-period EB (LP-EB) systems. We call it the PLC-β relation, to distinguish it from the Cepheid relation. Two versions of the PLC-β relation-based on the (B-V)0 or (V-I)0 color indices-have been calibrated for 33 systems with (V-I)0>0.25 spanning the orbital period range of 11 to 181 days (it was found that blue systems with (V-I)0<=0.25 do not follow the same calibration). The relations can provide maximum-light, absolute-magnitude estimates accurate to ɛMV~=0.35 mag within the approximate range -3light variations make these binaries very easy to spot in nearby galaxies, so that the PLC-β relation can offer an auxiliary and entirely independent method of distance determination to nearby stellar systems rich in massive stars.

Arctic tree rings as recorders of variations in light availability

PubMed Central

Stine, A. R.; Huybers, P.

2014-01-01

Annual growth ring variations in Arctic trees are often used to reconstruct surface temperature. In general, however, the growth of Arctic vegetation is limited both by temperature and light availability, suggesting that variations in atmospheric transmissivity may also influence tree-ring characteristics. Here we show that Arctic tree-ring density is sensitive to changes in light availability across two distinct phenomena: explosive volcanic eruptions (P<0.01) and the recent epoch of global dimming (P<0.01). In each case, the greatest response is found in the most light-limited regions of the Arctic. Essentially no late 20th century decline in tree-ring density relative to temperature is seen in the least light-limited regions of the Arctic. Consistent results follow from analysis of tree-ring width and from individually analysing each of seven tree species. Light availability thus appears an important control, opening the possibility for using tree rings to reconstruct historical changes in surface light intensity. PMID:24805143

Very preterm infants can detect small variations in light levels in incubators.

PubMed

Zores, Claire; Dufour, André; Pebayle, Thierry; Langlet, Claire; Astruc, Dominique; Kuhn, Pierre

2015-10-01

This prospective observational study was designed to improve our understanding of the responses of very preterm infants to light level variations in incubators and to evaluate what determined those reactions. The physiological responses of 27 very preterm infants were analysed following variations in the light level environments of their incubators over 10 hours. Heart and respiratory rates, systemic oxygen saturation and regional cerebral oxygen saturations were recorded using near-infrared spectroscopy, and the variation of each parameter was analysed. We analysed 332 light level changes. Heart rate increased by 3.8 beats per minute (range -2.6 to 12.6), respiratory rate by six cycles per minute (-1.5 to 26) and regional cerebral oxygen saturation by 1.1% (-0.5% to 3.9%) (p < 0.05 each) when delta lux was over 50. Only respiratory rate decreased significantly, by -8.4 cycles per minute (-28 to -0.4), when delta lux was 50 or lower (p < 0.05). The initial level of illumination altered the very preterm infants' responses, with higher reactivity for higher ambient light levels. Very preterm infants reacted to moderate variations in illumination in their incubator, within recommended ranges of light levels, suggesting that they may detect even small light level variations. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

Periodic spectrum variations in helium-rich stars

NASA Technical Reports Server (NTRS)

Walborn, N. R.

1982-01-01

Spectroscopic observations of four helium-rich stars are presented. In HD 37776, antiphase variations of Si III and He I have been found, which represent another point of similarity to the Ap phenomenon. The remarkable H-alpha emission variations in Sigma Ori E are illustrated with uniform phase coverage, and strict periodicity over a five-year interval is shown. A radial-velocity study of HD 64740 shows constancy to within the accuracy of the observations. Finally, Delta Ori B is confirmed as a helium-rich star.

Geographical variation in the periodicity of gypsy moth outbreaks

Treesearch

Derek M. Johnson; Andrew M. Liebhold; Ottar N. Bj& #248rnstad

2006-01-01

The existence of periodic oscillations in populations of forest Lepidoptera is well known. While information exists on how the periods of oscillations vary among different species, there is little prior evidence of variation in periodicity within the range of a single Lepidopteran species. The exotic gypsy moth is an introduced foliage-feeding insect in North America....

Effects of periodic photoinhibitory light exposure on physiology and productivity of Arabidopsis plants grown under low light.

PubMed

Tian, Yonglan; Sacharz, Joanna; Ware, Maxwell A; Zhang, Huayong; Ruban, Alexander V

2017-07-10

This work examined the long-term effects of periodic high light stress on photosynthesis, morphology, and productivity of low-light-acclimated Arabidopsis plants. Significant photoinhibition of Arabidopsis seedlings grown under low light (100 μmol photons m-2 s-1) was observed at the beginning of the high light treatment (three times a day for 30 min at 1800 μmol photons m-2 s-1). However, after 2 weeks of treatment, similar photosynthesis yields (Fv/Fm) to those of control plants were attained. The daily levels of photochemical quenching measured in the dark (qPd) indicated that the plants recovered from photoinhibition within several hours once transferred back to low light conditions, with complete recovery being achieved overnight. Acclimation to high light stress resulted in the modification of the number, structure, and position of chloroplasts, and an increase in the average chlorophyll a/b ratio. During ontogenesis, high-light-exposed plants had lower total leaf areas but higher above-ground biomass. This was attributed to the consumption of starch for stem and seed production. Moreover, periodic high light exposure brought forward the reproductive phase and resulted in higher seed yields compared with control plants grown under low light. The responses to periodic high light exposure of mature Arabidopsis plants were similar to those of seedlings but had higher light tolerance. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

The interpretation of optical light variations of Centaurus X-3

NASA Technical Reports Server (NTRS)

Mauder, H.

1976-01-01

The interpretation of optical light variations of X-ray binaries is discussed for the case of negligible reflection effect. The limiting cases of synchronous rotation of the visible star (Roche configuration) and of no rotation (pure tidal deformation) are considered. The theoretical results are compared with the available light curves of Cen X-3. X-ray data of the Copernicus satellite are used to get an impression of the atmospheric structure of the outer layers of the visible component. It is shown, that the X-ray eclipse duration is in good agreement with the mass ration derived from the optical variations. The X-ray eclipse duration is discussed with respect to the extended low states, and a possible correlation of the extended lows with the appearance of the optical light curves is considered.

Solar wind variations in the 60-100 year period range: A review

NASA Technical Reports Server (NTRS)

Feynman, J.

1983-01-01

The evidence for and against the reality of a solar wind variation in the period range of 60-100 years is reexamined. Six data sets are reviewed; sunspot numbers, geomagnetic variations, two auroral data sets and two (14)C data sets. These data are proxies for several different aspects of the solar wind and the presence or absence of 60-100 year cyclic behavior in a particular data set does not necessarily imply the presence or absence of this variation in other sets. It was concluded that two different analyses of proxy data for a particular characteristic of the heliospheric solar wind yielded conflicting results. This conflict can be resolved only by future research. It is also definitely confirmed that proxy data for the solar wind in the ecliptic at 1 A.U. undergo a periodic variation with a period of approximately 87 years. The average amplitude and phase of this variation as seen in eleven cycles of proxy data are presented.

Daily Light Exposure Patterns Reveal Phase and Period of the Human Circadian Clock.

PubMed

Woelders, Tom; Beersma, Domien G M; Gordijn, Marijke C M; Hut, Roelof A; Wams, Emma J

2017-06-01

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. This approach also yields an estimated circadian period of 24.2 h (SD = 0.2 h), with longer periods resulting in later DLMOs. A larger amount of daylight exposure resulted in an earlier DLMO. Individuals with a long circadian period also showed shorter intervals between DLMO and sleep timing. When a field-based estimation of tau can be validated under laboratory studies in a wide variety of individuals, the proposed methods may prove to be essential tools for individualized chronotherapy and light treatment for shift work and jetlag applications. These methods may improve our understanding of fundamental properties of human circadian rhythms under daily living conditions.

Using Machine Learning To Predict Which Light Curves Will Yield Stellar Rotation Periods

NASA Astrophysics Data System (ADS)

Agüeros, Marcel; Teachey, Alexander

2018-01-01

Using time-domain photometry to reliably measure a solar-type star's rotation period requires that its light curve have a number of favorable characteristics. The probability of recovering a period will be a non-linear function of these light curve features, which are either astrophysical in nature or set by the observations. We employ standard machine learning algorithms (artificial neural networks and random forests) to predict whether a given light curve will produce a robust rotation period measurement from its Lomb-Scargle periodogram. The algorithms are trained and validated using salient statistics extracted from both simulated light curves and their corresponding periodograms, and we apply these classifiers to the most recent Intermediate Palomar Transient Factory (iPTF) data release. With this pipeline, we anticipate measuring rotation periods for a significant fraction of the ∼4x108 stars in the iPTF footprint.

Influence of the variation potential on photosynthetic flows of light energy and electrons in pea.

PubMed

Sukhova, Ekaterina; Mudrilov, Maxim; Vodeneev, Vladimir; Sukhov, Vladimir

2018-05-01

Local damage (mainly burning, heating, and mechanical wounding) induces propagation of electrical signals, namely, variation potentials, which are important signals during the life of plants that regulate different physiological processes, including photosynthesis. It is known that the variation potential decreases the rate of CO 2 assimilation by the Calvin-Benson cycle; however, its influence on light reactions has been poorly investigated. The aim of our work was to investigate the influence of the variation potential on the light energy flow that is absorbed, trapped and dissipated per active reaction centre in photosystem II and on the flow of electrons through the chloroplast electron transport chain. We analysed chlorophyll fluorescence in pea leaves using JIP-test and PAM-fluorometry; we also investigated delayed fluorescence. The electrical signals were registered using extracellular electrodes. We showed that the burning-induced variation potential stimulated a nonphotochemical loss of energy in photosystem II under dark conditions. It was also shown that the variation potential gradually increased the flow of light energy absorbed, trapped and dissipated by photosystem II. These changes were likely caused by an increase in the fraction of absorbed light distributed to photosystem II. In addition, the variation potential induced a transient increase in electron flow through the photosynthetic electron transport chain. Some probable mechanisms for the influence of the variation potential on the light reactions of photosynthesis (including the potential role of intracellular pH decrease) are discussed in the work.

Masking responses to light in period mutant mice.

PubMed

Pendergast, Julie S; Yamazaki, Shin

2011-10-01

Masking is an acute effect of an external signal on an overt rhythm and is distinct from the process of entrainment. In the current study, we investigated the phase dependence and molecular mechanisms regulating masking effects of light pulses on spontaneous locomotor activity in mice. The circadian genes, Period1 (Per1) and Per2, are necessary components of the timekeeping machinery and entrainment by light appears to involve the induction of the expression of Per1 and Per2 mRNAs in the suprachiasmatic nuclei (SCN). We assessed the roles of the Per genes in regulating masking by assessing the effects of light pulses on nocturnal locomotor activity in C57BL/6J Per mutant mice. We found that Per1(-/-) and Per2(-/-) mice had robust negative masking responses to light. In addition, the locomotor activity of Per1(-/-)/Per2(-/-) mice appeared to be rhythmic in the light-dark (LD) cycle, and the phase of activity onset was advanced (but varied among individual mice) relative to lights off. This rhythm persisted for 1 to 2 days in constant darkness in some Per1(-/-)/Per2(-/-) mice. Furthermore, Per1(-/-)/Per2(-/-) mice exhibited robust negative masking responses to light. Negative masking was phase dependent in wild-type mice such that maximal suppression was induced by light pulses at zeitgeber time 14 (ZT14) and gradually weaker suppression occurred during light pulses at ZT16 and ZT18. By measuring the phase shifts induced by the masking protocol (light pulses were administered to mice maintained in the LD cycle), we found that the phase responsiveness of Per mutant mice was altered compared to wild-types. Together, our data suggest that negative masking responses to light are robust in Per mutant mice and that the Per1(-/-)/Per2(-/-) SCN may be a light-driven, weak/damping oscillator.

Daily Light Exposure Patterns Reveal Phase and Period of the Human Circadian Clock

PubMed Central

Woelders, Tom; Beersma, Domien G. M.; Gordijn, Marijke C. M.; Hut, Roelof A.; Wams, Emma J.

2017-01-01

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. This approach also yields an estimated circadian period of 24.2 h (SD = 0.2 h), with longer periods resulting in later DLMOs. A larger amount of daylight exposure resulted in an earlier DLMO. Individuals with a long circadian period also showed shorter intervals between DLMO and sleep timing. When a field-based estimation of tau can be validated under laboratory studies in a wide variety of individuals, the proposed methods may prove to be essential tools for individualized chronotherapy and light treatment for shift work and jetlag applications. These methods may improve our understanding of fundamental properties of human circadian rhythms under daily living conditions. PMID:28452285

Detection of Possible Quasi-periodic Oscillations in the Long-term Optical Light Curve of the BL Lac Object OJ 287

NASA Astrophysics Data System (ADS)

Bhatta, G.; Zola, S.; Stawarz, Ł.; Ostrowski, M.; Winiarski, M.; Ogłoza, W.; Dróżdż, M.; Siwak, M.; Liakos, A.; Kozieł-Wierzbowska, D.; Gazeas, K.; Debski, B.; Kundera, T.; Stachowski, G.; Paliya, V. S.

2016-11-01

The detection of periodicity in the broadband non-thermal emission of blazars has so far been proven to be elusive. However, there are a number of scenarios that could lead to quasi-periodic variations in blazar light curves. For example, an orbital or thermal/viscous period of accreting matter around central supermassive black holes could, in principle, be imprinted in the multi-wavelength emission of small-scale blazar jets, carrying such crucial information about plasma conditions within the jet launching regions. In this paper, we present the results of our time series analysis of the ˜9.2 yr long, and exceptionally well-sampled, optical light curve of the BL Lac object OJ 287. The study primarily used the data from our own observations performed at the Mt. Suhora and Kraków Observatories in Poland, and at the Athens Observatory in Greece. Additionally, SMARTS observations were used to fill some of the gaps in the data. The Lomb-Scargle periodogram and the weighted wavelet Z-transform methods were employed to search for possible quasi-periodic oscillations in the resulting optical light curve of the source. Both methods consistently yielded a possible quasi-periodic signal around the periods of ˜400 and ˜800 days, the former with a significance (over the underlying colored noise) of ≥slant 99 % . A number of likely explanations for this are discussed, with preference given to a modulation of the jet production efficiency by highly magnetized accretion disks. This supports previous findings and the interpretation reported recently in the literature for OJ 287 and other blazar sources.

Laser-induced periodic structures for light extraction efficiency enhancement of GaN-based light emitting diodes.

PubMed

Chen, Jiun-Ting; Lai, Wei-Chih; Kao, Yu-Jui; Yang, Ya-Yu; Sheu, Jinn-Kong

2012-02-27

The laser-induced periodic surface structure technique was used to form simultaneously dual-scale rough structures (DSRS) with spiral-shaped nanoscale structure inside semi-spherical microscale holes on p-GaN surface to improve the light-extraction efficiency of light-emitting diodes (LEDs). The light output power of DSRS-LEDs was 30% higher than that of conventional LEDs at an injection current of 20 mA. The enhancement in the light output power could be attributed to the increase in the probability of photons to escape from the increased surface area of textured p-GaN surface.

Periodicity Analysis of X-ray Light Curves of SS 433

NASA Astrophysics Data System (ADS)

Wang, Jun-yi; Lu, Xiang-long; Zhao, Qiu-wen; Dong, Dian-qiao; Lao, Bao-qiang; Lu, Yang; Wei, Yan-heng; Wu, Xiao-cong; An, Tao

2017-01-01

SS 433 is sofar the unique X-ray binary that has the simultaneously detected orbital period, super-orbital period, and nutation period, as well as a bidirectional spiral jet. The study on its X-ray light variability is helpful for understanding the dynamic process of the system, and the correlations between the different wavebands. In this paper, two time-series analysis techniques, i.e., the Lomb-Scargle periodogram and weighted wavelet Z-transform, are employed to search for the periods in the Swift/BAT (Burst Alert Telescope) (15-50 keV) and RXTE/ASM (Rose X-ray Timing Explorer/All Sky Monitor) (1.5-3, 3- 4, and 5-12 keV) light curves of SS 433, and the Monte Carlo simulation is performed for the obtained periodical components. For the 15-50 keV energy band, five significant periodical components are detected, which are P1(∼6.29 d), P2 (∼6.54 d), P3 (∼13.08 d), P4 (∼81.50 d), and P5 (∼162.30 d). For the 3-5 and 5-12 keV energy bands, the periodical components P3 (∼13 d) and P5 (∼162 d) are detected in both energy bands. However, for the 1.5-3 keV energy band, no significant periodic signal is detected. P5 is the strongest periodic signal in the power spectrum for all the energy bands of 3-5, 5-12, and 15-50 keV, and it is consistent with the previous result obtained from the study of optical light curves. Furthermore, in combination with the radio spiral jet of SS 433, it is suggested that the X-ray and optical variability of P5 (∼162 d) is probably related to the precession of its relativistic jet. The high correlation between the X-ray and optical light curves may also imply that the X-ray and optical radiations are of the same physical origin. P3 shows a good agreement with the orbital period (∼13.07 d) obtained by the previous study, and P2 and P4 are respectively the high-frequency harmonics of P3 and P5. P1 is detected only in the power spectrum of the 15-50 keV energy band, and it is consistent with the nutation period of the system. As

Simulations of light effects on the human circadian pacemaker: implications for assessment of intrinsic period

NASA Technical Reports Server (NTRS)

Klerman, E. B.; Dijk, D. J.; Kronauer, R. E.; Czeisler, C. A.

1996-01-01

The sensitivity of the human circadian system to light has been the subject of considerable debate. Using computer simulations of a recent quantitative model for the effects of light on the human circadian system, we investigated these effects of light during different experimental protocols. The results of the simulations indicate that the nonuniform distribution over the circadian cycle of exposure to ordinary room light seen in classical free-run studies, in which subjects select their exposure to light and darkness, can result in an observed period of approximately 25 h, even when the intrinsic period of the subject's endogenous circadian pacemaker is much closer to 24 h. Other simulation results suggest that accurate assessment of the true intrinsic period of the human circadian pacemaker requires low ambient light intensities (approximately 10-15 lx) during scheduled wake episodes, desynchrony of the imposed light-dark cycle from the endogenous circadian oscillator, and a study length of at least 20 days. Although these simulations await further experimental substantiation, they highlight the sensitivity to light of the human circadian system and the potential confounding influence of light on the assessment of the intrinsic period of the circadian pacemaker.

Quasi-periodic variations in x-ray emission and long-term radio observations: Evidence for a two-component jet in Sw J1644+57

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jiu-Zhou; Lei, Wei-Hua; Wang, Ding-Xiong

2014-06-10

The continued observations of Sw J1644+57 in X-ray and radio bands accumulated a rich data set to study the relativistic jet launched in this tidal disruption event. The X-ray light curve of Sw J1644+57 from 5-30 days presents two kinds of quasi-periodic variations: a 200 s quasi-periodic oscillation (QPO) and a 2.7 day quasi-periodic variation. The latter has been interpreted by a precessing jet launched near the Bardeen-Petterson radius of a warped disk. Here we suggest that the ∼200 s QPO could be associated with a second, narrower jet sweeping the observer line-of-sight periodically, which is launched from a spinningmore » black hole in the misaligned direction with respect to the black hole's angular momentum. In addition, we show that this two-component jet model can interpret the radio light curve of the event, especially the re-brightening feature starting ∼100 days after the trigger. From the data we infer that inner jet may have a Lorentz factor of Γ{sub j} ∼ 5.5 and a kinetic energy of E {sub k,} {sub iso} ∼ 3.0 × 10{sup 52} erg, while the outer jet may have a Lorentz factor of Γ{sub j} ∼ 2.5 and a kinetic energy of E{sub k,} {sub iso} ∼ 3.0 × 10{sup 53} erg.« less

The Long-term Light Curves of X-ray Binaries Contain Simultaneous Periodic and Random Components

NASA Technical Reports Server (NTRS)

White, Nicholas E. (Technical Monitor); Boyd, Patricia T.; Smale, Alan P.

2002-01-01

LMC X-3 and Cyg X-2 show large amplitude X-ray fluctuations that have been attributed to a warped accretion disk. Cyg X-3 displays high amplitude, apparently non-periodic oscillations. We reanalyze these systems using RXTE ASM data and time-frequency decomposition techniques. We find that the long-term variations in Cyg X-2 can be completely characterized by excursions whose durations are integer multiples of the orbital period, including one essentially identical to the reported "period" of 78 days. Cyg X-3 can be characterized in terms of integer multiples of a 71-day fundamental period unrelated to the 4.8 day orbital period, but suggestively close to the approximately equal to greater than 60 day reported precession period of the relativistic jet inferred from recent radio observations. The long-term excursions of LMC X-3 are related to each other by rational fractions, suggesting the characteristic time scale is 10.594 days, shorter than any observed excursion to date. We explore the phase space evolution of the light curves using a natural embedding and find that all three systems possess two rotation centers that organize the phase space trajectories, one of low luminosity and the other of high luminosity. The implications of this repeatable behavior on generic models of accretion disk dynamics and mass transfer variability are explored.

Long-term variation analysis of a tropical river's annual streamflow regime over a 50-year period

NASA Astrophysics Data System (ADS)

Seyam, Mohammed; Othman, Faridah

2015-07-01

Studying the long-term changes of streamflow is an important tool for enhancing water resource and river system planning, design, and management. The aim of this work is to identify the long-term variations in annual streamflow regime over a 50-year period from 1961 to 2010 in the Selangor River, which is one of the main tropical rivers in Malaysia. Initially, the data underwent preliminary independence, normality, and homogeneity testing using the Pearson correlation coefficient and Shapiro-Wilk and Pettitt's tests, respectively. The work includes a study and analysis of the changes through nine variables describing the annual streamflow and variations in the yearly duration of high and low streamflows. The analyses were conducted via two time scales: yearly and sub-periodic. The sub-periods were obtained by segmenting the 50 years into seven sub-periods by two techniques, namely the change-point test and direct method. Even though analysis revealed nearly negligible changes in mean annual flow over the study period, the maximum annual flow generally increased while the minimum annual flow significantly decreased with respect to time. It was also observed that the variables describing the dispersion in streamflow continually increased with respect to time. An obvious increase was detected in the yearly duration of danger level of streamflow, a slight increase was noted in the yearly duration of warning and alert levels, and a slight decrease in the yearly duration of low streamflow was found. The perceived changes validate the existence of long-term changes in annual streamflow regime, which increase the probability of floods and droughts occurring in future. In light of the results, attention should be drawn to developing water resource management and flood protection plans in order to avert the harmful effects potentially resulting from the expected changes in annual streamflow regime.

A technique to detect periodic and non-periodic ultra-rapid flux time variations with standard radio-astronomical data

NASA Astrophysics Data System (ADS)

Borra, Ermanno F.; Romney, Jonathan D.; Trottier, Eric

2018-06-01

We demonstrate that extremely rapid and weak periodic and non-periodic signals can easily be detected by using the autocorrelation of intensity as a function of time. We use standard radio-astronomical observations that have artificial periodic and non-periodic signals generated by the electronics of terrestrial origin. The autocorrelation detects weak signals that have small amplitudes because it averages over long integration times. Another advantage is that it allows a direct visualization of the shape of the signals, while it is difficult to see the shape with a Fourier transform. Although Fourier transforms can also detect periodic signals, a novelty of this work is that we demonstrate another major advantage of the autocorrelation, that it can detect non-periodic signals while the Fourier transform cannot. Another major novelty of our work is that we use electric fields taken in a standard format with standard instrumentation at a radio observatory and therefore no specialized instrumentation is needed. Because the electric fields are sampled every 15.625 ns, they therefore allow detection of very rapid time variations. Notwithstanding the long integration times, the autocorrelation detects very rapid intensity variations as a function of time. The autocorrelation could also detect messages from Extraterrestrial Intelligence as non-periodic signals.

Spectral variations of the symbiotic star V407 Cygni around light maximum of the secondary Mira variable in 2012

NASA Astrophysics Data System (ADS)

Iijima, T.; Naito, H.

2017-04-01

Context. The outburst of the symbiotic recurrent nova V407 Cyg in 2010 has been studied by numerous authors. On the other hand, its spectral variations in the quiescent stage have not been well studied yet. This paper is probably the first report for the relation between the pulsation of the secondary Mira variable and the temperature of the primary hot component for V407 Cyg. Aims: The spectral variation in the post-outburst stage has been monitored to study the properties of this object. In the course of this work, we found some unexpected spectral variations around the light maximum of the secondary Mira variable in 2012. The relation between the mass transfer in the binary system and the pulsation of the secondary Mira variable is studied. Methods: High- and low-resolution optical spectra obtained at the Astronomical Observatories at Asiago were used. The photometric data depend on the database of the VSNET. Results: The secondary Mira variable reached its light maximum in 2012, when an absorption spectrum of a late-M-type giant developed and the emission line of Hδ became stronger than those of Hβ and Hγ, which are typical spectral features of Mira variables at light maxima. On the other hand, intensity ratios to Hβ of the emission lines of He I, He II, [Fe VII], etc., which obviously depended on the temperature of the hot component, rapidly varied around the light maximum. The intensity ratios started to decrease at phase about 0.9 of the periodical light variation of the Mira variable. This phenomenon suggests that the mass transfer rate, as well as the mass accretion rate onto the hot component, decreased according to the contraction of the Mira variable. However, these intensity ratios somewhat recovered just on the light maximum: phase 0.99. There might have occurred a temporal mass loss from the Mira variable at that time. The intensity ratios decreased again after the light maximum, then recovered and returned to the normal level at phase about 0

Variable classification in the LSST era: exploring a model for quasi-periodic light curves

NASA Astrophysics Data System (ADS)

Zinn, J. C.; Kochanek, C. S.; Kozłowski, S.; Udalski, A.; Szymański, M. K.; Soszyński, I.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Skowron, J.; Mróz, P.; Pawlak, M.

2017-06-01

The Large Synoptic Survey Telescope (LSST) is expected to yield ˜107 light curves over the course of its mission, which will require a concerted effort in automated classification. Stochastic processes provide one means of quantitatively describing variability with the potential advantage over simple light-curve statistics that the parameters may be physically meaningful. Here, we survey a large sample of periodic, quasi-periodic and stochastic Optical Gravitational Lensing Experiment-III variables using the damped random walk (DRW; CARMA(1,0)) and quasi-periodic oscillation (QPO; CARMA(2,1)) stochastic process models. The QPO model is described by an amplitude, a period and a coherence time-scale, while the DRW has only an amplitude and a time-scale. We find that the periodic and quasi-periodic stellar variables are generally better described by a QPO than a DRW, while quasars are better described by the DRW model. There are ambiguities in interpreting the QPO coherence time due to non-sinusoidal light-curve shapes, signal-to-noise ratio, error mischaracterizations and cadence. Higher order implementations of the QPO model that better capture light-curve shapes are necessary for the coherence time to have its implied physical meaning. Independent of physical meaning, the extra parameter of the QPO model successfully distinguishes most of the classes of periodic and quasi-periodic variables we consider.

Survey of the BY Draconis syndrome among dMe stars. [BVr photometry search for slow quasisinusoidal light variations

NASA Technical Reports Server (NTRS)

Bopp, B. W.; Espenak, F.

1977-01-01

Results are reported for a BVr photometric survey of 22 dK, dKe, dM, and dMe stars conducted to search for slow quasi-sinusoidal fluctuations in V (the BY Draconis syndrome). The (B-V) and (V-r) color indices are determined in an attempt to detect wavelength-dependent color changes produced by starspots and to infer starspot temperatures. It is found that nine of the stars exhibit variations in V of the order of 0.05 to 0.10 magnitude on a time scale of days or weeks, that at least three more display changes in mean light level over a period of years, that the stars generally tend to become redder at minimum light, and that some of the stars show no detectable color changes over their photometric cycle. The color data are taken to suggest a probable temperature difference of about 200 to 500 K between the stellar photospheres and starspots if the V variations are attributed to dark spots. It is concluded that the BY Draconis syndrome is clearly a very common occurrence among dMe stars.

Photometry of the long period dwarf nova GY Hya

NASA Astrophysics Data System (ADS)

Bruch, Albert; Monard, Berto

2017-08-01

Although comparatively bright, the cataclysmic variable GY Hya has not attracted much attention in the past. As part of a project to better characterize such systems photometrically, we observed light curves in white light, each spanning several hours, at Bronberg Observatory, South Africa, in 2004 and 2005, and at the Observatório do Pico dos Dias, Brazil, in 2014 and 2016. These data permit to study orbital modulations and their variations from season to season. The orbital period, already known from spectroscopic observations of Peters and Thorstensen (2005), is confirmed through strong ellipsoidal variations of the mass donor star in the system and the presence of eclipses of both components. A refined period of 0.34723972 (6) days and revised ephemeries are derived. Seasonal changes in the average orbital light curve can qualitatively be explained by variations of the contribution of a hot spot to the system light together with changes of the disk radius. The amplitude of the ellipsoidal variations and the eclipse contact phases permit to put some constraints on the mass ratio, orbital inclination and the relative brightness of the primary and secondary components. There are some indications that the disk radius during quiescence, expressed in units of the component separation, is smaller than in other dwarf novae.

Light-dependent leaf trait variation in 43 tropical dry forest tree species.

PubMed

Markesteijn, Lars; Poorter, Lourens; Bongers, Frans

2007-04-01

Our understanding of leaf acclimation in relation to irradiance of fully grown or juvenile trees is mainly based on research involving tropical wet forest species. We studied sun-shade plasticity of 24 leaf traits of 43 tree species in a Bolivian dry deciduous forest. Sampling was confined to small trees. For each species, leaves were taken from five of the most and five of the least illuminated crowns. Trees were selected based on the percentage of the hemisphere uncovered by other crowns. We examined leaf trait variation and the relation between trait plasticity and light demand, maximum adult stature, and ontogenetic changes in crown exposure of the species. Leaf trait variation was mainly related to differences among species and to a minor extent to differences in light availability. Traits related to the palisade layer, thickness of the outer cell wall, and N(area) and P(area) had the greatest plasticity, suggesting their importance for leaf function in different light environments. Short-lived pioneers had the highest trait plasticity. Overall plasticity was modest and rarely associated with juvenile light requirements, adult stature, or ontogenetic changes in crown exposure. Dry forest tree species had a lower light-related plasticity than wet forest species, probably because wet forests cast deeper shade. In dry forests light availability may be less limiting, and low water availability may constrain leaf trait plasticity in response to irradiance.

Temporal Variation in Oscillatory Characteristics of Long-period Tremor at Aso Volcano, Japan.

NASA Astrophysics Data System (ADS)

Yamamoto, M.; Ohkura, T.; Kaneshima, S.; Kawakatsu, H.

2017-12-01

At Aso volcano, Japan, various kinds of volcanic signals with broad frequency contents have been observed since 1930s. One of these signals is long-period tremor (LPT) with a dominant period of around 15 s, which is intermittently emitted from the volcano regardless of the surface activity. Our broadband seismic observations have revealed that LPTs are a kind of resonance oscillation of a crack-like conduit beneath the crater. In this study, aiming to detect a temporal variation of volcanic system, we analyze the long-term variation of LPTs from 1994 to the present.We first examine the temporal variation of dominant periods of LPTs (fundamental mode of around 15 s and the first overtone of around 7 s) using the continuous data recorded at broadband stations close to the active crater. The result shows a clear temporal change in the dominant periods of LPTs in 2003-2005 and 2014-2015. In 2003-2005, the periods of the two modes show correlated temporal change, and it can be interpreted as compositional and/or thermal change of hydrothermal fluids. On the other hand, in 2014-2015, the period of first overtone is almost constant at around 8 s, while that of the fundamental mode shows relatively large temporal fluctuations between 16 s and 12 s. To explain the different behavior among the two resonant modes, we examine the oscillatory characteristics of a fluid-filled crack having linearly varying thickness. With this model, we find that the ratio between resonance periods becomes smaller than that in the case of a flat crack having constant thickness. This behavior can be understood by considering the effective thickness of the crack depends on the wavelength of each resonant mode. Based on these results, the different temporal variation of dominant periods can be interpreted by depth-dependent thickness of the crack-like conduit which may be caused by pressurization and/or intrusion of magma at deeper portion of the conduit. These results suggest the importance of

Quasi-Periodic Long-Term Quadrature Light Variability in Early Type Interacting Binary Systems

NASA Astrophysics Data System (ADS)

Peters, Geraldine Joan

2015-08-01

Four years of Kepler observations have revealed a class of Algol-type binaries in which the relative brightness of the quadrature light varies from > 1 to <1 on a time scale of about 100-400 days. The behavior pattern is quasi-periodic. We call these systems L/T (leading hemisphere/ trailing hemisphere) variables. Although L/T inequality in eclipsing binaries has been noted from ground-based photometry by several observers since the early 1950s, the regular or quasi-regular switching between maxima is new. Twenty L/T systems have so far been found in the Kepler database and at least three classes of L/T behavior have been identified. In this presentation I will give an update on the L/T phenomenon gleaned from the Kepler and K2 databases. The Kepler and K2 light curves are being analyzed with the 2015 version of the Wilson-Devinney (WD) program that includes major improvements in modeling star spots (i.e. spot motions due to drift and stellar rotation and spot growth and decay). The prototype L/T variable is WX Draconis (A8V + K0IV, P=1.80 d) which shows L/ T light variations of 2-3%. The primary is a delta Scuti star with a dominant pulsation period of 41 m. Preliminary analysis of the WX Dra data suggests that the L/T variability can be fit with either an accretion hot spot on the primary (T = 2.3 Tphot) that jumps in longitude or a magnetic cool spotted region on the secondary. If the latter model is correct the dark region must occupy at least 20% of the surface of the facing hemisphere of the secondary if it is completely black, or a larger area if not completely black. In both hot and cool spot scenarios magnetic fields must play a role in the activity. Support from NASA grants NNX11AC78G and NNX12AE44G and USC’s Women in Science and Engineering (WiSE) program is greatly appreciated.

Light curve variations of the eclipsing binary V367 Cygni

NASA Astrophysics Data System (ADS)

Akan, M. C.

1987-07-01

The long-period eclipsing binary star V367 Cygni has been observed photoelectrically in two colours, B and V, in 1984, 1985, and 1986. These new light curves of the system have been discussed and compared for the light-variability with the earlier ones presented by Heiser (1962). Using some of the previously published photoelectric light curves and the present ones, several primary minima times have been derived to calculate the light elements. Any attempt to obtain a photometric solution of the binary is complicated by the peculiar nature of the light curve caused by the presence of the circumstellar matter in the system. Despite this difficulty, however, some approaches are being carried out to solve the light curves which are briefly discussed.

Long-Period Tidal Variations in the Length of Day

NASA Technical Reports Server (NTRS)

Ray, Richard D.; Erofeeva, Svetlana Y.

2014-01-01

A new model of long-period tidal variations in length of day is developed. The model comprises 80 spectral lines with periods between 18.6 years and 4.7 days, and it consistently includes effects of mantle anelasticity and dynamic ocean tides for all lines. The anelastic properties followWahr and Bergen; experimental confirmation for their results now exists at the fortnightly period, but there remains uncertainty when extrapolating to the longest periods. The ocean modeling builds on recent work with the fortnightly constituent, which suggests that oceanic tidal angular momentum can be reliably predicted at these periods without data assimilation. This is a critical property when modeling most long-period tides, for which little observational data exist. Dynamic ocean effects are quite pronounced at shortest periods as out-of-phase rotation components become nearly as large as in-phase components. The model is tested against a 20 year time series of space geodetic measurements of length of day. The current international standard model is shown to leave significant residual tidal energy, and the new model is found to mostly eliminate that energy, with especially large variance reduction for constituents Sa, Ssa, Mf, and Mt.

First photometric analysis of magnetic activity and orbital period variations for the semi-detached binary BU Vulpeculae

NASA Astrophysics Data System (ADS)

Wang, Jingjing; Zhang, Bin; Yu, Jing; Liu, Liang; Tian, Xiaoman

2018-06-01

Four sets of multi-color CCD photometric observations of the close binary BU Vul were carried out for four successive months in 2010. From our observations, there are obvious variations and asymmetry of light curves on the timescale of a month, indicating high-level stellar spot activity on the surface of at least one component. The Wilson-Devinney (2010) program was used to determine the photometric solutions, which suggest that BU Vul is a semi-detached binary with the cool, less massive component filling with the critical Roche lobe. The solutions also reveal that the spots on the primary and the secondary have changed and drifted in 2010 July, August, and September. Based on analysis of the O - C curves of BU Vul, its orbital period shows a cyclic oscillation (T3 = 22.4 yr, A3 = 0.0029 d) superimposed on a secular increase. The continuous increase is possibly a result of mass transfer from the less massive component to the more massive one at a rate of dM/dt = -2.95 × 10-9 M⊙ yr-1. The cyclic variation maybe be caused by the presence of a tertiary companion with extremely low luminosity. Combined with the distortions of the light curve on 2009 November 4, we infer that BU Vul has two additional companions in a quadruple system.

Period changes of two contact binaries: DF Hya and WZ And

NASA Astrophysics Data System (ADS)

Bulut, A.; Bulut, I.

2018-02-01

Orbital period variations of two contact binaries DF Hya and WZ And are analyzed with the least-squares method by using all available minima times. It is shown that the period variations of these systems are due mainly to the Light-Time Effect (LITE) due originates from gravitational influence of a third body. New LITE elements such as, orbital periods and minimum masses of possibility third bodies are given.

Extraordinary variation of pump light intensity inside a four-level solid-state laser medium

NASA Astrophysics Data System (ADS)

Qin, Hua; Fu, Rulian; Wang, Zhaoqi; Liu, Juan

2008-08-01

A theoretical investigation of the absorption of the pump light at different intensities through a four-level solid-state laser medium is presented. It is found that the variation of the pump intensity inside the laser medium cannot always simply be dominated by Beer's law. Transmission of the pump light through this laser medium is closely related to the pump intensity itself. In fact, when the pump intensity is relatively low, whose values depend on the characteristics of the medium, the variation of the pump light through the laser medium is consistent with Beer's law. However, while the pump intensity is high enough, the relationship between the transmission of the pump light and its propagation distance is demonstrated to be linear. These theoretical results have been confirmed by the experiment with a medium of YAG:Nd.

Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity

NASA Astrophysics Data System (ADS)

Hatzes, A. P.; Cochran, W. D.; Endl, M.; Guenther, E. W.; MacQueen, P.; Hartmann, M.; Zechmeister, M.; Han, I.; Lee, B.-C.; Walker, G. A. H.; Yang, S.; Larson, A. M.; Kim, K.-M.; Mkrtichian, , D. E.; Döllinger, M.; Simon, , A. E.; Girardi, L.

2015-08-01

Aims: We investigate the nature of the long-period radial velocity variations in α Tau first reported over 20 yr ago. Methods: We analyzed precise stellar radial velocity measurements for α Tau spanning over 30 yr. An examination of the Hα and Ca II λ8662 spectral lines, and Hipparcos photometry was also done to help discern the nature of the long-period radial velocity variations. Results: Our radial velocity data show that the long-period, low amplitude radial velocity variations are long-lived and coherent. Furthermore, Hα equivalent width measurements and Hipparcos photometry show no significant variations with this period. Another investigation of this star established that there was no variability in the spectral line shapes with the radial velocity period. An orbital solution results in a period of P = 628.96 ± 0.90 d, eccentricity, e = 0.10 ± 0.05, and a radial velocity amplitude, K = 142.1 ± 7.2 m s-1. Evolutionary tracks yield a stellar mass of 1.13 ± 0.11 M⊙, which corresponds to a minimum companion mass of 6.47 ± 0.53 MJup with an orbital semi-major axis of a = 1.46 ± 0.27 AU. After removing the orbital motion of the companion, an additional period of ≈520 d is found in the radial velocity data, but only in some time spans. A similar period is found in the variations in the equivalent width of Hα and Ca II. Variations at one-third of this period are also found in the spectral line bisector measurements. The ~520 d period is interpreted as the rotation modulation by stellar surface structure. Its presence, however, may not be long-lived, and it only appears in epochs of the radial velocity data separated by ~10 yr. This might be due to an activity cycle. Conclusions: The data presented here provide further evidence of a planetary companion to α Tau, as well as activity-related radial velocity variations. Based in part on observations obtained at the 2-m-Alfred Jensch Telescope at the Thüringer Landessternwarte Tautenburg and the

Robust Period Estimation Using Mutual Information for Multiband Light Curves in the Synoptic Survey Era

NASA Astrophysics Data System (ADS)

Huijse, Pablo; Estévez, Pablo A.; Förster, Francisco; Daniel, Scott F.; Connolly, Andrew J.; Protopapas, Pavlos; Carrasco, Rodrigo; Príncipe, José C.

2018-05-01

The Large Synoptic Survey Telescope (LSST) will produce an unprecedented amount of light curves using six optical bands. Robust and efficient methods that can aggregate data from multidimensional sparsely sampled time-series are needed. In this paper we present a new method for light curve period estimation based on quadratic mutual information (QMI). The proposed method does not assume a particular model for the light curve nor its underlying probability density and it is robust to non-Gaussian noise and outliers. By combining the QMI from several bands the true period can be estimated even when no single-band QMI yields the period. Period recovery performance as a function of average magnitude and sample size is measured using 30,000 synthetic multiband light curves of RR Lyrae and Cepheid variables generated by the LSST Operations and Catalog simulators. The results show that aggregating information from several bands is highly beneficial in LSST sparsely sampled time-series, obtaining an absolute increase in period recovery rate up to 50%. We also show that the QMI is more robust to noise and light curve length (sample size) than the multiband generalizations of the Lomb–Scargle and AoV periodograms, recovering the true period in 10%–30% more cases than its competitors. A python package containing efficient Cython implementations of the QMI and other methods is provided.

On quasi-periodic variations of low-energy cosmic rays observed near earth.

PubMed

Kudela, Karel; Langer, Ronald

2015-06-01

Cosmic ray (CR) may partially, especially at high altitudes, contribute to the dosimetric characteristics. Along with irregular CR variations as Forbush decreases and solar particle events are, the quasi-periodic variations may be of some relevance too. A very short review (with references to original papers) of the present knowledge of various types of such variations is presented, namely (i) diurnal wave, (ii) ~27 d variability due to the solar rotation, (iii) Rieger-type periodicity, and (iv) quasi-biennial oscillations as well as waves on longer time scales related to solar activity and to polarity of magnetic field of the Sun. Variability is illustrated in measurements of secondary CR on the ground including the high-altitude observations at Lomnický štít. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Periodic variations in stratospheric-mesospheric temperature from 20-65 km at 80 N to 30 S

NASA Technical Reports Server (NTRS)

Nastrom, G. D.; Belmont, A. D.

1975-01-01

Results on large-scale periodic variations of the stratospheric-mesospheric temperature field based on Meteorological Rocket Network (MRN) measurements are reported for a long-term (12-year) mean, the quasi-biennial oscillation (QBO), and the first three harmonics of the annual wave (annual wave, semi-annual wave, and terannual wave or 4-month variation). Station-to-station comparisons are tabulated and charted for amplitude and phase of periodic variations in the temperature field. Masking and biasing factors, such as diurnal tides, solar radiation variations, mean monthly variations, instrument lag, aerodynamic heating, are singled out for attention. Models of the stratosphere will have to account for these oscillations of different periods in the thermal field and related properties of the wind fields, with multilayered horizontal stratification with height taken into account.-

Broadband light funneling in ultrasubwavelength channels having periodic connected unfilled apertures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subramania, Ganapathi Subramanian; Brener, Igal; Foteinopoulou, Stavroula

2017-08-01

A structure for broadband light funneling comprises a two-dimensional periodic array of connected ultrasubwavelength apertures, each aperture comprising a large sub-aperture that aids in the coupling of the incoming incident light and a small sub-aperture that funnels a significant fraction of the incident light power. The structure possesses all the capabilities of prior extraordinary optical transmission platforms, yet operates nonresonantly on a distinctly different mechanism. The structure demonstrates efficient ultrabroadband funneling of optical power confined in an area as small as .about.(.lamda./500).sup.2, where optical fields are enhanced, thus exhibiting functional possibilities beyond resonant platforms.

A connection between long-term luminosity variations and orbital period changes in chromospherically active binaries

NASA Technical Reports Server (NTRS)

Hall, Douglas S.

1991-01-01

The eclipsing binary CG Cyg provides observational confirmation of three predictions made by Applegate's (1991) improvement on the theory that magnetic cycles cause the quasi-periodic orbital period changes in binaries containing a convective star. The mean brightness outside eclipse and the period vary with the same cycle length of about 50 yr. The light curve and O - C curve are in phase, with maximum light and period increase occurring in early 1980. The chromospherically active star becomes bluer in phase with the brightening. Because a period increase occurs at maximum brightness, the sense of the star's differential rotation is specified: outside rotating faster.

Long-Period Variability in o Ceti

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.; Karovska, Margarita

2009-02-01

We carried out a new and sensitive search for long-period variability in the prototype of the Mira class of long-period pulsating variables, o Ceti (Mira A), the closest and brightest Mira variable. We conducted this search using an unbroken light curve from 1902 to the present, assembled from the visual data archives of five major variable star observing organizations from around the world. We applied several time-series analysis techniques to search for two specific kinds of variability: long secondary periods (LSPs) longer than the dominant pulsation period of ~333 days, and long-term period variation in the dominant pulsation period itself. The data quality is sufficient to detect coherent periodic variations with photometric amplitudes of 0.05 mag or less. We do not find evidence for coherent LSPs in o Ceti to a limit of 0.1 mag, where the amplitude limit is set by intrinsic, stochastic, low-frequency variability of approximately 0.1 mag. We marginally detect a slight modulation of the pulsation period similar in timescale to that observed in the Miras with meandering periods, but with a much lower period amplitude of ±2 days. However, we do find clear evidence of a low-frequency power-law component in the Fourier spectrum of o Ceti's long-term light curve. The amplitude of this stochastic variability is approximately 0.1 mag at a period of 1000 days, and it exhibits a turnover for periods longer than this. This spectrum is similar to the red noise spectra observed in red supergiants.

Periodic variation in physical and chemical properties of two central Washington soils.

Treesearch

Tom D. Anderson; Arthur R. Tiedemann

1970-01-01

Soils derived from two widely distributed parent materials in central Washington were examined periodically during 1968-69 for physical and chemical properties. Basalt soils showed significant periodic variation in cation exchange capacity, pH, and Na and K contents. In sandstone soils, cation exchange capacity and Ca, Na, and K contents varied significantly among...

Periodical climate variations and their impact on Earth rotation for the last 800Kyr

NASA Astrophysics Data System (ADS)

Chapanov, Yavor; Gambis, Daniel

2010-05-01

The Earth rotation variations are highly affected by climatic variations associated with the glacial cycles in the late Pleistocene. The processes of glaciation, followed by ice melting, are connected with significant changes of the mean sea level. These processes redistribute great amount of water masses between oceans and ice sheets, which lead to changes of the axial moment of inertia and corresponding variations of the Universal Time UT1 and Length of Day LOD, according to the law of angular momentum conservation. The climatic variations for the last 800Kyr are analyzed by means of time series of temperature changes, determined by deuterium data from Antarctica ice core. Reconstructed glacial sea level variations for the last 380Kyr, determined by the sediments from the Red sea, are used, too. Common periodicities of the temperature and mean sea level variations are determined. Time series of the long-periodical UT1 and LOD oscillations for the last 380Kyr and 800Kyr are reconstructed by means of empirical hydrological model of global water redistribution between the ocean and ice sheets during the last glacial events.

Variations of System IV period of the sulfur ions in the Io torus for the volcanic event in 2015 observed by the HISAKI/EXCEED

NASA Astrophysics Data System (ADS)

Ryo, A.; Misawa, H.; Tsuchiya, F.; Kagitani, M.; Yoshioka, K.; Yoshikawa, I.; Kimura, T.; Murakami, G.; Yamazaki, A.

2017-12-01

Previous ground-based and probe observations of Io plasma torus (IPT) in various wavelengths have detected a periodic variation which is longer than System III period (9.925 h). It has been called System IV period. Although various ideas to explain the origin of System IV period are proposed , little progress has been made. A previous study reported that the System IV period was 10.07 h during the Cassini's Jupiter flyby in 2000. This period was shorter than the typical period of 10.21h (Brown 1995). The Io's volcanic event just before Cassini's flyby might shorten the System IV period (Steffl et al., 2006). However, the certainty of this inference is not clear from the Cassini observation. Here, we analyzed time variations in intensities of EUV emissions from IPT obtained by the HISAKI satellite to understand the mechanism responsible for the System IV period and the influence of Io's volcanic event on IPT. The data used in this study was obtained from Dec. 2014 to the middle of May 2015. During this period, the Io's volcanic event from Jan. to Mar. 2015 was reported from the observation of Iogenic sodium emission (Yoneda et al., 2015). To find variations of the System IV period, the temporal variation of System III longitude at peak EUV intensity was derived by fitting light curves of three ion species (S II 76.5 nm + 126 nm, S III 68 nm, and S IV 65.7 nm + 140.5 nm). The System IV periods of S II before and after the Io's volcanic event were 10.16±0.008 h and 10.03±0.006 h, respectively. On the other hands, the System IV period of S II was 9.95±0.003 h during the Io's volcanic event. This is the first observational evidence which shows that the System IV period has shortened during the Io's volcanic event, which is consistent with the result from Cassini observation. Origin of the System IV period has been discussed with sub-corotation of plasma in IPT. Since the sub-corotation occurs due to mass loading of newly picked-up ions into IPT, it is expected that

33 CFR 67.05-15 - Operating periods of obstruction lights.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Operating periods of obstruction lights. 67.05-15 Section 67.05-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES General...

33 CFR 67.05-15 - Operating periods of obstruction lights.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Operating periods of obstruction lights. 67.05-15 Section 67.05-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES General...

Adaptive influence of extrinsic and intrinsic factors on variation of incubation periods among tropical and temperate passerines

USGS Publications Warehouse

Martin, Thomas E.; Ton, Riccardo; Oteyza, Juan C.

2018-01-01

Understanding intrinsic (physiological) and extrinsic (e.g., temperature) causes of variation in embryonic development time (incubation period) is important because they can have different impacts on individual quality. Robert Ricklefs and colleagues have argued that longer incubation periods result primarily from intrinsic physiological programs that increase individual quality and adult survival. They claim that incubation periods are largely invariant and that extrinsic factors like temperature have little impact. We have argued that adult survival may be a cause rather than a consequence of much of the variation in embryonic development time. A reduction in extrinsic sources of annual adult mortality (e.g., migration, predation, nonbreeding-season mortality) favors reduced parental effort during incubation to minimize costs to future reproduction and survival. Reduced parental effort, in turn, manifests as cooler average egg temperatures that yield longer incubation periods. Ricklefs and colleagues mischaracterized our hypothesis and deconstructed their own incorrect version, while also making some incorrect statements. We show that reevaluation of previous evidence provided by this group actually supports a role of egg temperature for the variation in incubation periods. We also summarize other observational and experimental evidence that incubation periods are not invariant and that egg temperature has a strong causal influence on variation within and among species. In fact, egg temperature explains ∼60% of the difference in incubation periods among species. The remaining ∼40% reflects intrinsic physiological programs and other factors, potentially providing intrinsic benefits. Ultimately, annual adult mortality explains substantial variation in parental effort and egg temperature, and the latter strongly explains variation in incubation periods. Both intrinsic programs and extrinsic temperature effects need to be considered in attempts to understand

Generating the Nighttime Light of the Human Settlements by Identifying Periodic Components from DMSP/OLS Satellite Imagery.

PubMed

Letu, Husi; Hara, Masanao; Tana, Gegen; Bao, Yuhai; Nishio, Fumihiko

2015-09-01

Nighttime lights of the human settlements (hereafter, "stable lights") are seen as a valuable proxy of social economic activity and greenhouse gas emissions at the subnational level. In this study, we propose an improved method to generate the stable lights from Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) daily nighttime light data for 1999. The study area includes Japan, China, India, and other 10 countries in East Asia. A noise reduction filter (NRF) was employed to generate a stable light from DMSP/OLS time-series daily nighttime light data. It was found that noise from amplitude of the 1-year periodic component is included in the stable light. To remove the amplitude of the 1-year periodic component noise included in the stable light, the NRF method was improved to extract the periodic component. Then, new stable light was generated by removing the amplitude of the 1-year periodic component using the improved NRF method. The resulting stable light was evaluated by comparing it with the conventional nighttime stable light provided by the National Oceanic and Atmosphere Administration/National Geophysical Data Center (NOAA/NGDC). It is indicated that DNs of the NOAA stable light image are lower than those of the new stable light image. This might be attributable to the influence of attenuation effects from thin warm water clouds. However, due to overglow effect of the thin cloud, light area in new stable light is larger than NOAA stable light. Furthermore, the cumulative digital numbers (CDNs) and number of light area pixels (NLAP) of the generated stable light and NOAA/NGDC stable light were applied to estimate socioeconomic variables of population, electric power consumption, gross domestic product, and CO2 emissions from fossil fuel consumption. It is shown that the correlations of the population and CO2FF with new stable light data are higher than those in NOAA stable light data; correlations of the EPC and GDP with NOAA

REVIEWS OF TOPICAL PROBLEMS: Periodic weather and climate variations

NASA Astrophysics Data System (ADS)

Ivanov, Vladimir V.

2002-07-01

Variations in meteorological parameters are largely due to periodic processes and can be forecast for several years. Many such processes are related to astronomical factors such as the gravitational influences of the Moon and the Sun, and the modulation of solar irradiance by lunar and planetary motion. The Moon, Jupiter, and Venus have the strongest effect. These influences produce lines in the spectra of meteorological variations, which are combinations of the harmonics of the frequencies of revolution of the planets, the Earth, and the Moon around the Sun with the harmonics of the lunar revolution around the Earth. Due to frequency differences between the orbital and radial motions, fine spectral features of three types appear: line splitting, line-profile complications due to radial oscillations, and additional lines due to the combination of radial-oscillation frequencies with perturbation harmonics.

Periodic molybdenum disc array for light trapping in amorphous silicon layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jiwei; Deng, Changkai; Shanghai Advanced Research Institute, Chinese Academy of Sciences, 99 Haike Road, Shanghai, 201210 China

2016-05-15

We demonstrate the light trapping effect in amorphous silicon (a-Si:H) layer by inserting a layer of periodic molybdenum disc array (MDA) between the a-Si:H layer and the quartz substrate, which forms a three-layer structure of Si/MDA/SiO{sub 2}. The MDA layer was fabricated by a new cost-effective method based on nano-imprint technology. Further light absorption enhancement was realized through altering the topography of MDA by annealing it at 700°C. The mechanism of light absorption enhancement in a-Si:H interfaced with MDA was analyzed, and the electric field distribution and light absorption curve of the different layers in the Si/MDA structure under lightmore » illumination of different wavelengths were simulated by employing numerical finite difference time domain (FDTD) solutions.« less

On the Origin of Quasi-Periodic Temperature Variations in Kun-1 Well (Kunashir Island)

NASA Astrophysics Data System (ADS)

Demezhko, D. Yu.; Yurkov, A. K.

2017-12-01

The results of temperature monitoring in the 300-m kun-1 well (Kunashir Island) in 2011-2015 are considered. Quasi-periodic temperature variations with an amplitude of up to 0.3°C and a variation period of 14-26 h were added from November 2011 to the previously observed temperature variations caused by tidal deformations, free thermal convection, and deformation processes associated with the preparation and occurrence of tectonic earthquakes. Five cycles of such variations lasting from 2 to 6 months have been recorded. Each cycle was initiated by an earthquake with magnitude M > 2.5log( R), where R is the epicentral distance (km). According to their characteristics, the variations are unique and have not been described previously. Assumptions have been made about the possible connection of the registered variations with the inertial currents of the ocean or with hydrothermal processes in the Earth's subsurface. The phenomenon discovered requires further study not only as an object of fundamental science, but also as a feature of an earlier unknown type of geodynamic activity that can be a significant threat to the regional population.

Reflection and transmission of light at periodic layered metamaterial films

NASA Astrophysics Data System (ADS)

Paul, Thomas; Menzel, Christoph; Śmigaj, Wojciech; Rockstuhl, Carsten; Lalanne, Philippe; Lederer, Falk

2011-09-01

The appropriate description of light scattering (transmission/reflection) at a bulky artificial medium, consisting of a sequence of functional metamaterial and natural material films, represents a major challenge in current theoretical nano-optics. Because in many relevant cases, in particular, in the optical domain, a metamaterial must not be described by an effective permittivity and permeability the usual Fresnel formalism cannot be applied. A reliable alternative consists in using a Bloch mode formalism known, e.g., from the theory of photonic crystals. It permits to split this complex issue into two more elementary ones, namely the study of light propagation in an infinitely extended metamaterial and the analysis of light scattering at interfaces between adjacent meta and natural materials. The first problem is routinely solved by calculating the relevant Bloch modes and their dispersion relations. The second task is more involved and represents the subject of the present study. It consists in using the general Bloch mode orthogonality to derive rigorous expressions for the reflection and transmission coefficients at an interface between two three-dimensional absorptive periodic media for arbitrary incidence. A considerable simplification can be achieved if only the fundamental Bloch modes of both media govern the scattering properties at the interface. If this approximation is valid, which depends on the longitudinal metamaterial period, the periodic metamaterial may be termed homogeneous. Only in this case the disentanglement of the fundamental modes of both media can be performed and the reflection/transmission coefficients can be expressed in terms of two impedances, each depending solely on the properties of the fundamental mode of the respective medium. In order to complement the picture, we apply the present formalism to the quite general problem of reflection/transmission at a metamaterial film sandwiched between a dissimilar metamaterial. This

Variational Wavefunction for the Periodic Anderson Model with Onsite Correlation Factors

NASA Astrophysics Data System (ADS)

Kubo, Katsunori; Onishi, Hiroaki

2017-01-01

We propose a variational wavefunction containing parameters to tune the probabilities of all the possible onsite configurations for the periodic Anderson model. We call it the full onsite-correlation wavefunction (FOWF). This is a simple extension of the Gutzwiller wavefunction (GWF), in which one parameter is included to tune the double occupancy of the f electrons at the same site. We compare the energy of the GWF and the FOWF evaluated by the variational Monte Carlo method and that obtained with the density-matrix renormalization group method. We find that the energy is considerably improved in the FOWF. On the other hand, the physical quantities do not change significantly between these two wavefunctions as long as they describe the same phase, such as the paramagnetic phase. From these results, we not only demonstrate the improvement by the FOWF, but we also gain insights on the applicability and limitation of the GWF to the periodic Anderson model.

Is the use of underwater polarized light by fish restricted to crepuscular time periods?

PubMed

Novales Flamarique, I; Hawryshyn, C W

1997-04-01

We measured the spectral distributions of the underwater total and polarized light fields in the upper photic zone of meso-eutrophic waters (i.e., blue-green waters containing medium to high chlorophyll a concentrations). Per cent polarization levels during the day were always lower than 40%, but at crepuscular times these values could increase to 67%. A corresponding change occurred in the spectral distribution, with proportionately more shorter wavelength photons contributing to the total spectrum during crepuscular periods. Electrophysiological recordings from the optic nerve of rainbow trout subjected to light stimuli of varying polarization percentages show that the animal's threshold for detecting polarized light is between 63 and 72%. These physiological findings suggest that the use of water-induced polarized light cues by rainbow trout and similar percomorph fish should be restricted to crepuscular time periods.

Multiple color light curves and period changes investigation of the contact binary HV Aqr

NASA Astrophysics Data System (ADS)

Li, K.; Qian, S.-B.

2013-07-01

New V, R and I light curves of the short period binary system, HV Aqr, are presented. Photometric solutions were derived using the Wilson-Devinney code. Our new determined light curves do not show O'Connell effect. The nearly symmetry and complete eclipses of the light curves of HV Aqr enable us to determine high-precision photometric parameters of the binary system. The new solutions suggest that HV Aqr is a low mass ratio (q=0.1455) deep contact binary with a contact degree of f=55.9%. Based on all available times of light minimum, we analyzed the long-term period changes of HV Aqr. A secular decrease rate of dP/dt=8.84(±0.18)×10-8 days yr-1 was determined. The continuous period decrease can be explained by the mass transfer from the primary component to the secondary and angular momentum loss via magnetic stellar wind. A conservative mass transfer rate of dM1/dt=1.81×10-8M⊙ yr-1 and angular momentum loss rate at dJ/dt=5.96×1045 g cm2 s-1 yr-1 were derived. As the orbital period decreases, the contact degree of HV Aqr will become deeper and finally it will evolve into a single rapid-rotation star.

Periodic intensity variations in sulfur emissions from the Io plasma torus

NASA Technical Reports Server (NTRS)

Woodward, R. Carey, Jr.; Scherb, Frank; Roesler, Fred L.

1994-01-01

In November and December 1988, we acquired 157 spectra of (S II) lambda 6731 emissions from the Io plasma torus with a Fabry-Perot interferometer at the McMath-Pierce Solar Telescope facility on Kitt Peak. A major goal of this experiment was to extend our earlier studies of intensity variations in the plasma torus. Our earlier analysis (F. L. Roesler, F. Scherb, and R. J. Oliversen, 1984, of (S III) lambda 9531 emission spectra acquired in April 1982 had shown that the intensity of torus emissions varied periodically with a period of 10.20 +/- 0.06 hr (1-sigma uncertainty level), slightly longer than Jupiter's System 3 rotational period of 9.925 hr. We present here an reanalysis of our 1982 data revealing, in addition to the 10.20-hr period, a clear secondary periodicity at 9.95 +/- 0.906 hr. By constrast, we show that our new (S II) lambda 6731 data have a single period of 10.14 +/- 0.03 hr. which is neither the System 3 period nor the proposed 'System 4' period of 10.224 hr.

Periodic intensity variations in sulfur emissions from the Io plasma torus

NASA Astrophysics Data System (ADS)

Woodward, R. Carey, Jr.; Scherb, Frank; Roesler, Fred L.; Oliversen, Ronald J.

1994-09-01

In November and December 1988, we acquired 157 spectra of (S II) lambda 6731 emissions from the Io plasma torus with a Fabry-Perot interferometer at the McMath-Pierce Solar Telescope facility on Kitt Peak. A major goal of this experiment was to extend our earlier studies of intensity variations in the plasma torus. Our earlier analysis (F. L. Roesler, F. Scherb, and R. J. Oliversen, 1984, of (S III) lambda 9531 emission spectra acquired in April 1982 had shown that the intensity of torus emissions varied periodically with a period of 10.20 +/- 0.06 hr (1-sigma uncertainty level), slightly longer than Jupiter's System 3 rotational period of 9.925 hr. We present here an reanalysis of our 1982 data revealing, in addition to the 10.20-hr period, a clear secondary periodicity at 9.95 +/- 0.906 hr. By constrast, we show that our new (S II) lambda 6731 data have a single period of 10.14 +/- 0.03 hr. which is neither the System 3 period nor the proposed 'System 4' period of 10.224 hr.

Periodic variations in the signal-to-noise ratios of signals received from the ICE spacecraft

NASA Technical Reports Server (NTRS)

Nadeau, T.

1986-01-01

Data from the ICE probe to comet Giacobini-Zinner are analyzed to determine the effects of spacecraft rotation upon the signal to noise ratio (SNR) for the two channels of data. In addition, long-term variations from sources other than rotations are considered. Results include a pronounced SNR variation over a period of three seconds (one rotation) and a lesser effect over a two minute period (possibly due to the receiving antenna conscan).

Boundedness and almost Periodicity in Time of Solutions of Evolutionary Variational Inequalities

NASA Astrophysics Data System (ADS)

Pankov, A. A.

1983-04-01

In this paper existence theorems are obtained for the solutions of abstract parabolic variational inequalities, which are bounded with respect to time (in the Stepanov and L^\\infty norms). The regularity and almost periodicity properties of such solutions are studied. Theorems are also established concerning their solvability in spaces of Besicovitch almost periodic functions. The majority of the results are obtained without any compactness assumptions. Bibliography: 30 titles.

Periodical cicadas use light for oviposition site selection.

PubMed

Yang, Louie H

2006-12-07

Organisms use incomplete information from local experience to assess the suitability of potential habitat sites over a wide range of spatial and temporal scales. Although ecologists have long recognized the importance of spatial scales in habitat selection, few studies have investigated the temporal scales of habitat selection. In particular, cues in the immediate environment may commonly provide indirect information about future habitat quality. In periodical cicadas (Magicicada spp.), oviposition site selection represents a very long-term habitat choice. Adult female cicadas insert eggs into tree branches during a few weeks in the summer of emergence, but their oviposition choices determine the underground habitats of root-feeding nymphs over the following 13 or 17 years. Here, field experiments are used to show that female cicadas use the local light environment of host trees during the summer of emergence to select long-term host trees. Light environments may also influence oviposition microsite selection within hosts, suggesting a potential behavioural mechanism for associating solar cues with host trees. In contrast, experimental nutrient enrichment of host trees did not influence cicada oviposition densities. These findings suggest that the light environments around host trees may provide a robust predictor of host tree quality in the near future. This habitat selection may influence the spatial distribution of several cicada-mediated ecological processes in eastern North American forests.

Periodical cicadas use light for oviposition site selection

PubMed Central

Yang, Louie H

2006-01-01

Organisms use incomplete information from local experience to assess the suitability of potential habitat sites over a wide range of spatial and temporal scales. Although ecologists have long recognized the importance of spatial scales in habitat selection, few studies have investigated the temporal scales of habitat selection. In particular, cues in the immediate environment may commonly provide indirect information about future habitat quality. In periodical cicadas (Magicicada spp.), oviposition site selection represents a very long-term habitat choice. Adult female cicadas insert eggs into tree branches during a few weeks in the summer of emergence, but their oviposition choices determine the underground habitats of root-feeding nymphs over the following 13 or 17 years. Here, field experiments are used to show that female cicadas use the local light environment of host trees during the summer of emergence to select long-term host trees. Light environments may also influence oviposition microsite selection within hosts, suggesting a potential behavioural mechanism for associating solar cues with host trees. In contrast, experimental nutrient enrichment of host trees did not influence cicada oviposition densities. These findings suggest that the light environments around host trees may provide a robust predictor of host tree quality in the near future. This habitat selection may influence the spatial distribution of several cicada-mediated ecological processes in eastern North American forests. PMID:17015354

Critical periods in the variation in body composition in school children.

PubMed

Cristi-Montero, Carlos; Bresciani, Guilherme; Alvarez, Ana; Arriagada, Valentina; Beneventi, Angelo; Canepa, Valentina; Espinoza, Paula; Parraguez, Melisa; Toledo, Carlos; Valencia, Consuelo; Rodriguez-Rodriguez, Fernando

2014-10-01

To identify critical periods in the variation in body composition during a school year and determine possible causes. A total of 363 boys and girls aged between 10 and 14 years participated in the study. Before and after the Winter Holidays (WIH) and National Holidays (NAH) (July and September, respectively), measurements were taken of body weight, body fat percentage, waist perimeter, time spent on physical activity and hours of sleep in order to determine the variations. The normality of the data was confirmed and the means were compared with an alpha significance level of p<0.05. The school children increased in weight by 600 g and 510 g in the NAH and WIH, respectively (p<0.0001), and their body fat percentage was significantly increased during both periods (0.51%); however, the waist perimeter measurement saw no significant changes. It can also be seen that in NAH physical activity dropped by an important amount (-41 min, p<0.0001), though this did not occur in WIH. A significant increase in hours of sleep was also seen during the two holiday periods (~1 to 2 hours/day). It is concluded that both NAH and WIH can be considered critical periods due to the sharp increase in body weight and body fat percentage in the school children, where a possible cause is the reduction in time spent on physical activity. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

EXTRACTING PERIODIC TRANSIT SIGNALS FROM NOISY LIGHT CURVES USING FOURIER SERIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samsing, Johan

We present a simple and powerful method for extracting transit signals associated with a known transiting planet from noisy light curves. Assuming the orbital period of the planet is known and the signal is periodic, we illustrate that systematic noise can be removed in Fourier space at all frequencies by only using data within a fixed time frame with a width equal to an integer number of orbital periods. This results in a reconstruction of the full transit signal, which on average is unbiased despite no prior knowledge of either the noise or the transit signal itself being used inmore » the analysis. The method therefore has clear advantages over standard phase folding, which normally requires external input such as nearby stars or noise models for removing systematic components. In addition, we can extract the full orbital transit signal (360°) simultaneously, and Kepler-like data can be analyzed in just a few seconds. We illustrate the performance of our method by applying it to a dataset composed of light curves from Kepler with a fake injected signal emulating a planet with rings. For extracting periodic transit signals, our presented method is in general the optimal and least biased estimator and could therefore lead the way toward the first detections of, e.g., planet rings and exo-trojan asteroids.« less

Short and long periodic atmospheric variations between 25 and 200 km

NASA Technical Reports Server (NTRS)

Justus, C. G.; Woodrum, A.

1973-01-01

Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of gravity wave and planetary wave atmospheric variations are presented. Time structure of the gravity wave variations were determined by the analysis of residuals from harmonic analysis of time series data. Planetary wave contributions in the 25-85 km range were discovered and found to have significant height and latitudinal variation. Long period planetary waves, and seasonal variations were also computed by harmonic analysis. Revised height variations of the gravity wave contributions in the 25 to 85 km height range were computed. An engineering method and design values for gravity wave magnitudes and wave lengths are given to be used for such tasks as evaluating the effects on the dynamical heating, stability and control of spacecraft such as the space shuttle vehicle in launch or reentry trajectories.

A new mechanism of long-term period variations for W UMa-type contact binaries

NASA Astrophysics Data System (ADS)

Liu, L.; Qian, S.-B.; Xiong, X.

2018-03-01

W UMa-type contact binaries belong to close binary systems whose components exactly overflow their Roche lobes and share a common convective envelope (CCE). In the last twenty years, the long-term variations of their orbital periods have been thought to depend on several mechanisms. Now, we suggest a new mechanism: CCE-dominated mechanism. The CCE-dominated mechanism is found based on our numerical result, especially at high mass ratios, that the orbital periods (P) of contact binaries change very much with their fill-out factors (f). Because f is taken as a measurement of the thickness of CCE, the physical cause for the variation of P is a mass transfer between CCE and components. Further, an f-dominated simplification model for this mechanism is introduced. According to it, P may change in a long-term oscillation way with a similar time scale of the thermal modulation, meanwhile q is decreasing slowly till the two components merge. It could be also applied to explain the presence of extremely short period, high mass ratio and deep contact binaries. Moreover, the CCE-dominated mechanism should always work due to mass transfer and mass loss both occurring via CCE. Therefor, the effect of CCE on the variations of orbital periods may have been underestimated before.

An Orbital Period Study of the W UMa-Type Binary RZ Comae Berenicis

NASA Astrophysics Data System (ADS)

Qian, Sheng-Bang; He, Jia-Jia

2005-12-01

New photoelectric and CCD photometry observations of a short-period W UMa-type binary system, RZ Com, are presented. The light curves of Broglia (1960, Contr. Milano-Merate, 165) were symmetric in V band, while the present light curve shows a typical O'Connell effect, with Maximum I brighter than Maximum II by 0.015mag. It is found that the light curve of the binary star has changed from W-subtype to A-subtype according to Binnendijk's classification. This variation may be caused by the activity of dark spot on the primary component. Combining four newly determined times of the light minimum with others published in the literature, the orbital period change of the system was investigated. A small-amplitude oscillation (A = 0.0058 d), with a period of 44.8yr has been discovered to be superimposed on a long-term period increase with a rate of dP/dt = +4.12 × 10-8 d yr-1. The period oscillation can be explained either by the light-time effect via the presence of an unseen third body or by magnetic-activity cycles of the components. The mass ratio of RZ Com is q = 0.43. The secular period variation is in agreement with the conclusions of Qian (2001, MNRAS, 328, 914; 2003, MNRAS, 342, 1260). This indicates that it is on the TRO-controlled stage of the evolutionary scheme proposed by Qian.

Periodicity Analysis of X-ray Light Curves of SS 433

NASA Astrophysics Data System (ADS)

Wang, J. Y.; Lu, X. L.; Zhao, Q. W.; Dong, D. Q.; Lao, B. Q.; Lu, Y.; Wei, Y. H.; Wu, X. C.; An, T.

2016-03-01

SS 433 is the only X-ray binary to date that was detected to have a pair of well-collimated jets, and its orbital period, super orbital period, and nutation period were all detected at the same time. The study on the periodic X-ray variabilities is helpful for understanding its dynamic process of the central engine and the correlation with other bands. In the present paper, two time series analysis techniques, Lomb-Scargle periodogram and weighted wavelet Z-transform, are employed to search for the periodicities from the Swift/BAT (Burst Alert Telescope)(15--50 keV) and RXTE/ASM (Rossi X-Ray Timing Explorer/All-Sky Monitor)(1.5--3, 3--5 and 5--12 keV) light curves of SS 433, and the Monte Carlo simulation is performed. For the 15--50 keV energy band, five significant periodic signals are detected, which are P_1(˜6.29 d), P_2 (˜6.54 d), P_3 (˜13.08 d), P_4 (˜81.50 d), and P_5 (˜162.30 d). For the 3--5 and 5--12 keV energy bands, periodic signals P_3 (˜13 d) and P_5 (˜162 d) are detected in both energy bands. However, for the 1.5--3 keV energy band, no significant periodic signal is detected. P_5 has the strongest periodic signal in the power spectrum for all the energy bands of 3--5, 5--12, and 15--50 keV, and it is consistent with that obtained by previous study in optical band. Further, due to the existence of relativistic radio jets, the X-ray and optical band variability of P_5 (˜162 d) is probably related to the precession of the relativistic jets. High coherence between X-ray and optical light curves may also imply that the X-ray and optical emissions are of the same physical origin. P_3 shows a good agreement with the orbital period (˜13.07 d) first obtained by previous study, and P_2 and P_4 are the high frequency harmonic components of P_3 and P_5, respectively. P_1 is detected from the power spectrum of 15--50 keV energy band only, and it is consistent with the systematic nutation period. As the power of energy band decreases (from hard X-ray to

RAPID COMMUNICATION: Improving prediction accuracy of GPS satellite clocks with periodic variation behaviour

NASA Astrophysics Data System (ADS)

Heo, Youn Jeong; Cho, Jeongho; Heo, Moon Beom

2010-07-01

The broadcast ephemeris and IGS ultra-rapid predicted (IGU-P) products are primarily available for use in real-time GPS applications. The IGU orbit precision has been remarkably improved since late 2007, but its clock products have not shown acceptably high-quality prediction performance. One reason for this fact is that satellite atomic clocks in space can be easily influenced by various factors such as temperature and environment and this leads to complicated aspects like periodic variations, which are not sufficiently described by conventional models. A more reliable prediction model is thus proposed in this paper in order to be utilized particularly in describing the periodic variation behaviour satisfactorily. The proposed prediction model for satellite clocks adds cyclic terms to overcome the periodic effects and adopts delay coordinate embedding, which offers the possibility of accessing linear or nonlinear coupling characteristics like satellite behaviour. The simulation results have shown that the proposed prediction model outperforms the IGU-P solutions at least on a daily basis.

Perfect coupling of light to a periodic dielectric/metal/dielectric structure

NASA Astrophysics Data System (ADS)

Wang, Zhengling; Li, Shiqiang; Chang, R. P. H.; Ketterson, John B.

2014-07-01

Using the finite difference time domain method, it is demonstrated that perfect coupling can be achieved between normally incident light and a periodic dielectric/metal/dielectric structure. The structure serves as a diffraction grating that excites modes related to the long range surface plasmon and short range surface plasmon modes that propagate on continuous metallic films. By optimizing the structural dimensions, perfect coupling is achieved between the incident light and these modes. A high Q of 697 and an accompanying ultrasharp linewidth of 0.8 nm are predicted for a 10 nm silver film for optimal conditions.

Influence of periodic vs continuous daily bright light exposure on development of experimental myopia in the chick.

PubMed

Backhouse, Simon; Collins, Andrew V; Phillips, John R

2013-09-01

In children, time spent outdoors has a protective effect against myopia development. In animal models, bright light reduces the development of experimental myopia. This study investigates how an increase in daily light exposure, presented either continuously during the day or periodically at different times of day, influences the development of experimental myopia in the chick. Myopia was induced in Cobb Chicks (Gallus domesticus) by monocular deprivation (MD) of form vision with a translucent diffuser for 3 days (from 4 days of age) under a 12:12 light: dark cycle. MD control chicks were exposed to constant 300 lux (n = 11) during the light period. MD treatment groups received either constant 2000 lux (n = 11) during the light period or 300 lux for 10 h with a 2 h period of bright light (10 000 lux), either in the morning (n = 10), midday (n = 10) or evening (n = 10), giving the same total daily light exposure as the 2000 lux group. After 3 days of MD, refractive status, corneal curvature and axial eye dimensions were measured for all eyes under anaesthesia. Myopia in the constant 2000 lux group (-4.94 ± 1.21 D) was significantly less than in the 300 lux control group (-9.73 ± 0.96 D; p = 0.022). However, compared to the 300 lux control group, 2 h periods of 10 000 lux did not produce significant effects on refraction when presented either in the morning (-9.98 ± 0.85; p = 1.00), midday (-8.00 ± 1.26; p = 0.80), or evening (-13.14 ± 1.16 D; p = 0.20), although significantly less myopia was induced in the midday group compared to the evening group (p = 0.018). Orthogonal regression showed that myopia development was matched by changes in vitreous chamber depth (R(2)  = 0.69; p < 0.0001). In chicks, an increase in daily light exposure continuously during the day is more effective at inhibiting myopia than adding an equivalent dose within a 2 h period of bright light. A weak time-of-day effect also appears

Comparison between periodic and stochastic parabolic light trapping structures for thin-film microcrystalline Silicon solar cells.

PubMed

Peters, M; Battaglia, C; Forberich, K; Bläsi, B; Sahraei, N; Aberle, A G

2012-12-31

Light trapping is of very high importance for silicon photovoltaics (PV) and especially for thin-film silicon solar cells. In this paper we investigate and compare theoretically the light trapping properties of periodic and stochastic structures having similar geometrical features. The theoretical investigations are based on the actual surface geometry of a scattering structure, characterized by an atomic force microscope. This structure is used for light trapping in thin-film microcrystalline silicon solar cells. Very good agreement is found in a first comparison between simulation and experimental results. The geometrical parameters of the stochastic structure are varied and it is found that the light trapping mainly depends on the aspect ratio (length/height). Furthermore, the maximum possible light trapping with this kind of stochastic structure geometry is investigated. In a second step, the stochastic structure is analysed and typical geometrical features are extracted, which are then arranged in a periodic structure. Investigating the light trapping properties of the periodic structure, we find that it performs very similar to the stochastic structure, in agreement with reports in literature. From the obtained results we conclude that a potential advantage of periodic structures for PV applications will very likely not be found in the absorption enhancement in the solar cell material. However, uniformity and higher definition in production of these structures can lead to potential improvements concerning electrical characteristics and parasitic absorption, e.g. in a back reflector.

Heliospheric Transient Structures Associated with Short-Period Variations in the GCR Flux

NASA Astrophysics Data System (ADS)

Mulligan, T.; Blake, J.B.; Shaul, D.; Quenby, J.

Short-period variations in the integral GCR fluence ( > 100 MeV) often observed in neutron monitor data have also been seen by the High Sensitivity Telescope (HIST) aboard the Polar spacecraft. Although HIST was designed to measure radiation-belt electrons, it makes clean measurements of the integral GCR fluence when Polar is outside the radiation belts. These measurements show GCR variability on a variety of timescales including 0.1 mHz - 1 mHz. On August 20, 2006 a Forbush decrease observed at Polar was also seen at the INTEGRAL spacecraft. Data from Polar HIST and from INTEGRAL’s Ge detector saturation rate (GEDSAT), which also measures the GCR background with a threshold of ~200 MeV, show similar, coherent, short-period GCR variations at two very different locations within the Earth’s magnetosphere. Comparing these variations from Polar and INTEGRAL to solar wind magnetic field and plasma conditions at the L1 Libration point sunward of the Earth reveal this coherency occurs when Earth is in close proximity to and inside a flux rope interplanetary CME (ICME). Inversion of the ICME magnetic field results in a flux rope axial orientation nearly parallel to the radial direction. This orientation is consistent with a grazing passage of the ICME with the Earth. New measurements from STEREO will enable detailed 3-D analyses of such solar wind disturbances along spatial scales on the same order of typical SEP and GCR proton gyroradii, which are needed to help determine the mechanism behind this short-period variability.

Effects of periodic atmospheric pressure variation on radon entry into buildings

NASA Astrophysics Data System (ADS)

Tsang, Y. W.; Narasimhan, T. N.

1992-06-01

Using a mathematical model, we have investigated the temporal variations of radon entry into a house basement in the presence of time-dependent periodic variations of barometric pressure as well as a persistent small steady depressurization within the basement. The tool for our investigation is an integral finite difference numerical code which can solve for both diffusive and advective flux of radon in the soil gas which is treated as a slightly compressible fluid. Two different boundary conditions at the house basement are considered: (1) a dirt floor basement so that diffusion is equally or more important than advective transport, and (2) an "impermeable" cement basement except for a 1-cm-wide crack near the perimeter of the basement floor; in which case, advective transport of radon flux dominates. Two frequencies of barometric pressure fluctuation with representative values of amplitudes, based on a Fourier decomposition of barometric pressure data, were chosen in this study: one with a short period of 0.5 hour with pressure amplitude of 50 Pa, the other a diurnal variation with a period of 24 hours with the typical pressure amplitude of 250 Pa. For a homogeneous soil medium with soil permeability to air between 10-13 and 10-10 m2, we predict that the barometric fluctuations increase the radon entry into the basement by up to 120% of the steady radon inflow into the basement owing to a steady depressurization of 5 Pa. If soil permeability heterogeneity is present, such as the presence of a thin layer of higher permeability aggregate immediately below the basement floor, radon flux due to atmospheric pumping is further increased. Effects of pressure pumping on radon entry are also compared to diffusion-only transport when the steady depressurization is absent. It is found that contribution to radon entry is significant for the basement crack configuration. In particular, for pressure pumping at 0.5-hour period and for a homogeneous medium of permeability of 10

A stable quasi-periodic 4.18-d oscillation and mysterious occultations in the 2011 MOST light-curve of TW Hya

NASA Astrophysics Data System (ADS)

Siwak, Michal; Rucinski, Slavek M.; Matthews, Jaymie M.; Guenther, David B.; Kuschnig, Rainer; Moffat, Anthony F. J.; Rowe, Jason F.; Sasselov, Dimitar; Weiss, Werner W.

2014-10-01

We present an analysis of the 2011 photometric observations of TW Hya by the MOST satellite; this is the fourth continuous series of this type. The large-scale light variations are dominated by a strong, quasi-periodic 4.18-d oscillation with superimposed, apparently chaotic flaring activity. The former is probably produced by stellar rotation with one large hotspot created by a stable accretion funnel, while the latter may be produced by small hotspots, created at moderate latitudes by unstable accretion tongues. A new, previously unnoticed feature is a series of semiperiodic, well-defined brightness dips of unknown nature, of which 19 were observed during 43 d of our nearly continuous observations. Re-analysis of the 2009 MOST light-curve revealed the presence of three similar dips. On the basis of recent theoretical results, we tentatively conclude that the dips may represent occultations of the small hotspots created by unstable accretion tongues by hypothetical optically thick clumps of dust.

Geographic variation in avian incubation periods and parental influences on embryonic temperature

USGS Publications Warehouse

Martin, T.E.; Auer, S.K.; Bassar, R.D.; Niklison, Alina M.; Lloyd, P.

2007-01-01

Theory predicts shorter embryonic periods in species with greater embryo mortality risk and smaller body size. Field studies of 80 passerine species on three continents yielded data that largely conflicted with theory; incubation (embryonic) periods were longer rather than shorter in smaller species, and egg (embryo) mortality risk explained some variation within regions, but did not explain larger differences in incubation periods among geographic regions. Incubation behavior of parents seems to explain these discrepancies. Bird embryos are effectively ectothermic and depend on warmth provided by parents sitting on the eggs to attain proper temperatures for development. Parents of smaller species, plus tropical and southern hemisphere species, commonly exhibited lower nest attentiveness (percent of time spent on the nest incubating) than larger and northern hemisphere species. Lower nest attentiveness produced cooler minimum and average embryonic temperatures that were correlated with longer incubation periods independent of nest predation risk or body size. We experimentally tested this correlation by swapping eggs of species with cool incubation temperatures with eggs of species with warm incubation temperatures and similar egg mass. Incubation periods changed (shortened or lengthened) as expected and verified the importance of egg temperature on development rate. Slower development resulting from cooler temperatures may simply be a cost imposed on embryos by parents and may not enhance offspring quality. At the same time, incubation periods of transferred eggs did not match host species and reflect intrinsic differences among species that may result from nest predation and other selection pressures. Thus, geographic variation in embryonic development may reflect more complex interactions than previously recognized. ?? 2007 The Author(s).

Characterizing directional variations in long-period ground motion amplifications in the Kanto Basin, Japan

NASA Astrophysics Data System (ADS)

Mukai, Y.; Furumura, T.; Maeda, T.

2017-12-01

In the Kanto Basin (including Tokyo in Japan), the long-period (T=3-10 s) ground motions are strongly developed when large earthquakes occur nearby. The amplitude of the long-period ground motion in the basin varies strongly among earthquakes; it is tremendous from the earthquakes in Niigata (northwest of Kanto), but is several times weaker from the earthquakes in Tohoku (north of Kanto). In this study, we examined the cause of such azimuthal-dependent amplitude variation for the 2004 Niigata Chuetsu (M6.8) and the 2011 Fukushima Hamadori (M7.0) earthquake based on numerical simulations of seismic wave propagation by the finite-difference method. We first examined the non-isotropic source-radiation effect of these events. By performing numerical simulations for different strike angles of these source faults, significant variation in amplitude of the long-period ground motions were observed in Tokyo for both the events. Among tested strike angles, the source of the 2004 event (strike = 212 deg.) produced the largest long-period ground motion due to strong radiation of surface wave towards the Kanto Basin, while the 2011 event (strike = 132 deg.) produced the least. The minimum-to-maximum ratio of their amplitudes with respect to strike angle is about 2 and 1.3, respectively. These investigations suggest the source radiation effect considerably contributes to the variations of the long-period ground motions. We then examined the effect of the 3D structure of the Kanto Basin on the generation of the long-period ground motion. For the 2004 event, we found that the long-period signal first arrives at the central Tokyo from the western edge of the Kanto Basin. Then, later signals containing both the Rayleigh and Love waves were amplified dramatically due to the localized low-velocity structure to the northwestern part of the basin. On the other hand, in the case of the 2011 event, the seismic waves propagating towards the basin were dissipated significantly as it travels

Imaging three-dimensional light propagation through periodic nanohole arrays using scanning aperture microscopy

PubMed Central

Chowdhury, Mustafa H.; Catchmark, Jeffrey M.; Lakowicz, Joseph R.

2009-01-01

The authors introduce a technique for three-dimensional (3D) imaging of the light transmitted through periodic nanoapertures using a scanning probe to perform optical sectioning microscopy. For a 4×4 nanohole array, the transmitted light displays intensity modulations along the propagation axis, with the maximum intensity occurring at 450 μm above the surface. The propagating fields show low divergence, suggesting a beaming effect induced by the array. At distances within 25 μm from the surface, they observe subwavelength confinement of light propagating from the individual nanoholes. Hence, this technique can potentially be used to map the 3D distribution of propagating light, with high spatial resolution. PMID:19696912

Direct periodic patterning of GaN-based light-emitting diodes by three-beam interference laser ablation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jeomoh; Ji, Mi-Hee; Detchprohm, Theeradetch

2014-04-07

We report on the direct patterning of two-dimensional periodic structures in GaN-based light-emitting diodes (LEDs) through laser interference ablation for the fast and reliable fabrication of periodic micro- and nano-structures aimed at enhancing light output. Holes arranged in a two-dimensional hexagonal lattice array having an opening size of 500 nm, depth of 50 nm, and a periodicity of 1 μm were directly formed by three-beam laser interference without photolithography or electron-beam lithography processes. The laser-patterned LEDs exhibit an enhancement in light output power of 20% compared to conventional LEDs having a flat top surface without degradation of electrical and optical properties of themore » top p-GaN layer and the active region, respectively.« less

A Simple yet Accurate Method for Students to Determine Asteroid Rotation Periods from Fragmented Light Curve Data

ERIC Educational Resources Information Center

Beare, R. A.

2008-01-01

Professional astronomers use specialized software not normally available to students to determine the rotation periods of asteroids from fragmented light curve data. This paper describes a simple yet accurate method based on Microsoft Excel[R] that enables students to find periods in asteroid light curve and other discontinuous time series data of…

Temporal and Periodic Variations of Sunspot Counts in Flaring and Non-Flaring Active Regions

NASA Astrophysics Data System (ADS)

Kilcik, A.; Yurchyshyn, V.; Donmez, B.; Obridko, V. N.; Ozguc, A.; Rozelot, J. P.

2018-04-01

We analyzed temporal and periodic variations of sunspot counts (SSCs) in flaring (C-, M-, or X-class flares), and non-flaring active regions (ARs) for nearly three solar cycles (1986 through 2016). Our main findings are as follows: i) temporal variations of monthly means of the daily total SSCs in flaring and non-flaring ARs behave differently during a solar cycle and the behavior varies from one cycle to another; during Solar Cycle 23 temporal SSC profiles of non-flaring ARs are wider than those of flaring ARs, while they are almost the same during Solar Cycle 22 and the current Cycle 24. The SSC profiles show a multi-peak structure and the second peak of flaring ARs dominates the current Cycle 24, while the difference between peaks is less pronounced during Solar Cycles 22 and 23. The first and second SSC peaks of non-flaring ARs have comparable magnitude in the current solar cycle, while the first peak is nearly absent in the case of the flaring ARs of the same cycle. ii) Periodic variations observed in the SSCs profiles of flaring and non-flaring ARs derived from the multi-taper method (MTM) spectrum and wavelet scalograms are quite different as well, and they vary from one solar cycle to another. The largest detected period in flaring ARs is 113± 1.6 days while we detected much longer periodicities (327± 13, 312 ± 11, and 256± 8 days) in the non-flaring AR profiles. No meaningful periodicities were detected in the MTM spectrum of flaring ARs exceeding 55± 0.7 days during Solar Cycles 22 and 24, while a 113± 1.3 days period was detected in flaring ARs of Solar Cycle 23. For the non-flaring ARs the largest detected period was only 31± 0.2 days for Cycle 22 and 72± 1.3 days for the current Cycle 24, while the largest measured period was 327± 13 days during Solar Cycle 23.

(abstract) Short Time Period Variations in Jupiter's Synchrotron Radiation

NASA Technical Reports Server (NTRS)

Bolton, S. J.; Klein, M. J.; Gulkis, S.; Foster, R.; Heiles, C.; Pater, I. de

1994-01-01

The long term time variability of Jupiter's synchrotron radiation on yearly time scales has been established for some time. For many years, theorists have speculated about the effects variations in the solar wind, solar flux, Io, the Io torus, and Jupiter's magnetic field have on the ultra-relativistic electron population responsible for the emission. Early observational results suggested the additional possibility of a short term time variability, on timescales of days to weeks. In 1989 a program designed to investigate the existence of short term time variability using the 85 foot Hat Creek radio telescope operating at 1400 MHz was initiated. The availability of a dedicated telescope provided the opportunity, for the first time, to obtain numerous observations over the full Jupiter rotation period. These and future observations will enable two important studies, characterization and confirmation of possible short term variations, and the investigation of the stability of Jupiter's synchrotron emission beaming curve. Analysis of Hat Creek observations and early results from the Maryland Point Naval research Laboratory will be presented.

Responses of southeast Alaska understory species to variation in light and simulated herbivory

Treesearch

Thomas A. Hanley; Jeffrey C. Barnard

2014-01-01

Responses to variation in light intensity, simulated herbivory by clipping, and their interaction were studied over three seasons in a factorial experimental design. Six major species of southeast Alaska forest understories were studied, each as a separate experiment: bunchberry, Cornus canadensis L.; threeleaf foamflower, Tiarella...

Finding hidden periodic signals in time series - an application to stock prices

NASA Astrophysics Data System (ADS)

O'Shea, Michael

2014-03-01

Data in the form of time series appear in many areas of science. In cases where the periodicity is apparent and the only other contribution to the time series is stochastic in origin, the data can be `folded' to improve signal to noise and this has been done for light curves of variable stars with the folding resulting in a cleaner light curve signal. Stock index prices versus time are classic examples of time series. Repeating patterns have been claimed by many workers and include unusually large returns on small-cap stocks during the month of January, and small returns on the Dow Jones Industrial average (DJIA) in the months June through September compared to the rest of the year. Such observations imply that these prices have a periodic component. We investigate this for the DJIA. If such a component exists it is hidden in a large non-periodic variation and a large stochastic variation. We show how to extract this periodic component and for the first time reveal its yearly (averaged) shape. This periodic component leads directly to the `Sell in May and buy at Halloween' adage. We also drill down and show that this yearly variation emerges from approximately half of the underlying stocks making up the DJIA index.

Photometric study and orbital period analysis of the W UMa type contact binary VZ Psc

NASA Astrophysics Data System (ADS)

Ma, S.; Li, K.; Li, Q.-C.; Gao, H.-Y.

2018-02-01

VZ Psc is a W-type contact binary system with a short period of 0.26125897 days. B, V, Rc and Ic light curves of the eclipsing binary system were obtained by using the 1.0 m reflecting telescope at Weihai Observatory of Shandong University. By collecting 136 times of minimum light, we studied the orbital period change of VZ Psc. A sinusoidal variation was discovered in the O - C diagram, and the amplitude of 0.d0023 and the period of 17.7 year were obtained. This can be caused by Applegate mechanism or light-time effect. Both the mechanisms are suited according to our investigation, but we prefer the latter that the light-time effect due to the presence of a third body results in the cyclic variation. By using the W-D program, we analyzed the four color light curves. Because of the asymmetric light curves and the possible third body, we used the spot mode of W-D program with and without L3. We found that a hot spot on the primary component with the third light leads to the best result. A very high filling factor of 94.4% ± 2.8% and orbit inclination of 53.2° were obtained.

Longitudinal polarization periodicity of unpolarized light passing through a double wedge depolarizer.

PubMed

de Sande, Juan Carlos G; Santarsiero, Massimo; Piquero, Gemma; Gori, Franco

2012-12-03

The polarization characteristics of unpolarized light passing through a double wedge depolarizer are studied. It is found that the degree of polarization of the radiation propagating after the depolarizer is uniform across transverse planes after the depolarizer, but it changes from one plane to another in a periodic way giving, at different distances, unpolarized, partially polarized, or even perfectly polarized light. An experiment is performed to confirm this result. Measured values of the Stokes parameters and of the degree of polarization are in complete agreement with the theoretical predictions.

Deciphering Periodic Methanol Masers

NASA Astrophysics Data System (ADS)

Stecklum, Bringfried; Caratti o Garatti, Alessio; Henning, Thomas; Hodapp, Klaus; Hopp, Ulrich; Kraus, Alex; Linz, Hendrik; Sanna, Alberto; Sobolev, Andrej; Wolf, Verena

2018-05-01

Impressive progress has been made in recent years on massive star formation, yet the involved high optical depths even at submm/mm wavelengths make it difficult to reveal its details. Recently, accretion bursts of massive YSOs have been identified to cause flares of Class II methanol masers (methanol masers for short) due to enhanced mid-IR pumping. This opens a new window to protostellar accretion variability, and implies that periodic methanol masers hint at cyclic accretion. Pinning down the cause of the periodicity requires joint IR and radio monitoring. We derived the first IR light curve of a periodic maser host from NEOWISE data. The source, G107.298+5.639, is an intermediate-mass YSO hosting methanol and water masers which flare every 34.5 days. Our recent joint K-band and radio observations yielded first but marginal evidence for a phase lag between the rise of IR and maser emission, respectively, and revealed that both NEOWISE and K-band light curves are strongly affected by the light echo from the ambient dust. Both the superior resolution of IRAC over NEOWISE and the longer wavelengths compared to our ground-based imaging are required to inhibit the distractive contamination by the light echo. Thus, we ask for IRAC monitoring of G107 to cover one flare cycle, in tandem with 100-m Effelsberg and 2-m Wendelstein radio and NIR observations to obtain the first high-quality synoptic measurements of this kind of sources. The IR-maser phase lag, the intrinsic shape of the IR light curves and their possible color variation during the cycle allow us to constrain models for the periodic maser excitation. Since methanol masers are signposts of intermediate-mass and massive YSOs, deciphering their variability offers a clue to the dynamics of the accretion-mediated growth of massive stars and their feedback onto the immediate natal environment. The Spitzer light curve of such a maser-hosting YSO would be a legacy science product of the mission.

AN EXTENDED AND MORE SENSITIVE SEARCH FOR PERIODICITIES IN ROSSI X-RAY TIMING EXPLORER/ALL-SKY MONITOR X-RAY LIGHT CURVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levine, Alan M.; Bradt, Hale V.; Chakrabarty, Deepto

2011-09-01

We present the results of a systematic search in {approx}14 years of Rossi X-ray Timing Explorer All-Sky Monitor (ASM) data for evidence of periodicities. Two variations of the commonly used Fourier analysis search method have been employed to significantly improve upon the sensitivity achieved by Wen et al. in 2006, who also searched for periodicities in ASM data. In addition, the present search is comprehensive in terms of sources studied and frequency range covered, and has yielded the detection of the signatures of the orbital periods of eight low-mass X-ray binary systems and of ten high-mass X-ray binaries not listedmore » in the tables of Wen et al. Orbital periods, epochs, signal amplitudes, modulation fractions, and folded light curves are given for each of these systems. Seven of the orbital periods are the most precise reported to date. In the course of this work, the 18.545 day orbital period of IGR J18483-0311 was co-discovered, and the first detections in X-rays were made of the {approx}3.9 day orbital period of LMC X-1 and the {approx}3.79 hr orbital period of 4U 1636-536. The results inform future searches for orbital and other periodicities in X-ray binaries.« less

ASTEROID LIGHT CURVES FROM THE PALOMAR TRANSIENT FACTORY SURVEY: ROTATION PERIODS AND PHASE FUNCTIONS FROM SPARSE PHOTOMETRY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waszczak, Adam; Chang, Chan-Kao; Cheng, Yu-Chi

We fit 54,296 sparsely sampled asteroid light curves in the Palomar Transient Factory survey to a combined rotation plus phase-function model. Each light curve consists of 20 or more observations acquired in a single opposition. Using 805 asteroids in our sample that have reference periods in the literature, we find that the reliability of our fitted periods is a complicated function of the period, amplitude, apparent magnitude, and other light-curve attributes. Using the 805-asteroid ground-truth sample, we train an automated classifier to estimate (along with manual inspection) the validity of the remaining ∼53,000 fitted periods. By this method we findmore » that 9033 of our light curves (of ∼8300 unique asteroids) have “reliable” periods. Subsequent consideration of asteroids with multiple light-curve fits indicates a 4% contamination in these “reliable” periods. For 3902 light curves with sufficient phase-angle coverage and either a reliable fit period or low amplitude, we examine the distribution of several phase-function parameters, none of which are bimodal though all correlate with the bond albedo and with visible-band colors. Comparing the theoretical maximal spin rate of a fluid body with our amplitude versus spin-rate distribution suggests that, if held together only by self-gravity, most asteroids are in general less dense than ∼2 g cm{sup −3}, while C types have a lower limit of between 1 and 2 g cm{sup −3}. These results are in agreement with previous density estimates. For 5–20 km diameters, S types rotate faster and have lower amplitudes than C types. If both populations share the same angular momentum, this may indicate the two types’ differing ability to deform under rotational stress. Lastly, we compare our absolute magnitudes (and apparent-magnitude residuals) to those of the Minor Planet Center’s nominal (G = 0.15, rotation-neglecting) model; our phase-function plus Fourier-series fitting reduces asteroid photometric

A light-responsive and periodic NADH oxidase activity of the cell surface of Tetrahymena and of human buffy coat cells

NASA Technical Reports Server (NTRS)

Peter, A. D.; Morre, D. J.; Morre, D. M.

2000-01-01

Oxidation of external NADH (NADH is an impermeant substrate) by cells of Tetrahymena pyriformis oscillated with a period of 24-26 min. The period length in darkness (25.6 min) appeared to be slightly longer than the period in light (approximately 24 min). When Tetrahymena were placed in darkness for 30-50 min and then returned to light, a new maximum in the rate of NADH oxidation was observed 36-38 min (13 + 24) min after the beginning of the light treatment. The cell-surface NADH oxidase of human buffy coats (a mixture of white cells and platelets) also was periodic and light responsive.

Effects of diurnal, lighting, and angle-of-incidence variation on anterior segment optical coherence tomography (AS-OCT) angle metrics.

PubMed

Akil, Handan; Dastiridou, Anna; Marion, Kenneth; Francis, Brian A; Chopra, Vikas

2017-03-23

First reported study to assess the effect of diurnal variation on anterior chamber angle measurements, as well as, to re-test the effects of lighting and angle-of-incidence variation on anterior chamber angle (ACA) measurements acquired by time-domain anterior segment optical coherence tomography (AS-OCT). A total of 30 eyes from 15 healthy, normal subjects underwent anterior chamber imaging using a Visante time-domain AS-OCT according to an IRB-approved protocol. For each eye, the inferior angle was imaged twice in the morning (8 am - 10 am) and then again in the afternoon (3 pm - 5 pm), under light meter-controlled conditions with ambient room lighting 'ON' and lights 'OFF', and at 5° angle of incidence increments. The ACA metrics measured for each eye were: angle opening distance (AOD, measured 500 and 750 μm anterior from scleral spur), the trabecular-iris-space area (TISA, measured 500 and 750 μm anterior from scleral spur), and scleral spur angle. Measurements were performed by masked, certified Reading Center graders using the Visante's Internal Measurement Tool. Differences in measurements between morning and afternoon, lighting variations, and angle of incidence were compared. Mean age of the participants was 31.2 years (range 23-58). Anterior chamber angle metrics did not differ significantly from morning to afternoon imaging, or when the angle of incidence was offset by 5° in either direction away from the inferior angle 6 o'clock position. (p-value 0.13-0.93). Angle metrics at the inferior corneal limbus, 6 o'clock position (IC270), with room lighting 'OFF', showed a significant decrease (p < 0.05) compared to room lighting 'ON'. There does not appear to be significant diurnal variation in AS-OCT parameters in normal individuals, but lighting conditions need to be strictly controlled since variation in lighting led to significant variability in AS-OCT parameters. No changes in ACA parameters were noted by varying the angle

Search for Exoplanets around Northern Circumpolar Stars III. Long-Period Radial Velocity Variations in HD 18438 and HD 158996

NASA Astrophysics Data System (ADS)

Bang, Tae-Yang; Lee, Byeong-Cheol; Jeong, Gwang-hui; Han, Inwoo; Park, Myeong-Gu

2018-02-01

Detecting exoplanets around giants are useful in understanding the later-stage evolution of planetary systems. We observed the M giant HD 18438 and the K giant HD 158996 as part of a Search for Exoplanets around Northern circumpolar Stars (SENS) and obtained 38 and 24 spectra from 2010 to 2017 using the high-resolution Bohyunsan Observatory Echelle Spectrograph (BOES) at the 1.8m telescope of Bohyunsan Optical Astronomy Observatory in Korea. We obtained precise RV measurements from the spectra and found long-period radial velocity (RV) variations with period 719.0 days for HD 18438 and 820.2 days for HD 158996. We checked the chromospheric activities using Ca II H and H_{α} lines, HIPPARCOS photometry and line bisectors to identify the origin of the observed RV variations. In the case of HD 18438, we conclude that the observed RV variations with period 719.0 days are likely to be caused by the pulsations because the periods of HIPPARCOS photometric and H_{α} EW variations for HD 18438 are similar to that of RV variations in Lomb-Scargle periodogram, and there are no correlations between bisectors and RV measurements. In the case of HD 158996, on the other hand, we did not find any similarity in the respective periodograms nor any correlation between RV variations and line bisector variations. In addition, the probability that the real rotational period can be as longer than the RV period for HD 158996 is only about 4.3%. Thus we conclude that observed RV variations with a period of 820.2 days of HD 158996 are caused by a planetary companion, which has the minimum mass of 14.0 M_{Jup}, the semi-major axis of 2.1 AU, and eccentricity of 0.13 assuming the stellar mass of 1.8 M_{⊙}. HD 158996 is so far one of the brightest and largest stars to harbor exoplanet candidate.

Photometric observations and orbital period variations of HS 0705 + 6700 and NY Vir

NASA Astrophysics Data System (ADS)

Çamurdan, C. M.; Zengin Çamurdan, D.; İbanoǧlu, C.

2012-04-01

We present photometric observations of two post-common-envelope stars, NY Vir (=PG 1336-018) and HS 0705 + 6700. The V band CCD observation of NY Vir was performed by a 40 cm telescope at Ege University Observatory and the R band observations of HS 0705 + 6700 were performed by 100 cm telescope at TÜBİTAK National Observatory. The new light curves were analyzed by the WD code and the physical parameters of stars were determined. We obtained new mid-eclipse timings for HS 0705 + 6700 and combined them with those previously published data. The analysis of the O-C residuals yields a period of about 8.06 ± 0.28 yr and an amplitude of 98.5 s for the system HS 0705 + 6700, which is attributed to the third star physically bounded to the evolved eclipsing pair. A mass function of 1.2 × 10 -4 M⊙ for the third star is obtained. The existence of a third star is also confirmed by the light curve analysis, indicating light contribution of about 0.043 at phase 0.25 in R-bandpass of the eclipsing pair. Using mass-luminosity relationship of the low mass stars we estimate a mass of 0.12 M⊙ with an orbital inclination of about 20°. The O-C residuals obtained for the system NY Vir were represented by a downward parabola which indicates orbital period decrease in the system. Using the coefficient of quadratic term we calculate a rate of orbital period decrease of about dP/ dt = -4.09 × 10 -8days yr -1. The period decrease we have measured in NY Vir may be explained by angular momentum loss from the binary system.

Light directs zebrafish period2 expression via conserved D and E boxes.

PubMed

Vatine, Gad; Vallone, Daniela; Appelbaum, Lior; Mracek, Philipp; Ben-Moshe, Zohar; Lahiri, Kajori; Gothilf, Yoav; Foulkes, Nicholas S

2009-10-01

For most species, light represents the principal environmental signal for entraining the endogenous circadian clock. The zebrafish is a fascinating vertebrate model for studying this process since unlike mammals, direct exposure of most of its tissues to light leads to local clock entrainment. Importantly, light induces the expression of a set of genes including certain clock genes in most zebrafish cell types in vivo and in vitro. However, the mechanism linking light to gene expression remains poorly understood. To elucidate this key mechanism, here we focus on how light regulates transcription of the zebrafish period2 (per2) gene. Using transgenic fish and stably transfected cell line-based assays, we define a Light Responsive Module (LRM) within the per2 promoter. The LRM lies proximal to the transcription start site and is both necessary and sufficient for light-driven gene expression and also for a light-dependent circadian clock regulation. Curiously, the LRM sequence is strongly conserved in other vertebrate per2 genes, even in species lacking directly light-sensitive peripheral clocks. Furthermore, we reveal that the human LRM can substitute for the zebrafish LRM to confer light-regulated transcription in zebrafish cells. The LRM contains E- and D-box elements that are critical for its function. While the E-box directs circadian clock regulation by mediating BMAL/CLOCK activity, the D-box confers light-driven expression. The zebrafish homolog of the thyrotroph embryonic factor binds efficiently to the LRM D-box and transactivates expression. We demonstrate that tef mRNA levels are light inducible and that knock-down of tef expression attenuates light-driven transcription from the per2 promoter in vivo. Together, our results support a model where a light-dependent crosstalk between E- and D-box binding factors is a central determinant of per2 expression. These findings extend the general understanding of the mechanism whereby the clock is entrained by light

To the problem of DQ Herculis orbital period variations.

NASA Astrophysics Data System (ADS)

Dmitrienko, E. S.

The eclipses of the primary component by the secondary one in DQ Her (Nova Her 1934) were analyzed using the light curves obtained by photometrical observations in 1982 - 1986. It is suspected that the value O-C is varying with time according to a sinusoidal law with the period of about 5 years and the amplitude ≡3 - 4 min. The secondary minimum is not shown up on the UBVRI-light curves of DQ Her. That is why the two hypotheses - the apsidal motion and the third component in the system - would seem adequate to explain the sinusoidal change of the value "O-C". By assuming that a probable sinusoidal dependence O-C on time occurs due to apsidal motion, it can be a result of deformation of the secondary component shape, since the contribution from the relativistic motion does not exceed 5%. The obtained value of k2 for the models with zero viscosity is (1 - 5)×10-3 that corresponds to a very high concentration of stellar matter toward the centre of the star. Application of models with the viscosity not equal to zero must lead to the increase of the k2 parameter.

[Geomagnetic field variations in the human prenatal period and cancer in adults].

PubMed

Iamshanov, V A

2007-01-01

Our earlier evidence pointed to a relationship between geomagnetic field (GMF) variations in pre- and early postnatal periods and appearance in the future of oncopathology in these patients. It appears to contribute to risk for such malignancies in adults as breast, lung, liver, bladder, kidney, prostate, hypophysis cancer, ovarian carcinoma, skin melanoma, Hodgkin's disease, lymphoma, and probably stomach cancer. No link was detected between esophageal, thyroid, colorectal cancer or cervical carcinoma, on the one hand, and GMF variations in prenatal period, on the other. It is suggested that low intensity of GMF is associated with increased death of macrophages and other granulocytes as well as nitric oxide formation both in fetal and maternal organism. The latter factor induces genes responsible for detoxication. In adults, under normal or disturbed GMF conditions, detoxication processes take care of excessive blood-nitric oxide. Both in fetus and mother, due to high GMF intensity, granulocyte decay is inhibited thus causing nitric oxide levels to fall. As a consequence, detoxication fails. That accounts for excessive blood-nitric oxide formation at adult stage when GMF intensity is low or normal. Nitric oxide causes certain nitrosamines to form, which are tissue-specific carcinogens. Therefore, the lower level of GMF oscillations was in pre- and early postnatal periods than in more late terms tumors appeared (for example, the negative correlation for breast cancer took place).

Investigating Long-Range Dependence in American Treasury Bills Variations and Volatilities during Stable and Unstable Periods

NASA Astrophysics Data System (ADS)

Lahmiri, Salim

2016-05-01

Detrended fluctuation analysis (DFA) is used to examine long-range dependence in variations and volatilities of American treasury bills (TB) during periods of low and high movements in TB rates. Volatility series are estimated by generalized autoregressive conditional heteroskedasticity (GARCH) model under Gaussian, Student, and the generalized error distribution (GED) assumptions. The DFA-based Hurst exponents from 3-month, 6-month, and 1-year TB data indicates that in general the dynamics of the TB variations process is characterized by persistence during stable time period (before 2008 international financial crisis) and anti-persistence during unstable time period (post-2008 international financial crisis). For volatility series, it is found that; for stable period; 3-month volatility process is more likely random, 6-month volatility process is anti-persistent, and 1-year volatility process is persistent. For unstable period, estimation results show that the generating process is persistent for all maturities and for all distributional assumptions.

The first orbital parameters and period variation of the short-period eclipsing binary AQ Boo

NASA Astrophysics Data System (ADS)

Wang, Shuai; Zhang, Liyun; Pi, Qingfeng; Han, Xianming L.; Zhang, Xiliang; Lu, Hongpeng; Wang, Daimei; Li, TongAn

2016-10-01

We obtained the first VRI CCD light curves of the short-period contact eclipsing binary AQ Boo, which was observed on March 22 and April 19 in 2014 at Xinglong station of National Astronomical Observatories, and on January 20, 21 and February 28 in 2015 at Kunming station of Yunnan Observatories of Chinese Academy of Sciences, China. Using our six newly obtained minima and the minima that other authors obtained previously, we revised the ephemeris of AQ Boo. By fitting the O-C (observed minus calculated) values of the minima, the orbital period of AQ Boo shows a decreasing tendency P˙ = - 1.47(0.17) ×10-7 days/year. We interpret the phenomenon by mass transfer from the secondary (more massive) component to the primary (less massive) one. By using the updated Wilson & Devinney program, we also derived the photometric orbital parameters of AQ Boo for the first time. We conclude that AQ Boo is a near contact binary with a low contact factor of 14.43%, and will become an over-contact system as the mass transfer continues.

Period and pulse duration with "strobe" lights

NASA Astrophysics Data System (ADS)

Birriel, Jennifer

2016-01-01

Strobe lights have traditionally been discussed in The Physics Teacher in the context of stop action strobe photography. During the Halloween season most department and hardware stores sell inexpensive, compact "strobe" lights (although these can be found online year round). These lights generally sell for under 10 and usually employ LED lights. Most such devices have a rotary switch to adjust the rate at which the LED bulbs flash. This rotary switch is not calibrated—i.e., it has no markings to indicate the rate, but in general the greater the rotation of the switch from the off position, the faster the rate of flashing. We show how these simple devices can be used with a light sensor to study both the frequency of flashing and the duration of the light pulse. We briefly discuss if these devices are truly strobe lights.

Ultraviolet photometry from the Orbiting Astronomical Observatory. XXVIII - Ultraviolet light curves for Alpha Lupi and BW Vulpeculae

NASA Technical Reports Server (NTRS)

Lesh, J. R.

1978-01-01

Photometric data from the Wisconsin Experiment Package on OAO-2 have been used to construct light curves at three ultraviolet wavelengths for Alpha Lup and at seven wavelengths for BW Vul. Both stars are well-known variables of the Beta Cephei (Beta Canis Majoris) type. The light curves for Alpha Lup are in good agreement with the radial-velocity period. A temperature variation of 400-500 K is derived. The BW Vul light curves confirm recent ephemerides based on a secularly varying period and show a stillstand near light maximum at some wavelengths. Both stars exhibit increasing light amplitude at the shortest ultraviolet wavelengths. There is little evidence for cycle-to-cycle variations on a time scale of the order of 1 day.

Periodic Variations in Low-Latitudinal Ionosphere during Stratospheric Sudden Warming Event in 2016/2017 Winter

NASA Astrophysics Data System (ADS)

Liu, J.; Zhang, D.

2017-12-01

With datasets of electron density, neutral wind, ionosonde, neutral temperature, and geomagnetism, we studied the low-latitudinal ionosphere in East-Asia sector during Stratospheric Sudden Warming (SSW) Event in 2016/2017 winter, and some periodic variations in several parameters were revealed. A notable quasi-14.5-day (Q14.5D) period was detected in the strength and location of the northern equatorial ionospheric anomaly (EIA) crest shown with total electron content (TEC). As comparison, northern EIA crest in the American sector had similar characters. With data from Wuhan meteor radar and Yunnan MF radar, we found that, within altitude ranging from 80-100 km, wind field also showed above-mentioned periodic variation, which varied in different heights and stations. The Q14.5D period was also revealed in critical frequency (foF2) and peak altitude (hmF2) of F2 layer from two ionosonde stations in southern China. From electron density of Defense Meteorological Satellite Program (DMSP) and TEC of Metop-A, it was shown that this period component is also noticeable in the topside ionosphere above 800 km. However, this character is different in EEJ, of which the Morlet wavelet showed higher strength in quasi-7.5-day period compared to its Q14.5D component.

Variational principle for scattering of light by dielectric particles

NASA Technical Reports Server (NTRS)

Yung, Y. L.

1978-01-01

Consideration is given to the work of Purcell and Pennypacker (1973) where a dielectric particle is taken to be an aggregate of N polarizable elements mounted on a cubic lattice. The simultaneous equations which result from the scattering problem are presented. This theory has been discussed in the case of nonspherical and inhomogeneous objects whose dimensions are smaller than or comparable to the wavelength of incident light. A more precise numerical treatment is derived for further progress. The variational principle is invoked and the practical limit for the current version of the scheme is a dipole array on the order of 10,000 atoms. Limits to the scattering parameter due to the phase difference between neighboring atoms are discussed.

Moonlight affects nocturnal Period2 transcript levels in the pineal gland of the reef fish Siganus guttatus.

PubMed

Sugama, Nozomi; Park, Ji-Gweon; Park, Yong-Ju; Takeuchi, Yuki; Kim, Se-Jae; Takemura, Akihiro

2008-09-01

The golden rabbitfish Siganus guttatus is a reef fish with a restricted lunar-synchronized spawning cycle. It is not known how the fish recognizes cues from the moon and exerts moon-related activities. In order to evaluate the perception and utilization of moonlight by the fish, the present study aimed to clone and characterize Period2 (Per2), a light-inducible clock gene in lower vertebrates, and to examine daily variations in rabbitfish Per2 (rfPer2) expression as well as the effect of light and moonlight on its expression in the pineal gland. The partially-cloned rfPer2 cDNA (2933 bp) was highly homologous (72%) to zebrafish Per2. The rfPer2 levels increased at ZT6 and decreased at ZT18 in the whole brain and several peripheral organs. The rfPer2 expression in the pineal gland exhibited a daily variation with an increase during daytime. Exposing the fish to light during nighttime resulted in a rapid increase of its expression in the pineal gland, while the level was decreased by intercepting light during daytime. Two hours after exposing the fish to moonlight at the full moon period, the rfPer2 expression was upregulated. These results suggest that rfPer2 is a light-inducible clock gene and that its expression is affected not only by daylight but also by moonlight. Since the rfPer2 expression level during the full moon period was higher than that during the new moon period, the monthly variation in the rfPer2 expression is likely to occur with the change in amplitude between the full and new moon periods.

Pigment variations in Emiliania huxleyi (CCMP370) as a response to changes in light intensity or quality.

PubMed

Garrido, José L; Brunet, Christophe; Rodríguez, Francisco

2016-12-01

Many studies on photoacclimation examine the pigment responses to changes in light intensity, but variations in light climate in the aquatic environment are also related to changes in spectral composition. We have employed a high-performance liquid chromatography method with improved resolution towards chlorophyll c and fucoxanthin-related xanthophylls to examine the pigment composition of Emiliania huxleyi CCMP 370 under different light intensities and spectral qualities. To maintain its photosynthetic performance, E. huxleyi CCMP370 promotes drastic pigment changes that can be either the interconversion of pigments in pools with the same basic chromophoric structure (Fucoxanthin type or chlorophyll c type), or the ex novo synthesis (Diatoxanthin). These changes are linked either to variations in light quality (Fucoxanthin related xanthophylls) or in light intensity (chlorophyll c 3 /Monovinyl chlorophyll c 3 , Diadinoxanthin/Diatoxanthin, β,ɛ-carotene/ β,β-carotene). Fucoxanthin and 19'-hexanoyloxyfucoxanthin proportions were highly dependent on spectral conditions. Whereas Fucoxanthin dominated in green and red light, 19'-hexanoyloxyfucoxanthin prevailed under blue spectral conditions. Our results suggest that the huge pigment diversity enhanced the photoacclimative capacities of E. huxleyi to efficiently perform under changing light environments. The ubiquity and success in the global ocean as well as the capacity of E. huxleyi to form large surface blooms might be associated to the plasticity described here. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Patterns of Variation in Teaching the Colour of Light to Primary 3 Students

ERIC Educational Resources Information Center

Ling, Lo Mun; Chik, Pakey; Pang, Ming Fai

2006-01-01

This paper shows how the patterns of variation created in the teaching were critical in helping a class of Primary 3 students in Hong Kong to learn about the colour of light, so that the students attained conceptual rather than procedural knowledge. A "Learning Study" approach was adopted, which is a Lesson Study grounded in a particular…

Pulsations and period variations of the δ Scuti star AN Lyncis in a possible three-body system

NASA Astrophysics Data System (ADS)

Li, Gang; Fu, Jianning; Su, Jie; Fox-Machado, Lester; Michel, Raul; Guo, Zhen; Liu, Jinzhong; Feng, Guojie

2018-01-01

Observations for the δ Scuti star AN Lyn have been made between 2008 and 2016 with the 85-cm telescope at Xinglong station of National Astronomical Observatories of China, the 84-cm telescope at SPM Observatory of Mexico and the Nanshan One metre Wide field Telescope of Xinjiang Observatory of China. Data in V in 50 nights and in R in 34 nights are obtained in total. The bi-site observations from both Xinglong Station and SPM Observatory in 2014 are analysed with Fourier Decomposition to detect pulsation frequencies. Two independent frequencies are resolved, including one non-radial mode. A number of stellar model tracks are constructed with the MESA code and the fit of frequencies leads to the best-fitting model with the stellar mass of M = 1.70 ± 0.05 M⊙, the metallicity abundance of Z = 0.020 ± 0.001, the age of 1.33 ± 0.01 billion years and the period change rate 1/P · dP/dt = 1.06 × 10-9 yr-1, locating the star at the evolutionary stage close to the terminal age main sequence. The O-C diagram provides the period change rate of (1/P)(dP/dt) = 4.5(8) × 10-7 yr-1. However, the period change rate calculated from the models is smaller in two orders than the one derived from the O-C diagram. Together with the sinusoidal function signature, the period variations are regarded to be dominated by the light-travel time effect of the orbital motion of a three-body system with two low-luminosity components, rather than the stellar evolutionary effect.

Variation with semilunar periodicity of plasma steroid hormone production in the mudskipper Boleophthalmus pectinirostris.

PubMed

Wang, Qiong; Hong, Wanshu; Chen, Shixi; Zhang, Qiyong

2008-02-01

Variation in the production of the plasma steroid hormones E(2), 17alpha-OHP and T in females and T and 11-KT in males, was investigated in the mudskipper Boleophthalmus pectinirostris during the spawning season. Females with oocytes at the vitellogenic stage (GSI 5.97-6.86%) and mature males with GSI of 0.255-0.288% were collected at intervals of 3-4 days within the two complete semilunar cycles from May 31 to June 30, 2006. The results showed that variations in the levels of plasma steroid hormones were synchronized obviously with semilunar periodicity in both females and males. Each steroid hormone level exhibited two cycles, each cycle with a peak. In females, the first peaks in plasma E(2), 17alpha-OHP and T levels were observed 3 days after the first lunar quarter, and the second ones, 4 days after the last lunar quarter. In males, the first peaks of plasma T and 11-KT levels occurred 3 days after the first lunar quarter, and the second ones, at the last lunar quarter. The fact that, in the present study, changes in the levels of plasma steroid hormones were synchronized with semilunar periodicity, although the fish were at the same stages of gonadal development, suggests that variation of plasma steroid hormones is basically regulated by biological rhythms (Zeitgebers), and that tidal movement (with its semilunar periodicity) is the major environmental factor stimulating steroid hormone production in B. pectinirostris.

40 CFR 264.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2010 CFR

2010-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 264.1062 Section... Emission Standards for Equipment Leaks § 264.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or operator subject to...

40 CFR 264.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2011 CFR

2011-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 264.1062 Section... Emission Standards for Equipment Leaks § 264.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or operator subject to...

40 CFR 265.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2014 CFR

2014-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 265.1062 Section... FACILITIES Air Emission Standards for Equipment Leaks § 265.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or...

40 CFR 264.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2012 CFR

2012-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 264.1062 Section... Emission Standards for Equipment Leaks § 264.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or operator subject to...

40 CFR 265.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2011 CFR

2011-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 265.1062 Section... FACILITIES Air Emission Standards for Equipment Leaks § 265.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or...

40 CFR 265.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2010 CFR

2010-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 265.1062 Section... FACILITIES Air Emission Standards for Equipment Leaks § 265.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or...

40 CFR 264.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2013 CFR

2013-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 264.1062 Section... Emission Standards for Equipment Leaks § 264.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or operator subject to...

40 CFR 265.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2013 CFR

2013-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 265.1062 Section... FACILITIES Air Emission Standards for Equipment Leaks § 265.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or...

40 CFR 265.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2012 CFR

2012-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 265.1062 Section... FACILITIES Air Emission Standards for Equipment Leaks § 265.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or...

40 CFR 264.1062 - Alternative standards for valves in gas/vapor service or in light liquid service: skip period...

Code of Federal Regulations, 2014 CFR

2014-07-01

... gas/vapor service or in light liquid service: skip period leak detection and repair. 264.1062 Section... Emission Standards for Equipment Leaks § 264.1062 Alternative standards for valves in gas/vapor service or in light liquid service: skip period leak detection and repair. (a) An owner or operator subject to...

Periodic Variations in the O - C Diagrams of Five Pulsation Frequencies of the DB White Dwarf EC 20058-5234

NASA Astrophysics Data System (ADS)

Dalessio, J.; Sullivan, D. J.; Provencal, J. L.; Shipman, H. L.; Sullivan, T.; Kilkenny, D.; Fraga, L.; Sefako, R.

2013-03-01

Variations in the pulsation arrival time of five independent pulsation frequencies of the DB white dwarf EC 20058-5234 individually imitate the effects of reflex motion induced by a planet or companion but are inconsistent when considered in unison. The pulsation frequencies vary periodically in a 12.9 year cycle and undergo secular changes that are inconsistent with simple neutrino plus photon-cooling models. The magnitude of the periodic and secular variations increases with the period of the pulsations, possibly hinting that the corresponding physical mechanism is located near the surface of the star. The phase of the periodic variations appears coupled to the sign of the secular variations. The standards for pulsation-timing-based detection of planetary companions around pulsating white dwarfs, and possibly other variables such as subdwarf B stars, should be re-evaluated. The physical mechanism responsible for this surprising result may involve a redistribution of angular momentum or a magnetic cycle. Additionally, variations in a supposed combination frequency are shown to match the sum of the variations of the parent frequencies to remarkable precision, an expected but unprecedented confirmation of theoretical predictions. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the US National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

Removing tidal-period variations from time-series data using low-pass digital filters

USGS Publications Warehouse

Walters, Roy A.; Heston, Cynthia

1982-01-01

Several low-pass, digital filters are examined for their ability to remove tidal Period Variations from a time-series of water surface elevation for San Francisco Bay. The most efficient filter is the one which is applied to the Fourier coefficients of the transformed data, and the filtered data recovered through an inverse transform. The ability of the filters to remove the tidal components increased in the following order: 1) cosine-Lanczos filter, 2) cosine-Lanczos squared filter; 3) Godin filter; and 4) a transform fitter. The Godin fitter is not sufficiently sharp to prevent severe attenuation of 2–3 day variations in surface elevation resulting from weather events.

Decadal-period external magnetic field variations resolved with eigenanalysis

NASA Astrophysics Data System (ADS)

Shore, Robert; Whaler, Kathryn; Macmillan, Susan; Beggan, Ciarán; Velímský, Jakub; Olsen, Nils

2017-04-01

Variations in the magnetic field at and above the Earth's surface permeate the interior of our planet, and can be used to determine the electrical conductivity of the mantle. Presently, the annual and semi-annual period fields induced by magnetospheric and ionospheric currents, suitable to estimate mantle conductivity in the approximate depth range 1,200-2,000 km, are subject to large uncertainty since they overlap with the periods on which the core field also changes significantly. It is timely to obtain an improved determination of the spatial geometry of the external, inducing, fields in order to better separate their internal, induced, part from that generated in the core. We apply the method of Empirical Orthogonal Functions (EOFs) to a dataset of ground-based magnetic observatory hourly means in order to decompose the external magnetic field during quiet times over a full 11-year solar cycle into its modes of maximum variance. This allows us to assess the spatial structures and magnitude changes of its dominant spatio-temporal patterns. Specifically, our focus is on isolating the long period external inducing fields as they penetrate to the depths of the mantle where the conductivity is least constrained. We expand ground-based measurements in the inertial local-time frame to produce spherical harmonic models of the dominant long period signals isolated by the EOF method. Whilst the ring current dominates the decomposition, we show that an annual and a semi-annual oscillation are important in describing the full inducing field. Each of these terms exhibits a modulation from the 11-year solar cycle. In summary, the most important harmonic in the description of the inducing fields is P10, followed by P21. There are lesser but still significant contributions from the P11 and P20 harmonics.

An Analysis of Light Periods of BL Lac Object S5 0716+714 with the MUSIC Algorithm

NASA Astrophysics Data System (ADS)

Tang, Jie

2012-07-01

The multiple signal classification (MUSIC) algorithm is introduced to the estimation of light periods of BL Lac objects. The principle of the MUSIC algorithm is given, together with a testing on its spectral resolution by using a simulative signal. From a lot of literature, we have collected a large number of effective observational data of the BL Lac object S5 0716+714 in the three optical wavebands V, R, and I from 1994 to 2008. The light periods of S5 0716+714 are obtained by means of the MUSIC algorithm and average periodogram algorithm, respectively. It is found that there exist two major periodic components, one is the period of (3.33±0.08) yr, another is the period of (1.24±0.01) yr. The comparison of the performances of periodicity analysis of two algorithms indicates that the MUSIC algorithm has a smaller requirement on the sample length, as well as a good spectral resolution and anti-noise ability, to improve the accuracy of periodicity analysis in the case of short sample length.

Inferring probabilistic stellar rotation periods using Gaussian processes

NASA Astrophysics Data System (ADS)

Angus, Ruth; Morton, Timothy; Aigrain, Suzanne; Foreman-Mackey, Daniel; Rajpaul, Vinesh

2018-02-01

Variability in the light curves of spotted, rotating stars is often non-sinusoidal and quasi-periodic - spots move on the stellar surface and have finite lifetimes, causing stellar flux variations to slowly shift in phase. A strictly periodic sinusoid therefore cannot accurately model a rotationally modulated stellar light curve. Physical models of stellar surfaces have many drawbacks preventing effective inference, such as highly degenerate or high-dimensional parameter spaces. In this work, we test an appropriate effective model: a Gaussian Process with a quasi-periodic covariance kernel function. This highly flexible model allows sampling of the posterior probability density function of the periodic parameter, marginalizing over the other kernel hyperparameters using a Markov Chain Monte Carlo approach. To test the effectiveness of this method, we infer rotation periods from 333 simulated stellar light curves, demonstrating that the Gaussian process method produces periods that are more accurate than both a sine-fitting periodogram and an autocorrelation function method. We also demonstrate that it works well on real data, by inferring rotation periods for 275 Kepler stars with previously measured periods. We provide a table of rotation periods for these and many more, altogether 1102 Kepler objects of interest, and their posterior probability density function samples. Because this method delivers posterior probability density functions, it will enable hierarchical studies involving stellar rotation, particularly those involving population modelling, such as inferring stellar ages, obliquities in exoplanet systems, or characterizing star-planet interactions. The code used to implement this method is available online.

Long-period sea-level variations in the Mediterranean

NASA Astrophysics Data System (ADS)

Zerbini, Susanna; Raicich, Fabio; Bruni, Sara; del Conte, Sara; Errico, Maddalena; Prati, Claudio; Santi, Efisio

2016-04-01

Since the beginning of its long-lasting lifetime, the Wegener initiative has devoted careful consideration to studying sea-level variations/changes across the Mediterranean Sea. Our study focuses on several long-period sea-level time series (from end of 1800 to 2012) acquired in the Mediterranean by tide gauge stations. In general, the analysis and interpretation of these data sets can provide an important contribution to research on climate change and its impacts. We have analyzed the centennial sea-level time series of six fairly well documented tide gauges. They are: Marseille, in France, Alicante in Spain, Genoa, Trieste, Venice and Marina di Ravenna (formerly Porto Corsini), in Italy. The data of the Italian stations of Marina di Ravenna and Venice clearly indicate that land subsidence is responsible for most of the observed rate of relative sea level rise. It is well known that, in the two areas, subsidence is caused by both natural processes and human activities. For these two stations, using levelling data of benchmarks at, and/or close to, the tide gauges, and for the recent years, also GPS and InSAR height time series, modelling of the long-period non-linear behavior of subsidence was successfully accomplished. After removing the land vertical motions, the estimate of the linear long-period sea-level rise at all six stations yielded remarkably consistent values, between +1,2 and +1,3 mm/yr, with associated errors ranging from ±0,2 to ±0,3 mm/yr (95% confidence interval), which also account for the statistical autocorrelation of the time series. These trends in the Mediterranean area are lower than the global mean rate of 1,7±0,2 mm/yr (1901-2010) presented by the IPCC in its 5th Assessment Report; however, they are in full agreement with a global mean sea-level rise estimate, over the period 1901-1990, recently published by Hay et al. (2015, doi:10.1038/nature14093) and obtained using probabilistic techniques that combine sea-level records with physics

Optical parametric amplification of arbitrarily polarized light in periodically poled LiNbO3.

PubMed

Shao, Guang-hao; Song, Xiao-shi; Xu, Fei; Lu, Yan-qing

2012-08-13

Optical parametric amplification (OPA) of arbitrarily polarized light is proposed in a multi-section periodically poled Lithium Niobate (PPLN). External electric field is applied on selected sections to induce the polarization rotation of involved lights, thus the quasi-phase matched optical parametric processes exhibit polarization insensitivity under suitable voltage. In addition to the amplified signal wave, an idler wave with the same polarization is generated simultaneously. As an example, a ~10 times OPA showing polarization independency is simulated. Applications of this technology are also discussed.

Circadian variation of melatonin, light exposure, and diurnal preference in day and night shift workers of both sexes.

PubMed

Papantoniou, Kyriaki; Pozo, Oscar J; Espinosa, Ana; Marcos, Josep; Castaño-Vinyals, Gemma; Basagaña, Xavier; Ribas, Ferran Calduch; Mirabent, Joan; Martín, Jordi; Carenys, Gemma; Martín, Celia Reyes; Middleton, Benita; Skene, Debra J; Kogevinas, Manolis

2014-07-01

Light-at-night has been shown in experimental studies to disrupt melatonin production but this has only partly been confirmed in studies of night shift workers. In this cross-sectional study, we examined the circadian variation of melatonin in relation to shift status, individual levels of light-at-night exposure, and diurnal preference, an attribute reflecting personal preference for activity in the morning or evening. One hundred and seventeen workers (75 night and 42 day) of both sexes, ages 22 to 64 years, were recruited from four companies. Participants collected urine samples from all voids over 24 hours and wore a data logger continuously recording their light exposure. Sociodemographic, occupational, lifestyle, and diurnal preference information were collected by interview. Concentrations of urinary 6-sulfatoxymelatonin (aMT6s), the main melatonin metabolite, were measured. Mean aMT6s levels were lower in night [10.9 ng/mg creatinine/hour; 95% confidence interval (CI), 9.5-12.6] compared with day workers (15.4; 95% CI, 12.3-19.3). The lowest aMT6s levels were observed in night workers with morning preference (6.4; 95% CI, 3.0-13.6). Peak time of aMT6s production occurred 3 hours later in night (08:42 hour, 95% CI, 07:48-09:42) compared with day workers (05:36 hour, 95% CI, 05:06-06:12). Phase delay was stronger among subjects with higher light-at-night exposure and number of nights worked. Night shift workers had lower levels and a delay in peak time of aMT6s production over a 24-hour period. Differences were modified by diurnal preference and intensity of light-at-night exposure. Night shift work affects levels and timing of melatonin production and both parameters may relate to future cancer risk. ©2014 American Association for Cancer Research.

Dew-worms in white nights: High latitude light constrains earthworm (Lumbricus terrestris) behaviour at the soil surface

USDA-ARS?s Scientific Manuscript database

Soil is an effective barrier to light penetration that limits the direct influence of light on belowground organisms. Variation in aboveground light conditions, however, is important to soil-dwelling animals that are periodically active on the soil surface. A prime example is the earthworm Lumbricus...

[Diurnal variations of grassland evapotranspiration over different periods in the Pailugou basin in the upper reach of the Heihe River, Northwest China.

PubMed

Wang, Zhong Fu; Zhang, Lan Hui; Wang, Yi Bo; He, Chan Sheng

2016-11-18

Evapotranspiration (ET) is an important component of water cycle, but its measurement in high altitude mountainous region is quite difficult, resulting in the poor understanding of the temporal and spatial variations of actual ET in high altitude mountainous region. In this paper, a weighing lysimeter was used to measure the hourly ET in a grassland in the Pailugou basin in the upper reach of the Heihe River, Northwest China. Based on the measured data, diurnal variations of grassland ET over different periods were analyzed. Results indicated that snow and ice sublimation appeared during the freezing period, with a very different diurnal variation pattern compared with other three periods. During the period without sunshine, the amount of snow and ice sublimation was nearly constant. When the highest global radiation and lowest relative humidity appeared in the same period, the amount of snow and ice sublimation increased a little. The early growth period was a period when snow and ice started to melt, during which snowmelt evaporation and soil evaporation occurred at the same time. The growth period had the highest ET rate. Due to continuous rainfall events, maximum and minimum ET values appeared at the same hour. ET in the late growth period mainly came from soil evaporation, producing 3 peaks in diurnal variation, which was different from only one peak in both the early growth period and the growth period.

Generation of light from free electrons.

PubMed

Salisbury, W W

1966-10-21

Experiments with the interaction of a rectangular cross- section beam of electrons which is brought into contact with a metallic diffraction grat e ng produce light variable in wavelength throughout the visible spectrum. Con tinuous variation of the beam thickness shows that light is produced by electrons hundreds of wavelengths from the grating, if the side of the beam near the grating is in contact with it. The results can be accounted for by periodic accelerations of the electrons passing over the surface of the grating. These accelerations are caused by electrostatic forces which in turn are due to the average spacecharge of sheets of elec trons reflected from the grating surface, so that in their space- charge structure the periodicity of the grating rulings is preserved.

Photometric study and absolute parameters of the short-period eclipsing binary HH Bootis

NASA Astrophysics Data System (ADS)

Gürol, B.; Bradstreet, D. H.; Demircan, Y.; Gürsoytrak, S. H.

2015-11-01

We present the results of our investigation on the geometrical and physical parameters of the W UMa type binary system HH Bootis from new CCD (BVRI) light curves and published radial velocity data. The photometric data were obtained in 2011 and 2012 at Ankara University Observatory (AUO). Light and radial velocity observations were analyzed simultaneously using the Wilson-Devinney (2013 revision) code to obtain absolute and geometrical parameters. The system was determined to be a W-type W UMa system of a type different from that suggested by Dal and Sipahi (2013). An interesting cyclic period variation in the time intervals between primary and secondary eclipses ("half-period variation") was discovered and analyzed and its possible cause is discussed. Combining our photometric solution with the spectroscopic data we derived masses and radii of the eclipsing system to be M1 = 0.627M⊙ , M2 = 1.068M⊙ , R1 = 0.782R⊙ and R2 = 0.997R⊙ . New light elements were derived and finally the evolutionary status of the system is discussed.

Light-driven growth in Amazon evergreen forests explained by seasonal variations of vertical canopy structure.

PubMed

Tang, Hao; Dubayah, Ralph

2017-03-07

Light-regime variability is an important limiting factor constraining tree growth in tropical forests. However, there is considerable debate about whether radiation-induced green-up during the dry season is real, or an apparent artifact of the remote-sensing techniques used to infer seasonal changes in canopy leaf area. Direct and widespread observations of vertical canopy structures that drive radiation regimes have been largely absent. Here we analyze seasonal dynamic patterns between the canopy and understory layers in Amazon evergreen forests using observations of vertical canopy structure from a spaceborne lidar. We discovered that net leaf flushing of the canopy layer mainly occurs in early dry season, and is followed by net abscission in late dry season that coincides with increasing leaf area of the understory layer. Our observations of understory development from lidar either weakly respond to or are not correlated to seasonal variations in precipitation or insolation, but are strongly related to the seasonal structural dynamics of the canopy layer. We hypothesize that understory growth is driven by increased light gaps caused by seasonal variations of the canopy. This light-regime variability that exists in both spatial and temporal domains can better reveal the drought-induced green-up phenomenon, which appears less obvious when treating the Amazon forests as a whole.

Editor's Highlight: Periodic Exposure to Smartphone-Mimic Low-Luminance Blue Light Induces Retina Damage Through Bcl-2/BAX-Dependent Apoptosis.

PubMed

Lin, Cheng-Hui; Wu, Man-Ru; Li, Ching-Hao; Cheng, Hui-Wen; Huang, Shih-Hsuan; Tsai, Chi-Hao; Lin, Fan-Li; Ho, Jau-Der; Kang, Jaw-Jou; Hsiao, George; Cheng, Yu-Wen

2017-05-01

Blue light-induced phototoxicity plays an important role in retinal degeneration and might cause damage as a consequence of smartphone dependency. Here, we investigated the effects of periodic exposure to blue light-emitting diode in a cell model and a rat retinal damage model. Retinal pigment epithelium (RPE) cells were subjected to blue light in vitro and the effects of blue light on activation of key apoptotic pathways were examined by measuring the levels of Bcl-2, Bax, Fas ligand (FasL), Fas-associated protein with death domain (FADD), and caspase-3 protein. Blue light treatment of RPE cells increased Bax, cleaved caspase-3, FasL, and FADD expression, inhibited Bcl-2 and Bcl-xL accumulation, and inhibited Bcl-2/Bax association. A rat model of retinal damage was developed with or without continuous or periodic exposure to blue light for 28 days. In this rat model of retinal damage, periodic blue light exposure caused fundus damage, decreased total retinal thickness, caused atrophy of photoreceptors, and injured neuron transduction in the retina. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

A New Light Curve and Analysis of the Long Period Eclipsing Binary BF Draconis

NASA Astrophysics Data System (ADS)

Wolf, G. W.; Craig, L. E.; Caffey, J. F.

1999-01-01

The star BF Draconis was found to be an eclipsing binary by Strohmeier, Knigge and Ott (1962) and originally thought to be an Algol-type system with a period of 5.6 days. A spectrographic study by Imbert (1985) showed that the period was actually double this value and that the system consisted of two well-separated, almost-equal F-type stars in elliptical orbit. Diethelm, Wolf and Agerer (1993) later published a preliminary light curve of this system showing minima of unequal depth and width with a displaced secondary, confirming the elliptical orbit but disagreeing with Imbert on the specific orbital parameters. As a part of our long-term program of obtaining improved light curves of double-lined spectroscopic and eclipsing binaries, we have observed BF Draconis for the past four years using the 0.4 meter telescope at the Baker Observatory of Southwest Missouri State University. Complete light curves in the Cousins BVRI passbands have been obtained with our Photometrics CCD system, and a new model and orbital parameters for the binary have been determined using the Wilson-Devinney program. This research has been supported by NSF Grants AST-9315061 and AST-9605822 and NASA Grant NGT5-40060.

Infrared light-induced protein crystallization. Structuring of protein interfacial water and periodic self-assembly

NASA Astrophysics Data System (ADS)

Kowacz, Magdalena; Marchel, Mateusz; Juknaité, Lina; Esperança, José M. S. S.; Romão, Maria João; Carvalho, Ana Luísa; Rebelo, Luís Paulo N.

2017-01-01

We show that a physical trigger, a non-ionizing infrared (IR) radiation at wavelengths strongly absorbed by liquid water, can be used to induce and kinetically control protein (periodic) self-assembly in solution. This phenomenon is explained by considering the effect of IR light on the structuring of protein interfacial water. Our results indicate that the IR radiation can promote enhanced mutual correlations of water molecules in the protein hydration shell. We report on the radiation-induced increase in both the strength and cooperativeness of H-bonds. The presence of a structured dipolar hydration layer can lead to attractive interactions between like-charged biomacromolecules in solution (and crystal nucleation events). Furthermore, our study suggests that enveloping the protein within a layer of structured solvent (an effect enhanced by IR light) can prevent the protein non-specific aggregation favoring periodic self-assembly. Recognizing the ability to affect protein-water interactions by means of IR radiation may have important implications for biological and bio-inspired systems.

A limit on the variation of the speed of light arising from quantum gravity effects

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2009-10-28

A cornerstone of Einstein's special relativity is Lorentz invariance—the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, l Planck ≈ 1.62 x 10 -33 cm or E Planck = M Planckc 2 ≈ 1.22 x 10 19 GeV), at which quantum effects are expected to strongly affect the nature of space–time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale.more » A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy. Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in γ-ray burst (GRB) light-curves. In this paper, we report the detection of emission up to ~31 GeV from the distant and short GRB 090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2E Planck on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of l Planck/1.2 on the length scale of the effect). Finally, our results disfavour quantum-gravity theories in which the quantum nature of space–time on a very small scale linearly alters the speed of light.« less

A limit on the variation of the speed of light arising from quantum gravity effects.

PubMed

Abdo, A A; Ackermann, M; Ajello, M; Asano, K; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Baring, M G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Bhat, P N; Bissaldi, E; Bloom, E D; Bonamente, E; Bonnell, J; Borgland, A W; Bouvier, A; Bregeon, J; Brez, A; Briggs, M S; Brigida, M; Bruel, P; Burgess, J M; Burnett, T H; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Celik, O; Chaplin, V; Charles, E; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Cominsky, L R; Connaughton, V; Conrad, J; Cutini, S; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; Dingus, B L; do Couto E Silva, E; Drell, P S; Dubois, R; Dumora, D; Farnier, C; Favuzzi, C; Fegan, S J; Finke, J; Fishman, G; Focke, W B; Foschini, L; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Gibby, L; Giebels, B; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Granot, J; Greiner, J; Grenier, I A; Grondin, M-H; Grove, J E; Grupe, D; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hoversten, E A; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Kippen, R M; Knödlseder, J; Kocevski, D; Kouveliotou, C; Kuehn, F; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McBreen, S; McEnery, J E; McGlynn, S; Mészáros, P; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Moretti, E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paciesas, W S; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Petrosian, V; Piron, F; Porter, T A; Preece, R; Rainò, S; Ramirez-Ruiz, E; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rochester, L S; Rodriguez, A Y; Roth, M; Ryde, F; Sadrozinski, H F-W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Stamatikos, M; Stecker, F W; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Toma, K; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Uehara, T; Usher, T L; van der Horst, A J; Vasileiou, V; Vilchez, N; Vitale, V; von Kienlin, A; Waite, A P; Wang, P; Wilson-Hodge, C; Winer, B L; Wood, K S; Wu, X F; Yamazaki, R; Ylinen, T; Ziegler, M

2009-11-19

A cornerstone of Einstein's special relativity is Lorentz invariance-the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, l(Planck) approximately 1.62 x 10(-33) cm or E(Planck) = M(Planck)c(2) approximately 1.22 x 10(19) GeV), at which quantum effects are expected to strongly affect the nature of space-time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale. A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy. Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in gamma-ray burst (GRB) light-curves. Here we report the detection of emission up to approximately 31 GeV from the distant and short GRB 090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2E(Planck) on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of l(Planck)/1.2 on the length scale of the effect). Our results disfavour quantum-gravity theories in which the quantum nature of space-time on a very small scale linearly alters the speed of light.

Natural Genetic Variation for Acclimation of Photosynthetic Light Use Efficiency to Growth Irradiance in Arabidopsis1[OPEN

PubMed Central

Harbinson, Jeremy

2015-01-01

Plants are known to be able to acclimate their photosynthesis to the level of irradiance. Here, we present the analysis of natural genetic variation for photosynthetic light use efficiency (ΦPSII) in response to five light environments among 12 genetically diverse Arabidopsis (Arabidopsis thaliana) accessions. We measured the acclimation of ΦPSII to constant growth irradiances of four different levels (100, 200, 400, and 600 µmol m−2 s−1) by imaging chlorophyll fluorescence after 24 d of growth and compared these results with acclimation of ΦPSII to a step-wise change in irradiance where the growth irradiance was increased from 100 to 600 µmol m−2 s−1 after 24 d of growth. Genotypic variation for ΦPSII is shown by calculating heritability for the short-term ΦPSII response to different irradiance levels as well as for the relation of ΦPSII measured at light saturation (a measure of photosynthetic capacity) to growth irradiance level and for the kinetics of the response to a step-wise increase in irradiance from 100 to 600 µmol m−2 s−1. A genome-wide association study for ΦPSII measured 1 h after a step-wise increase in irradiance identified several new candidate genes controlling this trait. In conclusion, the different photosynthetic responses to a changing light environment displayed by different Arabidopsis accessions are due to genetic differences, and we have identified candidate genes for the photosynthetic response to an irradiance change. The genetic variation for photosynthetic acclimation to irradiance found in this study will allow future identification and analysis of the causal genes for the regulation of ΦPSII in plants. PMID:25670817

Solid State Lighting: A Nanoenabled Case Study in Sustainability

NASA Astrophysics Data System (ADS)

Hicks, Andrea L.

This work uses three household lighting technology options (incandescent, compact fluorescent (CFL), and light emitting diode (LED)) in a nanoenabled case study of artificial lighting. Life cycle assessment (LCA) is used to analyze the environmental impact of three lighting types across all four lifecycle phases: raw materials acquisition, manufacturing, use, and end of life. Using the average United States electricity profile, the use phase is found to have the greatest impact in all nine impact categories defined by TRACI (Tool for the Reduction and Assessment of Chemical and other environmental Impacts). Agent based modeling (ABM) is used to further investigate the use phase with respect to the adoption of energy efficient lighting and the rebound effect. Survey data on the consumer adoption and use of energy efficient lighting technology yields insight into consumer actions and the potential for rebound to occur, and is used to inform the ABM. Based on the results of the ABM analysis it is suggested that regardless of the type of energy efficient lighting, as long as the consumption of light continues to increase, efficiency alone will not reduce energy consumption. Over extended periods of time (~70 years), energy consumption rebounds to levels of pre-efficiency periods. There is a need for policy measures that are coupled with efficiency increases in such a way that energy savings are sustainable. Geographical and temporal variations in electricity profiles and their associated impacts are explored using LCA. It is found that there is the potential for significant variation in the lifetime environmental impact of lighting options based on shifts in the electricity profile. These results suggest the need for effective local policy in coordination with flexible national policy.

The variation of cloud amount and light rainy days under heavy pollution over South China during 1960-2009.

PubMed

Fu, Chuanbo; Dan, Li

2018-01-01

The ground observation data was used to analyze the variation of cloud amount and light precipitation over South China during 1960-2009. The total cloud cover (TCC) decreases in this period, whereas the low cloud cover (LCC) shows the obvious opposite change with increasing trends. LCP defined as low cloud cover/total cloud cover has increased, and small rainy days (< 10 mm day -1 ) decreased significantly (passing 0.001 significance level) during the past 50 years, which is attributed to the enhanced levels of air pollution in the form of anthropogenic aerosols. The horizontal visibility and sunshine duration are used to depict the anthropogenic aerosol loading. When horizontal visibility declines to 20 km or sunshine duration decreases to 5 h per day, LCC increases 52% or more and LCP increases significantly. The correlation coefficients between LCC and horizontal visibility or sunshine duration are - 0.533 and - 0.927, and the values between LCP and horizontal visibility or sunshine duration are - 0.849 and - 0.641, which pass 0.001 significance level. The results indicated that aerosols likely impacted the long-term trend of cloud amount and light precipitation over South China.

Long-term orbital period behaviour of low mass ratio contact binaries GR Vir and FP Boo

NASA Astrophysics Data System (ADS)

Ćetinkaya, Halil; Soydugan, Faruk

2017-02-01

In this study, we investigated orbital period variations of two low mass ratio contact binaries GR Vir and FP Boo based on published minima times. From the O-C analysis, it was found that FP Boo indicates orbital period decrease while the period of GR Vir is increasing. Mass transfer process was used to explain increase and decrease in the orbital periods. In the O-C diagrams of both systems periodic variations also exist. Cyclic changes can be explained as being the result of a light-travel time effect via a third component around the eclipsing binaries. In order to interpret of cyclic orbital period changes for GR Vir, which has late-type components, possible magnetic activity cycles of the components have been also considered.

Research studies using OSO-6 zodiacal light experiment data

NASA Technical Reports Server (NTRS)

1977-01-01

The results of research studies on the OSO-6 zodiacal light experiment, conducted during the period from May 1976 to October 1977 are described. A discussion is included of the instrument performance and the empirical calibrations developed. Main areas of the research performed, i.e., (1) zodiacal light variation analysis; (2) integrated starlight and diffuse galactic light; and (3) earth/moon libration region counterglow, are covered. Considerable data processing was performed during these studies and it is summarized. Recommendations for future research to complete the interim results are given.

Long-period variations in the optical and microphysical parameters of surface aerosol in a Moscow suburb

NASA Astrophysics Data System (ADS)

Isakov, A. A.; Gruzdev, A. N.

2009-04-01

The mass concentration M of surface submicron aerosol and its condensation activity χ were measured at the Zvenigorod Scientific Station of the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, in 2001-2006. Variations in these quantities on scales of several days to several months are analyzed. It is shown that the occurrence of dense and superdense hazes over central Russia became more frequent during these years. This resulted in a change in the character of the seasonal dependence of the mass aerosol concentration M: ordered oscillations whose amplitude increases from year to year appeared in the seasonal cycle of M. Due to more frequent cases of dense and superdense hazes in 2002-2006, a significant monotonic increase is observed in the annual means of M. The annual mean of M increased more than twofold in 2005 (56 μm/m3) compared to 2001 (23 μm/m3). The time regimes of M and χ are characterized by variations with periods in the vicinity of 10, 20, and 40-50 days, as well as variations with longer periods within 70-100 days. In addition, the variability of mass concentration is of a strongly intermittent character. A cross-spectral analysis has shown that, on the whole, variations in M are coherent with those in χ. If the parameters M and χ vary on the same time scales, then, as a rule, variations in M lag behind variations in χ by several days. To understand the relationship between the parameters M and χ, special investigations, including studies of aerosol composition, are needed.

THE RECURRENT INTENSITY VARIATIONS OF PRIMARY COSMIC RADIATION IN PERIODS OF MAXIMUM SOLAR ACTIVITY (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freon, A.; Berry, J.; Coste, J.-P.

1959-02-01

Some recordings of the variations of intensity of cosmic neutrons, made since October 1956 at the observatory of the Pic du Midi and since July 1957 on the Kerguelen Islands, have shown the existence, since the beginning of the observations and during at least 20 solar rotations, of a cyclic variation with a stable period equal to 27.35 plus or minus 0.1 solar days and a maximum amplitude of 2.2% attained in October 1957. (tr-auth)

The hydrostatic gradient, not light availability, drives height-related variation in Sequoia sempervirens (Cupressaceae) leaf anatomy.

PubMed

Oldham, Alana R; Sillett, Stephen C; Tomescu, Alexandru M F; Koch, George W

2010-07-01

Leaves at the tops of most trees are smaller, thicker, and in many other ways different from leaves on the lowermost branches. This height-related variation in leaf structure has been explained as acclimation to differing light environments and, alternatively, as a consequence of hydrostatic, gravitational constraints on turgor pressure that reduce leaf expansion. • To separate hydrostatic effects from those of light availability, we used anatomical analysis of height-paired samples from the inner and outer tree crowns of tall redwoods (Sequoia sempervirens). • Height above the ground correlates much more strongly with leaf anatomy than does light availability. Leaf length, width, and mesophyll porosity all decrease linearly with height and help explain increases in leaf-mass-to-area ratio and decreases in both photosynthetic capacity and internal gas-phase conductance with increasing height. Two functional traits-leaf thickness and transfusion tissue-also increase with height and may improve water-stress tolerance. Transfusion tissue area increases enough that whole-leaf vascular volume does not change significantly with height in most trees. Transfusion tracheids become deformed with height, suggesting they may collapse under water stress and act as a hydraulic buffer that improves leaf water status and reduces the likelihood of xylem dysfunction. • That such variation in leaf structure may be caused more by gravity than by light calls into question use of the terms "sun" and "shade" to describe leaves at the tops and bottoms of tall tree crowns.

An Analysis of Periodic Components in BL Lac Object S5 0716 +714 with MUSIC Method

NASA Astrophysics Data System (ADS)

Tang, J.

2012-01-01

Multiple signal classification (MUSIC) algorithms are introduced to the estimation of the period of variation of BL Lac objects.The principle of MUSIC spectral analysis method and theoretical analysis of the resolution of frequency spectrum using analog signals are included. From a lot of literatures, we have collected a lot of effective observation data of BL Lac object S5 0716 + 714 in V, R, I bands from 1994 to 2008. The light variation periods of S5 0716 +714 are obtained by means of the MUSIC spectral analysis method and periodogram spectral analysis method. There exist two major periods: (3.33±0.08) years and (1.24±0.01) years for all bands. The estimation of the period of variation of the algorithm based on the MUSIC spectral analysis method is compared with that of the algorithm based on the periodogram spectral analysis method. It is a super-resolution algorithm with small data length, and could be used to detect the period of variation of weak signals.

Control effect of periodic variation on the growth of harmful algal bloom causative species

NASA Astrophysics Data System (ADS)

Zhang, L.; Liu, S. T.; Liu, T.; Yu, C.; Hu, Z.

2018-01-01

Blue-green algae and Dinoflagellate etc. are common types of phytoplankton as causative species which cause the harmful algal blooms (HABs). The growth process of causative species is complex according to the variation of the environmental disturbance such as the periodic factor in reality and recent studies have not revealed the secret of the growth complexity yet. Based on the empirical and theoretical results of the growth of causative species, a nonlinear controlled system with periodic factor was obtained and the different effects of the periodic factor on the control of the cell density and the growth rate of causative species were studied by three theorems using the norm theory and finite difference method. Simulations and experimental data were also used to assess the effectiveness of the controlled results.

Silicon monoxide in the 4 micron infrared spectrum of long-period variables

NASA Technical Reports Server (NTRS)

Hinkle, K. H.; Barnes, T. G.; Lambert, D. L.; Beer, R.

1976-01-01

The first-overtone sequence of vibration-rotation transitions of the free radical silicon monoxide are shown to have extreme phase-dependent variations in the spectra of two M-type long-period variables, Omicron Ceti and R Leonis, and the mild S-type long-period variable, Chi Cygni. At maximum light, the SiO band heads are not detectable. Near minimum light, the band heads of (Si-25)O are detected in the 4-micron spectra of all three stars. The band heads of the terrestrially less abundant isotopic species, (Si-29)O and (Si-30)O, are detected in Chi Cygni. Possible explanations of the phase-dependent behavior are discussed, and the role of the stellar chromosphere is considered.

Phase and period responses of the circadian system of mice (Mus musculus) to light stimuli of different duration.

PubMed

Comas, M; Beersma, D G M; Spoelstra, K; Daan, S

2006-10-01

To understand entrainment of circadian systems to different photoperiods in nature, it is important to know the effects of single light pulses of different durations on the free-running system. The authors studied the phase and period responses of laboratory mice (C57BL6J//OlaHsd) to single light pulses of 7 different durations (1, 3, 4, 6, 9, 12, and 18 h) given once per 11 days in otherwise constant darkness. Light-pulse duration affected both amplitude and shape of the phase response curve. Nine-hour light pulses yielded the maximal amplitude PRC. As in other systems, the circadian period slightly lengthened following delays and shortened following advances. The authors aimed to understand how different parts of the light signal contribute to the eventual phase shift. When PRCs were plotted using the onset, midpoint, and end of the pulse as a phase reference, they corresponded best with each other when using the mid-pulse. Using a simple phase-only model, the authors explored the possibility that light affects oscillator velocity strongly in the 1st hour and at reduced strength in later hours of the pulse due to photoreceptor adaptation. They fitted models based on the 1-h PRC to the data for all light pulses. The best overall correspondence between PRCs was obtained when the effect of light during all hours after the first was reduced by a factor of 0.22 relative to the 1st hour. For the predicted PRCs, the light action centered on average at 38% of the light pulse. This is close to the reference phase yielding best correspondence at 36% of the pulses. The result is thus compatible with an initial major contribution of the onset of the light pulse followed by a reduced effect of light responsible for the differences between PRCs for different duration pulses. The authors suggest that the mid-pulse is a better phase reference than lights-on to plot and compare PRCs of different light-pulse durations.

Development of a new model for short period ocean tidal variations of Earth rotation

NASA Astrophysics Data System (ADS)

Schuh, Harald

2015-08-01

Within project SPOT (Short Period Ocean Tidal variations in Earth rotation) we develop a new high frequency Earth rotation model based on empirical ocean tide models. The main purpose of the SPOT model is its application to space geodetic observations such as GNSS and VLBI.We consider an empirical ocean tide model, which does not require hydrodynamic ocean modeling to determine ocean tidal angular momentum. We use here the EOT11a model of Savcenko & Bosch (2012), which is extended for some additional minor tides (e.g. M1, J1, T2). As empirical tidal models do not provide ocean tidal currents, which are re- quired for the computation of oceanic relative angular momentum, we implement an approach first published by Ray (2001) to estimate ocean tidal current veloci- ties for all tides considered in the extended EOT11a model. The approach itself is tested by application to tidal heights from hydrodynamic ocean tide models, which also provide tidal current velocities. Based on the tidal heights and the associated current velocities the oceanic tidal angular momentum (OTAM) is calculated.For the computation of the related short period variation of Earth rotation, we have re-examined the Euler-Liouville equation for an elastic Earth model with a liquid core. The focus here is on the consistent calculation of the elastic Love num- bers and associated Earth model parameters, which are considered in the Euler- Liouville equation for diurnal and sub-diurnal periods in the frequency domain.

The 1991-2012 light curve of the old nova HR Lyrae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Honeycutt, R. K.; Shears, J.; Kafka, S.

2014-05-01

The 22 yr light curve of HR Lyr, acquired with a typical cadence of 2-6 days, is examined for periodic and quasi-periodic variations. No persistent periodicities are revealed. Rather, the light curve variations often take the form of nearly linear rises and falls having typical e-folding times of about 100 days. Occasional ∼0.6 mag outbursts are also seen, with properties similar to those of small outbursts found in some nova-like cataclysmic variables. When the photometry is formed into yearly averages, a decline of 0.012 ± 0.005 mag yr{sup –1} is apparent, consistent with the fading of irradiation-induced M-dot following themore » nova. The equivalent width of Hα is tabulated at three epochs over the interval 1986-2008 in order to compare with a recent result for DK Lac in which Hα was found to be fading 50 yr after the nova. However, our results for such a fading in HR Lyr are inconclusive.« less

Response of a hydrothermal system to magmatic heat inferred from temporal variations in the complex frequencies of long-period events at Kusatsu-Shirane Volcano, Japan

USGS Publications Warehouse

Nakano, M.; Kumagai, H.

2005-01-01

We investigate temporal variations in the complex frequencies (frequency and quality factor Q) of long-period (LP) events that occurred at Kusatsu-Shirane Volcano, central Japan. We analyze LP waveforms observed at this volcano in the period between 1988 and 1995, which covers a seismically active period between 1989 and 1993. Systematic temporal variations in the complex frequencies are observed in October-November 1989, July-October 1991, and September 1992-January 1993. We use acoustic properties of a crack filled with hydrothermal fluids to interpret the observed temporal variations in the complex frequencies. The temporal variations in October-November 1989 can be divided into two periods, which are explained by a gradual decrease and increase of a gas-volume fraction in a water-steam mixture in a crack, respectively. The temporal variations in July-October 1991 can be also divided into two periods. These variations in the first and second periods are similar to those observed in November 1989 and in September-November 1992, respectively, and are interpreted as drying of a water-steam mixture and misty gas in a crack, respectively. The repeated nature of the temporal variations observed in similar seasons between July and November suggests the existence of seasonality in the occurrence of LP events. This may be caused by a seasonally variable meteoritic water supply to a hydrothermal system, which may have been heated by the flux of volcanic gases from magma beneath this volcano. ?? 2005 Elsevier B.V. All rights reserved.

Squeezed-light generation in a nonlinear planar waveguide with a periodic corrugation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perina, Jan Jr.; Haderka, Ondrej; Sibilia, Concita

Two-mode nonlinear interaction (second-harmonic and second-subharmonic generation) in a planar waveguide with a small periodic corrugation at the surface is studied. Scattering of the interacting fields on the corrugation leads to constructive interference that enhances the nonlinear process provided that all the interactions are phase matched. Conditions for the overall phase matching are found. Compared with a perfectly quasi-phase-matched waveguide, better values of squeezing as well as higher intensities are reached under these conditions. Procedure for finding optimum values of parameters for squeezed-light generation is described.

On the day-to-day variation of the equatorial electrojet during quiet periods

NASA Astrophysics Data System (ADS)

Yamazaki, Y.; Richmond, A. D.; Maute, A.; Liu, H.-L.; Pedatella, N.; Sassi, F.

2014-08-01

It has been known for a long time that the equatorial electrojet varies from day to day even when solar and geomagnetic activities are very low. The quiet time day-to-day variation is considered to be due to irregular variability of the neutral wind, but little is known about how variable winds drive the electrojet variability. We employ a numerical model introduced by Liu et al. (2013), which takes into account weather changes in the lower atmosphere and thus can reproduce ionospheric variability due to forcing from below. The simulation is run for May and June 2009. Constant solar and magnetospheric energy inputs are used so that day-to-day changes will arise only from lower atmospheric forcing. The simulated electrojet current shows day-to-day variability of ±25%, which produces day-to-day variations in ground level geomagnetic perturbations near the magnetic equator. The current system associated with the day-to-day variation of the equatorial electrojet is traced based on a covariance analysis. The current pattern reveals return flow at both sides of the electrojet, in agreement with those inferred from ground-based magnetometer data in previous studies. The day-to-day variation in the electrojet current is compared with those in the neutral wind at various altitudes, latitudes, and longitudes. It is found that the electrojet variability is dominated by the zonal wind at 100-120 km altitudes near the magnetic equator. These results suggest that the response of the zonal polarization electric field to variable zonal winds is the main source of the day-to-day variation of the equatorial electrojet during quiet periods.

Effects of approach lighting and variation in visible runway length on perception of approach angle simulated night landings.

DOT National Transportation Integrated Search

1982-02-01

Previous experiments have demonstrated illusions due to variations in both length and width of runways in nighttime 'black hole' approaches. Even though approach lighting is not designed to provide vertical guidance, it is possible that cues from app...

Impacts of diurnal variation of ultraviolet-B and photosynthetically active radiation on phycobiliproteins of the hot-spring cyanobacterium Nostoc sp. strain HKAR-2.

PubMed

Kannaujiya, Vinod K; Sinha, Rajeshwar P

2017-01-01

The effects of diurnal variation of photosynthetically active radiation (PAR; 400-700 nm) and ultraviolet-B (UV-B; 280-315 nm) radiation on phycobiliproteins (PBPs) and photosynthetic pigments (PP) have been studied in the hot-spring cyanobacterium Nostoc sp. strain HKAR-2. The variations in PBPs and PP were monitored by alternating light and dark under PAR, UV-B, and PAR + UV-B radiations over a period of 25 h. There was a decline in the amount of Chl a and PBPs during light periods of UV-B and PAR + UV-B and an increase during dark periods showing a circadian rhythm by destruction and resynthesis of pigment-protein complex. However, a marked induction in carotenoids was recorded during light periods of the same radiations. Moreover, the ratio of Chl a/PE and Chl a/PC was increased in dark periods showing the resynthesis of bleached Chl a. The wavelength shift in emission fluorescence of PBPs toward shorter wavelengths further indicated the bleaching and destruction of PBPs during light periods. Oxidative damage upon exposure to PAR, UV-B, and PAR + UV-B was alleviated by induction of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). The studied cyanobacterium exhibits a significant increase in the activities of SOD, CAT, and APX upon exposure to UV-B and PAR + UV-B radiations. The results indicate that pigment-protein composition of Nostoc sp. stain HKAR-2 was significantly altered during diurnal variation of light/radiation, which might play an important role in optimization for their productivity in a particular cyanobacterium.

Spatial and temporal variation in emergency transport during periods of extreme heat in Japan: A nationwide study.

PubMed

Onozuka, Daisuke; Hagihara, Akihito

2016-02-15

Several studies have reported the burden of climate change on extreme heat-related mortality or morbidity. However, few studies have investigated the spatial and temporal variation in emergency transport during periods of extreme heat on a national scale. Daily emergency ambulance dispatch data from 2007 to 2010 were acquired from all 47 prefectures of Japan. The temporal variability in the relationship between heat and morbidity in each prefecture was estimated using Poisson regression combined with a distributed lag non-linear model and adjusted for time trends. The spatial variability in the heat-morbidity relationships between prefectures was estimated using a multivariate meta-analysis. A total of 5,289,660 emergency transports were reported during the summer months (June through September) within the study period. The overall cumulative relative risk (RR) at the 99th percentile vs. the minimum morbidity percentile was 1.292 (95% CI: 1.251-1.333) for all causes, 1.039 (95% CI: 0.989-1.091) for cardiovascular diseases, and 1.287 (95% CI: 1.210-1.368) for respiratory diseases. Temporal variation in the estimated effects indicated a non-linear relationship, and there were differences in the temporal variations between heat and all-cause and cause-specific morbidity. Spatial variation between prefectures was observed for all causes (Cochran Q test, p<0.001; I(2)=45.8%); however, there was no significant spatial heterogeneity for cardiovascular (Cochran Q test, p=0.054; I(2)=15.1%) and respiratory (Cochran Q test, p=0.681; I(2)=1.0%) diseases. Our nationwide study demonstrated differences in the spatial and temporal variations in the relative risk for all-cause and cause-specific emergency transport during periods of extreme heat in Japan between 2007 and 2010. Our results suggest that public health strategies aimed at controlling heat-related morbidity should be tailored according to region-specific weather conditions. Copyright © 2015 Elsevier B.V. All rights

Seasonal variation in the free-running period in two Talitrus saltator populations from Italian beaches differing in morphodynamics and human disturbance

NASA Astrophysics Data System (ADS)

Nardi, M.; Morgan, E.; Scapini, F.

2003-10-01

The sandhopper Talitrus saltator Montagu (Amphipoda) is a widespread species adapted to different changing environmental conditions and which typically shows a clear circadian rhythm of locomotor activity. The populations from two beaches on the western Italian coast differing in coastline dynamics (eroded versus dynamically stable) and human disturbance (inside a natural park versus freely used and cleaned for leisure) were studied to highlight intrapopulation variation in the endogenous locomotor rhythm. The activity of adult sandhoppers was studied under constant laboratory conditions within individual recording chambers. Variation of the free-running period was analysed at individual level within each population. Greater variability was found than previously reported for the circadian rhythm period of T. saltator, and seasonal variation was shown for the first time. Differences in the level of variation were correlated with coastline dynamics.

The Research of Variation of the Period and Precession of the Rotation Axis of EGS (AJISAI) Satellite by Using Photometric Measurement

NASA Astrophysics Data System (ADS)

Burlak, N.; Koshkin, N.; Korobeynikova, E.; Melikyants, S.; Shakun, L.; Strakhova, S.

The light curves of EGS Ajisai with temporal resolution of 20 ms referred to the time scale UTC (GPS) with an error of at most 0.1 ms were obtained. The observed flashes are produced when the mirrors which cover the spinning satellite's surface reflect off the sunlight. In previous paper the analysis of sequence of flashes allowed of reconstructing the arrangement and orientation of the mirrors, i.e. developing an optogeometric model of the satellite (Korobeynikova et al., 2012), and to apply that model along with new photometric observations to determine the satellite's sidereal rotational period with an accuracy that was previously unachievable. A new technique for determination of the spin-axis orientation during each passage of the satellite over an observation site was developed. The secular slowdown of the satellite's spin rate (Psid = 1.4858*EXP(0.000041099*T), where T is measured in days counted from the date of the satellite launch) and its variations correlating with the average duration of the satellite orbit out of the Earth's shadow were refined. New parameters of the spin-axis precession were estimated: the period Pprec = 116.44 days, αprec = 18.0h, δprec = 87.66°, the nutation angle θ = 1.78°.

Cell growth and lipid accumulation of a microalgal mutant Scenedesmus sp. Z-4 by combining light/dark cycle with temperature variation.

PubMed

Ma, Chao; Zhang, Yan-Bo; Ho, Shih-Hsin; Xing, De-Feng; Ren, Nan-Qi; Liu, Bing-Feng

2017-01-01

The light/dark cycle is one of the most important factors affecting the microalgal growth and lipid accumulation. Biomass concentration and lipid productivity could be enhanced by optimization of light/dark cycles, and this is considered an effective control strategy for microalgal cultivation. Currently, most research on effects of light/dark cycles on algae is carried out under autotrophic conditions and little information is about the effects under mixotrophic cultivation. At the same time, many studies related to mixotrophic cultivation of microalgal strains, even at large scale, have been performed to obtain satisfactory biomass and lipid production. Therefore, it is necessary to investigate cellular metabolism under autotrophic and mixotrophic conditions at different light/dark cycles. Even though microalgal lipid production under optimal environmental factors has been reported by some researchers, the light/dark cycle and temperature are regarded as separate parameters in their studies. In practical cases, light/dark cycling and temperature variation during the day occur simultaneously. Therefore, studies about the combined effects of light/dark cycles and temperature variation on microalgal lipid production are of practical value, potentially providing significant guidelines for large-scale microalgal cultivation under natural conditions. In this work, cell growth and lipid accumulation of an oleaginous microalgal mutant, Scenedesmus sp. Z-4, were investigated at five light/dark cycles (0 h/24 h, 8 h/16 h, 12 h/12 h, 16 h/8 h, and 24 h/0 h) in batch culture. The results showed that the optimal light/dark cycle was 12 h/12 h, when maximum lipid productivity rates of 56.8 and 182.6 mg L -1  day -1 were obtained under autotrophic and mixotrophic cultivation, respectively. Poor microalgal growth and lipid accumulation appeared in the light/dark cycles of 0 h/24 h and 24 h/0 h under autotrophic condition. Prolonging the light duration was

PULSATION PERIOD VARIATIONS IN THE RRc LYRAE STAR KIC 5520878

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hippke, Michael; Learned, John G.; Zee, A.

Learned et al. proposed that a sufficiently advanced extra-terrestrial civilization may tickle Cepheid and RR Lyrae variable stars with a neutrino beam at the right time, thus causing them to trigger early and jogging the otherwise very regular phase of their expansion and contraction. This would turn these stars into beacons to transmit information throughout the galaxy and beyond. The idea is to search for signs of phase modulation (in the regime of short pulse duration) and patterns, which could be indicative of intentional, omnidirectional signaling. We have performed such a search among variable stars using photometric data from themore » Kepler space telescope. In the RRc Lyrae star KIC 5520878, we have found two such regimes of long and short pulse durations. The sequence of period lengths, expressed as time series data, is strongly autocorrelated, with correlation coefficients of prime numbers being significantly higher (p = 99.8%). Our analysis of this candidate star shows that the prime number oddity originates from two simultaneous pulsation periods and is likely of natural origin. Simple physical models elucidate the frequency content and asymmetries of the KIC 5520878 light curve. Despite this SETI null result, we encourage testing of other archival and future time-series photometry for signs of modulated stars. This can be done as a by-product to the standard analysis, and can even be partly automated.« less

Enhanced light extraction of GaN-based light-emitting diodes with periodic textured SiO2 on Al-doped ZnO transparent conductive layer

NASA Astrophysics Data System (ADS)

Yu, Zhao; Bingfeng, Fan; Yiting, Chen; Yi, Zhuo; Zhoujun, Pang; Zhen, Liu; Gang, Wang

2016-07-01

We report an effective enhancement in light extraction of GaN-based light-emitting diodes (LEDs) with an Al-doped ZnO (AZO) transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent through-pore anodic aluminum oxide (AAO) membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 mA and 56% at 100 mA compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage. ).

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns

PubMed Central

Jeong, Hyun; Salas-Montiel, Rafael; Lerondel, Gilles; Jeong, Mun Seok

2017-01-01

In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results. PMID:28374856

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns.

PubMed

Jeong, Hyun; Salas-Montiel, Rafael; Lerondel, Gilles; Jeong, Mun Seok

2017-04-04

In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results.

Daily variation of the response to heat in Rhodnius prolixus: the roles of light and temperature as synchronisers.

PubMed

Fresquet, Nadine; Lazzari, Claudio R

2014-11-01

Triatominae are blood-sucking insects that localise their hosts with their multimodal host associated perceptive signals. Among that sensory information, one of the main short-range cue is heat which, even in isolation, is able to trigger the Proboscis Extension Response (PER) preceding the bite. Previous studies have demonstrated a rhythmic variation of the response to host signals compatible with the nocturnal habits of triatomine insects. This study was aimed at determining whether the PER to heat was also modulated by a daily variation and, if so, if it was an endogenous or exogenous rhythm. We also investigated what was used as a synchroniser between light and temperature. The results showed that alternation of light and darkness was required to ensure a high level of responsiveness to heat in early scotophase while the temperature cycle appeared with a weaker synchronisation power. We concluded that the responsiveness to heat was an exogenous rhythm synchronised by a complementary control of light and temperature cycles. The involvement of two synchronisers hierarchically organised might have increased the plasticity of the host-seeking behaviour to cope with environmental conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessing the effects of architectural variations on light partitioning within virtual wheat–pea mixtures

PubMed Central

Barillot, Romain; Escobar-Gutiérrez, Abraham J.; Fournier, Christian; Huynh, Pierre; Combes, Didier

2014-01-01

Background and Aims Predicting light partitioning in crop mixtures is a critical step in improving the productivity of such complex systems, and light interception has been shown to be closely linked to plant architecture. The aim of the present work was to analyse the relationships between plant architecture and light partitioning within wheat–pea (Triticum aestivum–Pisum sativum) mixtures. An existing model for wheat was utilized and a new model for pea morphogenesis was developed. Both models were then used to assess the effects of architectural variations in light partitioning. Methods First, a deterministic model (L-Pea) was developed in order to obtain dynamic reconstructions of pea architecture. The L-Pea model is based on L-systems formalism and consists of modules for ‘vegetative development’ and ‘organ extension’. A tripartite simulator was then built up from pea and wheat models interfaced with a radiative transfer model. Architectural parameters from both plant models, selected on the basis of their contribution to leaf area index (LAI), height and leaf geometry, were then modified in order to generate contrasting architectures of wheat and pea. Key results By scaling down the analysis to the organ level, it could be shown that the number of branches/tillers and length of internodes significantly determined the partitioning of light within mixtures. Temporal relationships between light partitioning and the LAI and height of the different species showed that light capture was mainly related to the architectural traits involved in plant LAI during the early stages of development, and in plant height during the onset of interspecific competition. Conclusions In silico experiments enabled the study of the intrinsic effects of architectural parameters on the partitioning of light in crop mixtures of wheat and pea. The findings show that plant architecture is an important criterion for the identification/breeding of plant ideotypes, particularly

Investigation of Structure in the Light Curves of a Sample of Newly Discovered Long Period Variable Stars

NASA Astrophysics Data System (ADS)

Craine, E. R.; Culver, R. B.; Eykholt, R.; Flurchick, K. M.; Kraus, A. L.; Tucker, R. A.; Walker, D. K.

2015-09-01

Long period variable stars exhibit hump structures, and possibly flares, in their light curves. While the existence of humps is not controversial, the presence of flaring activity is less clear. Mining of a sky survey database of new variable star discoveries (the first MOTESS-GNAT Variable Star Catalog (MG1-VSC)) has led to identification of 47 such stars for which there are sufficient data to explore the presence of anomalous light curve features. We find a number of hump structures, and see one possible flare, suggesting that they are rare events. We present light curves and measured parameters for these stars, and a population statistical analysis.

Glimpses of stellar surfaces. II. Origins of the photometric modulations and timing variations of KOI-1452

NASA Astrophysics Data System (ADS)

Ioannidis, P.; Schmitt, J. H. M. M.

2016-10-01

The deviations of the mid-transit times of an exoplanet from a linear ephemeris are usually the result of gravitational interactions with other bodies in the system. However, these types of transit timing variations (TTV) can also be introduced by the influences of star spots on the shape of the transit profile. Here we use the method of unsharp masking to investigate the photometric light curves of planets with ambiguous TTV to compare the features in their O-C diagram with the occurrence and in-transit positions of spot-crossing events. This method seems to be particularly useful for the examination of transit light curves with only small numbers of in-transit data points, I.e., the long cadence light curves from Kepler satellite. As a proof of concept we apply this method to the light curve and the estimated eclipse timing variations of the eclipsing binary KOI-1452, for which we prove their non-gravitational nature. Furthermore, we use the method to study the rotation properties of the primary star of the system KOI-1452 and show that the spots responsible for the timing variations rotate with different periods than the most prominent periods of the system's light curve. We argue that the main contribution in the measured photometric variability of KOI-1452 originates in g-mode oscillations, which makes the primary star of the system a γ-Dor type variable candidate.

Evaluation of indoor air composition time variation in air-tight occupied spaces during night periods

NASA Astrophysics Data System (ADS)

Markov, Detelin

2012-11-01

This paper presents an easy-to-understand procedure for prediction of indoor air composition time variation in air-tight occupied spaces during the night periods. The mathematical model is based on the assumptions for homogeneity and perfect mixing of the indoor air, the ideal gas model for non-reacting gas mixtures, mass conservation equations for the entire system and for each species, a model for prediction of basal metabolic rate of humans as well as a model for prediction of O2 consumption rate and both CO2 and H2O generation rates by breathing. Time variation of indoor air composition is predicted at constant indoor air temperature for three scenarios based on the analytical solution of the mathematical model. The results achieved reveal both the most probable scenario for indoor air time variation in air-tight occupied spaces as well as the cause for morning tiredness after having a sleep in a modern energy efficient space.

CSI 2264: Characterizing Young Stars in NGC 2264 With Short-Duration Periodic Flux Dips in Their Light Curves

NASA Technical Reports Server (NTRS)

Stauffer, John; Cody, Ann Marie; McGinnis, Pauline; Rebull, Luisa; Hillenbrand, Lynne A.; Turner, Neal J.; Carpenter, John; Plavchan, Peter; Carey, Sean; Terebey, Susan;

Inter- and Intraspecific Variation in the Germination Response to Light Quality and Scarification in Grasses Growing in Two-phase Mosaics of the Chihuahuan Desert

PubMed Central

PEZZANI, FABIANA; MONTAÑA, CARLOS

2006-01-01

• Background and Aims In many locations, plants are faced with adjacent, contrasting environments, and the between-species differential evolution of life history traits can be interpreted as an evolutionary response to this environmental heterogeneity. However, there has been little research on the intraspecific variability in these attributes as a possible evolutionary response of plants. • Methods In the two-phase mosaic of the Chihuahuan Desert (adjacent patches with contrasting resource availability), analyses were carried out of the germination response to the scarification and light quality to which grass seeds growing on these patches are exposed (open and closed habitats). • Key Results Species that grow in open habitats exhibited a higher germination success than those from closed habitats after scarification. At both the inter- and intraspecific level, there were differences in the germination percentage and in the germination speed in response to light quality. Intraspecific variation in the species from the closed habitat (Pleuraphis mutica and Trichloris crinita) and in Chloris virgata (which grows in both habitats) was due to genetic variation (the family factor was significant), but there was no genetic variation in phenotypic plasticity (non-significant interaction between family and light quality). In contrast, for the species that grows only in the open habitat (Dasyochloa pulchella), the family did not have a significant effect, but there was genetic variation in the phenotypic plasticity (significant interaction between family and light quality). • Conclusions In C. virgata, P. mutica and T. crinita, natural selection could be favouring those genotypes that responded better in each light environment, but it is not possible that the natural selection resulted in different optimal phenotypes in each habitat. On the contrary, in D. pulchella, selection could have reduced the genetic variation, but there is the possibility of the evolution

Inter- and intraspecific variation in the germination response to light quality and scarification in grasses growing in two-phase mosaics of the Chihuahuan Desert.

PubMed

Pezzani, Fabiana; Montaña, Carlos

2006-06-01

In many locations, plants are faced with adjacent, contrasting environments, and the between-species differential evolution of life history traits can be interpreted as an evolutionary response to this environmental heterogeneity. However, there has been little research on the intraspecific variability in these attributes as a possible evolutionary response of plants. In the two-phase mosaic of the Chihuahuan Desert (adjacent patches with contrasting resource availability), analyses were carried out of the germination response to the scarification and light quality to which grass seeds growing on these patches are exposed (open and closed habitats). Species that grow in open habitats exhibited a higher germination success than those from closed habitats after scarification. At both the inter- and intraspecific level, there were differences in the germination percentage and in the germination speed in response to light quality. Intraspecific variation in the species from the closed habitat (Pleuraphis mutica and Trichloris crinita) and in Chloris virgata (which grows in both habitats) was due to genetic variation (the family factor was significant), but there was no genetic variation in phenotypic plasticity (non-significant interaction between family and light quality). In contrast, for the species that grows only in the open habitat (Dasyochloa pulchella), the family did not have a significant effect, but there was genetic variation in the phenotypic plasticity (significant interaction between family and light quality). In C. virgata, P. mutica and T. crinita, natural selection could be favouring those genotypes that responded better in each light environment, but it is not possible that the natural selection resulted in different optimal phenotypes in each habitat. On the contrary, in D. pulchella, selection could have reduced the genetic variation, but there is the possibility of the evolution of reaction norms, resulting in the selection of alternative

Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. II The Second Year (2009-2010)

NASA Astrophysics Data System (ADS)

Kato, Taichi; Maehara, Hiroyuki; Uemura, Makoto; Henden, Arne; de Miguel, Enrique; Miller, Ian; Dubovsky, Pavol A.; Kudzej, Igor; Kiyota, Seiichiro; Hambsch, Franz-Josef; Tanabe, Kenji; Imamura, Kazuyoshi; Kunitomi, Nanae; Takagi, Ryosuke; Nose, Mikiha; Akazawa, Hidehiko; Masi, Gianluca; Nakagawa, Shinichi; Iino, Eriko; Noguchi, Ryo; Matsumoto, Katsura; Fujii, Daichi; Kobayashi, Hiroshi; Ogura, Kazuyuki; Ohtomo, Sachi; Yamashita, Kousei; Yanagisawa, Hirofumi; Itoh, Hiroshi; Bolt, Greg; Monard, Berto; Ohshima, Tomohito; Shears, Jeremy; Ruiz, Javier; Imada, Akira; Oksanen, Arto; Nelson, Peter; Gomez, Tomas L.; Staels, Bart; Boyd, David; Voloshina, Irina B.; Krajci, Thomas; Crawford, Tim; Stockdale, Chris; Richmond, Michael; Morelle, Etienne; Novák, Rudolf; Nogami, Daisaku; Ishioka, Ryoko; Brady, Steve; Simonsen, Mike; Pavlenko, Elena P.; Ringwald, Frederick A.; Kuramoto, Tetsuya; Miyashita, Atsushi; Pickard, Roger D.; Hynek, Tomáš; Dvorak, Shawn; Stubbings, Rod; Muyllaert, Eddy

2010-12-01

Continued from Kato et al. (2009, PASJ, 61, S395), we collected the times of superhump maxima for 68 SU UMa-type dwarf novae, mainly observed during the 2009-2010 season. The newly obtained data confirmed the basic findings reported in Kato et al. (ibid.): the presence of stages A-C and the predominance of positive period derivatives during stage B in systems with superhump periods shorter than 0.07 d. There was a systematic difference in the period derivatives for the systems with superhump periods longer than 0.075 d between this study and Kato et al. (ibid.). We suggest that this difference was possibly caused by a relative lack of frequently outbursting SU UMa-type dwarf novae in this period regime in the present study. We recorded a strong beat phenomenon during the 2009 superoutburst of IY UMa. A close correlation between the beat period and the superhump period suggests that the changing angular velocity of the apsidal motion of the elliptical disk is responsible for the variation of the superhump periods. We also described three new WZ Sge-type objects with established early superhumps and one with likely early superhumps. We suggest that two systems, VX For and EL UMa, are WZ Sge-type dwarf novae with multiple rebrightenings. The O - C variation in OT J213806.6+261957 suggests that the frequent absence of rebrightenings in very short-Porb objects can be the result of a sustained superoutburst plateau at the epoch when usual SU UMa-type dwarf novae return to quiescence, preceding a rebrightening. We also present a formulation for a variety of Bayesian extensions to traditional period analyses.

Survey of period variations of superhumps in SU UMa-type dwarf novae. VIII. The eighth year (2015-2016)

NASA Astrophysics Data System (ADS)

Kato, Taichi; Hambsch, Franz-Josef; Monard, Berto; Vanmunster, Tonny; Maeda, Yutaka; Miller, Ian; Itoh, Hiroshi; Kiyota, Seiichiro; Isogai, Keisuke; Kimura, Mariko; Imada, Akira; Tordai, Tamás; Akazawa, Hidehiko; Tanabe, Kenji; Otani, Noritoshi; Ogi, Minako; Ando, Kazuko; Takigawa, Naoki; Dubovsky, Pavol A.; Kudzej, Igor; Shugarov, Sergey Yu.; Katysheva, Natalia; Golysheva, Polina; Gladilina, Natalia; Chochol, Drahomir; Starr, Peter; Kasai, Kiyoshi; Pickard, Roger D.; de Miguel, Enrique; Kojiguchi, Naoto; Sugiura, Yuki; Fukushima, Daiki; Yamada, Eiji; Uto, Yusuke; Kamibetsunawa, Taku; Tatsumi, Taiki; Takeda, Nao; Matsumoto, Katsura; Cook, Lewis M.; Pavlenko, Elena P.; Babina, Julia V.; Pit, Nikolaj V.; Antonyuk, Oksana I.; Antonyuk, Kirill A.; Sosnovskij, Aleksei A.; Baklanov, Aleksei V.; Kafka, Stella; Stein, William; Voloshina, Irina B.; Ruiz, Javier; Sabo, Richard; Dvorak, Shawn; Stone, Geoff; Andreev, Maksim V.; Antipin, Sergey V.; Zubareva, Alexandra M.; Zaostrojnykh, Anna M.; Richmond, Michael; Shears, Jeremy; Dubois, Franky; Logie, Ludwig; Rau, Steve; Vanaverbeke, Siegfried; Simon, Andrei; Oksanen, Arto; Goff, William N.; Bolt, Greg; Dębski, Bartłomiej; Kochanek, Christopher S.; Shappee, Benjamin; Stanek, Krzysztof Z.; Prieto, José L.; Stubbings, Rod; Muyllaert, Eddy; Hiraga, Mitsutaka; Horie, Tsuneo; Schmeer, Patrick; Hirosawa, Kenji

2016-08-01

Continuing the project described by Kato et al. (2009, PASJ, 61, S395), we collected times of superhump maxima for 128 SU UMa-type dwarf novae observed mainly during the 2015-2016 season and characterized these objects. The data have improved the distribution of orbital periods, the relation between the orbital period and the variation of superhumps, and the relation between period variations and the rebrightening type in WZ Sge-type objects. Coupled with new measurements of mass ratios using growing stages of superhumps, we now have a clearer and statistically greatly improved evolutionary path near the terminal stage of evolution of cataclysmic variables. Three objects (V452 Cas, KK Tel, and ASASSN-15cl) appear to have slowly growing superhumps, which is proposed to reflect the slow growth of the 3 : 1 resonance near the stability border. ASASSN-15sl, ASASSN-15ux, SDSS J074859.55+312512.6, and CRTS J200331.3-284941 are newly identified eclipsing SU UMa-type (or WZ Sge-type) dwarf novae. ASASSN-15cy has a short (˜0.050 d) superhump period and appears to belong to EI Psc-type objects with compact secondaries having an evolved core. ASASSN-15gn, ASASSN-15hn, ASASSN-15kh, and ASASSN-16bu are candidate period bouncers with superhump periods longer than 0.06 d. We have newly obtained superhump periods for 79 objects and 13 orbital periods, including periods from early superhumps. In order that future observations will be more astrophysically beneficial and rewarding to observers, we propose guidelines on how to organize observations of various superoutbursts.

Periodic Anderson model with correlated conduction electrons: Variational and exact diagonalization study

NASA Astrophysics Data System (ADS)

Hagymási, I.; Itai, K.; Sólyom, J.

2012-06-01

We investigate an extended version of the periodic Anderson model (the so-called periodic Anderson-Hubbard model) with the aim to understand the role of interaction between conduction electrons in the formation of the heavy-fermion and mixed-valence states. Two methods are used: (i) variational calculation with the Gutzwiller wave function optimizing numerically the ground-state energy and (ii) exact diagonalization of the Hamiltonian for short chains. The f-level occupancy and the renormalization factor of the quasiparticles are calculated as a function of the energy of the f orbital for a wide range of the interaction parameters. The results obtained by the two methods are in reasonably good agreement for the periodic Anderson model. The agreement is maintained even when the interaction between band electrons, Ud, is taken into account, except for the half-filled case. This discrepancy can be explained by the difference between the physics of the one- and higher-dimensional models. We find that this interaction shifts and widens the energy range of the bare f level, where heavy-fermion behavior can be observed. For large-enough Ud this range may lie even above the bare conduction band. The Gutzwiller method indicates a robust transition from Kondo insulator to Mott insulator in the half-filled model, while Ud enhances the quasiparticle mass when the filling is close to half filling.

[Effects of reversing the feeding cycle and the light period on the spontaneous activity of the rat (author's transl)].

PubMed

Ticca, M

1976-01-01

The amount and the circadian distribution of spontaneous activity in the rat are influenced by a number of factors, whose importance and interrelationships are still deeply discussed. In order to check the reliability of previous studies about the effects of meal-eating on the spontaneous activity (wheel running) of rats of our Sprague-Dawley strain, the adjustment to the modifications of the normal day-night cycle and of the normal nocturnal feeding rhythm have been controlled. Reversing the normal light and dark periods caused the rats, after a 24 hours period, to lower and to irregularly distribute their spontaneous activity. Rats shifted their pattern of maximal activity by 12 hours in the new period of darkness in about five days, and showed to have completely fixed the new reversed running habit. Also feeding habits changed in a similar way, but more slowly. The levels of mean daily activity did not change. In a second experiment, rats, received food during light hours, and were deprived during dark hours. Their activity increased considerably and irregularly during dark hours, while a very slight rise of wheel running was shown during light hours. Body weight gain and food consumption were similar to those of the control group. These results slightly differ from those obtained using other rat strains, and are an interesting example of reinforcement of a spontaneous behavior resulting more from the light-dark cycle than from cues provided by food deprivation.

Effect of high wavelengths low intensity light during dark period on physical exercise performance, biochemical and haematological parameters of swimming rats.

PubMed

Beck, W; Gobatto, C

2016-03-01

Nocturnal rodents should be assessed at an appropriate time of day, which leads to a challenge in identifying an adequate environmental light which allows animal visualisation without perturbing physiological homeostasis. Thus, we analysed the influence of high wavelength and low intensity light during dark period on physical exercise and biochemical and haematological parameters of nocturnal rats. We submitted 80 animals to an exhaustive exercise at individualised intensity under two different illuminations during dark period. Red light (> 600 nm; < 15lux) was applied constantly during dark period (EI; for experimental illumination groups) or only for handling and assessments (SI; for standard illumination groups). EI led to worse haematological and biochemical conditions, demonstrating that EI alone can influence physiological parameters and jeopardise result interpretation. SI promotes normal physiological conditions and greater aerobic tolerance than EI, showing the importance of a correct illumination pattern for all researchers that employ nocturnal rats for health/disease or sports performance experiments.

Efficiency of ETV diagrams as diagnostic tools for long-term period variations. II. Non-conservative mass transfer, and gravitational radiation

NASA Astrophysics Data System (ADS)

Nanouris, N.; Kalimeris, A.; Antonopoulou, E.; Rovithis-Livaniou, H.

2015-03-01

Context. The credibility of an eclipse timing variation (ETV) diagram analysis is investigated for various manifestations of the mass transfer and gravitational radiation processes in binary systems. The monotonicity of the period variations and the morphology of the respective ETV diagrams are thoroughly explored in both the direct impact and the accretion disk mode of mass transfer, accompanied by different types of mass and angular momentum losses (through a hot-spot emission from the gainer and via the L2/L3 points). Aims: Our primary objective concerns the traceability of each physical mechanism by means of an ETV diagram analysis. Also, possible critical mass ratio values are sought for those transfer modes that involve orbital angular momentum losses strong enough to dictate the secular period changes even when highly competitive mechanisms with the opposite direction act simultaneously. Methods: The dot{J-dot{P}} relation that governs the orbital evolution of a binary system is set to provide the exact solution for the period and the function expected to represent the subsequent eclipse timing variations. The angular momentum transport is parameterized through appropriate empirical relations, which are inferred from semi-analytical ballistic models. Then, we numerically determine the minimum temporal range over which a particular mechanism is rendered measurable, as well as the critical mass ratio values that signify monotonicity inversion in the period modulations. Results: Mass transfer rates comparable to or greater than 10-8 M⊙ yr-1 are measurable for typical noise levels of the ETV diagrams, regardless of whether the process is conservative. However, the presence of a transient disk around the more massive component defines a critical mass ratio (qcr ≈ 0.83) above which the period turns out to decrease when still in the conservative regime, rendering the measurability of the anticipated variations a much more complicated task. The effects of

Rats fed only during the light period are resistant to stress-induced weight loss.

PubMed

Harris, Ruth B S; Zhou, Jun; Mitchell, Tiffany; Hebert, Sadie; Ryan, Donna H

2002-08-01

Repeated restraint stress (3 h/day for 3 days) causes a chronic down-regulation of body weight in rats. This study determined whether weight loss was influenced by the time of day that rats had access to food or that stress was applied. Groups of male Sprague-Dawley rats were fed a 40% kcal fat diet with food given ad libitum, only during the light phase or only during the dark phase. After 2 weeks of adaptation, rats within each feeding treatment were divided into four groups. One was exposed to repeated restraint at the start of the light phase, another was restrained at the start of the dark phase and the remaining groups were nonstressed controls for restrained rats. Body weight was significantly reduced in ad libitum- and dark-fed restrained rats, compared with nonstressed controls, from Day 2 of restraint, regardless of the time of day that they were stressed. There was no significant effect of restraint on weight change of light-fed rats. Food intake was inhibited by stress in ad libitum- and dark-fed rats, but it was not changed in light-fed rats. Serum corticosterone was increased by restraint in all rats irrespective of feeding schedule. This study demonstrates that stress-induced weight loss only occurs when rats have food available during their normal feeding period (dark phase) and is not determined by increased corticosterone release.

Changing Amplitudes: Detecting RR Lyrae Light Curve Shape Variations in the Galactic Disk and Inner Halo

NASA Astrophysics Data System (ADS)

De Lee, Nathan M.; Kinemuchi, K.; Pepper, J.; Rodriguez, J. E.

2014-01-01

In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-8 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 9,000 epochs per light curve with completeness out to 3 kpc from the Sun. Recent results from both Kepler and ground based surveys results suggest that as many as 50% of RR Lyrae stars show long-term modulation of their light curve shapes (Blazhko effect). These stars combined with RRL stars that pulsate in more than one mode give a sample of objects that the KELT survey is uniquely suited to explore. This poster concentrates on a pilot project to examine RRL stars in a limited number of KELT fields. In particular, we focus on, detecting RR Lyrae, developing a light curve shape-metallicity relationship in the KELT band-pass, and some initial characterization of RRL with either amplitude-modulated or period-modulated light curves.

Optical properties of periodic, quasi-periodic, and disordered one-dimensional photonic structures

NASA Astrophysics Data System (ADS)

Bellingeri, Michele; Chiasera, Alessandro; Kriegel, Ilka; Scotognella, Francesco

2017-10-01

Photonic structures are building blocks for many optical applications in which light manipulation is required spanning optical filtering, lasing, light emitting diodes, sensing and photovoltaics. The fabrication of one-dimensional photonic structures is achievable with a variety of different techniques, such as spin coating, sputtering, evaporation, pulse laser deposition, or extrusion. Such different techniques enable facile integration of the photonic structure with many types of devices. Photonic crystals are characterized by a spatial modulation of the dielectric constant on the length scale of the wavelength of light giving rise to energy ranges where light cannot propagate through the crystal - the photonic band gap. While mostly photonic crystals are referred to as periodic arrangements, in this review we aim to highlight as well how aperiodicity and disorder affects light modulation. In this review article, we introduce the concepts of periodicity, quasi-periodicity, and disorder in photonic crystals, focussing on the one-dimensional case. We discuss in detail the physical peculiarities, the fabrication techniques, and the applications of periodic, quasi-periodic, and disorder photonic structures, highlighting how the degree of crystallinity matters in the manipulation of light. We report different types of disorder in 1D photonic structures and we discuss their properties in terms of light transmission. We discuss the relationship between the average total transmission, in a range of wavelengths around the photonic band gap of the corresponding photonic crystal, and the homogeneity of the photonic structures, quantified by the Shannon index. Then we discuss the light transmission in structures in which the high refractive index layers are aggregated in clusters following a power law distribution. Finally, in the case of structures in which the high refractive index layers are aggregated in clusters with a truncated uniform distribution, we discuss: i) how

Orbital period changes in RW CrA, DX Vel and V0646 Cen

NASA Astrophysics Data System (ADS)

Volkov, I. M.; Chochol, D.; Grygar, J.; Mašek, M.; Juryšek, J.

2017-06-01

We aim to determine the absolute parameters of the components of southern Algol-type binaries with deep eclipses RW CrA, DX Vel, V0646 Cen and interpret their orbital period changes. The data analysis is based on a high quality Walraven photoelectric photometry, obtained in the 1960-70s, our recent CCD photometry, ASAS (Pojmanski, 2002), and Hipparcos (Perryman et al., 1997) photometry of the objects. Their light curves were analyzed using the PHOEBE program with fixed effective temperatures of the primary components, found from disentangling the Walraven (B-U) and (V-B) colour indices. We found the absolute parameters of the components of all three objects. All reliable observed times of minimum light were used to construct and analyze the Eclipse Time Variation (ETV) diagrams. We interpreted the ETV diagrams of the detached binary RW CrA and the semi-detached binary DX Vel by a LIght-Time Effect (LITE), estimated parameters of their orbits and masses of their third bodies. We suggest a long term variation of the inclination angle of both eclipsing binaries, caused by a non-coplanar orientation of their third body orbits. We interpreted the detected orbital period increase in the semi-detached binary V0646 Cen by a mass transfer from the less to more massive component with the rate M⊙ = 6.08×10-9 M⊙/yr.

Photometric long-term variations and superhump occurrence in the Classical Nova RR Pictoris

NASA Astrophysics Data System (ADS)

Fuentes-Morales, I.; Vogt, N.; Tappert, C.; Schmidtobreick, L.; Hambsch, F.-J.; Vučković, M.

2018-02-01

We present an analysis of all available time-resolved photometry from the literature and new light curves obtained in 2013-2014 for the old nova RR Pictoris. The well-known hump light curve phased with the orbital period reveals significant variations over the last 42 yr in shape, amplitude and other details which apparently are caused by long-term variations in the disc structure. In addition, we found evidence for the presence of superhumps in 2007, with the same period ( ˜ 9 per cent longer than the orbital period), as reported earlier by other authors from observations in 2005. Possibly, superhumps arise quickly in RR Pic, but are sporadic events, because in all the other observing runs analysed no significant superhump signal was detected. We also determined an actual version of the Stolz-Schoembs relation between superhump period and orbital period, analysing separately dwarf novae, classical novae and nova-like stars, and conclude that this relation is of general validity for all superhumpers among the cataclysmic variables (CVs), in spite of small but significant differences among the sub-types mentioned above. We emphasize the importance of such a study in context with the still open question of the interrelation between the different sub-classes of CVs, crucial for our understanding of the long-term CV evolution.

A search for periodicity in the x ray spectrum of black hole candidate A0620-00

NASA Technical Reports Server (NTRS)

Clark, George W.; Plaks, Kenneth

1991-01-01

The archived data from the SAS-3 observations of the X-ray nova A0620-00, the best of the stellar blackhole candidates, were exhaustively examined for evidence of variable phenomena correlated with the orbital motion of the binary system of which it is a member. The original analysis of these data was completed before discovery of the binary companion and determination of the orbital period of the system. New interest was drawn to the task of a reexamination of the archive data by the recent discovery of the massive nature of the X-ray source through analysis of the Doppler variations and ellipsoidal light variations of the faint K-star companion by McClintock and Remillard. The archive research, carried out under the supervision of the principal investigator, was the topic of the thesis submitted to the MIT Department of Physics by Kenneth Plaks in partial fulfillment of the requirements for the degree of Master of Science. Plaks' effort was focused on the elimination of fluctuations in the data due to errors in attitude solutions and other extraneous causes. The first products of his work were long-term light curves of the X-ray intensities in the various energy channels as functions of time during the time from outbursts in August 1975 to quiescence approximately 6 months later. These curves, are refined versions of the preliminary results published in 1976 (Matilsky et al. 1976). Smooth exponentials were fitted to these long term light curves to provide the basis for detrending the data, thereby permitting a calculation of residuals derived by subtracting the fitted curve from the data. The residuals were then analyzed by Fourier analysis to search for variations with the period of the binary orbit, namely 7.75 hours. No evidence of an orbital periodicity was found. However, the refined light curve provides a much clearer picture of the outburst and subsequent decay of the X-ray luminosity. In fact, there were two outbursts, each followed by an exponential

The effect of light and dark periods on the production of ethylene from water-stressed wheat leaves.

PubMed

Wright, S T

1981-10-01

inhibition!) for over 2 h before the rate began to decline, and for a much longer period (i.e. in excess of 41/2 h) if the leaves had previously been sprayed with BA. Predictably, leaves placed in the light (i.e. in leaf chambers) and then transferred to darkness, immediately or very soon produced ethylene at the dark rate. One explanation of these results, which is discussed, would be that the biosynthesis of an ethylene precursor requires an obligatory dark stage. The possible implications of these studies to a survival role of ethylene in plants during periods of water stress is discussed.

Melanopsin-Mediated Acute Light Responses Measured in Winter and in Summer: Seasonal Variations in Adults with and without Cataracts.

PubMed

Münch, Mirjam; Ladaique, Myriam; Roemer, Ségolène; Hashemi, Kattayoon; Kawasaki, Aki

2017-01-01

Seasonal adaptation is a ubiquitous behavior seen in many species on both global hemispheres and is conveyed by changing photoperiods. In humans this seasonal adaptation is less apparent, in part because changes in daylength are masked by the use of electrical lighting at night. On the other hand, cataracts which reduce light transmission, may compound seasonal changes related to the reduced daylength of winter. To better understand the effects of different photoperiod lengths in healthy adults without and with cataracts, we tested their melanopsin-mediated light responses in summer vs. winter. Fifty-two participants (mean age 67.4 years; 30 with bilateral cataracts and 22 age-matched controls with clear lenses; pseudophakes) were tested twice, once in summer and once in winter. At each test session we assessed the electroretinogram and pupil responses during daytime and we determined melatonin suppression, subjective sleepiness and mood in response to light exposure in the evening. Circadian rest-activity cycles and sleep from activity recordings were also analyzed for both seasons. Both groups had similar visual function. There were no seasonal differences in the electroretinogram. For the pupil responses to bright blue light, the post-illumination pupil response (PIPR) was greater in winter than summer in pseudophakes, but not in cataract participants, whereas melatonin suppression to acute light exposure showed no differences between both groups and seasons. Overall, intra-daily variability of rest-activity was worse in winter but participants felt sleepier and reported worse mood at the laboratory in evening time in the summer. Those with cataracts had poorer sleep quality with lower sleep efficiency, and higher activity during sleep in winter than summer. In this study, the PIPR showed a seasonal variation in which a larger response was found during winter. This variation was only detected in participants with a clear intraocular lens. In the cataract group

Melanopsin-Mediated Acute Light Responses Measured in Winter and in Summer: Seasonal Variations in Adults with and without Cataracts

PubMed Central

Münch, Mirjam; Ladaique, Myriam; Roemer, Ségolène; Hashemi, Kattayoon; Kawasaki, Aki

2017-01-01

Seasonal adaptation is a ubiquitous behavior seen in many species on both global hemispheres and is conveyed by changing photoperiods. In humans this seasonal adaptation is less apparent, in part because changes in daylength are masked by the use of electrical lighting at night. On the other hand, cataracts which reduce light transmission, may compound seasonal changes related to the reduced daylength of winter. To better understand the effects of different photoperiod lengths in healthy adults without and with cataracts, we tested their melanopsin-mediated light responses in summer vs. winter. Fifty-two participants (mean age 67.4 years; 30 with bilateral cataracts and 22 age-matched controls with clear lenses; pseudophakes) were tested twice, once in summer and once in winter. At each test session we assessed the electroretinogram and pupil responses during daytime and we determined melatonin suppression, subjective sleepiness and mood in response to light exposure in the evening. Circadian rest-activity cycles and sleep from activity recordings were also analyzed for both seasons. Both groups had similar visual function. There were no seasonal differences in the electroretinogram. For the pupil responses to bright blue light, the post-illumination pupil response (PIPR) was greater in winter than summer in pseudophakes, but not in cataract participants, whereas melatonin suppression to acute light exposure showed no differences between both groups and seasons. Overall, intra-daily variability of rest-activity was worse in winter but participants felt sleepier and reported worse mood at the laboratory in evening time in the summer. Those with cataracts had poorer sleep quality with lower sleep efficiency, and higher activity during sleep in winter than summer. In this study, the PIPR showed a seasonal variation in which a larger response was found during winter. This variation was only detected in participants with a clear intraocular lens. In the cataract group

Lighting constraints on lunar surface operations

NASA Technical Reports Server (NTRS)

Eppler, Dean B.

1991-01-01

An investigation into the levels of ambient lighting on the lunar surface indicates that for most nearside locations, illumination will be adequate throughout most of the lunar night to conduct EVAs with only minor artificial illumination. The maximum lighting available during the lunar night from Earthshine will be similar to the light level on a July evening at approximately 8:00 pm in the southern United States (approximately 15 minutes after sunset). Because of the captured rotation of the Moon about the Earth, the location of the Earth will remain approximately constant throughout the lunar night, with consequent constant shadow length and angle. Variations in the level of Earthside illumination will be solely a function of Earth phase angle. Experience during the Apollo Program suggests that EVA activities during the period around the lunar noon may be difficult due to lack of surface definition caused by elimination of shadows.

Beat-to-Beat Variation in Periodicity of Local Calcium Releases Contributes to Intrinsic Variations of Spontaneous Cycle Length in Isolated Single Sinoatrial Node Cells

PubMed Central

Monfredi, Oliver; Maltseva, Larissa A.; Spurgeon, Harold A.; Boyett, Mark R.; Lakatta, Edward G.; Maltsev, Victor A.

2013-01-01

Spontaneous, submembrane local Ca2+ releases (LCRs) generated by the sarcoplasmic reticulum in sinoatrial nodal cells, the cells of the primary cardiac pacemaker, activate inward Na+/Ca2+-exchange current to accelerate the diastolic depolarization rate, and therefore to impact on cycle length. Since LCRs are generated by Ca2+ release channel (i.e. ryanodine receptor) openings, they exhibit a degree of stochastic behavior, manifested as notable cycle-to-cycle variations in the time of their occurrence. Aim The present study tested whether variation in LCR periodicity contributes to intrinsic (beat-to-beat) cycle length variability in single sinoatrial nodal cells. Methods We imaged single rabbit sinoatrial nodal cells using a 2D-camera to capture LCRs over the entire cell, and, in selected cells, simultaneously measured action potentials by perforated patch clamp. Results LCRs begin to occur on the descending part of the action potential-induced whole-cell Ca2+ transient, at about the time of the maximum diastolic potential. Shortly after the maximum diastolic potential (mean 54±7.7 ms, n = 14), the ensemble of waxing LCR activity converts the decay of the global Ca2+ transient into a rise, resulting in a late, whole-cell diastolic Ca2+ elevation, accompanied by a notable acceleration in diastolic depolarization rate. On average, cells (n = 9) generate 13.2±3.7 LCRs per cycle (mean±SEM), varying in size (7.1±4.2 µm) and duration (44.2±27.1 ms), with both size and duration being greater for later-occurring LCRs. While the timing of each LCR occurrence also varies, the LCR period (i.e. the time from the preceding Ca2+ transient peak to an LCR’s subsequent occurrence) averaged for all LCRs in a given cycle closely predicts the time of occurrence of the next action potential, i.e. the cycle length. Conclusion Intrinsic cycle length variability in single sinoatrial nodal cells is linked to beat-to-beat variations in the average period of individual LCRs

Dietary intake variations from pre-conception to gestational period according to the degree of industrial processing: A Brazilian cohort.

PubMed

Alves-Santos, Nadya Helena; Eshriqui, Ilana; Franco-Sena, Ana Beatriz; Cocate, Paula Guedes; Freitas-Vilela, Ana Amélia; Benaim, Camila; Vaz, Juliana Dos Santos; Castro, Maria Beatriz Trindade; Kac, Gilberto

2016-10-01

To estimate food intake changes from pre-conception to gestational period according to the degree of food processing. Prospective cohort conducted in a public health care center in Rio de Janeiro with Brazilian pregnant women (n = 189). A food frequency questionnaire was applied at the first (5(th)-13(th)) and third (30(th)-36(th)) gestational trimesters. The food items were classified according to characteristics of food processing in four groups: unprocessed/minimally processed foods; sugar/fat; processed foods and ultra-processed foods. The variation of food intake according to the degree of processing between the pre-conception and gestational period was compared using paired Student's t-test. Linear regression models were performed to estimate the association of mother's characteristics on the variation of food group contribution to the total energy intake between periods. Total energy intake was 2415 (SD = 813) in the pre-conception and 2379 (750) kcal in the gestational period. We excluded women who had implausible total energy intake (<600 and >6000 kcal/day). The contribution of unprocessed/minimally processed food group to total energy intake during pregnancy when compared to the pre-conception period was higher [50.5 (14.1) vs. 48.8 (12.4), p-value = 0.048], while the caloric share of ultra-processed food group was lower [41.3 (14.6) vs. 43.1 (12.5), p-value = 0.032]. We observed a negative association of age (p-value = 0.009) and a positive association of pre-pregnancy BMI (p-value = 0.060) with the variation of ultra-processed food intake. Ultra-processed food intake decreased, while minimally/unprocessed food intake slightly increased from the pre-conception to gestational period. These results indicate potential for a larger improvement in the women's diet quality and that nutritional counseling interventions in pregnant women are still needed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evidence for Periodicity in 43 year-long Monitoring of NGC 5548

NASA Astrophysics Data System (ADS)

Bon, E.; Zucker, S.; Netzer, H.; Marziani, P.; Bon, N.; Jovanović, P.; Shapovalova, A. I.; Komossa, S.; Gaskell, C. M.; Popović, L. Č.; Britzen, S.; Chavushyan, V. H.; Burenkov, A. N.; Sergeev, S.; La Mura, G.; Valdés, J. R.; Stalevski, M.

2016-08-01

We present an analysis of 43 years (1972 to 2015) of spectroscopic observations of the Seyfert 1 galaxy NGC 5548. This includes 12 years of new unpublished observations (2003 to 2015). We compiled about 1600 Hβ spectra and analyzed the long-term spectral variations of the 5100 Å continuum and the Hβ line. Our analysis is based on standard procedures, including the Lomb-Scargle method, which is known to be rather limited to such heterogeneous data sets, and a new method developed specifically for this project that is more robust and reveals a ˜5700 day periodicity in the continuum light curve, the Hβ light curve, and the radial velocity curve of the red wing of the Hβ line. The data are consistent with orbital motion inside the broad emission line region of the source. We discuss several possible mechanisms that can explain this periodicity, including orbiting dusty and dust-free clouds, a binary black hole system, tidal disruption events, and the effect of an orbiting star periodically passing through an accretion disk.

Analysis of longer period variation of the Kuroshio Current intrusion into the Luzon Strait using rectified wavelet power spectra

NASA Astrophysics Data System (ADS)

Yuan, Yaochu; Yang, Chenghao; Tseng, Yu-heng; Zhu, Xiao-Hua; Wang, Huiqun; Chen, Hong

2017-08-01

Longer period variation of the Kuroshio into the Luzon Strait (LS) was identified using acoustic Doppler current profiler (ADCP) observations as well as pressure and temperature time series data recorded by two TDs (manufactured by the RBR Ltd.) at mooring station N2 (20°40.441‧N, 120°38.324‧E). The ADCP was deployed at depths of 50-300 m between July 7, 2009 and April 10, 2011, and the TDs at around 340 and 365 m between July 9, 2009 and July 9, 2011. Observations provide strong evidence of longer period variation of the Kuroshio into the LS using the Vector rotary spectra (VRS) and Rectified wavelet power spectra analysis (RWPSA). RWPSA of the observations allowed the identification of two types of dominant periods. The first type, with the strongest power spectral density (PSD), had a dominant period of 112 d and was found throughout the upper 300 m. For example, the maximum PSD for western and northern velocity components time series were 3800 and 3550 at 50 m, respectively. The maximum power spectral density decrease with deeper depths, i.e., the depth dependence of maximum PSD. The 112 d period was also identified in the pressure and temperature time series data, at 340 m and 365 m. Combined RWPSA with VRS and mechanism analysis, it is clear that the occurrence of the most dominant period of 112 d in the upper 300 m is related to the clockwise meandering of the Kuroshio into the LS, which is caused by westward propagating stronger anticyclonic eddies from the interior ocean due to the interaction of Rossby eddies with the Kuroshio. The second type of dominant period, for example a 40 d period, is related to the anticlockwise meandering of the Kuroshio. The final dominant period of 14 d coincides with the fortnightly spring-neap tidal period.

Photometric Variability of the mCP Star CS Vir: Evolution of the Rotation Period

NASA Astrophysics Data System (ADS)

Ozuyar, D.; Sener, H. T.; Stevens, I. R.

2018-01-01

The aim of this study is to accurately calculate the rotational period of CS Vir by using STEREO observations and investigate a possible period variation of the star with the help of all accessible data. The STEREO data that cover 5-yr time interval between 2007 and 2011 are analysed by means of the Lomb-Scargle and Phase Dispersion Minimization methods. In order to obtain a reliable rotation period and its error value, computational algorithms such as the Levenberg-Marquardt and Monte Carlo simulation algorithms are applied to the data sets. Thus, the rotation period of CS Vir is improved to be 9.29572(12) d by using the 5-yr of combined data set. Also, the light elements are calculated as HJD max = 2454715.975(11) + 9d . 29572(12) × E + 9d . 78(1.13) × 10 - 8 × E 2 by means of the extremum times derived from the STEREO light curves and archives. Moreover, with this study, a period variation is revealed for the first time, and it is found that the period has lengthened by 0.66(8) s y-1, equivalent to 66 s per century. Additionally, a time-scale for a possible spin-down is calculated around τSD 106 yr. The differential rotation and magnetic braking are thought to be responsible of the mentioned rotational deceleration. It is deduced that the spin-down time-scale of the star is nearly three orders of magnitude shorter than its main-sequence lifetime (τMS 109 yr). It is, in return, suggested that the process of increase in the period might be reversible.

First photometric study of ultrashort-period contact binary 1SWASP J140533.33+114639.1

NASA Astrophysics Data System (ADS)

Zhang, Bin; Qian, Sheng-Bang; Michel, Ri; Soonthornthum, Boonrucksar; Zhu, Li-Ying

2018-03-01

In this paper, CCD photometric light curves for the short-period eclipsing binary 1SWASP J140533.33+114639.1 (hereafter J1405) in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney (W-D) code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9 ± 0.5% and a mass ratio of q = 1.55 ± 0.02. In order to explain the asymmetric light curves of the system, a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the (O – C) method, the variation of orbital period is studied using all the available times of minimum light. The (O – C) diagram reveals that the period is increasing continuously at a rate of dP/dt = +2.09 × 10‑7, d yr‑1, which can be explained by mass transfer from the less massive component to the more massive one.

The response of middle atmospheric ozone to solar UV irradiance variations with a period of 27 days

NASA Technical Reports Server (NTRS)

Chen, LI; Brasseur, Guy; London, Julius

1994-01-01

A one-dimensional photochemical-dynamical-radiative time-dependent model was used to study the response of middle atmospheric temperature and ozone to solar UV irradiance variations with the period of 27 days. The model solar UV O(x), HO(x), NO(x), and CIO(x)families and modeled solar UV variations. The amplitude of the primary temperature response to the solar UV variation is plus 0.4 K at 85-90 km with a phase lag of about 6 days. A secondary maximum response of plus 0.3 K at 45-50 km appears with a phase lag of 1 day. There is a maximum positive ozone response to the 27-day solar UV oscillation of 2.5 percent at 80-90 km with a phase lag of about 10 days after the solar irradiance maximum. At 70 km the ozone response is about 1.2 percent and is out of phase with the solar variation. In the upper stratosphere (40-50 km) the relative ozone variation is small, about 0.2 percent to 0.3 percent, and there is a negative phase of about 4 days between the ozone and solar oscillations. These oscillations are in phase in the middle stratosphere (35-40 km) where there is again a maximum relative response of about 0.6 percent. The reasons for these ozone amplitude and phase variations are discussed.

Radioimmunoassay of Serum Concentrations of Melatonin in Sheep Exposed to Different Lighting Regimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

ROLLAG, M. D.; NISWENDER, G. D.

1976-02-01

A specific and sensitive double-antibody radioimmunoassay for melatonin (N-acetyl-5-methoxytryptamine) was developed. The least detectable concentration of melatonin standard was 10 pmolar (2.3 pg/tube) with 50 percent inhibition resulting when the concentration was 100 pmolar (23 pg/tube). Inhibition curves obtained with increasing quantities of melatonin or increasing quantities of chloroform extracts of ovine sera were parallel. Concentrations of melatonin could be accurately determined when 31 to 1000 pg were added to 1 ml ovine serum. Serum samples with melatonin concentrations of 1000 pg/ml, 500 pg/ml and 75 pg/ml had intra-assay coefficients of variation of 9.1 percent, 8.6 percent, and 17.4 percent,more » respectively. The respective inter-assay coefficients of variation were 22.7 percent, 18.1 percent, and 37.1 percent. Ewes exposed to a 12 h light:12 h dark lighting regimen demonstrated a circadian rhythm in serum concentrations of melatonin. Concentrations ranged from 10 to 30 pg/ml during periods of light to 100 to 300 pg/ml during periods of dark. During exposure to continuous light, the circadian rhythm was abolished and concentrations of melatonin were maintained at 10 to 50 pg/ml. When exposed to conditions of continuous dark the circadian rhythm persisted. A precipitous drop in serum concentrations of melatonin resulted when ewes experiencing peak melatonin concentrations were exposed to light. Concentrations returned to peak levels when the lights were turned off 3.5 h later. (auth)« less

A Model of the Temporal Variability of Optical Light from Extrasolar Terrestrial Planets

NASA Astrophysics Data System (ADS)

Ford, E. B.; Seager, S.; Turner, E. L.

2001-05-01

New observatories such as TPF (NASA) and Darwin (ESA) are being designed to detect light directly from terrestrial-mass planets. Such observations will provide new data to constrain theories of planet formation and may identify the possible presence of liquid water and even spectroscopic signatures suggestive of life. We model the light scattered by Earth-like planets focusing on temporal variability due to planetary rotation and weather. Since a majority of the scattered light comes from only a small fraction of the planet's surface, significant variations in brightness are possible. The variations can be as large as a factor of two for a cloud-free planet which has a range of albedos similar to those of the different surfaces found on Earth. If a significant fraction of the observed light is scattered by the planet's atmosphere, including clouds, then the amplitude of variations due to surface features will be diluted. Atmospheric variability (e.g. clouds) itself is extremely interesting because it provides evidence for weather. The planet's rotation period, fractional ice and cloud cover, gross distribution of land and water on the surface, large scale weather patterns, large regions of unusual reflectivity or color (such as major desserts or vegetation's "red edge") as well as the geometry of its spin, orbit, and illumination relative to the observer all have substantial effects on the planet's rotational light curve.

Variations of physicochemical properties in Kalpakkam coastal waters, east coast of India, during southwest to northeast monsoon transition period.

PubMed

Satpathy, Kamala Kanta; Mohanty, Ajit K; Sahu, Gouri; Sarkar, Santosh K; Natesan, Usha; Venkatesan, R; Prasad, M V R

2010-12-01

A significant variation in physicochemical properties of the Kalpakkam coastal waters, eastern part of India, was observed during the event of southwest to northeast monsoon transition. Increase in nitrate, total nitrogen, and silicate concentrations were noticed during post-transition period. Ammonia concentration was at peak during transition period as compared to pre- and post-transition periods. Hypo-saline condition (~23 psu) was observed during post-transition as the surface water salinity decreased by ~10 psu from the pre-transitional values. Turbidity, suspended particulate matter, phosphate and total phosphorous values decreased marginally, coinciding with northward to southward current reversal. A drastic decrease (eightfold) in chlorophyll-a concentration was observed in the coastal water during post-transition period.

Morphological study of the prostate gland in viscacha (Lagostomus maximus maximus) during periods of maximal and minimal reproductive activity.

PubMed

Chaves, Maximiliano; Aguilera-Merlo, Claudia; Cruceño, Albana; Fogal, Teresa; Mohamed, Fabian

2015-11-01

The viscacha (Lagostomus maximus maximus) is a rodent with photoperiod-dependent seasonal reproduction. The aim of this work was to study the morphological variations of the prostate during periods of maximal (summer, long photoperiod) and minimal (winter, short photoperiod) reproductive activity. Prostates of adult male viscachas were studied by light and electron microscopy, immunohistochemistry for androgen receptor, and morphometric analysis. The prostate consisted of two regions: peripheral and central. The peripheral zone exhibited large adenomeres with a small number of folds and lined with a pseudostratified epithelium. The central zone had small adenomeres with pseudostratified epithelium and the mucosa showed numerous folds. The morphology of both zones showed variations during periods of maximal and minimal reproductive activity. The prostate weight, prostate-somatic index, luminal diameter of adenomeres, epithelial height and major nuclear diameter decreased during the period of minimal reproductive activity. Principal cells showed variations in their shape, size and ultrastructural characteristics during the period of minimal reproductive activity in comparison with the active period. The androgen receptor expression in epithelial and fibromuscular stromal cells was different between the studied periods. Our results suggest a reduced secretory activity of viscacha prostate during the period of minimal reproductive activity. Thus, the morphological variations observed in both the central and peripheral zones of the viscacha prostate agree with the results previously obtained in the gonads of this rodent of photoperiod-dependent reproduction. Additionally, the variations observed in the androgen receptors suggest a direct effect of the circulating testosterone on the gland. © 2015 Wiley Periodicals, Inc.

Effects of light wavelength and coherence in structured light sensors

NASA Astrophysics Data System (ADS)

Harding, Kevin; Ramamurthy, Rajesh; Zhai, Zirong; Han, Jie; Yang, Dongmin

2016-05-01

Structured light methods are used by many commercial products on the market today. Many such systems using white light projectors while many line gages use standard red laser diodes. However, in recent years there has been much claimed about using blue light, polarized light and partially coherent systems to obtain better performance. Unlike interferometers, moving from red to blue light for a system using only geometric shape information does not gain an automatic advantage from the shorter wavelength. The sensitivity metric does not have a wavelength component to it. But there are other factors that can improve gage performance. The ability to measure some feature is also a function of other parameters such as signal to noise ratio, reflectivity variations, and depth-of-field over which a clear pattern can be seen. This paper will explore the theoretical and experimental data relating to what works and what can be expected from variations on the old methods.

Light equation in eclipsing binary CV Boo: third body candidate in elliptical orbit

NASA Astrophysics Data System (ADS)

Bogomazov, A. I.; Kozyreva, V. S.; Satovskii, B. L.; Krushevska, V. N.; Kuznyetsova, Y. G.; Ehgamberdiev, S. A.; Karimov, R. G.; Khalikova, A. V.; Ibrahimov, M. A.; Irsmambetova, T. R.; Tutukov, A. V.

2016-12-01

A short period eclipsing binary star CV Boo is tested for the possible existence of additional bodies in the system with a help of the light equation method. We use data on the moments of minima from the literature as well as from our observations during 2014 May-July. A variation of the CV Boo's orbital period is found with a period of {≈}75 d. This variation can be explained by the influence of a third star with a mass of {≈}0.4 M_{⊙} in an eccentric orbit with e≈0.9. A possibility that the orbital period changes on long time scales is discussed. The suggested tertiary companion is near the chaotic zone around the central binary, so CV Boo represents an interesting example to test its dynamical evolution. A list of 14 minima moments of the binary obtained from our observations is presented.

Effects of temperature, light and incubation period on production, germination and bioactivity of Trichoderma atroviride.

PubMed

Daryaei, A; Jones, E E; Ghazalibiglar, H; Glare, T R; Falloon, R E

2016-04-01

The goal was to determine the effect of temperature, light and incubation period on production, germination and bioactivity of Trichoderma atroviride LU132 against Rhizoctonia solani. The incubation temperatures of 20, 25 or 30°C were assessed on the production of T. atroviride conidia under constant light over a 25 and 50 days periods. The resulting conidia were also studied for germination and bioactivity. Conidium production was maximum at 25°C after 20 days. The second peak of conidium production occurred at 45-50 days. Incubation at 25°C after 15 days showed optimum production of T. atroviride LU132. Conidia produced at 30°C gave the greatest germination and bioactivity in comparison with incubation at 20 or 25°C. This study indicates that the temperature at which conidia of T. atroviride are produced affects germination and bioactivity. Formulations based on production of the high conidia yield may not result in optimal bioactivity and there is a trade-off between quantity and quality of T. atroviride LU132 conidia. Conidium production was shown to be a continuous process, and increased under a dark/light regime. This is the first report of bimodal conidium production in a Trichoderma biological control agent (BCA), which is likely to be on 20 days cycle, and is dependent on colony age rather than abiotic factors. Conidia produced after 15 days are likely to be the most suitable for use in commercial production of this strain as a BCA. Most studies on Trichoderma-based BCA have only shown the effect of culture conditions on the high conidia yield regardless of conidium quality. This study is the first report on conidium quality affected by principal culture conditions for Trichoderma biological control formulations. © 2016 The Society for Applied Microbiology.

A non-invasive geometric morphometrics method for exploring variation in dorsal head shape in urodeles: sexual dimorphism and geographic variation in Salamandra salamandra.

PubMed

Alarcón-Ríos, Lucía; Velo-Antón, Guillermo; Kaliontzopoulou, Antigoni

2017-04-01

The study of morphological variation among and within taxa can shed light on the evolution of phenotypic diversification. In the case of urodeles, the dorso-ventral view of the head captures most of the ontogenetic and evolutionary variation of the entire head, which is a structure with a high potential for being a target of selection due to its relevance in ecological and social functions. Here, we describe a non-invasive procedure of geometric morphometrics for exploring morphological variation in the external dorso-ventral view of urodeles' head. To explore the accuracy of the method and its potential for describing morphological patterns we applied it to two populations of Salamandra salamandra gallaica from NW Iberia. Using landmark-based geometric morphometrics, we detected differences in head shape between populations and sexes, and an allometric relationship between shape and size. We also determined that not all differences in head shape are due to size variation, suggesting intrinsic shape differences across sexes and populations. These morphological patterns had not been previously explored in S. salamandra, despite the high levels of intraspecific diversity within this species. The methodological procedure presented here allows to detect shape variation at a very fine scale, and solves the drawbacks of using cranial samples, thus increasing the possibilities of using collection specimens and alive animals for exploring dorsal head shape variation and its evolutionary and ecological implications in urodeles. J. Morphol. 278:475-485, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Retinex based low-light image enhancement using guided filtering and variational framework

NASA Astrophysics Data System (ADS)

Zhang, Shi; Tang, Gui-jin; Liu, Xiao-hua; Luo, Su-huai; Wang, Da-dong

2018-03-01

A new image enhancement algorithm based on Retinex theory is proposed to solve the problem of bad visual effect of an image in low-light conditions. First, an image is converted from the RGB color space to the HSV color space to get the V channel. Next, the illuminations are respectively estimated by the guided filtering and the variational framework on the V channel and combined into a new illumination by average gradient. The new reflectance is calculated using V channel and the new illumination. Then a new V channel obtained by multiplying the new illumination and reflectance is processed with contrast limited adaptive histogram equalization (CLAHE). Finally, the new image in HSV space is converted back to RGB space to obtain the enhanced image. Experimental results show that the proposed method has better subjective quality and objective quality than existing methods.

Multiple-wavelength Variability and Quasi-periodic Oscillation of PMN J0948+0022

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jin; Zhang, Hai-Ming; Zhu, Yong-Kai

We present a comprehensive analysis of multiple-wavelength observational data of the first GeV-selected narrow-line Seyfert 1 galaxy PMN J0948+0022. We derive its light curves in the γ -ray and X-ray bands from the data observed with Fermi /LAT and Swift /XRT, and generate the optical and radio light curves by collecting the data from the literature. These light curves show significant flux variations. With the LAT data we show that this source is analogous to typical flat spectrum radio quasars in the L {sub γ} –Γ {sub γ} plane, where L {sub γ} and Γ {sub γ} are the luminositymore » and spectral index in the LAT energy band. The γ -ray flux is correlated with the V-band flux with a lag of ∼44 days, and a moderate quasi-periodic oscillation (QPO) with a periodicity of ∼490 days observed in the LAT light curve. A similar QPO signature is also found in the V-band light curve. The γ -ray flux is not correlated with the radio flux in 15 GHz, and no similar QPO signature is found at a confidence level of 95%. Possible mechanisms of the QPO are discussed. We propose that gravitational-wave observations in the future may clarify the current plausible models for the QPO.« less

Ultraviolet light curves of beta Lyrae: Comparison of OAO A-2, IUE, and Voyager Observations

NASA Technical Reports Server (NTRS)

Kondo, Yoji; Mccluskey, George E.; Silvis, Jeffery M. S.; Polidan, Ronald S.; Mccluskey, Carolina P. S.; Eaton, Joel A.

1994-01-01

The six-band ultraviolet light curves of beta Lyrae obtained with the Orbiting Astronomical Observatory (OAO) A-2 in 1970 exhibited a very unusual behavior. The secondary minimum deepened at shorter wavelength, indicating that one was not observing light variations caused primarily by the eclipses of two stars having a roughly Planckian energy distribution. It was then suggested that the light variations were caused by a viewing angle effect of an optically thick, ellipsoidal circumbinary gas cloud. Since 1978 beta Lyrae has been observed with the International Ultraviolet Explorer (IUE) satellite. We have constructed ultraviolet light curves from the IUE archival data for comparison with the OAO A-2 results. We find that they are in substantial agreement with each other. The Voyager ultraviolet spectrometer was also used to observe this binary during a period covered by IUE observations. The Voyager results agree with those of the two other satellite observatories at wavelengths longer than about 1350 A. However, in the wavelength region shorter than the Lyman-alpha line at 1216 A, the light curves at 1085 and 965 A show virtually no light variation except an apparent flaring near phase 0.7, which is also in evidence at longer wavelengths. We suggest that the optically thick circumbinary gas cloud, which envelops the two stars completely, assumes a roughly spherical shape when observed at these shorter wavelengths.

Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin

NASA Astrophysics Data System (ADS)

Maciejewski, G.; Dimitrov, D.; Seeliger, M.; Raetz, St.; Bukowiecki, Ł.; Kitze, M.; Errmann, R.; Nowak, G.; Niedzielski, A.; Popov, V.; Marka, C.; Goździewski, K.; Neuhäuser, R.; Ohlert, J.; Hinse, T. C.; Lee, J. W.; Lee, C.-U.; Yoon, J.-N.; Berndt, A.; Gilbert, H.; Ginski, Ch.; Hohle, M. M.; Mugrauer, M.; Röll, T.; Schmidt, T. O. B.; Tetzlaff, N.; Mancini, L.; Southworth, J.; Dall'Ora, M.; Ciceri, S.; Zambelli, R.; Corfini, G.; Takahashi, H.; Tachihara, K.; Benkő, J. M.; Sárneczky, K.; Szabo, Gy. M.; Varga, T. N.; Vaňko, M.; Joshi, Y. C.; Chen, W. P.

2013-03-01

Aims: The transiting planet WASP-12 b was identified as a potential target for transit-timing studies because a departure from a linear ephemeris has been reported in the literature. Such deviations could be caused by an additional planet in the system. We attempt to confirm the claimed variations in transit timing and interpret their origin. Methods: We organised a multi-site campaign to observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre telescopes. Results: We obtained 61 transit light curves, many of them with sub-millimagnitude precision. The simultaneous analysis of the best-quality datasets allowed us to obtain refined system parameters, which agree with values reported in previous studies. The residuals versus a linear ephemeris reveal a possible periodic signal that may be approximated by a sinusoid with an amplitude of 0.00068 ± 0.00013 d and period of 500 ± 20 orbital periods of WASP-12 b. The joint analysis of timing data and published radial velocity measurements results in a two-planet model that explains observations better than do single-planet scenarios. We hypothesise that WASP-12 b might not be the only planet in the system, and there might be the additional 0.1 MJup body on a 3.6-d eccentric orbit. A dynamical analysis indicates that the proposed two-planet system is stable on long timescales. Partly based on (1) data collected with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, (2) observations made at the Centro Astronómico Hispano Alemán (CAHA), operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), (3) data collected with telescopes at the Rozhen National Astronomical Observatory, and (4) observations obtained with telescopes of the University Observatory Jena, which is operated

Performance of a two-leaf light use efficiency model for mapping gross primary productivity against remotely sensed sun-induced chlorophyll fluorescence data.

PubMed

Zan, Mei; Zhou, Yanlian; Ju, Weimin; Zhang, Yongguang; Zhang, Leiming; Liu, Yibo

2018-02-01

Estimating terrestrial gross primary production is an important task when studying the carbon cycle. In this study, the ability of a two-leaf light use efficiency model to simulate regional gross primary production in China was validated using satellite Global Ozone Monitoring Instrument - 2 sun-induced chlorophyll fluorescence data. The two-leaf light use efficiency model was used to estimate daily gross primary production in China's terrestrial ecosystems with 500-m resolution for the period from 2007 to 2014. Gross primary production simulated with the two-leaf light use efficiency model was resampled to a spatial resolution of 0.5° and then compared with sun-induced chlorophyll fluorescence. During the study period, sun-induced chlorophyll fluorescence and gross primary production simulated by the two-leaf light use efficiency model exhibited similar spatial and temporal patterns in China. The correlation coefficient between sun-induced chlorophyll fluorescence and monthly gross primary production simulated by the two-leaf light use efficiency model was significant (p<0.05, n=96) in 88.9% of vegetated areas in China (average value 0.78) and varied among vegetation types. The interannual variations in monthly sun-induced chlorophyll fluorescence and gross primary production simulated by the two-leaf light use efficiency model were similar in spring and autumn in most vegetated regions, but dissimilar in winter and summer. The spatial variability of sun-induced chlorophyll fluorescence and gross primary production simulated by the two-leaf light use efficiency model was similar in spring, summer, and autumn. The proportion of spatial variations of sun-induced chlorophyll fluorescence and annual gross primary production simulated by the two-leaf light use efficiency model explained by ranged from 0.76 (2011) to 0.80 (2013) during the study period. Overall, the two-leaf light use efficiency model was capable of capturing spatial and temporal variations in gross

Transit Timing Variation analysis with Kepler light curves of KOI 227 and Kepler 93b

NASA Astrophysics Data System (ADS)

Dulz, Shannon; Reed, Mike

2017-01-01

By searching for transit signals in approximately 150,000 stars, NASA’s Kepler Space telescope found thousands of exoplanets over its primary mission from 2009 to 2013 (Tenenbaum et al. 2014, ApJS, 211, 6). Yet, a detailed follow-up examination of Kepler light curves may contribute more evidence on system dynamics and planetary atmospheres of these objects. Kepler’s continuous observing of these systems over the mission duration produced light curves of sufficient duration to allow for the search for transit timing variations. Transit timing variations over the course of many orbits may indicate a precessing orbit or the existence of a non-transiting third body such as another exoplanet. Flux contributions of the planet just prior to secondary eclipse may provide a measurement of bond albedo from the day-side of the transiting planet. Any asymmetries of the transit shape may indicate thermal asymmetries which can measure upper atmosphere motion of the planet. These two factors can constrain atmospheric models of close orbiting exoplanets. We first establish our procedure with the well-documented TTV system, KOI 227 (Nesvorny et al. 2014, ApJ, 790, 31). Using the test case of KOI 227, we analyze Kepler-93b for TTVs and day-side flux contributions. Kepler-93b is likely a rocky planet with R = 1.50 ± 0.03 Earth Radii and M = 2.59 ± 2.0 Earth Masses (Marcy et al. 2014, ApJS, 210, 20). This research is funded by a NASA EPSCoR grant.

Dopamine and noradrenaline efflux in the prefrontal cortex in the light and dark period: effects of novelty and handling and comparison to the nucleus accumbens.

PubMed

Feenstra, M G; Botterblom, M H; Mastenbroek, S

2000-01-01

We used on-line microdialysis measurements of dopamine and noradrenaline extracellular concentrations in the medial prefrontal cortex of awake, freely moving rats during the dark and the light period of the day to study whether (i) basal efflux would be higher in the active, dark period than in the inactive, light period; (ii) the activation induced by environmental stimuli would be dependent on these conditions. When determined one day after cannula placement, noradrenaline and dopamine levels were higher during the dark. Maximal relative increases induced by novelty and handling were 150% and 175-200%, respectively, and were very similar in the light and the dark, but the net increases were higher in the dark. Separate groups were tested one week after cannula placement to ensure recovery of possibly disturbed circadian rhythms. While basal levels in the dark were now approximately twice those in the light, the maximal relative and net increases after both novelty and handling were very similar. Basal levels of dopamine in the nucleus accumbens (one day after cannula placement) were not different in the light or dark, but were increased by novelty and handling to about 130% only in the light period, not in the dark. Thus, in the prefrontal cortex, dopamine strongly resembles noradrenaline, in that basal efflux was state dependent, whereas activation by stimuli was not. In the nucleus accumbens, basal dopamine efflux was not state dependent, but activation by stimuli was. These results suggest that there are differential effects of circadian phase on basal activity and responsiveness of the mesolimbic vs the mesocortical dopamine system.

Rapid-cadence optical monitoring for short-period variability of ɛ Aurigae

NASA Astrophysics Data System (ADS)

Billings, Gary

2013-07-01

ɛ Aurigae was observed with CCD cameras and 35 mm SLR camera lenses, at rapid cadence (>1/minute), for long runs (up to 11 hours), on multiple occasions during 2009 - 2011, to monitor for variability of the system at scales of minutes to hours. The lens and camera were changed during the period to improve results, finalizing on a 135 mm focal length Canon f/2 lens (at f/2.8), an ND8 neutral density filter, a Johnson V filter, and an SBIG ST-8XME camera (Kodak KAF-1603ME microlensed chip). Differential photometry was attempted, but because of the large separation between the variable and comparison star (η Aur), noise caused by transient extinction variations was not consistently eliminated. The lowest-noise time series for searching for short-period variability proved to be the extinction-corrected instrumental magnitude of ɛ Aur obtained on "photometric nights", with η Aur used to determine and monitor the extinction coefficient for the night. No flares or short-period variations of ɛ Aur were detected by visual inspection of the light curves from observing runs with noise levels as low as 0.008 magnitudes rms.

Enhancement and inhibition of light tunneling mediated by resonant mode conversion.

PubMed

Kartashov, Yaroslav V; Vysloukh, Victor A; Torner, Lluis

2014-02-15

We show that the rate at which light tunnels between neighboring multimode waveguides can be drastically increased or reduced by the presence of small longitudinal periodic modulations of the waveguide properties that stimulate resonant conversion between the eigenmodes of each waveguide. Such a conversion, available only in multimode guiding structures, leads to periodic power transfer into higher-order modes, whose tails may considerably overlap with neighboring waveguides. As a result, the effective coupling constant for neighboring waveguides may change by several orders of magnitude upon small variations in the longitudinal modulation parameters.

Archeointensities in Greece during the Neolithic period: New insights into material selection and secular variation curve

NASA Astrophysics Data System (ADS)

Fanjat, G.; Aidona, E.; Kondopoulou, D.; Camps, P.; Rathossi, C.; Poidras, T.

2013-02-01

Numerous archeomagnetic studies have provided high quality data for both the direction and the intensity of the geomagnetic field, essentially in Europe for the last 10 millennia. In particular, Greece supplies a lot of archeological materials due to its impressive cultural heritage and volcanic activity, so that numerous data have been obtained from burnt clays or historical lava flows. The most recent Greek secular variation curves are available for the last 8 millennia for the intensity and the last 6 millennia for the direction. Nevertheless, the coverage still presents several gaps for periods older than 2500 BC. In an effort to complete the Greek curve and extend it to older times, we present the archeointensity results from three Neolithic settlements in Northern Greece. The samples are of two different natures: burnt structures from Avgi (5250 ± 150 BC) and Vasili (4800 ± 200 BC), as well as ceramics from Dikili Tash (4830 ± 80 BC) and Vasili (4750 ± 250 BC). The samples have been subjected to standard rock magnetic analyses in order to estimate the thermal stability and the domain state of the magnetic carriers before archeointensity measurements. Surprisingly, very few ceramic samples provided reliable archeointensities whereas samples from burnt structures presented a very good success rate. Complementary studies showed that a detailed examination of the matrix color, following archeological information and classification standards can be a decisive test for pre-selection of sherds. In spite of these unsuccessful measurements from ceramics, we obtained an intensity value of 73.5 ± 1.1 μT for Dikili Tash, a higher value than the other data obtained in the same area, during the same period. However we do not have evidences for a technical artefact during the experiment. The burnt structures yielded two reliable archeointensities of 36.1 ± 1.8 μT and 46.6 ± 3.4 μT for Avgi and Vasili, respectively. Finally, we achieved a new archeomagnetic dating

Searching Cyclical Period Variations in Cataclysmic Variable Stars

NASA Astrophysics Data System (ADS)

Borges, B. W.; Baptista, R.

2006-08-01

Cataclymic variables (CVs) are semi-detached binary systems in which a main sequence late-type star (the secondary) fills its Roche lobe and transfers matter to a white dwarf (the primary) through the inner Lagragian point L[1]. Evolutive models of CVs predicts that the orbital periods P[orb] of these systems would decrease on time scales of 10^8-10^9 years due to angular momentum losses either by magnetic braking via the secondary star's wind (P [orb] > 3 hr) or by emission of gravitational radiation (P[orb] < 3 hr). These models try to explain the observed gap of systems with P[orb] in the range of ~ 2 to 3 hr as the consequence of a sharp reduction of magnetic field open lines when the secondary star become fully convective (at P[orb] ~ 3 hr). However, up to now no well-studied CVs shows evidence of period decrease. Instead, most well-observed eclipsing CVs show cyclical period changes probably associated to solar-type (quasi-periodic and/or multiperiodic) magnetic activity cycles in the secondary star. The fast spinning secondaries of CVs, covering a range of masses and rotation periods, are an important laboratory to understanding magnetic activities cycles in late type stars. In the present work, we report some results of the search of cyclical period in four Cvs: V4140 Sgr, V2051 Oph, UU Aqr and IP Peg. Both V4140 Sgr and V2051 Oph show modulation periods of 22 yr and 7 yr respectively. A discussion of the distinct magnetic activity properties of short and long orbital period (P[orb] < 3 hr and P[orb] > 3 hr, respectively) systems in the framework of the CV evolution scenarios is presented.

Role of monochromatic light on daily variation of clock gene expression in the pineal gland of chick.

PubMed

Jiang, Nan; Wang, Zixu; Cao, Jing; Dong, Yulan; Chen, Yaoxing

2016-11-01

The avian pineal gland is a master clock that can receive external photic cues and translate them into output rhythms. To clarify whether a shift in light wavelength can influence the circadian expression in chick pineal gland, a total of 240 Arbor Acre male broilers were exposed to white light (WL), red light (RL), green light (GL) or blue light (BL). After 2weeks light illumination, circadian expressions of seven core clock genes in pineal gland and the level of melatonin in plasma were examined. The results showed after illumination with monochromatic light, 24h profiles of all clock gene mRNAs retained circadian oscillation, except that RL tended to disrupt the rhythm of cCry2. Compared to WL, BL advanced the acrophases of the negative elements (cCry1, cCry2, cPer2 and cPer3) by 0.1-1.5h and delayed those of positive elements (cClock, cBmal1 and cBmal2) by 0.2-0.8h. And, RL advanced all clock genes except cClock and cPer2 by 0.3-2.1h, while GL delayed all clock genes by 0.5-1.5h except cBmal2. Meanwhile, GL increased the amplitude and mesor of positive and reduced both parameters of negative clock genes, but RL showed the opposite pattern. Although the acrophase of plasma melatonin was advanced by both GL and RL, the melatonin level was significantly increased in GL and decreased in RL. This tendency was consistent with the variations in the positive clock gene mRNA levels under monochromatic light and contrasted with those of negative clock genes. Therefore, we speculate that GL may enhance positive clock genes expression, leading to melatonin synthesis, whereas RL may enhance negative genes expression, suppressing melatonin synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

Response to various periods of mechanical stimuli in Physarum plasmodium

NASA Astrophysics Data System (ADS)

Umedachi, Takuya; Ito, Kentaro; Kobayashi, Ryo; Ishiguro, Akio; Nakagaki, Toshiyuki

2017-06-01

Response to mechanical stimuli is a fundamental and critical ability for living cells to survive in hazardous conditions or to form adaptive and functional structures against force(s) from the environment. Although this ability has been extensively studied by molecular biology strategies, it is also important to investigate the ability from the viewpoint of biological rhythm phenomena so as to reveal the mechanisms that underlie these phenomena. Here, we use the plasmodium of the true slime mold Physarum polycephalum as the experimental system for investigating this ability. The plasmodium was repetitively stretched for various periods during which its locomotion speed was observed. Since the plasmodium has inherent oscillation cycles of protoplasmic streaming and thickness variation, how the plasmodium responds to various periods of external stretching stimuli can shed light on the other biological rhythm phenomena. The experimental results show that the plasmodium exhibits response to periodic mechanical stimulation and changes its locomotion speed depending on the period of the stretching stimuli.

Attaining the canopy in dry and moist tropical forests: strong differences in tree growth trajectories reflect variation in growing conditions.

PubMed

Brienen, Roel J W; Zuidema, Pieter A; Martínez-Ramos, Miguel

2010-06-01

Availability of light and water differs between tropical moist and dry forests, with typically higher understorey light levels and lower water availability in the latter. Therefore, growth trajectories of juvenile trees--those that have not attained the canopy--are likely governed by temporal fluctuations in light availability in moist forests (suppressions and releases), and by spatial heterogeneity in water availability in dry forests. In this study, we compared juvenile growth trajectories of Cedrela odorata in a dry (Mexico) and a moist forest (Bolivia) using tree rings. We tested the following specific hypotheses: (1) moist forest juveniles show more and longer suppressions, and more and stronger releases; (2) moist forest juveniles exhibit wider variation in canopy accession pattern, i.e. the typical growth trajectory to the canopy; (3) growth variation among dry forest juveniles persists over longer time due to spatial heterogeneity in water availability. As expected, the proportion of suppressed juveniles was higher in moist than in dry forest (72 vs. 17%). Moist forest suppressions also lasted longer (9 vs. 5 years). The proportion of juveniles that experienced releases in moist forest (76%) was higher than in dry forest (41%), and releases in moist forests were much stronger. Trees in the moist forest also had a wider variation in canopy accession patterns compared to the dry forest. Our results also showed that growth variation among juvenile trees persisted over substantially longer periods of time in dry forest (>64 years) compared to moist forest (12 years), most probably because of larger persistent spatial variation in water availability. Our results suggest that periodic increases in light availability are more important for attaining the canopy in moist forests, and that spatial heterogeneity in water availability governs long-term tree growth in dry forests.

Asynchronous polar V1500 Cyg: orbital, spin and beat periods

NASA Astrophysics Data System (ADS)

Pavlenko, E. P.; Mason, P. A.; Sosnovskij, A. A.; Shugarov, S. Yu; Babina, Ju V.; Antonyuk, K. A.; Andreev, M. V.; Pit, N. V.; Antonyuk, O. I.; Baklanov, A. V.

2018-06-01

The bright Nova Cygni 1975 is a rare nova on a magnetic white dwarf (WD). Later it was found to be an asynchronous polar, now called V1500 Cyg. Our multisite photometric campaign occurring 40 years post eruption covered 26-nights (2015-2017). The reflection effect from the heated donor has decreased, but still dominates the optical radiation with an amplitude ˜1m.5. The 0m.3 residual reveals cyclotron emission and ellipsoidal variations. Mean brightness modulation from night-to-night is used to measure the 9.6-d spin-orbit beat period that is due to changing accretion geometry including magnetic pole-switching of the flow. By subtracting the orbital and beat frequencies, spin-phase dependent light curves are obtained. The amplitude and profile of the WD spin light curves track the cyclotron emitting accretion regions on the WD and they vary systematically with beat phase. A weak intermittent signal at 0.137613-d is likely the spin period, which is 1.73(1) min shorter than the orbital period. The O-C diagram of light curve maxima displays phase jumps every one-half beat period, a characteristic of asynchronous polars. The first jump we interpret as pole switching between regions separated by 180°. Then the spot drifts during ˜ 0.1 beat phase before undergoing a second phase jump between spots separated by less than 180°. We trace the cooling of the still hot WD as revealed by the irradiated companion. The post nova evolution and spin-orbit asynchronism of V1500 Cyg continues to be a powerful laboratory for accretion flows onto magnetic white dwarfs.

Mutations in EID1 and LNK2 caused light-conditional clock deceleration during tomato domestication.

PubMed

Müller, Niels A; Zhang, Lei; Koornneef, Maarten; Jiménez-Gómez, José M

2018-05-22

Circadian period and phase of cultivated tomato ( Solanum lycopersicum ) were changed during domestication, likely adapting the species to its new agricultural environments. Whereas the delayed circadian phase is mainly caused by allelic variation of EID1 , the genetic basis of the long circadian period has remained elusive. Here we show that a partial deletion of the clock gene LNK2 is responsible for the period lengthening in cultivated tomatoes. We use resequencing data to phylogenetically classify hundreds of tomato accessions and investigate the evolution of the eid1 and lnk2 mutations along successive domestication steps. We reveal signatures of selection across the genomic region of LNK2 and different patterns of fixation of the mutant alleles. Strikingly, LNK2 and EID1 are both involved in light input to the circadian clock, indicating that domestication specifically targeted this input pathway. In line with this, we show that the clock deceleration in the cultivated tomato is light-dependent and requires the phytochrome B1 photoreceptor. Such conditional variation in circadian rhythms may be key for latitudinal adaptation in a variety of species, including crop plants and livestock.

Variation in crown light utilization characteristics among tropical canopy trees.

PubMed

Kitajima, Kaoru; Mulkey, Stephen S; Wright, S Joseph

2005-02-01

Light extinction through crowns of canopy trees determines light availability at lower levels within forests. The goal of this paper is the exploration of foliage distribution and light extinction in crowns of five canopy tree species in relation to their shoot architecture, leaf traits (mean leaf angle, life span, photosynthetic characteristics) and successional status (from pioneers to persistent). Light extinction was examined at three hierarchical levels of foliage organization, the whole crown, the outermost canopy and the individual shoots, in a tropical moist forest with direct canopy access with a tower crane. Photon flux density and cumulative leaf area index (LAI) were measured at intervals of 0.25-1 m along multiple vertical transects through three to five mature tree crowns of each species to estimate light extinction coefficients (K). Cecropia longipes, a pioneer species with the shortest leaf life span, had crown LAI <0.5. Among the remaining four species, crown LAI ranged from 2 to 8, and species with orthotropic terminal shoots exhibited lower light extinction coefficients (0.35) than those with plagiotropic shoots (0.53-0.80). Within each type, later successional species exhibited greater maximum LAI and total light extinction. A dense layer of leaves at the outermost crown of a late successional species resulted in an average light extinction of 61% within 0.5 m from the surface. In late successional species, leaf position within individual shoots does not predict the light availability at the individual leaf surface, which may explain their slow decline of photosynthetic capacity with leaf age and weak differentiation of sun and shade leaves. Later-successional tree crowns, especially those with orthotropic branches, exhibit lower light extinction coefficients, but greater total LAI and total light extinction, which contribute to their efficient use of light and competitive dominance.

Pulse periods and the long-term variations of the X-ray pulsars VELA X-1 and Centaurus X-3

NASA Astrophysics Data System (ADS)

Tsunemi, Hiroshi

The paper reports recent determinations of the pulse period for two X-ray pulsars, Vela X-1 and Cen X-3, made in 1987 with the All Sky Monitor (ASM) on board the Ginga satellite. The heliocentric pulse periods are 283.09 + or - 0.01 s and 4.8229 + or - 0.0001 s, respectively. These are the longest and shortest values in their respective observational histories. The random walk model for the Vela X-1 pulsar can explain this result as well as those obtained previously. It is also noted that the pulse-period change for the Cen X-3 system shows a 9-yr periodicity. This is probably due to the activity of the companion star rather than to Doppler-shift variations due to a third body or the precession of the neutron star.

Numerical Solution of Light Scattered from and Transmitted through a Rough Dielectric Surface with Applications to Periodic Roughness and Isolated Structures

NASA Technical Reports Server (NTRS)

Sun, Wenbo; Videnn, Gorden; Lin, Bing; Hu, Yongxiang

2007-01-01

Light scattering and transmission by rough surfaces are of considerable interest in a variety of applications including remote sensing and characterization of surfaces. In this work, the finite-difference time domain technique is applied to calculate the scattered and transmitted electromagnetic fields of an infinite periodic rough surface. The elements of Mueller matrix for scattered light are calculated by an integral of the near fields over a significant number of periods of the surface. The normalized Mueller matrix elements of the scattered light and the spatial distribution of the transmitted flux for a monolayer of micron-sized dielectric spheres on a silicon substrate are presented. The numerical results show that the nonzero Mueller matrix elements of the system of the monolayer of dielectric spheres on a silicon substrate have specific maxima at some scattering angles. These maxima may be used in characterization of the feature of the system. For light transmitted through the monolayer of spheres, our results show that the transmitted energy focuses around the ray passing through centers of the spheres. At other locations, the transmitted flux is very small. The technique also may be used to calculate the perturbance of the electromagnetic field due to the presence of an isolated structure on the substrate.

Periodic variations of atmospheric electric field on fair weather conditions at YBJ, Tibet

NASA Astrophysics Data System (ADS)

Xu, Bin; Zou, Dan; Chen, Ben Yuan; Zhang, Jin Ye; Xu, Guo Wang

2013-05-01

Observations of atmospheric electric field on fair weather conditions from the plateau station, YBJ, Tibet (90°31‧50″ E, 30°06‧38″ N), over the period from 2006 to 2011, are presented in this work. Its periodic modulations are analyzed in frequency-domain by Lomb-Scargle Periodogram method and in time-domain by folding method. The results show that the fair weather atmospheric electric field intensity is modulated weakly by annual cycle, solar diurnal cycle and its several harmonic components. The modulating amplitude of annual cycle is bigger than that of solar diurnal cycle. The annual minimum/maximum nearly coincides with spring/autumn equinox. The detailed spectrum analysis show that the secondary peaks (i.e. sidereal diurnal cycle and semi-sidereal diurnal cycle) nearly disappear along with their primary peaks when the primary signals are subtracted from electric field data sequence. The average daily variation curve exhibits dual-fluctuations, and has obviously seasonal dependence. The mean value is bigger in summer and autumn, but smaller in spring and winter. The daytime fluctuation is affected by the sunrise and sunset effect, the occurring time of which have a little shift with seasons. However, the nightly one has a great dependence on season conditions.

Electrically tunable two-dimensional holographic polymer-dispersed liquid crystal grating with variable period

NASA Astrophysics Data System (ADS)

Wang, Kangni; Zheng, Jihong; Liu, Yourong; Gao, Hui; Zhuang, Songlin

2017-06-01

An electrically tunable two-dimensional (2D) holographic polymer-dispersed liquid crystal (H-PDLC) grating with variable period was fabricated by inserting a cylindrical lens in a conventional holographic interference beam. The interference between the plane wave and cylindrical wave resulting in varying intersection angles on the sample, combined with dual exposure along directions perpendicular to each other, generates a 2D H-PDLC grating with varied period. We have identified periods varying from 3.109 to 5.158 μm across a 16 mm width, with supporting theoretical equations for the period. The period exhibits a symmetrical square lattice in a diagonal direction, with an asymmetrical rectangular lattice in off-diagonal locations. With the first exposure at 2 s and the second exposure at 60 s, the phase separation between the prepolymer and liquid crystal was most evident. The diffraction properties and optic-electric characteristics were also studied. The diffraction efficiency of first-order light was observed to be 13.5% without external voltage, and the transmission efficiency of non-diffracted light was 78% with an applied voltage of 100 V. The proposed method provides the capability of generating period variation to the conventional holographic interference path, with potential application in diffractive optics such as tunable multi-wavelength organic lasing from a dye-doped 2D H-PDLC grating.

Online tracking of outdoor lighting variations for augmented reality with moving cameras.

PubMed

Liu, Yanli; Granier, Xavier

2012-04-01

In augmented reality, one of key tasks to achieve a convincing visual appearance consistency between virtual objects and video scenes is to have a coherent illumination along the whole sequence. As outdoor illumination is largely dependent on the weather, the lighting condition may change from frame to frame. In this paper, we propose a full image-based approach for online tracking of outdoor illumination variations from videos captured with moving cameras. Our key idea is to estimate the relative intensities of sunlight and skylight via a sparse set of planar feature-points extracted from each frame. To address the inevitable feature misalignments, a set of constraints are introduced to select the most reliable ones. Exploiting the spatial and temporal coherence of illumination, the relative intensities of sunlight and skylight are finally estimated by using an optimization process. We validate our technique on a set of real-life videos and show that the results with our estimations are visually coherent along the video sequences.

A MODEL FOR (QUASI-)PERIODIC MULTIWAVELENGTH PHOTOMETRIC VARIABILITY IN YOUNG STELLAR OBJECTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kesseli, Aurora Y.; Petkova, Maya A.; Wood, Kenneth

We present radiation transfer models of rotating young stellar objects (YSOs) with hot spots in their atmospheres, inner disk warps, and other three-dimensional effects in the nearby circumstellar environment. Our models are based on the geometry expected from magneto-accretion theory, where material moving inward in the disk flows along magnetic field lines to the star and creates stellar hot spots upon impact. Due to rotation of the star and magnetosphere, the disk is variably illuminated. We compare our model light curves to data from the Spitzer YSOVAR project to determine if these processes can explain the variability observed at opticalmore » and mid-infrared wavelengths in young stars. We focus on those variables exhibiting “dipper” behavior that may be periodic, quasi-periodic, or aperiodic. We find that the stellar hot-spot size and temperature affects the optical and near-infrared light curves, while the shape and vertical extent of the inner disk warp affects the mid-IR light curve variations. Clumpy disk distributions with non-uniform fractal density structure produce more stochastic light curves. We conclude that magneto-accretion theory is consistent with certain aspects of the multiwavelength photometric variability exhibited by low-mass YSOs. More detailed modeling of individual sources can be used to better determine the stellar hot-spot and inner disk geometries of particular sources.« less

Transient IP Structures Associated with Short-Period Variations in the Solar Energetic Particle and Galactic Cosmic Ray Flux

NASA Astrophysics Data System (ADS)

Mulligan, T.; Blake, J.; Spence, H. E.; Jordan, A. P.; Quenby, J. J.; Shaul, D.

2006-12-01

Short-period variations in the integral SEP ( > 10 MeV) and GCR fluence ( > 100 MeV), often observed in neutron monitor data have also been seen by the High Sensitivity Telescope (HIST) aboard the Polar Spacecraft. Although HIST was designed to measure radiation-belt electrons, it makes clean measurements of the integral SEP and GCR fluence when Polar is outside the radiation belts. These measurements show variability on a variety of timescales including 0.1~mHz - 1~mHz. We examine these variations from Polar and compare them with IMF and plasma solar wind conditions at L1 using ACE data. We find coherent short-term variability occurs when Earth is in close proximity to the HCS and when Earth is either inside an ICME or when an ICME has just transited the Earth. Also, when a flux rope ICME signature is present, the rope axis is nearly parallel to the radial direction and the HCS. The launch of STEREO will enable detailed 3-D analyses of such solar wind disturbances along spatial scales on the same order of typical SEP and GCR proton gyroradii, which are needed to elucidate the mechanism behind this short-period variability.

CSI 2264: Characterizing Young Stars in NGC 2264 With Short-Duration Periodic Flux Dips in Their Light Curves

NASA Astrophysics Data System (ADS)

Stauffer, John; Cody, Ann Marie; McGinnis, Pauline; Rebull, Luisa; Hillenbrand, Lynne A.; Turner, Neal J.; Carpenter, John; Plavchan, Peter; Carey, Sean; Terebey, Susan; Morales-Calderón, María; Alencar, Silvia H. P.; Bouvier, Jerome; Venuti, Laura; Hartmann, Lee; Calvet, Nuria; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob; Barrado, David; Vrba, Frederick J.; Covey, Kevin; Padgett, Debbie; Herbst, William; Gillen, Edward; Lyra, Wladimir; Medeiros Guimaraes, Marcelo; Bouy, Herve; Favata, Fabio

2015-04-01

We identify nine young stellar objects (YSOs) in the NGC 2264 star-forming region with optical CoRoT light curves exhibiting short-duration, shallow periodic flux dips. All of these stars have infrared excesses that are consistent with their having inner disk walls near the Keplerian co-rotation radius. The repeating photometric dips have FWHMs generally less than 1 day, depths almost always less than 15%, and periods (3 < P < 11 days) consistent with dust near the Keplerian co-rotation period. The flux dips vary considerably in their depth from epoch to epoch, but usually persist for several weeks and, in two cases, were present in data collected in successive years. For several of these stars, we also measure the photospheric rotation period and find that the rotation and dip periods are the same, as predicted by standard “disk-locking” models. We attribute these flux dips to clumps of material in or near the inner disk wall, passing through our line of sight to the stellar photosphere. In some cases, these dips are also present in simultaneous Spitzer IRAC light curves at 3.6 and 4.5 microns. We characterize the properties of these dips, and compare the stars with light curves exhibiting this behavior to other classes of YSOs in NGC 2264. A number of physical mechanisms could locally increase the dust scale height near the inner disk wall, and we discuss several of those mechanisms; the most plausible mechanisms are either a disk warp due to interaction with the stellar magnetic field or dust entrained in funnel-flow accretion columns arising near the inner disk wall. Based on data from the Spitzer and CoRoT missions, as well as the Canada France Hawaii Telescope (CFHT) MegaCam CCD, and the European Southern Observatory Very Large Telescope, Paranal Chile, under program 088.C-0239. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA’s RSSD and Science Programmes, Austria, Belgium, Brazil, Germany

Rotation Period of Blanco 1 Members from KELT Light Curves: Comparing Rotation-Ages to Various Stellar Chronometers at 100 Myr

NASA Astrophysics Data System (ADS)

Cargile, Phillip; James, D. J.; Pepper, J.; Kuhn, R.; Siverd, R. J.; Stassun, K. G.

2012-01-01

The age of a star is one of its most fundamental properties, and yet tragically it is also the one property that is not directly measurable in observations. We must therefore rely on age estimates based on mostly model-dependent or empirical methods. Moreover, there remains a critical need for direct comparison of different age-dating techniques using the same stars analyzed in a consistent fashion. One chronometer commonly being employed is using stellar rotation rates to measure stellar ages, i.e., gyrochronology. Although this technique is one of the better-understood chronometers, its calibration relies heavily on the solar datum, as well as benchmark open clusters with reliable ages, and also lacks a comprehensive comparative analysis to other stellar chronometers. The age of the nearby (? pc) open cluster Blanco 1 has been estimated using various techniques, including being one of only 7 clusters with an LDB age measurement, making it a unique and powerful comparative laboratory for stellar chronometry, including gyrochronology. Here, we present preliminary results from our light-curve analysis of solar-type stars in Blanco 1 in order to identify and measure rotation periods of cluster members. The light-curve data were obtained during the engineering and calibration phase of the KELT-South survey. The large area on the sky and low number of contaminating field stars makes Blanco 1 an ideal target for the extremely wide field and large pixel scale of the KELT telescope. We apply a period-finding technique using the Lomb-Scargle periodogram and FAP statistics to measure significant rotation periods in the KELT-South light curves for confirmed Blanco 1 members. These new rotation periods allow us to test and inform rotation evolution models for stellar ages at ? Myr, determining a rotation-age for Blanco 1 using gyrochronology, and compare this rotation-age to other age measurements for this cluster.

Periodic variation and its effect on management and prognosis of Korean patients with acute myocardial infarction.

PubMed

Park, Hyo Eun; Koo, Bon-Kwon; Lee, Wonjae; Cho, Youngjin; Park, Jin Sik; Choi, Ji-Yong; Jeong, Myung-Ho; Kim, Jong Hyun; Chae, Shung Chull; Kim, Young Jo; Nam, Chang-Wook; Lee, Jae-Hwan; Choi, Dong Hoon; Hong, Taek Jong; Chae, Jei Keon; Rhew, Jae Young; Kim, Kee Sik; Kim, Hyo-Soo; Oh, Byung-Hee; Park, Young Bae

2010-05-01

The characteristics of the periodic variation in acute myocardial infarction (AMI) and the subsequent effect on management and prognosis have not been fully investigated in a large number of Asian populations. From a prospective, observational multicenter online registry, 4,573 patients diagnosed as AMI in Korea from January to December 2006 were included. The highest incidence of AMI was between 8 a.m. and noon. The number of cases was highest in the winter and lowest in the autumn (13.6 vs 11.4 patients per day, P<0.001). Patients with symptom onset during working hours had a shorter time to first medical contact (203+/-288 min) compared with out-of-hours onset (230+/-288 min, P=0.003). In patients who underwent primary angioplasty, out-of hours symptom onset was associated with a greater time delay in both the patient's and the medical facility's response (door-to-balloon time out-of hours vs working hours: 101+/-54 min vs 84+/-44 min, P<0.001). In patients with ST-segment elevation myocardial infarction, symptoms to first medical contact showed a significant relationship to in-hospital mortality (for every 10 min of symptoms to first medical contact, odds ratio 1.006, 95% confidence interval 1.001-1.012, P=0.018) Circadian and periodic variation in AMI exists in Korean patients, which resulted in different patient behavior, hospital management and outcomes.

Low-dose combined oral contraceptive use is associated with lower bone mineral content variation in adolescents over a 1-year period.

PubMed

Biason, Talita Poli; Goldberg, Tamara Beres Lederer; Kurokawa, Cilmery Suemi; Moretto, Maria Regina; Teixeira, Altamir Santos; Nunes, Hélio Rubens de Carvalho

2015-04-03

Low-dose combined oral contraceptives (COCs) can interfere with bone mass acquisition during adolescence. This study aimed to evaluate bone mineral density (BMD) and bone mineral content (BMC) in female adolescents taking a standard low-dose COC (ethinylestradiol 20 μg/desogestrel 150 μg) over a 1-year period and to compare their data with those of healthy adolescents from the same age group not taking COCs. This was a non-randomized parallel-control study with a 1-year follow-up. Sixty-seven adolescents aged from 12 to 19 years, divided into COC users (n = 41) taking 20 μg ethinylestradiol/150 μg desogestrel and COC non-user controls (n = 26), were evaluated by bone densitometry examinations at baseline and after 12 months. Comparisons between the groups at the study onset were performed using the Mann-Whitney test with the significance level fixed at 5% or p < 0.05. Comparisons between the groups at the study onset and after 12 months were based on variations in the median percentages for bone mass variables. The COC users presented with low bone mass acquisition in the lumbar spine, and had BMD and BMC median variations of 2.07% and +1.57%, respectively, between the measurements at baseline and 12 months. The control group had median variations of +12.16% and +16.84% for BMD and BMC, respectively, over the same period. The total body BMD and BMC showed similar evolutions during the study in both groups. Statistical significance (p < 0.05) was seen for the BMC percentage variation between COC users and non-users. Use of a low-dose COC (ethinylestradiol 20 μg/desogestrel 150 μg) was associated with lower bone mass acquisition in adolescents during the study period. Registry Number, RBR-5h9b3c.

Evidence of cyclical light/dark-regulated expression of freezing tolerance in young winter wheat plants.

PubMed

Skinner, Daniel Z; Bellinger, Brian; Hiscox, William; Helms, Gregory L

2018-01-01

The ability of winter wheat (Triticum aestivum L.) plants to develop freezing tolerance through cold acclimation is a complex rait that responds to many environmental cues including day length and temperature. A large part of the freezing tolerance is conditioned by the C-repeat binding factor (CBF) gene regulon. We investigated whether the level of freezing tolerance of 12 winter wheat lines varied throughout the day and night in plants grown under a constant low temperature and a 12-hour photoperiod. Freezing tolerance was significantly greater (P<0.0001) when exposure to subfreezing temperatures began at the midpoint of the light period, or the midpoint of the dark period, compared to the end of either period, with an average of 21.3% improvement in survival. Thus, freezing survival was related to the photoperiod, but cycled from low, to high, to low within each 12-hour light period and within each 12-hour dark period, indicating ultradian cyclic variation of freezing tolerance. Quantitative real-time PCR analysis of expression levels of CBF genes 14 and 15 indicated that expression of these two genes also varied cyclically, but essentially 180° out of phase with each other. Proton nuclear magnetic resonance analysis (1H-NMR) showed that the chemical composition of the wheat plants' cellular fluid varied diurnally, with consistent separation of the light and dark phases of growth. A compound identified as glutamine was consistently found in greater concentration in a strongly freezing-tolerant wheat line, compared to moderately and poorly freezing-tolerant lines. The glutamine also varied in ultradian fashion in the freezing-tolerant wheat line, consistent with the ultradian variation in freezing tolerance, but did not vary in the less-tolerant lines. These results suggest at least two distinct signaling pathways, one conditioning freezing tolerance in the light, and one conditioning freezing tolerance in the dark; both are at least partially under the control

Ethanol consumption in mice: relationships with circadian period and entrainment.

PubMed

Trujillo, Jennifer L; Do, David T; Grahame, Nicholas J; Roberts, Amanda J; Gorman, Michael R

2011-03-01

A functional connection between the circadian timing system and alcohol consumption is suggested by multiple lines of converging evidence. Ethanol consumption perturbs physiological rhythms in hormone secretion, sleep, and body temperature; and conversely, genetic and environmental perturbations of the circadian system can alter alcohol intake. A fundamental property of the circadian pacemaker, the endogenous period of its cycle under free-running conditions, was previously shown to differ between selectively bred high- (HAP) and low- (LAP) alcohol preferring replicate 1 mice. To test whether there is a causal relationship between circadian period and ethanol intake, we induced experimental, rather than genetic, variations in free-running period. Male inbred C57Bl/6J mice and replicate 2 male and female HAP2 and LAP2 mice were entrained to light:dark cycles of 26 or 22 h or remained in a standard 24 h cycle. On discontinuation of the light:dark cycle, experimental animals exhibited longer and shorter free-running periods, respectively. Despite robust effects on circadian period and clear circadian rhythms in drinking, these manipulations failed to alter the daily ethanol intake of the inbred strain or selected lines. Likewise, driving the circadian system at long and short periods produced no change in alcohol intake. In contrast with replicate 1 HAP and LAP lines, there was no difference in free-running period between ethanol naïve HAP2 and LAP2 mice. HAP2 mice, however, were significantly more active than LAP2 mice as measured by general home-cage movement and wheel running, a motivated behavior implicating a selection effect on reward systems. Despite a marked circadian regulation of drinking behavior, the free-running and entrained period of the circadian clock does not determine daily ethanol intake. Copyright © 2011 Elsevier Inc. All rights reserved.

Ethanol consumption in mice: relationships with circadian period and entrainment

PubMed Central

Trujillo, Jennifer L.; Do, David T.; Grahame, Nicholas J.; Roberts, Amanda J.; Gorman, Michael R.

2011-01-01

A functional connection between the circadian timing system and alcohol consumption is suggested by multiple lines of converging evidence. Ethanol consumption perturbs physiological rhythms in hormone secretion, sleep and body temperature, and conversely, genetic and environmental perturbations of the circadian system can alter alcohol intake. A fundamental property of the circadian pacemaker, the endogenous period of its cycle under free-running conditions, was previously shown to differ between selectively bred High- (HAP) and Low- (LAP) Alcohol Preferring replicate 1 mice. To test whether there is a causal relationship between circadian period and ethanol intake, we induced experimental, rather than genetic, variations in free-running period. Male inbred C57Bl/6J mice and replicate 2 male and female HAP2 and LAP2 mice were entrained to light:dark cycles of 26 h or 22 h or remained in a standard 24 h cycle. Upon discontinuation of the light:dark cycle, experimental animals exhibited longer and shorter free-running periods, respectively. Despite robust effects on circadian period and clear circadian rhythms in drinking, these manipulations failed to alter the daily ethanol intake of the inbred strain or selected lines. Likewise, driving the circadian system at long and short periods produced no change in alcohol intake. In contrast with replicate 1 HAP and LAP lines, there was no difference in free-running period between ethanol naïve HAP2 and LAP2 mice. HAP2 mice, however, were significantly more active than LAP2 mice as measured by general home-cage movement and wheel running, a motivated behavior implicating a selection effect on reward systems. Despite a marked circadian regulation of drinking behavior, the free-running and entrained period of the circadian clock does not determine daily ethanol intake. PMID:20880659

A statistical light use efficiency model explains 85% variations in global GPP

NASA Astrophysics Data System (ADS)

Jiang, C.; Ryu, Y.

2016-12-01

Photosynthesis is a complicated process whose modeling requires different levels of assumptions, simplification, and parameterization. Among models, light use efficiency (LUE) model is highly compact but powerful in monitoring gross primary production (GPP) from satellite data. Most of LUE models adopt a multiplicative from of maximum LUE, absorbed photosynthetically active radiation (APAR), and temperature and water stress functions. However, maximum LUE is a fitting parameter with large spatial variations, but most studies only use several biome dependent constants. In addition, stress functions are empirical and arbitrary in literatures. Moreover, meteorological data used are usually coarse-resolution, e.g., 1°, which could cause large errors. Finally, sunlit and shade canopy have completely different light responses but little considered. Targeting these issues, we derived a new statistical LUE model from a process-based and satellite-driven model, the Breathing Earth System Simulator (BESS). We have already derived a set of global radiation (5-km resolution), carbon and water fluxes (1-km resolution) products from 2000 to 2015 from BESS. By exploring these datasets, we found strong correlation between APAR and GPP for sunlit (R2=0.84) and shade (R2=0.96) canopy, respectively. A simple model, only driven by sunlit and shade APAR, was thus built based on linear relationships. The slopes of the linear function act as effective LUE of global ecosystem, with values of 0.0232 and 0.0128 umol C/umol quanta for sunlit and shade canopy, respectively. When compared with MPI-BGC GPP products, a global proxy of FLUXNET data, BESS-LUE achieved an overall accuracy of R2 = 0.85, whereas original BESS was R2 = 0.83 and MODIS GPP product was R2 = 0.76. We investigated spatiotemporal variations of the effective LUE. Spatially, the ratio of sunlit to shade values ranged from 0.1 (wet tropic) to 4.5 (dry inland). By using maps of sunlit and shade effective LUE the accuracy of

Temporal variation in methane emissions in a shallow lake at a southern mid latitude during high and low rainfall periods.

PubMed

Fusé, Victoria S; Priano, M Eugenia; Williams, Karen E; Gere, José I; Guzmán, Sergio A; Gratton, Roberto; Juliarena, M Paula

2016-10-01

The global methane (CH 4 ) emission of lakes is estimated at between 6 and 16 % of total natural CH 4 emissions. However, these values have a high uncertainty due to the wide variety of lakes with important differences in their morphological, biological, and physicochemical parameters and the relatively scarse data from southern mid-latitude lakes. For these reasons, we studied CH 4 fluxes and CH 4 dissolved in water in a typical shallow lake in the Pampean Wetland, Argentina, during four periods of consecutive years (April 2011-March 2015) preceded by different rainfall conditions. Other water physicochemical parameters were measured and meteorological data were reported. We identified three different states of the lake throughout the study as the result of the irregular alternation between high and low rainfall periods, with similar water temperature values but with important variations in dissolved oxygen, chemical oxygen demand, water turbidity, electric conductivity, and water level. As a consequence, marked seasonal and interannual variations occurred in CH 4 dissolved in water and CH 4 fluxes from the lake. These temporal variations were best reflected by water temperature and depth of the Secchi disk, as a water turbidity estimation, which had a significant double correlation with CH 4 dissolved in water. The mean CH 4 fluxes values were 0.22 and 4.09 mg/m 2 /h for periods with low and high water turbidity, respectively. This work suggests that water temperature and turbidity measurements could serve as indicator parameters of the state of the lake and, therefore, of its behavior as either a CH 4 source or sink.

Lidar observed seasonal variation of vertical canopy structure in the Amazon evergreen forests

NASA Astrophysics Data System (ADS)

Tang, H.; Dubayah, R.

2017-12-01

Both light and water are important environmental factors governing tree growth. Responses of tropical forests to their changes are complicated and can vary substantially across different spatial and temporal scales. Of particular interest is the dry-season greening-up of Amazon forests, a phenomenon undergoing considerable debates whether it is real or a "light illusion" caused by artifacts of passive optical remote sensing techniques. Here we analyze seasonal dynamic patterns of vertical canopy structure in the Amazon forests using lidar observations from NASA's Ice, Cloud, and and land Elevation Satellite (ICESat). We found that the net greening of canopy layer coincides with the wet-to-dry transition period, and its net browning occurs mostly at the late dry season. The understory also shows a seasonal cycle, but with an opposite variation to canopy and minimal correlation to seasonal variations in rainfall or radiation. Our results further suggest a potential interaction between canopy layers in the light regime that can optimize the growth of Amazon forests during the dry season. This light regime variability that exists in both spatial and temporal domains can better reveal the dry-season greening-up phenomenon, which appears less obvious when treating the Amazon forests as a whole.

Choosing surgical lighting in the LED era.

PubMed

Knulst, Arjan J; Stassen, Laurents P S; Grimbergen, Cornelis A; Dankelman, Jenny

2009-12-01

The aim of this study is to evaluate the illumination characteristics of LED lights objectively to ease the selection of surgical lighting. The illuminance distributions of 5 main and 4 auxiliary lights were measured in 8 clinically relevant scenarios. For each light and scenario, the maximum illuminance E(c) (klux) and the size of the light field d(10) (mm) were computed. The results showed: that large variations for both E(c) (25-160 klux) and d(10) (109-300 mm) existed; that using auxiliary lights reduced both E(c) and d(10) by up to 80% and 30%; that with segmented lights, uneven light distributions occurred; and that with colored LED lights shadow edges on the surgical field became colored. Objective illuminance measurements show a wide variation between lights and a superiority of main over auxiliary lights. Uneven light distributions and colored shadows indicate that LED lights still need to converge to an optimal design.

Optoelectronic Performance Variations in InGaN/GaN Multiple-Quantum-Well Light-Emitting Diodes: Effects of Potential Fluctuation.

PubMed

Islam, Abu Bashar Mohammad Hamidul; Shim, Jong-In; Shin, Dong-Soo

2018-05-07

We investigate the cause of the optoelectronic performance variations in InGaN/GaN multiple-quantum-well blue light-emitting diodes, using three different samples from an identical wafer grown on a c -plane sapphire substrate. Various macroscopic measurements have been conducted, revealing that with increasing strain in the quantum wells (QWs), the crystal quality improves with an increasing peak internal quantum efficiency while the droop becomes more severe. We propose to explain these variations using a model where the in-plane local potential fluctuation in QWs is considered. Our work is contrasted with prior works in that macroscopic measurements are utilized to find clues on the microscopic changes and their impacts on the device performances, which has been rarely attempted.

Light curve solutions of the eclipsing eccentric binaries KIC 8111622, KIC 10518735, KIC 8196180 and their out-of-eclipse variability

NASA Astrophysics Data System (ADS)

Kjurkchieva, Diana P.; Vasileva, Doroteya L.

2018-02-01

We determined the orbits and stellar parameters of three eccentric eclipsing binaries by light curve solutions of their Kepler data. KIC 8111622 and KIC 10518735 undergo total eclipses while KIC 8196180 reveals partial eclipses. The target components are G and K stars, excluding the primary of KIC 8196180 which is early F star. KIC 8196180 reveals well-visible tidally-induced feature at periastron, i.e. it is an eclipsing heartbeat star. The characteristics of the observed periastron feature (shape, width and amplitude) confirm the theoretical predictions. There are additional out-of-eclipse variations of KIC 8196180 with the orbital period which may be explained by spot activity of synchronously rotating component. Besides worse visible periastron feature KIC 811162 exhibits small-amplitude light variations whose period is around 2.3 times shorter than the orbital one. These oscillations were attributed to spot(s) on asynchronously rotating component.

The Pulsational Nature of R-Coronae - Light and Radial Velocity Variations during 1990 and 1991

NASA Astrophysics Data System (ADS)

Fernie, J. D.; Lawson, W. A.

1993-12-01

We report photometry and radial velocities of the R Coronae Borealis (RCB) star R CrB, obtained during 1991. We compare these observations with published photometry obtained during 1990 and velocities obtained during 1990 and 1991, and analyse these data using Fourier techniques. In line with the conclusions of earlier analyses, the pulsational nature of R CrB is difficult to quantify, particularly on timescales of longer than a yea The 1990 data are possibly consistent with the presence of a 43-d radial pulsation mode. During 1991 there was some evidence for a periodicity near this value in the radial velocities, but not in the photometric data. Additional data are desirable to investigate the possible presence of one or more periodicities in the light and radial velocity curves.

On-sky verification of the 6-h periodic basic angle variations of the Gaia satellite

NASA Astrophysics Data System (ADS)

Liao, Shilong; Lattanzi, Mario G.; Vecchiato, Alberto; Qi, Zhaoxiang; Crosta, Mariateresa; Tang, Zhenghong

2018-04-01

A Basic Angle (BA) of 106.5° separates the view directions of Gaia's two fields of view (FoV). A precise determination of the BA variations (BAV) is essential to guarantee a correct reconstruction of the global astrometric sphere, as residual systematic errors would result in, e.g., a bias in the parallaxes of the final Gaia catalog. The Basic Angle Monitoring (BAM) device, which provides a reliable and accurate estimation of BAV, shows that there exists a ~1 mas amplitude, 6-h period BA oscillation. It's essential to verify to what extent this signal is caused by real BAV, or is at least in part an effect of the BAM device itself. Here, we propose an astrometric on-sky approach to re-determine the 6-h periodic BAV. The results of this experiment, which treated a full day (17 Oct 2016) of Gaia astrometric data, recover a value for the 6-h oscillation of 1.856+/-0.857 mas. This is consistent, within the errors, with the BAM finding for that day.

Variations in total ozone column and biologically effective solar UV exposure doses in Bologna, Italy during the period 2005-2010

NASA Astrophysics Data System (ADS)

Petkov, Boyan; Vitale, Vito; Tomasi, Claudio; Mazzola, Mauro; Lanconelli, Christian; Lupi, Angelo; Busetto, Maurizio

2014-01-01

Variations in total ozone column and sun exposures able to cause erythema and damage the DNA molecules were observed by the narrow-band filter radiometer UV-RAD in Bologna, Italy from 2005 to 2010. The ozone columns determined from the UV-RAD measurements were found to be close to those provided by the satellite Ozone Monitoring Instrument (OMI) showing an average discrepancy of 1 % with standard deviation of ± 6 %. Analysis of the data highlights a well-marked annual cycle of the ozone column variations while the oscillations with periods of 8, 18 and 34 months present much smaller amplitudes. The influence of the frequency of solar irradiance measurements on the accuracy of the evaluated daily exposure dose has been studied and it was found that time intervals no longer than 5-10 min between the measurements of erythema and DNA damage effective UV irradiances provide a satisfactory assessment of the corresponding daily exposures. The latter do not present significant year-to-year variations for the period under study, while their annual distributions show slight changes likely due to the specific cloud cover and ozone column variability for different years. The annual erythemal exposure dose for 2007-2010 varied between 603.7 and 638.1 kJ m-2, while the corresponding sun exposure affecting DNA changed from 6.38 to 7.91 kJ m-2.

Comparing models of the periodic variations in spin-down and beamwidth for PSR B1828-11

NASA Astrophysics Data System (ADS)

Ashton, G.; Jones, D. I.; Prix, R.

2016-05-01

We build a framework using tools from Bayesian data analysis to evaluate models explaining the periodic variations in spin-down and beamwidth of PSR B1828-11. The available data consist of the time-averaged spin-down rate, which displays a distinctive double-peaked modulation, and measurements of the beamwidth. Two concepts exist in the literature that are capable of explaining these variations; we formulate predictive models from these and quantitatively compare them. The first concept is phenomenological and stipulates that the magnetosphere undergoes periodic switching between two metastable states as first suggested by Lyne et al. The second concept, precession, was first considered as a candidate for the modulation of B1828-11 by Stairs et al. We quantitatively compare models built from these concepts using a Bayesian odds ratio. Because the phenomenological switching model itself was informed by these data in the first place, it is difficult to specify appropriate parameter-space priors that can be trusted for an unbiased model comparison. Therefore, we first perform a parameter estimation using the spin-down data, and then use the resulting posterior distributions as priors for model comparison on the beamwidth data. We find that a precession model with a simple circular Gaussian beam geometry fails to appropriately describe the data, while allowing for a more general beam geometry provides a good fit to the data. The resulting odds between the precession model (with a general beam geometry) and the switching model are estimated as 102.7±0.5 in favour of the precession model.

Orbital period study of the Algol-type eclipsing binary system TW Draconis

NASA Astrophysics Data System (ADS)

Qian, S. B.; Boonrucksar, S.

2002-10-01

The century-long times of light minimum of the Algol-type eclipsing binary star, TW Dra (BD +64°1077, Sp A5V+K2III), are investigated by considering a new pattern of period change. Two sudden period increases and two successive period decreases are discovered to superimpose on a rapid secular increase (d P/d t=+4.43×10 -6 days/year). The secular increase may be caused by a dynamical mass transfer from the secondary to the primary component (d m/d t=6.81×10 -7 M ⊙/year) that is in agreement with the semi-detached configuration of the system and with the existence of a hot spot and a gaseous stream in the binary system. The irregular period jumps superimposed on the secular increase can be explained by the structure variation of the K2-type giant via instabilities of the outer convective layer or via magnetic activity cycles.

Relativistic boost as the cause of periodicity in a massive black-hole binary candidate.

PubMed

D'Orazio, Daniel J; Haiman, Zoltán; Schiminovich, David

2015-09-17

Because most large galaxies contain a central black hole, and galaxies often merge, black-hole binaries are expected to be common in galactic nuclei. Although they cannot be imaged, periodicities in the light curves of quasars have been interpreted as evidence for binaries, most recently in PG 1302-102, which has a short rest-frame optical period of four years (ref. 6). If the orbital period of the black-hole binary matches this value, then for the range of estimated black-hole masses, the components would be separated by 0.007-0.017 parsecs, implying relativistic orbital speeds. There has been much debate over whether black-hole orbits could be smaller than one parsec (ref. 7). Here we report that the amplitude and the sinusoid-like shape of the variability of the light curve of PG 1302-102 can be fitted by relativistic Doppler boosting of emission from a compact, steadily accreting, unequal-mass binary. We predict that brightness variations in the ultraviolet light curve track those in the optical, but with a two to three times larger amplitude. This prediction is relatively insensitive to the details of the emission process, and is consistent with archival ultraviolet data. Follow-up ultraviolet and optical observations in the next few years can further test this prediction and confirm the existence of a binary black hole in the relativistic regime.

Attaining the canopy in dry and moist tropical forests: strong differences in tree growth trajectories reflect variation in growing conditions

PubMed Central

Zuidema, Pieter A.; Martínez-Ramos, Miguel

2009-01-01

Availability of light and water differs between tropical moist and dry forests, with typically higher understorey light levels and lower water availability in the latter. Therefore, growth trajectories of juvenile trees—those that have not attained the canopy—are likely governed by temporal fluctuations in light availability in moist forests (suppressions and releases), and by spatial heterogeneity in water availability in dry forests. In this study, we compared juvenile growth trajectories of Cedrela odorata in a dry (Mexico) and a moist forest (Bolivia) using tree rings. We tested the following specific hypotheses: (1) moist forest juveniles show more and longer suppressions, and more and stronger releases; (2) moist forest juveniles exhibit wider variation in canopy accession pattern, i.e. the typical growth trajectory to the canopy; (3) growth variation among dry forest juveniles persists over longer time due to spatial heterogeneity in water availability. As expected, the proportion of suppressed juveniles was higher in moist than in dry forest (72 vs. 17%). Moist forest suppressions also lasted longer (9 vs. 5 years). The proportion of juveniles that experienced releases in moist forest (76%) was higher than in dry forest (41%), and releases in moist forests were much stronger. Trees in the moist forest also had a wider variation in canopy accession patterns compared to the dry forest. Our results also showed that growth variation among juvenile trees persisted over substantially longer periods of time in dry forest (>64 years) compared to moist forest (12 years), most probably because of larger persistent spatial variation in water availability. Our results suggest that periodic increases in light availability are more important for attaining the canopy in moist forests, and that spatial heterogeneity in water availability governs long-term tree growth in dry forests. Electronic supplementary material The online version of this article (doi:10.1007/s

Variations in the Orbital Light Curve of the Magnetic Cataclysmic Variable Star QQ Vulpecula (Abstract)

NASA Astrophysics Data System (ADS)

Rose, S. C.

2017-06-01

(Abstract only) Magnetic cataclysmic variable stars have brightness variations that repeat with each revolution of the two stars about the center of mass of the system. However, in the case of QQ Vulpecula, this brightness variation pattern changes in the long term. This study makes use of two decades worth of data from the Roboscope Telescope as well as data from the American Association of Variable Star Observers (AAVSO) database to examine the long-term evolution of QQ Vul's phase curves. Nightly observations using the Maria Mitchell Association Vestal and Loines Observatory supplemented this analysis by clarifying short-term brightness variation. The long-term data was divided into four commonly observed behavioral types ranging from a double peaked curve of 15.5 magnitude to a 15.0 magnitude curve that had a primary minimum and a slow, linear rise in brightness in place of the secondary minimum. The nightly data kept within the confines of these categories, though the secondary minimum in the nightly data never vanished. No periodicity was found in the long-term variations. The model often invoked to explain the double peaked curve consists of single pole accretion in which a partial self-eclipse causes the secondary minimum and cyclotron beaming causes the primary minimum. However, the long-term variation may indicate a changing accretion rate, which may manifest itself in changes to the shape, size, or location of the accretion spot on the white dwarf such that it lessens or removes the secondary minimum. This project was supported by the NSF REU grant AST-1358980, the Massachusetts Space Grant, and the Nantucket Maria Mitchell Association.

Does the hybrid light source (LED/laser) influence temperature variation on the enamel surface during 35% hydrogen peroxide bleaching? A randomized clinical trial.

PubMed

de Freitas, Patricia Moreira; Menezes, Andressa Nery; da Mota, Ana Carolina Costa; Simões, Alyne; Mendes, Fausto Medeiros; Lago, Andrea Dias Neves; Ferreira, Leila Soares; Ramos-Oliveira, Thayanne Monteiro

2016-01-01

The present study investigated how a hybrid light source (LED/laser) influences temperature variation on the enamel surfaces during 35% hydrogen peroxide (HP) bleaching. Effects on the whitening effectiveness and tooth sensitivity were analyzed. Twenty-two volunteers were randomly assigned to two different treatments in a split-mouth experimental model: group 1 (control), 35% HP; group 2 (experimental), 35% HP + LED/laser. Color evaluation was performed before treatment, and 7 and 14 days after completion of bleaching, using a color shade scale. Tooth sensitivity was assessed using a visual analog scale (VAS; before, immediately, and 24 hours after bleaching). During the bleaching treatment, thermocouple channels positioned on the tooth surfaces recorded the temperature. Data on color and temperature changes were subjected to statistical analysis (α = 5%). Tooth sensitivity data were evaluated descriptively. Groups 1 and 2 showed mean temperatures (± standard deviation) of 30.7 ± 1.2 °C and 34.1 ± 1.3 °C, respectively. It was found that there were statistically significant differences between the groups, with group 2 showing higher mean variation (P < .0001). The highest temperature variation occurred for group 2, with an increase of 5.3 °C at the enamel surface. The color change results showed no differences in bleaching between the two treatment groups (P = .177). The variation of the average temperature during the treatments was not statistically associated with color variation (P = .079). Immediately after bleaching, it was found that 36.4% of the subjects in group 2 had mild to moderate sensitivity. In group 1, 45.5% showed moderate sensitivity. In both groups, the sensitivity ceased within 24 hours. Hybrid light source (LED/ laser) influences temperature variation on the enamel surface during 35% HP bleaching and is not related to greater tooth sensitivity.

A long-term study of H(alpha) line variations in FK Comae Berenices

NASA Technical Reports Server (NTRS)

Welty, Alan D.; Ramsey, Lawrence W.; Iyengar, Mrinal; Nations, Harold L.; Buzasi, Derek L.

1993-01-01

We present observations of H(alpha) V/R ratio variations in FK Comae Berencies obtained during several observing seasons from 1981 to 1992. The raw H(alpha) emission profile is always observed to be double peaked due to the stellar-absorption component. During the most years the V/R ratio varies regularly with the period of the photometric light curve. The V/R periodicity is most obvious when time spans no longer than several stellar rotations are considered. We propose that the bulk of the emission component of the H(alpha) line arises in corotating circumstellar material that may be similar to that of a quiescent solar prominence. The lifetime of these structures appears to be on the order of weeks. A weak contribution from a circumstellar disk is evident and chromospheric emission may also be present. The appearance or disappearance of circumstellar structures over periods longer than a few weeks, or the total absence of such structures, blurs the more regular variations in H(alpha) seen over short time scales. Other more stochastic activity, such as flares, also clearly occurs. Phase shifts of the V/R ratio from year to year rule out the hypothesis that mass tranfer in a close binary system is responsible for the V/R variations.

The First Photometric and Period Investigation of the Total Eclipse Binary System V0474 Cam

NASA Astrophysics Data System (ADS)

Guo, D. F.; Li, K.; Hu, S. M.; Chen, X.

2018-06-01

Three complete multi-band light curves of the W UMa-type binary V0474 Cam, which display a total eclipse, were obtained on four nights during two observing seasons from 2016 February 9 to 2017 February 24. By analyzing all obtainable times of light minimum, including 8 newly calculated, a downward parabolic change was found to be overlaid with a possible cyclic oscillation. The secular period decrease is determined to be {dP}/{dt}=-9.42 × {10}-7 days yr‑1, which can be explained by the existence of angular momentum loss from the binary system via a magnetic stellar wind. The cyclic oscillation, with a 3.44-yr period and a 0.0015-days amplitude, could be explained more plausibly by the magnetic activity, although the light-travel time effect as result of the present of a third component cannot be excluded. According to the three complete light curves, the intrinsic variations are obvious, particularly in the deepness at primary minimum and in the phase around 0.75. The light curve of V0474 Cam is symmetric observed in February 2016, then it become asymmetric in December 2016 and February 2017. The W-D program was adopted to investigate the multi-band light curves and the results indicate V0474 Cam is a W-subtype binary (the less massive component is hotter). A mass ratio of q = 3.230 was derived by analyzing the symmetric light curves observed at February in 2016. After accepting the results derived from the symmetric light curves as the references, other two sets of asymmetrical light curves can be well resolved through adding a cool spot on the more massive component.

DNA Sequence Variation at the Period Locus within and among Species of the Drosophila Melanogaster Complex

PubMed Central

Kliman, R. M.; Hey, J.

1993-01-01

A 1.9-kilobase region of the period locus was sequenced in six individuals of Drosophila melanogaster and from six individuals of each of three sibling species: Drosophila simulans, Drosophila sechellia and Drosophila mauritiana. Extensive genealogical analysis of 174 polymorphic sites reveals a complex history. It appears that D. simulans, as a large population still segregating very old lineages, gave rise to the island species D. mauritiana and D. sechellia. Rather than considering these speciation events as having produced ``sister'' taxa, it seems more appropriate to consider D. simulans a parent species to D. sechellia and D. mauritiana. The order, in time, of these two phylogenetic events remains unclear. D. mauritiana supports a large number of polymorphisms, many of which are shared with D. simulans, and so appears to have begun and persisted as a large population. In contrast, D. sechellia has very little variation and seems to have experienced a severe population bottleneck. Alternatively, the low variation in D. sechellia could be due to recent directional selection and genetic hitchhiking at or near the per locus. PMID:8436278

Monitoring Period and Amplitude Changes in Classical Cepheids

NASA Astrophysics Data System (ADS)

Erickson, Mary; Engle, Scott G.; Wells, Mark

2017-06-01

Cepheid Variable Stars, which are located on the Instability Strip of the Hertzsprung-Russel Diagram, can be used as “standard candle” distance markers (Fiorentino 2007). This came about after the discovery of the Period-Luminosity Relationship (the Leavitt Law), and they have since become a cornerstone of the Cosmic Distance Scale and are helping to further refine the Hubble Constant. Cepheids will cross the Instability Strip, either in a “redward” (cooler) or “blueward” (hotter) direction depending on the stage in which the Cepheid is evolving (Neilson 2012). While Cepheids were originally believed to have regular periods, many are now known to have varying periods, dating back to Eddington (1919). Therefore, Cepheids must be closely monitored in order to deduce where these period variations are coming from - either from inside the star itself or from some outside source. Determining period changes in Cepheids can reveal important information (e.g. evolutionary states, potential companions, etc.).Photometric data were taken for two Cepheids from two different sources and analyzed. The Cepheids in question are AA Gem and BB Gem, both located in the Gemini constellation. Data for these two stars were taken from the All Sky Automated Survey (ASAS) and from the Robotically Controlled Telescope (RCT) at Kitt Peak National Observatory, on which Villanova has guaranteed access. ASAS observes automatically each clear night, and has done so for several years, making it an excellent source for obtaining Cepheid data. The RCT telescope also operates automatically, observing from a preset target list, and achieves a much higher precision than ASAS can. Multi-aperture photometry was performed on the AA Gem and BB Gem RCT images, in Astroimagej. The data were then separated into different seasons, and Fourier fits were applied to the light curves in Kephem (written by Andrej Prša and collaborators). These results were then analyzed via the Hertzsprung Method to

Monitoring Period and Amplitude Changes in Classical Cepheids

NASA Astrophysics Data System (ADS)

Erickson, Mary; Engle, Scott G.; Wells, Mark

2017-01-01

Cepheid Variable Stars, which are located on the Instability Strip of the Hertzsprung-Russel Diagram, can be used as “standard candle” distance markers (Fiorentino 2007). This came about after the discovery of the Period-Luminosity Relationship (the Leavitt Law), and they have since become a cornerstone of the Cosmic Distance Scale and are helping to further refine the Hubble Constant. Cepheids will cross the Instability Strip, either in a “redward” (cooler) or “blueward” (hotter) direction depending on the stage in which the Cepheid is evolving (Neilson 2012). While Cepheids were originally believed to have regular periods, many are now known to have varying periods, dating back to Eddington (1919). Therefore, Cepheids must be closely monitored in order to deduce where these period variations are coming from - either from inside the star itself or from some outside source. Determining period changes in Cepheids can reveal important information (e.g. evolutionary states, potential companions, etc.).Photometric data were taken for two Cepheids from two different sources and analyzed. The Cepheids in question are AA Gem and BB Gem, both located in the Gemini constellation. Data for these two stars were taken from the All Sky Automated Survey (ASAS) and from the Robotically Controlled Telescope (RCT) at Kitt Peak National Observatory, on which Villanova has guaranteed access. ASAS observes automatically each clear night, and has done so for several years, making it an excellent source for obtaining Cepheid data. The RCT telescope also operates automatically, observing from a preset target list, and achieves a much higher precision than ASAS can. Multi-aperture photometry was performed on the AA Gem and BB Gem RCT images, in Astroimagej. The data were then separated into different seasons, and Fourier fits were applied to the light curves in Kephem (written by Andrej Prša and collaborators). These results were then analyzed via the Hertzsprung Method to

Optimizing LED lighting for space plant growth unit: Joint effects of photon flux density, red to white ratios and intermittent light pulses

NASA Astrophysics Data System (ADS)

Avercheva, O. V.; Berkovich, Yu. A.; Konovalova, I. O.; Radchenko, S. G.; Lapach, S. N.; Bassarskaya, E. M.; Kochetova, G. V.; Zhigalova, T. V.; Yakovleva, O. S.; Tarakanov, I. G.

2016-11-01

The aim of this work were to choose a quantitative optimality criterion for estimating the quality of plant LED lighting regimes inside space greenhouses and to construct regression models of crop productivity and the optimality criterion depending on the level of photosynthetic photon flux density (PPFD), the proportion of the red component in the light spectrum and the duration of the duty cycle (Chinese cabbage Brassica chinensis L. as an example). The properties of the obtained models were described in the context of predicting crop dry weight and the optimality criterion behavior when varying plant lighting parameters. Results of the fractional 3-factor experiment demonstrated the share of the PPFD level participation in the crop dry weight accumulation was 84.4% at almost any combination of other lighting parameters, but when PPFD value increased up to 500 μmol m-2 s-1 the pulse light and supplemental light from red LEDs could additionally increase crop productivity. Analysis of the optimality criterion response to variation of lighting parameters showed that the maximum coordinates were the following: PPFD = 500 μmol m-2 s-1, about 70%-proportion of the red component of the light spectrum (PPFDLEDred/PPFDLEDwhite = 1.5) and the duty cycle with a period of 501 μs. Thus, LED crop lighting with these parameters was optimal for achieving high crop productivity and for efficient use of energy in the given range of lighting parameter values.

The Effect of Eradication of Lice on the Occurrence of the Grain Defect Light Flecks and Spots on Cattle Hides

PubMed Central

Nafstad, O; Grønstøl, H

2001-01-01

The influence of an eradication programme for lice on the prevalence of light flecks and spots on cattle hides was studied in 33 dairy cattle herds during a period of two and a half years. Lice were eradicated from the main group of herds after 9 to 12 months and the quality of the hides before and after treatment was compared. Hides from slaughtered animals were collected during the study period, tanned and examined with special emphasis on the occurrence of the grain damage light flecks and spots. The prevalence of hides without light flecks and spots increased from 24.2% before treatment to 61.6% after treatment. The prevalence of hides free from the damage increased significantly in all examined anatomical regions. The improvement in hide quality was most marked in the shoulders and neck region which corresponded to the major predilection site of cattle lice. The prevalence of hides with light flecks and spots started to decrease in the first period (2–40 days) after eradication. The changes after treatment suggested that most healing process took place over a period of about 4 months. The eradication programme eliminated the seasonal variation in the prevalence of light flecks and spots which was present before treatment. PMID:11455906

Simple Sequence Repeats Provide a Substrate for Phenotypic Variation in the Neurospora crassa Circadian Clock

PubMed Central

Michael, Todd P.; Park, Sohyun; Kim, Tae-Sung; Booth, Jim; Byer, Amanda; Sun, Qi; Chory, Joanne; Lee, Kwangwon

2007-01-01

Background WHITE COLLAR-1 (WC-1) mediates interactions between the circadian clock and the environment by acting as both a core clock component and as a blue light photoreceptor in Neurospora crassa. Loss of the amino-terminal polyglutamine (NpolyQ) domain in WC-1 results in an arrhythmic circadian clock; this data is consistent with this simple sequence repeat (SSR) being essential for clock function. Methodology/Principal Findings Since SSRs are often polymorphic in length across natural populations, we reasoned that investigating natural variation of the WC-1 NpolyQ may provide insight into its role in the circadian clock. We observed significant phenotypic variation in the period, phase and temperature compensation of circadian regulated asexual conidiation across 143 N. crassa accessions. In addition to the NpolyQ, we identified two other simple sequence repeats in WC-1. The sizes of all three WC-1 SSRs correlated with polymorphisms in other clock genes, latitude and circadian period length. Furthermore, in a cross between two N. crassa accessions, the WC-1 NpolyQ co-segregated with period length. Conclusions/Significance Natural variation of the WC-1 NpolyQ suggests a mechanism by which period length can be varied and selected for by the local environment that does not deleteriously affect WC-1 activity. Understanding natural variation in the N. crassa circadian clock will facilitate an understanding of how fungi exploit their environments. PMID:17726525

Variations in protein-flavin hydrogen bonding in a light, oxygen, voltage domain produce non-Arrhenius kinetics of adduct decay.

PubMed

Zoltowski, Brian D; Nash, Abigail I; Gardner, Kevin H

2011-10-18

Light, oxygen, voltage (LOV) domains utilize a conserved blue light-dependent mechanism to control a diverse array of effector domains in biological and engineered proteins. Variations in the kinetics and efficiency of LOV photochemistry fine-tune various aspects of the photic response. Characterization of the kinetics of a key aspect of this photochemical mechanism in EL222, a blue light responsive DNA binding protein from Erythrobacter litoralis HTCC2594, reveals unique non-Arrhenius behavior in the rate of dark-state cleavage of the photochemically generated adduct. Sequence analysis and mutagenesis studies establish that this effect stems from a Gln to Ala mutation unique to EL222 and homologous proteins from marine bacteria. Kinetic and spectroscopic analyses reveal that hydrogen bonding interactions between the FMN N1, O2, and ribityl hydroxyls and the surrounding protein regulate photocycle kinetics and stabilize the LOV active site from temperature-induced alteration in local structure. Substitution of residues interacting with the N1-O2 locus modulates adduct stability, structural flexibility, and sequestration of the active site from bulk solvent without perturbation of light-activated DNA binding. Together, these variants link non-Arrhenius behavior to specific alteration of an H-bonding network, while affording tunability of photocycle kinetics. © 2011 American Chemical Society

Can the relativistic light-bending model explain X-ray spectral variations of Seyfert galaxies?

NASA Astrophysics Data System (ADS)

Mizumoto, Misaki; Moriyama, Kotaro; Ebisawa, Ken; Mineshige, Shin; Kawanaka, Norita; Tsujimoto, Masahiro

2018-04-01

Many Seyfert galaxies are known to exhibit Fe-K broad emission line features in their X-ray energy spectra. The observed lines have three distinct features: (1) the line profiles are skewed and show significant low-energy tails, (2) the Fe-K band has low variability, which produces a broad and deep dip in the root-mean-square (rms) spectra, and (3) photons in this band have time lags behind those in the adjacent energy bands with amplitudes of several Rg/c, where Rg is the gravitational radius. The "relativistic light-bending model" is proposed to explain these observed features, where a compact X-ray source ("lamp post") above an extreme Kerr black hole illuminates the innermost area of the accretion disc. In this paper, we critically examine the relativistic light-bending model by computing the rms spectra and the lag features using a ray-tracing technique, when a lamp post moves vertically on the black hole spin axis. As a result, we found that the observed deep rms dip requires that the iron is extremely overabundant (≳10 solar), whereas the observed lag amplitude is consistent with the normal iron abundance. Furthermore, disappearance of the lag in the high-flux state requires a source height as high as ˜40 Rg, which contradicts the relativistically broad emission line feature. Our simulations agree with the data that the reverberation feature moves to lower frequencies with larger source height; however, if this scenario is correct, the simulations predict the detection of a clear Fe-K lag at low frequencies, which is not constrained in the data. Therefore, we conclude that the relativistic light-bending model may not explain the characteristic Fe-K spectral variations in Seyfert galaxies.

Can the relativistic light-bending model explain X-ray spectral variations of Seyfert galaxies?

NASA Astrophysics Data System (ADS)

Mizumoto, Misaki; Moriyama, Kotaro; Ebisawa, Ken; Mineshige, Shin; Kawanaka, Norita; Tsujimoto, Masahiro

2018-06-01

Many Seyfert galaxies are known to exhibit Fe-K broad emission line features in their X-ray energy spectra. The observed lines have three distinct features: (1) the line profiles are skewed and show significant low-energy tails, (2) the Fe-K band has low variability, which produces a broad and deep dip in the root-mean-square (rms) spectra, and (3) photons in this band have time lags behind those in the adjacent energy bands with amplitudes of several Rg/c, where Rg is the gravitational radius. The "relativistic light-bending model" is proposed to explain these observed features, where a compact X-ray source ("lamp post") above an extreme Kerr black hole illuminates the innermost area of the accretion disc. In this paper, we critically examine the relativistic light-bending model by computing the rms spectra and the lag features using a ray-tracing technique, when a lamp post moves vertically on the black hole spin axis. As a result, we found that the observed deep rms dip requires that the iron is extremely overabundant (≳10 solar), whereas the observed lag amplitude is consistent with the normal iron abundance. Furthermore, disappearance of the lag in the high-flux state requires a source height as high as ˜40 Rg, which contradicts the relativistically broad emission line feature. Our simulations agree with the data that the reverberation feature moves to lower frequencies with larger source height; however, if this scenario is correct, the simulations predict the detection of a clear Fe-K lag at low frequencies, which is not constrained in the data. Therefore, we conclude that the relativistic light-bending model may not explain the characteristic Fe-K spectral variations in Seyfert galaxies.

Effects of guidelines implementation in a surgical intensive care unit to control nighttime light and noise levels.

PubMed

Walder, B; Francioli, D; Meyer, J J; Lançon, M; Romand, J A

2000-07-01

Because of around-the-clock activities, environmental noise and light are among the many causes of sleep disturbance in an intensive care unit (ICU). The implementation of guidelines may potentially change behavior rules and improve sleep quality. A prospective interventional study, observing the effects of simple nighttime guidelines on light and noise levels in an ICU. A modern surgical ICU, subdivided into six identical three-bed rooms. Critically ill adult patients. Between two observation periods, five guidelines were implemented to decrease both light and noise during the night shift in the patient's room. Light levels and noise levels were obtained using a luxmeter and a sound level meter [A-weighted decibels (dB) scale] and were monitored continuously from 11 pm to 5 am both before (period P1) and after (period P2) the implementation of guidelines. Similar patient's gravity and nursing workload scores were observed between P1 and P2. A low mean (<5 Lux) and maximal light level were measured during both P1 and P2. The implementation of guidelines lowered mean light disturbance intensity with a greater variability of light during P2. All noise levels were high and corresponded more to a quiet office for noise level equivalents and to a busy restaurant for peak noise levels during both P1 and P2. Guidelines decreased the noise level equivalent (P1, 51.3 dB; P2, 48.3 dB), peak noise level (P1, 74.9 dB; P2, 70.8 dB), and the number of acoustic identified alarms (P1, 22.1 dB; P2, 15.8 dB) during P2. The night light levels were low during both periods, and lowering the light levels induced a greater variation of light, which may impair sleep quality. All measured noise levels were high during both periods, which could contribute to sleep disturbance, and the implementation of guidelines significantly lowers some important noise levels. The background noise level was unchanged.

Evidence of Coat Color Variation Sheds New Light on Ancient Canids

PubMed Central

Ollivier, Morgane; Tresset, Anne; Hitte, Christophe; Petit, Coraline; Hughes, Sandrine; Gillet, Benjamin; Duffraisse, Marilyne; Pionnier-Capitan, Maud; Lagoutte, Laetitia; Arbogast, Rose-Marie; Balasescu, Adrian; Boroneant, Adina; Mashkour, Marjan; Vigne, Jean-Denis; Hänni, Catherine

2013-01-01

We have used a paleogenetics approach to investigate the genetic landscape of coat color variation in ancient Eurasian dog and wolf populations. We amplified DNA fragments of two genes controlling coat color, Mc1r (Melanocortin 1 Receptor) and CBD103 (canine-β-defensin), in respectively 15 and 19 ancient canids (dogs and wolf morphotypes) from 14 different archeological sites, throughout Asia and Europe spanning from ca. 12 000 B.P. (end of Upper Palaeolithic) to ca. 4000 B.P. (Bronze Age). We provide evidence of a new variant (R301C) of the Melanocortin 1 receptor (Mc1r) and highlight the presence of the beta-defensin melanistic mutation (CDB103-K locus) on ancient DNA from dog-and wolf-morphotype specimens. We show that the dominant KB allele (CBD103), which causes melanism, and R301C (Mc1r), the variant that may cause light hair color, are present as early as the beginning of the Holocene, over 10 000 years ago. These results underline the genetic diversity of prehistoric dogs. This diversity may have partly stemmed not only from the wolf gene pool captured by domestication but also from mutations very likely linked to the relaxation of natural selection pressure occurring in-line with this process. PMID:24098367

Evidence of coat color variation sheds new light on ancient canids.

PubMed

Ollivier, Morgane; Tresset, Anne; Hitte, Christophe; Petit, Coraline; Hughes, Sandrine; Gillet, Benjamin; Duffraisse, Marilyne; Pionnier-Capitan, Maud; Lagoutte, Laetitia; Arbogast, Rose-Marie; Balasescu, Adrian; Boroneant, Adina; Mashkour, Marjan; Vigne, Jean-Denis; Hänni, Catherine

2013-01-01

We have used a paleogenetics approach to investigate the genetic landscape of coat color variation in ancient Eurasian dog and wolf populations. We amplified DNA fragments of two genes controlling coat color, Mc1r (Melanocortin 1 Receptor) and CBD103 (canine-β-defensin), in respectively 15 and 19 ancient canids (dogs and wolf morphotypes) from 14 different archeological sites, throughout Asia and Europe spanning from ca. 12 000 B.P. (end of Upper Palaeolithic) to ca. 4000 B.P. (Bronze Age). We provide evidence of a new variant (R301C) of the Melanocortin 1 receptor (Mc1r) and highlight the presence of the beta-defensin melanistic mutation (CDB103-K locus) on ancient DNA from dog-and wolf-morphotype specimens. We show that the dominant K(B) allele (CBD103), which causes melanism, and R301C (Mc1r), the variant that may cause light hair color, are present as early as the beginning of the Holocene, over 10,000 years ago. These results underline the genetic diversity of prehistoric dogs. This diversity may have partly stemmed not only from the wolf gene pool captured by domestication but also from mutations very likely linked to the relaxation of natural selection pressure occurring in-line with this process.

Spectroscopic Doppler analysis for visible-light optical coherence tomography

NASA Astrophysics Data System (ADS)

Shu, Xiao; Liu, Wenzhong; Duan, Lian; Zhang, Hao F.

2017-12-01

Retinal oxygen metabolic rate can be effectively measured by visible-light optical coherence tomography (vis-OCT), which simultaneously quantifies oxygen saturation and blood flow rate in retinal vessels through spectroscopic analysis and Doppler measurement, respectively. Doppler OCT relates phase variation between sequential A-lines to the axial flow velocity of the scattering medium. The detectable phase shift is between -π and π due to its periodicity, which limits the maximum measurable unambiguous velocity without phase unwrapping. Using shorter wavelengths, vis-OCT is more vulnerable to phase ambiguity since flow induced phase variation is linearly related to the center wavenumber of the probing light. We eliminated the need for phase unwrapping using spectroscopic Doppler analysis. We split the whole vis-OCT spectrum into a series of narrow subbands and reconstructed vis-OCT images to extract corresponding Doppler phase shifts in all the subbands. Then, we quantified flow velocity by analyzing subband-dependent phase shift using linear regression. In the phantom experiment, we showed that spectroscopic Doppler analysis extended the measurable absolute phase shift range without conducting phase unwrapping. We also tested this method to quantify retinal blood flow in rodents in vivo.

A Hybrid Algorithm for Period Analysis from Multiband Data with Sparse and Irregular Sampling for Arbitrary Light-curve Shapes

NASA Astrophysics Data System (ADS)

Saha, Abhijit; Vivas, A. Katherina

2017-12-01

Ongoing and future surveys with repeat imaging in multiple bands are producing (or will produce) time-spaced measurements of brightness, resulting in the identification of large numbers of variable sources in the sky. A large fraction of these are periodic variables: compilations of these are of scientific interest for a variety of purposes. Unavoidably, the data sets from many such surveys not only have sparse sampling, but also have embedded frequencies in the observing cadence that beat against the natural periodicities of any object under investigation. Such limitations can make period determination ambiguous and uncertain. For multiband data sets with asynchronous measurements in multiple passbands, we wish to maximally use the information on periodicity in a manner that is agnostic of differences in the light-curve shapes across the different channels. Given large volumes of data, computational efficiency is also at a premium. This paper develops and presents a computationally economic method for determining periodicity that combines the results from two different classes of period-determination algorithms. The underlying principles are illustrated through examples. The effectiveness of this approach for combining asynchronously sampled measurements in multiple observables that share an underlying fundamental frequency is also demonstrated.

Temporal variations of the anomalous oxygen component

NASA Technical Reports Server (NTRS)

Cummings, A. C.; Webber, W. R.

1983-01-01

Data from the cosmic ray experiment on Voyagers 1 and 2 was used to examine anomalous oxygen in the time period from launch in 1977 to the end of 1981. Several time periods were found where large periodic (typically 26 day) temporal variations of the oxygen intensity between approximately 5 - 15 MeV/nuc are present. Variations in intensity by up to a factor of 10 are observed during these periods. Several characteristics of these variations indicate that they are not higher energy extensions of the low energy particle (approximately 1 MeV/nuc) increases found in many corotating interaction regions (CIR's). Many of these periodic temporal variations are correlated with similar, but much smaller, recurrent variations in the 75 MeV proton rate. Voyager 1 and Voyager 2 counting rates were compared to estimate the local radial gradient for both the protons and the oxygen. The proton gradients during periods of both maximum and minumum fluxes are consistent with the overall positive radial gradients reported by others from Pioneer and near-Earth observations, supporting the view that these variations are due to local modulation of a source outside the radial range of project measurements. In contrast, the oxygen gradients during periods of maximum proton flux differ in sign from those during minimum proton fluxes, suggesting that the origin of the oxygen variations is different from that of the protons.

Physiological responses of the CAM epiphyte Tillandsia usneoides L. (Bromeliaceae) to variations in light and water supply.

PubMed

Haslam, Richard; Borland, Anne; Maxwell, Kate; Griffiths, Howard

2003-06-01

In an effort to understand the mechanisms that sustain rootless atmospheric plants, the modulation of Crassulacean acid metabolism (CAM) in response to variations in irradiance and water supply was investigated in the epiphyte Tillandsia usneoides. Plants were acclimated to three light regimes, i.e. high, intermediate and low, with integrated photon flux densities (PFD) of 14.40, 8.64 and 4.32 mol m-2 d-1 equivalent to an instantaneous PFD of 200, 100, and 50 mumol m-2 s-1, respectively. Daily watering was then withdrawn from half of the plants at each PFD for 7 d prior to sampling. In response to the three PFD treatments, chlorophyll content increased in plants acclimated to lower irradiances. Light response curves using non-invasive measurements of chlorophyll fluorescence demonstrated that photosystem II efficiency (phi PSII) was maintained in high PFD acclimated plants, as they exhibited a larger capacity for non-photochemical dissipation (NPQ) of excess light energy than low PFD acclimated plants. Net CO2 uptake increased in response to higher PFD, reflecting enhanced carboxylation capacity in terms of phosphoenolpyruvate carboxylase (PEPc) and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) activities. After water was withdrawn, nocturnal net CO2 uptake and accumulated levels of acidity declined in all PFD treatments, concomitant with increased respiratory recycling of malate. Examining the strategies employed by epiphytes such as T. usneodies to tolerate extreme light and water regimes has demonstrated the importance of physiological mechanisms that allow flexible carboxylation capacity and continued carbon cycling to maintain photosynthetic integrity.

CCD Photometric Observations and Light Curve Synthesis of the Near-Contact Binary XZ Canis Minoris

NASA Astrophysics Data System (ADS)

Kim, Chun-Hwey; Park, Jang-Ho; Lee, Jae Woo; Jeong, Jang-Hae

2009-06-01

Through the photometric observations of the near-contact binary, XZ CMi, new BV light curves were secured and seven times of minimum light were determined. An intensive period study with all published timings, including ours, confirms that the period of XZ CMi has varied in a cyclic period variation superposed on a secular period decrease over last 70 years. Assuming the cyclic change of period to occur by a light-time effect due to a third-body, the light-time orbit with a semi-amplitude of 0.0056d, a period of 29y and an eccentricity of 0.71 was calculated. The observed secular period decrease of -5.26× 10^{-11} d/P was interpreted as a result of simultaneous occurrence of both a period decrease of -8.20 × 10^{-11} d/P by angular momentum loss (AML) due to a magnetic braking stellar wind and a period increase of 2.94 × 10^{-11} d/P by a mass transfer from the less massive secondary to the primary components in the system. In this line the decreasi! ng rate of period due to AML is about 3 times larger than the increasing one by a mass transfer in their absolute values. The latter implies a mass transfer of dot M_{s}= 3.21 × 10^{-8} M_⊙ y^{-1} from the less massive secondary to the primary. The BV light curves with the latest Wilson-Devinney binary code were analyzed for two separate models of 8200K and 7000K as the photospheric temperature of the primary component. Both models confirm that XZ CMi is truly a near-contact binary with a less massive secondary completely filling Roche lobe and a primary inside the inner Roche lobe and there is a third-light corresponding to about 15-17% of the total system light. However, the third-light source can not be the same as the third-body suggested from the period study. At the present, however, we can not determine which one between two models is better fitted to the observations because of a negligible difference of sum (O-C)^2 between them. The diversity of mass ratios, with which previous investigators were in

No variations in transit times for Qatar-1 b

NASA Astrophysics Data System (ADS)

Maciejewski, G.; Fernández, M.; Aceituno, F. J.; Ohlert, J.; Puchalski, D.; Dimitrov, D.; Seeliger, M.; Kitze, M.; Raetz, St.; Errmann, R.; Gilbert, H.; Pannicke, A.; Schmidt, J.-G.; Neuhäuser, R.

2015-05-01

Aims: The transiting hot-Jupiter planet Qatar-1 b exhibits variations in transit times that could be perturbative. A hot Jupiter with a planetary companion on a nearby orbit would constitute an unprecedented planetary configuration, which is important for theories of the formation and evolution of planetary systems. We performed a photometric follow-up campaign to confirm or refute transit timing variations. Methods: We extend the baseline of transit observations by acquiring 18 new transit light curves acquired with 0.6-2.0 m telescopes. These photometric time series, together with data available in the literature, were analyzed in a homogenous way to derive reliable transit parameters and their uncertainties. Results: We show that the dataset of transit times is consistent with a linear ephemeris leaving no hint of any periodic variations with a range of 1 min. We find no compelling evidence of a close-in planetary companion to Qatar-1 b. This finding is in line with a paradigm that hot Jupiters are not components of compact multiplanetary systems. Based on dynamical simulations, we place tighter constraints on the mass of any fictitious nearby planet in the system. Furthermore, new transit light curves allowed us to redetermine system parameters with better precision than reported in previous studies. Our values generally agree with previous determinations. Partly based on (1) data collected with telescopes at the Rozhen National Astronomical Observatory and (2) observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University.Tables of light curve data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A109

Effects of Light and Temperature on the Association between Zea mays and Spirillum lipoferum1

PubMed Central

Albrecht, Stephan L.; Okon, Yaacov; Burris, Robert H.

1977-01-01

Zea mays was grown on a low N nutrient solution under 16 conditions of light and temperature in a crossed-gradient room in an attempt to determine whether or not variation in climatic conditions influences N2 fixation by the association between maize and Spirillum lipoferum. Temperatures were 28, 32, 36, and 40 C and 10 C lower at night; light intensities were 500, 1,250, 2,400, and 3,000 ft-c. Plants harvested after 94 days showed no significant benefit from association with S. lipoferum either in dry weight production or in total N content; variations in temperature and light had only a small influence on N2 fixation under the conditions tested. Measurements of total N, together with designated assumptions, indicated that less than the equivalent of 0.5 kilogram of N was fixed/hectare during the entire growing period by the maize-S. lipoferum association. Rates of C2H2 reduction by replicate root samples generally were low and variable and did not correlate with the measurements of total N. PMID:16660131

Photometric light curves for ten rapidly rotating stars in Alpha Persei, the Pleiades, and the field

NASA Technical Reports Server (NTRS)

Prosser, Charles F.; Schild, Rudolph E.; Stauffer, John R.; Jones, Burton F.

1993-01-01

We present the results from a photometric monitoring program of ten rapidly rotating stars observed during 1991 using the FLWO 48-in. telescope. Brightness variations for an additional six cluster stars observed with the Lick 40-in. telescope are also given. The periods and light curves for seven Alpha Persei members, two Pleiades members, and one naked T Tauri field star are reported.

Leaf age dependent changes in within-canopy variation in leaf functional traits: a meta-analysis

PubMed Central

Niinemets, Ülo

2018-01-01

Within-canopy variation in leaf structural and photosynthetic characteristics is a major means by which whole canopy photosynthesis is maximized at given total canopy nitrogen. As key acclimatory modifications, leaf nitrogen content (NA) and photosynthetic capacity (AA) per unit area increase with increasing light availability in the canopy and these increases are associated with increases in leaf dry mass per unit area (MA) and/or nitrogen content per dry mass and/or allocation. However, leaf functional characteristics change with increasing leaf age during leaf development and aging, but the importance of these alterations for within-canopy trait gradients is unknown. I conducted a meta-analysis based on 71 canopies that were sampled at different time periods or, in evergreens, included measurements for different-aged leaves to understand how within-canopy variations in leaf traits (trait plasticity) depend on leaf age. The analysis demonstrated that in evergreen woody species, MA and NA plasticity decreased with increasing leaf age, but the change in AA plasticity was less suggesting a certain re-acclimation of AA to altered light. In deciduous woody species, MA and NA gradients in flush-type species increased during leaf development and were almost invariable through the rest of the season, while in continuously leaf-forming species, trait gradients increased constantly with increasing leaf age. In forbs, NA plasticity increased, while in grasses, NA plasticity decreased with increasing leaf age, reflecting life form differences in age-dependent changes in light availability and in nitrogen resorption for growth of generative organs. Although more work is needed to improve the coverage of age-dependent plasticity changes in some plant life forms, I argue that the age-dependent variation in trait plasticity uncovered in this study is large enough to warrant incorporation in simulations of canopy photosynthesis through the growing period. PMID:27033356

Artificial light at night disrupts sleep in female great tits (Parus major) during the nestling period, and is followed by a sleep rebound.

PubMed

Raap, Thomas; Pinxten, Rianne; Eens, Marcel

2016-08-01

Artificial light at night has been linked to a wide variety of physiological and behavioural consequences in humans and animals. Given that little is known about the impact of light pollution on sleep in wild animals, we tested how experimentally elevated light levels affected sleep behaviour of female songbirds rearing 10 day old chicks. Using a within-subject design, individual sleep behaviour was observed over three consecutive nights in great tits (Parus major), with females sleeping in a natural dark situation on the first and third night, whereas on the second night they were exposed to a light-emitting diode (1.6 lux). Artificial light in the nest box dramatically and significantly affected sleep behaviour, causing females to fall asleep later (95 min; while entry time was unaffected), wake up earlier (74 min) and sleep less (56%). Females spent a greater proportion of the night awake and the frequency of their sleep bouts decreased, while the length of their sleep bouts remained equal. Artificial light also increased begging of chicks at night, which may have contributed to the sleep disruption in females or vice versa. The night following the light treatment, females slept 25% more compared to the first night, which was mainly achieved by increasing the frequency of sleep bouts. Although there was a consistent pattern in how artificial light affected sleep, there was also large among-individual variation in how strongly females were affected. When comparing current results with a similar experiment during winter, our results highlight differences in effects between seasons and underscore the importance of studying light pollution during different seasons. Our study shows that light pollution may have a significant impact on sleep behaviour in free-living animals during the reproductive season, which may provide a potential mechanism by which artificial light affects fitness. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photonic light-trapping versus Lambertian limits in thin film silicon solar cells with 1D and 2D periodic patterns.

PubMed

Bozzola, Angelo; Liscidini, Marco; Andreani, Lucio Claudio

2012-03-12

We theoretically investigate the light-trapping properties of one- and two-dimensional periodic patterns etched on the front surface of c-Si and a-Si thin film solar cells with a silver back reflector and an anti-reflection coating. For each active material and configuration, absorbance A and short-circuit current density Jsc are calculated by means of rigorous coupled wave analysis (RCWA), for different active materials thicknesses in the range of interest of thin film solar cells and in a wide range of geometrical parameters. The results are then compared with Lambertian limits to light-trapping for the case of zero absorption and for the general case of finite absorption in the active material. With a proper optimization, patterns can give substantial absorption enhancement, especially for 2D patterns and for thinner cells. The effects of the photonic patterns on light harvesting are investigated from the optical spectra of the optimized configurations. We focus on the main physical effects of patterning, namely a reduction of reflection losses (better impedance matching conditions), diffraction of light in air or inside the cell, and coupling of incident radiation into quasi-guided optical modes of the structure, which is characteristic of photonic light-trapping.

NIMBUS-7 SBUV (Solar Backscatter Ultraviolet) observations of solar UV spectral irradiance variations caused by solar rotation and active-region evolution for the period November 7, 1978 - November 1, 1980

NASA Technical Reports Server (NTRS)

Heath, D. F.; Repoff, T. P.; Donnelly, R. F.

1984-01-01

Observations of temporal variations of the solar UV spectral irradiance over several days to a few weeks in the 160-400 nm wavelength range are presented. Larger 28-day variations and a second episode of 13-day variations occurred during the second year of measurements. The thirteen day periodicity is not a harmonic of the 28-day periodicity. The 13-day periodicity dominates certain episodes of solar activity while others are dominated by 28-day periods accompanied by a week 14-day harmonic. Techniques for removing noise and long-term trends are described. Time series analysis results are presented for the Si II lines near 182 nm, the Al I continuum in the 190 nm to 205 nm range, the Mg I continuum in the 210 nm to 250 nm range, the MgII H & K lines at 280 nm, the Mg I line at 285 nm, and the Ca II K & H lines at 393 and 397 nm.

Long-term studies with the Ariel-5 asm. 1: Her X-1, Vela X-1 and Cen X-3. [periodic variations

NASA Technical Reports Server (NTRS)

Holt, S. S.; Kaluzienski, L. J.; Boldt, E. A.; Serlemitsos, P. J.

1978-01-01

Twelve hundred days of 3-6 keV X-ray data from Her X-1, Vela X-1 and Cen X-3 accumulated with the Ariel-5 all-sky monitor are interrogated. The binary periodicities of all three can be clearly observed, as can the approximately 35-d variation of Her X-1, for which we can refine the period to 34.875 plus or minus .030-d. No such longer-term periodicity less than 200-d is observed from Vela X-1. The 26.6-d low-state recurrence period for Cen X-3 previously suggested is not observed, but a 43.0-d candidate periodicity is found which may be consistent with the precession of an accretion disk in that system. The present results are illustrative of the long-term studies which can be performed on approximately 50 sources over a temporal base which will ultimately extend to at least 1800 days.

Assessing non-linear variation of temperature and precipitation for different growth periods of maize and their impacts on phenology in the Midwest of Jilin Province, China

NASA Astrophysics Data System (ADS)

Guo, Enliang; Zhang, Jiquan; Wang, Yongfang; Alu, Si; Wang, Rui; Li, Danjun; Ha, Si

2018-05-01

In the past two decades, the regional climate in China has undergone significant change, resulting in crop yield reduction and complete failure. The goal of this study is to detect the variation of temperature and precipitation for different growth periods of maize and assess their impact on phenology. The daily meteorological data in the Midwest of Jilin Province during 1960-2014 were used in the study. The ensemble empirical mode decomposition method was adopted to analyze the non-linear trend and fluctuation in temperature and precipitation, and the sensitivity of the length of the maize growth period to temperature and precipitation was analyzed by the wavelet cross-transformation method. The results show that the trends of temperature and precipitation change are non-linear for different growth periods of maize, and the average temperature in the sowing-jointing stage was different from that in the other growth stages, showing a slight decrease trend, while the variation amplitude of maximum temperature is smaller than that of the minimum temperature. This indicates that the temperature difference between day and night shows a gradually decreasing trend. Precipitation in the growth period also showed a decreasing non-linear trend, while the inter-annual variability with period of quasi-3-year and quasi-6-year dominated the variation of temperature and precipitation. The whole growth period was shortened by 10.7 days, and the sowing date was advanced by approximately 11 days. We also found that there was a significant resonance period among temperature, precipitation, and phenology. Overall, a negative correlation between phenology and temperature is evident, while a positive correlation with precipitation is exhibited. The results illustrate that the climate suitability for maize has reduced over the past decades.

Optimizing LED lighting for space plant growth unit: Joint effects of photon flux density, red to white ratios and intermittent light pulses.

PubMed

Avercheva, O V; Berkovich, Yu A; Konovalova, I O; Radchenko, S G; Lapach, S N; Bassarskaya, E M; Kochetova, G V; Zhigalova, T V; Yakovleva, O S; Tarakanov, I G

2016-11-01

The aim of this work were to choose a quantitative optimality criterion for estimating the quality of plant LED lighting regimes inside space greenhouses and to construct regression models of crop productivity and the optimality criterion depending on the level of photosynthetic photon flux density (PPFD), the proportion of the red component in the light spectrum and the duration of the duty cycle (Chinese cabbage Brassica сhinensis L. as an example). The properties of the obtained models were described in the context of predicting crop dry weight and the optimality criterion behavior when varying plant lighting parameters. Results of the fractional 3-factor experiment demonstrated the share of the PPFD level participation in the crop dry weight accumulation was 84.4% at almost any combination of other lighting parameters, but when PPFD value increased up to 500µmol m -2 s -1 the pulse light and supplemental light from red LEDs could additionally increase crop productivity. Analysis of the optimality criterion response to variation of lighting parameters showed that the maximum coordinates were the following: PPFD = 500µmol m -2 s -1 , about 70%-proportion of the red component of the light spectrum (PPFD LEDred /PPFD LEDwhite = 1.5) and the duty cycle with a period of 501µs. Thus, LED crop lighting with these parameters was optimal for achieving high crop productivity and for efficient use of energy in the given range of lighting parameter values. Copyright © 2016 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Diurnal variations of Titan

NASA Astrophysics Data System (ADS)

Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

2009-04-01

We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

V1494 Aql: Eclipsing Fast Nova with an Unusual Orbital Light Curve

NASA Astrophysics Data System (ADS)

Kato, Taichi; Ishioka, Ryoko; Uemura, Makoto; Starkey, Donn R.; Krajci, Tom

2004-03-01

We present the time-resolved photometry of V1494 Aql (Nova Aql 1999 No. 2) between 2001 November and 2003 June. The object is confirmed to be an eclipsing nova with a period of 0.1346138(2)d. The eclipses were present in all observed epochs. The orbital light curve shows a rather unusual profile, consisting of a bump-like feature at phase 0.6-0.7 and a dip-like feature at phase 0.2-0.4. These features were probably persistently present in all available observations between 2001 and 2003. A period analysis outside of the eclipses has confirmed that these variations have a period common to the orbital period, and are unlikely to be interpreted as superhumps. We suspect that the structure (probably in the accretion disk) fixed in the binary rotational frame is somehow responsible for this feature.

The ultraviolet variations of iota Cas

NASA Technical Reports Server (NTRS)

Molnar, M. R.; Mallama, A. D.; Soskey, D. G.; Holm, A. V.

1976-01-01

The Ap variable star iota Cas was observed with the photometers on OAO-2 covering the spectral range 1430-4250 A. The ultraviolet light curves show a double wave with primary minimum and maximum at phase ? 0.00 and 0.35, respectively. Secondary minimum light is at phase ? 0.65 with secondary maximum at phase ? 0.85. The light curves longward of 3150 A vary in opposition to those shortward of this 'null region'. Ground-based coude spectra show that the Fe II and Cr II line strengths have a double-wave variation such that maximum strength occurs at minimum ultraviolet light. We suggest that the strong ultraviolet opacities due to photoionization and line blanketing by these metals may cause the observed photometric variations. We have also constructed an oblique-rotator model which shows iron and chromium lying in a great circle band rather than in circular spots.

Physiological responses to daily light exposure

NASA Astrophysics Data System (ADS)

Yang, Yefeng; Yu, Yonghua; Yang, Bo; Zhou, Hong; Pan, Jinming

2016-04-01

Long daylength artificial light exposure associates with disorders, and a potential physiological mechanism has been proposed. However, previous studies have examined no more than three artificial light treatments and limited metabolic parameters, which have been insufficient to demonstrate mechanical responses. Here, comprehensive physiological response curves were established and the physiological mechanism was strengthened. Chicks were illuminated for 12, 14, 16, 18, 20, or 22 h periods each day. A quadratic relationship between abdominal adipose weight (AAW) and light period suggested that long-term or short-term light exposure could decrease the amount of AAW. Quantitative relationships between physiological parameters and daily light period were also established in this study. The relationships between triglycerides (TG), cholesterol (TC), glucose (GLU), phosphorus (P) levels and daily light period could be described by quadratic regression models. TG levels, AAW, and BW positively correlated with each other, suggesting long-term light exposure significantly increased AAW by increasing TG thus resulting in greater BW. A positive correlation between blood triiodothyronine (T3) levels and BW suggested that daily long-term light exposure increased BW by thyroid hormone secretion. Though the molecular pathway remains unknown, these results suggest a comprehensive physiological mechanism through which light exposure affects growth.

Comparative Phenotypical and Molecular Analyses of Arabidopsis Grown under Fluorescent and LED Light

PubMed Central

Seiler, Franka; Soll, Jürgen; Bölter, Bettina

2017-01-01

Comparative analyses of phenotypic and molecular traits of Arabidopsis thaliana grown under standardised conditions is still a challenge using climatic devices supplied with common light sources. These are in most cases fluorescent lights, which have several disadvantages such as heat production at higher light intensities, an invariable spectral output, and relatively rapid “ageing”. This results in non-desired variations of growth conditions and lowers the comparability of data acquired over extended time periods. In this study, we investigated the growth behaviour of Arabidopsis Col0 under different light conditions, applying fluorescent compared to LED lamps, and we conducted physiological as well as gene expression analyses. By changing the spectral composition and/or light intensity of LEDs we can clearly influence the growth behaviour of Arabidopsis and thereby study phenotypic attributes under very specific light conditions that are stable and reproducible, which is not necessarily given for fluorescent lamps. By using LED lights, we can also roughly mimic the sun light emission spectrum, enabling us to study plant growth in a more natural-like light set-up. We observed distinct growth behaviour under the different light regimes which was reflected by physiological properties of the plants. In conclusion, LEDs provide variable emission spectra for studying plant growth under defined, stable light conditions. PMID:28608805

UV Chromospheric Activity in Cool, Short-Period Contact Binaries

NASA Technical Reports Server (NTRS)

Hrivnak, Bruce J.

2000-01-01

We have completed our analysis of the IUE spectra of the short-period contact binary OO Aql. OO Aql is a rare W UMa-type eclipsing binary in which the two solar-type stars may have only recently evolved into contact. The binary has an unusually high mass ratio (0.84), and a relatively long orbital period (0.506 d) for its spectral type (mid-G). Twelve ultraviolet spectra of OO Aql were obtained in 1988 with the IUE satellite, including a series of consecutive observations that cover nearly a complete orbital cycle. Chromospheric activity is studied by means of the Mg II h+k emission at 2800 A. The Mg II emission is found to vary, even when the emission is normalized to the adjacent continuum flux. This variation may be correlated with orbital phase in the 1988 observations. It also appears that the normalized Mg H emission varies with time, as seen in spectra obtained at two different epochs in 1988 and when compared with two spectra obtained several years earlier. The level of chromospheric activity in OO Aql is less than that of other W UMa-type binaries of similar colors, but this is attributed to its early stage of contact binary evolution. Ultraviolet light curves were composed from measurements of the ultraviolet continuum in the spectra. These were analyzed along with visible light curves of OO Aql to determine the system parameters. The large wavelength range in the light curves enabled a well-constrained fit to a cool spot in the system. A paper on these results is scheduled for publication in the February 2001 issue of the Astronomical Journal.

Measures of Light in Studies on Light-Driven Plant Plasticity in Artificial Environments

PubMed Central

Niinemets, Ülo; Keenan, Trevor F.

2012-01-01

Within-canopy variation in light results in profound canopy profiles in foliage structural, chemical, and physiological traits. Studies on within-canopy variations in key foliage traits are often conducted in artificial environments, including growth chambers with only artificial light, and greenhouses with and without supplemental light. Canopy patterns in these systems are considered to be representative to outdoor conditions, but in experiments with artificial and supplemental lighting, the intensity of artificial light strongly deceases with the distance from the light source, and natural light intensity in greenhouses is less than outdoors due to limited transmittance of enclosure walls. The implications of such changes in radiation conditions on canopy patterns of foliage traits have not yet been analyzed. We developed model-based methods for retrospective estimation of distance vs. light intensity relationships, for separation of the share of artificial and natural light in experiments with combined light and for estimation of average enclosure transmittance, and estimated daily integrated light at the time of sampling (Qint,C), at foliage formation (Qint,G), and during foliage lifetime (Qint,av). The implications of artificial light environments were analyzed for altogether 25 studies providing information on within-canopy gradients of key foliage traits for 70 species × treatment combinations. Across the studies with artificial light, Qint,G for leaves formed at different heights in the canopy varied from 1.8- to 6.4-fold due to changing the distance between light source and growing plants. In experiments with combined lighting, the share of natural light at the top of the plants varied threefold, and the share of natural light strongly increased with increasing depth in the canopy. Foliage nitrogen content was most strongly associated with Qint,G, but photosynthetic capacity with Qint,C, emphasizing the importance of explicit description of light

Metabolism variation and better storability of dark- versus light-coloured soybean (Glycine max L. Merr.) seeds.

PubMed

Liu, Jiang; Qin, Wen-Ting; Wu, Hai-Jun; Yang, Cai-Qiong; Deng, Jun-Cai; Iqbal, Nasir; Liu, Wei-Guo; Du, Jun-Bo; Shu, Kai; Yang, Feng; Wang, Xiao-Chun; Yong, Tai-Wen; Yang, Wen-Yu

2017-05-15

The effects of storage duration on the seed germination and metabolite profiling of soybean seeds with five different coloured coats were studied. Their germination, constituents and transcript expressions of isoflavones and free fatty acids (FFAs) were compared using chromatographic metabolomic profiling and transcriptome sequencing. The seed water content was characterized using nuclear magnetic resonance (NMR) relaxometry. Results showed that dark-coloured seeds were less inactivated than light-coloured seeds. The aglycone and β-glucoside concentrations of upstream constituents increased significantly, whereas the acetylglucosides and malonylglucosides of downstream constituents decreased with an increase in the storage period. FFAs increased considerably in the soybean seeds as a result of storage. These results indicate that dark-coloured soybean seeds have better storability than light-coloured seeds, and seed water content plays a role in seed inactivation. It was concluded that there are certain metabolic regularities that are associated with different coloured seed coats of soybeans under storage conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nocturnal illumination maintains reproductive function and simulates the period-lengthening effect of constant light in the mature male Djungarian hamster (Phodopus sungorus)

NASA Technical Reports Server (NTRS)

Ferraro, J. S.

1990-01-01

Mature male Djungarian hamsters (Phodopus sungorus) were placed in individual light-tight, sound attenuated chambers and exposed to one of four lighting conditions for a duration of approximately seven weeks. The four lighting conditions were: constant light (LL); constant dark (DD); feedback lighting (LDFB; a condition that illuminates the cage in response to locomotor activity); or a feedback lighting neighbor control (LDFB NC; the animal receives the same light pattern as a paired animal in feedback lighting, but has no control over it). Exposure of hamsters to LL or LDFB produced significantly and similarly longer free-running periods of the locomotor activity rhythm than exposure of animals to DD. Hamsters exposed to LDFB NC did not free-run or entrain, but rather displayed "relative coordination". The paired testes and sex accessory glands weights suggest that in the Djungarian hamster, LL and LDFB exposed animals maintained reproductive function, whereas DD exposed animals did not. Animals exposed to LDFB NC had intermediate paired testes weights. Since several previous studies have demonstrated that short pulses of light, which are coincident with the subjective night, are photostimulatory, it is not surprising that LDFB maintained reproductive function in the mature Djungarian hamster. Feedback lighting, however, has been shown to be an insufficient stimulus to maintain reproductive function of mature male and female Syrian hamsters, and to the reproductive maturation of immature Djungarian hamsters. The results suggest that there may be slight, but significant differences in the way these two species interpret photoperiod, as well as a developmental change in the photoperiodic response of Djungarian hamsters.

Joint analysis of short-period variations of ionospheric parameters in Siberia and the Far East and processes of the tropical cyclogenesis

NASA Astrophysics Data System (ADS)

Chernigovskaya, M. A.; Kurkin, V. I.; Orlov, I. I.; Sharkov, E. A.; Pokrovskaya, I. V.

2009-04-01

In this work a possibility of manifestation of strong meteorological disturbances in the Earth lower atmosphere in variations of ionospheric parameters in the zone remote from the disturbance source has been studied. The spectral analysis of short-period variations (about ten minutes, hours) in maximum observed frequencies (MOF) of one-skip signals of oblique sounding has been carried out. These variations were induced by changes in the upper atmosphere parameters along the Magadan-Irkutsk oblique-incidence sounding path on the background of diurnal variations in the parameter under study. Data on MOF measurements with off-duty factor approximately 5 min in equinoxes (September, March) of 2005-2007 were used. The analysis was made using the improved ISTP-developed technique of determining periodicities in time series. The increase of signal spectrum energy at certain frequencies is interpreted as manifestation of traveling ionospheric disturbances (TID) associated with propagation of internal gravity waves in the atmosphere. The analysis revealed TIDs of temporal scales under consideration. The question concerning localization of possible sources of revealed disturbances is discussed. Troposphere meteorological disturbances giant in their energy (tropical cyclones, typhoon) are considered as potential sources of observable TIDs. The needed information on tropical cyclones that occurred in the north area of the Indian Ocean, south-west and central areas of the Pacific Ocean in 2005-2007 is taken from the electron base of satellite data on the global tropical cyclogenesis "Global-TC" (ISR RAS). In order to effectively separate disturbances associated with the magnetospheric-ionospheric interaction and disturbances induced by the lower atmosphere influence on the upper atmosphere, we analyze the tropical cyclogenesis events that occurred in quiet helio-geomagnetic conditions. The study was supported by the Program of RAS Presidium N 16 (Part 3) and the RFBR Grant N 08-05-00658.

Rotational Periods and Starspot Activity of Young Solar-Type Dwarfs in the Open Cluster IC 4665

NASA Technical Reports Server (NTRS)

Allain, S.; Bouvier, J.; Prosser, C.; Marschall, L. A.; Laaksonen, B. D.

1995-01-01

We present the results of a V-band photometric monitoring survey of 15 late-type dwarfs in the young open cluster IC 4665. Low-amplitude periodic light variations are found for 8 stars and ascribed to the modulation by starspots that cover typically a few percent of the stellar disk. Periods range from 0.6 to 3.7 d, translating to equatorial velocities between 13 and 93 km/s. That no period longer than 4 d was detected suggests a relative paucity of extremely slow rotators (V(sub eq) much less than 10 km/s) among late-type dwarfs in IC 4665. The fractional number of slow rotators in IC 4665 is similar to that of Alpha Per cluster, suggesting that IC 4665 is close in age to Alpha Per (approx. 50 Myr).

Contrasting variations in the surface layer structure between the convective and non-convective periods in the summer monsoon season for Bangalore location during PRWONAM

NASA Astrophysics Data System (ADS)

Reddy, N. Narendra; Rao, Kusuma G.

2018-01-01

An attempt has been made here to examine the contrasting variations in mean surface layer parameters including surface fluxes, and in surface layer stability between the convective and non-convective periods in the southwest monsoon season for the Bangalore experiment location (12.54° N, 77.22° E). The micrometeorological measurements analysed during 2009 and 2010 are from the instrumentation network established during the programme, "Prediction of Regional Weather using Observational meso-Network and Atmospheric Modelling (PRWONAM)". The Short Wave (SW) radiative flux at the surface is observed to be respectively at 799 ± 188 Wm-2 (772 ± 195 Wm-2) and 436 ± 113 Wm-2 (257 ± 101 Wm-2) at 12:00 LT (Local Time, UTC+05:30) during the non-convective and convective periods in 2009 (2010). The significant difference in SW radiative flux is due to the difference of cloud cover between the non-convective and convective periods. This significant reduction of 515 W m-2 at 12:00 LT in SW radiative flux caused maximum cooling in skin temperature (air temperature) by 6.2 °C (3.8 °C) at 12:00 LT (18:30 LT) from 30.8 ± 3.9 °C (27.1 ± 1.4 °C) in the non-convective period. The impact of convection on soil temperature is observed up to 0.2 m deep. The diurnal amplitudes in composites of air temperature are 8.4 °C (8.4 °C) and 5.7 °C (4.7 °C) during the non-convective and convective periods respectively in 2009 (2010); and the amplitudes in relative humidity are 41.5% (39.7%) and 29% (22.8%). Low wind speeds prevailed 63.4% of the time, all through the day and night, in the monsoon season. The diurnal variations in wind speed during the convective period showed higher variability than in non-convective period. The momentum flux varied in accordance with the strength of the wind speed during the monsoon seasons of both the years 2009 and 2010. The peak sensible heat flux in the convective period is noted to be smaller than that in the non-convective period by 128 W m-2

Variation of Transaminases, HCV-RNA Levels and Th1/Th2 Cytokine Production during the Post-Partum Period in Pregnant Women with Chronic Hepatitis C

PubMed Central

Ruiz-Extremera, Ángeles; Muñoz-Gámez, José Antonio; Abril-Molina, Ana; Salmerón-Ruiz, María Angustias; Muñoz-de-Rueda, Paloma; Pavón-Castillero, Esther José; Quiles-Pérez, Rosa; Carazo, Ángel; Gila, Ana; Jimenez-Ruiz, Sergio Manuel; Casado, Jorge; Martín, Ana Belén; Sanjuán-Núñez, Laura; Ocete-Hita, Esther; Viota, Julián López; León, Josefa; Salmerón, Javier

2013-01-01

This study analyses the evolution of liver disease in women with chronic hepatitis C during the third trimester of pregnancy and the post-partum period, as a natural model of immune modulation and reconstitution. Of the 122 mothers recruited to this study, 89 were HCV-RNA+ve/HIV-ve and 33 were HCV-RNA-ve/HIV-ve/HCVantibody+ve and all were tested during the third trimester of pregnancy, at delivery and post-delivery. The HCV-RNA+ve mothers were categorized as either Type-A (66%), with an increase in ALT levels in the post-partum period (>40 U/L; P<0.001) or as Type-B (34%), with no variation in ALT values. The Type-A mothers also presented a significant decrease in serum HCV-RNA levels in the post-delivery period (P<0.001) and this event was concomitant with an increase in Th1 cytokine levels (INFγ, P = 0.04; IL12, P = 0.01 and IL2, P = 0.01). On the other hand, the Type-B mothers and the HCV-RNA-ve women presented no variations in either of these parameters. However, they did present higher Th1 cytokine levels in the partum period (INFγ and IL2, P<0.05) than both the Type-A and the HCV-RNA-ve women. Cytokine levels at the moment of delivery do not constitute a risk factor associated with HCV vertical transmission. It is concluded that differences in the ALT and HCV-RNA values observed in HCV-RNA+ve women in the postpartum period might be due to different ratios of Th1 cytokine production. In the Type-B women, the high partum levels of Th1 cytokines and the absence of post-partum variation in ALT and HCV-RNA levels may be related to permanent Th1 cytokine stimulation. PMID:24130726

Diel Variation of Biogenic Volatile Organic Compound Emissions- A field Study in the Sub, Low and High Arctic on the Effect of Temperature and Light

PubMed Central

Lindwall, Frida; Faubert, Patrick; Rinnan, Riikka

2015-01-01

Many hours of sunlight in the midnight sun period suggest that significant amounts of biogenic volatile organic compounds (BVOCs) may be released from arctic ecosystems during night-time. However, the emissions from these ecosystems are rarely studied and limited to point measurements during daytime. We measured BVOC emissions during 24-hour periods in the field using a push-pull chamber technique and collection of volatiles in adsorbent cartridges followed by analysis with gas chromatography- mass spectrometry. Five different arctic vegetation communities were examined: high arctic heaths dominated by Salix arctica and Cassiope tetragona, low arctic heaths dominated by Salix glauca and Betula nana and a subarctic peatland dominated by the moss Warnstorfia exannulata and the sedge Eriophorum russeolum. We also addressed how climate warming affects the 24-hour emission and how the daytime emissions respond to sudden darkness. The emissions from the high arctic sites were lowest and had a strong diel variation with almost no emissions during night-time. The low arctic sites as well as the subarctic site had a more stable release of BVOCs during the 24-hour period with night-time emissions in the same range as those during the day. These results warn against overlooking the night period when considering arctic emissions. During the day, the quantity of BVOCs and the number of different compounds emitted was higher under ambient light than in darkness. The monoterpenes α-fenchene, α -phellandrene, 3-carene and α-terpinene as well as isoprene were absent in dark measurements during the day. Warming by open top chambers increased the emission rates both in the high and low arctic sites, forewarning higher emissions in a future warmer climate in the Arctic. PMID:25897519

Decadal period external magnetic field variations determined via eigenanalysis

NASA Astrophysics Data System (ADS)

Shore, R. M.; Whaler, K. A.; Macmillan, S.; Beggan, C.; Velímský, J.; Olsen, N.

2016-06-01

We perform a reanalysis of hourly mean magnetic data from ground-based observatories spanning 1997-2009 inclusive, in order to isolate (after removal of core and crustal field estimates) the spatiotemporal morphology of the external fields important to mantle induction, on (long) periods of months to a full solar cycle. Our analysis focuses on geomagnetically quiet days and middle to low latitudes. We use the climatological eigenanalysis technique called empirical orthogonal functions (EOFs), which allows us to identify discrete spatiotemporal patterns with no a priori specification of their geometry -- the form of the decomposition is controlled by the data. We apply a spherical harmonic analysis to the EOF outputs in a joint inversion for internal and external coefficients. The results justify our assumption that the EOF procedure responds primarily to the long-period external inducing field contributions. Though we cannot determine uniquely the contributory source regions of these inducing fields, we find that they have distinct temporal characteristics which enable some inference of sources. An identified annual-period pattern appears to stem from a north-south seasonal motion of the background mean external field distribution. Separate patterns of semiannual and solar-cycle-length periods appear to stem from the amplitude modulations of spatially fixed background fields.

AMERICAN STANDARD GUIDE FOR SCHOOL LIGHTING.

ERIC Educational Resources Information Center

Illuminating Engineering Society, New York, NY.

THIS IS A GUIDE FOR SCHOOL LIGHTING, DESIGNED FOR EDUCATORS AS WELL AS ARCHITECTS. IT MAKES USE OF RECENT RESEARCH, NOTABLY THE BLACKWELL REPORT ON EVALUATION OF VISUAL TASKS. THE GUIDE BEGINS WITH AN OVERVIEW OF CHANGING GOALS AND NEEDS OF SCHOOL LIGHTING, AND A TABULATION OF COMMON CLASSROOM VISUAL TASKS THAT REQUIRE VARIATIONS IN LIGHTING.…

Spitzer Space Telescope Mid-IR Light Curves of Neptune

NASA Technical Reports Server (NTRS)

Stauffer, John; Marley, Mark S.; Gizis, John E.; Rebull, Luisa; Carey, Sean J.; Krick, Jessica; Ingalls, James G.; Lowrance, Patrick; Glaccum, William; Kirkpatrick, J. Davy;

Direct measurement of light waves.

PubMed

Goulielmakis, E; Uiberacker, M; Kienberger, R; Baltuska, A; Yakovlev, V; Scrinzi, A; Westerwalbesloh, Th; Kleineberg, U; Heinzmann, U; Drescher, M; Krausz, F

2004-08-27

The electromagnetic field of visible light performs approximately 10(15) oscillations per second. Although many instruments are sensitive to the amplitude and frequency (or wavelength) of these oscillations, they cannot access the light field itself. We directly observed how the field built up and disappeared in a short, few-cycle pulse of visible laser light by probing the variation of the field strength with a 250-attosecond electron burst. Our apparatus allows complete characterization of few-cycle waves of visible, ultraviolet, and/or infrared light, thereby providing the possibility for controlled and reproducible synthesis of ultrabroadband light waveforms.

The influence of moonlight and lunar periodicity on the efficacy of CDC light trap in sampling Phlebotomus (Larroussius) orientalis Parrot, 1936 and other Phlebotomus sandflies (Diptera: Psychodidae) in Ethiopia.

PubMed

Gebresilassie, Araya; Yared, Solomon; Aklilu, Essayas; Kirstein, Oscar David; Moncaz, Aviad; Tekie, Habte; Balkew, Meshesha; Warburg, Alon; Hailu, Asrat; Gebre-Michael, Teshome

2015-02-15

Phlebotomus orientalis is the main sandfly vector of visceral leishmaniasis in the north and northwest of Ethiopia. CDC light traps and sticky traps are commonly used for monitoring sandfly populations. However, their trapping efficiency is greatly influenced by various environmental factors including moonlight and lunar periodicity. In view of that, the current study assessed the effect of moonlight and lunar periodicity on the performance of light traps in collecting P. orientalis. Trapping of P. orientalis and other Phlebotomus spp. was conducted for 7 months between December 2012 and June 2013 using CDC light traps and sticky traps from peri-domestic and agricultural fields. Throughout the trapping periods, collections of sandfly specimens were carried out for 4 nights per month, totaling 28 trapping nights that coincided with the four lunar phases (viz., first quarter, third quarter, new and full moon) distributed in each month. In total, 13,533 sandflies of eight Phlebotomus species (P. orientalis, P. bergeroti, P. rodhaini, P. duboscqi, P. papatasi, P. martini, P. lesleyae and P. heischi) were recorded. The predominant species was P. orientalis in both trapping sites and by both methods of collection in all lunar phases. A significant difference (P < 0.05) was observed in the mean numbers of P. orientalis and other Phlebotomus spp. caught by CDC light traps among the four lunar phases. The highest mean number (231.13 ± 36.27 flies/trap/night) of P. orientalis was collected during the new moon phases, when the moonlight is absent. Fewer sandflies were attracted to light traps during a full moon. However, the number of P. orientalis and the other Phlebotomus spp. from sticky traps did not differ in their density among the four lunar phases (P = 0.122). Results of the current study demonstrated that the attraction and trapping efficiency of CDC light traps is largely influenced by the presence moonlight, especially during a full moon. Therefore

Diel variation in summer habitat use, feeding periodicity, and diet of subyearling Atlantic salmon in the Salmon River Basin, New York

USGS Publications Warehouse

Johnson, James H.

2013-01-01

The habitat use, diet composition, and feeding periodicity of subyearling Atlantic salmon (Salmo salar) was examined during both day and night periods during summer in tributaries of Lake Ontario. The amount of cover used was the major habitat variable that differed between day and night periods in both streams. At night subyearling Atlantic salmon were associated with significantly less cover than during the day. Principal Component Analysis showed that habitat selection of subyearling Atlantic salmon was more pronounced during the day in both streams and that salmon in Orwell Brook exhibited more diel variability in habitat use than salmon in Trout Brook. Subyearling salmon fed primarily from the benthic substrate on baetids, chironomids, and leptocerids. There was a substantial amount of diel variation in diet composition with peak feeding occurring from 0400 h to 0800 h on July 21–22, 2008.

THE ROTATION PERIOD AND LIGHT-CURVE AMPLITUDE OF KUIPER BELT DWARF PLANET 136472 MAKEMAKE (2005 FY9)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heinze, A. N.; DeLahunta, Daniel

Kuiper Belt dwarf planet 136472 Makemake, formerly known as 2005 FY9, is currently the third-largest known object in the Kuiper Belt, after the dwarf planets Pluto and Eris. It is currently second only to Pluto in apparent brightness, due to Eris' much larger heliocentric distance. Makemake shows very little photometric variability, which has prevented confident determination of its rotation period until now. Using extremely precise time-series photometry, we find that the rotation period of Makemake is 7.7710 {+-} 0.0030 hr, where the uncertainty is a 90% confidence interval. An alias period is detected at 11.41 hr, but is determined withmore » approximately 95% confidence not to be the true period. Makemake's 7.77 hr rotation period is in the typical range for Kuiper Belt objects, consistent with Makemake's apparent lack of a substantial satellite to alter its rotation through tides. The amplitude of Makemake's photometric light curve is 0.0286 {+-} 0.0016 mag in V. This amplitude is about 10 times less than Pluto's, which is surprising given the two objects' similar sizes and spectral characteristics. Makemake's photometric variability is instead similar to that of Eris, which is so small that no confident rotation period has yet been determined. It has been suggested that dwarf planets such as Makemake and Eris, both farther from the Sun and colder than Pluto, exhibit lower photometric variability because they are covered with a uniform layer of frost. Such a frost is probably the correct explanation for Eris. However, it may be inconsistent with the spectrum of Makemake, which resembles reddish Pluto more than neutrally colored Eris. Makemake may instead be a more Pluto-like object that we observe at present with a nearly pole-on viewing geometry-a possibility that can be tested with continuing observations over the coming decades.« less

Relativistic Spin-Orbit Heavy Atom on the Light Atom NMR Chemical Shifts: General Trends Across the Periodic Table Explained.

PubMed

Vícha, Jan; Komorovsky, Stanislav; Repisky, Michal; Marek, Radek; Straka, Michal

2018-06-12

The importance of relativistic effects on the NMR parameters in heavy-atom (HA) compounds, particularly the SO-HALA (Spin-Orbit Heavy Atom on the Light Atom) effect on NMR chemical shifts, has been known for about 40 years. Yet, a general correlation between the electronic structure and SO-HALA effect has been missing. By analyzing 1 H NMR chemical shifts of the sixth-period hydrides (Cs-At), we discovered general electronic-structure principles and mechanisms that dictate the size and sign of the SO-HALA NMR chemical shifts. In brief, partially occupied HA valence shells induce relativistic shielding at the light atom (LA) nuclei, while empty HA valence shells induce relativistic deshielding. In particular, the LA nucleus is relativistically shielded in 5d 2 -5d 8 and 6p 4 HA hydrides and deshielded in 4f 0 , 5d 0 , 6s 0 , and 6p 0 HA hydrides. This general and intuitive concept explains periodic trends in the 1 H NMR chemical shifts along the sixth-period hydrides (Cs-At) studied in this work. We present substantial evidence that the introduced principles have a general validity across the periodic table and can be extended to nonhydride LAs. The decades-old question of why compounds with occupied frontier π molecular orbitals (MOs) cause SO-HALA shielding at the LA nuclei, while the frontier σ MOs cause deshielding is answered. We further derive connection between the SO-HALA NMR chemical shifts and Spin-Orbit-induced Electron Deformation Density (SO-EDD), a property that can be obtained easily from differential electron densities and can be represented graphically. SO-EDD provides an intuitive understanding of the SO-HALA effect in terms of the depletion/concentration of the electron density at LA nuclei caused by spin-orbit coupling due to HA in the presence of a magnetic field. Using an analogy between the SO-EDD concept and arguments from classic NMR theory, the complex question of the SO-HALA NMR chemical shifts becomes easily understandable for a wide

Effect of Nanohole Spacing on the Self-Imaging Phenomenon Created by the Three-Dimensional Propagation of Light through Periodic Nanohole Arrays

PubMed Central

Chowdhury, Mustafa H.; Lindquist, Nathan C.; Lesuffleur, Antoine; Oh, Sang-Hyun; Lakowicz, Joseph R.; Ray, Krishanu

2013-01-01

We present a detailed study of the inter-nanohole distance that governs the self-imaging phenomenon created by the three-dimensional propagation of light through periodic nanohole arrays on plasmonic substrates. We used scanning near-field optical microscopy (SNOM) to map the light intensity distributions at various heights above 10×10 nanohole arrays of varying pitch sizes on silver films. Our results suggest the inter-hole spacing has to be greater than the wavelength of the incident light to create the self-imaging phenomenon. We also present Finite-Difference Time-Domain (FDTD) calculations which show qualitative corroboration of our experimental results. Both our experimental and FDTD results show that the self-imaging phenomenon is more pronounced for structures with larger pitch sizes. We believe this self-imaging phenomenon is related to the Talbot imaging effect that has also been modified by a plasmonic component and can potentially be used to provide the basis for a new class of optical microscopes. PMID:24416456

Oscillatory patterns in the light curves of five long-term monitored type 1 active galactic nuclei

NASA Astrophysics Data System (ADS)

Kovačević, Andjelka B.; Pérez-Hernández, Ernesto; Popović, Luka Č.; Shapovalova, Alla I.; Kollatschny, Wolfram; Ilić, Dragana

2018-04-01

New combined data of five well-known type 1 active galactic nuclei (AGNs) are probed with a novel hybrid method in a search for oscillatory behaviour. Additional analysis of artificial light curves obtained from the coupled oscillatory models gives confirmation for detected periods that could have a physical background. We find periodic variations in the long-term light curves of 3C 390.3, NGC 4151 and NGC 5548, and E1821 + 643, with correlation coefficients larger than 0.6. We show that the oscillatory patterns of two binary black hole candidates, NGC 5548 and E1821 + 643, correspond to qualitatively different dynamical regimes of chaos and stability, respectively. We demonstrate that the absence of oscillatory patterns in Arp 102B could be the result of a weak coupling between oscillatory mechanisms. This is the first good evidence that 3C 390.3 and Arp 102B, categorized as double-peaked Balmer line objects, have qualitative different dynamics. Our analysis shows a novelty in the oscillatory dynamical patterns of the light curves of these type 1 AGNs.

Light delivery over extended time periods enhances the effectiveness of photodynamic therapy.

PubMed

Seshadri, Mukund; Bellnier, David A; Vaughan, Lurine A; Spernyak, Joseph A; Mazurchuk, Richard; Foster, Thomas H; Henderson, Barbara W

2008-05-01

The rate of energy delivery is a principal factor determining the biological consequences of photodynamic therapy (PDT). In contrast to conventional high-irradiance treatments, recent preclinical and clinical studies have focused on low-irradiance schemes. The objective of this study was to investigate the relationship between irradiance, photosensitizer dose, and PDT dose with regard to treatment outcome and tumor oxygenation in a rat tumor model. Using the photosensitizer HPPH (2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide), a wide range of PDT doses that included clinically relevant photosensitizer concentrations was evaluated. Magnetic resonance imaging and oxygen tension measurements were done along with the Evans blue exclusion assay to assess vascular response, oxygenation status, and tumor necrosis. In contrast to high-incident laser power (150 mW), low-power regimens (7 mW) yielded effective tumor destruction. This was largely independent of PDT dose (drug-light product), with up to 30-fold differences in photosensitizer dose and 15-fold differences in drug-light product. For all drug-light products, the duration of light treatment positively influenced tumor response. Regimens using treatment times of 120 to 240 min showed marked reduction in signal intensity in T2-weighted magnetic resonance images at both low (0.1 mg/kg) and high (3 mg/kg) drug doses compared with short-duration (6-11 min) regimens. Significantly greater reductions in pO(2) were observed with extended exposures, which persisted after completion of treatment. These results confirm the benefit of prolonged light exposure, identify vascular response as a major contributor, and suggest that duration of light treatment (time) may be an important new treatment variable.

Light Delivery Over Extended Time Periods Enhances the Effectiveness of Photodynamic Therapy

PubMed Central

Seshadri, Mukund; Bellnier, David A.; Vaughan, Lurine A.; Spernyak, Joseph A.; Mazurchuk, Richard; Foster, Thomas H.; Henderson, Barbara W.

2009-01-01

Purpose The rate of energy delivery is a principal factor determining the biological consequences of photodynamic therapy (PDT). In contrast to conventional high irradiance treatments, recent preclinical and clinical studies have focused on low irradiance schemes. The objective of this study was to investigate the relationship between irradiance, photosensitizer dose and PDT dose with regard to treatment outcome and tumor oxygenation in a rat tumor model. Experimental Design Using the photosensitizer HPPH (2-[1-hexyloxyethyl]-2 devinyl pyropheophorbide), a wide range of PDT doses that included clinically relevant photosensitizer concentrations were evaluated. Magnetic resonance imaging (MRI) and oxygen tension measurements were performed along with the Evans blue exclusion assay to assess vascular response, oxygenation status and tumor necrosis. Results In contrast to high incident laser power (150 mW), low power regimens (7 mW) yielded effective tumor destruction. This was largely independent of PDT dose (drug-light product), with up to 30-fold differences in photosensitizer dose and 15-fold differences in drug-light product. For all drug-light products, the duration of light treatment positively influenced tumor response. Regimens utilizing treatment times of 120–240 mins showed marked reduction in signal intensity in T2-weighted MR images at both low (0.1 mg/kg) and high (3 mg/kg) drug doses compared to short duration (6–11 mins) regimens. Significantly greater reductions in pO2 were observed with extended exposures, which persisted after completion of treatment. Conclusions These results confirm the benefit of prolonged light exposure, identify vascular response as a major contributor and suggest that duration of light treatment (time) may be an important new treatment parameter. PMID:18451247

Light-Curve Survey of Jupiter Trojan Asteroids

NASA Astrophysics Data System (ADS)

Duffard, R.; Melita, M.; Ortiz, J. L.; Licandro, J.; Williams, I. P.; Jones, D.

2008-09-01

: the WFC, Isaac Newton Telescope (ING, 2.5m, 7 nights), CAHA (2.2m, 6 nights), CCD direct OSN (1.5m, 6 nights) and CCD direct, JS (CASLEO, 2.15m, 7 nights). From these observations we have constructed the differential photometry light-curves of 15 Trojan asteroids. Plots showing the actual light curves and the quality assessment of our estimation of the rotational period can be downloaded from: http://www.df.uba.ar/users/melita/PICT07/PICT07.ht ml. See table 1 for the main results. In figure 1 we show the known periods of the Trojan asteroids as a function of their size. Some of these data are still of poor quality. It remains to be confirmed the reality of the clustering of small objects at small periods, so, there is a need to improve those rotation rates with reliable standard photometry produced at an instrument of larger aperture. Also, a lack of data for the biggest objects is apparent from this figure. In figure 2 we show a plot of the Rmagnitude amplitude variation as a function of the absolute magnitude. Most of the objects are from the survey of contact binaries by Mann et al. 2007. This plot seems to indicate that the extreme elongations recorded previously are constrained to the largest objects. Our data follows the trend of a negative slope, but given the error-bars involved, it remains to be confirmed if smaller objects tend to be more spherical.

The OmegaWhite Survey for short-period variable stars - IV. Discovery of the warm DQ white dwarf OW J175358.85-310728.9

NASA Astrophysics Data System (ADS)

Macfarlane, S. A.; Woudt, P. A.; Dufour, P.; Ramsay, G.; Groot, P. J.; Toma, R.; Warner, B.; Paterson, K.; Kupfer, T.; van Roestel, J.; Berdnikov, L.; Dagne, T.; Hardy, F.

2017-09-01

We present the discovery and follow-up observations of the second known variable warm DQ white dwarf OW J175358.85-310728.9 (OW J1753-3107). OW J1753-3107 is the brightest of any of the currently known warm or hot DQ and was discovered in the OmegaWhite Survey as exhibiting optical variations on a period of 35.5452 (2) min, with no evidence for other periods in its light curves. This period has remained constant over the last 2 yr and a single-period sinusoidal model provides a good fit for all follow-up light curves. The spectrum consists of a very blue continuum with strong absorption lines of neutral and ionized carbon, a broad He I λ4471 line and possibly weaker hydrogen lines. The C I lines are Zeeman split, and indicate the presence of a strong magnetic field. Using spectral Paschen-Back model descriptions, we determine that OW J1753-3107 exhibits the following physical parameters: Teff = 15 430 K, log (g) = 9.0, log (N(C)/N(He)) = -1.2 and the mean magnetic field strength is Bz =2.1 MG. This relatively low temperature and carbon abundance (compared to the expected properties of hot DQs) is similar to that seen in the other warm DQ SDSS J1036+6522. Although OW J1753-3107 appears to be a twin of SDSS J1036+6522, it exhibits a modulation on a period slightly longer than the dominant period in SDSS J1036+6522 and has a higher carbon abundance. The source of variations is uncertain, but they are believed to originate from the rotation of the magnetic white dwarf.

Stopping light in its tracks

NASA Astrophysics Data System (ADS)

Eggleton, B. J.; Martijn de Sterke, C.; Slusher, R. E.; Krug, Peter A.; Sipe, J. E.

1996-12-01

To control the speed of a light pulse without absorbing its photons, or distorting its shape, is a challenging problem. However, this has been accomplished using fiber gratings, as part of a joint research program of the University of Sydney, the Australian Photonics Research Centre, Lucent Technologies, and the University of Toronto. The gratings are written in the optical fiber's core by directing a UV beam onto it via a periodic phase mask. Through a photochemical process still not well-understood, the periodic intensity pattern burns a permanent index of refraction change in the core.1-2 In our experiments, we use gratings with a period of about 350 nm chosen to reflect light at 1.05 u m and a length of 5.5 cm.3 Because the grating has over 150,000 periods, an index change of only 0.0003 is sufficient to limit the transmission to less than 30 dB on resonance. Essentially no light is transmitted by such a grating at the Bragg resonance; yet a nanometer away, light propagates through as if the grating were absent. As we tune away from resonance, the light's group velocity increases from zero to c/n (where c is the speed of light in a vacuum and n=1.46 is the refractive index of the core of the fiber), leading to a dispersion about 100,000 times larger than that of bare fiber. Gratings can thus slow down a pulse of light, but at the price of tearing it apart.4 At high light intensities a nonlinearly, with the index of refraction increasing with intensity.5 In the center of the pulse, where the intensity is the highest, the index is thus raised the most. Since regions of high index attract light, the nonlinearity acts as a "glue," counteracting the strong dispersive effects of the grating.

Development of a circadian light source

NASA Astrophysics Data System (ADS)

Nicol, David B.; Ferguson, Ian T.

2002-11-01

Solid state lighting presents a new paradigm for lighting - controllability. Certain characteristics of the lighting environment can be manipulated, because of the possibility of using multiple LEDs of different emission wavelengths as the illumination source. This will provide a new, versatile, general illumination source due to the ability to vary the spectral power distribution. New effects beyond the visual may be achieved that are not possible with conventional light sources. Illumination has long been the primary function of lighting but as the lighting industry has matured the psychological aspects of lighting have been considered by designers; for example, choosing a particular lighting distribution or color variation in retail applications. The next step in the evolution of light is to consider the physiological effects of lighting that cause biological changes in a person within the environment. This work presents the development of a source that may have important bearing on this area of lighting. A circadian light source has been developed to provide an illumination source that works by modulating its correlated color temperature to mimic the changes in natural daylight through the day. In addition, this source can cause or control physiological effects for a person illuminated by it. The importance of this is seen in the human circadian rhythm's peak response corresponding to blue light at ~460 nm which corresponds to the primary spectral difference in increasing color temperature. The device works by adding blue light to a broadband source or mixing polychromatic light to mimic the variation of color temperature observed for the Planckian Locus on the CIE diagram. This device can have several applications including: a tool for researchers in this area, a general illumination lighting technology, and a light therapy device.

Differential sorting of the vesicular glutamate transporter 1 into a defined vesicular pool is regulated by light signaling involving the clock gene Period2.

PubMed

Yelamanchili, Sowmya V; Pendyala, Gurudutt; Brunk, Irene; Darna, Mahesh; Albrecht, Urs; Ahnert-Hilger, Gudrun

2006-06-09

Synaptic strength depends on the amount of neurotransmitter stored in synaptic vesicles. The vesicular transmitter content has recently been shown to be directly dependent on the expression levels of vesicular neurotransmitter transporters indicating that the transport capacity of synaptic vesicles is a critical determinant for synaptic efficacy. Using synaptic vesicles prepared from whole brain at different times of the day we now show that the amount of vesicular glutamate transporter (VGLUT) 1 undergoes strong diurnal cycling. VGLUT1 protein levels are high before the start of the light period, decline at noon, increase again before start of the dark period, and decline again at midnight. Mice kept in complete darkness showed within a 24-h period only a single peak of VGLUT1 expression in the middle of the rest phase. In contrast, mice lacking the period gene Period 2, a core component of the circadian clock, did not show any light-cycle-dependent changes of VGLUT1 levels. No other of several synaptic vesicle proteins examined underwent circadian cycling. Circadian cycling of VGLUT1 was not seen when analyzing homogenate or synaptosomes, the starting fraction for vesicle preparation. Circadian cycling of VGLUT1 was also not reflected at the mRNA level. We conclude that nerve terminals are endowed with mechanisms that regulate quantal size by changing the copy number of transporters in synaptic vesicles. A reduced amount of VGLUT1 per vesicle is probably achieved by means of selective sorting controlled by clock genes.

Blue-enriched office light competes with natural light as a zeitgeber.

PubMed

Vetter, Céline; Juda, Myriam; Lang, Dieter; Wojtysiak, Andreas; Roenneberg, Till

2011-09-01

Circadian regulation of human physiology and behavior (eg, body temperature or sleep-timing), depends on the "zeitgeber" light that synchronizes them to the 24-hour day. This study investigated the effect of changing light temperature at the workplace from 4000 Kelvin (K) to 8000 K on sleep-wake and activity-rest behavior. An experimental group (N=27) that experienced the light change was compared with a non-intervention group (N=27) that remained in the 4000 K environment throughout the 5-week study period (14 January to 17 February). Sleep logs and actimetry continuously assessed sleep-wake behavior and activity patterns. Over the study period, the timing of sleep and activity on free days steadily advanced parallel to the seasonal progression of sunrise in the non-intervention group. In contrast, the temporal pattern of sleep and activity in the experimental group remained associated with the constant onset of work. The results suggest that artificial blue-enriched light competes with natural light as a zeitgeber. While subjects working under the warmer light (4000 K) appear to entrain (or synchronize) to natural dawn, the subjects who were exposed to blue-enriched (8000 K) light appear to entrain to office hours. The results confirm that light is the dominant zeitgeber for the human clock and that its efficacy depends on spectral composition. The results also indicate that blue-enriched artificial light is a potent zeitgeber that has to be used with diligence.

QUASI-PERIODICITIES AT YEAR-LIKE TIMESCALES IN BLAZARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandrinelli, A.; Treves, A.; Covino, S.

2016-03-15

We searched for quasi-periodicities on year-like timescales in the light curves of six blazars in the optical—near-infrared bands and we made a comparison with the high energy emission. We obtained optical/NIR light curves from Rapid Eye Mounting photometry plus archival Small and Moderate Aperture Research Telescope System data and we accessed the Fermi light curves for the γ-ray data. The periodograms often show strong peaks in the optical and γ-ray bands, which in some cases may be inter-related. The significance of the revealed peaks is then discussed, taking into account that the noise is frequency dependent. Quasi-periodicities on a year-likemore » timescale appear to occur often in blazars. No straightforward model describing these possible periodicities is yet available, but some plausible interpretations for the physical mechanisms causing periodic variabilities of these sources are examined.« less

SPITZER SPACE TELESCOPE MID-IR LIGHT CURVES OF NEPTUNE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stauffer, John; Rebull, Luisa; Carey, Sean J.

2016-11-01

We have used the Spitzer Space Telescope in 2016 February to obtain high cadence, high signal-to-noise, 17 hr duration light curves of Neptune at 3.6 and 4.5 μ m. The light curve duration was chosen to correspond to the rotation period of Neptune. Both light curves are slowly varying with time, with full amplitudes of 1.1 mag at 3.6 μ m and 0.6 mag at 4.5 μ m. We have also extracted sparsely sampled 18 hr light curves of Neptune at W1 (3.4 μ m) and W2 (4.6 μ m) from the Wide-feld Infrared Survey Explorer ( WISE )/ NEOWISEmore » archive at six epochs in 2010–2015. These light curves all show similar shapes and amplitudes compared to the Spitzer light curves but with considerable variation from epoch to epoch. These amplitudes are much larger than those observed with Kepler / K 2 in the visible (amplitude ∼0.02 mag) or at 845 nm with the Hubble Space Telescope ( HST ) in 2015 and at 763 nm in 2016 (amplitude ∼0.2 mag). We interpret the Spitzer and WISE light curves as arising entirely from reflected solar photons, from higher levels in Neptune’s atmosphere than for K 2. Methane gas is the dominant opacity source in Neptune’s atmosphere, and methane absorption bands are present in the HST 763 and 845 nm, WISE W1, and Spitzer 3.6 μ m filters.« less

Planar light bullets under conditions of second-harmonic generation.

PubMed

Sazonov, Sergey V; Mamaikin, Mikhail S; Komissarova, Maria V; Zakharova, Irina G

2017-08-01

We study solutions to second-harmonic-generation equations in two-dimensional media with anomalous dispersion. The analytical solution is obtained in an approximate form of the planar spatiotemporal two-component soliton by means of the averaged Lagrangian method. It is shown that a decrease in the amplitudes of both soliton components and an increase in the value of the transverse coordinate are accompanied by an increase in their temporal duration. Within this variational approach, we have managed to find a stability criterion for the light bullet and a period of oscillations of soliton parameters. Then, we use the obtained form as an initial configuration to carry out the direct numerical simulation of soliton dynamics. We demonstrate stable propagation of spatiotemporal solitons undergoing small oscillations predicted analytically for a long distance. The formation of a two-component light bullet is shown when we launch a pulse only at the fundamental frequency. In addition, we investigate the phase and group-velocity mismatch effects on the propagation of pulses.

Evidence for an Optical Low-frequency Quasi-periodic Oscillation in the Kepler Light Curve of an Active Galaxy

NASA Astrophysics Data System (ADS)

Smith, Krista Lynne; Mushotzky, Richard F.; Boyd, Patricia T.; Wagoner, Robert V.

2018-06-01

We report evidence for a quasi-periodic oscillation (QPO) in the optical light curve of KIC 9650712, a narrow-line Seyfert 1 galaxy in the original Kepler field. After the development and application of a pipeline for Kepler data specific to active galactic nuclei (AGNs), one of our sample of 21 AGNs selected by infrared photometry and X-ray flux demonstrates a peak in the power spectrum at log ν = ‑6.58 Hz, corresponding to a temporal period of t = 44 days. We note that although the power spectrum is well fit by a model consisting of a Lorentzian and a single power law, alternative continuum models cannot be ruled out. From optical spectroscopy, we measure the black hole mass of this AGN as log (M BH/M ⊙) = 8.17. We find that this frequency lies along a correlation between low-frequency QPOs and black hole mass from stellar and intermediate mass black holes to AGNs, similar to the known correlation in high-frequency QPOs.

Rapid X-Ray Variations of the Geminga Pulsar Wind Nebula

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hui, C. Y.; Lee, Jongsu; Kong, A. K. H.

A recent study by Posselt et al. reported the deepest X-ray investigation of the Geminga pulsar wind nebula (PWN) by using Chandra X-ray Observatory . In comparison with previous studies of this system, a number of new findings have been reported, and we found that these suggest the possible variabilities in various components of this PWN. This motivates us to carry out a dedicated search for the morphological and spectral variations of this complex nebula. We have discovered variabilities on timescales from a few days to a few months from different components of the nebula. The fastest change occurred inmore » the circumstellar environment at a rate of 80% of the speed of light. One of the most spectacular results is the wiggling of a half light-year long tail as an extension of the jet, which is significantly bent by the ram pressure. The jet wiggling occurred at a rate of about 20% of the speed of light. This twisted structure could possibly be a result of a propagating torsional Alfv́en wave. We have also found evidence of spectral hardening along this tail for a period of about nine months.« less

Rapid X-Ray Variations of the Geminga Pulsar Wind Nebula

NASA Astrophysics Data System (ADS)

Hui, C. Y.; Lee, Jongsu; Kong, A. K. H.; Tam, P. H. T.; Takata, J.; Cheng, K. S.; Ryu, Dongsu

2017-09-01

A recent study by Posselt et al. reported the deepest X-ray investigation of the Geminga pulsar wind nebula (PWN) by using Chandra X-ray Observatory. In comparison with previous studies of this system, a number of new findings have been reported, and we found that these suggest the possible variabilities in various components of this PWN. This motivates us to carry out a dedicated search for the morphological and spectral variations of this complex nebula. We have discovered variabilities on timescales from a few days to a few months from different components of the nebula. The fastest change occurred in the circumstellar environment at a rate of 80% of the speed of light. One of the most spectacular results is the wiggling of a half light-year long tail as an extension of the jet, which is significantly bent by the ram pressure. The jet wiggling occurred at a rate of about 20% of the speed of light. This twisted structure could possibly be a result of a propagating torsional Alfv´en wave. We have also found evidence of spectral hardening along this tail for a period of about nine months.

The most plausible explanation of the cyclic period changes in close binaries: the case of the RS CVn-type binary WW Dra

NASA Astrophysics Data System (ADS)

Liao, W.-P.; Qian, S.-B.

2010-07-01

Cyclic period changes are a fairly common phenomenon in close binary systems and are usually explained as being caused either by the magnetic activity of one or both components or by the light travel time effect (LTTE) of a third body. We searched the orbital period changes in 182 EA-type (including the 101 Algol systems used by Hall), 43 EB-type and 53 EW-type binaries with known mass ratio and spectral type of the secondary component. We reproduced and improved the diagram in Hall according to the new collected data. Our plots do not support the conclusion derived by Hall that cyclic period changes are restricted to binaries having a secondary component with spectral type later than F5. The presence of period changes among systems with a secondary component of early type indicates that magnetic activity is one, but not the only, cause of the period variation. It is discovered that cyclic period changes, probably resulting from the presence of a third body, are more frequent in EW-type binaries among close systems. Therefore, the most plausible explanation of the cyclic period changes is the LTTE through the presence of a third body. Using the century-long historical record of the times of light minimum, we analysed the cyclic period change in the Algol binary WW Dra. It is found that the orbital period of the binary shows a ~112.2-yr cyclic variation with an amplitude of ~0.1977d. The cyclic oscillation can be attributed to the LTTE by means of a third body with a mass no less than 6.43Msolar. However, no spectral lines of the third body were discovered, indicating that it may be a candidate black hole. The third body is orbiting the binary at a distance closer than 14.4 au and may play an important role in the evolution of this system.

Period Study and Analyses of 2017 Observations of the Totally Eclipsing, Solar Type Binary, MT Camelopardalis

NASA Astrophysics Data System (ADS)

Faulkner, Danny R.; Samec, Ronald G.; Caton, Daniel B.

2018-06-01

We report here on a period study and the analysis of BVRcIc light curves (taken in 2017) of MT Cam (GSC03737-01085), which is a solar type (T ~ 5500K) eclipsing binary. D. Caton observed MT Cam on 05, 14, 15, 16, and 17, December 2017 with the 0.81-m reflector at Dark Sky Observatory. Six times of minimum light were calculated from four primary eclipses and two secondary eclipses:HJD I = 24 58092.4937±0.0002, 2458102.74600±0.0021, 2458104.5769±0.0002, 2458104.9434±0.0029HJD II = 2458103.6610±0.0001, 2458104.7607±0.0020,Six times of minimum light were also calculated from data taken by Terrell, Gross, and Cooney, in their 2016 and 2004 observations (reported in IBVS #6166; TGC, hereafter). In addition, six more times of minimum light were taken from the literature. From all 18 times of minimum light, we determined the following light elements:JD Hel Min I=2458102.7460(4) + 0.36613937(5) EWe found the orbital period was constant over the 14 years spanning all observations. We note that TGC found a slightly increasing period. However, our results were obtained from a period study rather than comparison of observations from only two epochs by the Wilson-Devinney (W-D) Program. A BVRcIc Johnson-Cousins filtered simultaneous W-D Program solution gives a mass ratio (0.3385±0.0014) very nearly the same as TGC’s (0.347±0.003), and a component temperature difference of only ~40 K. As with TGC, no spot was needed in the modeling. Our modeling (beginning with Binary Maker 3.0 fits) was done without prior knowledge of TGC’s. This shows the agreement achieved when independent analyses are done with the W-D code. The present observations were taken 1.8 years later than the last curves by TGC, so some variation is expected.The Roche Lobe fill-out of the binary is ~13% and the inclination is ~83.5 degrees. The system is a shallow contact W-type W UMa Binary, albeit, the amplitudes of the primary and secondary eclipse are very nearly identical. An eclipse duration of ~21

The Spot Variability and Related Brightness variations of the Solar Type PreContact W UMa Binary System V1001 Cas

NASA Astrophysics Data System (ADS)

Samec, Ronald George; Koenke, Sam S.; Faulkner, Danny R.

2015-08-01

A new classification of eclipsing binary has emerged, Pre Contact WUMa Binaries (PCWB’s, Samec et al. 2012). These solar-type systems are usually detached or semidetached with one or both components under filling their critical Roche lobes. They usually have EA or EB-type light curves (unequal eclipse depths, indicating components with substantially different temperatures). The accepted scenario for these W UMa binaries is that they are undergoing steady but slow angular momentum losses due to magnetic braking as stellar winds blow radially away on stiff bipolar field lines. These binaries are believed to come into stable contact and eventually coalesce into blue straggler type, single, fast rotating A-type stars (Guinan and Bradstreet,1988). High precision 2012 and 2009 light curves are compared for the very short period (~0.43d) Precontact W UMa Binary (PCWB), V1001 Cassiopeia. This is the shortest period PCWB found so far. Its short period, similar to the majority of W UMa’s, in contrast to its distinct Algol-type light curve, make it a very rare and interesting system. Our solutions of light curves separated by some three years give approximately the same physical parameters. However the spots radically change, in temperature, area and position causing a distinctive variation in the shape of the light curves. We conclude that spots are very active on this solar type dwarf system and that it may mimic its larger cousins, the RS CVn binaries.

Light-Induced Alterations in Striatal Neurochemical Profiles

NASA Technical Reports Server (NTRS)

Sroufe, Angela E.; Whittaker, J. A.; Patrickson, J. W.

1997-01-01

Much of our present knowledge regarding circadian rhythms and biological activity during space flight has been derived from those missions orbiting the Earth. During space missions, astronauts can become exposed to bright/dark cycles that vary considerably from those that entrain the mammalian biological timing system to the 24-hour cycle found on Earth. As a spacecraft orbits the Earth, the duration of the light/dark period experienced becomes a function of the time it takes to circumnavigate the planet which in turn depends upon the altitude of the craft. Orbiting the Earth at an altitude of 200-800 km provides a light/dark cycle lasting between 80 and 140 minutes, whereas a voyage to the moon or even another planet would provide a light condition of constant light. Currently, little is known regarding the effects of altered light/dark cycles on neurochemical levels within the central nervous system (CNS). Many biochemical, physiological and behavioral phenomena are under circadian control, governed primarily by the hypothalamic suprachiasmatic nucleus. As such, these phenomena are subject to influence by the environmental light/dark cycle. Circadian variations in locomotor and behavioral activities have been correlated to both the environmental light/dark cycle and to dopamine (DA) levels within the CNS. It has been postulated by Martin-Iverson et al. that DA's role in the control of motor activity is subject to modulation by circadian rhythms (CR), environmental lighting and excitatory amino acids (EAAs). In addition, DA and EAA receptor regulated pathways are involved in both the photic entrainment of CR and the control of motor activity. The cellular mechanisms by which DA and EAA-receptor ligands execute these functions, is still unclear. In order to help elucidate these mechanisms, we set out to determine the effects of altered environmental light/dark cycles on CNS neurotransmitter levels. In this study, we focused on the striatum, a region of the brain

Amplitude Variations in Pulsating Red Giants. II. Some Systematics

NASA Astrophysics Data System (ADS)

Percy, J. R.; Laing, J.

2017-12-01

In order to extend our previous studies of the unexplained phenomenon of cyclic amplitude variations in pulsating red giants, we have used the AAVSO time-series analysis package vstar to analyze long-term AAVSO visual observations of 50 such stars, mostly Mira stars. The relative amount of the variation, typically a factor of 1.5, and the time scale of the variation, typically 20-35 pulsation periods, are not significantly different in longer-period, shorter-period, and carbon stars in our sample, and they also occur in stars whose period is changing secularly, perhaps due to a thermal pulse. The time scale of the variations is similar to that in smaller-amplitude SR variables, but the relative amount of the variation appears to be larger in smaller-amplitude stars, and is therefore more conspicuous. The cause of the amplitude variations remains unclear, though they may be due to rotational modulation of a star whose pulsating surface is dominated by the effects of large convective cells.

An unusual very low-mass high-amplitude pre-main sequence periodic variable

NASA Astrophysics Data System (ADS)

Rodríguez-Ledesma, M. V.; Mundt, R.; Ibrahimov, M.; Messina, S.; Parihar, P.; Hessman, F. V.; Alves de Oliveira, C.; Herbst, W.

2012-08-01

Aims: We have investigated the nature of the variability of CHS 7797, an unusual periodic variable in the Orion Nebula Cluster. Methods: An extensive I-band photometric data set of CHS 7797 was compiled between 2004-2010 using various telescopes. Further optical data have been collected in R and z' bands. In addition, simultaneous observations of the ONC region including CHS 7797 were performed in the I,J,Ks & IRAC 3.6 and 4.5 μm bands over a time interval of ≈40 d. Results: CHS 7797 shows an unusual large-amplitude variation of ≈1.7 mag in the R,I, and z' bands with a period 17.786 ± 0.03 d (FAP = 1 × 10-15%). The amplitude of the brightness modulation decreases only slightly at longer wavelengths. The star is faint during ≈2/3 of the period and the shape of the phased light-curves for the seven different observing seasons shows minor changes and small-amplitude variations. Interestingly, there are no significant colour-flux correlations for λ ≲ 2 μm, while the object becomes redder when fainter at longer wavelengths. CHS 7797 has a spectral type of M 6 and an estimated mass between 0.04-0.1 M⊙. Conclusions: The analysis of the data suggests that the periodic variability of CHS 7797 is most probably caused by an orbital motion. Variability as a result of rotational brightness modulation by a hot spot is excluded by the lack of any colour-brightness correlation in the optical. The latter indicates that CHS 7797 is most probably occulted by circumstellar matter in which grains have grown from typical 0.1 μm to ≈1-2 μm sizes. We discuss two possible scenarios in which CHS 7797 is periodically eclipsed by structures in a disc, namely that CHS 7797 is a single object with a circumstellar disc, or that CHS 7797 is a binary system, similar to KH 15D, in which an inclined circumbinary disc is responsible of the variability. Possible reasons for the typical 0.3 mag variations in I-band at a given phase are discussed.

New variational principles for locating periodic orbits of differential equations.

PubMed

Boghosian, Bruce M; Fazendeiro, Luis M; Lätt, Jonas; Tang, Hui; Coveney, Peter V

2011-06-13

We present new methods for the determination of periodic orbits of general dynamical systems. Iterative algorithms for finding solutions by these methods, for both the exact continuum case, and for approximate discrete representations suitable for numerical implementation, are discussed. Finally, we describe our approach to the computation of unstable periodic orbits of the driven Navier-Stokes equations, simulated using the lattice Boltzmann equation.

Effect of eccentricity and light level on the timing of light adaptation mechanisms.

PubMed

Barrionuevo, Pablo A; Matesanz, Beatriz M; Gloriani, Alejandro H; Arranz, Isabel; Issolio, Luis; Mar, Santiago; Aparicio, Juan A

2018-04-01

We explored the complexity of the light adaptation process, assessing adaptation recovery (Ar) at different eccentricities and light levels. Luminance thresholds were obtained with transient background fields at mesopic and photopic light levels for temporal retinal eccentricities (0°-15°) with test/background stimulus size of 0.5°/1° using a staircase procedure in a two-channel Maxwellian view optical system. Ar was obtained in comparison with steady data [Vis. Res.125, 12 (2016)VISRAM0042-698910.1016/j.visres.2016.04.008]. Light level proportionally affects Ar only at fovea. Photopic extrafoveal thresholds were one log unit higher for transient conditions. Adaptation was equally fast at low light levels for different retinal locations with variations mainly affected by noise. These results evidence different timing in the mechanisms of adaptation involved.

Diurnal lighting patterns and habitat alter opsin expression and colour preferences in a killifish

PubMed Central

Johnson, Ashley M.; Stanis, Shannon; Fuller, Rebecca C.

2013-01-01

Spatial variation in lighting environments frequently leads to population variation in colour patterns, colour preferences and visual systems. Yet lighting conditions also vary diurnally, and many aspects of visual systems and behaviour vary over this time scale. Here, we use the bluefin killifish (Lucania goodei) to compare how diurnal variation and habitat variation (clear versus tannin-stained water) affect opsin expression and the preference to peck at different-coloured objects. Opsin expression was generally lowest at midnight and dawn, and highest at midday and dusk, and this diurnal variation was many times greater than variation between habitats. Pecking preference was affected by both diurnal and habitat variation but did not correlate with opsin expression. Rather, pecking preference matched lighting conditions, with higher preferences for blue at noon and for red at dawn/dusk, when these wavelengths are comparatively scarce. Similarly, blue pecking preference was higher in tannin-stained water where blue wavelengths are reduced. In conclusion, L. goodei exhibits strong diurnal cycles of opsin expression, but these are not tightly correlated with light intensity or colour. Temporally variable pecking preferences probably result from lighting environment rather than from opsin production. These results may have implications for the colour pattern diversity observed in these fish. PMID:23698009

Investigation on Periodically Surface-Corrugated Long-Period Gratings Inscribed on Photonic Crystal Fibers

NASA Astrophysics Data System (ADS)

Han, Young-Geun

2017-04-01

Transmission characteristics of periodically surface-corrugated long-period gratings (LPGs) inscribed on photonic crystal fibers (PCFs) using a wet-etching technique were experimentally investigated. A conventional wet method was implemented to periodically engrave the silica cladding region of the PCFs resulting in the periodic surface corrugation in the PCF. After applying the external strain to the PCF with the periodic surface micro-ridges, periodic modulation of refractive index based on the photoelastic effect is induced resulting in the formation of the PCF-based LPG. Increasing the applied strain successfully improves the extinction ratio of the resonant peak of the PCF-based LPG without the resonant wavelength shift. We also measured the transmission characteristics of the PCF-based LPG with variations in temperature and ambient index.

EVIDENCE FOR MASS EJECTION ASSOCIATED WITH LONG SECONDARY PERIODS IN RED GIANTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, P. R.; Nicholls, C. P., E-mail: wood@mso.anu.edu.a, E-mail: nicholls@mso.anu.edu.a

2009-12-10

Approximately 30% of luminous red giants exhibit a long secondary period (LSP) of variation in their light curves in addition to a shorter primary period of oscillation. The cause of the LSP has so far defied explanation: leading possibilities are binarity and a nonradial mode of oscillation. Here, large samples of red giants in the Large Magellanic Cloud both with and without LSPs are examined for evidence of an 8 or 24 mum mid-IR excess caused by circumstellar dust. It is found that stars with LSPs show a significant mid-IR excess compared to stars without LSPs. Furthermore, the near-IR Jmore » - K color seems unaffected by the presence of the 24 mum excess. These findings indicate that LSPs cause mass ejection from red giants and that the lost mass and circumstellar dust is most likely in either a clumpy or a disk-like configuration. The underlying cause of the LSP and the mass ejection remains unknown.« less

Period gene expression in four neurons is sufficient for rhythmic activity of Drosophila melanogaster under dim light conditions.

PubMed

Rieger, Dirk; Wülbeck, Corinna; Rouyer, Francois; Helfrich-Förster, Charlotte

2009-08-01

The clock gene expressing lateral neurons (LN) is crucial for Drosophila 's rhythmic locomotor activity under constant conditions. Among the LN, the PDF expressing small ventral lateral neurons (s-LN(v)) are thought to control the morning activity of the fly (M oscillators) and to drive rhythmic activity under constant darkness. In contrast, a 5th PDF-negative s-LN( v) and the dorsal lateral neurons (LN(d)) appeared to control the fly's evening activity (E oscillators) and to drive rhythmic activity under constant light. Here, the authors restricted period gene expression to 4 LN-the 5th s-LN(v) and 3 LN(d)- that are all thought to belong to the E oscillators and tested them in low light conditions. Interestingly, such flies showed rather normal bimodal activity patterns under light moonlight and constant moonlight conditions, except that the phase of M and E peaks was different. This suggests that these 4 neurons behave as ''M'' and ''E'' cells in these conditions. Indeed, they found by PER and TIM immunohistochemistry that 2 LN(d) advanced their phase upon moonlight as predicted for M oscillators, whereas the 5th s-LN(v) and 1 LN(d) delayed their activity upon moonlight as predicted for E oscillators. Their results suggest that the M or E characteristic of clock neurons is rather flexible. M and E oscillator function may not be restricted to certain anatomically defined groups of clock neurons but instead depends on the environmental conditions.

Light Exposure and Eye Growth in Childhood.

PubMed

Read, Scott A; Collins, Michael J; Vincent, Stephen J

2015-10-01

The purpose of this study was to examine the relationship between objectively measured ambient light exposure and longitudinal changes in axial eye growth in childhood. A total of 101 children (41 myopes and 60 nonmyopes), 10 to 15 years of age participated in this prospective longitudinal observational study. Axial eye growth was determined from measurements of ocular optical biometry collected at four study visits over an 18-month period. Each child's mean daily light exposure was derived from two periods (each 14 days long) of objective light exposure measurements from a wrist-worn light sensor. Over the 18-month study period, a modest but statistically significant association between greater average daily light exposure and slower axial eye growth was observed (P = 0.047). Other significant predictors of axial eye growth in this population included children's refractive error group (P < 0.001), sex (P < 0.01), and age (P < 0.001). Categorized according to their objectively measured average daily light exposure and adjusting for potential confounders (age, sex, baseline axial length, parental myopia, nearwork, and physical activity), children experiencing low average daily light exposure (mean daily light exposure: 459 ± 117 lux, annual eye growth: 0.13 mm/y) exhibited significantly greater eye growth than children experiencing moderate (842 ± 109 lux, 0.060 mm/y), and high (1455 ± 317 lux, 0.065 mm/y) average daily light exposure levels (P = 0.01). In this population of children, greater daily light exposure was associated with less axial eye growth over an 18-month period. These findings support the role of light exposure in the documented association between time spent outdoors and childhood myopia.

A search for transit timing variations and orbital decay in WASP-46b

NASA Astrophysics Data System (ADS)

Petrucci, R.; Jofré, E.; Ferrero, L. V.; Cúneo, V.; Saker, L.; Lovos, F.; Gómez, M.; Mauas, P.

2018-02-01

We present 12 new transit observations of the exoplanet WASP-46b obtained with the 1.54-m telescope at Estación Astrofísica de Bosque Alegre (EABA, Argentina) and the 0.40-m Horacio Ghielmetti and 2.15-m Jorge Sahade telescopes at Complejo Astronómico El Leoncito (CASLEO, Argentina). We analyse them together with 37 light curves from the literature to re-determine the physical parameters and search for additional planets via transit timing variations (TTVs). We consider the 31 transits with uncertainties in their mid-transit times (e_T0) < 1 min, to perform the first homogeneous study of TTVs for the system, finding a dispersion of σ = 1.66 min over a 6 yr baseline. Since no periodic variations are found, our interpretation for this relatively high value of σ is that the stellar activity could be affecting the measured mid-transit times. This value of dispersion allows us to rule out the presence of additional bodies with masses larger than 2.3, 4.6, 7 and 9.3 M_{\\oplus} at the first-order mean-motion resonances 2:1, 3:2, 4:3 and 5:4 with the transiting planet, respectively. Despite the 6 yr baseline and a typical light-curve precision of 2 × 10-3, we find that we cannot significantly demonstrate a slow decrease of the orbital period of WASP-46b. We place a lower limit of Q⋆ > 7 × 103 on the tidal quality factor and determine that an additional 6 yr baseline is required to rule out Q⋆ < 105.

Behavioral and physiological photoresponses to light intensity by intertidal microphytobenthos

NASA Astrophysics Data System (ADS)

Du, Guoying; Yan, Hongmei; Liu, Chunrong; Mao, Yunxiang

2018-03-01

Behavioral and physiological responses to light are the two major mechanisms by which natural microphytobenthic assemblages adapt to the intertidal environment and protect themselves from light stress. The present study investigated these photoresponses with different light intensities over 8 h of illumination, and used a specific inhibitor (Latrunculin A, Lat A) for migration to compare migratory and non-migratory microphytobenthos (MPB). Photosynthetic activity was detected using rapid light curves and induction curves by chlorophyll fluorescence. It showed distinct variation in migratory responses to different light intensities; high light induced downward migration to avoid photoinhibition, and low and medium light (50-250 μmol/(m2·s)) promoted upward migration followed by downward migration after certain period of light exposure. No significant difference in non-photochemical quenching (NPQ) or PSII maximal quantum yield ( F v/ F m) was detected between low and medium light irradiance, possibly indicating that only high light influences the photosynthetic capability of MPB. Decreased photosynthetic activity, indicated by three parameters, the maximum relative electron transport rate (rETR max), minimum saturating irradiance ( E k) and light utilization coefficient ( α), was observed in MPB after exposure to prolonged illumination under low and medium light. Lat A effectively inhibited the migration of MPB in all light treatments and induced lower F v/ F m under high light (500 and 100 μmol/(m2·s)) and prolonged illumination at 250 μmol/(m2·s), but did not significantly influence F v/ F m under low light (0-100 μmol/(m2·s)) or NPQ. The increase of NPQ in Lat A treatments with time implied that the MPB assemblages can recover their physiological photoprotection capacity to adapt to light stress. Non-migratory MPB exhibited lower light use efficiency (lower α) and lower maximum photosynthetic capacity (lower rETR max) than migratory MPB under light

Testing Limits on Matte Surface Color Perception in Three-Dimensional Scenes with Complex Light Fields

PubMed Central

Doerschner, K.; Boyaci, H.; Maloney, L. T.

2007-01-01

We investigated limits on the human visual system’s ability to discount directional variation in complex lights field when estimating Lambertian surface color. Directional variation in the light field was represented in the frequency domain using spherical harmonics. The bidirectional reflectance distribution function of a Lambertian surface acts as a low-pass filter on directional variation in the light field. Consequently, the visual system needs to discount only the low-pass component of the incident light corresponding to the first nine terms of a spherical harmonics expansion (Basri & Jacobs, 2001; Ramamoorthi & Hanrahan, 2001) to accurately estimate surface color. We test experimentally whether the visual system discounts directional variation in the light field up to this physical limit. Our results are consistent with the claim that the visual system can compensate for all of the complexity in the light field that affects the appearance of Lambertian surfaces. PMID:18053846

A method to eliminate the influence of incident light variations in spectral analysis

NASA Astrophysics Data System (ADS)

Luo, Yongshun; Li, Gang; Fu, Zhigang; Guan, Yang; Zhang, Shengzhao; Lin, Ling

2018-06-01

The intensity of the light source and consistency of the spectrum are the most important factors influencing the accuracy in quantitative spectrometric analysis. An efficient "measuring in layer" method was proposed in this paper to limit the influence of inconsistencies in the intensity and spectrum of the light source. In order to verify the effectiveness of this method, a light source with a variable intensity and spectrum was designed according to Planck's law and Wien's displacement law. Intra-lipid samples with 12 different concentrations were prepared and divided into modeling sets and prediction sets according to different incident lights and solution concentrations. The spectra of each sample were measured with five different light intensities. The experimental results showed that the proposed method was effective in eliminating the influence caused by incident light changes and was more effective than normalized processing.

Open water camouflage via 'leaky' light guides in the midwater squid Galiteuthis.

PubMed

Holt, Amanda L; Sweeney, Alison M

2016-06-01

Galiteuthis, a midwater squid, has photophores on the ventral surfaces of its eyes. These photophores emit bioluminescence to counter-illuminate the shadows cast by the eyes in downwelling sunlight, thereby hiding the eyes from upward-looking predators. The photophores consist of laminated fibre-like cells with semi-coaxial protein-dense layers around axial cytoplasm. These cells have been suggested to function as light guides: bioluminescence is an isotropic process used to hide in an anisotropic light environment, so any emission must be reshaped to be effective. We found a wide variation in cross-sectional geometries of photophore cells; some were more efficient at light guiding than others. We used a set of optical models to place these photophores in the context of the radiance where Galiteuthis lives and discovered a possible adaptive reason for this variation. In Galiteuthis's horizontal and vertical range, ocean radiance is also quite variable. For complete camouflage, photophores must reproduce this variation in radiance using an isotropic source. Our models show that variation in the geometry of the photophore light guides reproduces the predicted variation in ocean radiance experienced by this species. By selectively activating geometrically distinct populations of photophore cells, the animal may reproduce the angular distribution of light at all positions in its habitat. © 2016 The Author(s).

Diel variation of the cellular carbon to nitrogen ratio of Chlorella autotrophica (Chlorophyta) growing in phosphorus- and nitrogen-limited continuous cultures.

PubMed

Ng, Wai Ho Albert; Liu, Hongbin

2015-02-01

We investigated the relationship between daily growth rates and diel variation of carbon (C) metabolism and C to nitrogen (N) ratio under P- and N-limitation in the green algae Chlorella autotrophica. To do this, continuous cultures of C. autotrophica were maintained in a cyclostat culture system under 14:10 light:dark cycle over a series of P- and N-limited growth rates. Cell abundance, together with cell size, as reflected by side scatter signal from flow cytometric analysis demonstrated a synchronized diel pattern with cell division occurring at night. Under either type of nutrient limitation, the cellular C:N ratio increased through the light period and decreased through the dark period over all growth rates, indicating a higher diel variation of C metabolism than that of N. Daily average cellular C:N ratios were higher at lower dilution rates under both types of nutrient limitation but cell enlargement was only observed at lower dilution rates under P-limitation. Carbon specific growth rates during the dark period positively correlated with cellular daily growth rates (dilution rates), with net loss of C during night at the lowest growth rates under N-limitation. Under P-limitation, dark C specific growth rates were close to zero at low dilution rates but also exhibited an increasing trend at high dilution rates. In general, diel variations of cellular C:N were low when dark C specific growth rates were high. This result indicated that the fast growing cells performed dark C assimilation at high rates, hence diminished the uncoupling of C and N metabolism at night. © 2014 Phycological Society of America.

Anatomic variation and orgasm: Could variations in anatomy explain differences in orgasmic success?

PubMed

Emhardt, E; Siegel, J; Hoffman, L

2016-07-01

Though the public consciousness is typically focused on factors such as psychology, penis size, and the presence of the "G-spot," there are other anatomical and neuro-anatomic differences that could play an equal, or more important, role in the frequency and intensity of orgasms. Discovering these variations could direct further medical or procedural management to improve sexual satisfaction. The aim of this study is to review the available literature of anatomical sexual variation and to explain why this variation may predispose some patients toward a particular sexual experience. In this review, we explored the available literature on sexual anatomy and neuro-anatomy. We used PubMed and OVID Medline for search terms, including orgasm, penile size variation, clitoral variation, Grafenberg spot, and benefits of orgasm. First we review the basic anatomy and innervation of the reproductive organs. Then we describe several anatomical variations that likely play a superior role to popular known variation (penis size, presence of g-spot, etc). For males, the delicate play between the parasympathetic and sympathetic nervous systems is vital to achieve orgasm. For females, the autonomic component is more complex. The clitoris is the primary anatomical feature for female orgasm, including its migration toward the anterior vaginal wall. In conclusions, orgasms are complex phenomena involving psychological, physiological, and anatomic variation. While these variations predispose people to certain sexual function, future research should explore how to surgically or medically alter these. Clin. Anat. 29:665-672, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Light transmittance estimates in a longleaf pine woodland

Treesearch

Michael A. Battaglia; Robert J. Mitchell; Paul P. Mou; Stephen D. Pecot

2003-01-01

While the importance of canopy structure in open woodlands and savannas on regulating the flow of energy and matter is well known, few studies have investigated how variation in overstory abundance influences canopy light transmission and the extent that estimates vary in their ability to characterize the light environment in these ecosystems. Canopy light...

Charged Particle Periodicities in Saturn's Outer Magnetosphere

NASA Astrophysics Data System (ADS)

Carbary, J.; Mitchell, D.; Krimigis, S.; Krupp, N.

2006-12-01

The MIMI/LEMMS instrument on the Cassini spacecraft has measured energetic electrons in the energy range 20-300 keV within Saturn's magnetosphere. In the outer magnetosphere beyond about 20 RS, these electrons and their spectral index display strong variations with periods comparable to the 10.76 hour period measured by radio observations of Cassini. Inside about 20 RS, such electron variations may be present but are masked by satellite and ring effects. Electron periodicities are most easily recognized on the "night side" segments of the Cassini orbits, although they are also observed to some extent on the day side. For both day and night sides, a wavelet analysis of de-trended count rates in the 20-40 RS region reveals a mean period of 10.52 +/- 0.74 hrs for the six electron channels investigated. If constrained to the night side only, a wavelet analysis gives a mean period of 10.88 +/- 0.52 hours. These periods were obtained from several orbits of the Cassini spacecraft during the two-year period from SOI (July 2004) to the present (November 2006).

Angle-resolved light scattering of individual rod-shaped bacteria based on Fourier transform light scattering

NASA Astrophysics Data System (ADS)

Jo, Youngju; Jung, Jaehwang; Lee, Jee Woong; Shin, Della; Park, Hyunjoo; Nam, Ki Tae; Park, Ji-Ho; Park, Yongkeun

2014-05-01

Two-dimensional angle-resolved light scattering maps of individual rod-shaped bacteria are measured at the single-cell level. Using quantitative phase imaging and Fourier transform light scattering techniques, the light scattering patterns of individual bacteria in four rod-shaped species (Bacillus subtilis, Lactobacillus casei, Synechococcus elongatus, and Escherichia coli) are measured with unprecedented sensitivity in a broad angular range from -70° to 70°. The measured light scattering patterns are analyzed along the two principal axes of rod-shaped bacteria in order to systematically investigate the species-specific characteristics of anisotropic light scattering. In addition, the cellular dry mass of individual bacteria is calculated and used to demonstrate that the cell-to-cell variations in light scattering within bacterial species is related to the cellular dry mass and growth.

Light quality and efficiency of consumer grade solid state lighting products

NASA Astrophysics Data System (ADS)

Dam-Hansen, Carsten; Corell, Dennis Dan; Thorseth, Anders; Poulsen, Peter Behrensdorff

2013-03-01

The rapid development in flux and efficiency of Light Emitting Diodes (LED) has resulted in a flooding of the lighting market with Solid State Lighting (SSL) products. Many traditional light sources can advantageously be replaced by SSL products. There are, however, large variations in the quality of these products, and some are not better than the ones they are supposed to replace. A lack of quality demands and standards makes it difficult for consumers to get an overview of the SSL products. Here the results of a two year study investigating SSL products on the Danish market are presented. Focus has been on SSL products for replacement of incandescent lamps and halogen spotlights. The warm white light and good color rendering properties of these traditional light sources are a must for lighting in Denmark and the Nordic countries. 266 SSL replacement lamps have been tested for efficiency and light quality with respect to correlated color temperature and color rendering properties. This shows a trade-off between high color rendering warm white light and energy efficiency. The lumen and color maintenance over time has been investigated and results for products running over 11000 h will be presented. A new internet based SSL product selection tool will be shown. Here the products can be compared on efficiency, light quality parameters, thus providing a better basis for the selection of SSL products for consumers.

A simple method for correcting spatially resolved solar intensity oscillation observations for variations in scattered light

NASA Technical Reports Server (NTRS)

Jefferies, S. M.; Duvall, T. L., Jr.

1991-01-01

A measurement of the intensity distribution in an image of the solar disk will be corrupted by a spatial redistribution of the light that is caused by the earth's atmosphere and the observing instrument. A simple correction method is introduced here that is applicable for solar p-mode intensity observations obtained over a period of time in which there is a significant change in the scattering component of the point spread function. The method circumvents the problems incurred with an accurate determination of the spatial point spread function and its subsequent deconvolution from the observations. The method only corrects the spherical harmonic coefficients that represent the spatial frequencies present in the image and does not correct the image itself.

Toward understanding early Earth evolution: Prescription for approach from terrestrial noble gas and light element records in lunar soils

PubMed Central

Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A.; Miura, Yayoi N.

2008-01-01

Because of the almost total lack of geological record on the Earth's surface before 4 billion years ago, the history of the Earth during this period is still enigmatic. Here we describe a practical approach to tackle the formidable problems caused by this lack. We propose that examinations of lunar soils for light elements such as He, N, O, Ne, and Ar would shed a new light on this dark age in the Earth's history and resolve three of the most fundamental questions in earth science: the onset time of the geomagnetic field, the appearance of an oxygen atmosphere, and the secular variation of an Earth–Moon dynamical system. PMID:19001263

Detecting the Companions and Ellipsoidal Variations of RS CVn Primaries. II. o Draconis, a Candidate for Recent Low-mass Companion Ingestion

NASA Astrophysics Data System (ADS)

Roettenbacher, Rachael M.; Monnier, John D.; Fekel, Francis C.; Henry, Gregory W.; Korhonen, Heidi; Latham, David W.; Muterspaugh, Matthew W.; Williamson, Michael H.; Baron, Fabien; ten Brummelaar, Theo A.; Che, Xiao; Harmon, Robert O.; Schaefer, Gail H.; Scott, Nicholas J.; Sturmann, Judit; Sturmann, Laszlo; Turner, Nils H.

2015-08-01

To measure the stellar and orbital properties of the metal-poor RS CVn binary o Draconis (o Dra), we directly detect the companion using interferometric observations obtained with the Michigan InfraRed Combiner at Georgia State University's Center for High Angular Resolution Astronomy (CHARA) Array. The H-band flux ratio between the primary and secondary stars is the highest confirmed flux ratio (370 ± 40) observed with long-baseline optical interferometry. These detections are combined with radial velocity data of both the primary and secondary stars, including new data obtained with the Tillinghast Reflector Echelle Spectrograph on the Tillinghast Reflector at the Fred Lawrence Whipple Observatory and the 2 m Tennessee State University Automated Spectroscopic Telescope at Fairborn Observatory. We determine an orbit from which we find model-independent masses and ages of the components ({M}A=1.35+/- 0.05 {M}⊙ , {M}B=0.99+/- 0.02 {M}⊙ , system age = 3.0\\mp 0.5 Gyr). An average of a 23-year light curve of o Dra from the Tennessee State University Automated Photometric Telescope folded over the orbital period newly reveals eclipses and the quasi-sinusoidal signature of ellipsoidal variations. The modeled light curve for our system's stellar and orbital parameters confirm these ellipsoidal variations due to the primary star partially filling its Roche lobe potential, suggesting most of the photometric variations are not due to stellar activity (starspots). Measuring gravity darkening from the average light curve gives a best-fit of β =0.07+/- 0.03, a value consistent with conventional theory for convective envelope stars. The primary star also exhibits an anomalously short rotation period, which, when taken with other system parameters, suggests the star likely engulfed a low-mass companion that had recently spun-up the star.

Temperature Variation under Continuous Light Restores Tomato Leaf Photosynthesis and Maintains the Diurnal Pattern in Stomatal Conductance

PubMed Central

Haque, Mohammad S.; de Sousa, Alexandra; Soares, Cristiano; Kjaer, Katrine H.; Fidalgo, Fernanda; Rosenqvist, Eva; Ottosen, Carl-Otto

2017-01-01

The response of tomato plants (Solanum lycopersicum L. cv. Aromata) to continuous light (CL) in relation to photosynthesis, abscisic acid (ABA) and reactive oxygen species (ROS) was investigated to improve the understanding of the development and/or alleviation of CL-induced leaf injury in constant and diurnal temperature fluctuations with similar daily light integral and daily mean temperature. The plants were grown in three photoperiodic treatments for 15 days; One treatment with a 16/8 h light/dark period and a light/dark temperature of 27/17°C (Control), two CL treatments with 24 h photoperiods, one with a constant temperature of 24°C (CLCT) and the other one with variable temperature of 27/17°C for 16/8 ho, respectively (CLVT). A diurnal pattern of stomatal conductance (gs) and [ABA] was observed in the plants grown in the control and CLVT conditions, while the plants in CLCT conditions experienced a significant decrease in stomatal conductance aligned with an increase in ABA. The net photosynthesis (A) was significantly reduced in CLCT, aligned with a significant decrease in the maximum rate of Rubisco carboxylation (Vcmax), the maximum rate of electron transport (Jmax) and mesophyll diffusion conductance to CO2 (gm) in comparison to the control and CLVT. An increased production of H2O2 and O2•- linked with increased activities of antioxidative enzymes was seen in both CL treatments, but despite of this, leaf injuries were only observed in the CLCT treatment. The results suggest that the diurnal temperature fluctuations alleviated the CL injury symptoms, probably because the diurnal cycles of cellular mechanisms were maintained. The ROS were shown not to be directly involved in CL-induced leaf injury, since both ROS production and scavenging was highest in CLVT without leaf chlorotic symptoms. PMID:28979273

Emission lines in the long period Cepheid l Carinae

NASA Technical Reports Server (NTRS)

Boehm-Vitense, Erika; Love, Stanley G.

1991-01-01

For the Cepheid (l) Carinae with a pulsation period of 35.5 days we have studied the emission line fluxes as a function of pulsational phase in order to find out whether we see chromosphere and transition layer emission or whether we see emission due to an outward moving shock. All emission lines show a steep increase in flux shortly before maximum light suggestive of a shock moving through the surface layers. The large ratio of the C IV to C II line fluxes shows that these are not transition layer lines. During maximum light the large ratio of the C IV to C II line fluxes also suggests that we see emission from a shock with velocities greater than 100 km/sec such that C IV emission can be excited. With such velocities mass outflow appears possible. The variations seen in the Mg II line profiles show that there is an internal absorption over a broad velocity band independent of the pulsational phase. We attribute this absorption to a circumstellar 'shell'. This 'shell' appears to be seen also as spatially extended emission in the O I line at 1300 angstrom, which is probably excited by resonance with Ly beta.

Measurement of deformation and frequency response characteristic of PZT tube in tunable fiber laser with short period based on coherent laser beam

NASA Astrophysics Data System (ADS)

Lai, Zhi; Zeng, Xiaodong; Fan, Zhaojin; Xu, Zhichen

2016-09-01

The parameters of light source in synthetic aperture ladar (SAL) is very important to both the design of system and the signal processing algorithm. As the light source in the SAL, the fiber laser use PZT (piezoelectric ceramics) tube stretching the fiber Bragg grating in order to tune the laser frequency. So it is necessary to obtain the deformation and frequency response of PZT tube driven by saw-tooth voltage of different periods. Accordingly, the homodyne detection is used to measure the girth variation of PZT tube. Meanwhile, the frequency response of PZT tube can be viewed with the homodyne signal. The results from measuring a PZT tube show that the method can work well.

Seasonal variation of air temperature at the Mendel Station, James Ross Island in the period of 2006-2009

NASA Astrophysics Data System (ADS)

Laska, Kamil; Prošek, Pavel; Budík, Ladislav

2010-05-01

Key words: air temperature, seasonal variation, James Ross Island, Antarctic Peninsula Recently, significant role of the atmospheric and oceanic circulation variation on positive trend of near surface air temperature along the Antarctic Peninsula has been reported by many authors. However, small number of the permanent meteorological stations located on the Peninsula coast embarrasses a detail analysis. It comprises analysis of spatiotemporal variability of climatic conditions and validation of regional atmospheric climate models. However, geographical location of the Czech Johann Gregor Mendel Station (hereafter Mendel Station) newly established on the northern ice-free part of the James Ross Island provides an opportunity to fill the gap. There are recorded important meteorological characteristics which allow to evaluate specific climatic regime of the region and their impact on the ice-shelf disintegration and glacier retreat. Mendel Station (63°48'S, 57°53'W) is located on marine terrace at the altitude of 7 m. In 2006, a monitoring network of several automatic weather stations was installed at different altitudes ranging from the seashore level up to mesas and tops of glaciers (514 m a.s.l.). In this contribution, a seasonal variation of near surface air temperature at the Mendel Station in the period of 2006-2009 is presented. Annual mean air temperature was -7.2 °C. Seasonal mean temperature ranged from +1.4 °C (December-February) to -17.7 °C (June-August). Frequently, the highest temperature occurred in the second half of January. It reached maximum of +8.1 °C. Sudden changes of atmospheric circulation pattern during winter caused a large interdiurnal variability of air temperature with the amplitude of 30 °C.

A MODEL FOR THERMAL PHASE VARIATIONS OF CIRCULAR AND ECCENTRIC EXOPLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cowan, Nicolas B.; Agol, Eric, E-mail: n-cowan@northwestern.edu

2011-01-10

We present a semi-analytic model atmosphere for close-in exoplanets that captures the essential physics of phase curves: orbital and viewing geometry, advection, and re-radiation. We calibrate the model with the well-characterized transiting planet, HD 189733b, then compute light curves for seven of the most eccentric transiting planets: Gl 436b, HAT-P-2b, HAT-P-11b, HD 17156b, HD 80606b, WASP-17b, and XO-3b. We present phase variations for a variety of different radiative times and wind speeds. In the limit of instant re-radiation, the light-curve morphology is entirely dictated by the planet's eccentricity and argument of pericenter: the light curve maximum leads or trails themore » eclipse depending on whether the planet is receding from or approaching the star at superior conjunction, respectively. For a planet with non-zero radiative timescales, the phase peak occurs early for super-rotating winds, and late for sub-rotating winds. We find that for a circular orbit, the timing of the phase variation maximum with respect to superior conjunction indicates the direction of the dominant winds, but cannot break the degeneracy between wind speed and radiative time. For circular planets the phase minimum occurs half an orbit away from the phase maximum-despite the fact that the coolest longitudes are always near the dawn terminator-and therefore does not convey any additional information. In general, increasing the advective frequency or the radiative time has the effect of reducing the peak-to-trough amplitude of phase variations, but there are interesting exceptions to these trends. Lastly, eccentric planets with orbital periods significantly longer than their radiative time exhibit 'ringing', whereby the hot spot generated at periastron rotates in and out of view. The existence of ringing makes it possible to directly measure the wind speed (the frequency of the ringing) and the radiative time constant (the damping of the ringing).« less

Changes in the Long-Term Intensity Variations in Cygnus X-2 and LMC X-3

NASA Astrophysics Data System (ADS)

Paul, B.; Kitamoto, S.; Makino, F.

2000-01-01

We report the detection of changes in the long-term intensity variations in two X-ray binaries, Cyg X-2 and LMC X-3. In this work, we have used the long-term light curves obtained with the All-Sky Monitors (ASMs) of the Rossi X-Ray Timing Explorer (RXTE), Ginga, Ariel 5, and Vela 5B and the scanning modulation collimator of HEAO 1. It is found that in the light curves of both the sources, obtained with these instruments at various times over the last 30 years, more than one periodic or quasi-periodic component is always present. The multiple prominent peaks in the periodograms have frequencies unrelated to each other. In Cyg X-2, RXTE-ASM data show strong peaks at 40.4 and 68.8 days, and Ginga-ASM data show strong peaks at 53.7 and 61.3 days. Multiple peaks are also observed in LMC X-3. The various strong peaks in the periodograms of LMC X-3 appear at 104, 169, and 216 days (observed with RXTE-ASM) and 105, 214, and 328 days (observed with Ginga-ASM). The present results, when compared with the earlier observations of periodicities in these two systems, demonstrate the absence of any stable long period. The 78 day periodicity detected earlier in Cyg X-2 was probably due to the short time base in the RXTE data that were used, and the periodicity of 198 days in LMC X-3 was due to a relatively short duration of observation with HEAO 1.

Improving the -3 dB bandwidth of medium power GaN-based LEDs through periodic micro via-holes for visible light communications

NASA Astrophysics Data System (ADS)

Zhou, Zheng; Yan, Bing; Teng, Dongdong; Liu, Lilin; Wang, Gang

2017-06-01

Medium power GaN-based light emitting diode (LED) chips with periodic micro via-holes are designed and fabricated. The active area of each chip is 200 μm×800 μm and the diameter of each micro via-hole is 50 μm. For comparison, an LED chip with only one big via-hole (Diameter=86.6 μm) is also fabricated under the same conditions as the control partner. Both kinds of LED chips have an equal effective PN junction area. Experimentally, the LED with periodic via-holes exhibits higher output optical power and the -3 dB modulation bandwidth by about 33% and 48%, respectively, than the LED with only one bigger via-hole. The method of concurrently improving modulation and optical performances of power-type LED chips through periodic micro via-holes take the advantages of easy fabrication, suitable for mass-production.

Observations and Light Curve Solutions of Ultrashort-Period Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Kjurkchieva, Diana P.; Dimitrov, Dinko P.; Ibryamov, Sunay I.; Vasileva, Doroteya L.

2018-02-01

Photometric observations in V and I bands and low-dispersion spectra of 10 ultrashort-period binaries (NSVS 2175434, NSVS 2607629, NSVS 5038135, NSVS 8040227, NSVS 9747584, NSVS 4876238, ASAS 071829-0336.7, SWASP 074658.62+224448.5, NSVS 2729229, NSVS 10632802) are presented. One of them, NSVS 2729229, is newly discovered target. The results from modelling and analysis of our observations revealed that (i) eight targets have overcontact configurations with considerable fill-out factor (up to 0.5), while NSVS 4876238 and ASAS 0718-03 have almost contact configurations; (ii) NSVS 4876238 is rare ultrashort-period binary of detached type; (iii) all stellar components are late dwarfs; (iv) the temperature difference of the components of each target does not exceed 400 K; (v) NSVS 2175434 and SWASP 074658.62 + 224448.5 exhibit total eclipses and their parameters could be assumed as well determined; (v) NSVS 2729229 shows emission in the Hα line. Masses, radii, and luminosities of the stellar components were estimated by the empirical relation `period, orbital axis' for short- and ultrashort-period binaries. We found linear relations mass-luminosity and mass-radius for the stellar components of our targets.

Effectiveness of an extended period of flashing lights and strategic signage to increase the salience of alcohol-gel dispensers for improving hand hygiene compliance.

PubMed

Rashidi, Babak; Li, Aimee; Patel, Rakesh; Harmsen, Irene E; Sabri, Elham; Kyeremanteng, Kwadwo; D'Egidio, Gianni

2016-07-01

Multiple factors affect compliance with hand hygiene, including conspicuity of alcohol-gel dispensers. Previous studies have shown that flashing lights increase hand hygiene compliance; however, the durability of this effect has not been studied. We affixed flashing lights to hand sanitizer dispensers for a total of 6 weeks. Regression analysis was used to compare compliance rates between the beginning and end of the intervention. Our secondary objective was to determine whether compliance rates in cold weather could be improved by adding a sign separated in time and space from the dispensers. Flashing lights improved hand hygiene compliance from 11.8% to 20.7%, and this effect was unchanged over the 6-week study period. Fully charged lights resulted in a greater compliance increase. A preemptive sign did not have a significant effect on hand hygiene rates nor did absolute temperatures. Flashing lights are a simple, inexpensive way of improving hand hygiene. Brighter lights appear to have a greater effect; however, this must be balanced with annoyance in specific settings. Temperature did not have a significant effect; however, this may be because the relationship does not fit a linear model. Other interventions, such as signs, may need to be tailored specifically to individual hospital environments. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Variation in light intensity with height and time from subsequent lightning return strokes

NASA Technical Reports Server (NTRS)

Jordan, D. M.; Uman, M. A.

1983-01-01

Photographic measurements of relative light intensity as a function of height and time have been conducted for seven return strokes in two lightning flashes at 7.8 and 8.7 km ranges, using film which possesses an approximately constant spectral response in the 300-670 nm range. The amplitude of the initial light peak is noted to decrease exponentially with height, with a decay constant of 0.6-0.8 km. The logarithm of the peak light intensity near the ground is found to be approximately proportional to the initial peak electric field intensity, implying that the current decrease with height may be much slower than the light decrease. Absolute light intensity is presently estimated through the integration of the photographic signals from individual channel segments, in order to simulate the calibrated, all-sky photoelectric data of Guo and Krider (1982).

Pilot Study of the Effects of Ambient Light Level Variation on Spectral Domain Anterior Segment OCT-Derived Angle Metrics in Caucasians versus Asians.

PubMed

Dastiridou, Anna; Marion, Kenneth; Niemeyer, Moritz; Francis, Brian; Sadda, Srinivas; Chopra, Vikas

2018-04-11

To investigate the effects of ambient light level variation on spectral domain anterior segment optical coherence tomography (SD-ΟCT)-derived anterior chamber angle metrics in Caucasians versus Asians. Caucasian (n = 24) and Asian participants of Chinese ancestry (n = 24) with open angles on gonioscopy had one eye imaged twice at five strictly controlled, ambient light levels. Ethnicity was self-reported. Light levels were strictly controlled using a light meter at 1.0, 0.75, 0.5, 0.25, and 0 foot candle illumination levels. SD-OCT 5-line raster scans at the inferior 270° irido-corneal angle were measured by two trained, masked graders from the Doheny Image Reading Center using customized Image-J software. Schwalbe's line-angle opening distance (SL-AOD) and SL-trabecular iris space area (SL-TISA) in different light meter readings (LMRs) between the two groups were compared. Baseline light SL-AOD and SL-TISA measured 0.464 ± 0.115mm/0.351 ± 0.110mm 2 and 0.344 ± 0.118mm/0.257 ± 0.092mm 2 , respectively, in the Caucasian and the Asian group. SL-AOD and SL-TISA in each LMR were significantly larger in the Caucasian group compared to the Asian group (p < 0.05). Despite this difference in angle size between the groups, there were no statistically significant differences in the degree of change in angle parameters from light to dark (% changes in SL-AOD or SL-TISA between the two groups were statistically similar with all p-values >0.3). SL-based angle dimensions using SD-OCT are sensitive to changes in ambient illumination in participants with Caucasian and Asian ancestry. Although Caucasian eyes had larger baseline angle opening under bright light conditions, the light-to-dark change in angle dimensions was similar in the two groups.

Gut microbiota mediates diurnal variation of acetaminophen induced acute liver injury in mice.

PubMed

Gong, Shenhai; Lan, Tian; Zeng, Liyan; Luo, Haihua; Yang, Xiaoyu; Li, Na; Chen, Xiaojiao; Liu, Zhanguo; Li, Rui; Win, Sanda; Liu, Shuwen; Zhou, Hongwei; Schnabl, Bernd; Jiang, Yong; Kaplowitz, Neil; Chen, Peng

2018-07-01

Acetaminophen (APAP) induced hepatotoxicity is a leading cause of acute liver failure worldwide. It is well established that the liver damage induced by acetaminophen exhibits diurnal variation. However, the detailed mechanism for the hepatotoxic variation is not clear. Herein, we aimed to determine the relative contributions of gut microbiota in modulating the diurnal variation of hepatotoxicity induced by APAP. Male Balb/C mice were treated with or without antibiotics and a single dose of orally administered APAP (300 mg/kg) at ZT0 (when the light is on-start of resting period) and ZT12 (when the light is off-start of active period). In agreement with previous findings, hepatic injury was markedly enhanced at ZT12 compared with ZT0. Interestingly, upon antibiotic treatment, ZT12 displayed a protective effect against APAP hepatotoxicity similar to ZT0. Moreover, mice that received the cecal content from ZT12 showed more severe liver damage than mice that received the cecal content from ZT0. 16S sequencing data revealed significant differences in the cecal content between ZT0 and ZT12 in the compositional level. Furthermore, metabolomic analysis showed that the gut microbial metabolites were also different between ZT0 and ZT12. Specifically, the level of 1-phenyl-1,2-propanedione (PPD) was significantly higher at ZT12 than ZT0. Treatment with PPD alone did not cause obvious liver damage. However, PPD synergistically enhanced APAP-induced hepatic injury in vivo and in vitro. Finally, we found Saccharomyces cerevisiae, which could reduce intestinal PPD levels, was able to markedly alleviate APAP-induced liver damage at ZT12. The gut microbial metabolite PPD was responsible, at least in part, for the diurnal variation of hepatotoxicity induced by APAP by decreasing glutathione levels. Acetaminophen (APAP) induced acute liver failure because of over dose is a leading public health problem. APAP-induced liver injury exhibits diurnal variation, specifically APAP causes

Spectral characteristics and meridional variations of energy transformations during the first and second special observation periods of FGGE

NASA Technical Reports Server (NTRS)

Kung, E. C.; Tanaka, H.

1984-01-01

The global features and meridional spectral energy transformation variations of the first and second special observation periods of the First Global GARP Experiment (FGGE) are investigated, together with the latitudinal distribution of the kinetic energy balance. Specific seasonal characteristics are shown by the spectral distributions of the global transformations between (1) zonal mean and eddy components of the available potential energy, (2) the zonal mean and eddy components of the kinetic energy, and (3) the available potential energy and the kinetic energy. Maximum kinetic energy production is found to occur at subtropical latitudes, with a secondary maximum at higher middle latitudes. Between these two regions, there is another region characterized by the adiabatic destruction of kinetic energy above the lower troposphere.

[Variations of solar activity and radiation situation on board MIR station during the period 1986-1994].

PubMed

Bondarenko, V A; Mitrikas, V G; Tsetlin , V V

1995-01-01

This paper is dedicated to the analysis of the radiation situation onboard Mir station over a period of 1986-1994, there examined the main cosmophysics parameters and indices of the solar activity as well as the variations of the parameters of the earth's magnetic field and their association with the changes in the power of absorbed dose onboard the station. There noted the high levels of radiation exposure to the cosmonauts under terrestrial conditions when carrying out the roentgeno-radiologic examinations and procedures comparable or exceeding the absorbed doses during the flights. For revealing the regular associations of the radiation situation onboard the station with the parameters of solar activity there has been analyzed the time changes of average monthly values of dose power since the beginning of station functioning in 1986 until returning the fifteenth expedition to Earth. From the analyses of the results it might be assumed that the best statistical associations of average monthly power of the absorbed dose are found with the streams of protons of GCR. Wolff numbers and background stream of the radio emission of the Sun which reflects the existence of the radiation situation upon the phase of solar activity cycle. From this paper it transpires that calculating the dose loads during the period of the extreme phases of solar activity, it is possible to make between them the interpolations of time dependence by analogy with the dynamics in time of the background streams of GCR or Wolff numbers.

Is the Sun a Long Period Variable

NASA Technical Reports Server (NTRS)

Sonett, Charles P.

1990-01-01

The inventory of atmospheric radiocarbon exhibits quasi-periodic variations of mean period of bar-lambda=269 years over the entire 9000 year record. But the period is inconstant and subject to random variability (sigma m exp. 1/2 = 119 years). The radiocarbon maxima correspond to the quasiperiodic extension of the Maunder minimum throughout the Holocene and resolve the long-standing issue of Maunder cyclicity. The radiocarbon maxima are amplitude modulated by the approx. 2300 year period and thus vary significantly in peak value. The approx. 2300 year period in turn appears to not be modulated by the secular geomagnetic variation. Detection of a Maunder-like sequence of minima in tree ring growth of Bristlecone pine and its correlation with the Maunder (1890, 1922) cyclicity in the radiocarbon record supports the inference that solar forcing of the radiocarbon record is accompanied by a corresponding forcing of growth of timberline Bristlecone pine. Because of the random component of the Maunder period, prediction of climate, if tied to the Maunder cycle other than probabilistically, is significantly hindered. For the mean Maunder period of 269 years, the probability is 67 percent that a given climatic maximum lies anywhere between 150 and 388 years.

THE KEPLER LIGHT CURVE OF THE UNIQUE DA WHITE DWARF BOKS 53856

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holberg, J. B.; Howell, Steve B., E-mail: holberg@argus.lpl.arizona.edu, E-mail: howell@noao.edu

2011-08-15

The faint (g = 16.9) hot white dwarf BOKS 53856 was observed by the Kepler Mission in short cadence mode during mid-2009. Analysis of these observations reveals a highly stable modulation with a period of 6.1375 hr and a 2.46% half-amplitude. The folded light curve has an unusual shape that is difficult to explain in terms of a binary system containing an unseen companion more luminous than an L0 brown dwarf. Optical spectra of BOKS 53856 show a T{sub eff} = 34,000 K, log g = 8.0 DA white dwarf. There are few, if any, known white dwarfs in thismore » temperature range exhibiting photometric variations similar to those we describe. A magnetic spin-modulated white dwarf model can in principle explain the light curve, an interpretation supported by spectral observations of the H{alpha} line showing evidence of Zeeman splitting.« less

No Timing Variations Observed in Third Transit of Snow-line Exoplanet Kepler-421b

NASA Astrophysics Data System (ADS)

Dalba, Paul A.; Muirhead, Philip S.

2016-07-01

We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler spacecraft only observed two transits of Kepler-421b, leaving the planet’s transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3 m Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b, barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion, and find that a transit model with no TTVs is favored to 3.6σ confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.

Characterization and long term operation of a novel superconducting undulator with 15 mm period length in a synchrotron light source

NASA Astrophysics Data System (ADS)

Casalbuoni, S.; Cecilia, A.; Gerstl, S.; Glamann, N.; Grau, A. W.; Holubek, T.; Meuter, C.; de Jauregui, D. Saez; Voutta, R.; Boffo, C.; Gerhard, Th.; Turenne, M.; Walter, W.

2016-11-01

A new cryogen-free full scale (1.5 m long) superconducting undulator with a period length of 15 mm (SCU15) has been successfully tested in the ANKA storage ring. This represents a very important milestone in the development of superconducting undulators for third and fourth generation light sources carried on by the collaboration between the Karlsruhe Institute of Technology and the industrial partner Babcock Noell GmbH. SCU15 is the first full length device worldwide that with beam reaches a higher peak field than what expected with the same geometry (vacuum gap and period length) with an ideal cryogenic permanent magnet undulator built with the best material available PrFeB. After a summary on the design and main parameters of the device, we present here the characterization in terms of spectral properties and the long term operation of the SCU15 in the ANKA storage ring.

Determining the Rotation Periods of an Inactive LEO Satellite and the First Korean Space Debris on GEO, KOREASAT 1

NASA Astrophysics Data System (ADS)

Choi, Jin; Jo, Jung Hyun; Kim, Myung-Jin; Roh, Dong-Goo; Park, Sun-Youp; Lee, Hee-Jae; Park, Maru; Choi, Young-Jun; Yim, Hong-Suh; Bae, Young-Ho; Park, Young-Sik; Cho, Sungki; Moon, Hong-Kyu; Choi, Eun-Jung; Jang, Hyun-Jung; Park, Jang-Hyun

2016-06-01

Inactive space objects are usually rotating and tumbling as a result of internal or external forces. KOREASAT 1 has been inactive since 2005, and its drift trajectory has been monitored with the optical wide-field patrol network (OWL-Net). However, a quantitative analysis of KOREASAT 1 in regard to the attitude evolution has never been performed. Here, two optical tracking systems were used to acquire raw measurements to analyze the rotation period of two inactive satellites. During the optical campaign in 2013, KOREASAT 1 was observed by a 0.6 m class optical telescope operated by the Korea Astronomy and Space Science Institute (KASI). The rotation period of KOREASAT 1 was analyzed with the light curves from the photometry results. The rotation periods of the low Earth orbit (LEO) satellite ASTRO-H after break-up were detected by OWL-Net on April 7, 2016. We analyzed the magnitude variation of each satellite by differential photometry and made comparisons with the star catalog. The illumination effect caused by the phase angle between the Sun and the target satellite was corrected with the system tool kit (STK) and two line element (TLE) technique. Finally, we determined the rotation period of two inactive satellites on LEO and geostationary Earth orbit (GEO) with light curves from the photometry. The main rotation periods were determined to be 5.2 sec for ASTRO-H and 74 sec for KOREASAT 1.

Testing the recovery of stellar rotation signals from Kepler light curves using a blind hare-and-hounds exercise

NASA Astrophysics Data System (ADS)

Aigrain, S.; Llama, J.; Ceillier, T.; Chagas, M. L. das; Davenport, J. R. A.; García, R. A.; Hay, K. L.; Lanza, A. F.; McQuillan, A.; Mazeh, T.; de Medeiros, J. R.; Nielsen, M. B.; Reinhold, T.

2015-07-01

We present the results of a blind exercise to test the recoverability of stellar rotation and differential rotation in Kepler light curves. The simulated light curves lasted 1000 d and included activity cycles, Sun-like butterfly patterns, differential rotation and spot evolution. The range of rotation periods, activity levels and spot lifetime were chosen to be representative of the Kepler data of solar-like stars. Of the 1000 simulated light curves, 770 were injected into actual quiescent Kepler light curves to simulate Kepler noise. The test also included five 1000-d segments of the Sun's total irradiance variations at different points in the Sun's activity cycle. Five teams took part in the blind exercise, plus two teams who participated after the content of the light curves had been released. The methods used included Lomb-Scargle periodograms and variants thereof, autocorrelation function and wavelet-based analyses, plus spot modelling to search for differential rotation. The results show that the `overall' period is well recovered for stars exhibiting low and moderate activity levels. Most teams reported values within 10 per cent of the true value in 70 per cent of the cases. There was, however, little correlation between the reported and simulated values of the differential rotation shear, suggesting that differential rotation studies based on full-disc light curves alone need to be treated with caution, at least for solar-type stars. The simulated light curves and associated parameters are available online for the community to test their own methods.

Identification and period investigation of pulsation variable star UY Camelopardalis, an RR Lyrae star in binary system

NASA Astrophysics Data System (ADS)

Li, Lin-Jia; Qian, Sheng-Bang; Voloshina, Irina; Metlov, Vladimir G.; Zhu, Li-Ying; Liao, Wen-Ping

2018-06-01