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Search Results: 1 - 10 of 582912 matches for " A. D. Moy "
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Borehole temperatures reveal a changed energy budget at Mill Island, East Antarctica, over recent decades
J. L. Roberts,A. D. Moy,T. D. van Ommen,M. A. J. Curran
The Cryosphere , 2013, DOI: 10.5194/tc-7-263-2013
Abstract: A borehole temperature record from the Mill Island (East Antarctica) icecap reveals a large surface warming signal manifested as a 0.75 K temperature difference over the approximate 100 m depth in the zone of zero annual amplitude below the seasonally varying zone. The temperature profile shows a break in gradient around 49 m depth, which we model with inverse numerical simulations, indicating that surface warming started around the austral summer of 1980/81 AD ±5 yr. This warming of approximately 0.37 K per decade is consistent with trends seen in both instrumental and other reconstructions for Antarctica and, therefore, suggests that regional- rather than local-scale processes are largely responsible. Alteration of the surface energy budget arising from changes in radiation balances due to local cloud, the amount of liquid deposition and local air temperatures associated with altered air/sea exchanges also potentially plays a role at this location due to the proximity of the Shackleton Ice Shelf and sea-ice zone.
Borehole temperatures reveal a changed energy budget at Mill Island, East Antarctica over recent decades
J. L. Roberts,A. D. Moy,T. D. van Ommen,M. A. J. Curran
The Cryosphere Discussions , 2012, DOI: 10.5194/tcd-6-2575-2012
Abstract: A borehole temperature record from the Mill Island (East Antarctic) icecap reveals a large surface warming signal manifested as a 0.75 K temperature difference over the approximate 100 m depth below the seasonally varying zone. The temperature profile shows a break in gradient between 49 and 69 m depth, which we model with inverse numerical simulations, indicating that surface warming started around the austral summer of 1980/1981 AD ± 5 yr. This warming of approximately 0.37 K per decade is large by Antarctic standards and is only exceeded in regions of the Antarctic Peninsula. While this warming may reflect regional scale air temperature increases, the lack of comparable trends for other East Antarctic sites suggests local influences are largely responsible for the observed trend. Alteration of the surface energy budget arising from changes in radiation balances due to local cloud, the amount of liquid deposition and local air temperatures associated with altered air/sea exchanges potentially play a key role at this location due to the proximity of the Shackleton Ice Shelf and sea-ice zone.
Interannual variability of pteropod shell weights in the high-CO2 Southern Ocean
D. Roberts,W. R. Howard,A. D. Moy,J. L. Roberts
Biogeosciences Discussions , 2008,
Abstract: Anthropogenic inputs of CO2 are altering ocean chemistry and may alter the role of marine calcifiers in ocean ecosystems. CO2 emissions over the coming centuries may produce changes in ocean pH not seen for millions of years. Laboratory evidence has shown decreased calcification in some species of coccolithophores, foraminifera, corals and pteropods in response to CO2 enrichment. However, in situ observations of calcification in marine organisms are limited, especially for the aragonitic pteropods. This group of pelagic molluscs are likely to be more sensitive to changes in carbonate chemistry than calcite producers such as foraminifera and coccolithophores. Here we present observations of pteropod shell-weight and flux from 1997–2006 in sediment traps deployed at 47° S, 142° E at 2000 meters below sea surface in the Southern Ocean. A decadal trend of –1.17±0.47 μg yr 1 (P=0.02) in mean shell weight in the pteropod Limacina helicina antarctica forma antarctica suggests a small but detectable reduction in calcification. Gaps in the data make it difficult to state with certainty the significance of the trend. However, this data set represents the first attempt to estimate interannual variations in pteropod calcification and establish a benchmark against which future impacts of ocean acidification may be detected. Contributions of Limacina helicina antarctica morphotypes to the total pteropod flux were also reduced over the decade. We suggest these small though discernible trends are due to changing carbonate chemistry in the Subantarctic, as other oceanographic variables show no clear decadal trends. With CO2 continuing to enter the ocean such impacts on pteropods and other marine calcifiers could result in changes to the distribution of species and the structure of Southern Ocean ecosystems.
The 10 sea urchin receptor for egg jelly proteins (SpREJ) are members of the polycystic kidney disease-1 (PKD1) family
H Jayantha Gunaratne, Gary W Moy, Masashi Kinukawa, Shinji Miyata, Silvia A Mah, Victor D Vacquier
BMC Genomics , 2007, DOI: 10.1186/1471-2164-8-235
Abstract: The 10 full-length SpREJ cDNA sequences were determined. The secondary structures of their deduced proteins were predicted and compared to the five human hPKD1 proteins. The genomic structures of the 10 SpREJs show low similarity to each other. All 10 SpREJs are transcribed in either embryos or adult tissues. SpREJs show distinct patterns of expression during embryogenesis. Adult tissues show tissue-specific patterns of SpREJ expression.Possession of a REJ domain of about 600 residues defines this family. Except for SpREJ1 and 3, that are thought to be associated with the sperm acrosome reaction, the functions of the other SpREJ proteins remain unknown. The sea urchin genome is one-fourth the size of the human genome, but sea urchins have 10 SpREJ proteins, whereas humans have five. Determination of the tissue specific function of each of these proteins will be of interest to those studying echinoderm development. Sea urchins are basal deuterostomes, the line of evolution leading to the vertebrates. The study of individual PKD1 proteins will increase our knowledge of the importance of this gene family.The sea urchin is a model animal for cell and developmental biology and genomics. As a basal deuterostome, it provides an out-group for the chordates, and thus insights into vertebrate genome evolution. The genome of the purple sea urchin, Strongylocentrotus purpuratus (Sp), is one-quarter the size of the human genome and encodes ~23,300 genes [1], the majority having vertebrate orthologs. Sea urchin genes are closer to human and mouse than to other invertebrate models such as Drosophila and C. elegans. For example, the number of reciprocal pairs of genes between sea urchin and mouse is about 50% greater than between sea urchin and Drosophila [1]. The sea urchin lacks four of the human kinase subfamilies, while Drosophila lacks 20 and nematodes 30 [1,2]. Regarding gene conservation, 11 of the 13 known animal Wnt genes are present in the sea urchin [3]. The sea urchin h
On the Growth of the Counting Function of Stanley Sequences
Richard A. Moy
Mathematics , 2010, DOI: 10.1016/j.disc.2010.12.019
Abstract: Given a finite set of nonnegative integers A with no 3-term arithmetic progressions, the Stanley sequence generated by A, denoted S(A), is the infinite set created by beginning with A and then greedily including strictly larger integers which do not introduce a 3-term arithmetic progressions in S(A). Erdos et al. asked whether the counting function, S(A,x), of a Stanley sequence S(A) satisfies S(A,x)>x^{1/2-\epsilon} for every \epsilon>0 and x>x_0(\epsilon,A). In this paper we answer this question in the affirmative; in fact, we prove the slightly stronger result that S(A,x)\geq (\sqrt{2}-\epsilon)\sqrt{x} for x\geq x_0(\epsilon,A).
A systematic study of polarized electron emission from strained GaAs/GaAsP superlattice photocathodes
T. Maruyama,D. -A. Luh,A. Brachmann,J. E. Clendenin,E. L. Garwin,S. Harvey,J. Jiang,R. E. Kirby,C. Y. Prescott,R. Prepost,A. M. Moy
Physics , 2004, DOI: 10.1063/1.1795358
Abstract: Spin-polarized electron photoemission has been studied for GaAs/GaAs$_{1-x}$P$_x$ strained superlattice cathodes grown by gas-source molecular beam epitaxy. The superlattice structural parameters are systematically varied to optimize the photoemission characteristics. The heavy-hole and light-hole transitions are reproducibly observed in quantum efficiency spectra, enabling direct measurement of the band energies and the energy splitting. Electron-spin polarization as high as 86% with over 1% quantum efficiency has been observed.
There Exist Non-CM Hilbert Modular Forms of Partial Weight 1
Richard A. Moy,Joel Specter
Mathematics , 2014,
Abstract: In this note, we prove that there exists a classical Hilbert modular cusp form over Q(\sqrt{5}) of partial weight one which does not arise from the induction of a Grossencharacter from a CM extension of Q(\sqrt{5}).
Novel structures in Stanley sequences
Richard A. Moy,David Rolnick
Computer Science , 2015,
Abstract: Given a set of integers with no three in arithmetic progression, we construct a Stanley sequence by adding integers greedily so that no arithmetic progression is formed. This paper offers two main contributions to the theory of Stanley sequences. First, we characterize well-structured Stanley sequences as solutions to constraints in modular arithmetic, defining the modular Stanley sequences. Second, we introduce the basic Stanley sequences, where elements arise as the sums of subsets of a basis sequence, which in the simplest case is the powers of 3. Applications of our results include the construction of Stanley sequences with arbitrarily large gaps between terms, answering a weak version of a problem by Erd\H{o}s et al. Finally, we generalize many results about Stanley sequences to $p$-free sequences, where $p$ is any odd prime.
The last deglaciation: timing the bipolar seesaw
J. B. Pedro, T. D. van Ommen, S. O. Rasmussen, V. I. Morgan, J. Chappellaz, A. D. Moy, V. Masson-Delmotte,M. Delmotte
Climate of the Past (CP) & Discussions (CPD) , 2011,
Abstract: Precise information on the relative timing of north-south climate variations is a key to resolving questions concerning the mechanisms that force and couple climate changes between the hemispheres. We present a new composite record made from five well-resolved Antarctic ice core records that robustly represents the timing of regional Antarctic climate change during the last deglaciation. Using fast variations in global methane gas concentrations as time markers, the Antarctic composite is directly compared to Greenland ice core records, allowing a detailed mapping of the inter-hemispheric sequence of climate changes. Consistent with prior studies the synchronized records show that warming (and cooling) trends in Antarctica closely match cold (and warm) periods in Greenland on millennial timescales. For the first time, we also identify a sub-millennial component to the inter-hemispheric coupling. Within the Antarctic Cold Reversal the strongest Antarctic cooling occurs during the pronounced northern warmth of the B lling. Warming then resumes in Antarctica, potentially as early as the Intra-Aller d Cold Period, but with dating uncertainty that could place it as late as the onset of the Younger Dryas stadial. There is little-to-no time lag between climate transitions in Greenland and opposing changes in Antarctica. Our results lend support to fast acting inter-hemispheric coupling mechanisms, including recently proposed bipolar atmospheric teleconnections and/or rapid bipolar ocean teleconnections.
Infrared spectroscopy of faint 15 micron sources in the Hubble Deep Field South: first hints at the properties of the sources of the IR background
A. Franceschini,S. Berta,D. Rigopoulou,H. Aussel,C. J. Cesarsky,D. Elbaz,R. Genzel,E. Moy,S. Oliver,M. Rowan-Robinson,P. P. Van der Werf
Physics , 2003, DOI: 10.1051/0004-6361:20030351
Abstract: We present a spectroscopic analysis of 21 galaxies with z=0.2-1.5 drawn from a 25 sq. arcmin ultra-deep 15 micron ISOCAM survey centered in the HDFS. VLT/ISAAC spectra are reported for 18 sources, aimed at detecting the redshifted Ha. Optical data come from VLT/FORS2 and NTT/EMMI. Ha line emission is detected in all the observed objects. Our analysis of emission lines, morphology, and SEDs shows evidence for AGN in only two of these sources. The Ha luminosities indicate star formation rates (SFR) between 0.5 and 20 Msun, without extinction corrections. We find good correlations between the mid-IR, the radio and Ha luminosities, confirming the mid-IR light as a good tracer of star formation (while SFR based on Ha flux show large scatter and offset, still to be understood). We have estimated the baryonic masses in stars by fitting the optical-IR SED, and found that the host galaxies of ISO sources are massive members of groups with SFR=10 to 300 Msun/yr. We have finally compared this ongoing SF activity with the already formed stellar masses to estimate the timescales t(SF) for the stellar build-up, which turn-out to be widely spread between 0.1 Gyrs to more than 10 Gyr. The faint ISOCAM galaxies appear to form a composite population, including moderately active but very massive spiral-like galaxies, and very luminous ongoing starbursts, in a continuous sequence. From the observed t(SF), assuming typical starburst timescales, we infer that, with few exceptions, only a fraction of the galactic stars can be formed in any single starburst, while several of such episodes during a protracted SF history are required for the whole galactic build-up.
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