3,695 research outputs found
Biogeochemical variations at the Porcupine Abyssal Plain sustained Observatory in the northeast Atlantic Ocean, from weekly to inter-annual timescales
We present high-resolution autonomous measurements of carbon dioxide partial pressure p(CO2) taken in situ at the Porcupine Abyssal Plain sustained Observatory (PAP-SO) in the northeast Atlantic (49° N, 16.5° W; water depth of 4850 m) for the period 2010–2012. Measurements of p(CO2) made at 30 m depth on a sensor frame are compared with other autonomous biogeochemical measurements at that depth (including chlorophyll a fluorescence and nitrate concentration data) to analyse weekly to seasonal controls on p(CO2) flux in the inter-gyre region of the North Atlantic. Comparisons are also made with in situ regional time series data from a ship of opportunity and mixed layer depth (MLD) measurements from profiling Argo floats. There is a persistent under-saturation of CO2 in surface waters throughout the year which gives rise to a perennial CO2 sink. Comparison with an earlier data set collected at the site (2003–2005) confirms seasonal and inter-annual changes in surface seawater chemistry. There is year-to-year variability in the timing of deep winter mixing and the intensity of the spring bloom.The 2010–2012 period shows an overall increase in p(CO2) values when compared to the 2003–2005 period as would be expected from increases due to anthropogenic CO2 emissions. The surface temperature, wind speed and MLD measurements are similar for both periods of time. Future work should incorporate daily CO2 flux measurements made using CO2 sensors at 1 m depth and the in situ wind speed data now available from the UK Met Office Buoy
Relaxed 2-D Principal Component Analysis by Norm for Face Recognition
A relaxed two dimensional principal component analysis (R2DPCA) approach is
proposed for face recognition. Different to the 2DPCA, 2DPCA- and G2DPCA,
the R2DPCA utilizes the label information (if known) of training samples to
calculate a relaxation vector and presents a weight to each subset of training
data. A new relaxed scatter matrix is defined and the computed projection axes
are able to increase the accuracy of face recognition. The optimal -norms
are selected in a reasonable range. Numerical experiments on practical face
databased indicate that the R2DPCA has high generalization ability and can
achieve a higher recognition rate than state-of-the-art methods.Comment: 19 pages, 11 figure
A smoother end to the dark ages
Independent lines of evidence suggest that the first stars, which ended the
cosmic dark ages, came in pairs, rather than singly. This could change the
prevailing view that the early Universe had a Swiss-cheese-like appearance.Comment: Nature News and Views, April 7, 201
FLEET: Butterfly Estimation from a Bipartite Graph Stream
We consider space-efficient single-pass estimation of the number of
butterflies, a fundamental bipartite graph motif, from a massive bipartite
graph stream where each edge represents a connection between entities in two
different partitions. We present a space lower bound for any streaming
algorithm that can estimate the number of butterflies accurately, as well as
FLEET, a suite of algorithms for accurately estimating the number of
butterflies in the graph stream. Estimates returned by the algorithms come with
provable guarantees on the approximation error, and experiments show good
tradeoffs between the space used and the accuracy of approximation. We also
present space-efficient algorithms for estimating the number of butterflies
within a sliding window of the most recent elements in the stream. While there
is a significant body of work on counting subgraphs such as triangles in a
unipartite graph stream, our work seems to be one of the few to tackle the case
of bipartite graph streams.Comment: This is the author's version of the work. It is posted here by
permission of ACM for your personal use. Not for redistribution. The
definitive version was published in Seyed-Vahid Sanei-Mehri, Yu Zhang, Ahmet
Erdem Sariyuce and Srikanta Tirthapura. "FLEET: Butterfly Estimation from a
Bipartite Graph Stream". The 28th ACM International Conference on Information
and Knowledge Managemen
Cultivation possibilities of some common beans varieties under second crop conditions
This research was carried to determine the yield and yield components on some common bean (Phaseolus vulgaris) varieties in 2017 and 2018 years, in Diyarbakir, southeast Anatolia of Turkey. In the experiment, Onceler-98, Karacasehir-90, Yunus-90, Akman-98,
Goynuk-98, Aras-98, Terzibaba, Adabeyazi, Cihan and Noyanbey cultivars were used. Experiment was set up in randomized complete block design with three replications. Plots were 6 m length with five rows, the inter-row and intra-row spacing were 0.7 m and 0.10 m. Seeds were sown after wheat harvest as second crops. The differences among cultivars were significant for number of days of flowering and maturity, plant height,
number of pods and seeds per plant, grain yield and 100 seed weight. Number of days to flowering ranged from 48.0 to 62.8; number of days to maturity ranged from 99.8 to 113.8. The number of pods and seeds per plant varied from 12.8 to 30.8, and 24.3 to 105.6, respectively. Grain yield ranged from 792.3 kg ha-1 (Cihan and Noyanbey) to 2709 kg ha-1 (Goynuk-98 and Onceler-98). In the experiment area, high heat temperature and high evaporation throughout July and August, negatively affected the blooming, pollination and fertilization on cultivars of dwarf and determinate plant habit types. Brushy type and late-maturing varieties should be preferred under second crop conditions
Mne1 Is a Novel Component of the Mitochondrial Splicing Apparatus Responsible for Processing of a \u3ci\u3eCOX1\u3c/i\u3e Group I Intron in Yeast
Saccharomyces cerevisiae cells lacking Mne1 are deficient in
intron splicing in the gene encoding the Cox1 subunit of cytochrome
oxidase but contain wild-type levels of the bc1 complex.
Thus, Mne1 has no role in splicing of COB introns or expression
of the COB gene. Northern experiments suggest that splicing of
the COX1 aI5β intron is dependent on Mne1 in addition to the
previously known Mrs1, Mss116, Pet54, and Suv3 factors. Processing
of the aI5_ intron is similarly impaired in mne1∆ and
mrs1∆ cells and overexpression of Mrs1 partially restores the
respiratory function of mne1∆ cells. Mrs1 is known to function
in the initial transesterification reaction of splicing. Mne1 is a
mitochondrial matrix protein loosely associated with the inner
membrane and is found in a high mass ribonucleoprotein complex
specifically associated with the COX1 mRNA even within
an intronless strain. Mne1 does not appear to have a secondary
function in COX1 processing or translation, because disruption
of MNE1 in cells containing intronless mtDNA does not lead to
a respiratory growth defect. Thus, the primary defect in mne1∆
cells is splicing of the aI5β intron in COX1
Feedback from the IR Background in the Early Universe
It is commonly believed that the earliest stages of star-formation in the
Universe were self-regulated by global radiation backgrounds - either by the
ultraviolet Lyman-Werner (LW) photons emitted by the first stars (directly
photodissociating H_2), or by the X-rays produced by accretion onto the black
hole (BH) remnants of these stars (heating the gas but catalyzing H_2
formation). Recent studies have suggested that a significant fraction of the
first stars may have had low masses (a few M_sun). Such stars do not leave BH
remnants and they have softer spectra, with copious infrared (IR) radiation at
photon energies around 1eV. Similar to LW and X-ray photons, these photons have
a mean-free path comparable to the Hubble distance, building up an early IR
background. Here we show that if soft-spectrum stars, with masses of a few
M_sun, contributed more than 1% of the UV background (or their mass fraction
exceeded 90%), then their IR radiation dominated radiative feedback in the
early Universe. The feedback is different from the UV feedback from high-mass
stars, and occurs through the photo-detachment of H^- ions, necessary for
efficient H_2 formation. Nevertheless, we find that the baryon fraction which
must be incorporated into low-mass stars in order to suppress H_2-cooling is
only a factor of few higher than for high-mass stars.Comment: Accepted for publication in MNRAS (Letters). 5 pages with 2 figure
Security and Efficiency Analysis of the Hamming Distance Computation Protocol Based on Oblivious Transfer
open access articleBringer et al. proposed two cryptographic protocols for the computation of Hamming distance. Their first scheme uses Oblivious Transfer and provides security in the semi-honest model. The other scheme uses Committed Oblivious Transfer and is claimed to provide full security in the malicious case. The proposed protocols have direct implications to biometric authentication schemes between a prover and a verifier where the verifier has biometric data of the users in plain form.
In this paper, we show that their protocol is not actually fully secure against malicious adversaries. More precisely, our attack breaks the soundness property of their protocol where a malicious user can compute a Hamming distance which is different from the actual value. For biometric authentication systems, this attack allows a malicious adversary to pass the authentication without knowledge of the honest user's input with at most complexity instead of , where is the input length. We propose an enhanced version of their protocol where this attack is eliminated. The security of our modified protocol is proven using the simulation-based paradigm. Furthermore, as for efficiency concerns, the modified protocol utilizes Verifiable Oblivious Transfer which does not require the commitments to outputs which improves its efficiency significantly
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