76,280 research outputs found
Ecological Impact of Tsunami on the nearshore western coasts of Kerala and Tamil Nadu
No full textDeapartment of Ocean Development (DOD), Government of IndiaUnpublishedope
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
Mechanistic and synthetic studies on the prochlorosin and cytolysin families of lanthipeptides
No full textPeptides are an attractive class of therapeutics, occupying a niche between small molecules and biologics. Research in the van der Donk lab focuses on lanthipeptides, a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) that commonly feature antibacterial activity and contain the characteristic thioether residues lanthionine (Lan) and methyllanthionine (MeLan). Installation of thioether crosslinks in lanthipeptide biosynthesis is carried out by designated synthetases and involves dehydration of Ser/Thr residues and cyclization via Michael-type addition.
The remarkably broad substrate scope of the synthetase ProcM inspired us to explore its mechanism in detail (chapter 2). My studies on ProcM revealed the directionality of dehydration, the order of cyclization, and that, despite the impressive substrate scope, none of the cyclizations are non-enzymatic. In collaboration, we established the irreversibility of the Michael-type addition and proposed that the topology of the thioether rings is under kinetic control. Solid phase peptide synthesis (SPPS) was used to generate the substrates to study ProcM, and is also a flexibile tool to access non-native lanthipeptide analogues. Interestingly, a lanthipeptide, cytolysin S (CylLS”), exhibited cytolytic activity in synergy with cytolysin L (CylLL”). Given that a thioether crosslink in CylLS” has an unusual LL-stereochemistry, the synthesis of a diastereomer of CylLS” with the more common DL-stereochemistry was achieved by SPPS (chapter 3). We probed whether the cytolytic activity depended on the LL-stereochemistry observed in CylLS”. Surprisingly, the unusual LL-stereochemistry was found to be important for the antibacterial activity, but not necessary for the hemolytic activity of CylLS”. I have also synthesized another hydrophobic lanthipeptide analogue, the portion of microbisporicin that contains the A and B ring (chapter 4). We established that this motif is not recognized by the
halogenase MibH, and that the C terminus of microbisporicin is necessary for the chlorination by MibH.
During my graduate studies, I had the opportunity to collaborate in a different area of research in our laboratory, the phosphonates. My efforts in the syntheses of various substrates and intermediates were instrumental in elucidating the biosynthetic pathways of dehydrophos, fosfazinomycin, and rhizocticin (chapter 5).Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2017-12-01The student, Subha Mukherjee, accepted the attached license on 2015-09-16 at 09:51.The student, Subha Mukherjee, submitted this Dissertation for approval on 2015-09-16 at 10:30.This Dissertation was approved for publication on 2015-09-17 at 16:49.DSpace SAF Submission Ingestion Package generated from Vireo submission #8689 on 2016-03-02 at 14:12:02Made available in DSpace on 2016-03-02T20:57:20Z (GMT). No. of bitstreams: 5
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Prompt charm production in pp collisions at √<span style="text-decoration:overline">s</span>=7 TeV
No full textCharm production at the LHC in pp collisions at s√=7 TeV is studied with the LHCb detector. The decays D0→K−π+, D+→K−π+π+, D⁎+→D0(K−π+)π+, D+s→ϕ(K−K+)π+, Λ+c→pK−π+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb−1. Differential cross-sections dσ/dpT are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0<pT<8 GeV/c and 2.0<y<4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above pT-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives
σ(cc¯)pT<8 GeV/c,2.0<y<4.5=1419±12(stat)±116(syst)±65(frag) μb,
where the uncertainties are statistical, systematic, and due to the fragmentation functions
Seed source and region effects on growth rate and survival of blue spruce (Picea pungens) Christmas trees in New Jersey
No full textSeedlings from five different seed sources of blue spruce Christmas trees were planted at five sites throughout New Jersey. Two sites in northern New Jersey and one in central New Jersey had significantly higher survival rates than the two in southern New Jersey. Additionally, the two sites in northern New Jersey had significantly faster growth rates than those in southern and central New Jersey. There were no significant differences in survival rates between seed sources. In terms of growth rates, however, seedlings from seeds obtained in Santa Fe National Forest, New Mexico grew significantly faster than seedlings from the other seed sources tested. This forther growth rate is predicted to shorten the time needed to reach marketability size by one to five years
Measurement of the inclusive φ cross-section in pp collisions at √s=7 TeV
No full textThe cross-section for inclusive φ meson production in pp collisions at a centre-of-mass energy of √s = 7 TeV has been measured with the LHCb detector at the Large Hadron Collider. The differential cross-section is measured as a function of the φ transverse momentum pT and rapidity y in the region 0.6< pT <5.0 GeV/c and 2.44< y <4.06. The cross-section for inclusive φ production in this kinematic range is σ(pp→φX)=1758±19(stat) +43−14(syst)±182(scale) μb, where the first systematic uncertainty depends on the pT and y region and the second is related to the overall scale. Predictions based on the Pythia 6.4 generator underestimate the cross-section
Review of “St. Clive:” An Eastern Orthodox Author Looks Back at C. S. Lewis
No full textReview of C. J. S. Hayward, “St. Clive:” An Eastern Orthodox Author Looks Back at C. S. Lewis (Wheaton, Illinois: C. J. S. Hayward Publications, 2000-19). 381 pages. $49.99. ISBN 9781794669956
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment in
proton–proton collisions at a centre-of-mass energy of
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
APC/C and SCFcyclin F Constitute a Reciprocal Feedback Circuit Controlling S-Phase Entry
No full textSummaryThe anaphase promoting complex/cyclosome (APC/C) is an ubiquitin ligase and core component of the cell-cycle oscillator. During G1 phase, APC/C binds to its substrate receptor Cdh1 and APC/CCdh1 plays an important role in restricting S-phase entry and maintaining genome integrity. We describe a reciprocal feedback circuit between APC/C and a second ubiquitin ligase, the SCF (Skp1-Cul1-F box). We show that cyclin F, a cell-cycle-regulated substrate receptor (F-box protein) for the SCF, is targeted for degradation by APC/C. Furthermore, we establish that Cdh1 is itself a substrate of SCFcyclin F. Cyclin F loss impairs Cdh1 degradation and delays S-phase entry, and this delay is reversed by simultaneous removal of Cdh1. These data indicate that the coordinated, temporal ordering of cyclin F and Cdh1 degradation, organized in a double-negative feedback loop, represents a fundamental aspect of cell-cycle control. This mutual antagonism could be a feature of other oscillating systems
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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