2,319 research outputs found
Sea ice inhabiting Harpacticoida (Crustacea, Copepoda) of the Weddell Sea (Antarctica)
Five species of harpacticoid copepods belonging to three families and four genera were collected from various samples of sea ice taken during five cruises of RV Polarstern to the Weddell Sea from 1985-89. One species is new and described, namely Hastigerella antarctica sp. n. Drescheriella racovitzai comb. n. (Griesbrecht, 1902), Harpacticus furcifer Giesbrecht, 1902 and Idomene antarctica (Giesbrecht, 1902) are redescribed. The fourth nauplius of an unknown representative of Ectinosomatidae is described as well as three naupliar stages of Harpacticus furcifer
One Hundred Years of Philosophy of Science: The View from Munich
These days, a number of philosophers of science indulge in lamenting about a crisis of their discipline. They complain about its loss of relevance, and bemoan the mar gi na lization of their dis cipline in the philosophical community and in the wider academia , Hardcastle and Richardson ). The Munich take on the philosophy of science does not succumb to this temptation. According to it, philosophy of science is well and alive. In Carlos Ulises Moulines’s Die Entwicklung der modernen Wissen schaftstheorie Eine historische Einführung the word “crisis” is used only in reference to the 1940s when clas sical logical positivism encountered some dif fi culties in dealing with problems concerning veri fi cation, the ana ly tic/synthetic distinction, and similar conundrums. For Moulines, “crisis” is not a word that applies to contemporary philosophy of scienc
Electromagnetic probes
We introduce the seminal developments in the theory and experiments of
electromagnetic probes for the study of the dynamics of relativistic heavy ion
collisions and quark gluon plasma.Comment: 47 pages, 33 Figures; Lectures delivered by Dinesh K. Srivastava at
QGP Winter School (QGPWS08) at Jaipur, India, February 1-3, 200
Naupliar and Metanaupliar development of Thysanoessa raschii (Malacostraca, Euphausiacea) from Godthåbsfjord, Greenland, with a reinstatement of the ancestral status of the free-living Nauplius in Malacostracan evolution
The presence of a characteristic crustacean larval type, the nauplius, in many crustacean taxa has often been considered one of the few uniting characters of the Crustacea. Within Malacostraca, the largest crustacean group, nauplii are only present in two taxa, Euphauciacea (krill) and Decapoda Dendrobranchiata. The presence of nauplii in these two taxa has traditionally been considered a retained primitive characteristic, but free-living nauplii have also been suggested to have reappeared a couple of times from direct developing ancestors during malacostracan evolution. Based on a re-study of Thysanoessa raschii (Euphausiacea) using preserved material collected in Greenland, we readdress this important controversy in crustacean evolution, and, in the process, redescribe the naupliar and metanaupliar development of T. raschii. In contrast to most previous studies of euphausiid development, we recognize three (not two) naupliar (= ortho-naupliar) stages (N1-N3) followed by a metanauplius (MN). While there are many morphological changes between nauplius 1 and 2 (e.g., appearance of long caudal setae), the changes between nauplius 2 and 3 are few but distinct. They involve the size of some caudal spines (largest in N3) and the setation of the antennal endopod (an extra seta in N3). A wider comparison between free-living nauplii of both Malacostraca and non-Malacostraca revealed similarities between nauplii in many taxa both at the general level (e.g., the gradual development and number of appendages) and at the more detailed level (e.g., unclear segmentation of naupliar appendages, caudal setation, presence of frontal filaments). We recognize these similarities as homologies and therefore suggest that free-living nauplii were part of the ancestral malacostracan type of development. The derived morphology (e.g., lack of feeding structures, no fully formed gut, high content of yolk) of both euphausiid and dendrobranchiate nauplii is evidently related to their non-feeding (lecithotrophic) status
Identified charged hadron production in p+p collisions at sqrt(s)=200 and 62.4 GeV
Transverse momentum distributions and yields for , ,
and in collisions at =200 and 62.4 GeV at midrapidity
are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider
(RHIC). These data provide important baseline spectra for comparisons with
identified particle spectra in heavy ion collisions at RHIC. We present the
inverse slope parameter , mean transverse momentum and
yield per unit rapidity at each energy, and compare them to other
measurements at different in and collisions. We
also present the scaling properties such as scaling, scaling on the
spectra between different energies. To discuss the mechanism of the
particle production in collisions, the measured spectra are compared to
next-to-leading-order or next-to-leading-logarithmic perturbative quantum
chromodynamics calculations.Comment: 431 authors from 62 institutions, 32 pages, 23 figures, and 18
tables. Submitted to Physical Review C. Plain text data tables for the points
plotted in figures for this and previous PHENIX publications are (or will be)
publicly available at http://www.phenix.bnl.gov/papers.htm
Measurement of jet-medium interactions via direct photon-hadron correlations in AuAu and Au collisions at GeV
We present direct photon-hadron correlations in 200 GeV/A AuAu, Au
and collisions, for direct photon from 5--12 GeV/, collected
by the PHENIX Collaboration in the years from 2006 to 2011. We observe no
significant modification of jet fragmentation in Au collisions,
indicating that cold nuclear matter effects are small or absent. Hadrons
carrying a large fraction of the quark's momentum are suppressed in AuAu
compared to and Au. As the momentum fraction decreases, the
yield of hadrons in AuAu increases to an excess over the yield in
collisions. The excess is at large angles and at low hadron and is most
pronounced for hadrons associated with lower momentum direct photons.
Comparison to theoretical calculations suggests that the hadron excess arises
from medium response to energy deposited by jets.Comment: 578 authors from 80 institutions, 11 pages, 7 figures, data from
2007, 2008, 2010, and 2011. v2 is version accepted for publication in
Physical Review C. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV
A search for new physics is presented based on an event signature of at least
three jets accompanied by large missing transverse momentum, using a data
sample corresponding to an integrated luminosity of 36 inverse picobarns
collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector
at the LHC. No excess of events is observed above the expected standard model
backgrounds, which are all estimated from the data. Exclusion limits are
presented for the constrained minimal supersymmetric extension of the standard
model. Cross section limits are also presented using simplified models with new
particles decaying to an undetected particle and one or two jets
Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV
The production of b jets in association with a Z/gamma* boson is studied
using proton-proton collisions delivered by the LHC at a centre-of-mass energy
of 7 TeV and recorded by the CMS detector. The inclusive cross section for
Z/gamma* + b-jet production is measured in a sample corresponding to an
integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross
section with Z/gamma* to ll (where ll = ee or mu mu) for events with the
invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level
with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and
the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.)
+(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also
studied and found to be in agreement with the predictions made by the MadGraph
event generator with the parton shower and the hadronisation performed by
PYTHIA.Comment: Submitted to the Journal of High Energy Physic
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