798 research outputs found
Services within a busy period of an M/M/1 queue and Dyck paths
We analyze the service times of customers in a stable M/M/1 queue in
equilibrium depending on their position in a busy period. We give the law of
the service of a customer at the beginning, at the end, or in the middle of the
busy period. It enables as a by-product to prove that the process of instants
of beginning of services is not Poisson. We then proceed to a more precise
analysis. We consider a family of polynomial generating series associated with
Dyck paths of length 2n and we show that they provide the correlation function
of the successive services in a busy period with (n+1) customers
Thermal image processing for real-time noncontact respiration rate monitoring
A real-time thermal imaging based, non-contact respiration rate monitoring method was developed. It measured the respiration related skin surface temperature changes under the tip of the nose. Facial tracking was required as head movements caused the face to appear in different locations in the recorded images over time. The algorithm detected the tip of the nose and then, a region just under it was selected. The pixel values in this region in successive images were processed to determine respiration rate. The segmentation method, used as part of the facial tracking, was evaluated on 55,000 thermal images recorded from 14 subjects with different extent of head movements. It separated the face from image background in all images. However, in 11.7% of the images, a section of the neck was also included, but this did not cause an error in determining respiration rate. The method was further evaluated on 15 adults, against two contact respiration rate monitoring methods that tracked thoracic and abdominal movements. The three methods gave close respiration rates in 12 subjects but in 3 subjects, where there were very large head movements, the respiration rates did not match
Phase transitions in geometrothermodynamics
Using the formalism of geometrothermodynamics, we investigate the geometric
properties of the equilibrium manifold for diverse thermodynamic systems.
Starting from Legendre invariant metrics of the phase manifold, we derive
thermodynamic metrics for the equilibrium manifold whose curvature becomes
singular at those points where phase transitions of first and second order
occur. We conclude that the thermodynamic curvature of the equilibrium
manifold, as defined in geometrothermodynamics, can be used as a measure of
thermodynamic interaction in diverse systems with two and three thermodynamic
degrees of freedom
Geology of the Al Wathba 1:100 000 map sheet, 100-12, United Arab Emirates
This Sheet Description describes the Quaternary and bedrock geology of the Al Wathba 1:100 000 scale geological map. The district covers 2780 km2 southeast of Abu Dhabi island, and includes many of the suburbs of Abu Dhabi city, including the proposed Capital District, Madinat Khalifa A and B, Mussafah, Mohammed bin Zayed City, Mafraq, Bani Yas, Al Wathba, Al Falah, Al Shamka and Abu Dhabi International Airport. The sheet extends east as far as Al Khatim.
The pre-Quaternary bedrock comprises Miocene evaporitic mudstone and siltstone of the Gachsaran Formation (Fars Group) overlain by the dolomitic conglomerates, sandstones and siltstones of the Barzaman Formation in the north. In the south and west, the Gachsaran Formation is overlain by the dolomites and limestones of the Dam Formation which forms an escarpment around the Al Dhafra Air Base. These are overlain by the sandstones of the Shuwaihat and Baynunah Formations. Borehole evidence suggests there is a gradation from interbedded siltstones and sandstones of the Baynunah Formation in the west of the district to coarse dolomitic conglomerates of the Barzaman Formation in the north.
The Miocene rocks are locally overlain by fluvial sandstones and channel gravels of the Hili Formation which represent Quaternary outwash from the Hajar Mountains to the east. Much of the region is partially covered by pale carbonate aeolianites of the Ghayathi Formation, themselves often covered in a veneer of more recent aeolian sand. These are well exposed near the coast in spectacular zeugen and inland, they form a series of east-northeast trending linear ridges.
Modern pale carbonate-dominated low dunes occur particularly in the west of the district. The coastal zone is dominated by a range of Late Pleistocene to Holocene littoral and marine deposits, which comprise the Abu Dhabi Formation. These include coastal spits and bars, algal mats, mangrove swamps and intertidal sediments. Sabkha is developed on the surface of these deposits.
The region has seen major development over the past 30 years, which has radically changed the surface geology. Much of the coastal strip has been reclaimed or developed, with a variable amount of made ground, often composed of carbonate sand dredged from the neighbouring lagoons. Further inland, many areas have been extensively landscaped, with large areas of dunes levelled flat or quarried for fill. Much of the north-western part of the sheet is either developed or scheduled for development. Extensive areas of forestry occur along the line of the main Abu Dhabi – Al Ain highway and north of Abu Dhabi International Airport
Local search for the surgery admission planning problem
We present a model for the surgery admission planning problem, and a meta-heuristic algorithm for solving it. The problem involves assigning operating rooms and dates to a set of elective surgeries, as well as scheduling the surgeries of each day and room. Simultaneously, a schedule is created for each surgeon to avoid double bookings. The presented algorithm uses simple Relocate and Two-Exchange neighbourhoods, governed by an iterated local search framework. The problem's search space associated with these move operators is analysed for three typical fitness surfaces, representing different compromises between patient waiting time, surgeon overtime, and waiting time for children in the morning on the day of surgery. The analysis shows that for the same problem instances, the different objectives give fitness surfaces with quite different characteristics. We present computational results for a set of benchmarks that are based on the admission planning problem in a chosen Norwegian hospital
HI in the Outskirts of Nearby Galaxies
The HI in disk galaxies frequently extends beyond the optical image, and can
trace the dark matter there. I briefly highlight the history of high spatial
resolution HI imaging, the contribution it made to the dark matter problem, and
the current tension between several dynamical methods to break the disk-halo
degeneracy. I then turn to the flaring problem, which could in principle probe
the shape of the dark halo. Instead, however, a lot of attention is now devoted
to understanding the role of gas accretion via galactic fountains. The current
cold dark matter theory has problems on galactic scales, such as
the core-cusp problem, which can be addressed with HI observations of dwarf
galaxies. For a similar range in rotation velocities, galaxies of type Sd have
thin disks, while those of type Im are much thicker. After a few comments on
modified Newtonian dynamics and on irregular galaxies, I close with statistics
on the HI extent of galaxies.Comment: 38 pages, 17 figures, invited review, book chapter in "Outskirts of
Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and
Space Science Library, Springer, in pres
Computer Simulation of Final-Stage Sintering: I, Model Kinetics, and Microstructure
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65565/1/j.1151-2916.1990.tb06686.x.pd
Dynamic human MutSα–MutLα complexes compact mismatched DNA
DNA mismatch repair (MMR) corrects errors that occur during DNA replication. In humans, mutations in the proteins MutSα and MutLα that initiate MMR cause Lynch syndrome, the most common hereditary cancer. MutSα surveilles the DNA, and upon recognition of a replication error it undergoes adenosine triphosphate-dependent conformational changes and recruits MutLα. Subsequently, proliferating cell nuclear antigen (PCNA) activates MutLα to nick the error-containing strand to allow excision and resynthesis. The structure–function properties of these obligate MutSα–MutLα complexes remain mostly unexplored in higher eukaryotes, and models are predominately based on studies of prokaryotic proteins. Here, we utilize atomic force microscopy (AFM) coupled with other methods to reveal time- and concentration-dependent stoichiometries and conformations of assembling human MutSα–MutLα–DNA complexes. We find that they assemble into multimeric complexes comprising three to eight proteins around a mismatch on DNA. On the timescale of a few minutes, these complexes rearrange, folding and compacting the DNA. These observations contrast with dominant models of MMR initiation that envision diffusive MutS–MutL complexes that move away from the mismatch. Our results suggest MutSα localizes MutLα near the mismatch and promotes DNA configurations that could enhance MMR efficiency by facilitating MutLα nicking the DNA at multiple sites around the mismatch. In addition, such complexes may also protect the mismatch region from nucleosome reassembly until repair occurs, and they could potentially remodel adjacent nucleosomes
Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider
This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the ϒ(4S), ϒ(3S), and ϒ(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-→e+e- and (for the ϒ(4S) only) e+e-→μ+μ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-→e+e- and e+e-→μ+μ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the ϒ(3S) and ϒ(2S) resonances, an additional uncertainty arises due to ϒ→e+e-X background. For data collected off the ϒ resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the ϒ(4S), 0.58% (0.72%) for the ϒ(3S), and 0.68% (0.88%) for the ϒ(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat à l’Energie Atomique and Institut National de Physique Nucléaire et de Physiquedes Particules (France), the Bundesministerium für Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e Innovación (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)
Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA
An investigation of the hadronic final state in diffractive and
non--diffractive deep--inelastic electron--proton scattering at HERA is
presented, where diffractive data are selected experimentally by demanding a
large gap in pseudo --rapidity around the proton remnant direction. The
transverse energy flow in the hadronic final state is evaluated using a set of
estimators which quantify topological properties. Using available Monte Carlo
QCD calculations, it is demonstrated that the final state in diffractive DIS
exhibits the features expected if the interaction is interpreted as the
scattering of an electron off a current quark with associated effects of
perturbative QCD. A model in which deep--inelastic diffraction is taken to be
the exchange of a pomeron with partonic structure is found to reproduce the
measurements well. Models for deep--inelastic scattering, in which a
sizeable diffractive contribution is present because of non--perturbative
effects in the production of the hadronic final state, reproduce the general
tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil
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