1,004 research outputs found
Polymerase chain reaction for the confirmation of isolated Listeria spp.from food contact surfaces in the open markets in KhonKaen, Thailand
No full textSwab samples (280) were taken from different kinds of food contact surfaces including stainless steel, tile, polyethylene and wooden cutting board from five open markets in KhonKaen, Thailand. Listeria spp. was found from food contact surfaces in three open markets. Most positive samples were isolated from surfaces of stainless steel, wooden cutting board, ceramic tile and polyethylene. All suspected colonies were identified using biological tests such as Gram stain, mobility, catalase, and CAMP Tests. The weak hemolytic colonies of the CAMP reaction on 5% sheep blood agar defined that 13 out of 70 colonies were identified as L. monocytogenes. Listeria identification tests were performed by 10 Listeria API strips. All weak hemolytic strains were confirmed by PCR. PCR products amplified with 16sRNA primers were sent for sequencing. Results showed that all isolated strains amplified with the general Listeria primer were confirmed as Listeria spp. However, the PCR products bands which were amplified specifically for L. monocytogenes were missing on 1.5% Agarose gel. The PCR results implied that all isolated strains were not L. monocytogenes. Blasting results from EMBL-EBI and Ezbiocloud databases reported that all isolated strains with wealc hemolytic results were L. innocua
Strong constraints on jet quenching in centrality-dependent +Pb collisions at 5.02 TeV from ATLAS
No full textJet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including and +Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36 nb of +Pb and 3.6 pb of collisions at 5.02 TeV. The yields of charged hadrons with GeV near and opposite in azimuth to jets with or 60 GeV, and the ratios of these yields between +Pb and collisions, , are reported. The collision centrality of +Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The values are consistent with unity within a few percent for hadrons with GeV at all centralities. These data provide new, strong constraints which preclude almost any parton energy loss in central +Pb collisions
Searches for dark matter in association with top quarks with the ATLAS experiment [Elektronisk resurs]
No full textThis thesis presents a search for dark matter with the ATLAS experiment using 139 fb−1 of pp collision data at √s = 13 TeV delivered by the LHC from 2015 to 2018. The search targets a simplified model where a spin-0 scalar or pseudoscalar mediator particle, decaying to a pair of dark matter particles, is produced in association with a pair of top quarks. The final state of interest includes one charged lepton, multiple jets and missing transverse momentum. No excess over the Standard Model background is observed and new exclusion limits at 95% confidence level are placed on the mediator mass. Mediator masses up to 200 GeV are excluded for a dark matter mass of 1 GeV and a coupling strength of one. The one-lepton analysis is statistically combined with those targeting final states with zero or two leptons. The combined results extend the exclusion limits for mediator masses up to 370 GeV. These results are also used to set an upper limit on the Higgs boson branching ratio into invisible particles of 0.40 at 95% confidence level. Luminosity is a key measure of the LHC performance which relates the number of events of a physics process to its cross-section. This thesis presents systematic studies of the track-counting algorithm which is used to measure the luminosity in ATLAS.</p
Measurement of prompt photon production in root s(NN)=8.16 TeV p Pb collisions with ATLAS
No full textThe inclusive production rates of isolated, prompt photons in p Pb collisions at root s(NN) = 8.16 TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165 nb(-1) recorded in 2016. The cross-section and nuclear modification factor R-p pb are measured as a function of photon transverse energy from 20 GeV to 550 GeV and in three nucleon-nucleon centre-of-mass pseudorapidity regions, (-2.83, -2.02), (-1.84, 0.91), and (1.09, 1.90). The cross-section and R-p pb values are compared with the results of a next-to-leading-order perturbative QCD calculation, with and without nuclear parton distribution function modifications, and with expectations based on a model of the energy loss of partons prior to the hard scattering. The data disfavour a large amount of energy loss and provide new constraints on the parton densities in nuclei.</p
Long-term monitoring of breeding successes of Great Hornbill (Buceros bicornis) and Rhinoceros Hornbill (Buceros rhinoceros) using artificial nest boxes in Budo-Su-Ngai Padi National Park, Thailand
No full textNest boxes are a conservation tool for increasing the availability of nests. The efficacy of nest boxes can be assessed by examining the breeding parameters of birds in nest boxes to see whether data are comparable with tree cavities.
The hornbill artificial nest research was conducted in Budo-Su-Ngai Padi National Park, Thailand since 2003. This project aims to increase the breeding propensity of two large species of hornbills; the Great Hornbill (Buceros bicornis) and the Rhinoceros Hornbill (Buceros rhinoceros) that coexist in the study area, by utilizing nest boxes. The nest boxes were constructed from fiber-reinforced plastic. There were two designs; small nest box: 50 x 49 cm at base and 95 cm height, and large: 65 x 70 cm at base and 95 cm height. Twenty nest boxes were installed between 2004 and 2006. These nest boxes were monitored from 2004 to 2021.
The study results indicated that the proportion of nest occupancy of Great Hornbill breeding in natural nests was higher than nest boxes: 48.9% and 31.4%, respectively (the two binomial proportions test gives: Zc= 4.01, P < 0.0006 < α = 0.05). The results also showed that the Great Hornbill prefers to select a large nest box than a small one: 37.3% and 17.3%, respectively (the two binomial proportions test gives: Zc = 3.4, P < 0.00068 < α = 0.05). Eight nest boxes so far have been utilized by hornbills: six by Great Hornbill with 58 nesting successes and two by Rhinoceros Hornbill with 1 nesting success. The average life cycle of the fiberglass nest box is about 11.38±4.23 SD years.
The study results suggest that reproduction parameters of hornbills in nest boxes are different from natural cavities in many aspects. Our two target species do not equally benefit from nest boxes
Strong Constraints on Jet Quenching in Centrality-Dependent <em>p</em> + Pb Collisions at 5.02 TeV from ATLAS
No full textJet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including pp and p+Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36 nb−1 of p+Pb and 3.6 pb−1 of pp collisions at 5.02 TeV. The yields of charged hadrons with > 0.5 GeV near and opposite in azimuth to jets with >30 or 60 GeV, and the ratios of these yields between p+Pb and pp collisions, IpPb, are reported. The collision centrality of p+Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The IpPb values are consistent with unity within a few percent for hadrons with >4 GeV at all centralities. These data provide new, strong constraints that preclude almost any parton energy loss in central p+Pb collisions. </p
Measurement of prompt photon production in √sNN=8.16 TeV p + Pb collisions with ATLAS
No full textThe inclusive production rates of isolated, prompt photons in p + Pb collisions at √sNN = 8.16 TeV
are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated
luminosity of 165 nb−1 recorded in 2016. The cross-section and nuclear modification factor RpPb are
measured as a function of photon transverse energy from 20 GeV to 550 GeV and in three nucleon–
nucleon centre-of-mass pseudorapidity regions, (−2.83,−2.02), (−1.84, 0.91), and (1.09, 1.90). The
cross-section and RpPb values are compared with the results of a next-to-leading-order perturbative QCD
calculation, with and without nuclear parton distribution function modifications, and with expectations
based on a model of the energy loss of partons prior to the hard scattering. The data disfavour a large
amount of energy loss and provide new constraints on the parton densities in nuclei
Dijet azimuthal correlations and conditional yields in pp and p+Pb collisions at sNN=5.02TeV with the ATLAS detector
No full textThis paper presents a measurement of forward-forward and forward-central dijet azimuthal angular correlations and conditional yields in proton-proton (pp) and proton-lead (p+Pb) collisions as a probe of the nuclear gluon density in regions where the fraction of the average momentum per nucleon carried by the parton entering the hard scattering is low. In these regions, gluon saturation can modify the rapidly increasing parton distribution function of the gluon. The analysis utilizes 25pb-1 of pp data and 360μb-1 of p+Pb data, both at sNN=5.02 TeV, collected in 2015 and 2016, respectively, with the ATLAS detector at the Large Hadron Collider. The measurement is performed in the center-of-mass frame of the nucleon-nucleon system in the rapidity range between -4.0 and 4.0 using the two highest transverse-momentum jets in each event, with the highest transverse-momentum jet restricted to the forward rapidity range. No significant broadening of azimuthal angular correlations is observed for forward-forward or forward-central dijets in p+Pb compared to pp collisions. For forward-forward jet pairs in the proton-going direction, the ratio of conditional yields in p+Pb collisions to those in pp collisions is suppressed by approximately 20%, with no significant dependence on the transverse momentum of the dijet system. No modification of conditional yields is observed for forward-central dijets
Transverse momentum and process dependent azimuthal anisotropies in root S-NN=8.16 TeV p plus Pb collisions with the ATLAS detector
No full textThe azimuthal anisotropy of charged particles produced in sNN=8.16TeV p+Pb collisions is measured with the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 165 nb-1 that was collected in 2016. Azimuthal anisotropy coefficients, elliptic v2 and triangular v3\, extracted using two-particle correlations with a non-flow template fit procedure, are presented as a function of particle transverse momentum (pT) between 0.5 and 50 GeV. The v2 results are also reported as a function of centrality in three different particle pTintervals. The results are reported from minimum-bias events and jet-triggered events, where two jet pT thresholds are used. The anisotropies for particles with pT less than about 2 GeV are consistent with hydrodynamic flow expectations, while the significant non-zero anisotropies for pT in the range 9-50 GeV are not explained within current theoretical frameworks. In the pTrange 2-9 GeV, the anisotropies are larger in minimum-bias than in jet-triggered events. Possible origins of these effects, such as the changing admixture of particles from hard scattering and the underlying event, are discussed.</p
Measurement of the centrality dependence of the dijet yield in p+Pb collisions at √sNN = 8.16 TeV with the ATLAS detector
No full textATLAS measured the centrality dependence of the dijet yield using
165
nb
−
1
of
p
+
Pb
data collected at
√
s
NN
=
8.16
TeV
in 2016. The event centrality, which reflects the
p
+
Pb
impact parameter, is characterized by the total transverse energy registered in the Pb-going side of the forward calorimeter. The central-to-peripheral ratio of the scaled dijet yields,
R
CP
, is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The
R
CP
shows a scaling with the Bjorken
x
of the parton originating from the proton,
x
p
, while no such trend is observed as a function of
x
Pb
. This analysis provides unique input to understanding the role of small proton spatial configurations in
p
+
Pb
collisions by covering parton momentum fractions from the valence region down to
x
p
∼
10
−
3
and
x
Pb
∼
4
×
10
−
4
- …
