60 research outputs found
On the interaction between two Kerr black holes
The double-Kerr solution is generated using both a Backlund transformation
and the Belinskii-Zakharov inverse-scattering technique. We build a dictionary
between the parametrisations naturally obtained in the two methods and show
their equivalence. We then focus on the asymptotically flat double-Kerr system
obeying the axis condition which is Z_2^\phi invariant; for this system there
is an exact formula for the force between the two black holes, in terms of
their physical quantities and the coordinate distance. We then show that 1) the
angular velocity of the two black holes decreases from the usual Kerr value at
infinite distance to zero in the touching limit; 2) the extremal limit of the
two black holes is given by |J|=cM^2, where c depends on the distance and
varies from one to infinity as the distance decreases; 3) for sufficiently
large angular momentum the temperature of the black holes attains a maximum at
a certain finite coordinate distance. All of these results are interpreted in
terms of the dragging effects of the system.Comment: 19 pages, 4 figures. v2: changed statement about thermodynamical
equilibrium in section 3; minor changes; added references. v3: added
references to previous relevant work; removed one equation (see note added);
other minor corrections; final version to be published in JHE
On the existence of exotic and non-exotic multiquark meson states
To obtain an exact solution of a four-body system containing two quarks and
two antiquarks interacting through two-body terms is a cumbersome task that has
been tackled with more or less success during the last decades. We present an
exact method for the study of four-quark systems based on the hyperspherical
harmonics formalism that allows us to solve it without resorting to further
approximations, like for instance the existence of diquark components. We apply
it to systems containing two heavy and two light quarks using different
quark-quark potentials. While states may be stable in nature,
the stability of states would imply the existence of quark
correlations not taken into account by simple quark dynamical models.Comment: 3 pages. Contribution to the 20th European Conference on Few-Body
Problems in Physics, Pisa, Italy. To be published in Few-Body system
Optimization of flow shop scheduling through a hybrid genetic algorithm for manufacturing companies
A task scheduling problem is a process of assigning tasks to a limited set of resources available in a time interval, where certain criteria are optimized. In this way, the sequencing of tasks is directly associated with the executability and optimality of a preset plan and can be found in a wide range of applications, such as: programming flight dispatch at airports, programming production lines in a factory, programming of surgeries in a hospital, repair of equipment or machinery in a workshop, among others. The objective of this study is to analyze the effect of the inclusion of several restrictions that negatively influence the production programming in a real manufacturing environment. For this purpose, an efficient Genetic Algorithm combined with a Local Search of Variable Neighborhood for problems of n tasks and m machines is introduced, minimizing the time of total completion of the tasks. The computational experiments carried out on a set of problem instances with different sizes of complexity show that the proposed hybrid metaheuristics achieves high quality solutions compared to the reported optimal cases
Cold Accretion Disks and Lineless Quasars
The optical-UV continuum of quasars is broadly consistent with the emission
from a geometrically thin optically thick accretion disk (AD). The AD produces
the ionizing continuum which powers the broad and narrow emission lines. The
maximum AD effective temperature is given by Teff=fmax(Mdot/M^2)^1/4, where M
is the black hole mass, Mdot the accretion rate, and fmax is set by the black
hole spin a_*. For a low enough value of Mdot/M^2 the AD may become too cold to
produce ionizing photons. Such an object will form a lineless quasar. This
occurs for a local blackbody (BB) AD with a luminosity Lopt=10^46 erg/s for
M>3.6E9 Msun, when a_*=0, and for M>1.4E10 Msun, when a_*=0.998. Using the AD
based Mdot, derived from M and Lopt, and the reverberation based M, derived
from Lopt and the Hbeta FWHM, v, gives Teff \propto Lopt^-0.13v^-1.45. Thus,
Teff is mostly set by v. Quasars with a local BB AD become lineless for v>
8,000 km/s, when a_*=0, and for v> 16,000 km/s, when a_*=0.998. Higher values
of v are required if the AD is hotter than a local BB. The AD becoming
non-ionizing may explain why line emitting quasars with v>10,000 km/s are rare.
Weak low ionization lines may still be present if the X-ray continuum is
luminous enough, and such objects may form a population of weak emission line
quasars (WLQ). If correct, such WLQ should show a steeply falling SED at
lambda<1000A. Such an SED was observed by Hryniewicz et al. in SDSS
J094533.99+100950.1, a WLQ observed down to 570A, which is well modeled by a
rather cold AD SED. UV spectroscopy of z~1-2 quasars is required to eliminate
potential intervening Lyman limit absorption by the intergalactic medium (IGM),
and to explore if the SEDs of lineless quasars and some additional WLQ are also
well fit by a cold AD SED.Comment: Accepted for publication in MNRA
Mechanisms and management of loss of response to anti-TNF therapy for patients with Crohn's disease: 3-year data from the prospective, multicentre PANTS cohort study
This is the final version. Available from Elsevier via the DOI in this record. Background We sought to report the effectiveness of infliximab and adalimumab over the first 3 years of treatment
and to define the factors that predict anti-TNF treatment failure and the strategies that prevent or mitigate loss of
response.
Methods Personalised Anti-TNF therapy in Crohn’s disease (PANTS) is a UK-wide, multicentre, prospective
observational cohort study reporting the rates of effectiveness of infliximab and adalimumab in anti-TNF-naive patients
with active luminal Crohn’s disease aged 6 years and older. At the end of the first year, sites were invited to enrol
participants still receiving study drug into the 2-year PANTS-extension study. We estimated rates of remission across
the whole cohort at the end of years 1, 2, and 3 of the study using a modified survival technique with permutation
testing. Multivariable regression and survival analyses were used to identify factors associated with loss of response
in patients who had initially responded to anti-TNF therapy and with immunogenicity. Loss of response was defined
in patients who initially responded to anti-TNF therapy at the end of induction and who subsequently developed
symptomatic activity that warranted an escalation of steroid, immunomodulatory, or anti-TNF therapy, resectional
surgery, or exit from study due to treatment failure. This study was registered with ClinicalTrials.gov, NCT03088449,
and is now complete.
Findings Between March 19, 2014, and Sept 21, 2017, 389 (41%) of 955 patients treated with infliximab and
209 (32%) of 655 treated with adalimumab in the PANTS study entered the PANTS-extension study (median age
32·5 years [IQR 22·1–46·8], 307 [51%] of 598 were female, and 291 [49%] were male). The estimated proportion of
patients in remission at the end of years 1, 2, and 3 were, for infliximab 40·2% (95% CI 36·7–43·7),
34·4% (29·9–39·0), and 34·7% (29·8–39·5), and for adalimumab 35·9% (95% CI 31·2–40·5), 32·9% (26·8–39·2),
and 28·9% (21·9–36·3), respectively. Optimal drug concentrations at week 14 to predict remission at any later
timepoints were 6·1–10·0 mg/L for infliximab and 10·1–12·0 mg/L for adalimumab. After excluding patients who
had primary non-response, the estimated proportions of patients who had loss of response by years 1, 2, and 3
were, for infliximab 34·4% (95% CI 30·4–38·2), 54·5% (49·4–59·0), and 60·0% (54·1–65·2), and for adalimumab
32·1% (26·7–37·1), 47·2% (40·2–53·4), and 68·4% (50·9–79·7), respectively. In multivariable analysis, loss of
response at year 2 and 3 for patients treated with infliximab and adalimumab was predicted by low anti-TNF drug
concentrations at week 14 (infliximab: hazard ratio [HR] for each ten-fold increase in drug concentration 0·45
[95% CI 0·30–0·67], adalimumab: 0·39 [0·22–0·70]). For patients treated with infliximab, loss of response was
also associated with female sex (vs male sex; HR 1·47 [95% CI 1·11–1·95]), obesity (vs not obese 1·62 [1·08–2·42]),
baseline white cell count (1·06 [1·02–1·11) per 1 × 10⁹ increase in cells per L), and thiopurine dose quartile. Among
patients treated with adalimumab, carriage of the HLA-DQA1*05 risk variant was associated with loss of response
(HR 1·95 [95% CI 1·17–3·25]). By the end of year 3, the estimated proportion of patients who developed anti-drug
antibodies associated with undetectable drug concentrations was 44·0% (95% CI 38·1–49·4) among patients
treated with infliximab and 20·3% (13·8–26·2) among those treated with adalimumab. The development of antidrug antibodies associated with undetectable drug concentrations was significantly associated with treatment
without concomitant immunomodulator use for both groups (HR for immunomodulator use: infliximab 0·40
[95% CI 0·31–0·52], adalimumab 0·42 [95% CI 0·24–0·75]), and with carriage of HLA-DQA1*05 risk variant for
infliximab (HR for carriage of risk variant: infliximab 1·46 [1·13–1·88]) but not for adalimumab (HR 1·60
[0·92–2·77]). Concomitant use of an immunomodulator before or on the day of starting infliximab was associated
with increased time without the development of anti-drug antibodies associated with undetectable drug
concentrations compared with use of infliximab alone (HR 2·87 [95% CI 2·20–3·74]) or introduction of an
immunomodulator after anti-TNF initiation (1·70 [1·11–2·59]). In years 2 and 3, 16 (4%) of 389 patients treated
with infliximab and 11 (5%) of 209 treated with adalimumab had adverse events leading to treatment withdrawal.
Nine (2%) patients treated with infliximab and two (1%) of those treated with adalimumab had serious infections
in years 2 and 3.
Interpretation Only around a third of patients with active luminal Crohn’s disease treated with an anti-TNF drug were
in remission at the end of 3 years of treatment. Low drug concentrations at the end of the induction period predict
loss of response by year 3 of treatment, suggesting higher drug concentrations during the first year of treatment,
particularly during induction, might lead to better long-term outcomes. Anti-drug antibodies associated with
undetectable drug concentrations of infliximab, but not adalimumab, can be predicted by carriage of HLA-DQA1*05
and mitigated by concomitant immunomodulator use for both drugs.Guts UKCrohn’s and Colitis UKCure Crohn’s ColitisAbbVieMerck Sharp and DohmeNapp PharmaceuticalsPfizerCelltrion Healthcar
Thomas-Fermi Method For Particles Obeying Generalized Exclusion Statistics
We use the Thomas-Fermi method to examine the thermodynamics of particles obeying Haldane exclusion statistics. Specifically, we study Calogero-Sutherland particles placed in a given external potential in one dimension. For the case of a simple harmonic potential (constant density of states), we obtain the exact one-particle spatial density and a {\it closed} form for the equation of state at finite temperature, which are both new results. We then solve the problem of particles in a potential (linear density of states) and show that Bose-Einstein condensation does not occur for any statistics other than bosons
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Soil Science: Fundamentals to Recent Advances (Editors: Amitava Rakshit, S.K Singh, P.C. Abhilash, Asim Biswas)Indiscriminate use of pesticides will lead to their accumulation in soil and may impart an adverse impact on human and environmental health. Due to the intensification of agriculture, usage of pesticide is inevitable in India; however, in the absence of a strong legal framework and lack of awareness of the farmers, inappropriate use of pesticides contributed to the pollution of soil and sediments and induced health problems for human and aquatic lives. Some of the pesticide molecules and its derivatives persist in the soil for a longer period which disturbs soil ecological balance and sustainability. Moreover, traces of pesticides may cause threat to the aquatic endangered species. This is a serious concern for both soil and aquatic environments. Reviewing various literature it was found that the level of contamination in soil and sediment does not reflect the present pesticide usage scenario of India and further highlighted the widespread use of banned pesticides. Under these circumstances, this chapter describes the occurrence, distribution and source of pesticides in the Indian scenario based on the numerous studies conducted over the past decades in both soil and sediment environments. The impact of these pesticides on soil ecology is also discussed along with the mention of novel and effective bioremediation methods invented by team of researchers to overcome the problem of pesticide residues.Not Availabl
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