199 research outputs found
Addendum: A Classification of Plane Symmetric Kinematic Self-similar Solutions
In our recent paper, we classified plane symmetric kinematic self-similar
perfect fluid and dust solutions of the second, zeroth and infinite kinds.
However, we have missed some solutions during the process. In this short
communication, we add up those missing solutions. We have found a total of
seven solutions, out of which five turn out to be independent and cannot be
found in the earlier paperComment: 7 pages Late
On Physical Properties of Cylindrically Symmetric Self-Similar Solutions
This paper is devoted to discuss some of the features of self-similar
solutions of the first kind. We consider the cylindrically symmetric solutions
with different homotheties. We are interested in evaluating the quantities
acceleration, rotation, expansion, shear, shear invariant and expansion rate.
These kinematical quantities are discussed both in co-moving as well as in
non-co-moving coordinates (only in radial direction). Finally, we would discuss
the singularity feature of these solutions. It is expected that these
properties would help in exploring some interesting features of the
self-similar solutions.Comment: 16 pages, accepted for publication in Int. J. of Mod. Phys.
Kinematic Self-Similar Cylindrically Symmetric Solutions
This paper is devoted to find out cylindrically symmetric kinematic
self-similar perfect fluid and dust solutions. We study the cylindrically
symmetric solutions which admit kinematic self-similar vectors of second,
zeroth and infinite kinds, not only for the tilted fluid case but also for the
parallel and orthogonal cases. It is found that the parallel case gives
contradiction both in perfect fluid and dust cases. The orthogonal perfect
fluid case yields a vacuum solution while the orthogonal dust case gives
contradiction. It is worth mentioning that the tilted case provides solution
both for the perfect as well as dust cases.Comment: 22 pages, accepted for publication in Int. J. of Mod. Phys.
Symmetries of the Energy-Momentum Tensor: Some Basic Facts
It has been pointed by Hall et al. [1] that matter collinations can be
defined by using three different methods. But there arises the question of
whether one studies matter collineations by using the ,
or or . These alternative
conditions are, of course, not generally equivalent. This problem has been
explored by applying these three definitions to general static spherically
symmetric spacetimes. We compare the results with each definition.Comment: 17 pages, accepted for publication in "Communications in Theoretical
Physics
Kinematic Self-Similar Plane Symmetric Solutions
This paper is devoted to classify the most general plane symmetric spacetimes
according to kinematic self-similar perfect fluid and dust solutions. We
provide a classification of the kinematic self-similarity of the first, second,
zeroth and infinite kinds with different equations of state, where the
self-similar vector is not only tilted but also orthogonal and parallel to the
fluid flow. This scheme of classification yields twenty four plane symmetric
kinematic self-similar solutions. Some of these solutions turn out to be
vacuum. These solutions can be matched with the already classified plane
symmetric solutions under particular coordinate transformations. As a result,
these reduce to sixteen independent plane symmetric kinematic self-similar
solutions.Comment: 29 pages, accepted for publication in Classical Quantum Gravit
Classification of Spherically Symmetric Static Spacetimes according to their Matter Collineations
The spherically symmetric static spacetimes are classified according to their
matter collineations. These are studied when the energy-momentum tensor is
degenerate and also when it is non-degenerate. We have found a case where the
energy-momentum tensor is degenerate but the group of matter collineations is
finite. For the non-degenerate case, we obtain either {\it four}, {\it five},
{\it six} or {\it ten} independent matter collineations in which four are
isometries and the rest are proper. We conclude that the matter collineations
coincide with the Ricci collineations but the constraint equations are
different which on solving can provide physically interesting cosmological
solutions.Comment: 15 pages, no figure, Late
Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: Multispecialty, prospective cohort study in 25 countries
Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P \u3c 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (β coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely
Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries
Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely
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