15,823 research outputs found
Reconstruction of Family-Level Phylogenetic Relationships within Demospongiae (Porifera) Using Nuclear Encoded Housekeeping Genes
Background: Demosponges are challenging for phylogenetic systematics because of their plastic and relatively simple morphologies and many deep divergences between major clades. To improve understanding of the phylogenetic relationships within Demospongiae, we sequenced and analyzed seven nuclear housekeeping genes involved in a variety of cellular functions from a diverse group of sponges.
Methodology/Principal Findings: We generated data from each of the four sponge classes (i.e., Calcarea, Demospongiae, Hexactinellida, and Homoscleromorpha), but focused on family-level relationships within demosponges. With data for 21 newly sampled families, our Maximum Likelihood and Bayesian-based approaches recovered previously phylogenetically defined taxa: Keratosap, Myxospongiaep, Spongillidap, Haploscleromorphap (the marine haplosclerids) and Democlaviap. We found conflicting results concerning the relationships of Keratosap and Myxospongiaep to the remaining demosponges, but our results strongly supported a clade of Haploscleromorphap+Spongillidap+Democlaviap. In contrast to hypotheses based on mitochondrial genome and ribosomal data, nuclear housekeeping gene data suggested that freshwater sponges (Spongillidap) are sister to Haploscleromorphap rather than part of Democlaviap. Within Keratosap, we found equivocal results as to the monophyly of Dictyoceratida. Within Myxospongiaep, Chondrosida and Verongida were monophyletic. A wellsupported clade within Democlaviap, Tetractinellidap, composed of all sampled members of Astrophorina and Spirophorina (including the only lithistid in our analysis), was consistently revealed as the sister group to all other members of Democlaviap. Within Tetractinellidap, we did not recover monophyletic Astrophorina or Spirophorina. Our results also reaffirmed the monophyly of order Poecilosclerida (excluding Desmacellidae and Raspailiidae), and polyphyly of Hadromerida and Halichondrida.
Conclusions/Significance: These results, using an independent nuclear gene set, confirmed many hypotheses based on ribosomal and/or mitochondrial genes, and they also identified clades with low statistical support or clades that conflicted with traditional morphological classification. Our results will serve as a basis for future exploration of these outstanding questions using more taxon- and gene-rich datasets
A Scalable Model for Secure Multiparty Authentication
Distributed system architectures such as cloud computing or the emergent
architectures of the Internet Of Things, present significant challenges for
security and privacy. Specifically, in a complex application there is a need to
securely delegate access control mechanisms to one or more parties, who in turn
can govern methods that enable multiple other parties to be authenticated in
relation to the services that they wish to consume. We identify shortcomings in
an existing proposal by Xu et al for multiparty authentication and evaluate a
novel model from Al-Aqrabi et al that has been designed specifically for
complex multiple security realm environments. The adoption of a Session
Authority Cloud ensures that resources for authentication requests are
scalable, whilst permitting the necessary architectural abstraction for myriad
hardware IoT devices such as actuators and sensor networks, etc. In addition,
the ability to ensure that session credentials are confirmed with the relevant
resource principles means that the essential rigour for multiparty
authentication is established
Arwa: An Inspiring Story for Landmine Survivors
In 1999, Arwa Ali Saeed Wais was herding sheep in Al-Atabat village in the Morais district of Al-Dhale’e governorate, Yemen. As was the tradition in Arwa’s village, she spent much of her childhood caring for her family’s sheep in the nearby mountainous area instead of attending school. When she was 10 years old, she stepped on a landmine. Her right leg was immediately torn off, and her left leg was severely damaged. She was sent to Ibn Khaldon Hospital in Lahj governorate, where she underwent an above-the-knee bilateral amputation. After she was discharged from the hospital, she returned home to her village, where she contracted an infection in her right leg and was sent to Al-Jemhori Hospital in Aden governorate for additional surgery
Dynamic Multiparty Authentication of Data Analytics Services within Cloud Environments
Business analytics processes are often composed from orchestrated,
collaborating services, which are consumed by users from multiple cloud systems
(in different security realms), which need to be engaged dynamically at
runtime. If heterogeneous cloud systems located in different security realms do
not have direct authentication relationships, then it is a considerable
technical challenge to enable secure collaboration. In order to address this
security challenge, a new authentication framework is required to establish
trust amongst business analytics service instances and users by distributing a
common session secret to all participants of a session. We address this
challenge by designing and implementing a secure multiparty authentication
framework for dynamic interaction, for the scenario where members of different
security realms express a need to access orchestrated services. This novel
framework exploits the relationship of trust between session members in
different security realms, to enable a user to obtain security credentials that
access cloud resources in a remote realm. The mechanism assists cloud session
users to authenticate their session membership, thereby improving the
performance of authentication processes within multiparty sessions. We see
applicability of this framework beyond multiple cloud infrastructure, to that
of any scenario where multiple security realms has the potential to exist, such
as the emerging Internet of Things (IoT).Comment: Submitted to the 20th IEEE International Conference on High
Performance Computing and Communications 2018 (HPCC2018), 28-30 June 2018,
Exeter, U
Relationship between Thermodynamic Driving Force and One-Way Fluxes in Reversible Chemical Reactions
Chemical reaction systems operating in nonequilibrium open-system states
arise in a great number of contexts, including the study of living organisms,
in which chemical reactions, in general, are far from equilibrium. Here we
introduce a theorem that relates forward and re-verse fluxes and free energy
for any chemical process operating in a steady state. This rela-tionship, which
is a generalization of equilibrium conditions to the case of a chemical process
occurring in a nonequilibrium steady state, provides a novel equivalent
definition for chemical reaction free energy. In addition, it is shown that
previously unrelated theories introduced by Ussing and Hodgkin and Huxley for
transport of ions across membranes, Hill for catalytic cycle fluxes, and Crooks
for entropy production in microscopically reversible systems, are united in a
common framework based on this relationship.Comment: 11 page
Methylprednisolone for heart surgery in infants - A randomized, controlled trial
BACKGROUND: Although perioperative prophylactic glucocorticoids have been used for decades, whether they improve outcomes in infants after heart surgery with cardiopulmonary bypass is unknown.
METHODS: We conducted a multicenter, prospective, randomized, placebo-controlled, registry-based trial involving infants (\u3c1 year of age) undergoing heart surgery with cardiopulmonary bypass at 24 sites participating in the Society of Thoracic Surgeons Congenital Heart Surgery Database. Registry data were used in the evaluation of outcomes. The infants were randomly assigned to receive prophylactic methylprednisolone (30 mg per kilogram of body weight) or placebo, which was administered into the cardiopulmonary-bypass pump-priming fluid. The primary end point was a ranked composite of death, heart transplantation, or any of 13 major complications. Patients without any of these events were assigned a ranked outcome based on postoperative length of stay. In the primary analysis, the ranked outcomes were compared between the trial groups with the use of odds ratios adjusted for prespecified risk factors. Secondary analyses included an unadjusted odds ratio, a win ratio, and safety outcomes.
RESULTS: A total of 1263 infants underwent randomization, of whom 1200 received either methylprednisolone (599 infants) or placebo (601 infants). The likelihood of a worse outcome did not differ significantly between the methylprednisolone group and the placebo group (adjusted odds ratio, 0.86; 95% confidence interval [CI], 0.71 to 1.05; P = 0.14). Secondary analyses (unadjusted for risk factors) showed an odds ratio for a worse outcome of 0.82 (95% CI, 0.67 to 1.00) and a win ratio of 1.15 (95% CI, 1.00 to 1.32) in the methylprednisolone group as compared with the placebo group, findings suggestive of a benefit with methylprednisolone; however, patients in the methylprednisolone group were more likely than those in the placebo group to receive postoperative insulin for hyperglycemia (19.0% vs. 6.7%, P\u3c0.001).
CONCLUSIONS: Among infants undergoing surgery with cardiopulmonary bypass, prophylactic use of methylprednisolone did not significantly reduce the likelihood of a worse outcome in an adjusted analysis and was associated with postoperative development of hyperglycemia warranting insulin in a higher percentage of infants than placebo. (Funded by the National Center for Advancing Translational Sciences and others; STRESS ClinicalTrials.gov number, NCT03229538.)
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