Cauchy-type integral method for solving the linearized one-dimensional Vlasov-Poisson equation.

We present a method for solving the linearized Vlasov-Poisson equation, based on analyticity properties of the equilibrium and initial condition through Cauchy-type integrals, that produces algebraic expressions for the distribution and field, i.e., the solution is expressed without integrals. Standard extant approaches involve deformations of the Bromwich contour that give erroneous results for certain physically reasonable configurations or eigenfunction expansions that are misleading as to the temporal structure of the solution. Our method is more transparent, lacks these defects, and predicts previously unrecognized behavior.

Blood coagulation dissected.

Hemostasis is the physiological control of bleeding and is initiated by subendothelial exposure. Platelets form the primary vascular seal in three stages (localization, stimulation and aggregation), which are triggered by specific interactions between platelet surface receptors and constituents of the subendothelial matrix. As a secondary hemostatic plug, fibrin clot formation is initiated and feedback-amplified to advance the seal and stabilize platelet aggregates comprising the primary plug. Once blood leakage has been halted, the fibrinolytic pathway is initiated to dissolve the clot and restore normal blood flow. Constitutive and induced anticoagulant and antifibrinolytic pathways create a physiological balance between too much and too little clot production. Hemostatic imbalance is a major burden to global healthcare, resulting in thrombosis or hemorrhage.

Evaluating the test re-test reliability and inter-subject variability of Health Care Provider manual fluid resuscitation performance.

BACKGROUND: Health Care Providers (HCPs) report that manual techniques of intravascular fluid resuscitation are commonly used during pediatric shock management. The optimal pediatric fluid resuscitation technique is currently unknown. We sought to determine HCP test-retest reliability (repeatability) and inter-subject variability of fluid resuscitation performance outcomes to inform the design of future studies. METHODS: Fifteen consenting HCPs from McMaster Children's Hospital, in Hamilton, Canada participated in this single-arm interventional trial. Participants were oriented to a non-clinical model representing a 15 kg toddler, which incorporated a 22-gauge IV catheter. Following a standardization procedure, participants administered 600 mL (40 mL/kg) of saline to the simulated child under emergency conditions using prefilled 60-mL syringes. Each participant completed 5 testing trials. All testing was video recorded, with fluid administration time outcome data (in seconds) extracted from trial videos by two blinded outcome assessors. Data describing catheter dislodgement events, volume of saline effectively delivered, and participant demographics were also collected. The primary outcome of fluid administration time test-retest reliability was analyzed by one-way analysis of variance (ANOVA) and intra-class correlation (ICC), with good reliability defined as ICC > 0.70. RESULTS: Differences in HCP fluid administration times are attributable to inter-subject variability rather than intra-subject variability based on one-way ANOVA analysis, F (14,60) = 43.125; p < 0.001. Test-retest reliability of subjects was excellent with ICC = 0.97 (95% CI: 0.95-0.99); p < 0.001. CONCLUSIONS: Findings demonstrate excellent test-retest reliability of HCP fluid resuscitation performance in a setting involving a non-clinical model. Investigators can justify a single evaluation of HCP performance in future studies.

Reversal of new, factor-specific oral anticoagulants by rFVIIa, prothrombin complex concentrate and activated prothrombin complex concentrate: a review of animal and human studies.

INTRODUCTION: Recombinant activated factor VII (rFVIIa), prothrombin complex concentrate (PCC) and activated PCC (aPCC) are three non-specific haemostatic agents sometimes employed to reverse new, factor-specific oral anticoagulants. METHODS: We conducted a review in the literature to compare the abilities of rFVIIa, PCC and aPCC to reverse factor-specific anticoagulants. MEDLINE and EMBASE databases were searched up to Oct 2013. RESULTS: Eleven animal studies and two human trials met predefined inclusion criteria. To account for dosing variations of anticoagulants among studies, data were interpreted based on standards referenced from human trials at therapeutic doses. In animal studies, inconsistencies in the reversal abilities of rFVIIa, PCC and aPCC can be partly attributed to inter-species differences in the affinity among various clotting factors and tissue factors. Moreover, the differences in the affinity between species-specific clotting factors and anticoagulants that were initially designed to inhibit human factor may impose additional obstacles when comparing single factor rFVIIa with agents that contained multiple clotting factors. In the absence of a common clinical indication for the utilization of rFVIIa, PCC and aPCC, it is difficult, if not impossible, to establish an equivalent dose among these haemostatic agents when comparing their effectiveness in reversing factor-specific oral anticoagulants. Human trials were too few and sub-optimally designed to draw definite conclusions. CONCLUSION: While preclinical studies may hint at a role for these haemostatic agents in reversing the anticoagulant effects of oral, factor-specific anticoagulants, existing trials offer inconclusive evidence to guide a clinical decision among individual agents with respect to potency and thrombosis risk. The mechanistic differences of these hemostatic agents in terms of their interactions with other coagulation factors impose major obstacles for the scientists using animal models to compare the efficacy of these reversal agents.