Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole.

The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements. We use numerical calculations of regular, parametric, non-Kerr metrics to identify the common characteristic among these different parametrizations that control the predicted shadow size. We show that the shadow-size measurements place significant constraints on deviation parameters that control the second post-Newtonian and higher orders of each metric and are, therefore, inaccessible to weak-field tests. The new constraints are complementary to those imposed by observations of gravitational waves from stellar-mass sources.

A shunt decision-making protocol in the surgical palliation of hypoplastic left heart syndrome from 2004 to 2016.

OBJECTIVES: The aim of this study was to study the impact of a decision-making protocol for shunt type in the Norwood procedure for hypoplastic left heart syndrome. Our cohort extends from 2004 to 2016. In era 1 (pre-2008), there was no policy for the choice of Norwood shunt. In era 2 (post-2008), a standard protocol was implemented. The right ventricle (RV)-to-pulmonary artery conduit was utilized for low-birth weight patients (<2.5 kg). The right modified Blalock-Taussig Shunt (RBTS) was constructed for normal birth weight patients. METHODS: The records of 133 consecutive operative patients with hypoplastic left heart syndrome anatomy between 2004 and 2016 were retrospectively reviewed. Survival risk factors were analysed using the Cox proportional hazards risk model. RESULTS: The Norwood procedure was performed at a mean age of 2.9 ± 1.9 days. Bidirectional cavopulmonary shunt was performed at a median age of 99 days (interquartile range 91-107). In era 1, 38.6% (22/57) of patients received the RBTS and 61.4% (35/57) of patients received the RV-to-pulmonary artery conduit. In era 2, 86.8% (66/76) of patients received the RBTS and 13.2% (10/76) of patients received the RV-to-pulmonary artery conduit. The actuarial survival to Fontan was 72.2% (96/133). Era 1 patients were more likely to die within the 1st year (hazard ratio = 2.310, P = 0.025). CONCLUSIONS: The shunt protocol may improve outcomes in high-risk patients, and we have demonstrated the reliability of the RBTS in low-risk patients. The short- and mid-term outcomes of our Norwood population justify the continued efforts to improve surgical and perioperative management.

Passive Wrist Stiffness: The Influence of Handedness.

OBJECTIVE: This paper reports on the quantification of passive wrist joint stiffness and investigates the potential influence of handedness and gender on stiffness estimates. METHODS: We evaluated the torque-angle relationship during passive wrist movements in 2 degrees of freedom (into flexion-extension and radial-ulnar deviation) in 13 healthy subjects using a wrist robot. Experimental results determined intrasubject differences between dominant and nondominant wrist and intersubject differences between male and female participants. RESULTS: We found differences in the magnitude of passive stiffness of left- and right-hand dominant males and right-hand dominant females suggesting that the dominant hand tends to be stiffer than the nondominant hand. Left-hand stiffness magnitude was found to be 37% higher than the right-hand stiffness magnitude in the left-handed male group and the right-hand stiffness magnitude was 11% and 40% higher in the right-handed male and female groups, respectively. Other joint stiffness features such as the orientation and the anisotropy of wrist stiffness followed the expected pattern from previous studies. CONCLUSION: The observed difference in wrist stiffness between the dominant and nondominant limb is likely due to biomechanical adaptations to repetitive asymmetric activities (such as squash, tennis, basketball, or activities of daily living such as writing, teeth brushing, etc.). SIGNIFICANCE: Understanding and quantifying handedness influence on stiffness may have critical implication for the optimization of surgical and rehabilitative interventions.

Simulation and resolution of voltage reversal in microbial fuel cell stack.

To understand the biotic and non-biotic contributions of voltage reversals in microbial fuel cell stacks (MFC) they were simulated with an electronic MFC-Stack mimic. The simulation was then compared with results from a real 3L triple MFC-Stack with shared anolyte. It showed that voltage reversals originate from the variability of biofilms, but also the external load plays a role. When similar biofilm properties were created on all anodes the likelihood of voltage reversals was largely reduced. Homogenous biofilms on all anodes were created by electrical circuit alternation and electrostimulation. Conversely, anolyte recirculation, or increased nutriment supply, postponed reversals and unfavourable voltage asymmetries on anodes persisted. In conclusion, voltage reversals are often a negative event but occur also in close to best MFC-Stack performance. They were manageable and this with a simplified MFC architecture in which multiple anodes share the same anolyte.

Two stage bioethanol refining with multi litre stacked microbial fuel cell and microbial electrolysis cell.

Ethanol, electricity, hydrogen and methane were produced in a two stage bioethanol refinery setup based on a 10L microbial fuel cell (MFC) and a 33L microbial electrolysis cell (MEC). The MFC was a triple stack for ethanol and electricity co-generation. The stack configuration produced more ethanol with faster glucose consumption the higher the stack potential. Under electrolytic conditions ethanol productivity outperformed standard conditions and reached 96.3% of the theoretically best case. At lower external loads currents and working potentials oscillated in a self-synchronized manner over all three MFC units in the stack. In the second refining stage, fermentation waste was converted into methane, using the scale up MEC stack. The bioelectric methanisation reached 91% efficiency at room temperature with an applied voltage of 1.5V using nickel cathodes. The two stage bioethanol refining process employing bioelectrochemical reactors produces more energy vectors than is possible with today's ethanol distilleries.

Scale-up of phosphate remobilization from sewage sludge in a microbial fuel cell.

Phosphate remobilization from digested sewage sludge containing iron phosphate was scaled-up in a microbial fuel cell (MFC). A 3litre triple chambered MFC was constructed. This reactor was operated as a microbial fuel cell and later as a microbial electrolysis cell to accelerate cathodic phosphate remobilization. Applying an additional voltage and exceeding native MFC power accelerated chemical base formation and the related phosphate remobilization rate. The electrolysis approach was extended using a platinum-RVC cathode. The pH rose to 12.6 and phosphate was recovered by 67% in 26h. This was significantly faster than using microbial fuel cell conditions. Shrinking core modelling particle fluid kinetics showed that the reaction resistance has to move inside the sewage sludge particle for considerable rate enhancement. Remobilized phosphate was subsequently precipitated as struvite and inductively coupled plasma mass spectrometry indicated low levels of cadmium, lead, and other metals as required by law for recycling fertilizers.

Single ventricle: repair of atrioventricular valve using the bridging technique.

Atrioventricular valve regurgitation is one of the predictors of adverse outcomes after the Fontan procedure. We describe our surgical technique of GoreTex (W. L. Gore & Associates, Inc., Flagstaff, AZ, USA) bridge to repair a common atrioventricular valve in single-ventricular circulation. The repair includes a GoreTex strip that is secured to the mid-line of both superior and inferior bridging leaflets and annulus to obtain a better coaptation of the leaflets and prevent further dilatation of the annulus. We have applied this technique for 7 consecutive patients with excellent outcomes.

Mansonelliasis, a neglected parasitic disease in Haiti.

Reported in Haiti as early as 1923, Mansonella ozzardi is still a neglected disease ignored by the health authorities of the country. This review is an update on the geographic distribution of the coastal foci of mansonelliasis in Haiti, the epidemiological profile and prevalence rates of microfilariae in people living in endemic areas, the clinical impact of the parasite on health and the efficiency of the transmission of the parasite among three Culicoides biting-midge species identified as vectors in Haiti. Additionally, interest in establishing a treatment programme to combat this parasite using a single dose of ivermectin is emphasised.

Mansonelliasis, a neglected parasitic disease in Haiti

Reported in Haiti as early as 1923, Mansonella ozzardi is still a neglected disease ignored by the health authorities of the country. This review is an update on the geographic distribution of the coastal foci of mansonelliasis in Haiti, the epidemiological profile and prevalence rates of microfilariae in people living in endemic areas, the clinical impact of the parasite on health and the efficiency of the transmission of the parasite among three Culicoides biting-midge species identified as vectors in Haiti. Additionally, interest in establishing a treatment programme to combat this parasite using a single dose of ivermectin is emphasised.

Finite Element simulation of buckling-induced vein tortuosity and influence of the wall constitutive properties.

The mechanisms giving rise to vein tortuosity, which is often associated with varicosis, are poorly understood. Recent works suggest that significant biological changes in the wall of varicose veins may precede the mechanical aspects of the disease. To test the hypothesis of tortuosity being a consequence of these changes, a Finite Element model was developed based on previous experimental work on vein buckling. The model was then used to evaluate the effect of alterations of the mechanical behavior of the wall on tortuosity onset and severity. The results showed that increasing anisotropy toward the circumferential direction promotes tortuosity. An increase in wall stiffness tends to decrease the level of tortuosity but interestingly, if the vein segment is little or not pre-stretched such increase will not prevent, or it will even promote, the onset of tortuosity. These results provide additional arguments supporting the hypothesis of tortuosity being the consequence of biologically-induced changes in the varicose vein wall. Based on a 3D model of the leg and in vivo identification of the material properties of varicose veins, a clinical validation of these findings is being developed.

Differences in extra-cellular matrix and myocyte homeostasis between the neonatal right ventricle in hypoplastic left heart syndrome and truncus arteriosus.

OBJECTIVE: The right ventricle in hypoplastic left heart syndrome (HLHS) works at systemic pressure and large volume loading before and after first stage palliation. There is a paucity of information regarding the intrinsic characteristics of the right ventricle in HLHS. We studied extra-cellular matrix composition, myocyte homeostasis and gene expression in right ventricular biopsies obtained from patients with HLHS undergoing neonatal first stage palliation and from patients undergoing neonatal truncus arteriosus repair. METHODS: Tissue was evaluated using histological and real-time PCR techniques using the truncus group as a comparative group. Mean difference in outcomes between the HLHS and truncus groups was estimated using linear regression models in unadjusted and age-adjusted analyses. RESULTS: Markers of cell proliferation, apoptosis and fibronectin were significantly higher in the right ventricular myocardium of patients with hypoplastic left heart syndrome compared to truncus arteriosus. Type I collagen content and NKX2.5 expression were significantly lower in HLHS than the truncus group. CONCLUSION: The neonatal right ventricle in HLHS demonstrates a number of intrinsic differences compared to the right ventricle in truncus arteriosus including relative immaturity of the extra-cellular matrix, inappropriately low transcription factor expression and increased myocyte apoptosis.

Aortic translocation, Senning procedure and right ventricular outflow tract augmentation for congenitally corrected transposition, ventricular septal defect and pulmonary stenosis.

The management of congenitally corrected transposition of the great arteries and associated lesions is frequently challenging. Significant pulmonary stenosis is a contraindication to the conventional double-switch. Instead repair may be accomplished by the Rastelli-Senning procedure, using an extracardiac conduit to achieve continuity between the morphological left ventricle and the pulmonary arteries. This however can be accompanied by conduit and intra-ventricular baffle-related problems that can necessitate surgical re-intervention and lead to late mortality. We describe the use of aortic translocation, Senning procedure and reconstruction of the right ventricular outflow tract using autologous tissue and valved homograft to facilitate anatomical correction in congenitally corrected transposition. The advantages of this technique in this group of patients and the implications for conduction tissue are discussed.