Reachability Deficits in Quantum Approximate Optimization of Graph Problems

The quantum approximate optimization algorithm (QAOA) has become a cornerstone of contemporary quantum applications development. Here we show that the density of problem constraints versus problem variables acts as a performance indicator. Density is found to correlate strongly with approximation inefficiency for fixed depth QAOA applied to random graph minimization problem instances. Further, the required depth for accurate QAOA solution to graph problem instances scales critically with density. Motivated by Google's recent experimental realization of QAOA, we preform a reanalysis of the reported data reproduced in an ideal noiseless setting. We found that the reported capabilities of instances addressed experimentally by Google, approach a rapid fall-off region in approximation quality experienced beyond intermediate-density. Our findings offer new insight into performance analysis of contemporary quantum optimization algorithms and contradict recent speculation regarding low-depth QAOA performance benefits.

Evolutionary Design of Novel Coolant Passages for Cooling a Square Substrate by Single Stream

Different designs of novel coolant (i.e., water) circuits have been proposed using a well-established constructal law to cool a square substrate made up of aluminum oxide, and subjected to a uniform wall heat flux. Five different flow-path topologies: Case-1 (umbrella-shaped), Case-2 (dumbbell-shaped), Case-3 (hexagonal-shaped), Case-4 (down-arrow-shaped), and Case-5 (up-arrow-shaped) are evolved from a single pipe embedded in the heated substrate. The best cooling pathway has been anticipated by comparing the thermo-fluid characteristics of designs. A numerical route, via Ansys R 16, has been implemented to solve the transport equations for continuity, momentum, and energy along with relevant boundary conditions. The non-dimensional temperature and pressure drop for these cases have been quantified and compared, by varying the length and Reynolds number in the range of 2-3, and 100-2,000, respectively. We observe a decrease in the dimensionless temperature and an increase in the pressure drop with Reynolds number for all the considered pathways. At Re<=500, a rapid fall in the non-dimensional temperature has been noticed; and thereafter, it looks like a plateau for all cases. For Case-4, a minimum temperature is obtained at the non-dimensional pipe length of 2.5. At Lc/L=2.5, we observe that the Case-4 provides better cooling to the substrate among all other designs. Also, the pressure drop for case 4 is not too high as compared to other designs.

Lack of evidence for impaired preload or Bezold-Jarisch activation during brief umbilical cord occlusions in fetal sheep

Impaired cardiac preload secondary to umbilical cord occlusion (UCO) has been hypothesized to contribute to intrapartum decelerations, brief falls in fetal heart rate (FHR), through the activation of the Bezold-Jarisch reflex. This cardioprotective reflex increases parasympathetic and inhibits sympathetic outflows triggering hypotension, bradycardia and peripheral vasodilation but its potential to contribute to intrapartum decelerations has never been systematically examined. In this study we performed bilateral cervical vagotomy to remove the afferent arm and the efferent parasympathetic arm of the Bezold-Jarisch reflex. 22 chronically instrumented fetal sheep at 0.85 of gestation received vagotomy (n=7) or sham-vagotomy (control, n=15), followed by three 1-min complete UCOs separated by 4-min reperfusion periods. UCOs in control fetuses were associated with a rapid fall in FHR and reduced femoral blood flow mediated by intense femoral vasoconstriction, leading to hypertension. Vagotomy abolished the rapid fall in FHR (p<0.001), and despite reduced diastolic filling time, increased both carotid (p<0.001) and femoral (p<0.05) blood flow during UCOs, secondary to carotid vasodilation (p<0.01) and delayed femoral vasoconstriction (p<0.05). Finally, vagotomy was associated with an attenuated rise in cortical impedance during UCOs (p<0.05), consistent with improved cerebral substrate supply. In conclusion, increased carotid and femoral blood flows after vagotomy are consistent with increased left and right ventricular output, which is incompatible with the hypothesis that labor-like UCOs impair ventricular filling. Overall, the cardiovascular responses to vagotomy do not support the hypothesis that the Bezold-Jarisch reflex is activated by UCO. The Bezold-Jarisch reflex is therefore mechanistically unable to contribute to intrapartum decelerations.

Rapid fall in circulating non-classical monocytes in ST elevation myocardial infarction patients correlates with cardiac injury

ObjectiveMyocardial infarction leads to a rapid innate immune response that is ultimately required for repair of damaged heart tissue. We therefore examined circulating monocyte dynamics immediately after reperfusion of the culprit coronary vessel in STEMI patients to determine whether this correlated with level of cardiac injury. A mouse model of cardiac ischaemia/reperfusion injury was subsequently used to establish the degree of monocyte margination to the coronary vasculature that could potentially contribute to the drop in circulating monocytes.Approach and ResultsWe retrospectively analysed blood samples from 51 STEMI patients to assess the number of non-classical (NC), classical and intermediate monocytes immediately following primary percutaneous coronary intervention. Classical and intermediate monocytes showed minimal change. On the other hand circulating numbers of NC monocytes fell by approximately 50% at 90 minutes post-reperfusion. This rapid decrease in NC monocytes was greatest in patients with the largest infarct size (p<0.05) and correlated inversely with left ventricular function (r=0.41, p=0.04). The early fall in NC monocytes post reperfusion was confirmed in a second prospective study of 13 STEMI patients. Furthermore, in a mouse cardiac ischaemia model, there was significant monocyte adhesion to coronary vessel endothelium at 2 hours post-reperfusion pointing to a specific and rapid vessel margination response to cardiac injury.ConclusionsRapid depletion of NC monocytes from the circulation in STEMI patients following coronary artery reperfusion correlates with the level of acute cardiac injury and involves rapid margination to the coronary vasculature.Graphical AbstractHighlights3-5 bullet points that summarize the major findings of the study.Circulating non classical monocytes show a rapid fall in STEMI patients within 90 minutes of re-opening the culprit coronary artery.The extent of the drop in non classical monocytes correlates with loss of cardiac function and increased infarct size.A mouse model of cardiac ischaemia and reperfusion shows rapid margination of monocytes to the coronary vasculature

Cryopreservation of Mesenchymal Stem Cells Using Medical Grade Ice Nucleation Inducer

Mesenchymal stem cells (MSCs) can differentiate into multiple different tissue lineages and have favourable immunogenic potential making them an attractive prospect for regenerative medicine. As an essential part of the manufacturing process, preservation of these cells whilst maintaining potential is of critical importance. An uncontrolled area of storage remains the rate of change of temperature during freezing and thawing. Controlled-rate freezers attempted to rectify this; however, the change of phase from liquid to solid introduces two extreme phenomena; a rapid rise and a rapid fall in temperature in addition to the intended cooling rate (normally −1 °C/min) as a part of the supercooling event in cryopreservation. Nucleation events are well known to initiate the freezing transition although their active use in the form of ice nucleation devices (IND) are in their infancy in cryopreservation. This study sought to better understand the effects of ice nucleation and its active instigation with the use of an IND in both a standard cryotube with MSCs in suspension and a high-throughput adhered MSC 96-well plate set-up. A potential threshold nucleation temperature for best recovery of dental pulp MSCs may occur around −10 °C and for larger volume cell storage, IND and fast thaw creates the most stable process. For adhered cells, an IND with a slow thaw enables greatest metabolic activity post-thaw. This demonstrates a necessity for a medical grade IND to be used in future regenerative medicine manufacturing with the parameters discussed in this study to create stable products for clinical cellular therapies.

Significant Waning of Active Cases of Covid-19 With High Recovery After Three Months of Complete Lockdown: Plausible Implication On Emergence of Herd Immunity in The Population

COVID-19 is fast spreading around the globe in a highly contagious manner. Until date there are no therapeutic agents/vaccines developed which could control this highly infectious virus from spreading among human population. Our earlier studies showed that implementation of prolonged lockdown had a profound effect on the rate of spread of COVID-19 in the population. The observed increase in doubling time of COVID-19 with a high recovery rate following complete Lockdown reflected that protective immunity may be present in the population. In this article, the data from three months following completion of Lockdown was considered. The results reflected that there was a significant down trend in the rate of COVID-19 with high recovery rate reaching up to 83% of the affected cases of COVID-19 by September 30, 2020. The projection made from the data up to 30 November, 2020, pointed towards continued decrease in active cases of COVID-19. Concomitant with this result, the recovery from COVID-19 reached to ~90% by end of October, 2020. The significance of the above mentioned results with rapid fall in active cases from end of September 30, 2020, in spite of increased testing for COVID-19 in generating immunity against COVID-19 is discussed.

COVID-19: The Changing Trend of Tele-consultations in a Private Tertiary Level Health Facility in Tanzania

Introduction: The current COVID-19 pandemic has occasioned the increased adoption of telemedicine. This study reports the uptake and trend of a new teleconsultation service in a Tanzanian hospital.Methods: This is a retrospective observational study that profiled requests for teleconsultations and uptake of the service between April 1, 2020, and June 30, 2020.Results: Two hundred and eighteen telephone inquiries were received over the 3 months. One hundred and sixteen (53.2%) individuals followed through with the teleconsultations. Paediatric (38.8%) and Internal medicine (32.8%) were the subspecialties with the highest number of teleconsultations. In a frame of 3 months, teleconsultation uptake was highest in May and lowest in June.Conclusion: There was a steady rise and a rapid fall in requests and uptake of teleconsultation services over the period under evaluation. Lack of insurance coverage for teleconsultations was a significant barrier. We propose a re-education and reiteration of the benefits of telemedicine to all stakeholders. This is important for the current era and beyond.

Is Fertility a Leading Economic Indicator?

Many papers show that aggregate fertility is pro-cyclical over the business cycle. Using data on more than 100 million births from 1988 to 2014, we show that for recent recessions in the United States, there is a large and rapid fall in the growth rate of conceptions several quarters prior to economic decline. This newly emerging pattern appears in the aggregate data, as well as within individual states and in many European countries. Our findings suggest that fertility behaviour is more forward looking and sensitive to changes in short-run expectations about the economy than previously thought.