The impact of COVID-19 on small business outcomes and expectations.

To explore the impact of coronavirus disease 2019 (COVID-19) on small businesses, we conducted a survey of more than 5,800 small businesses between March 28 and April 4, 2020. Several themes emerged. First, mass layoffs and closures had already occurred-just a few weeks into the crisis. Second, the risk of closure was negatively associated with the expected length of the crisis. Moreover, businesses had widely varying beliefs about the likely duration of COVID-related disruptions. Third, many small businesses are financially fragile: The median business with more than $10,000 in monthly expenses had only about 2 wk of cash on hand at the time of the survey. Fourth, the majority of businesses planned to seek funding through the Coronavirus Aid, Relief, and Economic Security (CARES) Act. However, many anticipated problems with accessing the program, such as bureaucratic hassles and difficulties establishing eligibility. Using experimental variation, we also assess take-up rates and business resilience effects for loans relative to grants-based programs.

Terahertz radiation from propagating acoustic phonons based on deformation potential coupling.

We report on new THz electromagnetic emission mechanism from deformational coupling of acoustic (AC) phonons with electrons in the propagation medium of non-polar Si. The epicenters of the AC phonon pulses are the surface and interface of a GaP transducer layer whose thickness (d) is varied in nanoscale from 16 to 45 nm. The propagating AC pulses locally modulate the bandgap, which in turn generates a train of electric field pulses, inducing an abrupt drift motion at the depletion edge of Si. The fairly time-delayed THz bursts, centered at different times (t1T H z, t2T H z, and t3T H z), are concurrently emitted only when a series of AC pulses reach the point of the depletion edge of Si, even without any piezoelectricity. The analysis on the observed peak emission amplitudes is consistent with calculations based on the combined effects of mobile charge carrier density and AC-phonon-induced local deformation, which recapitulates the role of deformational potential coupling in THz wave emission in a formulatively distinct manner from piezoelectric counterpart.

Application of Genetic Testing in Unveiling the Diagnosis of Fabry Disease in a Patient with Hypertrophic Cardiomyopathy.

Fabry disease (FD) is a lysosomal storage disorder with an X-linked genetic pattern. It is caused by the genetic mutations in the galactosidase alpha gene on the long arm of the X-chromosome, resulting in the deficiency of the alpha-galactosidase A enzyme activity. This leads to an accumulation of globotriaosylceramide in a variety of cells, including cells in the heart. Left ventricular hypertrophy is one of the most common manifestations of FD involving the heart. Further cardiac disease progression portends significant morbidity and mortality. The early initiation of enzyme replacement therapy is associated with reversal or halting of the disease's progression and an improved clinical outcome. Here, we present the case of a 40-year-old male patient with left ventricular hypertrophy based on the results of a transthoracic echocardiogram and advanced cardiac imaging. He was later diagnosed with FD with the assistance of genetic testing. We also briefly outline the diagnostic challenges and treatment of FD.

Valley and Zeeman Splittings in Multilayer Epitaxial Graphene Revealed by Circular Polarization Resolved Magneto-infrared Spectroscopy.

Circular-polarization-resolved magneto-infrared studies of multilayer epitaxial graphene (MEG) are performed using tunable quantum cascade lasers in high magnetic fields up to 17.5 T. Landau level (LL) transitions in the monolayer and bilayer graphene inclusions of MEG are resolved, and considerable electron-hole asymmetry is observed in the extracted electronic band structure. For monolayer graphene, a four-fold splitting of the n = 0 to n = 1 LL transition is evidenced and attributed to the lifting of the valley and spin degeneracy of the zeroth LL and the broken electron-hole symmetry. The magnetic field dependence of the splitting further reveals its possible mechanisms. The best fit to experimental data yields effective g-factors, gVS* = 6.7 and gZS* = 4.8, for the valley and Zeeman splittings, respectively.

Cardiac Sarcoidosis Presenting as Ventricular Tachycardia.

Cardiac sarcoidosis is a rare clinical diagnosis, but can be identified in autopsy in up to a quarter of patients with sarcoidosis. Bradycardia, heart block, and syncope are often the presenting arrhythmias associated with sarcoidosis, but ventricular tachycardia can also occur. We present a patient presenting in ventricular tachycardia, later found to have multi-organ system involvement of sarcoidosis. The patient required pacemaker, implantable cardioverter-defibrillator, and immunosuppression for management of cardiac sarcoidosis. Patients with cardiac sarcoidosis are at elevated risk for arrhythmias, and patients with ventricular tachycardia and reduced ejection fraction should be evaluated for implantable cardioverter-defibrillator. In conclusion, sarcoid cardiomyopathy can present as ventricular tachycardia, and requires evaluation and management targeted at prevention of sudden cardiac death.

A Review of Commonly Prescribed Antiarrhythmics: Primer for Primary Care Providers, a Case Based Approach.

The incidence of atrial fibrillation has been steadily increasing as our average population continues to age. In addition, many patients with structural heart disease are on antiarrhythmic drugs for prevention of ventricular tachycardia. General practitioners have a large role in co-management of patients with cardiac disease. The general understanding of common antiarrhythmic drugs and underlying mechanism is pivotal to safely prescribe and follow up of patients as they have potent side effects and drug interactions that needs careful consideration. The decision of which antiarrhythmic medication to use should be personalized, as each patient has a variety of co-morbid conditions that may affect the selection of which drug therapy. The ideal use of antiarrhythmic drugs should focus on understanding the basic pharmacology of the medication. This manuscript is not meant to be an in-depth overview of antiarrhythmic therapy, but rather a review of the commonly used antiarrhythmic drugs to assist primary care practitioners on when to consider antiarrhythmic drugs best suited for their patients. Class I and class III antiarrhythmic drugs will be the focus in this manuscript.

A Case of an Acute Myocardial Infarction Post Thrombolytic Treatment of Ischemic Stroke - A Management Dilemma.

Acute ischemic stroke and myocardial infarction are emergency clinical events that require prompt intervention. Concurrent occurrence of both events magnifies the complexity of the clinical management. We present a case of a patient who presented with acute ischemic stroke, complicated by acute myocardial infarction shortly after thrombolytic was administered. This case highlights the importance of individualization of management especially in complex cases where there are no clear specific guidelines to follow.

Ultrafast generation of fundamental and multiple-order phonon excitations in highly enriched (6,5) single-wall carbon nanotubes.

Using a macroscopic ensemble of highly enriched (6,5) single-wall carbon nanotubes, combined with high signal-to-noise ratio and time-dependent differential transmission spectroscopy, we have generated vibrational modes in an ultrawide spectral range (10-3000 cm(-1)). A total of 14 modes were clearly resolved and identified, including fundamental modes of A, E1, and E2 symmetries and their combinational modes involving two and three phonons. Through comparison with continuous wave Raman spectra as well as calculations based on an extended tight-binding model, we were able to identify all the observed peaks and determine the frequencies of the individual and combined modes. We provide a full summary of phonon frequencies for (6,5) nanotubes that can serve as a basic reference with which to refine our understanding of nanotube phonon spectra as well as a testbed for new theoretical models.

Electron and phonon coupling dynamics in low-gap semiconductor: quantum versus classical scale.

We have studied the characteristics of longitudinal-optical-phonon-plasmon coupled (LOPC) mode by using the ultrashort pulsed laser with 45 THz bandwidth as a function of thickness in InAs epilayers, ranging from 10 to 900 nm. We have observed the LOPC modes split into the upper (L(+) mode) and the lower (L(-) mode) branches only in the classical scale, but the longitudinal-optical (LO) phonon peak was persistently observed. The shorter decay time of the plasmon-like L(+) modes rather than the phonon-like L(-) modes should be associated with carrier-carrier scattering which is further considered with diffusion properties in the low-gap semiconductors. This result leads to that the absence of the LOPC modes in a scale less than exciton Bohr radius manifests the role of electron diffusion rather than the carrier screening via drift motion in surface depletion region.

Low-rank human-like agents are trusted more and blamed less in human-autonomy teaming.

If humans are to team with artificial teammates, factors that influence trust and shared accountability must be considered when designing agents. This study investigates the influence of anthropomorphism, rank, decision cost, and task difficulty on trust in human-autonomous teams (HAT) and how blame is apportioned if shared tasks fail. Participants (N = 31) completed repeated trials with an artificial teammate using a low-fidelity variation of an air-traffic control game. We manipulated anthropomorphism (human-like or machine-like), military rank of artificial teammates using three-star (superiors), two-star (peers), or one-star (subordinate) agents, the perceived payload of vehicles with people or supplies onboard, and task difficulty with easy or hard missions using a within-subject design. A behavioural measure of trust was inferred when participants accepted agent recommendations, and a measure of no trust when recommendations were rejected or ignored. We analysed the data for trust using binomial logistic regression. After each trial, blame was apportioned using a 2-item scale and analysed using a one-way repeated measures ANOVA. A post-experiment questionnaire obtained participants' power distance orientation using a seven-item scale. Possible power-related effects on trust and blame apportioning are discussed. Our findings suggest that artificial agents with higher levels of anthropomorphism and lower levels of rank increased trust and shared accountability, with human team members accepting more blame for team failures.

Efficacy of natural antimicrobial peptides versus peptidomimetic analogues: a systematic review.

Aims: This systematic review was carried out to determine whether synthetic peptidomimetics exhibit significant advantages over antimicrobial peptides in terms of in vitro potency. Structural features - molecular weight, charge and length - were examined for correlations with activity. Methods: Original research articles reporting minimum inhibitory concentration  values against Escherichia coli, indexed until 31 December 2020, were searched in PubMed/ScienceDirect/Google Scholar and evaluated using mixed-effects models. Results: In vitro antimicrobial activity of peptidomimetics resembled that of antimicrobial peptides. Net charge significantly affected minimum inhibitory concentration values (p < 0.001) with a trend of 4.6% decrease for increments in charge by +1. Conclusion: AMPs and antibacterial peptidomimetics exhibit similar potencies, providing an opportunity to exploit the advantageous stability and bioavailability typically associated with peptidomimetics.

Percutaneous epicardial left atrial appendage closure: intermediate-term results.

UNLABELLED: Chronic Percutaneous Epicardial Appendage Closure. OBJECTIVES: To assess the chronic safety and feasibility of percutaneous epicardial closure of the left atrial appendage (LAA) guided by electrical navigation. BACKGROUND: Atrial fibrillation (AF) is associated with stroke, and LAA occlusion may be a useful nonpharmacologic strategy for stroke prevention in AF. METHODS: Percutaneous epicardial access was obtained in 6 dogs under general anesthesia. The ligation system included a grabber that captures the LAA guided by local electrograms (EGMs) and a looped hollow suture preloaded with a central wire enabling control and visualization. After a satisfactory position is confirmed the loop is tightened remotely, and the suture cut. Transesophageal echocardiography (TEE) assessed LAA dimensions and flow. LAA EGMs were recorded pre- and postclosure, and neurohormonal markers measured. Pathologic examination was performed. RESULTS: LAA ligation was successful in all dogs. LAA flow was immediately abolished in 5 of 6 dogs. Disappearance of local LAA EGMs following ligation was observed in all animals. Follow-up TEE at mean 54 days (range 23-75 days) documented residual flow in only the first 2 dogs. Prior to necropsy the LAA was examined at thoracotomy in 3 animals. Following a minor design change, complete closure and fibrosis with a remnant atretic LAA was noted in all animals. No damage to adjacent structures was noted. Neurohormonal markers were unchanged. CONCLUSION: Percutaneous epicardial LAA ligation guided by electrical navigation is feasible with promising intermediate-term results in the canine model. The technique may be useful as an alternative to existing methods of LAA obliteration in humans.

The black sheep effect: The case of the deviant ingroup robot.

The black sheep effect (BSE) describes the evaluative upgrading of norm-compliant group members (ingroup bias), and evaluative downgrading of deviant (norm-violating) group members, relative to similar outgroup members. While the BSE has been demonstrated extensively in human groups, it has yet to be shown in groups containing robots. This study investigated whether a BSE towards a 'deviant' robot (one low on warmth and competence) could be demonstrated. Participants performed a visual tracking task in a team with two humanoid NAO robots, with one robot being an ingroup member and the other an outgroup member. The robots offered advice to the participants which could be accepted or rejected, proving a measure of trust. Both robots were also evaluated using questionnaires, proxemics, and forced preference choices. Experiment 1 (N = 18) manipulated robot grouping to test our group manipulation generated ingroup bias (a necessary precursor to the BSE) which was supported. Experiment 2 (N = 72) manipulated the grouping, warmth and competence of both robots, predicting a BSE towards deviant ingroup robots, which was supported. Results indicated that a disagreeable ingroup robot is viewed less favourably than a disagreeable outgroup robot. Furthermore, when interacting with two independent robots, a "majority rule" effect can occur in which each robot's opinion is treated as independent vote, with participants significantly more likely to trust two unanimously disagreeing robots. No effect of warmth was found. The impact of these findings for human-robot team composition are discussed.

Coherent optical and acoustic phonons generated at lattice-matched GaP/Si(0 0 1) heterointerfaces.

Thin GaP films can be grown on an exact Si(0 0 1) substrate with nearly perfect lattice match. We perform all-optical pump-probe measurements to investigate the ultrafast electron-phonon coupling at the buried interface of GaP/Si. Above-bandgap excitation with a femtosecond laser pulse can induce coherent longitudinal optical (LO) phonons both in the GaP overlayer and in the Si substrate. The coupling of the GaP LO phonons with photoexcited plasma is reduced significantly with decreasing GaP layer thickness from 56 to 16 nm due to the quasi-two-dimensional confinement of the plasma. The same laser pulse can also generate coherent longitudinal acoustic phonons in the form of a strain pulse. The strain pulse induces not only a periodic modulation in the optical reflectivity as it propagates in the semiconductor, but also a sharp spike when it arrives at the GaP layer boundary. The acoustic pulse induced at the GaP/Si interface is remarkably stronger than that at the Si surface, suggesting a possible application of the GaP/Si heterostructure as an opto-acoustic transducer. The amplitude and the phase of the reflectivity modulation varies with the GaP layer thickness, which can be understood in terms of the interference caused by the multiple acoustic pulses generated at the top surface and at the buried interface.

Detecting the Photoexcited Carrier Distribution Across GaAs/Transition Metal Oxide Interfaces by Coherent Longitudinal Acoustic Phonons.

A prominent architecture for solar energy conversion layers diverse materials, such as traditional semiconductors (Si, III-V) and transition metal oxides (TMOs), into a monolithic device. The efficiency with which photoexcited carriers cross each layer is critical to device performance and dependent on the electronic properties of a heterojunction. Here, by time-resolved changes in the reflectivity after excitation of an n-GaAs/p-GaAs/TMO (Co3O4, IrO2) device, we detect a photoexcited carrier distribution specific to the p-GaAs/TMO interface through its coupling to phonons in both materials. The photoexcited carriers generate two coherent longitudinal acoustic phonons (CLAPs) traveling in opposite directions, one into the TMO and the other into the p-GaAs. This is the first time a CLAP is reported to originate at a semiconductor/TMO heterojunction. Therefore, these experiments seed future modeling of the built-in electric fields, the internal Fermi level, and the photoexcited carrier density of semiconductor/TMO interfaces within multilayered heterostructures.

Pressure-Guided cryoablation of pulmonary veins in atrial fibrillation: A fast and effective strategy.

BACKGROUND: Cryoballoon ablation of atrial fibrillation (AF) involves successful electrical pulmonary vein isolation (PVI). Pulmonary vein (PV) ostial occlusion with cryoballoon is classically assessed using PV angiography. A pressure-guided technique to assess ostial occlusion has been evaluated in small cohorts with mixed results. We evaluated the efficacy of this pressure-guided PVI technique and its impact on reducing contrast and fluoroscopy time as compared to the traditional approach. METHODS: We evaluated patients with paroxysmal AF, who underwent cryoballoon PVI. Patients prior to January 20th, 2013 underwent confirmation of PV occlusion by angiography only. Patients ablated after this time had PV occlusion initially determined by pressure monitoring and further confirmed by contrast injection into the PV in most cases (Pressure-guided PVI). Differences in the volume of contrast used and fluoroscopy time were evaluated. RESULTS: 46 patients had pressure-guided PVI and29 patients had occlusion of PV confirmed by angiography alone. Pressure-guided PVI was 99.5% successful in ablating AF, which was non-inferior to traditional method of PV isolation. This technique used an average of 8cc of contrast and 21.5min of fluoroscopy time, which was significantly less than the contrast amount used, and fluoroscopy time with angiographic isolation of PV. CONCLUSION: Pressure-guided PVI is an effective method for cryoablation of AF. This method not only significantly reduces the volume of contrast used but also decreases the fluoroscopy without compromising the success of PVI.

Correction: Curiosity Search: Producing Generalists by Encouraging Individuals to Continually Explore and Acquire Skills Throughout Their Lifetime.

[This corrects the article DOI: 10.1371/journal.pone.0162235.].

Curiosity Search: Producing Generalists by Encouraging Individuals to Continually Explore and Acquire Skills throughout Their Lifetime.

Natural animals are renowned for their ability to acquire a diverse and general skill set over the course of their lifetime. However, research in artificial intelligence has yet to produce agents that acquire all or even most of the available skills in non-trivial environments. One candidate algorithm for encouraging the production of such individuals is Novelty Search, which pressures organisms to exhibit different behaviors from other individuals. However, we hypothesized that Novelty Search would produce sub-populations of specialists, in which each individual possesses a subset of skills, but no one organism acquires all or most of the skills. In this paper, we propose a new algorithm called Curiosity Search, which is designed to produce individuals that acquire as many skills as possible during their lifetime. We show that in a multiple-skill maze environment, Curiosity Search does produce individuals that explore their entire domain, while a traditional implementation of Novelty Search produces specialists. However, we reveal that when modified to encourage intra-life behavioral diversity, Novelty Search can produce organisms that explore almost as much of their environment as Curiosity Search, although Curiosity Search retains a significant performance edge. Finally, we show that Curiosity Search is a useful helper objective when combined with Novelty Search, producing individuals that acquire significantly more skills than either algorithm alone.

Modelling of OPNMR phenomena using photon energy-dependent 〈Sz〉 in GaAs and InP.

We have modified the model for optically-pumped NMR (OPNMR) to incorporate a revised expression for the expectation value of the z-projection of the electron spin, 〈Sz〉 and apply this model to both bulk GaAs and a new material, InP. This expression includes the photon energy dependence of the electron polarization when optically pumping direct-gap semiconductors in excess of the bandgap energy, Eg. Rather than using a fixed value arising from coefficients (the matrix elements) for the optical transitions at the k=0 bandedge, we define a new parameter, Sopt(Eph). Incorporating this revised element into the expression for 〈Sz〉, we have simulated the photon energy dependence of the OPNMR signals from bulk semi-insulating GaAs and semi-insulating InP. In earlier work, we matched calculations of electron spin polarization (alone) to features in a plot of OPNMR signal intensity versus photon energy for optical pumping (Ramaswamy et al., 2010). By incorporating an electron spin polarization which varies with pump wavelength into the penetration depth model of OPNMR signal, we are able to model features in both III-V semiconductors. The agreement between the OPNMR data and the corresponding model demonstrates that fluctuations in the OPNMR intensity have particular sensitivity to light hole-to-conduction band transitions in bulk systems. We provide detailed plots of the theoretical predictions for optical pumping transition probabilities with circularly-polarized light for both helicities of light, broken down into illustrative plots of optical magnetoabsorption and spin polarization, shown separately for heavy-hole and light-hole transitions. These plots serve as an effective roadmap of transitions, which are helpful to other researchers investigating optical pumping effects.