Finiteness properties of automorphism spaces of manifolds with finite fundamental group.

Given a closed smooth manifold M of even dimension 2 n ≥ 6 with finite fundamental group, we show that the classifying space B Diff ( M ) of the diffeomorphism group of M is of finite type and has finitely generated homotopy groups in every degree. We also prove a variant of this result for manifolds with boundary and deduce that the space of smooth embeddings of a compact submanifold N ⊂ M of arbitrary codimension into M has finitely generated higher homotopy groups based at the inclusion, provided the fundamental group of the complement is finite. As an intermediate result, we show that the group of homotopy classes of simple homotopy self-equivalences of a finite CW complex with finite fundamental group is up to finite kernel commensurable to an arithmetic group.

A low-cost, highly functional, emergency use ventilator for the COVID-19 crisis.

Respiratory failure complicates most critically ill patients with COVID-19 and is characterized by heterogeneous pulmonary parenchymal involvement, profound hypoxemia and pulmonary vascular injury. The high incidence of COVID-19 related respiratory failure has exposed critical shortages in the supply of mechanical ventilators, and providers with the necessary skills to treat. Traditional mass-produced ventilators rely on an internal compressor and mixer to moderate and control the gas mixture delivered to a patient. However, the current emergency has energized the pursuit of alternative designs, enabling greater flexibility in supply chain, manufacturing, storage, and maintenance considerations. To achieve this, we hypothesized that using the medical gasses and flow interruption strategy would allow for a high performance, low cost, functional ventilator. A low-cost ventilator designed and built-in accordance with the Emergency Use guidance from the US Food and Drug Administration (FDA) is presented wherein pressurized medical grade gases enter the ventilator and time limited flow interruption determines the ventilator rate and tidal volume. This simple strategy obviates the need for many components needed in traditional ventilators, thereby dramatically shortening the time from storage to clinical deployment, increasing reliability, while still providing life-saving ventilatory support. The overall design philosophy and its applicability in this new crisis is described, followed by both bench top and animal testing results used to confirm the precision, safety and reliability of this low cost and novel approach to mechanical ventilation. The ventilator meets and exceeds the critical requirements included in the FDA emergency use guidelines. The ventilator has received emergency use authorization from the FDA.

A Method and Analysis to Enable Efficient Piezoelectric Transducer-Based Ultrasonic Power and Data Links for Miniaturized Implantable Medical Devices.

Acoustic links for implantable medical devices (implants) have gained attention primarily because they provide a route to wireless deep-tissue systems. The miniaturization of the implants is a key research goal in these efforts, nominally because smaller implants result in less acute tissue damage. Implant size in most acoustic systems is limited by the piezoelectric bulk crystal used for power harvesting and data communication. Further miniaturization of the piezocrystal can degrade system power transfer efficiency and data transfer reliability. Here, we present a new method for packaging the implant piezocrystal; the method maximizes power transfer efficiency ( η ) from the acoustic power at the piezo surface to the power delivered to the electrical load and information transfer across the acoustic link. Our method relies on placing piezo-to-substrate anchors to the piezo regions where the vibrational displacement of the mode of interest is zero. To evaluate our method, we investigated packaged 1×1×1 mm3 piezocrystals assembled with different sized anchors. Our results show that reducing the anchor size decreases anchor loss and thus improves piezo quality factor (Q). We also demonstrate that this method improves system electromechanical coupling. A strongly coupled, high-Q piezo with properly sized and located anchors is demonstrated to achieve significantly higher η and superior data transfer capability at resonance. Overall, this work provides an analysis and generic method for packaging the implant piezocrystal that enables the design of efficient acoustic power and data links, which provides a path toward the further miniaturization of ultrasonic implants to submillimeter scales.

Inferring the Flavor of High-Energy Astrophysical Neutrinos at Their Sources.

The sources and production mechanisms of high-energy astrophysical neutrinos are largely unknown. A promising opportunity for progress lies in the study of neutrino flavor composition, i.e., the proportion of each flavor in the flux of neutrinos, which reflects the physical conditions at the sources. To seize it, we introduce a Bayesian method that infers the flavor composition at the neutrino sources based on the flavor composition measured at Earth. We find that the present data from the IceCube neutrino telescope favor neutrino production via the decay of high-energy pions and rule out production via the decay of neutrons. In the future, improved measurements of flavor composition and mixing parameters may single out the production mechanism with high significance.

Echo Technique to Distinguish Flavors of Astrophysical Neutrinos.

The flavor composition of high-energy astrophysical neutrinos is a rich observable. However, present analyses cannot effectively distinguish particle showers induced by ν_{e} vs ν_{τ}. We show that this can be accomplished by measuring the intensities of the delayed, collective light emission from muon decays and neutron captures, which are, on average, greater for ν_{τ} than for ν_{e}. This new technique would significantly improve tests of the nature of astrophysical sources and of neutrino properties. We discuss the promising prospects for implementing it in IceCube and other detectors.

Universe's Worth of Electrons to Probe Long-Range Interactions of High-Energy Astrophysical Neutrinos.

Astrophysical searches for new long-range interactions complement collider searches for new short-range interactions. Conveniently, neutrino flavor oscillations are keenly sensitive to the existence of long-ranged flavored interactions between neutrinos and electrons, motivated by lepton-number symmetries of the standard model. For the first time, we probe them using TeV-PeV astrophysical neutrinos and accounting for all large electron repositories in the local and distant Universe. The high energies and colossal number of electrons grant us unprecedented sensitivity to the new interaction, even if it is extraordinarily feeble. Based on IceCube results for the flavor composition of astrophysical neutrinos, we set the ultimate bounds on long-range neutrino flavored interactions.

Extracting the Energy-Dependent Neutrino-Nucleon Cross Section above 10 TeV Using IceCube Showers.

Neutrinos are key to probing the deep structure of matter and the high-energy Universe. Yet, until recently, their interactions had only been measured at laboratory energies up to about 350 GeV. An opportunity to measure their interactions at higher energies opened up with the detection of high-energy neutrinos in IceCube, partially of astrophysical origin. Scattering off matter inside Earth affects the distribution of their arrival directions-from this, we extract the neutrino-nucleon cross section at energies from 18 TeV to 2 PeV, in four energy bins, in spite of uncertainties in the neutrino flux. Using six years of public IceCube High-Energy Starting Events, we explicitly show for the first time that the energy dependence of the cross section above 18 TeV agrees with the predicted softer-than-linear dependence, and reaffirm the absence of new physics that would make the cross section rise sharply, up to a center-of-mass energy sqrt[s]≈1 TeV.

Intsy: a low-cost, open-source, wireless multi-channel bioamplifier system.

OBJECTIVE: Multi-channel electrical recordings of physiologically generated signals are common to a wide range of biomedical fields. The aim of this work was to develop, validate, and demonstrate the practical utility of a high-quality, low-cost 32/64-channel bioamplifier system with real-time wireless data streaming capability. APPROACH: The new 'Intsy' system integrates three main off-the-shelf hardware components: (1) Intan RHD2132 bioamplifier; (2) Teensy 3.2 microcontroller; and (3) RN-42 Bluetooth 2.1 module with a custom LabView interface for real-time data streaming and visualization. Practical utility was validated by measuring serosal gastric slow waves and surface EMG on the forearm with various contraction force levels. Quantitative comparisons were made to a gold-standard commercial system (Biosemi ActiveTwo). MAIN RESULTS: Intsy signal quality was quantitatively comparable to that of the ActiveTwo. Recorded slow wave signals had high SNR (24 ± 2.7 dB) and wavefront propagation was accurately mapped. EMG spike bursts were characterized by high SNR (⩾10 dB) and activation timing was readily identified. Stable data streaming rates achieved were 3.5 kS s-1 for wireless and 64 kS s-1 for USB-wired transmission. SIGNIFICANCE: Intsy has the highest channel count of any existing open-source, wireless-enabled module. The flexibility, portability and low cost ($1300 for the 32-channel version, or $2500 for 64 channels) of this new hardware module reduce the entry barrier for a range of electrophysiological experiments, as are typical in the gastrointestinal (EGG), cardiac (ECG), neural (EEG), and neuromuscular (EMG) domains.

A self-sustaining high-strength wastewater treatment system using solar-bio-hybrid power generation.

This study focuses on system analysis of a self-sustaining high-strength wastewater treatment concept combining solar technologies, anaerobic digestion, and aerobic treatment to reclaim water. A solar bio-hybrid power generation unit was adopted to power the wastewater treatment. Concentrated solar power (CSP) and photovoltaics (PV) were combined with biogas energy from anaerobic digestion. Biogas is also used to store the extra energy generated by the hybrid power unit and ensure stable and continuous wastewater treatment. It was determined from the energy balance analysis that the PV-bio hybrid power unit is the preferred energy unit to realize the self-sustaining high-strength wastewater treatment. With short-term solar energy storage, the PV-bio-hybrid power unit in Phoenix, AZ requires solar collection area (4032m2) and biogas storage (35m3), while the same unit in Lansing, MI needs bigger solar collection area and biogas storage (5821m2 and 105m3, respectively) due to the cold climate.

Theoretically Palatable Flavor Combinations of Astrophysical Neutrinos.

The flavor composition of high-energy astrophysical neutrinos can reveal the physics governing their production, propagation, and interaction. The IceCube Collaboration has published the first experimental determination of the ratio of the flux in each flavor to the total. We present, as a theoretical counterpart, new results for the allowed ranges of flavor ratios at Earth for arbitrary flavor ratios in the sources. Our results will allow IceCube to more quickly identify when their data imply standard physics, a general class of new physics with arbitrary (incoherent) combinations of mass eigenstates, or new physics that goes beyond that, e.g., with terms that dominate the Hamiltonian at high energy.

Effective Stimulus Parameters for Directed Locomotion in Madagascar Hissing Cockroach Biobot.

Swarms of insects instrumented with wireless electronic backpacks have previously been proposed for potential use in search and rescue operations. Before deploying such biobot swarms, an effective long-term neural-electric stimulus interface must be established, and the locomotion response to various stimuli quantified. To this end, we studied a variety of pulse types (mono- vs. bipolar; voltage- vs. current-controlled) and shapes (amplitude, frequency, duration) to parameters that are most effective for evoking locomotion along a desired path in the Madagascar hissing cockroach (G. portentosa) in response to antennal and cercal stimulation. We identified bipolar, 2 V, 50 Hz, 0.5 s voltage controlled pulses as being optimal for evoking forward motion and turns in the expected contraversive direction without habituation in ≈50% of test subjects, a substantial increase over ≈10% success rates previously reported. Larger amplitudes for voltage (1-4 V) and current (50-150 µA) pulses generally evoked larger forward walking (15.6-25.6 cm; 3.9-5.6 cm/s) but smaller concomitant turning responses (149 to 80.0 deg; 62.8 to 41.2 deg/s). Thus, the radius of curvature of the initial turn-then-run locomotor response (≈10-25 cm) could be controlled in a graded manner by varying the stimulus amplitude. These findings could be used to help optimize stimulus protocols for swarms of cockroach biobots navigating unknown terrain.

Neutrino and cosmic-ray emission from multiple internal shocks in gamma-ray bursts.

Gamma-ray bursts (GRBs) are short-lived, luminous explosions at cosmological distances, thought to originate from relativistic jets launched at the deaths of massive stars. They are among the prime candidates to produce the observed cosmic rays at the highest energies. Recent neutrino data have, however, started to constrain this possibility in the simplest models with only one emission zone. In the classical theory of GRBs, it is expected that particles are accelerated at mildly relativistic shocks generated by the collisions of material ejected from a central engine. Here we consider neutrino and cosmic-ray emission from multiple emission regions since these internal collisions must occur at very different radii, from below the photosphere all the way out to the circumburst medium, as a consequence of the efficient dissipation of kinetic energy. We demonstrate that the different messengers originate from different collision radii, which means that multi-messenger observations open windows for revealing the evolving GRB outflows.

Experiencia y resultados en cirugía de disección aórtica tipo A durante una década en la Fundación Valle del Lili, Cali, Colombia / Experience and results in surgery of type A aortic dissection during a decade in the Fundación Valle del Lili, Cali, Colombia

Antecedentes: la disección aórtica tipo A continúa siendo una enfermedad con alto riesgo de muerte, que por ende requiere un diagnóstico rápido y manejo quirúrgico inmediato. Objetivo: reportar la experiencia y los resultados en cirugía de disección aórtica tipo A durante una década. Métodos: se realizó un estudio descriptivo, retrospectivo, mediante la revisión de historias clínicas de los pacientes atendidos entre enero de 2001 y diciembre de 2010. Se seleccionaron 58 pacientes con diagnóstico de disección aórtica tipo A, que cumplían con los criterios de inclusión y se analizaron variables demográficas, clínicas, intra y post-operatorias. Resultados: 79,3% de los pacientes fueron hombres; con una mediana de edad de 56 años. Los tiempos promedio para pinza aórtica, bomba y arresto fueron 136, 223 y 39 minutos, respectivamente. Los procedimientos más frecuentes fueron reemplazo de aorta ascendente y cirugía de Bentall en 34,5% de los casos cada uno. La mediana de estancia en la unidad de cuidado intensivo fue de seis y doce días para el total de hospitalización. Se reportaron complicaciones en 36,2% de los casos; la principal fue sepsis de cualquier causa en 20% de los pacientes. La mortalidad intrahospitalaria fue de 24% y la supervivencia a 28 días fue superior a 70%. Conclusiones: según nuestra casuística, la mortalidad observada no difiere mucho a la que se reporta en registros multicéntricos internacionales, en los cuales sigue siendo elevada, lo cual resalta la importancia del diagnóstico temprano y el manejo quirúrgico inmediato, que implica un esfuerzo humano e institucional considerable. Palabras clave: síndrome aórtico agudo, disección de aorta, cirugía cardíaca, mortalidad. Background: type A aortic dissection is still a disease with a high risk of death. Therefore it requires prompt diagnosis and immediate surgical management. Objective: to report our experience and results in surgery of type A aortic dissection during a decade. Methods: a descriptive, retrospective study, by reviewing medical records of patients treated between January 2001 and December 2010 was realized. 58 patients diagnosed as type A aortic dissection who met the inclusion criteria were selected, and demographic, clinical, intra and post-operative variables were analyzed. Results: 79.3% of the patients were men, with a median age of 56 years. The mean times for aortic clamp, pump and arrest were 136, 223 and 39 minutes, respectively. The most frequent procedures were ascending aortic replacement and Bentall surgery in 34.5% of cases each one. The median stay in the ICU was six days and overall hospitalization was twelve days. Complications were reported in 36.2% of cases. The main one was sepsis from any cause in 20% of patients. In-hospital mortality was 24% and survival at 28 days was higher than 70%. Conclusions: according to our casuistics, the observed mortality is not very different to that reported in international multicenter registries which remains still high. This fact highlights the importance of early diagnosis and immediate surgical management, implying a significant human and institutional effort.

Background: type A aortic dissection is still a disease with a high risk of death. Therefore it requires prompt diagnosis and immediate surgical management. Objective: to report our experience and results in surgery of type A aortic dissection during a decade. Methods: a descriptive, retrospective study, by reviewing medical records of patients treated between January 2001 and December 2010 was realized. 58 patients diagnosed as type A aortic dissection who met the inclusion criteria were selected, and demographic, clinical, intra and post-operative variables were analyzed. Results: 79.3% of the patients were men, with a median age of 56 years. The mean times for aortic clamp, pump and arrest were 136, 223 and 39 minutes, respectively. The most frequent procedures were ascending aortic replacement and Bentall surgery in 34.5% of cases each one. The median stay in the ICU was six days and overall hospitalization was twelve days. Complications were reported in 36.2% of cases. The main one was sepsis from any cause in 20% of patients. In-hospital mortality was 24% and survival at 28 days was higher than 70%. Conclusions: according to our casuistics, the observed mortality is not very different to that reported in international multicenter registries which remains still high. This fact highlights the importance of early diagnosis and immediate surgical management, implying a significant human and institutional effort.

Comparison of water availability effect on ammonia-oxidizing bacteria and archaea in microcosms of a Chilean semiarid soil.

Water availability is the main limiting factor in arid soils; however, few studies have examined the effects of drying and rewetting on nitrifiers from these environments. The effect of water availability on the diversity of ammonia-oxidizing bacteria (AOB) and archaea (AOA) from a semiarid soil of the Chilean sclerophyllous matorral was determined by microcosm assays. The addition of water every 14 days to reach 60% of the WHC significantly increased nitrate content in rewetted soil microcosms (p < 0.001). This stimulation of net nitrification by water addition was inhibited by acetylene addition at 100 Pa. The composition of AOA and AOB assemblages from the soils microcosms was determined by clone sequencing of amoA genes (A-amoA and B-amoA, respectively), and the 16S rRNA genes specific for ß-proteobacteria (beta-amo). Sequencing of beta-amo genes has revealed representatives of Nitrosomonas and Nitrosospira while B-amoA clones consisted only of Nitrosospira sequences. Furthermore, all clones from the archaeal amoA gene library (A-amoA) were related to "mesophilic Crenarchaeota" sequences (actually, reclassified as the phylum Thaumarchaeota). The effect of water availability on both microbial assemblages structure was determined by T-RFLP profiles using the genetic markers amoA for archaea, and beta-amo for bacteria. While AOA showed fluctuations in some T-RFs, AOB structure remained unchanged by water pulses. The relative abundance of AOA and AOB was estimated by the Most Probable Number coupled to Polymerase Chain Reaction (MPN-PCR) assay. AOB was the predominant guild in this soil and higher soil water content did not affect their abundance, in contrast to AOA, which slightly increased under these conditions. Therefore, these results suggest that water addition to these semiarid soil microcosms could favor archaeal contribution to ammonium oxidation.

Peroxisome proliferator-activated receptors: Targets for the treatment of metabolic illnesses (Review).

Peroxisome proliferator-activated receptors (PPARs) belong to a family of transcription factors of which three isotypes, PPARα, PPARδ (ß) and PPARγ, are known. These play a central role in regulating intermediate metabolism and in incidences of inflammation. In recent years, a greater understanding of their mechanisms of action and their effects, principally in the management of cardiovascular disease, has been achieved. PPAR agonists, catalysts and agents have been used since the 1990s, when it was confirmed that fibrates possess lipid modifying properties when selectively activating PPARα. In addition, thiazolidinediones, structures analogous to fibrates, showed PPARγ activity with an insulin-sensitizing effect, leading to their use in the control and even prevention of diabetes mellitus type 2. Currently, studies are oriented to the development of agents that activate multiple PPAR isoforms - not only dual (PPARα/γ), but also PPAR panagonists (α/γ/δ). The purpose of this review is to explain the mechanisms of the molecular action and the effects of PPAR agonists, and also to analyze existing and current studies concerning their use in cardiovascular and metabolic illnesses.