28 research outputs found
Monotonic Mechanisms for Selling Multiple Goods
Maximizing the revenue from selling two or more goods has been shown to
require the use of mechanisms, where a higher-valuation buyer
may pay less than a lower-valuation one. Here we show that the restriction to
mechanisms may not just lower the revenue, but may in fact yield
only a of the maximal revenue; more precisely, the
revenue from monotonic mechanisms is no more than k times the simple revenue
obtainable by selling the goods separately, or bundled (where k is the number
of goods), whereas the maximal revenue may be arbitrarily larger. We then study
the class of monotonic mechanisms and its subclass of allocation-monotonic
mechanisms, and obtain useful characterizations and revenue bounds.Comment: http://www.ma.huji.ac.il/hart/publ.html#mech-mono
RawECGNet: Deep Learning Generalization for Atrial Fibrillation Detection from the Raw ECG
Introduction: Deep learning models for detecting episodes of atrial
fibrillation (AF) using rhythm information in long-term, ambulatory ECG
recordings have shown high performance. However, the rhythm-based approach does
not take advantage of the morphological information conveyed by the different
ECG waveforms, particularly the f-waves. As a result, the performance of such
models may be inherently limited. Methods: To address this limitation, we have
developed a deep learning model, named RawECGNet, to detect episodes of AF and
atrial flutter (AFl) using the raw, single-lead ECG. We compare the
generalization performance of RawECGNet on two external data sets that account
for distribution shifts in geography, ethnicity, and lead position. RawECGNet
is further benchmarked against a state-of-the-art deep learning model, named
ArNet2, which utilizes rhythm information as input. Results: Using RawECGNet,
the results for the different leads in the external test sets in terms of the
F1 score were 0.91--0.94 in RBDB and 0.93 in SHDB, compared to 0.89--0.91 in
RBDB and 0.91 in SHDB for ArNet2. The results highlight RawECGNet as a
high-performance, generalizable algorithm for detection of AF and AFl episodes,
exploiting information on both rhythm and morphology
Cumulative Polarization Coexisting with Conductivity at Interfacial Ferroelectrics
Ferroelectricity in atomically thin bilayer structures has been recently
predicted1 and measured[2-4] in two-dimensional (2D) materials with hexagonal
non-centrosymmetric unit-cells. Interestingly, the crystal symmetry translates
lateral shifts between parallel 2D layers to a change of sign in their
out-of-plane electric polarization, a mechanism referred to as
"Slide-Tronics"[4]. These observations, however, have been restricted to
switching between only two polarization states under low charge carrier
densities[5-12], strongly limiting the practical application of the revealed
phenomena[13]. To overcome these issues, one needs to explore the nature of the
polarization that arises in multi-layered van der Waals (vdW) stacks, how it is
governed by intra- and inter-layer charge redistribution, and to which extent
it survives the introduction of mobile charge carriers, all of which are
presently unknown14. To explore these questions, we conduct surface potential
measurements of parallel WSe2 and MoS2 multi-layers with aligned and
anti-aligned configurations of the polar interfaces. We find evenly spaced,
nearly decoupled potential steps, indicating highly confined interfacial
electric fields, which provide means to design multi-state "ladder
ferroelectrics". Furthermore, we find that the internal polarization remains
significant upon electrostatic doping of a mobile charge carrier density as
high as 1013 cm-2, with substantial in-plane conductivity. Using
first-principles calculations based on density functional theory (DFT), we
trace the extra charge redistribution in real and momentum space and identify
an eventual doping-induced depolarization mechanism
Simultaneous multifocal intracranial haemorrhages associated with staphylococcus aureus endocarditis: a plausible role for diclofenac administration
Introduction:Â Intracranial haemorrhage may complicate infective endocarditis, caused by ruptured mycotic aneurysms or haemorrhagic transformation of brain septic emboli. The risk of intracranial bleeding may increase with the use of non-steroidal anti-inflammatory agent (NSAIDs).
Case description: We report on a 53-year-old male patient with a past history of intravenous drug abuse, who was treated with diclofenac (75 mg IM) for a few hours of preceding fever and arthralgia. Seven hours later he was hospitalised with impaired consciousness and hemiparesis. Evaluation revealed multiple intracranial haemorrhages, at least one originating from a mycotic aneurysm. Repeated blood cultures grew methicillin-resistant Staphylococcus aureus (MRSA), and echocardiography revealed a vegetation on the mitral valve, establishing the diagnosis of bacterial endocarditis.
Conclusion:Â The abrupt simultaneous multifocal intracranial bleeds shortly following the administration of NSAIDs for a few hours of febrile disease, one clearly originating from a mycotic aneurism, are exceptional. This raises a possibility of a role for diclofenac the intracranial bleeding diathesis in this unique clinical presentation. Intracranial haemorrhage in the set-up of undiagnosed infective endocarditis (IE) might be added to the long list of potential adverse outcomes of NSAID administration, and the possibility of IE should be considered before their administration for febrile disease of undetermined cause
Conserving European biodiversity across realms
Terrestrial, freshwater, and marine ecosystems are connected via multiple biophysical and ecological processes. Identifying and quantifying links among ecosystems is necessary for the uptake of integrated conservation actions across realms. Such actions are particularly important for species using habitats in more than one realm during their daily or life cycle. We reviewed information on the habitats of 2,408 species of European conservation concern and found that 30% of the species use habitats in multiple realms. Transportation and service corridors, which fragment species habitats, were identified as the most important threat impacting âŒ70% of the species. We examined information on 1,567 European Union (EU) conservation projects funded over the past 25 years, to assess the adequacy of efforts toward the conservation of âmultiârealmâ species at a continental scale. We discovered that less than a third of multiârealm species benefited from projects that included conservation actions across multiple realms. To achieve the EU's conservation target of halting biodiversity loss by 2020 and effectively protect multiârealm species, integrated conservation efforts across realms should be reinforced by: (1) recognizing the need for integrated management at a policy level, (2) revising conservation funding priorities across realms, and (3) implementing integrated landâfreshwaterâsea conservation planning and management
Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world
Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic.
Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality.
Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States.
Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis.
Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection
Shelter availability and human attitudes as drivers of rock hyrax (<i>Procavia capensis</i>) expansion along a ruralâurban gradient
While anthropogenic landâuse changes threaten wildlife globally, some species take advantage of such changes and disperse into urban areas. The wildlife in urban areas often promotes conflicts with humans, notably when the animals are associated with the spread of zoonotic diseases. In Israel, current urban invasion of rock hyraxes ( Procavia capensis ) draws public attention, since the species is a reservoir host of cutaneous leishmaniasis, a serious skin disease. The rock hyrax, however, has seldom been studied in densely populated areas, and the drivers for its urban expansion, as well as its abilities to live and spread in core urban areas, are relatively unknown. Here, we explore the rock hyrax expansion to urban areas process by examining the availability, characteristics and use of shelter along an urban gradient. Our findings suggest that a series of factors determines shelter availability and quality for the rock hyrax, which facilitates its dispersion across the urban gradient. We found that rock hyraxes from the Judean Desert expand to the periâurban region of Jerusalem by colonizing new rocky shelters formed as byâproducts of urban development. With their populations reaching extreme densities in this area and saturating the available shelters, there is some spill over to the adjacent core urban areas where they colonize littered sites, which are made available due to the local socioâeconomic conditions and cultural norms of waste disposal and illegal placement of temporary structures. Our work emphasizes the significance of the urban gradient approach for studying the mechanisms promoting wildlife expansion to cities. Our findings suggest that changes in shelter availability and quality due to urban development, and cultural norms promote shifts of the hyrax population by pushing from the already established areas and pulling into new environment across the urban gradient.</p
Landâuse changes interact with geology to facilitate dispersal of the rock hyrax (<i>Procavia capensis</i>) and leishmaniasis across Israel and the West Bank
Geology plays a fundamental role in establishing species' habitats, determining both physical (e.g., landscape morphology, soil texture) and chemical (e.g., mineral composition, water availability) properties. In the current Anthropocene epoch, human activity is transforming Earth's geology and ecosystems. Yet to date, there have been almost no studies incorporating geology when examining the effect of such landâuse changes on species distribution. This study seeks to uncover how specific landâuse changes interact with geology, in order to explain the recent and rapid expansion of the rock hyrax ( Procavia capensis ) across the mountains of central Israel and the West Bank. Hyraxes are dependent on rock mounds for their habitat, and their expansion seems to be correlated with increasing infrastructure construction. However, their expansion patterns differ among locations, even when the human landâuse is similar. To explain the patterns of hyrax distribution observed over the past 46âyears, we converted geological data into ecological data, which present the probability of the local bedrock breaking into boulders, whether due to either natural or anthropogenic weathering processes. We applied species distribution models (SDMs) and found that the expansion of rock hyrax populations was facilitated by means of the interaction of specific geological units with landâuse practices (e.g., roads and construction), which resulted in the accumulation of large boulders, creating novel habitats and stepping stones in previously unsuitable areas for hyraxes. Since rock hyraxes are major hosts of the leishmaniasis pathogen, the findings from this study offer important insights into the progression and potential outbreaks of the disease in human populations. Understanding the role that geology plays in shaping a species' niche is expected to prove useful in studying the distribution of other wildlife species and is fundamental in studies seeking to predict the potential ecological impacts on local biodiversity associated with landâuse change.</p
Estimation of f-wave Dominant Frequency Using a Voting Scheme
Atrial fibrillation (AF) is the most common heart arrhythmia, characterized by the presence of fibrillatory waves (f-waves) in the ECG. We introduce a voting scheme to estimate the dominant atrial frequency (DAF) of f-waves. Methods: We analysed a subset of Holter recordings obtained from the University of Virginia AF Database. 100 Holter recordings with manually annotated AF events, resulting in a total 363 AF events lasting more than 1 min. The f-waves were extracted using four different template subtraction (TS) algorithms and the DAF was estimated from the first 1-min window of each AF event. A random forest classifier was used. We hypothesized that better extraction of the f-wave meant better AF/non-AF classification using the DAF as the single input feature of the RF model. Results: Performance on the test set, expressed in terms of AF/non-AF classification, was the best when the DAF was computed computed the three best-performing extraction methods. Using these three algorithms in a voting scheme, the classifier obtained AUC=0.60 and the DAFs were mostly spread around 6 Hz, 5.66 (4.83-7.47). Conclusions: This study has two novel contributions: (1) a method for assessing the performance of f-wave extraction algorithms, and (2) a voting scheme for improved DAF estimation
The transcervical approach for parapharyngeal space pleomorphic adenomas: indications and technique.
BACKGROUND: Head and Neck Parapharyngeal space tumors are rare. Pleomorphic Adenomas are the most common Parapharyngeal space tumors. The purpose of this study was to define preoperative criteria for enabling full extirpation of parapharyngeal space pleomorphic adenomas via the transcervical approach while minimizing functional and cosmetic morbidity. METHODS: The surgical records and medical charts of 19 females and 10 males with parapharyngeal space pleomorphic adenomas operated between 1993 and 2012 were reviewed. RESULTS: Fifteen patients were operated by a simple transcervical approach, 13 by a transparotid transcervical approach, and one by a transmandibular transcervical approach. Complications included facial nerve paralysis, infection, hemorrhage and first bite syndrome. There were three recurrences, but neither recurrence nor complications were associated with the type of surgical approach. CONCLUSION: A simple transcervical approach is preferred for parapharyngeal space pleomorphic adenomas with narrow attachments to the deep lobe of the parotid gland and for pleomorphic adenomas originating in a minor salivary gland within the parapharyngeal space