Abstract Studies in Physics Education Research show that interdisciplinary approaches in education foster students’ motivation, creativity, curiosity, and interest in physics. We discuss their ...features and potential role in bringing contemporary physics topics to high school and how to use them to integrate formal educational programs. We make an explicit example of the use of storytelling and theatrical techniques to introduce secondary school students to black holes and gravitational wave topics. The Educational Division of the Physics Department at the University of Cagliari designed the activity. Participants were 200 high-school students (17 to 19 years old) from five schools (scientific, humanities) in Sardinia. Through a research questionnaire, we measure the efficacy of using artistic tools to communicate and teach the proposed subjects. We collected 76 answers. Results show that our methodology helps introduce students to contemporary physics themes, fostering their interest and learning of such content. Students from the humanities significantly appreciated the use of poetry and artistic tools more than their scientific peers. Finally, we discuss the potentiality of our approach in orientating students towards a STEAM (STEM and Arts) career.
A large number of algorithms introduced in the literature to find the global minimum of a real function rely on iterative executions of searches of a local minimum. Multistart, tunneling and some ...versions of simulated annealing are methods that produce well-known procedures. A crucial point of these algorithms is to decide whether to perform or not a new local search. In this paper we look for the optimal probability value to be set at each iteration so that by moving from a local minimum to a new one, the average number of function evaluations
evals
is minimal. We find that this probability has to be 0 or 1 depending on the number of function evaluations required by the local search and by the size of the level set at the current point. An implementation based on the above result is introduced. The values required to calculate
evals
are estimated from the history of the algorithm at running time. The algorithm has been tested both for sample problems constructed by the
GKLS
package and for problems often used in the literature. The outcome is compared with recent results.
Presented here is the design of the Mechanical Ventilator Milano (MVM), a novel mechanical ventilator designed for rapid mass production in response to the COVID-19 pandemic to address the urgent ...shortage of intensive therapy ventilators in many countries, and the growing difficulty in procuring these devices through normal supply chains across borders. This ventilator is an electro-mechanical equivalent of the old and reliable Manley Ventilator, and is able to operate in both pressure-controlled and pressure-supported ventilation modes. MVM is optimized for the COVID-19 emergency, thanks to the collaboration with medical doctors in the front line. MVM is designed for large-scale production in a short amount of time and at a limited cost, as it relays on off-the-shelf components, readily available worldwide. Operation of the MVM requires only a source of compressed oxygen (or compressed medical air) and electrical power. Initial tests of a prototype device with a breathing simulator are also presented. Further tests and developments are underway. At this stage the MVM is not yet a certified medical device but certification is in progress.
In recent years, several research studies have investigated the identification of electronic devices through their physical components and properties, both from a theoretical point of view and ...through extensive experimental studies. Results have shown that, in many cases, a very high identification accuracy can be obtained by exploiting imperfections and small differences in the electronic components, which are called fingerprints in this context. Part of these studies have focused on a specific category of electronic device, the mobile phone or smartphone, which is usually equipped with components, such as radio frequency frontends, cameras, micro-electro-mechanical systems, microphones, and speakers that are likely to reveal fingerprints in their digital outputs and then allow the identification of the component and of the mobile phone itself. Keeping the focus on mobile phones, this paper provides a survey of the different techniques for mobile phone identification on the basis of their built-in components. This paper describes the methodology, the classification algorithms, and the types of features that are typically used in literature. Outstanding challenges and research issues are also identified and described, together with an overview of the potential applications of mobile phone fingerprinting. In addition, this paper analyzes the potential privacy risks associated to the tracking of the mobile phone on the basis of its fingerprints and the related mitigation techniques. Finally, it summarizes the main issues and identifies research opportunities and potential future trends for mobile phone fingerprinting.
Current evidence suggests that HER2-driven tumorigenesis requires HER3. This is likely due to the unique ability of HER3 to activate PI3K/Akt pathway signaling, which is not directly accessible to ...HER2. By genetic elimination of HER3 or shRNA knockdown of HER3 in HER2-amplified cancer cells, we find residual HER2-driven activation of PI3K/Akt pathway signaling that is driven by HER2 through direct and indirect mechanisms. Indirect mechanisms involved second messenger pathways, including Ras or Grb2. Direct binding of HER2 to PI3K occurred through p-Tyr1139, which has a weak affinity for PI3K but becomes significant at very high expression and phosphorylation. Mutation of Y1139 impaired the tumorigenic competency of HER2. Total elimination of HER3 expression in HCC1569 HER2-amplified cancer cells significantly impaired tumorigenicity only transiently, overcome by subsequent increases in HER2 expression and phosphorylation with binding and activation of PI3K. In contrast to activation of oncogenes by mutation, activation by overexpression was quantitative in nature: weak intrinsic activities were strengthened by overexpression, with additional gains observed through further increases in expression. Collectively, these data show that progressive functional gains by HER2 can increase its repertoire of activities such as the activation of PI3K and overcome its dependency on HER3.
The intrinsic ability of HER2 to activate PI3K correlates with increased HER2 expression and can supplant the dependency upon HER3 for growth in HER2-amplified cancers.
.
The authors investigate the application of deep convolutional neural networks (CNNs) to the problem of radiometric identification, i.e. the task of authenticating wireless devices on the basis of ...their radio frequency (RF) emissions, which contain features directly related to the physical properties of the wireless devices. They collected digitised RF from 12 wireless devices, and used various techniques to transform the time series derived from the RF to images. A deep CNN is then applied to the images. The authors' results show that the identification performance of the combination of deep CNN with an image representation significantly outperforms conventional methods based on dissimilarity on the original time series. Moreover, a specific comparison among RF-to-image techniques show that on their datasets the wavelet-based approach outperforms other approaches, also in the presence of white Gaussian noise.
The Sources of Financing Constraints Nikolov, Boris; Schmid, Lukas; Steri, Roberto
Journal of financial economics,
02/2021, Letnik:
139, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Which financial frictions drive firms’ financing constraints? We structurally estimate dynamic firm financing models embedding many financial frictions, on panels of public firms and private firms. ...We focus on limited enforcement, moral hazard, and trade-off models and assess which models rationalize best observed corporate policies across various samples. Our tests, based on empirical policy function benchmarks, favor trade-off models for larger public firms, limited commitment models for smaller public firms, and moral hazard models for Private firms. Our estimates suggest significant financing constraints due to agency frictions and highlight the importance of identifying their sources for firm valuation.
ABSTRACT
This paper explores the connection between rising intangible capital and the secular upward trend in U.S. corporate cash holdings. We calibrate a dynamic model with two productive ...assets—tangible and intangible capital—in which only tangible capital can serve as collateral. We highlight the following points: (i) a shift toward intangible capital shrinks firms' debt capacity and leads them to hold more cash, (ii) the effect accounts for three‐quarters of the observed trend in average cash ratios, and (iii) it also accounts for the upward trend of cash ratios in the cross‐section of small and large firms and in the aggregate.
Inhibitors of VEGF (vascular endothelial growth factor)/VEGFR2 (vascular endothelial growth factor receptor 2) are commonly used in the clinic, but their beneficial effects are only observed in a ...subset of patients and limited by induction of diverse relapse mechanisms. We describe the up-regulation of an adaptive immunosuppressive pathway during antiangiogenic therapy, by which PD-L1 (programmed cell death ligand 1), the ligand of the negative immune checkpoint regulator PD-1 (programmed cell death protein 1), is enhanced by interferon-γ-expressing T cells in distinct intratumoral cell types in refractory pancreatic, breast, and brain tumor mouse models. Successful treatment with a combination of anti-VEGFR2 and anti-PD-L1 antibodies induced high endothelial venules (HEVs) in PyMT (polyoma middle T oncoprotein) breast cancer and RT2-PNET (Rip1-Tag2 pancreatic neuroendocrine tumors), but not in glioblastoma (GBM). These HEVs promoted lymphocyte infiltration and activity through activation of lymphotoxin β receptor (LTβR) signaling. Further activation of LTβR signaling in tumor vessels using an agonistic antibody enhanced HEV formation, immunity, and subsequent apoptosis and necrosis in pancreatic and mammary tumors. Finally, LTβR agonists induced HEVs in recalcitrant GBM, enhanced cytotoxic T cell (CTL) activity, and thereby sensitized tumors to antiangiogenic/anti-PD-L1 therapy. Together, our preclinical studies provide evidence that anti-PD-L1 therapy can sensitize tumors to antiangiogenic therapy and prolong its efficacy, and conversely, antiangiogenic therapy can improve anti-PD-L1 treatment specifically when it generates intratumoral HEVs that facilitate enhanced CTL infiltration, activity, and tumor cell destruction.
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