7,379 research outputs found
Introduction to neutrino astronomy
This writeup is an introduction to neutrino astronomy, addressed to
astronomers and written by astroparticle physicists. While the focus is on
achievements and goals in neutrino astronomy, rather than on the aspects
connected to particle physics, we will introduce the particle physics concepts
needed to appreciate those aspects that depend on the peculiarity of the
neutrinos. The detailed layout is as follows: In Sect.~1, we introduce the
neutrinos, examine their interactions, and present neutrino detectors and
telescopes. In Sect.~2, we discuss solar neutrinos, that have been detected and
are matter of intense (theoretical and experimental) studies. In Sect.~3, we
focus on supernova neutrinos, that inform us on a very dramatic astrophysical
event and can tell us a lot on the phenomenon of gravitational collapse. In
Sect.~4, we discuss the highest energy neutrinos, a very recent and lively
research field. In Sect.~5, we review the phenomenon of neutrino oscillations
and assess its relevance for neutrino astronomy. Finally, we offer a brief
overall assessment and a summary in Sect.~6. The material is selected - i.e.,
not all achievements are reviewed - and furthermore it is kept to an
introductory level, but efforts are made to highlight current research issues.
In order to help the beginner, we prefer to limit the list of references,
opting whenever possible for review works and books.Comment: 15 pages, 5 figures. Accepted for publication The European Physical
Journal Plus. Based on the lecture given at the "4th Azarquiel School of
Astronomy", June 2017, Porto Paolo di Capo Passero, Syracuse (Italy)
https://agenda.infn.it/conferenceDisplay.py?confId=1208
Design of a test bench for the flow ripple determination in positive-displacement hydraulic pumps
This thesis is about the study of two important characteristic values of positive-displacement pumps, the source flow ripple and the source impedance. The first one represents the flow fluctuations generated inside the pump, while the other one the complex ratio between the pressure fluctuations and the flow ripple occurring at the outlet port of the pump when the Norton model is used.Incomin
Electrokinetic delivery of reagents for groundwater remediation
L'abstract è presente nell'allegato / the abstract is in the attachmen
Designing sustainable cold chains for long-range food distribution: Energy-effective corridors on the Silk Road Belt
Modern food production-distribution processes represent a critical stressor for the environment and for natural ecosystems. The rising flows of food across growing and consumption areas couple with the higher expectations of consumers for the quality of products and compel the intensive use of refrigerated rooms and transport means throughout the food supply chain. In order to aid the design of sustainable cold chains that incorporate such aspects, this paper proposes a mixed integer linear programming model to minimize the total energy consumption associated with the cold operations experienced by perishable products. This model is intended for food traders, logistics practitioners, retail managers, and importers collaboratively called to design and plan a cost and environmentally effective supply strategy, physical channels, and infrastructures for cold chains. The proposed model is validated with a case study inspired by the distribution of two example food products, namely fresh apples and ice cream, along the New Silk Road connecting Europe and China. The illustrated analysis investigates the effect of alternative routes and transport modes on the sustainability of the cold chain. It is found that the most energy-efficient route for ice cream is via rail over a northern route and, for apples, is via a southern maritime route, and, for these two routes, the ratios of the total energy consumed to the energy content of the food are 760 and 913, respectively. By incorporating the energy lost due to the food quality decay, the model identifies the optimal route to adopt in accordance with the shelf life and the conservation temperature of each product
Impaired coronary blood flow at higher heart rates during atrial fibrillation: investigation via multiscale modelling
Background. Different mechanisms have been proposed to relate atrial
fibrillation (AF) and coronary flow impairment, even in absence of relevant
coronary artery disease (CAD). However, the underlying hemodynamics remains
unclear. Aim of the present work is to computationally explore whether and to
what extent ventricular rate during AF affects the coronary perfusion.
Methods. AF is simulated at different ventricular rates (50, 70, 90, 110, 130
bpm) through a 0D-1D multiscale validated model, which combines the left
heart-arterial tree together with the coronary circulation. Artificially-built
RR stochastic extraction mimics the \emph{in vivo} beating features. All the
hemodynamic parameters computed are based on the left anterior descending (LAD)
artery and account for the waveform, amplitude and perfusion of the coronary
blood flow.
Results. Alterations of the coronary hemodynamics are found to be associated
either to the heart rate increase, which strongly modifies waveform and
amplitude of the LAD flow rate, and to the beat-to-beat variability. The latter
is overall amplified in the coronary circulation as HR grows, even though the
input RR variability is kept constant at all HRs.
Conclusions. Higher ventricular rate during AF exerts an overall coronary
blood flow impairment and imbalance of the myocardial oxygen supply-demand
ratio. The combined increase of heart rate and higher AF-induced hemodynamic
variability lead to a coronary perfusion impairment exceeding 90-110 bpm in AF.
Moreover, it is found that coronary perfusion pressure (CPP) is no longer a
good measure of the myocardial perfusion for HR higher than 90 bpm.Comment: 8 pages, 5 figures, 3 table
An Experience in Mentoring: Shaping Young Mathematical Minds
The Math PLUS program is a partnership between Linfield College and a local middle school which seeks to encourage more mathematics in local and regional science fairs. Linfield students are paired with middle school students to mentor science fair projects that are required to have a mathematical focus. We briefly discuss an overview of the program—its goals, structure and execution—before touching on our personal experiences as mentors for Yamhill-Carlton Intermediate School students. We also provide suggestions for improvements for those looking to implement similar programs at their own institution. The program is funded by a Dolciani Mathematics Enrichment Grant
How to classify the stylohyoid complex syndrome in the ICHD
We have read the International Classification of Headache Disorders, third edition (beta) (ICHD-3 beta), and for the first time headaches are attributed to inflammation of the stylohyoid ligament (SL). It is included among the secondary headaches in “Headache or facial pain attributed to disorder of the cranium, neck, eyes, ears, nose, sinuses, teeth, mouth or other facial or cervical structure.
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