Asymptotic of grazing collisions and particle approximation for the Kac equation without cutoff

The subject of this article is the Kac equation without cutoff. We first show that in the asymptotic of grazing collisions, the Kac equation can be approximated by a Fokker-Planck equation. The convergence is uniform in time and we give an explicit rate of convergence. Next, we replace the small collisions by a small diffusion term in order to approximate the solution of the Kac equation and study the resulting error. We finally build a system of stochastic particles undergoing collisions and diffusion, that we can easily simulate, which approximates the solution of the Kac equation without cutoff. We give some estimates on the rate of convergence.Comment: 37 pages, 6 figure

Disseny i construcció d'una sonda atmosfèrica

The project consists of the construction of a functional meteorological probe, controlled by an Arduino microcontroller. This probe was design to measure pressure and temperature as functions of the altitude. This device is the first of its kind built at the EETAC, thus a considerable effort of requirement definition has been done. In the present report we describe how all the probesystems were designed, and all the necessary components as well as the reason why they were chosen are described. The resulting design is modular in order to facilitate future improvements/expansions.The steps necessary for the assembly of all the components in a common structure are detailed, as well as the choice of tools and materials. All the systems developed were tested simulating conditions similar to those expected in the real mission.Finally, after the construction and validation processes, all the materials and the tasks needed to launch the probe up to at an altitude of 35 km are detailed.The present report is intended to serve as a guide for futuresimilar projects in EETAC. The resulting device from this work is named FourCast after our surnames

At-risk brand relationships and threats to the bottom line

Like a stock portfolio, each relationship type offers a brand higher or lower growth opportunities and risks. The type of relationship is particularly relevant in brand crisis events. When a brand is hit by a crisis, it is not necessarily the most successful strategy to focus exclusively on protecting positive emotional relationships. At-risk relationships are affected more than others and can lead to a significant decline of brand value. Our cases highlight that at-risk relationships represent a critical, but often overlooked, aspect of a brand’s relationship portfolio. Risks range from negative word of mouth that might have a negative impact on potential new customers to clear retention risk. Marketers should manage these risks proactively by identifying and investigating the nature of their customer relationships and by responding frankly and credibly to crisis events.Published versio

A water-soluble supramolecular polymeric dual sensor for temperature and pH with an associated direct visible readout

We report a multi-stimuli responsive polymeric sensor consisting of a pseudorotaxane-like architecture fabricated from a 1,5-diaminonaphthalene end-functionalized poly(N-isopropyl)acrylamide (Napht-N-PNIPAM) and cyclobis(paraquat-p-phenylene) (CBPQT4+,4Cl-). The coloured nature of the poly-pseudorotaxane provides a sensor for temperature and pH in water with an associated visible readout. To create this dual responsive polymeric sensor, a new chain transfer agent (Napht-N-CTA) incorporating a pH-responsive 1,5-diaminonaphthalene unit was synthesized and used for the polymerization of N-isopropylacrylamide via Reversible Addition-Fragmentation Chain Transfer (RAFT). The ability of Napht-N-PNIPAM to form a pseudorotaxane architecture with CBPQT4+,4Cl- in aqueous media was studied by means of UV-Vis, NMR (1H, 2D-ROESY, DOSY) and ITC experiments. Interestingly, the pseudorotaxane architecture can be reversibly dissociated upon either heating the sample above its cloud point or protonating the nitrogen atoms of the 1,5-diaminonaphthalene-based guest unit by adjusting the pH to around 1. ln both cases a dramatic colour change occurs from intense blue-green to colourless

An Exploration of Technology Leadership in Three Maine Public School Districts

The promise of technology for positively influencing student outcomes is being hampered by a lack of understanding of who is leading technology in public schools and differing beliefs of technology use among technology leaders. The purpose of this qualitative multi-case study was to describe and understand the nature of technology leadership in three Maine public school districts. Research questions explored the roles, responsibilities, values, and beliefs of the technology leaders and examined how technology leaders mobilized stakeholders in using technology to positively influence student outcomes. Fifteen participants were interviewed from across three case sites. Data analysis was guided by the conceptual frameworkusing a “bottom-up” inductive approach. From the results of the study, technology leadership is defined as the enactment of a shared vision for learning with technology that: incorporates the values and beliefs of the technology leaders, teachers, and staff; utilizes a leadership framework where all technology leaders can lead in an atmosphere of trust; and uses adaptive leadership strategies (Heifetz, 1994) to mobilize technology leaders, teachers, and staff in using technology for the enhancement of student learning

Two Stories of Cancel Culture. How Value-Driven Calls to Cancel Affect the Bottom Line

[EN] Social media has become the environment for value-driven polemics that have been commonly dubbed cancel culture. As a construct, cancel culture has little empirical research especially as it relates to the efficacy of the calls to cancel a business. This research analyzes a successful call to cancel, evidenced in a break in sales for Abercrombie & Fitch, and an unsuccessful call to cancel directed toward Starbucks. The sentiments of tweets for both companies were reduced to a valenced level for the core emotions, using a one-dimensional k-mean clustering, for each fiscal quarter. Correlational and time-series analysis was performed. A successful call to cancel showed a structural break in sales but not in Altman’s z-score. The polemic differences in the emotions were strongly correlated to sales for the successful call to cancel but were not present in the unsuccessful case. Likewise, the time-series analysis showed Granger-causality between emotions and the sales for a successful call to cancel. In both the successful and unsuccessful campaigns, individual emotions were ultimately found to be representing two factors present in the 8-emotion model- positive and negative sentiment. This research supports the threshold model of consumer decision-making while calling into question the granular nature of emotions.Reyes-Fournier, P.; Reyes-Fournier, E.; Bracken, D. (2023). Two Stories of Cancel Culture. How Value-Driven Calls to Cancel Affect the Bottom Line. Editorial Universitat Politècnica de València. 81-82. http://hdl.handle.net/10251/201693818

X-ray Spectroscopy of the Radiation-Driven Winds of Massive Stars: Line Profile and Line Ratio Diagnostics

Massive stars drive powerful, supersonic winds via the radiative momentum associated with the thermal UV emission from their photospheres. Shock phenomena are ubiquitous in these winds, heating them to millions, and sometimes tens of millions, of degrees. The emission line spectra from the shock-heated plasma provide powerful diagnostics of the winds' physical conditions, which in turn provide constraints on models of wind shock heating. Here I show how x-ray line transfer is affected by photoelectric absorption in the partially ionized component of the wind and how it can be modeled to determine the astrophysically important mass-loss rates of these stellar winds. I also discuss how photoexcitation out of metastable excited levels of helium-like ions can provide critical information about the location of the hot plasma in magnetically channeled massive star winds.Comment: Invited talk presented at the 16th International Conference on Atomic Processes in Plasmas, Monterey, CA, March 2009; will appear in an AIP-published conference proceedings. 10 pages, 4 figures (2 color, but color not crucial

The Impact of Antihypertensive Drugs on the Number and Risk of Death, Stroke and Myocardial Infarction in the United States

Estimating the value of medical innovation is a continual challenge. In this research, we quantify the impact of antihypertensive therapy on U.S. blood pressures, risk and number of heart attacks, strokes, and deaths. We also consider the potential for further improvements. We estimate the value of innovation using equations relating blood pressure to adverse outcomes from the Framingham Heart Study. Our results show that without antihypertensive therapy, 1999-2000 average blood pressure for the U.S. population age 40 plus would have been 10-13 percent higher. 86,000 excess premature deaths from cardiovascular disease (2001), and 833,000 hospital discharges for stroke and heart attacks (2002) would have occurred. Life expectancy would be 0.5 (men) and 0.4 (women) years lower. At guideline care, there would have been 89,000 fewer premature deaths (2001) and 420,000 fewer hospital discharges for stroke and heart attack (2002) than observed. Our analysis suggests that antihypertensive therapy has had a significant impact on cardiovascular health outcomes but that mortality gains would have been approximately twice as high if guideline care had been achieved for all.

The WHY in Business Processes: Discovery of Causal Execution Dependencies

A crucial element in predicting the outcomes of process interventions and making informed decisions about the process is unraveling the genuine relationships between the execution of process activities. Contemporary process discovery algorithms exploit time precedence as their main source of model derivation. Such reliance can sometimes be deceiving from a causal perspective. This calls for faithful new techniques to discover the true execution dependencies among the tasks in the process. To this end, our work offers a systematic approach to the unveiling of the true causal business process by leveraging an existing causal discovery algorithm over activity timing. In addition, this work delves into a set of conditions under which process mining discovery algorithms generate a model that is incongruent with the causal business process model, and shows how the latter model can be methodologically employed for a sound analysis of the process. Our methodology searches for such discrepancies between the two models in the context of three causal patterns, and derives a new view in which these inconsistencies are annotated over the mined process model. We demonstrate our methodology employing two open process mining algorithms, the IBM Process Mining tool, and the LiNGAM causal discovery technique. We apply it on a synthesized dataset and on two open benchmark data sets.Comment: 20 pages, 19 figure