Francesco Piras

Role of heart rate and stroke volume during muscle metaboreflex-induced cardiac output increase: differences between activation during and after exercise

We hypothesized that the role of stroke volume (SV) in the metaboreflex-induced cardiac output (CO) increase was blunted when the metaboreflex was stimulated by exercise muscle ischemia (EMI) compared with post-exercise muscle ischemia (PEMI), because during EMI heart rate (HR) increases and limits diastolic filling. Twelve healthy volunteers were recruited and their hemodynamic responses to the metaboreflex evoked by EMI, PEMI, and by a control dynamic exercise were assessed. The main finding was that the blood pressure increment was very similar in the EMI and PEMI settings. In both conditions the main mechanism used to raise blood pressure was a CO elevation. However, during the EMI test CO was increased as a result of HR elevation whereas during the PEMI test CO was increased as a result of an increase in SV. These results were explainable on the basis of the different HR behavior between the two settings, which in turn led to different diastolic time and myocardial performance.

Estimating stroke volume from oxygen pulse during exercise.

This investigation aimed at verifying whether it was possible to reliably assess stroke volume (SV) during exercise from oxygen pulse (OP) and from a model of arterio-venous oxygen difference (a-vO(2)D) estimation. The model was tested in 15 amateur male cyclists performing an exercise test on a cycle-ergometer consisting of a linear increase of workload up to exhaustion. Starting from the analysis of previous published data, we constructed a model of a-vO(2)D estimation (a-vO(2)D(est)) which predicted that the a-vO(2)D at rest was 30% of the total arterial O(2) content (CaO(2)) and that it increased linearly during exercise reaching a value of 80% of CaO(2) at the peak workload (W(max)) of cycle exercise. Then, the SV was calculated by applying the following equation, SV = OP/a-vO(2)D(est), where the OP was assessed as the oxygen uptake/heart rate. Data calculated by our model were compared with those obtained by impedance cardiography. The main result was that the limits of agreement between the SV assessed by impedance cardiography and the SV estimated were between 22.4 and -27.9 ml (+18.8 and -24% in terms of per cent difference between the two SV measures). It was concluded that our model for estimating SV during effort may be reasonably applicable, at least in a healthy population.

On the continuous dual of a polynomial bialgebra

This paper is devoted to the study of the dual bialgebra of the bialgebra B n of polynomials in finitely many variables. The elements of are described in various ways in orcer to obtain some useful formulae (e.g., a formula for the “remainder” modulo a cofinite ideal of B n). The subcoalgebra C f generated by a given element of is studied and its structure constants with respect to different natural bases are given.

Indexes of physical capacity and repeated sprint ability of young soccer players

Repeated sprint ability (RSA) is thought to be an important skill for team sports. However, there is no study that correlates aerobic capacity (AC) and lactic anaerobic capacity (LAC) with RSA in young elite soccer players. Fourteen young players from a professional soccer team underwent two laboratory tests: an incremental exercise test (IET) and an all-out test (AOT) to asses AC and LAC, respectively. Athletes also performed a field RSA test. During both the IET and the AOT tests heart rate, oxygen uptake, carbon dioxide production, and pulmonary ventilation were obtained by a portable gas analyzer. Velocity and fatigue indices were measured during the RSA test. Blood lactate was also measured after the AOT (BLaAOT) and the RSA (BLaRSA) test. No correlation was found between AC and LAC indices and measures of the RSA test, even though the AOT test appeared to fully recruit LAC capacity, as no difference between BLaAOT and BLaRSA was detected. It was concluded that no correlation exists between AC and LAC capacities obtained in the laboratory setting and velocity and fatigue measures from RSA testing. This finding should be taken into account when testing young soccer players.

Some remarks on the inverse systems of polynomial modules

Abstract This paper is devoted to a generalization of the notion of inverse system of a polynomial ideal as can be found in Macaulays treatise on Modular Systems. The definition of inverse system given here relates polynomial modules to modules of linear forms on polynomials. The most interesting results obtained by Macaulay on the inverse systems of polynomial ideals are particular cases of propositions proved in this article.

G-R-sequences and incidence coalgebras of posets of full binomial type☆

Abstract A family of polynomial sequences, named G-R-sequences, is introduced and its connections with both graded coalgebras and posets of full binomial type are studied. Moreover, the G-R-sequences pn(x), such that pn is a divisor of pn + 1, are characterized in terms of roots of unity and linearly recursive sequences.

Polynomial Sequences Associated with a Class of Incidence Coalgebras.

A few special sequences of polynomials associated with both automorphisms and hemimorphisms of a particular class of coalgebras as well as their links with locally finite posets of binomial type are analysed.

Modal Share Change following Implementation of Travel Demand Management Strategies

The demand for urban mobility has seen a marked increase over the last few decades. The expansion of road networks, the increase in distance traveled and in the number of trips made has created car-dependent cities. One solution for achieving the switch from private car to public transport is the introduction of a new public transport line that improves the accessibility and frequency of service. However, an important behavioral process underpins travel choices and often a change in choice context is not sufficient to evoke behavior change. Voluntary travel behavior change (VTBC) programs were developed for heightening individuals’ awareness of the consequences of their travel choices and of the benefits to be reaped from using sustainable alternatives, through information provision and communication strategies. The objective of the present paper is to analyze the effect on travel mode choice of introducing a new light railway line into the choice set (hard measure) when implementing a VTBC program on a large scale, but with a high degree of personalization (soft measure). Although numerous studies have demonstrated the need to implement a (hard) measure that acts on the choice context, in combination with a (soft) measure that acts in a personalized way on demand, as far as the authors are aware, few have put this into practice. The first results have shown that a combination of hard and soft measures is more effective in evoking travel behavior change and personalized travel plans produce better results than generalized soft measures.

Automatic data collection for detecting travel behavior: the IPET platform.

Abstract The purpose of this paper is to analyze a mobile system developed both for collecting daily trips and activities information and for promoting sustainable means of transport. Use of a technological device is a first step towards implementing tools that allow more accurate activity and travel data to be collected compared to traditional methods and communication with individuals for persuading them to choose environmentally friendly modes of transport. Nowadays such systems are essential in transport research for designing Voluntary Travel Behavior Change programs [1]. This work presents the outcome of two pilot tests conducted using the IPET platform (Individual Persuasive Eco-Travel Technology [2]), developed for managing a Personalized campaign to promote sustainable means of transport. The two tests, each conducted on a small appropriate sample, had different goals. The first was to test the App and modify/improve it on the basis of users’ suggestions, before large-scale implementation; the second to assess the efficacy of the platform in terms of data collection and travel behavior change. Test results showed that the platform is easy to use and could be effective, once implemented further, for collecting and analyzing large amounts of data on mobility.

Incidence algebras and coalgebras of decomposition structures

Abstract In this paper a few relationships between a Decomposition Structure and its Incidence Coalgebra and Algebra are studied. In particular, some results about the so-called Isomorphism Problem for Incidence Algebras of Moebius Categories are generalized. Moreover, we determine conditions under which all endomorphisms and derivations of an Incidence Algebra are continuous with respect to the finite topology.