The structure of a minimal nn-chart with two crossings II: Neighbourhoods of Γ1∪Γn−1\Gamma_1\cup\Gamma_{n-1}

Given a 2-crossing minimal chart $\Gamma$, a minimal chart with two crossings, set $\alpha=\min\{~i~|~$there exists an edge of label $i$ containing a white vertex$\}$, and $\beta=\max\{~i~|~$there exists an edge of label $i$ containing a white vertex$\}$. In this paper we study the structure of a neighbourhood of $\Gamma_\alpha\cup\Gamma_\beta$, and propose a normal form for 2-crossing minimal $n$-charts, here $\Gamma_\alpha$ and $\Gamma_\beta$ mean the union of all the edges of label $\alpha$ and $\beta$ respectively.Comment: 57 pages, 36 figure

Aerosol-ozone correlations during dust transport episodes

Its location in the Mediterranean region and its physical characteristics render Mt. Cimone (44&deg;11&prime; N, 10&deg;42&prime; E), the highest peak of the Italian northern Apennines (2165 m asl), particularly suitable to study the transport of air masses from the north African desert area to Europe. During these northward transports 12 dust events were registered in measurements of the aerosol concentration at the station during the period June&ndash;December 2000, allowing the study of the impact of mineral dust transports on free tropospheric ozone concentrations, which were also measured at Mt. Cimone. Three-dimensional backward trajectories were used to determine the air mass origin, while TOMS Aerosol Index data for the Mt. Cimone area were used to confirm the presence of absorbing aerosol over the measurement site. <P style='line-height: 20px;'> A trajectory statistical analysis allowed identifying the main source areas of ozone and aerosols. The analysis of these back trajectories showed that central Europe and north and central Italy are the major pollution source areas for ozone and fine aerosol, whereas the north African desert regions were the most important source areas for coarse aerosol and low ozone concentrations. During dust events, the Mt. Cimone mean volume concentration for coarse particles was 6.18 &micro;m³/cm³ compared to 0.63 &micro;m³/cm³ in dust-free conditions, while the ozone concentrations were 4% to 21% lower than the monthly mean background values. Our observations show that surface ozone concentrations were lower than the background values in air masses coming from north Africa, and when these air masses were also rich in coarse particles, the lowest ozone values were registered. Moreover, preliminary results on the possible impact of the dust events on PM₁₀ and ozone values measured in Italian urban and rural areas showed that during the greater number of the considered dust events, significant PM₁₀ increases and ozone decreases have occurred in the Po valley

Higher health effects of ambient particles during the warm season: Therole of infiltration factors

A large number of studies have shown much higher health effects of particulate matter (PM) during the warm compared to the cold season. In this paper we present the results of an experimental study carried out in an unoccupied test apartment with the aim of understanding the reasons behind the seasonal variations of the health effects due to ambient PM2.5 exposure. Measurements included indoor and outdoor PM2.5 mass and chemical composition as well as particle size distribution of ultrafine particles. Monitoring campaigns were carried out during summer and winter following a ventilation protocol developed to replicate typical occupant behaviour according to a questionnaire-based survey. Our findings showed that seasonal variation of the relationship between ambient and indoor mass concentrations cannot entirely explain the apparent difference in PM toxicity between seasons and size distribution and chemical composition of particles were identified as other possible causes of changes in the apparent PM toxicity. A marked decrease of ultrafine particles (<100\u202fnm) passing from outdoors to indoors was observed during winter; this resulted in higher indoor exposure to nanoparticles (<50\u202fnm) during summer. With regards to the chemical composition, a pooled analysis showed infiltration factors of chemical species similar to that obtained for PM2.5 mass with values increasing from 0.73 during winter to 0.90 during summer and few deviations from the pooled estimates. In particular, significantly lower infiltration factors and sink effect were found for nitrates and ammonium during winter. In addition, a marked increase in the contribution of indoor and outdoor sulfates to the total mass was observed during summer

Pattern and determinants of hospitalization during heat waves: an ecologic study

<p>Abstract</p> <p>Background</p> <p>Numerous studies have investigated mortality during a heatwave, while few have quantified heat associated morbidity. Our aim was to investigate the relationship between hospital admissions and intensity, duration and timing of heatwave across the summer months.</p> <p>Methods</p> <p>The study area (Veneto Region, Italy) holds 4577408 inhabitants (on January 1^st, 2003), and is subdivided in seven provinces with 60 hospitals and about 20000 beds for acute care. Five consecutive heatwaves (three or more consecutive days with Humidex above 40°C) occurred during summer 2002 and 2003 in the region. From the regional computerized archive of hospital discharge records, we extracted the daily count of hospital admissions for people aged ≥75, from June 1 through August 31 in 2002 and 2003. Among people aged over 74 years, daily hospital admissions for disorders of fluid and electrolyte balance, acute renal failure, and heat stroke (grouped in a single nosologic entity, heat diseases, HD), respiratory diseases (RD), circulatory diseases (CD), and a reference category chosen a priori (fractures of the femur, FF) were independently analyzed by Generalized Estimating Equations.</p> <p>Results</p> <p>Heatwave duration, not intensity, increased the risk of hospital admissions for HD and RD by, respectively, 16% (p < .0001) and 5% (p < .0001) with each additional day of heatwave duration. At least four consecutive hot humid days were required to observe a major increase in hospital admissions, the excesses being more than twofold for HD (p < .0001) and about 50% for RD (p < .0001). Hospital admissions for HD peaked equally at the first heatwave (early June) and last heatwave (August) in 2004 as did RD. No correlation was found for FF or CD admissions.</p> <p>Conclusion</p> <p>The first four days of an heatwave had only minor effects, thus supporting heat health systems where alerts are based on duration of hot humid days. Although the finding is based on a single late summer heatwave, adaptations to extreme temperature in late summer seem to be unlikely.</p

Airborne dust and high temperatures are risk factors for invasive bacterial disease

Background The Sahel region of West Africa has the highest bacterial meningitis attack and case fatality rate in the world. The effect of climatic factors on patterns of invasive respiratory bacterial disease is not well documented. Objective We aimed to assess the link between climatic factors and occurrence of invasive respiratory bacterial disease in a Sahel region of Niger. Methods We conducted daily disease surveillance and climatic monitoring over an 8-year period between January 1, 2003, and December 31, 2010, in Niamey, Niger, to determine risk factors for bacterial meningitis and invasive bacterial disease. We investigated the mechanistic effects of these factors on Streptococcus pneumoniae infection in mice. Results High temperatures and low visibility (resulting from high concentrations of airborne dust) were identified as significant risk factors for bacterial meningitis. Dust inhalation or exposure to high temperatures promoted progression of stable asymptomatic pneumococcal nasopharyngeal carriage to pneumonia and invasive disease. Dust exposure significantly reduced phagocyte-mediated bacterial killing, and exposure to high temperatures increased release of the key pneumococcal toxin pneumolysin through increased bacterial autolysis. Conclusion Our findings show that climatic factors can have a substantial influence on infectious disease patterns, altering density of pneumococcal nasopharyngeal carriage, reducing phagocytic killing, and resulting in increased inflammation and tissue damage and consequent invasiveness. Climatic surveillance should be used to forecast invasive bacterial disease epidemics, and simple control measures to reduce particulate inhalation might reduce the incidence of invasive bacterial disease in regions of the world exposed to high temperatures and increased airborne dust

Inquinamento atmosferico e ricoveri ospedalieri urgenti in 25 citt? italiane: risultati del progetto EpiAir2 Air pollution and urgent hospital admissions in 25 Italian cities: results from the EpiAir2 project

OBJECTIVE: to evaluate the relationship between air pollution and hospital admissions in 25 Italian cities that took part in the EpiAir (Epidemiological surveillance of air pollution effects among Italian cities) project. DESIGN: study of time series with case-crossover methodology, with adjustment for meteorological and time-dependent variables. The association air pollution hospitalisation was analyzed in each of the 25 cities involved in the study; the overall estimates of effect were obtained subsequently by means of a meta-analysis. The pollutants considered were PM10, PM2.5 (in 13 cities only), NO2 and ozone (O3); this last pollutant restricted to the summer season (April-September). SETTING AND PARTICIPANTS: the study has analyzed 2,246,448 urgent hospital admissions for non-accidental diseases in 25 Italian cities during the period 2006- 2010; 10 out of 25 cities took part also in the first phase of the project (2001-2005). MAIN OUTCOME MEASURES: urgent hospital admissions for cardiac, cerebrovascular and respiratory diseases, for all age groups, were considered. The respiratory hospital admissions were analysed also for the 0-14-year subgroup. Percentage increases risk of hospitalization associated with increments of 10 &#956;g/m3 and interquartile range (IQR) of the concentration of each pollutant were calculated. RESULTS: reported results were related to an increment of 10 &#956;g/m3 of air pollutant. The percent increase for PM10 for cardiac causes was 0.34% at lag 0 (95%CI 0.04-0.63), for respiratory causes 0.75%at lag 0-5 (95%CI 0.25-1.25). For PM2.5, the percent increase for respiratory causes was 1.23% at lag 0- 5 (95%CI 0.58-1.88). For NO2, the percent increase for cardiac causes was 0.57%at lag 0 (95%CI 0.13-1.02); 1.29% at lag 0-5 (95%CI 0.52-2.06) for respiratory causes. Ozone (O3) did not turned out to be positively associated neither with cardiac nor with respiratory causes as noted in the previous period (2001-2005). CONCLUSION: the results of the study confirm an association between PM10, PM2.5, and NO2 on hospital admissions among 25 Italian cities. No positive associations for ozone was noted in this period.OBIETTIVO: valutare la relazione tra inquinamento atmosferico e ricoveri ospedalieri nelle citt? italiane partecipanti alla seconda fase del progetto EpiAir (Sorveglianza epidemiologica dell\u27inquinamento atmosferico: valutazione dei rischi e degli impatti nelle citt? italiane). DISEGNO: studio di serie temporali con metodologia case-crossover, con aggiustamento per i fattori temporali e meteorologici rilevanti. L\u27associazione inquinamento atmosferico- ospedalizzazioni ? stata analizzata in ciascuna delle 25 citt? in studio, le stime complessive di effetto sono state ottenute successivamente mediante una metanalisi. Gli inquinanti considerati sono stati il particolato (PM10), il biossido di azoto (NO2) e l\u27ozono (O3), quest\u27ultimo limitatamente al semestre estivo (da aprile a settembre). In 13 citt? in cui i dati erano disponibili ? stata analizzata anche la frazione fine del particolato (PM2.5). SETTING E PARTECIPANTI: lo studio ha esaminato 2.246.448 ricoveri ospedalieri urgenti per cause naturali di pazienti residenti e ricoverati, nel periodo 2006-2010, in 25 citt? italiane, di cui 10 gi? partecipanti alla prima fase del progetto EpiAir (2001-2005). PRINCIPALIMISURE DI OUTCOME: sono stati considerati i ricoveri ospedalieri urgenti per malattie cardiache, cerebrovascolari e respiratorie per tutte le fasce di et?. I ricoveri per cause respiratorie sono stati analizzati separatamente anche per la fascia di et? 0-14 anni. L\u27esposizione ? stata valutata per incremento sia di 10 &#956;g/m3 sia pari all\u27intervallo interquartile (IQR) della concentrazione di ciascun inquinante. RISULTATI: considerando un incremento di 10 &#956;g/m3 per inquinante, per il PM10 ? stato osservato un incremento percentuale di rischio per patologie cardiache dello 0,34%a lag 0 (IC95% 0,04-0,63), e per patologie respiratorie dello 0,75% a lag 0-5 (IC95% 0,25-1,25). Per il PM2.5 l\u27incremento percentuale di rischio per patologie respiratorie ? risultato dell\u271,23%a lag 0-5 (IC95%0,58-1,88). Per l\u27NO2 la stima di effetto per patologie cardiache ? risultata dello 0,57% a lag 0 (IC95% 0,13-1,02), e per patologie respiratorie dell\u271,29% a lag 0-5 (IC95% 0,52-2,06). L\u27ozono non ? risultato positivamente associato n? alle patologie cardiache n? a quelle respiratorie (a differenza del periodo 2001-2005). CONCLUSIONE: i risultati dello studio confermano l\u27effetto a breve termine dell\u27inquinamento atmosferico da PM10, PM2.5 e NO2 sulla morbosit?, in particolare respiratoria, nelle citt? italiane. Non sono state rilevate associazioni positive per l\u27O3