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The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/c in p-Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection.
The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/c in p-Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection.
The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/c in p–Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection.
The human amygdala is thought to play a pivotal role in the processing of emotionally significant sensory information. The major subdivisions of the human amygdala—the laterobasal group (LB), the superficial group (SF), and the centromedial group (CM)—have been anatomically delineated, but the functional response properties of these amygdala subregions in humans are still unclear. We combined functional MRI with cyto-architectonically defined probabilistic maps to analyze the response characteristics of amygdala subregions in subjects presented with auditory stimuli. We found positive auditory stimulation-related signal changes predominantly in probabilistically defined LB, and negative responses predominantly in SF and CM. In the left amygdala, mean response magnitude in the core area of LB with 90–100% assignment probability was significantly larger than in the core areas of SF and CM. These differences were observed for pleasant and unpleasant stimuli. Our findings reveal that the probabilistically defined anatomical subregions of the human amygdala show distinctive fMRI response patterns. The stronger auditory responses in LB as compared with SF and CM may reflect a predominance of auditory inputs to human LB, similar to many animal species in which the majority of sensory, including auditory, afferents project to this subdivision of the amygdala. Our study indicates that the intrinsic functional differentiation of the human amygdala may be probed using fMRI combined with probabilistic anatomical maps.
Aims: Inadequate treatment is one of the factors interfering with a successful social and working life. Among students, it can impair their health and learning progress. In the field of medicine the problem of inadequate treatment seems widespread. This study examines wether inadequate treatment in internships differs between medicine and other academic disciplines.
Method: Using a questionnaire, the frequency, forms and severity of inadequate treatment among students were compared between the disciplines of medicine, civil engineering and teaching.
Results: 69,3% of medical students reported inadequate treatment during their internships, about twice as many as students of other disciplines. The ratios of verbal, non-verbal and organisational inadequate treatment were similar between the different academic disciplines. However, medical students executed tasks without receiving sufficient safety precautions or training significantly more often (sevenfold) than students of other disciplines. In total however, the experienced incidents of inadequate treatment were seen as similarly severe across the different academic fields.
Conclusion: Inadequate treatment of students during internships is a larger problem in medicine than in civil engineering or teaching, particularly concerning the performance of unsafe tasks. With regard to the health of students and patients, inadequate treatment in the medical education should be tackled. Previous studies suggest that this goal can be achieved only through longtime extensive measures on the level of students, lecturers, faculty and teaching hospitals.
Mit der Neuregelung der Studienplatzverteilung von 2005 haben die Universitäten in Deutschland die Möglichkeit, bis zu 60% der Studienplätze nach universitätseigenen Kriterien zu vergeben. Implizit wird vom Gesetzgeber und der öffentlichen Meinung gefordert, nicht-leistungsbezogene Kriterien und Persönlichkeitsmerkmale verstärkt zur Bewerberauswahl einzusetzen (Motivation, Identifikation, Vermeidung von Fehlvorstellungen). Da in Anbetracht der Bewerberzahlen mündliche Auswahlgespräche als ungeeignet erscheinen, wurde vom Fachbereich Medizin der Johann Wolfgang Goethe Universität ein Fragebogen entworfen, um nichtschulische Leistungen zu erfassen. Dieser Fragebogen wurde am Beginn des Wintersemesters 2005/2006 von allen Studienanfängern der JWG-Universität Frankfurt und der Medizinischen Universität Innsbruck ausgefüllt. Entgegen der initialen Erwartungen der Verfasser gaben nur etwa 15% Prozent Medizin-spezifische berufliche Vorerfahrungen an (Rettungsdienst, Ausbildung als Krankenschwester/pfleger oder ähnliches); dagegen wurden von etwa 60% angegeben, mindestens ein Musikinstrument zu spielen oder länger sportlich aktiv gewesen zu sein. Die Zusammenstellung der Selbstangaben zeigt, dass Medizin-relevante Vorkenntnisse nur bei einem kleinen Anteil der Studienbewerber in größerem Umfang vorhanden sind. Aufgrund der großen Streuung in der Art und Dauer der angegebenen Vorleistungen sollte die Erhebung von Parametern zur Beurteilung von soft skills, z.B. durch Online-Fragebogen, als (Vor)Selektionsinstrument nur sehr vorsichtig eingesetzt werden.
Objective: Children with pre-school asthma suffer disproportionally more often from severe asthma exacerbations with emergency visits and hospital admissions compared to school children. Despite this high disease burden, there are only a few reports looking at this particular severe asthma cohort. Similarly, there is little real-life research on the distribution of asthma phenotypes and personalized treatment at discharge in this age group. Patients and Methods: Retrospective analysis of the electronic charts of all children aged 1–5 years with asthma hospitalizations (ICD J45) at the Frankfurt University between 2008 and 2017. An acute severe asthma exacerbation was defined as dyspnea, oxygen demand, and/or systemic steroid therapy. Age, gender, duration of hospitalization, asthma phenotype, treatment, and readmission rate were analyzed. Results: Of 572 patients, 205 met the definition of acute severe asthma. The phenotypic characterization showed 56.1% had allergic asthma, 15.2% eosinophilic asthma and 28.7% non-allergic asthma. Of these patients, 71.7% were discharged with inhaled corticosteroids (ICS) or ICS + long-acting-beta-agonists (LABA), 15.1% with leukotriene antagonists (LTRA) and 7.3% salbutamol on demand. The rate of emergency presentations (emergency department and readmission) within 12 months after discharge was high (n = 42; 20.5%). No phenotype tailored treatment was detectable. Neither the number of eosinophils (>300/μl) nor the treatment at discharge had an effect on emergency visits and readmission rate. Conclusion: Despite protective therapy with ICS, ICS + LABA, or LTRA, the readmission rate was high. Thus, current care and treatment strategies should be reevaluated continuously, in order to better control asthma in pre-school children and prevent hospitalization.
Background: Physical activity is an important part of life, and hence exercise-induced bronchoconstriction (EIB) can reduce the quality of life. A standardized test is needed to diagnose EIB. The American Thoracic Society (ATS) guidelines recommend an exercise challenge in combination with dry air. We investigated the feasibility of a new, ATS guidelines conform exercise challenge in a cold chamber (ECC) to detect EIB. The aim of this study was to investigate the surrogate marker reaction to methacholine, ECC and exercise challenge in ambient temperature for the prediction of a positive reaction and to re-evaluate the reproducibility of the response to an ECC.
Methods: Seventy-eight subjects aged 6 to 40 years with suspected EIB were recruited for the study. The subjects performed one methacholine challenge, two ECCs, and one exercise challenge at an ambient temperature. To define the sensitivity and specificity of the predictor, a receiver-operating characteristic curve was plotted. The repeatability was evaluated using the method described by Bland and Altman (95% Limits of agreement).
Results: The following cut-off values showed the best combination of sensitivity and specificity: the provocation dose causing a 20% decrease in the forced expiratory volume in 1 s (PD20FEV1) of methacholine: 1.36 mg (AUC 0.69, p < 0.05), the maximal decrease in FEV1 during the ECC: 8.5% (AUC 0.78, p < 0.001) and exercise challenges at ambient temperatures: FEV1 5.2% (AUC 0.64, p = 0.13). The median decline in FEV1 was 14.5% (0.0–64.2) during the first ECC and 10.7% (0.0–52.5) during the second ECC. In the comparison of both ECCs, the Spearman rank correlation of the FEV1 decrease was r = 0.58 (p < 0.001). The 95% limits of agreement (95% LOAs) for the FEV1 decrease were − 17.7 to 26.4%.
Conclusions: The surrogate markers PD20FEV1 of methacholine and maximal decrease in FEV1 during ECC can predict a positive reaction in another ECC, whereas the maximal FEV1 decrease in an exercise challenge at an ambient temperature was not predictive. Compared with previous studies, we can achieve a similar reproducibility with an ECC.
Clinical trial registration: NCT02026492 (retrospectively registered 03/Jan/2014).
Background: Many patients suffering from exercise-induced asthma (EIA) have normal lung function at rest and show symptoms and a decline in FEV1 when they do sports or during exercise-challenge. It has been described that long-chain polyunsaturated fatty acids (LCPUFA) could exert a protective effect on EIA.
Methods: In this study the protective effect of supplementation with a special combination of n-3 and n-6 LCPUFA (sc-LCPUFA) (total 1.19 g/ day) were investigated in an EIA cold air provocation model. Primary outcome measure: Decrease in FEV1 after exercise challenge and secondary outcome measure: anti-inflammatory effects monitored by exhaled NO (eNO) before and after sc-LCPUFA supplementation versus placebo.
Results: Ninety-nine patients with exercise-induced symptoms aged 10 to 45 were screened by a standardized exercise challenge in a cold air chamber at 4 °C. Seventy-three patients fulfilled the inclusion criteria of a FEV1 decrease > 15% and were treated double-blind placebo-controlled for 4 weeks either with sc-LCPUFA or placebo. Thirty-two patients in each group completed the study. Mean FEV1 decrease after cold air exercise challenge and eNO were unchanged after 4 weeks sc-LCPUFA supplementation.
Conclusion: Supplementation with sc-LCPUFA at a dose of 1.19 g/d did not have any broncho-protective and anti-inflammatory effects on EIA.
Trial registration: Clinical trial registration number: NCT02410096. Registered 7 February 2015 at Clinicaltrial.gov
Gute naturwissenschaftliche Vorkenntnisse sind insbesondere für den vorklinischen Studienabschnitt wichtig. Wegen der heterogenen Auswahl von Leistungskursen und Abituranforderungen kann jedoch nicht unbedingt von einem einheitlichen Wissensstand ausgegangen werden. Daher wurde versucht, mit einem Testbogen aus insgesamt 40 Aufgaben zur Biologie, Chemie, Mathematik und Physik den Wissensstand der Studienanfänger in Humanmedizin in Deutschland zu quantifizieren. Der Fragebogen enthielt neben Faktenaufgaben auch Anwendungen vor allem mathematischer und chemischer Prinzipien. Alle Fragen mussten durch Freitextantworten oder Skizzen beantwortet werden. Teilgenommen haben insgesamt 2 935 Studienanfänger des Wintersemesters 2004/2005 von 14 deutschen Universitäten (etwa 40% des Jahrganges). Im Mittel wurden 14,34 der 40 Aufgaben richtig beantwortet; etwas bessere Kenntnisse wurden in den 15 Biologiefragen (6,89) und den 8 Mathematikfragen erreicht (3,23), während vor allem in Chemie (2,18 von 10 Fragen) und Physik (1,55 von 8 Fragen) große Wissenslücken bestehen. Die Ergebnisse bestätigen, dass die naturwissenschaftlichen Vorkenntnisse der Studienanfänger schlecht sind; sie erfordern einen größeren Zeitaufwand für die Vermittlung des Abiturwissens im ersten vorklinischen Semester. Sinnvoll erscheint alternativ die verpflichtende Teilnahme an Zusatzkursen in diesen Fächern vor Aufnahme des eigentlichen Fachstudiums.
Bipolar disorder (BD) is a highly heritable neuropsychiatric disease characterized by recurrent episodes of mania and depression. BD shows substantial clinical and genetic overlap with other psychiatric disorders, in particular schizophrenia (SCZ). The genes underlying this etiological overlap remain largely unknown. A recent SCZ genome wide association study (GWAS) by the Psychiatric Genomics Consortium identified 128 independent genome-wide significant single nucleotide polymorphisms (SNPs). The present study investigated whether these SCZ-associated SNPs also contribute to BD development through the performance of association testing in a large BD GWAS dataset (9747 patients, 14278 controls). After re-imputation and correction for sample overlap, 22 of 107 investigated SCZ SNPs showed nominal association with BD. The number of shared SCZ-BD SNPs was significantly higher than expected (p = 1.46x10-8). This provides further evidence that SCZ-associated loci contribute to the development of BD. Two SNPs remained significant after Bonferroni correction. The most strongly associated SNP was located near TRANK1, which is a reported genome-wide significant risk gene for BD. Pathway analyses for all shared SCZ-BD SNPs revealed 25 nominally enriched gene-sets, which showed partial overlap in terms of the underlying genes. The enriched gene-sets included calcium- and glutamate signaling, neuropathic pain signaling in dorsal horn neurons, and calmodulin binding. The present data provide further insights into shared risk loci and disease-associated pathways for BD and SCZ. This may suggest new research directions for the treatment and prevention of these two major psychiatric disorders.
Als Konsequenz der Änderung des Hochschulrahmengesetzes können deutsche Hochschulen einen Großteil Ihrer zur Verfügung stehenden Studienplätze in den Numerus-Clausus Fächern nach eigenen Kriterien vergeben. Die Identifizierung von Merkmalen, die im Zusammenhang mit dem Studienerfolg stehen, stellt daher ein aktuelles Forschungsthema dar. Ein längsschnittlich angelegtes Forschungsprojekt der Universität Frankfurt am Main soll prüfen, inwieweit kognitive und nicht-kognitive Merkmale wie gewichtete Einzelfachnoten, das Ergebnis eines fachbezogenen Kenntnistests oder bildungsbiographische Daten neben der Abiturdurchschnittsnote einen bedeutsamen Beitrag zur Prognose des Studienerfolges in den Anfangssemestern des Studiengangs Medizin leisten können. Im Wintersemester 05/06 wurde Studierenden des ersten Fachsemesters ein Test zur Erfassung naturwissenschaftlicher Vorkenntnisse (Nawik) der Bereiche Mathematik, Physik, Chemie und Biologie vorgelegt sowie die Abiturdurchschnittsnote erhoben. Als Indikator für den Studienerfolg im ersten Fachsemester wurde die Punktzahl in der Anatomieklausur heran gezogen. Die ersten Ergebnisse einer Stichprobe von N=140 Studierenden lassen substanzielle Korrelationen der Leistungen im Nawik sowie der Abiturdurchschnittsnote mit der Klausurleistung erkennen (r= 0,45, p< 0,01 bzw. r= -0,24, p<0,01). Eine schrittweise Regression weist insbesondere die Leistung im Test naturwissenschaftlicher Vorkenntnisse als vorhersagestarken Prädiktor aus. Die vorläufigen Ergebnisse werden anhand einer größeren Stichprobe geprüft. Weitere Auswertungen zur Bedeutsamkeit von Einzelfachnoten und bildungsbiographischen Daten (wie das Ausmaß an Vorerfahrung in medizinischen Bereichen) für den Studienerfolg laufen derzeit.
Background: Chronic particulate matter (PM) exposure is correlated to various health effects, even at low amounts. WHO has defined PM concentration limits as daily and annual mean values which were made legally binding in the European Union. While many studies have focused on PM concentrations in special environments, little is known about the average PM- exposure for both employees and passengers in the German public transportation system.
Methods: Particulate matter (PM10, PM2.5, PM1) - concentrations were monitored for 30 minutes at 15 different areas in Frankfurt am Main with major public traffic. Maximum and mean concentrations and, as a surrogate for the inhaled dosage, the Area Under the Curve (AUC) for 15 minutes of exposure were calculated.
Results: The WHO limits for PM10 and PM2.5 were exceeded at nearly all times and areas. Highest maximum concentrations were found at underground stations, subterranean railway stations and subterranean shopping arcades with much lower values obtained at surface points. In one measurement at a surface test point smokers who neglected the non-smoking policy could be identified as a major cause for a at least temporary strong increase of PM-load as seen in high maximum values and normal averages.
Conclusions: Subterranean areas have high particulate matter contamination exceeding WHO limits. Improvement may be achieved by increased ventilation. Subterranean shops and kiosks, being workplaces with long term exposure, should be equipped with external air supply. The non- smoking policy of the "Deutsche Bahn" for public spaces should be enforced.
Das Medizinstudium und die spätere Berufstätigkeit werden als stressig angesehen; dennoch liegen nur wenige Daten zur Stressbelastung von Medizinstudenten und Ärzten vor. Als Teil einer umfangreichen Erhebung zur Stressbelastung haben wir die Stressbelastung und Resilienz von Frankfurter Medizinstudenten in den ersten Wochen des 1. vorklinischen Semesters erhoben (Trierer Inventar zum chronischen Stress TICS, Resilienz-Skala RS11); an der Studie nahmen 348 von 383 Studienanfängern (90,8%) teil. Übereinstimmend mit Ergebnissen aus dem 5. Semester zeigen die Studenten des 1. Semesters hohe Werte insbesondere in den Teilskalen Überlastung und Überforderung; auffallend sind ebenfalls hohe Werte in den Skalen Soziale Isolation und Summenscore. Ein T-Score (altersnormierter Normalwert = 50) über der 2fachen Vertrauensgrenze findet sich im Summenscore (17,2%), chronische Besorgnis (17,8%), Überforderung (11,2%) und Überlastung (22,7%), während in anderen Skalen entsprechende Werte nur bei 1–5% der Teilnehmer erreicht wurden. Die Skalen Überlastung, Erfolgsdruck, chronische Besorgnis sowie der Summenscore sind weitgehend normalverteilt (Schiefe <0,2), dieser Wert beträgt für die anderen Skalen 0,45–0,65. Zwischen den Unterskalen finden sich Korrelationskoeffizienten >0,5 für Überlastung und Überforderung sowie chronischer Besorgnis, zwischen Überforderung und mangelnder sozialer Anerkennung, sozialer Isolierung und chronischer Besorgnis sowie zwischen sozialen Spannungen, sozialer Isolierung und chronischer Besorgnis. Parallel wurde die Resilienz mit Hilfe des Fragebogens RS11 erhoben (kein Optimum, hohe Werte weisen auf Resilienz hin). Bei einer Maximalpunktzahl von 77 erreichten die Studenten 62,2 +/– 8,8 Punkte, bei einer ausgeprägten rechtsschiefen Verteilung. Zwischen der Stressbelastung und der Resilienz fand sich keine relevante Korrelation, mit einem Maximalwert von –0,267 zwischen dem RS11-Score und der Subskala Überforderung. Die Daten belegen ein bereits zu Studienbeginn vorliegendes hohes Maß an Überlastung und Überforderung; dieser Stress korreliert nicht mit der Fähigkeit, mit Stress adäquat umzugehen (Resilienz).
Bipolar disorder (BD) is a genetically complex mental illness characterized by severe oscillations of mood and behavior. Genome-wide association studies (GWAS) have identified several risk loci that together account for a small portion of the heritability. To identify additional risk loci, we performed a two-stage meta-analysis of >9 million genetic variants in 9,784 bipolar disorder patients and 30,471 controls, the largest GWAS of BD to date. In this study, to increase power we used ~2,000 lithium-treated cases with a long-term diagnosis of BD from the Consortium on Lithium Genetics, excess controls, and analytic methods optimized for markers on the Xchromosome. In addition to four known loci, results revealed genome-wide significant associations at two novel loci: an intergenic region on 9p21.3 (rs12553324, p = 5.87×10-9; odds ratio = 1.12) and markers within ERBB2 (rs2517959, p = 4.53×10-9; odds ratio = 1.13). No significant X-chromosome associations were detected and X-linked markers explained very little BD heritability. The results add to a growing list of common autosomal variants involved in BD and illustrate the power of comparing well-characterized cases to an excess of controls in GWAS.
Cannabinoid drugs are registered for postoperative nausea and emesis, Tourette syndrome and tumor-related anorexia, but are also used for spasticity and pain relief, among other conditions. Clinical studies for spasmolysis have been equivocal and even conclusions from meta-analyses were not consistent. This may be due to uncertainty in diagnostic criteria as well as a lack of direct spasmolytic activity (direct causality). In this review we used the Hill criteria to investigate whether a temporal association is causal or spurious. Methods: A systematic literature search was performed to identify all clinical trials of cannabinoids for spasticity. Studies were evaluated for dose dependency and time association; all studies together were analyzed for reproducibility, coherence, analogy and mechanistic consistency. A Funnel plot was done for all studies to identify selection or publication bias. Results: Twenty-seven studies were included in this meta-analysis. The spasmolytic activity (effect strength) was weak, with a nonsignificant small effect in most studies and a large effect only in a few studies (“enriched” studies, low patient numbers). No dose dependency was seen and plotting effect size vs. daily dose resulted in a slope of 0.004. Most studies titrated the cannabinoid to the optimum dose, e.g., 20 mg/d THC. The effect decreased with longer treatment duration (3–4 months). The spasmolytic effect is consistent for different European countries but not always within a country, nor is the effect specific for an etiology (multiple sclerosis, spinal cord injury, others). For other criteria like plausibility, coherence or analogous effects, no data exist to support or refute them. In most studies, adverse effects were frequently reported indicating a therapeutic effect only at high doses with relevant side effects. Conclusions: Current data do not support a specific spasmolytic effect; a general decrease in CNS activity analogous to benzodiazepines appears more likely. Whether individual patients or specific subgroups benefit from cannabinoids is unclear. Further studies should compare cannabinoids with other, nonspecific spasmolytic drugs like benzodiazepines.
Intrahepatic cholangiocarcinoma (iCCA) is the most frequent subtype of cholangiocarcinoma (CCA), and the incidence has globally increased in recent years. In contrast to surgically treated iCCA, data on the impact of fibrosis on survival in patients undergoing palliative chemotherapy are missing. We retrospectively analyzed the cases of 70 patients diagnosed with iCCA between 2007 and 2020 in our tertiary hospital. Histopathological assessment of fibrosis was performed by an expert hepatobiliary pathologist. Additionally, the fibrosis-4 score (FIB-4) was calculated as a non-invasive surrogate marker for liver fibrosis. For overall survival (OS) and progression-free survival (PFS), Kaplan–Meier curves and Cox-regression analyses were performed. Subgroup analyses revealed a median OS of 21 months (95% CI = 16.7–25.2 months) and 16 months (95% CI = 7.6–24.4 months) for low and high fibrosis, respectively (p = 0.152). In non-cirrhotic patients, the median OS was 21.8 months (95% CI = 17.1–26.4 months), compared with 9.5 months (95% CI = 4.6–14.3 months) in cirrhotic patients (p = 0.007). In conclusion, patients with iCCA and cirrhosis receiving palliative chemotherapy have decreased OS rates, while fibrosis has no significant impact on OS or PFS. These patients should not be prevented from state-of-the-art first-line chemotherapy.
Die Erfassung von subjektiven Theorien von bildungsfernen Personen gestaltet sich schwierig, wenn die Personen nicht in der Lage sind, ihre Theorien formal zu abstrahieren. In dieser Publikation wird ein Verfahren beschrieben, mit welchen Schritten dennoch subjektive Theorien zur aufgestellten Forschungsfrage extrahiert werden können. Das Verfahren basiert auf einer systematischen Auswertung von transkribierten Interviews.
Introduction: Potential health damage by environmental emission of tobacco smoke (environmental tobacco smoke, ETS) has been demonstrated convincingly in numerous studies. People, especially children, are still exposed to ETS in the small space of private cars. Although major amounts of toxic compounds from ETS are likely transported into the distal lung via particulate matter (PM), few studies have quantified the amount of PM in ETS. Study aim The aim of this study was to determine the ETS-dependent concentration of PM from both a 3R4F reference cigarette (RC) as well as a Marlboro Red brand cigarette (MRC) in a small enclosed space under different conditions of ventilation to model car exposure.
Method: In order to create ETS reproducibly, an emitter (ETSE) was constructed and mounted on to an outdoor telephone booth with an inner volume of 1.75 m3. Cigarettes were smoked under open- and closed-door condition to imitate different ventilation scenarios. PM2.5 concentration was quantified by a laser aerosol spectrometer (Grimm; Model 1.109), and data were adjusted for baseline values. Simultaneously indoor and outdoor climate parameters were recorded. The time of smoking was divided into the ETS generation phase (subset "emission") and a declining phase of PM concentration (subset "elimination"); measurement was terminated after 10 min. For all three time periods the average concentration of PM2.5 (Cmean-PM2.5) and the area under the PM2.5 concentration curve (AUC-PM2.5) was calculated. The maximum concentration (Cmax-PM2.5) was taken from the total interval.
Results: For both cigarette types open-door ventilation reduced the AUC-PM2.5 (RC: from 59 400 +/- 14 600 to 5 550 +/- 3 900 mug*sec/m3; MRC: from 86 500 +/- 32 000 to 7 300 +/- 2 400 mug*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 600 +/- 150 to 56 +/- 40 mug/m3, MRC from 870 +/- 320 to 75 +/- 25 mug/m3; p < 0.001) by about 90%. Cmax-PM2.5 was reduced by about 80% (RC: from 1 050 +/- 230 to 185 +/- 125 mug/m3; MRC: from 1 560 +/-500 mug/m3 to 250 +/- 85 mug/m3; p < 0.001). In the subset "emission" we identified a 78% decrease in AUC-PM2.5 (RC: from 18 600 +/- 4 600 to 4 000 +/- 2 600 mug*sec/m3; MRC: from 26 600 +/- 7 200 to 5 800 +/- 1 700 mug*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 430 +/- 108 to 93 +/- 60 mug/m3; MRC: from 620 +/- 170 to 134 +/- 40 mug/m3; p < 0.001). In the subset "elimination" we found a reduction of about 96-98% for AUC-PM2.5 (RC: from 40 800 +/- 11 100 to 1 500 +/- 1 700 mug*sec/m3; MRC: from 58 500 +/- 25 200 to 1 400 +/- 800 mug*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 730 +/- 200 to 27 +/- 29 mug/m3; MRC: from 1 000 +/- 450 to 26 +/- 15 mug/m3; p < 0.001). Throughout the total interval Cmax-PM2.5 of MRC was about 50% higher (1 550 +/- 500 mug/m3) compared to RC (1 050 +/- 230 mug/m3; p < 0.05). For the subset "emission" - but not for the other periods - AUC-PM2.5 for MRC was 43% higher (MRC: 26 600 +/- 7 200 mug*sec/m3; RC: 18 600 +/- 4 600 mug*sec/m3; p < 0.05) and 44% higher for Cmean-PM2.5 (MRC: 620 +/- 170 mug/m3; RC: 430 +/- 108 mug/m3; p < 0.05).
Conclusion: This method allows reliable quantification of PM2.5-ETS exposure under various conditions, and may be useful for ETS risk assessment in realistic exposure situations. The findings demonstrate that open-door condition does not completely remove ETS from a defined indoor space of 1.75 m3. Because there is no safe level of ETS exposure ventilation is not adequate enough to prevent ETS exposure in confined spaces, e.g. private cars. Additionally, differences in the characteristics of cigarettes affect the amount of ETS particle emission and need to be clarified by ongoing investigations.