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We analyze here how pre-service teachers explicate their views about the wave-particle duality of photons and what role it plays in their arguments supporting the quantum nature of light. The data for the analysis is provided by 12 written reports about the double-slit experiment with feeble light. The analysis is based on constructing semantic networks corresponding to pre-service teachers' written texts. Contingency-like associative correlation between word-pairs is used to differentiate between word-pairs, where associations of two terms or words is systematic. Such associations indicate connections, which are significant for key term vocabularies in construction of inferences and arguments. Based on that information of the key vocabulary we then construct the structure of pre-service teachers' argument for the nature of the photon and its wave-particle duality, in the form of directed argument graphs (DAGs). The results show that argument structures in four to six out of 12 cases meet the goals set for pre-service teacher education. In these cases, experimental aspects and wave-particle duality play an important role in the pre-service teachers' argument and its structure.

Teaching and learning the language of science is an important part of science education. Learning the vocabulary of science plays a key role in learning the language of science. The meaning of abstract scientific terms builds on their connections with other terms and how they are used. In this research, we study pre-service physics teachers' physics-related vocabularies and investigate how rich a vocabulary they use and what similarities and differences there are in their vocabularies regarding electrons and photons. We investigate the connectedness of physics terms by categorizing them according to their role in explaining quantum physics and carry out a lexical network analysis for N=60 written reports. The analysis shows that vocabularies do not share much similarity and the reports reflect narrow images of photons and electrons. We conclude that science teacher education needs to pay attention to explicit teaching of the language of science for pre-service teachers.

In this article, graduated physics teachers' views about their teacher education program and professional needs are evaluated. With respect to teacher knowledge, Physical Knowledge for Teaching (PKT) framework consisting of six domains related to content knowledge and pedagogical content knowledge was developed based on the framework of Mathematical Knowledge for Teaching. PKT was utilized in the design of a Likert scale instrument that aims to discover teachers' views concerning these six domains from two separate viewpoints: to what extent the domains were covered in their teacher education program concerning the domains, and how important is that theme for their profession. Results revealed that teachers see that the domains related to common content knowledge and structures of physics have been addressed adequately in their teacher education but characteristics of other domains, such as teaching methods, evaluation, and motivating learners, received less favorable evaluations. With respect to the importance of different domains for teacher profession, teachers valued the importance of every domain of teacher knowledge highly. These findings suggest that the greatest deficiencies in this physics teacher education program lie on addressing pedagogical content knowledge with its various sub-domains. Our PKT framework offers a promising base for evaluating physics teacher knowledge. We suggest that a framework for teacher knowledge should be explicitly introduced for pre-service teachers in their education so that they could evaluate their knowledge and professional needs better.

Relational interlinked dependencies between concepts constitute the structure of abstract knowledge and are crucial in learning conceptual knowledge and the meaning of concepts. To explore pre-service teachers' declarative knowledge of physics concepts, we have analyzed concept networks, which agglomerate 12 pre-service teacher students' representations of the key elements in electricity and magnetism. We show that by using network-based methods, the interlinked connections of nodes, locally and globally, can be analyzed to reveal how different elements of the network are supported through their connections to other nodes in the network. Nodes with high global connectivity initialize contiguous concept patchworks within the network and are thus most often found to be abstract, general, and advanced concepts. Locally cohesive concepts, on the other hand, are nearly always auxiliary supporting concepts, related to specific textbook-type experiments and model-type conceptional elements. Comparisons of group-level knowledge and individual pre-service teacher students' knowledge in the form of networks shows that while in group-level the aggregated knowledge is expert-like, at the individual level pre-service teacher students possess only a fraction of that knowledge.

We present a method to analyse how pre-service science teachers relate events, ideas, characters and deeds in history of science and in cultural and general history. A group of 25 students presented their views they deemed to be of importance in history of science, culture, society and politics in era between 1550 and 1850. The sample is based on students' study reports and analysed by using network analysis. We show how students' knowledge of history of science and history in general are organised around certain famous characters, ideas, events and institutions, thus revealing the phenomenon of accumulation of fame; the Matthew effect in action.

The concepts of electricity and magnetism in physics are complex and demanding to learn because their meaning builds through several different phenomenological areas. Each of the phenomenological areas adds a certain facet of the meaning of the concept. All standard physics textbooks discuss at least 1) force, 2) energy and work, and 3) electric charge and current, which are different phenomenological facets of the field and which also are implicitly covered in instruction. It is of interest to ask, how these three facets are actually reflected in university students' declarative (expressed and communicated) knowledge of electric and magnetic field concepts. Here this problem is addressed using recently introduced concept networks as a research tool. Using these concept networks, pre-service physics teachers have represented their views how electric and magnetic field concepts are linked to other concepts and conceptual elements in electricity and magnetism. The results suggest that more extensive is the students' basis of content knowledge the more balanced are the facets, while students with less extensive basis of content knowledge tend to favour forcebased understanding of the electric and magnetic fields. The implications of the findings on teaching and instruction are discussed.

In learning conceptual knowledge in physics, a common problem is the incompleteness of a learning process, where students' personal, often undifferentiated concepts take on more scientific and differentiated form. With regard to such concept learning and differentiation, this study proposes a systemic view in which concepts are considered as complex, dynamically evolving structures. The dynamics of the concept learning and differentiation is driven by the competition of model utility in explaining the evidence. Based on the systemic view, we introduce computational model, which represents the essential features of the conceptual system in the form of directed graph (DGM), where concepts are nodes connected to other conceptual elements (nodes) in the graph. The results of a DGM are then compared to the empirical findings to identify differentiation between concepts of electric current and voltage based on a re-analysis of previously published empirical findings on upped secondary school students' learning paths in the context of DC circuits. The comparison shows that the model predicts and explains many relevant, empirically observed features of the learning paths of concept learning and differentiation, such as: 1) Context-dependent dynamics, 2) the persistence of ontological shift and concept differentiation, and 3) the effects of communication on individual learning paths. The systemic view and the DGM model based on it make these generic features of interest in concept learning and differentiation understandable and show that these features are associated with the guidance of theoretical knowledge. Finally, we discuss briefly the implications of the results on teaching and instruction.

In learning conceptual knowledge in physics, a common problem is the development and differentiation of concepts in the learning process. An important part of this development process is the re-organisation or re-structuring process in which students' conceptual knowledge and concepts change. This study proposes a new view of concept development with explicit attention given to concept development from the level of knowledge-as-pieces to the level of knowledge-as-theory. The proposed new picture is based on the view that concepts are complex constructs essentially embedded in a larger system of knowledge. Three closely connected aspects require our attention: (1) conceptions of concepts, (2) conceptions of knowledge systems, and finally, (3) conceptions of the process of change. The potential advantages of this prospective are demonstrated through the re-analysis of the concept development in the well-known case of electric current and voltage. The results show that in the concept development process, both causal knowledge and coherence of the knowledge system play crucial roles. Finally, the study points out how the theoretical position proposed here directly impacts conceptions of learning and instruction as well as what solutions are sought for problems in learning--or even what is considered a problem or success in learning.

Good conceptual understanding of physics is based on understanding what the key concepts are and how they are related. This kind of understanding is especially important for physics teachers in planning how and in what order to introduce concepts in teaching; connections which tie concepts to each other give direction of progress--there is "flux of information" so that what was learned before provides the basis for learning new ideas. In this study, we discuss how such ordering of concepts can be made visible by using concept maps and how they can be used in analysing the students' views and ideas about the inherent logic of the teaching plans. The approach discussed here is informed by the recent cognitively oriented ideas of knowledge organisation concentrating on simple knowledge organisation patterns and how they form the basis of more complex concept networks. The analysis of such "concept networks" is then very naturally based on the use of network theory on analysing the concept maps. The results show that even in well-connected maps, there can be abrupt changes in the information flux in the way knowledge is passed from the initial levels to the final levels. This suggests that handling the information content is very demanding and perhaps a very difficult skill for a pre-service teacher to master.

A characteristic feature of scientific knowledge is the high degree of coherence and connectedness of its conceptual structure. This notion is also behind the widely accepted instructional method of representing the concepts as networks. We suggest here that notions of explanatory coherence and deductive coherence naturally connect the structure of knowledge to the processes which are important in constructing the concept networks. Of these processes, experimental method and modelling are shown to be closely connected with explanatory and deductive coherence, respectively. From this viewpoint, we compare here how experts and novices represent their physics knowledge in the form of concept networks, and show that significant differences between experts' and novices' quality of knowledge become directly reflected in the structure of the networks. The results also show how concept networks make visible both the structure of knowledge and the methodological procedures, which support its formation.

The model-based view (MBV) of science education, which strives for authenticity in science teaching, is currently seeking support from the philosophical positions related to the Semantic View of Theories (SVT). These recent advances are promising steps towards establishing a robust philosophical framework, but they need revision in so far as they are meant to apply to physics and physics education. It is suggested here that in physics education, attention needs to be guided to the notion of the "empirical reliability of models" and modelling, and to the methodological question of how empirical reliability is established in the process of "making a match between theory and experiment." The suggested picture--intended for the purposes of physics teacher education--replaces the current more limited philosophical frameworks used in science education with one of a wider scope. Moreover, the revised philosophical background gives a more authentic picture of physics as science, and the modelling activity within it, than the other current stances in the science education.

Learning to understand the content and meaning of physics' concepts is one of the main goals of physics education. In achieving this understanding, the creation of quantities through quantitative measurements, or rather through quantifying experiments, is a key process. The present article introduces a didactical reconstruction for understanding the construction of the meaning of physical quantities from a network point of view, where the quantities are part of networks and the quantifying experiments build up these networks. As a practical example, we discuss how the quantity temperature is constructed in an instructional unit designed for student teachers and what the learning outcomes are.

The purpose of the study was to determine the typical teaching methods used in upper secondary physics in Finland and Norway and how students would like to study physics. Moreover, the further aim of seeing how certain background variables may explain students' desire to study their chosen specialist subject, physics or social science (humanities), is discussed. The students' opinions were surveyed using a questionnaire and the data analysed by multivariate methods. The questionnaire was answered by randomly selected 2nd-year upper secondary students. Students say that physics teachers typically present new material or solve problems on the blackboard. This is also what students want. On the other hand, students would like to discuss difficult concepts and problems more, as well as work on problems and tasks in small groups. They would also like the teacher to lead the discussion when topics are discussed in the classroom. The student gender, as well as other predictors (perceived subject easiness, interest and workload, quality of instruction), excluding nationality and specialist subject, explain very little about how students say they like to study their specialist subject. The results were interpreted to mean that students preferred more versatile teaching methods, especially discussion in the classroom led by a teacher, than is presently the case. (Contains 5 tables.)

In physics teaching experimentality is an integral component in giving the starting point of knowledge formation and conceptualization. However, epistemology of experiments is not often addressed directly in the educational and pedagogical literature. This warrants an attempt to produce an acceptable reconstruction of the epistemological role of experiments in physics by drawing insight from history and philosophy of physics. Towards that end, the experiments' role in the 19th-century physics is discussed. We propose here a reconstruction, which is based on the idea that in epistemology of experiments the inductive-like "generative justification of knowledge" is central. A generative view makes it possible to retain those aspects of experiments which make them purposeful for learning and can give a starting point for students' own construction of knowledge. The reconstruction also helps to conceive the experiments with their correct historical role and helps to bring back the generative use of experiments in teaching, which, after all, has never vanished from the practice of physics.

The basis of this paper concerns a one-and-a-half year in-service training program ("In-service Training for Physics Teachers"; 40 ECTS credits) for physics teachers (Grades 7-12, n = 98) designed to enhance both their subject knowledge and pedagogical content knowledge. The role of laboratory experiments in physics education in particular was discussed during lectures, seminars, and through an e-mail list. This discussion centered on the epistemic role of experiments in the teaching of physics. Working in permanent small groups was also central to the training program. Following the active phase of the project, a survey was organized to clarify the teachers' beliefs about the role of experiments. The teachers' descriptions showed that approximately 20% had improved their use of experiments in conjunction with the goals of the "In-service Training for Physics Teachers" program.

Describes a long-term in-service training program for physics teachers grades 7-12 designed to enhance teachers' subject matter and pedagogical content knowledge. Teachers' opinions of the program were examined using a survey. Results suggest that the courses and activities that were most valuable for day-to-day teaching were those in which teachers could cooperate, reflect, and plan with each other in small groups. (Author/MM)

Using the Pan-European TIMES-VTT model, we studied pathways for carbon neutrality by 2050 for 31 European countries by modelling a large portfolio of various terrestrial and technological carbon dioxide removal (CDR) strategies. Negative emission technologies and practices (NETPs) such as af-/reforestation, soil carbon sequestration, bioenergy with carbon capture and storage, direct air capture and storage, biochar, and enhanced weathering were considered. Three different storylines were created to describe the role of NETPs in varying future developments. The scenario storylines illustrate potential opportunities and constraints for large scale NETP implementation focusing on (1) optimistic technology development, (2) strict protection of planetary boundaries, and (3) increased self-sufficiency due to geopolitical risks associated with policy fragmentation. The results show that the demand for NETPs could be on a gigaton scale to reach carbon neutrality in Europe by 2050. As different countries have different opportunities to implement NETPs, none of the NETP options should be excluded from mitigation portfolios at this stage. The results also indicate the potential of NETPs in providing cost-effective solutions for achieving climate targets. On the other hand, stricter greenhouse gas emission reduction policies are needed to avoid over-reliance on CDR.

The accurate determination of reactor antineutrino spectra remains a very hot research topic, where new questions have emerged in recent years. Indeed, after the “reactor anomaly” – a deficit of measured antineutrinos at short baseline reactor experiments with respect to spectral predictions – the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have evidenced spectral distortions in their measurements with respect to the same spectral predictions. This puzzle is called the “shape anomaly”. Recently summation calculations of reactor antineutrino spectra based on the use of nuclear data have obtained the best agreement to date with the reactor neutrino flux measurements at the level of 2% thanks to a decade of Total Absorption Gamma-ray Spectroscopy (TAGS) measurements at the radioactive beam facility of the University of Jyväskylä in two experimental campaigns. A selection of the results obtained so far is presented.

Three observables of interest for present and future reactors depend on the β decay properties of the fission products: antineutrinos from reactors, the reactor decay heat and delayed neutron emission. In these proceedings, we present new results from summation calculations of the first two quantities quoted above, performed with evolved independent yields coupled with fission product decay data, from various nuclear data bases or models. New TAGS results from the latest experiment of the TAGS collaboration at the JYFL facility of Jyväskylä will be displayed as well as their impact on the antineutrino spectra and the decay heat associated to fission pulses of the main actinides.

Measurements and theoretical calculations of meson form factors are essential for our understanding of internal hadron structure and QCD, the dynamics that bind the quarks in hadrons. The pion electromagnetic form factor has been measured at small space-like momentum transfer |q2| < 0.3 GeV2 by pion scattering from atomic electrons and at values up to 2.5 GeV2 by scattering electrons from the pion cloud around a proton. On the other hand, in the limit of very large (or infinite) Q2 = −q2, perturbation theory is applicable. This leaves a gap in the intermediate Q2 where the form factors are not known. As a part of their 12 GeV upgrade Jefferson Lab will measure pion and kaon form factors in this intermediate region, up to Q2 of 6 GeV2. This is then an ideal opportunity for lattice QCD to make an accurate prediction ahead of the experimental results. Lattice QCD provides a from-first-principles approach to calculate form factors, and the challenge here is to control the statistical and systematic uncertainties as errors grow when going to higher Q2 values. Here we report on a calculation that tests the method using an ηs meson, a ’heavy pion’ made of strange quarks, and also present preliminary results for kaon and pion form factors. We use the nf = 2 + 1 + 1 ensembles made by the MILC collaboration and Highly Improved Staggered Quarks, which allows us to obtain high statistics. The HISQ action is also designed to have small dicretisation errors. Using several light quark masses and lattice spacings allows us to control the chiral and continuum extrapolation and keep systematic errors in check.

he quark flavor sector of the Standard Model is a fertile ground to look for new physics effects through a unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix. We present a lattice QCD calculation of the scalar and the vector form factors (over a large q2 region including q2 = 0) associated with the D→ Klv semi-leptonic decay. This calculation will then allow us to determine the central CKM matrix element, Vcs in the Standard Model, by comparing the lattice QCD results for the form factors and the experimental decay rate. This form factor calculation has been performed on the Nf = 2 + 1 + 1 MILC HISQ ensembles with the physical light quark masses.

The accurate determination of reactor antineutrino spectra remains a very active research topic for which new methods of study have emerged in recent years. Indeed, following the long-recognized reactor anomaly (measured antineutrino deficit in short baseline reactor experiments when compared with spectral predictions), the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have recently demonstrated the existence of spectral distortions in their measurements with respect to the same predictions. These spectral predictions were obtained through the conversion of integral beta-energy spectra obtained at the ILL research reactor. Several studies have shown that the underlying nuclear physics required for the conversion of these spectra into antineutrino spectra is not totally understood. An alternative to such converted spectra is a complementary approach that consists of determining the antineutrino spectrum by means of the measurement and processing of nuclear data. The beta properties of some key fission products suffer from the pandemonium effect which can be circumvented by the use of the Total Absorption Gamma-ray Spectroscopy technique (TAGS). The two main contributors to the Pressurized Water Reactor antineutrino spectrum in the region where the spectral distortion has been observed are 92Rb and 142Cs, which have been measured at the radioactive beam facility of the University of Jyväskylä in two TAGS experiments. We present the results of the analysis of the TAGS measurements of the β-decay properties of 92Rb along with preliminary results on 142Cs and report on the measurements already performed.

Total absorption gamma-ray spectroscopy is used to measure accurately the intensity of γ emission from neutron-unbound states populated in the β-decay of delayed-neutron emitters. From the comparison of this intensity with the intensity of neutron emission one can deduce information on the (n,γ) cross section for unstable neutron-rich nuclei of interest in r process abundance calculations. A surprisingly large γ branching was observed for a number of isotopes. The results are compared with Hauser-Feshbach calculations and discussed.

In this work we report on total absorption γ-ray spectroscopy measurements of the β decay of fission products that are important contributors to the antineutrino spectrum. The experiment was performed at IGISOL as a part of a campaign of measurements with the new DTAS spectrometer. Preliminary results of the analysis of the β decay of 100Nb,100mNb and 140Cs are presented.

Preliminary results from beta decay studies of nuclei that are important for reactor applications are presented. The beta decays have been studied using the total absorption technique (TAS) and the pure beams provided by the JYFLTRAP system at the IGISOL facility of the University of Jyväskylä.

The β-delayed neutron emission probability, Pn, of very exotic nuclei is crucial for the understanding of nuclear structure properties of many isotopes and astrophysical processes such as the rapid neutron capture process (r-process). In addition β-delayed neutrons are important in a nuclear power reactor operated in a prompt sub-critical, delayed critical condition, as they contribute to the decay heat inducing fission reactions after a shut down. The study of neutron-rich isotopes and the measurement of β-delayed one-neutron emitters (β1n) is possible thanks to the Rare Isotope Beam (RIB) facilities, where radioactive beams allow the production of exotic nuclei of interest, which can be studied and analyzed using specific detection systems. This contribution reports two recent measurements of β-delayed neutron emitters which allowed the determination of half-lives and the neutron branching ratio of isotopes in the mass region above A = 200 and N > 126, and a second experiment which confirmed 136Sb as the heaviest double neutron emitter (β2n) measured so far.

Residential wood combustion (RWC) emits large amounts of gaseous and particulate organic aerosol (OA). In the atmosphere, the emission is transformed via oxidative reactions, which are under daylight conditions driven mainly by hydroxyl radicals (OH). This continuing oxidative ageing produces secondary OA and may change the health- and climate-related properties of the emission. However, it is not well known how the composition of RWC-originated OA changes as the function of OH exposure. In this work, emissions from two modern residential logwood combustion appliances were photochemically aged in an oxidation flow reactor (OFR) with various OH exposure levels, reaching up to 6×1011 s cm−3 (equivalent to 1 week in the atmosphere). Gaseous organic compounds were analysed by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS), while particulate OA was analysed online by a high-resolution soot particle aerosol mass spectrometer (SP-HR-ToF-AMS) and offline by in situ derivatization thermal desorption–gas chromatography–time-of-flight mass spectrometry (IDTD-GC-ToF-MS). Photochemical reactions increased the mass of particulate organic carbon by a factor of 1.3–3.9. The increase in mass took place during the first atmospheric equivalent day of ageing, after which the enhancement was independent of the extent of photochemical exposure. However, ageing increased the oxidation state of the particulate OA linearly throughout the assessed range, with ΔH:C/ΔO:C slopes between −0.17 and −0.49 in van Krevelen space. Ageing led to an increase in acidic fragmentation products in both phases, as measured by the IDTD-GC-ToF-MS for the particulate and PTR-ToF-MS for the gaseous phase. For the gaseous organic compounds, the formation of small carbonylic compounds combined with the rapid degradation of primary volatile organic compounds such as aromatic compounds led to a continuous increase in both the O : C and H : C ratios. Overall, the share of polycyclic aromatic compounds (PACs) in particles degraded rapidly during ageing, although some oxygen-substituted PACs, most notably naphthaldehydic acid, increased, in particular during relatively short exposures. Similarly, the concentrations of particulate nitrophenols rose extensively during the first atmospheric equivalent day. During continuous photochemical ageing, the dominant transformation mechanisms shifted from the initial gas-phase functionalization/condensation to the transformation of the particulate OA by further oxidation reactions and fragmentation. The observed continuous transformation of OA composition throughout a broad range of OH exposures indicates that the entire atmospheric lifetime of the emission needs to be explored to fully assess the potential climate and health effects of RWC emissions.

Complex networks are often used to analyze written text and reports by rendering texts in the form of a semantic network, forming a lexicon of words or key terms. Many existing methods to construct lexicons are based on counting word co-occurrences, having the advantage of simplicity and ease of applicability. Here, we use a quantum semantics approach to generalize such methods, allowing us to model the entanglement of terms and words. We show how quantum semantics can be applied to reveal disciplinary differences in the use of key terms by analyzing 12 scholarly texts that represent the different positions of various disciplinary schools (of conceptual change research) on the same topic (conceptual change). In addition, attention is paid to how closely the lexicons corresponding to different positions can be brought into agreement by suitable tuning of the entanglement factors. In comparing the lexicons, we invoke complex network-based analysis based on exponential matrix transformation and use information theoretic relative entropy (Jensen–Shannon divergence) as the operationalization of differences between lexicons. The results suggest that quantum semantics is a viable way to model the disciplinary differences of lexicons and how they can be tuned for a better agreement.

Knowledge structures are often represented in the form of networks or maps of concepts. The coherence and connectivity of such knowledge representations is known to be closely related to knowledge production, acquisition and processing. In this study we use network theory in making the clustering and cohesion of concept maps measurable, and show how the distribution of these properties can be interpreted through the Maximum Entropy (MaxEnt) method. This approach allows to introduce new concepts of the “energy of cognitive load” and the “entropy of knowledge organization” to describe the organization of knowledge in the concept maps.

A sub-micron resolution optical coherence tomography device was used together with a pipe rheometer to analyze the rheology and flocculation dynamics of a 0.5% microfibrillated cellulose (MFC) suspension. The bulk behavior of the MFC suspension showed typical shear thinning (power-law) behavior. This was reflected in a monotonously decreasing floc size when the shear stress exceeded the yield stress of the suspension. The quantitative viscous behavior of the MFC suspension changed abruptly at the wall shear stress of 10 Pa, which was reflected in a simultaneous abrupt drop of the floc size. The flocs were strongly elongated with low shear stresses. With the highest shear stresses, the flocs were almost spherical, indicating a good level of fluidization of the suspension.

This study presents an evaluation and modeling exercise of the size fractionated aerosol particle number concentrations measured nearby a major road in Helsinki during 23 August–19 September 2003 and 14 January–11 February 2004. The available information also included electronic traffic counts, on-site meteorological measurements, and urban background particle number size distribution measurement. The ultrafine particle (UFP, diameter

The properties of atmospheric aerosol particles in Marseille and Athens were investigated. The studies were performed in Marseille, France, during July 2002 and in Athens, Greece, during June 2003. The aerosol size distribution and the formation and growth rates of newly formed particles were characterized using Differential Mobility Particle Sizers. Hygroscopic properties were observed using a Hygroscopic Tandem Differential Mobility Analyzer setup. During both campaigns, the observations were performed at suburban, almost rural sites, and the sites can be considered to show general regional background behavior depending on the wind direction. At both sites there were clear pattern for both aerosol number concentration and hygroscopic properties. Nucleation mode number concentration increased during the morning hours indicating new particle formation, which was observed during more than 30% of the days. The observed formation rate was typically more than 1 cm−3 s−1, and the growth rate was between 1.2–9.9 nm h−1. Based on hygroscopicity measurements in Athens, the nucleation mode size increase was due to condensation of both water insoluble and water soluble material. However, during a period of less anthropogenic influence, the growth was to a larger extent due to water insoluble components. When urban pollution was more pronounced, growth due to condensation of water soluble material dominated.

Aerosol chemical composition was measured over the Atlantic Ocean in November–December 1999 and at the Finnish Antarctic research station Aboa in January 2000. The concentrations of all anthropogenic aerosol compounds decreased clearly from north to south. An anthropogenic influence was still evident in the middle of the tropical South Atlantic, background values were reached south of Cape Town. Chemical mass apportionment was calculated for high volume filter samples (Dp80% in the Southern Ocean, and 10% in most samples, also at Aboa. The correlation of biomass-burning-related aerosol components with 210Pb was very high compared with that between nss calcium and 210Pb which suggests that 210Pb is a better tracer for biomass burning than for Saharan dust. The ratio of the two clear tracers for biomass burning, nss potassium and oxalate, was different in European and in African samples, suggesting that this ratio could be used as an indicator of biomass burning type. The concentrations of continent-related particles decreased exponentially with the distance from Africa. The shortest half-value distance, ~100 km, was for nss calcium. The half-value distance of particles that are mainly in the submicron particles was ~700±200 km. The MSA to nss sulfate ratio, R, increased faster than MSA concentration with decreasing anthropogenic influence, indicating that the R increase could largely be explained by the decrease of anthropogenic sulfate.

Diurnal variation of number size distribution (particle size 3-800nm) and modal parameters (geometric standard deviation, geometric mean diameter and modal aerosol particle concentration) in a highly polluted urban environment was investigated during October and November 2002 in New Delhi, India. Continuous monitoring for more than two weeks with the time resolution of 10min was conducted using a Differential Mobility Particle Sizer (twin DMPS). The results indicated clear increase in Aitken mode (25-100nm) particles during traffic peak hours, but towards the evenings there were more Aitken mode particles compared to the mornings. Also high concentrations of accumulation mode particles (>100nm) were detected in the evenings only. In the evenings, biomass/refuse burning and cooking are possible sources beside the traffic. We have also shown that nucleation events are possible in this kind of atmosphere even though as clear nucleation events as observed in rural sites could not be detected. The formation rate of 3nm particles (J3) of the observed events varied from 3.3 to 13.9cm-3s-1 and the growth rate varied from 11.6 to 18.1nmh-1 showing rapid growth and high formation rate, which seems to be typical in urban areas.

The growth properties of nucleation mode particles were investigated. The variation of source rates of condensable vapors in different locations and environmental conditions was analyzed. The measurements were performed in background stations in Antarctica, in Finnish Lapland and Boreal Forest stations (SMEAR I and SMEAR II) as well as in polluted urban sites in Athens, Marseille and New Delhi. Taking advantage of only the measured spectral evolution of aerosol particles as a function of time the formation and growth properties of nucleation mode aerosols were evaluated. The diameter growth-rate and condensation sink were obtained from the measured size distribution dynamics. Using this growth rate and condensation sink, the concentration of condensable vapors and their source rate were estimated. The growth rates and condensation sinks ranged between 0.3-20nmh-1 and 10-4-0.07s-1, respectively. The corresponding source rate of condensable vapors varied more than 4 orders of magnitude from 103 to over 107cm-1s-1. The highest condensation sink and source rate values were observed in New Delhi and the smallest values in Antarctica.