The northernmost Cycladic island? Insularity and the case of prehistoric southern Euboea (the Karystia)

Το παρόν άρθρο χρησιμοποιώντας ως μελέτη περίπτωσης την περιοχή της Νότιας Εύβοιας (γνωστή και ως Καρυστία) διερευνά εν συντομία τις έννοιες των κοινωνικά ορισμένων ορίων, την κατασκευή κοινωνικό-πολιτικών οντοτήτων, και τον καθορισμό συλλογικών και ατομικών ταυτοτήτων στο Προϊ- στορικό Αιγαίο. Αναμφίβολα, οι εγγενείς περιορισμοί που διέπουν το αρχαιολογικό αρχείο, καθιστούν συχνά δύσκολη την μελέτη αυτών των αντικειμένων. Ωστόσο, η προσπάθεια διερεύνησης αυτών των όψεων της κοινωνικής ζωής, όχι μόνο δεν ειναι αδύνατη, αλλά θα μπορούσε να είναι και εξαιρετι- κά εποικοδομητική, λόγω της βαρύνουσας επιρροής που ασκούν οι παραπάνω έννοιες, στον τρόπο που προσεγγίζουμε τα αρχαιολογικά δεδομένα και διαμορφώνουμε τις ερμηνείες του παρελθόντος. Αφετηρία του άρθρου αποτελεί ο προσδιορισμός και η ερμηνεία της Καρυστίας, για την οποία υπο- στηρίζω πως θα πρέπει να ιδωθεί αυτοδίκαια ως ‘νησί’ , τουλάχιστον σε ότι αφορά την ένταξη της στην ευρύτερη ζώνη των Κυκλάδων. Μετα την διεξοδική αναφορά στα κριτήρια νησιωτικότητας που χαρακτηρίζουν το παράδειγμα της Καρυστίας, το άρθρο συνεχίζει με την διερεύνηση των τρόπων με τους οποίους η νησιωτικότητα και τα θαλάσσια δίκτυα επικοινωνίας διαμόρφωσαν τις ατομικές και συλλογικές ταυτότητες των προϊστορικών Καρυστίων και πως επηρέασαν την κοινωνικό-πολιτική ζωή και τους θεσμούς τους

Charging of Individual Micron-Size Interstellar/Planetary Dust Grains by Secondary Electron Emissions

Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with UV/X-ray radiation, as well as by electron/ion impact. Knowledge of physical and optical properties of individual dust grains is required for understanding of the physical and dynamical processes in space environments and the role of dust in formation of stellar and planetary systems. In this paper, we discuss experimental results on dust charging by electron impact, where low energy electrons are scattered or stick to the dust grains, thereby charging the dust grains negatively, and at sufficiently high energies the incident electrons penetrate the grain leading to excitation and emission of electrons referred to as secondary electron emission (SEE). Currently, very limited experimental data are available for charging of individual micron-size dust grains, particularly by low energy electron impact. Available theoretical models based on the Sternglass equation (Sternglass, 1954) are applicable for neutral, planar, and bulk surfaces only. However, charging properties of individual micron-size dust grains are expected to be different from the values measured on bulk materials. Our recent experimental results on individual, positively charged, micron-size lunar dust grains levitated in an electrodynamic balance facility (at NASA-MSFC) indicate that the SEE by electron impact is a complex process. The electron impact may lead to charging or discharging of dust grains depending upon the grain size, surface potential, electron energy, electron flux, grain composition, and configuration (e.g. Abbas et al, 2010). Here we discuss the complex nature of SEE charging properties of individual micron-size lunar dust grains and silica microspheres

Study of the Effects of the Electric Field on Charging Measurements on Individual Micron-size Dust Grains by Secondary Electron Emissions

The dust charging by electron impact is an important dust charging process in Astrophysical, Planetary, and the Lunar environments. Low energy electrons are reflected or stick to the grains charging the dust grains negatively. At sufficiently high energies electrons penetrate the grain leading to excitation and emission of electrons referred to as secondary electron emission (SEE). Available theoretical models for the calculation of SEE yield applicable for neutral, planar or bulk surfaces are generally based on Sternglass Equation. However, viable models for charging of individual dust grains do not exist at the present time. Therefore, the SEE yields have to be obtained by some experimental methods at the present time. We have conducted experimental studies on charging of individual micron size dust grains in simulated space environments using an electrodynamic balance (EDB) facility at NASA-MSFC. The results of our extensive laboratory study of charging of individual micron-size dust grains by low energy electron impact indicate that the SEE by electron impact is a very complex process expected to be substantially different from the bulk materials. It was found that the incident electrons may lead to positive or negative charging of dust grains depending upon the grain size, surface potential, electron energy, electron flux, grain composition, and configuration. In this paper we give a more elaborate discussion about the possible effects of the AC field in the EDB on dust charging measurements by comparing the secondary electron emission time-period (tau (sub em) (s/e)) with the time-period (tau (sub ac) (ms)) of the AC field cycle in the EDB that we have briefly addressed in our previous publication

Laboratory Measurements on Charging of Individual Micron-Size Apollo-11 Dust Grains by Secondary Electron Emissions

Observations made during Apollo missions, as well as theoretical models indicate that the lunar surface and dust grains are electrostatically charged, levitated and transported. Lunar dust grains are charged by UV photoelectric emissions on the lunar dayside and by the impact of the solar wind electrons on the nightside. The knowledge of charging properties of individual lunar dust grains is important for developing appropriate theoretical models and mitigating strategies. Currently, very limited experimental data are available for charging of individual micron-size size lunar dust grains in particular by low energy electron impact. However, experimental results based on extensive laboratory measurements on the charging of individual 0.2-13 micron size lunar dust grains by the secondary electron emissions (SEE) have been presented in a recent publication. The SEE process of charging of micron-size dust grains, however, is found to be very complex phenomena with strong particle size dependence. In this paper we present some examples of the complex nature of the SEE properties of positively charged individual lunar dust grains levitated in an electrodynamic balance (EDB), and show that they remain unaffected by the variation of the AC field employed in the above mentioned measurements

Experimental Investigation of Charging Properties of Interstellar Type Silica Dust Grains by Secondary Electron Emissions

The dust charging by electron impact is an important dust charging processes in astrophysical and planetary environments. Incident low energy electrons are reflected or stick to the grains charging the dust grains negatively. At sufficiently high energies electrons penetrate the grains, leading to excitation and emission of electrons referred to as secondary electron emission (SEE). Available classical theoretical models for calculations of SEE yields are generally applicable for neutral, planar, or bulk surfaces. These models, however, are not valid for calculations of the electron impact charging properties of electrostatically charged micron/submicron-size dust grains in astrophysical environments. Rigorous quantum mechanical models are not yet available, and the SEE yields have to be determined experimentally for development of more accurate models for charging of individual dust grains. At the present time, very limited experimental data are available for charging of individual micron-size dust grains, particularly for low energy electron impact. The experimental results on individual, positively charged, micron-size lunar dust grains levitated carried out by us in a unique facility at NASA-MSFC, based on an electrodynamic balance, indicate that the SEE by electron impact is a complex process. The electron impact may lead to charging or discharging of dust grains depending upon the grain size, surface potential, electron energy, electron flux, grain composition, and configuration (Abbas et al, 2010, 2012). In this paper, we discuss SEE charging properties of individual micron-size silica microspheres that are believed to be analogs of a class of interstellar dust grains. The measurements indicate charging of the 0.2m silica particles when exposed to 25 eV electron beams and discharging when exposed to higher energy electron beams. Relatively large size silica particles (5.2-6.82m) generally discharge to lower equilibrium potentials at both electron energies. These measurements conducted on silica microspheres are qualitatively similar in nature to our previous SEE measurements on lunar Apollo missions dust samples

Laboratory Studies of Charging Properties of Dust Grains in Astrophysical/Planetary Environments

Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with UV/X-ray radiation, as well as by electron/ion impact. Knowledge of physical and optical properties of individual dust grains is required for understanding of the physical and dynamical processes in space environments and the role of dust in formation of stellar and planetary systems. In this paper we focus on charging of individual micron/submicron dust grains by processes that include: (a) UV photoelectric emissions involving incident photon energies higher than the work function of the material and b) electron impact, where low energy electrons are scattered or stick to the dust grains, thereby charging the dust grains negatively, and at sufficiently high energies the incident electrons penetrate the grain leading to excitation and emission of electrons referred to as secondary electron emission (SEE). It is well accepted that the charging properties of individual micron/submicron size dust grains are expected to be substantially different from the bulk materials. However, no viable models for calculation of the charging properties of individual micron size dust grains are available at the present time. Therefore, the photoelectric yields, and secondary electron emission yields of micron-size dust grains have to be obtained by experimental methods. Currently, very limited experimental data are available for charging of individual micron-size dust grains. Our experimental results, obtained on individual, micron-size dust grains levitated in an electrodynamic balance facility (at NASA-MSFC), show that: (1) The measured photoelectric yields are substantially higher than the bulk values given in the literature and indicate a particle size dependence with larger particles having order-of-magnitude higher values than for submicron-size grains; (2) dust charging by low energy electron impact is a complex process. Also, our measurements indicate that the electron impact may lead to charging or discharging of dust grains depending upon the grain size, surface potential, electron energy, electron flux, grain composition, and configuration (e.g. Abbas et al, 2010). Laboratory measurements on charging of analogs of the interstellar dust as well as Apollo 11 dust grains conducted at the NASA-MSFC Dusty Plasma Lab. are presented her

A 3D spatial approach to post-excavation study, as exemplified at the Agia triada Cave, Karystos

Η εργασία συνοψίζει τα αποτελέσματα της προσπάθειας αναβάθμισης ενός συμβατικού ανασκαφικού αρχείου με τη χρήση τεχνολογιών Γεωγραφικών Συστημάτων Πληροφοριών (ΓΣΠ), με στόχο τη δια- χείριση των δεδομένων, την υποστήριξη της στρωματογραφικής ανάλυσης και την οπτική διερεύνηση της χωρικής κατανομής των ευρημάτων στις τρεις διαστάσεις (3Δ). Το ανασκαφικό πρόγραμμα στο σπήλαιο της Αγίας Τριάδας, στη Νότια Εύβοια, λειτούργησε ως περίπτωση εφαρμογής όπου επιχει- ρήθηκε η ενσωμάτωση διαφόρων τύπων ανασκαφικών δεδομένων (καταχωρίσεις ανασκαφικού ημε- ρολογίου, σχέδια, κατάλογοι ευρημάτων, φωτογραφίες) σε ένα συνεκτικό σύνολο δεδομένων για 3Δ ΓΣΠ. Ο συνδυασμός όλων των τεκμηρίων σε ένα ενιαίο ψηφιακό αρχείο συντέλεσε στην αρτιότερη διαχείριση, την πρόσβαση και την αντιπαραβολή των πληροφοριών. Η χωρική αναπαράσταση στις τρεις διαστάσεις και η οπτική διερεύνηση των δεδομένων συνέβαλε στη συγκρότηση ενός χρήσιμου αναλυτικού μέσου για την τρέχουσα μετα-ανασκαφική μελέτη που επέτρεψε την καλύτερη κατανό- ηση των πολύπλοκων στρωματογραφικών και ταφονομικών συνθηκών εντός του σπηλαίου. Σε αυτό το πλαίσιο, η χρήση της ψηφιακής τεχνολογίας για την αναδιάρθρωση παλαιότερων ή συμβατικών συλλογών δεδομένων σε νέα συγκρίσιμα ψηφιακά αρχεία μπορεί να συμβάλλει σημαντικά τόσο στην ενδο-ανασκαφική όσο και στην περιφερειακή αρχαιολογική έρευνα

Complex Role of Secondary Electron Emissions in Dust Grain Charging in Space Environments: Measurements on Apollo 11 and 17 Dust Grains

Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions. Knowledge of the dust grain charges and equilibrium potentials is important for understanding of a variety of physical and dynamical processes in the interstellar medium (ISM), and heliospheric, interplanetary, planetary, and lunar environments. The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. It has been well recognized that the charging properties of individual micron/submicron size dust grains are expected to be substantially different from the corresponding values for bulk materials and theoretical models. In this paper we present experimental results on charging of individual dust grains selected from Apollo 11 and Apollo 17 dust samples by exposing them to mono-energetic electron beams in the 10- 400 eV energy range. The charging rates of positively and negatively charged particles of approximately 0.2 to 13 microns diameters are discussed in terms of the secondary electron emission (SEE) process, which is found to be a complex charging process at electron energies as low as 10-25 eV, with strong particle size dependence. The measurements indicate substantial differences between dust charging properties of individual small size dust grains and of bulk materials

(C)overt linguistic racism: Eastern-European background immigrant women in the Australian workplace

Linguistic racism explores the varied ideologies that may generate and endorse monolingual, native, and normative language practices, while reinforcing the discrimination and injustice directed towards language users whose language and communicative repertoires are not necessarily perceived as standard and normal. This article, thus, investigates linguistic racism, as a form of existing, but newly defined, racism against unconventional ethnic language practices experienced by Eastern-European immigrant women in the Australian workplace. Our ethnographic study shows that, once these women directly or subtly exhibit their non-nativism, through a limited encounter with local expressions, non-native language skills, and ethnic accents, they become victims of covert and overt linguistic racism in the form of social exclusion, mockery, mimicking, and malicious sarcasm in the hierarchical power environment of the workplace. As a result, these migrants can suffer from long-lasting psychological trauma and distress, emotional hurdles, loss of credibility, and language-based inferiority complexes. We, as researchers, need to highlight the importance of combatting workplace linguistic racism and revealing language realities of underprivileged communities. In that way, we can assist them in adapting to host societies and help them regain some degree of power equality in their institutional environments