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Objective:In image-guided neurosurgery, co-registered preoperative anatomical, functional, and diffusion tensor imaging can be used to facilitate a safe resection of brain tumors in eloquent areas of the brain. However, the brain deforms during surgery, particularly in the presence of tumor resection. Non-Rigid Registration (NRR) of the preoperative image data can be used to create a registered image that captures the deformation in the intraoperative image while maintaining the quality of the preoperative image. Using clinical data, this paper reports the results of a comparison of the accuracy and performance among several non-rigid registration methods for handling brain deformation. A new adaptive method that automatically removes mesh elements in the area of the resected tumor, thereby handling deformation in the presence of resection is presented. To improve the user experience, we also present a new way of using mixed reality with ultrasound, MRI, and CT.Materials and methods:This study focuses on 30 glioma surgeries performed at two different hospitals, many of which involved the resection of significant tumor volumes. An Adaptive Physics-Based Non-Rigid Registration method (A-PBNRR) registers preoperative and intraoperative MRI for each patient. The results are compared with three other readily available registration methods: a rigid registration implemented in 3D Slicer v4.4.0; a B-Spline non-rigid registration implemented in 3D Slicer v4.4.0; and PBNRR implemented in ITKv4.7.0, upon which A-PBNRR was based. Three measures were employed to facilitate a comprehensive evaluation of the registration accuracy: (i) visual assessment, (ii) a Hausdorff Distance-based metric, and (iii) a landmark-based approach using anatomical points identified by a neurosurgeon.Results:The A-PBNRR using multi-tissue mesh adaptation improved the accuracy of deformable registration by more than five times compared to rigid and traditional physics based non-rigid registration, and four times compared to B-Spline interpolation methods which are part of ITK and 3D Slicer. Performance analysis showed that A-PBNRR could be applied, on average, in Conclusions:The A-PBNRR method performed significantly better than other readily available registration methods at modeling deformation in the presence of resection. Both the registration accuracy and performance proved sufficient to be of clinical value in the operating room. A-PBNRR, coupled with the mixed reality system, presents a powerful and affordable solution compared to current neuronavigation systems.

Modern Nuclear Physics experimental setups run experiments with higher beam intensity resulting in increased noise in detector components used for particle track reconstruction. Increased uncorrelated signals (noise) result in decreased particle reconstruction efficiency. In this paper, we investigate the usage of Machine Learning, specifically Convolutional Neural Network Auto-Encoders (CAE), for de-noising raw hits from drift chambers in the CLAS12 detector. To the best of our knowledge, this is the first time CAE is employed to perform such an operation in this field. During the de-noising phase, it is important to remove as much noise as possible while retaining the valid hits to avoid losing crucial information about the experiment. We show that using CAE, it is possible to remove noise hits while retaining up to 94% of valid tracks for a beam current of 110 n A while for lower beam currents ( 45 − 55 n A ), we get up to 98% efficiency. Studies on experimental conditions with increasing noise show that CAE performs better than conventional tracking algorithms in isolating hits belonging to tracks. Specifically, the de-noising algorithm results in tracking efficiency improvements greater than 15%, in real data production procedures with nominal conditions, and up to two times better efficiency in synthetically generated data with high luminosity conditions ( 90 − 110 n A ), indicating that machine learning can lead to significantly shorter times for conducting physics experiments.

Rent seeking leads to a misallocation of resources that worsens economic outcomes and reduces aggregate welfare. We conduct a quantitative examination of the distributional effects of rent extraction via the financial sector. Rent seeking introduces a possibility for insurance against idiosyncratic earnings risk that is more valuable for poorer households that are lacking in means of self insurance. However, it also creates a wedge that discourages savings, thus reducing self insurance via asset accumulation. When the model is calibrated to US data, the distorting effects dominate, implying welfare losses for all households, and an increase in wealth inequality. Nevertheless, welfare losses are bigger for households with higher initial wealth. Therefore, a policy reform to reduce rent seeking via the financial sector, despite being Pareto improving, will benefit predominantly wealthier households.

We consider a pure exchange economy with asymmetric information where individual behavior exhibits ambiguity aversion along the line of maximin expected utility decision making. For such economies, we introduce different notions of maximin value allocations. We also introduce a strong notion of incentive compatibility. We prove the existence and incentive compatibility of the maximin value allocation. We conclude that unlike the Bayesian value allocation approach in Krasa Yannelis (Econometrica 62(4):881–900, 1994), incentive compatibility is related to efficiency rather than to direct exchange of information.

In this work we show results of Monte Carlo modeling of electrons and heavy particles induced spatially resolved emission intensity or the Doppler profile in pure H2 discharge focusing on anode boundary. In particular we present study of fast H2 and fast H particles, scattered both at the surface and of the molecules. Since the anode boundary is characterized by a large electron flux, role of electron reflection and production of secondary electrons at the anode surface is part of the complete picture of spatial emission profile. In this work we verify our models of electron backscattering from the anode including both the reflection and the secondary electron production by making comparisons with the drift tube experiments. In order to achieve consistency with our previous results we select conditions of simulation appropriate for very high E/N (E‐electric field, N‐gas density) that are selected from experimental Townsend discharges in pure H2.

Several modalities are currently utilized for diagnosis and therapy, by appropriate application of x‐rays. In diagnostic radiology, interventional radiology, radiotherapy, interventional cardiology, nuclear medicine and other specialties radiation protection of a pregnant woman as a patient, as well as a member of the operating personnel, is of outmost importance. Based on radiation risk, the termination of pregnancy is not justified if foetal doses are below 100 mGy. For foetal doses between 100 and 500 mGy, a decision is reached on a case by case basis. In Diagnostic Radiology, when a pregnant patient takes an abdomen CT, then an estimation of the foetus’ dose is necessary. However, it is extremely rare for the dose to be high enough to justify an abortion. Radiographs of the chest and extremities can be done at any period of pregnancy, provided that the equipment is functioning properly. Usually, the radiation risk is lower than the risk of not undergoing a radiological examination. Radiation exposure in uterus from diagnostic radiological examinations is unlikely to result in any deleterious effect on the child, but the possibility of a radiation‐induced effect can not be entirely ruled out. The effects of exposure to radiation on the foetus depend on the time of exposure, the date of conception and the absorbed dose. Finally, a pregnant worker can continue working in an x‐ray department, as long as there is reasonable assurance that the foetal dose can be kept below 1 mGy during the pregnancy. Nuclear Medicine diagnostic examinations using short‐lived radionuclides can be used for pregnant patient. Irradiation of the foetus results from placental transfer and distribution of radiopharmaceuticals in the foetal tissues, as well as from external irradiation from radioactivity in the mother’s organ and tissues. As a rule, a pregnant patient should not undergo therapy with radionuclide, unless it is crucial for her life. In Radiotherapy, the patient, treating oncologist, other team and family members should carefully discuss for the decision of abortion. Important factors must be considered such as the stage and aggressiveness of the tumour, the location of the tumour, the stage of pregnancy, various therapies etc.

In the present paper we examine some aspects of using of microscopic models‐simulations in the teaching of Physics. Specifically, the aim is to investigate the effect of the microscopic model of thermal conduction in explaining a thermal phenomenon and to investigate the effect of the microscopic model of polarization in predicting an electrostatic phenomenon. Twenty‐five lower secondary students in compulsory education and 12 university pre‐service primary education student‐teachers, in Thessaloniki, Greece participated in the model‐based units of thermal conduction and electric polarization respectively. In both cases students were involved in model exploration rather than in model construction, however in electric polarization the “predictive” use of models has been adopted while in the case of thermal conductivity the approach emphasized explanation. Results showed that students, to a certain extend, managed to use the microscopic models of thermal conduction and electric polarization in order to explain and predict, respectively, the phenomena.

We present the time distribution of a large number (7798) of Myocardial Infractions (MI) recorded at the General Hospital ‘St. Panteleimon’ of the city of Nikea (in Piraeus, Greece), during time interval 1997–2007. This data set consisted of 5160 NON‐STEACS (non‐ST) and 2638 STEACS (ST) infractions are examined along with the monthly numbers of solar flares and Coronal Mass Ejections (CMEs), solar wind parameters and the geomagnetic activity (Dst geomagnetic index and other). The mean monthly value of ST and non‐ST events is 20 and 40 respectively. The maximum monthly value of non‐ST events (72 and 73) are recorded in October 2002 and January 2003, as well as the one of ST events (32), while solar maximum, recorded in November 2002. This time interval is characterized by magnetic storms from August 2002 peaked in October 2002 and ended in February 2003. It is noticeable that August 2002 corresponds to the solar maximum of CMEs and strong solar flares monthly values. The maximum monthly value of ST events (40) is recorded in November 2005 almost simultaneously with a sudden absence of solar flares (October 2005). Increased values have been recorded during a period of extreme solar events of October–November 2003 and January–March 2005. It seems from this extensive statistical study that there is an association between the monthly values of MI and of CMEs; the non‐ST MI shows a better association with CMEs. Moreover, the MI yearly distribution is in accordance with the time distribution of magnetic storms (number and duration). The non‐ST distribution is also affected by intense magnetic storms.

A novel slurry‐based process for aluminizing nickel foams while improving the mechanical properties and conserving the excellent ductility is reported. Cellular unalloyed nickel foams with 92% porosity and uniform pore size and distribution were used as a starting material. Several slurries of different compositions were examined to investigate the possibility of developing an aluminide‐nickel intermetallic coating on a Ni foam without considerably degrading the original ductile properties of the foam. The process temperature was varying from 400 to 850° C and the process holding time was ranging between 2h to 6h. Scanning electron microscopy with an energy dispersive X‐ray spectrometry and X‐Ray diffraction were applied to assess the effectiveness of the aluminizing process and determine both the optimum parameters of the procedure (slurry composition, holding temperature and time) and the concentration profiles across the coating cross‐section. The mechanical behavior of the aluminized Ni‐foams was evaluated by the conduction of micro‐tension tests. The resulting Ni‐foams after aluminization retain the pore structure of original Ni‐foams and present a thick outer surface layer which consists of a range of aluminide phases. The mechanical properties of the Ni‐foams aluminized in low process temperature were insignificantly affected.

The study of Munella ores is based on four analysis (A, B, Cand cores). They represent different types of minerals in the Munella area. Cores were taken by the geologist of Puka Geological Enterprise. A Core: It represents an ore with pyrite and chalcopyrite where copper and sulfur contents are 0.77 and 8.2% respectively. B Core: This core represents an ore with spharelites and pyrite where zinc content is 1.5% and 2.9% sulfur one. C Core: It is a chalcopyrite ore, massive in nature, where copper content is 2.01% and 36% sulfur one. D Core: It also represents copper‐ zinc—sulfur ore where their content is 0.66, 1.00 and 4.28% respectively. Each core is studied individually by selective schema to have copper, zinc and pyrite concentrates. Copper and pyrite concentrates will be the first material for pyro‐ metallurgical industry.

This paper presents several simple experiments in thermodynamics that enable students to accept and understand the basic thermodynamics laws and their practical application in an obvious way, through active learning by solving problems.

Plasma polymerized hexamethyldisiloxane (PPHMDS) is a polymer frequently considered for biomedical application due to its easy fabrication, low cost and biocompatibility. However, a drawback of using PPHMDS in osteosubstitutive engineering is its high hydrophobicity, causing extremely low cellular interaction. Surface wettability can be altered in many ways such as plasma treatment, surface coating, introduction of hydrophilic or hydrophobic groups by self‐assembled monolayers, etc. Among all these methods plasma treatment is one of most effective and economical ways to modify surface wettability of a material. Here, we investigated three different PPHMDS layers prepared by plasma polymerization (PP) of HMDS on cover glass (CG) under two different technological regimes. In order to improve cellular interactions, PPHMDS films obtained by the second operating mode were further hydrophylized in NH3 plasma. Cell‐biomaterial interactions were characterized by human osteoblast‐like MG63 cell model, where overal...

Some chemical compound with fluorescence properties can be used as artificial tracers for water system studies. The problem in this case is dealt with in relation to applying Sulphorhodamine G Extra to trace and study underground communications between Prespa and Ohrid Lakes. The fluorescence intensity of Sulphorhodamine G Extra (SRG) in water samples depends on their chemical and physical properties, such as pH, presence of oxidants, temperature, etc. This paper presents the experience of the Center of Applied Nuclear Physics, Tirana, in this field. The method we have elaborated to this purpose made it possible to optimize procedures we use to analyze water samples for the presence of Sulphorhodamine G Extra and measure its content, even in trace levels, by the means of a Perkin Elmer LS 55 Luminiscence Spectrometer.

Cosmic ray detectors are widely used, for educational purposes, in order to motivate students to the physics of elementary particles and astrophysics. Using a “telescope” of scintillation counters, the directional characteristics, diurnal variation, correlation with solar activity, can be determined, and conclusions about the composition, origin and interaction of elementary particles with the magnetic field of earth can be inferred. A telescope was built from two rectangular scintillator panels with dimensions: 91.6×1.9×3.7 cm3. The scintillators are placed on top of each other, separated by a fixed distance of 34.6 cm. They are supported by a wooden frame which can be rotated around a horizontal axis. Direction is determined by the coincidence of the signals of the two PMTs. Standard NIM modules are used for readout. This device is to be used in the undergraduate nuclear and particle physics laboratory. The design and construction of the telescope as well as some preliminary results are presented.

A fractal distribution requires that the number of objects larger than a specific size r has a power‐law dependence on the size N(r) = C/rD∝r−D where D is the fractal dimension. Usually the correlation integral is calculated to estimate the correlation fractal dimension of epicentres. A ‘box‐counting’ procedure could also be applied giving the ‘capacity’ fractal dimension. The fractal dimension can be an integer and then it is equivalent to a Euclidean dimension (it is zero of a point, one of a segment, of a square is two and of a cube is three). In general the fractal dimension is not an integer but a fractional dimension and there comes the origin of the term ‘fractal’. The use of a power‐law to statistically describe a set of events or phenomena reveals the lack of a characteristic length scale, that is fractal objects are scale invariant.Scaling invariance and chaotic behavior constitute the base of a lot of natural hazards phenomena. Many studies of earthquakes reveal that their occurrence exhibits s...

The thermostimulated discharge current method (TSDC) is widely used for the study of charge storage mechanisms in electrets. A new discharged technique, called differential, which consists in discharging a charged sample through an otherwise identical but uncharged one, has been proposed by J.‐P. Reboul and A. Toureille. In the present paper a new version of the differential thermostimulated discharge current method is advanced. In contrast to the differential technique described earlier, the measuring cell allows to realize typical differential technique. In this case the measuring system records the difference of the thermostimulated currents of two samples which have been preliminary charged (or thermally treated) under the same or different conditions. Samples of 0.85 mm thick polymethylmethacrylate are used to demonstrate an operation of the developed differential TSDC method.

Study of the linear harmonic oscillator confined in the square well with impenetrable walls is of great interest since its application for modeling parabolic quantum well semiconductor heterostructures. Fisher information and Shannon entropy, as a complexity measure for its ground and some excited energy levels are reported here.

Thin AuAgOx films with prolonged lifetimes (up to 1 1/2years) were produced by reactive sputtering in a magnetron allowing a smooth variation of the degree of ion assistance by an external solenoid. The film specific electric resistivity and the film lifetimes were found to be single power functions of a combined parameter representing a product of solenoid current and oxygen gas pressure divided by magnetron discharge power.

The design of alloys, that economize strategic element as chromium requires detailed physical investigations of their structure and phase composition. In the search for new materials in the last two decades a new class of Fe alloys was composed—the so‐called nitrogen steels. The contemporary achievements in the casting technology—the use of nitrogen under high preasure above the melt—made possible the production of Fe alloys with nitrogen concentration even above 0.4 wt%. The wide application of investigated alloy system is connected with creation of alloys without presence of strong carbides‐forming elements. The microstructure and phase formation of these new materials are insufficiently studied. The aim of this work is to characterize the microstructure and phase composition of two series Fe‐alloys casted with and without nitrogen pressure above the melt. The so cast steels appear as experimental ones and they are directed to demonstrate the possibility for nitrogen doping of steels without presence of...

In this study, response of the cofacial bis‐ phthalocyanine film to vapor of Volatile Organic Compounds (VOCs) was investigated. Test gases were vapors of acetone, toluene, ethanol and ammonia. Measurements were carried out between the temperatures of 293 K–423 K. Bis‐phthalocyanine was dissolved in chloroform. Thin film of bis‐phthalocyanine was deposited by spraying method on glass substrate patterned with Interdigital Transducer (IDT). During the measurements 0.5 volts were applied to the IDT. Response characteristics of the film were determined by means of change in dc conductivity as a function of gas concentration and temperature. Gas concentrations were controlled by mass flow controller. Dry nitrogen was used as carrier gas. Vapor pressure of the VOCs was calculated using Antoine equation. Response characteristics of the film were determined in a wide range of gas concentration (0.25%–18%). The film showed good sensitivity to the VOCs vapors in the measurement range. The responses of the film were...

We use the three‐species cyclic competition model (Rock‐Paper‐Scissors), described by reactions A+B→2B, B+C→2C, C+A→2A, for emulating a computer network with e‐mail viruses. Different topologies of the network bring about different dynamics of the epidemics. When the parameters of the network are varied, it is observed that very high clustering coefficients are necessary for a pandemics to happen. The differences between the networks of computer users, e‐mail networks, and social networks, as well as their role in determining the nature of epidemics are also discussed.

In the context of the European Project on Material Science we have developed a Teaching Learning Sequence (TLS), which is composed by units for teaching thermal conductivity in depth to students. The scientific content has been adapted to students’ conceptions taking into account research results. Units follow the Predict‐Observe‐Explain strategy and students conduct guided investigations using an enriched learning environment, which consists of extensive use of ICT based tools. Didactically transformed microscopic models depict thermal interactions in iconic, graphic and symbolic forms. Students working in groups, solve problems, explore models and are engaged in classroom discussion on the problem under study, constructing links between evidence and explanations. In this paper the structure of such innovative units is presented and results showing students’ development in scientific understanding are reported.

The electronic structure and magnetic properties of FexPt1−x disordered alloys have been studied by means of the tight‐binding linear muffin‐tin orbital method in the atomic sphere approximation and in conjunction with the coherent potential approximation. The iron magnetic moment depends linearly on composition. As the pressure increases there are phase transitions from magnetic to nonmagnetic states. The volume magnetostriction is evaluated within disordered local moment formalism. A good agreement with the experimental results is obtained in the Invar composition range. The volume magnetostriction rapidly decreases with increasing Pt content.

Series of relatively large earthquakes in different regions of the Earth are studied. The regions chooses are of a high seismic activity and has a good contemporary network for recording of the seismic events along them. The main purpose of this investigation is the attempt to describe analytically the seismic process in the space and time. We are considering the statistical distributions the distances and the times between consecutive earthquakes (so called pair analysis). Studies conducted on approximating the statistical distribution of the parameters of consecutive seismic events indicate the existence of characteristic functions that describe them best. Such a mathematical description allows the distributions of the examined parameters to be compared to other model distributions.

Polycrystalline silicon (poly‐Si) layers were functionalized through the growth of biomimetic hydroxyapatite (HA) on their surface. HA is the mineral component of bones and teeth and thus possesses excellent bioactivity and biocompatibility. MG‐63 osteoblast‐like cells were cultured on both HA‐coated and un‐coated poly‐Si surfaces for 1, 3, 5 and 7 days and toxicity, proliferation and cell morphology were investigated. The results revealed that the poly‐Si layers were bioactive and compatible with the osteoblast‐like cells. Nevertheless, the HA coating improved the cell interactions with the poly‐Si surfaces based on the cell affinity to the specific chemical composition of the bone‐like HA and/or to the higher HA roughness.

In this article we present an alternative explanation of the phenomenon of wire fragmentation under high transient currents based on classical electromagnetism. We also explain how this phenomenon can be utilized as a primitive example of low energy‐high power disruptive phenomena that can affect even nuclear matter.

A tunable electro‐optical switching is reported for single‐layered polymer‐dispersed liquid crystal (PDLC) films, controlled by the film thickness. Thin planar film of two‐dimensional layer of thickness continuously varying from a few micrometers to several tens of micrometers is examined. The wedge‐confined PDLC single layer contains E7 liquid‐crystal microdroplets dispersed in a transparent polymer matrix of NOA65. The diameters of the droplets with a linear‐gradient size distribution along the wedge slope reach several tens of micrometers, defined by the wedge geometry of the film. The electro‐optical switching of the single‐layered PDLC film is linked to its microstructure and droplet organization.

From May 2004, in the Institute of Nuclear Physics is installed Albanian Radiological Monitoring Network, in the framework of emergency monitoring in the territory of Albania. In this network, this is unique monitoring on‐line system in our country. are included 5(five) monitoring stations, respectively in Tirane, Shkoder, Kukes, Korce and Vlore. The last four stations are near Albanian borders The network performs measures of ambient dose rate in a range from 5 nSv/h up to 10 Sv/h. For measurements are used detector of type VACUTEC 70045 A, which are calibrated in the Centre of Applied Nuclear Physics, University of Tirana, using standard radiation source Cs‐137. This monitoring help to warn in real time the relative authorities, in case of radiological accidents of 5th degree (for example accidents in nuclear power plants, near Albanian territory).

We report analysis of temperature fluctuations in turbulent thermal convection in a cylindrical container of aspect ratio 4. Temperature fluctuations are measured at the opposite ends of a cell diameter 4 cm inboard of the sidewall and at the cell centre in the central horizontal plane of the apparatus, for Rayleigh numbers (Ra) ranging from 1.043×109 to 6.5×1011. For these Ra, experimental conditions obey Boussinesq approximation. Autocorrelation and cross correlation have been used to analyze the data. The period of about 33 s found by autocorrelation for Ra = 1.043×109, indicates the advection of plumes by a large‐scale coherent wind, tilted along the diagonal, which encompasses the entire container. In good agreement with autocorrelation, cross‐correlation between sidewall signals in the central horizontal, but at opposite ends of a cell diameter, show a strong long‐time correlation indicative of a well ordered and robust mean wind. While no clear correlation exists between the sidewall fluctuations a...

The discrete nonlinear Schrodinger equation with third‐ and fifth‐order nonlinearities is investigated. Effects of discreteness for the homogeneous case are analyzed. Exact analytical solutions are found for wide static solitons in the presence of impurities. The bound soliton‐defect solutions can be single‐peak for attractive impurities or double‐peak for repulsive impurities. In contrast to the standard cubic nonlinear case, where the positions of the peaks do not depend on the nonlinearity, now they are strongly influenced by the quintic nonlinearity. The model plays an important role in numerous physical systems with complicated nonlinear interactions.

Optical phonons (k≈0) of the double perovskite NdBaCo2O5+x are calculated in the cases of x = 0, 1 (tetragonal P4/mmm, a = b = ap, c≈2ap) and x = 0.5 (orthorhombic Pmmm, a = ap, b≈2ap, c≈2ap) using the shell model. The calculated modes in the three crystal structures are classified according to their symmetry and frequency. By analyzing the eigenvectors for different modes the most intense bands in the Raman spectra of the complex compound NdBaCo2O5+x are predicted.

Various problems in perturbation theory of (quantum) gauge models can be rephrased in the language of cohomology theory. This was already noticed in the functional formulation of perturbative gauge theories. Causal perturbation theory is a fully quantum approach: is works only with the chronological products which are defined as operator‐valued distributions in the Fock space of the model. The use of causal perturbation theory leads to similar cohomology problems; the main difference with respect to the functional methods comes from the fact that the gauge transformation of the causal approach is, essentially, the linear part of the non‐linear BRST transformation.Using these methods it is possible to give a nice determination of the interaction Lagrangians for gauge models (Yang‐Mills and gravitation in the linear approximation); one obtains with this method the unicity of the interaction Lagrangian up to trivial terms. The case of quantum gravity is highly non‐trivial and can be generalized with this met...

This study summarizes results of an investigation done in order to find out how the radioactive aerosols of 7Be could serve as indicators of air pollution conditions. Beryllium‐7 is a cosmic‐ray produced radionuclide with an important fraction of its production to take place in the upper troposphere. Once it is formed is rapidly associated with submicron aerosol particles and participates in the formation and growth of the accumulation mode aerosols, which is a major reservoir of pollutants in the atmosphere. In order to define any influence of AMAD of 7Be aerosols by air pollution conditions, the aerodynamic size distribution of 7Be aerosols was determined by collecting samples at different locations in the suburban area of the city of Thessaloniki, including rural areas, industrial areas, high elevations, marine environment and the airport area. The aerodynamic size distribution of 7Be aerosols in different locations was obtained by using Andersen 1‐ACFM cascade impactors and the Activity Median Aerodyn...

The Earth is bombarded by cosmic radiation, a nearly isotropic flux of energetic charged particles. Their interaction with air nuclei generates a cascade of secondary particles and gamma rays. This work describes the results of measurements of cosmic radiation at various altitudes on mount Olympus using TL dosimeters (Al2O3:C). The glow curves of TLDs after external exposure have been compared to the ones obtained after beta irradiation in the laboratory. Pb‐shielding was used for separation of gamma contribution from terrestrial radiation environment.

Polyelectrolyte complexes (PECs) of chitosan and carrageenan were used for preparation of multilayered microbeads. The optimal conditions of complex formation—pH and molar ratio between the polyelectrolyte partners, were preliminary investigated by viscometry. It was found that the yield of the complex is the highest at pH 5 where both of the partners were highly charged. Chitosan was used as a core of the beads and carrageenan/chitosan multilayers were deposited by layer‐by‐layer technique. Swelling and stability of the beads were investigated in dependence on the pH of the media. The multilayer deposition let to modification of the swelling behaviour—the equilibrium degree of swelling decreased at pH 3 and increased at basic pH. These changes were attributed to the polyelectrolyte properties of carrageenan/chitosan PECs—the impact of the effective charges in PECs network. Mehanical properties of the swelled beads were evaluated by Stable Micro Systems table penetrometer, with flat‐plate compression test. The test was carried out with low deformation speed, until the full rupture. The diameter of measure cylinder was chosen to be bigger then the diameter of beads. The different swellings caused differences in elastic properties of the multilayered beads.

Residue length dependency of conformational transition of Val1 ‐Pro2 ‐Gly3 ‐Val4‐ Gly5 known as elastin polypeptide is investigated by using multicanonical Monte Carlo (MUCA) method. By extending the residue length, change in the thermodynamical quantites is indicated in an implicit solvation model (SCH2). Strong residue length dependency is observed in thermodynamical quantities.

The photo‐induced changes in As‐S‐Se ternary glasses offer a possibility of using amorphous chalcogenide layers for high‐density information storage, high‐resolution display devices and fabrication of diffractive optical elements. In this paper we report results of the photo‐induced changes in the optical properties of optically uniform thin As40S60−xSex films. The refractive index is determined with spectrophotometric method in a wide spectral region. The influence of light on the dispersion parameters of thin chalcogenide films is demonstrated. The holographic properties of As40S30Se30 layers with different thickness are investigated applying a symmetrical two‐beam scheme. A semiconductor laser (Lead Light Technology, Inc.) generating at 532 nm is used as a light source. The two beams are s‐polarized. The total intensity after spatial filtering and beam expanding was 10 mW/cm2. The diffraction efficiency kinetics is monitored with a 1.5 mW semiconductor laser at 635 nm wavelength, operating at optimal r...

In this paper we present design considerations and experimental results of a thermosyphonic hybrid PV/T solar system that is investigated at the University of Patras. Hybrid PV/T systems can provide electrical and thermal energy, thus achieving a higher energy conversion rate of the absorbed solar radiation. We tested outdoors PV/T prototypes consisted of pc‐Si PV modules and heat exchanger of copper sheet with copper pipes, for two system types (PVT/UNGL and PVT/GL). We used commercial PV modules, which give about 12%–15% efficiency, depending on the operating temperature and the use or not of additional glazing. During the experiments the generated electricity was transmitted to a load, simulating real system operation. Steady state tests of the system were performed outdoors to determine collector thermal efficiency. The glazed PV/T collector presents remarkably higher thermal output than the unglazed PV/T collector, but the electrical output of it is reduced due to additional optical losses. The experimental study of the tested thermosyphonic hybrid PV/T solar device showed that it can perform effectively during all year long, achieving at least 40° C of hot water and producing electricity at a satisfactory level.

In this paper we study the solar wind parameters during the 23rd solar cycle and the possible correlation between them. Those parameters’ data, which are Alfven Mach number, plasma beta, flow speed, proton density and temperature, dynamic pressure, average magnetic field, Bx and By, has been taken from OMNI 2. The first part of this project is about analysis and correlation of the data, using Pearson’s product moment correlation coefficient and Spearman Rank Correlation Coefficient, during the 11 years of the 23rd cycle. The second part is about Wavelet analysis on those parameters during the 21st, 22nd, 23rd solar cycles in comparison with them. We found that each parameter has different behavior in every cycle and certain periodicities that appear constantly.

This report aims to give consideration to the time–space evolution of the phase boundary by making use of the kinematic condition on the interface, representing the balance of the mass fluxes through the movable growing boundary, as well as the Gibbs‐Thompson condition of the local phase equilibrium. The analysis has shown the determinative role of a dimensionles parameter—combination of only physical properties of the system—on the evolution of surface fluctuations.

Systematic effects in precision luminosity measurement at the International Linear Collider are discussed. In particular, beam‐beam interaction effects, background from physics processes, and effect of bias and resolution of measured energy in the luminosity calorimeter. Simulation is done at 500 GeV and 1 TeV center of mass energy. Some prospects at 3 TeV are also discussed for the CLIC case.

Instrumental Epithermal Neutron Activation Analysis was used to investigate the distribution of six major elements and 34 trace elements in a set of eight igneous and metamorphic rocks collected from Carpathian and Macin Mountainsas well as unconsolidated sediments collected from anoxic zone of the Black Sea. All experimental data were interpreted within the Upper Continental Core and Mid Ocean Ridge Basalt model system that allowed getting more information concerning samples origin as well as the environmental peculiarities.

In this work we present some results of lidar remote sensing of aerosol layers in the atmosphere in Sofia region. The investigations were made using a lidar system equipped with a CuBr‐vapor laser with high pulse repetition of 13 kHz and receiver in photon counting mode. These measurements were performed in frame of the project European Aerosol Research Lidar Network—Advanced Sustainable Observation System (EARLINET—ASOS). For some of presented results a conclusion about atmospheric aerosol’s origins was made upon analyses of the information about the weather condition during the lidar measurements. Such information was obtained by the weather‐forecast maps provided by the Atmospheric Modeling and Weather Forecasting Group of NTUA and the Forecast system of Barcelona Supercomputing Centre and accessible via Internet. Additional information is provided by calculations of the backward air mass trajectories, using online software of NOAA about HYSPLIT model (HYbrid Single‐Particle Lagrangian Integrated Trajectory). A common database that automatically collects the data products provided by the individual lidar stations is build and makes data of measurements available to the scientific community.

In the general framework of the computer‐aided drug design, the method of molecular‐dynamics simulations is applied for investigation of the human interferon‐gamma (hIFN‐γ) binding to its two known ligands (its extracellular receptor and the heparin‐derived oligosaccharides). A study of 100 mutated hIFN‐γ forms is presented, the mutations encompassing residues 86–88. The structural changes are investigated by comparing the lengths of the α‐helices, in which these residues are included, in the native hIFN‐γ molecule and in the mutated forms. The most intriguing cases are examined in detail.

In the middle of XV century, in European Renaissance, it was necessary to study the Aristotle in original Greek, because translations from Arab in Latin had caused considerable alterations in the meaning of original texts. This task in the beginning was trusted to Leonico Tomeo, which, not only opened the way for the studying of the Aristotle in original, but himself made important interpretations about philosophic and social problems and gave his arguments about concepts of natural sciences, as for motion, atoms etc. He translated some works of Plato, Aristotle, Ptolemy etc, from the Greek to Latin. The work of Tomeo gave revolutionary results and prepared the way for the scientific method of Galileo, which from Padua, where worked and lived Tomeo and later, Galileo, propagates in all European universities.

We investigate the relationship of metric type III radio bursts obtained with radio spectrograph ARTEMIS IV (20–650 MHz) in Thermopylae, to GOES SXR/Ha and SOHO/LASCO CMEs within the period of intense activity 20 October to 5 November 2003. Our sample consists of 123 type III radio bursts, 115 SXR Flares (mostly C—type) and 12 CMEs. 69% of type III bursts are coincident in time with SXR Flares, while the rest 31% were detected between successive SXR flux maxima and though not always in the same active region as the SXR Flare, thereby labeled as SXR Less. The lack of SXR enhancement in SXR less type III bursts was probably the result of increased SXR background which prevented detection. It is found also, that 62% of the Flares are associated with type III radio bursts. Furthermore, we study the characteristic type III parameters i.e. start frequency, frequency band and duration as well as the SXR Flare parameters i.e. Flux, Duration, Apparent Area, rise time, decay time and their ratio. Finally, we tried to investigate any characteristic variation occurred because of the different morphology of the three major active regions, 484, 486 and 488 of that period.