Development of skeletal deformities in Gilthead sea bream (Sparus aurata) reared under different larval culture and dietary conditions

[EN] Main deformities such as lordosis, opercular deformities and upper/lower jaws shortening are considered as quality descriptors in commercial marine fish fry production and seem to be related at least with larval culture conditions in early larval stages. The aim of this work was to obtain information about the contribution of the diet and rearing system to the apparition of these abnormalities in gilthead sea bream (Sparus aurata) larvae in semi-industrial scale facilities. For that purpose, two different larval rearing systems semi-intensive and intensive were compared by duplicate and with the same live feed enrichments; besides, two different rotifer enrichments were tested in an intensive system. Biochemical composition of larvae, preys and commercial products was analysed. At 50 days post hatching six hundred fish per treatment were individually studied under stereoscope and abnormalities frequency recorded. At 95 days post hatching fry were soft X ray monitored as well. Survival and malformation frequency were significantly different between treatments, the effect of diet and system are discussed. A significantly lower percentage of deformity rates together with better survival and growth were obtained in the semi-intensive system, whereas the rotifer enrichment significantly affected larval survival.

Atmospheric radiative transfer in multiple scattering conditions. Application to NWP models.

High spectral resolution radiative transfer (RT) codes are essential tools in the study of the radiative energy transfer in the Earth atmosphere and a support for the development of parameterizations for fast RT codes used in climate and weather prediction models. Cirrus clouds cover permanently 30% of the Earth's surface, representing an important contribution to the Earth-atmosphere radiation balance. The work has been focussed on the development of the RT model LBLMS. The model, widely tested in the infra-red spectral range, has been extended to the short wave spectrum and it has been used in comparison with airborne and satellite measurements to study the optical properties of cirrus clouds. A new database of single scattering properties has been developed for mid latitude cirrus clouds. Ice clouds are treated as a mixture of ice crystals with various habits. The optical properties of the mixture are tested in comparison to radiometric measurements in selected case studies. Finally, a parameterization of the mixture for application to weather prediction and global circulation models has been developed. The bulk optical properties of ice crystals are parameterized as functions of the effective dimension of measured particle size distributions that are representative of mid latitude cirrus clouds. Tests with the Limited Area Weather Prediction model COSMO have shown the impact of the new parameterization with respect to cirrus cloud optical properties based on ice spheres.

Atmospheric corrosion of quaternary bronzes (Cu-Sn-Zn-Pb): laboratory tests (accelerated ageing in wet & dry conditions)and field studies (the Bottego monument in Parma, Italy).

The interactions between outdoor bronzes and the environment, which lead to bronze corrosion, require a better understanding in order to design effective conservation strategies in the Cultural Heritage field. In the present work, investigations on real patinas of the outdoor monument to Vittorio Bottego (Parma, Italy) and laboratory studies on accelerated corrosion testing of inhibited (by silane-based films, with and without ceria nanoparticles) and non-inhibited quaternary bronzes are reported and discussed. In particular, a wet&dry ageing method was used both for testing the efficiency of the inhibitor and for patinating bronze coupons before applying the inhibitor. A wide range of spectroscopic techniques has been used, for characterizing the core metal (SEM+EDS, XRF, AAS), the corroded surfaces (SEM+EDS, portable XRF, micro-Raman, ATR-IR, Py-GC-MS) and the ageing solutions (AAS). The main conclusions were: 1. The investigations on the Bottego monument confirmed the differentiation of the corrosion products as a function of the exposure geometry, already observed in previous works, further highlighting the need to take into account the different surface features when selecting conservation procedures such as the application of inhibitors (i.e. the relative Sn enrichment in unsheltered areas requires inhibitors which effectively interact not only with Cu but also with Sn). 2. The ageing (pre-patination) cycle on coupons was able to reproduce the relative Sn enrichment that actually happens in real patinated surfaces, making the bronze specimens representative of the real support for bronze inhibitors. 3. The non-toxic silane-based inhibitors display a good protective efficiency towards pre-patinated surfaces, differently from other widely used inhibitors such as benzotriazole (BTA) and its derivatives. 4. The 3-mercapto-propyl-trimethoxy-silane (PropS-SH) additivated with CeO2 nanoparticles generally offered a better corrosion protection than PropS-SH.

Influence of processing conditions on quality aspects of potato-based fresh pasta

Gnocchi is a typical Italian potato-based fresh pasta that can be either homemade or industrially manufactured. The homemade traditional product is consumed fresh on the day it is produced, whereas the industrially manufactured one is vacuum-packed in polyethylene and usually stored at refrigerated conditions. At industrial level, most kinds of gnocchi are usually produced by using some potato derivatives (i.e. flakes, dehydrated products or flour) to which soft wheat flour, salt, some emulsifiers and aromas are added. Recently, a novel type of gnocchi emerged on the Italian pasta market, since it would be as much similar as possible to the traditional homemade one. It is industrially produced from fresh potatoes as main ingredient and soft wheat flour, pasteurized liquid eggs and salt, moreover this product undergoes steam cooking and mashing industrial treatments. Neither preservatives nor emulsifiers are included in the recipe. The main aim of this work was to get inside the industrial manufacture of gnocchi, in order to improve the quality characteristics of the final product, by the study of the main steps of the production, starting from the raw and steam cooked tubers, through the semi-finished materials, such as the potato puree and the formulated dough. For this purpose the investigation of the enzymatic activity of the raw and steam cooked potatoes, the main characteristics of the puree (colour, texture and starch), the interaction among ingredients of differently formulated doughs and the basic quality aspects of the final product have been performed. Results obtained in this work indicated that steam cooking influenced the analysed enzymes (Pectin methylesterase and α- and β-amylases) in different tissues of the tuber. PME resulted still active in the cortex, it therefore may affect the texture of cooked potatoes to be used as main ingredient in the production of gnocchi. Starch degrading enzymes (α- and β-amylases) were inactivated both in the cortex and in the pith of the tuber. The study performed on the potato puree showed that, between the two analysed samples, the product which employed dual lower pressure treatments seemed to be the most suitable to the production of gnocchi, in terms of its better physicochemical and textural properties. It did not evidence aggregation phenomena responsible of hard lumps, which may occur in this kind of semi-finished product. The textural properties of gnocchi doughs were not influenced by the different formulation as expected. Among the ingredients involved in the preparation of the different samples, soft wheat flour seemed to be the most crucial in affecting the quality features of gnocchi doughs. As a consequence of the interactive effect of the ingredients on the physicochemical and textural characteristics of the different doughs, a uniform and well-defined split-up among samples was not obtained. In the comparison of different kinds of gnocchi, the optimal physicochemical and textural properties were detected in the sample made with fresh tubers. This was probably caused not only by the use of fresh steam cooked potatoes, but also by the pasteurized liquid eggs and by the absence of any kind of emulsifier, additive or preserving substance.

Speciation of tetravalent plutonium in contact with humic substances and kaolinite under environmental conditions

Plutonium represents the major contribution to the radiotoxicity of spent nuclear fuel over storage times of up to several hundred thousand years. The speciation of plutonium in aquifer systems is important in order to assess the risks of high-level nuclear waste disposal and to acquire a deep knowledge of the mobilization and immobilization behavior of plutonium. In aqueous solutions, plutonium can coexist in four oxidation states and each one of them has different chemical and physical behavior. Tetravalent plutonium is the most abundant under natural conditions. Therefore, detailed speciation studies of tetravalent plutonium in contact with humic substances (HS) and kaolinite as a model clay mineral have been performed in this work. Plutonium is present in the environment at an ultratrace level. Therefore, speciation of Pu at the ultratrace level is mandatory. Capillary electrophoresis (CE) coupled to resonance ionization mass spectrometry (RIMS) was used as a new speciation method. CE-RIMS enables to improve the detection limit for plutonium species by 2 to 3 orders of magnitude compared to the previously developed CE-ICP-MS. For understanding the behavior of Pu(IV) in aqueous systems, redox reactions, complexation, and sorption behavior of plutonium were studied. The redox behavior of plutonium in contact with humic acid (HA) and fulvic acid (FA) was investigated. A relatively fast reduction of Pu(VI) in contact with HS was observed. It was mainly reduced to Pu(IV) and Pu(III) within a couple of weeks. The time dependence of the Pu(IV) complexation with Aldrich HA was investigated and a complex constant (logßLC) between 6.4 - 8.4 of Pu(IV) was determined by means of ultrafiltration taking into account the loading capacity (LC). The sorption of tetravalent plutonium onto kaolinite was investigated as a function of pH in batch experiments under aerobic and anaerobic conditions. The sorption edge was found at about pH = 1 and a maximum sorption at around pH = 8.5. In the presence of CO2 at pH > 8.5, the sorption of plutonium was decreased probably due to the formation of soluble carbonate complexes. For comparison, the sorption of Th(IV) onto kaolinite was also investigated and consistent results were found. The Pu(IV) sorption onto kaolinite was studied by XANES and EXAFS at pH 1, 4, 9 and the sorbed species on kaolinite surface was Pu(IV). Depending on the pH, only 1 - 10 % of the sorbed plutonium is desorbed from kaolinite and released into a fresh solution at the same pH value. Furthermore, the sorption of HS onto kaolinite was studied as a function of pH at varying concentrations of HS, as a prerequisite to understand the more complex ternary system. The sorption of HA onto kaolinite was found to be higher than that of FA. The investigation of the ternary systems (plutonium-kaolinite-humic substances) is performed as a function of pH, concentration of HS, and the sequences of adding the reactants. The presence of HS strongly influences the sorption of Pu(IV) onto kaolinite over the entire pH range. For comparison, the influence of HS on the sorption of Th(IV) onto kaolinite was also investigated and a good agreement with the results of Pu(IV) was obtained.

Weathering of Fe-bearing minerals under extraterrestrial conditions, investigated by Mössbauer spectroscopy

The weathering of Fe-bearing minerals under extraterrestrial conditions was investigated by Mössbauer (MB) spectroscopy to gain insights into the role of water on the planet Mars. The NASA Mars Exploration Rovers Spirit and Opportunity each carry a miniaturized Mössbauer spectrometer MIMOS II for the in situ investigation of Martian soils and rocks as part of their payload. The MER flight instruments had to be modified in order to work over the Martian diurnal temperature range (180 K – 290 K) and within the unique electronic environment of the rovers. The modification required special calibration procedures. The integration time necessary to obtain a good quality Mössbauer spectrum with the MIMOS II flight instruments was reduced by 30 % through the design of a new collimator. The in situ investigation of rocks along the rover Spirit's traverse in Gusev crater revealed weakly altered olivine basalt on the plains and pervasively altered basalt in the Columbia Hills. Correlation plots of primary Fe-bearing minerals identified by MB spectroscopy such as olivine versus secondary Fe-bearing phases such as nanophase Fe oxides showed that olivine is the mineral which is primarily involved in weathering reactions. This argues for a reduced availability of water. Identification of the Fe-oxyhydroxide goethite in the Columbia Hills is unequivocal evidence for aqueous weathering processes in the Columbia Hills. Experiments in which mineral powders were exposed to components of the Martian atmosphere showed that interaction with the atmosphere alone, in the absence of liquid water, is sufficient to oxidize Martian surface materials. The fine-grained dust suspended in the Martian atmosphere may have been altered solely by gas-solid reactions. Fresh and altered specimens of Martian meteorites were investigated with MIMOS II. The study of Martian meteorites in the lab helped to identify in Bounce Rock the first rock on Mars which is similar in composition to basaltic shergottites, a subgroup of the Martian meteorites. The field of astrobiology includes the study of the origin, evolution and distribution of life in the universe. Water is a prerequisite for life. The MER Mössbauer spectrometers identified aqueous minerals such as jarosite and goethite. The identification of jarosite was crucial to evaluate the habitability of Opportunity's landing site at Meridiani Planum during the formation of the sedimentary outcrop rocks, because jarosite puts strong constrains on pH levels. The identification of olivine in rocks and soils on the Gusev crater plains provide evidence for the sparsity of water under current conditions on Mars. Ratios of Fe2+/Fe3+ were obtained with Mössbauer spectroscopy from basaltic glass samples which were exposed at a deep sea hydrothermal vent. The ratios were used as a measure of potential energy for use by a microbial community. Samples from Mars analogue field sites on Earth exhibiting morphological biosignatures were also investigated.

Streptococcus agalactiae adapts to glucose stress conditions by modulating gene expression profile

Diabetes mellitus is considered a risk factor for Group B Streptococcus (GBS) infections. Typically, this pathology is associated to high glucose levels in the bloodstream. Although clinical evidences support this notion, the physiological mechanisms underlying GBS adaptation to such conditions are not yet defined. In the attempt to address this issue, we performed comparative global gene expression analysis of GBS grown under glucose-stress conditions and observed that a number of metabolic and virulence genes was differentially regulated. Of importance, we also demonstrated that by knocking-out the csrRS locus the transcription profile of GBS grown in high-glucose conditions was profoundly affected, with more than a third of glucose-dependent genes, including the virulence factor bibA, found to be controlled by this two-component system. Furthermore, in vitro molecular analysis showed that CsrR specifically binds to the bibA promoter and the phosphorilation increases the affinity of the regulator to this promoter region. Moreover, we demonstrated that CsrR acts as a repressor of bibA expression by binding to its promoter in vivo. In conclusion, this work by elucidating both the response of GBS to pathological glucose conditions and the underlined molecular mechanisms will set the basis for a better understanding of GBS pathogenesis.

Thermal fluctuations and boundary conditions in the lattice Boltzmann method

The lattice Boltzmann method is a popular approach for simulating hydrodynamic interactions in soft matter and complex fluids. The solvent is represented on a discrete lattice whose nodes are populated by particle distributions that propagate on the discrete links between the nodes and undergo local collisions. On large length and time scales, the microdynamics leads to a hydrodynamic flow field that satisfies the Navier-Stokes equation. In this thesis, several extensions to the lattice Boltzmann method are developed. In complex fluids, for example suspensions, Brownian motion of the solutes is of paramount importance. However, it can not be simulated with the original lattice Boltzmann method because the dynamics is completely deterministic. It is possible, though, to introduce thermal fluctuations in order to reproduce the equations of fluctuating hydrodynamics. In this work, a generalized lattice gas model is used to systematically derive the fluctuating lattice Boltzmann equation from statistical mechanics principles. The stochastic part of the dynamics is interpreted as a Monte Carlo process, which is then required to satisfy the condition of detailed balance. This leads to an expression for the thermal fluctuations which implies that it is essential to thermalize all degrees of freedom of the system, including the kinetic modes. The new formalism guarantees that the fluctuating lattice Boltzmann equation is simultaneously consistent with both fluctuating hydrodynamics and statistical mechanics. This establishes a foundation for future extensions, such as the treatment of multi-phase and thermal flows. An important range of applications for the lattice Boltzmann method is formed by microfluidics. Fostered by the "lab-on-a-chip" paradigm, there is an increasing need for computer simulations which are able to complement the achievements of theory and experiment. Microfluidic systems are characterized by a large surface-to-volume ratio and, therefore, boundary conditions are of special relevance. On the microscale, the standard no-slip boundary condition used in hydrodynamics has to be replaced by a slip boundary condition. In this work, a boundary condition for lattice Boltzmann is constructed that allows the slip length to be tuned by a single model parameter. Furthermore, a conceptually new approach for constructing boundary conditions is explored, where the reduced symmetry at the boundary is explicitly incorporated into the lattice model. The lattice Boltzmann method is systematically extended to the reduced symmetry model. In the case of a Poiseuille flow in a plane channel, it is shown that a special choice of the collision operator is required to reproduce the correct flow profile. This systematic approach sheds light on the consequences of the reduced symmetry at the boundary and leads to a deeper understanding of boundary conditions in the lattice Boltzmann method. This can help to develop improved boundary conditions that lead to more accurate simulation results.

Turbulence models in the atmospheric boundary layer under convective conditions

In this work a modelization of the turbulence in the atmospheric boundary layer, under convective condition, is made. For this aim, the equations that describe the atmospheric motion are expressed through Reynolds averages and, then, they need closures. This work consists in modifying the TKE-l closure used in the BOLAM (Bologna Limited Area Model) forecast model. In particular, the single column model extracted from BOLAM is used, which is modified to obtain other three different closure schemes: a non-local term is added to the flux- gradient relations used to close the second order moments present in the evolution equation of the turbulent kinetic energy, so that the flux-gradient relations become more suitable for simulating an unstable boundary layer. Furthermore, a comparison among the results obtained from the single column model, the ones obtained from the three new schemes and the observations provided by the known case in literature ”GABLS2” is made.

Influence of plant structure, cultural pratices and environmental conditions on the development of the bacterial canker of kiwifruits

Italy has a preeminent rank in kiwifruit industry, being the first exporter and the second largest producer after China. However, in the last years kiwifruit yields and the total cultivated area considerably decreased, due to the pandemic spread of the bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa). Several climatic conditions and cultural practices affect the development of the bacterial canker. This research work focused on the impact of agricultural practices and microclimate conditions on the incidence and epidemiology of Psa in the orchard. Therefore, the effect of fertilization, irrigation, use of bio-regulators, rootstock, training system and pruning were examined. The effect of different tunnel systems was analyzed as well, to study the plant-pathogen interaction. Considering the importance of insects as vectors in other pathosystems, the role of Metcalfa pruinosa in the spread of the bacterial canker was investigated in controlled conditions. In addition, quality and storage properties of fruits from infected plants were assessed. The study of all these aspects of the agronomic practices is useful to define a strategy to limit the bacterial diffusion in the orchard. Overall, excess nitrogen fertilization, water stress, stagnant water supplies, pruning before summer and the high number of Metcalfa pruinosa increased the Psa incidence. In contrast, tunnel covers may be useful for the control of the disease, with special attention to the kind of material.

Immunophenotyping of acute leukemia and lymphoproliferative disorders: a consensus proposal of the European LeukemiaNet Work Package 10

The European LeukemiaNet (ELN), workpackage 10 (WP10) was designed to deal with diagnosis matters using morphology and immunophenotyping. This group aimed at establishing a consensus on the required reagents for proper immunophenotyping of acute leukemia and lymphoproliferative disorders. Animated discussions within WP10, together with the application of the Delphi method of proposals circulation, quickly led to post-consensual immunophenotyping panels for disorders on the ELN website. In this report, we established a comprehensive description of these panels, both mandatory and complementary, for both types of clinical conditions. The reason for using each marker, sustained by relevant literature information, is provided in detail. With the constant development of immunophenotyping techniques in flow cytometry and related software, this work aims at providing useful guidelines to perform the most pertinent exploration at diagnosis and for follow-up, with the best cost benefit in diseases, the treatment of which has a strong impact on health systems.

Maximizing Product Formation and Minimizing Degradation: A Look at Buffering Conditions and Post-Reaction Degradation for the In-Line Jaffe Reaction with Capillary Electrophoresis

Creatinine levels in blood serum are typically used to assess renal function. Clinical determination of creatinine is often based on the Jaffe reaction, in which creatinine in the serum reacts with sodium picrate, resulting in a spectrophotometrically quantifiable product. Previous work from our lab has introduced an electrophoretically mediated initiation of this reaction, in which nanoliter plugs of individual reagent solutions can be added to the capillary and then mixed and reacted. Following electrophoretic separation of the product from excess reactant(s), the product can be directly determined on column. This work aims to gain a detailed understanding of the in-capillary reagent mixing dynamics, in-line reaction yield, and product degradation during electrophoresis, with an overall goal of improving assay sensitivity. One set of experiments focuses on maximizing product formation through manipulation of various conditions such as pH, voltage applied, and timing of the applied voltage, in addition to manipulations in the identity, concentration, and pH of the background electrolyte. Through this work, it was determined that dramatic changes in local voltage fields within the various reagent zones lead to ineffective reagent overlapping. Use of the software simulation program Simul 5 enabled visualization of the reaction dynamics within the capillary, specifically the wide variance between the electric field intensities within the creatinine and picrate zones. Because of this simulation work, the experimental method was modified to increase the ionic strength of the creatinine reagent zone to lower the local voltage field, thus producing more predictable and effective overlap conditions for the reagents and allowing the formation of more Jaffe product. As second set of experiments focuses on controlling the post-reaction product degradation. In that vein, we have systematically explored the importance of the identity, concentration, and pH of the background electrolyte on the post-reaction degradation rate of the product. Although prior work with borate background electrolytes indicated that product degradation was probably a function of the ionic strength of the background electrolyte, this work with a glycine background electrolyte demonstrates that degradation is in fact not a function of ionic strength of the background electrolyte. As the concentration and pH of the glycine background increased, the rate of degradation of product did not change dramatically, whereas in borate-buffered systems, the rate of Jaffe product degradation increased linearly with background electrolyte concentration above 100.0 mM borate. Similarly, increasing pH of the glycine background electrolyte did not result in a corresponding increase in product degradation, as it had with the borate background electrolyte. Other general trends that were observed include: increasing background electrolyte concentration increases peak efficiency and higher pH favors product formation; thus, it appears that use of a background electrolyte other than borate, such as glycine, the rate of degradation of the Jaffe product can be slowed, increasing the sensitivity of this in-line assay.

Talents in Migration Processes in the Conditions of the Czech Republic of the Nineties

The transformation of the 1990s has had a bearing on the academic and scientific world, as is becoming increasingly obvious with the changing numbers of foreign students wishing to study in the Czech Republic and of Czech students wishing to study abroad, the virtual collapse of doctoral studies, and the rapidly increasing age of Czech academics (placed at 48 by official sources and at rather more by this research). At the same time there is an apparent lack of interest in analysing and understanding these trends, which Mr. Cermak terms an ostrich policy, although his research showed that academics are in fact both aware and concerned about them. The mid-1990s migration of talent to and from R+D in the Czech Republic is also reflected in the number of talented Czech students studying abroad, who represent the largest and most interesting group of actual and potential migrants. Mr. Cermak's study took the form of a Delphi enquiry participated in by 44 specialists, including experts in the problems of higher education and science policy from the Presidium of the Higher Education Council (n = 23), members of the Council's Science and Research Commission (n = 14), former and current managers of higher education authorities (n = 4) and selected participants of the longitudinal talent research (n = 3). Questions considered included the influence of continuing talent migration from domestic R+D on the efficiency of domestic higher education, the diversification of forms of the brain drain and their impact on other processes in society, the possibility of positive influence on the brain drain processes to minimise the risks it presents, and the use of the knowledge obtained about the brain drain. The study revealed a clear drop of interest in brain drain problems in higher education in the mid-1990s, which is probably related to the collapsed of Czech R+D in the field of talent education. The effects on this segment of the labour market appeared earlier, with a major migration wave in 1991-1993 which significantly "cleared" the area of scientific talent. In addition, prospective talents from the ranks of younger students have not been integrated into domestic R+D, leading to the increasing average age of those working in this field. "Talent scouting" tended to be oriented towards much younger individuals, even in some cases towards undergraduate students. The R+D institutions deprived of human resources considered as basic in a functional R+D system have lost much of their dynamism and so no longer attract not only domestic talent but also talent from other regions. As a result the public, including the mass media and political structures, have stopped regarding the support of domestic science as a priority. This is clear both among the young people who are important for the future development of R+D (support for the education of talented children has dropped), from the drop in the prestige of this area as a profession among university students, and from the lack of explicit support for R+D by any of the political parties. On the basis of his findings Mr. Cermak concludes that there is no basis for the belief that the brain drain will represent a positive force in stimulating the development of the open society. Migration data shows that the outflow of talent from the Czech Republic far exceeds the inflow, and that the latter is largely short-term. Not only has the number of returning Czech professors dropped to half of its level at the beginning of the 1990s, but they also tend to take up only short-term contracts and retain their foreign positions. Recruitment of scientific talent from other countries, including the Slovak Republic, is limited. Furthermore internal contacts between those already involved in R+D have been badly hit by economic pressures and institutional co-operation has dropped to a minimum. There have been few moves to counteract this situation, the only notable one being the Program 250, launched in 1996 with government support to try and attract younger (i.e. under 40) talent into R+D. Its resources are however limited and its effects have not so far been evaluated. The deficit of academic and scientific talent in the Czech Republic is increasing and two major directions of academic work are emerging. Classic higher education science based on the teaching process is declining, largely due to economic factors, while there is an increasing emphasis on special; ad hoc projects which cannot be related directly to teaching but are often interesting to specialists outside the Czech Republic. This is shown clearly by the increase in publishing and in participation in domestic and foreign grant projects, which often serve to supplement the otherwise low salaries in the higher education sector. This tend was also accelerated by the collapse of applied R+D in individual sectors of the national economy and by substantial cutbacks in the Czech Academy of Sciences, which formerly fostered such research. Some part of the output of this research can be used in the education system and its financial contribution does significantly affect the stability of the present staff, but Mr. Cermak sees it as generally unfavourable for the development of talent education. In addition, it has led to a certain resignation on the question of integration into international structures, due to the emphasis on short-term targets, commercial advantages and individualism rather than team work. At the same time, he admits that these developments reflect those in other areas of the transformation in the Czech Republic.

"What is the Value of Youth Work?" Symposium Booklet

As a group of experienced and novice youth workers, we believe that youth work is fundamentally about building trust-filled, mutually respectful relationships with young people. We create safe environments for young people to connect with other supportive adults and peers and to avoid violence in their neighborhoods and their homes. We guide those harmed by oppressive community conditions such as racism, sexism, agism, homophobia, and classism through a process of healing. As we get to know more about young people’s interests, we help them develop knowledge and skills in a variety of areas including: academic, athletic, leadership/civic, the arts, health and wellbeing, and career exploration. In short, we create transformative experiences for young people. In spite of the critical roles we play, we have largely been overlooked in youth development research, policy, and as a professional workforce. We face challenges ‘moving up’ in our careers. We get frustrated by how little money we earn. We are discouraged that despite our knowledge and experience we are not invited to the tables where youth funding, programming, and policy decisions are made. It is true—many of us do not have formal training or degrees in youth work—a reality which at times we regret. Yet, as our colleague communicates in the accompanying passage (see below), we resent that formal education is required for us to get ahead, particularly because we question whether we need it to do our jobs more effectively. Through the “What is the Value of Youth Work?” symposium, we hope to address these concerns through a dialogue about youth work with the following objectives: • Increase awareness of the knowledge, skills, contributions, and professionalism of youth workers; • Advance a youth worker professional development model that integrates a dilemma-focused approach with principles of social justice youth development; • Launch an ongoing Worcester area Youth Worker network. This booklet provides a brief overview of the challenges in ‘professionalizing’ youth work and an alternative approach that we are advancing that puts the knowledge and expertise of youth workers at the center of professional development.

Jan Fook: Social Work: Critical Theory and Practice & Karen Healy: Social Work Practices: Contemporary Perspectives on Change

In his recent book on the contemporary politics of social work, Powell (2001) nominates Jan Fook and Karen Healy as two Australian authors who have made significant contributions to the radical or critical social work tradition. I have chosen to review them together, as each, in different ways, attempts to achieve the same purpose. That is, they attempt to provide a convincing account for adopting a critical approach to practice in the contemporary conditions of the 21st century and, in doing so, re-invigorate the radical tradition of social work practice. My first comment, important for the readership of this international journal, is that both books easily 'travel' beyond the Australian context.