I Servizi bibliotecari agli studenti

Relation about the library services provided by the University of Sassari, especially those intended for students

Riunione di coordinamento dei responsabili dei Centri di documentazione europea: introduzione e conclusioni

Report of the librarians and documentalists meeting about the management and spreading of European community information. The meeting was promoted by the European documentation centre of the University of Sassari together with the Italian Representation at the European Community, held in Naples on 31 October 1997 during the 43rd AIB National Conference

La Misurazione dei servizi delle biblioteche delle università

The topic of measurement is not new to the library world. For some twenty years, professional literature, especially American and British, has dealt with the topic, as is shown by the 600 plus titles listed in the bibliography of the IFLA's recently-published guidelines for measuring the quality of university library services. The initial, theoretical approach was supplanted, in the early 1990s, by a more practical stance, with numerous operational models for librarians. This is the direction in which some international bodies are also moving today; in addition to the manual promoted by IFLA, the provisional version of the ISO manual and that which originated from the PROLIB/PI project financed by the European Commission have also been published. In Italy, interest in the topic is recent. The current situation can be summarised as one of "ongoing research", in the sense that the various experiments, seminars and discussions now in progress are gradually standardising definitions and methodologies suited to the historical and cultural context of Italian libraries. As regards academic libraries, measurement studies and applications are still few and far between, there is a dearth of documentation and emphasis to date has been on the quantitative aspects of the return with a view to rationalising resources and saving costs. The work should be continued, but oriented also towards effectiveness and, hence, fostering an assessment of the value of the services and not just of their productivity and costs. The quality of client-oriented services and the need to control the effectiveness of the library's capacity for interaction with its users should become the objectives of the new climate of managerial and organisational measures and the benchmark of the suitability of the players' professionalism to sustain the change of mentality demanded by the continuous broadening and diversification of higher education establishment users and of their needs. The work, which derives from the co-ordination experience of the Sassari University libraries, and in particular from the recording of the work loads, aims to satisfy the need to monitor all organisational aspects, both quantitative and qualitative, with a renewed attention to the client. The work starts out with some methodological clarifications, dedicated to the manner of use and requisites of the indicators and to the measurement path, offers considerations regarding data collection (on finances, assets, personnel, user spaces and reading places, potential users and services) with a view to creating a computerised system as a mandatory measurement stage, and concludes by proposing some measurement instruments immediately applicable even in libraries with little experience in this field. A comparative analysis of the main sources of library performance measurement was used to draw up a list of twenty indicators, specifically adapted to the realities of Italian university libraries and oriented to the direct and indirect evaluation of the quality of the service with users as the principal reference. All indicators can respond to the measurement needs of individual libraries, but some are well suited to monitoring a university library system. The paper concludes with a description of the eleven indicators, of the twenty elaborated, which were deemed the most client-oriented. The attention paid to them meets the objective of exemplifying the approach, method, applicability and limits of use of performance indicators. For each indicator, the information is organised on the basis of a grid adopted by IFLA, which appeared the best suited to exemplify the measurement approach through performance indicators, to facilitate their use also by inexperienced librarians, and to highlight all the elements which it was deemed appropriate to take into account in the application phas

Estonia and Lithuania in transition: A compared analysis of the change and its costs and benefits

On the aftermath of the dissolution of the Soviet Union, the newly independent republics had to face a choice over which economic system should be adopted, and how to implement the transition from a planned economy to market economy system. The aim of this paper is to provide a brief overview of the transition process in the cases of Estonia and Lithuania, two countries with a similar history but with significant differences on the social, economic and cultural background. The two countries undertook two different sets of transition reforms: while the first country chose the path of the so called “shock therapy”, Lithuania opted for a more gradual transition. The paper will bring a comparative analysis of the two transitions and of its different outcomes after approximately 25 years of transition

Synergy between habitat fragmentation and climate change: implications for biodiversity in Alpine ecosystems

An increase in global temperature accompanied by rapid fragmentation of habitats will lead to greater pressure on biodiversity, with more dramatic impacts expected on high mountain ranges. A new wave of extinction is likely to occur as the ability of species to migrate toward new cooler suitable areas will be hampered by altered landscapes, also the magnitude of species loss will in part depend on species traits, or phenotypic plasticity of individuals which will have to adapt to the changed environmental conditions. In this PhD thesis, I included different models employing altitudinal gradient as a surrogate, to understand how effects determined by climatic variation might or might not exacerbate the negative impact of landscape changes on carabid communities (eastern Italian Alps). Chapter I contains a brief overview of the current body of scientific literature on the main ecological impacts of habitat fragmentation and climate change, and the emerging research related to the response of organisms to the synergistic impacts of these two threats. The aim of Chapter II is to determine whether the effects of rising temperature might enhance the impact of habitat fragmentation on beetle diversity and community structure. Chapter III describes an attempt to assess the existence of simultaneous effects generated by habitat fragmentation and climate change on variation of morphological traits (fluctuating asymmetry and body length) in natural populations of forest-dwelling species Haptoderus unctulatus. Finally, Chapter IV explores if species’ sensitivity to landscape modification and altitude might be maximized or not by a combination of life history traits of ground beetles. In summary, data of carabid assemblages suggest that the impact of rising temperature acting in synergy with land use pressure will move up along the mountainside, inflicting more serious negative impact on species composition, and causing changes in morphological traits of beetle populations particularly accentuated at lowlands. Also, interaction between these two drivers of change will exert a selective pressure on species with certain functional traits, which will result in a greater impact on the beetle assemblages of Alpine ecosystems than either driver acting individually

Gamma-ray pulsars: a multi-band view

This Thesis is based mainly on the results of the timing analysis applied to the gamma-ray pulsars observed principally by the AGILE satellite and also extended, in some cases, to observations with the Fermi-LAT satellite and the MAGIC Cherenkov telescope. Aim of this extended study of pulsars at the high energies was to characterize their properties based, now, on a more statistically relevant sample, and be able to disentangle useful informations that can be key to explain the emission mechanisms in pulsars. THE SCIENTIFIC CONTEXT Pulsars are highly-magnetized, rapidly-rotating neutron stars. As explained in Chapter 1, they have been observed in the radio band over the past forty years, due to their highly anisotropic emission, which, when combined with the misalignment between the rotation and the magnetic axis, produces the pulsed emission we observed, also called the ”lighthouse effect”. Pulsars have been observed as gamma-ray emitters as well, but it is only in the past three years that their number hit the double digits and they started to yield their potential as keys to explain the neutron stars mechanisms. In Chapter 1, the basics of pulsar theory are given. While the phenomenological aspects have been widely studied thanks to extensive radio observations through the years, their electrodynamics represents an articulated field that is difficult to probe. The ”classical” models of magnetosphere predict the presence of regions of particles’ under-density (a ”gap”), inside an overall force-free magnetized area that surrounds the pulsar, where the particles can be accelerated and can produce the observed radiation, after a number of cascade processes. More ”modern” models of magnetosphere, with their roots in old predictions, discuss the hypothesis of a totally force-free magnetosphere. The discussed theories search for a confirmation in our gamma-ray observations, as the gamma-rays are the ones carrying away a good fraction of the rotational energy loss. THE NEW PERSPECTIVES OPENED BY THE MULTI-BAND OBSERVATIONS In April 2007 the Italian Space Agency launched the AGILE satellite for gamma-ray astronomy. About one year later, AGILE was joined in the observation of gammarays by the 16 times bigger Fermi-LAT satellite launched by NASA. AGILE and Fermi-LAT, with their wide field of view and large collective area, are particularly suited for the study of pulsars at high energies. Most recently, the window of veryhigh energy observations has opened up to pulsar studies and, in particular, by the MAGIC telescope, with the lowest up to now threshold for ground-based telescopes, at 25 GeV. Its observations are briefly described, together with AGILE and Fermi-LAT’s, in Chapter 2. The techniques for studying pulsars in the gamma-rays are also explained in Chapter 2, with the fundamental premise about the radio observations which were part of my analysis work, as they constitute the primary basis for the gammaray observations. The advances with respect to the observations of the previous generation gamma-ray instruments are highlighted. In particular, AGILE was able to take into account, for the first time in gamma-ray observations, the timing noise that affects young pulsars. In this way, the observations can be carried out for longer time spans without being affected by sensible light curve smearing. Thus, we could take advantage of the long time span, up to now the longest for gamma-ray observations, to increase the resolution of our light curves and see structures at the sub-millisecond level. GAMMA-RAY PULSARS AGILE and Fermi-LAT pulsar observations first concentrated on the known gamma-ray pulsars. As shown in Chapter 3, the apparently ”familiar” pulsars actually hid thriving new prospects for pulsar studies, as well as the new pulsars subsequently detected, described in Chapter 4. In these two Chapters, the properties of the gamma-ray emission ars analyzed for a number of pulsars, mainly using AGILE data, but also with Fermi-LAT and MAGIC observations. The light curves are investigated with increased resolution from previous observations and the spectral properties are addressed. The availability of a statistically significant sample of gamma-ray pulsars led us to draw some lines on the models. The classical polar cap model seems to be failing the test of gamma-ray observations for most of the present sample, and a simple explanation of which can be found in conservation laws arguments discussed in Chapter 4. At the same time it starts getting clear that a model that contemplates a single gap zone does not seem to be feasible to explain the observed pulse profiles. And, possibly, the entire gap theory should be combined with the more physical force-free models. Episodes of variability in pulsars have been observed and studied in this context. The Vela glitch of August 2007 was observed by AGILE in search for gamma-ray emission. The Crab pulsar could have a contribution to the emission from a newly observed third pulsar peak, that is less significant and much weaker than the canonical two, and could be due to giant pulses. AGILE observed the first gamma-ray millisecond pulsar but its emission only appeared in a restricted time interval, leading to the interesting possibility that pulsar emission might have some intrinsic variability. HIGH MAGNETIC FIELD PULSARS After the advent of Fermi-LAT, AGILE found its collocation in the gamma-ray astronomy in the characterization of the low-energy gamma-rays (from 30 to 100 MeV), where the collective areas of the two instruments is equivalent, but AGILE deals with much lower background. For this reason, we concentrated on those pulsars that show a low-energy cutoff, which were theorized to emit gamma-ray radiation through the exotic QED process of photon splitting. A detailed analysis of the two most significant cases is given in Chapter 5. We have found that the concurrence of a high magnetic field and an aligned geometry, could overcome the objections from Chapter 4 against inner magnetosphere emission and be, indeed, dominated by polar cap emission. Interestingly, this phenomenology, that is observed in pulsars that are similar to magnetars, may be observed in objects that are transitioning from pulsar to magnetar. THE ENVIRONMENT OF PULSARS Young pulsars are known to power a relativistic wind of particles that surrounds the pulsar and is best known as its Pulsar Wind Nebula (PWN). Important phenomena take place in the PWN and they are powered by the pulsar inside it. As discussed in Chapter 6, very high energy emission was already observed from PWN, but high energy emission was missing, in a spectral region where important constraints on the emission processes could be given. AGILE was the first satellite to detect GeV emission from a PWN apart from Crab, Vela X, and it was also the first to claim the unexpected flux variation in the Crab Nebula which underwent two intense flares in 2010 and 2011. In Chapter 6 we give a description of the events and a possible trail for an interpretation, although no clear picture can yet emerge from the observed events. CONCLUSIONS AND FUTURE PROSPECTS The multi-band approach that has been used for the observations described in this Thesis has proven valid for the exploitation of new science and the most useful approach for the comprehensive analysis of pulsar phenomena across the electromagnetic spectrum. As a completion to this work, the more comprehensive AGILE Pulsar Catalog is in preparation. It will comprise all the pulsars observed by AGILE and particularly focus on the low-energy tail of them, which present interesting properties that bridge pulsars and magnetars

Gamma-ray pulsars: a multi-band view

This Thesis is based mainly on the results of the timing analysis applied to the gamma-ray pulsars observed principally by the AGILE satellite and also extended, in some cases, to observations with the Fermi-LAT satellite and the MAGIC Cherenkov telescope. Aim of this extended study of pulsars at the high energies was to characterize their properties based, now, on a more statistically relevant sample, and be able to disentangle useful informations that can be key to explain the emission mechanisms in pulsars. THE SCIENTIFIC CONTEXT Pulsars are highly-magnetized, rapidly-rotating neutron stars. As explained in Chapter 1, they have been observed in the radio band over the past forty years, due to their highly anisotropic emission, which, when combined with the misalignment between the rotation and the magnetic axis, produces the pulsed emission we observed, also called the \u201dlighthouse effect\u201d. Pulsars have been observed as gamma-ray emitters as well, but it is only in the past three years that their number hit the double digits and they started to yield their potential as keys to explain the neutron stars mechanisms. In Chapter 1, the basics of pulsar theory are given. While the phenomenological aspects have been widely studied thanks to extensive radio observations through the years, their electrodynamics represents an articulated field that is difficult to probe. The \u201dclassical\u201d models of magnetosphere predict the presence of regions of particles\u2019 under-density (a \u201dgap\u201d), inside an overall force-free magnetized area that surrounds the pulsar, where the particles can be accelerated and can produce the observed radiation, after a number of cascade processes. More \u201dmodern\u201d models of magnetosphere, with their roots in old predictions, discuss the hypothesis of a totally force-free magnetosphere. The discussed theories search for a confirmation in our gamma-ray observations, as the gamma-rays are the ones carrying away a good fraction of the rotational energy loss. THE NEW PERSPECTIVES OPENED BY THE MULTI-BAND OBSERVATIONS In April 2007 the Italian Space Agency launched the AGILE satellite for gamma-ray astronomy. About one year later, AGILE was joined in the observation of gammarays by the 16 times bigger Fermi-LAT satellite launched by NASA. AGILE and Fermi-LAT, with their wide field of view and large collective area, are particularly suited for the study of pulsars at high energies. Most recently, the window of veryhigh energy observations has opened up to pulsar studies and, in particular, by the MAGIC telescope, with the lowest up to now threshold for ground-based telescopes, at 25 GeV. Its observations are briefly described, together with AGILE and Fermi-LAT\u2019s, in Chapter 2. The techniques for studying pulsars in the gamma-rays are also explained in Chapter 2, with the fundamental premise about the radio observations which were part of my analysis work, as they constitute the primary basis for the gammaray observations. The advances with respect to the observations of the previous generation gamma-ray instruments are highlighted. In particular, AGILE was able to take into account, for the first time in gamma-ray observations, the timing noise that affects young pulsars. In this way, the observations can be carried out for longer time spans without being affected by sensible light curve smearing. Thus, we could take advantage of the long time span, up to now the longest for gamma-ray observations, to increase the resolution of our light curves and see structures at the sub-millisecond level. GAMMA-RAY PULSARS AGILE and Fermi-LAT pulsar observations first concentrated on the known gamma-ray pulsars. As shown in Chapter 3, the apparently \u201dfamiliar\u201d pulsars actually hid thriving new prospects for pulsar studies, as well as the new pulsars subsequently detected, described in Chapter 4. In these two Chapters, the properties of the gamma-ray emission ars analyzed for a number of pulsars, mainly using AGILE data, but also with Fermi-LAT and MAGIC observations. The light curves are investigated with increased resolution from previous observations and the spectral properties are addressed. The availability of a statistically significant sample of gamma-ray pulsars led us to draw some lines on the models. The classical polar cap model seems to be failing the test of gamma-ray observations for most of the present sample, and a simple explanation of which can be found in conservation laws arguments discussed in Chapter 4. At the same time it starts getting clear that a model that contemplates a single gap zone does not seem to be feasible to explain the observed pulse profiles. And, possibly, the entire gap theory should be combined with the more physical force-free models. Episodes of variability in pulsars have been observed and studied in this context. The Vela glitch of August 2007 was observed by AGILE in search for gamma-ray emission. The Crab pulsar could have a contribution to the emission from a newly observed third pulsar peak, that is less significant and much weaker than the canonical two, and could be due to giant pulses. AGILE observed the first gamma-ray millisecond pulsar but its emission only appeared in a restricted time interval, leading to the interesting possibility that pulsar emission might have some intrinsic variability. HIGH MAGNETIC FIELD PULSARS After the advent of Fermi-LAT, AGILE found its collocation in the gamma-ray astronomy in the characterization of the low-energy gamma-rays (from 30 to 100 MeV), where the collective areas of the two instruments is equivalent, but AGILE deals with much lower background. For this reason, we concentrated on those pulsars that show a low-energy cutoff, which were theorized to emit gamma-ray radiation through the exotic QED process of photon splitting. A detailed analysis of the two most significant cases is given in Chapter 5. We have found that the concurrence of a high magnetic field and an aligned geometry, could overcome the objections from Chapter 4 against inner magnetosphere emission and be, indeed, dominated by polar cap emission. Interestingly, this phenomenology, that is observed in pulsars that are similar to magnetars, may be observed in objects that are transitioning from pulsar to magnetar. THE ENVIRONMENT OF PULSARS Young pulsars are known to power a relativistic wind of particles that surrounds the pulsar and is best known as its Pulsar Wind Nebula (PWN). Important phenomena take place in the PWN and they are powered by the pulsar inside it. As discussed in Chapter 6, very high energy emission was already observed from PWN, but high energy emission was missing, in a spectral region where important constraints on the emission processes could be given. AGILE was the first satellite to detect GeV emission from a PWN apart from Crab, Vela X, and it was also the first to claim the unexpected flux variation in the Crab Nebula which underwent two intense flares in 2010 and 2011. In Chapter 6 we give a description of the events and a possible trail for an interpretation, although no clear picture can yet emerge from the observed events. CONCLUSIONS AND FUTURE PROSPECTS The multi-band approach that has been used for the observations described in this Thesis has proven valid for the exploitation of new science and the most useful approach for the comprehensive analysis of pulsar phenomena across the electromagnetic spectrum. As a completion to this work, the more comprehensive AGILE Pulsar Catalog is in preparation. It will comprise all the pulsars observed by AGILE and particularly focus on the low-energy tail of them, which present interesting properties that bridge pulsars and magnetars

Contractual autonomy and new green economy

No abstract availabl