marco barbieri - Academia.edu (original) (raw)

Papers by marco barbieri

Biological Journal of The Linnean Society, 1995

The taxonomie status of different morphotypes generally ascribed to the species of boring sponge ... more The taxonomie status of different morphotypes generally ascribed to the species of boring sponge Cliona viridis is examined. Morphometric, ecological and genetic differences between two morphotypes living sympatrically on rocky shores of the Ligurian Sea are considered. Morphotype 1 is characterized by small, well separated papillae (α stage), exclusively boring into the crust of coralline algae on the exposed rocky bottoms of the upper sublittoral zone. Morphotype 2 shows bigger papillae, often connected by portions of encrusting tissue (β stage), and is predominantly found boring into organogenic concretions in slightly lighted habitats. Measurements of tylostyles indicate that morphotype 1 has spicules significantly smaller than morphotype 2. Electrophoretic analysis shows that the two morphotypes are fixed for different alleles at all four loci scored, indicating absence of gene flow between the two populations, i.e. they appear to be distinct biological species.

Polar Biology, 1992

The biogeography of Antarctic demosponges has been studied by dividing Antarctic and circumantarc... more The biogeography of Antarctic demosponges has been studied by dividing Antarctic and circumantarctic areas into geographic entities, and then assigning to these entities all recorded species according to literature reports. Correspondence analysis ordination based on the presence or absence of species shows the existence of a distinct Antarctic Faunistic Complex (AFC), including continental Antarctica, most of the Antarctic and circumantarctic islands and the Magellan area. Such a result has enabled us to drawup a checklist of 352 Antarctic demosponge species. Investigation of within-AFC patterns indicates that the continent is a highly homogeneous area, establishing closer relationships with the Scotia Arc and to a lesser extent with the Magellan region. The AFC has low specific affinities with the other circumantarctic regions (South Africa, temperate Australia and New Zealand), whereas at the generic level relationships appear more pronounced. This biogeographic pattern may lead us to suppose a common Gondwanian origin for Antarctic and circumantarctic sponge faunas, followed by differentiation due to Gondwana fragmentation. Antarctica moved towards polar latitudes and became progressively isolated, only maintaining active interchanges with South America. Climatic changes possibly induced intense processes of speciation in the Antarctic demosponge fauna, thus contributing to its differentiation.

Physical Review Letters, 2007

Shor's powerful quantum algorithm for factoring represents a major challenge in quantum computati... more Shor's powerful quantum algorithm for factoring represents a major challenge in quantum computation. Here, we implement a compiled version in a photonic system. For the first time, we demonstrate the core processes, coherent control, and resultant entangled states required in a full-scale implementation. These are necessary steps on the path towards scalable quantum computing. Our results highlight that the algorithm performance is not the same as that of the underlying quantum circuit and stress the importance of developing techniques for characterizing quantum algorithms.

Nature Chemistry, 2010

The fundamental problem faced in quantum chemistry is the calculation of molecular properties, wh... more The fundamental problem faced in quantum chemistry is the calculation of molecular properties, which are of practical importance in fields ranging from materials science to biochemistry. Within chemical precision, the total energy of a molecule as well as most other properties, can be calculated by solving the Schrodinger equation. However, the computational resources required to obtain exact solutions on a conventional computer generally increase exponentially with the number of atoms involved. This renders such calculations intractable for all but the smallest of systems. Recently, an efficient algorithm has been proposed enabling a quantum computer to overcome this problem by achieving only a polynomial resource scaling with system size. Such a tool would therefore provide an extremely powerful tool for new science and technology. Here we present a photonic implementation for the smallest problem: obtaining the energies of H2, the hydrogen molecule in a minimal basis. We perform a key algorithmic step - the iterative phase estimation algorithm - in full, achieving a high level of precision and robustness to error. We implement other algorithmic steps with assistance from a classical computer and explain how this non-scalable approach could be avoided. Finally, we provide new theoretical results which lay the foundations for the next generation of simulation experiments using quantum computers. We have made early experimental progress towards the long-term goal of exploiting quantum information to speed up quantum chemistry calculations.

Otology & Neurotology, 2002

Clinical study of the keyhole acoustic neuroma retrosigmoid approach for facial nerve and hearing... more Clinical study of the keyhole acoustic neuroma retrosigmoid approach for facial nerve and hearing preservation. This was a prospective case review from October 1993 to December 1998 in a referral hospital care unit. A total of 119 consecutive patients with a tumor size of <25 mm in the cerebellopontine angle corrected by a retrosigmoid approach were included in the study. Standard audiometric and imaging assessments, complete tumor removal by using endoscopy-assisted control, and nerve monitoring. House-Brackmann facial nerve grade and hearing level by the American Academy of Otolaryngology-Head and Neck Surgery classification. Grades I and II facial nerve function was obtained in 96% of cases, measurable hearing was preserved in 49% of cases, and 30% of cases achieved serviceable hearing. The retrosigmoid approach is a safe and reliable approach in random patients with small and medium-sized acoustic neuromas.

International Congress Series, 2003

We examined the sera of patients with Ménière's disease for the presence of antibodies against ei... more We examined the sera of patients with Ménière's disease for the presence of antibodies against eight inner ear antigens by enzyme-linked immunosorbent assay (ELISA). One hundred eight patients with Ménière's disease and 28 control subjects were studied. The antibodies against chicken type II collagen, bovine type 11 collagen, the cyanogen bromide cleaved peptide 11 (CB11) of each, types IX and XI collagens, C-Raf-1, and h-tubulin were measured by ELISA. The sensitivity of each antigen was 37% and 60% individually and was 91% when all eight inner ear antigens were combined. These results showed that 91% of Ménière's disease sera have antibody activities to one or more of these inner ear antigens. The results suggest that performing ELISA for these eight inner ear antigens was useful as a diagnostic tool for Ménière's disease. Further study is required to elucidate the role of these antigens in the pathogenesis of Ménière's disease, which might eventually result in better therapy.

Value in Health, 2009

There is an increasing number of health-care systems using economic evaluations to inform decisio... more There is an increasing number of health-care systems using economic evaluations to inform decisions about the reimbursement of health technologies. There are usually two separate elements of this process: assembling relevant evidence and undertaking analyses (technology assessment), and decision-making. In most systems, technology assessment is undertaken by the manufacturer of the technology. In a few, "third-party" assessment is used. Methods: In the United Kingdom, the National Institute for Health and Clinical Excellence used a combination of third-party and manufacturer assessments between 1999 and 2005. After this point, a Single Technology Appraisal program (using manufacturer-based assessment) was instituted for some technologies. Here the role of third-party assessment is considered in this from of decision-making. The article reviews the requirements of economic evaluation to support decision-making, and considers the extent to which each type of assessment is likely to meet these requirements. It also attempts to address whether the two forms of assessment differ in their impact on decision-making using a comparison of the decisions made by National Institute for Health and Clinical Excellence (NICE) (under its multiple-technology appraisal system) and the Scottish Medicines Consortium (SMC), which relies on manufacturer assessment. Results: The comparison is limited by the small number of technologies considered by both bodies. Nevertheless, it suggests that there are potentially important differences between the two bodies, with NICE generally placing more restrictions of the use of technologies. Conclusions: The article concludes that there are potential advantages to third-party assessment, but its cost and timing may preclude its use for all new technologies. A hybrid arrangement is suggested where third-party assessment is used in particular circumstances.

Pharmacoeconomics, 2005

To estimate the cost effectiveness (from the UK NHS and personal social service perspectives) of ... more To estimate the cost effectiveness (from the UK NHS and personal social service perspectives) of infliximab plus methotrexate (MTX) compared with MTX alone, in the treatment of patients with severe rheumatoid arthritis (RA) who were not adequately controlled on disease-modifying antirheumatic drugs and who were resistant to MTX. Clinical data for the first year of therapy were taken from the ATTRACT (Anti-Tumour Necrosis Factor Trial in Rheumatoid Arthritis with Concomitant Therapy) and a Markov model developed to assess costs and consequences in the longer term. Transition probabilities and health state valuations for the model were estimated based on the ARAMIS (Arthritis, Rheumatism, and Aging Medical Information System) cohort, and resource use and costs ( 2,000 pounds values) obtained from various sources in the UK. Univariate sensitivity analyses were conducted to test the robustness of the results. The primary analysis suggested that infliximab plus MTX had an ICER of 33,618 pounds per QALY gained. Alternative modelling assumptions and various other sensitivity analyses were applied, but the ICER always remained within the range for interventions typically funded by the NHS. This model suggests, with its underlying assumptions and data, that the combination of infliximab and MTX may be a cost-effective treatment (from the UK NHS and personal social service perspectives) for patients experiencing RA that cannot be maintained on MTX alone.

Value in Health, 2009

Citation: Drummond M, Barbieri M, Cook J, et al. Transferability of economic evaluations across j... more Citation: Drummond M, Barbieri M, Cook J, et al. Transferability of economic evaluations across jurisdictions: ISPOR good research practices task force report.

Value in Health, 2003

Objectives: Despite the growing number of pharmacoeconomic (PE)/health economic (HE) studies, ver... more Objectives: Despite the growing number of pharmacoeconomic (PE)/health economic (HE) studies, very little is known about their use by decision makers. The objectives of the Task Force were to ensure that the good research practices of PE/HE studies pay attention to the needs of health-care decision makers and to develop a "toolbox" for the health-care decision maker wanting to interpret and use PE/HE studies. Methods: The membership of the Task Force consisted of individuals involved in making decisions about the availability or use of medicines and researchers into the use of economic evaluations. The group communicated by Email and face-to-face meetings. A literature review of decision makers' attitudes toward PE/HE studies and published economic evaluation guidelines was undertaken. In addition, a focus group discussion was held with opinion leaders in managed care pharmacy.

Value in Health, 2005

It has long been suggested that, whereas the results of clinical studies of pharmaceuticals are g... more It has long been suggested that, whereas the results of clinical studies of pharmaceuticals are generalizable from one jurisdiction to another, the results of economic evaluations are location dependent. There has been, however, little study of the causes of variation, whether differences in study results among countries are systematic, or whether they are important for decision making.A literature search was conducted to identify economic evaluations of pharmaceuticals conducted in two or more European countries. The studies identified were then classified by methodological type and analyzed to assess their level of variability and to identify the main causes of variation. Assessments were also made of the extent to which differences in study results among countries were systematic and whether they would lead to a different decision, assuming a range of values of the threshold willingness-to-pay for a life-year or quality-adjusted life-year (QALY).In total 46 intercountry drug comparisons were identified, 29 in multicountry studies and 17 in comparable single country studies that were considered to be sufficiently similar in terms of methodology. The type of study (i.e., trial-based or modeling study) had some impact on variability, but the most important factor was the extent of variation across countries in effectiveness, resource use or unit costs, allowed by the researcher's chosen methodology. There were few systematic differences in study results among countries, so a decision maker in country B, on seeing a recent economic evaluation of a new drug in country A, would have little basis on which to predict whether the drug, if evaluated, would be more or less cost-effective in his or her country. Given the extent of variation in cost-effectiveness estimates among countries, the importance of this for decision making depends on decision makers' thresholds in willingness-to-pay for a QALY or life-year. If a cost-effectiveness threshold (i.e., willingness-to-pay) for a life-year or QALY of $50,000 were assumed, the same conclusion regarding cost-effectiveness would be reached in most cases.This review shows that cost-effectiveness results for pharmaceuticals vary from country to country in Western Europe and that these variations are not systematic. In addition, constraints imposed by analysts may reduce apparent variability in the estimates. The lessons for inferring generalizability are not straightforward, although the implications of variation for decision making depend critically on the cost-effectiveness thresholds applying in Western Europe.

Biological Journal of The Linnean Society, 1995

The taxonomie status of different morphotypes generally ascribed to the species of boring sponge ... more The taxonomie status of different morphotypes generally ascribed to the species of boring sponge Cliona viridis is examined. Morphometric, ecological and genetic differences between two morphotypes living sympatrically on rocky shores of the Ligurian Sea are considered. Morphotype 1 is characterized by small, well separated papillae (α stage), exclusively boring into the crust of coralline algae on the exposed rocky bottoms of the upper sublittoral zone. Morphotype 2 shows bigger papillae, often connected by portions of encrusting tissue (β stage), and is predominantly found boring into organogenic concretions in slightly lighted habitats. Measurements of tylostyles indicate that morphotype 1 has spicules significantly smaller than morphotype 2. Electrophoretic analysis shows that the two morphotypes are fixed for different alleles at all four loci scored, indicating absence of gene flow between the two populations, i.e. they appear to be distinct biological species.

Polar Biology, 1992

The biogeography of Antarctic demosponges has been studied by dividing Antarctic and circumantarc... more The biogeography of Antarctic demosponges has been studied by dividing Antarctic and circumantarctic areas into geographic entities, and then assigning to these entities all recorded species according to literature reports. Correspondence analysis ordination based on the presence or absence of species shows the existence of a distinct Antarctic Faunistic Complex (AFC), including continental Antarctica, most of the Antarctic and circumantarctic islands and the Magellan area. Such a result has enabled us to drawup a checklist of 352 Antarctic demosponge species. Investigation of within-AFC patterns indicates that the continent is a highly homogeneous area, establishing closer relationships with the Scotia Arc and to a lesser extent with the Magellan region. The AFC has low specific affinities with the other circumantarctic regions (South Africa, temperate Australia and New Zealand), whereas at the generic level relationships appear more pronounced. This biogeographic pattern may lead us to suppose a common Gondwanian origin for Antarctic and circumantarctic sponge faunas, followed by differentiation due to Gondwana fragmentation. Antarctica moved towards polar latitudes and became progressively isolated, only maintaining active interchanges with South America. Climatic changes possibly induced intense processes of speciation in the Antarctic demosponge fauna, thus contributing to its differentiation.

Physical Review Letters, 2007

Shor's powerful quantum algorithm for factoring represents a major challenge in quantum computati... more Shor's powerful quantum algorithm for factoring represents a major challenge in quantum computation. Here, we implement a compiled version in a photonic system. For the first time, we demonstrate the core processes, coherent control, and resultant entangled states required in a full-scale implementation. These are necessary steps on the path towards scalable quantum computing. Our results highlight that the algorithm performance is not the same as that of the underlying quantum circuit and stress the importance of developing techniques for characterizing quantum algorithms.

Nature Chemistry, 2010

The fundamental problem faced in quantum chemistry is the calculation of molecular properties, wh... more The fundamental problem faced in quantum chemistry is the calculation of molecular properties, which are of practical importance in fields ranging from materials science to biochemistry. Within chemical precision, the total energy of a molecule as well as most other properties, can be calculated by solving the Schrodinger equation. However, the computational resources required to obtain exact solutions on a conventional computer generally increase exponentially with the number of atoms involved. This renders such calculations intractable for all but the smallest of systems. Recently, an efficient algorithm has been proposed enabling a quantum computer to overcome this problem by achieving only a polynomial resource scaling with system size. Such a tool would therefore provide an extremely powerful tool for new science and technology. Here we present a photonic implementation for the smallest problem: obtaining the energies of H2, the hydrogen molecule in a minimal basis. We perform a key algorithmic step - the iterative phase estimation algorithm - in full, achieving a high level of precision and robustness to error. We implement other algorithmic steps with assistance from a classical computer and explain how this non-scalable approach could be avoided. Finally, we provide new theoretical results which lay the foundations for the next generation of simulation experiments using quantum computers. We have made early experimental progress towards the long-term goal of exploiting quantum information to speed up quantum chemistry calculations.

Otology & Neurotology, 2002

Clinical study of the keyhole acoustic neuroma retrosigmoid approach for facial nerve and hearing... more Clinical study of the keyhole acoustic neuroma retrosigmoid approach for facial nerve and hearing preservation. This was a prospective case review from October 1993 to December 1998 in a referral hospital care unit. A total of 119 consecutive patients with a tumor size of <25 mm in the cerebellopontine angle corrected by a retrosigmoid approach were included in the study. Standard audiometric and imaging assessments, complete tumor removal by using endoscopy-assisted control, and nerve monitoring. House-Brackmann facial nerve grade and hearing level by the American Academy of Otolaryngology-Head and Neck Surgery classification. Grades I and II facial nerve function was obtained in 96% of cases, measurable hearing was preserved in 49% of cases, and 30% of cases achieved serviceable hearing. The retrosigmoid approach is a safe and reliable approach in random patients with small and medium-sized acoustic neuromas.

International Congress Series, 2003

We examined the sera of patients with Ménière's disease for the presence of antibodies against ei... more We examined the sera of patients with Ménière's disease for the presence of antibodies against eight inner ear antigens by enzyme-linked immunosorbent assay (ELISA). One hundred eight patients with Ménière's disease and 28 control subjects were studied. The antibodies against chicken type II collagen, bovine type 11 collagen, the cyanogen bromide cleaved peptide 11 (CB11) of each, types IX and XI collagens, C-Raf-1, and h-tubulin were measured by ELISA. The sensitivity of each antigen was 37% and 60% individually and was 91% when all eight inner ear antigens were combined. These results showed that 91% of Ménière's disease sera have antibody activities to one or more of these inner ear antigens. The results suggest that performing ELISA for these eight inner ear antigens was useful as a diagnostic tool for Ménière's disease. Further study is required to elucidate the role of these antigens in the pathogenesis of Ménière's disease, which might eventually result in better therapy.

Value in Health, 2009

There is an increasing number of health-care systems using economic evaluations to inform decisio... more There is an increasing number of health-care systems using economic evaluations to inform decisions about the reimbursement of health technologies. There are usually two separate elements of this process: assembling relevant evidence and undertaking analyses (technology assessment), and decision-making. In most systems, technology assessment is undertaken by the manufacturer of the technology. In a few, "third-party" assessment is used. Methods: In the United Kingdom, the National Institute for Health and Clinical Excellence used a combination of third-party and manufacturer assessments between 1999 and 2005. After this point, a Single Technology Appraisal program (using manufacturer-based assessment) was instituted for some technologies. Here the role of third-party assessment is considered in this from of decision-making. The article reviews the requirements of economic evaluation to support decision-making, and considers the extent to which each type of assessment is likely to meet these requirements. It also attempts to address whether the two forms of assessment differ in their impact on decision-making using a comparison of the decisions made by National Institute for Health and Clinical Excellence (NICE) (under its multiple-technology appraisal system) and the Scottish Medicines Consortium (SMC), which relies on manufacturer assessment. Results: The comparison is limited by the small number of technologies considered by both bodies. Nevertheless, it suggests that there are potentially important differences between the two bodies, with NICE generally placing more restrictions of the use of technologies. Conclusions: The article concludes that there are potential advantages to third-party assessment, but its cost and timing may preclude its use for all new technologies. A hybrid arrangement is suggested where third-party assessment is used in particular circumstances.

Pharmacoeconomics, 2005

To estimate the cost effectiveness (from the UK NHS and personal social service perspectives) of ... more To estimate the cost effectiveness (from the UK NHS and personal social service perspectives) of infliximab plus methotrexate (MTX) compared with MTX alone, in the treatment of patients with severe rheumatoid arthritis (RA) who were not adequately controlled on disease-modifying antirheumatic drugs and who were resistant to MTX. Clinical data for the first year of therapy were taken from the ATTRACT (Anti-Tumour Necrosis Factor Trial in Rheumatoid Arthritis with Concomitant Therapy) and a Markov model developed to assess costs and consequences in the longer term. Transition probabilities and health state valuations for the model were estimated based on the ARAMIS (Arthritis, Rheumatism, and Aging Medical Information System) cohort, and resource use and costs ( 2,000 pounds values) obtained from various sources in the UK. Univariate sensitivity analyses were conducted to test the robustness of the results. The primary analysis suggested that infliximab plus MTX had an ICER of 33,618 pounds per QALY gained. Alternative modelling assumptions and various other sensitivity analyses were applied, but the ICER always remained within the range for interventions typically funded by the NHS. This model suggests, with its underlying assumptions and data, that the combination of infliximab and MTX may be a cost-effective treatment (from the UK NHS and personal social service perspectives) for patients experiencing RA that cannot be maintained on MTX alone.

Value in Health, 2009

Citation: Drummond M, Barbieri M, Cook J, et al. Transferability of economic evaluations across j... more Citation: Drummond M, Barbieri M, Cook J, et al. Transferability of economic evaluations across jurisdictions: ISPOR good research practices task force report.

Value in Health, 2003

Objectives: Despite the growing number of pharmacoeconomic (PE)/health economic (HE) studies, ver... more Objectives: Despite the growing number of pharmacoeconomic (PE)/health economic (HE) studies, very little is known about their use by decision makers. The objectives of the Task Force were to ensure that the good research practices of PE/HE studies pay attention to the needs of health-care decision makers and to develop a "toolbox" for the health-care decision maker wanting to interpret and use PE/HE studies. Methods: The membership of the Task Force consisted of individuals involved in making decisions about the availability or use of medicines and researchers into the use of economic evaluations. The group communicated by Email and face-to-face meetings. A literature review of decision makers' attitudes toward PE/HE studies and published economic evaluation guidelines was undertaken. In addition, a focus group discussion was held with opinion leaders in managed care pharmacy.

Value in Health, 2005

It has long been suggested that, whereas the results of clinical studies of pharmaceuticals are g... more It has long been suggested that, whereas the results of clinical studies of pharmaceuticals are generalizable from one jurisdiction to another, the results of economic evaluations are location dependent. There has been, however, little study of the causes of variation, whether differences in study results among countries are systematic, or whether they are important for decision making.A literature search was conducted to identify economic evaluations of pharmaceuticals conducted in two or more European countries. The studies identified were then classified by methodological type and analyzed to assess their level of variability and to identify the main causes of variation. Assessments were also made of the extent to which differences in study results among countries were systematic and whether they would lead to a different decision, assuming a range of values of the threshold willingness-to-pay for a life-year or quality-adjusted life-year (QALY).In total 46 intercountry drug comparisons were identified, 29 in multicountry studies and 17 in comparable single country studies that were considered to be sufficiently similar in terms of methodology. The type of study (i.e., trial-based or modeling study) had some impact on variability, but the most important factor was the extent of variation across countries in effectiveness, resource use or unit costs, allowed by the researcher's chosen methodology. There were few systematic differences in study results among countries, so a decision maker in country B, on seeing a recent economic evaluation of a new drug in country A, would have little basis on which to predict whether the drug, if evaluated, would be more or less cost-effective in his or her country. Given the extent of variation in cost-effectiveness estimates among countries, the importance of this for decision making depends on decision makers' thresholds in willingness-to-pay for a QALY or life-year. If a cost-effectiveness threshold (i.e., willingness-to-pay) for a life-year or QALY of $50,000 were assumed, the same conclusion regarding cost-effectiveness would be reached in most cases.This review shows that cost-effectiveness results for pharmaceuticals vary from country to country in Western Europe and that these variations are not systematic. In addition, constraints imposed by analysts may reduce apparent variability in the estimates. The lessons for inferring generalizability are not straightforward, although the implications of variation for decision making depend critically on the cost-effectiveness thresholds applying in Western Europe.