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Biomedical subjects

C Carbone

Publications and source records attributed to C Carbone.

At least 19 recordsLinked to original sources
PubMed2006

Probing quasiparticle states bound by disparate periodic potentials.

Thin films of Ag(111) with two-dimensional crystallinity of large lateral coherence grow on Ge(111), free of in-plane registry with the underlying substrate. Ag s-p electrons forming two-dimensional quantum well states scatter coherently at the buried interface potential, resulting in an unexpected set of new quasiparticle states, as observed by angle-resolved photoemission. These new features originate from interactions among Ag quantum well bands, gaining a momentum equivalent to a reciprocal vector of the substrate lattice.

Journal Article↗
PubMed2006

Quasicrystalline electronic states of a one-dimensionally modulated Ag film.

Ag films on GaAs(110) exhibit a one-dimensional quasiperiodic modulation, resulting in a Fibonacci sequence of parallel stripes with two different widths. Valence level photoemission shows that the Ag electronic states acquire a unique character along the quasiperiodic direction, distinctively manifested by a hierarchy of energy level replicas and avoided crossings at characteristic intervals in reciprocal space. These observations demonstrate the strong influence of the one-dimensional quasiperiodic potential on the Ag film states.

Journal Article↗
PubMed2005

Probing the ground state electronic structure of a correlated electron system by quantum well states: Ag/Ni(111).

The ground state electronic properties of the strongly correlated transition metal Ni are usually not accessible from the excitation spectra measured in photoelectron spectroscopy. We show that the bottom of the Ni d band along [111] can be probed through the energy dependence of the phase of quantum-well states in Ag/Ni(111). Our model description of the quantum-well energies measured by angle-resolved photoemission determines the bottom of the empty set 1 d band of Ni as 2.6 eV, in full agreement with standard local density theory and at variance with the values of 1.7-1.8 eV from direct angle-resolved photoemission experiments of Ni.

Journal Article↗
PubMed2005

Spin-flop ordering from frustrated ferro- and antiferromagnetic interactions: a combined theoretical and experimental study of a Mn/Fe(100) monolayer.

The occurrence of a noncollinear magnetic structure at a Mn monolayer grown epitaxially on Fe(100) is predicted theoretically, using spinor density-functional theory, and observed experimentally, using x-ray magnetic circular dichroism (XMCD) and linear dichroism (XMLD) spectroscopies. The combined use of XMCD and XMLD at the Mn-absorption edge allows us to assess the existence of ferromagnetic and antiferromagnetic order at the interface, and also to determine the moment orientations with element specificity. The experimental results thus obtained are in excellent agreement with the magnetic structure determined theoretically.

Journal Article↗
PubMed2004

Oscillatory magnetic anisotropy in one-dimensional atomic wires.

One-dimensional Co atomic wires grown on Pt(997) have been investigated by x-ray magnetic circular dichroism. Strong changes of the magnetic properties are observed as the system evolves from 1D- to 2D-like. The easy axis of magnetization, the magnetic anisotropy energy, and the coercive field oscillate as a function of the transverse width of the wires, in agreement with theoretical predictions for 1D metal systems.

Journal Article↗
PubMed2004

Placental growth hormone in Down's syndrome screening.

A number of serum markers have been proposed to improve the sensitivity (and specificity) of the triple test, which, until now, has been the gold standard in second-trimester serum screening for Down's syndrome. Among them, human placental growth hormone (hPGH) has been proposed because of its significantly elevated serum levels in pregnancies affected by chromosomal aneuploidies. Our experience, on maternal serum stored from 32 Down's syndrome-affected pregnancies, confirms a slight but significant increase in hPGH levels compared with controls. These data summarized to that of the previous screening could give a calculated detection rate of 71.9%, better than that of the standard triple test alone (65.6%).

Adult↗
PubMed2003

Giant magnetic anisotropy of single cobalt atoms and nanoparticles.

The isotropic magnetic moment of a free atom is shown to develop giant magnetic anisotropy energy due to symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum (111) are found to have a magnetic anisotropy energy of 9 millielectron volts per atom arising from the combination of unquenched orbital moments (1.1 Bohr magnetons) and strong spin-orbit coupling induced by the platinum substrate. By assembling cobalt nanoparticles containing up to 40 atoms, the magnetic anisotropy energy is further shown to be dependent on single-atom coordination changes. These results confirm theoretical predictions and are of fundamental value to understanding how magnetic anisotropy develops in finite-sized magnetic particles.

Journal Article↗
PubMed2002

Finite temperature magnetism in Gd: evidence against a Stoner behavior.

The temperature dependence of the rare-earth valence bands has been regarded as a realization of the Stoner behavior. The exchange splitting of the electronic states appears to scale as the magnetic order parameter for T<T(C) and to vanish at T = T(C). We report here a spin-resolved photoemission study on the evolution of Gd bulk bands for 0.5< or =T/T(C)< or=1. The spin-polarized spectral line shapes display a complex temperature dependence, which clearly contrasts with the interpretation of previous experimental results. The spin-resolved photoemission data demonstrate the inadequacy of the Stoner model to the description of magnetism in rare earths.

Journal Article↗
PubMed2002

Ferromagnetism in one-dimensional monatomic metal chains.

Two-dimensional systems, such as ultrathin epitaxial films and superlattices, display magnetic properties distinct from bulk materials. A challenging aim of current research in magnetism is to explore structures of still lower dimensionality. As the dimensionality of a physical system is reduced, magnetic ordering tends to decrease as fluctuations become relatively more important. Spin lattice models predict that an infinite one-dimensional linear chain with short-range magnetic interactions spontaneously breaks up into segments with different orientation of the magnetization, thereby prohibiting long-range ferromagnetic order at a finite temperature. These models, however, do not take into account kinetic barriers to reaching equilibrium or interactions with the substrates that support the one-dimensional nanostructures. Here we demonstrate the existence of both short- and long-range ferromagnetic order for one-dimensional monatomic chains of Co constructed on a Pt substrate. We find evidence that the monatomic chains consist of thermally fluctuating segments of ferromagnetically coupled atoms which, below a threshold temperature, evolve into a ferromagnetic long-range-ordered state owing to the presence of anisotropy barriers. The Co chains are characterized by large localized orbital moments and correspondingly large magnetic anisotropy energies compared to two-dimensional films and bulk Co.

Journal Article↗
PubMed2002

Localized magnetic states of Fe, Co, and Ni impurities on alkali metal films.

X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) have been used to study transition metal impurities on K and Na films. The multiplet structure of the XAS spectra indicates that Fe, Co, and Ni have localized atomic ground states with predominantly d7, d8, and d9 character, respectively. XMCD shows that the localized impurity states possess large, atomiclike, magnetic orbital moments that are progressively quenched as clusters are formed. Ni impurities on Na films are found to be nonmagnetic, with a strongly increased d10 character of the impurity state. The results show that the high magnetic moments of transition metals in alkali hosts originate from electron localization.

Journal Article↗
PubMed2002

[Integrated clinical record: unique document for diverse uses].

Technological and scientific development and changes in the health system have led to modifications and greater complexity in health documents and clinical records, without there being at the same time definition of guidelines on their correct compilation and formulation. The present study was designed to develop a single Integrated Clinical Record that combines, on the one hand, data of all medical, nursing and technical interventions and, on the other, involves the patient in all decisional processes of diagnosis and treatment during the hospitalization period. All phases of the project related to development of the Integrated Clinical Record are discussed. The data of 240 new clinical records regarding patients admitted consecutively over a period of 6 months are reported. The results show a progressive reduction of compilation errors and an improved management of the patient's clinical course. The innovative aspects of the new clinical record are discussed, with particular reference to the system of quality management, within which context the clinical record has to function, and to the modalities of check, audit and improvement.

Humans↗
PubMed2001

Electronic band structure of Gd: a consistent description.

The dispersion of the Gd (5d6s)-valence bands has been investigated by means of spin- and angle-resolved photoemission. The spin analysis of various spectral features shows that their weak dispersion and unusual broadening is due to the photoelectron lifetime rather than to correlation induced band narrowing as previously proposed. These results resolve a long-standing discrepancy between theoretical and experimental descriptions of the rare earth band structure.

Journal Article↗
PubMed2000

Mice vaccination with interleukin 12-transduced colon cancer cells potentiates rejection of syngeneic non-organ-related tumor cells.

Cell-based gene therapy after cytokine gene transfer is being investigated for autologous and allogeneic vaccination in cancer therapy. Here we show that mice vaccinated with 3-5 x 10(6) interleukin 12 (IL-12) gene-transduced CT26 colon cancer cells developed a long-lasting antitumor immune memory able to reject not only parental cells but also syngeneic, LM3 mammary, and MCE fibrosarcoma tumorigenic cells. In contrast, mice vaccinated with 0.5-1 x 10(6) CT26 cells transduced with pBabe neo IL-12 retrovirus cells (CT26-IL12) were only able to reject parental cells. An increase in the total circulating levels of IgG2a and a clear shift toward a systemic Th1 response developed, regardless of the amount of injected CT26-IL12 cells. On the contrary, a strong increase in anti-CT26-specific IgG2a levels was observed only when 3-5 x 10(6) CT26-IL12 cells were injected. Immunocompetent mice vaccinated with 3-5 x 10(6) CT26-IL12 cells developed local nodules for a few days, which then ceased growing. These nodules comprised mainly blood vessels, suggesting that an angiogenic process was taking place. CD8+ T cells were responsible for the anti-LM3 tumor cell memory, whereas CD4+ T cells were not involved. Splenocytes and lymphocytes obtained from mice immunized against CT26 cells were able to kill LM3 cells in vitro. Adoptive transfer of lymphocytes obtained from animals immunized against CT26 colon cancer cells suppressed LM3 mammary tumor growth in tumor-bearing mice. The present studies raised the possibility of isolating CTL clones and identifying CTL epitopes shared by different tumor cell types, which can be a target for cancer therapy.

Animals↗
PubMed2000

One-dimensional spin-polarized quantum-wire states in Au on Ni(110)

Au chain structures have been prepared on Ni(110). Au6 s,p-derived features in photoemission spectra are identified as quantum-wire states due to their strong dispersion along the chains and absence of dispersion perpendicular to the chains in agreement with our ab initio calculation of the electronic structure. Spin analysis reveals that the states have minority-spin character showing that the confinement of electrons in the chain structure depends on the electron spin.

Journal Article↗
PubMed2000

Expression of allograft inflammatory factor-1 is a marker of activated human vascular smooth muscle cells and arterial injury.

The cytokine-induced activation and proliferation of medial vascular smooth muscle cells (VSMCs) leading to intimal hyperplasia is one of the most critical cellular events in the formation of transplant arteriopathy and balloon angioplasty-induced restenosis. Allograft inflammatory factor-1 (AIF-1) is a calcium-binding protein that we have previously shown to be expressed in balloon angioplasty-injured rat carotid arteries. We hypothesized that AIF-1 expression may be associated with the VSMC response to injury. In this study, we examined AIF-1 expression in immunologic and mechanical models of arterial injury. Reverse transcription-polymerase chain reaction and Western analysis demonstrated that AIF-1 is acutely and transiently expressed in aortic medial smooth muscle cells of rat cardiac allografts, with mRNA and protein peaking at 3 to 7 days after transplant and declining by 10 days after transplant. Immunohistochemical analysis identified abundant AIF-1 in the medial VSMCs of these vessels. Immunohistochemical analysis of balloon angioplasty-injured swine coronary arteries also demonstrates an acute AIF-1 expression detectable by 24 hours and continuing up to 14 days after the procedure. AIF-1 in these vessels also localizes to the medial VSMCs and cells of the developing neointima. AIF-1 protein is not expressed in quiescent cultured human VSMCs but is induced in cells challenged with various inflammatory cytokines, primarily by interferon-gamma, interleukin-1beta, and T-cell-conditioned media. Transfection and overexpression of AIF-1 in human VSMCs result in enhanced growth of these cells. Taken together, these data indicate that AIF-1 expression is associated with vascular trauma and suggest that this protein may play a role in VSMC activation subsequent to arterial injury.

Amino Acid Sequence↗
PubMed1999

Energetic constraints on the diet of terrestrial carnivores.

Species in the mammalian order Carnivora exhibit a huge diversity of life histories with body sizes spanning more than three orders of magnitude. Despite this diversity, most terrestrial carnivores can be classified as either feeding on invertebrates and small vertebrates or on large vertebrates. Small carnivores feed predominantly on invertebrates probably because they are a superabundant resource (sometimes 90% of animal biomass); however, intake rates of invertebrate feeders are low, about one tenth of those of vertebrate feeders. Although small carnivores can subsist on this diet because of low absolute energy requirements, invertebrate feeding appears to be unsustainable for larger carnivores. Here we show, by reviewing the most common live prey in carnivore diets, that there is a striking transition from feeding on small prey (less than half of predator mass) to large prey (near predator mass), occurring at predator masses of 21.5-25 kg. We test the hypothesis that this dichotomy is the consequence of mass-related energetic requirements and we determine the predicted maximum mass that an invertebrate diet can sustain. Using a simple energetic model and known invertebrate intake rates, we predict a maximum sustainable mass of 21.5 kg, which matches the point where predators shift from small to large prey.

Animals↗