Molecular nanomagnets: a viable path toward quantum information processing?

Molecular nanomagnets (MNMs), molecules containing interacting spins, have been a playground for quantum mechanics. They are characterized by many accessible low-energy levels that can be exploited to store and process quantum information. This naturally opens the possibility of using them as qudits, thus enlarging the tools of quantum logic with respect to qubit-based architectures. These additional degrees of freedom recently prompted the proposal for encoding qubits with embedded quantum error correction (QEC) in single molecules. QEC is the holy grail of quantum computing and this qudit approach could circumvent the large overhead of physical qubits typical of standard multi-qubit codes. Another important strength of the molecular approach is the extremely high degree of control achieved in preparing complex supramolecular structures where individual qudits are linked preserving their individual properties and coherence. This is particularly relevant for building quantum simulators, controllable systems able to mimic the dynamics of other quantum objects. The use of MNMs for quantum information processing is a rapidly evolving field which still requires to be fully experimentally explored. The key issues to be settled are related to scaling up the number of qudits/qubits and their individual addressing. Several promising possibilities are being intensively explored, ranging from the use of single-molecule transistors or superconducting devices to optical readout techniques. Moreover, new tools from chemistry could be also at hand, like the chiral-induced spin selectivity. In this paper, we will review the present status of this interdisciplinary research field, discuss the open challenges and envisioned solution paths which could finally unleash the very large potential of molecular spins for quantum technologies.

The critical role of ultra-low-energy vibrations in the relaxation dynamics of molecular qubits

Improving the performance of molecular qubits is a fundamental milestone towards unleashing the power of molecular magnetism in the second quantum revolution. Taming spin relaxation and decoherence due to vibrations is crucial to reach this milestone, but this is hindered by our lack of understanding on the nature of vibrations and their coupling to spins. Here we propose a synergistic approach to study a prototypical molecular qubit. It combines inelastic X-ray scattering to measure phonon dispersions along the main symmetry directions of the crystal and spin dynamics simulations based on DFT. We show that the canonical Debye picture of lattice dynamics breaks down and that intra-molecular vibrations with very-low energies of 1-2 meV are largely responsible for spin relaxation up to ambient temperature. We identify the origin of these modes, thus providing a rationale for improving spin coherence. The power and flexibility of our approach open new avenues for the investigation of magnetic molecules with the potential of removing roadblocks toward their use in quantum devices.

Theoretical Design of Optimal Molecular Qudits for Quantum Error Correction

We pinpoint the key ingredients ruling decoherence in multispin clusters, and we engineer the system Hamiltonian to design optimal molecules embedding quantum error correction. These are antiferromagnetically coupled systems with competing exchange interactions, characterized by many low-energy states in which decoherence is dramatically suppressed and does not increase with the system size. This feature allows us to derive optimized code words, enhancing the power of the quantum error correction code by orders of magnitude. We demonstrate this by a complete simulation of the system dynamics, including the effect of decoherence driven by a nuclear spin bath and the full sequence of pulses to implement error correction and logical gates between protected states.

Assessing the Nature of Chiral-Induced Spin Selectivity by Magnetic Resonance

Understanding chiral-induced spin selectivity (CISS), resulting from charge transport through helical systems, has recently inspired many experimental and theoretical efforts but is still the object of intense debate. In order to assess the nature of CISS, we propose to focus on electron-transfer processes occurring at the single-molecule level. We design simple magnetic resonance experiments, exploiting a qubit as a highly sensitive and coherent magnetic sensor, to provide clear signatures of the acceptor polarization. Moreover, we show that information could even be obtained from time-resolved electron paramagnetic resonance experiments on a randomly oriented solution of molecules. The proposed experiments will unveil the role of chiral linkers in electron transfer and could also be exploited for quantum computing applications.

Erratum: Many-Body Models for Molecular Nanomagnets [Phys. Rev. Lett. 110, 157204 (2013)]

This corrects the article DOI: 10.1103/PhysRevLett.110.157204.

Molecular Nanomagnets as Qubits with Embedded Quantum-Error Correction

We show that molecular nanomagnets have a potential advantage in the crucial rush toward quantum computers. Indeed, the sizable number of accessible low-energy states of these systems can be exploited to define qubits with embedded quantum error correction. We derive the scheme to achieve this crucial objective and the corresponding sequence of microwave/radiofrequency pulses needed for the error correction procedure. The effectiveness of our approach is shown already with a minimal S = 3/2 unit corresponding to an existing molecule, and the scaling to larger spin systems is quantitatively analyzed.

Molecular Nanomagnets as Qubits with Embedded Quantum-Error Correction

We show that molecular nanomagnets have a potential advantage in the crucial rush toward quantum computers. Indeed, the sizable number of accessible low-energy states of these systems can be exploited to define qubits with embedded quantum error correction. We derive the scheme to achieve this crucial objective and the corresponding sequence of microwave/radiofrequency pulses needed for the error correction procedure. The effectiveness of our approach is shown already with a minimal S = 3/2 unit corresponding to an existing molecule, and the scaling to larger spin systems is quantitatively analyzed.

Unveiling phonons in a molecular qubit with four-dimensional inelastic neutron scattering and density functional theory

Phonons are the main source of relaxation in molecular nanomagnets, and different mechanisms have been proposed in order to explain the wealth of experimental findings. However, very limited experimental investigations on phonons in these systems have been performed so far, yielding no information about their dispersions. Here we exploit state-of-the-art single-crystal inelastic neutron scattering to directly measure for the first time phonon dispersions in a prototypical molecular qubit. Both acoustic and optical branches are detected in crystals of [VO(acac)[Formula: see text]] along different directions in the reciprocal space. Using energies and polarisation vectors calculated with state-of-the-art Density Functional Theory, we reproduce important qualitative features of [VO(acac)[Formula: see text]] phonon modes, such as the presence of low-lying optical branches. Moreover, we evidence phonon anti-crossings involving acoustic and optical branches, yielding significant transfers of the spin-phonon coupling strength between the different modes.

Results of EN Bloc Resections for Lung Cancer

The results of en bloc resection carried out in 33 patients with lung cancer involving the chest wall are described. Microscopic examination of the lung specimen revealed large cell anaplastic carcinoma in 14 cases, squamous carcinoma in 10, adenocarcinoma in 5, microcytoma and fibrosarcoma in 2 cases respectively. The 5 year survival, calculated according to the actuarial method, was 32 %, only slightly lower than the 5 year overall survival observed in our survey. The long-term prognosis was essentially related to the presence of lymphnodal metastases, which were found to occur at a late stage of the clinical evolution.

Sentinel Node Biopsy in Clinical Stage 1 Melanoma: Rationale for Restaging and Follow-Up

Lymph node involvement appears to be the most significant prognostic factor in patients affected by melanoma and has been shown to reduce the five-year survival by 40%. We studied 31 patients (15 M; 16 F; age range, 28–83 years) with clinical stage 1 (CS1) intermediate thickness (0.75–4 mm) melanoma. Scintigraphic examination of the nodes was performed in all patients, 29 of whom underwent surgical biopsy of the SN after 24 hours. Early images were acquired 5, 15 and 79 min and late images 60–180 min following perilesional injection of 2–4 microdoses of 99mTc-nanocolloid (15–20 MBq). A cobalt marker was used to project the SN on the skin surface which was later stained with indelible ink. For intraoperative localization we used a portable probe and perilesional injection of patent blue violet dye, which proved positive in 24/29 patients (83%). After surgery histological examination of the sentinel lymph nodes (SNs) (hematoxylin-eosin and immunohistochemistry) found positivity for metastatic cells in 6 patients. They all underwent elective lymph node dissection (ELND); five are N0+ and are currently undergoing supportive therapy with interferon alpha with an 8–24-month follow-up, while one N+ patient died 14 months after surgery. Follow-up (3–26 months) of NO- patients has not evidenced any locoregional recurrence so far. Only one case showed hematogenic metastases. This procedure might radically change the therapeutic approach to CS1 melanoma because it is simple, scarcely invasive, and shows a favorable cost-benefit ratio.

Use of low-dose radioiodine ablation for Graves' orbitopathy: results of a pilot, perspective study in a small series of patients

OBJECTIVE

Elimination of thyroid antigens by total thyroid ablation (TTA), namely, thyroidectomy followed by radioiodine, may be beneficial for Graves' Orbitopathy (GO). TTA is usually performed with a ¹³¹I dose of 30 mCi. In Italy, this dose must be followed by a 24-h protected hospitalization, with increase in the waiting lists. In contrast, a 15 mCi dose can be given without hospitalization and with lower costs. Here, we investigated whether a lower dose of radioiodine can be used to ablate thyroid remnants in patients with GO, after thyroidectomy.

METHODS

The study was performed in two small groups of consecutive thyroidectomized patients (six patients per group) with Graves' hyperthyroidism and GO. Patients underwent ablation with either 15 or 30 mCi of ¹³¹I following treatment with recombinant human TSH (rhTSH). The primary outcome was rhTSH-stimulated serum thyroglobulin (Tg) at 6 months. The secondary outcome was baseline Tg at 6 months.

RESULTS

Baseline Tg and rhTSH-stimulated Tg after at 6 months did not differ between two groups, suggesting a similar extent of ablation. rhTSH-stimulated Tg was reduced significantly compared with rhTSH-stimulated Tg at ablation in both groups. GO outcome following treatment with intravenous glucocorticoids did not differ between the two groups.

CONCLUSIONS

Our findings may provide a preliminary basis for the use of a 15 mCi dose of radioiodine upon rhTSH stimulation in thyroidectomized patients with Graves' hyperthyroidism and GO.

Magnetic Exchange Interactions in the Molecular Nanomagnet Mn_{12}

The discovery of magnetic bistability in Mn_{12} more than 20 years ago marked the birth of molecular magnetism, an extremely fertile interdisciplinary field and a powerful route to create tailored magnetic nanostructures. However, the difficulty to determine interactions in complex polycentric molecules often prevents their understanding. Mn_{12} is an outstanding example of this difficulty: although it is the forefather and most studied of all molecular nanomagnets, an unambiguous determination of even the leading magnetic exchange interactions is still lacking. Here we exploit four-dimensional inelastic neutron scattering to portray how individual spins fluctuate around the magnetic ground state, thus fixing the exchange couplings of Mn_{12} for the first time. Our results demonstrate the power of four-dimensional inelastic neutron scattering as an unrivaled tool to characterize magnetic clusters.

Thyroglobulin autoantibodies switch to immunoglobulin (Ig)G1 and IgG3 subclasses and preserve their restricted epitope pattern after 131I treatment for Graves' hyperthyroidism: the activity of autoimmune disease influences subclass distribution but not epitope pattern of autoantibodies

The subclass distribution of thyroglobulin autoantibodies (TgAb) is debated, whereas their epitope pattern is restricted. Radioidine ((131)I) treatment for Graves' disease (GD) induces a rise in TgAb levels, but it is unknown whether it modifies subclass distribution and epitope pattern of TgAb as well. We collected sera from GD patients before (131) I treatment and 3 and 6 months thereafter. We measured total TgAb, TgAb light chains and TgAb subclasses by enzyme-linked immunosorbent assay (ELISA) in 25 patients. We characterized the TgAb epitope pattern in 30 patients by inhibiting their binding to (125-) (I) Tg by a pool of four TgAb-Fab (recognizing Tg epitope regions A, B, C and D) and to Tg in ELISA by each TgAb-Fab. Total TgAb immunoglobulin (Ig)G rose significantly (P = 0.024). TgAb κ chains did not change (P = 0.052), whereas TgAb λ chains increased significantly (P = 0.001) and persistently. We observed a significant rise in IgG1 and IgG3 levels after (131)I (P = 0.008 and P = 0.006, respectively), while IgG2 and IgG4 levels did not change. The rise of IgG1 was persistent, that of IgG3 transient. The levels of inhibition of TgAb binding to Tg by the TgAb-Fab pool were comparable. A slight, non-significant reduction of the inhibition by the immune-dominant TgAb-Fab A was observed 3 and 6 months after (131)I. We conclude that (131)I treatment for GD increases the levels of the complement-activating IgG1 and IgG3 subclasses and does not influence significantly the epitope pattern of TgAb. In autoimmune thyroid disease subclass distribution of autoantibodies is dynamic in spite of a stable epitope pattern.

Detection of metastases from differentiated thyroid cancer by different imaging techniques (neck ultrasound, computed tomography and [18F]-FDG positron emission tomography) in patients with negative post-therapeutic ¹³¹I whole-body scan and detectable serum thyroglobulin levels

INTRODUCTION

DTC patients having detectable Tg and negative post-therapeutic (131)I-WBS have to be investigated by different imaging techniques to detect metastases.

PURPOSE

Comparison of neck US, CT and [18F]-FDG PET scan.

METHODS

In 49 DTC patients with biochemical disease, neck was examined by US, CT and [18F]-FDG PET. FNA was performed and Tg was determined by FNA-Tg in selected cases of suspicious lymph nodes. Thorax was examined by CT and PET. Serum Tg was measured on LT4 therapy (basal Tg) and after the stimulation with recombinant human TSH (peak Tg).

RESULTS

A thyroid remnant was seen by US, CT and PET in eight patients; recurrences were seen by US, CT and PET in six, five and five patients, respectively. Two metastatic nodes were identified by US and CT but not by PET. Lung micronodules were detected by CT in 7/49 (14.3 %) patients and by FDG PET in three of them. Basal Tg ranged from 0.5-1,725 ng/ml while peak Tg ranged from 0.5 to 2,135 ng/ml: the distribution between positive and negative patients was similar. Bone scan was negative in all cases.

CONCLUSIONS

In DTC patients with detectable Tg and negative I-131 post-therapy WBS, imaging examination revealed remnant or metastases in 43 % of cases. Remnant and recurrences were equally detected by the three techniques; US was better than [18F]-FDG PET for lymph node metastases since this latter method can give false both positive and negative results; chest examination is best made by CT versus FDG PET due to its higher spatial resolution.

Magnetic properties and chiral states of a trimetallic uranium complex

The magnetic properties of the triangular molecular nanomagnet [UO2L]3 (L = 2-(4-tolyl)-1,3-bis(quinolyl)malondiiminate) have been investigated through electron paramagnetic resonance spectroscopy, high-field magnetization and susceptibility measurements. The experimental findings are well reproduced by a microscopic model including exchange interactions and local crystal fields. These results show that [UO2L]3 is characterized by a non-magnetic ground doublet corresponding to two oppositely twisted chiral arrangements of the uranium moments. The non-axial character of single-ion crystal fields leads to quantum tunneling of the noncollinear magnetization in the presence of a magnetic field applied perpendicularly to the triangle plane.

Whispering gallery mode diamond resonator

We demonstrate a nearly spherical diamond whispering gallery mode resonator with quality factor (Q factor) Q=2.4×10(7) limited by material loss approaching α=4×10(-3) cm(-1). The Q factor does not depend on the wavelength: it is approximately the same at 1319 and 1550 nm. Resonators with this range of Q (<10 MHz at 1550 nm wavelength) are attractive for laser locking and stabilization. Applications such as stable compact optical comb generators as well as Raman optical frequency shifters will be feasible with further improvement of the material.

Quantum information processing with hybrid spin-photon qubit encoding

We introduce a scheme to perform quantum information processing that is based on a hybrid spin-photon qubit encoding. The proposed qubits consist of spin ensembles coherently coupled to microwave photons in coplanar waveguide resonators. The quantum gates are performed solely by shifting the resonance frequencies of the resonators on a nanosecond time scale. An additional cavity containing a Cooper-pair box is exploited as an auxiliary degree of freedom to implement two-qubit gates. The generality of the scheme allows its potential implementation with a wide class of spin systems.

Many-body models for molecular nanomagnets

We present a flexible and effective ab initio scheme to build many-body models for molecular nanomagnets, and to calculate magnetic exchange couplings and zero-field splittings. It is based on using localized Foster-Boys orbitals as a one-electron basis. We apply this scheme to three paradigmatic systems, the antiferromagnetic rings Cr8 and Cr7Ni, and the single-molecule magnet Fe4. In all cases we identify the essential magnetic interactions and find excellent agreement with experiments.

Salivary glands ultrasound examination after radioiodine-131 treatment for differentiated thyroid cancer

BACKGROUND

The most important side effect of radioiodine ((131)I) therapy is sialoadenitis and xerostomy.

AIM

To evaluate by ultrasound (US) parotid and submandibular glands after (131)I therapy for differentiated thyroid cancer (DTC).

PATIENTS

Seventy-six subjects thyroidectomized for DTC submitted to salivary glands US examination. Forty-three of them had been previously treated with (131)I: 22 with 1.11 GBq (30 mCi) for remnant ablation, and 21 with higher doses [up to 44.4 GBq (1200 mCi)] for metastases. Thirty-three subjects studied before (131)I therapy served as controls. Parotid and submandibular volume, homogeneity, and echogenicity were determined. (131)I-treated patients filled a questionnaire about sialoadenitis symptoms.

RESULTS

Parotid gland volume was significantly higher in treated patients (28.3±16.2 ml) than in untreated patients (20.7±10.4 ml, p=0.0154) and related to the time from last (131)I therapy. Three had parotid volume <1.5 ml and complained severe xerostomy. Submandibular gland volume was similar in treated (11.2±7.6 ml) and untreated patients (8.6±4.2 ml, p=0.0602). Homogeneity and echogenicity were similar in treated and untreated patients. Sialoadenitis symptoms were reported in 26% and were related to the (131)I cumulative dose. Symptoms were not related to gland volume. Hypoechogenicity and inhomogeneity of the parotids were more frequent in patients with salivary stickiness.

CONCLUSION

Parotid, but not submandibular, volume is increased after (131)I treatment depending on the received activity and the time from irradiation but not on sialoadenitis symptoms. Xerostomy is associated to gland atrophy at US.

Magnetic properties and relaxation dynamics of a frustrated Ni₇ molecular nanomagnet

The Ni₇ nanomagnet represents an ideal model system for investigating the effects of geometrical frustration in magnetic interactions. The Ni ions in the magnetic core are arranged on two corner-sharing tetrahedra and interact through antiferromagnetic exchange couplings. We show that the high degree of frustration leads to a magnetic energy spectrum with large degeneracies which result in unusual static and dynamical magnetic properties. In particular, the relaxation dynamics of the magnetization is characterized by several distinct characteristic times. We also discuss the possible interest of Ni₇ for magnetocaloric refrigeration.

Cadmium-induced apoptosis and necrosis in human osteoblasts: role of caspases and mitogen-activated protein kinases pathways

Cadmium is a widespread environmental pollutant which induces severe toxic alterations, including osteomalacia and osteoporosis, likely by estrogen receptor-dependent mechanisms. Indeed, cadmium has been described to act as an endocrine disruptor and its toxicity is exerted both in vivo and in vitro through induction of apoptosis and/or necrosis by not fully clarified intracellular mechanism(s) of action. Aim of the present study was to further investigate the molecular mechanism by which cadmium might alter homeostasis of estrogen target cells, such as osteoblast homeostasis, inducing cell apoptosis and/or necrosis. Human osteoblastic cells (hFOB 1.19) in culture were used as an in vitro model to characterize the intracellular mechanisms induced by this heavy metal. Cells were incubated in the presence/ absence of 10-50 μM cadmium chloride at different times and DNA fragmentation and activation of procaspases- 8 and -3 were induced upon CdCl(2) treatment triggering apoptotic and necrotic pathways. Addition of caspase-8 and -3 inhibitors (Z-IETD-FMK and Z-DQMD-FMK) partially blocked these effects. No activation of procaspase-9 was observed. To determine the role of mitogen-activated protein kinases (MAPK) in these events, we investigated c-jun N-terminal kinase (JNK), p38 and extracellular signal-regulated protein kinase (ERK1/2) phosphorylation which were activated by 10 μM CdCl(2). Chemical inhibitors of JNK, p38, and ERK1/2, SP600125, SB202190, and PD98059, significantly reduced the phosphorylation of the kinases and blunted apoptosis. In contrast, caspase inhibitors did not reduce the cadmium-induced MAPK phosphorylation, suggesting an independent activation of these pathways. In conclusion, at least 2 pathways appear activated by cadmium in osteoblasts: a direct induction of caspase-8 followed by activation of caspase-3 and an indirect induction by phosphorylation of ERK1/2, p38, and JNK MAPK triggering activation of caspase-8 and -3.

Molecular nanomagnets as quantum simulators

Quantum simulators are controllable systems that can be used to simulate other quantum systems. Here we focus on the dynamics of a chain of molecular qubits with interposed antiferromagnetic dimers. We theoretically show that its dynamics can be controlled by means of uniform magnetic pulses and used to mimic the evolution of other quantum systems, including fermionic ones. We propose two proof-of-principle experiments based on the simulation of the Ising model in a transverse field and of the quantum tunneling of the magnetization in a spin-1 system.

Surface analysis and osteoblasts response of a titanium oxi-carbide film deposited on titanium by ion plating plasma assisted (IPPA)

Titanium is the most widely used material in orthopaedic and dental implantoprosthesis due to its superior physical properties and enhanced biocompatibility due to the spontaneous formation of a passivating layer of titanium oxides which, however, does not form good chemical bonds with bone and tends to brake exposing bulk titanium to harsh body fluids releasing titanium particles which may prime an inflammation response and a fibrotic tissue production. In order to avoid these possible problems and to enhance the biocompatibility of titanium implants, modifications of titanium surfaces by many different materials as hydroxyapatite, titanium nitride, titanium oxide and titanium carbide have been proposed. The latter is shown to be an efficient protection for the titanium implant in the harsh conditions of biological tissues and, compared to untreated titanium, acting like an osteoblast stimulation factor increasing in vitro production of proteins involved in osteogenesis. These results were confirmed by in vivo experiments in rabbits: implants covered by the titanium carbide (TiC) layer were faster and better osseointegrated than untreated titanium implants. The TiC layer was deposited by a Pulsed Laser Deposition (PLD) device which allowed only one deposition per cycle, shown to be unsuitable for industrial applications. Therefore the main objective of the present work was to replace PLD process with an Ion Plating Plasma Assisted (IPPA) deposition process, which is suitable for industrial upgrading. By this technique, nanostructured TiOx-TiCy-C has been deposited on titanium after sandblasting with 120 micron zirconia spheres. XPS analyses revealed the presence of about 33% carbon (50% of which is present as free carbon), 39% oxygen and 28% titanium (37% of which is bound to carbon to form TiC and 63% is bound to oxygen to form non stoichiometric oxides). Surface mechanical response of as-deposited coatings has been performed by nanoindentation techniques. Focused Ion Beam micrographs showed bigger differences on the obtained nanostructure compared to the PLD coating structure; in vitro tests confirm for IPPA produced coatings an improvement in stimulating osteoblasts to produce mRNA's of proteins involved in the ossification process, this latter case they resulted to be faster and more efficient. The proposed treatement is expected to improve the good results obtained by PLD, in vivo as well.

Quadrupolar waves in uranium dioxide

In presence of active orbital degrees of freedom, elementary excitations around a broken-symmetry state may include multipolar waves, but none of these exotic dispersive excitation branches has ever been identified. We show that quadrupolar waves constitute a major component of the dynamics of uranium dioxide in its magnetoquadrupolar ordered phase, and that many unexplained features in existing inelastic neutron scattering data, including a whole excitation branch, are associated with these propagating quadrupolar fluctuations. Our model permits us to separate the role of Jahn-Teller and superexchange mechanisms as sources of quadrupolar interactions.

Role of recombinant human TSH in the management of large euthyroid multinodular goitre: a new therapeutic option? Pros and cons

Conventional 131I treatment has been used in the last 20 years for large nodular goitres when patients present high surgical risk or simply refuse surgery. 131I therapy causes a mean goitre volume reduction of about 40% after one year. However, the individual response is variable and for low radioiodine uptake and very large goitres, high 131I activities are needed in order to have a adequate 131I accumulation in the thyroid. rhTSH is approved for thyroid cancer management and has been tested off label in large goitres, in whom increases 131I uptake, thus reducing the 131I amount to be administered. The use of lower 131I activities allows to reduce the radiation burden to body and the time of social life restriction. Moreover, depending on the radiation regulations of the different countries, the 131I therapy could be carried out either as outpatients or in a shorter hospitalization period, implying a decrease of costs. The effects of rhTSH on goitre may be due not only to the 131I uptake increase, but also to a more homogeneous distribution of 131I in the gland, and to the thyroid cell activation that makes them more radiosensitive. Acute adverse effects are due to the surge of thyroid hormone in blood and to the goitre volume increase, that cause cardiac symptoms and tracheal compression, respectively. These effects are probably dose dependent and are negligible for rhTSH lower doses.

Entanglement in supramolecular spin systems of two weakly coupled antiferromagnetic rings (purple-Cr7Ni)

We characterize supramolecular magnetic structures, consisting of two weakly coupled antiferromagnetic rings, by low-temperature specific heat, susceptibility, magnetization and electron paramagnetic resonance measurements. Intra- and inter-ring interactions are modeled through a microscopic spin-Hamiltonian approach that reproduces all the experimental data quantitatively and legitimates the use of an effective two-qubit picture. Spin entanglement between the rings is experimentally demonstrated through magnetic susceptibility below 50 mK and theoretically quantified by the concurrence.

Unconventional nonequilibrium dynamics in Ni10 magnetic molecules: evidence from NMR

Crystals containing Ni10 magnetic molecules display an unprecedented form of out-of-equilibrium behavior of the bulk magnetization M at temperatures as high as 17 K. We have performed 1H NMR measurements to probe the local Ni magnetic moments and their dynamics. It is apparent that no freezing of the Ni moments occurs, in striking contrast to what is observed in blocked superparamagnetic systems. The average local moments display the same behavior as M, thus unambiguously demonstrating the intrinsic character of the phenomenon. This result supports the hypothesis that the slowing down of M is due to a resonant phonon trapping mechanism which prevents the thermalization of M but not the fast spin flippings of the individual molecular moments. Indeed, the measured nuclear spin-lattice relaxation rate points to fast single-molecule dynamics at low temperature.

Breastfeeding in Northern Italy

AIM

To describe the duration and type, as classified by World Health Organization (WHO) criteria, of breastfeeding in Ligurian newborns up to 1 year of age, and to identify possible related factors.

METHODS

A prospective, observational study on a cohort of 757 women recruited in 10 hospitals in Northern Italy. Women were followed up by means of a questionnaire at discharge and by telephone interviews in the 4th, 12th, 24th and 48th weeks postpartum using the 'recall period' method.

RESULTS

At discharge, 97.3% of mothers had started breastfeeding; regional breastfeeding rates at the 4th, 12th, 24th and 48th weeks were respectively 84.4%, 71.2%, 54.4% and 26.3%. Socio-demographic factors did not significantly influence these percentages. Median duration of breastfeeding was 6.5 months. No statistically significant differences were observed in duration of breastfeeding between women who started exclusive breastfeeding (EBF) and those who did predominant breastfeeding (PBF), while the difference was statistically significant when comparing complementary breastfeeding (CBF) with EBF and with PBF.

CONCLUSIONS

Our study is the first regional experience in the Liguria region and represents a starting point for the diffusion of the culture of breastfeeding. Our results are satisfactory with regards to the overall duration of breastfeeding until the first year of life (26.3%), while duration of EBF (9.5% at the 24th week) is still unsatisfactory according to WHO objectives that include EBF for all children up to the sixth month of life.

Breakdown of the giant spin model in the magnetic relaxation of the Mn6 nanomagnets

We study the spin dynamics in two variants of the high-anisotropy Mn6 nanomagnet by inelastic neutron scattering, magnetic resonance spectroscopy and magnetometry. We show that a giant-spin picture is completely inadequate for these systems and that excited S multiplets play a key role in determining the effective energy barrier for the magnetization reversal. Moreover, we demonstrate the occurrence of tunneling processes involving pair of states having different total spin.

Quantum oscillations of the total spin in a heterometallic antiferromagnetic ring: evidence from neutron spectroscopy

Using inelastic neutron scattering and applied fields up to 11.4 T, we have studied the spin dynamics of the Cr7Ni antiferromagnetic ring in the energy window 0.05-1.6 meV. We demonstrate that the external magnetic field induces an avoided crossing (anticrossing) between energy levels with different total-spin quantum numbers. This corresponds to quantum oscillations of the total spin of each molecule. The inelastic character of the observed excitation and the field dependence of its linewidth indicate that molecular spins oscillate coherently for a significant number of cycles. Precise signatures of the anticrossing are also found at higher energy, where measured and calculated spectra match very well.

Hidden order and low-energy excitations in NpO2

We investigate the nature of the hidden order parameter in the ordered phase of NpO2, which had been identified with a staggered arrangement of Gamma5 magnetic multipoles. By analyzing the existing experimental data, we show that the most likely driving order parameter is not provided by octupoles, as usually assumed, but rather by the rank-5 triakontadipoles. Calculations of the coupled dynamics of spins, Gamma5 quadrupoles, and Gamma5 triakontadipoles in the ordered phase enable us to analyze the resulting structure of low-energy excitations. We show that the powder inelastic neutron scattering cross section should contain, in addition to the already-observed peak at 6.5 meV, a second weaker peak at about 14 meV.

High-temperature slow relaxation of the magnetization in Ni10 magnetic molecules

We investigate a family of molecular crystals containing noninteracting Ni10 magnetic molecules. We find slow relaxation of the magnetization below a temperature as high as 17 K and we show that this behavior is not associated with an anisotropy energy barrier. Ni10 has a characteristic magnetic energy spectrum structured in dense bands, the lowest of which makes the crystal opaque to phonons of energy below about 1 meV. We ascribe the nonequilibrium behavior to the resulting resonant trapping of these low-energy phonons. Trapping breaks up spin relaxation paths leading to a novel kind of slow magnetic dynamics which occurs in the lack of anisotropy, magnetic interactions and quenched disorder.

HYPERTENSION IN EARLY ALCOHOL WITHDRAWAL IN CHRONIC ALCOHOLICS

AIMS

Hypertension is an established risk factor in chronic alcoholics, but little is known about the relationship between blood pressure (BP), severity of their alcohol abuse, and severity of alcohol withdrawal syndrome (AWS).

METHOD

BP was assessed daily for 18 days in a series of chronic alcoholics on early alcohol withdrawal (AW), while also assessing the severity of their AWS on the CIWA-Ar scale.

RESULTS

A sharp and sustained decrease in BP was observed after AW; at T0, BP had increased in 55% of patients, and at T18 in 21%. The variation of BP is partially explained by years of at-risk drinking and AWS severity, but other factors may play a role in hypertension in alcoholics, as a large amount of BP variation was not explained by the alcohol-abuse-related parameters that we studied. BP values were not correlated with cigarette smoking, anxiety, or depression. Hypertension found in 'detoxified' alcoholics (approximately 20%) may be related to alcohol-independent hypertension or to a long-lasting alcohol-induced derangement of the BP regulating mechanisms. Further research is needed in these patients to elucidate the mechanisms of persistent hypertension and to set up a treatment protocol. At present, careful monitoring is advisable, as well as pharmacological treatment for moderate or severe hypertension; often a modification of life-style is needed which includes physical activity and possibly sodium (Na) restriction, since hypertension in detoxified alcoholics seems to be Na sensitive.

CONCLUSION

Complete alcohol abstinence must be recommended to all hypertensive alcoholics, as AW-induced transient hypertension was found to be harmless in all our subjects, and abstinence leads to a complete recovery from hypertension in most cases.

Intracranial pressure monitoring in children with single suture and complex craniosynostosis: a review

INTRODUCTION

One third of patients with craniofacial dysostosis syndromes and about 15-20% of children with single suture craniostenosis have a documented increase in intracranial pressure (ICP). The early detection of intracranial hypertension is important in order to reduce the risks for brain development and visual function. However, in children with craniosynostosis, the clinical manifestations of abnormally increased ICP are difficult to detect, as the majority of patients may have neither warning signs nor symptoms for a long period of time.

REVIEW

Moreover, data from the literature suggest that neither fundoscopic nor radiological findings are necessarily related to intracranial pressure recordings in this type of pathology. In this context prolonged ICP monitoring seems actually to be the most valuable diagnostic tool. Extradural, subdural, and intraparenchymal devices have been used, and different softwares have been employed for PC storage and analysis of the data obtained. Most recent series consider mean ICP combined with plateaux waves as the most sensitive indicators in the final evaluation of the results.

CONCLUSIONS

The analysis of the literature demonstrates a significant difference in the prevalence of raised ICP preoperatively between non-syndromic and syndromic patients. Among the non-syndromic children, a direct relation between the number of sutures involved and raised ICP is documented. The analysis of plateaux waves seems to be particularly important in children with borderline mean ICP values. Persistent postoperative raised ICP has been described in 6-15% of patients with craniofacial dysostosis. It must be related to the multifactorial etiology of increased ICP in these patients, which includes cerebral venous congestion, upper airway obstruction, and hydrocephalus.

Molecular engineering of antiferromagnetic rings for quantum computation

The substitution of one metal ion in a Cr-based molecular ring with dominant antiferromagnetic couplings allows the engineering of its level structure and ground-state degeneracy. Here we characterize a Cr7Ni molecular ring by means of low-temperature specific-heat and torque-magnetometry measurements, thus determining the microscopic parameters of the corresponding spin Hamiltonian. The energy spectrum and the suppression of the leakage-inducing S mixing render the Cr7Ni molecule a suitable candidate for the qubit implementation, as further substantiated by our quantum-gate simulations.

NMR as a probe of the relaxation of the magnetization in magnetic molecules

We investigate the time autocorrelation of the molecular magnetization M(t) for three classes of magnetic molecules (antiferromagnetic rings, grids, and nanomagnets), in contact with the phonon heat bath. For all three classes, we find that the exponential decay of the fluctuations of M(t) is characterized by a single characteristic time tau(T,B) for not too high temperature T and field B. This is reflected in a nearly single-Lorentzian shape of the spectral density of the fluctuations. We show that such fluctuations are effectively probed by NMR, and that our theory explains the recent phenomenological observation by Baek et al. [Phys. Rev. B 70, 134434 (2004)] that the Larmor-frequency dependence of 1/T(1) data in a large number of AFM rings fits to a single-Lorentzian form.

[Analysis of a Yersinia enterocolitica isolated from human diarrheic feces in Argentina]

Some serotypes of Yersinia enterocolitica might cause diarrheas and/or invasive infections. The aim of this work was to analyze virulence factors and associated markers in a strain of Y. enterocolitica isolated from human diarrheic feces. The strain analyzed was included in the biotype 1A. The virulence markers determination as well as the search of the genes vir F and ail, were negatives. However, it was demonstrated enterotoxin production at 20 degrees C, and at 37 degrees C in osmolarity conditions and pH similar to the human intestine. The enterotoxin presented reactivity for the infant mouse test, although it could not be proven the presence of yst gene by PCR. The results obtained by us, coincident with those of other investigators, indicated that certain clinical isolates of Y. enterocolitica of the biotype 1A ("avirulent"), could be the etiological agent of the illness through other mechanisms of virulence, that would differ from those previously characterized in species of enteropathogenic Yersinia.

Location of functioning metastases from differentiated thyroid carcinoma by simultaneous double isotope acquisition of I-131 whole body scan and bone scan

In a young patient with differentiated thyroid carcinoma (DTC), previously submitted to total thyroidectomy and I-131 therapy for ablation of thyroid remnant, a follow-up 1-131 diagnostic whole body scan (WBS) demonstrated four small abnormal I-131 uptake areas. Two of these were projected over the thoracic region and corresponded to lung nodules, as later demonstrated by lung computerized tomography (CT)-scan. The remaining two areas were found in the lumbar-pelvic region, but their precise location could not be determined. Standard bone Rx examination and bone scan were negative. After I-131 therapy, we simultaneously acquired a I-131 WBS and a Tc-99m oxidronate bone scan by setting a dual window on the gamma camera. Comparing the I-131 and bone images we were able to identify the 4th lumbar vertebra and right ilium as the bone segments to be studied by a radiological approach. Eventually, the thin slice CT-scan demonstrated the presence of two small osteolytic lesions in these areas. In conclusion, the simultaneous acquisition of images both from I-131 and a bone-seeking agent may be useful to locate functioning bone metastases from DTC.

S mixing and quantum tunneling of the magnetization in molecular nanomagnets

The role of S mixing in the quantum tunneling of the magnetization in nanomagnets has been investigated. We show that the effect on the tunneling frequency is huge and that the discrepancy (more than 3 orders of magnitude in the tunneling frequency) between spectroscopic and relaxation measurements in Fe(8) can be resolved if S mixing is taken into account.

Quantum magneto-oscillations in a supramolecular Mn(II)-[3 x 3] grid

The magnetic grid molecule Mn(II)-[3 x 3] has been studied by high-field torque magnetometry at 3He temperatures. At fields above 5 T, the torque versus field curves exhibit an unprecedented oscillatory behavior. A model is proposed which describes these magneto-oscillations well.

[Prolonged ICP monitoring in children with sylvian fissure arachnoid cysts]

BACKGROUND

The decision making process for patients with sylvian fissure arachnoid cysts still represents a challenge for the neurosurgeon. A high proportion of the patients is indeed asymptomatic, in spite of neuroimaging signs of apparently increased intracranial pressure (ICP). The aim of the present study was to evaluate the usefulness of prolonged ICP recording in the preoperative work-out.

METHODS

Twelve children (11 M/1 F) harboring temporal arachnoid cysts were investigated (men age 6.3 years). According to Galassi classification they were subdivided into 3 groups. Group I included 3 patients with Type I cysts; group II comprised 6 children with Type II cysts; group III consisted of 3 children with Type III cysts. An extensible silicone microprocessor (Codman ), developed for continuous ICP recording, was implanted intraparenchymally, adjacent to the major extension of the cyst. The collected information was cable unloaded to a PC and stored. All the patients underwent a minimum of 48 hours to a maximum of 72 hours ICP continuous check. Ten mmHg was arbitrarily chosen as the upper normal limit of ICP in resting conditions and the patients were classified according to the percentile distribution of their ICP daily and nightly pressure values.

RESULTS

ICP recordings were in the normal range in all the 3 children with Type I cysts (49-86% <10 mmHg during the entire recording), in spite of the fact that 2 of them were apparently symptomatic. Three of the 6 children with a Type II temporal cyst had elevated ICP values (69-99% >10 mmHG), even though they had an incidental (1 case) or prenatal (2 cases) diagnosis. The remaining 3 patients had normal ICP values for more than 70% of the recording time period. Two of the 3 patients with type III temporal arachnoid cysts had almost constantly abnormal ICP values (95=99% >10 mmHg); conversely the third patient showed normal ICP values for more than 80% of the recording time period. Five patients were operated on; in 4 of them the surgical indication was based on ICP recordings (2 of the 3 children with a Type II cyst and increased ICP and the 2 patients with a Type III cyst and increased ICP). The last child, harboring a Type I cyst, was operated on under parents request, as a preventive measure. At a mean follow-up of 10.1 months all the patients operated on are in excellent clinical conditions; 1 of them (Type II cyst) initially submitted to craniotomy and cystic membrane excision needed a subdural-peritoneal shunt implant 3 months after surgery for the appearance of a symptomatic subdural hygroma on the side of the cyst. Postoperative CT showed signs of brain expansion in the 2 patients operated on for a Type III cyst, and in the patients operated on for a Type I cyst.

CONCLUSIONS

With the limit of the relatively small series here presented, prolonged ICP recording appeared to be an important preoperative tool to rule out the necessity of operating on children with Type I cysts. Furthermore, it was particularly useful in the decision-making process for children with Type III cysts. In cases of Type II lesions, the investigation resulted less discriminating, though the ICP monitoring contributed to find out those patients in whom surgery was indicated in spite of the absence of symptoms.

[Symptoms experienced by people in vicinity of base stations: II/ Incidences of age, duration of exposure, location of subjects in relation to the antennas and other electromagnetic factors]

This is the 2nd part of a survey study conducted on 530 people (270 men, 260 women) living or not in vicinity of cellular phone base stations. Comparison of complaints frequencies for 16 Non Specific Health Symptoms was done with the CHI-Square test with Yates correction. Our results show significant increase (p < 0.05) in relation with age of subjects (elder subjects are more sensitive) and also, that the facing location is the worst position for some symptoms studied, especially for distances till 100 m from base stations. No significant difference is observed in the frequency of symptoms related to the duration of exposure (from < 1 year to > 5 years), excepted for irritability significantly increased after > 5 years. Other electromagnetic factors (electrical transformers, radio-television transmitters,...) have effects on the frequency of some symptoms reported by the subjects.