Enumerative Combinatorics of Intervals in the Dyck Pattern Poset

We initiate the study of the enumerative combinatorics of the intervals in the Dyck pattern poset. More specifically, we find some closed formulas to express the size of some specific intervals, as well as the number of their covering relations. In most of the cases, we are also able to refine our formulas by rank. We also provide the first results on the Möbius function of the Dyck pattern poset, giving for instance a closed expression for the Möbius function of initial intervals whose maximum is a Dyck path having exactly two peaks

The classical and quantum dynamics of molecular spins on graphene

PMCID: PMC4800001.-- et al.Controlling the dynamics of spins on surfaces is pivotal to the design of spintronic and quantum computing devices. Proposed schemes involve the interaction of spins with graphene to enable surface-state spintronics and electrical spin manipulation. However, the influence of the graphene environment on the spin systems has yet to be unravelled. Here we explore the spin-graphene interaction by studying the classical and quantum dynamics of molecular magnets on graphene. Whereas the static spin response remains unaltered, the quantum spin dynamics and associated selection rules are profoundly modulated. The couplings to graphene phonons, to other spins, and to Dirac fermions are quantified using a newly developed model. Coupling to Dirac electrons introduces a dominant quantum relaxation channel that, by driving the spins over Villain's threshold, gives rise to fully coherent, resonant spin tunnelling. Our findings provide fundamental insight into the interaction between spins and graphene, establishing the basis for electrical spin manipulation in graphene nanodevices.Financial support from Italian MIUR, Spanish MINECO (MAT2012-38318-C03-01), BW-Stiftung (Kompetenznetz Funktionelle Nanostrukturen), ERC StG-338258 “OptoQMol”, the Royal Society (URF fellowship and grant) and the AvH Stiftung (Sofja Kovalevskaja award).Peer Reviewe

Oxo-centered carboxylate-bridged trinuclear complexes deposited on Au(111) by a mass-selective electrospray.

We developed an apparatus for nondestructive in vacuum deposition of mass-selected fragile Cr based metal trinuclear complexes, by modifying a commercial Mass Spectrometer containing an electrospray ionization source. Starting from a solution, this system creates a beam of ionized molecules which is then transferred into an evacuated region where the molecules can be mass selected before deposition. To verify the system efficiency, we deposited sub monolayers of oxo-centered carboxylate-bridged trinuclear complexes (Cr3 and Cr2Ni) on Au(111) surface. By XPS and STM we determined the deposited molecule stoichiometry and the surface coverage. The results show that this apparatus is works well for the in vacuum deposition of molecular nanomagnets and, thanks to its reduced dimensions, it is portable

Providing a nurse-led complex nursing INtervention FOcused on quality of life assessment on advanced cancer patients: The INFO-QoL pilot trial.

PURPOSE Unmet needs for advanced-disease cancer patients are fatigue, pain, and emotional support. Little information is available about the feasibility of interventions focused on patient-reported outcome measurement developed according to the Medical Research Council (MRC) Framework in advanced-disease cancer patients. We aimed to pilot a nurse-led complex intervention focused on QoL assessment in advanced-disease cancer patients. METHODS The INFO-QoL study was based on an exploratory, nonequivalent comparison group, pre-test-post-test design. Study sites received either the INFO-QoL intervention or usual care. Adult advanced-disease cancer patients admitted to hospice inpatient units that gave their informed consent were included in the study. Subjects were 187 patients and their families and 19 healthcare professionals. We evaluated feasibility, acceptability, and patients' outcomes using the Integrated Palliative Care Outcome Scale. RESULTS Nineteen healthcare professionals were included. The mean competence score increased significantly over time (p < 0.001) and the mean usefulness score was high 8.63 (±1.36). In the post-test phase, 54 patients were allocated to the experimental unit and 36 in the comparison unit. Compared to the comparison unit, in the experimental unit anxiety (R2 = 0.07; 95% CI = -0.06; 0.19), family anxiety (R2 = 0.22; 95% CI = -0.03; 0.41), depression (R2 = 0.31; 95% CI = -0.05; 0.56) and sharing feelings (R2 = 0.09; 95% CI = -0.05; 0.23), were improved between pre-test and post-test phase. CONCLUSIONS The INFO-QoL was feasible and potentially improved psychological outcomes. Despite the high attrition rate, the INFO-QoL improved the quality and safety culture for patients in palliative care settings

Magnetic dynamics of Fe4 molecular clusters in crystals and on graphene

Resumen del trabajo presentado a la 20th International Conference on Solid Compounds of Transition Elements, celebrada del 11 al 15 de abril de 2016 en Zaragoza (España).Graphene, a two-dimensional carbon layer, is expected to contribute to a new revolution in electronics. However, the fact that graphene is not magnetic, just as any other carbon derivative, hinders its application to spintronics, i.e. to magnetic data storage and processing. A way to circumvent this difficulty is by doping graphene with either point-like defects or with molecules having a localized spin, such as free-radical systems. The nature of the ensuing magnetism and the existence of a coupling to graphene’s Dirac electrons remains, however, a subject of controversy. Besides, very little is known about the dynamics of spins in graphene. In this work, we have studied a new hybrid material formed by anchoring Fe4 molecular clusters, with a net spin S = 4, to graphene layers. In crystalline form, these clusters behave as single-molecule magnets, i.e. they show magnetic memory effects and slow relaxation at very low temperatures. Below 1 K, the dominant relaxation process is mediated by pure spin tunneling events. Because of the compact structure of its magnetic core, Fe4 clusters retain their electronic and magnetic properties when they are deposited onto solid substrates. Therefore, they provide an close to ideal situation to study how the spin dynamics is affected by the interaction with graphene. We have performed ac susceptibility experiments, with frequencies ranging from 0.1 Hz up to 200 kHz, using a high-sensitivity micro-SQUID susceptometer installed in a 3He-4He dilution refrigerator that gives access to the close neighbourhood of absolute zero (T > 11 mK). Experiments have been performed on the Ge4@graphene hybrid and on single crystals of Fe4 molecular magnets having different ligands and concentrations. The results confirm that properties such as the net molecular spin and magnetic anisotropy are preserved in the former material. However, the spin dynamics is dramatically affected by the presence of the graphene layer. In particular, the tunneling rate, measured at very low temperature, is enhanced by six orders of magnitude. We argue that the effect is due to a very effective shielding of dipole-dipole interactions between the molecules and to the crystal field generated by the graphene layer, which introduces new terms in the molecular spin Hamiltonian that break spin tunneling selection rules. As a result, the molecular spins enter a new dynamical regime, in which tunneling proceeds coherently. These results show that graphene can provide a useful platform for the coherent control of quantum spins with electric fields.Peer reviewe

Management and treatment of gamma butyrolactone withdrawal syndrome: a case report and review.

Gamma butyrolactone (GBL) is an increasingly popular drug of abuse that is readily available in most countries, and it is often purchased over the Internet. In addition to the acute hazards of intoxication and overdose, users who are dependent on GBL can also experience severe withdrawal reactions, including hallucinations, agitation, confusion, delusions, delirium, rhabdomyolysis, and seizures. Most of the existing literature suggests the use of a high-dose benzodiazepine as a first-line treatment for GBL withdrawal. However, several cases of resistance to benzodiazepines have been observed, which likely reflect some pharmacological differences between benzodiazepines and GBL. Specifically, the effects of benzodiazepines are primarily mediated by gamma-aminobutyric acid (GABA)-A receptors, while GBL and its analogues act mainly at GABA-B receptors, with possible additional effects via the ionotropic GABA-A receptors. In this regard, recent studies have found that GBL and its analogues possess a high affinity for a specific form of extrasynaptic GABA-A receptors that are strongly activated by barbiturates, such as phenobarbital, but that are insensitive to benzodiazepines. Taken together, these findings suggest that barbiturates could be evaluated as first-choice agents for the treatment of GBL/gamma hydroxybutyrate (GHB) withdrawal instead of benzodiazepines. In support of this view, we describe a clinical case of difficult to manage GBL withdrawal symptoms in a 42-year-old male. We also review the literature on treatment options for GBL/GHB withdrawal, including benzodiazepine-resistant withdrawa