TurboRVB: A many-body toolkit for ab initio electronic simulations by quantum Monte Carlo

TurboRVB is a computational package for ab initio Quantum Monte Carlo (QMC) simulations of both molecular and bulk electronic systems. The code implements two types of well established QMC algorithms: Variational Monte Carlo (VMC) and diffusion Monte Carlo in its robust and efficient lattice regularized variant. A key feature of the code is the possibility of using strongly correlated many-body wave functions (WFs), capable of describing several materials with very high accuracy, even when standard mean-field approaches [e.g., density functional theory (DFT)] fail. The electronic WF is obtained by applying a Jastrow factor, which takes into account dynamical correlations, to the most general mean-field ground state, written either as an antisymmetrized geminal power with spin-singlet pairing or as a Pfaffian, including both singlet and triplet correlations. This WF can be viewed as an efficient implementation of the so-called resonating valence bond (RVB) Ansatz, first proposed by Pauling and Anderson in quantum chemistry [L. Pauling, The Nature of the Chemical Bond (Cornell University Press, 1960)] and condensed matter physics [P.W. Anderson, Mat. Res. Bull 8, 153 (1973)], respectively. The RVB Ansatz implemented in TurboRVB has a large variational freedom, including the Jastrow correlated Slater determinant as its simplest, but nontrivial case. Moreover, it has the remarkable advantage of remaining with an affordable computational cost, proportional to the one spent for the evaluation of a single Slater determinant. Therefore, its application to large systems is computationally feasible. The WF is expanded in a localized basis set. Several basis set functions are implemented, such as Gaussian, Slater, and mixed types, with no restriction on the choice of their contraction. The code implements the adjoint algorithmic differentiation that enables a very efficient evaluation of energy derivatives, comprising the ionic forces. Thus, one can perform structural optimizations and molecular dynamics in the canonical NVT ensemble at the VMC level. For the electronic part, a full WF optimization (Jastrow and antisymmetric parts together) is made possible, thanks to state-of-the-art stochastic algorithms for energy minimization. In the optimization procedure, the first guess can be obtained at the mean-field level by a built-in DFT driver. The code has been efficiently parallelized by using a hybrid MPI-OpenMP protocol, which is also an ideal environment for exploiting the computational power of modern Graphics Processing Unit accelerators

Response to isolated limb perfusion and chemotherapy with epirubicin plus ifosfamide in a metastatic malignant ossifying fibromyxoid tumor

Background: Ossifying fibromyxoid tumor (OFMT) is a rare soft tissue neoplasm of uncertain lineage and intermediate biological potential. It is more common in middle-aged men, usually arising from the deep tissues of the extremities. It is now established that it is a translocation related tumor, most often marked by translocation of PHF1 gene. Surgery is the mainstay of treatment and proves usually curative, although, in rarer cases the disease shows malignant features and tendency to recur both locally and at distant sites. In such cases, no standard treatment exists. Case presentation: We report on a case of malignant advanced OFMT of the hand with lung metastases responding to isolated limb perfusion with human recombinant tumor necrosis factor and melphalan and chemotherapy with epirubicin and ifosfamide. Conclusions: To our knowledge, this is the first report of activity of soft tissue sarcoma-oriented chemotherapy in advanced OFMT

Intrathoracic solitary fibrous tumor - an international multicenter study on clinical outcome and novel circulating biomarkers

Intrathoracic solitary fibrous tumor (SFT) is a rare disease. Radical resection is the standard of care. However, estimating prognosis and planning follow-up and treatment strategies remains challenging. Data were retrospectively collected by five international centers to explore outcome and biomarkers for predicting event-free-survival (EFS). 125 histological proven SFT patients (74 female; 59.2%; 104 benign; 83.2%) were analyzed. The one-, three-, five- and ten-year EFS after curative-intent surgery was 98%, 90%, 77% and 67%, respectively. Patients age (>/=59 vs. 10 cm vs. 5 vs. < 5 HR 3.91, CI 1.40-10.89, p = 0.009) were prognostic after univariate analyses. After multivariate analyses tumor-dignity and fibrinogen remained as independent prognosticators. Besides validating the role of age, tumor-dignity, tumor-size, stage and resection margins, we identified for the first time inflammatory markers as prognosticators in SFT

Identification of an actionable mutation of kit in a case of extraskeletal myxoid chondrosarcoma

Extraskeletal myxoid chondrosarcoma (EMC) is an extremely rare soft tissue sarcoma, marked by a translocation involving the NR4A3 gene. EMC is usually indolent and moderately sensitive to anthracycline-based chemotherapy. Recently, we reported on the therapeutic activity of sunitinib in a series of EMC cases, however the molecular target of sunitinib in EMC is unknown. Moreover, there is still the need to identify alternative therapeutic strategies. To better characterize this disease, we performed whole transcriptome sequencing in five EMC cases. Peculiarly, in one sample, an in-frame deletion (c.1735_1737delGAT p.D579del) was identified in exon 11 of KIT. The deletion was somatic and heterozygous and was validated both at DNA and mRNA level. This sample showed a marked high expression of KIT at the mRNA level and a mild phosphorylation of the receptor. Sanger sequencing of KIT in additional 15 Formalin Fixed Paraffin Embedded (FFPE) EMC did not show any other mutated cases. In conclusion, exon 11 KIT mutation was detected only in one out of 20 EMC cases analyzed, indicating that KIT alteration is not a recurrent event in these tumors and cannot explain the EMC sensitivity to sunitinib, although it is an actionable mutation in the individual case in which it has been identified

Carbon nanotubes as excitonic insulators

Fifty years ago Walter Kohn speculated that a zero-gap semiconductor might be unstable against the spontaneous generation of excitons-electron-hole pairs bound together by Coulomb attraction. The reconstructed ground state would then open a gap breaking the symmetry of the underlying lattice, a genuine consequence of electronic correlations. Here we show that this excitonic insulator is realized in zero-gap carbon nanotubes by performing first-principles calculations through many-body perturbation theory as well as quantum Monte Carlo. The excitonic order modulates the charge between the two carbon sublattices opening an experimentally observable gap, which scales as the inverse of the tube radius and weakly depends on the axial magnetic field. Our findings call into question the Luttinger liquid paradigm for nanotubes and provide tests to experimentally discriminate between excitonic and Mott insulators

The Semiology of Cinema? It Is Necessary to Continue : A conversation with Christian Metz

This interview was conducted in Bologna in October 1988. The conversation unfolds along the three historical phases of Metz\u2019s work \u2013 the semio-linguistic, the semio-psychoanalytic, and the text-pragmatical phase on filmic enunciation. Metz self-critically returns to his proposition of a Grand Syntagmatique of f ilm. In addition, he embeds his film-semiological approach in a meta-theoretical and meta-historical reflection, and talks about how much his thinking owes to Andr\ue9 Bazin, Pier Paolo Pasolini, Jean Mitry, and many others