Primary yolk sac tumour of the prostate mimicking small round blue cell tumour.

Prostatic yolk sac tumour is a germ cell tumour with a wide range of age of occurrence, unusual anatomic locations, diverse morphologic patterns, and aggressive biologic behavior, posing challenges both to diagnosis and clinical management. We report a rare case of primary yolk sac tumour of the prostate with extensive local and liver metastasis, the latter of which exhibited sheets of small blue cells expressing CD99 and focal sall4 on biopsy. Positivity for CD99 and gata3 in the initial biopsy raised the differential diagnosis of Ewing sarcoma and poorly differentiated carcinoma. The primary tumour demonstrated an admixture of solid and glandular growth patterns and occasional Schiller-Duval bodies. A panel of immunohistochemical stains showing positivity for AE1/3, sall4, cdx2, and focal alpha-fetoprotein, and negativity for oct-4, facilitated the diagnosis. A thorough review of the literature and our current report indicate that a large tumour load, incomplete tumour resection, limited response to preoperative neoadjuvant chemotherapy, and late stage of the disease are predictive factors for a poor clinical outcome.

Interplanar coupling-dependent magnetoresistivity in high-purity layered metals.

The magnetic field-induced changes in the conductivity of metals are the subject of intense interest, both for revealing new phenomena and as a valuable tool for determining their Fermi surface. Here we report a hitherto unobserved magnetoresistive effect in ultra-clean layered metals, namely a negative longitudinal magnetoresistance that is capable of overcoming their very pronounced orbital one. This effect is correlated with the interlayer coupling disappearing for fields applied along the so-called Yamaji angles where the interlayer coupling vanishes. Therefore, it is intrinsically associated with the Fermi points in the field-induced quasi-one-dimensional electronic dispersion, implying that it results from the axial anomaly among these Fermi points. In its original formulation, the anomaly is predicted to violate separate number conservation laws for left- and right-handed chiral (for example, Weyl) fermions. Its observation in PdCoO2, PtCoO2 and Sr2RuO4 suggests that the anomaly affects the transport of clean conductors, in particular near the quantum limit.

The angular magnetothermoelectric power of a charge density wave system.

The angular dependence of the magnetothermopower of a charge transfer organic salt α-(ET)(2)KHg(SCN)(4) below (4 K) and above (9 K) the phase transition temperature, T(p) = 8 K, and under fields of 15 T and 25 T, below and above the 'kinkfield', has been studied. We find that for a longitudinal thermoelectric measurement both an interlayer thermopower (the Seebeck effect), S(zz), and a transverse thermopower (the Nernst effect), S(yz), exist in all three different B-T phases (the CDW (0), CDW (x) and metallic states) with large amplitude. Both thermoelectric effects display a resonant-like behavior without a sign reversal at the angles corresponding to angular magnetoresistance oscillation minima and maxima in this compound. The resonant behavior is most evident in the CDW(0) state, indicating a mechanism involving the Fermi surface nesting. Angular dependences reveal different behaviors of the thermopower and Nernst effect in the high magnetic field (CDW(x)) state.

Note: adhesive stamp electrodes using spider silk masks for electronic transport measurements of supra-micron sized samples.

A procedure for fabricating adhesive stamp electrodes based on gold coated adhesive tape used to measure electronic transport properties of supra-micron samples in the lateral range 10-100 µm and thickness >1 µm is described. The electrodes can be patterned with a ~4 µm separation by metal deposition through a mask using Nephila clavipes spider dragline silk fibers. Ohmic contact is made by adhesive lamination of a sample onto the patterned electrodes. The performance of the electrodes with temperature and magnetic field is demonstrated for the quasi-one-dimensional organic conductor (TMTSF)(2)PF(6) and single crystal graphite, respectively.

Co[V2]o4: a spinel approaching the itinerant electron limit.

Studies of the structure, magnetization, and resistivity under pressure on stoichiometric normal spinel Co[V(2)]O(4) single crystals show (i) absence of a structural distortion, (ii) abnormal magnetic critical exponents, and (iii) metallic conductivity induced by pressures at low temperatures. All these results prove that Co[V(2)]O(4) sits on the edge of the itinerant-electron limit. Compared with similar measurements on Fe[V(2)]O(4) and other A[V(2)]O(4) studies, it is shown that a critical V-V separation for a localized-itinerant electronic phase transition exists.

Density-of-state oscillation of quasiparticle excitation in the spin density wave phase of (TMTSF)2ClO4.

Systematic measurements of the magnetocaloric effect, heat capacity, and magnetic torque under a high magnetic field up to 35 T are performed in the spin density wave (SDW) phase of a quasi-one-dimensional organic conductor (TMTSF)2ClO4. In the SDW phase above 26 T, where the quantum Hall effect is broken, rapid oscillations (ROs) in these thermodynamic quantities are observed, which provides clear evidence of the density-of-state (DOS) oscillation near the Fermi level. The resistance is semiconducting and the heat capacity divided by temperature is extrapolated to zero at 0 K in the SDW phase, showing that all the energy bands are gapped, and there is no DOS at the Fermi level. The results show that the ROs are ascribed to the DOS oscillation of the quasiparticle excitation.

77Se and 63Cu NMR studies of the electronic correlations in CuxTiSe2 (x = 0.05, 0.07).

We report a (77)Se and (63)Cu nuclear magnetic resonance (NMR) investigation on the charge-density-wave (CDW) superconductor Cu(x)TiSe(2) (x = 0.05 and 0.07). At high magnetic fields where superconductivity is suppressed, the temperature dependence of (77)Se and (63)Cu spin-lattice relaxation rates 1/T(1) follow a linear relation. The slope of (77)Se 1/T(1) versus T increases with the Cu doping. This can be described by a modified Korringa relation which suggests the significance of electronic correlations and the Se 4p- and Ti 3d-band contribution to the density of states at the Fermi level in the studied compounds.

Pressure-dependent metallic and superconducting phases in a germanium artificial metal.

Germanium (Ge) becomes an "artificial metal" and a superconductor (T(c) approximately 5 K) above the pressure-induced semiconductor-(diamond structure)-to-metal (beta-Sn structure) transition at 10 GPa. We report single crystal resistance studies of the pressure-dependent metallic and metastable phases in the range 2.6 to 23 GPa, and show for a controlled pressure release, Ge is a metastable metal below 3 GPa. We find Ge has a superconducting upper critical field of 300 Oe (at 10.7 GPa and 1.8 K), above which a positive magnetoresistance consistent with that of a compensated closed orbit metal is observed.

Proximity detector circuits: an alternative to tunnel diode oscillators for contactless measurements in pulsed magnetic field environments.

A radio frequency oscillator circuit based on a proximity detector integrated circuit is described as an alternative for the traditional tunnel diode oscillator used for pulsed magnetic field measurements at low temperatures. The proximity detector circuit design, although less sensitive than tunnel diode oscillator circuits, has a number of essential advantages for measurements in the extreme environments of pulsed magnetic fields. These include the insensitivity of operation to voltages induced in the inductor coil, the elimination of a diode bias circuit and tuning, and a broad dynamic range of resonant frequency variation. The circuit has been successfully applied to measure the superconducting upper critical field in Ba(0.55)K(0.45)Fe2As2 single crystals up to 60 T.

Chemical pressure induced spin freezing phase transition in kagome pr langasites.

The 2D kagome system Pr3Ga5SiO14 has been previously identified as a spin-liquid candidate in zero field, displaying no magnetic long-ranged order down to at least 35 mK. Perturbations upon such systems, either under applied fields or applied pressure, should induce a spin freezing phase transition, but there are very few experimental realizations of this phenomena other than the well-studied 3D pyrochlore Tb2Ti2O7. In this Letter, we report the observation of a spin freezing phase transition in Pr3Ga5SiO14 through the application of chemical pressure--that is, through a systematic substitution on the Si site with larger ions and an elongation of the nearest-neighbor Pr-Pr distance in the kagome lattice. This results in a suppression of the T2 component of the heat capacity, and the reduction of the exchange constant eventually leads to dipolar-driven spin freezing.

Antiferromagnetic d-electron exchange via a spin-singlet pi-electron ground state in an organic conductor.

Electron spin resonance reveals the spin behavior of conduction (pi) and localized (d) electrons in beta-(BDA-TTP)2MCl4 (M=Fe, Ga). Both the Ga3+(S=0) and Fe3+(S=5/2) compounds exhibit a metal-insulator transition at 113 K with the simultaneous formation of a spin-singlet ground state in the pi electron system of the donor molecules. The behavior is consistent with charge ordering in beta-(BDA-TTP)2MCl4 at the metal-insulator transition. At 5 K, the Fe3+ compound orders antiferromagnetically, even though the pi electrons, which normally would facilitate magnetic exchange, are localized nonmagnetic singlets.

PEComa of the Upper Extremity: A Unique Case and Description of an Initial Response to Neoadjuvant Chemotherapy.

Purpose. Tumors of the perivascular epithelial cell tumor (PEComa), first described in 1992, represent a rare soft tissue neoplasm of varying malignant potential. Cases of PEComa have been previously described in a few somatic and visceral sites, most notably in the gastrointestinal tract, genitourinary tract, and one extremity case in the thigh. To date, most malignant cases of PEComa have been resistant to chemotherapy, and as such, an appropriate therapy is not known. Case report. Here we describe the first case of PEComa of the upper extremity. Open biopsy revealed a high-grade malignant lesion, and the patient subsequently underwent both neoadjuvant therapy with doxorubicin, ifosfamide and mensa, and radiation therapy prior to wide surgical resection. After six cycles of chemotherapy, the tumor underwent an 80% reduction in size. Subsequent neoadjuvant radiation therapy of 5000 cGy did not further reduce the size of the tumor. Following limb sparing radical resection, pathology showed 20% necrosis within a high-grade malignant lesion. Twenty one months after beginning treatment, the patient shows no sign of local recurrence, but metastatic disease was confirmed after resection of a lung nodule. Conclusion. Given the favorable albeit partial response seen in this patient, the course of therapy outlined here may represent a good starting point for neoadjuvant treatment in a tumor with a historically bleak prognosis. In addition, the diagnosis of PEComa must now be entertained in the differential diagnosis of upper extremity soft tissue sarcoma.

Vortex dynamics and the Fulde-Ferrell-Larkin-Ovchinnikov state in a magnetic-field-induced organic superconductor.

Under special conditions, a superconducting state where the order parameter oscillates in real space, the so-called FFLO state, is theoretically predicted to exist near the upper critical field, as first proposed by Fulde and Ferrell, and Larkin and Ovchinnikov. We report systematic measurements of the interlayer resistance in high magnetic fields to 45 T in the two-dimensional magnetic-field-induced organic superconductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. The resistance is found to show characteristic dip structures in the superconducting state. The results are consistent with pinning interactions between the vortices penetrating the insulating layers and the order parameter of the FFLO state. This gives strong evidence for an oscillating order parameter in real space.

Resonant nernst effect in the metallic and field-induced spin density wave States of (TMTSF)2ClO4.

We examine an unusual phenomenon where, in tilted magnetic fields near magic angles parallel to crystallographic planes, a "giant" resonant Nernst signal has been observed by Wu et al. [Phys. Rev. Lett. 91, 056601 (2003)] in the metallic state of an organic conducting Bechgaard salt. We show that this effect appears to be a general feature of these materials and is also present in the field-induced spin density wave phase with even larger amplitude. Our results place conditions on any model that treats the metallic state as a state with finite Cooper pairing.

Quantum oscillation of Hall resistance in the extreme quantum limit of an organic conductor (TMTSF)2ClO4.

We report resistance and magnetic torque experiments under a high magnetic field up to 45 T in a three dimensional quantum Hall (QH) system (TMTSF)(2)ClO(4), where TMTSF = tetramethyltetraselenafulvalene. The Hall resistance shows huge oscillations accompanied with sign reversal after the final QH state, where the Landau level filling factor is unity, is removed above 26 T. The magnetic torque also oscillates with the field. The results suggest that a novel quantum state, where the character of the carriers periodically changes with the field, is stabilized in the extreme quantum limit.

High magnetic field induced charge density wave state in a quasi-one-dimensional organic conductor.

The quasi-one-dimensional organic conductor (Per)2Pt(mnt)2 exhibits a charge density wave ground state below 8 K. Magnetoresistance and magnetization measurements show that the charge density wave is suppressed with magnetic fields of order 20 T, above which a high resistance state, with a cascade of subphases, appears. This new state, tentatively identified as a field induced charge density wave, reenters a low resistance state above 40 T. The results are presented in light of theoretical work [D. Zanchi et al. Phys. Rev. B 53, 1240 (1996)]] involving field induced charge density wave ground states in high magnetic fields.

Three-dimensional fermi-liquid ground state in the quasi-one-dimensional cuprate PrBa(2)Cu(4)O(8).

The interchain resistivity of PrBa(2)Cu(4)O(8) has been measured in high magnetic fields up to 30 T. Co-herent interchain transport at low temperatures is destroyed by a large magnetic field applied perpendicular to the CuO chains. Comparisons with quasiclassical transport theory provide strong experimental support for a three-dimensional Fermi-liquid ground state in PrBa(2)Cu(4)O(8), despite extreme anisotropy in its electronic properties and the presence of strong electron correlations.

MCM2 is an independent predictor of survival in patients with non-small-cell lung cancer.

PURPOSE: Minichromosome maintenance protein 2 (MCM2) is a component of the prereplicative complex. It is essential for eukaryotic DNA replication and is only expressed in proliferating cells. The prognostic utility of MCM2 compared with Ki-67, another marker of proliferating cells, on survival of patients with non-small-cell lung cancer (NSCLC) was studied. PATIENTS AND METHODS: We examined the immunohistochemical expression of MCM2 and Ki-67 in primary pathologic tumor specimens from 221 NSCLC patients. For each marker, the fraction of tumor cells with positive staining was assessed as a percentage and categorized into four groups: 0% to 24%, 25% to 49%, 50% to 74%, and > or = 75%. MCM2 and Ki-67 immunoreactivities were compared with each other, and associations with pathologic and clinical parameters predictive of survival were analyzed with the chi(2) test. Cox regression models were used to assess associations between MCM2 and Ki-67 and survival while controlling for confounders. RESULTS: Independent variables significantly associated with survival were tumor stage, performance status, and staining category. Patients with less than 25% MCM2 immunoreactivity had a longer median survival time than patients with > or = 25% MCM2 immunoreactivity (46 v 31 months; P =.039) and a lower relative risk (RR) of death (RR, 0.55, 95% confidence interval, 0.34 to 0.88). There was no significant association between survival and Ki-67 expression. CONCLUSION: Immunostaining of tumor cells for MCM2 is an independent prognostic parameter of survival for patients with NSCLC. Interpretable results can be obtained on more than 96% of paraffin-embedded specimens, and approximately 35% will be in the favorable subgroup, with less than 25% positively stained tumor cells. Whether MCM2 is predictive of response to therapy needs to be studied.

Superconductivity in an organic insulator at very high magnetic fields.

We investigate by electrical transport the field-induced superconducting state (FISC) in the organic conductor lambda-(BETS)2FeCl4. Below 4 K, antiferromagnetic-insulator, metallic, and eventually superconducting (FISC) ground states are observed with increasing in-plane magnetic field. The FISC state survives between 18 and 41 T and can be interpreted in terms of the Jaccarino-Peter effect, where the external magnetic field compensates the exchange field of aligned Fe3+ ions. We further argue that the Fe3+ moments are essential to stabilize the resulting singlet, two-dimensional superconducting state.