Penrose-Onsager Criterion Validation in a One-Dimensional Polariton Condensate

We perform quantum tomography on one-dimensional polariton condensates, spontaneously occurring in linear disorder valleys in a CdTe planar microcavity sample. By the use of optical interferometric techniques, we determine the first-order coherence function and the amplitude and phase of the order parameter of the condensate, providing a full reconstruction of the single particle density matrix for the polariton system. The experimental data are used as input to theoretically test the consistency of Penrose-Onsager criterion for Bose-Einstein condensation in the framework of nonequilibrium polariton condensates. The results confirm the pertinence and validity of the criterion for a non equilibrium condensed gas.Comment: 5 pages, 4 figure

Relevance of the Heisenberg-Kitaev model for the honeycomb lattice iridates A_2IrO_3

Combining thermodynamic measurements with theoretical density functional and thermodynamic calculations we demonstrate that the honeycomb lattice iridates A2IrO3 (A = Na, Li) are magnetically ordered Mott insulators where the magnetism of the effective spin-orbital S = 1/2 moments can be captured by a Heisenberg-Kitaev (HK) model with Heisenberg interactions beyond nearest-neighbor exchange. Experimentally, we observe an increase of the Curie-Weiss temperature from \theta = -125 K for Na2IrO3 to \theta = -33 K for Li2IrO3, while the antiferromagnetic ordering temperature remains roughly the same T_N = 15 K for both materials. Using finite-temperature functional renormalization group calculations we show that this evolution of \theta, T_N, the frustration parameter f = \theta/T_N, and the zig-zag magnetic ordering structure suggested for both materials by density functional theory can be captured within this extended HK model. Combining our experimental and theoretical results, we estimate that Na2IrO3 is deep in the magnetically ordered regime of the HK model (\alpha \approx 0.25), while Li2IrO3 appears to be close to a spin-liquid regime (0.6 < \alpha < 0.7).Comment: Version accepted for publication in PRL. Additional DFT and thermodynamic calculations have been included. 6 pages of supplementary material include

Metastasis of hormone-independent breast cancer to lung and bone is decreased by α-difluoromethylornithine treatment

INTRODUCTION: Polyamines affect proliferation, differentiation, migration and apoptosis of cells, indicating their potential as a target for cancer chemotherapy. Ornithine decarboxylase converts ornithine to putrescine and is the rate-limiting step in polyamine synthesis. α-Difluoromethylornithine (DFMO) irreversibly inhibits ornithine decarboxylase and MDA-MB-435 human breast cancer metastasis to the lung without blocking orthotopic tumor growth. This study tested the effects of DFMO on orthotopic tumor growth and lung colonization of another breast cancer cell line (MDA-MB-231) and the effects on bone metastasis of MDA-MB-435 cells. METHODS: MDA-MB-231 cells were injected into the mammary fat pad of athymic mice. DFMO treatment (2% per orally) began at the day of tumor cell injection or 21 days post injection. Tumor growth was measured weekly. MDA-MB-231 cells were injected into the tail vein of athymic mice. DFMO treatment began 7 days prior to injection, or 7 or 14 days post injection. The number and incidence of lung metastases were determined. Green fluorescent protein-tagged MDA-MB-435 cells were injected into the left cardiac ventricle in order to assess the incidence and extent of metastasis to the femur. DFMO treatment began 7 days prior to injection. RESULTS: DFMO treatment delayed MDA-MB-231 orthotopic tumor growth to a greater extent than growth of MDA-MB-435 tumors. The most substantial effect on lung colonization by MDA-MB-231 cells occurred when DFMO treatment began 7 days before intravenous injection of tumor cells (incidence decreased 28% and number of metastases per lung decreased 35–40%). When DFMO treatment began 7 days post injection, the incidence and number of metastases decreased less than 10%. Surprisingly, treatment initiated 14 days after tumor cell inoculation resulted in a nearly 50% reduction in the number of lung metastases without diminishing the incidence. After intracardiac injection, DFMO treatment decreased the incidence of bone metastases (55% vs 87%) and the area occupied by the tumor (1.66 mm(2 )vs 4.51 mm(2), P < 0.05). CONCLUSION: Taken together, these data demonstrate that DFMO exerts an anti-metastatic effect in more than one hormone-independent breast cancer, for which no standard form of biologically-based treatment exists. Importantly, the data show that DFMO is effective against metastasis to multiple sites and that treatment is generally more effective when administered early

A Tchebycheffian extension of multi-degree B-splines: Algorithmic computation and properties

In this paper we present an efficient and robust approach to compute a normalized B-spline-like basis for spline spaces with pieces drawn from extended Tchebycheff spaces. The extended Tchebycheff spaces and their dimensions are allowed to change from interval to interval. The approach works by constructing a matrix that maps a generalized Bernstein-like basis to the B-spline-like basis of interest. The B-spline-like basis shares many characterizing properties with classical univariate B-splines and may easily be incorporated in existing spline codes. This may contribute to the full exploitation of Tchebycheffian splines in applications, freeing them from the restricted role of an elegant theoretical extension of polynomial splines. Numerical examples are provided that illustrate the procedure described

Crystal field splitting and correlation effect on the electronic structure of A2IrO3

The electronic structure of the honeycomb lattice iridates Na2IrO3 and Li2IrO3 has been investigated using resonant inelastic x-ray scattering (RIXS). Crystal-field split d-d excitations are resolved in the high-resolution RIXS spectra. In particular, the splitting due to non-cubic crystal fields, derived from the splitting of j_eff=3/2 states, is much smaller than the typical spin-orbit energy scale in iridates, validating the applicability of j_eff physics in A2IrO3. We also find excitonic enhancement of the particle-hole excitation gap around 0.4 eV, indicating that the nearest-neighbor Coulomb interaction could be large. These findings suggest that both Na2IrO3 and Li2IrO3 can be described as spin-orbit Mott insulators, similar to the square lattice iridate Sr2IrO4

A new geometric description for Igusa's modular form (azy)5(azy)_5

The modular form $(azy)_5$ notably appears in one of Igusa's classic structure theorems as a generator of the ring of full modular forms in genus 2, being exhibited by means of a complicated algebraic expression. In this work a different description for this modular form is provided by resorting to a peculiar geometrical approach.Comment: 10 page

Promoter methylation and downregulated expression of the TBX15 gene in ovarian carcinoma.

TBX15 is a gene involved in the development of mesodermal derivatives. As the ovaries and the female reproductive system are of mesodermal origin, the aim of the present study was to determine the methylation status of the TBX15 gene promoter and the expression levels of TBX15 in ovarian carcinoma, which is the most lethal and aggressive type of gynecological tumor, in order to determine the role of TBX15 in the pathogenesis of ovarian carcinoma. This alteration could be used to predict tumor development, progression, recurrence and therapeutic effects. The study was conducted on 80 epithelial ovarian carcinoma and 17 control cases (normal ovarian and tubal tissues). TBX15 promoter methylation was first determined by pyrosequencing following bisulfite modification, then by cloning and sequencing, in order to obtain information about the epigenetic haplotype. Immunohistochemical analysis was performed to evaluate the correlation between the methylation and protein expression levels. Data revealed a statistically significant increase of the TBX15 promoter region methylation in 82% of the tumor samples and in various histological subtypes. Immunohistochemistry showed an inverse correlation between methylation levels and the expression of the TBX15 protein. Furthermore, numerous tumor samples displayed varying degrees of intratumor heterogeneity. Thus, the present study determined that ovarian carcinoma typically expresses low levels of TBX15 protein, predominantly due to an epigenetic mechanism. This may have a role in the pathogenesis of ovarian carcinoma independent of the histological subtype

Transcriptional variation of sensory-related genes in natural populations of Aedes albopictus

BACKGROUND: The Asian tiger mosquito, Aedes albopictus, is a highly dangerous invasive vector of numerous medically important arboviruses including dengue, chikungunya and Zika. In four decades it has spread from tropical Southeast Asia to many parts of the world in both tropical and temperate climes. The rapid invasion process of this mosquito is supported by its high ecological and genetic plasticity across different life history traits. Our aim was to investigate whether wild populations, both native and adventive, also display transcriptional genetic variability for functions that may impact their biology, behaviour and ability to transmit arboviruses, such as sensory perception. RESULTS: Antennal transcriptome data were derived from mosquitoes from a native population from Ban Rai, Thailand and from three adventive Mediterranean populations: Athens, Greece and Arco and Trento from Italy. Clear inter-population differential transcriptional activity was observed in different gene categories related to sound perception, olfaction and viral infection. The greatest differences were detected between the native Thai and the Mediterranean populations. The two Italian populations were the most similar. Nearly one million quality filtered SNP loci were identified. CONCLUSION: The ability to express this great inter-population transcriptional variability highlights, at the functional level, the remarkable genetic flexibility of this mosquito species. We can hypothesize that the differential expression of genes, including those involved in sensory perception, in different populations may enable Ae. albopictus to exploit different environments and hosts, thus contributing to its status as a global vector of arboviruses of public health importance. The large number of SNP loci present in these transcripts represents a useful addition to the arsenal of high-resolution molecular markers and a resource that can be used to detect selective pressure and adaptive changes that may have occurred during the colonization process