Metastability in zero-temperature dynamics: Statistics of attractors

The zero-temperature dynamics of simple models such as Ising ferromagnets provides, as an alternative to the mean-field situation, interesting examples of dynamical systems with many attractors (absorbing configurations, blocked configurations, zero-temperature metastable states). After a brief review of metastability in the mean-field ferromagnet and of the droplet picture, we focus our attention onto zero-temperature single-spin-flip dynamics of ferromagnetic Ising models. The situations leading to metastability are characterized. The statistics and the spatial structure of the attractors thus obtained are investigated, and put in perspective with uniform a priori ensembles. We review the vast amount of exact results available in one dimension, and present original results on the square and honeycomb lattices.Comment: 21 pages, 6 figures. To appear in special issue of JPCM on Granular Matter edited by M. Nicodem

Directional emission of light from a nano-optical Yagi-Uda antenna

The plasmon resonance of metal nanoparticles can enhance and direct light from optical emitters in much the same way that radio frequency (RF) antennas enhance and direct the emission from electrical circuits. In the RF regime, a typical antenna design for high directivity is the Yagi-Uda antenna, which basically consists of a one-dimensional array of antenna elements driven by a single feed element. Here, we present the experimental demonstration of directional light emission from a nano-optical Yagi-Uda antenna composed of an array of appropriately tuned gold nanorods. Our results indicate that nano-optical antenna arrays are a simple but efficient tool for the spatial control of light emission.Comment: 4 pages, including 4 figure

Fabrication of magnetic and photocatalytic polyamide fabric coated with Fe2O3 particles

Hematite (alpha-Fe₂O₃) particles are prepared and synchronously deposited on the surface of polyamide (PA) fabric using ferric sulfate as the precursor, sodium hydroxide as the precipitant, and sodium dodecyl benzene sulfonate as the dispersant in a low temperature hydrothermal process. The Fe₂O₃ coated PA fabric is then modified with silane coupling agent Z-6040. The Fe₂O₃ coated PA fabric and remaining particles are systematically characterized by different techniques, such as small-spot micro X-ray fluorescence (μ-XRF), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), diffuse reflectance spectrum (DRS), and vibrating sample magnetometer (VSM). The properties of tensile, durable washing and photocatalytic activity are investigated. The experimental results show that Fe₂O₃ particles composed of nanoparticles having the average crystallite size of 37.8 nm are grafted onto PA fabric and enhanced by coupling agent via the C-Fe, O-Fe and Si-O-Fe bonds. It is found that, after treatments, the thermal stability of PA fabric hardly changes; the visible light absorption capability and magnetism are gained; and the tensile property decreases slightly. It is also confirmed that the Fe₂O₃ coated PA fabric can withstand the repeated washings up to 20 times and photodegrade the adsorbed methyl orange (MO) exposed to ultraviolet (UV) irradiation. Therefore, the present method provides a new strategy for the production of durable magnetic fabric

The ‘Biophilic Organization’: An Integrative Metaphor for Corporate Sustainability

This paper proposes a new organizational metaphor, the ‘Biophilic Organization’, which aims to counter the bio-cultural disconnection of many organizations despite their espoused commitment to sustainability. This conceptual research draws on multiple disciplines such as evolutionary psychology and architecture to not only develop a diverse bio-cultural connection but to show how this connection tackles sustainability, in a holistic and systemic sense. Moreover, the paper takes an integrative view of sustainability, which effectively means that it embraces the different emergent tensions. Three specific tensions are explored: efficiency versus resilience, organizational versus personal agendas and isomorphism versus institutional change. In order to illustrate how the Biophilic Organization could potentially provide a synthesis strategy for such tensions, healthcare examples are drawn from the emerging fields of Biophilic Design in Singapore and Generative Design in the U.S.A. Finally, an example is provided which highlights how a Taoist cultural context has impacted on a business leader in China, to illustrative the significance of a transcendent belief system to such a bio-cultural narrative

Investigation of spin excitations and charge order in bulk crystals of the infinite-layer nickelate LaNiO2_2

Recent x-ray spectroscopic studies have revealed spin excitations and charge density waves in thin films of infinite-layer (IL) nickelates. However, clarifying whether the origin of these phenomena is intrinsic to the material class or attributable to impurity phases in the films has presented a major challenge. Here we utilize topotactic methods to synthesize bulk crystals of the IL nickelate LaNiO$_2$ with crystallographically oriented surfaces. We examine these crystals using resonant inelastic x-ray scattering (RIXS) at the Ni $L_3$-edge to elucidate the spin and charge correlations in the bulk of the material. While we detect the presence of prominent spin excitations in the crystals, fingerprints of charge order are absent at the ordering vectors identified in previous in thin-film studies. These results contribute to the understanding of the bulk properties of LaNiO$_2$ and establish topotactically synthesized crystals as viable complementary specimens for spectroscopic investigations.Comment: 11 pages, 7 figures with supplemental material

Salvinorin A Regulates Dopamine Transporter Function Via A Kappa Opioid Receptor and ERK1/2-Dependent Mechanism

Salvinorin A (SalA), a selective κ-opioid receptor (KOR) agonist, produces dysphoria and pro-depressant like effects. These actions have been attributed to inhibition of striatal dopamine release. The dopamine transporter (DAT) regulates dopamine transmission via uptake of released neurotransmitter. KORs are apposed to DAT in dopamine nerve terminals suggesting an additional target by which SalA modulates dopamine transmission. SalA produced a concentration-dependent, nor-binaltorphimine (BNI)- and pertussis toxin-sensitive increase of ASP+ accumulation in EM4 cells coexpressing myc-KOR and YFP-DAT, using live cell imaging and the fluorescent monoamine transporter substrate, trans 4-(4-(dimethylamino)-styryl)-N-methylpyridinium) (ASP+). Other KOR agonists also increased DAT activity that was abolished by BNI pretreatment. While SalA increased DAT activity, SalA treatment decreased serotonin transporter (SERT) activity and had no effect on norepinephrine transporter (NET) activity. In striatum, SalA increased the Vmax for DAT mediated DA transport and DAT surface expression. SalA up-regulation of DAT function is mediated by KOR activation and the KOR-linked extracellular signal regulated kinase-½ (ERK1/2) pathway. Co-immunoprecipitation and BRET studies revealed that DAT and KOR exist in a complex. In live cells, DAT and KOR exhibited robust FRET signals under basal conditions. SalA exposure caused a rapid and significant increase of the FRET signal. This suggests that the formation of KOR and DAT complexes is promoted in response to KOR activation. Together, these data suggest that enhanced DA transport and decreased DA release resulting in decreased dopamine signaling may contribute to the dysphoric and pro-depressant like effects of SalA and other KOR agonists

Lumbar hernia diagnosed after laparoscopic hiatal hernia surgery

The presence of a new lumbar swelling or pain in the postoperative period following laparoscopic surgery should raise the suspicion of a lumbar hernia. Cross‐sectional imaging can be used to establish an early diagnosis to enable successful management

Systematic profiling of DNMT3A variants reveals protein instability mediated by the DCAF8 E3 ubiquitin ligase adaptor

Clonal hematopoiesis is a prevalent age-related condition associated with greatly increased risk of hematologic disease; mutations in DNA methyltransferase 3A (DNMT3A) are the most common driver of this state. DNMT3A variants occur across the gene with some particularly associated with malignancy, but the functional relevance and mechanisms of pathogenesis of the majority of mutations is unknown. Here, we systematically investigated the methyltransferase activity and protein stability of 253 disease-associated DNMT3A mutations, finding that 74% were loss-of-function mutations. Half of these variants exhibited reduced protein stability and, as a class, correlated with greater clonal expansion and AML development. We investigated the mechanisms underlying the instability using a CRISPR screen and uncovered regulated destruction of DNMT3A mediated by the DCAF8 E3 ubiquitin ligase adaptor. We establish a new paradigm to classify novel variants that has prognostic and potential therapeutic significance for patients with hematologic disease