Evolution of magnetic surfboards and spin glass behavior in (Fe1-pGap)2TiO5.

The unusual anisotropy of the spin glass (SG) transition in the pseudobrookite system Fe2TiO5has been interpreted as arising from an induced, van der Waals-like, interaction among magnetic clusters. Here we present susceptibility (χ) and specific heat data (C) for Fe2TiO5diluted with non-magnetic Ga, (Fe1-pGap)2TiO5, for disorder parameterp= 0, 0.11, and 0.42, and elastic neutron scattering data forp= 0.20. A uniform suppression ofTgis observed upon increasingp, along with a value ofχTgthat increases asTgdecreases, i.e.dχ(Tg)/dTg<0We also observeCT∝T2in the low temperature limit. The observed behavior places (Fe1-pGap)2TiO5in the category of a strongly geometrically frustrated SG.

Tomonaga-Luttinger liquid behavior and spinon confinement in YbAlO3.

Low dimensional quantum magnets are interesting because of the emerging collective behavior arising from strong quantum fluctuations. The one-dimensional (1D) S = 1/2 Heisenberg antiferromagnet is a paradigmatic example, whose low-energy excitations, known as spinons, carry fractional spin S = 1/2. These fractional modes can be reconfined by the application of a staggered magnetic field. Even though considerable progress has been made in the theoretical understanding of such magnets, experimental realizations of this low-dimensional physics are relatively rare. This is particularly true for rare-earth-based magnets because of the large effective spin anisotropy induced by the combination of strong spin-orbit coupling and crystal field splitting. Here, we demonstrate that the rare-earth perovskite YbAlO3 provides a realization of a quantum spin S = 1/2 chain material exhibiting both quantum critical Tomonaga-Luttinger liquid behavior and spinon confinement-deconfinement transitions in different regions of magnetic field-temperature phase diagram.

Scaling of Memories and Crossover in Glassy Magnets.

Glassiness is ubiquitous and diverse in characteristics in nature. Understanding their differences and classification remains a major scientific challenge. Here, we show that scaling of magnetic memories with time can be used to classify magnetic glassy materials into two distinct classes. The systems studied are high temperature superconductor-related materials, spin-orbit Mott insulators, frustrated magnets, and dilute magnetic alloys. Our bulk magnetization measurements reveal that most densely populated magnets exhibit similar memory behavior characterized by a relaxation exponent of [Formula: see text]. This exponent is different from [Formula: see text] of dilute magnetic alloys that was ascribed to their hierarchical and fractal energy landscape, and is also different from [Formula: see text] of the conventional Debye relaxation expected for a spin solid, a state with long range order. Furthermore, our systematic study on dilute magnetic alloys with varying magnetic concentration exhibits crossovers among the two glassy states and spin solid.

CD45 regulates GM-CSF, retinoic acid and T-cell homing in intestinal inflammation.

CD45 is a leukocyte-specific tyrosine phosphatase important for T-cell development, and as a result, CD45-/- mice have substantially reduced numbers of T cells. Here we show that, upon dextran sodium sulfate (DSS)-induced colitis, CD45-/- mice have equivalent intestinal pathology and T-cell numbers in their colon as C57BL/6 mice and show enhanced weight loss. CD45-/- mice have a greater percentage of α4ß7+ T cells prior to and after colitis and an increased percentage of T cells producing inflammatory cytokines in the inflamed colon, suggesting that CD45-/- effector T cells preferentially home to the intestine. In DSS-induced colitis in CD45RAG-/- mice lacking an adaptive immune system, CD45 was required for optimal granulocyte-macrophage colony-stimulating factor (GM-CSF) and retinoic acid (RA) production by innate immune cells. Addition of CD45+/+ T cells led to greater weight loss in the RAG-/- mice compared with CD45RAG-/- mice that correlated with reduced α4ß7+ T cells and lower recruitment to the colon of CD45RAG-/- mice in DSS-induced colitis. Addition of exogenous GM-CSF to CD45RAG-/- mice rescued RA production, increased colonic T-cell numbers, and increased weight loss. This demonstrates opposing effects of CD45 in innate and adaptive immune cells in proinflammatory responses and the expression of the gut-homing molecule, α4ß7.

Assessing causes of quality deterioration of groundwater in Puttalam, Sri Lanka, using isotope and hydrochemical tools.

Extensive extraction of groundwater has resulted in deterioration of the groundwater quality in the Puttalam area in the northwestern coastal zone of Sri Lanka. This situation led us to carry out the present comprehensive study based on environmental isotopic ((18)O, (2)H, (3)H) and geochemical evaluation to understand the root cause for water quality deterioration. The isotopic data suggest that the surface water and shallow groundwaters are subjected to intensive evaporation and, as a result, increase in their salinity. Deep groundwater of the area is mostly recharged by direct infiltration of rainwater and at few places by nearby surface water bodies. The salinity increase of deep groundwater depends on the specific hydrogeological zones and would be due to dissolution of salts which are precipitated in soil through the seawater spray over the time, dissolution of minerals in geological matrix and leaching of salts from salterns. The quality of the deep groundwater is relatively good in the granitic gneiss zone and nearby areas outside the sedimentary aquifer. There is no evidence from isotope and hydrogeochemical evaluation for seawater intrusion into groundwater in the Puttalam area.

Size of Sri Lankan newborns at birth.

This prospective population-based study, involving 4,120 births at the Maternity Unit, Teaching Hospital Kandy, in the years 2008 and 2009, was undertaken to determine the mean birth weight of the newborns in the Central Province, Sri Lanka. The mean birth weight of 2,854 g was found to be equivalent with those calculated from several earlier studies. The mean differences in the birth weights of the three major ethnic communities, the Sinhala, the Tamils and the Sri Lankan Moors, were found to be not statistically significant. The gender difference of 60 g (CI 28-92) and the difference between the birth weights of the first and second born, for babies of all three communities were statistically significant, in uniform with those for white Caucasian populations. A graphical production of the mean birth weights is depicted in percentiles, with the mean birth weights of newborns in the UK superimposed on it for comparison.

Deletion of PI3K-p85alpha gene impairs lineage commitment, terminal maturation, cytokine generation and cytotoxicity of NK cells.

Class IA phosphotidylinositol-3-kinases (PI3Ks) are a family of p85/p110 heterodimeric lipid kinases that are important in regulating signaling events in B and T cells. However, their role in natural killer (NK) cells is not understood. Here, using mice that lack the regulatory p85alpha subunit and its alternatively spliced variants p55alpha/p50alpha (collectively termed as p85alpha(-/-)), we defined the role of PI3K in NK cell development and function. p85alpha(-/-) mice had impaired lineage commitment leading to reduced NK cellularity in the bone marrow and liver. p85alpha(-/-) NK cells showed a defective Ly49 subset specification and a decreased expression of CD43. Lack of p85alpha severely reduced the NK-mediated cytotoxicity against tumor cells representing 'induced-self' and 'missing-self'. More importantly, NKG2D and NK1.1 receptor-mediated cytokine and chemokine generation was significantly compromised in p85alpha(-/-) NK cells. These results reveal a previously unrecognized role of p85alpha in the development, terminal maturation, cytokine/chemokine generation and tumor clearance of NK cells.

Vein Loading in Seedlings of Phaseolus vulgaris Exposed to Excess Cobalt, Nickel, and Zinc.

Vein loading in unifoliate leaves of white bean seedlings exposed to excess Co(2+), Ni(2+), or Zn(2+) for 1 to 4 days was studied by incubating leaf discs in [(14)C]sucrose. The discs from plants exposed to metal exhibited an increased total uptake of radiosucrose but reduced vein loading. Differences between treatments due to infiltration of disc margins were eliminated by analyzing 7-millimeter discs cut from the center of incubated 14-millimeter discs. Uptake of radiosucrose was greater particularly in discs from seedlings exposed to excess Ni(2+) and Zn(2+). The effect increased as exposure of the seedlings to metal increased up to 4 days. Autoradiographs showed vein loading in control leaf tissues with most of the radiosucrose accumulating in minor veins and little remaining in the mesophyll. In discs from metal-treated plants, most of the sucrose remained in the mesophyll without accumulating preferentially in the minor veins. This effect was evident within 24 hours of exposure to excess metal and intensified with longer exposures to metal. The inhibition of vein loading was also evident in situ. Both the preferential accumulation of sucrose into the minor veins of control tissues and the accumulation into mesophyll of metal exposed tissues were sensitive to 2,4-dinitrophenol and the blockage of sulfhydryl groups. It is concluded that the inhibition of vein loading contributes markedly to the observed toxicological effects of reduced photoassimilate export and of accumulation of carbohydrates in fully expanded leaves of bean seedlings exposed to excess metal ions.

Carbohydrate Levels and Photoassimilate Export from Leaves of Phaseolus vulgaris Exposed to Excess Cobalt, Nickel, and Zinc.

Exposure of white bean seedlings to phytotoxic burdens of Co, Ni, or Zn reduced the export of (14)C-photoassimilates from the nearly fully expanded unifoliate leaves. Little (14)C reached the major sink areas, the young trifoliate leaves and the root tips, of seedlings exposed to metal. The unifoliate leaves accumulated sucrose, reducing sugars, and starch. These effects were evident within 1 or 2 days.