Structure of pregna-4,16-diene-7[alpha],14[alpha]-diol-3,20-dione

7a,14a-Dihydroxypregna-4,16-diene-3,20- dione, C21H2804, M r = 344.45, orthorhombic, P212121, a = 7.136 (1), b = 12.342 (1), c = 20.049 (3)/k, V= 1765.7 (3)/k 3, Z = 4, Dx = 1.295 g cm -3, A(Cu Kte) = 1.5418/k, /z = 6.7 cm- a, F(000) = 744, T = 293 K, R = 0.048 for 1345 observations. The A ring may be described as in a l a,2flhalf- chair conformation or a l a-sofa conformation. The B and C rings adopt normal chair conformations and the D ring has a 14a-envelope conforma tion. The molecules are held together by a hydrogen bond [0(3)...0(7)= 2.767 A].

Onttojen puiden lahopuukovakuoriaiset — kolmen pyydystyypin vertailu

Vanhat ja ontot puut ovat tärkeä elinympäristö monelle lahopuusta riippuvaiselle eliölajille. Onttoihin puihin on erikoistunut suuri määrä myös vaarantuneita ja harvinaisia hyönteislajeja, jotka elävät puun onkalon seinämillä tai onkalon pohjalle kerääntyvässä orgaanisessa aineksessa, ns. mulmissa. Tutkimuksen tavoitteena oli selvittää, mikä kolmesta pyydystyypistä (ikkuna-, vuoka- ja kuoppapyydys) soveltuu parhaiten onttojen puiden lahopuukovakuoriaisten pyyntiin. Lisäksi tavoitteena oli kartoittaa hyönteisnäytteiden ensimmäiseen laboratoriokäsittelyyn vaadittua aikaa. Tutkimuksessa oli mukana vanhoja rungostaan onttoutuneita lehmuksia, tammia ja vaahteroita pääkaupunkiseudun puisto- ja kartanoalueilta. Puiden onkaloiden sisään aseteltiin ikkuna-, vuoka- ja kuoppapyydyksiä, kaksi kutakin tyyppiä ja ne tyhjennettiin kolmen viikon välein touko-heinäkuussa 2006. Pyydyksiä oli siis yhteensä 90 per pyyntijakso. Kun näytteistä eroteltiin halutut hyönteislahkot (mukaanlukien kovakuoriaiset) niiden käsittelyyn käytetty aika kirjattiin ylös. Aineistosta tunnistettiin yhteensä 3825 kovakuoriaisyksilöä ja 212 lajia, joista lahopuusta riippuvaisia oli yhteensä 3398 yksilöä ja 121 lajia. Ikkunapyydyksissä esiintyi yhteensä 1639 yksilöä ja 140 lajia, vuokapyydyksissä 1506 yksilöä ja 134 lajia, kuoppapyydyksissä 680 yksilöä ja 111 lajia. Näytteiden käsittelyaikojen keskiarvot olivat 48,3 minuuttia ikkunapyydykselle, 65,5 minuuttia vuokapyydykselle ja 34,1 kuoppapyydykselle. Lajistokoostumuksen huomioiva ?-diversiteetti erosi huomattavasti pyydysten välillä, se oli 36,5 % ikkuna- ja vuokapyydysten välillä, 13,1 % ikkuna- ja kuoppapyydysten välillä ja 14,2 % vuoka- ja kuoppapyydysten välillä. Ikkuna- ja vuokapyydysten välillä ei havaittu tilastollisesti merkitsevää eroa saproksyylilajien (p<0,05), -yksilöiden (p<0,05) tai käsittelyaikojen (p<0,05) keskiarvoissa. Ikkuna- ja vuokapyydyksillä saatiin keskimäärin selvästi enemmän saproksyylilajeja ja –yksilöitä kuoppapyydykseen verrattuna. Kuoppapyydyksellä saatiin kokonaisyksilömäärään verrattuna suhteellisesti vähemmän saproksyylejä (59 %) kuin ikkuna- (69 %) ja vuokapyydyksillä (71 %). Ikkunapyydykset olivat tehokkain pyydystyyppi vertailtaessa pyydysten keräämää saproksyyliyksilömäärää suhteessa aineiston käsittelyn vaatimaan aikaan. Tehokkuus (yksilöä minuutissa) ikkunapyydykselle oli 0,74, vuokapyydykselle 0,43 ja kuoppapyydykselle 0,21. Ikkunapyydyksiä ei ole aikaisemmin käytetty puun onkalon sisällä hyönteisiä pyydettäessä vaan ne ovat aikaisemmissa tutkimuksissa roikkuneet onkalon ulkopuolella. Ikkunapyydykset kuitenkin toimivat erinomaisesti myös onkaloiden sisällä. Ikkuna- sekä vuokapyydys toimivatkin selkeästi paremmin lahopuukovakuoriaisten pyynnissä verrattuna kuoppapyydykseen, jonka poisjättäminen olisi kuitenkin tuottanut huomattavasti lajiköyhemmän aineiston. Mahdollisimman monimuotoisen onttojen puiden lahopuukovakuoriaislajiston keräämiseksi tulisi käyttää ikkuna- tai vuokapyydyksiä yhdessä kuoppapyydysten kanssa.

Excitation and correlation of N-14 overtone transitions and measurement of heteronuclear dipolar coupling using DAPT

For studying systems containing nitrogen, limited use of N-14 NMR spectroscopy has been made because of the large quadrupolar interaction experienced by the N-14 nucleus and the absence of a central transition. To overcome the above problem, use of overtone spectroscopy has been suggested. Though this approach has limited applicability for powder samples due to second order quadrupole broadening, it is useful for studying oriented samples and single crystals. Here, we demonstrate the use of the recently proposed dipolar assisted polarization transfer (DAPT) pulse scheme for exciting the overtone transitions. The pulse sequence may also be utilized as a two-dimensional experiment to obtain H-1-N-14 dipolar couplings and H-1 chemical shifts. (C) 2010 Elsevier B.V. All rights reserved.

Synthesis and characterization of poly(vinyl acetate peroxide)

Poly(vinyl acetate peroxide) (PVACP) was prepared from vinyl acetate by free-radical-initiated oxidative polymerization. The polyperoxide was isolated and characterized by different spectroscopic methods. The extreme instability of PVACP was demonstrated by FTIR spectroscopy. The H-1- and C-13-NMR studies show the irregularities in the polyperoxide chain due to the cleavage reactions of the propagating peroxide radical. Thermal degradation studies using differential scanning calorimetry revealed that PVACP degrades at a lower temperature and the heat of degradation is in the same range as reported for other vinyl polyperoxides. (C) 1996 John Wiley & Sons, Inc.

The reaction of lambda 3-cyclotriphosphazanes with tetrachloro-ortho-benzoquinone: An unusual ring contraction-rearrangement

Oxidative addition of tetrachloro-ortho-benzoquinone to lambda(3)-cyclotriphosphazanes, [EtNP(OR)](3) results in an unprecedented ring contraction-rearrangement to give diazadiphosphetidines (EtN)(2)[P(OR)(O2C6Cl4)] [P(O2C6Cl4)-[N(Et)P(OR)(2)}] (R = C6H4Br-4 or C(6)H(3)Me(2)-2,6), a process indicated to be thermodynamically favourable on the basis of PM3 calculations.

Spin distributions in antiferromagnetically coupled Mn2+Cu2+ systems: from the pair to the infinite chain

Probably the most informative description of the ground slate of a magnetic molecular species is provided by the spin density map. Such a map may be experimentally obtained from polarized neutron diffraction (PND) data or theoretically calculated using quantum chemical approaches. Density functional theory (DFT) methods have been proved to be well-adapted for this. Spin distributions in one-dimensional compounds may also be computed using the density matrix renormalization group (DMRG) formalism. These three approaches, PND, DFT, and DMRG, have been utilized to obtain new insights on the ground state of two antiferromagnetically coupled Mn2+Cu2+ compounds, namely [Mn(Me-6-[14]ane-N-4)Cu(oxpn)](CF3SO3)(2) and MnCu(pba)(H2O)(3) . 2H(2)O, with Me-6-[14]ane-N-4 = (+/-)-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, oxpn = N,N'-bis(3-aminopropyl)oxamido and pba = 1,3-propylenebis(oxamato). Three problems in particular have been investigated: the spin distribution in the mononuclear precursors [Cu(oxpn)] and [Cu(pba)](2-), the spin density maps in the two Mn2+Cu2+ compounds, and the evolution of the spin distributions on the Mn2+ and Cu2+ sites when passing from a pair to a one-dimensional ferrimagnet.

Rossby waves in May and the Indian summer monsoon rainfall

Large amplitude stationary Rossby wave trains with wavelength in the range 50 degrees to 60 degrees longitude have been identified in the upper troposphere during May, through the analysis of 200 hPa wind anomalies. The spatial phase of these waves has been shown to differ by about 20 degrees of longitude between the dry and wet Indian monsoon years. It has been shown empirically that the Rossby waves are induced by the heat sources in the ITCZ. These heat sources appear in the Bay of Bengal and adjoining regions in May just prior to the onset of the Indian summer monsoon. The inter-annual spatial phase shift of the Rossby waves has been shown to be related to the shift in the deep convection in the zonal direction.

Precoder Designs for MIMO Broadcast Channels with Imperfect CSI

[1] D. Tse and P. Viswanath, Fundamentals of Wireless Communication.Cambridge University Press, 2006. [2] H. Bolcskei, D. Gesbert, C. B. Papadias, and A.-J. van der Veen, Spacetime Wireless Systems: From Array Processing to MIMO Communications.Cambridge University Press, 2006. [3] Q. H. Spencer, C. B. Peel, A. L. Swindlehurst, and M. Haardt, “An introduction to the multiuser MIMO downlink,” IEEE Commun. Mag.,vol. 42, pp. 60–67, Oct. 2004. [4] K. Kusume, M. Joham,W. Utschick, and G. Bauch, “Efficient tomlinsonharashima precoding for spatial multiplexing on flat MIMO channel,”in Proc. IEEE ICC’2005, May 2005, pp. 2021–2025. [5] R. Fischer, C. Windpassinger, A. Lampe, and J. Huber, “MIMO precoding for decentralized receivers,” in Proc. IEEE ISIT’2002, 2002, p.496. [6] M. Schubert and H. Boche, “Iterative multiuser uplink and downlink beamforming under SINR constraints,” IEEE Trans. Signal Process.,vol. 53, pp. 2324–2334, Jul. 2005. [7] ——, “Solution of multiuser downlink beamforming problem with individual SINR constraints,” IEEE Trans. Veh. Technol., vol. 53, pp.18–28, Jan. 2004. [8] A. Wiesel, Y. C. Eldar, and Shamai, “Linear precoder via conic optimization for fixed MIMO receivers,” IEEE Trans. Signal Process., vol. 52,pp. 161–176, Jan. 2006. [9] N. Jindal, “MIMO broadcast channels with finite rate feed-back,” in Proc. IEEE GLOBECOM’2005, Nov. 2005. [10] R. Hunger, F. Dietrich, M. Joham, and W. Utschick, “Robust transmit zero-forcing filters,” in Proc. ITG Workshop on Smart Antennas, Munich,Mar. 2004, pp. 130–137. [11] M. B. Shenouda and T. N. Davidson, “Linear matrix inequality formulations of robust QoS precoding for broadcast channels,” in Proc.CCECE’2007, Apr. 2007, pp. 324–328. [12] M. Payaro, A. Pascual-Iserte, and M. A. Lagunas, “Robust power allocation designs for multiuser and multiantenna downlink communication systems through convex optimization,” IEEE J. Sel. Areas Commun.,vol. 25, pp. 1392–1401, Sep. 2007. [13] M. Biguesh, S. Shahbazpanahi, and A. B. Gershman, “Robust downlink power control in wireless cellular systems,” EURASIP Jl. Wireless Commun. Networking, vol. 2, pp. 261–272, 2004. [14] B. Bandemer, M. Haardt, and S. Visuri, “Liner MMSE multi-user MIMO downlink precoding for users with multple antennas,” in Proc.PIMRC’06, Sep. 2006, pp. 1–5. [15] J. Zhang, Y. Wu, S. Zhou, and J. Wang, “Joint linear transmitter and receiver design for the downlink of multiuser MIMO systems,” IEEE Commun. Lett., vol. 9, pp. 991–993, Nov. 2005. [16] S. Shi, M. Schubert, and H. Boche, “Downlink MMSE transceiver optimization for multiuser MIMO systems: Duality and sum-mse minimization,”IEEE Trans. Signal Process., vol. 55, pp. 5436–5446, Nov.2007. [17] A. Mezghani, M. Joham, R. Hunger, and W. Utschick, “Transceiver design for multi-user MIMO systems,” in Proc. WSA 2006, Mar. 2006. [18] R. Doostnejad, T. J. Lim, and E. Sousa, “Joint precoding and beamforming design for the downlink in a multiuser MIMO system,” in Proc.WiMob’2005, Aug. 2005, pp. 153–159. [19] N. Vucic, H. Boche, and S. Shi, “Robust transceiver optimization in downlink multiuser MIMO systems with channel uncertainty,” in Proc.IEEE ICC’2008, Beijing, China, May 2008. [20] A. Ben-Tal and A. Nemirovsky, “Selected topics in robust optimization,”Math. Program., vol. 112, pp. 125–158, Feb. 2007. [21] D. Bertsimas and M. Sim, “Tractable approximations to robust conic optimization problems,” Math. Program., vol. 107, pp. 5–36, Jun. 2006. [22] P. Ubaidulla and A. Chockalingam, “Robust Transceiver Design for Multiuser MIMO Downlink,” in Proc. IEEE Globecom’2008, New Orleans, USA, Dec. 2008, to appear. [23] S. Boyd and L. Vandenberghe, Convex Optimization. Cambridge University Press, 2004. [24] G. H. Golub and C. F. V. Loan, Matrix Computations. The John Hopkins University Press, 1996.

Mechanism of Fragility at BCL2 Gene Minor Breakpoint Cluster Region during t(14;18) Chromosomal Translocation

The t(14;18) translocation in follicular lymphoma is one of the most common chromosomal translocations. Breaks in chromosome 18 are localized at the 3'-UTR of BCL2 gene or downstream and are mainly clustered in either the major breakpoint region or the minor breakpoint cluster region (mcr). The recombination activating gene (RAG) complex induces breaks at IgH locus of chromosome 14, whereas the mechanism of fragility at BCL2 mcr remains unclear. Here, for the first time, we show that RAGs can nick mcr; however, the mechanism is unique. Three independent nicks of equal efficiency are generated, when both Mg2+ and Mn2+ are present, unlike a single nick during V(D)J recombination. Further, we demonstrate that RAG binding and nicking at the mcr are independent of nonamer, whereas a CCACCTCT motif plays a critical role in its fragility, as shown by sequential mutagenesis. More importantly, we recapitulate the BCL2 mcr translocation and find that mcr can undergo synapsis with a standard recombination signal sequence within the cells, in a RAG-dependent manner. Further, mutation to the CCACCTCT motif abolishes recombination within the cells, indicating its vital role. Hence, our data suggest a novel, physiologically relevant, nonamer-independent mechanism of RAG nicking at mcr, which may be important for generation of chromosomal translocations in humans.

Potential G-quadruplex formation at breakpoint regions of chromosomal translocations in cancer may explain their fragility

Genetic alterations like point mutations, insertions, deletions, inversions and translocations are frequently found in cancers. Chromosomal translocations are one of the most common genomic aberrations associated with nearly all types of cancers especially leukemia and lymphoma. Recent studies have shown the role of non-B DNA structures in generation of translocations. In the present study, using various bioinformatic tools, we show the propensity of formation of different types of altered DNA structures near translocation breakpoint regions. In particular, we find close association between occurrence of G-quadruplex forming motifs and fragile regions in almost 70% of genes involved in rearrangements in lymphoid cancers. However, such an analysis did not provide any evidence for the occurrence of G-quadruplexes at the close vicinity of translocation breakpoint regions in nonlymphoid cancers. Overall, this study will help in the identification of novel non-B DNA targets that may be responsible for generation of chromosomal translocations in cancer. (C) 2012 Elsevier Inc. All rights reserved.

NMR Analysis of Cross Strand Aromatic Interactions in an 8 Residue Hairpin and a 14 Residue Three Stranded beta-Sheet Peptide

Cross strand aromatic interactions between a facing pair of phenylalanine residues in antiparallel beta-sheet structures have been probed using two structurally defined model peptides. The octapeptide Boc-(LFVPPLFV)-P-D-P-L-OMe (peptide 1) favors the beta-hairpin conformation nucleated by the type II' beta-turn formed by the (D)Pro-(L)Pro segment, placing Phe2 and Phe7 side chains in proximity. Two centrally positioned (D)Pro-(L)Pro segments facilitate the three stranded beta-sheet formation in the 14 residue peptide Boc-LFV(D)P(L)PLFVA(D)P(L)PLFV-OMe (peptide 2) in which the Phe2/Phe7 orientations are similar to that in the octapeptide. The anticipated folded conformations of peptides 1 and 2 are established by the delineation of intramolecularly hydrogen bonded NH groups and by the observation of specific cross strand NOEs. The observation of ring current shifted aromatic protons is a diagnostic of close approach of the Phe2 and Phe7 side chains. Specific assignment of aromatic proton resonances using HSQC and HSQC-TOCSY methods allow an analysis of interproton NOEs between the spatially proximate aromatic rings. This approach facilitates specific assignments in systems containing multiple aromatic rings in spectra at natural abundance. Evidence is presented for a dynamic process which invokes a correlated conformational change about the C-alpha-C-beta(chi(1)) bond for the pair of interacting Phe residues. NMR results suggest that aromatic ring orientations observed in crystals are maintained in solution. Anomalous temperature dependence of ring current induced proton chemical shifts suggests that solvophobic effects may facilitate aromatic ring clustering in apolar solvents.

High-temperature, high-pressure granulites (retrogressed eclogites) in the central region of the Lewisian, NW Scotland: Crustal-scale subduction in the Neoarchaean

Eclogites and associated high-pressure (HP) rocks in collisional and accretionary orogenic belts preserve a record of subduction and exhumation, and provide a key constraint on the tectonic evolution of the continents. Most eclogites that formed at high pressures but low temperatures at > 10-11 kbar and 450-650 degrees C can be interpreted as a result of subduction of cold oceanic lithosphere. A new class of high-temperature (HT) eclogites that formed above 900 degrees C and at 14 to 30 kbar occurs in the deep continental crust, but their geodynamic significance and processes of formation are poorly understood. Here we show that Neoarchaean mafic-ultramafic complexes in the central granulite facies region of the Lewisian in NW Scotland contain HP/HT garnet-bearing granulites (retrogressed eclogites), gabbros, Iherzolites, and websterites, and that the HP granulites have garnets that contain inclusions of omphacite. From thermodynamic modeling and compositional isopleths we calculate that peak eclogite-facies metamorphism took place at 24-22 kbar and 1060-1040 degrees C. The geochemical signature of one (G-21) of the samples shows a strong depletion of Eu indicating magma fractionation at a crustal level. The Sm-Nd isochron ages of HP phases record different cooling ages of ca. 2480 and 2330 Ma. We suggest that the layered mafic-ultramafic complexes, which may have formed in an oceanic environment, were subducted to eclogite depths, and exhumed as HP garnet-bearing orogenic peridotites. The layered complexes were engulfed by widespread orthogneisses of tonalite-trondhjemite-granodiorite (TTG) composition with granulite facies assemblages. We propose two possible tectonic models: (1) the fact that the relicts of eclogitic complexes are so widespread in the Scourian can be taken as evidence that a >90 km x 40 km-size slab of continental crust containing mafic-ultramafic complexes was subducted to at least 70 km depth in the late Archaean. During exhumation the gneiss protoliths were retrogressed to granulite facies assemblages, but the mafic-ultramafic rocks resisted retrogression. (2) The layered complexes of mafic and ultramafic rocks were subducted to eclogite-facies depths and during exhumation under crustal conditions they were intruded by the orthogneiss protoliths (TTG) that were metamorphosed in the granulite facies. Apart from poorly defined UHP metamorphic rocks in Norway, the retrogressed eclogites in the central granulite/retrogressed eclogite facies Lewisian region, NW Scotland have the highest crustal pressures so far reported for Archaean rocks, and demonstrate that lithospheric subduction was transporting crustal rocks to HP depths in the Neoarchaean. (C) 2012 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Spark plasma sintering may lead to phase instability and inferior mechanical properties: A case study with TiB2

In contrast to the widely reported beneficial aspects of spark plasma sintering in developing materials with better properties, we report here two interesting aspects recorded with difficult-to-sinter titanium diboride: (a) in situ formation of second phase (TiB) and (b) inferior hardness (by similar to 30%) and elastic modulus (by similar to 20%) for spark plasma sintered TiB2, with respect to hot pressed TiB2. The formation of TiB is discussed with reference to the enhanced reaction kinetics in the presence of pulsed electric field. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Variation at Diabetes- and Obesity-Associated Loci May Mirror Neutral Patterns of Human Population Diversity and Diabetes Prevalence in India

South Asian populations harbor a high degree of genetic diversity, due in part to demographic history. Two studies on genome-wide variation in Indian populations have shown that most Indian populations show varying degrees of admixture between ancestral north Indian and ancestral south Indian components. As a result of this structure, genetic variation in India appears to follow a geographic cline. Similarly, Indian populations seem to show detectable differences in diabetes and obesity prevalence between different geographic regions of the country. We tested the hypothesis that genetic variation at diabetes-and obesity-associated loci may be potentially related to different genetic ancestries. We genotyped 2977 individuals from 61 populations across India for 18 SNPs in genes implicated in T2D and obesity. We examined patterns of variation in allele frequency across different geographical gradients and considered state of origin and language affiliation. Our results show that most of the 18 SNPs show no significant correlation with latitude, the geographic cline reported in previous studies, or by language family. Exceptions include KCNQ1 with latitude and THADA and JAK1 with language, which suggests that genetic variation at previously ascertained diabetes-associated loci may only partly mirror geographic patterns of genome-wide diversity in Indian populations.