418 research outputs found
Phosphorus status of diverse soils in Finland as influenced by long-term P fertilisation 2.Changes of soil test values in relation to P balance with references to incorporation depth of residual and freshly applied P
Fertilising with phosphorus (P) ensures continuous supply of an essential growth factor as necessary for productive and sustainable agriculture. The amounts of P required to attain and maintain an adequate P status in the soil were investigated in field experiments at 22 sites in Finland on soils containing large amounts of residual fertiliser P. The effects of five rates (0, 15, 30, 45 and 60 kg ha-1) of annual P application were measured in the soil by chemical methods after 9 to 15 experimental years, and the changes in soil test P values (STP) were compared with P balances. Stratification of P in ley soil by broadcast application of fertilisers was assessed at four sites. The mean changes of STP in the whole topsoil caused by P fertilisation expressed as per cent of the balance difference were 3.5% (0.0159 mg dm-3)/(kg ha-1) in the acid ammonium acetate test (PAc), 4.7% (0.0214 mg dm-3)/(kg ha-1) in water extraction (Pw) and 9.7% (0.058 mg kg-1)/(kg ha-1) in sodium bicarbonate extraction (modified Olsen P). Initially high PAc values tended to slowly decrease at zero P balance, while low values did not change without some particular reason, such as soil acidification or mixing of the topsoil with some of the less fertile subsurface soil. A thin layer of the uppermost soil was quickly enriched by broadcast application of P fertiliser.;Fosforilannoituksella tehostetaan kasvintuotantoa jaturvataan vÀlttÀmÀttömÀn kasvutekijÀn jatkuva saanti kestÀvÀn maatalouden vaatimusten mukaisesti. Hyvien satojen edellyttÀmÀn maan fosforitilan saavuttamiseen ja yllÀpitoon tarvittavaa lannoitusta tutkittiin pitkÀaikaisilla kenttÀkokeilla 22 koepaikalla ominaisuuksiltaan vaihtelevilla mailla, joihin oli edellisinÀ vuosikymmeninÀ kertynyt runsaasti fosforia. Viiden vuosittain annetun fosforimÀÀrÀn (0, 15, 30, 45 ja 60 kg ha-1) vaikutuksia maan fosforitilaan tutkittiin useilla kemiallisilla menetelmillÀ 915 koevuoden jÀlkeen, ja analyysituloksia verrattiin pellon fosforitaseeseen. Nurmelle levitetyn fosforin kerrostumista tutkittiin neljÀllÀ koepaikalla. Fosforilannoituksen koko kyntökerroksessa aiheuttamat maan fosforipitoisuuden keskimÀÀrÀiset erot prosentteina fosforitaseesta olivat asetaattitestillÀ 3,5 % (0,0159 mg P dm-3 maata)/(P-taseen ero 1 kg ha-1), vesiuutolla 4,7 % (0,0214 mg P dm-3)/(kg P ha-1) ja Olsenin menetelmÀllÀ 9,7 % (0,058 mg P kg-1)/(kg P ha-1). Mailla, jotka pidÀttivÀt liukoista fosforia tehokkaimmin, enimmillÀÀn yli 500 kg ha-1 sadoissa poistuneita suuremmat fosforimÀÀrÀt eivÀt riittÀneet nostamaan asetaatti- ja vesiuutolla mÀÀritettyjÀ fosforipitoisuuksia enempÀÀ kuin hyvÀÀn kasvuun tarvittiin. Alussa korkeat asetaattiuuttoisen fosforin pitoisuudet pienenivÀt hitaasti fosforilannoituksen ollessa yhtÀ suuri kuin fosforin poistuma sadoissa, mutta pienet alkupitoisuudet eivÀt muuttuneet ilman erityistÀ syytÀ kuten maan happamoitumista ja niukkafosforisen jankon sekoittumista kyntökerrokseen. AsetaattimenetelmÀn mukaan lannoitefosforia tarvittiin maan fosforitilan yllÀpitoon keskimÀÀrin noin 10 kg ha-1 enemmÀn kuin sadoissa poistui. Tulosten mukaan syvÀllÀ perusmuokkauksella homogenisoitujen kivennÀismaiden fosforitilan hitaat ja sÀÀnnölliset muutokset voidaan mÀÀrittÀÀ riittÀvÀn tarkasti ja luotettavasti suhteellisen harvoin tehtÀvillÀ viljavuustutkimuksilla. Maatalouden ympÀristönsuojelua varten turvemaiden liukoisen fosforin pitoisuus tulisi mÀÀrittÀÀ myös muokkauskerrosta syvempÀÀ. Pintalannoitettujen nurmien ohut pintakerros rikastui paljon nopeammin kuin koko kyntökerros. Jos fosforia levitetÀÀn maan pinnalle toistuvasti ilman vÀlillÀ tehtÀvÀÀ kunnollista multausta, huuhtoutumisriskin luotettava arviointi edellyttÀÀ pintaa pitkin valuvan veden huuhtoman maan tutkimista erikseen ohuesta pintakerroksesta otetuttujen maanÀytteiden avulla
Concentration Dependence of the Effective Mass of He-3 Atoms in He-3/He-4 Mixtures
Recent measurements by Yorozu et al. (S. Yorozu, H. Fukuyama, and H.
Ishimoto, Phys. Rev. B 48, 9660 (1993)) as well as by Simons and Mueller (R.
Simons and R. M. Mueller, Czhechoslowak Journal of Physics Suppl. 46, 201
(1976)) have determined the effective mass of He-3 atoms in a He-3/He-4 mixture
with great accuracy. We here report theoretical calculations for the dependence
of that effective mass on the He-3 concentration. Using correlated basis
functions perturbation theory to infinite order to compute effective
interactions in the appropriate channels, we obtain good agreement between
theory and experiment.Comment: 4 pages, 1 figur
Stability of vortex lines in liquid 3He-4He mixtures at zero temperature
At low temperatures and 3He concentrations below 6.6 %, there is experimental
evidence about the existence in liquid helium mixtures, of stable vortices with
3He-rich cores. When the system is either supersaturated or submitted to a
tensile strength, vortices lose stability becoming metastable and eventually
completely unstable, so that their cores freely expand. Within a density
functional approach, we have determined the pressure-3He concentration curve
along which this instability appears at zero temperature.Comment: Typeset using Revtex, 9 pages and 5 Postscript figure
Single Particle and Fermi Liquid Properties of He-3/--He-4 Mixtures: A Microscopic Analysis
We calculate microscopically the properties of the dilute He-3 component in a
He-3/--He-4 mixture. These depend on both, the dominant interaction between the
impurity atom and the background, and the Fermi liquid contribution due to the
interaction between the constituents of the He-3 component. We first calculate
the dynamic structure function of a He-3 impurity atom moving in He-3. From
that we obtain the excitation spectrum and the momentum dependent effective
mass. The pole strength of this excitation mode is strongly reduced from the
free particle value in agreement with experiments; part of the strength is
distributed over high frequency excitations. Above k > 1.7^{-1}$ the
motion of the impurity is damped due to the decay into a roton and a low energy
impurity mode. Next we determine the Fermi--Liquid interaction between He-4
atoms and calculate the pressure-- and concentration dependence of the
effective mass, magnetic susceptibility, and the He-3--He-3 scattering phase
shifts. The calculations are based on a dynamic theory that uses, as input,
effective interactions provided by the Fermi hypernetted--chain theory. The
relationship between both theories is discussed. Our theoretical effective
masses agree well with recent measurements by Yorozu et al. (Phys. Rev. B 48,
9660 (1993)) as well as those by R. Simons and R. M. Mueller (Czekoslowak
Journal of Physics Suppl. 46, 201 (1996)), but our analysis suggests a new
extrapolation to the zero-concentration limit. With that effective mass we also
find a good agreement with the measured Landau parameter F_0^a.Comment: 47 pages, 15 figure
Statistical properties of hybrid estimators proposed for GEDI â NASAâs Global Ecosystem Dynamics Investigation
NASAâs Global Ecosystem Dynamics Investigation (GEDI) mission will collect waveform lidar data at a dense sample of âŒ25 m footprints along ground tracks paralleling the orbit of the International Space Station (ISS). GEDIâs primary science deliverable will be a 1 km grid of estimated mean aboveground biomass density (Mg ha ^â1 ), covering the latitudes overflown by ISS (51.6 °S to 51.6 °N). One option for using the sample of waveforms contained within an individual grid cell to produce an estimate for that cell is hybrid inference, which explicitly incorporates both sampling design and model parameter covariance into estimates of variance around the population mean. We explored statistical properties of hybrid estimators applied in the context of GEDI, using simulations calibrated with lidar and field data from six diverse sites across the United States. We found hybrid estimators of mean biomass to be unbiased and the corresponding estimators of variance appeared to be asymptotically unbiased, with under-estimation of variance by approximately 20% when data from only two clusters (footprint tracks) were available. In our study areas, sampling error contributed more to overall estimates of variance than variability due to the model, and it was the design-based component of the variance that was the source of the variance estimator bias at small sample sizes. These results highlight the importance of maximizing GEDIâs sample size in making precise biomass estimates. Given a set of assumptions discussed here, hybrid inference provides a viable framework for estimating biomass at the scale of a 1 km grid cell while formally accounting for both variability due to the model and sampling error
High miR-30 Expression Associates with Improved Breast Cancer Patient Survival and Treatment Outcome
Deregulated miRNA expression has been suggested in several stages of breast cancer pathogenesis. We have studied the miR-30 family, in particular miR-30d, in relation to breast cancer patient survival and treatment outcomes. With tumor specimens from 1238 breast cancer patients, we analyzed the association of miR-30d expression with tumor characteristics with the 5-year occurrence of breast cancer-specific death or distant metastasis (BDDM), and with 10-year breast cancer survival (BCS). We conducted a two-stage drug-screen to investigate the impact of miR-30 family members (miR-30a-30e) on sensitivity to doxorubicin and lapatinib in six breast cancer cell lines HCC1937, HCC1954, MDA-MB-361, MCF7, MDA-MB-436 and CAL-120, using drug sensitivity scores (DSS) to compare the miR-30 family mimics to their specific inhibitors. The study was complemented with Ingenuity Pathway Analysis (IPA) with the METABRIC data. We found that while high miR-30d expression is typical for aggressive tumors, it predicts better metastasis-free (pBDDM = 0.035, HR = 0.63, 95% CI = 0.4â0.9) and breast cancer-specific survival (pBCS = 0.018, HR = 0.61, 95% CI = 0.4â0.9), especially in HER2-positive (pBDDM = 0.0009), ER-negative (pBDDM = 0.003), p53-positive (pBDDM = 0.011), and highly proliferating (pBDDM = 0.0004) subgroups, and after adjuvant chemotherapy (pBDDM = 0.035). MiR-30d predicted survival independently of standard prognostic markers (pBDDM = 0.0004). In the drug-screening test, the miR-30 family sensitized the HER2-positive HCC1954 cell line to lapatinib (p < 10â2) and HCC1937, MDA-MB-361, MDA-MB-436 and CAL120 to doxorubicin (p < 10â4) with an opposite impact on MCF7. According to the pathway analysis, the miR-30 family has a suppressive effect on cell motility and metastasis in breast cancer. Our results suggest prognostic and predictive potential for the miR-30 family, which warrants further investigation
High miR-30 Expression Associates with Improved Breast Cancer Patient Survival and Treatment Outcome
Deregulated miRNA expression has been suggested in several stages of breast cancer pathogenesis. We have studied the miR-30 family, in particular miR-30d, in relation to breast cancer patient survival and treatment outcomes. With tumor specimens from 1238 breast cancer patients, we analyzed the association of miR-30d expression with tumor characteristics with the 5-year occurrence of breast cancer-specific death or distant metastasis (BDDM), and with 10-year breast cancer survival (BCS). We conducted a two-stage drug-screen to investigate the impact of miR-30 family members (miR-30a-30e) on sensitivity to doxorubicin and lapatinib in six breast cancer cell lines HCC1937, HCC1954, MDA-MB-361, MCF7, MDA-MB-436 and CAL-120, using drug sensitivity scores (DSS) to compare the miR-30 family mimics to their specific inhibitors. The study was complemented with Ingenuity Pathway Analysis (IPA) with the METABRIC data. We found that while high miR-30d expression is typical for aggressive tumors, it predicts better metastasis-free (pBDDM = 0.035, HR = 0.63, 95% CI = 0.4â0.9) and breast cancer-specific survival (pBCS = 0.018, HR = 0.61, 95% CI = 0.4â0.9), especially in HER2-positive (pBDDM = 0.0009), ER-negative (pBDDM = 0.003), p53-positive (pBDDM = 0.011), and highly proliferating (pBDDM = 0.0004) subgroups, and after adjuvant chemotherapy (pBDDM = 0.035). MiR-30d predicted survival independently of standard prognostic markers (pBDDM = 0.0004). In the drug-screening test, the miR-30 family sensitized the HER2-positive HCC1954 cell line to lapatinib (p < 10â2) and HCC1937, MDA-MB-361, MDA-MB-436 and CAL120 to doxorubicin (p < 10â4) with an opposite impact on MCF7. According to the pathway analysis, the miR-30 family has a suppressive effect on cell motility and metastasis in breast cancer. Our results suggest prognostic and predictive potential for the miR-30 family, which warrants further investigation
Somatic mutations and T-cell clonality in patients with immunodeficiency
Common variable immunodeficiency (CVID) and other late-onset immunodeficiencies often co-manifest with autoimmunity and lymphoproliferation. The pathogenesis of most cases is elusive, as only a minor subset harbors known monogenic germline causes. The involvement of both B and T cells is, however, implicated. To study whether somatic mutations in CD4(+) and CD8(+) T cells associate with immunodeficiency, we recruited 17 patients and 21 healthy controls. Eight patients had late-onset CVID and nine patients other immunodeficiency and/or severe autoimmunity. In total, autoimmunity occurred in 94% and lymphoproliferation in 65%. We performed deep sequencing of 2,533 immune-associated genes from CD4(+) and CD8(+) cells. Deep T-cell receptor b-sequencing was used to characterize CD4(+) and CD8(+) T-cell receptor repertoires. The prevalence of somatic mutations was 65% in all immunodeficiency patients, 75% in CVID, and 48% in controls. Clonal hematopoiesis-associated variants in both CD4(+)and CD8(+) cells occurred in 24% of immunodeficiency patients. Results demonstrated mutations in known tumor suppressors, oncogenes, and genes that are critical for immuneand proliferative functions, such as STAT5B (2 patients), C5AR1 (2 patients), KRAS (one patient), and NOD2 (one patient). Additionally, as a marker of T-cell receptor repertoire perturbation, CVID patients harbored increased frequencies of clones with identical complementarity determining region 3 sequences despite unique nucleotide sequences when compared to controls. In conclusion, somatic mutations in genes implicated for autoimmunity and lymphoproliferation are common in CD4(+) and CD8(+) cells of patients with immunodeficiency. They may contribute to immune dysregulation in a subset of immunodeficiency patients.Peer reviewe
Systematic bioinformatic analysis of expression levels of 17,330 human genes across 9,783 samples from 175 types of healthy and pathological tissues
Our knowledge on tissue- and disease-specific functions of human genes is rather limited and highly context-specific. Here, we have developed a method for the comparison of mRNA expression levels of most human genes across 9,783 Affymetrix gene expression array experiments representing 43 normal human tissue types, 68 cancer types, and 64 other diseases. This database of gene expression patterns in normal human tissues and pathological conditions covers 113 million datapoints and is available from the GeneSapiens website
The progamic phase of an early-divergent angiosperm, Annona cherimola (Annonaceae)
33 Pag.
The definitive version, with the figures, is available at:
http://aob.oxfordjournals.org/Background and Aims: Recent studies of reproductive biology in ancient angiosperm lineages are beginning to shed light on the early evolution of flowering plants, but comparative studies are restricted by fragmented and meagre species representation in these angiosperm clades. In the present study, the progamic phase, from pollination to fertilization, is characterized in Annona cherimola, which is a member of the Annonaceae, the largest extant family among early-divergent angiosperms. Beside interest due to its phylogenetic position, this species is also an ancient crop with a clear niche for expansion in subtropical climates.
Methods: The kinetics of the reproductive process was established following controlled pollinations and sequential fixation. Gynoecium anatomy, pollen tube pathway, embryo sac and early post-fertilization events were characterized histochemically.
Key Results: A plesiomorphic gynoecium with a semi-open carpel shows a continuous secretory papillar surface along the carpel margins, which run from the stigma down to the obturator in the ovary. The pollen grains germinate in the stigma and compete in the stigma-style interface to reach the narrow secretory area that lines the margins of the semi-open stylar canal and is able to host just one to three pollen tubes. The embryo sac has eight nuclei and is well provisioned with large starch grains that are used during early cellular endosperm development.
Conclusions: A plesiomorphic simple gynoecium hosts a simple pollenâpistil interaction, based on a supportâcontrol system of pollen tube growth. Support is provided through basipetal secretory activity in the cells that line the pollen tube pathway. Spatial constraints, favouring pollen tube competition, are mediated by a dramatic reduction in the secretory surface available for pollen tube growth at the stigmaâstyle interface. This extramural pollen tube competition contrasts with the intrastylar competition predominant in more recently derived lineages of angiosperms.This work was supported by the Spanish Ministry of Education (Project Grants AGL2004-02290/AGR, AGL2006-13529 and AGL2007-60130/AGR), GIC-AragĂłn 43, Junta de AndalucĂa (AGR2742), and the European Union under the INCO-DEV program (Contract 015100). J.L. was supported by a grant from Junta de AndalucĂa.Peer reviewe
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