An effective palynological preparation procedure using hydrogen peroxide

Most pre-Quaternary palynology samples are currently prepared by demineralization of the sediment/sedimentary rock matrix using hydrochloric and hydrofluoric acids (HCl and HF respectively). If a consistently effective alternative to this procedure can be developed, palynological processing will be made significantly less hazardous to both laboratory personnel, and to the wider environment. Furthermore, most non-acid processing methods are normally quicker and cheaper than matrix dissolution using acid. Some authors have previously used hydrogen peroxide (H2O2) to extract palynomorphs by the physico–chemical disaggregation of the clay fraction. However, H2O2 is a powerful oxidizing agent and hence can potentially destroy sedimentary organic material, including palynomorphs. A new method using hot H2O2, where exposure of the sample material to the H2O2 is minimized, has been developed. Crushed sample material in a suitable vessel is placed on a hot plate for one minute, treated with 15–30% H2O2 for 10 minutes, then the residue is diluted with cold distilled water. Disaggregated sample material tends to float, and is decanted into a large vessel containing distilled water to further dilute the H2O2. If any undisaggregated sample remains, the procedure is repeated several times if necessary. Relatively indurated sedimentary lithotypes normally require several treatments. The reason for this stepwise treatment is that the organic material is not exposed to H2O2 for sustained periods, thereby reducing the possibility of palynomorph damage/degradation due to oxidation. When the sample matrix has been fully disaggregated, the residue can be further processed as appropriate. In this study, eight samples of Carboniferous, Jurassic, Paleogene, and Quaternary age were prepared quantitatively using the new H2O2 method. These were all prepared using 30% H2O2. For comparison, they were also prepared quantitatively using HCl/HF and/or sodium hexametaphosphate [(NaPO3)6]. Quantitative preparations allow the concentration of palynomorphs extracted to be determined, and therefore the effectiveness of the techniques used can be compared objectively. The palynomorph residues derived from these three techniques varied markedly. The H2O2 method does not consistently disaggregate all the sample material, particularly the older and more indurated lithotypes. Some evidence of oxidation effects was observed. Two samples of Mississippian mudstone from the U.S.A. were prepared using H2O2 and (NaPO3)6. Both methods produced abundant miospores, however the H2O2 procedure yielded far higher palynomorph concentrations than the (NaPO3)6 technique. Minor degradation of palynomorphs in the H2O2 preparation was noted. The H2O2 and HCl/HF methods were compared directly on a palynomorph-rich sample of Upper Carboniferous mudstone from offshore Scotland. Both preparations produced abundant miospores. The HCl/HF method had significantly higher recovery levels than the H2O2 procedure. It appears that the H2O2 method simultaneously macerates the matrix, and oxidizes any amorphous organic material (AOM) present. In this sample, the HCl/HF residue was relatively rich in AOM. By contrast, the H2O2 preparation is virtually clear of this phytoclast type, which partially obscures palynomorphs. Two samples of the Middle Jurassic Grantham Formation of eastern England were processed using H2O2 and HCl/HF. The two methods produced abundant palynofloras of similar palynomorph concentrations. Two dinoflagellate cyst acmes within the Danian (Paleogene) part of the López de Bertodano Formation of Seymour Island, Antarctica were also tested using H2O2, (NaPO3)6, and HCl/HF. TheH2O2 preparation completely destroyed the dominant taxon, Palaeoperidinium pyrophorum, in one sample. By contrast, the (NaPO3)6 and HCl/HF preparations produced abundant, fully representative palynofloras. In the other sample, the acme of Spinidinium spp. is completely unaffected by the H2O2 preparation procedure. The final sample of this study is an unconsolidated clay of Late Pleistocene age from offshore Scotland. Both the H2O2 and HCl/HF preparations proved similar in both taxonomic content and overall palynomorph yield. The new method of preparation using hot H2O2 has proved to be extremely effective. In particular, it appears to be superior to the (NaPO3)6 procedure for indurated lithotypes. However care should be taken because H2O2 can destroy certain dinoflagellate cysts and kerogen macerals which are especially susceptible to oxidation. Further development work, and more comparative testing of the H2O2, (NaPO3)6, and HCl/HF procedures, should be undertaken

SMEs and access to finance : an investigation of different sources of funding

Access to finance is a necessity for the start-up, growth, innovation and survival of any organisation. As a result, access to finance has become an important theme in small business research. Although there is overwhelming research evidence on access to finance, there are still research gaps in the knowledge base of different forms of access to finance, especially in times of uncertainty and economic distress. Specifically, more research is needed on the identification of relevant theories of access to finance, the role of venture capital and crowdfunding, the effect of financial education and self-confidence on access to micro finance and the role of institutions in small firms financial liquidity. The thesis aims to fill these gaps and provide comprehensive reviews and new empirical evidence related to the above issues. Reviewing the academic literature, this research supports the view that venture capital and crowdfunding are both relevant in access to funding for firms as they represent worthy alternatives for different types of firms. Venture capital firms (VCF) have targeted their investment on later-stage, management buy-out and buy-in to limit their risks and increase returns. Although VCF traditionally have huge appetite for high risk and high returns, research show that they concentrate their funding on older innovative firms. In their risk aversion, VCF have become more stringent in their entrepreneurial project selection and monitoring with reduced funding of seed and early stage of projects. Turning to empirical parts of the thesis, a series of interesting and new findings have emerged. First, this thesis supports the view that financial self-confidence of the owner manager contributes to successful access to finance for UK firms whereas financial education is found to have weak explanatory power. However, financial education is found to increase financial self-confidence, and thus can be used as a means of improving access to micro-finance for SMEs. Self-confidence is also found to be affected by past poor performance of the owners’ credit outcomes stressing the importance of building a successful credit history and experience with the financial sector. Finally, at international level this thesis stresses the importance of regulation and institutions in Baltic States and South Caucasus countries in SME access to finance. The analysis points also towards some gender differences which add to the existing debate on differences between males and females

Double π0\pi^0 Photoproduction off the Proton at Threshold

The reaction $\gamma p \to \pi^0 \pi^0 p$ has been measured using the TAPS BaF$_2$ calorimeter at the tagged photon facility of the Mainz Microtron accelerator. Chiral perturbation theory (ChPT) predicts that close to threshold this channel is significantly enhanced compared to double pion final states with charged pions. In contrast to other reaction channels, the lower order tree terms are strongly suppressed in 2$\pi^0$ photoproduction. The consequence is the dominance of pion loops in the 2$\pi^0$ channel close to threshold - a result that opens new prospects for the test of ChPT and in particular its inherent loop terms. The present measurement is the first which is sensitive enough for a conclusive comparison with the ChPT calculation and is in agreement with its prediction. The data also show good agreement with a calculation in the unitary chiral approach.Comment: Submitted to PL

Crystal structure of chlorido-methanol-(N-(2-(oxy)-3-methoxybenzylidene)pyridine-4-carbohydrazonato-κ3O,N,O′)-(4-methylphenyl)methyl-tin(IV), C23H24ClN3O4Sn

C23H24ClN3O4Sn, triclinic, P¯1 (no. 2), a=9.7536(2) Å, b=10.0755(2) Å, c=12.4215(3) Å, α=84.928(2)°, β=72.544(2)°, γ=74.382(2)°, V =1121.44(4) Å3, Z =2, Rgt(F)=0.021, wRref(F2)=0.054, T =100(2) K

A comprehensive analysis of the contributions to the nonlinear optical properties of thin Ag films

© 2010 American Institute of Physics. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1063/1.3429118DOI: 10.1063/1.3429118The nonlinear optical properties of 20 nm thick Ag films are investigated by time-resolved white- light continuum pump-probe experiments in both transmission and reflection mode. The dynamics of changes in permittivity Δε are measured at wavelengths between 500 to 700 nm. The data is fitted to a modified Drude model in the frequency domain and to a two-temperature model in the time domain. Changes in the individual Drude parameters are calculated as a function of time. A single, coherent model is proposed based on these fittings that describes the dynamics of the nonlinear optical properties of Ag, which could be used to model the nonlinear responses of multilayer structures containing thin films of Ag. The physical origins of the observed responses are discussed

Perspectives on the design and methodology of periconceptional nutrient supplementation trials.

Periconceptional supplementation could extend the period over which maternal and fetal nutrition is improved, but there are many challenges facing early-life intervention studies. Periconceptional trials differ from pregnancy supplementation trials, not only because of the very early or pre-gestational timing of nutrient exposure but also because they generate subsidiary information on participants who remain non-pregnant. The methodological challenges are more complex although, if well designed, they provide opportunities to evaluate concurrent hypotheses related to the health of non-pregnant women, especially nulliparous adolescents. This review examines the framework of published and ongoing randomised trial designs. Four cohorts typically arise from the periconceptional trial design--two of which are non-pregnant and two are pregnant--and this structure provides assessment options related to pre-pregnant, maternal, pregnancy and fetal outcomes. Conceptually the initial decision for single or micronutrient intervention is central--as is the choice of dosage and content--in order to establish a comparative framework across trials, improve standardisation, and facilitate interpretation of mechanistic hypotheses. Other trial features considered in the review include: measurement options for baseline and outcome assessments; adherence to long-term supplementation; sample size considerations in relation to duration of nutrient supplementation; cohort size for non-pregnant and pregnant cohorts as the latter is influenced by parity selection; integrating qualitative studies and data management issues. Emphasis is given to low resource settings where high infection rates and the possibility of nutrient-infection interactions may require appropriate safety monitoring. The focus is on pragmatic issues that may help investigators planning a periconceptional trial

Nucleon Structure Functions from Relativistic Constituent Quarks

We investigate deep inelastic lepton scattering from the nucleon within a constituent quark picture, in which the internal structure of constituent quarks is modeled by meson and diquark dressing. In a covariant framework this structure leads to a breakdown of the factorization necessary for a convolution formulation. We perform our analysis in time-ordered perturbation theory in the infinite momentum frame where factorization of subprocesses is automatic. Numerical results are compared with recent data on valence quark distributions in the proton.Comment: 10 pages LaTeX, 3 figures available upon request, TPR-94-7, to appear in Physics Letters

Haloperidol and Ziprasidone for Treatment of Delirium in Critical Illness

BACKGROUND: There are conflicting data on the effects of antipsychotic medications on delirium in patients in the intensive care unit (ICU). METHODS: In a randomized, double-blind, placebo-controlled trial, we assigned patients with acute respiratory failure or shock and hypoactive or hyperactive delirium to receive intravenous boluses of haloperidol (maximum dose, 20 mg daily), ziprasidone (maximum dose, 40 mg daily), or placebo. The volume and dose of a trial drug or placebo was halved or doubled at 12-hour intervals on the basis of the presence or absence of delirium, as detected with the use of the Confusion Assessment Method for the ICU, and of side effects of the intervention. The primary end point was the number of days alive without delirium or coma during the 14-day intervention period. Secondary end points included 30-day and 90-day survival, time to freedom from mechanical ventilation, and time to ICU and hospital discharge. Safety end points included extrapyramidal symptoms and excessive sedation. RESULTS: Written informed consent was obtained from 1183 patients or their authorized representatives. Delirium developed in 566 patients (48%), of whom 89% had hypoactive delirium and 11% had hyperactive delirium. Of the 566 patients, 184 were randomly assigned to receive placebo, 192 to receive haloperidol, and 190 to receive ziprasidone. The median duration of exposure to a trial drug or placebo was 4 days (interquartile range, 3 to 7). The median number of days alive without delirium or coma was 8.5 (95% confidence interval [CI], 5.6 to 9.9) in the placebo group, 7.9 (95% CI, 4.4 to 9.6) in the haloperidol group, and 8.7 (95% CI, 5.9 to 10.0) in the ziprasidone group (P=0.26 for overall effect across trial groups). The use of haloperidol or ziprasidone, as compared with placebo, had no significant effect on the primary end point (odds ratios, 0.88 [95% CI, 0.64 to 1.21] and 1.04 [95% CI, 0.73 to 1.48], respectively). There were no significant between-group differences with respect to the secondary end points or the frequency of extrapyramidal symptoms. CONCLUSIONS: The use of haloperidol or ziprasidone, as compared with placebo, in patients with acute respiratory failure or shock and hypoactive or hyperactive delirium in the ICU did not significantly alter the duration of delirium. (Funded by the National Institutes of Health and the VA Geriatric Research Education and Clinical Center; MIND-USA ClinicalTrials.gov number, NCT01211522 .)

Indications of suppressed high p_T hadron production in nucleus-nucleus collisions at CERN-SPS

Inclusive pion production at high transverse momenta (p_T > 2 GeV/c) in nucleus-nucleus (A+A) collisions at CERN SPS (sqrt(s_NN)~20 GeV) is revisited and systematically compared to all existing proton-proton data in the same range of center-of-mass energies. The ratio of A+A to p+p pion cross-sections (nuclear modification factor) for 0-8% central Pb+Pb, Pb+Au and S+Au reactions does not show a strong enhancement as a function of p_T as previously found, but is consistent with scaling with the number of nucleon-nucleon (NN) collisions. Neutral pion yields per NN collision in head-on Pb+Pb reactions are suppressed, whereas peripheral yields are enhanced. These results together indicate that some amount of ``jet quenching'' may already be present in central heavy-ion reactions at sqrt(s_NN)~20 GeV.Comment: Updated versions of Figs. 1,2 and 4. Minor text modification

High-performance transistors for bioelectronics through tuning of channel thickness.

UNLABELLED: Despite recent interest in organic electrochemical transistors (OECTs), sparked by their straightforward fabrication and high performance, the fundamental mechanism behind their operation remains largely unexplored. OECTs use an electrolyte in direct contact with a polymer channel as part of their device structure. Hence, they offer facile integration with biological milieux and are currently used as amplifying transducers for bioelectronics. Ion exchange between electrolyte and channel is believed to take place in OECTs, although the extent of this process and its impact on device characteristics are still unknown. We show that the uptake of ions from an electrolyte into a film of poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate ( PEDOT: PSS) leads to a purely volumetric capacitance of 39 F/cm(3). This results in a dependence of the transconductance on channel thickness, a new degree of freedom that we exploit to demonstrate high-quality recordings of human brain rhythms. Our results bring to the forefront a transistor class in which performance can be tuned independently of device footprint and provide guidelines for the design of materials that will lead to state-of-the-art transistor performance