Impossibility of independence amplification in Kolmogorov complexity theory

The paper studies randomness extraction from sources with bounded independence and the issue of independence amplification of sources, using the framework of Kolmogorov complexity. The dependency of strings $x$ and $y$ is ${\rm dep}(x,y) = \max\{C(x) - C(x \mid y), C(y) - C(y\mid x)\}$, where $C(\cdot)$ denotes the Kolmogorov complexity. It is shown that there exists a computable Kolmogorov extractor $f$ such that, for any two $n$-bit strings with complexity $s(n)$ and dependency $\alpha(n)$, it outputs a string of length $s(n)$ with complexity $s(n)- \alpha(n)$ conditioned by any one of the input strings. It is proven that the above are the optimal parameters a Kolmogorov extractor can achieve. It is shown that independence amplification cannot be effectively realized. Specifically, if (after excluding a trivial case) there exist computable functions $f_1$ and $f_2$ such that ${\rm dep}(f_1(x,y), f_2(x,y)) \leq \beta(n)$ for all $n$-bit strings $x$ and $y$ with ${\rm dep}(x,y) \leq \alpha(n)$, then $\beta(n) \geq \alpha(n) - O(\log n)$

Carbon-nitrogen interactions in European forests and semi-natural vegetation - Part 2: Untangling climatic, edaphic, management and nitrogen deposition effects on carbon sequestration potentials

The effects of atmospheric nitrogen deposition (N$_{dep}$) on carbon (C) sequestration in forests have often been assessed by relating differences in productivity to spatial variations of N$_{dep}$ across a large geographic domain. These correlations generally suffer from covariation of other confounding variables related to climate and other growth-limiting factors, as well as large uncertainties in total (dry+wet) reactive nitrogen (N$_{r}$) deposition.We propose a methodology for untangling the effects of N$_{dep}$ from those of meteorological variables, soil water retention capacity and stand age, using a mechanistic forest growth model in combination with eddy covariance CO$_{2}$ exchange fluxes from a Europe-wide network of 22 forest flux towers. Total N$_{r}$ deposition rates were estimated from local measurements as far as possible. The forest data were compared with data from natural or semi-natural, non-woody vegetation sites. The response of forest net ecosystem productivity to nitrogen deposition (dNEP= dN$_{dep}$) was estimated after accounting for the effects on gross primary productivity (GPP) of the co-correlates by means of a meta-modelling standardization procedure, which resulted in a reduction by a factor of about 2 of the uncorrected, apparent dGPP/dN$_{dep}$ value. This model-enhanced analysis of the C and N$_{dep}$ flux observations at the scale of the European network suggests a mean overall dNEP/dN$_{dep}$ response of forest lifetime C sequestration to N$_{dep}$ of the order of 40–50 g C per g N, which is slightly larger but not significantly different from the range of estimates published in the most recent reviews. Importantly, patterns of gross primary and net ecosystem productivity versus N$_{dep}$ were non-linear, with no further growth responses at high N$_{dep}$ levels (N$_{dep}$ >2.5–3 gNm$^{-2}$ yr$^{-1}$) but accompanied by increasingly large ecosystem N losses by leaching and gaseous emissions. The reduced increase in productivity per unit N deposited at high N$_{dep}$ levels implies that the forecast increased N$_{r}$ emissions and increased Ndep levels in large areas of Asia may not positively impact the continent’s forest CO$_{2}$ sink. The large level of unexplained variability in observed carbon sequestration efficiency (CSE) across sites further adds to the uncertainty in the dC/dN response

Carbon-nitrogen interactions in European forests and semi-natural vegetation - Part 1: Fluxes and budgets of carbon, nitrogen and greenhouse gases from ecosystem monitoring and modelling

The impact of atmospheric reactive nitrogen (N$_{r}$) deposition on carbon (C) sequestration in soils and biomass of unfertilized, natural, semi-natural and forest ecosystems has been much debated. Many previous results of this dC/dN response were based on changes in carbon stocks from periodical soil and ecosystem inventories, associated with estimates of N$_{r}$ deposition obtained from large-scale chemical transport models. This study and a companion paper (Flechard et al., 2020) strive to reduce uncertainties of N effects on C sequestration by linking multi-annual gross and net ecosystem productivity estimates from 40 eddy covariance flux towers across Europe to local measurement-based estimates of dry and wet N$_{r}$ deposition from a dedicated collocated monitoring network. To identify possible ecological drivers and processes affecting the interplay between C and N$_{r}$ inputs and losses, these data were also combined with in situ flux measurements of NO, N$_{2}$O and CH$_{4}$ fluxes; soil NO$_{3}$̅ leaching sampling; and results of soil incubation experiments for N and greenhouse gas (GHG) emissions, as well as surveys of available data from online databases and from the literature, together with forest ecosystem (BASFOR) modelling. Multi-year averages of net ecosystem productivity (NEP) in forests ranged from -70 to 826 gCm$^{-2}$ yr$^{-1}$ at total wet+dry inorganic N$_{r}$ deposition rates (N$_{dep}$) of 0.3 to 4.3 gNm$^{-2}$ yr$^{-1}$ and from -4 to 361 g Cm$^{-2}$ yr$^{-1}$ at N$_{dep}$ rates of 0.1 to 3.1 gNm$^{-2}$ yr$^{-1}$ in short semi-natural vegetation (moorlands, wetlands and unfertilized extensively managed grasslands). The GHG budgets of the forests were strongly dominated by CO$_{2}$ exchange, while CH$_{4}$ and N$_{2}$O exchange comprised a larger proportion of the GHG balance in short semi-natural vegetation. Uncertainties in elemental budgets were much larger for nitrogen than carbon, especially at sites with elevated N$_{dep}$ where N$_{r}$ leaching losses were also very large, and compounded by the lack of reliable data on organic nitrogen and N$_{2}$ losses by denitrification. Nitrogen losses in the form of NO, N$_{2}$O and especially NO$_{3}$̅ were on average 27%(range 6 %–54 %) of N$_{dep}$ at sites with N$_{dep}$ 3 gNm$^{-2}$ yr$^{-1}$. Such large levels of N$_{r}$ loss likely indicate that different stages of N saturation occurred at a number of sites. The joint analysis of the C and N budgets provided further hints that N saturation could be detected in altered patterns of forest growth. Net ecosystem productivity increased with N$_{r}$ deposition up to 2–2.5 gNm$^{-2}$ yr$^{-1}$, with large scatter associated with a wide range in carbon sequestration efficiency (CSE, defined as the NEP = GPP ratio). At elevated N$_{dep}$ levels (> 2.5 gNm$^{-2}$ yr$^{-1}$), where inorganic N$_{r}$ losses were also increasingly large, NEP levelled off and then decreased. The apparent increase in NEP at low to intermediate N$_{dep}$ levels was partly the result of geographical cross-correlations between N$_{dep}$ and climate, indicating that the actual mean dC/dN response at individual sites was significantly lower than would be suggested by a simple, straightforward regression of NEP vs. N$_{dep}$

Suelos loéssicos influenciados por depósitos de conchilla pleistocenos de la formación pascua, noreste de la provincia de Buenos Aires, Argentina

En el litoral de la provincia de Buenos Aires se encuentran varias unidades litoestratigráficas cuaternarias carbonáticas vinculadas a ingresiones marinas. En la Formación Las Escobas (Holoceno) se desarrollan suelos calcáreos litogénicos que han sido objeto de estudios taxonómicos, mineralógicos y micromorfológicos. La unidad marina más antigua es la Formación Pascua (Pleistoceno medio a superior) intercalada en la parte superior de sedimentos loéssicos de la Formación Pampiano y constituida por sedimentos arenosos, cuya parte superior posee alta concentración de valvas de moluscos fuertemente cementadas con carbonato de calcio, constituyendo una coquina. Los suelos actuales, de los cuales hay escasa información y son motivo de esta presentación, se desarrollan principalmente en los sedimentos suprayacentes de la Formación Pampiano y están afectados por procesos de carbonatación, argiluviación y vertisolización. Los objetivos de esta contribución son: a) analizar las propiedades de los suelos desarrollados en sedimentos loéssicos que cubren a la Formación Pascua, y b) estimar la influencia de los depósitos carbonáticos de esta formación en la génesis de los suelos. Se estudiaron cinco pedones (cuatro Molisoles y un Vertisol) en los partidos de La Plata, Magdalena y Punta Indio (provincia de Buenos Aires), en los cuales los depósitos carbonáticos tienen influencia en los horizontes inferiores de los suelos. Los pedones se desarrollan en sucesiones estratigráficas donde en la parte inferior se encuentra la Formación Pascua y donde los procesos de pedogénesis afectan a veces el techo de la misma. Es decir, que en algunos suelos hay un ciclo pedológico completo (horizontes A, B y C) desarrollado en materiales loéssicos y en otros casos, parte del ciclo pedológico (solum: horizontes A y B) se desarrolla en el loess y parte en la coquina (horizontes C). Todos los suelos poseen evolución calcárea, con horizontes enriquecidos con carbonato de calcio y/o horizontes cálcicos y/o horizontes petrocálcicos (calcreta). Los horizontes enriquecidos en carbonato de calcio y los horizontes cálcicos están desarrollados en los depósitos loéssicos, mientras que el horizonte petrocálcico se desarrolla en la parte superior de la coquina, por alteración epigénica de la misma, y cuyo contacto con el depósito loéssico suprayacente es neto (espesor <2 cm) y de forma plana u ondulada. Los horizontes petrocálcicos constituyen una calcreta pedogénica de clima húmedo, compacta, sin estructura (masiva) o laminar, de menos de 10 cm de espesor. El origen del carbonato pedogénico puede atribuirse a varios mecanismos: a) disolución de carbonatos en la parte superior del perfil, translocación descendente y precipitación; b) ascenso capilar y evaporación de agua carbonatada acumulada en la parte superior de capas compactas, casi impermeables; c) disolución y reprecipitación in situ de los carbonatos de la coquina y d) precipitación biogénica debida a la acción de bacterias, hongos y raíces, como proceso complementario. El proceso de carbonatación sería de origen mixto: a) por reorganización de la roca basal y b) por translocación en clima húmedo; en ambos casos el carbonato pedogenético tendría origen abiótico con participación biótica. Predomina la cristalización y recristalización, ya sea por disolución de depósitos preexistentes o por soluciones carbonatadas de desplazamiento vertical y lateral, interviniendo asimismo la biomineralización en estructuras orgánicas

Une inégalité polynômiale en plusieurs variables

RésuméSoit Ω un ouvert borné de RN et m une fonction de Cs(Ω). Sous des conditions assez générales sur m et Ω on montre qu'il existe deux constantes C et d telles que pour tout polynôme P de N variables réelles on ait: ∥P∥L∞(Ω) ⩽C (degré deP)d ∥Pm∥L∞(Ω). De plus on donne la valeur optimale exacte de la constante d en précisant sa signification géométrique

Synthesis and attempted reductions of bulky 1,3,5-triazapentadienyl groups 2 and 13 halide complexes

This research was supported by the Australian Research Council and the US Air Force Asian Office of Aerospace Research and Development (grant FA23861141114043 to CJ).Three extremely bulky 1,3,5-triazapentadienes, ArNNNH (ArNNN = N{C(But)=N(Ar)}2; Ar = Mes (mesityl), Dep (2,6-diethylphenyl) or Dip (2,6-diisopropylphenyl)) have been prepared and structurally characterized. These are readily deprotonated, yielding a series of lithium and potassium triazapentadienyl complexes, one of which, (DipNNN)Li, has been structurally characterized. Similarly, three monomeric triazapentadienyl magnesium iodide complexes, (ArNNN)MgI(OEt2), and a dimeric calcium counterpart, {(MesNNN)Ca(THF)(μ-I)}2, have been prepared. Attempts to reduce the former gave homoleptic bis(triazapentadienyl) magnesium complexes, (ArNNN)2Mg (Ar = Mes or Dep) as the main products. One reaction also gave a very low yield of the magnesium(I) dimer, {(DepNNN)Mg−}2, which was structurally characterized. In related chemistry, two triazapentadienyl boron difluoride compounds, (ArNNN)BF2 (Ar = Mes or Dep), have been synthesized, and unsuccessful attempts made to reduce these to boron(I) heterocycles. For sake of comparison, attempts have been made to prepare a series of related amino-substituted β-diketiminato group 13 element(I) heterocycles. While these were also not successful, several group 13 element(III) halide complexes incorporating this ligand class, and related amino-substituted β-diketiminates, have been characterized.PostprintPeer reviewe

Structural studies of the pleckstrin protein by nuclear magnetic resonance spectroscopy

Das Pleckstrinprotein ist das Hauptsubstrat von Protein Kinase C (PKC) in Blutplättchenzellen. Die Phosphorylierung Pleckstrins setzt Prozesse in Gang, die zur Aktivierung des Blutplättchens, Blutgerinnung und Wundverschluss führen. Pleckstrin besteht aus drei Domänen: den prototypischen pleckstrin homology (PH)-Domänen an den Termini des Proteins sowie einer zentralen DEP-Domäne. Die Phosphorylierungsstellen für PKC liegen in der Verbindungssequenz zwischen der N-terminalen PH-Domäne (N-PH) und DEP. Die Strukturen dieser beiden Domänen sind (als Einzeldomänen) bereits bekannt. Im ersten Teil dieser Dissertation wird die mittels der Kernresonanzspektroskopie (NMR) berechnete hochaufgelöste Struktur der C-terminalen PH-Domäne (C-PH) vorgestellt. Durch biochemische und NMR-Analyse wurde eine spezifische Bindung C-PHs an Phosphatidylinositol-3,4-bisphosphat (PtdIns(3,4)P2), einem wichtigen Botenstoff im Blutplättchen, nachgewiesen. Die Interaktion zwischen C-PH und PtdIns(3,4)P2 beruht auf einem konservierten Sequenzmotiv auf den beta1- und beta2-Strängen der Domäne und auf Sequenzdeterminanten in der beta1-beta2-Schleife. Diese Reste bilden eine positiv geladene Bindungstasche an der �offenen� Seite der Domäne. Die spezifische Bindung an PtdIns(3,4)P2 deutet erstmals auf eine mögliche zweite Regulationsebene Pleckstrins neben PKC-Phosphorylierung hin. Im zweiten Teil dieser Arbeit wurden das Doppeldomänenkonstrukt DEP_C-PH mit NMR und biochemischen Methoden untersucht. Die Ergebnisse dieser Versuche lassen darauf schließen, dass C-PH in DEP_C-PH einen unabhängigen PtdIns(3,4)P2-Sensor darstellt. Im letzten Teil dieser Dissertation wurde eine neue Strategie zur NMR-Strukturbestimmung von Multidomänenproteinen methodisch ausgearbeitet und auf Pleckstrin-Doppeldomänenkonstrukte angewandt. Die Methode beinhaltet die systematische Mutation aller nativen Cysteine zwecks Derivatisierung des Proteins mit einem �Spin-label� an eigens dafür eingeführten Cysteinen. Die vom �Spin-label� verursachte paramagnetische Relaxationsverstärkung wurde als �distance restraint� (Abstandsschranke) mittels interner Kalibrierung in Strukturrechnungen eingesetzt. Die auf diese Weise berechnete vorläufige Struktur von N-PH_DEP zeigt, dass die beiden Domänen dieses Proteins räumlich eng aneinander angelagert sind, was eine Blockierung der funktionalen Regionen von N-PH zur Folge haben könnte. Daher wird ein Auto-Inhibitions-Modell für unphosphoryliertes Pleckstrin vorgeschlagen

Synthesis, solution dynamics and chemical vapour deposition of heteroleptic zinc complexes via ethyl and amide zinc thioureides

Ethyl and amide zinc thioureides [L^{1}ZnEt]_{2} (1), [L^{1*}ZnEt]_{2} (2) and [L^{1}Zn(N(SiMe_{3})_{2})]_{2} (3) have been synthesised from the equimolar reaction of thiourea ligands (HL^{1} = iPrN(H)CSNMe2 and HL^{1*} = PhN(H)CSNMe_{2}) with diethyl zinc and zinc bis[bis(trimethylsilyl)amide] respectively. New routes towards heteroleptic complexes have been investigated through reactions of 1, 2 and 3 with β-ketoiminates (HL^{2} = [(Me)CN(H){iPr}–CHC(Me)[double bond, length as m-dash]O]), bulky aryl substituted β-diiminates (HL3 = [(Me)CN(H){Dipp}–CHC(Me)[double bond, length as m-dash]N{Dipp}] (Dipp = diisopropylphenyl) and HL3* = [(Me)CN(H){Dep}–CHC(Me)[double bond, length as m-dash]N{Dep}] (Dep = diethylphenyl)) and donor-functionalised alcohols (HL^{4} = Et_{2}N(CH_{2})_{3}OH and HL4* = Me_{2}N(CH_{2}){3}_OH) and have led to the formation of the heteroleptic complexes [L^{1*}ZnL^{3*}] (5), [L^{1}ZnL^{4}]_{2} (6), [L^{1}ZnL^{4*}]_{2} (7), [L^{1*}ZnL^{4}] (8) and [L^{1*}ZnL^{4*}] (9). All complexes have been characterised by {1}^H and 1{3}^C NMR, elemental analysis, and the X-ray structures of HL^{1*}, 1, 2, 6 and 7 have been determined via single crystal X-ray diffraction. Variable temperature 1H, COSY and NOESY NMR experiments investigating the dynamic behaviour of 5, 6 and 7 have shown these molecules to be fluxional. On the basis of solution state fluxionality and thermogravimetric analysis (TGA), alkoxyzinc thioureides 6 and 7 were investigated as single-source precursors for the deposition of the ternary material zinc oxysulfide, Zn(O,S), a buffer layer used in thin film photovoltaic devices. The aerosol-assisted chemical vapour deposition (AACVD) reaction of 7 at 400 °C led to the deposition of the heterodichalcogenide material Zn(O,S), which was confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDX), with optical properties investigated using UV/vis spectroscopy, and surface morphology and film thickness examined using scanning electron microscopy (SEM)

<i>Crithmum maritimum</i> L. (Apiaceae) voor het eerst in België gevonden

In 1985 Crithmum maritimum has been recorded for the first time in Belgium. The single plant is still present It is growing on the seaward side of the strongly disturbed dunefront bordering the parking zone of a road on the sea promenade at Raversijde (51°l2'N, 2°50'3O"E; IFBL/C 1.23) near Ostend. Like other continental northern records of the species (France, dep. Du Nord and Netherlands, especially Zeeland) the Belgian locality will probably be of a temporary nature

Values that Underlie and Undermine Well-Being : Variability Across Countries

We examined relations of 10 personal values to life satisfaction (LS) and depressive affect (DEP) in representative samples from 32/25 countries (N=121495). We tested hypotheses both for direct relations and cross-level moderation of relations by Cultural Egalitarianism. We based hypotheses on the growth versus self-protection orientation and person-focus versus social-focus motivations that underlie values. As predicted, openness to change values (growth/person) correlated positively with subjective well-being (SWB: higher LS, lower DEP) and conservation values (self-protection/social) correlated negatively with SWB. The combination of underlying motivations also explained more complex direct relations of self-transcendence and self-enhancement values with SWB. We combined an analysis of the environmental context in societies low versus high in Cultural Egalitarianism with the implications of pursuing person-focused versus social-focused values to predict how Cultural Egalitarianism moderates value-SWB relations. As predicted, under low versus high Cultural Egalitarianism, (i) openness to change values related more positively to SWB, (ii) conservation values more negatively, (iii) self-enhancement values less negatively and (iv) self-transcendence values less positively. Culture moderated value-SWB relations more weakly for DEP than for LS. Culture moderated value-LS relations more strongly than the socio-economic context did. This study demonstrates how the cultural context shapes individual-level associations between values and SWB. Copyright (c) 2017 European Association of Personality PsychologyPeer reviewe