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Introduction to the Deep Convective Clouds and Chemistry (DC3) 2012 Studies
The Deep Convective Clouds and Chemistry (DC3) project aimed to determine the impact ofdeep, midlatitude continental convective clouds on tropospheric composition and chemistry. The DC3field campaign was conducted over a broad area of the central United States during May–June 2012. Datacollected by DC3 have been extensively analyzed, with many results published in Deep Convective Cloudsand Chemistry 2012 Studies (DC3), a joint special section of JGR Atmospheres and Geophysical ResearchLetters. This paper highlights key results from the DC3 project as an introduction to the special issue.</p
Patchiness and Demographic Noise in Three Ecological Examples
Understanding the causes and effects of spatial aggregation is one of the
most fundamental problems in ecology. Aggregation is an emergent phenomenon
arising from the interactions between the individuals of the population, able
to sense only -at most- local densities of their cohorts. Thus, taking into
account the individual-level interactions and fluctuations is essential to
reach a correct description of the population. Classic deterministic equations
are suitable to describe some aspects of the population, but leave out features
related to the stochasticity inherent to the discreteness of the individuals.
Stochastic equations for the population do account for these
fluctuation-generated effects by means of demographic noise terms but, owing to
their complexity, they can be difficult (or, at times, impossible) to deal
with. Even when they can be written in a simple form, they are still difficult
to numerically integrate due to the presence of the "square-root" intrinsic
noise. In this paper, we discuss a simple way to add the effect of demographic
stochasticity to three classic, deterministic ecological examples where
aggregation plays an important role. We study the resulting equations using a
recently-introduced integration scheme especially devised to integrate
numerically stochastic equations with demographic noise. Aimed at scrutinizing
the ability of these stochastic examples to show aggregation, we find that the
three systems not only show patchy configurations, but also undergo a phase
transition belonging to the directed percolation universality class.Comment: 20 pages, 5 figures. To appear in J. Stat. Phy
Modelling harmonic generation measurements in solids
Harmonic generation measurements typically make use of the plane wave result when extracting values for the nonlinearity parameter, beta, from experimental measurements. This approach, however, ignores the effects of diffraction, attenuation, and receiver integration which are common features in a typical experiment. Our aim is to determine the importance of these effects when making measurements of beta over different sample dimensions, or using different input frequencies. We describe a three-dimensional numerical model designed to accurately predict the results of a typical experiment, based on a quasi-linear assumption. An experiment is designed to measure the axial variation of the fundamental and second harmonic amplitude components in an ultrasonic beam, and the results are compared with those predicted by the model. The absolute b values are then extracted from the experimental data using both the simulation and the standard plane wave result. A difference is observed between the values returned by the two methods, which varies with axial range and input frequency. (C) 2013 Elsevier B. V. All rights reserved.</p
Body condition score, weight variation and reproductive performance of beef cows in rangelands from the Pantanal region
Objetivou-se avaliar a influĂŞncia do escore de condição corporal (ECC) sobre a eficiĂŞncia reprodutiva de vacas de cria nos perĂodos prĂ© e pĂłs-parto e a probabilidade de parição, usando o escore de condição corporal e a variação ponderal no perĂodo crĂtico do ciclo reprodutivo. Utilizaram-se 248 vacas multĂparas mantidas em pastagens nativas distribuĂdas em quatro estratĂ©gias de suplementação: mistura mineral (controle); suplemento farelado; suplemento lĂquido; suplemento lĂquido para vacas e bezerros. As avaliações de peso e ECC, na escala de 1 a 9, foram realizadas no perĂodo crĂtico: em agosto (perĂodo prĂ©-parto, 60-90 dias antes da parição) e em janeiro (perĂodo pĂłs-parto e reprodutivo) durante quatro anos consecutivos. Para a análise dos anos consecutivos de reprodução, criou-se um escore de reprodução, ou seja, somou-se o nĂşmero de parições de cada vaca durante os quatro anos pecuários avaliados. O escore de condição corporal nos perĂodos prĂ© e pĂłs-parto e a idade da vaca influenciaram o escore de reprodução. Portanto, para avaliação da probabilidade de parição, foram utilizadas todas as vacas, classificadas em paridas e vazias. Utilizando equações de estimação generalizadas (EEG), foi modelada a probabilidade de as matrizes serem classificadas como paridas considerando variáveis exploratĂłrias ao longo do tempo. Para se obter probabilidade de parição superior a 80%, as vacas devem possuir escore de aproximadamente 5,5 no perĂodo prĂ©-parto. Aproximadamente 60% das vacas paridas mantiveram ou ganharam peso no perĂodo crĂtico do ano, o que levou a maior probabilidade de reconcepção, similar ao observado para as vacas vazias, porĂ©m com probabilidade menor de parição. O perĂodo prĂ©-parto Ă© o melhor para estimar a probabilidade de parição das vacas por meio da avaliação do escore corporal. A seleção de vacas adaptadas Ă s condições bioclimáticas do Pantanal aumenta a probabilidade de produção de um bezerro por vaca por ano. _________________________________________________________________________________ ABSTRACTThe aim of this study was to evaluate the influence of body condition score (BCS) on reproductive performance of beef cows before and after calving and to evaluate the calving probability using body condition score and weight variation during critical periods of the cow reproductive cycle. From 2001 to 2005, the body condition score was recorded in 248 multiparous cows raised in native pastures, submitted to different supplementation treatments (mineral mixture only - control; dry supplement; liquid supplement and liquid supplement for cow and calves). Weighing and body condition evaluation were made on a 1-9 point scale in August (prepartum period, 60-90 days before parturition) and January (postpartum and reproductive period). A reproduction score was created in function of the body scores in four consecutive years. Except for the treatment, the other factors (body condition score in the prepartum and postpartum periods and cow age) influenced the reproduction score. Thus, the calving probabilities were estimated for all cows. Generalized estimating equations (GEE) were used to evaluate the calving probability in function of the exploratory variables over time. Calving probability higher than 80% was obtained when cows scored 5,5 before calving. In relation to weight, the results showed that about 60% of calving cows maintained or gained weight in the postpartum period, leading to increase in the rebreeding probability. Similar situation occurred with single cows; however, the calving probability was lower. These results indicate that the calving probability using BCS is better estimated before calving. Furthermore, it indicates the presence of cows more adapted to the Pantanal climatic and feeding conditions than others
Can forest management based on natural disturbances maintain ecological resilience?
Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance
Ecological Invasion, Roughened Fronts, and a Competitor's Extreme Advance: Integrating Stochastic Spatial-Growth Models
Both community ecology and conservation biology seek further understanding of
factors governing the advance of an invasive species. We model biological
invasion as an individual-based, stochastic process on a two-dimensional
landscape. An ecologically superior invader and a resident species compete for
space preemptively. Our general model includes the basic contact process and a
variant of the Eden model as special cases. We employ the concept of a
"roughened" front to quantify effects of discreteness and stochasticity on
invasion; we emphasize the probability distribution of the front-runner's
relative position. That is, we analyze the location of the most advanced
invader as the extreme deviation about the front's mean position. We find that
a class of models with different assumptions about neighborhood interactions
exhibit universal characteristics. That is, key features of the invasion
dynamics span a class of models, independently of locally detailed demographic
rules. Our results integrate theories of invasive spatial growth and generate
novel hypotheses linking habitat or landscape size (length of the invading
front) to invasion velocity, and to the relative position of the most advanced
invader.Comment: The original publication is available at
www.springerlink.com/content/8528v8563r7u2742
Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets
The spins of ten stellar black holes have been measured using the
continuum-fitting method. These black holes are located in two distinct classes
of X-ray binary systems, one that is persistently X-ray bright and another that
is transient. Both the persistent and transient black holes remain for long
periods in a state where their spectra are dominated by a thermal accretion
disk component. The spin of a black hole of known mass and distance can be
measured by fitting this thermal continuum spectrum to the thin-disk model of
Novikov and Thorne; the key fit parameter is the radius of the inner edge of
the black hole's accretion disk. Strong observational and theoretical evidence
links the inner-disk radius to the radius of the innermost stable circular
orbit, which is trivially related to the dimensionless spin parameter a_* of
the black hole (|a_*| < 1). The ten spins that have so far been measured by
this continuum-fitting method range widely from a_* \approx 0 to a_* > 0.95.
The robustness of the method is demonstrated by the dozens or hundreds of
independent and consistent measurements of spin that have been obtained for
several black holes, and through careful consideration of many sources of
systematic error. Among the results discussed is a dichotomy between the
transient and persistent black holes; the latter have higher spins and larger
masses. Also discussed is recently discovered evidence in the transient sources
for a correlation between the power of ballistic jets and black hole spin.Comment: 30 pages. Accepted for publication in Space Science Reviews. Also to
appear in hard cover in the Space Sciences Series of ISSI "The Physics of
Accretion onto Black Holes" (Springer Publisher). Changes to Sections 5.2,
6.1 and 7.4. Section 7.4 responds to Russell et al. 2013 (MNRAS, 431, 405)
who find no evidence for a correlation between the power of ballistic jets
and black hole spi
Diversity of Agaricales (Basidiomycota) in the Reserva BiolĂłgica Walter Egler, Amazonas, Brazil
A study of the order Agaricales Clements (Hymenomycetes, Basidiomycotina), occurring in the Reserva BiolĂłgica Walter Egler was carried out from December 2000 to June 2001. The area of study is situated at Road AM-010, Manaus-Itacoatiara, km 64, Latitude 02° 43' S and Longitude 59° 47' W, Rio Preto da Eva, in the State of Amazonas, with a total area of 709 ha of terra firme rain forest. The fungi collected were identified based on traditional methodology for identification of Agaricales. A total of 39 species were studied, distributed in 13 genera and six families: Polyporaceae: Pleurotus sp.; Hygrophoraceae: Hygrocybe cf. megistospora, Hygrocybe aff. miniceps, Hygrocybe occidentalis var. scarletina and eight indeterminate species of Hygrocybe; Tricholomataceae: Clitocybe sp., Hydropus sp.1 and Hydropus sp.2, Macrocystidia sp., Marasmiellus sp., Marasmius bellus, Marasmius haedinus var. haedinus, Marasmius cf. leoninus, Marasmius cf. mazatecus, Marasmius cf. ruber, Marasmius cf. setulosifolius, Marasmius tageticolor, Marasmius cf. variabiliceps var. variabiliceps, Marasmius sp.1, Marasmius sp.2, Marasmius sp.3 and Marasmius sp.4, Tricholoma sp.; Agaricaceae: Agaricus sp.1 and Agaricus sp.2, Lepiota sp., Cystoderma sp.; Entolomataceae: Entoloma cf. azureoviride, Entoloma cf. cystidiophorum, Entoloma strigosissima, Entoloma sp.; Russulaceae: Lactarius panuoides. Entoloma azureoviride, Hygrocybe miniceps, Lactarius panuoides, Marasmius cf. mazatecus, Marasmius cf. setulosifolius and Marasmius variabiliceps var. variabiliceps, apparently are here cited for the first time from Brazil. With exception of Marasmius tageticolor, all species are cited here for the first time as occurring in Egler Forest. The tables with the species occurrence, in accordance with the topographical gradient (sand bank, incline, plateau) and its respective habitat, are supplied.", 'enFoi realizado um estudo dos representantes da Ordem Agaricales Clements (Hymenomycetes, Basidiomycotina), ocorrentes na Reserva BiolĂłgica Walter Egler, situada na Estrada AM-010, Manaus-Itacoatiara, Km 64, Latitude 02° 43' S e Longitude 59° 47' W, Rio Preto da Eva, Amazonas. A área abrange 709 ha de floresta de terra firme primária. As coletas foram realizadas no perĂodo de dezembro de 2000 a junho de 2001 e seguiu-se a metodologia usual para identificação de Agaricales. Foram estudadas um total de 39 espĂ©cies, distribuĂdas em 13 gĂŞneros e seis famĂliasPolyporaceaePleurotus sp.; HygrophoraceaeHygrocybe cf. megistospora, Hygrocybe aff. miniceps, Hygrocybe occidentalis var. scarletina, e mais oito espĂ©cies de Hygrocybe indeterminadas; TricholomataceaeClitocybe sp., Hydropus sp.1 e Hydropus sp.2, Macrocystidia sp., Marasmiellus sp., Marasmius bellus, Marasmius haedinus var. haedinus,Marasmius cf. leoninus, Marasmius cf. mazatecus, Marasmius cf. ruber,Marasmius cf. setulosifolius, Marasmius tageticolor, Marasmius cf. variabiliceps var. variabiliceps, Marasmius sp.1, Marasmius sp.2, Marasmius sp.3 e Marasmius sp.4, Tricholoma sp.; AgaricaceaeAgaricus sp.1 e Agaricus sp.2, Lepiota sp., Cystoderma sp.; EntolomataceaeEntoloma cf. azureoviride, Entoloma cf. cystidiophorum, Entoloma strigosissima, Entoloma sp.; RussulaceaeLactarius panuoides. Destas, Entoloma azureoviride, Hygrocybe miniceps, Lactarius panuoides, Marasmius cf. mazatecus, Marasmius cf. setulosifolius e Marasmius variabiliceps var. variabiliceps, provavelmente, estĂŁo sendo aqui citadas pela primeira vez, para o Brasil. Com exceção de Marasmius tageticolor, as demais espĂ©cies sĂŁo citadas pela primeira vez, para a Reserva Egler. SĂŁo fornecidas tabelas com a ocorrĂŞncia das espĂ©cies de acordo com o gradiente topográfico (baixio, vertente, platĂ´) e seus respectivos habitats