pinecone/core-2020-05-10-deduplication huggingface dataset:
Modelling upstream fish passage in standard box culverts: interplay between turbulence, fish kinematics, and energetics

Box culverts are common hydraulic structures along rivers and streams, in rural and urban water systems. The expertise in fish-friendly culvert design is limited, sometimes leading to adverse impact on the catchment ecosystem or to uneconomical structures. Basic dimensional considerations highlight a number of key parameters relevant to any laboratory modelling of upstream fish passage, including the ratio of fish speed fluctuations to fluid velocity fluctuations, the ratios of fish dimensions to turbulent length scale, and the fish species. Alternately, the equation of conservation of momentum may be applied to an individual fish, yielding some deterministic estimate of instantaneous thrust and power expended during fish swimming, including the associated energy consumption. The rate of work required by the fish to deliver thrust is proportional to the cube of the local fluid velocity, and the model results demonstrate the key role of slow-velocity regions in which fish will minimize their energy consumption when swimming upstream
Epilithic biomass in a large gravel-bed river (the Garonne, France): a manifestation of eutrophication?

In order to evaluate the impact of outputs of the city of Toulouse (740 000 inhabitants) on the epilithic communities\ud
colonizing pebble banks in the river Garonne, a large gravel-bed river (eighth order), dry mass (DM), ash-free dry\ud
mass (AFDM) and chlorophyll-a (chla) epilithic biomass per unit area were measured and autotrophic index (AI) (i.e.\ud
ratio AFDM/chla) was calculated at four stations. This river is morphologically characterized by a succession of pools\ud
and riffles and by highly fluctuating hydraulic conditions. At the four stations studied (223 km apart), the means of\ud
AFDM values varied between 17.1 and 31.1 g m−2 of colonized surface and the chla concentration varied between\ud
112 and 254 mg m−2. However, there were no significant differences in AFDM per unit area between the parts of the\ud
river upstream and downstream of the Toulouse area (Mann–Whitney U-test statistic), nor between the four stations\ud
(Kruskal–Wallis test statistic), and the AI did not allow the description of changes in periphyton communities between\ud
sampling locations. This study showed that epilithic biomass should be considered as the typical microbial community\ud
of the river rather than as a manifestation of eutrophication
A numerical tool to integrate biophysical diversity of a large regulated river: hydrobiogeochemical bases. The case of the Garonne River (France)

This article presents the bases of a hydrobiogeochemical model of the Garonne River (southwest France) which has been developed to integrate physical and biological processes during summer low-water periods. The physical part of this model is composed of a one-dimensional unsteady hydrodynamic model, allowing the resolution of the Saint-Venant equations, and a transport model which simulates downstream changes in solute concentrations. Biogeochemical processes are considered through the definition of functional compartments which make up the channel bed. These different compartments are defined both by the organisms involved in the solute transformation processes and by the physical and hydraulic characteristics of their habitat. Integration of these functional compartments within the model required investigations at different scales. The scale at which biological processes take place ranges from millimetres to metres. The scale of a reach, at which organization of the functional compartments along the river can be linked to hydrodynamic and morphological characteristics, ranges from 500 m to several kilometres. The regional scale is that at which homogeneous reaches can be integrated. A feedback between numerical results and field experiments has allowed improvements to in situ measurement to increase modelling accuracy. For example, the model allows estimation of variables, such as fluxes, that are difficult to measure in situ. The developed model can integrate various functional compartments and their biogeochemical functioning. Two application examples, focused on dissolved inorganic nitrogen, are presented in order to illustrate the numerical tool functioning: integration of equations on nitrification processes in the water body, and integration of consumption/production terms on epilithic biofilm resulting from in situ experimental mean values. The model we have developed constitutes a promising analytical tool that will be able to integrate previous and future studies
Environmental flow requirements of fish in Lesotho rivers using the drift methodology

DRIFT (Downstream Response to Imposed Flow Transformations) is a scenario-based environmental flow assessment methodology applied during impact studies associated with the Lesotho Highlands Water Project, Southern Africa. DRIFT offers a structured process for predicting the biophysical, social and economic consequences of altering a river's flow regime. The fish component of DRIFT provides a ten-step protocol designed to make such predictions using field data on a river's fish fauna linked to information on flow-related aspects of fish biology drawn from the literature and the knowledge base and professional experience of fish ecologists. Aworked example of the methodology is presented based on a study site downstream from Katse Dam on the Malibamatso River, Lesotho, where the ecological consequences of four flow scenarios were evaluated. DRIFT and  its fish component have emerged from studies in a semi-arid, developing region where unpredictable hydrological regimes and data scarcity constrain the prediction of ecological responses to flow regulation. Faced with similar information constraints, scientific uncertainty and limited windows of opportunity to guide water management, other countries have employed scientific panels to recommend environmental flows. DRIFT and its fish component compare favourably with recommended best practice for Australian scientific panel assessments of the flow requirements of river ecosystems. The risks associated with use of scientific panel approaches are discussed and minimum data sets and standards are recommended for the conduct of a DRIFT fish assessment. DRIFT and related frameworks represent the second level in a three-tiered hierarchy of environmental flow methods. They can provide environmental flow recommendations of far greater scientific resolution than hydrological methods by integrating many types of information on the responses of riverine biota to flow modifications. However, DRIFT should only be applied within an adaptive management framework where there is a genuine commitment to the generation and use of new knowledge derived from monitoring and research.Griffith Sciences, Griffith School of EnvironmentFull Tex
Experimental reintroduction of woody debris on the Williams River, NSW: Geomorphic and ecological responses

A total of 436 logs were used to create 20 engineered log jams (ELJs) in a 1.1 km reach of the Williams River, NSW, Australia, a gravel-bed river that has been desnagged and had most of its riparian vegetation removed over the last 200 years. The experiment was designed to test the effectiveness of reintroducing woody debris (WD) as a means of improving channel stability and recreating habitat diversity. The study assessed geomorphic and ecological responses to introducing woody habitat by comparing paired test and control reaches. Channel characteristics (e.g. bedforms, bars, texture) within test and control reaches were assessed before and after wood placement to quantify the morphological variability induced by the ELJs in the test reach. Since construction in September 2000, the ELJs have been subjected to five overtopping flows, three of which were larger than the mean annual flood. A high-resolution three-dimensional survey of both reaches was completed after major bed-mobilizing flows. Cumulative changes induced by consecutive floods were also assessed. After 12 months, the major geomorphologic changes in the test reach included an increase in pool and riffle area and pool depth; the addition of a pool-riffle sequence; an increase by 0.5-1 m in pool-riffle amplitude; a net gain of 40 m3 of sediment storage per 1000 m2 of channel area (while the control reach experienced a net loss of 15 m3/1000 m2 over the same period); and a substantial increase in the spatial complexity of bed-material distribution. Fish assemblages in the test reach showed an increase in species richness and abundance, and reduced temporal variability compared to the reference reach, suggesting that the changes in physical habitat were beneficial to fish at the reach scale.Griffith Sciences, Griffith School of EnvironmentFull Tex
Flow variability and macroinvertebrate community response within riverine systems

This is the pre-peer reviewed version of the article, which has been published in final form at: http://dx.doi.org/10.1002/rra.933River flow regimes, controlled by climatic and catchment factors, vary over a wide\ud
range of temporal and spatial scales. This hydrological dynamism is important in\ud
determining the structure and functioning of riverine ecosystems; however, such\ud
hydroecological associations remain poorly quantified. This paper explores and models\ud
relationships between a suite of flow regime predictors and macroinvertebrate\ud
community metrics from 83 rivers in England and Wales. A two-stage analytical\ud
approach was employed: (1) classification of 83 river basins based upon the magnitude\ud
and shape (form) of their long-term (1980 – 1999) average annual regime to group\ud
basins with similar flow responses; and (2) examination of relationships between a total\ud
of 201 flow regime descriptors identified by previous researchers and macroinvertebrate\ud
community metrics for the whole data set and long-term flow regime classes over an\ud
11-year period (1990 – 2000). The classification method highlighted large-scale patterns\ud
in river flow regimes, identifying five magnitude classes and three shape classes. A\ud
west–east trend of flow regime magnitude (high-low) and timing (early-late peak) was\ud
displayed across the study area, reflecting climatic gradients and basin controls (e.g.\ud
lithology). From the suite of hydrological variables, those associated with the magnitude\ud
of the flow regime consistently produced the strongest relationships with\ud
macroinvertebrate community metrics for all sites and for the long-term regime\ud
composite classes. The results indicate that the classification (subdivision) of rivers into\ud
flow regime regions potentially offers a means of increasing predictive capacity and, in\ud
turn, better management of fluvial hydrosystems
Selection of river flow indices for the assessment of hydroecological change

This is the pre-peer reviewed version of the article, which has been published in final form at: http://dx.doi.org/10.1002/rra.964A wide range of ‘ecologically relevant’ hydrological indices (variables) have been\ud
identified as potential drivers of riverine communities. Recently, concerns have been\ud
expressed regarding index redundancy (i.e. similar patterns of variance) across the host of\ud
hydrological descriptors on offer to researchers and water resource managers. Some\ud
guiding principles are required to aid selection of the most statistically defensible and\ud
meaningful river flow indices for hydroecological analysis. In this short communication,\ud
we investigate the utility of a principal components analysis (PCA)-based method that\ud
identifies 25 hydrological variables to characterise the major modes of statistical variation\ud
in 201 hydrological indices for 83 rivers across England and Wales. The emergent\ud
variables, and all 201 hydrological variables, are used to develop regression models [for the\ud
whole data set and three river flow regime shape (i.e. annual hydrograph form) classes] for\ud
an 11-year macroinvertebrate community dataset (i.e. LIFE scores). The same ‘best’\ud
models are produced using the PCA-based method and all 201 hydrological variables for\ud
two of the three river flow regime groups. However, weaker models are yielded by the\ud
PCA-based method for the remaining (flashy) river flow regime class and the whole data\ud
set (all 83 rivers). Thus, it is important to exercise caution when employing data reduction/\ud
index redundancy approaches, as they may reject variables of ecological significance due to\ud
the assumption that the statistically dominant sources of hydrological variability are the\ud
principal drivers of, perhaps more subtle (sensitive), hydroecological associations
Assessing the effectiveness of two theoretically motivated computerassisted reading interventions in the United Kingdom: GG Rime and GG Phoneme

We report an empirical comparison of the effectiveness of two theoretically motivated computer-assisted reading interventions (CARI) based on the Finnish GraphoGame CARI: English GraphoGame Rime (GG Rime) and English GraphoGame Phoneme (GG Phoneme). Participants were 6–7-year-old students who had been identified by their teachers as being relatively poor at reading. The students were divided into three groups. Two of the groups played one of the games as a supplement to normal classroom literacy instruction for five sessions per week for a period of 12 weeks. The third group formed an untreated control. Both games led to gains in reading, spelling, and phonological skills in comparison with the untreated control group. The two interventions also had some differential effects. The intervention gains were maintained at a four-month follow-up
First-language Longitudinal Predictors of Second-language Literacy In Young L2 Learners

Can young students' early reading abilities in their first language (L1) predict later literacy development in a second language (L2)? The cross-language relationships between Chinese (L1) and English (L2) among 87 Hong Kong students were explored in a longitudinal study. Chinese word-reading fluency, Chinese rapid digit naming, and Chinese rhyme awareness at age 7 (grade 1), with age and IQ taken into account, were significant concurrent and longitudinal predictors of English word reading, and text-level reading and writing skills across ages 7-10. These three Chinese measures together accounted for 16-28% of unique variance in the English literacy tasks across the three-year period. Students who showed word-reading difficulties in Chinese in grade 1 also performed more poorly than average Chinese readers in English reading and related cognitive tasks later on, especially on phonological tasks. The results provided evidence for the cross-language transfer of cognitive-linguistic abilities between two distinctly different orthographies. L1 markers underlying reading difficulties in both L1 and L2 can serve as early indicators of possible reading problems that may arise later in L2. These findings have clinical, educational, and theoretical implications.postprin
Hydromorphological control of phosphorus in a \ud
large free-flowing gravel bed river: the Garonne\ud
river (France)

The objective of this paper is to relate phosphorus (P) transport dynamics and hydromorphological characteristics of a large human-influenced river, the River Garonne within a sector receiving the waste water of a sewage treatment plant for a population of 600 000. Two studies were conducted in 1997 and 1999 during two different hydrological conditions at low-flow periods. The 1997 study was carried out on an 18-km stretch with discharges varying between 33 and 53 m3/s and with very small fluctuations. The 1999 study concerned a longer stretch of 47 km, divided into four smaller reaches, and with discharges fluctuating rapidly from 40 to 108 m3/s.\ud
\ud
Downstream of the sewage treatment plant, total phosphorus (TP) concentrations ranged from 0.19 to 0.27 mg/L and were mainly in the dissolved form: between 60 and 78% of TP was dissolved reactive phosphorus (DRP). P concentrations were significantly lower upstream of the sewage treatment plant.\ud
\ud
By a mass-balance approach, we estimated that the sewage treatment plant represents more than half the input (between 59 and 67%) of the studied sector. TP dynamic is linked to suspended solids for discharges above 60 m3/s.\ud
\ud
During established low-flow period in the 1997 study (<60 m3/s), 22 and 27% of TP and DRP were retained by the river bed.\ud
\ud
In the 1999 study, under different low-water period hydraulic conditions, we calculate that particulate P retention occurred in two reaches among the four under study and only for discharges below 60 m3/s.\ud
We show that for established discharges below 60 m3/s, there is an active uptake of transported P by functional compartments (i.e. the hyporheic zone and the periphyton). During the low-water period with relatively high hydraulic fluctuations, and for discharges >60 m3/s, P retention is controlled as expected by suspended matter dynamics.\u
On the critical exponents of random k-SAT

There has been much recent interest in the satisfiability of random Boolean
formulas. A random k-SAT formula is the conjunction of m random clauses, each
of which is the disjunction of k literals (a variable or its negation). It is
known that when the number of variables n is large, there is a sharp transition
from satisfiability to unsatisfiability; in the case of 2-SAT this happens when
m/n --> 1, for 3-SAT the critical ratio is thought to be m/n ~ 4.2. The
sharpness of this transition is characterized by a critical exponent, sometimes
called \nu=\nu_k (the smaller the value of \nu the sharper the transition).
Experiments have suggested that \nu_3 = 1.5+-0.1, \nu_4 = 1.25+-0.05,
\nu_5=1.1+-0.05, \nu_6 = 1.05+-0.05, and heuristics have suggested that \nu_k
--> 1 as k --> infinity. We give here a simple proof that each of these
exponents is at least 2 (provided the exponent is well-defined). This result
holds for each of the three standard ensembles of random k-SAT formulas: m
clauses selected uniformly at random without replacement, m clauses selected
uniformly at random with replacement, and each clause selected with probability
p independent of the other clauses. We also obtain similar results for
q-colorability and the appearance of a q-core in a random graph.Comment: 11 pages. v2 has revised introduction and updated reference
The Scaling Window of the 2-SAT Transition

We consider the random 2-satisfiability problem, in which each instance is a
formula that is the conjunction of m clauses of the form (x or y), chosen
uniformly at random from among all 2-clauses on n Boolean variables and their
negations. As m and n tend to infinity in the ratio m/n --> alpha, the problem
is known to have a phase transition at alpha_c = 1, below which the probability
that the formula is satisfiable tends to one and above which it tends to zero.
We determine the finite-size scaling about this transition, namely the scaling
of the maximal window W(n,delta) = (alpha_-(n,delta),alpha_+(n,delta)) such
that the probability of satisfiability is greater than 1-delta for alpha <
alpha_- and is less than delta for alpha > alpha_+. We show that
W(n,delta)=(1-Theta(n^{-1/3}),1+Theta(n^{-1/3})), where the constants implicit
in Theta depend on delta. We also determine the rates at which the probability
of satisfiability approaches one and zero at the boundaries of the window.
Namely, for m=(1+epsilon)n, where epsilon may depend on n as long as |epsilon|
is sufficiently small and |epsilon|*n^(1/3) is sufficiently large, we show that
the probability of satisfiability decays like exp(-Theta(n*epsilon^3)) above
the window, and goes to one like 1-Theta(1/(n*|epsilon|^3)) below the window.
We prove these results by defining an order parameter for the transition and
establishing its scaling behavior in n both inside and outside the window.
Using this order parameter, we prove that the 2-SAT phase transition is
continuous with an order parameter critical exponent of 1. We also determine
the values of two other critical exponents, showing that the exponents of 2-SAT
are identical to those of the random graph.Comment: 57 pages. This version updates some reference
The Minimum Expectation Selection Problem

We define the min-min expectation selection problem (resp. max-min
expectation selection problem) to be that of selecting k out of n given
discrete probability distributions, to minimize (resp. maximize) the
expectation of the minimum value resulting when independent random variables
are drawn from the selected distributions. We assume each distribution has
finitely many atoms. Let d be the number of distinct values in the support of
the distributions. We show that if d is a constant greater than 2, the min-min
expectation problem is NP-complete but admits a fully polynomial time
approximation scheme. For d an arbitrary integer, it is NP-hard to approximate
the min-min expectation problem with any constant approximation factor. The
max-min expectation problem is polynomially solvable for constant d; we leave
open its complexity for variable d. We also show similar results for binary
selection problems in which we must choose one distribution from each of n
pairs of distributions.Comment: 13 pages, 1 figure. Full version of paper presented at 10th Int.
  Conf. Random Structures and Algorithms, Poznan, Poland, August 200
The emergence of a giant component in random subgraphs of pseudo-random
  graphs

Let $G$ be a $d$-regular graph $G$ on $n$ vertices. Suppose that the
adjacency matrix of $G$ is such that the eigenvalue $\lambda$ which is second
largest in absolute value satisfies $\lambda=o(d)$. Let $G_p$ with
$p=\frac{\alpha}{d}$ be obtained from $G$ by including each edge of $G$
independently with probability $p$. We show that if $\alpha<1$ then whp the
maximum component size of $G_p$ is $O(\log n)$ and if $\alpha>1$ then $G_p$
contains a unique giant component of size $\Omega(n)$, with all other
components of size $O(\log n)$.Comment: 9 page
Transfer Theorems and Asymptotic Distributional Results for m-ary Search
  Trees

We derive asymptotics of moments and identify limiting distributions, under
the random permutation model on m-ary search trees, for functionals that
satisfy recurrence relations of a simple additive form. Many important
functionals including the space requirement, internal path length, and the
so-called shape functional fall under this framework. The approach is based on
establishing transfer theorems that link the order of growth of the input into
a particular (deterministic) recurrence to the order of growth of the output.
The transfer theorems are used in conjunction with the method of moments to
establish limit laws. It is shown that (i) for small toll sequences $(t_n)$
[roughly, $t_n =O(n^{1 / 2})$] we have asymptotic normality if $m \leq 26$ and
typically periodic behavior if $m \geq 27$; (ii) for moderate toll sequences
[roughly, $t_n = \omega(n^{1 / 2})$ but $t_n = o(n)$] we have convergence to
non-normal distributions if $m \leq m_0$ (where $m_0 \geq 26$) and typically
periodic behavior if $m \geq m_0 + 1$; and (iii) for large toll sequences
[roughly, $t_n = \omega(n)$] we have convergence to non-normal distributions
for all values of m.Comment: 35 pages, 1 figure. Version 2 consists of expansion and rearragement
  of the introductory material to aid exposition and the shortening of
  Appendices A and B.
Sharp thresholds and percolation in the plane

Recently, the authors showed that the critical probability for random Voronoi
percolation in the plane is 1/2. A by-product of the method was a short proof
of the Harris-Kesten Theorem concerning bond percolation in the planar square
lattice. The aim of this paper is to show that the same techniques can be
applied to many other planar percolation models, both to obtain short proofs of
known results, and to prove new ones.Comment: 28 pages, 8 figures. Minor revisions and additions. To appear in
  Random Structures and Algorithm