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Hydrologic verification: A call for action and collaboration
Traditionally, little attention has been focused on the systematic verification of operational hydrologic forecasts. This paper summarizes the results of forecasts verification from 15 river basins in the United States. The verification scores for these forecast locations do not show improvement over the periods of record despite a number of forecast process improvements. In considering a root cause for these results, the authors note that the current paradigm for designing hydrologic forecast process improvements is driven by expert opinion and not by objective verification measures. The authors suggest that this paradigm should be modified and objective verification metrics should become the primary driver for hydrologic forecast process improvements. ©2007 American Meteorological Society
The channels of technology acquisition in commercial firms, and the NASA dissemination program
Technology acquisition in commercial firms, and NASA dissemination progra
Ames collaborative study of cosmic ray neutrons
The results of a collaborative study to define both the neutron flux and the spectrum more precisely and to develop a dosimetry package that can be flown quickly to altitude for solar flare events are described. Instrumentation and analysis techniques were used which were developed to measure accelerator-produced radiation. The instruments were flown in the Ames Research Center high altitude aircraft. Neutron instrumentation consisted of Bonner spheres with both active and passive detector elements, threshold detectors of both prompt-counter and activation-element types, a liquid scintillation spectrometer based on pulse-shape discrimination, and a moderated BF3 counter neutron monitor. In addition, charged particles were measured with a Reuter-Stokes ionization chamber system and dose equivalent with another instrument. Preliminary results from the first series of flights at 12.5 km (41,000 ft) are presented, including estimates of total neutron flux intensity and spectral shape and of the variation of intensity with altitude and geomagnetic latitude
Separating and Collapsing Electoral Control Types
[HHM20] discovered, for 7 pairs (C,D) of seemingly distinct standard
electoral control types, that C and D are identical: For each input I and each
election system, I is a Yes instance of both C and D, or of neither.
Surprisingly this had gone undetected, even as the field was score-carding how
many std. control types election systems were resistant to; various "different"
cells on such score cards were, unknowingly, duplicate effort on the same
issue. This naturally raises the worry that other pairs of control types are
also identical, and so work still is being needlessly duplicated.
We determine, for all std. control types, which pairs are, for elections
whose votes are linear orderings of the candidates, always identical. We show
that no identical control pairs exist beyond the known 7. We for 3 central
election systems determine which control pairs are identical ("collapse") with
respect to those systems, and we explore containment/incomparability
relationships between control pairs. For approval voting, which has a different
"type" for its votes, [HHM20]'s 7 collapses still hold. But we find 14
additional collapses that hold for approval voting but not for some election
systems whose votes are linear orderings. We find 1 additional collapse for
veto and none for plurality. We prove that each of the 3 election systems
mentioned have no collapses other than those inherited from [HHM20] or added
here. But we show many new containment relationships that hold between some
separating control pairs, and for each separating pair of std. control types
classify its separation in terms of containment (always, and strict on some
inputs) or incomparability.
Our work, for the general case and these 3 important election systems,
clarifies the landscape of the 44 std. control types, for each pair collapsing
or separating them, and also providing finer-grained information on the
separations.Comment: The arXiv.org metadata abstract is an abridged version; please see
the paper for the full abstrac
Search versus Search for Collapsing Electoral Control Types
Electoral control types are ways of trying to change the outcome of elections
by altering aspects of their composition and structure [BTT92]. We say two
compatible (i.e., having the same input types) control types that are about the
same election system E form a collapsing pair if for every possible input
(which typically consists of a candidate set, a vote set, a focus candidate,
and sometimes other parameters related to the nature of the attempted
alteration), either both or neither of the attempted attacks can be
successfully carried out [HHM20]. For each of the seven general (i.e., holding
for all election systems) electoral control type collapsing pairs found by
Hemaspaandra, Hemaspaandra, and Menton [HHM20] and for each of the additional
electoral control type collapsing pairs of Carleton et al. [CCH+ 22] for veto
and approval (and many other election systems in light of that paper's Theorems
3.6 and 3.9), both members of the collapsing pair have the same complexity
since as sets they are the same set. However, having the same complexity (as
sets) is not enough to guarantee that as search problems they have the same
complexity. In this paper, we explore the relationships between the search
versions of collapsing pairs. For each of the collapsing pairs of Hemaspaandra,
Hemaspaandra, and Menton [HHM20] and Carleton et al. [CCH+ 22], we prove that
the pair's members' search-version complexities are polynomially related (given
access, for cases when the winner problem itself is not in polynomial time, to
an oracle for the winner problem). Beyond that, we give efficient reductions
that from a solution to one compute a solution to the other. For the concrete
systems plurality, veto, and approval, we completely determine which of their
(due to our results) polynomially-related collapsing search-problem pairs are
polynomial-time computable and which are NP-hard.Comment: The metadata's abstract is abridged due to arXiv.org's
abstract-length limit. The paper itself has the unabridged (i.e., full)
abstrac
Precipitation and temperature ensemble forecasts from single-value forecasts
International audienceA procedure is presented to construct ensemble forecasts from single-value forecasts of precipitation and temperature. This involves dividing the spatial forecast domain and total forecast period into a number of parts that are treated as separate forecast events. The spatial domain is divided into hydrologic sub-basins. The total forecast period is divided into time periods, one for each model time step. For each event archived values of forecasts and corresponding observations are used to model the joint distribution of forecasts and observations. The conditional distribution of observations for a given single-value forecast is used to represent the corresponding probability distribution of events that may occur for that forecast. This conditional forecast distribution subsequently is used to create ensemble members that vary in space and time using the "Schaake Shuffle" (Clark et al, 2004). The resulting ensemble members have the same space-time patterns as historical observations so that space-time joint relationships between events that have a significant effect on hydrological response tend to be preserved. Forecast uncertainty is space and time-scale dependent. For a given lead time to the beginning of the valid period of an event, forecast uncertainty depends on the length of the forecast valid time period and the spatial area to which the forecast applies. Although the "Schaake Shuffle" procedure, when applied to construct ensemble members from a time-series of single value forecasts, may preserve some of this scale dependency, it may not be sufficient without additional constraint. To account more fully for the time-dependent structure of forecast uncertainty, events for additional "aggregate" forecast periods are defined as accumulations of different "base" forecast periods. The generated ensemble members can be ingested by an Ensemble Streamflow Prediction system to produce ensemble forecasts of streamflow and other hydrological variables that reflect the meteorological uncertainty. The methodology is illustrated by an application to generate temperature and precipitation ensemble forecasts for the American River in California. Parameter estimation and dependent validation results are presented based on operational single-value forecasts archives of short-range River Forecast Center (RFC) forecasts and medium-range ensemble mean forecasts from the National Weather Service (NWS) Global Forecast System (GFS)
Three-dimensional Ginzburg-Landau simulation of a vortex line displaced by a zigzag of pinning spheres
A vortex line is shaped by a zigzag of pinning centers and we study here how
far the stretched vortex line is able to follow this path. The pinning center
is described by an insulating sphere of coherence length size such that in its
surface the de Gennes boundary condition applies. We calculate the free energy
density of this system in the framework of the Ginzburg-Landau theory and study
the critical displacement beyond which the vortex line is detached from the
pinning center.Comment: Submitted to special issue of Prammna-Journal of Physics devoted to
the Vortex State Studie
Reading Videogames as (authorless) Literature
This article presents the outcomes of research, funded by the Arts and Humanities Research Council in England and informed by work in the fields of new literacy research, gaming studies and the socio-cultural framing of education, for which the videogame L.A. Noire (Rockstar Games, 2011) was studied within the orthodox framing of the English Literature curriculum at A Level (pre-University) and Undergraduate (degree level). There is a plethora of published research into the kinds of literacy practices evident in videogame play, virtual world engagement and related forms of digital reading and writing (Gee, 2003; Juul, 2005; Merchant, Gillen, Marsh and Davies, 2012; Apperley and Walsh, 2012; Bazalgette and Buckingham, 2012) as well as the implications of such for home / school learning (Dowdall, 2006; Jenkins, 2006; Potter, 2012) and for teachers’ own digital lives (Graham, 2012). Such studies have tended to focus on younger children and this research is also distinct from such work in the field in its exploration of the potential for certain kinds of videogame to be understood as 'digital transformations' of conventional ‘schooled’ literature. The outcomes of this project raise implications of such a conception for a further implementation of a ‘reframed’ literacy (Marsh, 2007) within the contemporary curriculum of a traditional and conservative ‘subject’. A mixed methods approach was adopted. Firstly, students contributing to a gamplay blog requiring them to discuss their in-game experience through the ‘language game’ of English Literature, culminating in answering a question constructed with the idioms of the subject’s set text ‘final examination’. Secondly, students taught their teachers to play L.A. Noire, with free choice over the context for this collaboration. Thirdly, participants returned to traditional roles in order to work through a set of study materials provided, designed to reproduce the conventions of the ‘study guide’ for literature education. Interviews were conducted after each phase and the outcomes informed a redrafting of the study materials which are now available online for teachers – this being the ‘practical’ outcome of the research (Berger and McDougall, 2012). In the act of inserting the study of L.A. Noire into the English Literature curriculum as currently framed, this research moves, through a practical ‘implementation’ beyond longstanding debates around narratology and ludology (Frasca, 2003; Juul, 2005) in the field of game studies (Leaning, 2012) through a direct connection to new literacy studies and raises epistemological questions about ‘subject identity’, informed by Bernstein (1996) and Bourdieu (1986) and the implications for digital transformations of texts for both ideas about cultural value in schooled literacy (Kendall and McDougall, 2011) and the politics of ‘expertise’ in pedagogic relations (Ranciere, 2009, Bennett, Kendall and McDougall, 2012a)
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