Absence Of Observations Research Articles

Using modelled stream temperatures to predict macro‐spatial patterns of stream invertebrate biodiversity

Summary Stream temperature is thought to be a primary determinant of the macro‐spatial distribution of stream biota, but we lack temperature data for most streams. Past research often relied on surrogates, such as altitude, latitude, catchment area (ALCA) and air temperature to study biota–temperature relationships. However, temperature surrogates may not accurately represent the thermal environments experienced by the biota and could thus produce misleading inferences regarding such relationships. In the absence of observations, modelled stream temperature could improve both predictions and interpretations of stream biodiversity patterns. We tested this hypothesis by relating stream benthic invertebrate assemblage structure and composition at 92 reference‐quality streams to ALCA, air temperature, modelled stream temperature and measured stream temperature, that is a progression from a coarse surrogate to directly measured water temperature. Modelled stream temperatures were obtained from a U.S.A.‐wide model developed previously with data from 569 reference‐quality sites. Variation in taxonomic composition, measured with an ordination, was strongly and almost identically associated with both modelled and measured stream temperature, but was less strongly associated with ALCA and air temperature. We also built predictive niche models to assess how choice of thermal metrics affected model performance. Model performance was measured as the precision with which each model predicted the number of taxa at a site (i.e. observed‐to‐expected taxon ratios). Niche models that contained modelled or measured stream temperature were more precise than those based on air temperature and ALCA. In addition, we compared the predicted probabilities of occurrence using niche models based on both modelled and measured stream temperatures. The two produced predicted probabilities of occurrence that were statistically indistinguishable for most (79%) taxa. Finally, we calculated thermal optima for each taxon as the abundance‐weighted average of stream temperature at sites where each taxon occurred. Thermal optima produced with modelled and measured stream temperatures were almost identical. Large‐scale models of stream temperature can be sufficiently accurate and precise to detect temperature‐driven patterns in stream biodiversity and should be useful in predicting the effects of climate change and other human‐caused thermal alterations on stream biodiversity.

From maps to movies: high-resolution time-varying sensitivity analysis for spatially distributed watershed models

Abstract. Distributed watershed models are now widely used in practice to simulate runoff responses at high spatial and temporal resolutions. Counter to this purpose, diagnostic analyses of distributed models currently aggregate performance measures in space and/or time and are thus disconnected from the models' operational and scientific goals. To address this disconnect, this study contributes a novel approach for computing and visualizing time-varying global sensitivity indices for spatially distributed model parameters. The high-resolution model diagnostics employ the method of Morris to identify evolving patterns in dominant model processes at sub-daily timescales over a six-month period. The method is demonstrated on the United States National Weather Service's Hydrology Laboratory Research Distributed Hydrologic Model (HL-RDHM) in the Blue River watershed, Oklahoma, USA. Three hydrologic events are selected from within the six-month period to investigate the patterns in spatiotemporal sensitivities that emerge as a function of forcing patterns as well as wet-to-dry transitions. Events with similar magnitudes and durations exhibit significantly different performance controls in space and time, indicating that the diagnostic inferences drawn from representative events will be heavily biased by the a priori selection of those events. By contrast, this study demonstrates high-resolution time-varying sensitivity analysis, requiring no assumptions regarding representative events and allowing modelers to identify transitions between sets of dominant parameters or processes a posteriori. The proposed approach details the dynamics of parameter sensitivity in nearly continuous time, providing critical diagnostic insights into the underlying model processes driving predictions. Furthermore, the approach offers the potential to identify transition points between dominant parameters and processes in the absence of observations, such as under nonstationarity.

Texas City refinery accident: Case study in breakdown of defense-in-depth and violation of the safety–diagnosability principle in design

In 2005 an explosion rocked the BP Texas City refinery, killing 15 people and injuring 180. The company incurred direct and indirect financial losses on the order of billions of dollars for victims’ compensation as well as significant property damage and loss of production. The internal BP accident investigation and the Chemical Safety Board investigation identified a number of factors that contributed to the accident. In this work, we first examine the accident pathogens or lurking adverse conditions at the refinery prior to the accident. We then analyze the sequence of events that led to the explosion, and we highlight some of the provisions for the implementation of defense-in-depth and their failures. Next we identify a fundamental failure mechanism in this accident, namely the absence of observability or ability to diagnose hazardous states in the operation of the refinery, in particular within the raffinate splitter tower and the blowdown drum of the isomerization unit. We propose a general safety–diagnosability principle for supporting accident prevention, which requires that all safety-degrading events or states that defense-in-depth is meant to protect against be diagnosable, and that breaches of safety barriers be unambiguously monitored and reported. The safety–diagnosability principle supports the development of a “living” or online quantitative risk assessment, which in turn can help re-order risk priorities in real time based on emerging hazards, and re-allocate defensive resources. We argue that the safety–diagnosability principle is an essential ingredient for improving operators’ situation awareness. Violation of the safety–diagnosability principle translates into a shrinking of the time window available for operators to understand an unfolding hazardous situation and intervene to abate it. Compliance with this new safety principle provides one way to improve operators’ sensemaking and situation awareness and decrease the conditional probability that an accident will occur following an adverse initiating event. We suggest that defense-in-depth be augmented with this principle, without which it can degenerate into an ineffective defense-blind safety strategy.

<b> A necessidade de regulamentação dos conflitos armados para o reestabelecimento da democracia </b> - doi: 10.5102/rdi.v9i2.1840

This paper has the scope of analyzing the humanitarian needs on the battlefi eld which are little, or not at all, regulated, as well as the absence of observation of rules of jus post bellum, and its relations with the establishment of democracy aft er a confl ict, which aims to establishing peace. By understanding that the standard norms are made through history, this paper will present an account of the formation of international humanitarian law. Next, it will expose the obscurities and lack of regulation of humanitarian aid during confl icts. Th e conceptual ideal of jus post bellum will also be presented, followed by the defense of the need to create a principled normative framework. Also, an exhibition of what is democracy through its mechanisms, given that they can be seen practically as ways to peace. In conclusion, it will be shown that there are guiding and normative principles of jus post bellum, which are not, yet, consensual among scholars regarding their application. However with the collaboration of the UN Peacebuilding Commission, more vigorously work has been seen in defi ning this framework, which will not be useful if States do not begin to respect the international system.

A 90-day oral (dietary) toxicity study of arruva, an R, R-monatin salt isomer, in Crl:CD-1(ICR) mice

R,R-Monatin [2R,4R- isomer of 2-hydroxy-2-(indol-3-ylmethyl)-4-aminoglutaric acid] is one of four natural constituent isomers in the root bark of Sclerochitin ilicifolius; and "arruva" is the common/usual name that is proposed to represent R,R-monatin salt forms, which have potential use as high potency sweetener food ingredients. In the present study, groups of male and female Crl:CD-1(ICR) mice were exposed to 0 (control), 5000, 10,000, 20,000, or 35,000ppm of arruva in the diet for 90days. There were no toxicologically relevant clinical or histopathological findings in any of the test article-treated groups. Significantly lower mean body weights and cumulative body weight gains were noted in the 35,000ppm group when compared to the control group. Mean body weights in the 35,000ppm group males and females were 9% and 7% less than the control group, respectively, at week 13. In the absence of observations associated with systemic toxicity and in consideration of the magnitude of body weight difference, these effects were not considered toxicologically significant. Based on the results of this study, the dietary no-observed-adverse-effect level (NOAEL) of arruva for 90days in male and female mice was 35,000ppm (equivalent to an exposure level of 5764 and 8013mg/kg bw/day, respectively).

Object-based selection from spatially-invariant representations: evidence from a feature-report task

Attention selects objects as well as locations. When attention selects an object's features, observers identify two features from a single object more accurately than two features from two different objects (object-based effect of attention; e.g., Duncan, Journal of Experimental Psychology: General, 113, 501-517, 1984). Several studies have demonstrated that object-based attention can operate at a late visual processing stage that is independent of objects' spatial information (Awh, Dhaliwal, Christensen, & Matsukura, Psychological Science, 12, 329-334, 2001; Matsukura & Vecera, Psychonomic Bulletin & Review, 16, 529-536, 2009; Vecera, Journal of Experimental Psychology: General, 126, 14-18, 1997; Vecera & Farah, Journal of Experimental Psychology: General, 123, 146-160, 1994). In the present study, we asked two questions regarding this late object-based selection mechanism. In Part I, we investigated how observers' foreknowledge of to-be-reported features allows attention to select objects, as opposed to individual features. Using a feature-report task, a significant object-based effect was observed when to-be-reported features were known in advance but not when this advance knowledge was absent. In Part II, we examined what drives attention to select objects rather than individual features in the absence of observers' foreknowledge of to-be-reported features. Results suggested that, when there was no opportunity for observers to direct their attention to objects that possess to-be-reported features at the time of stimulus presentation, these stimuli must retain strong perceptual cues to establish themselves as separate objects.

Processing of the Incentive for Social Approval in the Ventral Striatum during Charitable Donation

Human behaviors are motivated not only by materialistic rewards but also by abstract social rewards, such as the approval of others. When choosing an action in social situations, to evaluate each action, the brain must convert different types of reward (such as money or social approval) into a common scale. Here using fMRI, we investigated the neural correlates of such valuation computations while individuals freely decided whether to donate to real charities or to take the money for themselves in the presence or absence of observers. Behavioral evidence showed that the mere presence of observers increased donation rates, and neuroimaging results revealed that activation in the ventral striatum before the same choice ("donate" or "not donate") was significantly modulated by the presence of observers. Particularly high striatal activations were observed when a high social reward was expected (donation in public) and when there was the potential for monetary gain without social cost (no donation in the absence of observers). These findings highlight the importance of this area in representing both social and monetary rewards as a "decision utility" and add to the understanding of how the brain makes a choice using a "common neural currency" in social situations.

A Reformulation of von Neumann’s Postulates on Quantum Measurement by Using Two Theorems in Clifford Algebra

According to a procedure previously introduced from Y. Ilamed and N. Salingaros, we start giving proof of two existing Clifford algebras, the Si that has isomorphism with that one of Pauli matrices and the Ni,±1 where Ni stands for the dihedral Clifford algebra. The salient feature is that we show that the Ni,±1 may be obtained from the Si algebra when we attribute a numerical value (+1 or −1) to one of the basic elements (e1,e2,e3) of the Si. We utilize such result to advance a criterium under which the Si algebra has as counterpart the description of quantum systems that in standard quantum mechanics are considered in absence of observation and quantum measurement while the Ni,±1 attend when a quantum measurement is performed on such system with advent of wave function collapse. The physical content of the criterium is that the quantum measurement with wave function collapse induces the passage in the considered quantum system from the Si to Ni,+1 or to the Ni,−1 algebras, where each algebra has of course its proper rules of commutation. After a proper discussion on the difference between decoherence and wave function collapse, we re-examine the von Neumann postulate on quantum measurement, and we give a proper justification of such postulate by using the Si algebra. Soon after we study some applications of the above mentioned criterium to some cases of interest in standard quantum mechanics, analyzing in particular a two state quantum system, the case of time dependent interaction of such system with a measuring apparatus and finally the case of a quantum system plus measuring apparatus developed at the order n=4 of the considered Clifford algebras and of the corresponding density matrix in standard quantum mechanics. In each of such cases examined, we find that the passage from the algebra Si to Ni,±1, considered during the quantum measurement of the system, actually describes the collapse of the wave function. Therefore we conclude that the actual quantum measurement has as counterpart in the Clifford algebraic description, the passage from the Si to the Ni,±1 Clifford algebras, reaching in this manner the objective to reformulate von Neumann postulate on quantum measurement and proposing a self-consistent formulation of quantum theory.

Distributed LMS for Consensus-Based In-Network Adaptive Processing

Adaptive algorithms based on in-network processing of distributed observations are well-motivated for online parameter estimation and tracking of (non)stationary signals using ad hoc wireless sensor networks (WSNs). To this end, a fully distributed least mean-square (D-LMS) algorithm is developed in this paper, offering simplicity and flexibility while solely requiring single-hop communications among sensors. The resultant estimator minimizes a pertinent squared-error cost by resorting to i) the alternating-direction method of multipliers so as to gain the desired degree of parallelization and ii) a stochastic approximation iteration to cope with the time-varying statistics of the process under consideration. Information is efficiently percolated across the WSN using a subset of ldquobridgerdquo sensors, which further tradeoff communication cost for robustness to sensor failures. For a linear data model and under mild assumptions aligned with those considered in the centralized LMS, stability of the novel D-LMS algorithm is established to guarantee that local sensor estimation error norms remain bounded most of the time. Interestingly, this weak stochastic stability result extends to the pragmatic setup where intersensor communications are corrupted by additive noise. In the absence of observation and communication noise, consensus is achieved almost surely as local estimates are shown exponentially convergent to the parameter of interest with probability one. Mean-square error performance of D-LMS is also assessed. Numerical simulations: i) illustrate that D-LMS outperforms existing alternatives that rely either on information diffusion among neighboring sensors, or, local sensor filtering; ii) highlight its tracking capabilities; and iii) corroborate the stability and performance analysis results.

Ultrarelativistic Electrons in Jupiter's Inner Magnetosphere: First Observation of Angular Distributions in the 2.5 to 6 R J Region

Jupiter has been recognized as a probable location of magnetically trapped ultrarelativistic electrons since its discovery as a source of polarized decimeter radio waves. A series of spacecraft (Pioneers 10 and 11, Voyagers 1 and 2, Ulysses, Cassini, and New Horizons) have flown by and orbited Jupiter with the goal of observing the trapped radiation that generates the radio waves. Follow-on studies have attempted to reconcile intensity patterns of Jovian radio emission with direct measurements of ultrarelativistic electrons that radiate via a synchrotron process. These studies have been limited by the absence of observations of measurement of the angular distributions of ultrarelativistic electrons. Since the strongest synchrotron emission from an electron occurs near its mirror point, the distribution of synchrotron emission is expected to follow the distribution of the mirror points. From the description of magnetic trapping, it further follows that observing the angular distribution at low magnetic latitudes allows one to infer the distribution of mirror points along the magnetic field. Observations made with the Energetic Particle Detector aboard the Galileo orbiter during its penultimate Jovian orbit provided excellent angular distribution observations on the magnetic field lines containing the electrons which account for most of the Jovian decimeter radiation. Because ultrarelativistic electrons are especially difficult to observe directly with low-mass flight instruments, inferring angular distributions for such particles required extensive modeling of instrument responses that matched the observations. We report these results here and suggest their implications for past and future studies of astrophysical synchrotron emission.

Crusader Art in The Holy Land: From the Third Crusade to the Fall of Acre, 1187-1291 (review)

Crusader Art in The Holy Land: From the Third Crusade to the Fall of Acre, 1187-1291. By Jaroslav Folda. (New York: Cambridge University Press. 2005. Pp. Ixvii, 714; 11 colour plates, 10 maps, 415 figures, 501 illustrations on the compact disc. $150.00.) Jaroslav Folda's monumental book is another link in his life's work that has been dedicated to the research of crusader art. Besides his numerous articles on the subject, his books show systematic development, from his Crusader Manuscript Ilumination at Saint-Jean d'Acre, 12 75-1291 (Princeton University Press, 1976), through The Art of the Crusades in the Holy Land 10981187 (Cambridge University Press, 1995) and up to the current comprehensive volume, which will be a basic resource to any researcher of the crusaders. The need for such a book was evident for a considerable period of time, since only parts of the relevant period have been investigated, and no aE-embracing view on the subject existed. In his book, Folda examines the art created for the crusaders by various social classes and ethnic groups, from Western merchants to Muslims in the Orient. But more than that, the book provides significant new contributions to a number of aspects and concepts in the research of crusader art. Unlike any previous work, Folda places art itself, in its various forms, in a primary position, and raises the discussion on the essence of crusader art of the thirteenth century to a theoretical level, thus creating and setting it as a significant chapter in art history. This is a major innovation. Unlike many art historians, Folda discusses historical events in the Holy Land, which he considers relevant to his research. It is my belief that this meticulous discussion contributes to the interpretation of the conditions of artistic creation in the following chapters. In the introduction to his book, Folda informs the reader of his work process and the significance he accords to each chapter. The first chapter, dedicated to the historiography of crusader art history, is of the utmost significance. Here, Folda not only reviews the contribution of the various scholars of the Latin Orient since the nineteenth century, but also examines the efforts and perceptions of those who shaped the field in the twentieth century. Thus, he presents a progressive process of the development of research, in all artistic media, discussing, for example, the work of two of the leading art historians, Camille Enlart and Paul Deschamps, whose works paved the way for future scholarship and are still in use today. In an extensive and accurate analysis, Folda shows Enlart's positions, specifically the parallels Enlart draws between crusader architecture and the contemporaneous architecture in France and his constant desire to view crusader architecture as part of French architecture; Folda also points to the relative absence of observations in Enlart's work regarding local elements that do not fit his theory. …

Bayesian inference for normal multiple-trait individual-tree models with missing records via full conjugate Gibbs

In forest genetics, restricted maximum likelihood (REML) estimation of (co)variance components from normal multiple-trait individual-tree models is affected by the absence of observations in any trait and individual. Missing records affect the form of the distribution of REML estimates of genetics parameters, or of functions of them, and the estimating equations are computationally involved when several traits are analysed. An alternative to REML estimation is a fully Bayesian approach through Markov chain Monte Carlo. The present research describes the use of the full conjugate Gibbs algorithm proposed by Cantet et al. (R.J.C. Cantet, A.N. Birchmeier, and J.P. Steibel. 2004. Genet. Sel. Evol. 36: 49–64) to estimate (co)variance components in multiple-trait individual-tree models. This algorithm converges faster to the marginal posterior densities of the parameters than regular data augmentation from multivariate normal data with missing records. An expression to calculate the deviance information criterion for the selection of linear parameters in normal multiple-trait models is also given. The developments are illustrated by means of data from different crosses of two species of Pinus.

Interaction of B chromosomes with A or B chromosomes in segregation in insects

Additional or B chromosomes not belonging to the regular karyotype of a species are found in many animal and plant groups. They form a highly heterogeneous group with respect to their morphology and behaviour both in mitosis and meiosis. Achiasmatic mechanisms that ensure the segregation of a B chromosome from another B chromosome or from an A chromosome are reviewed. An achiasmatic mechanism characterized by the “distance pairing” of segregating univalents at metaphase I was found to be responsible for the preferential segregation of B chromosome univalents in Hemerobius marginatus L. (Neuroptera), and a mechanism characterized by the “touch and go pairing” of segregating univalents was responsible for the highly regular segregation of a B chromosome and the X chromosome in Rhinocola aceris (L.) (Psylloidea, Homoptera). The latter mechanism resulted in the integration of a B chromosome to the A chromosome set as a Y chromosome in a psyllid species Cacopsylla peregrina (Frst.). Furthermore, B chromosomes can disturb the regular segregation of the achiasmatic X and Y chromosomes resulting in the formation of X0/XY polymorphism in a population, which might precede the loss of the Y chromosome. The absence of observations on accurately functioning achiasmatic segregation mechanisms in grasshoppers (Orthoptera) was attributed to the X and B chromosomes, which re-orient one or several times during metaphase I. Apparently, these re-orientations mask any achiasmatic segregation mechanism that might operate during meiotic prophase in these insects.

Estimating true age-dependence in survival when only adults can be observed: an example with Black-legged Kittiwakes

In long-lived birds, pre-breeders are often difficult or impossible to observe, and even though a proportion of marked adults may be of known age, the estimation of age-specific survival is complicated by the absence of observations during the first years of life. New developments in MARK now allow use of an updated individual covariate. We used this powerful approach to model age-dependence in survival of Black-legged Kittiwakes (Rissa tridactyla) at a North Sea colony. Although only 69 marked breeders were of known age, there was strong evidence for a quadratic relationship between true age and survival. We believe that this simple but powerful approach could be implemented for many species and could provide improved estimates of how survival changes with age, a central theme in life history theory.

Improved general circulation models of the Martian atmosphere from the surface to above 80 km

We describe a set of two “new generation” general circulation models of the Martian atmosphere derived from the models we originally developed in the early 1990s. The two new models share the same physical parameterizations but use two complementary numerical methods to solve the atmospheric dynamic equations. The vertical resolution near the surface has been refined, and the vertical domain has been extended to above 80 km. These changes are accompanied by the inclusion of state‐of‐the‐art parameterizations to better simulate the dynamical and physical processes near the surface (boundary layer scheme, subgrid‐scale topography parameterization, etc.) and at high altitude (gravity wave drag). In addition, radiative transfer calculations and the representation of polar processes have been significantly improved. We present some examples of zonal‐mean fields from simulations using the model at several seasons. One relatively novel aspect, previously introduced by Wilson [1997], is that around northern winter solstice the strong pole to pole diabatic forcing creates a quasi‐global, angular‐momentum conserving Hadley cell which has no terrestrial equivalent. Within such a cell the Coriolis forces accelerate the winter meridional flow toward the pole and induce a strong warming of the middle polar atmosphere down to 25 km. This winter polar warming had been observed but not properly modeled until recently. In fact, thermal inversions are generally predicted above one, and often both, poles around 60–70 km. However, the Mars middle atmosphere above 40 km is found to be very model‐sensitive and thus difficult to simulate accurately in the absence of observations.

Representational flexibility and response control in a multistep multilocation search task.

Three experiments were conducted to explore the determinants of 2-year-olds' perseverative errors in a search task. In Experiment 1, children either retrieved an object during a preswitch phase or merely observed a hiding event. Active search produced perseveration on postswitch trials, but mere observation did not. In Experiment 2, similar results were found, even when active search occurred in the absence of observation. Finally, in Experiment 3, children observed a hiding event at 1 location on some pretest trials and simply retrieved an object at a different location on other trials. On test trials, in which an object was hidden at a 3rd location, children tended to search where they had searched previously. Together, the results indicate that active search is required to elicit perseveration, which points to failures of response control rather than representational inflexibility.

A study of frost events in areas characterised by the absence of observations

Serious events of radiative frost were reported in an important agricultural area of central Macedonia, the valley of Lagadas, at the end of March 1994. Since the phenomenon has a strong local character and no surface observations are available, a simulation is performed using a three dimensional numerical model in order to investigate the horizontal and vertical thermal structure of the lower troposphere during the frost event. The synoptic analysis reveals that the background flow was weak, associated with anticyclonic circulation and insignificant pressure gradient in the lower troposphere. Under these synoptic conditions, it was demonstrated that the meteorological model represents successfully the temperature and wind fields over the valley of Lagadas during the frost event. It appears that the model can serve as an alternative method to analyse the characteristics of the radiative frost that occurs very frequently over the examined area associated with substantial economic repercussion.

Weather forecasting for aviation and marine operations in the Antarctic Peninsula region

AbstractAn account is given of one Austral summer's experience of forecasting for flying activities and marine operations around the Antarctic Peninsula. Data available included surface and upper‐air observations, analyses and forecasts from the UK Meteorological Office global, 19‐level model and AVHRR satellite imagery. The numerical analyses and forecasts provided good guidance and correctly represented most of the synoptic‐scale features. A number of mesoscale disturbances affected the central Peninsula area and the AVHRR imagery was very valuable in allowing the development and track of these systems to be followed. The major problems were the absence of observations to the west of the Peninsula, the lack of radiosonde ascents from the Peninsula itself and the complexity of local wind systems as a result of the topography. Forecasting frontal activity over the ocean areas was also very difficult because of the unavailability of precipitation forecasts in the GRIB data.

Relating surface albedos in GCM to remotely sensed data

The albedo of land surfaces is an important parameter for climate models. Observations over large areas are determined by satellite-sensed radiation from a single direction. This bidirectional reflectance is related to albedo by integration over all view angles. In the absence of observations at all view angles, a model of the radiative transfer through the atmosphere and at the surface is required to carry out this integration and to relate observations at one or a limited number of angles to surface albedo. Ideally, the same surface radiative model would be used to represent albedos in climate models. Both remote sensing and climate models require simple expressions for surface radiative models that are computationally inexpensive. We develop an analytic solution for reflection from a homogeneous leaf canopy with statistically prescribed leaf orientations. Following the approach of Hapke for planetary surfaces, this solution is used with adjustable parameters to invert observations of canopy bidirectional reflectance and define values for the model parameters. We allow for the asymmetric scattering resulting from leaf geometry and leaf-scattering properties. The former results from the product of projections of the leaf normal in the source and view directions integrated over the leaf distribution. This integration is approximated by simple analytic functions. The analytic solution is exact in the single scattering limit for the model assumed but uses a simple two-stream solution to include multiple scattering contributions to the bidirectional reflectance. The accuracy of the procedure is bench-marked using the ray-tracing model of Kimes. The analytic bidirectional reflectances agree with the numerical solution with relative errors less than 10% for near-infrared and less than 1% for visible radiation. With the use of a more accurate two-stream approach available for total fluxes, analytic albedos agree with those computed numerically with even smaller relative error. Application to remote sensing is illustrated with two examples: Kimes' lawn and Kriebel's pasture land. The inferred parameters are physically plausible. The observations are fit with an r.m.s. error of the order of 5–10%.

Non-linear state smoothing and filtering in blocks for dynamic systems with missing observations

State smoothing and filtering are treated for non-linear dynamic systems in the absence of observations in a considered observation interval. Models are taken to be non-linear functions of the states, disturbance noises, and observation noises, whereas the state estimation of these models cannot, in general, be performed by classical estimation schemes, such as the extended Kalman filter. State estimation is performed in blocks by estimating missing observations with interpolating functions. The resulting estimation scheme requires a constant memory for its implementation.