Applied probabilistic forecasting

In any actual forecast, the future evolution of the system is uncertain and the forecasting model is mathematically imperfect. Both, ontic uncertainties in the future (due to true stochasticity) and epistemic uncertainty of the model (reflecting structural imperfections) complicate the construction and evaluation of probabilistic forecast. In almost all nonlinear forecast models, the evolution of uncertainty in time is not tractable analytically and Monte Carlo approaches (”ensemble forecasting”) are widely used. This thesis advances our understanding of the construction of forecast densities from ensembles, the evolution of the resulting probability forecasts and methods of establishing skill (benchmarks). A novel method of partially correcting the model error is introduced and shown to outperform a competitive approach. The properties of Kernel dressing, a method of transforming ensembles into probability density functions, are investigated and the convergence of the approach is illustrated. A connection between forecasting and Information theory is examined by demonstrating that Kernel dressing via minimization of Ignorance implicitly leads to minimization of Kulback-Leibler divergence. The Ignorance score is critically examined in the context of other Information theory measures. The method of Dynamic Climatology is introduced as a new approach to establishing skill (benchmarking). Dynamic Climatology is a new, relatively simple, nearest neighbor based model shown to be of value in benchmarking of global circulation models of the ENSEMBLES project. ENSEMBLES is a project funded by the European Union bringing together all major European weather forecasting institutions in order to develop and test state-of-the-art seasonal weather forecasting models. Via benchmarking the seasonal forecasts of the ENSEMBLES models we demonstrate that Dynamic Climatology can help us better understand the value and forecasting performance of large scale circulation models. Lastly, a new approach to correcting (improving) imperfect model is presented, an idea inspired by [63]. The main idea is based on a two-stage procedure where a second stage ‘corrective’ model iteratively corrects systematic parts of forecasting errors produced by a first stage ‘core’ model. The corrector is of an iterative nature so that at a given time t the core model forecast is corrected and then used as an input into the next iteration of the core model to generate a time t + 1 forecast. Using two nonlinear systems we demonstrate that the iterative corrector is superior to alternative approaches based on direct (non-iterative) forecasts. While the choice of the corrector model class is flexible, we use radial basis functions. Radial basis functions are frequently used in statistical learning and/or surface approximations and involve a number of computational aspects which we discuss in some detail

Perbuatan Melawan Hukum atas Transaksi Efek Obligasi Surat Utang Negara Dalam Perspektif Undang-Undang Nomor 8 Tahun 1995 Tentang Pasar Modal

Aktivitas perdagangan efek yang semakin kompleks di bidang pasar modal mengakibatkan semakin canggihnya teknik yang digunakan oleh pihak-pihak tertentu dalam melakukan perbuatan yang bertentangan dengan hukum. Pengaturan terkait perbuatan yang dilarang dalam pasar modal sejatinya telah diatur dalam Undang-Undang Nomor 8 Tahun 1995 tentang Pasar Modal. Oleh karena itu, penulis tertarik untuk meneliti pelanggaran dalam perdagangan efek yang dapat dikaitkan dengan aturan-aturan yang terdapat dalam pasar modal. Adapun pokok permasalahan yang dibahas dalam penelitian ini adalah Bagaimana dasar pemenuhan perbuatan melawan hukum yang dilakukan oleh para pelaku yang terbukti bersalah dalam transaksi efek obligasi surat utang negara seri FR 0035 ditinjau dari UUPM dan bagaimana konsekuensi hukum terhadap pelaku yang terbukti bersalah terkait transaksi efek obligasi Surat Utang Negara dengan seri FR0035 pada putusan Nomor 746/Pdt.G/2017/PN.Jkt.Sel menurut Undang-Undang Pasar Modal. Untuk menjawab permasalahan di atas, penulis menggunakan metode penelitian secara normatif atau disebut juga penelitian kepustakaan yaitu mengkaji sumber-sumber bahan pustaka atau data-data yang sudah ada. Berdasarkan analisis terhadap tindakan yang dilakukan oleh Para pelaku tersebut dapat dikategorikan sebagai perbuatan melawan hukum. Adapun konsekuensi hukum yang terkait pelanggaran dalam pasar modal tersebut adalah sanksi yang dapat dikenakan terhadap tindakan tersebut menurut UUPM adalah sanksi perdata yang diatur dalam Pasal 111 UUPM berupa ganti rugi secara tanggung renteng. Kata Kunci: perbuatan melawan hukum, pasar modal, transaksi efek obligasi

Anatomical and physiological adaptations of high mountain plants in Ladakh

The Ladakh region of the northwestern Indian Himalaya is a high-elevation desert that presents a suite of environmental conditions that constrain plant growth. At lower elevations, aridity and high temperatures constrain plant growth. However, at higher elevations, temperature steeply drops and an increase in precipitation occurs. Therefore, the Ladakh region can be considered a natural laboratory where the adaptive responses of plant traits to moisture and temperature gradients can be observed. Plants in high mountain regions had to evolve and adapt to harsh environmental stress including low temperatures, UV radiation, short growing seasons, etc. Morphological, anatomical and physiological adaptations allow plants in Ladakh to grow at altitudes up to 6150 meters. This limit for plant growth in Ladakh is not set by the permanent snow line or any other mechanical barrier, but instead by the inability of plants to survive at such an elevation. This situation allows us to study the physiological limits of plant adaptations in extreme conditions. Thus, studying plants in Ladakh can bring an important understanding to adaptive ability of mountain plants.Ladak je horská oblast, nacházející se v severozápadní Indii, charakteristická velkým výškovým gradientem. V relativně nižších polohách se musejí rostliny potýkat zejména s vysokými teplotami a aridním klimatem. Množství srážek pakstoupá podél výškového gradientu, teplota naopak výrazně klesá. Ladak se díky tomu dá přirovnat k jakési přírodní laboratoři, ve které můžeme pozorovat změny různých vlastností rostlin v odpovědi na gradienty teploty a vlhkosti. Nepříznivé podmínky ve vyšších polohách, jako je nízká teplota, zvýšené ozáření atd., selektovaly u vysokohorských rostlin Ladaku celou řadu morfologických, anatomických a fyziologických adaptací. Tyto adaptace umožňují růst rostlin i v extrémních nadmořských výškách sahajících až k 6150 m n. m. Horní limit výskytu rostlin není dán přítomností fyzických bariér, jako je například hranice trvalého sněhu, a je tedy odrazem toho, jakým podmínkám se rostliny ještě dokázaly přizpůsobit. To umožňuje studovat adaptace rostlin na ty opravdu nejextrémnější podmínky. Díky výše uvedeným faktorům může studium rostlin v Ladaku nabídnout zajímavou perspektivu pro pochopení biologie horských rostlin.Katedra experimentální biologie rostlinDepartment of Experimental Plant BiologyFaculty of SciencePřírodovědecká fakult

Shadowing the rotating annulus. Part I: Measuring candidate trajectory shadowing times

An intuitively necessary requirement of models used to provide forecasts of a system's future is the existence of shadowing trajectories that are consistent with past observations of the system: given a system-model pair, do model trajectories exist that stay reasonably close to a sequence of observations of the system? Techniques for finding such trajectories are well-understood in low-dimensional systems, but there is significant interest in their application to high-dimensional weather and climate models. We build on work by Smith et al. [2010, Phys. Lett. A, 374, 2618-2623] and develop a method for measuring the time that individual "candidate" trajectories of high-dimensional models shadow observations, using a model of the thermally-driven rotating annulus in the perfect model scenario. Models of the annulus are intermediate in complexity between low-dimensional systems and global atmospheric models. We demonstrate our method by measuring shadowing times against artificially-generated observations for candidate trajectories beginning a fixed distance from truth in one of the annulus' chaotic flow regimes. The distribution of candidate shadowing times we calculated using our method corresponds closely to (1) the range of times over which the trajectories visually diverge from the observations and (2) the divergence time using a simple metric based on the distance between model trajectory and observations. An empirical relationship between the expected candidate shadowing times and the initial distance from truth confirms that the method behaves reasonably as parameters are varied.Comment: This paper was submitted to Physica D in 2010, but, after review, was not accepted. We no longer have the time or resources to work on this topic, but would like this record of our work to be available for others to read, cite, and follow up. 19 pages, 9 figure

Formation of monofunctional cisplatin-DNA adducts in carbonate buffer

Carbonate in its various forms is an important component in blood and the cytosol. Since, under conditions that simulate therapy, carbonate reacts with cisplatin to form carbonato complexes, one of which is taken up and/or modified by the cell [C.R. Centerwall, J. Goodisman, D.J. Kerwood, J. Am. Chem. Soc., 127 (2005) 12768–12769], cisplatin-carbonato complexes may be important in the mechanism of action of cisplatin. In this report we study the binding of cisplatin to pBR322 DNA in two different buffers, using gel electrophoresis. In 23.8 mM HEPES, N-(2-hydroxyethyl)-piperazine-N′-2-ethanesulfonic acid, 5 mM NaCl, pH 7.4 buffer, cisplatin produces aquated species, which react with DNA to unwind supercoiled Form I DNA, increasing its mobility, and reducing the binding of ethidium to DNA. This behavior is consistent with the formation of the well-known intrastrand crosslink on DNA. In 23.8 mM carbonate buffer, 5 mM NaCl, pH 7.4, cisplatin forms carbonato species that produce DNA-adducts which do not significantly change supercoiling but enhance binding of ethidium to DNA. This behavior is consistent with the formation of a monofunctional cisplatin adduct on DNA. These results show that aquated cisplatin and carbonato complexes of cisplatin produce different types of lesions on DNA and they underscore the importance of carrying out binding studies with cisplatin and DNA using conditions that approximate those found in the cell

Assessment of 3D velocity vector fields and turbulent kinetic energy in a realistic aortic phantom using multi-point variable-density velocity encoding

ISSN:1097-6647ISSN:1532-429

DNA methylation at birth and fine motor ability in childhood: an epigenome-wide association study with replication

DNA methylation; Cognitive function; Cord bloodMetilació de l'ADN; Funció cognitiva; Sang de cordóMetilación del ADN; Función cognitiva; Sangre de cordónLower fine motor performance in childhood has been associated with poorer cognitive development and neurodevelopmental conditions such as autism spectrum disorder, yet, biological underpinnings remain unclear. DNA methylation (DNAm), an essential process for healthy neurodevelopment, is a key molecular system of interest. In this study, we conducted the first epigenome-wide association study of neonatal DNAm with childhood fine motor ability and further examined the replicability of epigenetic markers in an independent cohort. The discovery study was embedded in Generation R, a large population-based prospective cohort, including a subsample of 924 ~ 1026 European-ancestry singletons with available data on DNAm in cord blood and fine motor ability at a mean (SD) age of 9.8 (0.4) years. Fine motor ability was measured using a finger-tapping test (3 subtests including left-, right-hand and bimanual), one of the most frequently used neuropsychological instruments of fine motor function. The replication study comprised 326 children with a mean (SD) age of 6.8 (0.4) years from an independent cohort, the INfancia Medio Ambiente (INMA) study. Four CpG sites at birth were prospectively associated with childhood fine motor ability after genome-wide correction. Of these, one CpG (cg07783800 in GNG4) was replicated in INMA, showing that lower levels of methylation at this site were associated with lower fine motor performance in both cohorts. GNG4 is highly expressed in the brain and has been implicated in cognitive decline. Our findings support a prospective, reproducible association between DNAm at birth and fine motor ability in childhood, pointing to GNG4 methylation at birth as a potential biomarker of fine motor ability.The EWAS data was funded by a grant from the Netherlands Genomics Initiative (NGI)/Netherlands Organisation for Scientific Research (NWO) Netherlands Consortium for Healthy Aging (NCHA; project nr. 050-060-810), funds from the Genetic Laboratory of the Department of Internal Medicine, Erasmus MC, and a grant from the National Institute of Child and Human Development (R01HD068437). HT was supported by a grant of the Dutch Ministry of Education, Culture, and Science and the Netherlands Organization for Scientific Research (NWO grant No. 024.001.003, Consortium on Individual Development). FS was supported by a Royal Netherlands Academy of Science and Art (KNAW) Van Leersum fellowship. ML is supported by the scholarship from the China Scholarship Council (201706990036). CC is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme under grant agreements No 101039672 (TEMPO) and No 848158 (EarlyCause). This project received funding from the European Union’s Horizon 2020 research and innovation programme (733206, LifeCycle).The epigenetic studies in INMA were mainly funded by grants from Instituto de Salud Carlos III (Red INMA G03/176, CB06/02/0041, CP18/00018), Spanish Ministry of Health (FIS-PI04/1436, FIS-PI08/1151 including FEDER funds, FIS-PI11/00610, FIS-FEDER-PI06/0867, FIS-FEDER-PI03-1615) Generalitat de Catalunya-CIRIT 1999SGR 00241, Fundació La marató de TV3 (090430), EU Commission (261357-MeDALL: Mechanisms of the Development of ALLergy), and European Research Council (268479-BREATHE: BRain dEvelopment and Air polluTion ultrafine particles in scHool childrEn)

Shadowing the rotating annulus. Part II: Gradient descent in the perfect model scenario

Shadowing trajectories are model trajectories consistent with a sequence of observations of a system, given a distribution of observational noise. The existence of such trajectories is a desirable property of any forecast model. Gradient descent of indeterminism is a well-established technique for finding shadowing trajectories in low-dimensional analytical systems. Here we apply it to the thermally-driven rotating annulus, a laboratory experiment intermediate in model complexity and physical idealisation between analytical systems and global, comprehensive atmospheric models. We work in the perfect model scenario using the MORALS model to generate a sequence of noisy observations in a chaotic flow regime. We demonstrate that the gradient descent technique recovers a pseudo-orbit of model states significantly closer to a model trajectory than the initial sequence. Gradient-free descent is used, where the adjoint model is set to $\lambda$I in the absence of a full adjoint model. The indeterminism of the pseudo-orbit falls by two orders of magnitude during the descent, but we find that the distance between the pseudo-orbit and the initial, true, model trajectory reaches a minimum and then diverges from truth. We attribute this to the use of the $\lambda$-adjoint, which is well suited to noise reduction but not to finely-tuned convergence towards a model trajectory. We find that $\lambda=0.25$ gives optimal results, and that candidate model trajectories begun from this pseudo-orbit shadow the observations for up to 80 s, about the length of the longest timescale of the system, and similar to expected shadowing times based on the distance between the pseudo-orbit and the truth. There is great potential for using this method with real laboratory data.Comment: This paper was originally prepared for submission in 2011; but, after Part I was not accepted, it was not submitted. It has not been peer-reviewed. We no longer have the time or resources to work on this topic, but would like this record of our work to be available for others to read, cite, and follow up. 22 pages, 11 figure