Computational methods for risk-averse undiscounted transient markov models

The total cost problem for discrete-time controlled transient Markov models is considered. The objective functional is a Markov dynamic risk measure of the total cost. Two solution methods, value and policy iteration, are proposed, and their convergence is analyzed. In the policy iteration method, we propose two algorithms for policy evaluation: the nonsmooth Newton method and convex programming, and we prove their convergence. The results are illustrated on a credit limit control problem. © 2014 INFORMS

Risk-averse control of undiscounted transient Markov models

We use Markov risk measures to formulate a risk-averse version of the undiscounted total cost problem for a transient controlled Markov process. Using the new concept of a multikernel, we derive conditions for a system to be risk transient, that is, to have finite risk over an infinite time horizon. We derive risk-averse dynamic programming equations satisfied by the optimal policy and we describe methods for solving these equations. We illustrate the results on an optimal stopping problem and an organ transplantation problem. © 2014 Society for Industrial and Applied Mathematic

Minimising multi-centre radiomics variability through image normalisation:a pilot study

Radiomics is an emerging technique for the quantification of imaging data that has recently shown great promise for deeper phenotyping of cardiovascular disease. Thus far, the technique has been mostly applied in single-centre studies. However, one of the main difficulties in multi-centre imaging studies is the inherent variability of image characteristics due to centre differences. In this paper, a comprehensive analysis of radiomics variability under several image- and feature-based normalisation techniques was conducted using a multi-centre cardiovascular magnetic resonance dataset. 218 subjects divided into healthy (n = 112) and hypertrophic cardiomyopathy (n = 106, HCM) groups from five different centres were considered. First and second order texture radiomic features were extracted from three regions of interest, namely the left and right ventricular cavities and the left ventricular myocardium. Two methods were used to assess features' variability. First, feature distributions were compared across centres to obtain a distribution similarity index. Second, two classification tasks were proposed to assess: (1) the amount of centre-related information encoded in normalised features (centre identification) and (2) the generalisation ability for a classification model when trained on these features (healthy versus HCM classification). The results showed that the feature-based harmonisation technique ComBat is able to remove the variability introduced by centre information from radiomic features, at the expense of slightly degrading classification performance. Piecewise linear histogram matching normalisation gave features with greater generalisation ability for classification ( balanced accuracy in between 0.78 ± 0.08 and 0.79 ± 0.09). Models trained with features from images without normalisation showed the worst performance overall (balanced accuracy in between 0.45 ± 0.28 and 0.60 ± 0.22). In conclusion, centre-related information removal did not imply good generalisation ability for classification

Bilkent University at TRECVID 2005

We describe our second-time participation, that includes one high-level feature extraction run, and three manual and one interactive search runs, to the TRECVID video retrieval evaluation. All of these runs have used a system trained on the common development collection. Only visual and textual information were used where visual information consisted of color, texture and edgebased low-level features and textual information consisted of the speech transcript provided in the collection. With the experience gained with our second-time participation, we are in the process of building a system for automatic classification and indexing of video archives

Do the rodents have a role in transmission of cutaneous leishmaniasis in Turkey? [Türkiye’de kutanöz leyşmanyaziste kemiricilerin rolü var mı?]

PubMed ID: 30156512Leishmaniasis is a zoonotic/anthroponotic vector borne parasitic infection which is caused by Leishmania species and transmitted by sand flies (Phlebotomus spp.) The reservoirs of Leishmania species in nature are various wild and domestic carnivores, rodents and human. The aim of this study was to investigate whether the rodents in genera Meriones, Mesocricetus, Rattus and Mus which inhabit in the natural habitat of our country could be natural reservoirs of Leishmania tropica, Leishmania infantum, Leishmania major and Leishmania donovani for cutaneous Leishmaniasis (CL)., The rodents Mus musculus (Balb/C mouse), Mesocricetus auratus (hamster), Meriones unguiculatus (gerbil) and Rattus norvegicus (rat) which are part of the natural habitat in Turkey were used in the study. L.tropica, L.infantum, L.major and L.donovani promastigote isolates obtained from CL patients and cultured in enriched media were injected in the footpads of the animals intradermally using the density of 108 promastigote/ml. The scale of the lesions on the footpads of the animals were measured for 12 weeks. At the end of the experiment, the animals were sacrificed and “touch preparations” were prepared using footpad, liver, spleen and testicles of the sacrified animals and were examined using Giemsa stained slides following culturing in enriched NNN medium. Leishmania amastigotes were seen in the slides prepared from the footpads of the all experimental animals and all cultures were positive for promastigotes prepared from the same clinical material. But not all the experiment groups were positive for the liver, spleen and testicle preparations. According to these results it was concluded that while all rodents in the experiment groups were positive for CL, only a part of the experiment groups were positive for internal organ involvement. Accordingly, (a) All Leishmania strains caused both CL and internal organ involvement in M.unguiculatus and M.musculus, (b) only L.tropica caused CL and internal organ involvement in R.norvegicus, while other Leishmania strains only caused CL in this group, (c) in M.auratus only L.donovani caused CL while other strains caused both CL and internal organ involvement. In our study, it was determined that the rodents Meriones, Mesocricetus, Rattus and Mus genera which are part of our country’s natural habitat could serve as natural reservoirs of L.tropica, L.infantum, L.major and L.donovani, thus having the potential for the spreading of Leishmaniasis in our country and important information were gathered concerning the clinical aspects of the infection caused by Leishmania species in their potential reservoir hosts. © 2018 Ankara Microbiology Society. All rights reserved

Do the rodents have a role in transmission of cutaneous leishmaniasis in Turkey? [Türkiye’de kutanöz leyşmanyaziste kemiricilerin rolü var mı?]

Leishmaniasis is a zoonotic/anthroponotic vector borne parasitic infection which is caused by Leishmania species and transmitted by sand flies (Phlebotomus spp.) The reservoirs of Leishmania species in nature are various wild and domestic carnivores, rodents and human. The aim of this study was to investigate whether the rodents in genera Meriones, Mesocricetus, Rattus and Mus which inhabit in the natural habitat of our country could be natural reservoirs of Leishmania tropica, Leishmania infantum, Leishmania major and Leishmania donovani for cutaneous Leishmaniasis (CL)., The rodents Mus musculus (Balb/C mouse), Mesocricetus auratus (hamster), Meriones unguiculatus (gerbil) and Rattus norvegicus (rat) which are part of the natural habitat in Turkey were used in the study. L.tropica, L.infantum, L.major and L.donovani promastigote isolates obtained from CL patients and cultured in enriched media were injected in the footpads of the animals intradermally using the density of 108 promastigote/ml. The scale of the lesions on the footpads of the animals were measured for 12 weeks. At the end of the experiment, the animals were sacrificed and “touch preparations” were prepared using footpad, liver, spleen and testicles of the sacrified animals and were examined using Giemsa stained slides following culturing in enriched NNN medium. Leishmania amastigotes were seen in the slides prepared from the footpads of the all experimental animals and all cultures were positive for promastigotes prepared from the same clinical material. But not all the experiment groups were positive for the liver, spleen and testicle preparations. According to these results it was concluded that while all rodents in the experiment groups were positive for CL, only a part of the experiment groups were positive for internal organ involvement. Accordingly, (a) All Leishmania strains caused both CL and internal organ involvement in M.unguiculatus and M.musculus, (b) only L.tropica caused CL and internal organ involvement in R.norvegicus, while other Leishmania strains only caused CL in this group, (c) in M.auratus only L.donovani caused CL while other strains caused both CL and internal organ involvement. In our study, it was determined that the rodents Meriones, Mesocricetus, Rattus and Mus genera which are part of our country’s natural habitat could serve as natural reservoirs of L.tropica, L.infantum, L.major and L.donovani, thus having the potential for the spreading of Leishmaniasis in our country and important information were gathered concerning the clinical aspects of the infection caused by Leishmania species in their potential reservoir hosts. © 2018 Ankara Microbiology Society. All rights reserved