Advances in Hyperspectral Image Classification: Earth monitoring with statistical learning methods

Hyperspectral images show similar statistical properties to natural grayscale or color photographic images. However, the classification of hyperspectral images is more challenging because of the very high dimensionality of the pixels and the small number of labeled examples typically available for learning. These peculiarities lead to particular signal processing problems, mainly characterized by indetermination and complex manifolds. The framework of statistical learning has gained popularity in the last decade. New methods have been presented to account for the spatial homogeneity of images, to include user's interaction via active learning, to take advantage of the manifold structure with semisupervised learning, to extract and encode invariances, or to adapt classifiers and image representations to unseen yet similar scenes. This tutuorial reviews the main advances for hyperspectral remote sensing image classification through illustrative examples.Comment: IEEE Signal Processing Magazine, 201

Adaptive Markov random fields for joint unmixing and segmentation of hyperspectral image

Linear spectral unmixing is a challenging problem in hyperspectral imaging that consists of decomposing an observed pixel into a linear combination of pure spectra (or endmembers) with their corresponding proportions (or abundances). Endmember extraction algorithms can be employed for recovering the spectral signatures while abundances are estimated using an inversion step. Recent works have shown that exploiting spatial dependencies between image pixels can improve spectral unmixing. Markov random fields (MRF) are classically used to model these spatial correlations and partition the image into multiple classes with homogeneous abundances. This paper proposes to define the MRF sites using similarity regions. These regions are built using a self-complementary area filter that stems from the morphological theory. This kind of filter divides the original image into flat zones where the underlying pixels have the same spectral values. Once the MRF has been clearly established, a hierarchical Bayesian algorithm is proposed to estimate the abundances, the class labels, the noise variance, and the corresponding hyperparameters. A hybrid Gibbs sampler is constructed to generate samples according to the corresponding posterior distribution of the unknown parameters and hyperparameters. Simulations conducted on synthetic and real AVIRIS data demonstrate the good performance of the algorithm

Extremely Low Birthweight Infants in Iceland. Survival and Disability

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenObjective: In recent years advances in medical care and technology have increased newborn survival rate, both fullterm and preterm. This is reflected in a low Perinatal Mortality Rate in Iceland. Survival of extremely low birthweight infants (ELBW with BW<1000g) has also increased, especially since the availability of surfactant therapy for Respiratory Distress Syndrome of Prematurity. The purpose of this geographically defined national study was to evaluate survival and longterm outcome of ELBW children in Iceland. Material and methods: Information on all births in Iceland 1982-95 was collected from the National Birth Registry and Statistics Iceland with information on ELBW infants weighing 500-999g born in two periods 1982-90 and 1991-95, before and after the use of surfactant became routine therapy. Information on disability was obtained from records at the State Social Security Institute. Comparison was made between the two groups of ELBW infants. Results: In 1982-90 the proportion of ELBW infants was 0.3% of all births (116 of 38.378) and longterm survival at five years of age was 19 of 87 liveborn children or 22%. In 1991-95 ELBW infants were 0.5% of all births (102 of 22.261) and longterm survival was 35 of 67 liveborn children or 52%. Of the 19 ELBW children born in 1982-90 three are considered handicapped (16%) and 6 of 35 ELBW children born in 1991-95 (17%). Conclusions: The study shows that at the same time that proportionally more children are of extreme low birthweight, the survival of ELBW infants has increased from 22% in 1982-90 to 52% in 1991-95. The proportion of ELBW children with disability is not increased significantly between the two periods.Inngangur: Aukin þekking, reynsla og tækniframfarir seinni ára hafa bætt lífsmöguleika veikra nýbura, sem endurspeglast í lágum burðarmálsdauða á Íslandi. Lífslíkur lítilla fyrirbura með fæðingarþyngd <1000 g hafa aukist verulega, einkum eftir að notkun lungnablöðruseytis (surfactants) við glærhimnusjúkdómi (HMD/Hyaline Membrane Disease) varð almenn. Hluti þessara barna glímir við langvinn og alvarleg heilsuvandamál. Tilgangur þessarar rannsóknar var að varpa ljósi á lífslíkur og fötlun lítilla fyrirbura á Íslandi. Efniviður og aðferðir: Upplýsingar um fæðingar á Íslandi á árabilinu 1982-95 fengust úr tölvuvæddri Fæðingarskráningu Ríkisspítala, nú Landspítala. Einnig var aflað upplýsinga hjá Hagstofu Íslands um litla fyrirbura sem vógu 500-999 g og fæddust á tveimur tímabilum 1982-90 og 1991-95, fyrir og eftir að notkun lungnablöðruseytis varð almenn. Upplýsingar um fötlunargreiningar fengust í gagnagrunni Tryggingastofnunar ríkisins. Við úrvinnslu var gerður samanburður á fyrirburahópunum. Niðurstöður: Á árunum 1982-90 var hlutfall lítilla fyrirbura 0,3% af öllum fæðingum (116 af 38.378) og lifðu 19 af 87 lifandi fæddum börnum við fimm ára aldur, eða 22%. Á seinna tímabilinu 1991-95 var hlutfall lítilla fyrirbura 0,5% af öllum fæðingum (102 af 22.261) og lifðu 35 af 67 lifandi fæddum börnum við fimm ára aldur, eða 52%. Af fyrirburum áranna 1982-90 eru þrjú (16%) af 19 börnum talin fötluð og 6 (17%) af 35 fyrirburum áranna 1991-95. Ályktanir: Rannsóknin sýnir að á sama tíma og hlutfallslega fleiri litlir fyrirburar fæðast í hverjum árgangi hafa lífslíkur þeirra aukist úr 22% á árunum 1982-90 í 52% 1991-95. Hlutfall lítilla fyrirbura með fötlunargreiningar hefur ekki aukist marktækt milli tímabila þrátt fyrir aukna lifun

Fjármögnun Háskóla Íslands

Efst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkin

Feature Selection Based on Hybridization of Genetic Algorithm and Particle Swarm Optimization

A new feature selection approach that is based on the integration of a genetic algorithm and particle swarm optimization is proposed. The overall accuracy of a support vector machine classifier on validation samples is used as a fitness value. The new approach is carried out on the well-known Indian Pines hyperspectral data set. Results confirm that the new approach is able to automatically select the most informative features in terms of classification accuracy within an acceptable CPU processing time without requiring the number of desired features to be set a priori by users. Furthermore, the usefulness of the proposed method is also tested for road detection. Results confirm that the proposed method is capable of discriminating between road and background pixels and performs better than the other approaches used for comparison in terms of performance metrics.Rannís; Rannsóknarnámssjóður / The Icelandic Research Fund for Graduate Students.PostPrin

Neonatal life support

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenAlthough most newborn infants are vigorous at birth, some need to be resuscitated. Therefore, at least one person skilled in neonatal resuscitation should be present at every delivery and appropriate equipments for resuscitation should be available. Most infants who reqiure resuscitation only need respiratory support. Chest compressions and administration of medications are infrequently needed. This article provides guidelines on neonatal resuscitation, which are mainly based on recently published International Liasion Committee on Resuscitation (ILCOR) guidelines.Flest börn fæðast í þennan heim í góðu ástandi, en í 5-10% tilvika þarf nýburinn á aðstoð að halda fyrst eftir fæðinguna (1). Yfirleitt nægir þá að örva barnið eða veita því öndunaraðstoð í stuttan tíma. Mjög sjaldan þarf að grípa til hjartahnoðs og enn sjaldnar að gefa lyf, en í þeim tilvikum er oft tvísýnt um horfur barnsins ef endurlífgun tekst þá á annað borð (2). Gott mæðraeftirlit og góð fæðingarhjálp er hornsteinn að velferð nýburans, en jafnvel þó vel sé að því staðið verður alltaf að gera ráð fyrir að nýfætt barn geti þurft á hjálp að halda á fyrstu mínútum lífsins. Hér eru gefnar leiðbeiningar um endurlífgun nýbura. Eiga þær fyrst og fremst við um endurlífgun fyrst eftir fæðinguna, en jafnframt um endurlífgun á börnum upp að eins mánaða aldri. Byggjast þær einkum á ráðleggingum sem gefnar hafa verið út á vegum International Liaison Committee on Resuscitation (ILCOR) og voru nýlega endurskoðaðar (3-6)