Probabilistic approach to cloud and snow detection on Advanced Very High Resolution Radiometer (AVHRR) imagery

Derivation of probability estimates complementary to geophysical data sets has gained special attention over the last years. Information about a confidence level of provided physical quantities is required to construct an error budget of higher-level products and to correctly interpret final results of a particular analysis. Regarding the generation of products based on satellite data a common input consists of a cloud mask which allows discrimination between surface and cloud signals. Further the surface information is divided between snow and snow-free components. At any step of this discrimination process a misclassification in a cloud/snow mask propagates to higher-level products and may alter their usability. Within this scope a novel probabilistic cloud mask (PCM) algorithm suited for the 1 km × 1 km Advanced Very High Resolution Radiometer (AVHRR) data is proposed which provides three types of probability estimates between: cloudy/clear-sky, cloudy/snow and clear-sky/snow conditions. As opposed to the majority of available techniques which are usually based on the decision-tree approach in the PCM algorithm all spectral, angular and ancillary information is used in a single step to retrieve probability estimates from the precomputed look-up tables (LUTs). Moreover, the issue of derivation of a single threshold value for a spectral test was overcome by the concept of multidimensional information space which is divided into small bins by an extensive set of intervals. The discrimination between snow and ice clouds and detection of broken, thin clouds was enhanced by means of the invariant coordinate system (ICS) transformation. The study area covers a wide range of environmental conditions spanning from Iceland through central Europe to northern parts of Africa which exhibit diverse difficulties for cloud/snow masking algorithms. The retrieved PCM cloud classification was compared to the Polar Platform System (PPS) version 2012 and Moderate Resolution Imaging Spectroradiometer (MODIS) collection 6 cloud masks, SYNOP (surface synoptic observations) weather reports, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) vertical feature mask version 3 and to MODIS collection 5 snow mask. The outcomes of conducted analyses proved fine detection skills of the PCM method with results comparable to or better than the reference PPS algorithm.

Daytime Low Stratiform Cloud Detection on AVHRR Imagery

The near-real time retrieval of low stratiform cloud (LSC) coverage is of vital interest for such disciplines as meteorology, transport safety, economy and air quality. Within this scope, a novel methodology is proposed which provides the LSC occurrence probability estimates for a satellite scene. The algorithm is suited for the 1 × 1 km Advanced Very High Resolution Radiometer (AVHRR) data and was trained and validated against collocated SYNOP observations. Utilisation of these two combined data sources requires a formulation of constraints in order to discriminate cases where the LSC is overlaid by higher clouds. The LSC classification process is based on six features which are first converted to the integer form by step functions and combined by means of bitwise operations. Consequently, a set of values reflecting a unique combination of those features is derived which is further employed to extract the LSC occurrence probability estimates from the precomputed look-up vectors (LUV). Although the validation analyses confirmed good performance of the algorithm, some inevitable misclassification with other optically thick clouds were reported. Moreover, the comparison against Polar Platform System (PPS) cloud-type product revealed superior classification accuracy. From the temporal perspective, the acquired results reported a presence of diurnal and annual LSC probability cycles over Europe.

To look or not to look at threat? Scanpath differences within a group of spider phobics

Predicting the behavior of phobic patients in a confrontational situation is challenging. While avoidance as a major clinical component of phobias suggests that patients orient away from threat, findings based on cognitive paradigms indicate an attentional bias towards threat. Here we present eye movement data from 21 spider phobics and 21 control subjects, based on 3 basic oculomotor tasks and a visual exploration task that included close-up views of spiders. Relative to the control group, patients showed accelerated reflexive saccades in one of the basic oculomotor tasks, while the fear-relevant exploration task evoked a general slowing in their scanning behavior and pronounced oculomotor avoidance. However, this avoidance strongly varied within the patient group and was not associated with the scores from spider avoidance-sensitive questionnaire scales. We suggest that variation of oculomotor avoidance between phobics reflects different strategies of how they cope with threat in confrontational situations.

Spindle cell oncocytoma of the adenohypophysis: report of a case with a 16-year follow-up

Spindle cell oncocytoma (SCO) is a recently described, rare neoplasm of the anterior pituitary. Clinically and radiologically simulating a non-functioning macroadenoma, its eponymous fusiform cells display a non-epithelial phenotype with conspicuous cytoplasmic accumulation of mitochondria. We report a case of SCO retrospectively identified in a biopsy specimen 16 years after transsphenoidal operation of a 48-year-old woman. Presenting symptoms were adynamia and transient decrease of visual acuity. Neuroimaging showed an isointense, enhancing, sellar-centered mass 1.8 cm in diameter without evidence of invasive growth. No postoperative adjuvant therapy was administered. The patient was left with panhypopituitarism, yet no recurrence was seen during follow-up. Initially diagnosed as a null cell adenoma of oncocytic type, repeat immunohistochemistry showed the characteristic coexpression of S100 protein, vimentin, and epithelial membrane antigen. Oncocytic granula stained intensely with antimitochondrial antibody 113-1, and were negative with the lysosomal marker CD68. Anterior pituitary hormones tested negative, and there was no evidence of neuroendocrine differentiation using antibodies to synaptophysin and chromogranin. Few cells stained for glial fibrillary acidic protein (GFAP). SCO has been proposed to represent a neoplasm of folliculo-stellate cells (FSCs). While the dynamic properties of the latter are incompletely characterized, and indeed no specific marker allows for their identification, overlapping features of SCO with look alikes, in particular pituicytoma, point to FSCs being a potential adult stem cell. The favorable outcome of the present case further argues for SCO to be considered a low-grade neoplasm. Moderate tumor size, lack of invasiveness, and low proliferation rate are likely predictors of benign behavior.

The World Trade Organization’s Legitimacy Crisis: What Does The Beast Look Like?

The concept of legitimacy has many facets. The article reviews from a politics and law perspective the diagnosis of an ``institution in crisis''. This article is divided into three sections. It starts with a cautionary note on existing fallacies about assessing multilateral intergovernmental institutions and discusses competing schools of thought that approach the World Trade Organization (WTO) with varying perceptions of democracy and legitimacy. Section II takes up the actual debate on redesigning the WTO and directs attention to the question of balancing input and output legitimacy. Section III sketches potential avenues of research that have been neglected in the past.

“But look: we have sat here too long”: Hilary Mantel’s tightrope walk of present-tense usage

Even after Hilary Mantel has won the Man Booker prize two times in a row with Wolf Hall and Bring up the Bodies, her novelistic account of the life of Thomas Cromwell, her intriguing decision to write these historical novels in the present tense gave cause to surprisingly little extended comment beyond a perfunctory nod to its evocation of immediacy. This presents not only a lacunae in the discussion about Mantel’s novels, but is also symptomatic for a change in the contemporary critical evaluation of present-tense narration in general. If present-tense narration once used to be a marker for experimental daring and might even have implied a certain hostility towards fictionality, Mantel’s novels give ample evidence that literary sensibilities have changed. In order to understand the scope and nature of this change, my paper puts Mantel’s use of the present tense in the context of both the historical development of present-tense usage and the ample contemporary landscape of present-tense narration. This allows me to show that the complexities of present-tense usage belie a reduction of its effect to an evocation of immediacy. Rather, I argue, Mantel uses it for a delicate tightrope walk between proximity and distance, history and fiction, authenticity and imagination.

From regression estimates to document tables: output formatting using -estout-

Postestimation processing and formatting of regression estimates for input into document tables are tasks that many of us have to do. However, processing results by hand can be laborious, and is vulnerable to error. There are therefore many benefits to automation of these tasks while at the same time retaining user flexibility in terms of output format. The estout package meets these needs. estout assembles a table of coefficients, "significance stars", summary statistics, standard errors, t/z statistics, p-values, confidence intervals, and other statistics calculated for up to twenty models previously fitted and stored by estimates store. It then writes the table to the Stata log and/or to a text file. The estimates are formatted optionally in several styles: html, LaTeX, or tab-delimited (for input into MS Excel or Word). There are a large number of options regarding which output is formatted and how. This talk will take users through a range of examples, from relatively basic simple applications to complex ones.