Sleep and breathing disorders in patients with brain stem lesions

Most information about the structures within the brain stem that modulate respiration and sleep are gathered from animal experiments. Therefore we examined 10 patients several weeks after an infarction of the brain stem by means of polysomnography and tested the chemosensitive drives of respiration. None of these patients complained about symptoms of sleep disordered breathing. In each case polysomnographic measurements and ventilatory response curves revealed pathologic findings. The respiratory response to CO2 was diminished or completely abolished in each patient. In some cases hypoventilation or disturbances of the respiratory rhythmicity could be seen. In several cases missing REM sleep, sleep fragmentation or the reduction of slow wave sleep were observed. The study indicates that on the base of results from animal research the comparison of morphological and pathophysiological data is helpful to gain a better understanding on the coupling of the respiratory system with sleep at the brain stem level as well as on the pathomechanism of sleep related breathing disorder.     

Reducing the window of opportunity for Android malware Gotta catch ’em all

Spotting malicious samples in the wild has always been difficult, and Android malware is no exception. Actually, the fact Android applications are (usually) not directly accessible from market places hardens the task even more. For instance, Google enforces its own communication protocol to browse and download applications from its market. Thus, an efficient market crawler must reverse and implement this protocol, issue appropriate search requests and take necessary steps so as not to be banned. From end-users?? side, having difficulties spotting malicious mobile applications results in most Android malware remaining unnoticed up to 3?months before a security researcher finally stumbles on it. To reduce this window of opportunity, this paper presents a heuristics engine that statically pre-processes and prioritizes samples. The engine uses 39 different flags of different nature such as Java API calls, presence of embedded executables, code size, URLs?? Each flag is assigned a different weight, based on statistics we computed from the techniques mobile malware authors most commonly use in their code. The engine outputs a risk score which highlights samples which are the most likely to be malicious. The engine has been tested over a set of clean applications and malicious ones. The results show a strong difference in the average risk score for both sets and in its distribution, proving its use to spot malware.     

Customer entrepreneurship on digital platforms: Challenges and solutions for platform business models

Drawing on the mixed methods of qualitative research and agent‐based simulation, this study examines: (a) how end‐users use digital platforms to become customer–entrepreneurs undertaking commercial activities on platforms; and (b) how platform providers can convert this customer entrepreneurship into a revenue stream. Considering that end‐users have traditionally been defined as passive and uncharged actors in platform business models, an in‐depth understanding of their commercial activities and the viable revenue model to monetize this emerging customer practice is warranted. Our qualitative study reveals that customer–entrepreneurs make substantial use of platform offerings to advertise their products; communicate with end‐consumers; and accept payments. These commercial activities are largely exercised for free on platforms, even though they could otherwise serve as a source of revenue. On this point, our simulation results identify two pricing models achieving the generation of nearly identical revenues over time. First, platform providers may charge both advertising and transaction fees, which maximize the survival of professional customer–entrepreneurs. Second, platform businesses may levy advertising fees only, which maximizes the survival of informal customer–entrepreneurs operating on a micro‐scale and part‐time basis. This study offers theoretical, methodological, and managerial implications for platform studies.     

Fast full‐color reflective display via photoluminescent enhancement

Reflective displays are advantageous in applications requiring low power or daylight readability. However, there are no low‐cost reflective technologies capable of displaying bright colors. By employing photoluminescence to more efficiently use ambient light, we created a prototype display that provides bright, full color in a simple, low‐cost architecture. This prototype includes a novel electrokinetic shutter, a layer that incorporates patterned luminescent red, green, and blue sub‐pixel elements, and a novel optical out‐coupling scheme. The luminescent elements convert otherwise‐wasted portions of the incident spectrum to light in the desired color band, resulting in improved color saturation and lightness. This prototype provides a color gamut that is superior to competing reflective display technologies that utilize color filters in single‐layer side‐by‐side sub‐pixel architectures. The current prototype is capable of switching in <0.5 s; future displays based on an alternative electro‐optic shutter technology should achieve video rate operation. A transflective version of this technology has also been prototyped. The transflective version utilizes its backlight with a power efficiency that is at least three times that of a conventional liquid crystal display. These photoluminescence‐based technologies enable a host of applications ranging from low‐power mobile products and retail pricing signage to daylight readable signage for outdoor advertising segments.     

A neuron membrane mesh representation for visualization of electrophysiological simulations

We present a process to automatically generate three-dimensional mesh representations of the complex, arborized cell membrane surface of cortical neurons (the principal information processing cells of the brain) from nonuniform morphological measurements. Starting from manually sampled morphological points (3D points and diameters) from neurons in a brain slice preparation, we construct a polygonal mesh representation that realistically represents the continuous membrane surface, closely matching the original experimental data. A mapping between the original morphological points and the newly generated mesh enables simulations of electrophysiolgical activity to be visualized on this new membrane representation. We compare the new mesh representation with the state of the art and present a series of use cases and applications of this technique to visualize simulations of single neurons and networks of multiple neurons.     

The next-generation business meeting: from i-lands to flexible meeting landscapes

Meetings are an important form of interaction in business settings. However, meetings are often not held in a way that makes all participants feel engaged. Meeting support systems try to overcome this obstacle by helping meeting participants in the meeting workflow. This paper takes a complementary approach by distinguishing between different perspectives of good meetings: the peopleware perspective, the generic groupware perspective, and the roomware perspective. It is argued that all these perspectives have to be considered simultaneously when heading toward an ideal meeting system design. The paper presents excerpts of a pattern language that empowers users to improve their meeting. Besides this, the pattern language can be considered as a tool for the designer. After showing, how both groups made use of the patterns, the paper finally presents LivingAgendas, a meeting support system that can accompany the meeting participant through the meeting life cycle.     

Ionic conductivity of synthetic analcime,sodalite and offretite

The ionic conductivity of pressed pellets of dehydrated synthetic analcime, sodalite and offretite was determined by a.c. measurements within the range 10 Hz to 10 MHz. The ionic conductivity values of those zeolites exchanged with various monovalent cations were determined by the complex impedance plane method. The conduction activation energies range between 63 and 101 kJ mol^–1. Sodium analcime shows the best ionic conductivity, namely 1.8×10^–4–1 cm^–1 at 400° C. A comparison with the conductivity of other ion-conducting solids was made.     

Bewertung von Ausfallvarianten für die Netzsicherheitsanalyse

Übersicht Für die On-line-Netzsicherheitsüberwachung wird eine adaptive Güteindex-Prozedur zur dynamischen Erstellung von Ausfallisten vorgestellt. Mit den bisher bekannten Güteindex-Verfahren konnten aufgrund des Verdeckungseffektes meist nicht alle tatsächlich kritischen Varianten als solche erkannt und deklariert werden. In der neuen Prozedur werden die Ergebnisse der Ausfallsimulationsrechnung der unmittelbaren Systemvergangenheit für die Erstellung der aktuellen Ausfalliste verwendet. Mit einer linearen Korrekturfunktion werden dabei die verdeckungseffektbehaftetenG ₂-Werte des Standard-Güteindex-Verfahrens in verbesserte Werte transformiert.

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Contingency assessment for power system security analysis

Contents An adaptive procedure for dynamic contingency selection in the on-line security assessment is proposed. Because of the masking effect in conventional performance index algorithms a possibly large number of critical contingencies is misclassified. In the new procedure results of former security checks are used for evaluating the current contingency list. A linear corrective function is applied to transform the standard second orderG-values into improved values.

     

A Further Comparison of Splitting Rules for Decision-Tree Induction

One approach to learning classification rules from examples is to build decision trees. A review and comparison paper by Mingers (Mingers, 1989) looked at the first stage of tree building, which uses a splitting rule to grow trees with a greedy recursive partitioning algorithm. That paper considered a number of different measures and experimentally examined their behavior on four domains. The main conclusion was that a random splitting rule does not significantly decrease classificational accuracy. This note suggests an alternative experimental method and presents additional results on further domains. Our results indicate that random splitting leads to increased error. These results are at variance with those presented by Mingers.     

Crystallization of Fe-Si-B metallic glasses studied by X-ray synchrotron radiation

We have studied the crystallization kinetics of Fe_90-x Si _x B₁₀ amorphous alloys withx ranging from 7 to 21, by synchrotron X-ray radiation. Using energy- dispersive X-ray diffraction, the kinetics of the different crystalline phases evolving during isothermal annealing were followed. These crystalline phases were identified as precipitation of-Fe(Si) and/or Fe₃Si in the amorphous matrix. At a later time or at a higher temperature, Fe₂B starts to crystallize (x < 21 ). Only at low iron concentration (x = 21) was the second phase different, namely Fe₅SiB₂ The hypo- and hyper-eutectic Fe-Si-B glasses were found to crystallize differently. The crystallization processes are discussed in some detail.