simpcomp -- A GAP toolbox for simplicial complexes

simpcomp is an extension (a so called package) to GAP, the well known system for computational discrete algebra. The package enables the user to compute numerous properties of (abstract) simplicial complexes, provides functions to construct new complexes from existing ones and an extensive library of triangulations of manifolds.Comment: 4 page

A High-Level Programming Language for Modelling the Earth

Computational models based on the solution of partial differential equations (PDEs) play a key role in Earth systems simulations. The software implementing these models depends on the discretisation method, data structures and the computer architecture. For this reason, it is difficult for scientists to implement new models without strong software engineering skills. In this paper, we present a computational modeling language (escript) based on the object-oriented scripting language (Python). This language, is designed to implement PDE-based models with a high degree of abstraction from the underlying discretization techniques and their implementation. The main components of escript are the Data class objects which handle data with a spatial distribution and the linearPDE class which define linear PDEs to be solved in each step of a time integration or non-linear iteration scheme. As an example we will discuss the solution of the Lame equation and the implementation of a quasi-static model for crustal fault systems

Yield losses in vegetable and arable crops caused by yellow nutsedge (Cyperus esculentus) in farmers fields in Switzerland

Cyperus esculentus ist zu einem Problemunkraut in der Schweiz geworden. Trotz Sensibilisierungsanstrengungen werden die drohenden Ertragsverluste von noch nicht betroffenen Landwirten oft unterschätzt. Dementsprechend wird den Auswirkungen eines Erdmandelgrasbefalls zu wenig Beachtung geschenkt und Eindämmungs- und Bekämpfungsmaßnahmen werden oft nur zögerlich ergriffen.Ertragsverlustzahlen aus dem Ausland sind breit verfügbar. Diese Zahlen erwiesen sich aber nur als bedingt hilfreich, um Schweizer Landwirte zu sensibilisieren. Die Übertragbarkeit auf Schweizer Anbausysteme wurde bezweifelt. Um diese Datenlücke zu schließen, wurden entsprechende Ertragsdaten für verschiedene Kulturen auf Schweizer Praxisflächen erhoben (2013-2016). Erträge mit und ohne Besatz von C. esculentus wurden erhoben und dessen Deckungsgrad geschätzt. Auf den Flächen war eine praxisübliche, chemische Unkrautbekämpfung erfolgt. Für Zuckerrüben und Kartoffeln betrugen die Ertragsverluste durchschnittlich 67 % und 34 %, bei einer Cyperus-Bedeckung von 68 % respektive 44 %. Bei einem hohen Besatz (80-100 % Deckungsgrad) betrugen die Ertragsverluste in Lauch, Zwiebeln und Rosenkohl 86 %, 90 % and 93 %. In Karotten führte ein starker Befall zu einer Ertragsreduktion von 61 %. Bei so hohen Dichten war auch die Qualität des Ernteguts beeinträchtigt.Die Ergebnisse sollen dazu dienen, Schweizer Landwirte weiter zu sensibilisieren. Die Ergebnisse werden zudem Forschungsinstituten bzw. landwirtschaftlichen Beratungsinstitutionen in anderen Ländern zur Verfügung gestellt, die mit der gleichen Problematik konfrontiert sind.Cyperus esculentus has become a serious weed in Switzerland. Despite intensive awareness training unaffected farmers tend to underestimate the consequences of C. esculentus infestation, especially the potential yield losses. Hence, countermeasures are often taken hesitantly.Yield loss data from abroad is widely available. However, this data was of limited value to raise awareness in Switzerland, because its transferability to our production systems was questioned. To close this gap yield losses caused by C. esculentus were determined for different crops in farmers’ fields in Switzerland (2013-2016). Yield was assessed with and without C. esculentus infestation and its coverage was estimated. Standard herbicides had been applied in the fields. For sugar beet and potatoes average, actual yield losses of 67% and 34% were detected at C. esculentus coverages of 68% and 44%, respectively. High infestation (80-100%) in leek, onions and Brussels sprouts caused losses of 86%, 90%, 93%, accordingly. In carrots: A high infestation led to 61% yield loss. At these infestation levels yield quality was also negatively affected.In Switzerland, these figures are employed to further train farmers. The findings are presented here to make this more recent yield loss data available to colleagues facing the same problem in their countries

The Decoupled Mind : Mind-wandering Disrupts Cortical Phase-locking to Perceptual Events

The mind flows in a "stream of consciousness," which often neglects immediate sensory input in favor of focusing on intrinsic, self-generated thoughts or images. Although considerable research has documented the disruptive influences of task-unrelated thought for perceptual processing and task performance, the brain dynamics associated with these phenomena are not well understood. Here we investigate the possibility, suggested by several convergent lines of research, that task-unrelated thought is associated with a reduction in the trial-to-trial phase consistency of the oscillatory neural signal in response to perceptual input. Using an experience sampling paradigm coupled with continuous high-density electroencephalography, we observed that task-unrelated thought was associated with a reduction of the P1 ERP, replicating prior observations that mind-wandering is accompanied by a reduction of the brain-evoked response to sensory input. Time-frequency analysis of the oscillatory neural response revealed a decrease in theta-band cortical phase-locking, which peaked over parietal scalp regions. Furthermore, we observed that task-unrelated thought impacted the oscillatory mode of the brain during the initiation of a task-relevant action, such that more cortical processing was required to meet task demands. Together, these findings document that the attenuation of perceptual processing that occurs during task-unrelated thought is associated with a reduction in the temporal fidelity with which the brain responds to a stimulus and suggest that increased neural processing may be required to recouple attention to a task. More generally, these data provide novel confirmatory evidence for the mechanisms through which attentional states facilitate the neural processing of sensory input

Beyond the Scope: Using Motion Capture Data from Bronchoscopy Simulations to Build Feedback Models

Mannequin simulators and task trainers are commonly used in health sciences training programs to teach techniques performed during medical procedures. However, there are drawbacks to their deployment. First and foremost, the cost of high-fidelity task trainers is prohibitively expensive for many programs. Additionally, the combination of mannequin-to-learner and teacher-to-learner ratios often makes it difficult to efficiently teach procedures to a large number of students. This project aims to create a low-cost, game-based, easily portable task trainer to assist learners in building skills and expertise in performing bronchoscopies. This preliminary report focuses on designing a motion capture device to record hand, wrist, and thumb motions performed by experts and learners during simulated bronchoscopy procedures and then using this captured data to construct computational feedback models

Perfluoroalkyl acids (PFAAs) in children’s serum and contribution from PFAA-contaminated drinking water

We investigated associations between serum perfluoroalkyl acid (PFAA) concentrations in children aged 4, 8, and 12 years (sampled in 2008–2015; n = 57, 55, and 119, respectively) and exposure via placental transfer, breastfeeding, and ingestion of PFAA-contaminated drinking water. Sampling took place in Uppsala County, Sweden, where the drinking water has been historically contaminated with perfluorobutanesulfonate (PFBS), perfluorohexanesulfonate (PFHxS), perfluorooctanesulfonate (PFOS), perfluoroheptanoate (PFHpA), and perfluorooctanoate (PFOA). PFOS showed the highest median concentrations in serum (3.8–5.3 ng g–1 serum), followed by PFHxS (1.6–5.0 ng g–1 serum), PFOA (2.0–2.5 ng g–1 serum), and perfluorononanoate (PFNA) (0.59–0.69 ng g–1 serum) in children. Including all children, serum PFOA, PFHxS, and PFOS concentrations in children increased 10, 10, and 1.3% (adjusted mean), respectively, per unit (ng g–1 serum) of increase in the maternal serum level (at delivery), the associations being strongest for 4 year-old children. PFHxS and PFOS significantly increased 3.9 and 3.8%, respectively, per month of nursing, with the highest increase for 4 year-olds. PFOA, PFBS, PFHxS, and PFOS increased 1.2, 207, 7.4, and 0.93%, respectively, per month of cumulative drinking water exposure. Early life exposure to PFOA, PFHxS, and PFOS is an important determinant of serum concentrations in children, with the strongest influence on younger ages. Drinking water with low to moderate PFBS, PFHxS, PFOS, and PFOA contamination is an important source of exposure for children with background exposure from other sources

Contact structures on M × S2 {Mathematical expression}

We show that if a manifold {Mathematical expression} admits a contact structure, then so does {Mathematical expression}. Our proof relies on surgery theory, a theorem of Eliashberg on contact surgery and a theorem of Bourgeois showing that if {Mathematical expression} admits a contact structure then so does {Mathematical expression}. © 2013 Springer-Verlag Berlin Heidelberg