A uniform controllability result for the Keller-Segel system

In this paper we study the controllability of the Keller-Segel system approximating its parabolic-elliptic version. We show that this parabolic system is locally uniform controllable around a constant solution of the parabolic-elliptic system when the control is acting on the component of the chemical

Pseudogap and the specific heat of high TcT_c superconductors

The specific heat of a two dimensional repulsive Hubbard model with local interaction is investigated. We use the two-pole approximation which exhibits explicitly important correlations that are sources of the pseudogap anomaly. The interplay between the specific heat and the pseudogap is the main focus of the present work. Our self consistent numerical results show that above the occupation $n_T\approx 0.85$, the specific heat starts to decrease due to the presence of a pseudogap in the density of states. We have also observed a two peak structure in the specific heat. Such structure is robust with respect to the Coulomb interaction $U$ but it is significantly affected by the occupation $n_T$. A detailed study of the two peak structure is carried out in terms of the renormalized quasi-particle bands. The role of the second nearest neighbor hopping on the specific heat behavior and on the pseudogap, is extensively discussed.Comment: 6 pages, 6 figures, accepted for publication in Solid State Communication

Precision Assessment of the HPLC Phytoplankton Pigment Dataset Analyzed by NASA to Quantify Global Variability in Support of Ocean Color Remote Sensing

The ability to generate chlorophyll a (Chl a) assessments from ocean color orbital sensors, such as VIIRS and MODIS, that satisfy the requirements to be climate-quality data record (CDR) quality is contingent in part on the quality of the in situ ground or sea truth observations that serve as datasets for vicarious calibration and algorithm validation activities. NASA has a mandate to collect, analyze, and distribute in situ data of the highest possible quality with documented uncertainties and in keeping with established performance metrics. Using a dataset of over 18,000 HPLC phytoplankton pigment samples representing water collected in all major ocean basins analyzed a central laboratory (Field Support Group (FSG) of the Ocean Ecology Laboratory (OEL) at NASA Goddard Space Flight Center (GSFC)), we performed an assessment of the global precision among sample replicates of Chl a as well as major accessory pigments. We investigated the impacts of filtration volume, water basin, collection technique, pigment concentration, and different filtration volumes for replicate filters on replicate filter precision, as well as investigating any pigment-specific differences. Our results quantify sample variability with the goal of understanding any systemic biases or biogeographic influences

An entropic approach to local realism and noncontextuality

For any Bell locality scenario (or Kochen-Specker noncontextuality scenario), the joint Shannon entropies of local (or noncontextual) models define a convex cone for which the non-trivial facets are tight entropic Bell (or contextuality) inequalities. In this paper we explore this entropic approach and derive tight entropic inequalities for various scenarios. One advantage of entropic inequalities is that they easily adapt to situations like bilocality scenarios, which have additional independence requirements that are non-linear on the level of probabilities, but linear on the level of entropies. Another advantage is that, despite the nonlinearity, taking detection inefficiencies into account turns out to be very simple. When joint measurements are conducted by a single detector only, the detector efficiency for witnessing quantum contextuality can be arbitrarily low.Comment: 12 pages, 8 figures, minor mistakes correcte

Assessing The Influence Of Assistive Technology On People With Spinal Cord Injury Using A Measure Of Participation

The occurrence of a spinal cord injury (SCI) leads to an enormous change in an individual�s lifestyle. Limitation related to mobility can become critical affecting ability to participate in nearly all activities of daily living (ADL). People with SCI rely on assistive technology (AT), especially wheelchair to facilitate the return to as many pre-injury activities as possible and serve as a resource tool for community living and participation12. The purpose of this study was to investigate the wheelchair and related factors that affect the participation of individuals with SCI in activities performed in three settings including home, community and transportation. Seventy individuals with SCI who use wheelchairs for mobility participated in this study. A written survey, which recorded AT usage in daily activities, was distributed among individuals from Pittsburgh (Pitt) and Saint Louis (SL). The wheelchair was found to be the most limiting factor in activities performed in the home, community and transportation use. The second most limiting factor was physical impairment and environment. Significant differences were shown among individuals from Pitt and SL. A higher number of individuals from SL indicated pain, fatigue, wheelchair seating, social attitudes and self-concept as factors that limit their participation. In addition, significant differences were revealed in transportation use between individuals with paraplegia and tetraplegia. Pain was shown as a limiting factor for people with paraplegia, whereas, lack of equipment was indicated by people with tetraplegia.AT and related factors impact participation of individuals with SCI. The wheelchair was the most common limiting factor, followed by physical impairment and physical environment. The wheelchair is most likely their most important mobility device while also the one that is most associated with barriers