Homological stability for spaces of commuting elements in Lie groups

In this paper we study homological stability for spaces ${\rm Hom}(\mathbb{Z}^n,G)$ of pairwise commuting $n$-tuples in a Lie group $G$. We prove that for each $n\geqslant 1$, these spaces satisfy rational homological stability as $G$ ranges through any of the classical sequences of compact, connected Lie groups, or their complexifications. We prove similar results for rational equivariant homology, for character varieties, and for the infinite-dimensional analogues of these spaces, ${\rm Comm}(G)$ and ${\rm B_{com}} G$, introduced by Cohen-Stafa and Adem-Cohen-Torres-Giese respectively. In addition, we show that the rational homology of the space of unordered commuting $n$-tuples in a fixed group $G$ stabilizes as $n$ increases. Our proofs use the theory of representation stability - in particular, the theory of ${\rm FI}_W$-modules developed by Church-Ellenberg-Farb and Wilson. In all of the these results, we obtain specific bounds on the stable range, and we show that the homology isomorphisms are induced by maps of spaces.Comment: 56 pages, accepted versio

Hilbert-Poincare series for spaces of commuting elements in Lie groups

In this article we study the homology of spaces ${\rm Hom}(\mathbb{Z}^n,G)$ of ordered pairwise commuting $n$-tuples in a Lie group $G$. We give an explicit formula for the Poincare series of these spaces in terms of invariants of the Weyl group of $G$. By work of Bergeron and Silberman, our results also apply to ${\rm Hom}(F_n/\Gamma_n^m,G)$, where the subgroups $\Gamma_n^m$ are the terms in the descending central series of the free group $F_n$. Finally, we show that there is a stable equivalence between the space ${\rm Comm}(G)$ studied by Cohen-Stafa and its nilpotent analogues.Comment: 20 pages, journal versio

Quantifying Diachronic Variability: The 'Ain Difla rockshelter (Jordan) and the Evolution of Levantine Mousterian Technology

Condette Jean-François. RAYNAL Pierre, voir CHAUDRU de RAYNAL Pierre. In: , . Les recteurs d'académie en France de 1808 à 1940. Tome II, Dictionnaire biographique. Paris : Institut national de recherche pédagogique, 2006. p. 327. (Histoire biographique de l'enseignement, 12

Telomere Estimates by qPCR in American Kestrel Birds

Telomeres are highly conserved repeated sequences found at the ends of linear chromosomes. Measuring telomere length has been used to estimate the ages of individuals in several species. The research presented here focuses on developing telomere length estimates in the American Kestrel (Falco sparverius), using Quantitative Polymerase Chain Reaction (qPCR). The verification of a primer pair that can amplify a reference gene and serve to normalize the telomere qPCR data is vitally important. The gene for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was preferably chosen because it occurs in a single copy in most birds. However, the Kestrel genome has not been sequenced making primer design challenging. We used a bioinformatics approach to find regions of the GAPDH gene that are conserved between chicken and several species of raptors. We also checked several published GAPDH primers reported in the literature. Here, we report the sequence and efficiency of qPCR primers that can be used for telomere length studies in the American Kestral

Radio Frequency Tag Satellite: Backscatter Communication in Low Earth Orbit

Wireless sensor communication can evaluate the structural integrity of a system while reducing the danger and cost of installation and maintenance on satellites. This is needed at the International Space Station as well as other satellites. The objective of this mission is to perform a demonstration using backscatter Radio Frequency Identification (RFID) Tag technology as a method of wireless communication in extremely low earth orbit. While RFID tag communication has been used on earth for many practical applications the technology has yet to be tested in space. A 3U Cubesat was selected as the configuration to house the experiment. This project utilizes an electrical power system, an interface board custom built around a microcontroller, and two radio communication systems to run the RFID experiment to be designed by a Georgia Tech engineering team. The RFID tag will be mounted to a carbon fiber boom that can be extended out one meter to incrementally collect data. This satellite will need to be strong enough to pass a series of vibration and heat tests to be qualified for flight. It will be programmed to maintain its own power, take data, and communicate the data back to earth via the Globalstar Network

How Pure is Pure? Metal Complexation Studies Directed Towards Pharmaceutical Drug Purification

Catalytic processes play critical roles in the modern-day industrial syntheses of many commonplace materials such as plastics, fuel production, electronics, and pharmaceuticals. Transition metal catalysts may become homogeneously embedded within solid nanomaterials during their synthetic scheme, which can result in deleterious effects on both the construction and durability of the material as well as its intended functionality. Traditional purification methods of these materials rely upon harsh reaction conditions that may either affect or allow for specific functionalities. Arylazothioformamide (ATF) ligands have proven to be a mild alternative for their ability to chelate these solid transition metal catalysts. This work will describe the synthetic steps towards developing a versatile library of ATF ligands, the characterization of those already synthesized, and initial chelation studies directed towards the purification of pharmaceutical drugs which employ catalytic processes in their production

Development of a Meteorologically Instrumented Small Transition Unmanned Aerial System For Urban Boundary Layer Investigations

It is estimated that more than 55% of the world’s population is currently living in urban areas and this number is expected to grow to 70% by 2050. The environment that houses this population is the urban boundary layer (UBL). The UBL is the portion of the atmospheric boundary layer whose characteristics are modified by the presence of a city and is regarded as one of the most complex and least understood environments. In order to investigate this region, an electric hybrid (transition) unmanned aerial system (UAS) was meteorologically instrumented. A hybrid UAS allows the meteorological sensor suite to be protected during vertical launch and recovery, allows for more deployment options in an urban environment, and capitalizes on the efficiency of forward flight. This work, under mentoring by Dr. Kevin Adkins, details the design, assembly and integration of the sensor suite that consists of a multi-hole pressure probe along with a temperature and humidity sensor. Each sensor’s data is time and geo-stamped and subsequently post-processed. The instrumented platform is planned to be fielded during the summer of 2020 and beyond

Modulation of Lysenin’s Memory by Cu\u3csup\u3e2+\u3c/sup\u3e Ions

Lysenin is a pore-forming protein extracted from the red earthworm E. fetida, which forms voltage-gated channels in artificial and natural lipid membranes. A prominent feature of the channels is their memory, originating in the conductance hysteresis that occurs during the application of slow oscillatory voltages. In this work, we showed this innate memory was strongly influenced by the addition of small amounts of Cu2+ ions. After Cu2+ addition, the lysenin channels previously closed by an applied voltage showed a stronger preference for the closed state, indicative of major changes in kinetics and equilibrium. However, the physiology behind this shift is still obscure. To fill this gap in our knowledge, we employed electrophysiology measurements to identify the changes in the closing and opening rates of lysenin channels exposed to Cu2+ ions and step voltages. We found Cu2+ simultaneously reduced the closing rates and increased the reopening rates, leading to a more prominent hysteretic behavior and improved memory. These findings may constitute the starting point on investigations of the memory of brainless microorganisms, and potential applications to bioelectronics and development of smart biological switches and nano-valves

IMPACT OF AGRICULTURAL INTERVENTION PROGRAMS ON INCOME AND EMPLOYMENT: EVIDENCE FROM VEGETABLE SECTOR IN KOSOVO

The paper aims to analyse the feasibility of the vegetable crop production in Kosovo by developing a model used to measure the impact of agricultural intervention programs. For this purpose, we have used combination of direct costing (DC) and activity based costing (ABC) to assess the production costs schemes comparing the two crop modalities extended in the two different regions using different cultivars and different production technologies. This study uses a DC and ABC approach in calculating costs in the pepper and tomatoes’ production sectors and in the related agro-processing industries based on five case studies. The results derived from the adopted DC and ABC model in the vegetable sector provide more details and precise cost information that assist various managerial decisions, but are primarily used here to evaluate the impact of agricultural programmes on employment and income generation. It helps government and donors to decide between types of funding intervention programs and to see their impact on agricultural development and employment. Results, which referred to one-hectare area, showed both a higher economic and financial sustainability of good agricultural practice with respect to conventional farming, while the opposite was true in terms of employment effects of intervention programs. The study provides policy implications for both, policy makers and donors when estimating impact of interventions on employment and income levels