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Existing Protocols (existing + protocol)
Selected AbstractsTesting extraction and storage parameters for a fecal hormone methodAMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2010David J. Pappano Abstract Four experiments were conducted to test different aspects of a "field-friendly" fecal hormone extraction method that utilizes methanol extraction in the field followed by storage on C18 solid-phase extraction cartridges. Fecal samples were collected from geladas (Theropithecus gelada) housed at the Bronx Zoo, and the experiments were conducted in a laboratory setting to ensure maximum control. The experiments were designed to either simulate the conditions to which fecal samples are subjected during fieldwork or improve on an existing protocol. The experiments tested the relationship between fecal hormone metabolite preservation/recovery and: (1) the amount of time a sample is stored at ambient temperature; (2) the number of freeze/thaw cycles a sample undergoes; (3) the effectiveness of different extraction solutions; and (4) the effectiveness of different cartridge washes. For each experiment, samples were assayed by radioimmunoassay for fecal glucocorticoid (GC) and testosterone (T) metabolites. Results for each of the experiments were as follows. First, storage at ambient temperature did not affect hormone levels until 4 weeks of storage, with significant increases for both GC and T metabolites at 4 weeks. Second, hormone levels significantly decreased in samples after two freeze/thaw cycles for GCs and six freeze/thaws cycles for T. Third, for both GCs and T, hormone extraction using various methanol solutions was significantly higher than using 100% ethanol. Finally, using a 20% methanol solution to wash cartridges significantly increased GC levels but had no effect on T levels. These results suggest that, when utilizing C18 cartridges for fecal steroid storage, researchers should consider several methodological options to optimize hormone preservation and recovery from fecal samples. Am. J. Primatol. 72:934,941, 2010. © 2010 Wiley-Liss, Inc. [source] Re-refinement from deposited X-ray data can deliver improved models for most PDB entriesACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2009Robbie P. Joosten The deposition of X-ray data along with the customary structural models defining PDB entries makes it possible to apply large-scale re-refinement protocols to these entries, thus giving users the benefit of improvements in X-ray methods that have occurred since the structure was deposited. Automated gradient refinement is an effective method to achieve this goal, but real-space intervention is most often required in order to adequately address problems detected by structure-validation software. In order to improve the existing protocol, automated re-refinement was combined with structure validation and difference-density peak analysis to produce a catalogue of problems in PDB entries that are amenable to automatic correction. It is shown that re-refinement can be effective in producing improvements, which are often associated with the systematic use of the TLS parameterization of B factors, even for relatively new and high-resolution PDB entries, while the accompanying manual or semi-manual map analysis and fitting steps show good prospects for eventual automation. It is proposed that the potential for simultaneous improvements in methods and in re-refinement results be further encouraged by broadening the scope of depositions to include refinement metadata and ultimately primary rather than reduced X-ray data. [source] An efficient MAC protocol for multi-channel mobile ad hoc networks based on location informationINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2006Yu-Chee Tseng Abstract This paper considers the channel assignment problem in a multi-channel MANET environment. We propose a scheme called GRID, by which a mobile host can easily determine which channel to use based on its current location. In fact, following the GSM style, our GRID spends no communication cost to allocate channels to mobile hosts since channel assignment is purely determined by hosts' physical locations. We show that this can improve the channel reuse ratio. We then propose a multi-channel MAC protocol, which integrates GRID. Our protocol is characterized by the following features: (i) it follows an ,on-demand' style to access the medium and thus a mobile host will occupy a channel only when necessary, (ii) the number of channels required is independent of the network topology, and (iii) no form of clock synchronization is required. On the other hand, most existing protocols assign channels to a host statically even if it has no intention to transmit [IEEE/ACM Trans. Networks 1995; 3(4):441,449; 1993; 1(6): 668,677; IEEE J. Selected Areas Commun. 1999; 17(8):1345,1352], require a number of channels which is a function of the maximum connectivity [IEEE/ACM Trans. Networks 1995; 3(4):441,449; 1993; 1(6): 668,677; Proceedings of IEEE MILCOM'97, November 1997; IEEE J. Selected Areas Commun. 1999; 17(8):1345,1352], or necessitate a clock synchronization among all hosts in the MANET [IEEE J. Selected Areas Commun. 1999; 17(8):1345,1352; Proceedings of IEEE INFOCOM'99, October 1999]. Through simulations, we demonstrate the advantages of our protocol. Copyright © 2005 John Wiley & Sons, Ltd. [source] Design of multichannel MAC protocols for wireless ad hoc networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 5 2009Shou-Chih Lo Medium access control (MAC) protocols coordinate channel access between wireless stations, and they significantly affect the network throughput of wireless ad hoc networks. MAC protocols that are based on a multichannel model can increase the throughput by enabling more simultaneous transmission pairs in the network. In this paper, we comprehensively compare different design methods for multichannel MAC protocols. We classify existing protocols into different categories according to the channel negotiation strategies they employ. The common problems that may be encountered in multichannel design are discussed. We then propose a hybrid protocol that combines the advantages of the two methods of a common control channel and a common control period. The simulation results show that our proposed protocol can significantly outperform two representative protocols. Copyright © 2008 John Wiley & Sons, Ltd. [source] One-Pot Thioetherification of Aryl Halides Using Thiourea and Alkyl Bromides Catalyzed by Copper(I) Iodide Free from Foul-Smelling Thiols in Wet Polyethylene Glycol (PEG 200)ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2010Habib Firouzabadi Abstract In this article, we have developed a new protocol for the thioarylation of structurally diverse alkyl bromides such as benzyl, cinnamyl, n -octyl, cyclohexyl, cyclopentyl, and tert -butyl bromides with aryl iodides, bromides and an activated chloride using thiourea catalyzed by copper(I) iodide in wet polyethylene glycol (PEG 200) as an eco-friendly medium in the presence of potassium carbonate at 80 and 100,°C under an inert atmosphere. The process is free from foul-smelling thiols which makes this method more practical for the thioetherification of aryl halides. Another important feature of this method is the variety of alkyl bromides which are commercially available for the in situ generation of thiolate ions with respect to the existing protocols in which the less commercially available thiols are directly used for the preparation of arylthio ethers. [source] The MAGi RNA extraction method: a highly efficient and simple procedure for fresh and dry plant tissuesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2009e Gül Ince Abstract BACKGROUND: Samples from different plant species, different organs or tissues at different times of the year, usually show great differences in their cell compositions, pH, and the endogenous RNase activities, decreasing the RNA yield and quality. RESULTS: In this study we describe a reagent and a simple total RNA isolation method for plant organs, tissues and dry seeds. The RNA extraction reagent (MAGi) is non-toxic and can be stored at room temperature for several months to years. The principle of the total RNA extraction is that tissues are lysed in extraction solution with the aid of mortar homogenization,maceration, and cellular proteins, polysaccharides and DNA are removed from the RNA. We tested the reported method on more than 16 different types of plant seed and 15 different tissues and organs of pepper. CONCLUSION: The RNA extraction procedure reported in the present study greatly reduces the time required to isolate dry seed total RNA and other tissues by more than half as compared with the previously reported methods. The range of typical RNA yield and quality represents a significant improvement over existing protocols. The quality is high enough to be considered as suitable method for RT-PCR, cDNA library construction and microarray gene expression studies. Copyright © 2008 Society of Chemical Industry [source] Effect of light filters on reading speed in normal and low vision due to age-related macular degenerationOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2004Frank Eperjesi Abstract Purpose:, To investigate the effects of light filters on reading speed in normal and low vision due to age-related macular degeneration (AMD). Methods:, Reading speed was determined for 12 subjects with normal vision and 12 subjects with non-exudative AMD using stationary lowercase nonsensical print in Times Roman font and four light filters; a yellow Corning Photochromic Filter (CPF) 450, a grey neural density (ND) filter, an individual filter obtained using the Intuitive Colorimeter® and a clear filter. Results:, There was no statistically significant light filter effect on reading speed for the normal subjects. The AMD group demonstrated a statistically significant 5% average improvement in reading speed with the CPF450 compared with the other filters although some AMD subjects had improvements of 10,15%. Conclusions:, Light filters obtained using the Intuitive Colorimeter® performed poorly when compared with the CPF450, ND and clear filters for both the study groups. For the AMD group, average reading speed was statistically greater with the CPF450 than the other filters, however it is questionable whether the improvement (5%) would be clinically significant. As some of the subjects with AMD had greater improvements with the CPF450 we advocate clinical assessment of light filters using existing protocols on an individual basis. [source] | ||||||||||