John Charles Wills: Reminiscences of the Three Days Battle of Gettysburg at the Globe Hotel

John Charles Wills left the fullest account of what happened at and around the Globe Inn in the borough of Gettysburg during the Battle. In July of 1910, the Gettysburg Compiler interviewed Wills and printed a short story of his observations and experience during the Gettysburg Campaign entitled, Battle Days at Globe Inn. In September of 1915, Wills once again shared his memories of the Battle of Gettysburg, this time in greater length. Fifty two years had passed since the battle occurred and Wills was approximately 77 years old. The 1910 and 191 5 reminiscences are remarkably similar indicating perhaps a good memory or years of re-telling the same stories. Wills does not offer an introduction to his account nor comment on any limitation of his memory. He drifted outside of the timeline of his story on occasion; some of his stories can be refuted, while others cannot be substantiated with any evidence. Wills refers to certain homes and businesses in his account using them as landmarks. It would be easy to assume that his references are to the Gettysburg of 1863; however, several of these places mentioned did not yet exist in 1863 but were contemporary landmarks in the Gettysburg of the early twentieth-century. [excerpt

Mesoscopic dynamical differences from quantum state preparation in a Bose-Hubbard trimer

Conventional wisdom is that quantum effects will tend to disappear as the number of quanta in a system increases, and the evolution of a system will become closer to that described by mean field classical equations. In this letter we combine newly developed experimental techniques to propose and analyse an experiment using a Bose-Hubbard trimer where the opposite is the case. We find that differences in the preparation of a centrally evacuated trimer can lead to readily observable differences in the subsequent dynamics which increase with system size. Importantly, these differences can be detected by the simple measurements of atomic number.Comment: 5 pages, 4 figures, theor

What are the odds? option-based forecasts of FOMC target changes

This article uses probability forecasts derived from options to assess evolving market uncertainty about Federal Reserve monetary policy actions in a variety of recent events and episodes. Options on federal funds futures contracts reveal a complete probability density function over possible Federal Reserve target rates, thus augmenting the expectations provided by federal funds futures contracts. Option-based forecasts are most useful when more than two federal funds target outcomes are plausible at an upcoming policy meeting.Federal Open Market Committee ; Forecasting ; Monetary policy

The BsaHI restriction-modification system: Cloning, sequencing and analysis of conserved motifs

<p>Abstract</p> <p>Background</p> <p>Restriction and modification enzymes typically recognise short DNA sequences of between two and eight bases in length. Understanding the mechanism of this recognition represents a significant challenge that we begin to address for the BsaHI restriction-modification system, which recognises the six base sequence GRCGYC.</p> <p>Results</p> <p>The DNA sequences of the genes for the BsaHI methyltransferase, bsaHIM, and restriction endonuclease, bsaHIR, have been determined (GenBank accession <ext-link ext-link-type="gen" ext-link-id="#EU386360">#EU386360</ext-link>), cloned and expressed in <it>E. coli</it>. Both the restriction endonuclease and methyltransferase enzymes share significant similarity with a group of 6 other enzymes comprising the restriction-modification systems HgiDI and HgiGI and the putative HindVP, NlaCORFDP, NpuORFC228P and SplZORFNP restriction-modification systems. A sequence alignment of these homologues shows that their amino acid sequences are largely conserved and highlights several motifs of interest. We target one such conserved motif, reading SPERRFD, at the C-terminal end of the bsaHIR gene. A mutational analysis of these amino acids indicates that the motif is crucial for enzymatic activity. Sequence alignment of the methyltransferase gene reveals a short motif within the target recognition domain that is conserved among enzymes recognising the same sequences. Thus, this motif may be used as a diagnostic tool to define the recognition sequences of the cytosine C5 methyltransferases.</p> <p>Conclusion</p> <p>We have cloned and sequenced the BsaHI restriction and modification enzymes. We have identified a region of the R. BsaHI enzyme that is crucial for its activity. Analysis of the amino acid sequence of the BsaHI methyltransferase enzyme led us to propose two new motifs that can be used in the diagnosis of the recognition sequence of the cytosine C5-methyltransferases.</p

Effect of Ceramic Reinforcements on the Mechanical Behaviour of 7xxx series Aluminium Matrix Composites

The effect of ceramic reinforcements on the mechanical properties of 7xxx series aluminium matrix composites (AMCs) was critically reviewed. Reinforcement of an Al 7xxx alloy with ceramic particulates is expected to improve its tensile strength but in practice the incorporation has produced diverse results. Some researchers have reported significant increases in the tensile strengths of particulate reinforced 7xxx Al matrices while others have reported decreases in this property. The published data including our present experimental work performed on particulate reinforced Al 7xxx alloys was analysed to study the role of ceramic particulates on the tensile and fracture behaviour of this class of composites. It was concluded that high strength of the matrix can negate the benefits of particulate reinforcements though this role is still ambiguous and further work is required to optimise the potential enhancement of Al 7xxx matrix composites reinforced with nano-scale ceramic particles

Suppressing restricted shock separation in a subscale rocket nozzle using contour geometry

The use of a thrust-optimized contour (TOC) for the supersonic nozzle in a rocket engine will inherently maximize the propulsive efficiency and payload capacity of the entire launch system. A TOC can be approximated using a skewed parabola, commonly referred to as a thrust-optimized parabola (TOP), and the TOP contour can be manipulated to avoid undesirable flow separation during low-altitude operation by increasing the static wall pressure at the expense of thrust (approximately 0.1 0.2%). For this reason, a TOP design is often used in nozzles with a high area ratio, such as those used in the Vulcain and Vulcain 2 corestage engines, and suggests that ensuring full-flowing operation at low-altitude conditions can be considered a nozzle design requirement. Unfortunately, any thrust-optimized nozzle may excite an undesirable shift between a free shock separation (FSS) and restricted shock separation (RSS) mode during engine startup and shutdown. The shift between an FSS and an RSS flowregimewas first noticed during operation of the high-area-ratio J2-S engine, and the RSS condition consequently was deemed responsible for inducing high structural loading to the nozzle walls. However, it was later found that the highest levels of side loading were, in fact, caused by the transition process to and from the RSS flow condition, as opposed to the RSS phenomenon itself. Because the precise flow mechanisms that drive the transition to and from the RSS condition are still not fully understood, the structural loading that occurs as a result of RSS appears to currently be accepted as a design consideration in core-stage rocket nozzles. A nozzle contour that was capable of suppressing the RSS flow condition itself would inherently prevent the transition to and from RSS and, therefore, decrease the structural loading that occurs during these transition phases. For a net benefit to be realized, the resulting nozzle must produce an equal or greater thrust coefficient compared to the existing design, as well as avoid flow separation during low-altitude operation. In this paper, a set of equivalent thrust-optimized nozzle contours have been produced using an arc-based design method to determine if the suppression of RSS could be achieved by manipulating the contour geometry. The subscale Volvo S1 TOP nozzle that was designed by Volvo Aero Corporation (now GKN Aerospace Engine Systems) was selected as the test case due to the availability of experimental data that captures the transition from FSS to RSS and to ensure that a positive result may be applicable to a full-scale rocket engine, because this nozzle has been shown to possess equivalent flow characteristics to the core-stage Vulcain engine nozzle

Localizer:fast, accurate, open-source, and modular software package for superresolution microscopy

We present Localizer, a freely available and open source software package that implements the computational data processing inherent to several types of superresolution fluorescence imaging, such as localization (PALM/STORM/GSDIM) and fluctuation imaging (SOFI/pcSOFI). Localizer delivers high accuracy and performance and comes with a fully featured and easy-to-use graphical user interface but is also designed to be integrated in higher-level analysis environments. Due to its modular design, Localizer can be readily extended with new algorithms as they become available, while maintaining the same interface and performance. We provide front-ends for running Localizer from Igor Pro, Matlab, or as a stand-alone program. We show that Localizer performs favorably when compared with two existing superresolution packages, and to our knowledge is the only freely available implementation of SOFI/pcSOFI microscopy. By dramatically improving the analysis performance and ensuring the easy addition of current and future enhancements, Localizer strongly improves the usability of superresolution imaging in a variety of biomedical studies

Dynamic and Energetic Stabilization of Persistent Currents in Bose-Einstein Condensates

We study conditions under which vortices in a highly oblate harmonically trapped Bose-Einstein condensate (BEC) can be stabilized due to pinning by a blue-detuned Gaussian laser beam, with particular emphasis on the potentially destabilizing effects of laser beam positioning within the BEC. Our approach involves theoretical and numerical exploration of dynamically and energetically stable pinning of vortices with winding number up to $S=6$, in correspondence with experimental observations. Stable pinning is quantified theoretically via Bogoliubov-de Gennes excitation spectrum computations and confirmed via direct numerical simulations for a range of conditions similar to those of experimental observations. The theoretical and numerical results indicate that the pinned winding number, or equivalently the winding number of the superfluid current about the laser beam, decays as a laser beam of fixed intensity moves away from the BEC center. Our theoretical analysis helps explain previous experimental observations, and helps define limits of stable vortex pinning for future experiments involving vortex manipulation by laser beams.Comment: 8 pages 5 figure