A Direct Asymmetric Synthesis of Juglomycin A

Juglomycin A has been synthesized in four steps from 5-methoxy-1-naphthol

A Direct Route to Biologically Active Kainic Acid Analogs

The synthesis of kainic acid, acromelic acid, and related compounds such as domoic acid has been the subject of considerable investigation.1 The observation by Shirahama that 1a and 1b have potent neurophysiological activity has spawned intense synthetic attention toward C-4 aryl analogs.2 Control of the C-3/C-4 stereochemistry is important, since the isomer bearing the opposite stereochemistry exhibits little biological activity. Most of the synthetic routes to C-4 aryl analogs begin from 4-hydroxyproline.3 Most notable among these routes is a recent contribution by Baldwin and co-workers wherein the crucial C-3/C-4 stereochemistry was introduced by a hydroxyl-directed hydrogenation.4 As part of a program to better understand the interplay between the structure, activity, and toxicological profiles of kainoids, we required a direct route to the kainoid skeleton.5 We report herein a very direct route to racemic 1a from the dimethyl ester of R-keto glutaric acid (2) and nitrostyrene 3

Principles of Discrete Time Mechanics: IV. The Dirac Equation, Particles and Oscillons

We apply the principles of discrete time mechanics discussed in earlier papers to the first and second quantised Dirac equation. We use the Schwinger action principle to find the anticommutation relations of the Dirac field and of the particle creation operators in the theory. We find new solutions to the discrete time Dirac equation, referred to as oscillons on account of their extraordinary behaviour. Their principal characteristic is that they oscillate with a period twice that of the fundamental time interval T of our theory. Although these solutions can be associated with definite charge, linear momentum and spin, such objects should not be observable as particles in the continuous time limit. We find that for non-zero T they correspond to states with negative squared norm in Hilbert space. However they are an integral part of the discrete time Dirac field and should play a role in particle interactions analogous to the role of longitudinal photons in conventional quantum electrodynamics.Comment: 27 pages LateX; published versio

An Electrophysiological Analysis of the Primary Input to the Cat Prepyriform Cortex

Properties of the lateral olfactory tract (LOT) action potential and cortical evoked potential (EPSP) were studied using discrete stimuli applied to the tract in acute and chronic preparations. Stimulus response curves for both presynaptic (action) and postsynaptic (EPSP) potentials were sigmoidal and linearly related over the entire range. Simulated action potentials were used to determine the diameter to amplitude relationship, an intermediate step for finding the threshold as a function of tract axon diameter. Our results indicate that threshold is proportional to (diameter) -3.4 instead of (diameter) -1 as found by others in frog peripheral nerve. Further work is required to test the validity of this method. The tract membrane time constant determined from strength-duration data was 0.3 msec. Divergent and convergent LOT to cortex pathways have been reported. We found that a given cortical cell could be activated equally well from sites anterior or posterior to the recording electrode. This supports the anatomical work of others showing collaterals leaving the tract to synapse with cortical cells, with the main axon sending collaterals along the length of the tract (divergence). Neurons were also activated with similar thresholds at points across the tract trajectory, indicative of convergence from several axons. Antidromic axons had punctate threshold points. Centrifugal axons originating from cortical neurons were found in the olfactory tract. To show this, middle prepyriform cortical neurons were antidromically driven by peduncular volleys. Antidromic cells had much shorter latencies than orthodromically driven cells (Kolmogorov- Smirnov Test). Further, antidromic cells were found slightly above the superficial pyramidal cell layer or in it, the area thought to be the source of centrifugal fibers because of retrograde degeneration following bulbar lesions. The existence of centrifugal fibers points to the possibility of cortical control over olfactory information processed in the bulb. Orthodromically driven cells were classified into firing pattern groups similar to those described in previous studies. Temporal firing patterns determined by poststimulus time histograms and their integrals were used to further separate these cells into subclasses. Generally, spontaneously active cells were inhibited by LOT volleys, the inhibitory period lengthening with increased stimulus intensity. Two recovery patterns were observed, a gradual smooth recovery to spontaneity and a rebound type. Modifications or additions to wiring diagrams presented by others are not suggested in this study

Cardioregulatory Role of the Abdominal Ganglion of APLYSIA CALIFORNICA

An isolated heart-abdominal ganglion preparation of this mollusc was developed and used to study the cardioregulatory function of the ganglion and nerves. The heart was perfused with artificial sea water through an atrial cannula and the gastro-esophageal artery was catheterized for blood pressure monitoring. The presence and cardioregulatory effects of axons in the nerves was investigated by electrical stimulation. Fine-tipped glass microelectrodes inserted into ganglionic neurons were used to determine the relationship between the neuronal and cardiac activities. The principal results are listed below. Primarily inhibitory responses are obtained from both right and left connective stimulation, with some evidence for excitatory axons. The siphon nerve exerts a strong inhibitory influence on the heart, probably acting as part of a feedback pathway. Predominantly acceleratory responses are elicited from pericardial nerve stimulation (confirming work of Wright, 1960, and Carlson, 1905). A high frequency spike burst in L7 precedes bradycardia, a coincidental but not deterministic relationship obtained from one subject. Preliminary evidence indicates the presence of a nondeterministic inhibition of long duration in cell L10 associated with bradycardia. There is speculative evidence for inhibitory axons in the genital nerve

Principles of Discrete Time Mechanics: II. Classical field Theory

We apply the principles discussed in an earlier paper to the construction of discrete time field theories. We derive the discrete time field equations of motion and Noether's theorem and apply them to the Schrodinger equation to illustrate the methodology. Stationary solutions to the discrete time Schrodinger wave equation are found to be identical to standard energy eigenvalue solutions except for a fundamental limit on the energy. Then we apply the formalism to the free neutral Klein Gordon system, deriving the equations of motion and conserved quantities such as the linear momentum and angular momentum. We show that there is an upper bound on the magnitude of linear momentum for physical particle-like solutions. We extend the formalism to the charged scalar field coupled to Maxwell's electrodynamics in a gauge invariant way. We apply the formalism to include the Maxwell and Dirac fields, setting the scene for second quantisation of discrete time mechanics and discrete time Quantum Electrodynamics.Comment: 23 pages, LateX, To be published in J.Phys.A: Math.Gen: contact email address: [email protected]

Coronal X-ray emission from an intermediate-age brown dwarf

We report the X-ray detection of the brown dwarf (BD) companion TWA 5B in a $\simeq 12$ Myr old pre-main sequence binary system. We clearly resolve the faint companion (35 photons) separated from the X-ray luminous primary by 2 arcsec in a {\it Chandra} ACIS image. TWA 5B shows a soft X-ray spectrum with a low plasma temperature of only 0.3 keV and a constant flux during the 3 hour observation, of which the characteristics are commonly seen in the solar corona. The X-ray luminosity is 4$\times10^{27}$ erg s$^{-1}$ (0.1--10 keV band) or $\log L_X/L_{bol} = -3.4$. Comparing these properties to both younger and older BDs, we discuss the evolution of the X-ray emission in BDs. During their first few Myr, they exhibit high levels of X-ray activity as seen in higher mass pre-main sequence stars. The level in TWA 5B is still high at $t \simeq 12$ Myr in $\log L_X/L_{bol}$ while $kT$ has already substantially cooled

Program Management for Sustainable University CubeSat Programs Based on the Experience of Five Generations of CubeSat Projects, BIRDS Program

BIRDS program is a university CubeSat program whose primary mission is capacity building of non-space faring countries. It has been run by Kyushu Institute of Technology, Japan, where a group of foreign and Japanese students designs, builds, tests and operates CubeSats. The program started in 2015. Roughly every year since 2017, BIRDS program delivered and launched multiple CubeSats from International Space Station. In total, the program generated 17 CubeSats in five generations. The satellites have been designed in a way so that even satellite beginners can go through the satellite system life cycles from the mission definition to the operation in two years, the duration of Master course. Subsequent generations of students overlap in the laboratory so that they can inherit the know-hows and the experience directly in-person. The satellite design has been modified based on the lessons learned in the former generations, especially during the operation phase. After going through the series of developments and operations, the satellite bus has become very mature. Currently, the initiative to open-source the BIRDS bus is also running. The program, rather than project, management aspects of university CubeSat program is discussed

BIRDS-2: Multi-Nation Cubesat Constellation Project for Learning and Capacity Building

The BIRDS project began in October, 2015 with an objective to provide hands on experience to the graduate students on satellite technology. In a BIRDS project, the students define missions, design, build, test, and operate satellite within given time frame of the project. A 1U CubeSat is built per participating country which are then released from International Space Station (ISS) into Low Earth Orbit (LEO) and operated through a ground station network, with one ground station established in each member nation. That being the first is series, the second BIRDS project or so called BIRDS-2 project started in November, 2016 with students from, Philippines, Bhutan, Malaysia and Japan. Lean philosophy is adopted for the development of CubeSats and an overlap of a year is created between successive projects so that the lessons learned and knowledge gained from each project is properly passed on. The BIRDS program targets to improve the development process of a CubeSat while maintaining/improving the reliability and reducing waste. But the true success of the program is indicated by the ability of project members to replicate what they learn from this project, at their home country after graduating