Buckling without bending: a new paradigm in morphogenesis

A curious feature of organ and organoid morphogenesis is that in certain cases, spatial oscillations in the thickness of the growing "film" are out-of-phase with the deformation of the slower-growing "substrate," while in other cases, the oscillations are in-phase. The former cannot be explained by elastic bilayer instability, and contradict the notion that there is a universal mechanism by which brains, intestines, teeth, and other organs develop surface wrinkles and folds. Inspired by the microstructure of the embryonic cerebellum, we develop a new model of 2d morphogenesis in which system-spanning elastic fibers endow the organ with a preferred radius, while a separate fiber network resides in the otherwise fluid-like film at the outer edge of the organ and resists thickness gradients thereof. The tendency of the film to uniformly thicken or thin is described via a "growth potential". Several features of cerebellum, +blebbistatin organoid, and retinal fovea morphogenesis, including out-of-phase behavior and a film thickness amplitude that is comparable to the radius amplitude, are readily explained by our simple analytical model, as may be an observed scale-invariance in the number of folds in the cerebellum. We also study a nonlinear variant of the model, propose further biological and bio-inspired applications, and address how our model is and is not unique to the developing nervous system.Comment: version accepted by Physical Review

Pengaruh Pengurangan Diameter Valvestem Dan Penambahan Radius Valveneck Terhadap Performa Motor Bakar Honda Supra Fit 100 CC

Salah satu untuk meningkatkan performa dari sepeda motor adalah dengan melakukan penggantian katup standard ke katup racing. Katup racing ini bertujuan untuk memperlancar aliran udara yang masuk ke ruang bakar. Katup racing, biasanya, cara memodifikasinya adalah dengan melakukan pengurangan diameter pada batang katup. Pemilihan diameter katup pada penelitian ini adalah pengurangan sebesar 0,7 mm, 0,9 mm, dan 1,1 mm, dan membandingkan ketiga diameter dengan katup ukuran standard. Metode pengujian yang dilakukan pada penelitian ini adalah dengan melakukan simulasi aliran dengan menggunakan program komputer ANSYS. Serta dengan melakukan uji dynotest untuk mengetahui peningkatan daya dan torsi, sebelum dan sesudah dilakukan penggantian pada masing-masing variasi pada katup. Hasil yang didapatkan setelah melakukan simulasi adalah katup dengan diameter batang yang diperkecil menghasilkan pressure drop yang lebih kecil dan velocity yang besar. Hasil tersebut dicapai oleh katup dengan pengurangan sebesar 0,9 mm. Untuk hasil dynotest, daya tertinggi dicapai oleh katup dengan pengurangan sebesar 1,1 mm. yaitu 6,8 HP, mengalami pengingkatan sebesar 17,24%. Sedangkan torsi maksimum dicapai oleh katup dengan pengurangan 0,9 mm, yaitu 7,39 N.m, meningkat sebesar 14,75% dari katup standard

Unified cyclic stress-strain model for normal and high strength concrete confined with FRP

Fiber reinforced polymer (FRP) has become increasingly popular as a confining material for concrete, both in the strengthening of existing columns where FRP wraps with fibers oriented completely or predominantly in the hoop direction are typically used, and in new construction where filament-wound FRP tubes with fibers oriented at desired angles to the longitudinal axis are typically used. For both types of applications, the stress-strain behavior of FRP-confined concrete under cyclic axial compression needs to be properly understood and modeled for the accurate simulation of such columns under seismic loading. This paper presents an improved cyclic stress-strain model for FRP-confined concrete on the basis of a critical assessment of an earlier model proposed by Lam and Teng in 2009 by making use of a database containing new test results of both concrete-filled FRP tubes (CFFTs) and concrete cylinders confined with an FRP wrap. The assessment reveals several deficiencies of Lam and Teng\u27s model due to the limited test results available to them. The proposed model corrects these deficiencies and is shown to provide reasonably accurate predictions for both concrete in CFFTs and concrete confined with an FRP wrap and for both normal strength concrete (NSC) and high strength concrete (HSC)

A Storm in a "T" Cup

We revisit the process of transversification and agglomeration of particle momenta that are often performed in analyses at hadron colliders, and show that many of the existing mass-measurement variables proposed for hadron colliders are far more closely related to each other than is widely appreciated, and indeed can all be viewed as a common mass bound specialized for a variety of purposes.Comment: 3 pages, 2 figures, presented by K.C. Kong at the 19th Particles and Nuclei International Conference, PANIC 2011, MIT, Cambridge, MA (July 24-29, 2011

BUSINESS PROCESS REDESIGN AND INFORMATION ARCHITECTURE: ESTABLISHING THE MISSING LINKS

Business Process Redesign (BPR) and Information Architecture (IA) have been recognized as high organizational priority agenda items in the 1990s. This paper provides tile premise for integrating these two critical issues. A model depicting the relationship between IA and BPR is presented. IA design and BPR share a common focus on business processes and, when properly conducted, IA design should produce a stable information architecture capable of supporting existing as well as improved business processes. Furthermore, selected IA methods and techniques are recommended for possible application in BPR. Future research is suggested concerning the need to validate this BPR and IA relationship and test the appropriateness of applying IA methodologies to BPR

Exploring the Dust Content of Galactic Winds with Herschel. I. NGC 4631

We present a detailed analysis of deep far-infrared observations of the nearby edge-on star-forming galaxy NGC 4631 obtained with the Herschel Space Observatory. Our PACS images at 70 and 160 um show a rich complex of filaments and chimney-like features that extends up to a projected distance of 6 kpc above the plane of the galaxy. The PACS features often match extraplanar Halpha, radio-continuum, and soft X-ray features observed in this galaxy, pointing to a tight disk-halo connection regulated by star formation. On the other hand, the morphology of the colder dust component detected on larger scale in the SPIRE 250, 350, and 500 um data matches the extraplanar H~I streams previously reported in NGC 4631 and suggests a tidal origin. The PACS 70/160 ratios are elevated in the central ~3.0 kpc region above the nucleus of this galaxy (the "superbubble"). A pixel-by-pixel analysis shows that dust in this region has a higher temperature and/or an emissivity with a steeper spectral index (beta > 2) than the dust in the disk, possibly the result of the harsher environment in the superbubble. Star formation in the disk seems energetically insufficient to lift the material out of the disk, unless it was more active in the past or the dust-to-gas ratio in the superbubble region is higher than the Galactic value. Some of the dust in the halo may also have been tidally stripped from nearby companions or lifted from the disk by galaxy interactions.Comment: Accepted for publication in The Astrophysical Journa