Symmetric and Asymmetric Coalescence of Drops on a Substrate

The coalescence of viscous drops on a substrate is studied experimentally and theoretically. We consider cases where the drops can have different contact angles, leading to a very asymmetric coalescence process. Side view experiments reveal that the "bridge" connecting the drops evolves with self-similar dynamics, providing a new perspective on the coalescence of sessile drops. We show that the universal shape of the bridge is accurately described by similarity solutions of the one-dimensional lubrication equation. Our theory predicts a bridge that grows linearly in time and stresses the strong dependence on the contact angles. Without any adjustable parameters, we find quantitative agreement with all experimental observations.Comment: 5 pages, 4 figure

Rancang Bangun Alat Pengering Tipe Tray Dryer

Kabupaten Limapuluh Kota merupakan salah satu daerah penghasil pinang di Sumatera Barat. Salah satu penanganan pasca panen terhadap buah pinang adalah pengeringan. Tahap pengeringan pinang oleh petani dilakukan dengan memanfaatkan sinar matahari. Pengeringan dengan cara ini sangat bergantung dengan keadaan cuaca sehingga tahap pengeringan tidak berjalan dengan baik. Untuk mengatasi permasalahan pengeringan buah pinang diatas, maka dibuat alat pengering sederhana yang mudah, efisien dan efektif jika di bandingkan dengan pengeringan secara manual. Alat pengering pinang ini memiliki sumber panas dari pembakaran serbuk gergaji. Berdasarkan pengujian kinerja, alat pengering pinang mampu mengeringkan 10 kg menjadi 1 kg dengan waktu pengeringan selama 10 jam, kadar air 10,1%. Analisa ekonomi teknik pada alat pengering pinang tipe tray drayer didapat biaya pokok Rp. 18. 795,51812/jam, BEP (Break Event Point) Rp. 34. 0361 Kg/tahun dengan harga jual alat Rp. 4.214.600,-

Elastodynamics of a soft strip subject to a large deformation

To produce sounds, we adjust the tension of our vocal cords to shape their properties and control the pitch. This efficient mechanism offers inspiration for designing reconfigurable materials and adaptable soft robots. However, understanding how flexible structures respond to a significant static strain is not straightforward. This complexity also limits the precision of medical imaging when applied to tensioned organs like muscles, tendons, ligaments and blood vessels among others. In this article, we experimentally and theoretically explore the dynamics of a soft strip subject to a substantial static extension, up to 180\%. Our observations reveal a few intriguing effects, such as the resilience of certain vibrational modes to a static deformation. These observations are supported by a model based on the incremental displacement theory. This has promising practical implications for characterizing soft materials but also for scenarios where external actions can be used to tune properties

A classical explanation of quantization

In the context of our recently developed emergent quantum mechanics, and, in particular, based on an assumed sub-quantum thermodynamics, the necessity of energy quantization as originally postulated by Max Planck is explained by means of purely classical physics. Moreover, under the same premises, also the energy spectrum of the quantum mechanical harmonic oscillator is derived. Essentially, Planck's constant h is shown to be indicative of a particle's "zitterbewegung" and thus of a fundamental angular momentum. The latter is identified with quantum mechanical spin, a residue of which is thus present even in the non-relativistic Schroedinger theory.Comment: 20 pages; version accepted for publication in Foundations of Physic

Producción y descomposición de hojarasca en el bosque natural de Cayo Quemado, Livingston, Izabal, Guatemala

Los bosques naturales de los sistemas marino costeros son importantes por los bienes y servicios ambientales que prestan. Sin embargo, en la Costa Atlántica del país son vulnerables a múltiples amenazas. Como parte de un inventario de carbono del bosque natural Cayo Quemado, se cuantificó la producción y descomposición de hojarasca de las especies vegetales predominantes por unidad de área: Mangle rojo (Rhizophora mangle) 38.14%, zapotón (Pachira aquatica) 19.07%, cahue (Pterocarpus officinalis) 18.56% y anonillo (Rollinia pittieri) 7.22%. En bloques de 30 x 30 m, fueron colocadas en forma aleatoria trampas de 2 x 2 m, y bolsas de descomposición con 200 g de hojarasca fresca, con tres repeticiones, con lecturas cada 30 días. Se concluye que el mangle rojo aportó 0.6015, el zapotón 0.2701, el cahué 0.1836 y el anonillo 0.1119 para un total de 1.1671 MgC/ha, equivalentes a 4.28 MgCO2/ha. Así mismo, se determinó que después de cinco meses de descomposición la masa seca remanente fue de cahué (47.9%), zapotón (40.94%), mangle (38.86%) y anonillo (30.41%) en base a peso seco. El rol de las especies vegetales asociadas a los manglares es de suma importancia por su naturaleza recalcitrante y preservación del Cayo Quemado per se

Taenia solium Cysticercosis in the Democratic Republic of Congo: How Does Pork Trade Affect the Transmission of the Parasite?

Taenia solium is a parasite that can affect both humans and pigs, causing important economic losses in pig production and being the main cause of acquired epilepsy in endemic areas. However, the parasite has been neglected in many African countries and particularly in the Democratic Republic of Congo (DRC), where recent data are non-existent. The present study is part of a first initiative to assess whether cysticercosis is actually present in DRC and to estimate its potential economic and public health importance. Focusing our work on porcine cysticercosis, we demonstrated high prevalence figures of active infections in villages in a rural area of DRC and in markets in the city of Kinshasa. Moreover, the intensity of infection was higher in pigs sampled in villages as compared to pigs sampled on urban markets. Preliminary surveys conducted in parallel in both study sites suggest an effect of pork trade on the transmission of the parasite selecting highly infected pigs at village level

Measurement of prompt and nonprompt charmonium suppression in PbPb collisions at 5.02 TeV

The nuclear modification factors of J/psi and psi(2S) mesons are measured in PbPb collisions at a centre-of-mass energy per nucleon pair of root S-NN = 5.02 TeV. The analysis is based on PbPb and pp data samples collected by CMS at the LHC in 2015, corresponding to integrated luminosities of 464 mu b(-1) and 28 pb(-1), respectively. The measurements are performed in the dimuon rapidity range of vertical bar y vertical bar 25 GeV/c is seen with respect to that observed at intermediate p(T). The prompt psi(2S) meson yield is found to be more suppressed than that of the prompt J/psi mesons in the entire p(T) range.Peer reviewe