Sensory modulation of crustacean non-giant tailflipping

As a first step in re-examining the modulation of non-giant tailflipping, we further investigate how the presence of weapons affects non-giant tailflipping. Removing both claws significantly changes the threshold for tailflipping (Krasne and Wine, 1975; Lang et al., 1977). Claw removal affects several variables at once, however; e.g., the animal’s mass; visual stimuli associated with having claws; tactile and proprioceptive cues. For example, a crayfish with claws that are present but useless might “bluff,” and may not tailflip away from a stimuli more than an intact animal

Compromised weaponry enhances crayfish tailflipping

As a defense strategy, many crustaceans perform one of two well described stereotyped single fast tailflips (~6 ms in adult crayfish), which are triggered by a neural circuit that includes medial giant interneurons (MG) and lateral giant interneurons (LG). Tailflips can also occur without these giant interneurons firing, however; these non-giant tailflips are variable, repetitive, and significantly longer (~150 ms). Previous work showed that crayfish exposed to natural stimulus respond with a non-giant tailflip significantly faster than when presented with an artificial stimulus and that complete removal of claws lowered tailflipping threshold. We tested whether compromising weapons would influence tailflipping. Claws were deafferented by cutting the leg nerve between the coxa-basis joint. Crayfish were presented with artificial tactile stimuli, and their tailflipping behaviour was video recorded in three conditions: intact, deafferentation of one claw, and deafferentation of both claws. Crayfish with either one or both claws deafferented tailflipped greater distances than intact animals when tapped. The orientation that crayfish assumed after tailflipping was not significantly different with claw deafferentation, however. We plan to conduct similar experiments compromising vision and in species that have no claws and use alternate weapons (e.g., antennae)

Observational tests for oscillating expansion rate of the Universe

We investigate the observational constraints on the oscillating scalar field model using data from type Ia supernovae, cosmic microwave background anisotropies, and baryon acoustic oscillations. According to a Fourier analysis, the galaxy number count $N$ from redshift $z$ data indicates that galaxies have preferred periodic redshift spacings. We fix the mass of the scalar field as $m_\phi=3.2\times 10^{-31}h$ ${\rm eV}$ such that the scalar field model can account for the redshift spacings, and we constrain the other basic parameters by comparing the model with accurate observational data. We obtain the following constraints: $\Omega_{m,0}=0.28\pm 0.03$ (95% C.L.), $\Omega_{\phi,0} -158$ (95% C.L.) (in the range $\xi \le 0$). The best fit values of the energy density parameter of the scalar field and the coupling constant are $\Omega_{\phi,0}= 0.01$ and $\xi= -25$, respectively. The value of $\Omega_{\phi,0}$ is close to but not equal to $0$. Hence, in the scalar field model, the amplitude of the galaxy number count cannot be large. However, because the best fit values of $\Omega_{\phi,0}$ and $\xi$ are not $0$, the scalar field model has the possibility of accounting for the periodic structure in the $N$--$z$ relation of galaxies. The variation of the effective gravitational constant in the scalar field model is not inconsistent with the bound from observation.Comment: 9 pages, 11 figures, 1 table, Accepted for publication in Physical Review

Ab initio molecular dynamics with noisy forces: Validating the quantum Monte Carlo approach with benchmark calculations of molecular vibrational properties

We present a systematic study of a recently developed ab initio simulation scheme based on molecular dynamics and quantum Monte Carlo. In this approach, a damped Langevin molecular dynamics is employed by using a statistical evaluation of the forces acting on each atom by means of quantum Monte Carlo. This allows the use of an highly correlated wave function parametrized by several variational parameters and describing quite accurately the Born-Oppenheimer energy surface, as long as these parameters are determined at the minimum energy condition. However, in a statistical method both the minimization method and the evaluation of the atomic forces are affected by the statistical noise. In this work, we study systematically the accuracy and reliability of this scheme by targeting the vibrational frequencies of simple molecules such as the water monomer, hydrogen sulfide, sulfur dioxide, ammonia, and phosphine. We show that all sources of systematic errors can be controlled and reliable frequencies can be obtained with a reasonable computational effort. This work provides convincing evidence that this molecular dynamics scheme can be safely applied also to realistic systems containing several atoms. \ua9 2014 AIP Publishing LLC

Karakteristik Biografis dan Pengaruhnya terhadap Kinerja Individual yang Dimediasi oleh Kepuasan Kerja

Tujuan Penelitian – Penelitian ini bertujuan untuk mengetahui apakah terdapat pengaruh dari karakteristik biografis terhadap kepuasan kerja dan kinerja individual serta apakah kepuasan kerja mampu menjadi variabel mediasi antara karakteristik biografis dengan kinerja individual.Desain/Metodologi/Pendekatan – Penelitian ini merupakan penelitian kausalitas dan data yang digunakan adalah data kuantitatif. Data dikumpulkan dengan menggunakan kuesioner dengan jumlah sampel 220 orang. Data dianalisis menggunakan analisis jalur.Temuan – 1) Tidak ada pengaruh karakteristik biografis terhadap kinerja individual, 2) Ada pengaruh karakteristik biografis dan kepuasan kerja secara bersama-sama terhadap kinerja individual, dan 3) Kepuasan kerja mampu menjadi variabel mediasi (intervening) antara karakteristik biografis dan kinerja individual dosen.Keterbatasan Penelitian – Untuk penelitian selanjutnya dapat ditambahkan variabel lainnya seperti karakteristik pekerjaan dan karakteristik organisasi

Loss of Escape-Related Giant Neurons in a Spiny Lobster, Panulirus Argus

When attacked, many decapod crustaceans perform tailflips, which are triggered by a neural circuit that includes lateral giant interneurons, medial giant interneurons, and fast flexor motor giant neurons (MoGs). Slipper lobsters (Scyllaridae) lack these giant neurons, and it has been hypothesized that behavioral (e.g., digging) and morphological (e.g., flattening and armor) specializations in this group caused the loss of escape-related giant neurons. To test this hypothesis, we examined a species of spiny lobster, Panulirus argus. Spiny lobsters belong to the sister taxon of the scyllarids, but they have a more crayfish-like morphology than scyllarids and were predicted to have escape-related giant neurons. Ventral nerve cords of P. argus were examined using paraffin-embedded sections and cobalt backfills. We found no escape-related giant neurons and no large axon profiles in the dorsal region of the nerve cord of P. argus. Cobalt backfills showed one fewer fast flexor motor neuron than in species with MoGs and none of the fast flexor motor neurons show any of the anatomical specializations of MoGs. This suggests that all palinuran species lack this giant escape circuit, and that the loss of rapid escape behavior preceded, and may have driven, alternative predator avoidance and anti-predator strategies in palinurans

Penelusuran Jenis Pekerjaan Para Alumni Jurusan Bahasa Prancis Fakultas Bahasa Dan Seni Universitas Negeri Jakarta

Lulusan jurusan bahasa Prancis UNJ memperoleh pekerjaan di bidang pendidikan dan nonkependidikan misalnya pariwisata, perhotelan, sekretaris, alih bahasa dan interpreting (penerjemahan lisan). Hal ini terjadi karena terbatasnya lapangan kerja di bidang pengajaran apalagi akibat Perubahan orientasi kurikulum di sekolah menengah untuk pelajaran bahasa asing kecuali Inggris, sebagian alumni terpaksa tidak bekerja di lapangan pengajaran bahasa. Penelitian ini menggunakan metode deskriptif . Instrumen dalam penelitian ini adalah angket yang terbagi dalam dua bagian. Bagian pertama (A) merupakan identitas responden dan bagian Kedua (B) merupakan aspek keadaan lulusan dan kurikulum Jurusan Bahasa Prancis. Tujuan penelitian ini untuk memperoleh data terkini mengenai lapangan kerja para alumni Jurusan Bahasa Prancis dan kaitannya dengan kurikulum Jurusan Bahasa Prancis. Hasil penelitian menunjukkan bahwa jenis kompetensi yang dibutuhkan lulusan JBP saat ini di pasar kerja saat ini sangat bervariasi, yang berkaitan dengan kompetensi kebahasaan, kompetensi administrasi dan perkantoran, serta keahlian magerial, dan yang terakhir adalah kompetensi di bidang wiraswasta, yaitu USAha menciptakan lapangan kerja secara mandiri

Microcracks, spall and fracture in glass : A study using short pulsed laser shock waves

Copyright 1998 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics, 83(7), 3583-3594, 1998 and may be found at http://dx.doi.org/10.1063/1.36657