Cutaneous eccrine glands of the foot pads of the rock hyrax (Procavia capensis, Hyracoidea, mammalia)

In order to find correlations between skin gland morphology and specific ethological features, the cutaneous glands of the foot pads of Procavia capensis were studied by histological and various histochemical methods and by electron microscopy. In the foot pads, abundant specific eccrine skin glands occur, which consist of coiled tubular secretory portions and coiled ducts. The wall of the secretory part is composed of cuboidal glandular cells and myoepithelial cells. Among the glandular cells two types occur: clear and dark cells. Clear cells have numerous mitochondria and form a basal labyrinth, indicating fluid transport. Dark cells, which stain strongly with periodic acid-Schiff, contain a highly developed perinuclear Golgi apparatus, large amounts of rough endoplasmic reticulum and many secretory granules indicating production of glycoproteins. Cytokeratin (CK) 19 was found in secretory compartments and ducts, CK14 only in duct cells. Single cells of the secretory coils and ducts may be stained with antibodies against antimicrobial peptides. Some glandular cells contain proliferating cell nuclear antigen-positive nuclei especially in the ducts indicating an increased cell proliferation. Terminal transferase (TdT)-mediated d-UTP nick-end labeling-positive nuclei can be detected predominantly in the secretory coils and rarely in the transitional portions between ducts and end pieces. We suppose that proliferating cells migrate from the ducts to the secretory coils. The secretory product of the eccrine cutaneous glands seems to improve the traction between the foot pads of these animals and the steep and smooth rock formations among which they live

Self-referencable frequency comb from a 170-fs, 1.5-μm solid-state laser oscillator

We report measurement of the first carrier-envelope offset (CEO) frequency signal from a spectrally broadened ultrafast solid-state laser oscillator operating in the 1.5μm spectral region. The f-to-2f CEO frequency beat signal is 49 dB above the noise floor (100-kHz resolution bandwidth) and the free-running linewidth of 3.6 kHz is significantly better than typically obtained by ultrafast fiber laser systems. We used a SESAM mode-locked Er:Yb:glass laser generating 170-fs pulses at a 75MHz pulse repetition rate with 110-mW average power. It is pumped by one standard telecom-grade 980-nm diode consuming less than 1.5W of electrical power. Without any further pulse compression and amplification, a coherent octave-spanning frequency comb is generated in a polarization-maintaining highly-nonlinear fiber (PM-HNLF). The fiber length was optimized to yield a strong CEO frequency beat signal between the outer Raman soliton and the spectral peak of the dispersive wave within the supercontinuum. The polarization-maintaining property of the supercontinuum fiber was crucial; comparable octave-spanning supercontinua from two non-PM fibers showed higher intensity noise and poor coherence. Astable CEO-beat was observed even with pulse durations above 200fs. Achieving a strong CEO frequency signal from relatively long pulses with moderate power levels substantially relaxes the demands on the driving laser, which is particularly important for novel gigahertz diode-pumped solid-state and semiconductor laser

Picosecond diode-pumped 1.5 μm Er,Yb:glass lasers operating at10-100 GHz repetition rate

Stable ultrafast laser sources at multi-GHz repetition rates are important for various application areas, such as optical sampling, frequency comb metrology, or advanced high-speed return-to-zero telecom systems. We review SESAM-mode-locked Er,Yb:glass lasers operating in the 1.5μm spectral region at multi-GHz repetition rates, discussing the key improvements that have enabled increasing the repetition rate up to 100GHz. We also present further improved results with shorter pulse durations from a 100GHz Er,Yb:glass laser. With an improved SESAM design we achieved 1.1ps pulses with up to 30mW average output power. Moreover, we discuss for the first time the importance of beam quality deteriorations arising from frequency-degenerate higher order spatial modes in such laser

Critical Competencies of 4-H Camp Staff for Achieving High Performance

Camps provide a substantial opportunity for youth to develop important life skills. Identifying and training staff on critical competencies are essential to achieving the desired outcomes for camp participants. The purpose of this study was to determine the most critical competencies of the 4-H residential camp staff for achieving high staff performance. The modified Delphi technique was used to achieve study objectives. The Delphi panel of this study consisted of 23 4-H camping experts from across the United States. This three-round Delphi study led to identify 15 critical competencies that will be useful in standardizing 4-H camp staff training programs

Atomistic modelling of large-scale metal film growth fronts

We present simulations of metallization morphologies under ionized sputter deposition conditions, obtained by a new theoretical approach. By means of molecular dynamics simulations using a carefully designed interaction potential, we analyze the surface adsorption, reflection, and etching reactions taking place during Al physical vapor deposition, and calculate their relative probability. These probabilities are then employed in a feature-scale cellular-automaton simulator, which produces calculated film morphologies in excellent agreement with scanning-electron-microscopy data on ionized sputter deposition.Comment: RevTeX 4 pages, 2 figure

The development of post-processing algorithm for the ultrasonic evaluation by the application of automated robotic testing systems

The implementation of automated testing systems based on six degrees of freedom (DOF) robotic manipulators is the actual trend in ultrasonic testing equipment development. Such systems are able to provide a fast ultrasonic evaluation with the respect of the surface of the testing object. In this work, the post-processing algorithm based on Synthetic Aperture Focusing Technique (SAFT) is suggested. Such algorithm allows presenting the results in the form of high-resolution imagery of the internal structure of testing objects. The suggested algorithm is applicable in the case of the utilization of automated testing systems based on six DOF robotic manipulators and takes into account all the features conditioned by such equipment application. Performance of the suggested algorithm was tested experimentally

Электрооборудование и электропривод механизма подъема бурового станка

Цель работы - разработка и исследование двухзонного электропривода подъемной лебедки буровой установки. В работе выбраны элементы силовой цепи, определены оптимальные параметры настройки регуляторов системы, рассчитаны статические и динамические характеристики, определены качественные показатели. В результате исследования установлено, что разработанная система соответствует технологическим и техническим требованиям.The purpose of the work is to develop and research a two-zone electric drive of the lifting winch of the drilling rig. In the operation, elements of the power circuit are selected, optimal parameters of system regulators are determined, static and dynamic characteristics are calculated, qualitative indicators are determined. As a result of the study, it was found that the developed system meets the technological and technical requirements