Ways that designers and fabricators can help each other

We show that, when designers and fabricators understand each other's art, there are ways to combine their techniques to achieve the best results with the minimum difficulty. We share some problems that we have encountered, and sometimes caused ourselves, in hopes of helping the reader avoid the same pitfalls.

Weekly Versus Monthly Testosterone Administration On Fast and Slow Skeletal Muscle Fibers in Older Adult Males

Context: In older adults, loss of mobility due to sarcopenia is exacerbated in men with low serum T. T replacement therapy is known to increase muscle mass and strength, but the effect of weekly (WK) vs monthly (MO) administration on specific fiber types is unknown. Objective: To determine the efficacy of WK vs MO T replacement on the size and functional capacity of individual fast and slow skeletal muscle fiber types. Design, Setting, and Patients: Subjects were randomized into a 5-month, double-blind, placebo-controlled trial. All subjects (ages, 61–71 y) were community-dwelling men who had T levels \u3c 500 ng/dL. Intervention: Subjects were dosed weekly for 5 months, receiving continuous T (WK, n = 5; 100 mg T enanthate, im injection), monthly cycled T (MO, n = 7; alternating months of T and placebo), or placebo (n = 7). Muscle biopsies of the vastus lateralis were obtained before and after treatment. Main Outcome Measures: Main outcomes for individual slow and fast fibers included fiber diameter, peak force (P0), rate of tension development, maximal shortening velocity, peak power, and Ca2+ sensitivity. Results: Both treatments increased fiber diameter and peak power, with WK treatment 5-fold more effective than MO in increasing type I fiber P0. WK effects on fiber diameter and force were 1.5-fold higher in slow fibers compared to fast fibers. In fast type II fibers, diameter and P0 increased similarly between treatments. The increased power was entirely due to increased fiber size and force. Conclusions: In conclusion, T replacement effects were fiber-type dependent, restricted to increases in cell size, P0, and peak power, and dependent on the paradigm selected (WK vs MO)

Chain formation can enhance the vertical migration of phytoplankton through turbulence

Many species of motile phytoplankton can actively form long multicellular chains by remaining attached to one another after cell division. While chains swim more rapidly than single cells of the same species, chain formation also dramatically reduces phytoplankton’s ability to maintain their bearing. This suggests that turbulence, which acts to randomize swimming direction, could sharply attenuate a chain’s ability to migrate between well-lit surface waters during the day and deeper nutrient rich waters at night. Here we use numerical models to investigate how chain formation affects the migration of phytoplankton through a turbulent water column. Unexpectedly, we find that the elongated shape of chains helps them travel through weak to moderate turbulence much more effectively than single cells and isolate the physical processes that confer chains this ability. Our findings provide a new mechanistic understanding of how turbulence can select for phytoplankton with elongated morphologies and may help explain why turbulence triggers chain formation

Anomalous relaxation kinetics of biological lattice-ligand binding models

We discuss theoretical models for the cooperative binding dynamics of ligands to substrates, such as dimeric motor proteins to microtubules or more extended macromolecules like tropomyosin to actin filaments. We study the effects of steric constraints, size of ligands, binding rates and interaction between neighboring proteins on the binding dynamics and binding stoichiometry. Starting from an empty lattice the binding dynamics goes, quite generally, through several stages. The first stage represents fast initial binding closely resembling the physics of random sequential adsorption processes. Typically this initial process leaves the system in a metastable locked state with many small gaps between blocks of bound molecules. In a second stage the gaps annihilate slowly as the ligands detach and reattach. This results in an algebraic decay of the gap concentration and interesting scaling behavior. Upon identifying the gaps with particles we show that the dynamics in this regime can be explained by mapping it onto various reaction-diffusion models. The final approach to equilibrium shows some interesting dynamic scaling properties. We also discuss the effect of cooperativity on the equilibrium stoichiometry, and their consequences for the interpretation of biochemical and image reconstruction results.Comment: REVTeX, 20 pages, 17 figures; review, to appear in Chemical Physics; v2: minor correction

Congenital absence of the external carotid artery: Atherosclerosis without a bifurcation

AbstractWe report the case of a patient with congenital absence of the external carotid artery in whom we performed a carotid endarterectomy. The radiographic features and operative findings are presented. Four similar cases previously reported in the literature are reviewed. A comment on the pathophysiology of atherosclerosis at the carotid bulb in the absence of a bifurcation and a brief discussion on the possible embryologic explanation of this anomaly are discussed. (J Vasc Surg 2002;35:573-5.

Antenna Characterization for the Wideband Instrument for Snow Measurements (WISM)

Experimental characterization of the antenna for the Wideband Instrument for Snow Measurement (WISM) under development for the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP), is discussed. A current sheet antenna, consisting of a small, 6x6 element, dual-linear polarized array with integrated beamformer, feeds an offset parabolic reflector, enabling WISM operation over an 8 to 40 GHz frequency band. An overview of the test program implemented for both the feed and the reflector antenna is given along with select results for specific frequencies utilized by the radar and radiometric sensors of the WISM

Antenna Characterization for the Wideband Instrument for Snow Measurements

Experimental characterization of the antenna for the Wideband Instrument for Snow Measurements (WISM) under development for the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP), is discussed. A current sheet antenna, consisting of a small, 6x6 element, dual-linear polarized array with integrated beamformer, feeds an offset parabolic reflector, enabling WISM operation over an 8 to 40 GHz frequency band. An overview of the test program implemented for both the feed and the reflector antenna is given along with select results for specific frequencies utilized by the radar and radiometric sensors of the WISM

Design of an 8-40 GHz Antenna for the Wideband Instrument for Snow Measurements (WISM)

This poster describes the implementation of a 6x6 element, dual linear polarized array with beamformer that operates from about 8-40 GHz. It is implemented using a relatively new multi-layer microfabrication process. The beamformer includes baluns that feed dual-polarized differential antenna elements and reactive splitters that cover the full frequency range of operation. This fixed beam array (FBA) serves as the feed for a multi-band instrument designed to measure snow water equivalent (SWE) from an airborne platform known as the Wideband Instrument for Snow Measurements (WISM)

NCS-1 Inhibits insulin stimulated GLUT4 translocation in 3T3L1 adipocytes through a phosphatidylinositol 4-kinase dependent pathway

Expression of NCS-1 (neuronal calcium sensor-1, also termed frequenin) in 3T3L1 adipocytes strongly inhibited insulin-stimulated translocation of GLUT4 and insulin-responsive aminopeptidase. The effect of NCS-1 was specific for GLUT4 and the insulin-responsive aminopeptidase translocation as there was no effect on the trafficking of the cation-independent mannose 6-phosphate receptor or the GLUT1 glucose transporter isoform. Moreover, NCS-1 showed partial colocalization with GLUT4-EGFP in the perinuclear region. The inhibitory action of NCS-1 was independent of calcium sequestration since neither treatment with ionomycin nor endothelin-1, both of which elevated the intracellular calcium concentration, restored insulin-stimulated GLUT4 translocation. Furthermore, NCS-1 did not alter the insulin-stimulated protein kinase B (PKB/Akt) phosphorylation or the recruitment of Cbl to the plasma membrane. In contrast, expression of the NCS-1 effector phosphatidylinositol 4-kinase (PI 4-kinase) inhibited insulin-stimulated GLUT4 translocation, whereas co-transfection with an inactive PI 4-kinase mutant prevented the NCS-1-induced inhibition. These data demonstrate that PI 4-kinase functions to negatively regulate GLUT4 translocation through its interaction with NCS-1

Antagonists of retinoic acid receptors (RARs) are potent growth inhibitors of prostate carcinoma cells

Novel synthetic antagonists of retinoic acid receptors (RARs) have been developed. To avoid interference by serum retinoids when testing these compounds, we established serum-free grown sub-lines (>3 years) of the prostate carcinoma lines LNCaP, PC3 and DU145. A high affinity pan-RAR antagonist (AGN194310, Kd for binding to RARs = 2–5 nM) inhibited colony formation (by 50%) by all three lines at 16–34 nM, and led to a transient accumulation of flask-cultured cells in G1 followed by apoptosis. AGN194310 is 12–22 fold more potent than all-trans retinoic acid (ATRA) against cell lines and also more potent in inhibiting the growth of primary prostate carcinoma cells. PC3 and DU145 cells do not express RARβ, and an antagonist with predominant activity at RARβ and RARγ (AGN194431) inhibited colony formation at concentrations (∼100 nM) commensurate with a Kd value of 70 nM at RARγ. An RARα antagonist (AGN194301) was less potent (IC50 ∼200 nM), but was more active than specific agonists of RARα and of βγ. A component(s) of serum and of LNCaP-conditioned medium diminishes the activity of antagonists: this factor is not the most likely candidates IGF-1 and EGF. In vitro studies of RAR antagonists together with data from RAR-null mice lead to the hypothesis that RARγ-regulated gene transcription is necessary for the survival and maintenance of prostate epithelium. The increased potencies of RAR antagonists, as compared with agonists, suggest that antagonists may be useful in the treatment of prostate carcinoma. © 2001 Cancer Research Campaign http://www.bjcancer.co