A Theory of Cheap Control in Embodied Systems

We present a framework for designing cheap control architectures of embodied agents. Our derivation is guided by the classical problem of universal approximation, whereby we explore the possibility of exploiting the agent’s embodiment for a new and more efficient universal approximation of behaviors generated by sensorimotor control. This embodied universal approximation is compared with the classical non-embodied universal approximation. To exemplify our approach, we present a detailed quantitative case study for policy models defined in terms of conditional restricted Boltzmann machines. In contrast to non-embodied universal approximation, which requires an exponential number of parameters, in the embodied setting we are able to generate all possible behaviors with a drastically smaller model, thus obtaining cheap universal approximation. We test and corroborate the theory experimentally with a six-legged walking machine. The experiments indicate that the controller complexity predicted by our theory is close to the minimal sufficient value, which means that the theory has direct practical implications.     

A Cooling Modification to an Apparatus for Phage Typing of Staphylococcus aureus

Difficulty is experienced through overheating of the Tarr apparatus for phage typing. The provision of a cooling coil which overcomes this difficulty is described.     

Gastric Cooling for Massive Upper Gastrointestinal Bleeding

The treatment of massive upper gastrointestinal hemorrhage by gastric hypothermia was studied clinically in 23 patients: five with peptic ulcer, six with multiple gastric erosions, nine with portal hypertension and varices, and three with coagulation defects. Hemorrhage was controlled in 13 of the patients. The high mortality (14 out of 23 patients) was attributed to the severity of the bleeding and to the underlying disease, particularly in patients with liver failure. This form of treatment is a useful method of treating selected patients with upper gastrointestinal hemorrhage.     

Effective Pollination Period and Nature of Pollen-collecting Apparatus in the Gymnosperm, Larix leptolepis

In controlled environment, the effective pollination periodin Larix leptolepis is characterized by its brevity, lastingfor less than 1 d. It is associated with the opening of thepapillae of the pollen collecting apparatus which possess surfaceesterase activity, a condition that has its parallel in thesurface pellicle of angiosperm stigmas. Larix leptolepis, ovule receptivity, morphometric analysis, pollination, stigma surface, esterase activity     

A New Instrument for Control of Hemorrhage by Aortic Compression: A Preliminary Report

After laparotomy, immediate compression of the aorta with the heel of the hand just above the bifurcation of the common iliac arteries is a quick and effective way of controlling catastrophic pelvic hemorrhage. This maneuver, which can be maintained for several hours without any harmful sequelae, enables the surgeon to remove the blood from the peritoneal cavity and take definitive steps to stop the bleeding, and the loss of administered blood is halted. An instrument for aortic compression is described which is easily applied to the aorta; it is controlled by a handle outside the abdomen and does not obstruct the operative field. It has been found to be valuable, not only in the control of serious pelvic hemorrhage, but also in pelvic surgery where considerable blood loss is anticipated.     

A Direct Silver Method for the Golgi Apparatus

Direct immersion of fresh tissue in a solution of silver in formalin at pH 4, followed by development in hydroquinone-formalin, results in consistent silvering of the Golgi apparatus. The time required depends on the penetration of the tissue, two hours for each step being adequate for routine purposes. Proper general fixation of the tissue is enhanced by returning it to a fixative for the customary periods of time. A weak solution of iron alum is suggested as a convenient method for reducing the intensity of the silver image in sections, when that is desired. Replacing the silver image with gold allows it to survive more drastic subsequent treatment, such as periodic acid oxidation.     

A New Apparatus for Control of Temperature and Humidity in Leaf and Small Plant Chambers

A new electronic system for effecting feedback control of temperaturefrom 3 to 50 °C and humidity from approximately 15 to 99per cent is described. This system uses thermistor sensors tocontrol, through electronic control units, the temperature ofwater baths which determined the temperature and humidity ofthe airstream passing through leaf or small plant chambers.The control has been found to be precise, and the temperatureand humidity can each be reset from a separate single controlknob.     

A Modified Freezing-Drying Apparatus for Tissues

The preparation of tissues by the freezing-drying technic is preferred for many histochemical studies because of the rapid fixation, avoidance of deleterious action of chemical fixation and extraction by aqueous and lipid solvents in fixation, dehydration and clearing; to facilitate this procedure a freezing-drying apparatus has been constructed which permits cutting of sections within five hours after the fresh tissue is obtained. Liquid nitrogen provides a most efficient moisture trap and in conjunction with a heating element provides any desired temperature down to — 80°C. during tissue drying. Paraffin infiltration is started without disassembling the equipment and completed in a few minutes. Most stains and histochemical reactions for enzyme and other substances can be applied directly to sections of frozen-dried tissue cut from the same blocks.     

VEGF, MVD 在胃癌预后及上消化道出血风险的研究进展

胃癌是危害人类健康的常见恶性肿瘤,也是上消化道出血常见的病因之一。其发生发展是多因素、多基因改变参与的长期、协同的病理过程。血管生成(angiogenesis)是这一发展过程中的关键步骤,血管内皮生长因子(vascular endothelial growth factor,VEGF)和微血管密度(micro vessel density,MVD)作为调控血管生成的主要因子和微血管的主要评价指标,在胃癌患者预后、临床病理因素中的作用被广泛研究。上消化道出血(upper gastrointestinal hemorrhage)是胃癌患者的常见临床症状威胁和影响患者的生存质量。新近有研究者提出,VEGF及MVD与胃癌患者的上消化道出血风险正相关,本文就相关研究进展进行介绍。     

A Simple Automatic Apparatus for the Concentration of Macromolecular Solutions

An apparatus for the concentration of macromolecular solutions is described in detail. It features automatic volume control and is inexpensive and simple to fabricate. The basis for the device is negative pressure dialysis.     

A New Apparatus for Preparative Gel Electrophoresis

Syntheses of two carbonyl derivatives of hydantocidin 1, a potent, naturally occurring herbicide, and their herbicidal activity are described. Spiroimidazolidinone 2, the descarbonyl compound at C9, was prepared by employing reductive demethylsulfurization with tri-n-butyltin hydride as the key step. Another derivative, spiroimidazolinone 10, was obtained from α-azidoamide 8 and benzyl isocyanate via the aza-Wittig reaction. 2 had lost almost all herbicidal activity, whereas 10 retained herbicidal activity against such dicotyledonous weeds as ragweed and cocklebur, but lost activity against monocotyledonous weeds. These results imply the possibility that proper modification of the carbonyl group at C7 of the parent compound would afford hydantocidin analogues possessing crop selectivity.     

Photorespiration is More Effective than the Mehler Reaction in Protecting the Photosynthetic Apparatus against Photoinhibition

I. Isolated intact chloroplasts: Photosystem II, but not photosystem I, of the electron transport chain is rapidly photoinactivated even by very low intensities of red light when no large proton gradient can be formed and the electron transport chain becomes over-reduced in the absence of oxygen and other reducable substrates. Electron acceptors including oxygen provide protection against photoinactivation. Nevertheless, photosystem II is rapidly, and photosystem I more slowly, photoinactivated by high intensities of red light when oxygen is the only electron acceptor available. Increased damage is observed at increased oxygen concentrations although catalase is added to destroy H₂O₂ formed during oxygen reduction in the Mehler reaction. Photoinactivation can be decreased, but not prevented by ascorbate which reduces hydrogen peroxide inside the chloroplasts and increases coupled electron flow. II. Leaves: Simple measurements of chlorophyll fluorescence permit assessment of damage to photosystem II after exposure of leaves to high intensity illumination. In contrast to isolated chloroplasts, chloroplasts suffer more damage in situ at reduced than at elevated oxygen concentrations. The difference in the responses is due to photorespiration which is active in leaves, but not in isolated chloroplasts. After photosynthesis and photorespiration are inhibited by feeding glyceraldehyde to leaves, photoinactivation is markedly increased, although oxygen reduction in the Mehler reaction is not affected by glyceraldehyde. In the presence of reduced CO₂ levels, photorespiratory reactions, but not the Mehler reaction, can prevent the overreduction of the electron transport chain. Over-reduction indicates ineffective control of photosystem II activity. Effective control is needed for protection of the electron transport chain against photoinactivation. It is suggested to be made possible by coupled cyclic electron flow around photosystem I which is facilitated by the redox poising resulting from the interplay between photorespiratory carbohydrate oxidation and the refixation of evolved CO₂.     

A Mobile Apparatus for Measuring Leaf Photosynthesis in the Field

An apparatus is described that has been designed to measurethe gas exchange of individual cereal leaves in the field, usinginfrared gas analysis. Measurements on leaves of winter wheatshowed that there was true saturation of net photosynthesisat high irradiances but as irradiance decreased there was aproportional decrease in net photosynthesis. Measurements madeon wheat plants grown in a controlled environment, for comparison,showed the photosynthesis–light response curve to be betterfitted by a rectangular hyperbola. This dissimilar responseof photosynthesis to irradiancc for plants grown in controlledenvironments indicates the possible problems of extrapolationfrom the laboratory to the field.     

A Stereotaxic Apparatus for Injection of the Trigeminal Root and Ganglion

A stereotaxic apparatus was designed which would enable a needle to be passed easily through the foramen ovale with accuracy and with a minimum of radiological aid by one relatively unskilled in injection of the trigeminal ganglion. Successful penetration of the foramen was achieved in 39 of 46 injections on cadavers and in six injections on five patients. The substance injected was 5% phenol in glycerin. In one patient alcohol was used. The anesthesia produced was satisfactory in all except one patient. We feel that this apparatus will enable the trigeminal ganglion to be injected relatively easily in all patients except those with unusually shaped skulls.