when neurons start shouting “go to bed NOW!”

DrosophilaA study carried out in fruit flies (2–4 millimetres long Drosophila) by some clever researchers at Oxford University’s Centre for Neural Circuits and Behaviour (CNCB) has recently pointed out a sleep mechanism which is meant to be relevant to humans.

Human sleep regulation is supposed to be managed by two mechanisms:

  • a first one, called body clock, related to the external environment. For instance, thanks to it, humans and others animals get used to the 24-hour day-night cycle and regularly alternate sleep-wake cycles;
  • a second one, related to the body homeostasis, which monitors the internal environment and basically makes us feel spleepy when we’ve been awake for too long. Such mechanism works like a sleep switch and is separate from external factors.

i-am-not-sleepy-and-i-will-not-go-to-bedProfessor Gero Miesenböck, in whose laboratory the research was performed, says that “what makes us go to sleep at night is probably a combination of the two mechanisms. The body clock says it’s the right time, and the sleep switch has built up pressure during a long waking day“. Now, the researchers found (in the tiny Drosophilae’s brains) a group of sleep-promoting neurons that work as a thermostat which automatically turns on when it’s too cold: such neurons are active when the body is tired and needs to sleep, while they don’t fire under fully rested conditions. Doctor Jeffrey Donlea, specialised in testing new scientific ideas in flies at the CNCB, says that “there is a similar group of neurons in a region of the human brain. These neurons are also electrically active during sleep and, like the flies’ cells, are the targets of general anesthetics that put us to sleep“. Therefore, a similar molecular mechanism is likely to operate in humans too. In order to specifically solicit the sleep switch, certain genes were silenced in a group of flies’ brains: a key molecular component was disabled in order to keep the sleep-inducing neurons permanently switched off. The mutant flies were found not to be able to catch up on lost sleep after being kept awake all night. Such behaviour was assumed to be caused by the disabled molecular component, thus identified as a cause of sleep disorder.

Upon further investigation, this study might help the identification of new targets to improve treatments for sleep disorders like insomnia. In the long term, this research work may provide precious hints to find the answer to the big question: “What is the purpose of sleep?“. For the moment, what is sure is that the greatest enemy of sleep is the Internet.

gotobed

main sources: this and that

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how to select the right screw?

source: this website

Hobbyists, prototype builders and engineers may have to deal with tough choices: which screw size should I choose? how tight should it be, and which load can it bear? what’s the best thread size for my application? Luckily, this website provides a set of basic rules and definitions, a sort of handy guide with useful terminology and hints about the choice of screws, bolts, nuts etc.

wood_screwheads

bolt_tension_1For instance, Wood, Sheet Metal and Drywall screws differ from Machine ones; the screw head type depends on the application; the screw thread could be coarse or fine, according to the accuracy requirement. Sizing a screw for a given load would seem to be a simple matter, but a set of basic rules exist and it is reasonable to abide as much as possible by them. Did you know that, in most situations, the ground acts as a spring? I did not… Another nice thing is the guide for picking a screw or bolt for a given load, as well as the computation of how much thread engagement is needed. Material choice, the use of washers and other locking methods are also discussed. No doubt, this webpage is worth a visit! 🙂

 

el limite de la ciencia? su costo…

! first post ever in spanish !

parcialmente tomado de este artículo

Hugh Herr, director del grupo de biomecánica del Media Lab (en el Massachussets Institute of Technology), aseguró durante su charla en  la reunión anual que la plataforma TED dedica a la innovación que “la electromecánica integrada o implantada en el cuerpo está empezando a derribar la barrera entre capacidad y discapacidad, entre las limitaciones del ser humano y su potencial”. Para encontrar un ejemplo solo le hizo falta señalarse a sí mismo porque, además de diseñar miembros biónicos en los laboratorios del MIT, los lleva puestos.

herr

Su idea es que el cuerpo humano nunca se rompe, lo único que falla es la tecnología disponible: “las partes artificiales de mi cuerpo son maleables, pueden tomar cualquier forma, cualquier función, para crear estructuras que podrían incluso ir más allá de las capacidades biológicas”. Con ayuda de un nutrido equipo de ingenieros y científicos, logró fabricarse unos miembros especiales que no solo le han permitido volver a practicar el deporte que le apasiona (escalada), sino que, según él, lo hace incluso mejor que antes.

Como Hugh, cerca de un millar de pacientes utiliza la prótesis biónica BiOM, desarrollada en el MIT y comercializada desde 2011. Considerando que este miembro artificial cuesta màs o menos 50000 $ (si, 40000 $ más que una prótesis estándar), quién se puede permitir esa compra? Ademàs, la mayoría de las compañías aseguradoras no cubre BiOM, que entonces se vuelve aún más caro… Aunque los abogados traten de demostrar tener una prótesis disminuye a largo plazo los costos de la asistencia sanitaria, asegurando a los amputados un estilo de vida más activo y, por consiguiente, un menor riesgo de problemas como la obesidad, la diabetes y la depresión. Entonces, quiénes son los usuarios de BiOM? Parece que se trata de veteranos, que pueden aprovechar los beneficios del seguro social del Departamento de Defensa (que financió la investigación de Herr y ayudó a la comercialización de BiOM)… beneficios exclusivos en favor de una parte de la sociedad. Entonces, de momento, BiOM es realmente “una tecnología innovadora que ayuda a alcanzar sus propias metas y mejorar su movilidad“, pero severamente limitada por su costo.