Impact of lunar oxygen production on direct manned Mars missions

A manned Mars program made up of six missions is evaluated to determine the impact of using lunar liquid oxygen (LOX) as a propellant. Two departure and return nodes, low Earth orbit and low lunar orbit, are considered, as well as two return vehicle configurations, a full 70,000-kg vehicle and a 6800-kg capsule. The cost of lunar LOX delivered to orbit is expressed as a ratio of Earth launch cost

Letter to Alliance for Headache Disorders Advocacy

Several years ago the Centers for Medicare and Medicare Services (CMS) decided it would not pay for oxygen for the treatment of cluster headache. This is a serious hardship for many people with cluster headache. The American Headache Society and the Alliance for Headache Disorders Advocacy appealed to CMS to reverse this decision but they refused. In February, we went to Congress, asking them to encourage CMS to reconsider this appeal. As a result of these efforts, Nebraska Senator Johanns and Delaware Senator Coons are circulating a letter for all Senators to sign urging CMS to re-evaluate this situation. To have the best chance of success, we need to have as many Senators as possible sign the letter

The effects of greater occipital nerve block and trigger point injection on brush allodynia and pain in migraine

Objective: To evaluate the effect of GONB, with or without trigger point injection (TPI), on dynamical mechanical (brush) allodynia (BA) and on head pain in migraine. Background: Patients with migraine often have cutaneous allodynia, which is related to sensitization of central pain neurons. Greater occipital nerve block (GONB) is an effective treatment for migraine headache, however its effect on cutaneous allodynia in migraine is unknown. Methods: We studied patients with migraine and BA who were treated with GONB with or without TPI. Demographic data, migraine history and headache features were documented. Allodynia was evaluated using a structured questionnaire and by applying a 4x4-inch gauze pad to skin areas in the trigeminal and cervical dermatomes. Degree of allodynia (the allodynia score) was measured on a 100 mm visual analog scale (VAS) before treatment and 10 and 20 minutes thereafter. Headache levels were assessed using an 11-point verbal scale. Allodynia scores, as well as headache levels, before and after treatment were compared. Results: Nineteen patients were studied. Mean age was 43.6 ± 11.8 years. Twenty minutes after treatment, headache was reduced in 17 patients (89.5%) and did not change in two (10.5%). The average headache level was 6.53 before treatment and 3.47 twenty minutes after it. The average allodynia score decreased after 20 minutes in all patients. Average allodynia score per site was reduced by 18.69 mm and 13.74 mm in the trigeminal and cervical areas, respectively. There was a positive correlation between allodynia index, obtained through the questionnaire, and allodynia score, obtained by examination. Conclusion: GONB, with or without TPI, reduced both head pain and brush allodynia in this migraine patient group

Dynamic mechanical (brush) allodynia in cluster headache

Cutaneous allodynia is the perception of pain when a non-noxious stimulus is applied to normal skin. It has been described in patients with migraine. Cutaneous allodynia is caused by sensitization of central nervous system neurons that receive convergent sensory input from both skin and intracranial structures. This phenomenon has not been previously described in patients with cluster headache. Although migraine and cluster headache (CH) may share some clinical features, the pathogenesis of these two primary headaches is different. The aim of this study was to examine the occurrence of dynamic mechanical (brush) allodynia (BA) in patients with CH

The Nusselt numbers of horizontal convection

We consider the problem of horizontal convection in which non-uniform buoyancy, $b_{\rm s}(x,y)$, is imposed on the top surface of a container and all other surfaces are insulating. Horizontal convection produces a net horizontal flux of buoyancy, $\mathbf{J}$, defined by vertically and temporally averaging the interior horizontal flux of buoyancy. We show that $\overline{\mathbf{J}\cdot\mathbf{\nabla}b_{\rm s}}=-\kappa\langle|\boldsymbol{\nabla}b|^2\rangle$; overbar denotes a space-time average over the top surface, angle brackets denote a volume-time average and $\kappa$ is the molecular diffusivity of buoyancy $b$. This connection between $\mathbf{J}$ and $\kappa\langle|\boldsymbol{\nabla}b|^2\rangle$ justifies the definition of the horizontal-convective Nusselt number, $Nu$, as the ratio of $\kappa \langle|\boldsymbol{\nabla}b|^2\rangle$ to the corresponding quantity produced by molecular diffusion alone. We discuss the advantages of this definition of $Nu$ over other definitions of horizontal-convective Nusselt number currently in use. We investigate transient effects and show that $\kappa \langle|\boldsymbol{\nabla}b|^2\rangle$ equilibrates more rapidly than other global averages, such as the domain averaged kinetic energy and bottom buoyancy. We show that $\kappa\langle|\boldsymbol{\nabla} b|^2\rangle$ is essentially the volume-averaged rate of Boussinesq entropy production within the enclosure. In statistical steady state, the interior entropy production is balanced by a flux of entropy through the top surface. This leads to an equivalent "surface Nusselt number", defined as the surface average of vertical buoyancy flux through the top surface times the imposed surface buoyancy $b_{\rm s}(x,y)$. In experiments it is likely easier to evaluate the surface entropy flux, rather than the volume integral of $|\mathbf{\nabla}b|^2$ demanded by $\kappa\langle|\mathbf{\nabla}b|^2\rangle$.Comment: 16 pages, 7 figure

A theory of the wind-driven circulation II. Gyres with western boundary layers

The quasigeostrophic, wind-driven circulation theory given by Rhines and Young (1982b) is extended in two directions. First, we consider forcing patterns which are not contrived so as to close without a western boundary layer. The resulting barotropic circulation pattern (see Fig. 1) has the well known east-west asymmetry produced by the β-effect...

A theory of wind-driven circulation. I. Mid-ocean gyres

A theory of the wind-driven ocean circulation is presented in which the key feature is strong deformation of interior density layers and consequent production of closed geostrophic-contours by the flow itself. The constraint imposed on the subsurface flow by the imposition of a no flux condition where a geostrophic contour strikes a coastal boundary is thus removed. Within regions where the geostrophic contours close the potential vorticity is uniform...

Referred cutaneous allodynia in a migraine patient without simultaneous headache

Cutaneous allodynia is defined as the perception of pain when a non-noxious stimulus is applied to normal skin. This phenomenon has been demonstrated in migraine patients during an acute attack. It is thought to result from central sensitization of neurons in the trigemino-vascular system and may spread to areas beyond that of the referred head pain. In a recent study, migraine patients demonstrated increased temporal summation to painful mechanical stimuli in their referred head pain area between attacks. This suggests that changes in physiologic properties of nociceptive neurons may occur in migraine patients between attacks. We describe a migraine patient with interictal cutaneous allodynia contralateral to her usual head pain

Occipital nerve block rapidly eliminates allodynia far from the site of headache: A case report

Seventy to 80% of persons with migraine develop allodynia during the course of a severe attack. During a migraine attack, allodynia spreads topographically to extratrigeminal territory. Dynamic mechanical allodynia, otherwise known as brush allodynia (BA), is a subtype of allodynia that is easily tested. Ashkenazi & Young recently reported on the immediate benefits of greater occipital nerve (GON) block on brush allodynia and pain in migraine and in cluster headache. In these studies, testing was performed at fixed sites in the trigeminal and cervical distributions. Allodynia in thoracic dermatomes was not studied