The Emirates Mars Mission.

The Emirates Mars Mission (EMM) was launched to Mars in the summer of 2020, and is the first interplanetary spacecraft mission undertaken by the United Arab Emirates (UAE). The mission has multiple programmatic and scientific objectives, including the return of scientifically useful information about Mars. Three science instruments on the mission's Hope Probe will make global remote sensing measurements of the Martian atmosphere from a large low-inclination orbit that will advance our understanding of atmospheric variability on daily and seasonal timescales, as well as vertical atmospheric transport and escape. The mission was conceived and developed rapidly starting in 2014, and had aggressive schedule and cost constraints that drove the design and implementation of a new spacecraft bus. A team of Emirati and American engineers worked across two continents to complete a fully functional and tested spacecraft and bring it to the launchpad in the middle of a global pandemic. EMM is being operated from the UAE and the United States (U.S.), and will make its data freely available.

The evolution of the school nurse practitioner: past, present, and future.

The role of school nurse practitioner (SNP) evolved in response to the growing need of the school-age population for health care and the school as a setting for providing primary health services. SNPs have broadened the role of the traditional school nurse while extending advanced nursing into the arena of primary health services.

Nitrate Effects on Nodule Oxygen Permeability and Leghemoglobin (Nodule Oximetry and Computer Modeling).

Two current hypotheses to explain nitrate inhibition of nodule function both involve decreased O2 supply for respiration in support of N2 fixation. This decrease could result from either (a) decreased O2 permeability (PO) of the nodule cortex, or (b) conversion of leghemoglobin (Lb) to an inactive, nitrosyl form. These hypotheses were tested using alfalfa (Medicago sativa L. cv Weevlchek) and birdsfoot trefoil (Lotus corniculatus L. cv Fergus) plants grown in growth pouches under controlled conditions. Nodulated roots were exposed to 10 mM KNO3 or KCI. Fractional oxygenation of Lb under air (FOLair), relative concentration of functional Lb, apparent PO, and O2-saturated central zone respiration rate were all monitored by nodule oximetry. Apparent PO and FOLair in nitrate-treated nodules decreased to <50% of values for KCI controls within 24 h, but there was no decrease in functional Lb concentration during the first 72 h. In nitrate-treated alfalfa, but not in birdsfoot trefoil, FOLair, apparent PO, and O2-saturated central zone respiration rate decreased during each light period and recovered somewhat during the subsequent dark period. This species difference could be explained by greater reliance on photoreduction of nitrate in alfalfa than in birdsfoot trefoil. Computer simulations extended the experimental results, showing that previously reported decreases in apparent PO of Glycine max nodules with nitrate exposure cannot be explained by hypothetical decreases in the concentration or O2 affinity of Lb.

Carpal tunnel syndrome: surgical and nonsurgical treatment.

A retrospective study was performed to evaluate treatment for carpal tunnel syndrome. Two hundred sixty-five patients were treated over a 4 1/2-year period. Only patients in whom studies showed abnormal nerve conduction (a median nerve sensory latency greater than 3.6 msec or a median distal motor latency greater than 4.3 msec) were included in the evaluation. Nonsurgical treatment consisted of patient education, wrist splinting, B vitamins, nonsteroidal anti-inflammatory medication, steroid injections, and job change or modification when possible. A follow-up history, physical examination, and repeat nerve conduction studies were performed at 3- to 9-month intervals, depending on the severity of symptoms and the degree of abnormal latencies. Surgery was performed on 77 patients and 95 hands. The remaining 188 patients were treated nonsurgically. Both surgically and nonsurgically treated patients considered the results to be satisfactory.

Indications for surgery in work-related compression neuropathies of the upper extremity.

Symptoms caused by compression neuropathies are subjective and often difficult to quantify. The author describes sites of compression involving the median, ulnar, and radial nerves and their branches, and emphasizes that surgical procedures should be performed only when objective evidence of an abnormality is present and the chance for surgical correction is high.

High-pressure injection injuries.

The use of high-pressure injection devices has resulted in an unusual type of injury to the upper extremity. Though on initial inspection the wound often appears benign, tissue damage beneath the skin is extensive. These injuries are surgical emergencies that demand prompt evaluation and treatment.

Formation of ionic channels in black lipid membranes by succinic derivatives of gramicidin A.

Different succinyl derivatives of Gramicidin A were synthesized and their activity was investigated with different methods on lipid bilayer membranes. The succinyl derivatives of Gramicidin A can be classified as three different types, the O-succinyl derivative, the N-succinyl derivative and the N-O-succinyl derivative of Gramicidin A. An O-pyromellityl-N-succinyl gramicidin was synthesized which can be attributed to the latter class. It was found that O-succinyl gramicidin behaves like the unmodified Gramicidin A despite a charge effect on single-channel conductance, arising from the negative charge of the succinic residue at the mouth of the channel. The activity of N-succinyl and N-O-succinyl gramacidin and of O-pyromellityl-N-succinyl-gramicidin depends strongly on the pH of the electrolyte solution. It is demonstrated that at low pH (less than or equal to 5) the N-succinyl derivatives show high activity, whereas at high pH (greater than or equal to 7) the activity is sharply reduced or disappears totally. From these experiments it can be concluded that, for the formation of a dimeric gramicidin channel, the hydrogen of the formyl group can be replaced by a protonated carboxylic group of a succinic residue. Further results, obtained by measurement of the single-channel conductance and of the reaction rate constants for the channel formation, are discussed in terms of the structural basis of the single stranded model for the gramicidin channel. On this basis the double stranded helix can be excluded and an interesting head-to-head single stranded beta(pi L.D.) helical channel is described which contains carboxyl groups at the head-to-head junction.