Deposits from giant floods in Gale crater and their implications for the climate of early Mars.

This study reports in-situ sedimentologic evidence of giant floods in Gale crater, Mars, during the Noachian Period. Features indicative of floods are a series of symmetrical, 10 m-high gravel ridges that occur in the Hummocky Plains Unit (HPU). Their regular spacing, internal sedimentary structures, and bedload transport of fragments as large as 20 cm suggest that these ridges are antidunes: a type of sedimentary structure that forms under very strong flows. Their 150 m wavelength indicates that the north-flowing water that deposited them was at least 24 m deep and had a minimum velocity of 10 m/s. Floods waned rapidly, eroding antidune crests, and re-deposited removed sediments as patches on the up-flow limbs and trough areas between these ridges forming the Striated Unit (SU). Each patch of the SU is 50-200 m wide and long and consists of 5-10 m of south-dipping layers. The strike and dip of the SU layers mimic the attitude of the flank of the antidune on which they were deposited. The most likely mechanism that generated flood waters of this magnitude on a planet whose present-day average temperature is - 60 °C was the sudden heat produced by a large impact. The event vaporized frozen reservoirs of water and injected large amounts of CO2 and CH4 from their solid phases into the atmosphere. It temporarily interrupted a cold and dry climate and generated a warm and wet period. Torrential rainfall occurred planetwide some of which entered Gale crater and combined with water roaring down from Mt. Sharp to cause gigantic flash floods that deposited the SU and the HPU on Aeolis Palus. The warm and wet climate persisted even after the flooding ended, but its duration cannot be determined by our study.

Speech impairment in primary hypothyroidism.

OBJECTIVE: Thyroid hormone deficiency may affect human speech and voice. The aim of this study was to evaluate speech variables in patients with hypothyroidism. DESIGN: A case control study. PATIENTS: One hundred and twenty patients, 106 women and 14 men with symptoms and signs of thyroid failure; the diagnosis was confirmed by serum T4<4.5 µg/dl and serum TSH>10 mU/l. Eighty-eight normal subjects, 78 women and 10 men, age-, sex-, and smoking status- matched, served as controls. MEASUREMENTS: All symptoms and signs of hypothyroidism were recorded. Serum T4, T3, and TSH concentrations were measured. Speech parameters were analyzed by the Visipitch III system model 3900 and multidimensional voice program software and compared to a group of normal subjects with no thyroid disease. RESULTS: Mean age was 35.9±11.4 yr. Dryness in larynx and pharynx, dyspnea, and sensation of lump in the throat were reported by 53.49 and 43% of patients, respectively. Fundamental frequency, voice turbulence index, and soft phonation index were significantly different from control values. There was positive correlation between TSH concentration and variation in fundamental frequency and prevalence of voice disorders (37.2±31.2 vs 23.9±25.8 mU/l, p<0.003). CONCLUSION: Frequent speech disturbances occur in patients with primary hypothyroidism.