Response to: Some historical remarks on ipsilateral hemiparesis and the absence of decussation of the pyramidal tracts

Generation of few-cycle optical pulses in free-electron laser (FEL) oscillators has been experimentally demonstrated in FEL facilities based on normal-conducting and superconducting linear accelerators. Analytical and numerical studies have revealed that the few-cycle FEL lasing can be explained in the frame of superradiance, cooperative emission from self-bunched systems. In the present paper, we review historical remarks of superradiance FEL experiments in short-pulse FEL oscillators with emphasis on the few-cycle pulse generation and discuss the application of the few-cycle FEL pulses to the scheme of FEL-HHG, utilization of infrared FEL pulses to drive high-harmonic generation (HHG) from gas and solid targets. The FEL-HHG enables one to explore ultrafast science with attosecond ultraviolet and X-ray pulses with a MHz repetition rate, which is difficult with HHG driven by solid-state lasers. A research program has been launched to develop technologies for the FEL-HHG and to conduct a proof-of-concept experiment of FEL-HHG.

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Distal Radius Fracture Treatment Outcomes in Patients With Ipsilateral Hemiplegia or Hemiparesis

Hand ◽

10.1177/1558944721999733 ◽

2021 ◽

pp. 155894472199973

Author(s):

Nicholas Munaretto ◽

Adam Tagliero ◽

Raahil Patel ◽

Peter C. Rhee

Keyword(s):

Distal Radius Fracture ◽

Distal Radius ◽

Case Series ◽

Distal Radius Fractures ◽

Radius Fracture ◽

Functional Classification ◽

Radius Fractures ◽

Radiographic Outcomes ◽

Ipsilateral Hemiparesis

Background Little information exists to guide decision-making with regard to distal radius fractures in the setting of ipsilateral hemiparesis or hemiplegia. Methods Patients who sustained a distal radius fracture in the setting of ipsilateral hemiparesis or hemiplegia secondary to brain injury were evaluated. Investigated variables included perioperative pain, preinjury House functional classification score, length of immobilization, radiographic outcome measurements, and time to union. Results There were 15 patients with distal radius fractures with a mean age of 65.9 years. The mean clinical and radiographic follow-up was 2.8 and 2.9 years, respectively. Wrists were placed into the nonoperative group (NOG, n = 10) and operative group (OG, n = 5). Pain significantly decreased at final follow-up for both groups. Baseline House functional classification scores averaged 1.3 and 1.6 for the NOG and OG, respectively, and were maintained at final follow-up. Length of immobilization for the NOG was 46 days and OG was 37 days, P = .15. Radiographic outcomes at final follow-up in the NOG and OG, respectively, were a mean radial height of 9.3 versus. 11.6 mm, radial inclination of 18.3° versus 22.3°, 4.2° dorsal tilt versus 5.3° volar tilt, and tear drop angle of 45.6° versus 44.5°. There were no significant differences in these measurements. Time to radiographic union averaged 58 days for the NOG and 67 days for the OG, P = .42. There were no revision surgeries. Conclusions Based on this small case series, patients with distal radius fracture and ipsilateral hemiparesis or hemiplegia may have similar clinical, functional, and radiographic outcomes, regardless of nonoperative or operative treatment.

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Theory of Effective Stress in Soil and Rock and Implications for Fracturing Processes: A Review

Geosciences ◽

10.3390/geosciences11030119 ◽

2021 ◽

Vol 11 (3) ◽

pp. 119

Author(s):

Vincenzo Guerriero ◽

Stefano Mazzoli

Keyword(s):

Porous Media ◽

Effective Stress ◽

Biological Tissues ◽

Theory Of Elasticity ◽

Past Century ◽

Metal Powders ◽

Science Community ◽

Experimental Approaches ◽

Historical Remarks ◽

Open Issues

The effective stress principle (ESP) plays a basic role in geology and engineering problems as it is involved in fundamental issues concerning strain and failure of rock and soil, as well as of other porous materials such as concrete, metal powders, biological tissues, etc. Although since its introduction in the 1920s the main ESP aspects have been unravelled and theoretically derived, these do not appear to have been always entirely perceived by many in the science community dealing with ESP-related topics but having little familiarity with the complex theories of porous media and poroelasticity. The purpose of this review is to provide a guidance for the reader who needs an updated overview of the different theoretical and experimental approaches to the ESP and related topics over the past century, with particular reference to geological fracturing processes. We begin by illustrating, after some introductive historical remarks, the basic theory underlying the ESP, based on theory of elasticity methods. Then the different ESP-related theories and experimental results, as well as main interpretations of rock jointing and fracturing phenomena, are discussed. Two main classical works are then revisited, and a rigorous ESP proof is derived. Such a proof is aimed at geologists, engineers and geophysicists to become more familiar with theories of porous media and poroelasticity, being based on the classical theory of elasticity. The final part of this review illustrates some still open issues about faulting and hydraulic fracturing in rocks.

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