Hector Lopez

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Judith L Green

University of California, Santa Barbara

E. Wayne Ross

University of British Columbia

Alisa Perren

The University of Texas at Austin

Don Ross

University College Cork

Giulia Sissa

Ucla

Göran Bolin

Södertörn University

Didier COSTE

Université Bordeaux-Montaigne

Luca Barra

Università di Bologna

Maria Immacolata Vassallo de Lopes

Universidade de São Paulo

Alberto N. García

Universidad de Navarra

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Papers by Hector Lopez

Statistics of Speckle in Ultrasound B-Scans

IEEE Transactions on Sonics and Ultrasonics, 1983

Statistics of speckle in ultrasound B-scans. RF Wagner, SW Smith, JM Sandrik, H Lopez IEEE TRANS.... more

Low Contrast Detectability and Contrast/Detail Analysis in Medical Ultrasound

IEEE Transactions on Sonics and Ultrasonics, 1983

Abstruct-The first-and second-order statistics of envelope detected ultrasound (US) B-mode images... more Abstruct-The first-and second-order statistics of envelope detected ultrasound (US) B-mode images for the case of a scattering phantom with many scatteiers per resolution cell have been previously derived. These characteristics are integrated over the region of a simulated focal (disk) lesion and the signal-to-noise ratio (SNR) for lesion detectability is obtained. This SNR requires the average number of independent speckle cells over the lesion area (analogous to the number of x-ray photons over the lesion area in incoherent light or x-ray imaging). This number is obtained from our autocorrelation analysis (second-order statistics). By setting the SNR expression equal to the threshold value SNRT required to detect a lesion in the presence of speckle noise, the dependence of lesion contrast on lesion diameter at threshold is found, i.e., the contrast/detail function. This is a simple inverse relation for ideal observers of US B-scans. It is also found that the contrast/detail results for envelope detection in diagnostic ultrasound are almost identical with the results for square law detection (the usual laser case) with the latter serving as an upper limit for performance in lesion detection. Finally, the results of human observer performance using a contrast/ detail phantom are compared with the predictions for optimal or ideal performance. The results are comparable with results for photon imaging systems, with values of the SNR at threshold in the neighborhood of 2-3.

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International Society of Sports Nutrition position stand: creatine supplementation and exercise

Journal of The International Society of Sports Nutrition, 2007

Position Statement: The International Society of Sports Nutrition (ISSN) bases the following posi... more Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on a critical analysis of the literature on the use of beta-hydroxy-beta-methylbutyrate (HMB) as a nutritional supplement. The ISSN has concluded the following. 1. HMB can be used to enhance recovery by attenuating exercise induced skeletal muscle damage in trained and untrained populations. 2. If consuming HMB, an athlete will benefit from consuming the supplement in close proximity to their workout. 3. HMB appears to be most effective when consumed for 2 weeks prior to an exercise bout. 4. Thirty-eight mg·kg·BM -1 daily of HMB has been demonstrated to enhance skeletal muscle hypertrophy, strength, and power in untrained and trained populations when the appropriate exercise prescription is utilized. 5. Currently, two forms of HMB have been used: Calcium HMB (HMB-Ca) and a free acid form of HMB (HMB-FA). HMB-FA may increase plasma absorption and retention of HMB to a greater extent than HMB-CA. However, research with HMB-FA is in its infancy, and there is not enough research to support whether one form is superior. 6. HMB has been demonstrated to increase LBM and functionality in elderly, sedentary populations. 7. HMB ingestion in conjunction with a structured exercise program may result in greater declines in fat mass (FM). 8. HMB's mechanisms of action include an inhibition and increase of proteolysis and protein synthesis, respectively. 9. Chronic consumption of HMB is safe in both young and old populations.

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International Society of Sports Nutrition position stand: protein and exercise

Journal of The International Society of Sports Nutrition, 2007

The following seven points related to the intake of protein for healthy, exercising individuals c... more The following seven points related to the intake of protein for healthy, exercising individuals constitute the position stand of the Society. They have been approved by the Research Committee of the Society. 1) Vast research supports the contention that individuals engaged in regular exercise training require more dietary protein than sedentary individuals. 2) Protein intakes of 1.4 -2.0 g/kg/day for physically active individuals is not only safe, but may improve the training adaptations to exercise training. 3) When part of a balanced, nutrient-dense diet, protein intakes at this level are not detrimental to kidney function or bone metabolism in healthy, active persons. 4) While it is possible for physically active individuals to obtain their daily protein requirements through a varied, regular diet, supplemental protein in various forms are a practical way of ensuring adequate and quality protein intake for athletes. 5) Different types and quality of protein can affect amino acid bioavailability following protein supplementation. The superiority of one protein type over another in terms of optimizing recovery and/or training adaptations remains to be convincingly demonstrated. 6) Appropriately timed protein intake is an important component of an overall exercise training program, essential for proper recovery, immune function, and the growth and maintenance of lean body mass. 7) Under certain circumstances, specific amino acid supplements, such as branched-chain amino acids (BCAA's), may improve exercise performance and recovery from exercise.

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International Society of Sports Nutrition position stand: Nutrient timing

Journal of The International Society of Sports Nutrition, 2008

Position Statement: The position of the Society regarding nutrient timing and the intake of carbo... more Position Statement: The position of the Society regarding nutrient timing and the intake of carbohydrates, proteins, and fats in reference to healthy, exercising individuals is summarized by the following eight points: 1.) Maximal endogenous glycogen stores are best promoted by following a high-glycemic, high-carbohydrate (CHO) diet (600 -1000 grams CHO or ~8 -10 g CHO/kg/d), and ingestion of free amino acids and protein (PRO) alone or in combination with CHO before resistance exercise can maximally stimulate protein synthesis. 2.) During exercise, CHO should be consumed at a rate of 30 -60 grams of CHO/hour in a 6 -8% CHO solution (8 -16 fluid ounces) every 10 -15 minutes. Adding PRO to create a CHO:PRO ratio of 3 -4:1 may increase endurance performance and maximally promotes glycogen re-synthesis during acute and subsequent bouts of endurance exercise. 3.) Ingesting CHO alone or in combination with PRO during resistance exercise increases muscle glycogen, offsets muscle damage, and facilitates greater training adaptations after either acute or prolonged periods of supplementation with resistance training. 4.) Post-exercise (within 30 minutes) consumption of CHO at high dosages (8 -10 g CHO/kg/day) have been shown to stimulate muscle glycogen re-synthesis, while adding PRO (0.2 g -0.5 g PRO/ kg/day) to CHO at a ratio of 3 -4:1 (CHO: PRO) may further enhance glycogen re-synthesis. 5.) Post-exercise ingestion (immediately to 3 h post) of amino acids, primarily essential amino acids, has been shown to stimulate robust increases in muscle protein synthesis, while the addition of CHO may stimulate even greater levels of protein synthesis. Additionally, pre-exercise consumption of a CHO + PRO supplement may result in peak levels of protein synthesis. 6.) During (page number not for citation purposes) consistent, prolonged resistance training, post-exercise consumption of varying doses of CHO + PRO supplements in varying dosages have been shown to stimulate improvements in strength and body composition when compared to control or placebo conditions. 7.) The addition of creatine (Cr) (0.1 g Cr/kg/day) to a CHO + PRO supplement may facilitate even greater adaptations to resistance training. 8.) Nutrient timing incorporates the use of methodical planning and eating of whole foods, nutrients extracted from food, and other sources. The timing of the energy intake and the ratio of certain ingested macronutrients are likely the attributes which allow for enhanced recovery and tissue repair following high-volume exercise, augmented muscle protein synthesis, and improved mood states when compared with unplanned or traditional strategies of nutrient intake.

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Statistics of Speckle in Ultrasound B-Scans

IEEE Transactions on Sonics and Ultrasonics, 1983

Statistics of speckle in ultrasound B-scans. RF Wagner, SW Smith, JM Sandrik, H Lopez IEEE TRANS.... more