DOCSLIB.ORG

A Primer for Technical Diving Decompression Theory

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Primer for Technical Diving Decompression Theory SCUBA AA PPRRIIMMEERR FFOORR TECH TTEECCHHNNIICCAALL DDIIVVIINNGG DDEECCOOMMPPRREESSSSIIOONN PHILIPPINES TTHHEEOORRYY 1 | P a g e ©Andy Davis 2015 www.scubatechphilippines.com Sidemount, Technical & Wreck Guide | Andy Davis First Published 2016 All documents compiled in this publication are open-source and freely available on the internet. Copyright Is applicable to the named authors stated within the document. Cover and logo images are copyright to ScubaTechPhilippines/Andy Davis. Not for resale. This publication is not intended to be used as a substitute for appropriate dive training. Diving is a dangerous sport and proper training should only be conducted under the safe supervision of an appropriate, active, diving instructor until you are fully qualified, and then, only in conditions and circumstances which are as good or better than the conditions in which you were trained. Technical scuba diving should be taught by a specialized instructor with training credentials and experience at that level of diving. Careful risk assessment, continuing education and skill practice may reduce your likelihood of an accident, but are in no means a guarantee of complete safety. This publication assumes a basic understanding of diving skills and knowledge. It should be used to complement the undertaking of prerequisite training on the route to enrolling upon technical diving training. 2 | P a g e ©Andy Davis 2015 www.scubatechphilippines.com This primer on decompression theory is designed as a supplement to your technical diving training. Becoming familiar with the concepts and terms outlined in this document will enable you to get the most out of your theory training with me; and subsequently enjoy safer, more refined dive planning and management in your technical diving activities. I have collated several highly-regarded articles which explain key concepts behind the design and use of the Bühlmann ZH- L16 B/C GF algorithm. This algorithm is generally the preferred decompression model in technical diving computers and planning software. If you need any help whilst self-studying this topic, please don’t hesitate to contact me: [email protected] 3 | P a g e ©Andy Davis 2015 www.scubatechphilippines.com Contents Gradient Factors - A Simplified Primer ................................................................................................................ 5 Flexible Control of Decompression ...................................................................................................................... 11 Gradient Factors .................................................................................................................................................... 15 History .............................................................................................................................................................. 15 Decompression Basics ..................................................................................................................................... 16 Tissue Saturation and Ascent Ceiling ............................................................................................................. 17 M-Values .......................................................................................................................................................... 19 Gradient Factors .............................................................................................................................................. 21 Practical Applications and Safe Diving Habits ............................................................................................... 24 Understanding M-Values ...................................................................................................................................... 28 What are M-Values? ....................................................................................................................................... 28 Historical Background ..................................................................................................................................... 29 The Workman M-Values ................................................................................................................................. 31 The Bühlmann M-Values................................................................................................................................. 32 DCAP And DSAT M-Values .............................................................................................................................. 34 Comparison of M-Values ................................................................................................................................ 34 Consistency of M-Values................................................................................................................................. 37 Format for M-Values ....................................................................................................................................... 37 M-Value Characteristics .................................................................................................................................. 37 The Ambient Pressure Line ............................................................................................................................. 38 The Decompression Zone ............................................................................................................................... 39 Multiple Inert Gases ........................................................................................................................................ 39 What Do M-Values Represent? ...................................................................................................................... 40 M-Values and Conservatism ........................................................................................................................... 42 M-Value Relationships .................................................................................................................................... 43 Analysis of Profiles .......................................................................................................................................... 44 Universal Reference Values ............................................................................................................................ 44 Margin of Safety .............................................................................................................................................. 46 4 | P a g e ©Andy Davis 2015 www.scubatechphilippines.com Gradient Factors - A Simplified Primer By Steve Lewis This short article is based on a series of presentations made in various locations during the late winter and spring of 2015, and is a shortened version of a more detailed treatment to be included in an upcoming book. Let’s start off with a disclaimer and an outline of some assumptions made while working on this blog post. First off, I did not start out intending to write a definitive piece on decompression theory or on the stellar work of Professor Albert Bühlmann. Also, this contains no detailed explanation of the internal workings of the maths behind a decompression algorithm and the challenges it meets while trying to model human physiology. Simply put, this was written to help the average punter better understand what gradient factors describe; and the potential impact of playing around with the GF settings on your personal dive computer (for example, a Shearwater Petrel). Secondly, I’ve made several assumptions… not the least of which is that readers have a basic understanding what happens to an individual after spending more than a couple of minutes sub-surface breathing compressed gas. (That’s just another way of saying that I’m writing for certified and reasonably experienced divers who understand that diving can result in decompression stress of one flavor or another.) OK, that settled, here we go. All dives are decompression dives, ergo all divers are decompression divers. Our acknowledgement of this and the depth of that acknowledgement can greatly influence our behavior when we dive: most specifically, our ascent behavior. How deep we dive, what gases we breathe, and how long we spend at depth vary considerably from dive to dive; but all dives share one common threat for individual divers: the risk of getting bent. 5 | P a g e ©Andy Davis 2015 www.scubatechphilippines.com Smart divers consider many factors when planning dives, many of which help to alleviate that risk. One is choosing to dive a “conservative profile.” I guess there are many interpretations of what that means… but for our purposes here, it means choosing a decompression algorithm that’s proven, and choosing a setting for that algorithm that will generate stress-tolerant dive tables. Many PDC (personal dive computers) use a Bühlmann ZHL-8 or ZHL-16 algorithm to model decompression stress in divers and their decompression obligation on ascent. In a way this is odd because both deco models are not only dated (Herr Doktor Professor Bühlmann died of heart failure in early 1994), but are based on the faulty premise that we can prevent bubbles from forming in our bodies during our ascent if we follow the schedules the algorithm kicks out. The data set on all recreational diving, but in particular staged decompression diving, has grown considerably since the Professor’s unfortunate and untimely death, and
Load more

Recommended publications
  • Urinary Problems in Decompression Sickness*
    Paraplegia 23 (1985) 20-25 © 1985 International Medical Society of Paraplegia Urinary Problems in Decompression Sickness* Athanasios Dounis, M.D. and Dionisios Mitropoulos, M.D. The Naval Medical Hyperbaric Center) Piraeus Naval Hospital and Department of Urology) Athens Naval Hospital) Greece Summary The records of 25 patients with type II decompression sickness and urinary problems have been reviewed. Seventeen patients were professionals and 8 were above the age of 40. The disease appeared within the 1st hour of emergence from the water in 70% of the cases and within the first 4 hours in the remaining 30%. Nine patients were diagnosed as paraplegic and two as tetraplegic. All patients had urinary disturbances and 14 were on Foley-catheter drainage during the decompression while 11 were on intermittent catheterisation. Fifteen patients had improved urinary function after recompression) 8 had some difficulty) 2 underwent a sphincterotomy and one a transurethral prostatectomy. The low percentage of complete recovery was due to the delayed arrival at the decompression chamber. Key words: Diving; Decompression sickness; Urinary disturbances. Introduction Diving for sponge fishery is the main professional occupation of the young men in the South-East Aegean islands. Although the use of recompression has decreased the number of decompression sickness victims, patients with remaining neurological problems still present. During the last 20 years, although there is a decrease of the professional divers' accidents there is an increase of the number of patients with decompression sickness. This is due to the continuously increasing numbers of sport divers in Greece. In Greece, the field of underwater medicine is covered mainly by the Naval Medical Service.
    [Show full text]
  • VR Series Dive Computer Manual
    VR Technology Limited To ensure your user information is up to date. Please check www.technologyindepth.com for updates to this manual. VR Series Dive Computer Manual VR Dive Computer Operations Manual 2009 rev E 28/01/2009 1 VR Technology Limited Model Name VRX/VR3 Manufactured by VR Technology Limited Unit 12 Blackhill Road West Holton Heath Industrial Estate Poole Dorset BH16 6LE England UK WARNING Diving is an adventurous sport and should not be undertaken without receiving the necessary training from a recognised training agency. VR Dive Computer Operations Manual 2009 rev E 28/01/2009 2 VR Technology Limited Table of Contents Model Name...................................................................................................................2 Manufactured by ............................................................................................................2 Getting Started ...............................................................................................................7 Battery............................................................................................................................7 Power Monkey charging option (VRx)..........................................................................8 Switches .....................................................................................................................8 Home Screen..................................................................................................................9 The Home Screen features.........................................................................................9
    [Show full text]
  • Nitrox CONFIRME
    Formation théorique NITROX Patrick Baptiste MF1 n° 22108 Formation théorique Nitrox confirmé Sommaire de la formation • Rappels • La réglementation • La crise Hyperoxique l’effet Paul Bert l’effet Lorrain Smith • La table NOAA • Le compteur SNC • Les UPDT ou OTU • Les autres effets physiologiques La syncope Hypoxique Effet vasoconstricteur de l’O2 • La fabrication des mélanges Patrick Baptiste MF1 n° 22108 Formation théorique Nitrox confirmé Composition de l’air L'air sec au voisinage du sol est approximativement composé de: • 78,08 % d’azote, • 20,95 % d’oxygène, • moins de 1 % d'autres gaz dont : • argon 0,93%, • néon 0,0018%, • krypton 0,00011%, • xénon 0,00009% • dioxyde de carbone 0,033 %. Il contient aussi des traces d'hydrogène 0,000072%, mais aussi d'ozone et de radon. Patrick Baptiste MF1 n° 22108 Formation théorique Nitrox confirmé Composition de l’air Nous considérons que la composition de l’air est la suivante : - Oxygène (O²) 21 % - Azote (N²) 79 % Convention d’appellation Par convention, on désigne ce mélange en citant en premier sa teneur en O² puis sa teneur en N², on obtient une indication du type : O²/N² ou XX / YY . un mélange définit comme suit : 40/60 Désigne un NITROX contenant 40 % d’O² et 60 % de N² Patrick Baptiste MF1 n° 22108 Formation théorique Nitrox confirmé Limites et contraintes Liés à l’augmentation de la pression partielle d’oxygène (PpO²) - Limitation de la profondeur maximum par rapport à l’air( PpO²max = 1,6b .) - Limitation variable de la profondeur en fonction du mélange respiré - Risque d’accident hyperoxique si les profondeurs planchées ou la durée d’utilisation sont dépassés, - Manipulation plus contraignante et plus dangereuse, - Nécessite un matériel spécifique ( compresseur, équipement spécifique si Nitrox > 40/60) - Planification des plongées obligatoires et plus complexes - Prix de revient plus élevé que l’air.
    [Show full text]
  • Hyperbaric Physiology the Rouse Story Arrival at Recompression
    Hyperbaric Physiology The Rouse Story • Oct 12, 1992, off the New Jersey coast • father/son team of experienced divers • explore submarine wreck in 230 ft (70 m) • breathing compressed air • trapped in wreck & escaped with no time for decompression Chris and Chrissy Rouse Arrival at recompression Recompression efforts facility • Both divers directly ascend to dive boat • Recompression starts about 3 hrs after • Helicopter arrives at boat in 1 hr 27 min ascent • Bronx Municipal Hospital recompression facility – put on pure O2 and compressed to 60 ft – Chris (39 yrs) pronounced dead • extreme pain as circulation returned – compressed to 165 ft, then over 5.5 hrs – Chrissy (22 yrs) gradually ascended back to 30 ft., lost • coherent and talking consciousness • paralysis from chest down • no pain – back to 60 ft. Heart failure and death • blood sample contained foam • autopsy revealed that the heart contained only foam Medical Debriefing Gas Laws • Boyle’s Law • Doctors conclusions regarding their – P1V1 = P2V2 treatment • Dalton’s Law – nothing short of recompression to extreme – total pressure is the sum of the partial pressures depths - 300 to 400 ft • Henry’s Law – saturation treatment lasting several days – the amt of gas dissolved in liquid at any temp is – complete blood transfusion proportional to it’s partial pressure and solubility – deep helium recompression 1 Scuba tank ~ 64 cf of air Gas problems during diving Henry, 1 ATM=33 ft gas (10 m) dissovled = gas Pp & tissue • Rapture of the deep (Nitrogen narcosis) solubility • Oxygen
    [Show full text]
  • Full Paper/Talk Deep Stops and Shallow Stops – Fact and Fancy
    Full Paper/Talk Deep Stops and Shallow Stops – Fact and Fancy B.R. Wienke1 and T.R. O’Leary2 1 C&C Dive Team Ldr, Program Manager Computational Physics, LANL, MS D490, Los Alamos, NM 87545 [email protected] 2 Director, NAUI Technical Diving Operations, 33256 State Rd 100, South Padre Island, TX, 78597 Abstract The question of deep stops and shallow stops is interesting and fraught with controversy in diving circles and operations, training, exploration and scientific endeavors. Plus frought with some misunderstanding which is understandable as the issues are complex. We therefore attempt a short history of deep and shallow stops, physical aspects, staging differences, diving tests, models with data correlations and data banks with user statistics and DCS outcomes as diver amplification. Pros and cons of both deep stop and shallow stop staging are presented. Misfacts are righted when appropriate. Chamber, wet and Doppler tests are contrasted. A compendium of Training Agency Standards regarding deep and shallow stops is included. Dive software is also detailed. Some commercial diving operations are discussed. A short tabulation of dive computer and software algorithms is given. From diving data, tests, DCS outcomes and field usage, we conclude that both deep stops and shallow stops are safely employed in recreational and technical diving. That is a good thing but choose your deco wisely and know why. Keywords: computational models, decompression staging, profile data, risk, statistical correlations, tests Acronyms and Nomenclature ANDI: Association of Nitrox Diving Instructors. BM: bubble phase model dividing the body into tissue compartments with halftimes that are coupled to inert gas diffusion across bubble film surfaces of exponential size distribution constrained in cumulative growth by a volume limit point.
    [Show full text]
  • Dysbarism - Barotrauma
    DYSBARISM - BAROTRAUMA Introduction Dysbarism is the term given to medical complications of exposure to gases at higher than normal atmospheric pressure. It includes barotrauma, decompression illness and nitrogen narcosis. Barotrauma occurs as a consequence of excessive expansion or contraction of gas within enclosed body cavities. Barotrauma principally affects the: 1. Lungs (most importantly): Lung barotrauma may result in: ● Gas embolism ● Pneumomediastinum ● Pneumothorax. 2. Eyes 3. Middle / Inner ear 4. Sinuses 5. Teeth / mandible 6. GIT (rarely) Any illness that develops during or post div.ing must be considered to be diving- related until proven otherwise. Any patient with neurological symptoms in particular needs urgent referral to a specialist in hyperbaric medicine. See also separate document on Dysbarism - Decompression Illness (in Environmental folder). Terminology The term dysbarism encompasses: ● Decompression illness And ● Barotrauma And ● Nitrogen narcosis Decompression illness (DCI) includes: 1. Decompression sickness (DCS) (or in lay terms, the “bends”): ● Type I DCS: ♥ Involves the joints or skin only ● Type II DCS: ♥ Involves all other pain, neurological injury, vestibular and pulmonary symptoms. 2. Arterial gas embolism (AGE): ● Due to pulmonary barotrauma releasing air into the circulation. Epidemiology Diving is generally a safe undertaking. Serious decompression incidents occur approximately only in 1 in 10,000 dives. However, because of high participation rates, there are about 200 - 300 cases of significant decompression illness requiring treatment in Australia each year. It is estimated that 10 times this number of divers experience less severe illness after diving. Physics Boyle’s Law: The air pressure at sea level is 1 atmosphere absolute (ATA). Alternative units used for 1 ATA include: ● 101.3 kPa (SI units) ● 1.013 Bar ● 10 meters of sea water (MSW) ● 760 mm of mercury (mm Hg) ● 14.7 pounds per square inch (PSI) For every 10 meters a diver descends in seawater, the pressure increases by 1 ATA.
    [Show full text]
  • 8. Decompression Procedures Diver
    TDI Standards and Procedures Part 2: TDI Diver Standards 8. Decompression Procedures Diver 8.1 Introduction This course examines the theory, methods and procedures of planned stage decompression diving. This program is designed as a stand-alone course or it may be taught in conjunction with TDI Advanced Nitrox, Advanced Wreck, or Full Cave Course. The objective of this course is to train divers how to plan and conduct a standard staged decompression dive not exceeding a maximum depth of 45 metres / 150 feet. The most common equipment requirements, equipment set-up and decompression techniques are presented. Students are permitted to utilize enriched air nitrox (EAN) mixes or oxygen for decompression provided the gas mix is within their current certification level. 8.2 Qualifications of Graduates Upon successful completion of this course, graduates may engage in decompression diving activities without direct supervision provided: 1. The diving activities approximate those of training 2. The areas of activities approximate those of training 3. Environmental conditions approximate those of training Upon successful completion of this course, graduates are qualified to enroll in: 1. TDI Advanced Nitrox Course 2. TDI Extended Range Course 3. TDI Advanced Wreck Course 4. TDI Trimix Course 8.3 Who May Teach Any active TDI Decompression Procedures Instructor may teach this course Version 0221 67 TDI Standards and Procedures Part 2: TDI Diver Standards 8.4 Student to Instructor Ratio Academic 1. Unlimited, so long as adequate facility, supplies and time are provided to ensure comprehensive and complete training of subject matter Confined Water (swimming pool-like conditions) 1.
    [Show full text]
  • Chapter 23 ENVIRONMENTAL EXTREMES: ALTERNOBARIC
    Environmental Extremes: Alternobaric Chapter 23 ENVIRONMENTAL EXTREMES: ALTERNOBARIC RICHARD A. SCHEURING, DO, MS*; WILLIAM RAINEY JOHNSON, MD†; GEOFFREY E. CIARLONE, PhD‡; DAVID KEYSER, PhD§; NAILI CHEN, DO, MPH, MASc¥; and FRANCIS G. O’CONNOR, MD, MPH¶ INTRODUCTION DEFINITIONS MILITARY HISTORY AND EPIDEMIOLOGY Altitude Aviation Undersea Operations MILITARY APPLIED PHYSIOLOGY Altitude Aviation Undersea Operations HUMAN PERFORMANCE OPTIMIZATION STRATEGIES FOR EXTREME ENVIRONMENTS Altitude Aviation Undersea Operations ONLINE RESOURCES FOR ALTERNOBARIC ENVIRONMENTS SUMMARY *Colonel, Medical Corps, US Army Reserve; Associate Professor, Military and Emergency Medicine, Uniformed Services University of the Health Sci- ences, Bethesda, Maryland †Lieutenant, Medical Corps, US Navy; Undersea Medical Officer, Undersea Medicine Department, Naval Medical Research Center, Silver Spring, Maryland ‡Lieutenant, Medical Service Corps, US Navy; Research Physiologist, Undersea Medicine Department, Naval Medical Research Center, Silver Spring, Maryland §Program Director, Traumatic Injury Research Program; Assistant Professor, Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland ¥Colonel, Medical Corps, US Air Force; Assistant Professor, Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland ¶Colonel (Retired), Medical Corps, US Army; Professor and former Department Chair, Military and Emergency Medicine, Uniformed Services University of the Health Sciences,
    [Show full text]
  • T1, U-2 and L1 Transmitters™ Software V3.06 April 22, 2014
    ™ Air Integrated Dive Computer User Manual ™ Air Integrated Dive Computer Software v1.18 Ultrasonic software v1.11 And T1, U-2 and L1 Transmitters™ Software v3.06 April 22, 2014 Liquivision Products, Inc -1- Manual 1.6; Lynx 1.18; US 1.11; U-2 3.06 ™ Air Integrated Dive Computer User Manual CONTENTS IMPORTANT NOTICES ............................................................................................................................... 8 Definitions ..................................................................................................................................................... 9 User Agreement and Warranty ....................................................................................................................... 9 User Manual .................................................................................................................................................. 9 Liquivision Limitation of Liability ............................................................................................................... 10 Trademark Notice ........................................................................................................................................ 10 Patent Notice ............................................................................................................................................... 10 CE ............................................................................................................................................................... 10 LYNX
    [Show full text]
  • Deadly Acute Decompression Sickness in Risso's Dolphins
    www.nature.com/scientificreports OPEN Deadly acute Decompression Sickness in Risso’s dolphins A. Fernández, E. Sierra, J. Díaz-Delgado, S. Sacchini , Y. Sánchez-Paz, C. Suárez-Santana, M. Arregui, M. Arbelo & Y. Bernaldo de Quirós Received: 19 April 2017 Diving air-breathing vertebrates have long been considered protected against decompression sickness Accepted: 5 October 2017 (DCS) through anatomical, physiological, and behavioural adaptations. However, an acute systemic gas Published: xx xx xxxx and fat embolic syndrome similar to DCS in human divers was described in beaked whales that stranded in temporal and spatial association with military exercises involving high-powered sonar. More recently, DCS has been diagnosed in bycaught sea turtles. Both cases were linked to human activities. Two Risso’s dolphin (Grampus griseus) out of 493 necropsied cetaceans stranded in the Canary Islands in a 16-year period (2000–2015), had a severe acute decompression sickness supported by pathological fndings and gas analysis. Deadly systemic, infammatory, infectious, or neoplastic diseases, ship collision, military sonar, fsheries interaction or other type of lethal inducing associated trauma were ruled out. Struggling with a squid during hunting is discussed as the most likely cause of DCS. Pathologies related to efects of changes in pressure are well known among human divers. Decompression sick- ness (DCS) is a syndrome related to the formation of gas bubbles in blood and/or tissues when the sum of the dissolved gas tensions exceeds the local absolute pressure. Gas bubbles may have biochemical efects and disrupt the tissues or occlude the vessels with clinical and pathological signs and, in certain cases, death1.
    [Show full text]
  • Diving Safety Manual Revision 3.2
    Diving Safety Manual Revision 3.2 Original Document: June 22, 1983 Revision 1: January 1, 1991 Revision 2: May 15, 2002 Revision 3: September 1, 2010 Revision 3.1: September 15, 2014 Revision 3.2: February 8, 2018 WOODS HOLE OCEANOGRAPHIC INSTITUTION i WHOI Diving Safety Manual DIVING SAFETY MANUAL, REVISION 3.2 Revision 3.2 of the Woods Hole Oceanographic Institution Diving Safety Manual has been reviewed and is approved for implementation. It replaces and supersedes all previous versions and diving-related Institution Memoranda. Dr. George P. Lohmann Edward F. O’Brien Chair, Diving Control Board Diving Safety Officer MS#23 MS#28 [email protected] [email protected] Ronald Reif David Fisichella Institution Safety Officer Diving Control Board MS#48 MS#17 [email protected] [email protected] Dr. Laurence P. Madin John D. Sisson Diving Control Board Diving Control Board MS#39 MS#18 [email protected] [email protected] Christopher Land Dr. Steve Elgar Diving Control Board Diving Control Board MS# 33 MS #11 [email protected] [email protected] Martin McCafferty EMT-P, DMT, EMD-A Diving Control Board DAN Medical Information Specialist [email protected] ii WHOI Diving Safety Manual WOODS HOLE OCEANOGRAPHIC INSTITUTION DIVING SAFETY MANUAL REVISION 3.2, September 5, 2017 INTRODUCTION Scuba diving was first used at the Institution in the summer of 1952. At first, formal instruction and proper information was unavailable, but in early 1953 training was obtained at the Naval Submarine Escape Training Tank in New London, Connecticut and also with the Navy Underwater Demolition Team in St.
    [Show full text]
  • Dive Theory Guide
    DIVE THEORY STUDY GUIDE by Rod Abbotson CD69259 © 2010 Dive Aqaba Guidelines for studying: Study each area in order as the theory from one subject is used to build upon the theory in the next subject. When you have completed a subject, take tests and exams in that subject to make sure you understand everything before moving on. If you try to jump around or don’t completely understand something; this can lead to gaps in your knowledge. You need to apply the knowledge in earlier sections to understand the concepts in later sections... If you study this way you will retain all of the information and you will have no problems with any PADI dive theory exams you may take in the future. Before completing the section on decompression theory and the RDP make sure you are thoroughly familiar with the RDP, both Wheel and table versions. Use the appropriate instructions for use guides which come with the product. Contents Section One PHYSICS ………………………………………………page 2 Section Two PHYSIOLOGY………………………………………….page 11 Section Three DECOMPRESSION THEORY & THE RDP….……..page 21 Section Four EQUIPMENT……………………………………………page 27 Section Five SKILLS & ENVIRONMENT…………………………...page 36 PHYSICS SECTION ONE Light: The speed of light changes as it passes through different things such as air, glass and water. This affects the way we see things underwater with a diving mask. As the light passes through the glass of the mask and the air space, the difference in speed causes the light rays to bend; this is called refraction. To the diver wearing a normal diving mask objects appear to be larger and closer than they actually are.
    [Show full text]