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ISO and Aperture
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ISO, aperture and shutter speed videography camerasA solution is composed of a solute dissolved in a solvent. In the sugar water described in Figure 5-1, the solute was sugar and the solvent was water, and the solute molecules diffused through the solvent. It is also possible for solvent molecules to diffuse. In the case of cells, the solutes are organic and inorganic compounds, and the solvent is water. The process by which water molecules diffuse across a cell membrane from an area of higher concentration to an area of lower concentration is called osmosis (ahs-MOH-sis). Because water is moving from a higher to lower concentration, osmosis does not require cells to expend energy. Therefore, osmosis is the passive transport of water. Direction of Osmosis The net direction of osmosis depends on the relative concentra- tion of solutes on the two sides of the membrane. Examine Table 5-1. When the concentration of solute molecules outside the cell is lower than the concentration in the cytosol, the solution outside is hypotonic to the cytosol. In this situation, water diffuses into the cell until equilibrium is established. When the concentration of solute molecules outside the cell is higher than the concentration in the cytosol, the solution outside is hypertonic to the cytosol. In this situation, water diffuses out of the cell until equilibrium is established. Observing Diffusion Materials 600 mL beaker, 25 cm dialysis tubing, funnel, 15 mL starch solution (10 percent), 20 drops Lugol’s solution, 300 mL water, 100 mL graduated cylinder, 20 cm piece of string (2) Procedure 1. Put on your disposable gloves, lab apron, and safety goggles. 2. Pour 300 mL of water in the 600 mL beaker. 3. Add 20 drops of Lugol’s solution to the water. CAUTION: Lugol’s solution is a poison and eye and skin irritant. 4. Open the dialysis tubing, and tie one end tightly with a piece of string. 5. Using the funnel, pour 15 mL of 10 percent starch solution into the dialysis tubing. 6. Tie the other end of the dialysis tubing tightly with the second piece of string, forming a sealed bag around the starch solution. 7. Place the bag into the solution in the beaker, and observe the setup for a color change. Analysis What happened to the color in the bag? What happened to the color of the water around the bag? Explain your observations. Quick Lab www.scilinks.org Topic: Osmosis Keyword: HM61090 mb06se_homs01.qxd 11/27/07 8:52 AM Page 98 HOMEOSTASIS AND CELL TRANSPORT 99 When the concentrations of solutes outside and inside the cell are equal, the outside solution is said to be isotonic to the cytosol. Under these conditions, water diffuses into and out of the cell at equal rates, so there is no net movement of water. Notice that the prefixes hypo-, hyper-, and iso- refer to the relative solute concentrations of two solutions. Thus, if the solution outside the cell is hypotonic to the cytosol, then the cytosol must be hyper- tonic to that solution. Conversely, if the solution outside is hypertonic to the cytosol, then the cytosol must be hypotonic to the solution. Water tends to diffuse from hypo- tonic solutions to hypertonic solutions. How Cells Deal with Osmosis Cells that are exposed to an isotonic external environment usually have no difficulty keeping the movement of water across the cell membrane in balance. This is the case with the cells of ver- tebrate animals on land and of most other organ- isms living in the sea. In contrast, many cells function in a hypotonic environment. Such is the case for unicellular freshwater organisms. Water constantly diffuses into these organisms. Because they require a relatively lower concentration of water in the cytosol to function normally, unicel- lular organisms must rid themselves of the excess water that enters by osmosis. Some of them, such as the paramecia shown in Figure 5-2, do this with contractile vacuoles (kon-TRAK-til VAK-y ̄ ̄o ̄ ̄o-OL), which are organelles that remove water. Contractile vacuoles collect the excess water and then contract, pumping the water out of the cell. Unlike diffusion and osmosis, this pumping action is not a form of passive trans- port because it requires the cell to expend energy. Copyright © by Holt, Rinehart and Winston. All rights reserved. (a) (b) Vacuole filling with water Vacuole contracting TABLE 5-1 Direction of Osmosis Condition External solution is hypotonic to cytosol External solution is hypertonic to cytosol External solution is isotonic to cytosol Net movement of water into the cell out of the cell none H2O H2O H2O H2O H2O H2O The paramecia shown below live in fresh water, which is hypotonic to their cytosol. (a) Contractile vacuoles collect excess water that moves by osmosis into the cytosol. (b) The vacuoles then contract, returning the water to the outside of the cell. (LM 315) FIGURE 5-2 100 CHAPTER 5 (a) HYPOTONIC Cell walls (b) HYPERTONIC (a) ISOTONIC (b) HYPOTONIC (c) HYPERTONIC Other cells, including many of those in multicellular organisms, respond to hypotonic environments by pumping solutes out of the cytosol. This lowers the solute concentration in the cytosol, bring- ing it closer to the solute concentration in the environment. As a result, water molecules are less likely to diffuse into the cell. Most plant cells, like animal cells, live in a hypotonic environ- ment. In fact, the cells that make up plant roots may be surrounded by water. This water moves into plant cells by osmosis. These cells swell as they fill with water until the cell membrane is pressed against the inside of the cell wall, as Figure 5-3a shows. The cell wall is strong enough to resist the pressure exerted by the water inside the expanding cell. The pressure that water molecules exert against the cell wall is called turgor pressure (TER-GOR PRESH-er). In a hypertonic environment, water leaves the cells through osmosis. As shown in Figure 5-3b, the cells shrink away from the cell walls, and turgor pressure is lost. This condition is called plasmolysis (plaz-MAHL-uh-sis), and is the reason that plants wilt if they don’t receive enough water. Some cells cannot compensate for changes in the solute con-G10-Q and A in POWER ISO-Q2Good day this is Chris today we will be doing a quick walkthrough on ISO 14001 2015 Environmental Management System and its main clauses let's get started ISO 14001 2015 Environmental Management System is a globally recognized standard for environment Management systems or EMS an EMS is a framework that organizations use to manage their environmental impact comply with regulations and improve their environmental performance the standard outlines are requirements for an EMS including the development of an environmental policy the identification of environmental aspects and impacts the establishment of objectives and targets the implementation of operational control monitoring and measurement systems and the ongoing review and Improvement of the system ISO 14001 is a flexible standard that can be used by organizations of any size or type regardless of their environment impact or level of environment performance it provides a practical framework for organizations to manage their environmental impact reduce environment risks and demonstrate their commitment on sustainability to their stakeholders here is the standard that provides a structured approach to develop an EMS which includes several key steps one organizations must develop an environmental policy that outlines their commitment to environmental sustainability this policy should be communicated to all employees and stakeholders two organizations must identify their environmental aspects and impacts this involves identifying the activities products and services that have an impact on the environment as well as the potential environmental consequences of those impacts three once the environmental aspects and the impacts have been identified organizations must establish environmental objectives and targets these objectives and targets should be specific measurable achievable relevant and time-bound 4. after setting objectives and targets organizations must Implement operational controls and establish monitoring and measurement systems to ensure that they are meeting their objectives and targets finally organizations must review and continually improve their EMS this involves conducting regular audits reviewing the EMS to ensure that it remains relevant and effective and making any necessary changes or improvements the main Clause of iso 14001 2015 apart from its scope normative references and terms and conditions that the main Clauses of iso 14001 2015 can be listed as context of the organization leadership planning support operation performance evaluation and Improvement Clause 4.0 context of the organization is about understanding the organization and its context understanding the needs and expectations of the interested parties determining the scope of the Environmental Management System EMS and Environmental Management System itself Clause 5.0 talks about leadership and commitment Environmental Policy organizational roles responsibility and authorities Clause 6.0 planning focuses on actions to address risk and opportunities as well as environmental objectives and planning to achieve them Clause 7.0 support are detailed requirements on resources competence awareness communication that includes external and internal communication documented information that involves creating updating in control of documented information Clause 8.0 operation talks about operational planning and control as well as emergency preparedness and response overall the design of iso 14001 2015 provides guidelines to form a system that is structured to cater the requirements of stakeholder needs and expectations to drive life cycle perspective and Energy Efficiency as pictured here Clause 9.0 performance evaluation provides guidelines to monitoring measurement analysis and evaluation evaluation compliance and management review an additional note here is that ISO 19011 2018 guidelines for auditing Management Systems which is an audit process that will determine the scope to establish the audit criteria by collecting evidence evaluating the evidence and then draw a conclusion based on the findings as pictured here [Music] finally Clause 10.0 Improvement talks about how Improvement is an integral factor to an effective Environmental Management system through General non-conformity and corrective action and continual Improvement talking about Improvement it is always continual in putting efforts towards the betterment of the existing system here is a snapshot of the main Clauses of iso 14001 2015 [Music] I hope you find this video useful we are industry experts specialized in management system consultancy and Industry relevant corporate training give us a call and let us help you drive your business excellence and upskill your employees to elevate workplace efficiency [Music] CREATE 10 MCQ AND 2 SAQ QUESTIONS BASED ON THE ABOVE PARAGRAPHGenerate 10 MCQs on Quality Management System fundamentals based on ISO 9001. Include basic concepts like PDCA cycle, quality policy, customer focus, and process approach. Add 3 scenario-based questions.Chapter 7 - Review Data and Decision Making *Glow bus due at midnight, name and student number: answer questions using content in class People have created wonderful things for centuries, and management Management can be traced as far back as 500 bc when the ancient Sumerians used written records to improve government and business activities Why is it important to lean from the past Not to repeat our mistakes Classical management approaches Scientific management Administrative Principles Bureaucratic organisation Behavioural Management Approaches Follett’s Organizations as communities The Hawthorne studies Maslow’s theory of human needs Mcgregor’s Theory x and Theory Y Argyris Personality and organisation Modern Management foundations Organises as systems Contingency thinking Quality management Quantitative and analysis and tools Evidence-based management Contributions Frederick Taylor - Father of Scientific management He noticed that workers often did their jobs with wasted motions and without a constant approach. His resulted in inefficiency and low performance He believed the problem could be fixed if workers were taught to do their jobs in the best ways and ten were helped and guided by supervisors Four guiding principles of scientific management Rules of motion, standardized work and proper working conditions Select workers with the right abilities Train workers and give them incentives Support workers by planning and smoothing the way as they do their work Frank and Lillian Gilbreth Pioneered use of motitono studies as a management tool In one famous case, the gilbreaths cut down the number of motions used by bricklayers adn tripled their productivity Contributions from scientific management Make results-based compensation a performance incentive Carefully design jobs with efficient work methods Carefully select workers with the ability to perform the job Trian workers to execute activities to the best of their abilities Train supervisors to support workers so they can perform jobs to the best of their abilities Classical Management Adiminstative principle (Henro Fayol) 1919, after a career in French industry, Henri F published “adminisration Industrielle et Generale” (General and industrial management) in which we out like his views on the management of organiztion and workers Rules and duties in management Foresight - to complete a plan of action for the future Organization - To provide and mobilize resources to implement the plan Common- to lead, select and evaluate workers to get the best work toward the plan Coordination- to fit diverse efforts together and ensure information is shared and problems solved Control- to make sure things happen according to plan and to take necessary corrective action Classical management Bureacratic organiztion (Max Weber) Max weber (Bureaucrativ organization) - late 19th century German political economist who had a major impact in the fields of management and sociology Bureaucratic Organization An ideal, intentionally rational adn very efficient form of organization Based on the principles of logic, order and legitimate authority Characteristics of BO Clear division of labour Clear hierarchy of authority Formal rules and procedure Impersonality Careers based on merit What are some disadvantages of bureaucracy Takes a long time for problems to become solved bec there are procedures and there is a chain of people in command Having the power Rules have to follow Excessive paperwork or “red tape” Slowness in handling problems Rigidity in the face of shifting needs Resistance to change Employee apathy Behavioural Management Approaches (focus on understanding the elements that affect human behaviour in organisations) Follett’s Organizations as communites Mary park follett contributed to the transition from classical thinking inot behavioural management Groups and human cooperation Groups allow individuales too combine their talents for a greater good Organizations are cooperating “communites” of managers adn workers Managers job is to help people copperate and achive an integration of goals and intrests Forward-looking managment insight: Making every emploee an owner creates a sense of collective responsibility Prescursor of employrr ownership, profit sharing and gain sharing Buniess problems invovle a varity of inter realted factors Prescursor of systems thinking Private profits realtive to public good Precursor of managerial ethics and social respinsibility Hawthorne studies Took place at western electric chicago plan, a tran led by Harvards Elton Mayo set out to learn how econmic incentives and workplace conditions affected workers output Maing objective Intial study examined how ecomoin incentives adn physical conditions affected worker output (productivity) No consistent relationship found During experientmetn they had 2 groups The expertiant groups (impoved wokring ocnditions ) The control group ( no changes to original working conidtions) No consitant relationship found, perfomance in both groups increased even after removing incentives Social setting and human relations Concluded New “social setting” led workers to do good job Good “Human relations” = higher productivity The contect - The Great Depression (1929-1940) Employee attitudes and groups processes Osme thinsf satisifed some workers but not others People resticited output to adhere to groups norms (Avoid layoffs) Lessons from he hawthrone stufirs Social and human concerns are keys to prductivity Hawthrone effect - People who are singled out for special attention perform as expected Maslow’s Theory of human needs Human needs The work of psychologist Abraham Maslow in the area if human “needs,” also has had a major impact in the behavioual apporach to management Maslow’s hierarchy of human needs Self actualization needs Higherst level: need foe self fulfillment to grow and use abilites to fullest and most creative extent Esteem needs Needs fro esteem in eyes of others need for respect, prestige, recognition; need for self esteem, personal sense of competence, mastery Social needs Need for love, affection, sense of belongingness in ones relationship either other people Safett needs Need for security, protection and stability in teh events of day to day life Physiological needs Most basic of all human needs: need for biological maintence; food, water and phydical well being Principles Defict principle: A satidifed need is not a motivator of behaviour Progress principles: A need becomes a motivator once the preceding lower-level need is satisfied Both principles cease to operate at self actulilzation level McGregor’s Theories Thepry x assumes that workers; Dislike work Lack ambition Are irresponsible Resist change Prefer to be led Theoyry y assumes that workers are Willing to work Willing to accept responsibility Capable of self control Capable of self direction Imaginative and creative According to McGregor, Managers create: Self fulfilling prophecies Implications of Theory x and y Theory x managers: Create situations where workers become dependent, passive and reluctant Theory y managers create situations where workers respond with initiative and high performance Central to notions of empowerment and self management Argyris’s theory of adult personality Classical management principles and practices inhibit worker maturation and are inconsistent with the mature adult personality Management practices should accommodate the mature personality: Increasing task responsibility Increasing task variety Using participative decision making Modern Management Foundation Quantitative analysis and Tools Analytics: the use of large data bases and mathematics to solve problems and make informed decision using systematic analysis Organization as systems System Collection of interrelated parts that function together to achieve a common purpose Subsystem A smaller component of a larger system Open systems Organisations that interact with their environment Contingency thinking Tires to maths managerial responses with problem (situation) No “one best way” to manage The “appropriate way to to manage depends on the situations Quality management Qality anc competitive advantafe are linked Total quality managment (TQM) Comprehensive approach to contiou impovment on teh entire organization ISO certification Gloval quality management standards Refine and upgrade quality to meet ISO requirments Evidednce Based Managment Making management decision on “hard facts” about what really works Multiple Choice Questions A6. You’ve hired a third-party to gather information about your company’s servers and data. The third-party will not have direct access to your internal network but can gather information from any other source. Which of the following would BEST describe this approach? ❍ A. Backdoor testing ❍ B. Passive footprinting ❍ C. OS fingerprinting ❍ D. Partially known environment A7. Which of these protocols use TLS to provide secure communication? (Select TWO) ❍ A. HTTPS ❍ B. SSH ❍ C. FTPS ❍ D. SNMPv2 ❍ E. DNSSEC ❍ F. SRTP A8. Which of these threat actors would be MOST likely to attack systems for direct financial gain? ❍ A. Organized crime ❍ B. Hacktivist ❍ C. Nation state ❍ D. Competitor A9. A security incident has occurred on a file server. Which of the following data sources should be gathered to address file storage volatility? (Select TWO) ❍ A. Partition data ❍ B. Kernel statistics ❍ C. ROM data ❍ D. Temporary file systems ❍ E. Process table Quick Answer: 33 The Details: 43 Quick Answer: 33 The Details: 44 Quick Answer: 33 The Details: 45 Quick Answer: 33 The Details: 46 6 Practice Exam A - Questions A10. An IPS at your company has found a sharp increase in traffic from all-in-one printers. After researching, your security team has found a vulnerability associated with these devices that allows the device to be remotely controlled by a third-party. Which category would BEST describe these devices? ❍ A. IoT ❍ B. RTOS ❍ C. MFD ❍ D. SoC A11. Which of the following standards provides information on privacy and managing PII? ❍ A. ISO 31000 ❍ B. ISO 27002 ❍ C. ISO 27701 ❍ D. ISO 27001 A12. Elizabeth, a security administrator, is concerned about the potential for data exfiltration using external storage drives. Which of the following would be the BEST way to prevent this method of data exfiltration? ❍ A. Create an operating system security policy to prevent the use of removable media ❍ B. Monitor removable media usage in host-based firewall logs ❍ C. Only allow applications that do not use removable media ❍ D. Define a removable media block rule in the UTM Quick Answer: 33 The Details: 47 Quick Answer: 33 The Details: 48 Quick Answer: 33 The Details: 49 Practice Exam A - Questions 7 A13. A CISO (Chief Information Security Officer) would like to decrease the response time when addressing security incidents. Unfortunately, the company does not have the budget to hire additional security engineers. Which of the following would assist the CISO with this requirement? ❍ A. ISO 27701 ❍ B. PKI ❍ C. IaaS ❍ D. SOAR A14. An insurance company has created a set of policies to handle data breaches. The security team has been given this set of requirements based on these policies: • Access records from all devices must be saved and archived • Any data access outside of normal working hours must be immediately reported • Data access must only occur inside of the country • Access logs and audit reports must be created from a single database Which of the following should be implemented by the security team to meet these requirements? (Select THREE) ❍ A. Restrict login access by IP address and GPS location ❍ B. Require government-issued identification during the onboarding process ❍ C. Add additional password complexity for accounts that access data ❍ D. Conduct monthly permission auditing ❍ E. Consolidate all logs on a SIEM ❍ F. Archive the encryption keys of all disabled accounts ❍ G. Enable time-of-day restrictions on the authentication server Quick Answer: 33 The Details: 50 Quick Answer: 33 The Details: 51 8 Practice Exam A - Questions A15. Rodney, a security engineer, is viewing this record from the firewall logs: UTC 04/05/2018 03:09:15809 AV Gateway Alert 136.127.92.171 80 -> 10.16.10.14 60818 Gateway Anti-Virus Alert: XPACK.A_7854 (Trojan) blocked. Which of the following can be observed from this log information? ❍ A. The victim's IP address is 136.127.92.171 ❍ B. A download was blocked from a web server ❍ C. A botnet DDoS attack was blocked ❍ D. The Trojan was blocked, but the file was not A16. A user connects to a third-party website and receives this message: Your connection is not private. NET::ERR_CERT_INVALID Which of the following attacks would be the MOST likely reason for this message? ❍ A. Brute force ❍ B. DoS ❍ C. On-path ❍ D. Disassociation A17. Which of the following would be the BEST way to provide a website login using existing credentials from a third-party site? ❍ A. Federation ❍ B. 802.1X ❍ C. PEAP ❍ D. EAP-FAST Quick Answer: 33 The Details: 53 Quick Answer: 33 The Details: 54 Quick Answer: 33 The Details: 55 Practice Exam A - Questions 9 A18. A system administrator, Daniel, is working on a contract that will specify a minimum required uptime for a set of Internet-facing firewalls. Daniel needs to know how often the firewall hardware is expected to fail between repairs. Which of the following would BEST describe this information? ❍ A. MTBF ❍ B. RTO ❍ C. MTTR ❍ D. MTTF A19. An attacker calls into a company’s help desk and pretends to be the director of the company’s manufacturing department. The attacker states that they have forgotten their password and they need to have the password reset quickly for an important meeting. What kind of attack would BEST describe this phone call? ❍ A. Social engineering ❍ B. Tailgating ❍ C. Watering hole ❍ D. On-path A20. A security administrator has been using EAP-FAST wireless authentication since the migration from WEP to WPA2. The company’s network team now needs to support additional authentication protocols inside of an encrypted tunnel. Which of the following would meet the network team’s requirements? ❍ A. EAP-TLS ❍ B. PEAP ❍ C. EAP-TTLS ❍ D. EAP-MSCHAPv2 Quick Answer: 33 The Details: 56 Quick Answer: 33 The Details: 57 Quick Answer: 33 The Details: 58 10 Practice Exam A - Questions A21. Which of the following would be commonly provided by a CASB? (Select TWO) ❍ A. List of all internal Windows devices that have not installed the latest security patches ❍ B. List of applications in use ❍ C. Centralized log storage facility ❍ D. List of network outages for the previous month ❍ E. Verification of encrypted data transfers ❍ F. VPN connectivity for remote users A22. The embedded OS in a company’s time clock appliance is configured to reset the file system and reboot when a file system error occurs. On one of the time clocks, this file system error occurs during the startup process and causes the system to constantly reboot. Which of the following BEST describes this issue? ❍ A. DLL injection ❍ B. Resource exhaustion ❍ C. Race condition ❍ D. Weak configuration A23. A recent audit has found that existing password policies do not include any restrictions on password attempts, and users are not required to periodically change their passwords. Which of the following would correct these policy issues? (Select TWO) ❍ A. Password complexity ❍ B. Password expiration ❍ C. Password history ❍ D. Password lockout ❍ E. Password recovery Quick Answer: 33 The Details: 59 Quick Answer: 33 The Details: 60 Quick Answer: 33 The Details: 61 Practice Exam A - Questions 11 A24. What kind of security control is associated with a login banner? ❍ A. Preventive ❍ B. Deterrent ❍ C. Corrective ❍ D. Detective ❍ E. Compensating ❍ F. Physical A25. A security team has been provided with a noncredentialed vulnerability scan report created by a thirdparty. Which of the following would they expect to see on this report? ❍ A. A summary of all files with invalid group assignments ❍ B. A list of all unpatched operating system files ❍ C. The version of web server software in use ❍ D. A list of local user accounts A26. A business manager is documenting a set of steps for processing orders if the primary Internet connection fails. Which of these would BEST describe these steps? ❍ A. Communication plan ❍ B. Continuity of operations ❍ C. Stakeholder management ❍ D. Tabletop exercise A27. A security administrator is concerned about data exfiltration resulting from the use of malicious phone charging stations. Which of the following would be the BEST way to protect against this threat? ❍ A. USB data blocker ❍ B. Personal firewall ❍ C. MFA ❍ D. FDE Quick Answer: 33 The Details: 62 Quick Answer: 33 The Details: 63 Quick Answer: 33 The Details: 64 Quick Answer: 33 The Details: 65 12 Practice Exam A - Questions A28. A company would like to protect the data stored on laptops used in the field. Which of the following would be the BEST choice for this requirement? ❍ A. MAC ❍ B. SED ❍ C. CASB ❍ D. SOAR A29. A file server has a full backup performed each Monday at 1 AM. Incremental backups are performed at 1 AM on Tuesday, Wednesday, Thursday, and Friday. The system administrator needs to perform a full recovery of the file server on Thursday afternoon. How many backup sets would be required to complete the recovery? ❍ A. 2 ❍ B. 3 ❍ C. 4 ❍ D. 1Plăcile de rețea (Network Interface Cards-NICs) conectează un echipament la rețea. Plăcile de rețea Ethernet sunt folosite pentru o conexiune cablată, în timp ce plăcile de rețea WLAN (Wireless Local Area Network) sunt folosite pentru wireless. Un echipament cu utilizator final ar putea include unul sau ambele tipuri de plăci de rețea. De exemplu, o imprimantă de rețea poate avea doar o placă de rețea Ethernet, așadar, trebuie să se conecteze la rețea printr-un cablu Ethernet. Alte echipamente, precum tabletele sau telefoanele pot conține o placă de rețea WLAN și trebuie să folosească o conexiune wireless. Layer-ul Fizic Layer-ul fizic de la OSI furnizează mijloacele de transport a biților care realizează un frame de data link în mediul de rețea. Acest layer acceptă un frame complet de la layer-ul data link și îl codifică sub forma unor serii de semnale care sunt transmise în mediul local. Biții codificați care comprimă un frame sunt primiți fie de un echipament final, fie de unul intermediar. Procesul prin care trec datele de la nodul sursă la nodus destinație este: • Datele utilizatorului sunt segmentate de layer-ul transport, plasate în pachete de către layer-ul rețea, iar apoi încapsulate sub formă de frame-uri de către layer-ul data link. • Layer-ul fizic codifică frame-urile și creează semnalele undelor electrice, optice și radio care reprezintă biții în fiecare frame. • Aceste semnale sunt trimise în mediu pe rând. • Nodul destinație preia aceste semnale individuale de la nivelul fizic, le transformă în reprezentare binară și transmit biții la nivelul superior, data link, sub forma unui frame. Mediul layer-ului Fizic Există trei forme de bază ale mediului de rețea. Layer-ul fizic produce reprezentarea și gruparea biților pentru fiecare mediu, după cum urmează: • Cablu de cupru: Semnalele sunt modele ale pulsurilor electrice. • Cablul cu fibră optică: Semnalele sunt modele de lumină. • Wireless: Semnalele sunt modele ale transmisiunilor cu microunde. Figura afișează exemple de semnalizare pentru cupru, fibră optică și wireless. Pentru a activa interoperabilitatea layer-ului fizic, toate aspectele acestor funcții sunt guvernate de organizațiile de standardizare. Standardele Layer-ului Fizic Protocoalele și operațiile layerelor superioare din OSI sunt efectuate în software proiectat de ingineri și oameni de știință. De exemplu, serviciile și protocoalele din suita TCP/IP sunt definite de Internet Engineering Task Force (IETF) în RFC-uri așa cum se arată în Figura 1. Layer-ul fizic constă în circuite electronice, mediu și conectori dezvoltați de ingineri. Așadar, este corespunzător ca standardele care guvernează acest hardware să fie definite de orgnizațiile relevante din domeniul ingineriei și electronicii. Există mai multe organizații naționale și internaționale diferite, organizații guvernamentale de reglementare și companii private implicate în stabilirea și menținerea standardelor layer-ului fizic. De exemplu, hardware-ul layer-ului fizic, mediul, codificarea și standardele de semnalizare sunt definite și guvernate de către: • International Organization for Standardization (ISO) • Telecommunications Industry Association/Electronic Industries Association (TIA/EIA) • International Telecommunication Union (ITU) • American National Standards Institute (ANSI) • Institute of Electrical and Electronics Engineers (IEEE) • Autoritățile de reglementare națională a telecomunicațiilor, inclusiv Federal Communication Commission (FCC) din USA și European Telecommunications Standards Institute (ESTI) Pe lângă acestea, există grupuri de standardizare a cablărilor regionale precum CSA (Canadian Standards Association), CENELEC (European Committee for Electrotechnical Standardization) și JSA/JSI (Japanese Standards Association), care dezvoltă specificații locale. Figura 2 listează contribuitorii principali și câteva standarde relevante ale layer-ului fizic.