Assessments part 1 peds

Research Methods

• Primary and secondary methods are used in research
• Surveys can be completed in person, online, or via telephone to gather quantitative or qualitative data
• Interviews are useful to collect detailed qualitative insights from an individual
• Focus groups are a form of qualitative research where a group of people are asked about their perceptions, opinions, beliefs, and attitudes towards a product, service, concept, advertisement, idea, or packaging
• Observations are used to collect data on naturally occurring behavior in its usual context
• Experiments involve manipulating one variable to determine if it causes changes in another variable
• Literature reviews give an overview of what has been studied, published, and written on a specific topic
• Data analysis is a process of inspecting, cleansing, transforming, and modeling data with the goal of discovering useful information, informing conclusions, and supporting decision-making
• Online research refers to collecting information from the internet for research purposes

Sampling Methods

• Probability sampling techniques involve random selection
• Simple random sampling gives each member of the population an equal chance of being selected
• Stratified random sampling divides the population into subgroups and then randomly samples from each group
• Cluster random sampling divides the population into clusters, randomly selects some clusters, and then samples all members within the selected clusters
• Systematic random sampling selects every nth member from a list
• Non-probability sampling techniques do not involve random selection
• Convenience sampling selects participants that are easily accessible
• Quota sampling sets quotas for each category of participant
• Purposive sampling is when the researcher uses their own judgment to select participants
• Snowball sampling is when existing study subjects recruit future subjects from among their acquaintances

Data Analysis

• Quantitative data analysis involves numerical or statistical analysis to quantify the data and make generalizations
• Statistical analysis is a component of data analytics
• Regression analysis is a set of statistical methods used for the estimation of relationships between a dependent variable and one or more independent variables
• Hypothesis testing is a statistical method that is used in making statistical decisions using experimental data
• Qualitative data analysis involves interpreting non-numerical data, such as text, audio, and video
• Content analysis is a research technique used to make replicable and valid inferences by interpreting and coding textual material
• Thematic analysis is used for identifying, analyzing, and interpreting patterns of meaning ("themes") within qualitative data
• Narrative analysis uses stories and personal accounts researched or told by an individual

Static Electricity: Charging

• Static electricity involves the accumulation of electric charge on the surface of a material
• Materials can become charged through friction, induction or contact
• Friction occurs when materials rub together, electrons are transferred
• Gaining electrons results in a negative charge
• Losing electrons results in a positive charge
• An electric field is created around a charged object
• The field's strength is greatest nearest the charged object
• Electric field lines point from positive to negative charges
• Induction occurs when a charged object brings a charge in another object without contact
• A positive object attracts negative charges
• A negative object repels negative charges
• Earthing is connecting a charged object to the earth to allow charge flow
• Earthing removes excess charge

Static Electricity: Dangers

• Fuel flowing through pipes generates charge via friction
• This can cause sparks that could ignite the fuel
• Pipelines are earthed to prevent charge build-up
• Rain clouds become charged from friction between ice particles and air
• Negative cloud bottoms induce positive charges on the ground
• When the charge is high enough lightning strikes
• Aircraft flying through air experience friction charging
• Aircraft static can interfere with communication equipment
• Static dischargers on wings remove excess charge

Static Electricity: Uses

• Electrostatic precipitators filter dust and smoke in chimneys
• Dust particles gain a negative charge passing through a grid
• Charged particles stick to positive plates
• Plates shaken to remove collected dust
• Photocopiers use static electricity to copy documents
• The drum receives a positive charge
• The image projects onto the drum and reduces charge
• Toner (black powder) gets a negative charge and sticks to positive drum areas
• The paper receives positive charge and toner is transferred
• Toner is fused by heat
• Spray painting
• The object receives a negative charge
• The paint receives a positive charge
• Paint is attracted to the object

Static Electricity: Equations

• Key equations are used to quantify static electricity phenomena
• The electrical charge equation is $Q = l*t$
• Q is the charge measured in Coulombs (C)
• I is the current measured in Amperes (A)
• t is time measured in seconds (s)
• Electric field equations is $E = \frac{kQ}{r^2}$
• E is the electric field strength measured in Newtons per Coulomb (N/C)
• k is Coulomb's constant (8.99 x 10^9 Nm^2C^{-2})
• Q is the charge measured in Coulombs (C)
• r is the distance from the charge measured in meters (m)
• $F = \frac{kQq}{r^2}$ is used to calculate electrostatic force (N)
• Here, Q and q are quantities of charge (C)
• r is the distance measures between charges (m)

Measuring CPU Performance

• The importance of CPU performance metrics, performance counters, and the perf tool in analyzing CPU performance
• You can improve your understanding how a CPU's microarchitecture affects performance

CPU Performance Metrics

• Clock Rate: Measures how fast a CPU executes instructions, in Hertz (Hz)
• a higher clock rate means better performance but this is only one factor among others
• Instructions Per Cycle (IPC): The average number of instructions a CPU executes in a single clock cycle
• Higher IPC indicates a more efficient CPU architecture
• Cache Miss Rate: the percentage of times the CPU needs to access main memory because required data isn't in the cache
• Higher cache miss rates significantly degrade performance

Performance Counters

• Special-purpose registers in modern CPUs that count hardware events
• Measure instructions executed, clock cycles, and cache misses
• Provide detailed information about CPU performance to identify bottlenecks
• Key counters include cycles for the number of clock cycles
• instructions for the number of instructions executed
• cache-references for the number of cache accesses made
• cache-misses for the number of cache misses

Perf Tool

• perf is a command-line tool in Linux used for performance analysis
• Allows monitoring performance counters
• Enables profiling code and tracing system events and optimizing CPU performance
• Three basic perfcommands include:
• perf stat: Reports performance counter statistics for a given command
• perf record: Records performance counter data for a given command
• perf report: Analyzes performance counter data recorded by perf record

Motion and Force: Forces

• Types of forces
• Contact
• Normal force ($\vec{N}$) is perpendicular to the surface of contact
• Tension force ($\vec{T}$) is transmitted through a string, rope, cable, or wire when it is pulled tight by forces acting from opposite ends
• Friction force ($\vec{f}$) opposes motion (static and kinetic)
• Applied force ($\vec{F}_{app}$) is a force that is applied to an object by a person or another object
• Field
• Gravity ($\vec{F}_{g}$) is the universal force of attraction between all matter
• Electric force ($\vec{F}_{e}$) is the attraction or repulsion between charged particles
• Magnetic force ($\vec{F}_{m}$) is the force exerted on magnets and moving charges

Motion and Force: Combining Forces

• Forces are vectors.
• Use vector addition to find net force.
• The net or resultant force is $\vec{F}{net} = \vec{F}{1} + \vec{F}_{2} +...$

Motion and Force: Newton's Laws

• Newton's First Law: "Law of Inertia"- an object will remain in a state of rest or constant velocity unless acted upon by a net external force, $\vec{v} = constant$
• Newton's Second Law $\vec{F}_{net} = m\vec{a}$
• Newton's Third Law "Action-Reaction"- If object 1 and object 2 interact, the force exerted by object 1 on object 2 is equal in magnitude and opposite in direction to the force exerted by object 2 on object 1, $\vec{F}{12} = -\vec{F}{21}$

Motion and Force: Inertia and Mass

• Inertia is an object's tendency to resist velocity changes
• Mass measures an object's resistance to velocity changes
• Mass is a scalar quantity
• Mass is an intrinsic property of an object
• Mass is not weight
• Kilogram (kg) is the SI unit for mass

Motion and Force: Other Forces

• Gravitational Force (Weight), $F_{g} = mg$
• g = 9.8 m/s^2 on Earth
• Weight isn't intrinsic
• Location determines weight (location determines g)
• Weight is a force
• Mass and weight are separate
• Normal Force is a contact force exerted by a surface
• The normal force is perpendicular to the surface
• The normal force isn't always the object's weight

Motion and Force: Free Body Diagrams

• To create free body diagrams:
• Draw a diagram of the object(s) of interest.
• Draw forces acting on the object.
• Only forces acting on the object
• Indicate force magnitudes and directions.
• Resolve forces into components.
• Apply Newton's Second Law in component form.
• $\sum F_{x} = ma_{x}$
• $\sum F_{y} = ma_{y}$

Detecting Phony News Stories

• Phony news deceives and misleads
• Can slant public opinion and agendas
• Uses sensational, dubious, or manufactured headlines
• Investigate the reporting source to ensure it is known and reputable
• Read past the fabricated headlines and sensational claims, to properly understand it
• Check the credibility and expertise of the author
• Consider supporting evidence, facts, sources, and links
• Verify publication date for relevancy
• Critical thought and contemplation are useful
• Check reputable fact-checkers
• Never share and always report

Relational Algebra: Introduction

• Relational algebra is a foundational query language
• Serves as basis for relational database management systems (RDBMS)
• Key characteristics
• Formal: Based on strong math foundations like set theory
• Procedural: Describes how to assess a query

Relational Algebra: Key Components

• Relations are sets of tuples (rows) sharing a stricture (attributes)- like tables
• Relation Schema specifies a relation's name, attribute names, and data types
• Example: Etudiant(nom: string, age: integer, adresse: string)
• Relation Instance is a set of tuples that adhere to the relation schema
• Example includes a table with name, age, and address columns

Relational Algebra: Basic Operators

• Core set of functions used to manipulate and retrieve data from relations
• Includes Selection, Projection, Union, Set Difference, Cartesian Product, and Rename

The Selection Operator

• The symbol for Selection is $\sigma$
• Selection identifies tuples within a relation that meet a given predicate
• It uses the syntax, $\sigma_{predicat}(relation)$
• The Predicate is a conditional expression consisting of logical (\land, \lor, \lnot) and comparative operators (=, $\neq$, , $\le$, $\ge$).
• The example $\sigma_{age > 20}(Etudiant)$ shows the selection of students older than 20

The Projection Operator

• Projects identifies specific attributes from a relation and includes the symbol $\Pi$
• It uses the syntax $\Pi_{attribut1, attribut2,...}(relation)$
• The result will contain the specified attributes from the relation
• Duplicates are removed
• The example $\Pi_{nom, age}(Etudiant)$ fetches student names and ages together

Set Operators

• The UNION operator is a set operator, its symbol is $\cup$
• It combines tuples from two relations while removing duplicates
• Requires that both relations have the same schema
• The Intersection operator helps to find common tuples of two relations
• The SET DIFFERENCE finds differing pairs of relations, using the symbol '-' It requires that both relations have the same schema
• Returns tuples present exclusively in the first relations

Cartesian Product Operator

• Cartesian Product is symbolized by $\times$
• Allows combinations of tuples from two relations
• Returns all possible pairings between the two
• Does not require schema compatibility
• Is rarely used directly
• Renaming Relations requires symbol $\rho$ and enables renaming relation or attribute names
• Facilitates self-joins and multiple uses of the same relation in an expression
• Renames, example $\rho_{Eleve}(Etudiant)$ helps by renaming "Etudiant" into "Eleve"

Division And Join

• Join joins related tuples from multiple relations
• Connects based on a join condition predicate
• Division finds tuples in relation 1 that relate exclusively to all tuples in relation 2
• Less frequently used, but helpful for specific needs

Jointure and Intersection

• The JOIN operator ($\Join$), is to combine tuples from two (or more) relations based on related attributes
• Uses Syntax: $relation1 \Join_{predicat} relation2$
• "predicat" is a join state comparing attributes between 2 relations
• Join operations can be expressed through Cartesian products and selections
• Different kinds of JOINS exist and include Natural, Equi, Outer

Phony News Social Media

• It is important to refrain from sharing phony news stories
• This should be reported on social platforms
• Consider the impact of each piece, and look to help prevent dissemination

Radiation from Matter for Radiative Transfer

• All matter radiates when T > 0K
• Its spectrum depends on the temperature and emittance quality
• Radiation comes as a photon (packet form) or electromagnetic waveform (wave form)

Radiative Transfer Basic Quantities

• Solid Angle $$\Omega = A/r^2$$
• A is the area
• r the radius and the units are in Steradians (sr)
• Flux $$F = \frac{dW}{dt dA}$$
• dW is energy and dt the timing. The units are in $W m^{-2}$
• Specific Intensity $$I = \frac{dW}{dt dA d\Omega \cos\theta d\nu}$$
• I is independent to distance in vacuum
• Where $dW$ is energy, $dt$ the timing. $dA$ area. $d\Omega$ solid angle, $d\nu$ the frequency and the units in $W m^{-2} sr^{-1} Hz^{-1}$
• Mean Density $$J = \frac{1}{4\pi} \int I d\Omega$$
• For isotropic is $J=I$ and the units $W m^{-2} sr^{-1} Hz^{-1}$
• Energy density $$u = \frac{1}{c} \int I d\Omega = \frac{4\pi}{c} J$$
• Measured in $J m^{-3}$
• Radiation $$P = \frac{1}{c} \int I \cos^2\theta d\Omega$$
• For isotropic the radiation pressure is $P = u/3$ and the units in $N_m^{-2}$

Radiative Transfer Blackbody

• Blackbody radiation will absorb radiation to emit radiation and is determined according to temperature.
• Planck Function $$B_\nu(T) = \frac{2h\nu^3}{c^2} \frac{1}{e^{h\nu/kT} - 1}$$
• h is Planck's constant
• c speed of light, k Boltzmann's constant, $\nu$ is frequency, $T$ the temperature
• Wien's $$\lambda_{max} = \frac{b}{T}$$
• $b \approx 2.9 \times 10^{-3} m \cdot K$
• Stefan-Boltzmann $$F = \sigma T^4$$
• $\sigma \approx 5.67 \times 10^{-8} W m^{-2} K^{-4}$ Stefan-Boltzmann constant.

Radiative Transfer Equation

$$\frac{dI}{ds} = -\alpha I + j$$

• I is the intensity, s is the distance, $\alpha$ is the absorption. j is the emission
• Optical Depth $$d\tau = \alpha ds$$ $$\tau = \int \alpha ds$$
• Rewritten $$\frac{dI}{d\tau} = -I + S$$
• For constant $S$ $$I(\tau) = I(0)e^{-\tau} + S(1 - e^{-\tau})$$ $$I(\tau) = I(0)e^{-\tau} + B_\nu(T)(1 - e^{-\tau})$$

Understanding Exposure: What is Exposure?

• Exposure is how light or dark an image is.
• Images happen when camera sensors/films are exposed to light.
• The quantity of light is based on:
• Aperture = the Lens opening size
• Shutter Speed = How long the sensor is exposed to light
• ISO = How well the sensor can detect light
• These three controls can affect exposure and is named the “Exposure Triangle.”

Understanding Exposure: Why is exposure so important?

• Correctly exposing an image is important because it determines how much detail is captured.
• Images that underexposed too dark lead to no details Images that are overexposed are too bright and will also lack detail Meter Settings
• Meter camera setting
  • A tool to assist correct exposure that reviews the metrics
• “Sunny 16” rule: a quick good starting point for a great exposure
  • On sunny days the aperture should be closed (f / 16), and your shutter speed should be the reciprocal = 1/ ISO
  • ISO 200 = 1 / 200, this is a starting point and adjustments may be needed.

Understanding Exposure: Other settings

• Exposure adjustments by hand can help in troublesome photos
  • scenes with bright and low brights
  • "+/-" symbol typically denotes exposure compensation
• Histograms:
  • graphs/exposure of visual data and image exposure
• "well exposed graph" and great data should be in center, underexposed is to the left and overexposed is to the right.

Understanding Exposure: ISO, Aperture and Shutter Speed

ISO: This is for sensor sensitivity.

• Low ISO = Less sensitive, but less noise
• High ISO = Higher sensitivity, but also image noise
• when should this be adjusted? when the aperture and shutter are “desired settings/goals”, make appropriate changes from there.
  • typical: 100-200 @Sunny, 400-800 indoor, and 1600-3200 when low lighting. Aperture is for lens opening
• The opening is the opening in the lens and will allow data through to the sensor. -f-stops is the measure here
• lower f-stop = large opening, more lighting, less depth vs higher f-spot = smaller opening, less, and large DoF. Aperture and Depth of Field relation is defined by
• depth of field is the goal, Shutter Speed is a sensor with light for data
• Seconds/part of seconds is the quantity here.
  • high shutter speed =less light but more capture low shutter speed=more lights but blurred objects and images

Rules of Inference

• Rules guide for valid arguments. and derive a conclusion from premises.
• Basic rule
• Modus Ponens, with $P \rightarrow Q$, then P, meaning Q.
• Modus Tollens, with $P \rightarrow Q$, then $\neg Q$ means $\neg P$..
• Hypothetical Syllogism, with $P \rightarrow Q$ and $Q \rightarrow R$ means $P \rightarrow R$
• Disjunctive Syllogism with $P \lor Q$ and $\neg P$ with Q
• Premise rules for addition, simplification, and conjunction

Rules of Inference: Testing

• Formal proof
• Using If it rains, then the ground is wet, AND If the ground is wet it is slippery. Meaning, if it Rains, then ground slippery
• Proof:
• $L \rightarrow M$ (Premise)
• $M \rightarrow R$ (Premise)
• $L \rightarrow R$ with reasoning

Rules of Inference: Key Notations

• $L$: It is raining
• $M$: The ground is wet
• $R$: The ground is slippery