Notes, summaries, assignments, exams, and problems

Un Chien Andalou: The First Surrealist Film

Considered the definitive first surrealist film, Un Chien Andalou is a short work composed of seemingly unrelated images. It was created by Luis Buñuel in collaboration with his friend Salvador Dalí. Despite the title, there is no dog, nor is it Andalusian. The film unfolds in an unknown space, devoid of personal character development or temporal markers.

The Mechanics of Dream Logic

The film employs a unique narrative structure: it ignores linear time and utilizes abysmal jumps. For instance, the protagonist reverts to childhood without physical change when punished while holding books. The images appear as they do in dreams: disjointed, representing inner fears, impossible memories, and Freudian

Pulmonary Ventilation and Gas Exchange

Pulmonary ventilation: This is the mechanism through which the air in the lungs and the respiratory tract is renewed. It allows air to flow in and out of the lungs. Ventilation is carried out through two respiratory movements: inhalation and exhalation. The diaphragm and the intercostal muscles mainly participate in these movements. By contracting and relaxing, these muscles produce changes in the volume of the lungs.

Inhalation

This is the movement that allows air to enter the lungs.

1. The diaphragm contracts, increasing the vertical diameter of the thoracic cavity.
2. The external intercostal muscles contract. The diameters of the thoracic cavity increase.
3. The lungs, which are elastic, expand.

Exhalation

This is... Continue reading "Human Physiology: Respiratory and Renal System Functions" »

Chapter 1: Basic Securities

Common stock represents an ownership interest, usually purchased for growth and solid returns over time. It is the most junior security, and income may be generated through dividends if declared by the Board of Directors (BOD), which are typically paid quarterly.

• Defensive stocks: Low returns, conservative, less volatile (e.g., utilities or consumer staples).
• Blue chip stocks: Consistent dividends, large-cap stocks.
• Value stocks: Underpriced with higher risk and higher returns.
• Growth stocks: Higher-than-average returns with higher risk (e.g., tech or biotech).
• Mid-cap stocks: Moderate returns.
• Speculative stocks: Small-cap or micro-cap, very risky (e.g., penny stocks/OTC stocks).

Preferred Stock: An ownership interest senior... Continue reading "Series 6 Exam Preparation Essentials" »

Nitrogen Fixation and Symbiosis

Module 3: N₂ + 8e^- + 8H⁺ + 16ATP → 2NH₃ + H₂. Nitrogenase is killed by O₂; leghemoglobin binds O₂ (pink), nodules block O₂, and high respiration lowers free O₂. The plant provides sugars while rhizobia fix N₂. High N levels lead to glutamate, while low N levels lead to glutamine. Plant flavonoids trigger bacterial Nod factors (LPS signals) to initiate symbiosis. Root hair curls (“shepherd’s crook”) trap bacteria and start nodule formation.

Archaea: Biology and Genomics

Archaea: Once thought to be only extremophiles, they are actually ubiquitous. Identified via 16S rRNA (distinct from bacteria and eukaryotes). Methanogens: Only archaea perform methanogenesis, the terminal step of the C-cycle and a source... Continue reading "Microbiology Fundamentals: From Microbial Ecology to Genomics" »

Understanding the Sentence

A sentence is a unit of meaning that conveys a message with a complete verb form and subject-predicate structure. It possesses syntactic independence, meaning it is not part of a larger syntactic unit.

Elements of a Compound Sentence

• Propositions: Two sentence structures consisting of a subject and a predicate.
• Link: A connector joining the two propositions.

Classification of Compound Sentences

• Coordinated: Maintains a relationship of equality. If separated, they function independently (syntactic autonomy) and are connected by a coordinating link.
• Subordinate: A relationship of dependency where the proposition cannot act as an independent sentence. These are linked by a subordinating conjunction and function as nouns, adjectives,

Josep Vicenç Foix (1893–1987)

Josep Vicenç Foix is a complex figure, difficult to classify, often labeled as avant-garde, post-symbolist, or Noucentista. His subjects are distributed across his books, written in a variety of shapes, styles, and techniques that blend avant-garde and classical literary traditions.

Work: Sun and Mourning (1947)

Topic: The protagonist experiences disorientation in nature, perceiving it as an innate land. Though the author feels lost and alone, he immediately recognizes the landscape of a thousand years ago; nothing seems strange, and he rediscovers the countryside where he walks. The space where the poem is set is where he feels lost and lonely due to the elements of nature.

Structure: A sonnet consisting of two... Continue reading "J.V. Foix: Analysis of Sun and Mourning and Key Poems" »

The Middle Ages: From Rome to the 15th Century

The Middle Ages began in 476 with the disintegration of the Western Roman Empire and ended in the 15th century with the fall of the Byzantine Empire to the Ottoman Turks in 1453. Christian culture was emphasized by the Byzantine and Carolingian Empires, while Muslim culture spread west to North Africa and much of the Iberian Peninsula following the teachings of Muhammad.

The Byzantine Empire

Justinian the Great concentrated his efforts on the recovery of lost territories: Italy from the Goths, North Africa from the Vandals, and the south and southeast of the Iberian Peninsula from the Visigoths.

Byzantine Organization

• Centralized Power: Political and military authority were unified.
• Religious Control:

Professional and Military Terminology

• Personnel Officer: A worker responsible for recruiting employees and dealing with matters relating to them.
• Aboard: On or onto a ship, aircraft, bus, or train.
• USS Ranger: The third of four Forrestal-class supercarriers built for the United States Navy in the 1950s.
• Discharge: Official permission to leave the armed forces, a prison, or a hospital.
• Reassignment: The act of giving someone a different job or position.
• Paperwork: The written records connected with a particular job, deal, or journey.
• To discharge somebody for something: To be officially allowed or forced to leave an institution such as a hospital, a prison, or the army.

Social and Personal Definitions

• Elder: An older person, especially one with a respected

Al-Andalus: The Muslim Conquest

In the 8th century, the Arabs began their conquest of the Iberian Peninsula. The weakness of the Visigoths allowed them to easily seize the territory, creating the lasting legacy of Al-Andalus.

The Expansion of Islam

In 711, the Arab invasion began. It was very fast, taking advantage of internal conflicts within the Visigothic monarchy, and faced little armed resistance.

• Phase 1: When Muslims realized the weakness of the Visigothic state, they formed a new army under the command of Musa and Tariq. They toured the peninsula with minimal fighting. By 716, most of the territory had been conquered, and Visigothic nobles accepted covenants that ensured their land ownership.
• Phase 2: The hardest phase occurred between 716

Supervised Classification

Logistic Regression (LR)

• Type: Classification (binary only)
• Scaling: YES (StandardScaler)
• Outliers: NOT robust
• Categorical Variables: NO (encode first)
• Idea: Sigmoid function → probability 0–1 → if ≥ 0.5 → class 1
• Advantages: Fast, simple, interpretable, outputs probabilities
• Disadvantages: Binary only, needs linear boundary, fails non-linear data
• Metrics: Accuracy, Precision, Recall, F1, Confusion Matrix

Decision Trees (DT)

• Type: Classification + Regression
• Scaling: NO (never needs it)
• Outliers: Robust
• Categorical Variables: YES
• Idea: IF-ELSE splits by feature → leaf = final prediction
• Advantages: Interpretable, no scaling, handles any data type, fast
• Disadvantages: Overfits easily, sensitive to small changes
• Metrics: Gini,