Some experimenters speculated that invisible "fluids" were being transferred from one object to another during the process of rubbing, and that these "fluids" were able to effect a physical force over a distance.

## Saturday, 21 July 2018

### ORGANIC SYNTHESIS :-THE ROLES OF BORON AND SILICON BY SUSAN E.THOMAS

Compounds of boron and silicon play a vital role in organic synthesis and the study of their properties and reactions is an important feature of undergraduate courses in organic chemistry.

Labels:
Chemistry,
E-BOOK,
ORGANIC CHEMISTRY

## Friday, 20 July 2018

### SOLID STATE CHEMISTRY AND ITS APPLICATIONS 2ND EDITION BY ANTHONY R.WEST

Solid State Chemistry and its Applications, 2nd Edition: Student Edition is an extensive update and sequel to the bestselling textbook Basic Solid State Chemistry, the classic text for undergraduate teaching in solid state chemistry worldwide.

## Thursday, 19 July 2018

### ORDINARY DIFFERENTIAL EQUATIONS 3RD EDITION BY VLADIMIR I.ARNOL'D

"Professor Arnold has expanded his classic book to include new material on exponential growth, predator-prey, the pendulum, impulse response, symmetry groups and group actions, perturbation and bifurcation … .

### BASIC CIVIL ENGINEERING BY S S BHAVIKATTI

This subject is a mixture of many civil engineering subjects like Building Materials, Building Constructions, Surveying and Engineering Mechanics. Various books are available in these subjects including some of them by the author.

Labels:
CIVIL ENGINEERING,
E-BOOK,
Engineering

### GEOGRAPHY OF INDIA BY DHYEYA PUBLICATIONS

Our aim is to develop & nurture competitive attitude amongst student. We empower you to stay ahead a step in life by offering qualitative teaching. At DhyeyaIAs, we believe that “Geniuses are made, not born”.

### SCIENCE AND TECHNOLOGY BY DHYEYA PUBLICATIONS

Dhyeya IAS has been very successful in making potential aspirants realize their dreams which is evident from the success stories of the previous years. It is manned with qualified & experienced faculties besides especially designed study material that helps the students in achieving the desired goal.

### INDIAN NATION MOVEMENT BY DHYEYA PUBLICATIONS

Jigeesha’s History of India and Indian National Movement is a comprehensive book designed for UPSC aspirants preparing for the preliminary examinations. The text is divided into three parts—Academic Abstracts, Annexures and Question Banks.

### INDIAN POLITICS BY DHYEYA PUBLICATIONS

Jigssolanki.in is one of the fastest growing educational website spanning every field of education. One can find all types of educational stuffs for almost all requirements in the educational fields.

### INDIAN ECONOMY BY DHYEYA PUBLICATIONS

Dhyeya IAS has been very successful in making potential aspirants realize their dreams which is evident from the success stories of the previous years.

### MATHEMATICS STUDY MATERIAL PART 2 BY PLANCESS

Do you find it difficult to score high in IIT JEE Mathematics? If you are one struggling to get the answer right, switch to Plancess Mathematics Video Lectures for JEE. Our video lectures and study material focus on conceptual clarity.

### MATHEMATICS STUDY MATERIAL PART 1 BY PLANCESS

### 3D GEOMETRY NOTE BY PLANCESS

Three-dimensional space (also: 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called parameters) are required to determine the position of an element (i.e., point). This is the informal meaning of the term dimension.

## Wednesday, 18 July 2018

### MCGRAW HILL PHYSICS 12

McGraw-Hill Ryerson Physics 12 is a NEW resource written specifically for the Ontario Physics, Grade 12 University Preparation course (SPH4U). The student text's clear explanations and diagrams, as well as its many excellent Problem tips, Sample, Practice and Conceptual Problems, and labs, ensure a solid grasp of the concepts and skills essential for university-bound students.

### VECTORS NOTE BY PLANCESS

A vector is what is needed to "carry" the point A to the point B; the Latin word vector means "carrier". It was first used by 18th century astronomers investigating planet rotation around the Sun. The magnitude of the vector is the distance between the two points and the direction refers to the direction of displacement from A to B.

### PROBABILITY NOTE BY PLANCESS

Probability is the measure of the likelihood that an event will occur. Probability is quantified as a number between 0 and 1, where, loosely speaking, 0 indicates impossibility and 1 indicates certainty. The higher the probability of an event, the more likely it is that the event will occur.

### AREA UNDER THE CURVE AND LINEAR PROGRAMING NOTE BY PLANCESS

The technique of linear programming is a very powerful and widely applied numerical method. In general, chemists have not made use of this tool. Here we present a simple example which shows the superiority of a linear programming based fitting process over that of the weighted or unweighted least squares formulation.

### ELLIPSE NOTE BY PLANCESS

In mathematics, an ellipse is a curve in a plane surrounding two focal points such that the sum of the distances to the two focal points is constant for every point on the curve. As such, it is a generalization of a circle, which is a special type of an ellipse having both focal points at the same location.

## Tuesday, 17 July 2018

### BEGINNING PARTIAL DIFFERENTIAL EQUATIONS 3RD EDITION BY PETER V.O'NEIL

Beginning Partial Differential Equations, Second Edition provides a comprehensive introduction to partial differential equations (PDEs) with a special focus on the significance of characteristics, solutions by Fourier series, integrals and transforms, properties and physical interpretations of solutions, and a transition to the modern function space approach to PDEs.

### MATRICES NOTE BY PLANCESS

Applications of matrices are found in most scientific fields. In every branch of physics, including classical mechanics, optics, electromagnetism, quantum mechanics, and quantum electrodynamics, they are used to study physical phenomena, such as the motion of rigid bodies.

### DETERMINANTS NOTE BY PLANCESS

In linear algebra, the determinant is a value that can be computed from the elements of a square matrix. The determinant of a matrix A is denoted det(A), det A, or |A|. Geometrically, it can be viewed as the scaling factor of the linear transformation described by the matrix.

### MODERN METHODS OF ORGANIC SYNTHESIS BY W.CARRUTHERS IAIN COLDHAM

Covering modern methods in organic synthesis, the fourth edition of this well-known textbook demonstrates their value, scope and use in the synthesis of complex molecules.

Labels:
Chemistry,
E-BOOK,
ORGANIC CHEMISTRY

### BASIC MATHEMATICS NOTE BY PLANCESS

Basic mathematics, pre-algebra, geometry, statistics, and algebra skills are what this website will teach you. It is designed for anyone who needs a basic to advanced understanding of mathematics concepts and operations.

### MATHEMATICAL REASONING AND STATISTICS NOTE BY PLANCESS

The focus of this chapter is on the nature of mathematical and statistical reasoning. The chapter begins with a description of the general nature of human reasoning. This is followed by a description of mathematical reasoning as described by mathematicians along with recommendations by mathematics educators regarding educational experiences to improve mathematical reasoning.

### PAPPA TAMNE NAHI SAMJAY FREE DOWNLOAD

A movie about a special bond between a father and his child and the emotional bond that swings about throughout the movie. 'Papa Tamne Nai Samjaay 'is a full on entertainer which has comedy, drama and emotions that will not moisten your eyes but it has the emotional values which is very well blended with the comedy.

Labels:
GUJARATI DRAMA & FILM,
MOVIE

## Monday, 16 July 2018

### HETEROCYCLIC CHEMISTRY AT A GLANCE BY JOHN A .JOULE KEITH MILLS

Heterocyclic chemistry is a central part of organic chemistry and biochemistry, dealing with a particular set of chemical structures; organic compounds with a ring structure containing at least one heteroatom (commonly nitrogen, oxygen or sulfur).

### SOLVED PRACTICAL PROBLEMS IN FLUID MECHANICS BY CARL J SCHASCHKE

Based on the principle that many students learn more effectively by using solved problems, Solved Practical Problems in Fluid Mechanics presents a series of worked examples relating fluid flow concepts to a range of engineering applications.

### QUANTITATIVE APTITUDE BY R.S AGGARWAL

The Quantitative Aptitude For Competitive Examinations by R.S. Aggarwal is a handbook of mathematical questions covering the extensive syllabi taken into consideration by most public competitive examinations held in the country every year.

Labels:
E-BOOK,
Maths,
QUANTITATIVE APTITUDE,
REASONING

### A MODERN APPROACH TO VERBAL & NON VERBAL REASONING BY R.S. AGGARWAL

This revised edition of A Modern Approach to Verbal & Non-Verbal Reasoning, while retaining the key strengths and structure of the previous edition, brings to the readers additional questions from various competitive examinations as per the latest pattern and trends.

Labels:
QUANTITATIVE APTITUDE,
REASONING,
RRB,
SBI

### A MODERN APPROACH TO VERBAL REASONING BY R.S AGGARWAL

The book, 'A Modern Approach to Verbal Reasoning (FULLY SOLVED)’ is a very effective study material for students who are preparing for various competitive exams. 'Verbal Reasoning’ is an important aspect of all competitive exams and this book helps students in understanding and studying topics related to verbal reasoning.

Labels:
MBA,
QUANTITATIVE APTITUDE,
REASONING,
RRB,
SBI

### NITOVATOR'S ACADEMY OF EXCELLENCE:- FOR FREE EDUCATION

A mission to reach out, a mission to provide education with a vision, 4 students from different NIT's took the initiative and bought you NITovators.

## Saturday, 14 July 2018

### INORGANIC CHEMISTRY BY JAMES HUHEEY,ELLEN A KEITER.RICHARD L.KEITER

Its user-friendly approach and straightforward slant, patterned on professional literature, gives students a comprehensive look at the discipline and introduces them to such exciting topics as bioinorganic chemistry and solid state chemistry.

Labels:
Chemistry,
E-BOOK,
INORGANIC CHEMISTRY

### GENOMES-3 BY T A BROWN

This is a superb textbook for modern molecular biology. The approach to the subject is significantly new and improved over Watson et al.’s Molecular Biology of the Gene and the material is categorically up-to-date.

### OXFORD GRAMMAR SPECTRUM 3

Spectrum Grammar introduz e pratica os tÃ³picos gramaticais relevantes para seu nÃvel. Grammar Spectrum 2 e 3 tambÃ©m reve e consolida regras introduzidas ao nÃvel anterior. GravaÃ§Ãµes foram especialmente preparadas pela BBC para a Universidade de Cambridge Examinations Syndicate local e incluem transmissÃ£o BBC autÃªntico.

### OXFORD GRAMMAR SPECTRUM 1:-ENGLISH RULES AND PRACTICE BY KEN PATERSON

This Oxford Grammar English Workbook is designed to consolidate and increase your knowledge of grammar concepts. This book includes activities, stimulus pages and authentic text extracts so that you can see grammar being used in everyday language applications.

### LUCENT'S SAMANY HINDI

Various competitive exams have general knowledge as an integral subject. Plus the extensive scope of this subject makes it difficult for students who are preparing for competitive exams.

### RELATIONS AND FUNCTIONS NOTE BY PLANCESS

This topic “Relations and Functions” is a foundation or fundamental of algebra in mathematics. Relations and functions are two different words having different meaning mathematically. Many us you might be confused in their difference. We shall study both these concepts in detail here.

### SAHI HINDI SUNDER HINDI BY VIJAY AGGARWAL

Dr. history . Vijay Aggarwal favorite topic so much that he kept it in Ai.as.as preliminary and main examinations . The last thirty years of the civil service candidates are guided . The harmony of these two deep insight they have given to this topic.

### PHYSICAL PRINCIPLES OF ELECTRON MICROSCOPY :-AN INTRODUCTION TO TEM,SEM AND AEM BY RAY F.EGERTON

Scanning and stationary-beam electron microscopes have become an indispensable tool for both research and routine evaluation in materials science. The semiconductor industry, nanotechnology, and the biological and medical sciences.

Labels:
Chemistry,
E-BOOK,
PHYSICAL CHEMISTRY,
Physics

### INORGANIC CHEMISTRY BY CATHERINE E. HOUSECROFT AND ALAN G. SHARPE

Inorganic Chemistry provides both teachers and students with a clearly written and beautifully-illustrated introduction to core physical-inorganic principles. It introduces the descriptive chemistry of the elements and the role played by inorganic chemistry in our everyday lives.

Labels:
Chemistry,
E-BOOK,
INORGANIC CHEMISTRY

### HYPERBOLA NOTE BY PLANCESS

In mathematics, a hyperbola (plural hyperbolas or hyperbolae) is a type of smooth curve lying in a plane, defined by its geometric properties or by equations for which it is the solution set.

## Friday, 13 July 2018

### GRB PHYSICAL CHEMISTRY

Physical Chemistry enjoys great significance in contemporary life. Development of new technologies and materials requires application of multidisciplinary skills, which means that physical chemistry overlaps with other fundamental and applied sciences.

### GRB INORGANIC CHEMISTRY

1. NCERT Inorganic Chemistry for Class 11 & 12 – Again, NCERT inorganic chemistry is a must for any JEE aspirant. You must try to go through the chapters and reactions line-by-line many times and I’d suggest while you’re reading the chapters, make your own notes from the chapters.

## Thursday, 12 July 2018

### GRB ORGANIC CHEMISTRY

2 Years ago.There is nothing intimidating about chemistry, it is just that the way you prepare for it is different than other subjects. If you are thorough with concepts and strong with the basics, solving questions of Organic Chemistry during the course of preparation would become the most exciting thing for you.

Labels:
Chemistry,
E-BOOK,
GRB PUBLICATION,
JEE-NEET,
ORGANIC CHEMISTRY

### REAL ANALYSIS BY H.L ROYDEN AND P.M FITZPATRIC

Real Analysis, Fourth Edition, covers the basic material that every reader should know in the classical theory of functions of a real variable, measure and integration theory, and some of the more important and elementary topics in general topology and normed linear space theory.

### THEORY AND PROBLEMS OF ELECTRIC CIRCUITS BY SCHAUM'S OUTLINES

Tough Test Questions? Missed Lectures? Not Enough Time?

Fortunately, there's Schaum's. This all-in-one-package includes more than 500 fully solved problems.

Fortunately, there's Schaum's. This all-in-one-package includes more than 500 fully solved problems.

Labels:
E-BOOK,
Electrical Engineering,
Engineering,
Physics

## Wednesday, 11 July 2018

### PHYSICS TOPIC AND CHAPTER WISE BY DISHA PUBLICATION

NEET Chapter-wise + Topic-wise Solved Papers PHYSICS is the thoroughly revised & updated 12th edition and it contains the past year papers of NEET 2017 to 1988 distributed in 28 Topics.

## Tuesday, 10 July 2018

### LIMITS, CONTINUITY AND DIFFERENTIABILITY NOTE BY PLANCESS

Limits, Continuity and Differentiability can in fact be termed as the building blocks of Calculus as they form the basis of entire Calculus. The basic concept of limit of a function lays the groundwork for the concepts of continuity and differentiability.

### CIRCLE NOTE BY PLANCESS

A circle is a simple closed shape. It is the set of all points in a plane that are at a given distance from a given point, the centre; equivalently it is the curve traced out by a point that moves so that its distance from a given point is constant.

### PARABOLA NOTE BY PLANCESS

In mathematics, a parabola is a plane curve which is mirror symmetrical and is approximately U shaped. It fits any of several superficially different mathematical descriptions, which can all be proved to define exactly the same curves.

## Monday, 9 July 2018

### INDEFINITE INTEGRATION NOTE BY PLANCESS

Indefinite integration, also known as antidifferentiation, is the reversing of the process of differentiation. Given a function f, one finds a function F such that F' = f.

Finding an antiderivative is an important process in calculus.

Finding an antiderivative is an important process in calculus.

### DIFFERENTIAL EQUATIONS NOTE BY PLANCESS

A differential equation is a mathematical equation that relates some function with its derivatives. In applications, the functions usually represent physical quantities, the derivatives represent their rates of change, and the equation defines a relationship between the two.

### TRIGONOMETRIC RATIOS, IDENTITIES AND EQUATIONS NOTE BY PLANCESS

In mathematics, trigonometric identities are equalities that involve trigonometric functions and are true for every value of the occurring variables where both sides of the equality are defined. Geometrically, these are identities involving certain functions of one or more angles.

### DEFINITE INTEGRATION NOTE BY PLANCESS

The definite integral of a function is closely related to the antiderivative and indefinite integral of a function. The primary difference is that the indefinite integral, if it exists, is a real number value, while the latter two represent an infinite number of functions that differ only by a constant.

### METHODS OF DIFFERENTIATION AND APPLICATIONS ON DERIVATIVES NOTE BY PLANCESS

In mathematics, differential calculus is a subfield of calculus[citation needed] concerned with the study of the rates at which quantities change. It is one of the two traditional divisions of calculus, the other being integral calculus, the study of the area beneath a curve.

## Sunday, 8 July 2018

### STRAIGHT LINE NOTE BY PLANCESS

The notion of line or straight line was introduced by ancient mathematicians to represent straight objects (i.e., having no curvature) with negligible width and depth. Lines are an idealization of such objects. Until the 17th century, lines were defined in this manner:

### PERMUTATION AND COMBINATION NOTE BY PLANCESS

**Permutation**: Permutation means arrangement of things. The word arrangement is used, if the order of things is considered.

**Combination**: Combination means selection of things. The word selection is used, when the order of things has no importance.

### COMPLEX NUMBER NOTE BY PLANCESS

A complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is a solution of the equation x2 = −1. Because no real number satisfies this equation, i is called an imaginary number.

## Saturday, 7 July 2018

### SOLUTIONS OF TRIANGLE NOTE BY PLANCESS

Solution of triangles (Latin: solutio triangulorum) is the main trigonometric problem of finding the characteristics of a triangle (angles and lengths of sides), when some of these are known. The triangle can be located on a plane or on a sphere.

### SEQUENCES AND SERIES NOTE BY PLANCESS

A "sequence" (called a "progression" in British English) is an ordered list of numbers; the numbers in this ordered list are called the "elements" or the "terms" of the sequence.

## Friday, 6 July 2018

### QUADRATIC EQUATIONS AND INEQUALITIES NOTE BY PLANCESS

Quadratic Equations and Inequalities introduces students to the graphs of quadratics, teaches them to find the vertex, intercepts, discriminant, domain and range and interpret the graph in relation to these qualities.

### INVERSE TRIGONOMETRIC FUNCTIONS NOTE BY PLANCESS

In mathematics, the inverse trigonometric functions (occasionally also called arcus functions, anti trigonometric functions or cyclometric functions) are the inverse functions of the trigonometric functions (with suitably restricted domains).

## Thursday, 5 July 2018

### BINOMIAL THEOREM NOTE BY PLANCESS

In elementary algebra, the binomial theorem (or binomial expansion) describes the algebraic expansion of powers of a binomial. According to the theorem, it is possible to expand the polynomial (x + y)n into a sum involving terms of the form a xb yc, where the exponents b and c are non negative integers with b + c = n, and the coefficient a of each term is a specific positive integer depending on n and b.

### AROMATICITY NOTE FOR CAIR NET/SET/GATE/IIT-JAM

In organic chemistry, the term aromaticity is used to describe a cyclic (ring-shaped), planar (flat) molecule with a ring of resonance bonds that exhibits more stability than other geometric or connective arrangements with the same set of atoms.

### MOLE CONCEPT AND STOICHIOMETRY HAND WRITTEN NOTE

The mole concept is one of the topics with which you kick-off your preparation of physical chemistry in class 11. One of the reasons for it being taught earlier is that the concept of mole will be required in almost every other topic of physical chemistry that you study later, irrespective of the complexity of that topic.

### PHYSICAL CHEMISTRY 6TH EDITION BY IRA N LEVINE

This textbook is for the standard undergraduate course in physical chemistry. To make the presentation easy to follow, the book gives careful definitions and explanations of concepts, full details of most derivations, and reviews of relevant topics in mathematics and physics.

Labels:
Chemistry,
E-BOOK,
PHYSICAL CHEMISTRY

### LINEAR ALGEBRA AND ITS APPLICATIONS BY DAVID C LAY

With traditional linear algebra texts, the course is relatively easy for students during the early stages as material is presented in a familiar, concrete setting. However, when abstract concepts are introduced, students often hit a wall.

Labels:
E-BOOK,
LINEAR ALGEBRA,
Maths

### COORDINATION CHEMISTRY BY AJAI KUMAR

A good book if you are preparing for competitive exams like NET etc. Gives you a good understanding of coordination compounds. It's really good book for students ,seeking for qualify IITJAM and NET. All the material are such good and well explained by author.

## Wednesday, 4 July 2018

### PHYSICS PART 2 BY PLANCESS

Take your Physics JEE preparation to the next level with our Physics Study Material. Designed by Top 100 JEE Rankers, the JEE Physics book is a comprehensive guide to help you clear your Physics concepts and learn new ways to solve Physics problems.

## Tuesday, 3 July 2018

### PHYSICS PART 1 BY PLANCESS

### NUCLEAR PHYSICS AND RADIOACTIVITY NOTE BY PLANCESS

Radioactivity is the conversion of one nuclear state to another. It is accompanied by the emission of particles or electromagnetic radiation. The nuclear state change can often involve a change in the atomic number of the atoms involved.

### INDIAN POLITY & CONSTITUTION MCQ SERIES BY PRATIYOGITA DARPAN

Here we are with INDIAN POLITY & CONSTITUTION MCQ SERIES BY PRATIYOGITA DARPAN for you, To improve your exam preparation. We suggest you Download all Books and notes. we will post important PDF every day. These PDF will help you a lot in your competitive exams.

Labels:
CIVIL SERVICES,
E-BOOK,
POLITY,
UPSC STUDY MATERIAL

### GRAVITATION NOTE BY PLANCESS

Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy including planets, stars, galaxies, and even light are brought toward (or gravitate toward) one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides.

### EXPERIMENTAL PHYSICS NOTE BY PLANCESS

Experimental physics is the category of disciplines and sub-disciplines in the field of physics that are concerned with the observation of physical phenomena and experiments.

## Monday, 2 July 2018

### INDIA POLITY PART-2 BY M LAXMIKANTH

The book deals with every little detail that aggregates with the major events, corresponding to the governance system in India. An aspirant who plans to appear in a civil services examination or a public service commission exam has to understand the subject of Indian governance meticulously.

Labels:
CIVIL SERVICES,
E-BOOK,
POLITY,
UPSC STUDY MATERIAL

### INDIA POLITY PART-3 BY M LAXMIKANTH

Labels:
CIVIL SERVICES,
E-BOOK,
POLITY,
UPSC STUDY MATERIAL

### HEAT TRANSFER NOTE BY PLANCESS

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes.

### SEMI CONDUCTOR AND COMMUNICATION SYSTEM NOTE BY PLANCESS

A semiconductor material has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Semiconductors are the foundation of modern electronics. Semiconducting materials exist in two types - elemental materials and compound materials.

### MODERN PHYSICS NOTE BY PLANCESS

Modern physics is the post Newtonian conception of physics. It implies that classical descriptions of phenomena are lacking, and that an accurate, "modern", description of nature requires theories to incorporate elements of quantum mechanics or Einsteinian relativity, or both.

## Sunday, 1 July 2018

### RAILWAY MEGA STUDY BOOK 8000+ MCQ WITH PREVIOUS YEAR PAPERS

Here we are with RAILWAY MEGA STUDY BOOK 8000+ MCQ WITH PREVIOUS YEAR PAPERS for you, To improve your exam preparation. We suggest you Download all Books and notes. we will post important PDF every day. These PDF will help you a lot in your competitive exams.

### WORK ENERGY AND POWER NOTE BY PLANCESS

Work has a specific definition in physics. Work is done when a force is exerted on an object, and the object moves from one place to another. Work is the result of a force, acting over a certain distance. This distance is called the displacement of the object.

### WAVES ON A STRING NOTE BY PLANCESS

When studying waves, it is helpful to use a string to observe the physical properties of waves visually. Imagine you are holding one end of a string, and the other end is secured and the string is pulled tight.

### CALORIMETRY AND THERMAL EXPANSION NOTE BY PLANCESS

Calorimetry And Thermal Expansion

Introduction. Calorimetry can be considered to be the earliest known principal of Heat and Thermodynamics.

This was the introduction of the widely used principal of Conservation of Energy to mankind.

Introduction. Calorimetry can be considered to be the earliest known principal of Heat and Thermodynamics.

This was the introduction of the widely used principal of Conservation of Energy to mankind.

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