What is Activity: Definition and 191 Discussions

Paranormal Activity is a 2007 American supernatural horror film produced, written, directed, photographed and edited by Oren Peli. It centers on a young couple (Katie Featherston and Micah Sloat) who are haunted by a supernatural presence in their home. They then set up a camera to document what is haunting them. The film utilizes found-footage conventions that were mirrored in the later films of the series.
Originally developed as an independent feature and given film festival screenings in 2007, the film was shot for $15,000. It was then acquired by Paramount Pictures and modified, particularly with a new ending that cost an additional $200,000. It was given a limited U.S. release on September 25, 2009, and then a nationwide release on October 16, 2009. The film earned nearly $108 million at the U.S. box office and a further $85 million internationally for a worldwide total of $193 million. Paramount/DreamWorks acquired the U.S. rights for $350,000. It is the most profitable film ever made, based on return on investment, although such figures are difficult to verify independently as this is likely to exclude marketing costs.The film is the first (chronologically, the third) entry in the Paranormal Activity film series. A parallel sequel and prequel, Paranormal Activity 2, was released in 2010. The success of the first two films would spawn additional films in the series: the prequel Paranormal Activity 3 in 2011, and Paranormal Activity 4 (the sequel to the second installment) in 2012. The fifth installment, The Marked Ones, was released in 2014, and the sixth installment, The Ghost Dimension, was released in 2015.
On June 19, 2019, Paramount announced that a seventh installment is in development and would be released on March 19, 2021. However, in August 2020, it was announced it would be delayed to March 4, 2022 due to the COVID-19 pandemic.

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  1. Astronuc

    Nevado del Ruiz Volcano, Colombia - increased activity

    https://volcano.si.edu/volcano.cfm?vn=351020 The Street reported, "The last time the Nevado del Ruiz volcano was active, it erupted and killed 23,000 people in Colombia, wiping out the town of Armero in the process." Pay attention to volcanoes in the neighborhood and be prepared to...
  2. pinball1970

    Mass Extinction Event 259-263 Mya via volcanic activity.

    In a study published in the journal Earth and Planetary Science Letters, researchers say their analysis provides evidence that the oxygen-deprived oceans precipitated two mass extinctions around 259 million and 262 million years ago during the Middle Permian Period. "We are studying the...
  3. Dario56

    Concept of Absolute Thermodynamic Activity

    In the textbook Electrochemical Systems by Newman and Alyea, Chapter 14: The definition of some thermodynamic functions, chemical potential of component (ionic or neutral) is written as a function of absolute activity: $$\mu_i=RT\ln(\lambda_i)\tag1$$ where ##\lambda_i## is the absolute activity...
  4. Dario56

    Standard Activity in Electrochemistry

    In the textbook Electrochemical Systems by Newman and Alyea, chapter 14: The definition of some thermodynamic functions, chemical potential of component (ionic or neutral) is written as a function of absolute activity: $$ \mu_i = RTln(\lambda_i) \tag {1} $$ where ##\lambda_i## is the absolute...
  5. Astronuc

    Alaska's Trident Volcano has increased seismic activity

    Andrew Wulfeck (FOX Weather) - Alaska officials raise alert level for volcano after increase in earthquake activity Wed, February 22, 2023 at 6:47 PM EST https://www.yahoo.com/news/alaska-officials-raise-alert-level-234711944.html https://www.avo.alaska.edu/activity/Trident.php...
  6. E

    Activity of 0.000001 mL Rn-222?

    TL;DR Summary: What is the activity of 0.000001 mL Rn-222? Trying to do a quick calculation of the activity of 0.000001 mL of Rn-222 and I'm not ending up with what I expected.
  7. Astronuc

    Mount Edgecumbe, dormant for 800 years, now showing activity

    https://www.msn.com/en-us/weather/topstories/u-s-volcano-that-s-been-dormant-for-more-than-800-years-showing-signs-of-life/ar-AA13s3xt It's also unusual.
  8. shivajikobardan

    MHB What is the difference between activity and event in "simulation"?

    I am studying about components of a system. Activity-: It is What entities do to cause changes is activity. It is represented by time period of a specified length. Event-: Event is defined as an instantaneous occurrence that might change state of the system. Endogenous events occurs within...
  9. S

    Is there an explanation for the unexpected increase in activity of Nuclide A?

    I found something I think does not make sense. Decay constant of A: $$\lambda_{A}=\frac{ln~2}{t_{\frac 1 2}}$$ $$=\frac{ln~2}{10\times 365 \times 24 \times 3600}$$ $$=2.2\times 10^{-9} / s$$ Initial activity of A = ##\lambda_{A} N_{\text{initial}}## = 2.2 x 10-9 x 1.29 x 109 = 2.84 Bq Then...
  10. I

    Biology Volume of substrate affecting enzyme activity

    I know that as the concentration of substrate increases, the enzyme activity increases because there are more substrate molecules to react on (but at an increasingly slower rate). Would the same reasoning work with volume? Thanks!
  11. A

    Is it possible to deduce the software from the hardware activity?

    Suppose one knows well the laws of physics but knows nothing about computers and IT. Would one be able to deduce how a computer works only by studying its hardware? Could one rebuild the software code and understand its meaning only by looking at the internal flow of bits in its CPU?
  12. U

    Understanding the determination of Radon activity

    When we want to determine the radioactivity of a nucleus, we usually determine the counts detected using say a Geiger counter. The count rate is then usually used as the disintegration rate i.e. the activity of the nucleus. However, say now we wish to measure the activity of Radon 222 using...
  13. M

    Tensor Inverse (Optical Activity)

    Clearly, they used the binomial expansion on this; however, I cannot figure out why [G] is sandwiched by the epsilon inverses: $$\varepsilon^{'-1}=1/(\varepsilon+i\epsilon_{0}[G])\approx(1-i\epsilon_{0}[G]\varepsilon^{-1})\varepsilon^{-1}$$
  14. il postino

    Chemistry Calculate the activity of the chloride ion in a solution

    Hi everyone! I have to calculate the activity of ##Cl^{-}## I have a solution formed by ## Na_{2}SO_{4}## 0.0016 m + ##NaCl## 0.0014m + ##FeCl_{3}## 0.0012m I calculated the ionic strength ##I## ##I=0.0134## The activity of the chloride ion is ##a_{Cl^{-}}=m_{Cl}*\gamma _{Cl}## But I don't...
  15. I

    Activity - Equilibrium Expressions

    When I use the concept of activity to express the equilibrium constant expression, for either equilibrium pressures or concentrations, the units cancel and the value of K has no units (which is how K is customarily reported). But because of the difference in reference states (the reference...
  16. dRic2

    How to measure the activity of a radioactive source

    Hi, I've been reading about radiation detectors (manly form Knoll's book), but there is something I don't understand. Radiation detectors are of very different nature, but they all share a common process to detect a type of radiation: - I have a control volume - The incoming radiation interacts...
  17. P

    Chemistry Solving for electron activity given pH and ratio of redox elements

    I've written out the half reaction 8e- + 9H+ + SO42- = HS- + 4H2O and I know the logK = 4.25 (that's the constant mentioned in the prompt) I've written out the equilibrium statement of 10^4.25 = ([x^1/8]*[H2O^1/2])/([10x^1/8]*[e-]*[(10^-8.2)^9/8] However, from there, it seems like I have two...
  18. B

    Finding the activity of a carbon 14 sample

    Hi there So I have had a go at this question but I'm not confident that I have done the last 2 parts of this question right? Can anyone please see if this is what you do to get the values? Any help would be appreciated! Thanks
  19. P

    Chemistry Structural formulas & optical activity

    How do I determine which group is dash (into the page) and which is wedge (out of page)? Won't that literally change which isomer it is? How to determine optical activity then? (I believe that in order for something to be optically active it has to be an enantiomer--a non-superimposable mirror...
  20. C

    Anti-viral Activity of Anise Extract

    Anise extracts contain Lignin-Carbohydrate complexes (LCs), which have been found to have anti-viral effects according to this article (DOI: 10.1271/bbb.100645 ). However, from what I understood by going quickly through the article, the scientists applied the extract directly onto the cell...
  21. S

    B How well do we know solar activity?

    From what I've understood, we know sun's activity well enough that we can make some good predictions about it for a decade or so to the future. But is it theoretically possible that all the measurements that we have been able to make about the solar cycles and their effect on our climate, are in...
  22. M

    Chemistry The Importance of pKa in Determining Activity: A Brief Overview

    My explanation is : for ph=pka , the number of two ionic forms[A-] and [HA] are equal, then, for ph>pka,[A-]>[HA], the gratient gets smaller when ph is increased, and also, for ph<pka, [A-]<[HA], the slope is becoming larger when pH is increasing . Would u like to have a look of my explanation...
  23. T

    Calculate the activity in Bq of 1g of (238-94 Pu).

    Problem Statement: Question: Calculate the activity in Bq of 1g of (238-94 Pu).Would love some help with the working. The final answer is 6.35 x 1011 Bq Relevant Equations: Atomic Mass of Pu = 238.049550u Previously calculated: λ=2.51x10-10 s-1 Pls help
  24. A

    What’s the relation between activity and half-life

    I’m confused because there are two equations: 1) A=λN 2) A=A0exp^-(λt)If half-life increases, λ decreases, and A decreases according to 1); but, If half life increases, λ decreases, hence exp^-(λt) decreases, A should decreases according to 2)Why is this so? Where went wrong? Thanks!
  25. C

    I Activity of daugther isotope in secular equilibrium

    Consider chain of two radioactive decays ##A \to B\to C##. The equation that regulates ##N_B## is $${\frac {\mathrm {d} N_{B}}{\mathrm {d} t}}=-\lambda _{B}N_{B}+\lambda _{A}N_{A}$$ I can't understand why the activity of ##B## is get as ##\lambda_B N_B##, for example at page 20 here...
  26. Zach90

    I Need Help Co-60 Shielding Mcnp Activity Input

    Greeting, I am trying to figure out how can I include the activity of a Co-60 source in MCNP code. I have the following problem Co-60 source in a cylinder surrounded by concrete. I just need to know how to include the source activity and whether it should be in Bq or Ci. Thank you in advance
  27. Paul Colby

    Can Crystal Symmetry Explain the Lack of Optical Activity in Quartz?

    Hi, I've been looking at the optics of ##\alpha##-quartz which comes in two parities, left and right. Quartz is optically active which means that the plane of a linearly polarized beam propagating along the optic axis is rotated by an angle proportional to the distance traveled. I would like...
  28. E

    What is the true meaning of chemical activity in solutions?

    Hello - I am wondering abut the meaning of chemical activity. Most definitions are something along the lines of "effective concentration," which is fine until you have a real concentration in a lab, and you don't know if you need to calculate the concentration or "effective" concentration of the...
  29. N

    Factors that affect enzyme activity

    Two graphs are given But i don't know how to explain each of them?? first one is curved because there is not enough substrate maybe ??
  30. C

    Why is activity of solvated components equal to 1?

    Homework Statement Consider the following reaction $$\mathrm{Ni^{2+}_{(aq)} + H_2S_{(g)} \to Ni_{(s)} + S_{(s)} + 2H^{+}_{(aq)}}$$ What are the activities of the terms in the reaction? Homework Equations The activity is defined as ##a = c/c^\circ## in ##\mathrm{ mol \, dm^3}## 3. The...
  31. F

    Standard chemical potential and activity of asphaltene

    Hi , this is my equation : μA= μA0 + RTlnaA A is the asphaltene in toluene solution . i want to calculate μA in different temperatures. where can i get μA0 and aA? tables? other equations? μA0 is the standard chemical potential of asphaltene and aA is the asphaltene activity in solution.
  32. Stavros Kiri

    Stargazing Solar Activity and Space Weather Update thread

    I am picking this up as a continuation and extension of the idea laid out e.g. in @davenn 's thread "The Sun today - 9 July 2017 - nice spot group" https://www.physicsforums.com/threads/the-sun-today-9-july-2017-nice-spot-group.919696/ See also (for continuity purposes)...
  33. U

    Activity Definition: Is T Temp of Current State?

    The definition of activity is: $$\mu _{i}=\mu _{i}^{0}+RT\cdot \ln a_{i}$$ where μi is the chemical potential of i in current state and μi0 is the chemical potential of i in standard state. The current and standard state have the same temperature or can their temperature differ? If their...
  34. K

    Static Electricity powered toy car project for school

    I have to make a project for school, so I thought that i can make a static electricity car. I wanted to make a car, and stick/put a material behind the car which creates a charge, and then take another material which creates a charge, and rub it. As it creates static electricity, the cars...
  35. A

    B How are activity and decay constant different?

    What's the difference between activity of a radioactive sample and the decay constant. Both are measured in second inverse. Please distinguish among the two?
  36. S

    I Converting measured activity between isotopes

    Hello there, I have a question that I just can't seem to solve by myself (although compared to the other threads here it seems quite simple) I did some FDG-PET scans for my master thesis: I inject a certain dose of F18-FDG and prepare these injections by measuring the right dose using a...
  37. Andrew1949

    B Calculating activity of a radionuclide

    Activity (in Bq) of 1 mol of a radionuclide is given by formula: A = NA x ln(2) / t1/2 = 0.693 x NA / t1/2 where NA is Avogadro number and t1/2 the half-life (in seconds) Why don't we use simply A = 0.5 x NA / t1/2 ? After all, t1/2 means that, after that time, half of atoms will have decayed...
  38. SpiffyPhysics

    Help with diffraction flashlight lab activity....

    I'm updating some poorly written lab activities for an online physics class that I have been given, and I am going through the experiments and doing them myself to better write them. I came across this one, and I have no idea what the results are supposed to be. It comes after the chapter on...
  39. A

    Imagine that you are conducting an activity with a laser....

    Homework Statement Imagine that you are conducting an activity with laser to create an interference pattern. Use the appropriate equations to predict two ways to change the interference pattern in order to have closer fringes. Explain your predictions. Change in X = L(Lambda) / d Homework...
  40. WhiteWolf98

    Activity of 1 g of carbon if 1 in 10^12 atoms are carbon-14

    Homework Statement Carbon-14 decays by β emission and has a half-life of 5570 years. What is the decay constant of carbon-14? What is the activity of 1 g of carbon if 1 in 1012 atoms are carbon-14? After what time will the activity per gram have fallen to 3 Bq? Homework Equations λt½ = ln(2)...
  41. H

    What's your brain break activity?

    Some activity you do while working to refresh your brain. It is actually a serious thing. I encourage anyone not familiar to learn about. I have desktop versions of field sports I play eg miniature basketball hoop, Velcro dart board, desktop catapults, and some mindless funny YouTube sub's eg...
  42. S

    What is the uncertainty in the activity of Cesium 137 over time?

    Hello, one of my friends came over to get some help on a homework problem, and it went past over my head I am pretty good with stats, just don't know how to approach this to help him out. So a radionuclides' activity (Cesium 137) is measured in the year of 1981, (no date just year), and its...
  43. Mary curie

    B Paradox in the nuclear activity

    good evening everybody! i'm studying these days the nuclear activity and this amazing world where an atom try to find its/her stability ! so i came across the famous radiations but then stopped by something i didn't quite understand! when an atom release a beta radiation a negative one for...
  44. T

    B Nuclear Decay with time (half-life,initial activity/ nuclei)

    Hi! I just keep having a hard time looking for the formula stating the relationship between half life, the initial number of unstable nuclei and the initial activity, can someone help me on that ? To be more specific, here is a problem which can be solved using that formula: "A substance has a...
  45. S

    Co-60 Unit Activity: Treatment Time Calculation

    Homework Statement A patient is treated for cancer using radiation from a cobalt-60 unit. Exactly 1.5 years later another patient is treated for the same cancer using the same co-60unit previously used. How much longer would treatment be for the second patient? Homework Equations Decay...
  46. CapnGranite

    Nocturnal seismic activity at Mt. Vesuvius

    https://www.researchgate.net/publication/301759171_Evidences_for_higher_nocturnal_seismic_activity_at_the_Mt_Vesuvius abstract We analyze hourly seismic data measured at the Osservatorio Vesuviano Ovest (OVO, 1972–2014) and at the Bunker Est (BKE, 1999–2014) stations on the Mt. Vesuvius. The...
  47. Astronuc

    Mount Teide, Tenerife Island, seismic activity

    http://www.ibtimes.co.uk/volcanologists-fear-infamous-tenerife-volcano-will-erupt-after-100-earthquakes-are-recorded-1584962 Keep an eye on that one.
  48. wronski11

    Specific and surface activity of nuclear waste

    Dear all, I am looking for more information how specific activity \frac{Bq}{g} and surface activity \frac{Bq}{cm^2} is measured. This is done to determine whether the materials of interest can be treated as harmless and disposed as usual waste. I am interested how the experimental procedure...
  49. B

    MHB Probability Activity Word problem for relative frequency

    I am drowning in math right now and would love some help bc I am horrible at math. Here is what I have got. Question: 1. The four major blood groups are designated A, B, AB and O. Within each group there are two types; positive and negative. Find data on the relative frequency of these eight...