question
stringlengths 5
1.87k
| choices
listlengths 2
4
| answer
int64 0
3
|
|---|---|---|
Which of the following are correct implementation for acquire function ? Assume 0 means UNLOCKED and 1 means LOCKED. Initially l->locked = 0.
|
[
"c \n void acquire(struct lock *l)\n {\n for(;;)\n if(xchg(&l->locked, 1) == 0)\n return;\n }",
"c \n void acquire(struct lock *l)\n {\n if(cas(&l->locked, 0, 1) == 0)\n return;\n }",
"c \n void acquire(struct lock *l)\n {\n for(;;)\n if(cas(&l->locked, 1, 0) == 1)\n return;\n }",
"c \n void acquire(struct lock *l)\n {\n if(l->locked == 0) \n return;\n }"
] | 0
|
Suppose we run JOS and set a breakpoint at syscall (in lib/syscall.c). What are the Current Privilege Level (CPL) before invoking the syscall function and after executing the int 0x30 instruction?
|
[
"0 3",
"0 0",
"3 0",
"3 3"
] | 2
|
Given that JOS has correctly initialized the IDT and installed all the interrupt handlers. Which of the following will JOS do if the CPU with CPL = 3 tries to read the memory in data segment with DPL = 0?
|
[
"Calling the Page Fault Handler.",
"Calling the General Protection Fault handler.",
"Shuting down the system .",
"Reading out the memory content successfully."
] | 1
|
Assume a 32-bit architecture with a single-level page table. Each entry has 20 bits for PPN, 12 bits for permissions, and extra 32 bits used by the OS to store the access time of the page table entry. What is the size of page table required if a process uses all of its memory? (2 pts)
|
[
"2 MB",
"4 MB",
"8 MB",
"16 MB"
] | 2
|
Can there be a race condition in a multi-threaded application running on a single-core machine and multi-core machine?
|
[
"Single-core: Yes, Multi-core: Yes",
"Single-core: Yes, Multi-core: No",
"Single-core: No, Multi-core: Yes",
"Single-core: No, Multi-core: No"
] | 0
|
In executing interrupts, when does JOS use Task State Segment and what is it used for?
|
[
"Switching from kernel space to user space; Poping all general registers.",
"Switching between user space environments; Loading the stack and instruction register of another environment.",
"Switching from user space to kernel space; Loading the saved kernel stack registers to esp and ss registers."
] | 2
|
In JOS, suppose one Env sends a page to another Env. Is the page copied?
|
[
"Yes",
"No"
] | 1
|
In JOS and x86, please select all valid options for a system call.
|
[
"A system call is for handling interrupts like dividing zero error and page fault.",
"In user mode, before and after a system call instruction(such as int 0x30), the stack pointer(esp in x86) stays the same.",
"During the execution of a system call, when transfering from user mode to kernel mode, the stack pointer(esp in x86) stays the same."
] | 1
|
If you write "hello" to a file in a JOS file system. Right after the write operation, the computer crashes. Is the content "hello" persisted (or written) on the disk?
|
[
"Yes",
"No"
] | 1
|
Suppose a file system used only for reading immutable files in random fashion. What is the best block allocation strategy?
|
[
"Linked-list allocation",
"Continuous allocation",
"Index allocation with B-tree",
"Index allocation with Hash-table"
] | 1
|
Which flag prevents user programs from reading and writing kernel data?
|
[
"PTE_P",
"PTE_U",
"PTE_D",
"PTE_W"
] | 1
|
In JOS, after finishing the execution of a user-level page fault handler, how is the program control flow transferred back to the program? (You may get insights from the code snippet of _pagefault_upcall.)
|
[
"The control flow will be transferred to kernel first, then to Env that caused the page fault.",
"The control flow will be transferred to Env that caused the page fault directly."
] | 1
|
What data structure is used for tracking free data blocks in ext3/4 file system?
|
[
"Linked-list",
"Bitmap",
"Heap",
"Stack"
] | 1
|
In JOS, which of the following does NOT happen during the execution of a system call? (Including the period of entering kernel, executing kernel function, and exiting kernel.)
|
[
"The kernel pushes Env’s cs and eip register on the kernel stack.",
"The CPU reads the interrupt handler address from IDT.",
"The kernel executes iret to return to user mode.",
"The kernel switches from Env's page table to the kernel's page table, by loading cr3 register."
] | 3
|
In JOS, is page fault handled by a system call?
|
[
"Yes",
"No"
] | 1
|
Which of the execution of an application are possible on a single-core machine?
|
[
"Concurrent execution",
"Parallel execution",
"Both concurrent and parallel execution",
"Neither concurrent or parallel execution"
] | 0
|
In JOS, suppose a value is passed between two Envs. What is the minimum number of executed system calls?
|
[
"1",
"2",
"3",
"4"
] | 1
|
What strace tool does?
|
[
"It prints out system calls for given program. These system calls are always called when executing the program.",
"It prints out system calls for given program. These systems calls are called only for that particular instance of the program.",
"To trace a symlink. I.e. to find where the symlink points to.",
"To remove wildcards from the string."
] | 1
|
Chez les eucaryotes tels que l’être-humain toute régulation épigénétique passe par une modification post-traductionnelle des queues d'histones.
|
[
"Vrai",
"Faux"
] | 1
|
Chez les eucaryotes tels que l’être-humain un nucléosome contient quatre types d'histones différents.
|
[
"Vrai",
"Faux"
] | 0
|
Pendant le traitement du pré-ARNm, la queue polyA est ajoutée au pré-ARNm par l'ARN polymérase II elle-même. Vrai Faux
|
[
"Vrai",
"Faux"
] | 1
|
Chez les eucaryotes tels que l’être-humain l'histone H1 est l'une des histones de cœur (core histones) des nucléosomes dans l'hétérochromatine compactée.
|
[
"Vrai",
"Faux"
] | 1
|
la phosphorylation des protéines est fréquemment impliquée dans tous ces processus sauf un; lequel?
|
[
"1. Régulation transcriptionnelle induite par des molécules signal extracellulaires",
"2. L’activation des récepteurs couplés à une protéine G",
"3. Activation des récepteurs de type tyrosine kinase",
"4. Activation des kinases qui phosphorylent des protéines"
] | 1
|
Chez les eucaryotes tels que l’être-humain une fois qu'un nucléosome a été formé, il reste stable jusqu'à la phase S suivante.
|
[
"Vrai",
"Faux"
] | 1
|
La transcription par l'ARN polymérase II se termine au signal AAUAAA. Vrai ou Faux. Justifiez brièvement votre réponse.
|
[
"Vrai",
"Faux"
] | 1
|
Chez les eucaryotes tels que l’être-humain l'histone H4 forme un dimère avec soit H2A, soit H2B.
|
[
"Vrai",
"Faux"
] | 1
|
Chez les eucaryotes tels que l’être-humain les histones de cœur (core histones) forment d'abord des hétérodimères qui sont ensuite assemblés en un octamère.
|
[
"Vrai",
"Faux"
] | 0
|
Dans un ARNm eucaryote, la coiffe 5 '(CAP en anglais) est codée dans le génome par un résidu C, où la transcription commence.
|
[
"Vrai",
"faux"
] | 1
|
En utilisant vos connaissances sur la maturation des lymphocytes T dans le thymus, indiquez si une souris déficiente pour le MHC I possède :
|
[
"A la fois des T CD4 et des T CD8",
"Des T CD4 mais pas des T CD8",
"Des T CD8 mais pas des T CD4",
"Ni des T CD4 ni des T CD8"
] | 1
|
Un anticorps neutralisant peut protéger l’hôte par les mécanismes suivants, sauf un. Indiquer lequel.
|
[
"Empêcher la fixation d’une bactérie aux récepteurs de surface.",
"Empêcher une toxine d’agir sur sa cible cellulaire.",
"Empêcher un virus d’entrer dans une cellule cible.",
"Empêcher une bactérie spécialisée dans la survie intracellulaire d’accéder à la vacuole phagocytaire."
] | 3
|
Comment une cellule T reconnaît-elle un antigène intracellulaire ?
|
[
"Via les molécules du MHC (complexe majeur d’histocompatibilité).",
"Les molécules MHC présentent les peptides antigèniques à la surface des cellules portant des antigènes intracellulaires.",
"En reconnaissant les molécules du soi.",
"Les cellules T sont incapables de réagir aux antigènes intracellulaires."
] | 0
|
Les caractéristiques de rubor (rougeur locale), calor (augmentation de température) et de tuméfaction locale sont causés par:
|
[
"le volume du liquide de vaccin injecté sous la peau",
"des médiateurs vasoactifs",
"la réponse de cytotoxicité locale qui détruit le muscle"
] | 1
|
Que signifie CDR dans la région variable d’un anticorps ?
|
[
"Complementarity-Determining Region",
"Complement Domain region",
"Nom donné aux régions constantes des domaines variables",
"Nom donné aux régions hypervariables des domaines constants"
] | 0
|
Lors de la reconnaissance d’un antigène, un TCR se lie à :
|
[
"l’antigène peptidique soluble",
"l’antigène peptidique ancré sur une membrane",
"l’antigène peptidique et la molécule MHC qui le porte",
"la molécule MHC portant l’antigène"
] | 2
|
Les médicaments immunosuppresseurs utilisés lors de transplantations ont les effets ou mécanismes suivants :
|
[
"Ils empêchent la reconnaissance des antigènes de la greffe par les cellules T.",
"Ils empêchent que des cellules T ayant reconnu un antigène de la greffe subissent l’expansion clonale.",
"Certains bloquent la signalisation induite par IL-2.",
"Certains bloquent la phosphorylation des transducteurs du signal (p.ex. NF-AT,NF-kB) dans les cellules T."
] | 1
|
What is true about reducing phase-encoding steps? (i.e how can we reduce phase encoding step and what is its effect)
|
[
"Increasing k-space spacing - leads to worse resolution",
"Dropping peripheral k-space lines (dropping scan percentage) – leads to smaller FOV",
"Half-Fourier acquisition – leads to worse resolution",
"Reducing phase-encoding steps leads to worse SNR"
] | 3
|
Note: Make sure you select all of the correct options—there may be more than one!
|
[
"The Larmor equation describes the precession of the total magnetization around the static magnetic field \\(\\vec B_0\\) with a frequency \\(f=\\gamma B_0/(2π)\\) in the Lab frame",
"The Larmor equation describes the precession of the total magnetization around \\(\\vec B_0\\) with a frequency \\(f=\\gamma B_0/(2π)\\) in the rotating frame.",
"At equilibrium, all the spins are aligned along \\(\\vec B_0\\)."
] | 0
|
Can we use MRI as a lie detector?
|
[
"Yes, and it is already often used.",
"No, it is strictly impossible to distinguish different brain zones, based on MRI images.",
"Maybe, some scientists are developping it. But at this time, the technique is not reliable."
] | 2
|
Integral under peak of the Fourier transform of a signal gives information about...
|
[
"Properties of the compound",
"Concentration of the compound",
"Relaxation time of the compound"
] | 1
|
When the RF pulse stops, protons...
|
[
"Dephase according to \\(T_2^*\\) and recover along \\(\\vec B_0\\) according to \\(T_1\\)",
"Dephase according to \\(T_1\\) and recover along \\(\\vec B_0\\) according to \\(T_2^*\\)",
"Dephase according to \\(T_1\\) and recover along \\(\\vec B_0\\) according to \\(T_2\\)",
"Dephase according to \\(T_2\\) and recover along \\(\\vec B_0\\) according to \\(T_1\\)"
] | 0
|
Why do we put on sunscreen in Australia?
|
[
"Because the ionizing limit is at shorter wavelength than visible light",
"Because the ionizing limit is at longer wavelength than visible light",
"Because the sunscreen absorbs all the ultraviolet radiation"
] | 0
|
Diffusion is typically NOT restricted by...
|
[
"Intracellular water",
"Extracellular water",
"Pus",
"Tumor cells"
] | 1
|
What is one of the major problem encountered with Emission Tomography?
|
[
"Bad CNR",
"Inefficient detection of X-rays",
"Attenuation",
"High cost of exam"
] | 2
|
Compartmental modeling and tracers studies have application in different areas such as...
|
[
"Drug kinetics in pharmacology",
"Studies of metabolic systems",
"Analysis of ecosystem",
"Chemical reaction kinetics"
] | 0
|
What information does a Doppler shift provide?
|
[
"Flow",
"Cardiac output",
"Velocity",
"Speed"
] | 2
|
How many lines are there in the 1H spectrum of CHD3?
|
[
"2",
"3",
"5",
"7"
] | 3
|
What does the Doppler shift measure?
|
[
"The ratio of incident frequency to reflected frequency",
"The sum of incident frequency and reflected frequency",
"The difference between incident and reflected frequency",
"The product of incident and reflected frequency"
] | 2
|
The size of a voxel can be calculated from:
|
[
"Matrix size",
"Slice thickness",
"Field of view"
] | 0
|
In PET, how can the attenuation correction be performed?
|
[
"Preacquisition of a (known) external radioactive source to be used for attenuation",
"Utilizing CT images for attenuation correction",
"Both of the above"
] | 2
|
The strength of the frequency-encoding gradient...
|
[
"...is changed many times to generate k-space",
"...has no influence on the final image",
"...alters the bandwidth of the signal",
"...alters the tissue contrast"
] | 2
|
During fluoroscopy, what is the principal source of the dose received by the technologist (outside the primary beam)?
|
[
"Compton electrons.",
"Photoelectrons.",
"Compton scattered photons.",
"Rayleigh scattering"
] | 2
|
The ratio T1 / T2 = 10 was measured for a 1H resonance on a 600 MHz spectrometer. What is the value of tau c?
|
[
"0.52 ns",
"1.13 ns",
"1.38 ns",
"2.05 ns"
] | 1
|
Diagnostic ultrasound is defined as a sound with a frequency of:
|
[
"Greater than 20 kHz",
"Greater than 0.2 MHz",
"Greater than 1 MHz",
"Less than 1 kHz"
] | 2
|
Why are filters placed within the X-ray tube of a CT scanner?
|
[
"To decrease the scan time",
"To remove high energy photons from the beam",
"To remove low energy X-ray photons from the beam"
] | 2
|
Where is hydrogen magnetization measured?
|
[
"Along the main magnetic field",
"Perpendicular to the main magnetic field"
] | 1
|
Why should you go to the bathroom before leaving the hospital after a PET scan?
|
[
"In order to eliminate most of the radioactive substance.",
"Doctors can check the desintegration of radioactive substance after the scan.",
"Urine analysis is necessary to a better interpretation of PET scan images"
] | 0
|
What produces a uniform density of the radiograph called image noise?
|
[
"Photoelectric effect",
"Filter",
"Photodisintegration",
"Rayleigh (coherent) scattering"
] | 3
|
In an X-ray tube, electrons travel:
|
[
"Toward the cathode.",
"Toward the anode.",
"Within the nucleus of an atom."
] | 1
|
Regarding the current PET/CT scanners, which of the following two statements is true?
|
[
"PET and CT are in the same gantry, and acquisition of PET and CT occurs simultaneously.",
"After the CT scan, the PET image is acquired."
] | 1
|
How long does it take for the free induction decay of an NMR line with T2 = 0.5 s to decay to 1% of its initial amplitude?
|
[
"2.30 s",
"2.90 s",
"3.20 s",
"3.70 s"
] | 0
|
Rats have a higher glucose metabolic rate (GMR) in their brain than humans. Can we conclude they are smarter ?
|
[
"Yes, some studies tend to show that rats learn faster than humans.",
"No, some studies indicate an inverse relationship between GMR and intelligence.",
"Studies have shown that there is no correlation between GMR and intelligence"
] | 1
|
Which element within the body is the most important regarding MRI?
|
[
"Oxygen",
"Carbon",
"Hydrogen"
] | 2
|
You discover a mummy. Which imaging technique will you use?
|
[
"MRI",
"PET scan",
"X-ray radiography"
] | 2
|
Which interaction between X-ray beam and matter results in the largest patient dose?
|
[
"Characteristic",
"Compton's scatter",
"Bremsstrahlung",
"Photoelectric effect"
] | 3
|
What is the optimal \(TI\) to detect changes in \(T_1\)?
|
[
"\\(TI = T_1\\)",
"\\(TI = T_1/2\\)",
"\\(TI = \\pi/2\\)"
] | 0
|
Let's consider a drug distribution rate from a compartment 1 to 2. In the simplest case, this rate is assumed to be...
|
[
"Approximately constant",
"Decreasing exponentially",
"Proportional to the mass (or concentration) of the drug in compartment 1."
] | 2
|
Which component of an MRI system allows to choose exactly where in the body to acquire an image?
|
[
"Gradient magnets",
"RF pulses",
"Contrast agents"
] | 0
|
Compared with SE (spin echo), GRE (gradient echo) sequences use
|
[
"Longer \\(TR\\)",
"Shorter \\(TR\\)",
"Longer \\(TE\\)",
"Shorter \\(TE\\)"
] | 1
|
Which of the following statements is true?
|
[
"Is due to photoelectric absorption and Compton scatter.",
"Gives the relative number of x-rays emitted at each photon energy.",
"Depends only on the braking radiation.",
"Is produced by electron transitions between the electron shells."
] | 1
|
What are the types of coincidence events?
|
[
"True",
"Random",
"Scattered",
"Multiple"
] | 0
|
In a gamma camera, what is the component that "converts" the light signal in electronic signal?
|
[
"Dynode",
"Photocatode",
"Photomultiplier tube",
"Scintillator crystal"
] | 2
|
What is the name of the Austrian mathematician who proved in 1917 that it was possible to reconstruct a three-dimensional object from the infinite set of all of its projections?
|
[
"Radon",
"Tsien",
"Bracewell",
"Cormack"
] | 0
|
How long (in multiples of T1) is it necessary to wait for Δn(t) to relax to 99% of Δneq??
|
[
"2.61 T1",
"4.61 T1",
"5.02 T1",
"7.03 T1"
] | 1
|
What is the NMR frequency of 1H in a 23.488 T magnetic field?
|
[
"1000.0 Hz",
"1000.0 kHz",
"1000.0 MHz",
"1000.0 GHz"
] | 2
|
Which phenomena does the term "beam hardening" describe?
|
[
"The decrease in average photon energy of a heterogeneous X-ray beam",
"The increase in average photon energy of a homogeneous X-ray beam",
"The increase in average photon energy of a heterogeneous X-ray beam",
"None of the above"
] | 2
|
When incoming electrons interacts with bound electrons in the X-ray target, ionization of the atom can occur...
|
[
"if the absolute energy transferred exceeds the absolute binding energy of the shell involved.",
"as well as emission of alpha and beta particles.",
"and gamma ray emission too.",
"when the kinetic energy of the incoming electrons is less than the binding energy of the shell involved."
] | 0
|
For each of the following compounds determine which protons are magnetically equivalent:
|
[
"benzene",
"the 2,5 protons in furan",
"F2C=C=CH2"
] | 0
|
How is termed the fraction of attenuated incident photons per unit thickness of a material?
|
[
"Linear attenuation coefficient",
"Mass absorption coefficient",
"Coefficient of scattering",
"Mean attenuation ratio"
] | 0
|
Predict the total number of lines in the 1H spectrum of CH3Cl
|
[
"0",
"1",
"2",
"3"
] | 1
|
How is called the reduction of intensity when an X-ray beam interacts with matter?
|
[
"Scatter",
"Attenuation",
"Transmission",
"Differential absorption"
] | 1
|
In a "90 degree impulsion" when the RF pulse is applied...
|
[
"The excess of protons spins parallel to \\(\\vec B_0\\) disappears.",
"Proton spins precess in phase.",
"All of the above"
] | 2
|
Why using a rotating reference frame to describe motion of magnetization?
|
[
"Because the formulas were developped historically considering rotating frame.",
"To simplify the complex motion of precessing spins.",
"It is the international standard."
] | 1
|
Which action allows the formation of a spin echo?
|
[
"Reversing the direction of \\(\\vec B_0\\).",
"Flipping proton direction by a radiofrequency pulse.",
"Applying a negative magnetic field gradient."
] | 1
|
Predict which of the following compounds has the highest and which the lowest 1H chemical shift: CH3Br, CH2Br2 and CHBr3. (from highest to lowest)
|
[
"CH3Br > CH2Br2 > CHBr3",
"CHBr3 > CH2Br2 > CH3Br",
"CH2Br2 > CHBr3 > CH3Br",
"They have all the same 1H chemical shift"
] | 1
|
The three most common parameters used to measure the "quality" of an image are…
|
[
"The spatial resolution, the sensitivity and signal-to-noise ratio.",
"The SNR, the spatial resolution and contrast-to-noise ratio.",
"The image noise, the spatial resolution and signal-to-noise ratio."
] | 1
|
X-ray detection in Emission Tomography involves...
|
[
"A beta camera composed of PMT and scintillating crystal",
"A measure at 180 degrees simultaneously",
"An x-ray tube and a circular detector ring",
"Collimation, scintillation and amplification"
] | 3
|
An MRI system creates an image when:
|
[
"All the hydrogen atoms in the body precess around the same axis.",
"Hydrogens atoms align to the magnetic field.",
"After excitation, the hydrogen atoms go back to their initial position, releasing energy."
] | 2
|
What is the name given to the relaxation process due to a transfer of energy from the nuclear spin system to neighboring molecules?
|
[
"Spin - lattice relaxation",
"Spin - spin relaxation"
] | 0
|
Which of the following is not directly ionizing radiation?
|
[
"Positrons",
"\\(\\alpha-\\)particles",
"Neutrons",
"Protons"
] | 2
|
When was the first MRI human scan performed?
|
[
"1952",
"1965",
"1977",
"1985"
] | 2
|
What is the cause of the light areas seen on a radiograph (low optical density), such those corresponding to bone?
|
[
"Photoelectric effect",
"Image noise",
"Compton interactions"
] | 0
|
What is the essential and biggest component of an MRI scanner?
|
[
"Magnet",
"Digitizer",
"Imager"
] | 0
|
When a hydrogen atom in a magnetic field absorbs radiation energy...
|
[
"Frequency of precession of the nucleus increases.",
"The magnetic moment vector spins faster.",
"The magnetic moment vector of nucleus \"flips\" so that it now opposes the applied field."
] | 2
|
On a chest radiograph, lungs are mainly imaged because of differences in...
|
[
"Mass density",
"Absorption coefficient",
"Attenuation coefficient"
] | 0
|
The following data were measured in an inversion recovery experiment: tau [s]: 2.0 , 5.0 , 10.0 , 20.0 , 100.0 with their respective signal intensities Signal(tau): -0.702 , -0.336 , 0.107 , 0.601 , 1.000. Determine the value of T1.
|
[
"10.5 s",
"12.4 s",
"15.6 s",
"18.1 s"
] | 1
|
How is called a digital imaging system's ability to distinguish between similar tissues?
|
[
"Spatial resolution",
"Good SNR",
"Contrast resolution"
] | 2
|
The recorded sharpness or detail of structures on the image is known as...
|
[
"SNR",
"Contrast",
"Spatial resolution"
] | 2
|
In Doppler effect, which incident angle (in degree) results in no shift?
|
[
"180",
"90",
"45",
"0"
] | 1
|
How is called the difference in brightness between light and dark areas of an image?
|
[
"Spatial resolution",
"SNR",
"Contrast"
] | 2
|
What is the NMR frequency of 13C in a 23.488 T magnetic field?
|
[
"1000.0 MHz",
"251.5 MHz",
"503.0 MHz",
"754.5 MHz"
] | 1
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.