Online Activities – 4th week
Dear students,
Your assignment this week is to find a text in your study/research area in which perfect tenses are being used. Try to look for texts that are relevant for you, you can select one that you have already read or one that you would like to read (this is the chance to do that).
Remember to cite the source of the text.
If it’s a paper or article, you don’t need to analyze the whole text, you can choose a part of it, al least one page, so that we can have a better idea of what the text is about.
After finding the text and selecting the part you want to analyze, answer the following questions:
a) Using your own words, what is main topic of the text you choose? What is the text about?
b) Identify which perfect tenses were used and try to explain why they were used, you should copy at least two sentences to justify your answer.
If you have any questions, don’t hesitate to contact me.
You need to post your answers until September 26th, 8a.m.
You need to post your answers until September 26th, 8a.m.
Have a nice week.
Regards,
Claudia
Septins comprise a conserved family of proteins that are found primarily in fungi and animals. These GTP-binding proteins have several roles during cell division, cytoskeletal organization and membrane-remodelling events. One factor that is crucial for their functions is the ordered assembly of individual septins into oligomeric core complexes that, in turn, form higher-order structures such as filaments, rings and gauzes. The molecular details of these interactions and the mechanism by which septin-complex assembly is regulated have remained elusive. Recently, the first detailed structural views of the septin core have emerged, and these, along with studies of septin dynamics in vivo, have provided new insight into septin-complex assembly and septin function in vivo.
ResponderExcluirhttp://www.nature.com/nrm/journal/v9/n6/abs/nrm2407.html
a)The main topic of this abstract is to show a sumary of the functions of the septin protein family, and illustrate the recent discoveries.
b)...core have emerged, and....
this perfect tense is used to show that keeps emerging more structural views of the proteins.
...vivo, have provided new insight....
this sentence uses a perfect presento to show that new experiments with this proteins keeps showing new insights of how they work
(just a thing, this my name with " D ROSO" is because of my blog, is the name i use in it....)
There has been much effort recently to define the role of adipocytokines, which
ResponderExcluirare soluble mediators derived mainly from adipocytes (fat cells), in the interaction between
adipose tissue, inflammation and immunity. The adipocytokines adiponectin and leptin have
emerged as the most abundant adipocyte products, thereby redefining adipose tissue as a
key component not only of the endocrine system, but also of the immune system. Indeed,
as we discuss here, several adipocytokines have a central role in the regulation of insulin
resistance, as well as many aspects of inflammation and immunity. Other adipocytokines,
such as visfatin, have only recently been identified. Understanding this rapidly growing family
of mainly adipocyte-derived mediators might be of importance in the development of new
therapies for obesity-associated diseases
Source: http://www.nature.com/nri/journal/v6/n10/abs/nri1937.html
A)The text is an abstract about adipocytokines and its potential in developing therapies for obesity-associated diseases thanks to its relations with inflammatory and immunity processes.
B)“There has been much effort recently to define the role of adipocytokines…” – The present perfect was used to talk about a recent event: the effort to define the role of adipocytokines.
”Other adipocytokines, such as visfatin, have only recently been identified…” – The present perfect was used to talk about a past recent situation, that is the identification of Visfatin, without mentioning time.
Este comentário foi removido pelo autor.
ResponderExcluirIs the special theory of relativity, for reasons unspecified
ResponderExcluirand unknown, only an approximate symmetry of
nature? To investigate possible violations of Lorentz
symmetry, we follow earlier analyses [ 1 ] by assuming
the laws of physics to be invariant under rotations
and translations in a preferred reference frame 3. This
frame is often taken to be the ‘rest frame of the universe,’
the frame in which the cosmic microwave background
is isotropic. To parameterize departures from
Lorentz invariance, standard practice has been to modify
Maxwell’s equations while leaving other physical
laws intact.
Although we shall shortly consider more general
Lorentz non-invariant perturbations, let us for the moment
adhere to standard practice: we assume that the
only Lorentz non-invariant term in C is proportional
to the square of the magnetic field strength. Thus, the
in vacua speed of light c differs from the maximum
attainable speed of a material body (here taken to be
unity). The small parameter 1 - c completely characterizes
this departure from special relativity in 3.
In a frame moving at velocity u relative to F, the velocity of light c’ depends on its angle 8 relative to u.
Foru<< l,wefindc’(@ -c+2(c-l)ucos8.The
failure of rotational invariance in the laboratory frame
leads to potentially observable effects that are proportional
to u* ( 1 - c*>. S earches for these anisotropies
yielding null results have provided precision tests of
special relativity.
A laser-interferometric Michelson-Morley experiment
[ 21 found 11 -cl < 10d9. Atomic physicists obtained
stronger constraints using techniques pioneered
by Hughes and Drever [ 31. Prestage et al. [4] found
< lo-‘* and Lamoreaux et al. [ 51 set the current limit
on the velocity difference,
11 - cl < 3 x lo-**. (1)
These limits are obtained for T at rest relative to the
cosmic background radiation and u N 10T3. They
would be two orders of magnitude weaker were 3 at
rest relative to the Sun.
We find additional limits on 1 - c that do not require
precision experiments, yet are comparable in sensitivity to ( 1) . For u < 1, the new constraints do
not depend on the motion of the laboratory relative
to F. They follow from the mere existence of highenergy
cosmic rays. Suppose c > 1. Because the photon
4-momentum (E/c, E) is timelike, a sufficiently
energetic photon can and will decay rapidly into an
electron-positron pair. The threshold energy for y --+
ef + e- is Eo = 2mf @Ci, with m the electron
mass. In first-order perturbation theory (using an invariant
matrix element and the modified photon dispersion
relation), we obtain for the decay rate in 7
I = a(c - l)E{ 1 - (Eo/E)2}3’2 . (2)
A photon that is produced with energy well
above Eo decays rapidly, with mean lifetime r N_
3(&/E) /m ns. Hence a primary cosmic-ray
photon with E > Eo cannot reach Earth. However,
primary photons with energies up to 20 TeV have
been seen [ 61. Thus we obtain the bound ’
c - 1 < 1.5 x lo-15. (3)
(If this bound were saturated, the threshold energy for
photon decay would be 18.6 TeV and the mean range
of a 20 TeV photon would be 8 cm.) Eq. (3) is weaker
than ( 1) , but it arises, so to speak, for free.
Source: http://www.sciencedirect.com/science/article/pii/S0920563299004351
A-) The article discusses about experiments involving neutrinos and cosmic rays permormed to check the consistency of Special Relativity Theory, in addition to the tests initially performed by Michelson and Morley.
B-) In the statement “Searches for these anisotropies yielding null results have provided precision tests of special relativity.”, Present Pefect Tense is used to show that now the results of an action in the past have a consequence (to confirm special relativity).
In “ However, primary photons with energies up to 20 TeV have been seen.” , Present Perfect continuous in passive form was used to emphasize that primary photons were observed and are currently observed.
Review - Enzymes of triacylglycerol synthesis and their regulation
ResponderExcluir1. Introduction
Bacteria, yeast, plants, and animals all have the ability to synthesize triacylglycerol (TAG), a critical function during both periods of nutritional excess and nutritional stress. In eukaryotes TAG is an energy store and a repository of essential and non-essential fatty acids and precursors for phospholipid biosynthesis. Fatty acids are packaged in VLDL and chylomicra as TAG for distribution to peripheral tissues where they can be used immediately or stored. TAG is also an essential component of milk (Fig. 1, pathway 1). In addition, forming TAG acts to attenuate diacylglycerol (DAG) signals and to protect cells from sudden increases in fluxes of fatty acids and acyl-CoAs (Fig. 1, Pathway 2). It is generally believed that these molecules are potentially membrane-damaging and that their incorporation into TAG enables them to be converted to a non-toxic compound that can be safely stored. Thus, even brain tissue has the ability to synthesize TAG [1]. TAG is contained in lipid droplets in every cell in which it has been looked for. Like the huge droplets in fat cells, these smaller droplets are enclosed by a monolayer of phospholipid and specific proteins like ADRP that probably regulate their formation, growth, and issolution (Fig. 1, pathway 3) [2,3]. Finally, TAG stores can be partially hydrolyzed to form DAG, a precursor of the major phospholipids phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine
(Fig. 1, pathway 4), and the DAG hydrolyzed from TAG can be phosphorylated to form PA, the
precursor of phosphatidylinositol, phosphatidylglycerol and cardiolipin (Fig. 1, pathway 5).
Energy-dense TAG stores can free organisms temporally and spatially from the need for an
immediate energy supply and provide a reserve depot that can be used when local resources fail
or when specific kinds of fatty acids or lipid precursors are required. In bacteria, the few studies that have been performed suggest that TAG is synthesized during times of stress and resource depletion, and that the TAG is used to generate precursors that will be converted to phospholi- pids or other products when food supplies improve and growth resumes [4–7]. Similarly, Tetrahymena use their TAG stores primarily for PL synthesis [8]. In animals, TAG is both an energy store (Fig. 1, pathway 3) and a depot of phospholipids and signaling molecules. In this view it is not surprising that higher organisms have developed several pathways for TAG synthesis as well as several modes of regulation. This review will focus primarily on recent studies of the enzymes of TAG synthesis with particular emphasis on cloned isoforms. Excellent reviews are available on TAG synthesis and regulation in plants [9–11] and yeast [12], DAG metabolism [13], CoA independent transacylases [14,15], and transcriptional control [16]. The older literature contains additional information of interest concerning the enzymes of glycerolipid synthesis [16–19].
[Rosalind A. Coleman, Douglas P. Lee
Departments of Nutrition and Pediatrics, University of North Carolina, Chapel Hill, NC, USA. Progress in Lipid Research 43 (2004) 134–176.]
a) This article reviews the current status of knowledge about triacylglycerols (TAG) enzymatic synthesis, an important chemical pathway in all eucaryotic cells. The TAG are the major source of energy storage in these living cells, that's why they are so relevant.
b) 1. In this statment, the Past Perfect tense is used to indicate something that started in the past (looking for in cells) and haven't necessarily finished: "TAG is contained in lipid droplets in every cell in which it has been looked for"
2. In this one, there's the same idea - the performig of studies is still happening: "In bacteria, the few studies
that have been performed suggest that TAG is synthesized during times of stress and resource
depletion"
Worrying trends in econophysics
ResponderExcluirMauro Gallegatia, Steve Keenb, Thomas Luxc, Paul Ormerodd, Corresponding Author Contact Information, E-mail The Corresponding Author
a Universita’ Politecnica delle Marche, Ancona, Italy
b University of Western Sydney, Australia
c Department of Economics, University of Kiel, Germany
d Volterra Consulting, London, UK
Available online 12 May 2006.
Abstract
Econophysics has already made a number of important empirical contributions to our understanding of the social and economic world. These fall mainly into the areas of finance and industrial economics, where in each case there is a large amount of reasonably well-defined data.
More recently, Econophysics has also begun to tackle other areas of economics where data is much more sparse and much less reliable. In addition, econophysicists have attempted to apply the theoretical approach of statistical physics to try to understand empirical findings.
Our concerns are fourfold. First, a lack of awareness of work that has been done within economics itself. Second, resistance to more rigorous and robust statistical methodology. Third, the belief that universal empirical regularities can be found in many areas of economic activity. Fourth, the theoretical models which are being used to explain empirical phenomena.
The latter point is of particular concern. Essentially, the models are based upon models of statistical physics in which energy is conserved in exchange processes. There are examples in economics where the principle of conservation may be a reasonable approximation to reality, such as primitive hunter–gatherer societies. But in the industrialised capitalist economies, income is most definitely not conserved. The process of production and not exchange is responsible for this. Models which focus purely on exchange and not on production cannot by definition offer a realistic description of the generation of income in the capitalist, industrialised economies.
1a)This text is about an introduction to the principal issues of the physical methods used on economics and a overview of some papers about that theme.
1b)
1* Econophysics has already made a number of important empirical contributions to our understanding of the social and economic world. (l.1)
2* More recently, Econophysics has also begun to tackle other areas of economics where data is much more sparse and much less reliable.(l.3)
3* a lack of awareness of work that has been done within economics itself.(l.5)
In the sentence 1* the main idea lies in the fact that econophysics still making contributions. The sentence 2* uses the same idea to show continuity that it is still tackling more areas of economics. The use on the 3* sentence is to emphasize the concern not the time nor the subject.
Correlation of B-FABP and GFAP expression in malignant glioma
ResponderExcluirAbstract
The murine brain fatty acid binding protein (B-FABP) is encoded by a developmentally regulated gene that is expressed in radial glial cells and immature astrocytes. We have cloned the human B-FABP gene and have mapped it to chromosome 6q22-23. We show that B-FABP mRNA is expressed in human malignant glioma tumor biopsies and in a subset of malignant glioma cell lines, as well as in human fetal retina and brain. Malignant glioma tumors are characterized by cytoplasmic bundles of glial fibrillary acidic protein (GFAP), a protein normally expressed in mature astrocytes. Establishment of malignant glioma cell lines often results in loss of GFAP. The subset of malignant glioma cell lines that express GFAP mRNA also express B-FABP mRNA. Co-localization experiments in cell lines indicate that the same cells produce both GFAP and B-FABP. We suggest that some malignant gliomas may be derived from astrocytic precursor cells which can express proteins that are normally produced at different developmental stages in the astrocytic differentiation pathway.
http://www.nature.com/onc/journal/v16/n15/abs/1201740a.html
a)the article is about the relation between the expression of brain fat acid bound protein and glial fibrillary acidic protein and malignant glioma tumors. They found out that some tumors express this proteins that are usually only expressed by cells in diferent developmental stage.
b)
"We have cloned the human" ... "have mapped it to chromosome"
Both setences express actions that happened at an unspecified time before now. The exact time is not important.
hey guys, was I the only one that couldn´t find a full article? Every single one that I tried, in nature or ncbi, I should pay to get acces to the full text...