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  • Mohan Chandra Pradhan added an answer in Wireless Communications:
    How do I design a loop filter of DPLL in OFDM system?

    Hi all,

    I am designing a loop filter of DPLL in 802.11ac OFDM system. The DPLL tracking is achieved by pilot symbols inserted into OFDM symbols.

    Importantly, the coefficients of loop filter significantly impact the PER ( packet error rate ) of the OFDM system.

    So, does anyone know that how to design or determine the coefficients of the loop filter is able to maximize the performance of the OFDM system.

    Many thanks

    Jiajun Zhu

    Mohan Chandra Pradhan

    Dear Dr Zhu

    please refer to the attachments if it is helpful for you.


    + 1 more attachment

  • Lesly Llaja Salazar asked a question in Peru:
    This is Crassispira cerithoidea?

    This specimen was colected in Bocapan, north of Peru in sand substrate.

    + 1 more attachment

  • Juan Manuel Velazquez-Gutierrez asked a question in WDS:
    How do you understand the coexistence in Wireless Communication Systems?

    The coexistence of wireless devices (WDs) represent an important challenge. As far I understand the coexistence concept considers at least two considerations - spectrum (frequency) & coverage area- and I include other one: time. With these three 'parameters' I can describe, in wide sense, the coexistence but I do not know if my context is complete, then I would like to know your idea,

    -How do you define Coexistence of WDs?     

    -What parameter must I consider to define it?

    Your comments are important for me.


  • Margaret Ward added an answer in History of Mathematics:
    Does anyone know why the mathematics of Rome was at a lower level than the lowest level mathematics of ancient Greece?

    More specifically, why is it so? Who is the culprit why Rome was not delivered of a single scientific discovery?

    Margaret Ward

    Please would you elucidate to a non-mathematician, concerning Justinian?

  • Ben Wurim Pam added an answer in Export:
    Do you need free import export training ?

    Contact: philipnelsonassociates@yahoo.com

    Ben Wurim Pam

    Yes Mr Nelson, but in which practical areas?

  • Kennedy Gicini asked a question in Ascorbic Acid:
    What is the mechanism and theory ofreduction of hexacyanoferrate by ascorbic acid?

    experiment report

  • María José Docampo added an answer in Zymography:
    Why in my zimography, does the gel separation of animal serum show uneven staining after electrophoresis?

    During the zimography after the staining gel appeared different colors separating the gel, giving us trouble in the analysis.What can I do if I am following the Krisztina Kupai protocol, PharmD, PhD,2011.

    María José Docampo

    Dear Angela,

    I agree. It looks quite good!

  • Vikash Pandey added an answer in Light:
    Polariztion states by assuming particle nature of light???

    Hello everyone, i did not understand why we are finding polarization states by assuming light as a wave??? Don't you think that if we assume light also particle i.e photon then by using quantum mechanics we can find accuracy in finding polarization states???

    Maybe i did not explain my question well but i think a good thinker can easily guess my thinking. Thanks

    Vikash Pandey

    accuracy and quantum mechanics?  They are poles apart. haven't heard of uncertainty principle? Polarization is better explained using wave property.

  • Suvadip Roy added an answer in FPGAs:
    Diversity and Redundancy of FPGA based systems used for safety critical applications?

    What should be the basic safety measures taken in terms of tool diversity, redundancy etc for using FPGA based system in safety critical application? What about Tool validation and reliability of software tools used in the design deveopment of the logic implemented in the FPGAs?

    Suvadip Roy

    What about the aspects of using IntellectualProperty Cores (IP) in design of Safety critical systems and use of different HDLs to program the same FPGA

  • Erkki J. Brändas added an answer in Cognitive Systems:
    Is Chalmers' so-called "hard problem" in consciousness real?

    In his 2014 book "Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts" Stanislas Dehaene wrote "Chalmers, a philosopher of the University of Arizona, is famous for introducing a distinction between the easy and the hard problems. The easy problem of consciousness, he argues, consists in explaining the many functions of the brain: how do we recognize a face, a word, or a landscape? How do we extract information form the senses and use it to guide our behavior? How do we generate sentences to describe what we feel?

    “Although all these questions are associated with consciousness,” Chalmers argues, “they all concern the objective mechanisms of the cognitive system, and consequently, we have every reason to expect that continued work in cognitive psychology and neuroscience will answer them. By contrast the hard problem is the “question of how physical processes in the brain give rise to subjective experience … the way things feel for the subject. When we see for example, we experience visual sensations, such as that of vivid blue. Or think of the ineffable sound of a distant oboe, the agony of an intense pain, the sparkle of happiness or the meditative quality of a moment lost in thought … It is these phenomena that poses the real mystery of the mind”."

    Stanislas Dehaene's opinion is "that Chalmers swapped the labels: it is the “easy” problem that is hard, while the “hard” problem just seems hard because it engages ill-defined intuitions. Once our intuition is educated by cognitive neuroscience and computer simulations, Chalmers’ “hard problem” will evaporate".

    Personally, I agree with Stanislas Dehaene's opinion.

    Erkki J. Brändas


    From my point of view coding and decoding should be rooted in the same mechanism as you may anticipate from my earlier answers to Alfredo.

    This view is also commensurate (have you heard this word before?) with teleonomic evolution from marginal communications between cells to all kinds of communications in a “civilization” of actual life forms. Cardiovascular systems, brain functions, consciousness, feelings etc. occur along the chain of events.

    This interpretation is not in conflict with your retinoid system and its importance to understand and predict illusions, hallucinations etc. and it also agrees with the astrocyte mechanism of Alfredo.

    My comments are not the result of a deeper understanding of the neurological examination. However, this might be a blessing in disguise, since my conclusions draw from the application of physical laws in chemical physics, without watching in which “direction the wind blows”.

  • Muhammad Mudasir Firdosi asked a question in Religion:
    Why does religion become first port of call during social and economic strife?

    Why does religion become first port of call during social and economic strife?

    Within religion, why does a large chunk of the population not go deeper into orthodox religion but head instead towards these new age guys with their superficial cosmologies and simplistic solutions?

  • Khaled Hamdy asked a question in Chips:
    According to Kinzle Equation how to calculate the cross section area of undeformed chip in face milling?

    the problem in the three parameters that depth of cut, chip thickness and width of chip

  • Vikash Pandey added an answer in Applied Mathematics:
    How can i solve the system of ODE equations like attached file?

    can anyone help me to solve the system of ODE equations like attached file?

    Vikash Pandey

    Use chain rule and some substitutions and then rearrange the terms, it will be easier then!

  • Virendra Kumar Saxena added an answer in TDS:
    Like pH, EC and TDS meter can we not think about sensor based equipment to measure the conc of nutrients (N, P2O5, K2O, S, Zn, B, Fe, Cu, Mg etc..) ?

    We are still following very old chemical methods to distinguish the nutrients in soil and water. It consume lot of energy, chemicals, manpower and it also pollute the environment.   

    Virendra Kumar Saxena

    Gaurav you point out a very important question/suggestion. Some development in this regard is very much required.  

  • John Clarkson added an answer in Oligopeptides:
    How can I quantify amide species in reaction mixture by UV-Vis method preferably?

    I need to quantify short oligopeptides from reaction mixture or at least show the increase in amide bonds concentration when compared to reference sample. 

    John Clarkson

    Obtain UV spectrum of Reference material and compare with reaction mixture throughout reaction time line: do you see the increase at 205nm, as suggested?

    You may wish to explore ATR FTIR, by drop casting, (drying) your samples onto the ATR crystal surface? See attached links and papers on use of FTIR (and Raman) of proteins, which uses the Amide I band for secondary structure analysis.

    + 3 more attachments

  • Paul Reed Hepperly added an answer in Conservation Agriculture:
    Has there been any study on food quality of the produce obtained from Conservation agriculture, long term fertility experiment?

    Has there been any study on food quality of the produce obtained from Conservation agriculture, long term fertility experiment?

    Paul Reed Hepperly

    Dear Naveen Kalra To the extent the soil organic matter and biological activity and chemical content of soil is enhanced the food from that soil will be similarly enhanced. This will work regardless of the practices and systems are employed. The maize is maize argument is strictly an argument to favor standardized practices with vested corporate interests. Follow the money! Paul

  • Alvaro Sanz Rubiales added an answer in Trials:
    What is the impact of crossover in clinical trials?

    In oncology randomized controlled trials, offering patients the opportunity to cross over to treatment from the other arm at disease progression is a routine practice to address ethical issues (associated with placebo controls, for instance, or even when comparing two active treatments, such as many trials with target-therapy in 1st-line treatment of NSCLC). In this situation, it is common to justify that the intervention has a PFS benefit but not an OS benefit due to the crossover. On the other hand, some colleges say that “true good” treatments can impact in OS despite crossover and minor gain in PFS should not be considered relevant. How should we interpret data form these studies? How to avoid underestimate a real benefit? How to avoid overestimate it?

    Alvaro Sanz Rubiales

    The crossover design minimizes the differences between arms and limits, sometimes severely, the interpretation of results. But as noted earlier, the reason for this design is usually ethics. A "clean" comparison between two treatments simplifies the design and help to discriminate the results. But it does not seem to be honest to block the access to the apparently best treatment to those patients who accept already help in research. And almost no patient would refuse the chance to try (albeit a little later) the treatment that is supposedly superior or that already is showing better results than the one he is receiving in his assigned arm.

  • Marcel M. Lambrechts added an answer in Fitness:
    What is your definition of 'fitness'?

    It's all in the question


    Marcel M. Lambrechts

    Perhaps everything in the human body can be defined as fitness components given that all will contribute to the performance, directly or indirectly, e.g. without a stomach no energy, no fitness component, no fitness?

  • Bachir Achour added an answer in Evaporation:
    How to calculate evaporation from water surface?

    For comparing  calculation methods of evaporation 

    Bachir Achour

    Dear Mirwais,

    I suggest you the following link in which there is a calculation toolbox


    With my best regards

    Prof. Bachir ACHOUR

  • Hossein Javadi added an answer in General Relativity:
    Universe is static!!! Yes or no?

    Space of Universe is static! Yes or no?

    Question: Are there any observations that do not fit into the model static space of Universe, are there any theoretical obstacles to the existence of such a model?

    I assume that the Universe is eternal, infinite and static, it is not expanded and not curved, it is possible to construct a preferred inertial frame of reference in which the CMBR is most isotropic. The matter in this space evolves, but the average density of matter and energy (in large enough volumes) fluctuate within a rather broad range.
    The light in this model is "tired", the speed of light depends on the optical density intergalactic medium. Gravity is also "tired" t.i. weakens a little faster R2. The energy of destroying matter goes into the surrounding vacuum. The excess energy from the vacuum give rise to new particles of matter.

    I state that all the observed cosmological effects can be explained in such a Static Model of the Universe.
    See attached "Basic_Cosmological_Formula_1_En.pdf"

    Dear colleagues, I do not ask, what are the problems faced by other theories (though I would be interested in your opinion on that. The General theory of relativity is not applicable to the entire space of the Universe).

    Hossein Javadi

    Dear Aleš
    "...universe (the one we can observe) is open, closed or isolated." Yes, you are right.
    You have written: "All graviton particle models of gravity have failed experimental ..."
    These two above problems have related to each other and in my view they has unique answrer. We need a new definition of graviton, and then we need to reconsider the relativistic Newton's second law.



    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: To date, there is no way to explain the process that describes how particles as photon absorb gravitons. According to the results of our years-long research we can definitely say that the best way for explain this process is using color charge concept from photon properties. This model might be called "Creative Particles of Higgs" or CPH theory. Gravitons behave like charge particles and in interaction between gravity and photons, gravitons convert to negative and positive color charges and also magnetic color. These color charges and magnetic color form the electromagnetic energy.
      Full-text · Dataset · Mar 2014

    + 1 more attachment

  • Lilliana Ramos-Collado added an answer in Debator:
    Is public art "public"? Is it art? Who's its owner/its public? What does it mean? We need it? Who will preserve it? Can any such artwork be universal?

    With respect to “public art,” an examination of the state of the question points to at least two ways in which that concept may be defined, two “circles” within which it may fall: It may be related either to the space the art object is to occupy (which might be called a “public space”) or to the art object itself (which might then be called “public art”). Here, we might pose several questions that seem either to make it easier to understand the public art/ public space duality, or to make such an understanding impossible. We might, for example, ask questions about:

    Legitimacy (Is the work an art object?)  

    The constitution of the cultural imaginary with respect to what a “public space” is and what “public art” is (Does the work reflect my identity?)

    Ownership of the space and the work (Who owns what?)

    Authorship (Is the work created by an individual with personal title to it, or is it created on behalf of a collectivity?)

    Decency and decorum (Is the art appropriate to the space it occupies or will occupy, and is it suitable for being seen by men, women, and children?)

    Preservation and conservation (Who shall assume the ownership of the patrimonial work and be responsible for its explanation and esteem, defense, custody, maintenance, restoration, and permanence?)

    Each of these issues raises a debate, implicit in the very existence of the public-art object, and each debate may be different. And each potential controversy suggests its own “public,” in the sense of audience or interest group, each with its own defining expectations. Below a polemical article I wrote about a country-wide public art project:


    Lilliana Ramos-Collado

    Excellent questions, Marcel. I have the impression that your questions are actually tentative answers. I like them for their polemical value. The challenge is precisely that: is it possible for an art object to have a relatively stable meaning throughout a community? If that communal meaning could exist, could it last through time? How long and why? Thanks for sharing your questions! 

    Best regards, Lilliana

  • Gerard Van Rhoon added an answer in Hyperthermia:
    What are the presumed advantages and disadvantages of non-invasive RF capacitive and RF inductive hyperthermia for cancer treatment?

    A lot many reports have emerged in the recent past investigating non-invasive RF hyperthermia using nanoparticles for cancer treatment. What are the presumed advantages of capacitive RF hyperthermia over inductive RF hyperthermia or vice versa? Since capacitive RF hyperthermia can cause heating up of ions, would its use on the body produce undesirable heating effects unlike inductive hyperthermia?

    Gerard Van Rhoon

    Dear Sajid Fazal,

    The biggest difference is whether the technology requires invasive procedures yes or no.

    In general non-invasive RF electromagnetic heating can be delivered using:

    RF-capacitive coupling: two electrodes are placed on either side of the body and RF-current is flowing between both electrodes. The advantages are relative simple technology (so cheap systems). Disadvantages in most clinical applications is that the E-field is directed perpendicular on tissue transitions, more specifically those between fatty and muscle tissue. In this situation flux is constant resulting in preferential fat heating over muscle heating. Skin cooling with cold water is used to prevent over heating of fatty tissue. This works for patients with fat layers of less than 2 cm thickness. Western patients have in general fat thicknesses of more than 2 cm RF. A second disadvantage is that RF-capacitive heating does not provide a mean for focusing of RF-energy to the treatment volume. Frequencies used in clinical practice vary from 8 to 27 MHz.

    RF-inductive coupling: RF-energy is transferred using inductive fields. The applicator consists often of an helical coil or pancake coil. In the early days of hyperthermia large single and multiple turn helical coils have been placed around the patient. RF-currents will be induced in the peripheral layers  of the body causing heating. Deep heating is poor as in the center of the coil no currents flow. Advantages: energy coupling through air, avoiding direct contact of the heating system with the patient. Disadvantage: poor deep heating and no ability to focus heating at the target volume. Frequencies used in clinical practice vary from 8 to 27 MHz.

    RF-radiative coupling: multiple radiative antennas are used to couple energy to the patient. Water is used as a coupling medium between the antenna and the human body to preferentially transfer the energy to the patient. Further the water provides also a possibility to cool the superficial tissue, reduces the antenna size (high relative permittivity) and reduce reflection of RF-energy from the skin (in comparison a tissue contrast of air-skin has 60% reflections versus nearly zero for water-skin).

    The main advantage of RF-radiative energy transfer is the ability to focus RF-energy at the target volume by optimizing the phase and amplitude settings per antenna. Using hyperthermia treatment planning phase and amplitude settings can be optimized based on the feedback of measured temperatures and patient information.

    All the above is explained and demonstrated in the attached papers.

    Besides the non-invasive technologies one can use more invasive procedures.

    The most recent technology with promising potential for selective tumor heating is nano-particle inductive heating. Multiple papers have been published on this topic. A special issue of the Int. J. of Hyperthermia was devoted to this technology. Please check this literature.

    Although the ultimate idea is to coat the nano-particles with proteins that connect to receptors at the tumors cell, the current practice is that the nano-particles still must be injected directly into the tumor in order to obtain a sufficient high concentration of nano-particles to allow sufficient energy delivery to increase tumor temperature to 43°C.


    Gerard van Rhoon 

    + 8 more attachments

  • Asimina Voskaki asked a question in Urban Environment:
    Urban climate change resilience assessment framework

    Hello!!! I would like to have your views and thoughts on what to include in a climate change resilience assessment framework for urban environments. Thank you

  • Mayadhar Barik added an answer in Identification:
    Identification of motifs?

    Hello there,

    Can anyone tell me how to identify 'prokaryotic / eukaryotic inhibitory motifs', + the technical definition of 'AT-rich' and 'GC-rich' sequence stretches respectively


    Mayadhar Barik

    May read one practical text book. 

  • Naveen Kalra added an answer in Agroforestry:
    How to measure / parameters for the productive efficiency of agroforestry systems for carbon sequestration?

    If there are two or three different agroforestry system to be evaluated for efficiency of productivity in terms of carbon sequestration potential, then what are the parameters to be used for comparison

    Naveen Kalra

    Ahmad, thanks for uploading nice paper in this regard, as far as the question asked is very appropriate in the present context, the indicators for c-sequestration by adoption of agro-forestry could be Soil Organic Carbon  dynamics within the profile (b periodic measurements), Net primary productivity from the agro-forestry system in comparison with the mono- agro or forestry systems, emission of GHGs from the system comparisons, soil environment changes (physical, chemical and biological) by the new changed land use type, the relationship of change with the climatic conditions.


  • Ramchandra Pageni asked a question in Quantum Mechanics:
    Show that linear momentum is not quantised?

    quantum mechanics

  • Mayadhar Barik added an answer in Mice:
    Has anyone come across a study comparing the genetic profiles of C57BL/6J mice to outbred CD-1's?

    Specifically in regards to inflammation and cartilage specific genes

    Mayadhar Barik

    little difficult 

  • Renzo Bianchi added an answer in Psychological Disorders:
    What is the distinction between moral and mental disorder?

    Do moral disorders lead to mental psychological disorders in individuals?  

  • Mayadhar Barik added an answer in Real-Time Systems:
    Can we reuse StepOne spectral calibration kit?

    We need dye calibration for our step-one real-time system. One of our friends have a calibration kit with single used. can we reuse it or not.

    Thank you for your attention.


    Mayadhar Barik


  • Ramchandra Pageni asked a question in Quantum Mechanics:
    Show that linear momentum is not quantised?

    quantum mechanics