prompt_front: Now, answer the following question based on the text below, only give me the answer and do not output any other words.

Question: Who compiled the 88-page letter to the HHS regarding vaccine safety?

Read the following text and answer briefly.

Context 1: A special tribute to Del Bigtree (pictured) and his team at ICAN for his stunning 88 page letter to the HHS regarding vaccine safety  As Del reported - in the latest edition of Highwire - the letter, in response to an earlier reply from the then acting Director National Vaccine Program Office, Melinda Wharton, took virtually a year to compile, and is a meticulous piece of research  Most sensationally they researched the HHS claim through US government archives that at least some pediatric vaccines had been trialed against genuine placebo, and came to a negative conclusion  Not only that, they established that none of the vaccines those vaccines had been trialed against had ever been trialed against genuine placebo either  At the end of the line the toxic products were only being compared with other toxic products, rather than against saline 
Leave aside the sceptics, for any believer in the vaccine program as a necessary intervention in public health, this should be a devastating finding  Fundamentally, the research into the safety of any of the products before marketing was simply not there  The manufacturers apparently had no faith that their proto-products could withstand this scrutiny, and for the rest they just did not care: under the alleged imperative of protecting the population it seems anything went  So even before all the sham monitoring procedures and reviews which Del and his team dismantle in forensic detail we are left with the proposition that none of the present products being given to US children – and frequently other children across most of the developed world – have any meaningful pre-marketing safety data all  If you are believer in the program you have been let down: if you wanted a program with any pretensions to safety - supposing such a thing to be possible - it looks like you would have to start from scratch  The manufacturers did this: the governments, the politicians and the regulators (internationally) let it happen 
This damning document is published simultaneously with a demand in the UK from the Royal Society for Public Health (which I had never heard of) to shut down comment about vaccines on the web  It echoes calls from Seth Berkley of GAVI, Heidi Larson of the Vaccine Confidence Project and the European Parliament  The pamphlet airily dismisses concerns that vaccines have side effects or that you could possibly have too many  It is pure public relations, and if the RSPH claims to be "independent" it also admits that the publication was paid for by Merck, a detail which was reported by British Medical Journal and the Guardian, but not true to form by the BBC  We have, in truth, been building to this moment for two decades: as the evidence piles up that every single aspect of the program lacks integrity or is simply rotten to the core all the perpetrators can do is call for the silencing of their critics, and maintain the products are safe because they say so 
Please help give the ICAN letter the widest possible distribution, particularly to politicians 
"The outcome of disease always depends both on the virulence of the pathogen and the health of the individual immune system "
Nope  This makes no sense  Lots of people who seemed vibrant will get a very severe case of the same illness that a vulnerable baby overcomes in a day 
And under the germ theory it doesn't matter how strong your immune system *was*  Once it's been overcome by the pathogen it is every bit as weak as anybody else's with that pathogen 
What you say makes no sense  There's no reason for me to reply to you again 
"Why do you think that within a few years (not many) of the introduction of the vaccines for them, pertussis, measles, mumps, rubella, tetanus, diphtheria, Hib disease, and chickenpox (and others) almost entirely disappeared?"
Why do you keep asking this question when I've already provided the answer hundreds of times? Why are you so desperate to believe the people who you already recognize are harming our children?
Why would Walter Reed be any more trustworthy than Paul Offit or Senator Pan? Why would Jenner or Pasteur?
And you went no way to explaining my arguments against germ theory  If we are attacked by billions of viruses every day then if even a tiny fraction of them are pathogenic then we couldn't possibly survive  And even if we could, we would already be immune rendering every vaccine pointless  Once we had survived our first few days on earth, then we could never get sick again 
If that's wrong then we must conclude that precisely 0% of germs are pathogenic 
Plus your comment about the immune system completely misunderstood my point  The immune system does not allow us to overcome our math problem  In fact, it makes it worse 
You did provide one solitary example of a patient with what are presumably yellow fever symptoms but you didn't say whether they had been given any toxic medical treatments 
And like I said before, the whole "incubation period" is more than a little suspicious  Clearly they never found what they thought they would and just rigged the results to tell them what they want to hear 
Like every other germ theorist/vaccine promoter in history 
Many kinds of bacteria are constantly evolving and changing, like flu viruses  Others are more stable over time, like the yellow fever virus  Those that change develop new ways of infiltrating the cells of the organism being attacked (from our point of view, from its unconscious point of view, it's just carrying out its need to replicate, which it can only do inside the cells of its host)  The changes which allow it to better infiltrate are more successful and result in more viruses with those traits 
Our immune system is designed to detect and destroy potentially dangerous invading pathogens  Many bacteria are usually harmless and absolutely necessary  The minority are dangerous, and most people's immune systems do a good job of analyzing them and killing them, often with no signs of disease  Others experience a clinical infection, and the immune system usually mounts a successful attack on them 
The outcome of disease always depends both on the virulence of the pathogen and the health of the individual immune system  Vaccines are usually effective in giving immunity to the targeted diseases  They also have many dangers which everyone should be aware of, and vaccines should be avoided whenever possible  But in the case of the most dangerous diseases, everyone should learn about them and think about what he wants to do to protect himself and his children from them, considering all the factors involved  And no one can have 100% certainty that he has made the right decision, but that's life  But if you live in the Congo and many people around you are currently dying of yellow fever, then that means that you yourself are at risk of being bitten by a loaded mosquito and getting, often dying, of yellow fever  The yellow fever vaccine is very effective at preventing yellow fever  From there, each person must make a choice 
At the end of this stage there is a remission of two or three days  About 80% of those with clinical disease recover at this point, with permanent immunity  The other 20% enter the toxic stage, with a return of the fever, black vomit (coffee-ground emesis), diarrhea, a slowing of the pulse (Faget's sign), jaundice, yellow eyes, yellow skin, and failure of the kidneys, liver, and heart  The patient gets a strange hiccup (like with Ebola, a related disease), falls into a coma, and dies  About half of those patients who enter the toxic stage dies, even now, even with the best of hospital care  The Faget's sign can also occur at the end of the first stage 
You asked specifically about the symptoms of the Americans on Dr  Reed's team who got yellow fever in Cuba in 1900  I'll give the passage from The American Plague (162-5), which describes the course of Jesse Lazear's illness  "In his logbook, Lazear wrote an unusual entry on September 13  In all cases before those, page after page of records, Lazear had used the soldier's name and simply the date he was bitten, with no other attention to the mosquito  A one-line entry with a name and a date  On that day, however, in his elegant hand, Lazear did not write the soldier's name, but instead wrote 'Guinea Pig No  1 ' He went on to write that this guinea pig had been bitten by a mosquito that developed from an egg laid by a mosquito that developed from an egg laid by a mosquito that fed on a number of yellow fever cases: Suarez, Hernández, De Long, Ferández  It was a precise, detailed history that proved beyond doubt that the mosquito was loaded with the virus when it bit a healthy soldier   (If he had entered his name, then his death would have been considered medical suicide by the insurance company, and his wife and two children would not have gotten any payment ) For the next few days, Lazear's life continued much as it had over the last few months in Cuba  He fed and cared for the mosquitoes in the lab    Then he began to lose his appetite  He skipped a few meals in the mess hall  He didn't mention it to anyone, nor did he ask to see one of the yellow fever doctors; instead, he worked hard in the lab trying to ignore the oncoming headache 
"On September 18, he complained of feeling 'out of sorts,' and stayed in his officer's quarters  His head pounded and L  decided to write a letter    (he wrote to his mother, and referred to his one-year old son Houston and the baby his wife Mabel was about to have: they were staying with his mother in the US)    That night, L  started to feel chilled as the fever came on  He never went to sleep but worked at his desk all through the night, trying to get all the information about the mosquitoes organized  By morning, he showed all the signs of a severe attack of yellow fever  The camp doctors made the diagnosis, and L  agreed to go to the yellow fever ward    L  was carried by litter out of the two-room, white pine board house in which he had lived since he and Mabel first arrived in Cuba    (In the yellow fever ward, in a separate one-room building), Lena Warner (the immune nurse who had survived the yellow fever in 1878, when she was nine, and was found in her boarded-up house by a former slave who first thought she was dead, and carried her to safety) nursed J L , recording his vitals  (I put up a link to his case record and vital signs last week  The surgeon general required that this record be made for every yellow fever patient )    (On September 25,) Lena Warner braced L's arms with all of her weight, shouting for help  Still he bolted from the bed, darting around the small frame-wood room as wildly as a trapped insect beating against glass  Two soldiers ran into the ward, pinning L to his bed, tying restraints around his wrists and elbows    Warner sponged his body with iced whiskey and water  She recorded his temperature, which had held at 104 degrees for days, on the chart beside his bed    (Warner watched him sleep ) But the quiet did not last  L's body began to lurch, and black vomit rolled from his mouth; through the bar hanging above his hospital cot  He writhed in the bed, and his skin grew deep yellow  His 104 temperature slowly fell, leveling out 99 degrees, and JL died at 8:45 p m  at the age of thirty-four "
As is obvious, there are many problems with vaccines  But, that being said, most of them usually work for a period of time to prevent the targeted diseases  The basic science behind vaccines is correct  Why do you think that within a few years (not many) of the introduction of the vaccines for them, pertussis, measles, mumps, rubella, tetanus, diphtheria, Hib disease, and chickenpox (and others) almost entirely disappeared? In the case of the routine childhood diseases, this was a bad thing, but it is a true thing 
Vaccines usually don't cause any obvious reactions  While they usually prevent the diseases, and that's why people continue to get them  With the increasing vaccination schedule, more and more are severely and permanently damaged, and it is immoral to mandate any vaccine for anyone for this reason  But it would also be immoral to prohibit vaccines for those who want them enough to take the risk 
Your article said as though it had any probative value that 90% of those who get pertussis had been vaxxed  The old DPT vaccine was MUCH more effective at preventing pertussis, but it was so dangerous (again, not to most, but to many), that developed countries replaced it with the acellular version, DTaP  From the beginning about twenty years ago, it was clear that it was not very effective and that huge numbers of vaxxed people got pertussis anyway, including my daughter who got pertussis at eight month old after having gotten three DTaPs  The pertussis vaccine continues to be very dangerous, and I do not recommend that anyone get it  It used to be a killer disease, but evolved to become much milder, to the extent that the disease is very rarely dangerous (usually only to newborns under three months old), while the vaccine is very dangerous  And they're trying to see how they can go back to the old DPT  This does not show that vaccine science has collapsed, but rather that the vaccine they developed to replace the DPT turned out to be much less effective than they first thought, while continuing to be much more dangerous than they first thought 
Your article extrapolated from that that modern medical science in general has collapsed, but that, again, is going too far  A older woman in Mexico City who is like my mother to me had a pacemaker inserted about two months ago to aid her failing heart, and it has restored her to optimism and energy, when she was despondent, weak, and close to death  I took my daughter to the dentist yesterday, who said she has three wisdom teeth coming in and that she said that the lower right one was sore  So, although I am cautious about X-rays, I made an appointment for a panoramic X-ray in a month to assess the wisdom teeth, and, if it seems appropriate, I'll take her to an oral surgeon to have one or more extracted under IV sedation, in his office, if possible (the dentist thought that it would be)  And I am confident that there will be no serious problems, but this is thanks to technology and training in modern medicine that haven't been available for that long 
I think that everyone should inform himself on all medical procedures before agreeing to anything, but I also think that he should have access to any medical procedure which is reasonable (and opinions can differ as to that) 
One problem is that you have not said how you think people should protect themselves against tetanus, bacterial meningitis, and yellow fever in the relevant cases, for example  These are diseases which healthy, well-nourished people used to die from very readily 
If most people stopped vaxxing and the mortality from these diseases rose to something like pre-vaccine levels, do you think they should just accept dying from them?
I put that in a separate paragraph because it is the crucial issue 
balinaheuchter Air Traffic Control You Tube - Colin Campbell example of - How to "Fudge a Nudge" -"Deal" or "No Deal" "Not in a month of Sundays" "No exceptions/no compromise?" -make a trade off -do an exception- everyone get's a good deal /good outcome!
Hans, you are right that we are looking at one of the biggest crimes in all history  When I read the story of that poor girl who was so healthy and is now confined to a wheelchair after getting her third Gardasil shot I could not believe that Merck could produce such a toxic vaccine and give it out to girls like it was something they absolutely had to have only to be mislead and made into cripples  Merck should be prosecuted for the damage they have done to so many girls who got the Gardasil vaccine and were physically debilitated for life  There is a place for the people who perpetrated this crime on young girls and women and it is called hell  They have destroyed people's lives and gotten away with it  My heart goes out to those who have suffered this damage for no damn good reason except to help make huge profits for Merck!
Here is the reason that the germ theory is nonsense 
1) Everyday we are bombarded with billions of germs  Presumably at least some of them are of the kind that germ theorists believe are dangerous (otherwise we would have to conclude that none of them are dangerous)  So how do we survive?
2) Let's just say that we ignore 1 and imagine that, by way of magic, none of the billions of viruses we get bombarded with are pathogenic but all those that are are tucked away somewhere  Ok  But presumably they reside in sick people right? So where are there lots of sick people? Doctor offices and hospitals! So everybody must be dying the moment they enter these places right?
3) I love this one because I have never seen anybody else ever raise it  Under the germ theory there are no negative feedbacks  This makes a stable biological system by definition impossible  The immune system is *not* a negative feedback it is the opposite  It actually reinforces our math problem because the immune system will weaken as the number of pathogens increase 
There is no way of resolving this problem without a discontinuity  A Deus ex Machina as The Almighty Pill so beautifully put it  So the germ theory is quite literally, mathematically impossible 
There is as much chance of it being true as 2+2 = 5 
There are plenty of other massive problems with germ theory such as why did things like SARS and bird flu magically disappear? Why do we have the symptoms that we do? Is our body controlling the symptoms to help fight the germs and if so, why would suppressing the symptoms with antibiotics or Tamiflu be considered a good idea? If the virus is causing the symptoms then why would it cause these kinds of things?
Context 2: Publications of Kam W  Leong
Publications of Kam W  Leong :chronological alphabetical combined bibtex listing:
K W  Leong, Synthetic mast-cell granules as adjuvants to promote and polarize immunity in lymph nodes (2013) [PDF]
K W  Leong, Tuning Physical Properties of Nanocomplexes through Microfluidics-Assisted Confinement (2013) [PDF]
K W  Leong, Nucleic acid scavengers inhibit thrombosis without increasing bleeding (2013) [PDF]
K W  Leong, Nanotopography as modulator of human mesenchymal stem cell function (2013) [PDF]
K W  Leong, Efficacy of engineered FVIII-producing skeletal muscle enhanced by growth factor-releasing co-axial electrospun fibers (2013) [PDF]
Zhao, F  and Veldhuis, J  J  and Duan, Y  J  and Yang, Y  and Christoforou, N  and Ma, T  and Leong, K  W , Low Oxygen Tension and Synthetic Nanogratings Improve the Uniformity and Stemness of Human Mesenchymal Stem Cell Layer, Molecular Therapy, vol  18 no  5 (2010), pp  1010-1018 [abs]
Kadiyala, I  and Loo, Y  H  and Roy, K  and Rice, J  and Leong, K  W , Transport of chitosan-DNA nanoparticles in human intestinal M-cell model versus normal intestinal enterocytes, European Journal of Pharmaceutical Sciences, vol  39 no  1-3 (2010), pp  103-109 [abs]
Wang, Y  and Quek, C  H  and Leong, K W  and Fang, J , Synthesis and Cytotoxity of Luminescent InP Quantum Dots, MRS Symposium Proceeding, vol  1241E (2010)
Jiang, X  and Zheng, Y  and Chen, H  H  and Leong, K  W  and Wang, T  H  and Mao, H  Q , Dual-Sensitive Micellar Nanoparticles Regulate DNA Unpacking and Enhance Gene-Delivery Efficiency, Adv Mater (2010)
Ho, Y  P  and Leong, K  W , Quantum dot-based theranostics, Nanoscale, vol  2 no  1 (2010), pp  60-68 [PDF] [abs]
Phua, K  and Leong, K  W , Microscale oral delivery devices incorporating nanoparticles, Nanomedicine, vol  5 no  2 (2010), pp  161-163
Grigsby, C  L  and Leong, K  W , Balancing protection and release of DNA: tools to address a bottleneck of non-viral gene delivery, Journal of the Royal Society Interface, vol  7 (2010), pp  S67-S82 [abs]
Chalut, K  J  and Kulangara, K  and Giacomelli, M  G  and Wax, A  and Leong, K  W , Deformation of stem cell nuclei by nanotopographical cues, Soft Matter, vol  6 no  8 (2010), pp  1675-1681 [abs]
Chen, S  and Jones, J  A  and Xu, Y  and Low, H  Y  and Anderson, J  M  and Leong, K  W , Characterization of topographical effects on macrophage behavior in a foreign body response model, Biomaterials, vol  31 no  13 (2010), pp  3479-91 [PDF] [abs]
Yim, E  K  F  and Darling, E  M  and Kulangara, K  and Guilak, F  and Leong, K  W , Nanotopography-induced changes in focal adhesions, cytoskeletal organization, and mechanical properties of human mesenchymal stem cells, Biomaterials, vol  31 no  6 (2010), pp  1299-1306 [PDF] [abs]
Yow, S  Z  and Quek, C  H  and Yim, E  K  F  and Lim, C  T  and Leong, K  W , Collagen-based fibrous scaffold for spatial organization of encapsulated and seeded human mesenchymal stem cells, Biomaterials, vol  30 no  6 (2009), pp  1133-1142 [abs]
Kunder, C  A  and John, A  L  S  and Li, G  J  and Leong, K  W  and Berwin, B  and Staats, H  F  and Abraham, S  N , Mast cell-derived particles deliver peripheral signals to remote lymph nodes, Journal of Experimental Medicine, vol  206 no  11 (2009), pp  2455-2467 [abs]
Ho, Y P  and Chen, H H  and Leong, K W  and Wang, T H , Combining QD-FRET and microfluidics to monitor DNA nanocomplex self-assembly in real-time, J Vis Exp (2009), pp  1432
Kulangara, K  and Leong, K  W , Substrate topography shapes cell function, Soft Matter, vol  5 no  21 (2009), pp  4072-4076 [abs]
Chakraborty, S  and Liao, I  C  and Adler, A  and Leong, K  W , Electrohydrodynamics: A facile technique to fabricate drug delivery systems, Advanced Drug Delivery Reviews, vol  61 no  12 (2009), pp  1043-1054 [abs]
Oney, S  and Lam, R  T  S  and Bompiani, K  M  and Blake, C  M  and Quick, G  and Heidel, J  D  and Liu, J  Y  C  and Mack, B  C  and Davis, M  E  and Leong, K  W  and Sullenger, B  A , Development of universal antidotes to control aptamer activity, Nature Medicine, vol  15 no  10 (2009), pp  1224-1228 [PDF] [abs]
Chen, H  H  and Ho, Y  P  and Jiang, X  and Mao, H  Q  and Wang, T  H  and Leong, K  W , Simultaneous non-invasive analysis of DNA condensation and stability by two-step QD-FRET, Nano Today, vol  4 no  2 (2009), pp  125-134 [PDF] [abs]
Ho, Y  P  and Chen, H  H  and Leong, K  W  and Wang, T  H , The convergence of quantum-dot-mediated fluorescence resonance energy transfer and microfluidics for monitoring DNA polyplex self-assembly in real time, Nanotechnology, vol  20 no  9 (2009), pp  - [abs]
Liao, I  C  and Chen, S  L  and Liu, J  B  and Leong, K  W , Sustained viral gene delivery through core-shell fibers, Journal of Controlled Release, vol  139 no  1 (2009), pp  48-55 [abs]
Lou, Y  L  and Peng, Y  S  and Chen, B  H  and Wang, L  F  and Leong, K  W , Poly(ethylene imine)-g-chitosan using EX-810 as a spacer for nonviral gene delivery vectors, Journal of Biomedical Materials Research Part A, vol  88A no  4 (2009), pp  1058-1068 [abs]
Chew, S  Y  and Mi, R  and Hoke, A  and Leong, K  W , The effect of the alignment of electrospun fibrous scaffolds on Schwann cell maturation, Biomaterials, vol  29 no  6 (2008), pp  653-61 [abs]
Chen, H  H  and Ho, Y  P  and Jiang, X  and Mao, H  Q  and Wang, T  H  and Leong, K  W , Quantitative comparison of intracellular unpacking kinetics of polyplexes by a model constructed from quantum Dot-FRET, Molecular Therapy, vol  16 no  2 (2008), pp  324-332 [abs]
Chan, B  P  and Leong, K  W , Scaffolding in tissue engineering: general approaches and tissue-specific considerations, European Spine Journal, vol  17 (2008), pp  S467-S479 [abs]
Tsurushima, H  and Yuan, X  and Dillehay, L  E  and Leong, K  W , Radiation-inducible caspase-8 gene therapy for malignant brain tumors, International Journal of Radiation Oncology Biology Physics, vol  71 no  2 (2008), pp  517-525 [abs]
Bowman, K  and Sarkar, R  and Raut, S  and Leong, K  W , Gene transfer to hemophilia A mice via oral delivery of FVIII-chitosan nanoparticles, Journal of Controlled Release, vol  132 no  3 (2008), pp  252-259 [abs]
Choi, J  S  and Leong, K  W  and Yoo, H  S , In vivo wound healing of diabetic ulcers using electrospun nanofibers immobilized with human epidermal growth factor (EGF), Biomaterials, vol  29 no  5 (2008), pp  587-96 [abs]
Liao, I  C  and Liu, J  B  and Bursac, N  and Leong, K  W , Effect of Electromechanical Stimulation on the Maturation of Myotubes on Aligned Electrospun Fibers, Cellular and Molecular Bioengineering, vol  1 no  2-3 (2008), pp  133-145 [abs]
Prow, T  W  and Bhutto, I  and Kim, S  Y  and Grebe, R  and Merges, C  and McLeod, D  S  and Uno, K  and Mennon, M  and Rodriguez, L  and Leong, K  and Lutty, G  A , Ocular nanoparticle toxicity and transfection of the retina and retinal pigment epithelium, Nanomedicine-Nanotechnology Biology and Medicine, vol
Context 3: \section{Introduction}

Spectral line surveys have revealed that high-mass star-forming
regions are rich reservoirs of molecules from simple diatomic species
to complex and larger molecules (e g ,
\citealt{schilke1997b,hatchell1998b,comito2005,bisschop2007}) 
However, there have been rarely studies undertaken to investigate the
chemical evolution during massive star formation from the earliest
evolutionary stages, i e , from High-Mass Starless Cores (HMSCs) and
High-Mass Cores with embedded low- to intermediate-mass protostars
destined to become massive stars, via High-Mass Protostellar Objects
(HMPOs) to the final stars that are able to produce Ultracompact H{\sc
  ii} regions (UCH{\sc ii}s, see \citealt{beuther2006b} for a recent
description of the evolutionary sequence)  The first two evolutionary
stages are found within so-called Infrared Dark Clouds (IRDCs)   While
for low-mass stars the chemical evolution from early molecular
freeze-out to more evolved protostellar cores is well studied (e g ,
\citealt{bergin1997,dutrey1997,pavlyuchenkov2006,joergensen2007}),
it is far from clear whether similar evolutionary patterns are present
during massive star formation 

To better understand the chemical evolution of high-mass star-forming
regions we initiated a program to investigate the chemical properties
from IRDCs to UCH{\sc ii}s from an observational and theoretical
perspective  We start with single-dish line surveys toward a large
sample obtaining their basic characteristics, and then perform
detailed studies of selected sources using interferometers on smaller
scales  These observations are accompanied by theoretical modeling of
the chemical processes   Long-term goals are the chemical
characterization of the evolutionary sequence in massive star
formation, the development of chemical clocks, and the identification
of molecules as astrophysical tools to study the physical processes
during different evolutionary stages  Here, we present an initial
study of the reactive radical ethynyl (C$_2$H) combining single-dish
and interferometer observations with chemical modeling   Although
C$_2$H was previously observed in low-mass cores and Photon Dominated
Regions (e g , \citealt{millar1984,jansen1995}), so far it was not
systematically investigated in the framework of high-mass star
formation 

\section{Observations}
\label{obs}

The 21 massive star-forming regions were observed with the Atacama
Pathfinder Experiment (APEX) in the 875\,$\mu$m window in fall 2006 
We observed 1\,GHz from 338 to 339\,GHz and 1\,GHz in the image
sideband from 349 to 350\,GHz   The spectral resolution was
0 1\,km\,s$^{-1}$, but we smoothed the data to
$\sim$0 9\,km\,s$^{-1}$  The average system temperatures were around
200\,K, each source had on-source integration times between 5 and 16
min  The data were converted to main-beam temperatures with forward
and beam efficiencies of 0 97 and 0 73, respectively
\citep{belloche2006}  The average $1\sigma$ rms was 0 4\,K   The main
spectral features of interest are the C$_2$H lines around 349 4\,GHz
with upper level excitation energies $E_u/k$ of 42\,K (line blends of
C$_2$H$(4_{5,5}-3_{4,4})$ \& C$_2$H$(4_{5,4}-3_{4,3})$ at
349 338\,GHz, and C$_2$H$(4_{4,4}-3_{3,3})$ \&
C$_2$H$(4_{4,3}-3_{3,2})$ at 349 399\,GHz)  The beam size was $\sim
18''$ 

The original Submillimeter Array (SMA) C$_2$H data toward the
HMPO\,18089-1732 were first presented in \citet{beuther2005c}  There
we used the compact and extended configurations resulting in good
images for all spectral lines except of C$_2$H  For this project, we
re-worked on these data only using the compact configuration  Because
the C$_2$H emission is distributed on larger scales (see
\S\ref{results}), we were now able to derive a C$_2$H image  The
integration range was from 32 to 35\,km\,s$^{-1}$, and the achieved
$1\sigma$ rms of the C$_2$H image was 450\,mJy\,beam$^{-1}$   For more
details on these observations see \citet{beuther2005c} 

\section{Results}
\label{results}

The sources were selected to cover all evolutionary stages from IRDCs
via HMPOs to UCH{\sc ii}s  We derived our target list from the samples
of \citet{klein2005,fontani2005,hill2005,beltran2006}   Table
\ref{sample} lists the observed sources, their coordinates, distances,
luminosities and a first order classification into the evolutionary
sub-groups IRDCs, HMPOs and UCH{\sc ii}s based on the previously
available data  Although this classification is only based on a
limited set of data, here we are just interested in general
evolutionary trends  Hence, the division into the three main classes
is sufficient 

Figure \ref{spectra} presents sample spectra toward one source of each
evolutionary group  While we see several CH$_3$OH lines as well as
SO$_2$ and H$_2$CS toward some of the HMPOs and UCH{\sc ii}s but not
toward the IRDCs, the surprising result of this comparison is the
presence of the C$_2$H lines around 349 4\,GHz toward all source types
from young IRDCs via the HMPOs to evolved UCH{\sc ii}s   Table
\ref{sample} lists the peak brightness temperatures, the integrated
intensities and the FWHM line-widths of the C$_2$H line blend at
349 399\,GHz  The separation of the two lines of 1 375\,MHz already
corresponds to a line-width of 1 2\,km\,s$^{-1}$  We have three C$_2$H
non-detections (2 IRDCs and 1 HMPO), however, with no clear trend with
respect to the distances or the luminosities (the latter comparison is
only possible for the HMPOs)  While IRDCs are on average colder than
more evolved sources, and have lower brightness temperatures, the
non-detections are more probable due to the relatively low sensitivity
of the short observations (\S\ref{obs})  Hence, the data indicate
that the C$_2$H lines are detected independent of the evolutionary
stage of the sources in contrast to the situation with other
molecules   When comparing the line-widths between the different
sub-groups, one finds only a marginal difference between the IRDCs and
the HMPOs (the average $\Delta v$ of the two groups are 2 8 and
3 1\,km\,s$^{-1}$)   However, the UCH{\sc ii}s exhibit significantly
broader line-widths with an average value of 5 5\,km\,s$^{-1}$ 

Intrigued by this finding, we wanted to understand the C$_2$H spatial
structure during the different evolutionary stages   Therefore, we
went back to a dataset obtained with the Submillimeter Array toward
the hypercompact H{\sc ii} region IRAS\,18089-1732 with a much higher
spatial resolution of $\sim 1''$ \citep{beuther2005c}   Albeit this
hypercompact H{\sc ii} region belongs to the class of HMPOs, it is
already in a relatively evolved stage and has formed a hot core with a
rich molecular spectrum   \citet{beuther2005c} showed the spectral
detection of the C$_2$H lines toward this source, but they did not
present any spatially resolved images  To recover large-scale
structure, we restricted the data to those from the compact SMA
configuration (\S\ref{obs})  With this refinement, we were able to
produce a spatially resolved C$_2$H map of the line blend at
349 338\,GHz with an angular resolution of $2 9''\times 1 4''$
(corresponding to an average linear resolution of 7700\,AU at the
given distance of 3 6\,kpc)  Figure \ref{18089} presents the
integrated C$_2$H emission with a contour overlay of the 860\,$\mu$m
continuum source outlining the position of the massive protostar  In
contrast to almost all other molecular lines that peak along with the
dust continuum \citep{beuther2005c}, the C$_2$H emission surrounds the
continuum peak in a shell-like fashion 

\section{Discussion and Conclusions}

To understand the observations, we conducted a simple chemical
modeling of massive star-forming regions  A 1D cloud model with a mass
of 1200\,M$_\sun$, an outer radius of 0 36\,pc and a power-law density
profile ($\rho\propto r^p$ with $p=-1 5$) is the initially assumed
configuration  Three cases are studied: (1) a cold isothermal cloud
with $T=10$\,K, (2) $T=50$\,K, and (3) a warm model with a temperature
profile $T\propto r^q$ with $q=-0 4$ and a temperature at the outer
radius of 44\,K  The cloud is illuminated by the interstellar UV
radiation field (IRSF, \citealt{draine1978}) and by cosmic ray
particles (CRP)  The ISRF attenuation by single-sized $0 1\mu$m
silicate grains at a given radius is calculated in a plane-parallel
geometry following \citet{vandishoeck1988}  The CRP ionization rate is
assumed to be $1 3\times 10^{-17}$~s$^{-1}$ \citep{spitzer1968}  The
gas-grain chemical model by \citet{vasyunin2008} with the desorption
energies and surface reactions from \citet{garrod2006} is used 
Gas-phase reaction rates are taken from RATE\,06 \citep{woodall2007},
initial abundances, were adopted from the ``low metal'' set of
\citet{lee1998} 

Figure \ref{model} presents the C$_2$H abundances for the three models
at two different time steps: (a) 100\,yr, and (b) in a more evolved
stage after $5\times10^4$\,yr  The C$_2$H abundance is high toward the
core center right from the beginning of the evolution, similar to
previous models (e g , \citealt{millar1985,herbst1986,turner1999}) 
During the evolution, the C$_2$H abundance stays approximately
constant at the outer core edges, whereas it decreases by more than
three orders of magnitude in the center, except for the cold $T=10$~K
model   The C$_2$H abundance profiles for all three models show
similar behavior 

The chemical evolution of ethynyl is determined by relative removal
rates of carbon and oxygen atoms or ions into molecules like CO, OH,
H$_2$O  Light ionized hydrocarbons CH$^+_{\rm n}$ (n=2  5) are quickly
formed by radiative association of C$^+$ with H$_2$ and hydrogen
addition reactions: C$^+$ $\rightarrow$ CH$_2^+$ $\rightarrow$
CH$_3^+$ $\rightarrow$ CH$_5^+$   The protonated methane reacts with
electrons, CO, C, OH, and more complex species at later stage and
forms methane   The CH$_4$ molecules undergo reactive collisions with
C$^+$, producing C$_2$H$_2^+$ and C$_2$H$_3^+$  An alternative way to
produce C$_2$H$_2^+$ is the dissociative recombination of CH$_5^+$
into CH$_3$ followed by reactions with C$^+$   Finally, C$_2$H$_2^+$
and C$_2$H$_3^+$ dissociatively recombine into CH, C$_2$H, and
C$_2$H$_2$  The major removal for C$_2$H is either the direct
neutral-neutral reaction with O that forms CO, or the same reaction
but with heavier carbon chain ions that are formed from C$_2$H by
subsequent insertion of carbon  At later times, depletion and
gas-phase reactions with more complex species may enter into this
cycle   At the cloud edge the interstellar UV radiation
instantaneously dissociates CO despite its self-shielding,
re-enriching the gas with elemental carbon 

The transformation of C$_2$H into CO and other species proceeds
efficiently in dense regions, in particular in the ``warm'' model
where endothermic reactions result in rich molecular complexity of the
gas (see Fig ~\ref{model})   In contrast, in the ``cold'' 10\,K model
gas-grain interactions and surface reactions become important   As a
result, a large fraction of oxygen is locked in water ice that is hard
to desorb ($E_{\rm des} \sim 5500$~K), while half of the elemental
carbon goes to volatile methane ice ($E_{\rm des} \sim 1300$~K)  Upon
CRP heating of dust grains, this leads to much higher gas-phase
abundance of C$_2$H in the cloud core for the cold model compared to
the warm model  The effect is not that strong for less dense regions
at larger radii from the center 

Since the C$_2$H emission is anti-correlated with the dust continuum
emission in the case of IRAS\,18089-1732 (Fig \,\ref{18089}), we do
not have the H$_2$ column densities to quantitatively compare the
abundance profiles of IRAS\,18089-1732 with our model  However, data
and model allow a qualitative comparison of the spatial structures 
Estimating an exact evolutionary time for IRAS\,18089-1732 is hardly
possible, but based on the strong molecular line emission, its high
central gas temperatures and the observed outflow-disk system
\citep{beuther2004a,beuther2004b,beuther2005c}, an approximate age of
$5\times10^4$\,yr appears reasonable   Although dynamical and chemical
times are not necessarily exactly the same, in high-mass star
formation they should not differ to much: Following the models by
\citet{mckee2003} or \citet{krumholz2006b}, the luminosity rises
strongly right from the onset of collapse which can be considered as a
starting point for the chemical evolution  At the same time disks and
outflows evolve, which should hence have similar time-scales   The
diameter of the shell-like C$_2$H structure in IRAS\,18089-1732 is
$\sim 5''$ (Fig \,\ref{18089}), or $\sim$9000\,AU in radius at the
given distance of 3 6\,kpc   This value is well matched by the modeled
region with decreased C$_2$H abundance (Fig \,\ref{model})   Although
in principle optical depths and/or excitation effects could mimic the
C$_2$H morphology, we consider this as unlikely because the other
observed molecules with many different transitions all peak toward the
central submm continuum emission in IRAS\,18089-1732
\citep{beuther2005c}  Since C$_2$H is the only exception in that rich
dataset, chemical effects appear the more plausible explanation 

The fact that we see C$_2$H at the earliest and the later evolutionary
stages can be explained by the reactive nature of C$_2$H: it is
produced quickly early on and gets replenished at the core edges by
the UV photodissociation of CO  The inner ``chemical'' hole observed
toward IRAS\,18089-1732 can be explained by C$_2$H being consumed in
the chemical network forming CO and more complex molecules like larger
carbon-hydrogen complexes and/or depletion 

The data show that C$_2$H is not suited to investigate the central gas
cores in more evolved sources, however, our analysis indicates that
C$_2$H may be a suitable tracer of the earliest stages of (massive)
star formation, like N$_2$H$^+$ or NH$_3$ (e g ,
\citealt{bergin2002,tafalla2004,beuther2005a,pillai2006})  While a
spatial analysis of the line emission will give insights into the
kinematics of the gas and also the evolutionary stage from chemical
models, multiple C$_2$H lines will even allow a temperature
characterization  With its lowest $J=1-0$ transitions around 87\,GHz,
C$_2$H has easily accessible spectral lines in several bands between
the 3\,mm and 850\,$\mu$m   Furthermore, even the 349\,GHz lines
presented here have still relatively low upper level excitation
energies ($E_u/k\sim42$\,K), hence allowing to study cold cores even
at sub-millimeter wavelengths   This prediction can further be proved
via high spectral and spatial resolution observations of different
C$_2$H lines toward young IRDCs 

\acknowledgments{H B  acknowledges financial support
  by the Emmy-Noether-Programm of the Deutsche Forschungsgemeinschaft
  (DFG, grant BE2578)  }






ground_truth: Del Bigtree and his team at ICAN.

prompt_front: Now, answer the following question based on the text below, only give me the answer and do not output any other words.

Question: What are the titles of one of Kam W. Leong's publications in Journal of Controlled Release?

Read the following text and answer briefly.

Context 2:  4 no  4 (2008), pp  340-349 [abs]
Tan, S  C  W  and Pan, W  X  and Ma, G  and Cai, N  and Leong, K  W  and Liao, K , Viscoelastic behaviour of human mesenchymal stem cells, Bmc Cell Biology, vol  9 (2008), pp  - [abs]
Chalut, K  J  and Chen, S  and Finan, J  D  and Giacomelli, M  G  and Guilak, F  and Leong, K  W  and Wax, A , Label-free, high-throughput measurements of dynamic changes in cell nuclei using angle-resolved low coherence interferometry, Biophysical Journal, vol  94 no  12 (2008), pp  4948-4956 [abs]
Haider, M  and Cappello, J  and Ghandehari, H  and Leong, K  W , In vitro chondrogenesis of mesenchymal stem cells in recombinant silk-elastinlike hydrogels, Pharmaceutical Research, vol  25 no  3 (2008), pp  692-699 [abs]
N  Bursac and Y  H  Loo and K  Leong and L  Tung, Novel anisotropic engineered cardiac tissues: Studies of electrical propagation, Biochemical And Biophysical Research Communications, vol  361 no  4 (October, 2007), pp  847 -- 853, ISSN 0006-291X [abs]
Chen, Beiyi and Dang, Jiyoung and Tan, Tuan Lin and Fang, Ning and Chen, Wei Ning and Leong, Kam W  and Chan, Vincent, Dynamics of smooth muscle cell deadhesion from thermosensitive hydroxybutyl chitosan, Biomaterials, vol  28 no  8 (2007), pp  1503 - 1514 [027] [abs]
Chen, B  and Dang, J  and Tan, T  L  and Fang, N  and Chen, W  N  and Leong, K  W  and Chan, V , Dynamics of smooth muscle cell deadhesion from thermosensitive hydroxybutyl chitosan, Biomaterials, vol  28 no  8 (2007), pp  1503-14 [abs]
Park, D  J  and Choi, J  H  and Leong, K  W  and Kwon, J  W  and Eun, H  S , Tissue-engineered bone formation with gene transfer and mesenchymal stem cells in a minimally invasive technique, Laryngoscope, vol  117 no  7 (2007), pp  1267-71 [abs]
Tsurushima, H  and Yuan, X  and Dillehay, L  E  and Leong, K  W , Radioresponsive tumor necrosis factor-related apoptosisinducing ligand (TRAIL) gene therapy for malignant brain tumors, Cancer Gene Therapy, vol  14 no  8 (2007), pp  706-716 [abs]
Chai, C  and Leong, K  W , Biomaterials approach to expand and direct differentiation of stem cells, Molecular Therapy, vol  15 no  3 (2007), pp  467-480 [abs]
Zhang, Y  and Chai, C  and Jiang, X  S  and Teoh, S  H  and Leong, K  W , Fibronectin immobilized by covalent conjugation or physical adsorption shows different bioactivity on aminated-PET, Materials Science & Engineering C-Biomimetic and Supramolecular Systems, vol  27 no  2 (2007), pp  213-219 [abs]
Song, R  J  and Liu, S  Q  and Leong, K  W , Effects of MIP-1 alpha, MIP-3 alpha, and MIP-3 beta on the induction of HIV Gag-specific immune response with DNA vaccines, Molecular Therapy, vol  15 no  5 (2007), pp  1007-1015 [abs]
Yim, E  K  F  and Liao, I  C  and Leong, K  W , Tissue compatibility of interfacial polyelectrolyte complexation fibrous scaffold: Evaluation of blood compatibility and biocompatibility, Tissue Engineering, vol  13 no  2 (2007), pp  423-433 [abs]
Sharma, B  and Williams, C  G  and Kim, T  K  and Sun, D  N  and Malik, A  and Khan, M  and Leong, K  and Elisseeff, J  H , Designing zonal organization into tissue-engineered cartilage, Tissue Engineering, vol  13 no  2 (2007), pp  405-414 [abs]
Chua, K  N  and Tang, Y  N  and Quek, C  H  and Ramakrishna, S  and Leong, K  W  and Mao, H  Q , A dual-functional fibrous scaffold enhances P450 activity of cultured primary rat hepatocytes, Acta Biomaterialia, vol  3 no  5 (2007), pp  643-650 [abs]
Chua, K  N  and Chai, C  and Lee, P  C  and Ramakrishna, S  and Leong, K  W  and Mao, H  Q , Functional nanofiber scaffolds with different spacers modulate adhesion and expansion of cryopreserved umbilical cord blood hematopoietic stem/progenitor cells, Experimental Hematology, vol  35 no  5 (2007), pp  771-781 [abs]
Yim, E  K  F  and Pang, S  W  and Leong, K  W , Synthetic nanostructures inducing differentiation of human mesenchymal stem cells into neuronal lineage, Experimental Cell Research, vol  313 no  9 (2007), pp  1820-1829 [abs]
Chew, S  Y  and Mi, R  F  and Hoke, A  and Leong, K  W , Aligned protein-polymer composite fibers enhance nerve regeneration: A potential tissue-engineering platform, Advanced Functional Materials, vol  17 no  8 (2007), pp  1288-1296 [abs]
Tsurushima, H  and Yuan, X  and Dillehay, L  E  and Leong, K  W , Radio-responsive gene therapy for malignant glioma cells without the radiosensitive promoter: Caspase-3 gene therapy combined with radiation, Cancer Letters, vol  246 no  1-2 (2007), pp  318-323 [abs]
Dang, J M  and Leong, K  W , Myogenic induction of aligned mesenchymal stem cell sheets by culture on thermally responsive electrospun nanofibers, Advanced Materials, vol  19 no  19 (2007), pp  2775-2779
Dai, H  and Jiang, X  and Tan, G  C  and Chen, Y  and Torbenson, M  and Leong, K  W  and Mao, H  Q , Chitosan-DNA nanoparticles delivered by intrabiliary infusion enhance liver-targeted gene delivery, International Journal of Nanomedicine, vol  1 no  4 (2006), pp  507-522 [abs]
Le Visage, C  and Kim, S  W  and Tateno, K  and Sieber, A  N  and Kostuik, J  P  and Leong, K  W , Interaction of human mesenchymal stem cells with disc cells - Changes in extracellular matrix biosynthesis, Spine, vol  31 no  18 (2006), pp  2036-2042
Ong, S  Y  and Dai, H  and Leong, K  W , Inducing hepatic differentiation of human mesenchymal stem cells in pellet culture, Biomaterials, vol  27 no  22 (2006), pp  4087-4097
Bright, C  and Park, Y  S  and Sieber, A  N  and Kostuik, J  P  and Leong, K  W , In vivo evaluation of plasmid DNA encoding OP-1 protein for spine fusion, Spine, vol  31 no  19 (2006), pp  2163-2172
Yim, E  K  and Wan, A  C  and Le Visage, C  and Liao, I  C  and Leong, K  W , Proliferation and differentiation of human mesenchymal stem cell encapsulated in polyelectrolyte complexation fibrous scaffold, Biomaterials, vol  27 no  36 (2006), pp  6111-22 [abs]
Luong-Van, E  and Grondahl, L  and Chua, K  N  and Leong, K  W  and Nurcombe, V  and Cool, S  M , Controlled release of heparin from poly(epsilon-caprolactone) electrospun fibers, Biomaterials, vol  27 no  9 (2006), pp  2042-2050
Dang, J  M  and Leong, K  W , Natural polymers for gene delivery and tissue engineering, Advanced Drug Delivery Reviews, vol  58 no  4 (2006), pp  487-499
Li, J  and Li, X  and Ni, X  P  and Wang, X  and Li, H  Z  and Leong, K  W , Self-assembled supramolecular hydrogels formed by biodegradable PEO-PHB-PEO triblock copolymers and alpha-cyclodextrin for controlled drug delivery, Biomaterials, vol  27 no  22 (2006), pp  4132-4140
Yim, E  K  F  and Wen, J  and Leong, K  W , Enhanced extracellular matrix production and differentiation of human embryonic germ cell derivatives in biodegradable poly(epsilon-caprolactone-co-ethyl ethylene phosphate) scaffold, Acta Biomaterialia, vol  2 no  4 (2006), pp  365-376
Chew, S  Y  and Hufnagel, T  C  and Lim, C  T  and Leong, K  W , Mechanical properties of single electrospun drug-encapsulated nanofibres, Nanotechnology, vol  17 no  15 (2006), pp  3880-3891
Zhang, Y  and Chai, C  and Jiang, X  S  and Teoh, S  H  and Leong, K  W , Co-culture of umbilical cord blood CD34(+) cells with human mesenchymal stem cells, Tissue Engineering, vol  12 no  8



ground_truth: Sustained viral gene delivery through core-shell fibers and Gene transfer to hemophilia A mice via oral delivery of FVIII-chitosan nanoparticles.

prompt_front: Now, answer the following question based on the text below, only give me the answer and do not output any other words.

Question: What molecule was the focus of the study?

Read the following text and answer briefly.

Context 4:  In order for the object to remain stable we need to apply a normal force: where µ is the friction coefficient between the object and the wall 
In the case of a dexterous hand manipulating an object, we want the normal forces applied by all fingers to be greater than the tangential force divided by the friction coefficient of the materials of the object and the fingertip  Since it is hard to accurately compute the friction coefficient between all possible object materials previous works have used multi-modal tactile sensors like the BioTac sensor, which provides information about the pressure, skin deformation, and temperature, to predict slip and based on that signal to increase the applied normal force 
In our work we use the FTS3 sensors which is a low-cost sensor that measures the 3D force applied in each fingertip  In addition, previous works gathered labeled datasets in order to train their slip prediction models which is time-consuming and limits the possible orientations of the hand, because gathering labeled data for all possible orientations is impractical 
To overcome this we experimentally selected the parameters that determine the value of the applied normal force such that we avoid slip for all objects in our dataset, from the lightest to the heaviest  In order to guarantee contact between the fingertip and the object, in the beginning of the grasping phase, we use an offset f of f set n as the minimum normal force applied by each finger 
In they also suggest that humans use an additional safety margin which is proportional to the tangential force, f margin n ∝ f t   So the final desired normal contact force becomes: where G is the gain that includes the friction coefficient and the additional safety margin  To alleviate the effects of noise in the sensors, the running average of the measured normal force f n and tangential force f t is used, as a low pass filter 
So for each force measurement we have the following relation: where α ∈ (0, 1) is a parameter that determines how much new measurements affect the value, and is experimentally selected  Given the measured normal force f n from the fingertip sensors we can compute the error f err n = f des n − f n   We use this error signal to control the grasp size variable g size , that we use as a conditional variable in our posture mapping function 
The grasp size represents the distance between the thumb and the index finger in a grasp posture  So a smaller grasp size will result in a tighter grasp and greater normal force applied to the surface of the object  We use a linear controller for the grasp size variable that is implemented as follows: where K is a parameter that controls the rate of decrease of the grasp size, and is experimentally selected 
So when the error between the desired normal force and the actual normal force is large the grasp size decreases so tighter grasp postures are generated in order to apply more normal force  In practice, in order to avoid oscillations in the grasp size we use the desired normal force as a high threshold that we want the measured normal force to be below:
If the normal force is below that threshold the grasp size does not change even if there are small oscillations in the measured tangential and normal forces  Also, in order to avoid the hand applying too much force that damages the hardware or the object we use a low threshold, that is: where w threshold is the width of the threshold in mN  
If the measured normal force is below the grasp size increases in order to apply less force  So the final grasp size variable for grasping is calculated as follows: where This is similar to the deadband control method , where instead of having a fixed reference point, an operating range is set  If the response is in this range, the controller does not exert any correction 
In our case, the operating range changes according to the force signals from the robot's fingertips  The grasp posture mapping function is based on the conditional postural synergies model presented in   It uses a conditional Variational Auto-Encoder model to generate grasps postures conditioned on additional variables such as the grasp size 
In this work we augment this model to also generate grasp postures conditioned on the grasp type  The model is trained on a set of labeled grasp samples acquired by teleoperating a robotic hand using a data-glove  Using this model we are able to abstract away the low-level control of each joint of each finger and generate grasps based on more general characteristics such as the type and the size of the grasp 
In this way we can control all the fingers jointly by a single value, the grasp size, thus greatly reducing the control parameters  In addition we are able to use the same control algorithm for different precision grasp types, by changing the grasp type conditional variable  Finally, we can modify our controller to release objects instead of grasping them 
Given the pose of the hand in the world coordinate frame, which we can acquire from the robotic arm that is attached to, we can use the forward kinematics of the hand to compute the poses of each fingertip  Then using the force readings of each fingertip we can calculate the global direction of the net tangential force 
If the angle between the direction of the net tangential force and the direction of gravity is less than 90 degrees, i e  the net tangential force's direction is towards the ground, we assume that the tangential force is due to gravity pulling the object, so the force controller tries to grasp it  If the angle is more than 90 degrees, i e  the net tangential force's direction is upward, it means that something is pushing (or pulling) the object upward, in which case we assume that the object is touching on a support surface or someone is pulling the object so the controller increases the grasp size given to the posture mapping function proportionally to the normal force measured thus slowly releasing the object 
Opening the grasp is done by controlling the grasp size variable as follows: That way we can place objects on surfaces but also perform robot to human handovers, where the robot holds the object and the human grasps the object and slightly pushes or pulls it up, signaling to the robot that there is a support surface 
The robot then slowly releases the object by opening its grasp  We showcase these scenarios in the experiments' section  Based on these observations, we present our force controller in Figure   The hand starts in an open pre-grasp position, a latent point is sampled from the prior distribution of the posture mapping function, and given the desired grasp type and the grasp size a grasp posture, i e  the joint angles of the fingers, is sampled 
The initial grasp size is set to the maximum value, and when the force controller comes into effect and depending on the state of the system and the forces on the fingertips grasp size changes by some value C, according to equations 1,2, until the desired normal force is achieved  To choose between grasping or releasing an object we use a finite state machine formulation 
When the hand reaches the desired grasp pose, which we assume is provided, the GRASP state is activated, in which the controller tries to grasp the object  When the controller detects that the tangential force applied to the object is coming from a support surface the state changes to the RELEASE state, in which the controller releases the object by opening the grasp 
You can see the full algorithm in Python-like pseudocode in Figure   To summarize, the advantages of our controller compared with previous approaches are threefold: 1) instead of controlling each joint of each finger of the hand we use only two variables, the grasp size and the grasp type, which allows us to perform multiple grasp types by changing only one variable while the grasp size variable is common among all grasp types, that greatly reduces the complexity of the control process compared to independently controlling a 21 DoF hand to perform different grasp types, 2) we do not rely on slip prediction for controlling the desired normal force, which involves gathering labeled data and works only for the hand poses in the training dataset, and 3) we can use our controller to also release objects instead of only grasping them 

Experimental Set-up 

For our experiments we used the Seed Robotics RH8D Hand , which is a robotic hand with 7 DoFs  The hand is equipped with the FTS-3 force sensors in each fingertip, which are high resolution tactile sensors that provide the 3D force applied in each fingertip  The sensor provides data at a rate of 50Hz  For the experiments the hand was mounted on a Kinova Gen3 7DoF robot 
To train the posture mapping function we used the CyberGlove to teleoperate the hand and collect 468 grasps belonging to three precision grasp  types: tripod, pinch, lateral tripod  The architecture of the cVAE model was the same as in , with the addition of the grasp type as a conditional variable, which was one-hot encoded 
We used 10 household objects shown in Figure   With the heaviest object weighing 380g and the lightest 1g  During the experiments the trajectories of the arm were prerecorded, while the hand was controlled online by our control algorithm 

Parameter tuning 

To select the values of the parameters in our controllers we conducted preliminary experiments where we tested lifting and releasing several objects, with different physical properties  To select the value of the normal offset force f of f set n , we used an empty plastic cup as our test object, and we choose a value such that the fingers do not deform the cup 
The final value of the parameter was set to -50 mN  To select the values of the gain G and the rate of decrease K, of the grasp size, we experimented with the heaviest object in our dataset, which is the mustard bottle and weighs 380g  The gain G was set to 2 0 such that the desired normal force would be enough to hold the object 
The rate of change of the grasp size was set to 100 0, based on the operating frequency of the force sensor and the range of values of the tangential force  For the tangential force averaging process we used a parameter value of α t = 0 7, because we want the controller to be sensitive to fast changes in its value, that can arise for example during lifting an object 
For the normal force averaging process we used a parameter value of α n = 0 5, as we do not want it to be affected by noise that could make the controller overconfident 

Experiments 

To explore the capabilities of our controller, we demonstrate five experiments of increasing complexity: 1) we picked and placed a bottle using a tripod grasp, 2) we picked, rotated and placed a chips can on a box using a tripod grasp, 3) we picked, rotated and handed over the chips can to a person using a tripod grasp, 4) we picked, rotated and handed over a brown foam brick to a person using a pinch grasp, 5) a person handed over a plastic cup to the robot, filled it with coins to increase its weight, and the robot then handed it back to the person using a tripod grasp 
You can see the execution of the first experiment in  In the middle row, for our third experiment, the robot picks up the chips can, rotates it 90 degrees, and hands it over to a person  In the bottom row, for our forth experiment, the robot picks up a foam brick, rotates it 180 degrees, and hands it over to a person, using a pinch grasp 
Fig    In our fifth experiment, a person hands over an empty plastic cup to the robot, throws coins in it to increase its weight while the robot adjusts its grip to stabilize the object, and then hand overs the cup back to the person  force is below the offset f of f set n , 2) (green part) the robot lifts the object, as it tries to lift the tangential force increases, increasing the threshold, so the grasp size decreases to apply more normal force, 3) (orange part) the robot transports the object, you can see, in point A in the Figure, a perturbation in the tangential force when the robot begins to move, the controller responds by decreasing the grasp thus stabilizing the object, and 4) (blue part) the robot enters the releasing phase, where it lowers the arm until it detects that the tangential force is due to a support surface, then it stops lowering the arm and increases the grasp size slowly releasing the object 
In point B in the Figure, you can see that there is noise in the tangential force, due to the arm moving to place the object on the table, that is also reflected in the desired normal force  Because we use the desired normal force as a threshold and not as a reference signal this noise is not manifested in the control of the grasp size 
You can see the execution of the second experiment in the upper part of Figure   This experiment demonstrates the ability of the controller to handle arbitrary hand poses  The experiment is divided in four parts: 1) the robot enters the GRASP phase and the force controller generates grasps to achieve a normal contact force below the f of f set n threshold, 2) the robot lifts the object and adjusts the grasp size to avoid the object falling, 3) the hand rotates to place the chips can on the horizontal position, and 4) the robot enters the RELEASE phase, and the arm lowers until the object touches the box, when the hand detects the supporting surface, it starts to slowly release the object 
You can see the execution of the third experiment in the middle part of Figure   This experiment demonstrates the ability of the controller to perform robot to human handovers  The experiment is divided in four parts: 1) the robot enters the GRASP phase and the force controller generates grasps to achieve a normal contact force below the f of f set n threshold, 2) the robot lifts the object and adjusts the grasp size to avoid the object falling, 3) the hand rotates to place the chips can on the vertical position, and 4) the robot enters the RELEASE phase, the arm stays still, the human grasps the object from the bottom and slightly pushes it up, the hand then detects that there is a supporting surface and starts to slowly release the object 
You can see the execution of the fourth experiment in the bottom part of Figure   This experiment is similar to previous one, but the grasp type that the robot uses is a pinch grasp, that involves only the thumb and the index finger  To perform this we only had to alter the grasp type conditional variable that was given to the posture mapping function 
You can see the execution of the fifth experiment in the bottom part of Figure   In the first part (blue) of the experiment the robot closes its grasp, by reducing the grasp size, until the normal force is below the force offset  In the next three parts (pink, green, red) the person throws coins in the cup to increase its weight 
You can see in the signal plots that each time coins are added the tangential force decreases so the normal force threshold decreases too  The grasp sizes then decreases as well in order to apply more normal force  This experiment demonstrates the ability of the controller to handle perturbations in the weight of the object during grasping 

CONCLUSION

In summary, we presented a controller that uses force feedback integrated with conditional synergies to control a dexterous robotic hand to grasp and release objects  We demonstrated that our controller can lift objects of different weights and materials while avoiding slip, react online when the weight of the object changes, place them down on surfaces, and hand them over to humans 
In addition, the control architecture is modular, so the synergy grasp mapping component can be easily changed in order to control several precision grasp types  However, our experiments also revealed various limitations of our controller  For example our method fails to stabilize the object when rotational slip occurs 
In addition hardware limitations such as, slow update rates and noise in the force measurements can create problems that result in the object falling  In future work we plan to incorporate additional sensing modalities, such as vision to alleviate some of these issues 



ground_truth: The focus of the study was on the reactive radical ethynyl (C$_2$H).