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doi: 10.1128/AEM.68.4.1616-1623.2002

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ABSTRACT

Acetic acid (167 mM) and lactic acid (548 mM) completely inhibited growth of Saccharomyces cerevisiae both in minimal medium and in media which contained supplements, such as yeast extract, corn steep powder, or a mixture of amino acids. However, the yeast grew when the pH of the medium containing acetic acid or lactic acid was adjusted to 4.5, even though the medium still contained the undissociated form of either acid at a concentration of 102 mM. The results indicated that the buffer pair formed when the pH was adjusted to 4.5 stabilized the pH of the medium by sequestering protons and by lessening the negative impact of the pH drop on yeast growth, and it also decreased the difference between the extracellular and intracellular pH values (ΔpH), the driving force for the intracellular accumulation of acid. Increasing the undissociated acetic acid concentration at pH 4.5 to 163 mM by raising the concentration of the total acid to 267 mM did not increase inhibition. It is suggested that this may be the direct result of decreased acidification of the cytosol because of the intracellular buffering by the buffer pair formed from the acid already accumulated. At a concentration of 102 mM undissociated acetic acid, the yeast grew to higher cell density at pH 3.0 than at pH 4.5, suggesting that it is the total concentration of acetic acid (104 mM at pH 3.0 and 167 mM at pH 4.5) that determines the extent of growth inhibition, not the concentration of undissociated acid alone.

The yeast Saccharomyces cerevisiae under aerobic conditions can use short-chain organic acids, such as acetic acid and lactic acid, as carbon sources. The process involves induction of certain anabolic pathways, enzymes, and specific transport mechanisms ( 2 , 4 , 5 , Destroyed Knee Mom Fit Jeans Bright white Noisy May Eastbay Cheap Price Clearance For Cheap Clearance Cheapest bE3twE
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). If glucose is available in the growth medium, these pathways and permeases are repressed. Glucose-repressed yeast cells are unable to take up the anions of these acids ( 6 ), but the undissociated acids diffuse freely into the cells. Once inside, these acids dissociate because of the higher intracellular pH and cause acidification of the cytoplasm. Generally, eucaryotic cells maintain their intracellular pH within a narrow range despite wide variations that may occur in the extracellular pH ( 7 ). Under fermentation conditions, the intracellular pH of S. cerevisiae is usually maintained between 5.5 and 5.75 when the external pH is 3.0 ( 9 ) or between 5.9 and 6.75 when the external pH is varied between 6.0 and 10.0 ( 8 ). To maintain the intracellular pH within a physiological range optimum for metabolism, the cells pump out protons at the expense of metabolic energy (ATP). Increased diversion of energy (ATP) to pump out protons results in decreased molar growth yield with respect to glucose ( Y glucose ) ( 19 , 24 ). It has also been reported that the Y ATP (grams of biomass produced per mole of ATP generated) decreased from 14 to 4 when the concentration of acetic acid was increased from 0 to 170 mM ( 19 ). As the gap between the extracellular pH and the intracellular pH widens, greater stress is placed on the cells and more energy is expended to maintain the intracellular pH within the range that permits growth and survival of the yeast.

This is Live Roads' default view. Due to my unfamiliarity with Android, obtaining screenshots while I was driving was out of the question, so these were all done at my desk.
As you zoom in, more details resolve. The app did place me accurately in the right spot in the house.
The picture-in-picture function looks flashy, but I don't know how useful it is on the move.
The route guidance is indeed lane-specific.

But the spatial resolution was indeed better than it should be on a consumer phone, and Live Roads was able to locate me down to a specific lane on a multi-lane road. Various navigation apps give you lane-specific instructions—for instance, telling you to stay in the middle two lanes if you're approaching a complicated intersection.Where Live Roads differs is that it can also tell which lane you're actually in. Whether this is enough of a feature to build a business model around is an open question; I'm quite happy using Google Maps on iOS, with occasional forays into Waze (running in the background to warn of speed traps) and Apple Maps (if I'm driving something with CarPlay and the infotainment's built-in navigation sucks).

But it left me wondering: how does it work?

Paul Konieczny, CEO of Live Roads, gave me an explanation—up to a point. "Primarilyit is based around sensor fusion and certain probabilistic models—we call it the Black Box," he said. "The current release of the app that isavailable in the Play Store has an earlier revisionof our Black Box. This initial version is missing some of the functionality of the full-fledged system and thus has a spatial resolution of ~2.5m. This compares favorablyto standard GPS that has a resolution of 4.0 m+."

By summer, Konieczny hopes that the system will be fully operational and that accuracy will be down to under 1.5m. Assuming a large enough user base, that should let it offer lane-specific traffic data, "as well as introducing an entire ecosystem of 3D objects that users will be able tointeractwith," he told me.

There are actually a few different ways to make your GPS system more accurate. The simplest is called Real Time Kinematics (RTK). This system involves comparing the signal from the constellation (or constellations, if you pull in signals from GLONASS, Galileo, and BeiDou as well as GPS) of orbiting satellites to a second signal from a base station at a known position. For things like field surveys, this works very well, but RTK base stations have a limited range—under 20 miles—so you need a network of them if you want widespread coverage.

Precise Point Positioning (PPP) is another alternative; it does away with the base station and instead sends the end user's GPS a correction signal calculated by knowing any corrections made to either the clocks or orbits of the satellites . Increasingly, that correction signal is delivered via the cloud.

"RTK is expensive; between $5,000 and$10,000 per station, and it doesn't scale," explained Fergus Noble, CTO at Swift Navigation. "PPP has global coverage but lower accuracy, and up to 30 min of waiting during initialization." Noble's company has developed a hybrid approach for getting centimeter-accurate localization at relatively low cost, called Skylark. "We model error profiles as GPS signals travel through the different regions of the atmosphere and the environment to correct the clock error," Noble said.

/ / Generating Power Like Plants

When plants absorb sunlight, theyconvert carbon dioxideinto energy-rich organic compounds. What if humans could do the same thing? What if we could pull CO2 out of the air and use it to build organic molecules? This revolutionary idea is still just that — an idea. But organic chemists at UNC are laying the groundwork for turning it into reality.

A freshwater aquarium looks a bit like an underwater garden — bright, green grasses grow next to burgundy leaves resembling arugula. Small, silver fish dart between the foliage, as streams of bubbles flow up through the water column.

Dave Nicewicz stares at this array of life contained within the rectangular glass tank on his desk.

“Look at the little oxygen bubble at the edge of the leaf — that’s a good one” he says, pointing to theplant with a reddish hue. A small heat lamp mimics the sun, radiating light into the tank, while six different species of plants release oxygen.

“I love this thing because you can actually see photosynthesis happening — you can’t see that outside.”

As a research scientist, Nicewicz finds inspiration in photosynthesis. And while he loves plants (both his office and home are full of them) he is not a biologist — he’s an organic chemist.

“I’m not equating what we do to photosynthesis, but we’re inspired by that process,” he says.

Nicewicz’s ultimate goal is to use the most abundant source of energy on the planet — sunlight — to power chemical reactions. “To harvest sunlight in a way that either directly or indirectly can be used in chemical reactions by translating photons into electrons,” he says. “That’s the future.”

Humans have not yet engineered a way to create the complex biological machinery of plant life in a lab, according to Nicewicz, but the inspiration for the starting point is there — in the form of photo-redox catalysis.

“It’s just a fancy way of saying we use light to make cool molecules,” says Nate Romero, a former PhD student of the Nicewicz lab.

To explain this chemical process, it’s helpful to break down each word. We’re talking about creating reactions, and all reactions require an energy input – like heat or light. Photo refers to light, and redox refers to the transfer of electrons. Catalysis simply means using a catalyst, which decreases the amount of energy needed for a reaction to occur.

“We can use a single catalyst to make hundreds or thousands or millions of molecules that we’re interested in studying,” says Cole Cruz, a graduate research assistant in the lab.

By trying out different catalysts, this group of organic chemists can trim off one part of a molecule, or combine molecules that wouldn’t typically combine. These “cool molecules” play a major role in the development of vital plastics and medicines around the world — making the production process more economical and more environmentally friendly.

Clang supports the  format  attribute, which indicates that the function accepts a  printf  or  scanf  -like format string and corresponding arguments or a  va_list  that contains these arguments.

Clang implements two kinds of checks with this attribute.

Clang checks that the function with the  format  attribute is called with a format string that uses format specifiers that are allowed, and that arguments match the format string. This is the  -Wformat  warning, it is on by default.

Clang checks that the format string argument is a literal string. This is the  -Wformat-nonliteral  warning, it is off by default.

Clang implements this mostly the same way as GCC, but there is a difference for functions that accept a  va_list  argument (for example,  vprintf  ). GCC does not emit  -Wformat-nonliteral  warning for calls to such functions. Clang does not warn if the format string comes from a function parameter, where the function is annotated with a compatible attribute, otherwise it warns. For example:

In this case we warn because  s  contains a format string for a  scanf  -like function, but it is passed to a  printf  -like function.

If the attribute is removed, clang still warns, because the format string is not a string literal.

Another example:

In this case Clang does not warn because the format string  s  and the corresponding arguments are annotated. If the arguments are incorrect, the caller of  foo  will receive a warning.

ifunc (gnu::ifunc) ¶

is used to mark that the address of a declaration should be resolved at runtime by calling a resolver function.

The symbol name of the resolver function is given in quotes. A function with this name (after mangling) must be defined in the current translation unit; it may be . The resolver function should take no arguments and return a pointer.

The attribute may only be used on a function declaration. A function declaration with an attribute is considered to be a definition of the declared entity. The entity must not have weak linkage; for example, in C++, it cannot be applied to a declaration if a definition at that location would be considered inline.

Not all targets support this attribute. ELF targets support this attribute when using binutils v2.20.1 or higher and glibc v2.11.1 or higher. Non-ELF targets currently do not support this attribute.

The attribute changes the linkage type of the declaration to internal. This is similar to C-style , but can be used on classes and class methods. When applied to a class definition, this attribute affects all methods and static data members of that class. This can be used to contain the ABI of a C++ library by excluding unwanted class methods from the export tables.

interrupt (ARM) ¶

Clang supports the GNU style attribute on ARM targets. This attribute may be attached to a function definition and instructs the backend to generate appropriate function entry/exit code so that it can be used directly as an interrupt service routine.

The parameter passed to the interrupt attribute is optional, but if provided it must be a string literal with one of the following values: “IRQ”, “FIQ”, “SWI”, “ABORT”, “UNDEF”.

The semantics are as follows:

If the function is AAPCS, Clang instructs the backend to realign the stack to 8 bytes on entry. This is a general requirement of the AAPCS at public interfaces, but may not hold when an exception is taken. Doing this allows other AAPCS functions to be called.

What is Thrive?

Thrive provides families with the resources, tools, and support to raise healthy, successful children.

We accomplish this though our evidence-based, signature programs that are available to everyone in Montana’s Gallatin Valley communities.