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Fun fact: Gender and Sex are both human made constructs designed to describe natural phenomenon but are not actually based in any biological reality. Much like the concept of “species”, it’s a model, and no model is an actuality - then it would not be a model, it would be a fact.
In truth sexual characteristics are diverse and varied and do not always match up with sex chromosomes; also, a sexual “binary” of sorts is not constant amongst all living things, and most organisms have other systems of reproduction.
Furthermore, gender is the suite of societally-defined social roles and behavioral characteristics that is typically assigned based on the externally perceived sex of a child; and does not actually have anything to do with biology - even less so than sex. Even though it is assigned based on this externally perceived sex, a person’s gender does not have to remain with the one assigned; much as we don’t determine people’s careers based on who their parents were anymore, your birth has no limitation on who you are and what gender identity you construct for yourself. Since it is a societally defined construct, people can and do construct more than the two traditional ones, and all are valid.
Just because you cannot handle your societally constructed worldview surrounding sex, gender, and genetics being dismantled by sociology & biology itself doesn’t mean, additionally, that you have the right to make other people feel unsafe and uncomfortable - in short, that you have the right to remove people from moral consideration - simply because you don’t like having your world view being dismantled. Believe it or not, the complexities of human behavior & the diversity of sex and reproduction in life cannot all be covered in a simple high school biology class.
So next time you want to say “didn’t you pass biology” remember: a biology PhD student, who graduated from the University of Notre Dame with an actual degree in Biological Sciences, has reminded you that you’re wrong.
There are more than two genders.
The end.
Sex is biological tough… It’s not a social construct… It’s not time, racism etc. It’s a physics attribute.
Why are you trying to argue with someone who said species is a constructed model and not a fact? You’re not going to change someone’s mind when they’re that far down the rabbit hole
Me: Spends 6 years intensely studying biological science and evolution at two major universities with widespread academic acclaim, earning honors and high GPAs and am currently working on a PhD in the subject of biodiversity and evolution
You: Somehow thinks they know more because you took a couple of classes
Lol
…Buddy. Buddy. Dude. I really don’t think you want to open this can of worms.
I mean, I know that in school they teach you a very clean, concise, definitive way of doing things and you’ve probably learnt something like the definition of a species is a population of organisms that are able to reproduce and produce viable offspring, or something. But I mean literally anyone who has done even undergrad biology can tell you that that statement is incredibly reductive and incredibly controversial in the scientific community [1][2]. In fact, you probably don’t even need a background in biology to spot the obvious flaw in the logic there, which is the fact that organisms classified as different species do reproduce and produce viable offspring. Quite a lot, actually. Lions and tigers (Panthera leo and P. tigris), coyotes and grey wolves (Canis latrans and C. lupus)… In fact, there’s even a word for new species arising through hybridisation between existing species - hybrid speciation [3]. The great skua (Stercorarius skua) is believed to be an example of this in animals [4], and another interesting one that may be pretty much hybrid speciation in action (though not nearly anything that can be called a new distinct species yet) is the so-called “Eastern coyote”, a population of wild coyotes in the eastern US that are mixed with grey wolf and domestic dog, and can contain as much as 40% non-coyote DNA [5].
And, in fact, the ability of two organisms to reproduce and produce viable offspring actually has very little with how we choose to classify them, because evolutionary and genetic relationships are rarely that simple. For example, some species that are the same genus - e.g. horses (Equus ferus) and donkeys (Equus africanus) can interbreed, but their offspring are usually sterile [6], while other species that are different genera to each other can interbreed to produce intergeneric hybrids, some of which are even fertile (for example crosses between false killer whales (Pseudorca crassidens) and bottlenose dolphins (Tursiops truncatus) [7], or between king snakes (genus Lampropeltis) and corn snakes (genus Pantherophis) [8]). Most “exotic” domestic cat breeds (e.g. Bengals and Savannahs) also fall into this category - for some reason felids are genetically Weird in that a wide variety of species in the family Felidae seem able to interbreed with each other, no matter how different or distantly related they are. I mean…
Look at this shit. Now bear in mind that the domestic cat (Felis catus) is known to be able to interbreed with species in the caracal, ocelot, lynx and leopard cat lineages in addition to those in its own lineage, and if that wasn’t bad enough puma/leopard hybrids are a thing that exist. Those species aren’t even in the same subfamily, let alone genus or genetic lineage - the leopard is classed as subfamily Pantherinae, genus Panthera (P. pardus) while the puma is classed as subfamily Felinae, genus Puma (P. concolor).
[9]
Although these aren’t even the most distantly related species that are able to interbreed - domestic chickens (Gallus gallus domesticus) are known to hybridise with guineafowl [10], and the offspring of these crosses are interfamilial hybrids since chickens and guineafowl are classified in different families (chickens belong to family Phasianidae, guineafowl to family Numididae).
And of course another place where the “able to interbreed and produce viable offspring” definition falls apart is with organisms that reproduce asexually or without the need for a sexual partner, which is even more complicated when you consider that some species (for example, some species in the paraphyletic whiptail lizard genus Cnemidophorus) are dioecious, meaning they have separate sexes, and reproduce by producing gametes via meiosis, but have actually lost the ability to reproduce sexually somewhere along the evolutionary line - these species reproduce predominantly or entirely by parthenogenesis (essentially a form of self-cloning) and the Y chromosome has been entirely lost in the population. This also ties into hybrid speciation because it is believed that these parthenogenic species arose from hybridisation between two or three sexual species [11][12], leading to polyploid individuals (i.e. those with ‘extra’ sets of chromosomes) - for example, the all-female parthenogenic species Cnemidophorus neomexicanus is actually a hybrid of two sexual species, Cnemidophorus inornatus and C. marmoratus (or C. tigris, according to Wikipedia), and thus new individuals of this species can be formed either by parthenogenesis in a single C. neomexicanus parent, or sexual reproduction between a male and female C. inornatus and C. marmoratus/C. tigris [13]. Some female parthenogenic species are also able to interbreed sexually with males from sexual species, resulting in hybrids which may or may not also be parthenogenic [14].
So you can ask, well what the fuck is a genus, or a species for that matter, if it doesn’t necessarily indicate whether two animals are genetically similar enough to interbreed or not? And, more to the point, is there a strict set of quantitative criteria that defines whether two populations of organisms are classified as the same or different species? And I mentioned speciation, which brings up the question, when exactly in the process of evolution does one species actually become another?
The thing is, there aren’t actually definitive answers to these questions - if you ask a bunch of biologists what a species is, it’s likely you’ll get different answers. “Species” also has a number of definitions [15][16], mainly depending on the type of organism being studied and the angle it is being studied from. For bacteria, for instance - where “similar enough to reproduce” really isn’t applicable - I think the general consensus is that individuals are grouped together if their genetic similarity to one another is 97-98% or higher, while a similar definition of “organisms that are highly genetically similar to one another” tends to be used for asexually reproducing organisms such as some plants, and parthenogenic animals like whiptail lizards or Bdelloid rotifers (which does of course raise the question of what exactly “highly similar” means - any decided-upon cutoff point will necessarily be somewhat arbitrary). Such groupings of organisms may be referred to as phylotypes to distinguish them from the reproductive definition of a “species” [17]. Likewise, a lot of ecological writing will define species and speciation according to reproductive isolation, which isn’t necessarily synonymous with reproductive compatibility - reproductively isolated populations may be genetically able to reproduce, but be prevented from doing so or unlikely to do naturally so due to differences in geographical location, habitat or behaviour (think lions and tigers). These are some of the many different “types” of species, with either competing or overlapping definitions of what exactly constitutes a species in each case:
Morphological or typological species (morphospecies)
Phylogenetic species
Evolutionary species
Genetic species
Genalogical concordance species
Reproductive species
Autapomorphic species
Ecological species
Recognition species
Phenetic species
Isolation species
Cohesion species
…You get the idea.
For vertebrates, I think generally the two most used definitions are the biological species concept (BSC) and phylogenetic or cladistic species concept (PSC), which differ in their criteria for what they consider a species [18][19]. PSC, for example, doesn’t include a subspecies category while BSC does - and thus, some organisms that are classified as subspecies of the same species under BSC are either classified as different species or are lumped together as the same species under PSC. For example, grey wolves and domestic dogs. The domestic dog is/was often considered a separate species to the grey wolf, for obvious (morphological/behavioural) reasons - the wolf was Canis lupus, the dog C. familiaris - but since dogs are descended from wolves (a now-extinct lineage of wolves, not modern grey wolves [20], but Canis lupus nonetheless) they are more properly classified as a subspecies, C. l. familiaris. Likewise, having also ultimately descended from wolves, the dingo is officially classified as C. l. dingo, although there is some debate about that - at one stage I remember it being classified as a “subspecies” of domestic dog, Canis lupus familiaris dingo (and it’s still, to my knowledge, widely considered to be descended from domestic dogs [21][22], in which case the second name would be more correct), while still other people classify it as a completely separate species, Canis dingo [23]. You can see why species boundaries and definitions can get murky, especially when the exact evolutionary origins of a particular animal are unknown or hotly contested.
In fact, canids as a whole are kind of a mess when it comes to phylogeny. How many species of wolf there are really depends on who you ask - some populations traditionally classified as subspecies of the grey wolf, for example the Indian wolf (traditionally C. l. pallipes), the Himalayan or Tibetan wolf (traditionally C. l. chanco) and the Eastern wolf (traditionally C. l. lycaon) have been suggested instead to be classified as separate species - Canis indica, Canis himalayensis and Canis lycaon, respectively [24][25]. Likewise, just last year it was discovered that what was thought to be an African subspecies of the golden jackal (Canis aureus) had in fact been misidentified and was instead an undiscovered species of wolf, now the African golden wolf (Canis anthus) [26]. And then there’s also the fact that, despite being called “jackals”, the black-backed and side-striped jackals actually aren’t very closely related to the golden jackal, or indeed to any of the rest of the genus Canis [27]. In fact, going by the cladogram below, you can see that the African wild dog and dhole - both of which are classed in their own, unique genera (Lycaon and Cuon, respectively) - are actually placed closer to wolves, golden jackals and coyotes than black-backed and side-striped jackals are, even though both of the latter species are considered part of genus Canis (the black-backed jackal is C. mesomelas and the side-striped is C. adustus). Many sources also say that these two species differ from the rest of the group in that they have only 74 chromosomes, while wolves, coyotes, golden jackals, African wild dogs and dholes all have 78. This makes the moniker of genus Canis somewhat useless when trying to determine exactly how genetically similar these animals actually are to one another.
[28]
And this isn’t even touching the issue of the “red wolf” (Canis rufus), a critically endangered so-called “species” of wolf closely related to the grey wolf, eastern wolf and coyote, which more recent molecular and genetic analysis has revealed may simply be a wolf/coyote hybrid [29]. Of course these classifications aren’t set in stone, either - new studies and discoveries are constantly uprooting and rewriting our knowledge of phylogenetic and evolutionary relationships among species. Sometimes it’s also pretty much impossible to accurately represent the relationships between similar-but-distinct populations using only the terms “genus” and “species”, which is where alternate concepts like species complex, subgenus and superspecies come in.
Another feature of evolution and speciation that makes classification difficult is what are known as ring species, in which a series of neighbouring populations of organisms may evolve divergently (i.e. undergo allopatric speciation) in such a way that each geographically adjacent or overlapping population can interbreed with the next, but the last population in the “ring” has diverged to the point that it can no longer interbreed with the first (basically, population A can interbreed with population B, B with C and C with D, but D can no longer interbreed with A).
[30][31]
When does the actual split occur, and at what point in the ring can we consider the populations to be different species? We just don’t know. (And in some cases this is considerably more messy and complicated than even the ring species model makes it seem [32]). The point is, though, that there is no definitive, universally agreed-upon cutoff point at which we can say with certainty that two organisms have evolved sufficiently as to become different species, any more than you can definitively say where along a rainbow spectrum of colours red becomes orange or orange becomes yellow. The decision whether to lump or split taxa becomes even more arbitrary in paleontology than it is with extant species [33][34] - when you’re working with an incomplete fossil record and pretty much going entirely on morphological similarities since genetic or molecular analysis often isn’t possible, there isn’t really a way to conclusively determine whether that specimen you found represents a new species, a new genus, or is simply a larger/smaller/juvenile/unfortunate-looking version of an already-described animal. Many specimens now believed to be juveniles of previously-described species were originally believed to be completely new ones - for example, Nanotyrannus is now often (but not universally) agreed to be a juvenile Tyrannosaurus rex [35], and Dracorex and Stygimoloch are considered immature specimens of Pachycephalosaurus [36]. And then there was the whole deal where Brontosaurus didn’t exist for a while and then it did again and it was all very confusing [37].
Obviously, at the end of the day, a zebra is materially different from a dog in the same way that, to get back to the original topic, a penis is materially different from a vagina (actually a bad analogy since homologous reproductive organs are much more similar to each other than taxa that have been separated for millions of years, but anyway). The biological differences and similarities themselves exist, but any attempt to categorise and quantify them will necessarily rely on socially constructed and frequently arbitrary models, definitions and assumptions. That’s basically what science is - a continuous (and frequently wildly inaccurate) attempt to try to make sense of reality. We often attempt to understand or make predictions about reality using mathematical or quantitative models of the situation or by sorting things into sets and categories, which is useful and necessary in many cases but is also often far too simplistic to be taken as any kind of gospel truth regarding the actual nature of reality, because simply put reality doesn’t care for or abide by human-made rules and categories. Essentially, we’re trying to find quantitative ways to represent things that are by nature qualitative, and that’s always going to be arbitrary to some extent. Obviously biological characteristics (whether genetic, sexual/reproductive, etc.) objectively exist and would continue to exist if humans and human culture were to suddenly disappear, and in that sense, things like sex, gender and taxonomic classification can be said to be based in biological reality. But human attempts to define or categorise these characteristics - for example species concepts, the binary model of sex, etc. - are not in themselves biological realities, and are subject to change based on new information. For example, evolutionarily speaking, “reptiles” (as we traditionally understand them) don’t exist [38]. Obviously this doesn’t mean that lizards, tortoises, snakes, crocodiles, non-avian dinosaurs etc. don’t exist or never existed. It simply means that the socially constructed classification of animals into two distinct, mutually exclusive groups called “reptiles” and “birds” is completely arbitrary and not actually the result of any inherent biological reality (in fact the opposite).
I mean I know how crappy the highschool biology syllabus can be @valarie-lynn so I’ll also link you to the Wikipedia page on species and the species problem, and also to some more on sex and how it’s just as complicated and arbitrary as the concept of species (from Actual Biologists™) if you’re interested. I’ll also leave you with a quote from Charles Darwin:
“From these remarks it will be seen that I look at the term species as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other, and that it does not essentially differ from the word variety, which is given to less distinct and more fluctuating forms. The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, and for convenience sake .” [39]
…But you know, what would us simple SJWs know about our own fields of study ¯\_(ツ)_/¯ Thank god we have the Pro-Science, Pro-Logic crowd to save us from the liberal Tumblr “rabbit hole”.
Holy fucking shit
Thank you, my friend, for doing what I was admittedly too lazy to do
I’m so glad you guys took the time to do this! THANK YOU
I suggest that those who are “gender critical” and/or believe in the myth of the “special snowflake” read these posts, because
Synchronous System synthesis; the order of proceedings for creating a synchronous logic system
a rough sketch of where I see glitch art and the overall aesthetic headed.
Interesting tutorial for some basic operations with the normal distribution.
Hysteresis and Schmitt Trigger
- Schmitt trigger is like a comparator in that it has a reference voltage and input signal - the difference is that Schmitt trigger has a high and low reference, by having feedback as a reference voltage via a potential divider - the system triggers when the input goes over V high, and doesn't trigger again until it drops below V low - for inverting, V-=Vi, Vthresh=R2/(R2+R1) *Vo - the difference between high and low threshold is called hysteresis voltage - an offset voltage can be added by adding an offset voltage Vs on the far end of the potential divider of the feedback - if Vs were ground, the threshold would be about 0V - oscillators have a constant repeating output - they have positive feedback because it is in phase with the input signal - thus there is 0 deg phase shift - also gain must be 1 to keep signal constant - at startup an oscillator must first be brought up to the correct amplitude - a wien bridge can be used to bring the gain up to 1 and maintain it -
Opamps in Control and Instrumentation
- integrators are inverting amplifiers with the feedback resistor replaced with a capacitor thus making the gain A = -Zc/Ri - higher frequency means lower gain as the impedance of Zc decreases - a differentiator is an inverting amplifier with the input resistor replaced with a capacitor, with gain Rf/Zc - differentiators and integrators work as high and low pass filters, and differentiators can block dc signals - differentiators are high pass and integrators are low pass - current to voltage converters have a current source instead of an input resistor, and voltage to current converters have a current source as well as the feedback resistor - a voltage comparator with positive feedback can be used to induce hysteresis by removing the virtual ground - this reduces sensitivity to noise from the signal - ふ
Magnetic Circuits
- magnetic fields have flux lines that eminate from north to south - they decrease in intensity s they get further away from the magnetic source - flux density B is a property of magnetic fields that is a measure of the number of flux lines passing through one square unit of space and is measured in teslas T - flux lines or flux linkage Φ have units weibers Wb - B= Φ/A - magnetic circuits can be compared to real circuits, where emf is like mmf (magnetomotive), current is like flux and resistance is the property reluctance R - thus V=IR becomes Fm=ΦR - Fm is also defined by NI, number of coils times current, giving it units ampere-turn At - Reluctance is defined thus by At/Wb - permeability is a property unique to a medium in a magnetic circuit, µ - relative permeability µr is a ratio between material permeability and permeability of free space, µo - there are three levels of magnetization properties in materials; strong ferromagnetic with µr >100, mild paramagnetic µr>=1, and repulsive diamagnetic with µr
- in a symmetrically shaped core, the reluctance of each side is the same provided the depth is uniform - in an asymmetrical shape, the reluctances vary for each side - either case forms a basic series magnetic circuit with reluctance and mmf - reluctance of side ab is Rab= lab/µr*µo*Aab where A is area - gaps in magnetic cores are common and usually small so flux can cross it - flux is lost through fringing effect when crossing a gap, but a small gap makes this loss negligible - air gaps behave as another reluctance as well as the core - parallel magnetic circuits work much the same as basic parallel circuits, with equivalent kerchoff laws for flux and mmf - when finding the reluctance of an air gap, µr=1 and the cross-sectional area of the gap is 5% greater than the physical gap -
Comparators
- accepts 2 analogue inputs and produces a binary output - if vi>Vref, output is 1 and if vi
Signal Conditioning Circuits
- using of opamps to condition signals from sensors so that they have an optimal output for situation - opamps ideally have infinite input impedance, 0 output impedance - the inputs thus become a virtual ground - inverting amplifiers invert phase by 180 and have gain -Rf/Ri - summing amplifiers have multiple inputs and adds the currents of the inputs together - non inverting have gain 1+Rf/Rg - has minimum gain of 1 (unity gain) - buffer amplifiers can make sure that voltage drops across multiple components in series is not attenuated because of the number of components - a differential amplifier has two inputs, vi1 and 2
Temperature Sensors
- thermocouples, thermistors, semiconductors and RTDs are all types of temperature sensor - in thermocouples, V=a(T1-T2) unless T2=0degC, then V=a*T1 - thermocouple outputs are nonlinear - they are made of two materials which have a variable voltage at different temperatures -
Probability
- probability is a ratio of success versus failure in it’s simplest form - the probability of two or more independent events is given by the product of probabilities of the individual attempts - binomial distribution is shown as P(k) = n!/((n-k)!k! *Pk (1-p)^(n-k) where k = 0 to n and n is number of trials and p is probability of 1 success - the Poisson distribution formula is a simplification of the binomial distribution equation, that states Pk~=(µ^k *e^-µ)/k! Where µ =np - Poisson distribution has the added benefit that it only needs an average to solve -
Optical Encoder
- there are 2 kinds of optical encoder: Incremental and Absolute - Incremental: measuring change of angular position, not the actual position - Absolute: measuring the position relative to a reference position at any time - number of pulses of a rotation indicate the number of angular increments in one rotation in incremental encoding - ω(rpm) = f/N *60 where N is number of slots on an optical encoder -
Gain Bandwidth
- amplifier bandwidth ωA = (Ri*ωT)/(Ri+Rf) - gain bandwidth product, AωA=ωT - ωb = ωa
Strain Gauges
- strain gauge changes it’s resistance due to stress - strain ε=Δl/l, which is the deformation due to stress - the elastic modulus, λ=σ/ε where σ is stress - stress σ = F/A - the elastic modulus is called the young’s modulus for linear graphs - possion ratio μ = -(Δd/d)/(Δl/l) shows rate of expansion by rate of compression or transverse by longitudinal strain - the resistance of a material R=ρl/A where ρ is resistivity - ΔR/R = Δl/l = 2Δd/d shows the relative change of resistance - G = 1+2µ is the gauging factor, showing sensitivity - the gauge factor can also be defined by G = (ΔR/R)/ε - strain gauges measure the strain on an object along one plane - tensile or stretch force increase resistance, compressive or squashing force decrease resistance -
Filters
- filters remove noise from useful signals - filters spurious emissions - they also select channels from a range of frequencies, like on radio - are present in crossover units in speaker systems - passive Rc or LC filters can be used for simple applications - active RC filters use opamps particularly for low frequencies - digital filters which use adcs can be used - filters can be band pass, high pass, low pass and band stop - active lo pass filters are an inverting opamp with a capacitor in parallel with the feedback resistor - thus Vo/Vi = -Xc||Rf/Ri - as frequency gets higher Xc tends to 0, thus shorting out Rf and reducing the gain of the amplifier - a high pass filter has a capacitor in parallel with the ground resistor that goes to ground and is non-inverting - gain is found by 1+(Rf/(Rg//Xc)) - at low frequencies Xc gets greater - the Butterworth design equations give attenuation = 10Log[1+(w/wc)^2n]dB where n is the order and wc is the turning point frequency - and n= (log[10^(A/10)-1])/(2log(w/wc)) where A in this case is attenuation - n must be an integer -
Wheatstone Bridge
- made up of 4 resistors in a square with a sensor as one of the resistors - change in resistance of Rsensor gives change in Vo - Vo=Va-Vb, where a and b are points between R1/2 and R3/4 - Va=I1*R4=(Vs/(R1+R4)) *R4 - Vb = I2*R3=(Vs/(R2+R3))*R3 - Vo=[(R4/(R1+R4))-(R3/(R2+R3))] = (R4*R2-R3*R1)/((R1+R4)(R2+R3)) - Vo= 0 when R4*R2=R2+R3 - R1/R4 = R2/R3 - if R1 was a strain gauge, R1 becomes R1+ΔR - if R»ΔR, Vo~=(ΔR/4R)Vs - the sensitivity k= Vo/ΔR = (Vs/4)(1/R) - the sensitivity of the system increases by the factor of number of sensors added - output and input is always linear - sometimes sensors are far from the rest of the circuit, and resistance of cables add resistance to the sensor - this is compensated by using long leads of equal length for that entire half of the bridge, so the resistive differences compensate themselves -